Neurosciences

Video: A Celebration of 50 Years of DNA in Medicine: The Genome and Human Rights

2006-11-13T12:40:00.000Z

Video: A Celebration of 50 Years of DNA in Medicine: Stem Cell Biology and Human Disease

2006-11-13T12:38:00.000Z

Video: "DNA and the Brain" - Dr. James Watson

2006-11-13T12:24:00.000Z

BoTox Receptor

2006-04-30T15:03:00.000Z

From Science 28 April 2006:Vol. 312. no. 5773, pp. 592 - 596

Botulinum neurotoxin type A (BoNT/A) is one of seven neurotoxins produced
by the bacterium Clostridium botulinum. BoNT/A has a long half-life within
cells and is widely used in treatments of wrinkles to chronic pain.
Moreover, BoNT/A can cause paralysis that persists for months. BoNT/A is
known to block neurotransmission by cleaving the protein SNAP-25 in
presynaptic terminals, but it is not clear how this toxin selectively
recognizes and enters neurons. Dong et al. (p. 592, published online 16
March; see the Perspective by Miller) now identify a protein component of
the cellular receptor for BoNT/A as a synaptic vesicle protein, SV2. BoNT/A
enters neurons via recycling synaptic vesicles by binding to SV2 isoforms,
and cells and animals lacking SV2 are resistant to intoxication.

The cellular mRNA expression of GABA and glutamate receptors in spinal motor neurons of SOD1 mice

2005-10-28T19:59:00.000Z

From Journal of the Neurological Sciences Volume 238, Issues 1-2 , 15 November 2005, Pages 25-30

Abstract
ALS is a fatal neurodegenerative disorder characterized by a selective loss of upper motor neurons in the motor cortex and lower motor neurons in the brain stem and spinal cord. About 10% of ALS cases are familial, in 10–20% of these, mutations in the gene coding for superoxide dismutase 1 (SOD1) can be detected. Overexpression of mutated SOD1 in mice created animal models which clinically resemble ALS. Abnormalities in glutamatergic and GABAergic neurotransmission presumably contribute to the selective motor neuron damage in ALS. By in situ hybridization histochemistry (ISH), we investigated the spinal mRNA expression of the GABAA and AMPA type glutamate receptor subunits at different disease stages on spinal cord sections of mutant SOD1 mice and control animals overexpressing wild-type SOD1 aged 40, 80, 120 days and at disease end-stage, i.e. around 140 days) (n = 5, respectively). We detected a slight but statistically significant decrease of the AMPA receptor subunits GluR3 and GluR4 only in end stage disease animals.

Alzheimer Disease And The Blood Brain Barrier: Is Abeta Transport The Key?

2005-10-28T19:52:00.000Z

From Journal of Clinical Investigation

Increased production of the amyloid-beta (Abeta) peptide can lead to Abeta aggregation and buildup in the brain and rare familial forms of early onset Alzheimer disease (AD). Aggregation and buildup of Abeta also appears to contribute to the common, late-onset form of AD, which accounts for 99% of cases, however, there is not strong evidence of Abeta over-production in late-onset AD.

This suggests that there is an age-associated alteration in brain Abeta clearance that contributes to late-onset AD. There is substantial clearance of Abeta from the brain to the blood via the blood-brain-barrier (BBB). Thus, understanding which molecules at the BBB are responsible for Abeta clearance is important. Several transporters have been identified on the BBB that mediate Abeta efflux, however if and how these transporters contribute to Abeta deposition as plaques remain unclear.

In a paper appearing online on October 20 in advance of print publication of the November issue of the Journal of Clinical Investigation, David Holtzman and colleagues from Washington University demonstrate that P-glycoprotein is required for Abeta transport across the BBB and that ablation of this transporter at the BBB increases Abeta deposition in a mouse model of AD.

P-glycoprotein has been a major pharmaceutical target by conferring resistance to many chemotherapy regimens, as well as its role in eliminating a wide variety of medicines via liver uptake. It is possible that chronic treatment with these types of drugs could alter P-glycoprotein function, thereby altering Abeta transport and the risk of developing AD. The findings in this manuscript, in addition to its implications in understanding Abeta transport via the BBB and its therapeutic implications, suggests that researchers should begin to explore whether drugs currently being utilized in humans that affect PgP activity, alter risk for AD.

Gene For B-Cell Development Factor Might Be Involved In Multiple Sclerosis

2005-10-28T19:46:00.000Z

From Biomed Central

A gene involved in B-cell development might play a role in multiple sclerosis. The results of a large study published today in the open access journal BMC Neurology reveal that multiple sclerosis (MS) patients are more likely to carry two specific genetic variations in the Early B-cell factor gene (EBF-1), than healthy individuals.

These variations – or polymorphisms - could play a causative role in MS or be located near other polymorphisms that do play a causative role in the disorder. As such, they could be used as genetic markers for MS.

Alfonso Martinez and colleagues from the Hospital Clinico San Carlos, in Madrid, Spain, who carried out the research, suggest that EBF-1 might be involved in MS due to its role in axonal damage. "Axonal damage is a hallmark for multiple sclerosis," write the authors, and EBF is involved in the expression of proteins essential for axonal pathfinding. How axonal damage occurs in MS, however, is not well understood.

In their study, Martinez et al. compared the occurrence of a polymorphism at a single point in the DNA sequence of the gene EBF-1 – also called a single nucleotide polymorphism (SNP) - in 356 patients diagnosed with MS and 540 healthy individuals acting as controls. Both groups consisted of white Spanish individuals. The authors also compared the variants of a microsatellite – a highly variable, short stretch of non-coding DNA within the EBF-1 gene - in the two groups.

Their results show that patients with MS are more likely to carry the base adenine in the SNP analysed, than controls (p=0.02). In addition, one specific version (allele) of the microsatellite was more frequently found in MS patients than in controls (p=0.08). The authors confirmed this finding with a Transmission Disequilibrium Test: a study of the transmission rate of the allele in 53 patients and their parents, which showed that the allele was more likely to be present in both patients and their parents than other alleles.

Protein Aggregates In Lou Gehrig's Disease Linked To Neuron Death

2005-10-28T19:38:00.000Z

From Northwestern University

French neurologist Jean-Martin Charcot first described amyotrophic lateral sclerosis (ALS) in 1869, but, nearly 140 years later, little is known about the cause of the devastating neurodegenerative disease, and there is no cure.

What is known about Lou Gehrig's disease, as it is commonly called, is that misfolded and damaged proteins clump together in cells to form aggregates and motor neurons die. But scientists have long debated whether or not the protein aggregates actually kill the cells.

Now a research team at Northwestern University, using mammalian neurons and live-cell time-lapse spectroscopy, has become the first to clearly link the presence of the ALS-associated mutant SOD1 protein aggregates with neuronal cell death. This evidence could help explain the disease process and eventually lead to new therapeutics.

In the study, published this month in the Journal of Cell Biology, the scientists looked one at a time at neuronal cells expressing the mutant SOD1 protein and found that in cells where the protein accumulated and aggregates formed, 90 percent of the cells went on to die. (They died between six and 24 hours after aggregates were visually detected.) Cells that did not form aggregates did not die.

The study also provides a new understanding of the structure and composition of the deadly aggregates -- one of the first studies to do so.
"We found that these aggregates are quite peculiar and very different from the aggregates formed in Huntington's disease," said Richard I. Morimoto, Bill A. and Gayle Cook Professor in Biological Sciences, who led the study. Morimoto is an expert in Huntington's disease and on the cellular response to damaged proteins.

"In Huntington's, the aggregate is very dense and impenetrable and binds irreversibly with other molecules in the cell," he said. "In ALS, the aggregates are amorphous, like a sponge. Other proteins can go through the structure and interact with it, which may help explain why mutant SOD1 is so toxic." Morimoto believes this surprising finding indicates that the structure of aggregates associated with other neurodegenerative diseases such as Parkinson's and Alzheimer's will be found to be different as well.

Looking at individual cells in a population, the researchers also found that cells side by side did different things. In cells expressing the same amount of damaged protein, some cells formed aggregates and died and others did not form aggregates and lived. Only a certain subset of at-risk cells went on to lose function and die.

"It would be terrifying if 100 percent of the cells expressing mutant proteins died," said Morimoto. "This means that in many cases the cell's protective machinery suppresses the damaged proteins, keeping the cell healthy. This discovery will be important to scientists looking to develop genetic suppressors and therapeutics."

Morimoto's team focused on SOD1 because it is a form of familial (hereditary) ALS in which a mutation in just one gene and its associated protein has devastating consequences to the cell. (Approximately 10 percent of ALS cases are familial.) This provides experimentalists with a powerful framework. For the other 90 percent the disease is not the result of one mutation but rather a series of many genetic events that debilitate motor neurons. With non-familial forms it is extremely difficult to design hypothesis-based experiments, said Morimoto.

The next question the researchers plan to address is what are the events that lead to cell death once mutant SOD1 protein aggregates form in the cell? This knowledge would help scientists identify small molecules that could halt, arrest or reverse the disease process.

Myelin Suppresses Plasticity In The Mature Brain

2005-10-17T20:39:00.000Z

From Yale University

Yale School of Medicine researchers report in Science this week genetic evidence for the hypothesis that myelination, or formation of a protective sheath around a nerve fiber, consolidates neural circuitry by suppressing plasticity in the mature brain.

This finding has implications for research on restoring mobility to people who have lost motor functions due to spinal cord injury, multiple sclerosis, Lou Gehrig's disease, and other central nervous system disorders.

"The failure of surviving neurons to reestablish functional connection is most obvious after spinal cord injury, but limited nerve cell regeneration and plasticity is central to a range of neurological disorders, including stroke, head trauma, multiple sclerosis, and neurodegenerative disease," said senior author Stephen Strittmatter, professor in the Departments of Neurology and Neurobiology. "Recovery of motor function after serious damage to the mature brain is facilitated by structural and synaptic plasticity."

Strittmatter's laboratory studies how myelin in the central nervous system physically limits axonal growth and regeneration after traumatic and ischemic injury, when blood supply is cut off. A physiological role for the myelin inhibitor pathway has not been defined.

Blocking vision in one eye normally alters ocular dominance in the cortex of the brain only during a critical developmental period, or 20 to 32 days postnatal in mice. Strittmatter's lab, working in collaboration with Nigel Daw, M.D., professor of ophthalmology and neuroscience, and his group, found that mutations in the Nogo-66 receptor (NgR) affect plasticity of ocular dominance. In mice with altered NgR, plasticity during the critical period is normal, but it continues abnormally so that ocular dominance later in development is similar to the plasticity of juvenile stages.

Neural Stem Cells Are Long-Lived

2005-10-17T20:25:00.000Z

From Howard Hughes Medical Institute

New studies in mice have shown that immature stem cells that proliferate to form brain tissues can function for at least a year — most of the life span of a mouse — and give rise to multiple types of neural cells, not just neurons. The discovery may bode well for the use of these neural stem cells to regenerate brain tissue lost to injury or disease.

Alexandra L. Joyner, a Howard Hughes Medical Institute investigator at New York University School of Medicine, and her former postdoctoral fellow, Sohyun Ahn, who is now at the National Institute of Child Health and Human Development, published their findings in the October 6, 2005, issue of the journal Nature. They said the technique they used to trace the fate of stem cells could also be used to understand the roles of stem cells in tissue repair and cancer progression.

Joyner said that previous studies by her lab and others had shown that a regulatory protein called Sonic hedgehog (Shh) orchestrates the activity of an array of genes during development of the brain. Scientists also knew that Shh played a role in promoting the proliferation of neural stem cells. However, Joyner said the precise role of Shh in regulating stem cell self-renewal — the process whereby stem cells divide and maintain an immature state that enables them to continue to generate new cells — was unknown.

In the studies published in Nature, Joyner and Ahn developed genetic techniques that enabled them to label neural stem cells in adult mice that are responding to Shh signaling at any time point so they could study which stem cells respond to Shh.

Other researchers had shown that transient bursts of Shh signaling caused neural stem cells to proliferate and create new neurons. But a central question remained, said Joyner. At issue was whether resting, or quiescent, cells — which are important for long-term function — responded to Shh signaling. Or was the response limited to the actively dividing stem cells with a short life span involved in building new tissue? To test these options, the researchers used a chemical called AraC that selectively kills fast-dividing cells, leaving only quiescent cells.

“This was an important experiment, because by giving AraC, we could kill all the cells that were actively dividing for a week,” said Joyner. “And since the quiescent cells only divide every couple of weeks, they were spared.” The researchers' observations revealed that the quiescent cells did, indeed, respond to Shh signaling, expanding to produce large numbers of neural cells. Even when the researchers gave the mice two doses of AraC separated by a year, the quiescent cells recovered — demonstrating that the cells could still respond to Shh signaling.

That the quiescent stem cells remained capable of self-renewal after a year in both normal and AraC-treated mice was a central finding of the study, said Joyner. “It has been assumed that these cells probably live for some time, but it has never really been known whether they keep dividing, or divide a few times and give out,” she said.

The researchers also found evidence that neural stem cells in vivo responded to Shh signals by giving rise to other neural cell types, including glial cells that support and guide neurons. “An important point is that earlier studies indicating that neural stem cells could give rise to multiple cell types had been done in vitro,” said Joyner. “Before our work, it had never been formally shown that they normally make those different cell types in vivo.” Joyner and Ahn also found that the neural stem cell “niches” — the microenvironments in tissue that support and regulate stem cells — were not formed until late embryonic stages.

Joyner said that the new findings have important clinical implications. “In terms of using neural stem cells for therapeutic purposes and to regenerate tissue, it's important that they can continue to proliferate, and that these stem cells can make different cell types,” she said.

In further studies, the researchers plan to use their technique of marking stem cells and tracing their fate to explore their role in repairing injured brain tissue in animal models. Such studies, she said, could reveal whether growth factors that influence stem cell growth could be used to treat brain injuries. “If these stem cells do produce cells that contribute to injury repair, it is fairly easy to infuse growth factors to coax these stem cells to do more in repairing injury,” she said.

Joyner and her colleagues are already discussing how to apply their genetic fate-mapping techniques to stem cells in the spinal cord and other organs. They are hopeful that since Shh signaling has been implicated in spurring the metastatic progression of cancer, the technique might also be used to explore the role of Shh signaling in tumor progression.

CENTRAL NERVOUS SYSTEM INJURY-INDUCED IMMUNE DEFICIENCY SYNDROME

2005-10-04T17:53:00.000Z

From Nature Reviews Neuroscience 6, 775-786 (2005); doi:10.1038/nrn1765

Abstract

Infections are a leading cause of morbidity and mortality in patients with acute CNS injury. It has recently become clear that CNS injury significantly increases susceptibility to infection by brain-specific mechanisms: CNS injury induces a disturbance of the normally well balanced interplay between the immune system and the CNS. As a result, CNS injury leads to secondary immunodeficiency — CNS injury-induced immunodepression (CIDS) — and infection. CIDS might serve as a model for the study of the mechanisms and mediators of brain control over immunity. More importantly, understanding CIDS will allow us to work on developing effective therapeutic strategies, with which the outcome after CNS damage by a host of diseases could be improved by eliminating a major determinant of poor recovery.

Summary

1. Infections are a leading cause of death in patients suffering from acute CNS injury, such as stroke, traumatic brain injury or spinal cord injury. In affected patients infections impede neurological recovery and increase morbidity as well as mortality.
2. CNS injury induces a disturbance of the normally well balanced interplay between the immune system and the CNS.
3. Brain injury leads to a characteristic immunological phenotype, which is immunodepressant.
4. During systemic inflammation, either as a result of bacterial infection or injury, the CNS mounts a homeostatic, counter-regulatory anti-inflammatory response. However, when triggered by CNS injury, in the absence of systemic inflammation, this response may be detrimental because it shuts down defence mechanisms, rendering the affected organism susceptible to infection. Under these conditions, the immunodepression exerted by the brain is not balanced by general immunostimulation.
5. CNS injury suppresses cell-mediated immune responses via three major pathways of neuroimmunomodulation: the hypothalamo–pituitary–adrenal (HPA) axis, and the sympathetic and parasympathetic nervous systems.
6. We propose that 'neurogenic' mechanisms are involved in the induction of CNS injury-induced immunodepression (CIDS). Damage to sites in the nervous system that control neural–immune interactions (such as the hypothalamus) may lead to anti-inflammatory signals, without initial involvement of immune mechanisms.
7. CIDS is an important, independent contributor to the negative outcomes of patients with brain injury.
8. Recognizing and understanding CIDS could lead to novel treatment strategies to improve outcome in patients with CNS injury.

THE NEURAL BASIS OF HUMAN MORAL COGNITION

2005-10-04T17:49:00.000Z

From Nature Reviews Neuroscience 6, 799-809 (2005); doi:10.1038/nrn1768

Moral cognitive neuroscience is an emerging field of research that focuses on the neural basis of uniquely human forms of social cognition and behaviour. Recent functional imaging and clinical evidence indicates that a remarkably consistent network of brain regions is involved in moral cognition. These findings are fostering new interpretations of social behavioural impairments in patients with brain dysfunction, and require new approaches to enable us to understand the complex links between individuals and society. Here, we propose a cognitive neuroscience view of how cultural and context-dependent knowledge, semantic social knowledge and motivational states can be integrated to explain complex aspects of human moral cognition.

At a time of increasing awareness of the different value systems in multicultural societies and across nations, a deeper understanding of the cognitive and brain mechanisms that guide human behaviour is of general interest. Recent social cognitive neuroscience reviews have emphasized perceptual and emotional abilities that are shared by humans and other animals. However, social neuroscience has largely avoided dealing directly with the complex aspects of human moral cognition, including MORAL EMOTIONS and MORAL VALUES. Here, we review current theoretical accounts of social cognition and put forth a framework designed to overcome the main limitations of earlier accounts. We argue that moral phenomena emerge from the integration of contextual social knowledge, represented as event knowledge in the prefrontal cortex (PFC); social semantic knowledge, stored in the anterior and posterior temporal cortex; and motivational and basic emotional states, which depend on cortical–limbic circuits. Our framework offers new interpretations for social behaviour patterns in healthy individuals and in patients with brain dysfunction, and makes testable predictions for neuropsychological dissociations in moral cognition.

Characterization of the caspase cascade in a cell culture model of SOD1-related familial amyotrophic lateral sclerosis

2005-09-15T20:25:00.000Z

From Neuropathology & Applied NeurobiologyVolume 31 Issue 5 Page 467 - October 2005

There is increasing evidence that apoptosis or a similar programmed cell death pathway is the mechanism of cell death responsible for motor neurone degeneration in amyotrophic lateral sclerosis. Knowledge of the relative importance of different caspases in the cell death process is at present incomplete. In addition, there is little information on the critical point of the death pathway when the process of dying becomes irreversible. In this study, using the well-established NSC34 motor neurone-like cell line stably transfected with empty vector, normal or mutant human Cu-Zn superoxide dismutase (SOD1), we have characterized the activation of the caspase cascade in detail, revealing that the activation of caspases-9, -3 and -8 are important in motor neurone death and that the presence of mutant SOD1 causes increased activation of components of the apoptotic cascade under both basal culture conditions and following oxidative stress induced by serum withdrawal. Activation of the caspases identified in the cellular model has been confirmed in the G93A SOD1 transgenic mice. Furthermore, investigation of the effects of anti-apoptotic neuroprotective agents including specific caspase inhibitors, minocycline and nifedipine, have supported the importance of the mitochondrion-dependent apoptotic pathway in the death process and revealed that the upstream caspase cascade needs to be inhibited if useful neuro-protection is to be achieved.

Sgk1, a cell survival response in neurodegenerative diseases

2005-09-15T20:14:00.000Z

From Molecular and Cellular Neuroscience Volume 30, Issue 2 , October 2005, Pages 249-264

Serum and glucocorticoid-regulated kinase 1 (sgk1) belongs to a family of serine/threonine kinases that is under acute transcriptional control by serum and glucocorticoids. An expanding set of receptors and cellular stress pathways has been shown to enhance sgk1 expression, which is implicated in the regulation of ion channel conductance, cell volume, cell cycle progression, and apoptosis. Recent evidence for the involvement of sgk1 in the early pathogenesis of MPTP-induced Parkinson's disease (PD) prompted us to investigate in more detail its expression and role in animal models of different neurodegenerative diseases.

Here, we show that transcription of sgk1 is increased in several animal models of PD and a transgenic model of amyotrophic lateral sclerosis (ALS). The upregulation of sgk1 strongly correlates with the occurrence of cell death. Furthermore, we provide evidence that the Forkhead transcription factor FKHRL1 and some of the voltage-gated potassium channels are physiological substrates of sgk1 in vivo. Using a small interfering RNA approach to silence sgk1 transcripts in vitro, we give evidence that sgk1 exerts a protective role in oxidative stress situations.

These findings underline a key role for sgk1 in the molecular pathway of cell death, in which sgk1 seems to exert a protective role.

Clues To Parkinson's, Huntington's, And ALS May Be Found In The Walking Patterns Of Affected Mice

2005-09-15T19:34:00.000Z

From Mouse Specifics, Inc. (MSI)

In a published report in the Journal of NeuroEngineering and Rehabilitation, scientists from Harvard Medical School and Mouse Specifics, Inc. (MSI) in Boston have characterized gait dynamics in mice with Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis (ALS). Gait analysis is the process of quantification and interpretation of locomotion. In humans, gait analysis is widely used to quantify patients' movement disorders to provide diagnosis and treatment options. The distinct gait patterns of mice with Parkinson's, Huntington's, and ALS reflect impairment of specific neural pathways involved in the different aspects of the diseases, and provide the basis for testing new therapies.

Gait disturbances are characteristic of patients with Parkinson's disease, Huntington's disease, and ALS. Sudden falls due to unsteady gait are major hazards for the affected patients. Mouse models of these human diseases are essential to their understanding and treatment, yet gait disturbances in diseased mice are seldom described. The scientists from Harvard and MSI used a high speed digital imaging system and a recently patented treadmill with a transparent belt (The DigiGait™ Imaging System) to quantify gait indices in mice treated with toxins to mimic symptoms of either Parkinson's or Huntington's disease, and in mice genetically modified to replicate symptoms of ALS. As in patients, mice with Parkinson's and Huntington's disease exhibited less steady gait than healthy mice, with greater stride-to-stride variability of gait cycle timing. As in patients, upper limb dynamics were more variable in mice with Huntington's disease than in mice with Parkinson's disease. As in patients, gait variability was less disturbed in mice with ALS than in mice with Parkinson's. The altered gait dynamics in the different mouse models indicate that specific neural pathways are involved in the different observed gait pathologies.

"The ability to quantify and distinguish measures of 'walking' in mice with, say, Parkinson's disease and mice with Huntington's disease provides a new opportunity to zero in on the mechanisms underlying their distinct pathologies and characteristics," said Visiting Professor Ivo Amende, Medical University Hannover, Germany, lead author of the study. "Our hope is that gait analysis in mouse models of human movement disorders and neurodegenerative diseases will accelerate the development of drugs to prevent or reverse gait disturbances." The publication can be accessed via the Journal of NeuroEngineering and Rehabilitation website at http://www.jneuroengrehab.com/content/2/1/20 .

Molecule protects against developing Alzheimer's Disease

2005-09-09T20:01:00.000Z

A molecule expressed by nerve cells may protect humans from developing Alzheimer's Disease (AD). In particular, it may reduce the risk of the formation of senile plaques in the brains of patients with AD, as researchers from the Max Delbrück Center for Molecular Medicine (MDC) Berlin-Buch (Germany) and their collaborators in Denmark, Australia, and the USA have been able to demonstrate. The findings by Dr. Olav M. Andersen, Professor Thomas Willnow (both from the MDC) and Dr. Anders Nykjær (University of Aarhus, Denmark) have been published online in PNAS* (doi:10.1073).

A hallmark of Alzheimer disease are protein plaques in the brain which accumulate over many years. They are derived from the amyloid precursor protein (APP) which for unknown reasons is chopped up into smaller fragments, including the amyloid beta peptide, which forms these dangerous plaques. The plaques destroy the patients' nerve cells and lead to dementia, impairing the patients memory, thinking, and behaviour. According to the National Institutes of Health (NIH) more than four million Americans suffer from AD, an incurable disease.

The older one gets, the greater the risk of developing this disease. It is estimated that about half of the individuals over 85 years of age are affected. Professor Willnow and his colleagues were able to demonstrate that the molecule, named sorLa (abb. sorting protein-related receptor), binds to APP in nerve cells and thus prevents its dissection into the amyloid beta peptide. They could also show that genetically modified mice which cannot produce sorLA have increased levels of amyloid beta peptides because APP is destructed at a much higher rate than in healthy animals.

The researchers also looked at the brains of patients who died from AD and compared them with subjects who had not suffered from this disease. Surprisingly, the nerve cells of the AD patients had not produced sorLA, but the nerve cells of the control group had done so. The researchers conclude that in individuals whose brains produce little or no sorLA, the uncontrolled production of amyloid beta peptides likely accelerates onset and progression of neurodegenerative processes, making sorLA an important risk factor for AD.

Ongoing research is directed towards identification of substances that could increase the production of sorLA in the brain of those people that produce insufficient amounts of the molecule. The researchers hope that in the future it will be possible to pharmacologically reduce the formation of these dangerous plaques in the brain by modulating sorLA levels.

The most infectious prion protein particles

2005-09-09T19:49:00.000Z

From Nature Volume 437 Number 7056 pp169-294

The prospects of limiting the spread of transmissible spongiform encephalopathies such as Creutzfeldt−Jakob disease depend in part on identifying the most infectious forms of the prions that carry the diseases. A study of modified scrapie prions shows that clusters of 14 to 28 prion proteins are the most infectious and that clusters of less than six molecules have virtually no infectivity. That could have implications for the treatment of diseases such as Alzheimer's and Parkinson's, characterized by deposition of prion-related amyloid fibrils. It's possible that efforts to alleviate symptoms by destabilizing these large protein aggregates might make things worse by producing smaller, more infective particles. Two other papers in this issue tackle fundamental aspects of the biology of prions and amyloid fibrils. The conversion of the yeast protein Sup35 to its prion form does not need to happen during the synthesis of Sup35 — mature and fully functional molecules can readily join a prion seed. This remodelling of the mature protein is accompanied by the immediate loss of its activity. And a study of a 'designed' amyloid fibril made from ribonuclease A reveals that amyloid containing native-like molecules can retain enzyme activity. This involves a domain swap with the neighbouring protein, and supports the 'zipper-spine model' for -amyloid structures.

Montreal Researchers Probe The Genetic Basis Of Memory

2005-09-02T18:56:00.000Z

From University of Montreal

A group of Montreal researchers has discovered that GCN2, a protein in cells that inhibits the conversion of new information into long-term memory, may be a master regulator of the switch from short-term to long-term memory. Their paper Translational control of hippocampal synaptic plasticity and memory by the eIF2a kinase GCN2, which was published in the August 25th issue of the journal Nature, provides the first genetic evidence that protein synthesis is critical for the regulation of memory formation.

"Not all new information we acquire is stored as long-term memory," says Dr. Costa-Mattioli, a post-doctoral fellow in the laboratory of Dr. Sonenberg, who spearheaded the research project. "For example, it takes most people a number of attempts to learn new things, such as memorizing a passage from a book. The first few times we may initially succeed in memorizing the passage, but the memory may not be stored completely in the brain and we will have to study the passage again."

In a series of experiments, the researchers demonstrated that mice bred without the GCN2 protein acquire new information that does not fade as easily as that of normal mice. This new information is more frequently converted into long-term memory. The researchers concluded that GCN2 may prevent new information from being stored in long-term memory.

Adds Dr.Jean-Claude Lacaille: "The process of switching to long-term memory in the brain requires both the activation of molecules that facilitate memory storage, and the silencing of proteins such as GCN2 that inhibit memory storage."

Although research on humans is still a distant possibility, the scientists believe their discovery may hold promise in the treatment of a variety of illnesses linked to memory. "The discovery of the role of GCN2 in long-term memory may help us develop targeted drugs designed to enhance memory in patients with memory loss due to illnesses such as Alzheimer's disease, where protein synthesis and memory are impaired," concludes Dr. Karim Nader

New Techniques Study The Brain's Chemistry, Neuron By Neuron

2005-09-02T18:47:00.000Z

From University of Illinois at Urbana-Champaign

Researchers at the University of Illinois at Urbana-Champaign have developed tools for studying the chemistry of the brain, neuron by neuron. The analytical techniques can probe the spatial and temporal distribution of biologically important molecules, such as vitamin E, and explore the chemical messengers behind thought, memory and emotion.

"In most organ tissues of the body, adjacent cells do not have significant differences in their chemical contents," said Jonathan Sweedler, a William H. and Janet Lycan Professor of Chemistry and director of the Biotechnology Center at the U. of I. "In the brain, however, chemical differences between neurons are critical for their operation, and the connections between cells are crucial for encoding information or controlling functions."

By dismantling a slice of brain tissue into millions of single cell-size pieces, each of which can be interrogated by mass spectrometric imaging techniques, Sweedler's research group can perform cellular profiling, examine intercellular signaling, map the distribution of new neuropeptides, and follow the release of chemicals in an activity-dependent manner.

Sweedler will describe the techniques and present new results at the 230th American Chemical Society national meeting in Washington, D.C. Using these techniques, Sweedler's group has already discovered multiple novel neuropeptides in a range of neuronal models from mollusks to mammals.

"We work with sea slugs, whose simple brains contain 10,000 neurons; we work with insects possessing one million neurons; and we work with mice having 100 million neurons," said Sweedler, who also is a researcher at the Beckman Institute for Advanced Science and Technology. "Working with these model organisms allows us to examine the functioning of such basic operations as the neuronal control of behavior and long-term memory."
Sweedler's group also developed an approach for looking at the distribution of smaller molecules in brain cells. In a paper accepted for publication in the Journal of the American Chemical Society, and posted on its Web site, they report the subcellular imaging of vitamin E in the sea slug Aplysia californica.

The researchers utilized novel sampling protocols and single cell time-of-flight secondary ion mass spectrometry to identify and map the presence of vitamin E in the membranes of isolated neurons.
"To our surprise, we found that vitamin E was not distributed uniformly in the neuronal membrane," Sweedler said. "Instead, vitamin E was concentrated in the neuron right where it extends to connect with other neurons."
The subcellular localization of vitamin E, which had been impossible to obtain in the past, supports other work that suggested vitamin E performed an active role in transport mechanisms and cellular signaling of neurons.

"Our technique doesn't tell us how or why vitamin E is distributed this way, but suggests that it is under active control and tight regulation," Sweedler said. "Understanding the chemistry that takes place within and between neurons, including small molecules like vitamin E, will no doubt lead to a better understanding of brain function in healthy and diseased brains."

Virginia Tech Engineer Investigates Enzyme Link To Neurological Disease

2005-09-02T14:05:00.000Z

From Virginia Tech

Several neurologically based afflictions, such as Huntington's, Parkinson's, and Alzheimer diseases, have been correlated to a higher than normal presence of a specific type of enzymes, called transglutaminases (TGase) in the human body. TGases, whose function is to catalyze covalent bonds among proteins, are commonly found in several different human tissues.

In the presence of unusually high levels of these enzymes, some proteins tend to form denser clusters than normal in vivo. If the aggregates grow in size, it can lead to a build-up of insoluble plaques that can block neurovascular transport and cause neural cell death.

"If higher TGase concentrations in cerebrospinal fluid and in the brain lead to protein agglomeration, then their inhibition could reduce symptoms, delay the onset of agglomeration, and maintain viable neural cell health extending the quality of life for those afflicted," hypothesizes Brian Love, a professor of materials science and engineering (MSE) at Virginia Tech.

Love, who focuses his research on tissue and cell engineering, and Elena Fernandez Burguera, a post-doctoral research associate, are evaluating specific therapies to fight the abnormally high TGase binding. Based upon the prior work of several others who are conducting clinical trials, Love and Burguera are developing an in vitro model to evaluate the ability of several inhibitors to block protein aggregation by TGases.

Again, based on the work of other scientists, "several compounds show some positive effects," Love says. These include creatine, cystamine hydrochloride, and a few others. "The development of an inhibition protocol may help test the efficacy of other inhibitors as well," the engineer adds.

The Virginia Tech researchers are looking at the enzymatic binding of protein-bound polystyrene particles as models. Groups of particles are dispersed in calcium-rich aqueous solutions containing TGases. Once mixed, the particle binding begins. The bigger agglomerates attempt to settle out of the solution, and Love and Burguera track particle sedimentation.

The tracking method, called Z-axis Translating Laser Light Scattering (ZATLLS), is unique to Virginia Tech and based on key concepts in transport phenomena. It has been used to gauge how other complex fluids, such as paints and sealants, are dispersed. Now Love and Burguera are resolving when protein coated particles are effectively dispersed in vitro and under what conditions they are unstable enough to agglomerate.

They track in situ sedimentation of protein-coated particles exposed to transglutaminase, both in the presence of and without transglutaminase inhibitors. "We can use ZATLLS to resolve whether inhibitors prevent agglomeration of protein coated particles by TGase if the inhibitors lower the particle sedimentation velocity,"

Love says. "Our goal is to find the safest and most effective inhibitors that prevent the agglomeration-based crosslinking found throughout these neurological disorders."

Brain Remembers Familiar Faces When Choosing Potential Mate

2005-09-01T21:10:00.000Z

From University of Liverpool

Scientists at the University of Liverpool have discovered that the human brain favours familiar-looking faces when choosing a potential partner.

The research team found that people find familiar faces more attractive than unfamiliar ones. They also found that the human brain holds separate images of both male and female faces and reacts to them differently depending on how familiar it is with their facial features.

Dr Anthony Little, from the University's School of Biological Sciences, examined whether early visual experience of male and female faces affected later preferences. The research team asked over 200 participants to view a number of human faces that had been digitally manipulated to change their facial characteristics.

Dr Little said: "We found that participants preferred the face that they were most visually familiar with. In one of the tests we showed participants a block of faces with wide-spaced eyes and then asked them to compare these with a face that had narrow-spaced eyes. We found that participants preferred the face with wide-spaced eyes, suggesting that the brain connects familiarity with attraction."

The team also asked participants to judge the same preferred facial features in those of the opposite sex. Participants who were shown male faces with wide-spaced eyes preferred this trait in subsequent male faces but not in female faces.

Dr Little explains: "The research revealed that the sex of the face can be a deciding factor in facial preference. The tests showed for the first time that the brain holds separate visual patterns of male and female faces and responds to them based on their sex as well as their familiarity. We will continue to investigate why this is the case."

"The next step in the research is to find out why the brain makes a link between familiarity and attractiveness. It maybe that visual experience of particular facial features suggests that a person is 'safe' or more 'approachable', both of which are desirable traits."

'Mad Cow' Proteins Successfully Detected In Blood

2005-08-31T21:59:00.000Z

From University of Texas Medical Branch at Galveston

Researchers at the University of Texas Medical Branch at Galveston (UTMB) have found a way to detect in blood the malformed proteins that cause "mad cow disease," the first time such "prions" have been detected biochemically in blood.

The discovery, reported in an article scheduled to appear online in Nature Medicine Aug. 28, is expected to lead to a much more effective detection method for the infectious proteins responsible for brain-destroying disorders, such as bovine spongiform encephalopathy (BSE) in cattle and variant Creutzfeldt-Jakob disease (vCJD) in humans. The blood test would make it much easier to keep BSE-infected beef out of the human food supply, ensure that blood transfusions and organ transplants do not transmit vCJD, and give researchers their first chance to figure out how many people may be incubating the disease.

"The concentration of infectious prion protein in blood is far too small to be detected by the methods used to detect it in the brain, but we know it's still enough to spread the disease," said UTMB neurology professor Claudio Soto, senior author of the Nature Medicine paper. "The key to our success was developing a technique that would amplify the quantity of this protein more than 10 million-fold, raising it to a detectable level."

Soto and the paper's other authors, UTMB assistant professor of neurology Joaquin Castilla and research assistant Paula Saá, applied a method they call protein misfolding cyclic amplification (PMCA) to blood samples taken from 18 prion-infected hamsters that had developed clinical symptoms of prion disease. PMCA uses sound waves to vastly accelerate the process that prions use to convert normal proteins to misshapen infectious forms.

Successive rounds of PMCA led to the discovery of prions in the blood of 16 of the 18 infected hamsters. No prions were found in blood samples that were taken from 12 healthy control hamsters and subjected to the same treatment.

"Since the original publication of a paper on our PMCA technology, we've spent four years optimizing and automating this process to get to this point," Soto said. "The next step, which we're currently working on, will be detecting prions in the blood of animals before they develop clinical symptoms and applying the technology to human blood samples."

Tests for infectious prions in cattle and human blood are badly needed. Because current tests require post-slaughter brain tissue for analysis, in the United States only cattle already showing clinical symptoms of BSE (so-called "downer cows") are tested for the disorder. This is true even though vCJD potentially can be transmitted by animals not yet showing symptoms of the disease. (Only two cases of BSE have been found in American cows so far.) And although British BSE cases have been in decline since 1992, scientists believe the British BSE epidemic of the 1980s could have exposed millions of people in the UK and Europe to infectious prions. The extent of the vCJD epidemic is yet unknown. So far the disease has killed around 180 people worldwide, but numbers could reach thousands or even hundreds of thousands in the coming decades. Prions have also been shown to be transmissible through blood transfusions and organ transplants.

"Who knows what the real situation is in cattle in the United States? And with people, we could be sitting on a time bomb, because the incubation period of this disease in humans can be up to 40 years," Soto said. "That's why a blood test is so important. We need to know the extent of the problem, we need to make sure that beef and the human blood supply are safe, and we need early diagnosis so that when scientists develop a therapy we can intervene before clinical symptoms appear--by then, it's too late."

Study: Brain Structures Contribute To Asthma

2005-08-31T21:42:00.000Z

From University of Wisconsin-Madison

The mere mention of a stressful word like "wheeze" can activate two brain regions in asthmatics during an attack, and this brain activity may be associated with more severe asthma symptoms, according to a study by University of Wisconsin-Madison researchers and collaborators.

The study, which appears in the Proceedings of the National Academy of Sciences (Online, August 29, 2005), reveals a functional link between emotion processing centers in the brain and certain physiological processes relevant to disease.

"While this study was small, it shows how important specific brain circuits can be in modulating inflammation," says Davidson, director of the affective neuroscience laboratory and the Waisman Laboratory for Functional Brain Imaging and Behavior. "The data suggest potential future targets for the development of drugs and behavioral interventions to control asthma and other stress-responsive disorders."

Previous studies and clinical evidence have shown that stress and emotional turmoil adversely affect people with inflammatory diseases like asthma. And signs of inflammation have been shown to affect the brain. But until now, nobody knew exactly what brain circuits were involved in these seemingly intertwined emotional and immune events or how the circuits might influence the severity of an acute asthma response.

Researchers used functional magnetic resonance imaging (fMRI) to scan the brains of six mildly asthmatic people who were asked to inhale ragweed or dust-mite extracts.

Subjects were then shown three types of words: asthma-related (such as "wheeze"), non-asthma negative (such as "loneliness") and neutral (such as "curtains"). Shortly after, researchers measured lung function in the subjects as well as molecular signs of inflammation in their sputum.

The fMRI scans revealed that the asthma-related terms stimulated robust responses in two brain regions--the anterior cingulate cortex and the insula--that were strongly correlated with measures of lung function and inflammation. The other types of words were not strongly associated with lung function or inflammation.

The two brain structures are involved in transmitting information about the physiological condition of the body, such as shortness of breath and pain levels, says Davidson, and they have strong connections with other brain structures essential in processing emotional information.

"In asthmatics, the anterior cingulate cortex and the insula may be hyper-responsive to emotional and physiological signals, like inflammation, which may in turn influence the severity of symptoms," says Davidson.
The researchers suspect that other brain regions may also be involved in the asthma-stress interaction.

Pinpointing The Cause Of A Neurodegenerative Disorder

2005-08-30T18:08:00.000Z

From Howard Hughes Medical Institute

Researchers have discovered how the abnormal repetition of a genetic sequence can have disastrous consequences that lead to the death of neurons that govern balance and motor coordination. The studies bolster the emerging theory that neurodegenerative disorders can be caused by having extra copies of a normal protein, not just a mutated one.

People who are afflicted with the rare neurodegenerative disorder spinocerebellar ataxia type 1 (SCA1) suffer damage to cerebellar Purkinje cells caused by a toxic buildup of the protein Ataxin-1. Researchers knew that SCA1, Huntington's disease and other related disorders arise because of a “genetic stutter,” in which a mutation causes a particular gene sequence to repeat itself. These abnormal genetic repeats cause the resulting proteins to contain unusually long repetitive stretches of the amino acid glutamine.

The new findings, which are published in the August 26, 2005, issue of the journal Cell, provide a molecular explanation for Ataxin-1's assault on cerebellar Purkinje cells.

People with polyglutamine repeat disorders suffer severe degeneration in particular groups of neurons that vary depending on the type of disease. In SCA1, for example, the buildup of Ataxin-1 damages the cerebellar Purkinje cells. As a result of the damage, people with SCA1 lose balance and motor coordination. Loss of muscle control worsens until patients can no longer eat or breathe.

“We had known that the expansion of the glutamine tract within Ataxin-1 probably interfered with normal clearance of Ataxin-1, meaning that it accumulated in cells,” said Zoghbi. She noted that earlier studies yielded hints that the glutamine repeats somehow caused Ataxin-1 function to be altered in a way that damaged or killed Purkinje cells.
“We had been accumulating clues that the glutamine tract expansion is clearly what is important for disease because that's the mutation,” said Zoghbi. “But we also concluded that there was something else beyond the glutamine that's really mediating the toxicity of the protein.” Those conclusions were based, in part, on experiments in mice that showed that increased levels of normal Ataxin-1 can cause the pathology of SCA1.

Turning to the fruit fly, Drosophila, a favorite of geneticists, Zoghbi and her colleagues showed that a particular domain of Ataxin-1 was responsible for causing the flies to lose sensory neurons, but the domain's function remained unknown. Then, a finding by co-author Hugo Bellen, an HHMI investigator at Baylor, set the researchers off in a more fruitful direction. Bellen's team was doing experiments designed to identify proteins that interact with the Drosophila protein, Senseless. His group discovered serendipitously that Senseless interacts with the Ataxin-1 domain and is important for nervous system development.

In further experiments in flies, Zoghbi and her colleagues showed that increases in Ataxin-1 reduced levels of Senseless during peripheral nervous system development, causing developmental abnormalities. Additional experiments demonstrated that enhanced levels of normal and abnormal human Ataxin-1 produced even more serious pathology in the flies.

The researchers then showed that the same interaction and pathological effects occurred in mice — in which Ataxin-1 affected the mammalian version of Senseless, which is called GFi-1. And, they found that mice lacking GFi-1 showed Purkinje cell degeneration, just like humans with SCA1.

“The overall picture we have now is that glutamine expansion causes some aspects of the pathology of SCA1 in part by enhancing the activity of the domain that is outside the glutamine repeat,” said Zoghbi.

The finding offers insight into the molecular mechanisms that cause SCA1, Huntington's disease and other glutamine repeat disorders, said Zoghbi. “It seems to be a recurring theme in neurodegenerative disorders that having extra copies of a normal protein, not just a mutated one, can cause pathology. There have been observations that having extra copies of the normal alpha synuclein protein that causes Parkinson's disease, or of the amyloid precursor protein that causes Alzheimer's disease, can cause pathology,” she said. “So, this raises the question of whether mutations in the genes for these proteins enhance their normal action.

“Importantly, such insights can now guide studies that focus on the normal function and interactions of these proteins and how they might be enhanced by disease-causing mutations," said Zoghbi. "These studies could give better understanding of how the proteins cause disease.”

Loss of ALS2 Function Is Insufficient to Trigger Motor Neuron Degeneration in Knock-Out Mice But Predisposes Neurons to Oxidative Stress

2005-08-30T18:01:00.000Z

From The Journal of Neuroscience, August 17, 2005, 25(33):7567-7574

Amyotrophic lateral sclerosis (ALS), the most common motor neuron disease, is caused by a selective loss of motor neurons in the CNS. Mutations in the ALS2 gene have been linked to one form of autosomal recessive juvenile onset ALS (ALS2). To investigate the pathogenic mechanisms of ALS2, we generated ALS2 knock-out (ALS2-/-) mice. Although ALS2-/- mice lacked obvious developmental abnormalities, they exhibited age-dependent deficits in motor coordination and motor learning. Moreover, ALS2-/- mice showed a higher anxiety response in the open-field and elevated plus-maze tasks. Although they failed to recapitulate clinical or neuropathological phenotypes consistent with motor neuron disease by 20 months of age, ALS2-/- mice or primary cultured neurons derived from these mice were more susceptible to oxidative stress compared with wild-type controls. These observations suggest that loss of ALS2 function is insufficient to cause major motor deficits or motor neuron degeneration in a mouse model but predisposes neurons to oxidative stress.

New Target Found To Fight, Treat Parkinson's

2005-08-25T16:12:00.000Z

From University at Buffalo

Neuroscientists from the University at Buffalo have described for the first time how rotenone, an environmental toxin linked specifically to Parkinson's disease, selectively destroys the neurons that produce dopamine, the neurotransmitter critical to body movement and muscle control.

Microtubules, intracellular highways that transport dopamine to the brain area that controls body movement, are the crucial target, they report.

Damage to microtubules prevents dopamine from reaching the brain's movement center, causing a back-up of the neurotransmitter in the transport system, the researchers found. The backed-up dopamine accumulates in the body of the neuron and breaks down, causing a release of toxic free radicals, which destroy the neuron.
The study appeared in the Aug. 9 issue of the Journal of Biological Chemistry.

"This study shows how an environmental toxin affects the survival of dopamine neurons by targeting microtubules that are critical for the survival of dopamine-producing neurons," said Jian Feng, Ph.D., assistant professor of physiology and biophysics in the UB School of Medicine and Biomedical Sciences and senior author on the study.
"Based on these findings, we have identified several ways to stabilize microtubules against the onslaught of rotenone. These results ultimately may lead to novel therapies for Parkinson's disease."

Feng and colleagues in the Department of Physiology and Biophysics have concentrated their research on the cellular mechanisms of the disease. They are interested specifically in understanding why rotenone destroys neurons that produce dopamine, while sparing neurons that produce other neurotransmitters.

Using cultures of rat neurons, the researches subjected neurons that produce various types of neurotransmitters to agents that mimic the action of rotenone. These results showed that dopaminergic neurons were destroyed while others survived.
They then topped off the treatment by adding the drug taxol, which stabilizes microtubules and prevents their breakdown. Findings showed that by protecting microtubules, the toxic effect of rotenone on dopamine-producing neurons was greatly reduced.

"Based on these findings, we believe that microtubules are a critical target of PD environmental toxins such as rotenone," said Feng. "Since many microtubule-depolymerizing agents are compounds naturally produced in many plants, our research points to the need to examine their possible link to Parkinson's disease. In addition, PD has a higher incidence in rural areas and is associated with pesticides and insecticides frequently used in farming practices."

The research also opens up novel avenues for the development of PD therapies by targeting microtubules, he said. Feng and colleagues in his laboratory are working actively towards this goal.

The Oral Antidiabetic Pioglitazone Protects from Neurodegeneration and ALS-Like Symptoms in Superoxide Dismutase-G93A Transgenic Mice

2005-08-25T15:36:00.000Z

From The Journal of Neuroscience, August 24, 2005, 25(34):7805-7812

Amyotrophic lateral sclerosis (ALS) represents a fatal neurodegenerative disorder characterized by progressive death of the upper and lower motor neurons. Because accompanying inflammation may interact with and promote neurodegeneration, anti-inflammatory treatment strategies are being evaluated. Because peroxisome proliferator-activated receptor (PPAR) agonists act as potent anti-inflammatory drugs, we tested whether superoxide dismutase (SOD1)-G93A transgenic mice, a mouse model of ALS, benefit from oral treatment with the PPAR agonist pioglitazone (Pio). Pio-treated transgenic mice revealed improved muscle strength and body weight, exhibited a delayed disease onset, and survived significantly longer than nontreated SOD1-G93A mice. Quantification of motor neurons of the spinal cord at day 90 revealed complete neuroprotection by Pio, whereas nontreated SOD1-G93A mice had lost 30% of motor neurons. This was paralleled by preservation of the median fiber diameter of the quadriceps muscle, indicating not only morphological but also functional protection of motor neurons by Pio. Activated microglia were significantly reduced at sites of neurodegeneration in Pio-treated SOD1-G93A mice, as were the protein levels of cyclooxygenase 2 and inducible nitric oxide synthase. Interestingly, mRNA levels of the suppressor of cytokine signaling 1 and 3 genes were increased by Pio, whereas both the mRNA and protein levels of endogenous mouse SOD1 and of transgenic human SOD1 remained unaffected.

Identification of Aldolase as a Target Antigen in Alzheimer’s Disease

2005-08-25T15:30:00.000Z

From The Journal of Immunology, 2005, 175: 3439-3445.

Alzheimer’s disease (AD) is the most common human neurodegenerative disease, leading to progressive cognitive decline and eventually death. The prevailing paradigm on the pathogenesis of AD is that abnormally folded proteins accumulate in specific brain areas and lead to neuronal loss via apoptosis. In recent years it has become evident that an inflammatory and possibly autoimmune component exists in AD. Moreover, recent data demonstrate that immunization with amyloid- peptide is therapeutically effective in AD. The nature of CNS Ags that are the target of immune attack in AD is unknown. To identify potential autoantigens in AD, we tested sera IgG Abs of AD patients in immunoblots against brain and other tissue lysates. We identified a 42-kDa band in brain lysates that was detected with >50% of 45 AD sera. The band was identified by mass spectrometry to be aldolase A. Western blotting with aldolase using patient sera demonstrated a band of identical size. The Ab reactivity was verified with ELISAs using aldolase. One of 25 elderly control patients and 3 of 30 multiple sclerosis patients showed similar reactivity (p < color="#000099">These findings reveal an autoimmune component in AD, point at aldolase as a common autoantigen in this disease, and suggest a new target for potential immune modulation.

Tissue Plasminogen Activator Promotes Matrix Metalloproteinase-9 Upregulation After Focal Cerebral Ischemia

2005-08-25T10:19:00.000Z

From Stroke. 2005;36:1954.

Background and Purpose— Thrombolytic therapy with tissue plasminogen activator (tPA) in ischemic stroke is limited by increased risks of cerebral hemorrhage and brain injury. In part, these phenomena may be related to neurovascular proteolysis mediated by matrix metalloproteinases (MMPs). Here, we used a combination of pharmacological and genetic approaches to show that tPA promotes MMP-9 levels in stroke in vivo.

Methods— In the first experiment, spontaneously hypertensive rats were subjected to 3 hours of transient focal cerebral ischemia. The effects of tPA (10 mg/kg IV) on ischemic brain MMP-9 levels were assessed by zymography. In the second experiment, wild-type (WT) and tPA knockout mice were subjected to 2 hours of transient focal cerebral ischemia, and MMP-9 levels and brain edema during reperfusion were assessed. Phenotype rescue was performed by administering tPA to the tPA knockout mice.

Results— In the first experiment, exogenous tPA did not change infarct size but amplified MMP-9 levels in ischemic rat brain at 24 hours. Coinfusion of the plasmin inhibitor tranexamic acid (300 mg/kg) did not ameliorate this effect, suggesting that it was independent of plasmin. In the second experiment, ischemic MMP-9 levels, infarct size, and brain edema in tPA knockouts were significantly lower than WT mice. Administration of exogenous tPA (10 mg/kg IV) did not alter infarction but reinstated the ischemic MMP-9 response back up to WT levels and correspondingly worsened edema.

Conclusions— These data demonstrate that tPA upregulates brain MMP-9 levels in stroke in vivo, and suggest that combination therapies targeting MMPs may improve tPA therapy.

Translation elongation factor 1A is essential for regulation of the actin cytoskeleton and cell morphology

2005-08-24T15:13:00.000Z

From Nature Structural and Molecular Biology, published online: 21 August 2005

The binding of eukaryotic translation elongation factor 1A (eEF1A) to actin is a noncanonical function that may link two distinct cellular processes, cytoskeleton organization and gene expression. Using the yeast Saccharomyces cerevisiae, we have established an in vivo assay that directly identifies specific regions and residues of eEF1A responsible for actin interactions and bundling. Using a unique genetic screen, we isolated a series of eEF1A mutants with reduced actin bundling activity. These mutations alter actin cytoskeleton organization but not translation, indicating that these are separate functions of eEF1A. This demonstrates for the first time a direct consequence of eEF1A on cytoskeletal organization in vivo and the physiological significance of this interaction.

A compensatory subpopulation of motor neurons in a mouse model of amyotrophic lateral sclerosis

2005-08-23T14:32:00.000Z

From J. Comp. Neurol. 490:209-219, 2005.

Abstract
Amyotrophic lateral sclerosis is a fatal paralytic disease that targets motor neurons, leading to motor neuron death and widespread denervation atrophy of muscle. Previous electrophysiological data have shown that some motor axon branches attempt to compensate for loss of innervation, resulting in enlarged axonal arbors. Recent histological assays have shown that during the course of the disease some axonal branches die back. We thus asked whether the two types of behavior, die-back and compensatory growth, occur in different branches of single neurons or, alternatively, whether entire motor units are of one type or the other. We used high-resolution in vivo imaging in the G93A SOD1 mouse model, bred to express transgenic yellow fluorescent protein in all or subsets of motor neurons. Time-lapse imaging showed that degenerative axon branches are easily distinguished from those undergoing compensatory reinnervation, showing fragmentation of terminal branches but sparing of the more proximal axon. Reconstruction of entire motor units showed that some were abnormally large. Surprisingly, these large motor units contained few if any degenerating synapses. Some small motor units, however, no longer possessed any neuromuscular contacts at all, giving the appearance of winter trees. Thus, degenerative versus regenerative changes are largely confined to distinct populations of neurons within the same motor pool. Identification of factors that protect compensatory motor neurons from degenerative changes may provide new targets for therapeutic intervention.

An astrocytic basis of epilepsy

2005-08-22T14:15:00.000Z

From Nature Medicine August 2005 - Vol 11 No 8

Hypersynchronous neuronal firing is a hallmark of epilepsy, but the mechanisms underlying simultaneous activation of multiple neurons remains unknown. Epileptic discharges are in part initiated by a local depolarization shift that drives groups of neurons into synchronous bursting. In an attempt to define the cellular basis for hypersynchronous bursting activity, we studied the occurrence of paroxysmal depolarization shifts after suppressing synaptic activity using tetrodotoxin (TTX) and voltage-gated Ca2+ channel blockers. Here we report that paroxysmal depolarization shifts can be initiated by release of glutamate from extrasynaptic sources or by photolysis of caged Ca2+ in astrocytes. Two-photon imaging of live exposed cortex showed that several antiepileptic agents, including valproate, gabapentin and phenytoin, reduced the ability of astrocytes to transmit Ca2+ signaling. Our results show an unanticipated key role for astrocytes in seizure activity. As such, these findings identify astrocytes as a proximal target for the treatment of epileptic disorders.

Nerve cell breakthrough is world first

2005-08-19T22:26:00.000Z

SCIENTISTS in Edinburgh have created the world's first clutch of nerve stem cells in what could prove to be a major breakthrough in the race to treat diseases such as Parkinson's and Alzheimer's.
The cells were created in Edinburgh by the Institute for Stem Cell Research and the University of Milan. A team led by Professor Austin Smith developed the cells at the Edinburgh University-based institution.

It is a breakthrough because it is the first time that scientists have been able to grow and sustain pure brain cells. Until now, scientists had not been able to sustain the ability of neural stem cells to produce copies of themselves when grown in a dish. By changing the growth conditions for the cells, the Edinburgh and Milan labs have for the first time established pure stem cell divisions.

Researcher Steven Pollard said: "The purity of the cells, and the fact that they do not make tumours, means they should be valuable for studying the potential of transplantation to repair damage."
The long-term aim of the research is that the cells will be used to build replacement neural tissue for Alzheimer's and Parkinson's sufferers.

Alzheimer's disease is a progressive, irreversible brain disorder with no known cause or cure, and Parkinson's a disorder of the nervous system. The most likely immediate use for the artificially-created cells is to test out the effectiveness of new drugs. The scientists also hope that the cells will eventually help them to grow replacement brain tissue. The new technology could also lessen the need for animal testing.

Stem Cell Sciences plc (SCS) is the Edinburgh-based stem cell company which gained the licence to the new technology to derive and grow neural stem cells. Chief executive officer Dr Peter Mountford said: "Being able to grow pure brain cells is an exciting prospect for the company.

"SCS sees new business opportunities in both cell-based drug discovery and cell-based therapies for neurological disorders." The company's chief science officer, Dr Tim Allsopp, added: "The remarkable stability and purity of the cells is something unique in the field of tissue stem cells and a great step forward. "We have already had a number of approaches from pharmaceutical companies interested in using these cells to test and develop new drugs, and are looking forward to working with them to further develop and licence the technology."

Stem cells are "master" cells that can become many kinds of tissue, while nerve stem cells are those which help build the brain and central nervous system.

Worldwide research has been carried out on stem cells taken from adult tissue since the 1960's.

South Korean scientists stunned the medical world when they cloned 30 human embryos and developed them over several days last year.

Previous attempts at creating the nerve cells have produced contaminated samples that have not been scientifically useful.

And the breakthrough comes three months after scientists at Newcastle University announced they had successfully produced a cloned embryo using donated eggs and genetic material from stem cells.
It was the first time a human cloned embryo had been created in Britain.

Campaigners, including pro-life groups, have branded the research as "profoundly unethical" in the past. The creation of cloned babies is banned in the UK, but therapeutic cloning has been legal since 2002.

From Scotsman News

Mitochondrial changes in skeletal muscle in amyotrophic lateral sclerosis and other neurogenic atrophies

2005-08-19T21:56:00.000Z

From Brain 2005 128(8):1870-1876.

Previous findings suggested specific mitochondrial dysfunction in skeletal muscle of patients with amyotrophic lateral sclerosis (ALS). To answer the question of whether the dysfunction is specific, we investigated the histochemical distribution of mitochondrial marker activities, the ratio of mitochondrial (mt) versus nuclear (n) DNA, and the activities of citrate synthase (CS) and respiratory chain enzymes in muscle biopsies of 24 patients with sporadic ALS. The data were compared with those in 23 patients with other neurogenic atrophies (NAs), and 21 healthy controls.

Muscle histology revealed similar signs of focally diminished mitochondrial oxidation activity in muscle fibres in both diseased groups. There was only minimal decline of mt/nDNA ratios in ALS and NA patients in comparison with healthy controls. The specific activities of mitochondrial markers CS and succinate dehydrogenase were significantly increased in both ALS and NA patients. The specific activities of respiratory chain enzymes were not significantly different in all three groups. It is concluded that the histochemical, biochemical and molecular mitochondrial changes in muscle are not specific for ALS, but accompany other NAs as well.

Mutant Cu/Zn Superoxide Dismutase (SOD1) Enzymes Implicated In Lou Gehrig's Disease

2005-08-19T21:23:00.000Z

By American Society for Biochemistry and Molecular Biology, A new study indicates that mutant Cu/Zn superoxide dismutase (SOD1) enzymes that are associated with an inherited form of Lou Gehrig's disease cause the protein to become sticky in tissues. Partial unfolding of the mutant protein can expose hydrophobic residues that may promote abnormal interactions with other proteins or membranes in the cell.Over 5,600 people in the U.S. are diagnosed with amyotrophic lateral sclerosis (ALS) or Lou Gehrig's disease each year. About 30,000 Americans have the disease at any given time, and 10% of cases are inherited.

"Amyotrophic lateral sclerosis is a neurodegenerative disorder in which neurons of the motor pathways in the brain and spinal cord die," explains Dr. Lawrence J. Hayward of the University of Massachusetts Medical School. "It typically strikes during middle age, and although it may start with only mild weakness, the symptoms can spread insidiously over months to impair mobility, speech and swallowing, and ultimately the muscles required for respiration."

Despite the prevalence of ALS, the biological mechanisms that kill the motor neurons in most patients are incompletely understood. However, for a fraction of inherited ALS patients, mutations in the gene for SOD1 cause the disease by creating a toxic enzyme. Evidence suggests that misfolding or partial unfolding of mutant SOD1 proteins in these patients might be key to the toxicity.

Hoping to learn more about how SOD1 contributes to ALS, Dr. Hayward began to study the properties of several ALS-causing SOD1 mutants in research sponsored by the National Institutes of Health and the ALS Association. "Our efforts have focused upon trying to explain how over 100 different mutant forms of SOD1 cause inherited ALS," says Dr. Hayward. "The initial results were puzzling because some mutations had dramatic effects on copper and zinc binding, enzymatic activity, and stability of the protein, but many other mutations seemed to cause only subtle changes in these properties in vitro. Yet all of the mutants were known to be toxic in patients."

As a result of several additional experiments done in his lab and by other groups, Dr. Hayward suspected that the mutant proteins might be more vulnerable than the normal enzyme to specific stresses in tissues. In their Journal of Biological Chemistry paper, Dr. Hayward and his colleagues at the University of Massachusetts Medical School show that when the mutant SOD1 enzymes are exposed to reagents that can disrupt some of the protein's bonds or remove its metal ions, they become much stickier than the normal protein.

"The mutants, but not the normal SOD1, adhere to a hydrophobic or 'greasy' surface, and this property could promote abnormal interactions with other proteins or membranes in the cell," explains Dr. Hayward. "How well different tissues can handle this burden of sticky protein, especially during aging, may be one factor that determines which cell types are most vulnerable in the disease. It was interesting to us that the adherent forms were not restricted to the nervous system in the mouse models but were also seen in other tissues such as heart and skeletal muscle. It is possible that this property could contribute to abnormalities in muscle, while other tissues such as kidney do not accumulate hydrophobic SOD1 despite a high expression level of the mutants."

These results may lead to new treatments for some forms of ALS. For example, if researchers can minimize the hydrophobic exposure or can understand how certain tissues prevent build-up of the sticky forms of SOD1, they might be able to boost defenses in tissues known to be susceptible to mutant SOD1 accumulation.

Ref: J. Biol. Chem. 2005 280: 29771-29779.

Enzyme Action Creates Protein Linked To Alzheimer's Disease

2005-08-19T21:09:00.000Z

From UT Southwestern Medical Center

Researchers at UT Southwestern Medical Center have defined a key step in the production of beta-amyloid, a short protein that is thought to be responsible for the development of Alzheimer's disease. Understanding this step may aid in the discovery of drugs that could help block the disease from developing.

In Alzheimer's disease, too much beta-amyloid is produced by an enzyme that has many other essential roles. As a result, simply blocking the whole enzyme knocks out many of its other functions - which is fatal to the organism.

Using cultured human and mouse cells, as well as test-tube assays, UT Southwestern researchers singled out how just one portion of the enzyme, a protein called nicastrin, is involved in the pathway that produces beta-amyloid, thereby leading to Alzheimer's disease. They hope next to work on ways to specifically block nicastrin. The study appears in the August 12 issue of the journal Cell. (Volume 122, Issue 3 , 12 August 2005, Pages 435-447 )

"The work provides an attractive potential strategy for developing treatment for Alzheimer's disease," said Dr. Gang Yu, assistant professor in the Center for Basic Neuroscience and of cell biology and senior author of the study. The research uncovered an "unprecedented mechanism of biochemistry," Dr. Yu said.

Nicastrin is a large protein that is a component of an enzyme called gamma-secretase, which is lodged in the cell's membrane. When it is at the cell surface, nicastrin sticks out into the area outside the cell. It has been thought to play a key role in the creation of a protein called amyloid-beta - the prime suspect for the damage Alzheimer's does to the brain - but the exact mechanism was unknown.

Dr. Yu and his colleagues found that nicastrin binds to several proteins lodged in the cell's membrane, including one called amyloid precursor protein, or APP. Nicastrin then guides membrane-bound proteins to the active area of gamma-secretase, which then splits the proteins. APP, for example, is chopped into two parts: amyloid-beta, which is then shipped to the outside of the cell, and another part that remains inside. Amyloid-beta forms the plaques seen in brains afflicted with Alzheimer's.

"Actually, it's quite a simple mechanism," Dr. Yu said. "Hopefully, we can screen for compounds that can block this process and find the exact pathways and how it can be regulated in Alzheimer's disease."

Now that nicastrin's function has been ascertained, it opens a way to block just the splitting of APP, leaving all the enzyme's other functions intact. For instance, it may be possible to generate chemical compounds that specifically prevent nicastrin from latching on to APP. If APP doesn't attach to nicastrin, APP remains intact and harmless. Meanwhile, nicastrin would be free to bind all the other essential proteins that it works on.
"We want to find a particular way to block the recognition of APP but not the others," Dr. Yu said.

Gene Loss Accelerates Aging

2005-08-19T21:03:00.000Z

Researchers have discovered that the loss of a gene called p63 accelerates aging in mice. Similar versions of the gene are present in many organisms, including humans. Therefore, the p63 gene is likely to play a fundamental biological role in aging-related processes.

"To study how the p63 gene works, we devised a system for eliminating it from adult mouse tissues. What struck us right away was that these p63 deficient mice were aging prematurely," says Alea Mills of Cold Spring Harbor laboratory, who led the research.

Mice that are born without the p63 gene do not survive. Therefore, Mills had previously conducted extensive studies of mice that are born with only one copy of the gene. Still, these animals die at a young age. So to study p63 function in adults, Mills and her colleagues devised a sophisticated molecular genetic technique that enabled them to eliminate both copies of the gene from particular tissues--including skin and other multi-layered epithelial tissues--after the animals reached maturity.

The effects of premature aging observed in these p63 deficient mice were hair loss, reduced fitness and body weight, progressive curvature of the spine, and a shortened lifespan.

"Aging and cancer are two sides of the same coin. In one case, cells stop dividing and in the other, they can't stop dividing. We suspect that having the right amount of the p63 protein in the right cells at the right time creates a balance that enables organisms to live relatively cancer-free for a reasonably long time," says Mills, who adds that this is the first time the p63 gene has been implicated in aging.

"I first presented these results at a meeting in Tuscany. I don't want to sound flippant, but if you have to grow old somewhere, that's about as good a place as any to do it," says Mills.

The study is published in the September issue of the journal Genes & Development (advance online publication August 17). The other researchers involved in the study were Scott Lowe, Ying Wu, Xuecui Guo, and first author William Keyes of Cold Spring Harbor Laboratory, and Hannes Vogel of Stanford University.

Scientists for the first time have cloned a dog.

2005-08-08T14:55:00.000Z

DENVER, Colorado (AP) -- Scientists for the first time have cloned a dog. But don't count on a better world populated by identical, well-behaved canines just yet.

That's because the dog duplicated by South Korea's cloning pioneer, Hwang Woo-suk, is an Afghan hound, a resplendent supermodel in a world of mutts, but ranked by dog trainers as the least companionable and most indifferent among the hundreds of canine breeds.

The experiment extends the remarkable string of laboratory successes by Hwang, but also re-ignites a fierce ethical and scientific debate about the rapidly advancing technology.
Last year, Hwang's team created the world's first cloned human embryos. In May, they created the first embryonic stem cells that genetically match injured or sick patients.

Researchers nicknamed their cloned pal Snuppy, which is shorthand for "Seoul National University puppy." One of the dog's co-creators, Gerald Schatten of the University of Pittsburgh School of Medicine, describes their creation, now 14 weeks old, as "a frisky, healthy, normal, rambunctious puppy."

Researchers congratulated the Korean team on improving techniques that might someday be medically useful. Others, including the cloner of Dolly the sheep, renewed their demand for a worldwide ban on human reproductive cloning.
"Successful cloning of an increasing number of species confirms the general impression that it would be possible to clone any mammalian species, including humans," said Ian Wilmut, a reproductive biologist at the University of Edinburgh, who produced Dolly nearly a decade ago.

The dog cloning team tried to distance its work from commercial cloning. "This is to advance stem cell science and medicine, not to make dogs by this unnatural method," Schatten said.

On scientific terms, the experiment's success was mixed. More than 1,000 cloned embryos were implanted into surrogate mothers and just three pregnancies resulted. That's a cloning efficiency rate lower than experiments with cloned cats and horses. Details appear in Thursday's issue of the journal Nature.

From CNN
Picture CLICK HERE

The mRNA for EF1A Is Localized in Dendrites and Translated in Response to Treatments That Induce Long-Term Depression

2005-08-05T21:13:00.000Z

The mRNA for Elongation Factor 1 Is Localized in Dendrites and Translated in Response to Treatments That Induce Long-Term Depression

From The Journal of Neuroscience, August 3, 2005, 25(31):7199-7209

There is increasing evidence that long-lasting forms of activity-dependent synaptic plasticity, such as long-term potentiation (LTP) and long-term depression (LTD), require local synthesis of proteins within dendrites. Identifying novel dendritic mRNAs and determining how their distribution and translation is regulated is a high priority. We demonstrate here that the mRNA for the elongation factor 1 (EF1) is present in vivo in the dendrites of neurons that exhibit LTP and LTD, and that its translation is locally regulated. The subcellular distribution of EF1 mRNA differs from any of the dendritic mRNAs that have been described previously. In the hippocampus, the mRNA is highly expressed in cell bodies and is also concentrated in the zone of termination of commissural/associational afferents in the inner molecular layer, suggesting that mRNA localization is in some way related to the distribution of different types of synapses. Nevertheless, the localization of EF1 mRNA is not altered by prolonged periods of synaptic activation that are sufficient to cause a dramatic redistribution of Arc mRNA. Local application of the metabotropic glutamate receptor agonist (R,S)-3,5-dihydroxyphenylglycine (DHPG) led to dramatic increases in immunostaining for EF1 protein in dendrites, and treatment of hippocampal slices with DHPG, which is known to induce LTD, led to increases in EF1 protein levels. Both responses were blocked by the protein synthesis inhibitor anisomycin. In contrast, stimulation of the perforant path using patterns of stimulation that induce LTP caused rapid increases of immunostaining for EF1 protein in the activated dendritic lamina, but these increases were not blocked by anisomycin or rapamycin. The findings suggest that local synthesis of EF1 protein may be important for the synaptic mechanisms that underlie protein synthesis-dependent LTD.

Early nuclear translocation of endonuclease G and subsequent DNA fragmentation after transient focal cerebral ischemia in mice

2005-08-04T14:42:00.000Z

From Neuroscience Letters Volume 386, Issue 1 , 23 September 2005, Pages 23-27

Abstract
We investigated whether the endonuclease G (endoG) translocated from mitochondria to nucleus after transient focal cerebral ischemia (tFCI), thereby contributed to subsequent DNA fragmentation. Adult male mice were subjected to 60 min of focal cerebral ischemia by intraluminal suture blockade of the middle cerebral artery. Western blot analysis for endoG was performed at various time points of tFCI. Nuclear endoG was detected as early as 4 h after tFCI in the ischemic brain, and correspondingly mitochondrial endoG showed a significant reduction at 4 h after reperfusion (p <>. Immunohistochemistry of endoG confirmed that the nuclear translocation of endoG was detected as early as 4 h after tFCI in the middle cerebral artery (MCA) territory of the ischemic brain. Double immunofluorescent staining with endoG and AIF showed that endoG was predominantly colocalized with AIF at 24 h after tFCI. Double staining with endoG immunohistochemistry and TdT-mediated dUTP-biotin nick end labeling showed a spatial relationship between endoG expression and DNA fragmentation at 24 h after tFCI. These data suggest that the early nuclear translocation of endoG occurs and could induce DNA fragmentation in the ischemic brain after tFCI.

Gene Expression In The Aging Brain

2005-08-03T14:48:00.000Z

From Public Library of Science

While medical science and a healthy lifestyle can help increase life expectancy, many aspects of aging and longevity are beyond our control. Published this week in the open-access journal PLoS Biology, Michael Eisen and colleagues shed light on these genetic factors by identifying sets of genes whose expression changes with age in human and chimp brains.

Using results from three microarray data studies performed in old and young humans and chimps in four different regions of the cortex (the brain region responsible for functions such as thinking), the authors found a pattern of age-related changes in the expression of hundreds of genes. Only one non-cortical region, the cerebellum (whose principal functions include movement), showed little change in age-related gene expression. Intriguingly, the set of affected cortical genes was different between humans and chimps. Since humans and chimps diverged about 5 million years ago - these changes have accumulated over a relatively short evolutionary time.

What might account for the difference? One common theory of aging holds that damage is done to DNA and proteins by "free-radicals" (highly reactive molecules produced by the metabolic activity of mitochondria). It predicts that more metabolically active tissues will show greater age-related differential gene expression. The results of this study support this theory since the more metabolically active cortex shows a greater reduction in gene activity.

These results raise questions about age-related gene expression changes, including whether metabolically active non-brain tissues display similar patterns, and whether the divergence between human and chimp patterns was the direct result of selection or an inevitable consequence of some other difference in brain evolution. The patterns seen here provide a starting point for understanding genetic changes in aging, and may reveal targets for treatment of neurodegenerative diseases.

Amphetamines Reverse Parkinson's Disease Symptoms In Mice

2005-08-03T14:35:00.000Z

From Duke University Medical Center

Amphetamines, including the drug popularly known as Ecstasy, can reverse the symptoms of Parkinson's disease in mice with an acute form of the condition, according to new research at Duke University Medical Center. The team reports its findings in the August 2005 issue of Public Library of Science (PLoS) Biology.

The researchers caution that the findings in animals do not suggest Parkinson's disease patients should find relief by taking amphetamines, which are drugs of abuse with many dangerous side effects. The findings rather indicate that drugs with similar chemical attributes might offer useful alternatives to current therapies, the researchers said.

The new mouse model enables the researchers to acutely eliminate dopamine, exposing systems contributing to the disease that may not have been obvious before. In the current study, the researchers treated mice unable to recycle dopamine with a drug that also prevented them from manufacturing the brain messenger. The brains of the mice therefore lack detectable levels of dopamine and the animals exhibit all the symptoms of Parkinson's disease for up to 16 hours. Those symptoms included severely impaired movement, rigidity and tremor. When treated with L-DOPA, the symptoms disappeared as the animals resumed normal movement.

Surprisingly, the researchers reported, treating mice lacking dopamine with high doses of amphetamine derivatives – including methamphetamine and MDMA, otherwise known as Ecstasy – reversed those symptoms. Ecstasy was most effective at counteracting the manifestations of Parkinson's symptoms in the mice, with the beneficial effects becoming more pronounced with increasing dose.

The researchers also report that low doses of amphetamines could, when combined with L-DOPA, potentiate minimally effective doses of L-DOPA in the mice. This could have important considerations in reducing some of the side effects of current therapy.

"Taken together, the findings indicate that Ecstasy can improve movement control independently of dopamine and, most importantly provide evidence that drug activation of other neuronal pathways may be sufficient to restore movement even in the virtual absence of dopamine neurotransmission."

Using Nanoparticles To Repair Brain Cells Damaged By Disease, Trauma Or Stroke

2005-08-01T18:49:00.000Z

Using Nanoparticles, In Vivo Gene Therapy Activates Brain Stem Cells: Technique May Allow Scientists To Repair Brain Cells Damaged By Disease, Trauma Or Stroke

From: University at Buffalo

Using customized nanoparticles that they developed, University at Buffalo scientists have for the first time delivered genes into the brains of living mice with an efficiency that is similar to, or better than, viral vectors and with no observable toxic effect, according to a paper published this week in Proceedings of the National Academy of Sciences.

In addition to delivering therapeutic genes to repair malfunctioning brain cells, the nanoparticles also provide promising models for studying the genetic mechanisms of brain disease.

Viral vectors can be produced only by specialists under rigidly controlled laboratory conditions. By contrast, the nanoparticles developed by the UB team can be synthesized easily in a matter of days by an experienced chemist.

The UB researchers make their nanoparticles from hybrid, organically modified silica (ORMOSIL), the structure and composition of which allow for the development of an extensive library of tailored nanoparticles to target gene therapies for different tissues and cell types. A key advantage of the UB team's nanoparticle is its surface functionality, which allows it to be targeted to specific cells.

This is the first time that a non-viral vector has demonstrated efficacy in vivo at levels comparable to a viral vector. In the future, this technology may make it possible to repair neurological damage caused by disease, trauma or stroke.

Journal: Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0504926102

SCIENTISTS DISCOVER HOW NIPAH VIRUS ENTERS CELLS

2005-08-01T15:10:00.000Z

From: National Institutes of Health

Working independently, two research teams funded by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH), have identified how Nipah and Hendra viruses, closely related viruses first identified in the mid-1990s, gain entry into human and animal cells.

Nipah and Hendra are emerging viruses that cause serious respiratory and neurological disease. People can get these deadly viruses from animals. Beginning in 1994, public health officials have recognized disease outbreaks in Malaysia, Singapore, Bangladesh and Australia. Both viruses use a protein essential to embryonic development to enter cells and begin their often-fatal attack, report researchers at the University of California, Los Angeles (UCLA) and the Uniformed Services University of the Health Sciences (USUHS) in Bethesda, Maryland.

The UCLA team, headed by Benhur Lee, M.D., describes its findings in a "Nature" paper posted online on July 6. The report by the USUHS researchers, led by Christopher Broder, Ph.D., is appearing online the week of July 4 in the "Proceedings of the National Academy of Sciences".

Using different methods, both teams identified a specific cell surface receptor, Ephrin-B2, as the doorway used by Nipah and Hendra viruses to get inside cells. This receptor is found on cells in the central nervous system and those lining blood vessels. It is crucial for the normal development of the nervous system and the growth of blood vessels in human and other animal embryos. Ephrin-B2 is found in humans, horses, pigs, bats and other mammals, which explains the unusually broad range of species susceptible to Nipah and Hendra virus infection.

The team narrowed the search for the Nipah/Hendra receptor by first sifting through the genetic sequences of 55,000 possible receptors using microarray technology as a molecular "sieve."

The scientists compared microarray signals from the 55,000 genetic sequences in one set of Nipah virus-resistant human cells with microarray signals from three sets of human cells that the virus can infect. This enabled the research team to narrow the possible number of receptor proteins to 120 by identifying those present in the virus-susceptible cells but absent in the virus-resistant cells. They winnowed the possibilities further -- to just 21 -- by selecting only those candidate receptors within the molecular weight range they expected. They selected 10 expressed at high levels in the susceptible cell lines and inserted them, one by one, into the cells that resisted Nipah virus to identify the receptor. When they inserted the gene for Ephrin-B2, the previously Nipah-resistant cells admitted the virus.

The UCLA team, with collaborators at the University of Pennsylvania, took a different approach, using tools of advanced molecular biology as well as old-fashioned detective work to identify the Ephrin-B2 receptor. They knew the receptor would be abundant among the type of cells Nipah virus attacks, that is, nerve cells and cells lining blood vessels.

To identify the human cell receptor, they created a bait: the Nipah protein that docks to that unknown receptor was attached to part of a human antibody, like a worm on a fishing hook. When they placed this bait onto cells susceptible to Nipah virus infection, it attached to a protein on the cell surface. When placed on Nipah-resistant cells, however, the antibody did not attach to the cells. The scientists used an instrument that sorts molecules by weight to identify that Ephrin-B2 was the cell receptor protein that bound to the antibody/Nipah protein "fishing pole" they had made.

They wanted to confirm their findings, but since they did not have access to a high-level biosafety laboratory as Dr. Broder's team did, the UCLA researchers engineered a harmless virus with Nipah virus proteins embedded in its coat. The UCLA team found that this artificial construct could infect cells vulnerable to Nipah virus but was unable to infect Nipah virus-resistant cells. They also showed that this engineered virus could infect nerve cells and cells lining blood vessels using Ephrin-B2 as the receptor, in the same way as actual Nipah virus would infect these cells.

Induction of endogenous neural precursors in mouse models of spinal cord injury and disease

2005-08-01T14:40:00.000Z

From: European Journal of NeurologyVolume 12 Issue 8 Page 638 - August 2005

Adult neural precursor cells (NPCs) in the mammalian central nervous system (CNS) have been demonstrated to be responsive to conditions of injury and disease. Here we investigated the response of NPCs in mouse models of spinal cord disease [motor neuron disease (MND)] with and without sciatic nerve axotomy, and spinal cord injury (SCI). We found that neither axotomy, nor MND alone brought about a response by Nestin-positive NPCs. However, the combination of the two resulted in mobilization of NPCs in the spinal cord. We also found that there was an increase in the number of NPCs following SCI which was further enhanced by systemic administration of the neuregulatory cytokine, leukaemia inhibitory factor (LIF). NPCs were demonstrated to differentiate into astrocytes in axotomized MND mice. However, significant differentiation into the various neural cell phenotypes was not demonstrated at 1 or 2 weeks following SCI. These data suggest that factors inherent to injury mechanisms are required for induction of an NPC response in the mammalian spinal cord.

Mutant SOD1 alters the motor neuronal transcriptome: implications for familial ALS

2005-08-01T13:53:00.000Z

From: Brain 2005 128(7):1686-1706

Abstract: Familial amyotrophic lateral sclerosis (FALS) is caused, in 20% of cases, by mutations in the Cu/Zn superoxide dismutase gene (SOD1). Although motor neuron injury occurs through a toxic gain of function, the precise mechanism(s) remains unclear. Using an established NSC34 cellular model for SOD1-associated FALS, we investigated the effects of mutant SOD1 specifically in cells modelling the vulnerable cell population, the motor neurons, without contamination from non-neuronal cells present in CNS. Using gene expression profiling, 268 transcripts were differentially expressed in the presence of mutant human G93A SOD1. Of these, 197 were decreased, demonstrating that the presence of mutant SOD1 leads to a marked degree of transcriptional repression. Amongst these were a group of antioxidant response element (ARE) genes encoding phase II detoxifying enzymes and antioxidant response proteins (so-called ‘programmed cell life’ genes), the expression of which is regulated by the transcription factor NRF2. We provide evidence that dysregulation of Nrf2 and the ARE, coupled with reduced pentose phosphate pathway activity and decreased generation of NADPH, represent significant and hitherto unrecognized components of the toxic gain of function of mutant SOD1. Other genes of interest significantly altered in the presence of mutant SOD1 include several previously implicated in neurodegeneration, as well as genes involved in protein degradation, the immune response, cell death/survival and the heat shock response. Preliminary studies on isolated motor neurons from SOD1-associated motor neuron disease cases suggest key genes are also differently expressed in the human disease.

Textbook Explanation Of mRNA Translation May Need Rethinking

2005-06-30T19:05:00.000Z

Our understanding of how messenger RNAs are translated into proteins is challenged by new research published today in the Open Access journal Journal of Biology. The study suggests that EF-G, the GTPase that facilitates tRNA translocation in bacteria, enters the ribosome bound to a different guanine nucleotide than previously thought – GDP, not GTP. The ribosome itself then seems to act as the guanine-nucleotide exchange factor, not some as-yet-unidentified factor as previously assumed. This finding questions the prevailing model for RNA translocation.

According to the textbook model EF-G provides the energy needed for the translocation phase of translation by bringing GTP into the ribosome where GTP is subsequently hydrolysed into GDP.

Andrei Zavialov, Vasili Hauryliuk and Måns Ehrenberg from Uppsala University in Sweden first performed an important purification step ensuring that their GTP was not contaminated by GDP (and vice versa), as had been the case with previous studies using these purified components. They next measured the affinity of EF-G for GTP and GDP. Their results strongly suggest that EF-G is bound to GDP in the cytoplasm and that it binds to the pre-translocation complex - composed of the ribosome, tRNA and mRNA strand – as a EF-G-GDP complex. The ribosome itself then seems to act as a GTP exchange factor that swaps GDP for GTP, which results in a modification in the structure of the ribosome. This triggers partial translocation of the mRNA, which is completed after GTP hydrolysis. "Our results suggest that the ribosome plays a previously unidentified dual role of both guanine-nucleotide exchange factor and GTPase-activating protein" explain the authors. EF-G then detaches from the ribosome in its GDP-bound form, ready to be used again by another ribosome.

These findings differ radically from all previous models and as such may represent a considerable step forward in our understanding of translocation, a fundamental mechanism in protein synthesis and gene expression. RNA translation is a highly conserved mechanism and these results using a bacterial system are likely to be applicable to higher organisms as well. This should spur more research in the field to confirm or disprove the findings and give us a clearer picture of RNA translation. In particular, the present clarification of the translocation process at the biochemical level may allow a deeper understanding of how relative movements of the ribosomal subunits can accomplish thousands of translocation events without frame-shifting or loss of tRNA-bound nascent protein chains during peptide elongation.

BioMed Central

Molecular Steps Involved In The Creation Of Gene-Silencing MicroRNAs Identified

2005-06-30T18:51:00.000Z

First discovered only a few brief years ago, microRNAs are small, remarkably powerful molecules that appear to play a pivotal role in gene silencing, one of the body's main strategies for regulating its genome. A scant 22 nucleotides in length, miRNAs appear to work by binding to and somehow interfering with messenger RNA, itself responsible for translating genes into proteins.

But how do miRNAs arise? And what can we learn about their biological function from their origins? In a study published last year in Nature, researchers at The Wistar Institute identified a two-protein complex, called the microprocessor complex, which controls the earliest steps in the creation of miRNAs in the cell nucleus.

Now, in a new study published online by Nature today, the Wistar group has identified a three-protein complex that picks up the process in the cell cytoplasm and carries it through to the maturation of the finished miRNAs.

Taken together, the two Nature studies trace the generation of miRNAs from the genes that give rise to long primary RNA molecules through to the mature miRNAs that target messenger RNA. Significantly, the research also shows that the finished miRNAs are associated with a protein called Argonaute 2, known to be involved in inactivating messenger RNA.

"In this study, we were able to link processing of the miRNAs directly through to the molecules responsible for silencing genes," says Ramin Shiekhattar, Ph.D., an associate professor at Wistar and senior author on both Nature studies. "The miRNAs provide specificity for those molecules, which do the actual work of gene silencing."

Intriguingly, the research also links the process of creating miRNAs with aspects of the HIV life cycle and with tumor suppression. The study identifies three proteins that work together in the cytoplasm to create finished miRNAs. Individually, each of the proteins was known previously, but their joint role in producing miRNAs is newly delineated here. Equally as important, however, is the fact that while two of the proteins had been associated with miRNAs in earlier work, the third protein, TRBP, had not been. And TRBP is clearly a protein of interest to scientists.

"TRBP was first observed as a protein that binds to HIV during transcription of the virus," says Shiekhattar. "The tantalizing implication is that the RNA interference pathway may play a significant role in HIV replication. TRBP has also been identified as a tumor suppressor, which suggests still other connections to be explored."

The Wistar Institute

Study Shows How Sleep Improves Memory

2005-06-30T18:31:00.000Z

A good night's sleep triggers changes in the brain that help to improve memory, according to a new study led by researchers at Beth Israel Deaconess Medical Center (BIDMC).

These findings, reported in the June 30, 2005, issue of the journal Neuroscience and currently published on-line, might help to explain why children – infants, in particular – require much more sleep than adults, and also suggest a role for sleep in the rehabilitation of stroke patients and other individuals who have suffered brain injuries.

"In this new research, by using functional magnetic resonance imaging (fMRI), we can actually see which parts of the brain are active and which are inactive while subjects are being tested, enabling us to better understand the role of sleep to memory and learning."

New memories are formed within the brain when a person engages with information to be learned (for example, memorizing a list of words or mastering a piano concerto). However, these memories are initially quite vulnerable; in order to "stick" they must be solidified and improved. This process of "memory consolidation" occurs when connections between brain cells as well as between different brain regions are strengthened, and for many years was believed to develop merely as a passage of time. More recently, however, it has been demonstrated that time spent asleep also plays a key role in preserving memory.

In this new study, twelve healthy, college-aged individuals were taught a sequence of skilled finger movements, similar to playing a piano scale. After a 12- hour period of either wake or sleep, respectively, the subjects were tested on their ability to recall these finger movements while an MRI measured the activity of their brain.

According to Walker, who is also an Assistant Professor of Psychiatry at Harvard Medical School, the MRI results showed that while some areas of the brain were distinctly more active after a period of sleep, other areas were noticeably less active. But together, the changes brought about by sleep resulted in improvements in the subjects' motor skill performance.

"The cerebellum, which functions as one of the brain's motor centers controlling speed and accuracy, was clearly more active when the subjects had had a night of sleep," he explains. At the same time, the MRIs showed reduced activity in the brain's limbic system, the region that controls for emotions, such as stress and anxiety.

"The MRI scans are showing us that brain regions shift dramatically during sleep," says Walker. "When you're asleep, it seems as though you are shifting memory to more efficient storage regions within the brain. Consequently, when you awaken, memory tasks can be performed both more quickly and accurately and with less stress and anxiety."

This new research may explain why children and teenagers need more sleep than adults and, in particular, why infants sleep almost round the clock.

"Sleep appears to play a key role in human development," says Walker. "At 12 months of age, infants are in an almost constant state of motor skill learning, coordinating their limbs and digits in a variety of routines. They have an immense amount of new material to consolidate and, consequently, this intensive period of learning may demand a great deal of sleep."

The new findings may also prove to be important to patients who have suffered brain injuries, for example, stroke patients, who have to re-learn language, limb control, etc.

"Perhaps sleep will prove to be another critical factor in a stroke patient's rehabilitation," he notes, adding that in the future he and his colleagues plan to examine sleep disorders and memory disorders to determine if there is a reciprocal relationship between the two.

Beth Israel Deaconess Medical Center

Exercise and IGF-1 Act Synergistically to Prolong Survival in Experimental ALS

2005-06-16T15:12:00.000Z

NEW YORK (Reuters Health) - In a mouse model of amyotrophic lateral sclerosis (ALS), running on an exercise wheel further boosts the increased survival associated with insulin-like growth factor-1 (IGF-1) gene therapy, investigators report.

Dr. Fred H. Gage, at the Salk Institute for Biological Studies in La Jolla, California, previously showed that IGF-1 treatment using an adeno-associated virus (AAV) vector prolongs survival in transgenic mice that overexpress superoxide dismutase-1 (SOD1), a model of ALS.

For their current report, published in the Annals of Neurology for May, Dr. Gage's group placed SOD1 mice with a running wheel, beginning before symptom onset (age 40 days) or after onset (90 days) and compared outcomes with those of sedentary mice.

Early exposure to the wheel for 2 hours/day increased median survival by 7 days (p < 0.0005) over the median survival of 122.5 days seen in nonrunning animals. Exposure for 6 and 12 hours increased median survival to 163 days and 147 days, respectively.

In a separate set of experiments, the authors showed that AAV-IGF-1 treatment increased median survival compared with controls (148 days survival versus 119 days in untreated mice). Early running without AAV-IGF-1 treatment led to a similar prolongation of survival (to 141 days).

Treatment at day 90 with AAV-IGF-1 along with early running increased survival most of all (83-day increase, to 202 days, p < 0.0001). Postponing wheel exercise to 90 days of age led to a smaller benefit in AAV-IGF-1-treated animals (survival to 156 days).

Whereas nonrunning mice exhibited a 50% decrease in the number of motor neurons in the lumbar spinal cord at 110 days compared with wild-type mice, early running, AAV-IGF-1 treatment or combined treatment was associated with no significant change in motor neuron counts, the investigators report. Both modalities decreased astrogliosis compared with sedentary, nontreated animals.

Early running, but not AAV-IGF-1 treatment, was also associated with significantly increased levels of the antiapoptotic genes Bcl-xL and Bcl-2 in the lumbar spinal cord, in comparison with wild-type animals.

None of the animals showed any significant changes in SOD1 expression, "suggesting that the therapeutic effect of running and/or IGF-1 were acting through signaling pathways versus downregulating mutant SOD1 protein," Dr. Gage's group suggests.

Summing up, the team writes, "we have shown that exercise promotes motor neuron survival, attenuates astrogliosis, improves motor function and extends survival."

They propose that "exercise in conjunction with IGF-1 gene therapy may provide the most efficacious treatment for ALS to date."

Ann Neurol 2005;57:649-655.

RNA Silencing of SOD1 Preserves Strength in Mouse Model of ALS

2005-06-16T14:54:00.000Z

NEW YORK (Reuters Health) - Intramuscular injections of a viral vector encoding short interfering RNA (siRNA) directed against superoxide dismutase (SOD1) delays the loss of grip strength in a mouse model of amyotrophic lateral sclerosis (ALS), investigators report in the May Annals of Neurology.

Mutations in SOD1 cause one form of dominantly inherited ALS in humans, senior investigator Dr. Don W. Cleveland and his colleagues note. Transgenic mice that overexpress mutant SOD1 develop symptoms that resemble ALS in humans.

To test the efficacy of treatment with siRNA, Dr. Cleveland, at the University of California, San Diego, in La Jolla and his team designed an adeno-associated virus (AAV-2) that carried green fluorescent protein (GFP) and siRNA directed against SOD1 or a 2 base-pair missense control. They then injected the lower part of the hind limb on one side of SOD1 mutant mice with one of the two AAV-2 viruses and tested the animals weekly with a grip strength meter.

GFP was found in the spinal cord of all the injected animals, demonstrating retrograde transport of the virus, the authors note, and motor neurons expressing GFP had lower levels of SOD1.

Only the limbs of the mice that were treated with the SOD1-directed siRNA showed "remarkable preservation of grip strength," compared with the non-injected control limb.

"We anticipate that reduction in mutant SOD1 by AAV-2-mediated delivery of siRNA after peripheral injection may be an effective therapy for SOD1 familial ALS patients," Dr. Cleveland and his associates maintain.

Ann Neurol 2005;57:773-776.

Progressive Loss of Motor Neuron Function in Wasted Mice

2005-05-29T11:56:00.000Z

Progressive Loss of Motor Neuron Function in Wasted Mice: Effects of a Spontaneous Null Mutation in the Gene for the eEF1A2 Translation Factor.
JNEN: Journal of Neuropathology & Experimental Neurology. 64(4):295-303, April 2005.
Newbery, Helen J PhD; Gillingwater, Thomas H PhD; Dharmasaroja, Permphan MD; Peters, Josephine PhD; Wharton, Stephen B MBBS, MRCPath; Thomson, Derek MIBiol; Ribchester, Richard R PhD, DSc; Abbott, Catherine M PhD

Abstract: Wasted (wst) is a spontaneous autosomal recessive mutation in which the gene encoding translation factor eEF1A2 is deleted. Homozygous mice show tremors and disturbances of gait shortly after weaning, followed by motor neuron degeneration, paralysis, and death by about 28 days. We have now conducted a more detailed analysis of neuromuscular pathology in these animals. Reactive gliosis was observed at 19 days postnatal in wst/wst cervical spinal cord, showing a rostrocaudal gradient. This was followed a few days later by motor neuron vacuolation and neurofilament accumulation, again with a rostrocaudal progression. Thoracic/abdominal muscles from wst/wst mice aged 17 days showed evidence of progressive denervation of motor endplates, including weak synaptic transmission and retraction of motor nerve terminals. Similar abnormalities appeared in distal, lumbrical muscles from about 25 days of age. We conclude that spontaneous failure of eEF1A2 expression in the wasted mutant first triggers gliosis in spinal cord and retraction of motor nerve terminals in muscle, and then motor neuron pathology and death. The early initiation and rapid progression of motor unit degeneration in wst/wst mice suggest that they should be considered an important and accessible model of early-onset motor neuron degeneration in humans.

Nogo expression in muscle correlates with amyotrophic lateral sclerosis severity

2005-05-29T11:42:00.000Z

Nogo, a protein inhibiting axonal regeneration, exhibits a characteristic isoform-specific pattern of expression in skeletal muscle of transgenic mice and patients with amyotrophic lateral sclerosis. Here, the increased levels of Nogo-A or Nogo-B in muscle biopsies of 15 amyotrophic lateral sclerosis patients significantly correlated with the severity of clinical disability and with the degree of muscle fiber atrophy. Nogo-A immunoreactivity was observed selectively in atrophic slow-twitch type I fibers. These results suggest that Nogo expression in muscle is a marker of amyotrophic lateral sclerosis severity.

From Ann Neurol 2005;57:553-556

Breakthrough In Stem Cell Research

2005-05-29T11:20:00.000Z

In an Australian first, UNSW researchers have developed three clones of cells from existing human embryonic stem cells. The breakthrough could lead to new treatments for diabetes, Parkinson's disease and spinal cord injury.

"This cloning of cells involves a new technique, which is a very accurate way of extracting and then growing a single cell," said UNSW Senior Lecturer Dr Kuldip Sidhu, who is leading the research and is based at the Diabetes Transplant Unit (DTU) at the Prince of Wales Hospital, a major teaching hospital of UNSW. "There has only been one report of cloning of cells from human embryonic stem cells anywhere else in the world – in Israel."

By growing a human stem cell colony from a single cell, researchers are one step closer to deriving a homogenous population of cells of a particular type.

"There are about 230 different cell types in the body. All these cells are derived from three embryonic layers – one which forms the brain and spinal cord, another which forms the guts and liver and a third which forms muscles and bones," he said. "We need to establish a recipe to derive each of these from human embryonic stem cells, so they can be transplanted straight into the affected area of a patient.

"The insulin-producing cells, which are derived from the layer which also forms the gut and liver are the holy grail for diabetes researchers," said Dr Sidhu. "That's because they are destroyed in type-1 diabetes, which affects at least 100,000 people in Australia. So far there is no cure for it.

"Human embryonic stem cell research offers a permanent answer to the problem. It gives the hope that we can produce a pure population of those cells in large numbers and transplant them into the patient."
The researchers are currently in the discovery phase, where they are trying to characterise the three clonal lines they have developed.

"It is too early to say anything about these clonal lines, but one of them is inclined towards the cells which form the guts and liver," said Dr Sidhu.

Dr Sidhu and Professor Bernie Tuch, the Director of DTU have received a grant for US$140,000 for two years from the Juvenile Diabetes Research Foundation (JDRF) in the United States to continue their work.

EXERCISE SLOWS DEVELOPMENT OF ALZHEIMER'S-LIKE BRAIN CHANGES IN MICE

2005-05-29T11:08:00.000Z

Physical activity appears to inhibit Alzheimer's-like brain changes in mice, slowing the development of a key feature of the disease, according to a new study. The research demonstrated that long-term physical activity enhanced the learning ability of mice and decreased the level of plaque-forming beta-amyloid protein fragments -- a hallmark characteristic of Alzheimer's disease (AD) -- in their brains.

Results of this study, conducted by Paul A. Adlard, Ph.D., Carl W. Cotman, Ph.D., and colleagues at the University of California, Irvine, are published in the April 27, 2005, issue of "The Journal of Neuroscience".

Compared to the sedentary animals, mice that had exercised for 5 months on the running wheels had significantly fewer plaques and fewer beta-amyloid fragments (peptides) in the cerebral cortex and hippocampus, approximately by 50 percent. Additional studies, of exercised animals at 10 weeks old, showed that the mechanism underlying this difference began within the first month of exercise.

"From other research, it is known that in the aging human brain, deposits of beta-amyloid normally increase. This
study tells us that development of those deposits can be reduced and possibly eliminated through exercise, at least in this mouse model."

A detailed analysis of chromosomes 2 and 4 has detected the largest "gene deserts" known in the human genome

2005-04-06T21:27:00.000Z

Bethesda, Maryland -- A detailed analysis of chromosomes 2 and 4 has detected the largest "gene deserts" known in the human genome and uncovered more evidence that human chromosome 2 arose from the fusion of two ancestral ape chromosomes, researchers supported by the NHGRI, part of the NIH, reported today.

In a study published in the April 7 issue of the journal "Nature", a multi-institution team, led by Washington University School of Medicine in St Louis, described its analysis of the high quality, reference sequence of chromosomes 2 and 4.

Chromosome 4 has long been of interest to the medical community because it holds the gene for Huntington's disease, polycystic kidney disease, a form of muscular dystrophy and a variety of other inherited disorders. Chromosome 2 is noteworthy for being the second largest human chromosome, trailing only chromosome 1 in size. It is also home to the gene with the longest known, protein-coding sequence -- a 280,000 base pair gene that codes for a muscle protein, called titin, which is 33,000 amino acids long.

The new analysis confirmed the existence of 1,346 protein-coding genes on chromosome 2 and 796 protein-coding genes on chromosome 4.

As part of their examination of chromosome 4, the researchers found what are believed to be the largest "gene deserts" yet discovered in the human genome sequence. These regions of the genome are called gene deserts because they are devoid of any protein-coding genes. However, researchers suspect such regions are important to human biology because they have been conserved throughout the evolution of mammals and birds, and work is now underway to figure out their exact functions.

Humans have 23 pairs of chromosomes -- one less pair than chimpanzees, gorillas, orangutans and other great apes. For more than two decades, researchers have thought human chromosome 2 was produced as the result of the fusion of two mid-sized ape chromosomes and a Seattle group located the fusion site in 2002.

In the latest analysis, researchers searched the chromosome's DNA sequence for the relics of the center (centromere) of the ape chromosome that was inactivated upon fusion with the other ape chromosome. They subsequently identified a 36,000 base pair stretch of DNA sequence that likely marks the precise location of the inactived centromere. That tract is characterized by a type of DNA duplication, known as alpha satellite repeats, that is a hallmark of centromeres. In addition, the tract is flanked by an unusual abundance of another type of DNA duplication, called a segmental
duplication.

"These data raise the possibility of a new tool for studying genome evolution. We may be able to find other chromosomes that have disappeared over the course of time by searching other mammals' DNA for similar patterns of duplication," said Richard K. Wilson, Ph.D., director of the Washington
University School of Medicine's Genome Sequencing Center and senior author of the study.

In another intriguing finding, the researchers identified a mRNA transcript from a gene on chromosome 2 that possibly may produce a protein unique to humans and chimps. Scientists have tentative evidence that the gene may be used to make a protein in the brain and the testes. The team also identified "hypervariable" regions in which genes contain variations that may lead to the production of altered proteins unique to humans. The functions of the altered proteins are not known, and researchers emphasized that their findings still require "cautious evaluation."

In October 2004, the International Human Genome Sequencing Consortium published its scientific description of the finished human genome sequence in "Nature". Detailed annotations and analyses have already been published for chromosomes 5, 6, 7, 9, 10, 13, 14, 16, 19, 20, 21, 22, X and Y.
Publications describing the remaining chromosomes are forthcoming.

The sequence of chromosomes 2 and 4, as well as the rest of the human genome sequence, can be accessed through the following public databases: GenBank (www.ncbi.nih.gov/Genbank) at NIH's National Center for Biotechnology Information (NCBI); the UCSC Genome Browser (www.genome.ucsc.edu) at the University of California at Santa Cruz; the Ensembl Genome Browser
(www.ensembl.org) at the Wellcome Trust Sanger Institute and the EMBL-European Bioinformatics Institute; the DNA Data Bank of Japan (www.ddbj.nig.ac.jp); and EMBL-Bank (www.ebi.ac.uk/embl/index.html) at EMBL's Nucleotide Sequence Database.

Silence The Gene, Save The Cell: RNA Interference As Promising Therapy For ALS

2005-03-24T19:35:00.000Z

Scientists at the Ecole Polytechnique Fédérale de Lausanne (EPFL) in Switzerland have used RNA interference in transgenic mice to silence a mutated gene that causes inherited cases of amytrophic lateral sclerosis (ALS), substantially delaying both the onset and the progression rate of the fatal motor neuron disease. Their results will be published in the April issue of Nature Medicine, and in the journal's advanced online publication March 13.

In addition to silencing the mutated gene that causes ALS, the EPFL researchers were able to simultaneously deliver a normal version of the gene to motor neuron cells using a single delivery mechanism. "This is the first proof of principle in the human form of a disease of the nervous system in which you can silence the gene and at the same time produce another normal form of the protein," notes Patrick Aebischer, EPFL President and a co-author of the study.

ALS is a progressive neurological disease that attacks the motor neurons controlling muscles. Although its victims retain all their mental faculties, they experience gradual paralysis and eventually lose all motor function, becoming unable to speak, swallow or breathe. Known also as Lou Gehrig's disease, from the baseball player who succumbed to it, this harrowing disease has no cure and its pathogenesis is not very well understood.

An estimated 5,000 Americans are diagnosed with ALS every year, and most of these cases are "sporadic", with no identifiable cause. About 5-10% of ALS cases are inherited. Of these, 20% have been linked to any of more than 100 mutations in the gene that expresses the superoxide dismutase enzyme (SOD1).

These SOD1 mutations are "toxic gain-of-function mutations," meaning that the protein expressed by the mutated gene has, in addition to all its normal cellular functions, some additional function that makes it toxic to the cell. "Any mutation to the SOD1 gene is fatal to motor neuron cells," Aebischer notes. Recent research also indicates that mutant SOD1 gene expression in neighboring glial cells is also implicated in motor neuron death.

Lead author Cedric Raoul and colleagues targeted the cause of the disease by using RNA interference to silence the defective gene, preventing it from expressing the SOD1 protein.

RNA interference is part of a complex cellular housekeeping process that protects cells from invading viruses or other genetic threats. It works by interrupting messenger RNA as it transfers the genetic code for a protein from the nucleus to the site in the cell where the protein is synthesized.

To trigger RNA interference and silence a gene, short bits of double-stranded RNA are introduced in the cell, where they bind with matching sections of messenger RNA. The cell identifies the resulting messenger RNA strand as faulty and chops it up. As a result, the genetic blueprint isn't delivered and the protein never gets made.
"Gene silencing is an example of using "molecular scissors" at its most advanced level," Raoul explains.

Raoul and colleagues used RNA interference to reduce levels of mutant SOD1 protein in the spinal cords of transgenic ALS mice (mice bred to express the human SOD1 gene). Short strands of RNA that targeted multiple mutated and normal forms of the human SOD1 gene were delivered in a specially engineered lentivirus. Expression of the SOD1 protein was knocked down in the affected motor neurons and neighboring glial cells, and both the onset and the rate of progression of the disease in the treated mice were substantially reduced. In addition, the mice showed a significant improvement in neuromuscular function.
"This is the first demonstration of therapeutic efficacy in vivo of RNA interference-mediated gene silencing in an ALS model," notes Raoul.

Because the normal form of the SOD1 protein may be necessary for the survival or function of adult human motor neurons, the Swiss researchers designed a gene replacement technology that allows the knock-down of all mutant SOD1 forms while permitting the expression of a normal type SOD1 protein that is resistant to RNA interference-based silencing. Both these effects are expressed long-term via delivery by a single lentiviral vector.

Aebischer is optimistic about the future of gene silencing as a potential therapy, particularly in incurable progressive neurological diseases such as ALS. "I would not be surprised to see, in the next ten years, this technology used for treating diseases of the nervous system, particularly diseases that involve toxic gain-of-function, such as inherited forms of Parkinson's disease or Huntington's disease," notes Aebischer. "But it's important to note that the safety of delivering lentiviral vectors to the nervous system will have to be carefully examined prior to treating patients."

Source: Ecole Polytechnique Fédérale de Lausanne

First Mouse Model For Multiple System Atrophy Points To New Treatment Targets For Brain Diseases

2005-03-24T19:26:00.000Z

A newly developed animal model for Multiple System Atrophy (MSA) – a collection of neurodegenerative disorders once thought to be three separate diseases – sheds new light on this little-studied brain disease, according to research from investigators at the University of Pennsylvania School of Medicine.

Virginia M.-Y. Lee, PhD, Director of Penn's Center for Neurodegenerative Disease Research, and colleagues demonstrated that the mice showed symptoms similar to human MSA. These include an accumulation of a protein called á-synuclein in oligodendrocytes – cells that produce the protective myelin sheath that covers axons. This protein accumulation disables oligodendrocytes, leading to a loss of the sheath on neurons and eventually nerve-cell malfunction and death. The mice also showed slowly progressive problems with their motor skills associated with the nerve-cell damage. Neurons are important in transmitting signals and in maintaining learning and memory.

"The uniqueness of this disease is that, unlike most of the neurodegenerative diseases, which affect neurons primarily and oligodendrocytes secondarily, this is the other way around," says Lee. In fact, there is growing evidence that non-neuronal cells also play a role in amyloid deposits in Alzheimer's disease and amyotrophic lateral sclerosis (ALS) mouse models. Lee and colleagues report their findings in the March 24, 2005 issue of Neuron.

MSA is so named because it affects multiple parts of the nervous system. Initially MSA was given three names, based on the symptoms physicians had observed. However, when they closely examined patients' pathology, the disorders seemed related, based on the á-synuclein proteins in cells. In the clinic, many patients with MSA present with symptoms similar to Parkinson's disease (PD), and MSA has been misdiagnosed as such.

Collectively, MSA now includes three related disorders characterized by their most prominent symptoms: olivopontocerebellar atrophy, which affects balance, coordination, and speech; striatonigral degeneration, the closest to Parkinson's disease because of slow movement and stiff muscles; and Shy-Drager syndrome, which involves altered bowel, bladder, and blood-pressure control. Other general symptoms include dizziness, impaired speech, breathing and swallowing difficulties, and blurred vision. Most patients develop dementia late in the course of the disease, which is usually diagnosed in people over 50.

Currently there is no specific drug to treat the myelin and nerve damage caused by the protein inclusions. Parkinson's disease drugs and others are used to alleviate early symptoms. "With this animal model, we now can plan tests of potential therapies for Multiple System Atrophy as part of our drug discovery program for Parkinson's disease, MSA, and related disorders," says Lee.

Source: University of Pennsylvania Medical Center

Selected examples of best practice in computational biology

2005-03-23T14:41:00.000Z

1. A team of researchers from Case Western Reserve University (Cleveland, Ohio; http://www.csuohio.edu/mims/index.htm) is combining computational modeling with physiological experimentation to understand the relationship between metabolism of single human cells and organ and whole body metabolism. This work is yielding computer models of metabolism in liver, heart and brain that promote evidence-based methods for clinical decision support, including diagnosis and treatment [9].

2. An industrial team at United Devices, Inc. (Austin, Texas; http://ud.com/rescenter/ and http://ud.com/rescenter/files/ds_smallpox.pdf) developed technology for massive computational screening of lead drug compounds for drugs by accessing otherwise unused computer time in a global collaborative network of desktop computers. Recently they reported that this work yielded new compounds against a smallpox protein. This work will bring new drugs into animal and human testing cheaply and quickly, yielding more effective, less expensive drugs (United Devices, Inc. http://www-unix.gridforum.org/7_APM/LSG.htm; www.ud.com/rescenter/files/ds_smallpox.pdf.)

3. A team from the University of Connecticut in Storrs, Connecticut (http://www.cbit.uchc.edu/index.html) formed the National Resource for Cell Analysis and Modeling, a nationally accessible computational environment for modeling cell functions. This environment speeds the pace of research at the cellular level by permitting researchers to readily put experimental biochemical data in the context of a computational model of a cell to understand how individual biochemical reactions give rise to coordinated functions at the pathway and cellular level [10].

4. A team from Johns Hopkins University (http://www.bme.jhu.edu/labs/levchenko) is using Monte Carlo modeling to predict biochemical signaling pathways in heart muscle cells. By using the computer-driven random walk to simulate diffusion of signaling molecules in the cell, it is possible to model cellular behavior in great detail, and thus provide a more detailed view of cell signaling. Cell signaling relates to basic and clinical research [11].

5. A team from Indiana University (http://www.indiana.edu/neurosci/sporns.html and
http://www.indiana.edu/cortex/robots.html) is developing an autonomous computational robot with learning capabilities similar to the human brain. This research is aimed at understanding principles of brain function and also at understanding brain function to build automated intelligent systems and robots that can serve human needs [12].

6. A team based at Massachusetts General Hospital/Harvard Medical School is studying malignant brain tumors as self-organizing and adaptive biosystems. Their Tumor Complexity Modeling Project (TCMP) uses methods from various disciplines, such as tumor biology, bioengineering, materials science, mathematical biology, nonlinear physics as well as computational and complex systems science. The immediate aim of TCMP is to develop novel experimental, computational, mathematical and theoretical tumor models. The ultimate goal is to develop virtual treatment planning devices and strategies for malignant brain tumors (http://btc.mgh.harvard.edu/TumorModeling/)

From Trends in Biotechnology Volume 23, Issue 3 , March 2005, Pages 113-117

The artist as neuroscientist

2005-03-16T20:22:00.000Z

When a flat picture is viewed from different angles, the 3D scene can still be perceived without jarring distortions.

Vuilleumier et al. found that the blurry, fearful face on the right activated the amygdala more than the sharply detailed or unfiltered versions.

The neuroscience of art
Paintings and drawings are a 40,000-year record of experiments in visual neuroscience, exploring how depth and structure can best be conveyed in an artificial medium. Artists are driven by a desire for impact and economy: thousands of years of trial and error have revealed effective techniques that bend the laws of physics without penalty. We can look at their work to find a naive physics that uncovers deep and ancient insights into the workings of our brain. Discrepancies between the real world and the world depicted by artists reveal as much about the brain within us as the artist reveals about the world around us.

From www.nature.com/nature/focus/arts/index.html

Profiles in Science Web site

2005-03-06T23:39:00.000Z

PAPERS OF DNA PIONEER AND NOBEL LAUREATE FRANCIS CRICK
ADDED TO NATIONAL LIBRARY OF MEDICINE'S PROFILES IN SCIENCE
WEB SITE

BETHESDA, MARYLAND - The National Library of Medicine, a
part of the National Institutes of Health, is proud to
present an extensive selection from the papers of one of
the twentieth century's greatest scientists, Francis Crick,
on its Profiles in Science Web site.

This latest collection on Profiles in Science represents a
close collaboration between the National Library of
Medicine and the Wellcome Library for the History and
Understanding of Medicine in London, which holds the Crick
papers. The Crick collection brings to 14 the number of
notable researchers and public health officials whose
personal and professional records are featured on Profiles.
The site is located at <http://www.profiles.nlm.nih.gov>.

The name of Francis Crick (1916-2004) is inextricably
linked to the discovery of the double helix of
deoxyribonucleic acid (DNA) in 1953, considered the most
significant advance in biology since Darwin's theory of
evolution. The insights of Crick, and his collaborator,
James D. Watson, into the structure of DNA and into the
genetic code made possible a new understanding of heredity
at the molecular level.

"Major current advances in science and biotechnology, such
as genetic engineering, the mapping of the human genome,
and genetic fingerprinting, all have their origins in
Crick's inspired work," said Donald A.B. Lindberg, M.D.,
director of the National Library of Medicine. "The double
helix has not only reshaped biology, it has become a
cultural icon, represented in sculpture, visual art,
jewelry, and toys."

New Neurons Born in Adult Rat Cortex

2005-02-05T17:37:00.000Z

NIH News
FOR IMMEDIATE RELEASE
Thursday, February 3, 2005

Recent evidence suggesting that antidepressants may act by
triggering the birth of new neurons in the adult
hippocampus,* the brain's memory hub, has heightened
interest in such adult neurogenesis and raised the
question: Could new neurons also be sprouting up in the
parts of the adult brain involved in the thinking and mood
disturbances of depression and anxiety?

Now, scientists at the National Institute of Health's (NIH)
National Institute of Mental Health (NIMH) have found newly
born neurons that communicate via the chemical messenger
GABA (gamma-aminobutyric acid) in adult rat cortex, seat of
higher order "executive" functions, and in the striatum,
site of habits, reward and motor skill learning. In the
cortex, the new neurons appear to arise from previously
unknown precursor cells native to the area, rather than
from cells migrating in from another area. NIMH's Drs.
Heather Cameron, Alexandre Dayer, and colleagues, report on
their findings in the January 31, 2005 "Journal of Cell
Biology".

Their discovery adds to the scientific debate over adult
neurogenesis, which has potential implications for
understanding a variety of brain disorders, possibly
including Alzheimer's and schizophrenia. While most
researchers agree that new neurons are generated in the
adult hippocampus and olfactory bulb, the existence of
adult neurogenesis in other brain regions remains
controversial.

The NIMH team used many more markers than previous studies
to track newborn neurons as they matured and to identify
the type of neurotransmitters they secreted. The markers
exploited antibody affinities for specific proteins to tag
particular cell types with telltale color codes, visible on
brain slices under fluorescence with a laser-powered
microscope.

The researchers found that the cortex and striatum were
giving birth to new, widely scattered small cells, called
interneurons, that make and secrete GABA, a
neurotransmitter that dampens neuronal activity. The new
interneurons closely resembled those seen in the
hippocampus and olfactory bulb and seemed to arise at
similar rates. Interneurons are thought to play a role in
regulating larger types of neurons that make long-distance
connections between brain regions and predominate in these
areas.

The NIMH team was surprised to find that the new cortex
interneurons appeared to arise from a previously unknown
class of local precursor cells rather than from cells that
migrate into the area from the subventricular zone, where
other neurons - including those seen in the striatum and
olfactory bulb - originate during adulthood. However,
during development, both the cortex and striatum precursors
likely stem from common ancestor cells that somehow retain
their ability to divide and generate new GABA interneurons,
propose the researchers.

"Since antidepressants increase neurogenesis in the adult
hippocampus, they might have similar effects in the cortex,
the region probably responsible for mood dysregulation in
depression," suggested Cameron. "But answers to such
questions about regulation and possible functions of the
new neurons must await results of future studies."

Also participating the project were Kathryn Cleaver and
Thamara Abouantoun of the NIMH Unit on Neuroplasticity. Dr.
Dayer's work was supported by the Swiss National Fund.

DNA molecules used to assemble nanoparticles

2005-02-03T17:04:00.000Z

University of Michigan researchers have developed a faster, more efficient way to produce a wide variety of nanoparticle drug delivery systems, using DNA molecules to bind the particles together.

Nanometer-scaled dendrimers can be assembled in many configurations by using attached lengths of single-stranded DNA molecules, which naturally bind to other DNA strands in a highly specific fashion.
"With this approach, you can target a wide variety of molecules—drugs, contrast agents—to almost any cell," said Dr. James R. Baker Jr., the Ruth Dow Doan Professor of Nanotechnology and director of the Center for Biologic Nanotechnology at U-M.

Nanoparticle complexes can be specifically targeted to cancer cells and are small enough to enter a diseased cell, either killing it from within or sending out a signal to identify it. But making the particles is notoriously difficult and time-consuming.

The nanoparticle system used by Baker's lab is based on dendrimers, star-like synthetic polymers that can carry a vast array of molecules on the ends of their arms. It is possible to build a single dendrimer carrying many different kinds of molecules such as contrast agents and drugs, but the synthesis process is long and difficult, requiring months for each new molecule added to the dendrimer in sequential steps. And the yield of useful particles drops with each successive step of synthesis.

For a paper published Jan. 21 in the journal Chemistry and Biology, U-M Biomedical Engineering graduate student Youngseon Choi built nanoparticle clusters of two different functional dendrimers, one designed for imaging and the other for targeting cancer cells. Each of the dendrimers also carried a single-stranded, non-coding DNA synthesized by Choi.

In a solution of two different kinds of single dendrimers, these dangling lengths of DNA, typically 34-66 bases long, found complementary sequences on other dendrimers and knitted together, forming barbell shaped two-dendrimer complexes with folate on one end and fluorescence on the other end.

Folate receptors are over-expressed on the surface of cancer cells, so these dendrimer clusters would tend to flock to the diseased cells. The other end of the complex carries a fluorescent protein so that the researchers can track their movement.

A series of experiments using cell sorters, 3-D microscopes and other tools verified that these dendrimers hit their targets, were admitted into the cells and gave off their signaling light. The self-assembled dendrimer clusters were shown to be well formed and functional.

"This is the proof-of-concept experiment," Choi said. But now that the assembly system has been worked out, other forms of dendrimer clusters are in the works.

"If you wanted to make a therapeutic that targeted five drugs to five different cells, it would be 25 synthesis steps the traditional way," Baker said. At two to three months per synthesis, and a significant loss of yield for each step, that approach just wouldn't be practical.

Instead, the Baker group will create a library of single-functional dendrimers that can be synthesized in parallel, rather than sequentially, and then linked together in many different combinations with the DNA strands.
"So it's like having a shelf full of Tinker Toys," Baker said.

An array of single-functional dendrimers, such as targets, drugs, and contrast agents, and the ability to link them together quickly and easily in many different ways would enable a clinic to offer 25 different "flavors" of dendrimer with only ten synthesis steps, Baker said.

Baker foresees a nanoparticle cluster in which a single dendrimer carries three single-strands of DNA, each with a sequence specific to the DNA attached to other kinds of dendrimers. Put into solution with these other tinker toys, the molecule would self-assemble into a four-dendrimer complex carrying one drug, one target, and one fluorescent.

The original news release can be found here.

Human stem cells trigger immune attack

2005-02-03T11:40:00.000Z

From http://www.nature.com/news/channels/medicalresearch.html

Most human embryonic stem-cell lines, including those available to federally funded researchers in the United States, may be useless for therapeutic applications. The body's immune defences would probably attack the cells, say US researchers. When embryonic stem cells are added to serum from human blood, antibodies stick to the cells. This suggests the cells are seen as foreign, and that transplanting them into the body would trigger the immune system to reject them. "We've found a serious problem," says Ajit Varki, a cell biologist at the University of California, San Diego. The difficulty arises from the way human embryonic stem cells are grown and maintained in the lab. Scientists grow stem cells in petri dishes containing nutrient broth and other cells. These feed the stem cells, and give them a place to attach themselves. Feeder cells are typically embryonic cells from mice and nutrient broth usually contains animal serum. These mouse cells have a molecule on their surface called N-glycolylneuraminic acid or Neu5Gc. Varki's team had already found that human embryonic stem cells take up Neu5Gc; they now show that humans react against it. Eating red meat and dairy products has sensitized people to the molecule, Varki says. The team reports its latest finding in the February issue of Nature Medicine1.

The current stem-cell lines have little clinical value, but that is "not an issue for pursuing basic research", says James Battey, chairman of the National Institutes of Health's stem-cell task force.

Treatment of motoneuron degeneration by intracerebroventricular delivery of VEGF in a rat model of ALS

2005-01-25T16:43:00.000Z

Nature Neuroscience January 2005 - Vol 8 No 1

Neurotrophin treatment has so far failed to prolong the survival of individuals affected with amyotrophic lateral sclerosis (ALS), an incurable motoneuron degenerative disorder. Here we show that intracerebroventricular (i.c.v.) delivery of recombinant vascular endothelial growth factor (Vegf) in a SOD1 G93A rat model of ALS delays onset of paralysis by 17 d, improves motor performance and prolongs survival by 22 d, representing the largest effects in animal models of ALS achieved by protein delivery. By protecting cervical motoneurons, i.c.v. delivery of Vegf is particularly effective in rats with the most severe form of ALS with forelimb onset. Vegf has direct neuroprotective effects on motoneurons in vivo, because neuronal expression of a transgene expressing the Vegf receptor prolongs the survival of SOD1 G93A mice. On i.c.v. delivery, Vegf is anterogradely transported and preserves neuromuscular junctions in SOD1 G93A rats. Our findings in preclinical rodent models of ALS may have implications for treatment of neurodegenerative disease in general.

Related article:
VEGF: multitasking in ALS
Nature Neuroscience News and Views (01 Jan 2005)

CSX/NKX2.5 modulates differentiation of skeletal myoblasts and promotes differentiation into neuronal cells

2005-01-24T17:33:00.000Z

J. Biol. Chem (Papers In Press, published online ahead of print January 13, 2005)

CSX/NKX2.5 modulates differentiation of skeletal myoblasts and promotes differentiation into neuronal cells in vitro

ABSTRACT:
CSX/Nkx2.5 transcription factor plays a pivotal role in cardiac development, however, its role in development and differentiation of other organs has not been investigated. In this study, we used C2C12 myoblasts and human fetal primary myoblasts to investigate the function of Nkx2.5 in skeletal myogenesis. The expression levels of Nkx2.5 decreased as C2C12 myoblasts elongated and fused to form myotubes. Expression of human NKX2.5 in C2C12 myoblasts inhibited myocyte differentiation and myotube formation, and up-regulated Gata4 and Tbx5 expression. Expression of NKX2.5 in terminally differentiated C2C12 myotubes resulted in a change in morphology and breakdown into smaller myotubes. Furthermore, over-expression of NKX2.5 in C2C12 cells and primary cultures of human fetal myoblasts led to differentiation of myoblasts into neuron-like cells and expression of neuronal markers. This study sheds light on previously unknown non-cardiac functions of Nkx2.5 transcription factor.

Quantum dots and other nanoparticles

2005-01-21T15:05:00.000Z

Nanocrystals (quantum dots) and other nanoparticles (gold colloids, magnetic bars, nanobars, dendrimers and nanoshells) have been receiving a lot of attention recently with their unique properties for potential use in drug discovery, bioengineering and therapeutics.

Quantum dots (QDs) are semiconducting materials that are, in general, synthesized with II-VI or III-V column elements of the periodic table. They are neither atomic nor bulk semiconductors. Their properties originate from their physical size, which ranges from 10–100 Å in radius. Due to their bright fluorescence, narrow emission, broad UV excitation and high photostability [[4 and 5]], QDs have been adopted for in vitro bioimaging by many researchers as an alternative to organic based fluorophores [[4, 6, 7, 8, 9 and 10]]. Most recently, in vivo applications of these QDs have also been reported [[11, 12 and 13]].

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microRNAs may control more than one-third of human genes

2005-01-20T16:21:00.000Z

More than one-third of human genes could be controlled by minuscule molecules called microRNAs. This claim by US scientists suggests that the molecules, which were first discovered in 2000, could play a role in almost every process from cell birth to cell death, and that they might even be useful in treating human disease.

MicroRNAs are rather like fragments of DNA, and are made up of around 22 chemical 'letters'. They act as controls by effectively blocking a gene from doing its normal job in a cell.

When a gene is switched on, its sequence is converted into messenger RNA, which carries the information to make a protein. MicroRNAs recognize and bind to particular messenger RNAs and stop them from making proteins.

Scientists know that human cells are swimming in microRNAs, but have been unsure how many of our 22,000 or so human genes they control. They might affect only a few hundred genes, say some, or as many as several thousand.

Full news at Nature.com

Neurons Reach Out and Touch Everyone

2005-01-19T15:22:00.000Z

3D synaptic contact_Brain
(Picture and full text from PNAS January 18, 2005 vol. 102 no. 3 880-885 )
Using multi-neuron whole-cell recordings and confocal microscopy images of rat somatosensory cortex, the authors found that the pyramidal neurons in a region called cortical layer V send out axons that touch all neighboring dendrites; they describe this process as "all-to-all" geometry. The functional synapses were characterized by the presence of synaptic boutons. These findings suggest that, within the neocortex, all possible connections already exist, though most are nonfunctional. These data provide the first direct experimental evidence for a tabula rasa-like structural matrix between neocortical pyramidal neurons and suggests that pre- and postsynaptic interactions shape the conversion between touches and synapses to form specific functional microcircuits. The authors suggest that this architecture provides the neocortex with its immense capacity for plasticity without requiring the wasteful process of axonal and dendritic remodeling.

Biotechnology, the brain and the future

2005-01-17T11:36:00.000Z

Trends in Biotechnology Volume 23, Issue 1 , January 2005, Pages 34-41
Here is another interesting review.

Several new approaches to illness, inspired by recent advances in molecular biology, informatics and nanoscience, are readily applicable to diseases of the central nervous system. Novel classes of drugs will widen the scope of therapeutic action beyond merely modifying transmitter function and stem cell and gene therapies could offer an even more selective mode of targeting. Further into the future, nanotechnology has the potential to allow development of new medicines and novel access routes via miniaturized monitoring and screening devices: these systems, together with increasing use of carbon–silicon interfacing, will challenge traditional neuropharmacology. As the 21st century unfolds, the structure and function of the brain, which is incomparable with any other organ, will present unique technological and ethical questions.

Nanotechnology and Neuroscience

2005-01-12T14:53:00.000Z

Self-Propagating, Molecular-Level Polymorphism in Alzheimer's ß-Amyloid Fibrils
Science, Vol 307, Issue 5707, 262-265 , 14 January 2005
ABSTRACT: Amyloid fibrils commonly exhibit multiple distinct morphologies in electron microscope and atomic force microscope images, often within a single image field. By using electron microscopy and solid-state nuclear magnetic resonance measurements on fibrils formed by the 40-residue ß-amyloid peptide of Alzheimer's disease (Aß1–40), we show that different fibril morphologies have different underlying molecular structures, that the predominant structure can be controlled by subtle variations in fibril growth conditions, and that both morphology and molecular structure are self-propagating when fibrils grow from preformed seeds. Different Aß1–40 fibril morphologies also have significantly different toxicities in neuronal cell cultures. These results have implications for the mechanism of amyloid formation, the phenomenon of strains in prion diseases, the role of amyloid fibrils in amyloid diseases, and the development of amyloid-based nano-materials.

Nanoscale velocity–drag force relationship in thin liquid layers measured by atomic force microscopy
Applied Physics Letters -- October 25, 2004 -- Volume 85, Issue 17, pp. 3881-3883
ABSTRACT: The relationship between velocity and drag force acting on a nanoprobe has been measured with an atomic force microscope (AFM). A special nanoprobe "whisker" was partially submerged in thin layers of glycerol–water mixtures and moved by using the AFM in scanning mode. The viscous drag force-caused torsion of the cantilever probe was recorded as a function of scanning speed and submersion depth. A linear drag force–velocity function was determined for cylindrical bodies with diameters of the order of 50 nm. The experimental results were supported by calculations for the torsional force exerted on an AFM probe dragged through a viscous medium. The viscosity was calculated for each experiment assuming no slip conditions and was in agreement with the macroscopically determined values. With some refinements, this offers a possible means of determining viscosity in thin liquid layers.

Integrated multiple patch-clamp array chip via lateral cell trapping junctions
Applied Physics Letters -- March 15, 2004 -- Volume 84, Issue 11, pp. 1973-1975
ABSTRACT: We present an integrated multiple patch-clamp array chip by utilizing lateral cell trapping junctions. The intersectional design of a microfluidic network provides multiple cell addressing and manipulation sites for efficient electrophysiological measurements at a number of patch sites. The patch pores consist of openings in the sidewall of a main fluidic channel, and a membrane patch is drawn into a smaller horizontal channel. This device geometry not only minimizes capacitive coupling between the cell reservoir and the patch channel, but also allows simultaneous optical and electrical measurements of ion channel proteins. Evidence of the hydrodynamic placement of mammalian cells at the patch sites as well as measurements of patch sealing resistance is presented. Device fabrication is based on micromolding of polydimethylsiloxane, thus allowing inexpensive mass production of disposable high-throughput biochips.

Nanotubular Highways for Intercellular Organelle Transport
Science -- February 13, 2004 -- Volume 303, Issue 5660, pp. 1007-1010
ABSTRACT: Cell-to-cell communication is a crucial prerequisite for the development and maintenance of multicellular organisms. To date, diverse mechanisms of intercellular exchange of information have been documented, including chemical synapses, gap junctions, and plasmodesmata. Here, we describe highly sensitive nanotubular structures formed de novo between cells that create complex networks. These structures facilitate the selective transfer of membrane vesicles and organelles but seem to impede the flow of small molecules. Accordingly, we propose a novel biological principle of cell-to-cell interaction based on membrane continuity and intercellular transfer of organelles.

Nanotechnology for neuronal ion channels
Journal of Neurology Neurosurgery and Psychiatry 2003;74:1466-1475
ABSTRACT: Ion channels provide the basis for the regulation of electrical excitability in the central and peripheral nervous systems. This review deals with the techniques that make the study of structure and function of single channel molecules in living cells possible. These are the patch clamp technique, which was derived from the conventional voltage clamp method and is currently being developed for automated and high throughput measurements; and fluorescence and nano-techniques, which were originally applied to non-biological surfaces and are only recently being used to study cell membranes and their proteins, especially in combination with the patch clamp technique. The characterisation of the membrane channels by techniques that resolve their morphological and physical properties and dynamics in space and time in the nano range is termed nanoscopy.

Botulinum toxin type B micromechanosensor
PNAS November 11, 2003 vol. 100 no. 23 13621-13625
ABSTRACT: Botulinum neurotoxin (BoNT) types A, B, E, and F are toxic to humans; early and rapid detection is essential for adequate medical treatment. Presently available tests for detection of BoNTs, although sensitive, require hours to days. We report a BoNT-B sensor whose properties allow detection of BoNT-B within minutes. The technique relies on the detection of an agarose bead detachment from the tip of a micromachined cantilever resulting from BoNT-B action on its substratum, the synaptic protein synaptobrevin 2, attached to the beads. The mechanical resonance frequency of the cantilever is monitored for the detection. To suspend the bead off the cantilever we use synaptobrevin's molecular interaction with another synaptic protein, syntaxin 1A, that was deposited onto the cantilever tip. Additionally, this bead detachment technique is general and can be used in any displacement reaction, such as in receptor-ligand pairs, where the introduction of one chemical leads to the displacement of another. The technique is of broad interest and will find uses outside toxicology.

Simultaneous imaging of ionic conductivity and morphology of a microfluidic system
Journal of Applied Physics -- June 15, 2003 -- Volume 93, Issue 12, pp. 10134-10136
ABSTRACT: We present a method for nanoscale simultaneous measurements of the conductivity and morphology of microfluidic systems. While device morphology is imaged by atomic force microscopy (AFM), the AFM tip is used as an electrode probe to measure the conductivity through a buffer in the fluidic channels to a reference electrode. Connectivity to a reference electrode can be probed simultaneously at a large number of test points along micro- and nanofluidic channels without the requirement of external fluidic connections. Since the placement of microelectrodes is essential to a number of microfluidic applications, this technique allows for the AFM tip to be used as a rapid prototyping tool.

Nanomechanics of Microtubules
Phys. Rev. Lett. 89, 248101 (2002)
ABSTRACT: We have determined the mechanical anisotropy of a single microtubule by simultaneously measuring the Young's and the shear moduli in vitro. This was achieved by elastically deforming the microtubule deposited on a substrate tailored by electron-beam lithography with a tip of an atomic force microscope. The shear modulus is 2 orders of magnitude lower than the Young's, giving rise to a length-dependent flexural rigidity of microtubules. The temperature dependence of the microtubule's bending stiffness in the (5–40) °C range shows a strong variation upon cooling coming from the increasing interaction between the protofilaments.

RGM is a repulsive guidance molecule for retinal axons
Nature -- September 26, 2002 -- Volume 419, Issue 6905, pp. 392-395
ABSTRACT: Axons rely on guidance cues to reach remote targets during nervous system development. A well-studied model system for axon guidance is the retinotectal projection. The retina can be divided into halves; the nasal half, next to the nose, and the temporal half. A subset of retinal axons, those from the temporal half, is guided by repulsive cues expressed in a graded fashion in the optic tectum, part of the midbrain. Here we report the cloning and functional characterization of a membrane-associated glycoprotein, which we call RGM (repulsive guidance molecule). This molecule shares no sequence homology with known guidance cues, and its messenger RNA is distributed in a gradient with increasing concentration from the anterior to posterior pole of the embryonic tectum. Recombinant RGM at low nanomolar concentration induces collapse of temporal but not of nasal growth cones and guides temporal retinal axons in vitro, demonstrating its repulsive and axon-specific guiding activity.

beta-Lactam antibiotics offer neuroprotection by increasing glutamate transporter expression

2005-01-10T16:23:00.000Z

Nature 433, 73 - 77 (06 January 2005); doi:10.1038/nature03180

Correspondence and requests for materials should be addressed to J.D.R. (jrothste@jhmi.edu).

Abstract: Glutamate is the principal excitatory neurotransmitter in the nervous system. Inactivation of synaptic glutamate is handled by the glutamate transporter GLT1 (also known as EAAT2; refs 1, 2), the physiologically dominant astroglial protein. In spite of its critical importance in normal and abnormal synaptic activity, no practical pharmaceutical can positively modulate this protein. Animal studies show that the protein is important for normal excitatory synaptic transmission, while its dysfunction is implicated in acute and chronic neurological disorders, including amyotrophic lateral sclerosis (ALS)3, stroke4, brain tumours5 and epilepsy6. Using a blinded screen of 1,040 FDA-approved drugs and nutritionals, we discovered that many -lactam antibiotics are potent stimulators of GLT1 expression. Furthermore, this action appears to be mediated through increased transcription of the GLT1 gene7. -Lactams and various semi-synthetic derivatives are potent antibiotics that act to inhibit bacterial synthetic pathways8. When delivered to animals, the -lactam ceftriaxone increased both brain expression of GLT1 and its biochemical and functional activity. Glutamate transporters are important in preventing glutamate neurotoxicity1, 9-11. Ceftriaxone was neuroprotective in vitro when used in models of ischaemic injury and motor neuron degeneration, both based in part on glutamate toxicity11. When used in an animal model of the fatal disease ALS, the drug delayed loss of neurons and muscle strength, and increased mouse survival. Thus these studies provide a class of potential neurotherapeutics that act to modulate the expression of glutamate neurotransmitter transporters via gene activation.

Dopaminergic neurons generated from monkey embryonic stem cells function in a Parkinson primate model

2005-01-06T16:00:00.000Z

Abstract

Parkinson disease (PD) is a neurodegenerative disorder characterized by loss of midbrain dopaminergic (DA) neurons. ES cells are currently the most promising donor cell source for cell-replacement therapy in PD. We previously described a strong neuralizing activity present on the surface of stromal cells, named stromal cell–derived inducing activity (SDIA). In this study, we generated neurospheres composed of neural progenitors from monkey ES cells, which are capable of producing large numbers of DA neurons. We demonstrated that FGF20, preferentially expressed in the substantia nigra, acts synergistically with FGF2 to increase the number of DA neurons in ES cell–derived neurospheres. We also analyzed the effect of transplantation of DA neurons generated from monkey ES cells into 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine–treated (MPTP-treated) monkeys, a primate model for PD. Behavioral studies and functional imaging revealed that the transplanted cells functioned as DA neurons and attenuated MPTP-induced neurological symptoms.

J. Clin. Invest. 115:102-109 (2005). doi:10.1172/JCI200521137.

Antibiotic Shown to Protect Nerves in Animal Study

2005-01-06T15:48:00.000Z

January 5, 2005 10:38:39 AM PST , Reuters

Antibiotics could one day be used for more than killing bacteria and may help patients suffering from neurological diseases, scientists said on Wednesday.

If a family of antibiotics, which include penicillin, produces the same effect in humans as they did in mice, researchers from Johns Hopkins University in Maryland believe the drugs could help to prevent nerve damage and death in illnesses such dementia, stroke and epilepsy.
"We're very excited by these drugs' abilities," Jeffrey Rothstein, a professor of neurology and neuroscience at the university, said in a statement.

In studies of mice genetically engineered to develop amyotrophic lateral sclerosis (ALS), or Lou Gehrig's disease, Rothstein and his team discovered that daily injections of the drug ceftriaxone improved survival and reduced symptoms of the progressive disease that attacks nerve cells in the brain and spinal cord causing paralysis and death.

Ceftriaxone is produced by Roche Holding AG under the brand name Rocephin.

They found that the drug turned on a gene that increased the number of transporters that remove the brain chemical glutamate from nerves. Glutamate usually helps electrical signals travel from one nerve to another but too much of the chemical can kill nerves.

"Because we study ALS, we tested the drugs in a mouse model of that disease, but this is much bigger than ALS. This approach has potential applications in numerous neurological and psychiatric conditions that arise from abnormal control of glutamate," Rothstein, who reported the findings in the science journal Nature, explained.

Although it is early research and clinical trials in humans are needed to prove if the drugs can help patients, the scientists said the results are encouraging despite the fact that the mice treated with the antibiotic were eventually paralyzed.

"If we can find drugs that protect against other causes of nerve death in ALS, the combination might offer a real therapy, much like using drug combinations to treat cancer," said Rothstein.

2005-01-06T12:38:00.000Z

Clones may aid work on motor neuron disease

2005-01-05T23:41:00.000Z

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2005-01-05T13:23:00.000Z