NewScientist.com news service We are more unique than previously thought, according to new comparisons of human and chimpanzee DNA. It has long been held that we share 98.5 per cent of our genetic material with our closest relatives. That now appears to be wrong. In fact, we share less than 95 per cent of our genetic material, a three-fold increase in the variation between us and chimps. The new value came to light when Roy Britten of the California Institute of Technology became suspicious about the 98.5 per cent figure. Ironically, that number was originally derived from a technique that Britten himself developed decades ago at Caltech with colleague Dave Kohne. By measuring the temperature at which matching DNA of two species comes apart, you can work out how different they are. © Copyright Reed Business Information Ltd.

Keyword: Evolution; Development of the Brain
Link ID: 2700 - Posted: 06.24.2010

By RICHARD A. FRIEDMAN, M.D. Most young gay and bisexual American men who were found to be infected with the AIDS virus in a recent study were unaware of their infection, according to a finding reported recently at the 14th International AIDS Conference in Barcelona by Dr. Duncan MacKellar, an epidemiologist at the Centers for Disease Control and Prevention. The study surveyed 5,719 men, ages 15 to 29, of whom 573 were discovered to be H.I.V.-positive. Of those 573 men, 77 percent did not know that they were infected. Despite having engaged in frequent high-risk sex like unprotected anal intercourse, most of these men still believed that they were at low risk of contracting H.I.V. How can one explain such potentially fatal self-destructive behavior? After all, the route of H.I.V. transmission and safer sexual practices are well known. Copyright 2002 The New York Times Company

Keyword: Sexual Behavior
Link ID: 2699 - Posted: 09.24.2002

By ANDREW POLLACK IRVINE, Calif. — In a closetlike room at the "Leg Lab" here, salamanders stare blankly out of clear plastic drinking cups. The lab is so named because many of the animals have had, or will have, a leg cut off. But the salamanders recover, with perfect new limbs growing back in weeks. Salamanders are the superstars of regeneration. They can grow back not only limbs but also tails, parts of their hearts and the retinas and lenses in their eyes. Humans cannot do any of that. So scientists here hope that the salamander's tricks may one day be applied to people. "I really do believe it's just a matter of time before you're going to regenerate an arm or at least a finger," said Dr. David M. Gardiner, a biologist who runs the laboratory at the University of California at Irvine with Dr. Susan V. Bryant, the dean of biological sciences and his wife. "I'd like to see that in my lifetime." Copyright 2002 The New York Times Company

Keyword: Regeneration
Link ID: 2698 - Posted: 06.24.2010

By NICHOLAS WADE Most people have around 100 billion nerve cells in their brain. But the roundworm, down at the other end of the scale of animal complexity, figures out everything it needs to know about life with exactly 302 neurons. Researchers have now gained what seems to be a major insight into how nature builds brains of such different capabilities. They have discovered a gene that apparently determines the brain's size. The gene has come to light through study of a disease known as microcephaly, in which people are born with a head and brain significantly smaller than usual. Patients are in general only mildly retarded but have far fewer neurons. The microcephalic patients might not have come to clinical attention but for a dam that was completed in 1967 in the Mirpur Province of Pakistani-controlled Kashmir. Some 50,000 Pakistanis were displaced by the rising waters, and many emigrated to Bradford, in the British midlands. The emigrants included some large families with many marriages between close relatives, a circumstance that can make genetic disease more evident. Copyright 2002 The New York Times Company

Keyword: Evolution; Development of the Brain
Link ID: 2697 - Posted: 09.24.2002

Big brains gave humans an evolutionary edge, but how did they grow so big? An important clue may come, ironically, from a gene that has been found to stunt the cerebral cortex in people with microcephaly. A team led by biologist Geoffrey Woods of the University of Leeds, U.K., found the brain-shrinking gene, called ASPM, by sequencing the DNA of people afflicted with primary microcephaly, a familial disease that stunts the growth of the cerebral cortex during development. The researchers discovered that in microcephalic people, chunks of the protein encoded by ASPM are missing because of mutations in the gene. To determine where in the body ASPM is active, they screened different fetal tissues and found the gene expressed in the progenitor cells that produce cerebral cortex neurons. Previous work with fruit flies suggests how the gene might influence brain size. The fruit fly version of ASPM organizes the spindle fibers that separate chromosome pairs into the two halves of dividing neuronal progenitor cells. The orientation of these fibers determines how many neurons a progenitor cell will produce, and the more neurons produced, the larger the brain. Humans with microcephaly probably have fewer cortical neurons because mutant ASPM disrupts cell division in the progenitor cells, says Christopher Walsh, a neurobiologist at Harvard University and co-author of the new study, which is published online 23 September by Nature Genetics. Copyright © 2002 by the American Association for the Advancement of Science.

Keyword: Evolution; Development of the Brain
Link ID: 2696 - Posted: 06.24.2010

Attention Deficit Hyperactivity Disorder (ADHD) is a neuropsychiatric condition characterized by hyperactive-impulsive behavior and persistent inattention. Individuals with this condition experience social and academic dysfunction. It is postulated that a developmental failure in the brain mechanism underlies self-control and inhibition in ADHD. ADHD affects approximately 3 to 6% of children from different geographical regions worldwide. Boys are affected more frequently than girls, with the ratio ranging from 3:1 to 9:1. Family studies have indicated a strong genetic component in susceptibility to ADHD. An approximate five to six fold increase in the frequency of ADHD among first-degree relatives when compared with the general population was observed. A number of twin studies have estimated the heritability of ADHD to range from 39% to 91% for various symptoms of the disorder. Synaptosomal-associated protein 25 (SNAP-25) is a protein which is expressed highly and specifically in the nerve cells. The gene encodes a protein essential for synaptic vesicle fusion and neurotransmitter release. Animal model studies have shown that the coloboma mouse mutant has a hyperactive phenotype similar to that of ADHD. This model was shown to be the result of a deletion of the SNAP-25 gene.

Keyword: ADHD; Genes & Behavior
Link ID: 2695 - Posted: 09.24.2002

Copyright © 2002 AP Online The Associated Press WASHINGTON - There are more differences between a chimpanzee and a human being than once believed, according to a new genetic study. Biologists have long held that the genes of chimps and humans are about 98.5 percent identical. But Roy Britten, a biologist at the California Institute of Technology, said in a study published this week that a new way of comparing the genes shows that the genetic similarity between humans and chimps is only about 95 percent. Copyright © 2001 Nando Media

Keyword: Evolution; Genes & Behavior
Link ID: 2694 - Posted: 06.24.2010

Movements faster than your reaction time stop a stick falling off your finger. PHILIP BALL There's more to balancing tricks than quick reactions. Most of the tiny movements we make to balance a stick on a fingertip happen faster than our typical response time, say Juan Cabrera and John Milton of the University of Chicago, thanks to noise in our nervous system.1 Cabrera and Milton think that this mechanism could apply to any problem of balance. Random movements may explain how a tightrope walker stays aloft, for instance. Robotics engineers could make their machines more stable by injecting a little noise into their systems. Using fast cameras that detect infrared light, Cabrera and Milton filmed the motion of a stick with reflective ends, balanced on end on a person's fingertip. Light reflected from the ends enabled them to measure fluctuations in the stick's angle from the vertical. © Nature News Service / Macmillan Magazines Ltd 2002

Keyword: Movement Disorders
Link ID: 2693 - Posted: 06.24.2010

Had an out-of-body experience? Scientists believe they know why BY JEFFREY KLUGER Shamans teach that out-of-body experiences are best achieved through meditation, reflection and transcendental calm. Scientists believe they have found a less celestial source: the right angular gyrus of the brain. The new thinking is the result of the case of a woman, 43, who was undergoing treatment for epilepsy originating in her brain's right hemisphere. A team of researchers at the University Hospitals of Geneva and Lausanne wrote in Nature last week that to pinpoint the problem, it implanted electrodes in the suspect region to record seizures and used a weak current to map the brain. The doctors — and the patient — then got a surprise. When the current was applied to a particular spot, the woman experienced a sense of lightness, as if she were floating above herself. More remarkably, she seemed to see part of her body as if she were viewing it from the ceiling. When the doctors asked her to move her limbs, she experienced other illusions: one arm seemed shorter than the other; her legs seemed to fly toward her face; if she closed her eyes, her upper body felt as if it were flying toward her legs. Copyright © 2002 Time Inc. All rights reserved.

Keyword: Miscellaneous
Link ID: 2692 - Posted: 06.24.2010

DALLAS – – Researchers at UT Southwestern Medical Center at Dallas and their colleagues have uncovered new information that will help brain researchers better understand a person’s tolerance to drugs of abuse and open new avenues of investigation into the relationship of addictive-drug usage and the biological causes of mood disorders. Dr. Michel Barrot, assistant professor of psychiatry at UT Southwestern and lead author of the paper, said researchers used genetically altered mice to show that pain – both physiological and psychological – as well as pleasure can activate changes in the nucleus accumbens, the forebrain structure critical for reward and motivation processes. The findings appeared in a recent issue of Proceedings of the National Academy of Sciences. Senior author Dr. Eric Nestler, chairman of psychiatry at UT Southwestern, had previously established that drugs of abuse activate CREB, a specific binding protein known for playing a role in the plasticity and adaptation of nerves in the nucleus accumbens. This action between a drug and a binding site is involved with the learning processes and can affect the interaction between subject and environment. © 2002 The University of Texas Southwestern Medical Center at Dallas

Keyword: Drug Abuse
Link ID: 2691 - Posted: 06.24.2010

Artificial neuro-stimulation offers hope — and movement — to the paralysed BY THOMAS K. GROSE Our brains constantly and subconsciously send commands to which our bodies react almost simultaneously. And the internal communications network that accomplishes this miraculous feat is the nervous system. But for many stroke patients, a portion of the nerve network crashes, and that often results in paralysis. Researchers have for years tried using artificial stimulation to sidestep the damaged portion of the system, with little success. Nerves don't appreciate being tampered with. But now scientists at Aalborg University in Denmark have developed electrodes that allow for artificial neuro-stimulation, a breakthrough that may help many stroke patients overcome paralysis. Aalborg's initial technology is an implant — like a pacemaker — that "stimulates the nerve to mimic natural movement," explains Thomas Sinkjaer, the professor who is heading the research. It will benefit patients who sustained so much damage that they are beyond rehabilitation therapies and would otherwise remain paralyzed. Artificially stimulating nerves to perform even simple tasks is a challenge. Even a routine movement, like picking up a paper coffee cup, requires a complex set of instructions to the hand to determine, among other things, how much pressure is needed. Too little pressure, and the cup is dropped; too much, and it's crushed. But the sensors Sinkjaer's team developed can pick up nerve impulses sent to and from the brain to determine how much stimulation is needed to control grasp. Copyright © 2002 Time Inc. All rights reserved.

Keyword: Robotics; Regeneration
Link ID: 2690 - Posted: 06.24.2010

Animal experiments a year away, doctors predict ASSOCIATED PRESS — Attempts to restore sight to people with damaged retinas are turning toward signaling the brain the way nature does it, using chemicals to deliver signals to nerve endings. EXPERIMENTS ALREADY under way with retinal implants seek to use electrical signals to make the nerves send information to the brain. But doctors from Michigan and California described a different method Monday, using retinal implants that respond to images by releasing nerve-stimulating chemicals. MSNBC Terms, Conditions and Privacy © 2002

Keyword: Vision
Link ID: 2689 - Posted: 06.24.2010

The number of Scottish adults contracting meningitis has shown a significant increase, according to a charity. The Meningitis Trust for Scotland said the illness has been on the rise in adults in recent years - although most people still believe that it is a child-centred illness. Now the charity has launched a campaign stressing that meningitis does not only affect children. Of the 177 cases of meningitis notified to Scottish health officials in the 12 months to August, 25% patients involved adults. During 2001 there was a 63% increase in meningococcal meningitis - a severe form of the disease - among the over 20s north of the border. That compared to a rise of about 47% in England and Wales. (C) BBC

Keyword: Miscellaneous
Link ID: 2688 - Posted: 09.23.2002

By THE ASSOCIATED PRESS SACRAMENTO,(AP) — Gov. Gray Davis today signed a law that explicitly allows research on stem cells from fetal and embryonic tissue. The measure is meant to encourage the type of research that the Bush administration made subject to federal limits last year. State officials said they believed they were the first in the country to take such a step. Mr. Davis was joined in announcing the law by the actor Christopher Reeve, who became a stem cell research advocate after an accident left him paralyzed from the neck down. Mr. Davis, Mr. Reeve and other supporters said the legislation was necessary to keep California at the forefront of medical research. The bill was opposed by the Roman Catholic Church and anti-abortion groups. Copyright 2002 The New York Times Company

Keyword: Stem Cells; Regeneration
Link ID: 2687 - Posted: 06.24.2010

Copyright © 2002 United Press International By JOE GROSSMAN, UPI Science News SEATTLE - In a conclusion that counters other recent findings, researchers said postmenopausal women taking hormone replacement therapy, adjusting for overall cardiovascular risk, seem to show no increased risk of stroke vs. women not taking HRT. The overall adjusted risk for postmenopausal women taking HRT is no lower than 0.7 times postmenopausal women not taking hormone therapy and no higher than 1.4 times the risk, the researchers reported, although they added they did find an increased stroke risk for postmenopausal women during the first six months of HRT about 1.8 times greater than for women not taking HRT. "What we can say for sure is that hormone replacement therapy did not prevent stroke, lead researcher Rozenn N. Lemaitre, a research scientist in the cardiovascular research unit at the University of Washington, told United Press International. "We found a transient association of increased risk (and it) needs to be confirmed by additional study." Copyright © 2001 Nando Media

Keyword: Hormones & Behavior; Stroke
Link ID: 2686 - Posted: 06.24.2010

What makes one body better proportioned than another? By Andrew Epstein and Eric Haseltine As far back as 500 B.C., architects believed that certain proportions were inherently pleasing to the eye. So they designed buildings such as the Parthenon on the Acropolis at Athens according to an "ideal" proportion, sometimes referred to as the golden rectangle. If you divide any line into two unequal sections such that the ratio of the larger section to the smaller section equals the ratio of the entire line to the longer section, this ratio is the irrational golden number 1.618. . . that mathematicians call phi. The 13th-century scholar Leonardo Fibonacci discovered that if you start a number series with 0 and 1, then add any two adjacent numbers to obtain the next integer, the series that results (0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89. . .) has the property such that the ratio of any two successive numbers converges on the golden number phi. © Copyright 2002 The Walt Disney Company.

Keyword: Sexual Behavior; Vision
Link ID: 2685 - Posted: 06.24.2010

Learn what your brain and silicon circuits have in common By Eric Haseltine Although you may not know exactly what goes on inside the hardware of your PC, you might suspect that it's not all that similar to what goes on in the "wetware" inside your skull. After all, your PC is a digital computer that's compelled to "think" in discrete ones and zeros, while your brain, the quintessential analog processor, is free to think any way it pleases. Or is it? Perceptual psychologists have uncovered a phenomenon in which the brain exhibits all-or-nothing logic suspiciously like that of a digital computer. To experience this, click on each of the colored dots above. The blue and yellow dots should produce a sound like the phoneme ga, and the red and green dots should make a sound like the phoneme da. (Phonemes are basic building blocks of speech).

Keyword: Language; Hearing
Link ID: 2684 - Posted: 09.22.2002

By SANDRA BLAKESLEE When Christopher Reeve went on national television last week to announce that he could wiggle his fingers and hips, the news seemed startling. Paralyzed from the neck down after a horseback riding accident in 1995, Mr. Reeve had been told repeatedly that he would never be able to move any part of his body below his shoulders. But scientists who study the brain say Mr. Reeve's recovery is part of a quiet revolution in how intense physical exercise can help restore the brain and spinal cord after serious injury. At academic research centers in the United States, Europe and Japan, paralyzed patients are hanging from harnesses, walking on treadmills and tying down limbs to force the use of paralyzed arms and legs. Some are being fit into robots designed to help move their bodies. Using such techniques, an estimated 500 paraplegics who had limited sensations in their lower bodies are now able to walk for short distances, unassisted or using walkers, scientists say. Copyright 2002 The New York Times Company

Keyword: Regeneration; Brain Injury/Concussion
Link ID: 2683 - Posted: 09.22.2002

Boosting antioxidants is first defense against cognitive dysfunction syndrome Sophia Yin It's sad when Fido's rusty gait and late-blooming gray paint a picture of a pooch physically past his prime, but that's nothing compared with watching Fido's brain start to wane. Dr. Debra Horwitz, a diplomate of the American College of Veterinary Behaviorists and owner of Chelsea, an aged Labrador retriever, has experienced this firsthand. "About a year ago I began to notice changes in Chelsea's behavior," Horwitz says. "She was more anxious than normal. At night she'd pant and pant. She was also barking and waking us up in the middle of the night." ©2002 San Francisco Chronicle.

Keyword: Alzheimers
Link ID: 2682 - Posted: 06.24.2010

Patients with Alzheimer's disease and dementia are to be helped to talk to their family and friends using a hi-tech device to trigger memories. One of the most distressing aspects of the dementia can be the person's loss of short-term memory. But long-term memories often stay strong, and researchers from the Universities of Dundee and St Andrews in Scotland have devised a touch-screen multimedia system which patients and carers can use as a conversation aid. A prototype of the Computer Interactive Reminiscence Conversation Aid (CIRCA) will be given a special demonstration at the University of Dundee on Saturday to mark World Alzheimer's Day. The Circa system will use video, songs and pictures to prompt memories and conversation. (C) BBC

Keyword: Alzheimers; Learning & Memory
Link ID: 2681 - Posted: 09.21.2002