A study by scientists in the US has given every teenager the perfect excuse to sleep late at weekends. Research carried out at Northwestern University in Illinois has found that teenagers need extra sleep at the weekend to catch up on hours lost during the week. They also suggest that failing to have long lie-ins could lead to behavioural problems and poor academic results. The results, presented at the American Academy of Neurology's annual meeting in Denver on Friday, show that young people sleep on average 8.5 hours on weekdays and more than 9.5 on weekends (C) BBC

Keyword: Sleep; Development of the Brain
Link ID: 1924 - Posted: 04.20.2002

Ben Harder In 1988, physician and amateur moth enthusiast Kenneth D. Frank published a scientific paper that pulled together much of what researchers then knew about the consequences of artificial night-time lighting on moths. That paper is the closest thing the nascent field of artificial-light ecology has to a classic work. It didn't exactly trigger the response one might expect from a seminal study, however. The report has received precious little attention and stimulated no immediate cascade of follow-up research. Frank recently searched the scientific literature to count how many subsequent papers had made reference to his study—and found exactly one. Nevertheless, Frank and a handful of other scientists are endeavoring to synthesize a coherent understanding of the ecological impacts of artificial light on a multitude of organisms. These efforts are gradually gaining momentum. From anecdotal reports of little-studied phenomena—such as moths' tendency to perish, Icarus-style, in lamps and flames—researchers suspect that artificial night lighting disrupts the physiology and behavior of nocturnal animals. In many cases, scientists have few reliable data on which to rest conclusions—but every reason to be concerned. From Science News, Vol. 161, No. 16, April 20, 2002, p. 248. Copyright ©2002 Science Service. All rights reserved.

Keyword: Biological Rhythms
Link ID: 1923 - Posted: 06.24.2010

John Pickrell As dawn breaks on a misty Welsh morning, the earliest birds to break into song are likely to include European robins, followed by blackbirds and song thrushes and then a plethora of other species as sunlight crowns the horizon. The last to join the chorus, such as chaffinches and blue tits, may not chime in until 100 minutes after the first crooners began. This pattern is repeated worldwide, and ornithologists have often pondered what determines when a particular species begins its morning singing. Now, scientists say that they've found the explanation: The larger a bird's eyes, the earlier it starts to sing. The staggering of avian choruses was first documented 70 years ago but has remained unexplained. Now, researchers have revisited an idea first proposed in the 1960s but never tested. It's that visual acuity—determined by eye size—governs when birds start to sing. From Science News, Vol. 161, No. 16, April 20, 2002, p. 245. Copyright ©2002 Science Service. All rights reserved.

Keyword: Biological Rhythms; Sexual Behavior
Link ID: 1922 - Posted: 06.24.2010

Ben Harder At common environmental concentrations, the popular weed killer atrazine strips male frogs of a key hormone and turns some of them into hermaphrodites, according to new research. The finding raises concerns that the chemical may be contributing to global amphibian declines. In use for about 4 decades and currently employed in 80 countries atrazine is the most common herbicide in the United States. It's found in virtually all the nation's waterways and is especially prevalent around cornfields in the Midwest. It has also been identified in tests of preschoolers' drinking water (SN: 11/3/01, p. 285: Available to subscribers at http://www.sciencenews.org/20011103/note16.asp). "There seems to be no atrazine-free environment," says Tyrone B. Hayes of the University of California, Berkeley. Past research has found no evidence that typical environmental concentrations of atrazine cause premature death or abnormal growth in amphibians. The new research, which Hayes and his colleagues report in the April 16 Proceedings of the National Academy of Sciences, similarly finds that mortality and overall growth of the common lab frog Xenopus laevis are unaffected by atrazine. From Science News, Vol. 161, No. 16, April 20, 2002, p. 243. Copyright ©2002 Science Service. All rights reserved.

Keyword: Hormones & Behavior; Sexual Behavior
Link ID: 1921 - Posted: 06.24.2010

By C. CLAIBORNE RAY Q. Why do chickens have white meat and dark meat and ducks have only dark meat? A. Chickens and ducks have different exercise habits and different muscle structures, with differing levels of a dark substance called myoglobin. Chickens, which are mostly earthbound, with an occasional spurt of flying, have breasts that contain mostly fast-twitch muscle fibers; these contract powerfully for a short hop in the air, but they soon become tired. Copyright 2002 The New York Times Company

Keyword: Muscles
Link ID: 1920 - Posted: 04.20.2002

Whether for finding food, avoiding predators or choosing a mate, the sense of smell is critical for the existence of many creatures. We humans, able to distinguish over 10,000 scents, utilize our sense of smell for a multitude of activities from enjoying the aroma of freshly brewed coffee to deciding whom not to sit next to on the bus. Scientists are now beginning to understand how the nose and brain process the complex information that gives rise to the perception of smell. Copyright © 1995-2002 UniSci. All rights reserved.

Keyword: Chemical Senses (Smell & Taste)
Link ID: 1918 - Posted: 06.24.2010

BOSTON – The identification of a protein that enables the body to overcome resistance to the hormone leptin could help scientists move one step closer to creating a drug therapy to help prevent and treat obesity. The findings, made by researchers at Beth Israel Deaconess Medical Center (BIDMC), are reported in the April 16 issue of Developmental Cell. Nearly all obese individuals are resistant to leptin, the hormone that signals the brain that our appetites are satisfied and we can stop eating. For this reason, explains study co-senior author Barbara Kahn, M.D., Chief of Endocrinology and Metabolism at BIDMC, efforts made several years ago to use leptin in drug form to treat obesity were largely unsuccessful. “The majority of obese people actually have high levels of leptin,” explains Kahn, who is a Professor of Medicine at Harvard Medical School. “But they are unable to put it to use.” In this new research, Kahn, together with co-senior author Benjamin Neel, M.D., Ph.D., – Director of the Cancer Biology Program at BIDMC who studies the biological functions of molecules known as protein-tyrosine phosphatases – initially began studying PTP1B (protein tyrosine phosphatase 1B) to determine its role in regulating insulin receptor signaling.

Keyword: Obesity
Link ID: 1917 - Posted: 06.24.2010

Two drugs used to treat hallucinations in patients with Parkinson’s disease (PD) can not only reduce hallucinations, but may also lead to long-term benefits in these patients, according to a group of Emory University researchers. The long-term benefits may include reduced mortality and a reduced risk of nursing home placement. The drugs studied were the atypical antipsychotics quetiapine (trade name Seroquel®) and clozapine (trade name Clozaril®). Jorge Juncos, M.D., associate professor of neurology, Emory University School of Medicine, and colleagues will present their findings at the American Academy of Neurology 54th Annual Meeting in Denver, Colo., on April 18. The research will also appear as an abstract in the April issue of the journal, Neurology. "Drug-induced psychotic symptoms, such as visual hallucinations, are seen in a significant number of patients with advanced PD," says Dr. Juncos. "Approximately 15 to 20 percent of PD patients may experience these hallucinations over time. They are due to a interaction between the progression of the illness and the drugs used to treat its symptoms," Dr. Juncos explains.

Keyword: Parkinsons
Link ID: 1916 - Posted: 06.24.2010

For at least one of North America’s most common birds, mating songs are more than just empty amorous enticement, according to a new study from The Johns Hopkins University. Scientists have found that male starlings’ singing ability is strong evidence of the health of their immune systems and, thus, their suitability as breeding partners. The new finding may explain why female starlings take singing talent into account when choosing their mates and is an important first step towards proving a decade-old theory that suggests evolution has found a way to stop male birds from engaging in false sexual advertising. “The theory, which is known as the Immunocompetence Handicap Hypothesis, or ICHH, proposes that males of lesser reproductive quality are prevented from cheating – producing a signal that falsely indicates high reproductive quality – by some cost associated with producing that signal,” explains Deborah Duffy, lead author on the new paper. Duffy, a recent Ph.D. graduate of Johns Hopkins, is now a postdoctoral fellow at Indiana University. She is co-author with Greg Ball , professor of psychological and brain sciences in the Krieger School of Arts and Sciences at Johns Hopkins, of a paper published in the April 22 issue of The Proceedings of the Royal Society of London.

Keyword: Sexual Behavior; Neuroimmunology
Link ID: 1915 - Posted: 06.24.2010

Larger Studies of Herbal Supplement Are Needed, Experts Say By Salynn Boyles WebMD Medical News -- Millions of people take the herbal supplement ginkgo biloba in the belief that it boosts brain power, and several studies suggest it improves mental function in some patients with Alzheimer's disease. New research now shows that it may do the same thing for patients with multiple sclerosis (MS). Researchers from the University of California, San Diego, report that small group of MS patients treated with ginkgo biloba had improved memory and mental function, compared with placebo-treated patients. The study was reported today at the annual meeting of the American Academy of Neurology in Denver. "In fairness, this was a pilot study with only 23 patients enrolled," study co-author Christopher Kenney, MD, tells WebMD. "We wanted to address the question of whether a large study of ginkgo biloba is justified in patients with MS. I think the answer is an overwhelming yes." © 1996-2002 WebMD Corporation. All rights reserved.

Keyword: Multiple Sclerosis
Link ID: 1914 - Posted: 06.24.2010

By David Derbyshire, Science Correspondent AN EXPERIMENTAL treatment for Parkinson's disease has regenerated the brains of five people with the condition. One of the patients has learned to laugh again and has regained his sense of smell. Although the results are preliminary, and have yet to be published, doctors believe the procedure could offer hope to Britain's 120,000 sufferers. © Copyright of Telegraph Group Limited 2002.

Keyword: Parkinsons; Trophic Factors
Link ID: 1913 - Posted: 06.24.2010

Scientific evidence that the clubbers' drug ecstasy damages the brain is fundamentally flawed, a report says. New Scientist magazine says that while there is little doubt that the drug can be harmful, some studies suggesting a serious impact on the brain cannot be trusted. Central to the magazine's argument are question marks over the validity of brain scans which researchers have said show that ecstasy damages production of a vital brain chemical called serotonin. The scans purportedly provided evidence that the drug destroyed nerve cells that specialise in serotonin production. US researchers used a radioactive chemical to show up serotonin activity in the brain. Scans showed that the brains of ecstasy users glowed less - suggesting that the drug had reduced serotonin production. (C) BBC

Keyword: Drug Abuse
Link ID: 1912 - Posted: 04.18.2002

Drinking coffee late in the afternoon could ruin the chance of a good night's sleep, say scientists. Coffee is not just a stimulant, it interrupts the flow of melatonin, the brain hormone that sends people to sleep. Melatonin levels start to rise about two hours before bed time and peak between 0200 and 0400. However, researchers in Israel have found that caffeinated coffee halves the body's levels of the sleep hormone. Lotan Shilo and a team at the Sapir Medical Center at Tel Aviv University, found that six volunteers slept less well after a cup of caffeinated coffee than after drinking the same amount of decaffeinated. (C) BBC

Keyword: Sleep; Hormones & Behavior
Link ID: 1911 - Posted: 04.18.2002

NewScientist.com news service Single mums are better at raising their kids than two parents - at least in the bird world. Mother zebra finches have to work harder and raise fewer chicks on their own, but they also produce sexier sons who are more likely to get a mate. The finding shows that family conflict is as important an evolutionary driving force as ecological factors such as predation and food supply. With two parents around, there is always a conflict of interests, which can have a detrimental effect on the quality of the offspring. In evolutionary terms, the best strategy for any parent in the animal world is to find someone else to care for their offspring, so they can concentrate on breeding again. So it is normal for parents to try to pass the buck to each other. But Ian Hartley from the University of Lancaster and his team wondered how families resolve this conflict, and how the conflict itself affects the offspring. © Copyright Reed Business Information Ltd.

Keyword: Sexual Behavior; Evolution
Link ID: 1910 - Posted: 06.24.2010

By DENISE GRADY A new report by a panel of international experts casts doubt on longstanding claims that hormone replacement can prevent or treat a variety of ills in postmenopausal women, including heart disease, Alzheimer's disease, severe depression, urinary incontinence and broken bones caused by osteoporosis. While hormone therapy is the most effective way to relieve menopausal symptoms like hot flashes and night sweats, there is not enough scientific evidence to support its use for the other problems, says the report, which is to be published in June. The hormone treatments have well-documented drawbacks, including an increased risk of blood clots and gall bladder disease and breast cancer with prolonged use. More than 40 million American women are 50 or older, and 20 million more will reach menopause within the next decade. About 20 percent of women who reach menopause naturally use hormone replacement at least temporarily, according to the North American Menopause Society. The figure is higher among women who reach menopause early because their ovaries have been surgically removed. Copyright 2002 The New York Times Company

Keyword: Hormones & Behavior; Alzheimers
Link ID: 1909 - Posted: 04.18.2002

Conflict between mates means uglier offspring. JOHN WHITFIELD Parental bickering damages young birds. Mother finches do less work when a father is around and their sons are less attractive to females as a consequence, researchers have discovered. Each mate plays a game of 'evolutionary poker', trying to invest as little as it can get away with. "Parents hold back a bit in the hope that the other will make up the shortfall," says ecologist Ian Hartley of Lancaster University, UK. This is the first time that such gambling has been shown to damage offspring. A female zebra finch (Taeniopygia guttata ) raising two chicks alone does more work than a paired mother with a brood of four, Hartley and his colleagues found. Males reared in one- and two-parent families were of similar size and weight, but, given the choice, females plumped for single-parented males more often. * Royle, N.J., Hartley, I.R. & Parker, G.A. Sexual conflict reduces offspring fitness in zebra finches. Nature, 416, 733 - 736, (2002). © Nature News Service / Macmillan Magazines Ltd 2002

Keyword: Sexual Behavior; Evolution
Link ID: 1906 - Posted: 06.24.2010

Field Museum scientist challenges accepted theories, dating methods CHICAGO - New research that accounts for gaps in the fossil record challenges traditional methods of interpreting fossils and constructing evolutionary trees. Applying a new statistical approach to primates demonstrates that this group-from which humans developed-originated 85 million years ago (Mya) rather than 65 Mya, as is widely accepted. This revision has implications throughout the evolutionary tree of primates, including the time of origin of the human lineage. Key findings from the new approach to interpreting the fossil record include: * Primates originated while dinosaurs still roamed the earth. This challenges the widely accepted theory that primates could not establish a foothold until the end of the Cretaceous (65 Mya) when an asteroid cleared the way by hitting the earth and wiping out dinosaurs. * If times of divergence within the primate tree are revised accordingly, it is likely that the divergence of humans from chimps occurred about 8 Mya rather than 5 Mya.

Keyword: Evolution
Link ID: 1905 - Posted: 04.18.2002

Emory researchers study the possibilities of a common, unrecognized comorbidity Emory University researchers may have found a common but heretofore unrecognized link between low testosterone levels and certain non-motor symptoms (fatigue, depression, anxiety or sexual dysfunction) in male Parkinson’s disease (PD) patients. When given testosterone replacement therapy (TRT), the researchers report that patients with low levels of testosterone experienced significant improvement in these symptoms, which had not responded to other medications. But investigators caution they only looked at a small group of five patients and they did not compare those people to a placebo or control group. Michael Okun, M.D., and Mahlon DeLong, M.D., in the Department of Neurology, as well as William McDonald, M.D., in the Department of Psychiatry and Behavioral Sciences will present their findings at the American Academy of Neurology 54th Annual Meeting in Denver, Colo., on April 17. The researchers will also publish their work in an upcoming issue of the Archives of Neurology.

Keyword: Parkinsons; Hormones & Behavior
Link ID: 1904 - Posted: 06.24.2010

By Julia Sommerfeld MSNBC DENVER, — Experimental transplants of cells from aborted fetuses and donated eyes are showing promise for the treatment of Parkinson’s disease, according to two studies out Wednesday. Both types of cells were shown to survive in patients’ brains and improve some of the hallmark symptoms of the dreaded disease. PARKINSON’S, which affects an estimated 1 million people in the United States, is caused when the brain cells that produce a chemical known as dopamine die off. Colorado researchers reported follow-up results on a controversial experiment in which holes were drilled in the skull and dopamine cells from aborted fetuses were implanted in the brains of advanced Parkinson’s patients. Other doctors described the initial results of transplants of dopamine cells from the retinas of donated eyes. Both findings were presented at the annual meeting of the American Academy of Neurology in Denver. “It takes the loss of 80 percent to 90 percent of dopamine-producing neurons to lead to the symptoms of Parkinson’s disease,” said Dr. Robin Brey, a professor of medicine, division of neurology at University of Texas Health Sciences Center, San Antonio. “So you need fairly small amount of dopamine-producing neurons to remain normal. That tells us that even if a small number of transplanted cells were to take and produce dopamine, that could do a lot. So this is very promising.” MSNBC Terms, Conditions and Privacy © 2002

Keyword: Parkinsons; Stem Cells
Link ID: 1902 - Posted: 06.24.2010

The study is small but the results encouraging By Pallab Ghosh BBC science correspondent Doctors in Bristol, UK, have developed an experimental treatment which, they suspect, has regenerated the brains of five patients with Parkinson's disease. One patient has learned to laugh again and has regained his sense of smell. The doctors say it is too soon to tell whether the treatment is long lasting or could be used on all sufferers of Parkinson's. But they have been astonished at how effective the treatment has been so far. The treatment involves putting a drug called GDNF into a mechanical pump, which feeds it to the most damaged parts of the brain. (C) BBC

Keyword: Parkinsons; Trophic Factors
Link ID: 1901 - Posted: 04.18.2002