October 25, 2007, 10:24 PM CT
How Diseases Jump Across Species
Scientists at the University of Leeds have made a breakthrough in understanding a virus which poses one of the greatest global disease threats to wild carnivores including lions, African wild dogs and several types of seal.
The discovery of how canine distemper Virus (CDV) jumps across and infects different species of carnivores could lead to a more effective monitoring and control of the virus.
Whilst these 'pathogen jumps' across species are quite common, very little is known about the process of how viruses takes hold and become established in new host species.
CDV is passed through close contact from domestic and feral dogs causing epidemics that often result in mass mortalities - and is pushing some species to the brink of extinction (2).
"The virus needs to bind to a specific receptor on cells in the host in order to infect it," explains lead researcher, PhD student Alex McCarthy, from the University's Faculty of Biological Sciences. "But the sequences of receptors vary between species, so a virus from one species shouldn't be able recognise and infect the cells of other species".
By analysing the virus' genetic sequence in both dog and wild carnivore species, the research team were able to prove that two key parts of a CDV protein specifically involved in receptor recognition had evolved during the host jumps, where as the rest of the protein showed very few changes among viruses from different species.........
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October 25, 2007, 10:22 PM CT
Recognizing someone's name but forgetting how you met them
New research from The University of Western Ontario suggests the sometimes eerie feeling experience when recognizing someone, yet failing to remember how or why, reveals important insight into how memory is wired in the human brain.
In research published recently in one of the world's most-cited multidisciplinary scientific publications, "Proceedings of the National Academy of Sciences USA," Western psychology graduate student Ben Bowles and psychology professor Stefan Kohler have observed that this feeling of familiarity during recognition relies on a distinct brain mechanism and does not simply reflect a weak form of memory.
"Recognition based on familiarity can be contrasted with recognition when we spontaneously conjure up details about the episode in which we encountered the person before, such as where we met the person or when it happened," explains Kohler.
The authors report that a rare form of brain surgery that can be highly effective for therapy of epilepsy can selectively impair the ability to assess familiarity.
"It is counterintuitive but makes a lot of sense from a theoretical perspective that familiarity can be affected, while the ability to recollect episodic detail is completely spared," adds Kohler.
The research is based on Bowles' Master's thesis and was supported by a grant from the Canadian Institutes of Health Research (CIHR) to Dr. Kohler. It has important implications for understanding memory deficits in neurology, including in Alzheimer's disease.........
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October 25, 2007, 10:19 PM CT
'Knocking Out' Cell Receptor May Help to Prevent Weight Gain
University of Cincinnati (UC) pathologists have identified a new molecular target that one day may help researchers develop drugs to reduce fat transport to adipocytes (fat cells) in the body and prevent obesity and related disorders, like diabetes.
Detailed in the Oct. 18 online edition and the November 2007 print issue of the Journal of Clinical Investigation, the findings about a specific cell receptor, known as the adipocyte LDL receptor-related protein 1 (LRP1), provide important clues about the underlying biological mechanisms that control fat transport in the body.
Using genetically altered mice, David Hui, PhD, and his team demonstrated that "knocking out" the LRP1 in fat cells has a direct impact on how a number of lipids (fats and fat-like substances) are transferred and deposited to different tissues. Hui says the experimental mice gained less weight, stored less fat, tolerated glucose better and expended more energy (due to increased muscle activity) when compared with a control group.
"This receptor is expressed in numerous tissues throughout the body-including the heart, muscles, liver and vascular wall-but its specific functions in the different tissues are still relatively unknown," says Hui, corresponding author of the study and professor of pathology and laboratory medicine at UC. "Our study has shown that this molecule directly impacts the rate of fat transport in the body, so with further study it could be a new target for drugs aimed at controlling obesity".........
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October 25, 2007, 10:16 PM CT
HIV patients sicker when seeking care
It was hoped that as HIV therapy improved and as HIV-related public health initiatives encouraged people to be tested for the disease and seek care, that HIV-infected patients would seek care quickly. Unfortunately, a new study indicates that patients are actually sicker when they begin treatment. The study is reported in the November 15 issue of Clinical Infectious Diseases, currently available online.
The study, carried out in Baltimore, MD, from 1990 through 2006, shows that HIV patients beginning HIV treatment have trended toward increasing levels of immunocompromise. This is probably an indicator that people are getting tested for HIV later after theyve contracted the disease than in the past. Also, people in several key demographic groups are not any quicker now to seek care than they were in the past and some are even taking longer.
HIV is a disease that is most effectively treated if caught early in the course of the illness. Early therapy also helps to limit the spread of the virus from one person to another. For these reasons, HIV services in the United States have evolved over time to encourage people to be tested for HIV and seek therapy if infected.
The researchers, Jeanne Keruly, MS and Richard Moore, MD, of Johns Hopkins University School of Medicine in Baltimore, analyzed data from over 3,300 patients seeking HIV care from the Johns Hopkins HIV service. The data were examined both as a whole and as demographic subsets including gender, race, injecting drug use, men who have sex with men, and heterosexuals. They looked at the amount of time between a patients diagnosis of HIV and the time when that person first sought care; and they looked at the patients immune status at the time of first care. Ideally, they would have found trends that showed a decrease in the time between diagnosis and therapy and an increase in the immune status.........
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October 24, 2007, 8:09 PM CT
Pregnant women at risk for unnecessary operations
New research reported in the recent issue of the Journal of the American College of Surgeons suggests that pregnant women suspected of having appendicitis are often misdiagnosed and undergo unnecessary appendectomies (removal of the appendix) that can result in early delivery or loss of the fetus. The study points to the need to require more accurate diagnosis to avoid unnecessary operations and the potential for fetal loss.
Appendicitis is difficult to diagnose in pregnant women, with signs and symptoms that are similar to those of pregnancy itself. Consequently, surgeons have historically taken an aggressive approach to the therapy of suspected appendicitis in pregnant women in order to reduce the risk and possible consequences of a ruptured appendix.
Our study shows that the complication rate in pregnant women who undergo a negative appendectomy is nearly identical to those who suffer a ruptured appendix, said Marcia L. McGory, MD, David Geffen School of Medicine, University of California at Los Angeles. This finding argues for a change in the basic approach to the therapy of suspected appendicitis in pregnant women. One potential straightforward solution is to use more advanced imaging tools, such as ultrasound and magnetic resonance imaging, to increase diagnostic accuracy.........
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October 24, 2007, 7:44 PM CT
Severely Restricted Diet Linked to Physical Fitness into Old Age
Severely restricting calories leads to a longer life, researchers have proved.
New research now has demonstrated for the first time that such a diet also can maintain physical fitness into advanced age, slowing the seemingly inevitable progression to physical disability and loss of independence.
The study, using a rat model of life-time caloric restriction, showed that the diet reduces the amount of visceral fat, which expresses inflammatory factors that in humans cause chronic disease and a decline in physical performance and vitality across the lifespan.
The study appears in the recent issue of Journals of Gerontology Series A: Biological Sciences and Medical Sciences.
Have we finally discovered the Fountain of Youth?.
No. But we may be getting a little closer.
"This is the first study to report that caloric restriction reduced production in visceral fat of the inflammatory cytokine IL-6 and enhanced performance on overall physical function assessments," said Tongjian You, Ph.D., assistant professor of exercise and nutrition sciences in the UB School of Public Health and Health Professions and principal investigator.
"In addition, rats that ate a normal diet lost a significant amount of lean muscle mass and acquired more fat, while calorie-restricted rats maintained lean muscle mass as they aged".........
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October 23, 2007, 10:23 PM CT
Cannabis a double-edged sword
A new neurobiological study has observed that a synthetic form of THC, the active ingredient in cannabis, is an effective anti-depressant at low doses. However, at higher doses, the effect reverses itself and can actually worsen depression and other psychiatric conditions like psychosis.
The study, reported in the October 24 issue of The Journal of Neuroscience, was led by Dr. Gabriella Gobbi of McGill University and Le Centre de Recherche Fernand Seguin of Hpital Louis-H. Lafontaine, affiliated with l'Universit de Montral. First author is Dr. Gobbi's McGill PhD student Francis Bambico, along with Noam Katz and the late Dr. Guy Debonnel* of McGill's Department of Psychiatry.
It has been known for a number of years that depletion of the neurotransmitter serotonin in the brain leads to depression, so SSRI-class anti-depressants like Prozac and Celexa work by enhancing the available concentration of serotonin in the brain. However, this study offers the first evidence that cannabis can also increase serotonin, at least at lower doses.
Laboratory animals were injected with the synthetic cannabinoid WIN55,212-2 and then tested with the Forced Swim test a test to measure depression in animals; the scientists observed an antidepressant effect of cannabinoids paralleled by an increased activity in the neurons that produce serotonin. However, increasing the cannabinoid dose beyond a set point completely undid the benefits, said Dr. Gobbi.........
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October 23, 2007, 10:21 PM CT
Link between obesity and viral infections
Experts dont dispute the important role that diet and activity play in maintaining a healthy weight. But can poor eating habits and a less active lifestyle fully explain the prevalence of obesity in the United States today? That question has led some scientists to ask whether there might be other causes for this serious problem. In the recent issue of Mayo Clinic Proceedings, researcher Richard Atkinson, M.D., asserts that there is a growing body of evidence demonstrating that viruses may play a role in causing obesity in humans.
The cause of obesity is not a secret -- if you consume more calories than you burn in daily activity, you gain weight. What is interesting is that much of the obesity epidemic cannot be explained just by Americans eating more and exercising less. There are other factors at play, and viruses causing obesity may be one of them, say Dr. Atkinson.
Dr. Atkinson, director of Obetech Obesity Research Center in Richmond, Va., evaluated multiple published articles that demonstrate a correlation between viral infections and obesity. His article in Mayo Clinic Proceedings discusses five animal viruses and three human viruses that have been shown to cause obesity in laboratory studies.
As per Dr. Atkinson, several studies offer ample evidence that animals infected with certain human viruses experience excess weight gain and fat storage. When scientists infected animal subjects with a human virus known as Human Ad-36, they reported measurable increases in the infected animals body fat and the visceral fat that surrounds the organs deep within the belly. In addition, studies also demonstrated that infection with Ad-36 and the resulting weight gain could be transmitted from infected animals to uninfected animals.........
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October 23, 2007, 10:19 PM CT
Mate tea lower cholesterol
When a study in her lab showed that mate tea drinkers had experienced a significant increase in the activity of an enzyme that promotes HDL (good) cholesterol while lowering LDL (bad) cholesterol, University of Illinois scientist Elvira de Mejia headed for Argentina where mate tea has been grown and taken medicinally for centuries.
She returned with a five-year agreement signed by administrators of La Universidad Nacional de Misiones (UNaM) to cooperate in the study of 84 genotypes of mate tea, both cultivated and wild, never-before-studied, varieties. The arrangement calls for the writing of joint grants and an exchange of students and professors between UNaM and the U of I.
The scientist is also negotiating a grant from the National Institute of Yerba Mate to fund further research, she said.
Our studies show that some of the most important antioxidant enzymes in the body are induced by this herbal tea, said de Mejia of her study in Septembers Planta Medica.
Because Argentina has the different mate varieties, well be able to do more comparisons and characterizations between the different genotypes and the benefits of different growing conditionswhether in sun (on a plantation) or in shade (under the rainforest canopy), she added.
Not only does de Mejia hope to identify the most nutritionally beneficial genotypes of the herbal tea, she hopes that Argentine experience with drying and processing mate will lead to improved extraction of the teas bioactive compounds. Food companies are very interested in adding tea extracts to juices, soda, and even beer to increase the nutritional value of their products, she said.........
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October 23, 2007, 10:15 PM CT
MRI predicts liver fibrosis, study says
Moderate to severe chronic liver disease can be predicted with the use of diffusion-weighted MRI (DWI), as per a recent study conducted by scientists at New York University Medical Center in New York, NY.
Due to the increased occurence rate of chronic hepatitis in the United States, especially hepatitis C, there is a strong need for non-invasive methods to replace or supplement liver biopsy, which is relatively invasive and limited by interobserver variability and sampling error, said Bachir Taouli, MD, lead author of the study. DWI appears promising in that purpose, eventhough it needs validation in larger series, he said.
The study included 23 patients with chronic hepatitis and 7 volunteers. The scientists compared apparent diffusion coefficients (ADCs) or the quantification of water diffusion in a tissue between patients who had stage 2 or greater versus stage 1 or less fibrosis and stage 3 or greater versus stage 2 or less fibrosis. In liver fibrosis and cirrhosis, decreased ADC (i.e. restricted water diffusion) is possibly correlation to increased collagen deposition and decreased perfusion. The study showed that hepatic ADC was a significant predictor of stage 2 or greater and stage 3 or greater liver fibrosis.
At this point, this is an experimental method that needs to be tested in a larger series. It should also be compared with other methods such as FibroTest (a score based on a combination of basic serum markers) or FibroScan (an ultrasound based method to measure liver stiffness) in order to be validated, said Dr. Taouli. However, diffusion imaging does show potential for decreasing the number of biopsies and decreasing the number of antifibrogenic drug trials, he said.........
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