Two plant-derived chemicals can reduce the damage from a simulated stroke in cultured mouse brain cells, according to a study from SFVAMC researchers. Further research might lead to a new class of stroke drugs, the researchers said. The chemicals work by shutting down the enzyme PARG (Poly-ADP-Ribose Glycohydrolase), which contributes to cell death in the wake of a stroke, said the study's lead author Raymond Swanson, MD, acting chief of neurology at San Francisco Veterans Affairs Medical Center and UCSF associate professor of neurology. "By inhibiting PARG we can protect brain cells from the type of cell death that happens during a stroke. This same death mechanism is seen in several other disorders, such as diabetes, inflammation, and heart attack," Swanson said. Copyright © 2001, The Regents of the University of California.

Keyword: Stroke
Link ID: 781 - Posted: 10.20.2001

By Jennifer Fisher Wilson Severe daytime sleepiness, inability to stay awake or sleep for extended periods of time, cataplexy (muscle atonia triggered by emotions such as laughing or anger), and an inability to move on sleep onset or awakening: These are all signs of narcolepsy, an uncommon, disabling neurological disorder that affects about one in every 2,000 people. Narcolepsy has long fascinated sleep researchers because it is the only known neurological disorder that affects the generation and organization of sleep. In 1999, scientists of these Hot Papers identified the genes that cause narcolepsy, opening the door to understanding sleep at a molecular level. The Scientist 15[20]:22, Oct. 15, 2001 © Copyright 2001, The Scientist, Inc. All rights reserved.

Keyword: Sleep; Genes & Behavior
Link ID: 778 - Posted: 11.06.2001

By MICHIKO KAKUTANI he son of two physicians in wartime England, Oliver Sacks says it was "understood, almost from my birth, that I would be a doctor," and in fact he would grow up to become a doctor, a humane, philosophical doctor, uncommonly attuned to the passion and pathos of his patients and the astonishing resilience of human life, as his earlier books ("Awakenings," "An Anthropologist on Mars," "The Man Who Mistook His Wife for a Hat") so eloquently attest. Dr. Sacks's first love, however, was not medicine but chemistry, and in his new memoir, "Uncle Tungsten," he gives us a moving account of his childhood ardor for science: for numbers, for the chemical elements, for formulas and systems. Copyright 2001 The New York Times Company

Keyword: Miscellaneous
Link ID: 774 - Posted: 10.20.2001

From butterflies to newts, many creatures roam the neighborhood--or globe--and still find their way home. Now, two studies in the 12 October issue of Science reveal how sea turtles and mole rats tap a basic navigational tool: Earth's magnetic field. Earth's churning liquid core casts a magnetic field across the planet's surface. Birds, fish, crustaceans, and a host of other kinds of animals appear to use regional variations in the magnetic field, along with sensory cues such as sight and sound, to navigate. The finer details of these strategies, however, remain largely a mystery. Earlier work by Kenneth Lohmann of the University of North Carolina (UNC), Chapel Hill, and his colleagues had found that eastern Florida's loggerhead sea turtles sense magnetic fields. Now the team decided to examine whether the turtles used regional fields during migration. Copyright © 2001 by the American Association for the Advancement of Science.

Keyword: Animal Communication
Link ID: 773 - Posted: 10.20.2001

Chameleon tongues have special muscle to haul in dinner. JOHN WHITFIELD Chameleons can reel in prey anywhere within two-and-a-half body lengths of their jaws. Their tongues can overcome even a bird's weight and reluctance to be eaten. How? Muscles that are unique among backboned animals, researchers now reveal. Anthony Herrel of the University of Antwerp, Belgium, and colleagues put crickets at different distances from the noses of two chameleon species, Chameleo calyptratus and Chameleo oustaletti. The tongues of these 12-cm-long reptiles pull at maximum strength on prey from 5-30 centimetres away, the team found. Such versatility is beyond normal muscle: "it wouldn't be able to pull back," says Herrel. 1.Herrel, A., Meyers, J. J., Aerts, P. & Nishikawa, K. C. Functional implications of supercontracting muscle in the chameleon tongue retractors. Journal of Experimental Biology, 204, 3621 - 3627 , (2001). © Nature News Service / Macmillan Magazines Ltd 2001

Keyword: Robotics
Link ID: 771 - Posted: 10.20.2001

ITHACA, N.Y. -- Bioengineers at Cornell University have demonstrated a system for transplanting clusters of brain cells, together with controlled-release microcapsules of protein, to enable cell differentiation and growth. The system, first tested with rat fetal brain cells and nerve growth factor (NGF) implanted in the brains of adult rats, has yet to be demonstrated in humans. But the technique to create microenvironments for tissue growth is said to be adaptable to a variety of other transplantation needs, including the treatment of neurodegenerative disease and spinal cord injuries. The achievement is reported in the latest issue (October 2001) of the journal Nature Biotechnology.

Keyword: Regeneration; Trophic Factors
Link ID: 770 - Posted: 10.20.2001

The Lancet (C) 2001 The Lancet. via ProQuest Information and Learning Company; All Rights Reserved Love, Rebecca Dehydroascorbic acid (DHA), a precursor of vitamin C, has cerebroprotective effects in a mouse model of stroke according to a new study from the USA. "These results suggest that an antioxidant precursor that readily penetrates the bloodbrain barrier has promise in the treatment of stroke in humans", says Sander Connolly (Columbia University, NY, USA), one of the investigators. Judy Huang and colleagues compared the effects of vitamin C and DHA on cerebral ischaemia induced by transient or permanent middle cerebral artery occlusion in mice. They found that pretreatment with DHA immediately prior to a reversible (45 min) occlusion significantly reduced infarct volume, increased post-ischaemic blood flow and reduced neurological deficit; pretreatment with vitamin C had no effect. Similarly, pretreatment with DHA protected against permanent (24 h) occlusion, although the effects were less marked. The investigators also found that giving DHA 15 min or 3 h after the ischaemic period was protective, suggesting that antioxidant depletion contributes to neuronal damage following ischaemia (Proc Natl Acad Sci 2001; 98: 117 2024).

Keyword: Stroke; Hormones & Behavior
Link ID: 768 - Posted: 10.20.2001

Bruce Bower An unprecedented genetic find has emerged from an extended British family in which more than half the members display a severe speech and language disorder. Scientists have now identified a genetic mutation that lies at the root of this family's communication breakdown. This is the first gene implicated in people's capability to talk and to understand language, according to a team led by geneticist Cecilia S.L. Lai of the University of Oxford in England. She and her colleagues describe their discovery in the Oct. 4 Nature. "It's exciting that we've found a mutation common to every family member with this disorder," says study coauthor Faraneh Vargha-Khadem, a neuroscientist at the Institute of Child Health in London. "This mutation may impede development of brain areas that mediate speech and language use." From Science News, Vol. 160, No. 14, Oct. 6, 2001, p. 213. Copyright ©2001 Science Service. All rights reserved.

Keyword: Language; Genes & Behavior
Link ID: 767 - Posted: 10.20.2001

by J. Wesley Boyd, M.D., Ph.D., and Karen Lasser, M.D. Psychiatric Times October 2001 Vol. XVII Issue 10 Those who suffer from mental illness smoke cigarettes at astoundingly high rates compared to those without some form of mental illness. We have published data showing that between 50% and 80% of those suffering from a major mental illness (such as major depression, bipolar disorder, generalized anxiety disorder and schizophrenia, among others) smoke, whereas less than 40% of those who have never had mental illness smoke (Lasser et al., 2000). In all, people with mental illness consume 44% of all cigarettes in the United States, an exceedingly high figure that might surprise even the most sanguine mental health care professional. This statistic bears within it numerous individual stories of pain and suffering. Consider the case of one of our patients, whose woeful story no doubt mirrors that of many others we treat who suffer with chronic mental illness:

Keyword: Drug Abuse
Link ID: 766 - Posted: 10.20.2001

by Marc N. Potenza, M.D., Ph.D., and Mary K. Wilber Psychiatric Times October 2001 Vol. XVII Issue 10 Pathological gambling (PG) represents a growing public health concern (Potenza et al., 2001a). As compared with other major neuropsychiatric disorders with similar prevalence rates (e.g., schizophrenia and bipolar disorder), relatively few investigations have been performed about the pathophysiology or treatment of PG (For more information on the history and background of PG, please visit www.psychiatrictimes.com/srpg.html -- Ed.) In order to advance current treatment standards, an improved understanding of the biological processes underlying PG is needed. One major theory proposes that PG is a non-chemical addictive disorder (Blanco et al., 2001; Potenza, 2001; Potenza, in press). Given the shared features between PG and substance dependence (SD) and the significant advances made over the past several decades in our understanding of SD, there exists a useful platform on which to base studies of PG to investigate for similarities and differences between SD and PG (Potenza, 2001).

Keyword: Drug Abuse
Link ID: 765 - Posted: 10.20.2001

To survive in utero, the fetus must resist an onslaught by the mother's immune system that, most researchers agree, recognizes the father's share of the embryo as foreign and sometimes rejects it. Now, endocrinologists have determined that the principal soother of the maternal immune system is the same master hormone that commands the body's stress response. The results could help explain some infertility and recurring miscarriages. Immunologists have long speculated that hormone changes early in pregnancy somehow alter the mother's immune system, but they couldn't pinpoint the mechanism. In the early 1990s, pediatric endocrinologist George Chrousos and his colleagues at the National Institute of Child Health and Human Development in Bethesda, Maryland, came across a clue. They found that corticotropin-releasing hormone (CRH), secreted by the hypothalamus to induce secretion of stress hormones by the pituitary and the adrenal glands, also appeared around sites of inflammation in adults. Copyright © 2001 by the American Association for the Advancement of Science.

Keyword: Hormones & Behavior; Development of the Brain
Link ID: 763 - Posted: 10.20.2001

Investigators seek to understand the molecular mechanisms of taste By Jennifer Fisher Wilson By design, humans crave sweet-tasting foods, which supply necessary calories, and avoid bitter-tasting foods, which could be poisonous. But an individual's genetic makeup can acutely tune taste buds. Visitors to Linda Bartoshuk's Yale University lab can take a simple taste test to discover genetic influences on their food intake. The test measures sensitivity to the chemical 6-n-propyl-thiouracil, which is intensely bitter to acute taste buds, moderately bitter to a medium taste bud, and tasteless to an insensitive bud. Sensitive tasters, or supertasters, generally have more taste buds--and they are often women. To them, vegetables are more bitter, fats creamier, and chili peppers hotter. Conversely, nontasters are more likely to eat excessively sweet, very fatty, and highly spiced foods. The Scientist 15[20]:18, Oct. 15, 2001 © Copyright 2001, The Scientist, Inc. All rights reserved.

Keyword: Chemical Senses (Smell & Taste)
Link ID: 762 - Posted: 10.20.2001

Definitive answers about ERT effects are down the road By Harvey Black While estrogen replacement therapy shows promise in helping post-menopausal women preserve important cognitive abilities such as memory, its effectiveness is still being questioned. In studies at the National Institutes of Health and at the University of California, Los Angeles, researchers have demonstrated that in some women, this hormone alters brain blood flow and improves performance on certain mental tests. But other studies are not as definitive, suggesting that improved cognitive abilities could be associated with a decrease in menopausal symptoms. "The epidemiologic data we have is not that mature," says Stanley Birge, clinical director of the Older Adult Health Center at Washington University. "But I think if you add up the negative studies and the positive studies, it does fall to the side of recommending. It probably is effective in preserving the brain." But don't advise treatment right now, some researchers say. "Not yet," says Pauline Maki, an investigator with the National Institute on Aging. "There haven't been any [looks] at large numbers of women on cognitive outcomes." The Scientist 15[20]:21, Oct. 15, 2001 © Copyright 2001, The Scientist, Inc. All rights reserved.

Keyword: Hormones & Behavior; Alzheimers
Link ID: 761 - Posted: 10.20.2001

Hazel Muir Catching the eye of someone beautiful triggers a flurry of activity deep in the brain, new research has found. The discovery may shed light on why first impressions last when we meet new people. Evidence is growing that in animals, a region of the brain called the ventral striatum becomes active when the animal anticipates a reward of food. The same region becomes active in drug addicts and compulsive gamblers when they are about to indulge their habit. Knut Kampe of University College London and his colleagues wondered whether a social "reward" - the sight of an attractive face - would have the same effect. To find out, they scanned the brains of eight men and eight women as they looked at 160 photos of 40 different people in quick succession. The volunteers then rated how attractive they found the faces they had seen. © Copyright Reed Business Information Ltd.

Keyword: Sexual Behavior; Brain imaging
Link ID: 760 - Posted: 10.20.2001

by Lucy Yardley, M.Sc., Ph.D. Psychiatric Times October 2001 Vol. XVII Issue 10 Dizziness is a very common symptom, with a lifetime prevalence of about one in four of the general population (Kroenke, 1992). Patients usually use the term dizziness to describe the disorientation and imbalance that result from abnormal balance system functioning, which is most commonly caused by a vestibular disorder. But dizziness is a non-specific symptom that patients also use to describe different sensations -- for example, lightheadedness or mental confusion -- which result from quite different etiologies, such as a cardiovascular or psychiatric disorder. It is often difficult either to confirm or exclude an organic diagnosis for dizziness because of the extensive range of possible etiologies, the lack of definitive exhaustive tests of balance system function, and the transient and ambiguous nature of signs and symptoms. Differential diagnosis of organic versus psychogenic dizziness is further complicated by the very high prevalence of anxiety, panic disorder and agoraphobia among people with diagnosed balance disorders (Clark et al., 1994; Stein et al., 1994; Sullivan et al., 1993; Yardley et al., 1998b) and the unexpectedly high prevalence of balance system dysfunction in patients with panic disorder and agoraphobia that can be detected by sensitive tests (Jacob et al., 1996; Yardley et al., 1995a).

Keyword: Emotions
Link ID: 759 - Posted: 10.20.2001

by Christine E. Marx, M.D., M.A. Psychiatric Times October 2001 Vol. XVII Issue 10 The term neurosteroid refers to steroids formed in the brain. It was created in 1981 by Dr. Etienne-Emile Baulieu and colleagues, following the remarkable discovery that the brain appeared to have the capacity to synthesize its own steroids in situ. In a set of rodent experiments, these researchers determined that the steroid dehydroepiandrosterone sulfate (DHEAS) was present in adult rat brains at concentrations up to 20-fold greater than plasma (Corpechot et al., 1981). Moreover, brain DHEAS concentrations persisted unchanged for over two weeks following adrenalectomy and gonadectomy in these animals, demonstrating that central nervous system DHEAS levels were likely independent of peripheral DHEAS formation in the adrenals or gonads. Hence, the brain itself appeared to be a potential site of steroidogenesis, and subsequent efforts confirmed this possibility. These molecules became known as neurosteroids, since they can be synthesized de novo in the brain from cholesterol or from peripheral steroid precursors that cross the blood-brain barrier readily. A closely related term, neuroactive steroids, includes steroids formed in the brain and periphery that exhibit rapid actions on neuronal excitability. Unlike classical steroid mechanisms that involve the binding of intracellular receptors and the regulation of gene transcription, neuroactive steroids have nongenomic actions (Paul and Purdy, 1992). Specifically, neuroactive steroids bind to membrane-bound ligand-gated ion channel receptors. As a result, their actions occur very rapidly (over the course of seconds to minutes), in contrast to steroid genomic actions that require hours to days. Interestingly, certain neuroactive steroids with rapid nongenomic effects, such as progesterone, also exhibit traditional genomic steroid actions. Progesterone is considered to be a neurosteroid if it is synthesized in the brain, hence, the terms neurosteroid and neuroactive steroid are often used interchangeably.

Keyword: Hormones & Behavior; Emotions
Link ID: 758 - Posted: 10.20.2001

by John DeQuardo, M.D. Psychiatric Times October 2001 Vol. XVII Issue 10 For almost a century, researchers have suggested that schizophrenia is the result of brain-based abnormalities (Kraepelin, 1919). The first structural neuroanatomic studies conducted in patients with schizophrenia were undertaken in the 1930s and 1940s using pneumoencephalography -- a radiologic technique wherein cerebrospinal fluid (CSF) is replaced by air, thereby facilitating X-ray imaging of the brain ventricular system. These early investigations demonstrated lateral ventricle enlargement in some patients with schizophrenia (Haug, 1962). A few investigators found evidence of progression of ventricular enlargement in severely ill patients; however, technical factors involved in image acquisition limited the veracity of the results. The first computed tomography (CT) scan study in patients with schizophrenia was published in 1976 by Johnstone et al. The researchers found that, in chronically ill patients, ventricle enlargement was common and most pronounced in those patients who were most ill (i.e., had the most negative symptoms). Since that time, dozens of studies have replicated the finding of ventricular enlargement in schizophrenia (as well as findings of cerebral cortical atrophy) (Shelton and Weinberger, 1986), some found evidence for progression (Illowsky et al., 1988; Nasrallah et al., 1986), while others did not (Kemali et al., 1989; Woods et al., 1990). The discrepancy in results is very likely the result of methodologic differences between studies.

Keyword: Schizophrenia
Link ID: 757 - Posted: 10.20.2001

Eight years after identifying the first gene responsible for inherited cases of Lou Gehrig's disease, scientists have found another one. Currently there is little hope for those suffering from the neurodegenerative disease that led to the death of Baseball Hall of Famer Lou Gehrig. Scientists hope that this latest finding could help clarify how the disease destroys the central nervous system. Formally known as amyotrophic lateral sclerosis (ALS), Lou Gehrig's disease usually strikes people in their 40s or 50s. Neurons in the brain and spinal cord that control muscles degenerate, eventually killing those affected. The cause of most ALS cases remains a mystery, but about 10% are inherited, and in 1993, scientists found that a gene called SOD1 was mutated in a fifth of these cases. Now, two teams have independently pinpointed a second culprit gene that accounts for some of the other inherited ALS cases. = Copyright © 2001 by the American Association for the Advancement of Science.

Keyword: ALS-Lou Gehrig's Disease ; Genes & Behavior
Link ID: 756 - Posted: 10.20.2001

In the absence of leptin signaling, mice, like humans, grow extremely obese and develop many of the common sequellae of obesity in humans, such as diabetes and steatosis of the liver. Introduction of leptin directly into the hypothalamus potently reverses the overeating and obesity seen in leptin-deficient animals. Still, expression of the leptin receptor ObR is not limited to the hypothalamus and other regions of the brain, but also occurs in the liver and many other sites. Hence, the possibility remains that some of aspects of the leptin-deficient phenotype reflect the absence of peripheral signaling. To test the significance of various sites of central and peripheral leptin signaling, Cohen et al. have used Cre-lox technology to generate mice in which particular cell types delete the ObR gene by somatic recombination. Here, they describe the effects of ObR deficiency in the brain or the liver. Absence of neuronal ObR greatly increases body weight and induces the accumulation of fat in the liver, effects that are not seen when the ObR defect is restricted to the liver. Because obesity in the brain-specific knockout is not as severe as that in simple knockouts, it may be that OBR signaling in organs helps regulate energy homeostasis?effects that may still be revealed in other Cre/lox experiments . However, the authors note that there was considerable scatter in their data and that those animals that had most efficiently removed the ObR gene from their neurons weighed the most. The complete absence of neuronal ObR might, if it could be achieved using this technology, might therefore recapitulate all of the effects observed in Ob- or ObR-deficient animals.

Keyword: Obesity
Link ID: 755 - Posted: 10.20.2001

Michael W. Schwartz Obesity, insulin resistance, and type 2 diabetes are a tightly linked and increasingly common triad of metabolic disorders. A well-supported and widely accepted explanation for their association is that obesity-induced insulin resistance in tissues such as muscle, liver, and fat increases the demand for insulin, and that type 2 diabetes ensues when this heightened demand cannot be met by defective pancreatic ß cells. Despite the undeniable importance of adipocytes in the regulation of insulin sensitivity (see refs. 1-3 for recent reviews and insights into this interaction), this understanding of the pathogenesis of type 2 diabetes may yet be incomplete. Growing evidence suggests that the CNS plays a key role in glucose homeostasis, via brain pathways that overlap with those controlling food intake and body weight. Advancing this notion a step further is the study by Obici et al., published in this issue of the JCI (4), implicating a specific hypothalamic neuronal pathway - the melanocortin pathway - in the control of insulin sensitivity in peripheral tissues. The recognition that neuronal melanocortin signaling also figures prominently in energy homeostasis, the process whereby energy intake is matched to energy expenditure over time, suggests an intimate coupling of neuronal mechanisms regulating body weight and glucose metabolism (Figure 1). Disorders affecting key neuronal pathways can therefore be included among potential mechanisms linking obesity to type 2 diabetes (5).

Keyword: Obesity
Link ID: 754 - Posted: 10.20.2001