January 3, 2008, 9:29 PM CT
Gene dose affects tumor growth
Scientists at Johns Hopkins and Ohio State University have observed that the number of copies of a particular gene can affect the severity of colon cancer in a mouse model. Publishing in the Jan. 3 issue of Nature, the research team describes how trisomy 21, or Down syndrome in humans, can repress tumor growth.
We took a new approach to a 50-year-old debate about whether people with Down syndrome develop cancer less often than other people, says Roger H. Reeves, Ph.D., professor of physiology in the McKusick-Nathans Institute of Genetic Medicine at Hopkins. Studying the genetic differences linked to Down syndrome has revealed a new way of thinking about repressing cancer growth in everyone.
The research team started with a mouse model that carries, rather than a whole extra copy of chromosome 21 as is seen in trisomy 21, or Down syndrome, a partial copy containing 108 genes. They then mated those trisomic mice to mice that carry a mutation that causes intestinal tumors, similar to those seen in colon cancer in humans. The trisomic, colon cancer mice had 44 percent fewer intestinal tumors in comparison to the colon cancer mice without the extra 108 genes.
The team then used another mouse model of Down syndrome, one that carries extra copies of only 33 of the genes on chromosome 21, and repeated their genetic crosses. Mice with three copies of the 33 genes developed half the number of tumors as mice with the standard two copies. Mice carrying a deletion that left them with only one copy of these 33 genes developed twice the number of tumors as usual.........
Posted by: Janet Read more Source
January 2, 2008, 8:33 PM CT
Where thoughts of familiar objects occur inside the human brain
A team of Carnegie Mellon University computer researchers and cognitive neuroscientists, combining methods of machine learning and brain imaging, have found a way to identify where peoples thoughts and perceptions of familiar objects originate in the brain by identifying the patterns of brain activity linked to the objects. An article in the Jan. 2 issue of PLoS One discusses this new method, which was developed over two years under the leadership of neuroscientist Professor Marcel Just and Computer Science Professor Tom M. Mitchell.
A dozen study participants enveloped in an MRI scanner were shown line drawings of 10 different objects five tools and five dwellings one at a time and asked to think about their properties. Just and Mitchells method was able to accurately determine which of the 10 drawings a participant was viewing based on their characteristic whole-brain neural activation patterns. To make the task more challenging for themselves, the scientists excluded information in the brains visual cortex, where raw visual information is available, and focused more on the thinking parts of the brain.
The researchers observed that the activation pattern evoked by an object wasnt located in just one place in the brain. For instance, thinking about a hammer activated a number of locations. How you swing a hammer activated the motor area, while what a hammer is used for, and the shape of a hammer activated other areas.........
Posted by: Daniel Read more Source
December 28, 2007, 7:47 AM CT
LASIK works well in highly myopic patients
Laser surgery to correct vision problems has been in use since the early part of 1990s. Photorefractive Keratotomy (PRK) is typically used to correct low to moderate myopia, while laser in-situ keratomileusis (LASIK) is preferred for high myopia corrections. Eventhough over 18 million LASIK procedures have been performed worldwide, there is still some controversy regarding the maximum correction possible and efficacy with this technique. In an article reported in the January 2008 issue of the American Journal of Ophthalmology, scientists from Miguel Hernandez University, Medical School, Alicante, Spain; and Ankara University School of Medicine, Ankara, Turkey; report on a study of high myopia patients ten years after LASIK surgery. The findings show that LASIK for myopia over -10 D is a safe and effective procedure in the long-term.
196 high myopic eyes of 118 patients, preoperatively needing at least 10 diopter (10 D) corrections to achieve 20/20 vision, were reviewed ten years following surgery. Uncorrected vision was 77% of best-corrected vision (BSCVA) before surgery. BSCVA improved 1 line. Only 5% of eyes lost more than 2 lines of BSCVA and 40% avoided the use of glasses. 119 (61 %) of eyes were within 2.00 Diopters at 10 years. Only 2 eyes (1%) developed corneal ectasia. The retreatment rate was 27%.........
Posted by: Mike Read more Source
December 27, 2007, 8:39 AM CT
Fast-acting cyanide antidote
University of Minnesota Center for Drug Design and Minneapolis VA Medical Center scientists have discovered a new fast-acting antidote to cyanide poisoning. The antidote has potential to save lives of those who are exposed to the chemical namely firefighters, industrial workers, and victims of terrorist attacks.
Current cyanide antidotes work slowly and are ineffective when administered after a certain point, said Steven Patterson, Ph.D., principal investigator and associate director of the University of the Minnesota Center for Drug Design.
Patterson is developing an antidote that was discovered by retired University of Minnesota Professor Herbert Nagasawa. This antidote works in less than three minutes meeting the United States Department of Defense three minute solution standard. The research will be featured in the Dec. 27, 2007 issue of the Journal of Medicinal Chemistry.
Its much, much faster than current antidotes, Patterson said. The antidote is also effective over a wider time window. Giving emergency responders more time is important because its not likely that someone will be exposed to cyanide near a paramedic.
The antidote was tested on animals and has been exceptionally effective, Patterson said. Scientists hope to begin human clinical trials during the next three years.........
Posted by: Scott Read more Source
December 25, 2007, 11:15 PM CT
Genetic clues identified in alcohol addiction
People with clinical addictions know first-hand the ravages the disease can take on almost every aspect of their lives. So why do they continue addictive behaviors, even after a period of peaceable abstinence".
Some answers appear rooted in regions of the brain active during decision making.
"It's perhaps not just that people are slaves to pleasure, but that they have trouble thinking through a decision," said Charlotte Boettiger, an assistant professor of psychology at the University of North Carolina at Chapel Hill, and lead author of a study in the recent issue of the Journal of Neuroscience that took a novel tack in addiction imaging research.
"Our data suggest there may be a cognitive difference in people with addictions," Boettiger said. "Their brains may not fully process the long-term consequences of their choices. They may compute information less efficiently".
The study also observed that a variant of the COMT gene, which controls the level of the neurotransmitter dopamine in the cortex, was linked to a tendency to make impulsive decisions and with high activity in certain brain areas during decision making.
Current medications for addictions are not universally effective; a number of either mimic the addictive substance to help people get through withdrawal periods or block the substance to prevent its effects. For stimulants, such as methamphetamines, there are no therapies yet, Boettiger said.........
Posted by: Scott Read more Source
December 25, 2007, 11:07 PM CT
Why fish oil is good for you
It's good news that we are living longer, but bad news that the longer we live, the better our odds of developing late-onset Alzheimer's disease.
A number of Alzheimer's scientists have long touted fish oil, by pill or diet, as an accessible and inexpensive "weapon" that may delay or prevent this debilitating disease. Now, UCLA researchers have confirmed that fish oil is indeed a deterrent against Alzheimer's, and they have identified the reasons why.
Reporting in the current issue of the Journal of Neuroscience, now online, Greg Cole, professor of medicine and neurology at the David Geffen School of Medicine at UCLA and associate director of UCLA's Alzheimer Disease Research Center, and colleagues report that the omega-3 fatty acid docosahexaenoic acid (DHA) found in fish oil increases the production of LR11, a protein that is found at reduced levels in Alzheimer's patients and which is known to destroy the protein that forms the "plaques" linked to the disease.
The plaques are deposits of a protein called beta amyloid that is believed to be toxic to neurons in the brain, leading to Alzheimer's. Since having high levels of LR11 prevents the toxic plaques from being made, low levels in patients are thought to bea factor in causing the disease.
Alzheimer's is a debilitating neurodegenerative disease that causes memory loss, dementia, personality change and ultimately death. The national Alzheimer's Association estimates that 5.1 million Americans are currently afflicted with the disease and predicts that the number may increase to between 11 million and 16 million people by the year 2050.........
Posted by: Daniel Read more Source
December 25, 2007, 11:04 PM CT
Thinking patterns and addiction
Researchers have for the first time identified brain sites that fire up more when people make impulsive decisions. In a study comparing brain activity of sober alcoholics and non-addicted people making financial decisions, the group of sober alcoholics showed significantly more "impulsive" neural activity.
The scientists also discovered that a specific gene mutation boosted activity in these brain regions when people made impulsive choices. The mutation was already known to reduce brain levels of the neurotransmitter dopamine. The newly found link involving the gene, impulsive behavior and brain activity suggests that raising dopamine levels may be an effective therapy for addiction, the researchers say.
The research is published in the Dec. 26, 2007 issue of the Journal of Neuroscience.
Lead scientist is Charlotte Boettiger, PhD, assistant professor of psychology at the University of North Carolina at Chapel Hill. Boettiger led the research as a scientist at UCSF's Ernest Gallo Clinic and Research Center. Senior author is Howard Fields, MD, PhD, a UCSF professor of neurology and an investigator in the Gallo Center. He also serves as director of the UCSF Wheeler Center for the Neurobiology of Addiction.
Our data suggest there may be a cognitive difference in people with addictions, Boettiger said. Their brains may not fully process the long-term consequences of their choices. They may compute information less efficiently.........
Posted by: JoAnn Read more Source
December 20, 2007, 5:15 AM CT
Breakthrough in rapid malaria detection
A research team led by Dr. Paul Wiseman of the Departments of Physics and Chemistry at McGill University has developed a radically new technique that uses lasers and non-linear optical effects to detect malaria infection in human blood, as per a research studyreported in the Biophysical Journal. The scientists say the new technique holds the promise of simpler, faster and far less labour-intensive detection of the malaria parasite in blood samples.
Malaria is a vector-borne infectious disease spread by parasites of the genus Plasmodium. Most common in tropical and subtropical regions, it is a global scourge with 350 to 500 million new cases and one to three million fatalities reported annually. Most of the fatalities are concentrated in sub-Saharan Africa, where the resources and trained personnel currently mandatory to accurately diagnose the disease are spread the thinnest.
Current detection techniques require trained technicians to stain slides, look for the parasites DNA signature under the microscope, and then manually count all the visible infected cells, a labourious process dependent on the skill and availability of trained analysts. By contrast, the proposed new technique relies on a known optical effect called third harmonic generation (THG), which causes hemozoin a crystalline substance secreted by the parasite to glow blue when irradiated by an infrared laser.........
Posted by: Mark Read more Source
December 18, 2007, 10:14 PM CT
Providing chronic fatigue syndrome answers
One of the most difficult things for people suffering from Chronic Fatigue Syndrome (CFS) is that a number of believe the condition to be a psychological, not physical affliction.
New research by the Faculty of Kinesiology hopes to measure one of the syndromes most obvious symptoms information that could help doctors in the diagnosis CFS.
Diagnosis of the syndrome, generally follows eliminating every other possible cause, which leads some to speculate that the condition isnt real, says Dr. Brian MacIntosh. One thing we know is that CFS sufferers feel profound fatigue and worsening of other symptoms following even moderate physical activity. Using our expertise in the field of exercise physiology we believe we can measure this post exertion malaise and say with certainty if an individual has recovered from exercise or if that activity is making them even more fatigued.
MacIntosh, who is the Faculty of Kinesiologys Associate Dean of Graduate Studies, is an expert in the area of muscle fatigue. Much of his research has centered on high-performance athletes in peak physical condition, however he says that this research fits in well with his overall area of interest.
The tools we have developed in high performance sport are perfectly suited to track muscle fatigue in this application so without question we will be able to get some concrete answers, he says.........
Posted by: Janet Read more Source
December 17, 2007, 10:23 PM CT
The science of shivering
Scientists at Oregon Health & Science Universitys Neurological Sciences Institute have uncovered the system that tells the body when to perform one of its most basic defenses against the cold: shivering. The researchers have discovered the brains wiring system, which takes temperature information from the skin and determines when a person should start shivering. Their findings appear in the advance online edition of the journal Nature Neuroscience.
Shivering, which is actually heat production in skeletal muscles, requires quite a bit of energy and is commonly the last strategy the body uses to maintain its internal temperature to survive in a severe cold environment. Other strategies to defend against the cold, such as reducing heat loss to the environment by restricting blood flow to the skin, also appear to be controlled by the sensory mechanism that we found, explained Kazuhiro Nakamura, Ph.D., an OHSU Fellow for Research Abroad from the Japan Society for the Promotion of Science. He published the research along with his colleague Shaun Morrison, Ph.D., a senior scientist. One fascinating aspect of this study is that it shows the sensory pathway for shivering, which can be thought of as brain wiring, is parallel to but not the same as the sensory pathway for conscious cold detection. In other words, your body is both consciously and subconsciously detecting the cold at the same time using two different but related sensory systems.........
Posted by: Scott Read more Source