(Press-News.org) Scientists at Texas Biomed have developed the laboratory opossum as a new animal model to study the most common liver disease in the nation – afflicting up to 15 million Americans – and for which there is no cure.
The condition, nonalcoholic steatohepatitis (NASH), resembles alcoholic liver disease, but occurs in people who drink little or no alcohol. The major feature of NASH is accumulation of fat in the liver, along with inflammation and functional damage. Most people with NASH feel well and are not aware that they have a liver problem. Nevertheless, NASH can progress to cirrhosis, in which the liver is permanently damaged and no longer able to work properly. NASH-related cirrhosis is the fourth most common indication for liver transplantation in the U.S.
NASH affects 2 to 5 percent of Americans – roughly six million to 15 million people. An additional 15 to 30 percent of Americans have excess fat in their livers, but no inflammation or liver damage, a condition called "fatty liver" or the non-progressive form of nonalcoholic fatty liver disease (NAFLD).
The study, published in the July issue of the American Journal of Physiology-Gastrointestinal and Liver Physiology, was supported by the National Institutes of Health and the Robert J. Kleberg, Jr., and Helen C. Kleberg Foundation.
"This is the type of model in which to develop mechanism-based therapies," writes Geoffrey C Farrell, M.D., of the Australian National University Medical School in Canberra, in a journal editorial.
Both NASH and NAFLD are becoming more common, possibly because of the greater number of Americans with obesity and its important health complications, type 2 diabetes, high blood cholesterol levels, high blood pressure and other risk factors for heart attack and stroke. In the past 10 years, the prevalence of obesity has doubled in adults and tripled in children. It was previously reported by other scientists that the prevalence of NAFLD and NASH in a cohort of middle-aged patients in San Antonio is 46 percent and 12 percent, respectively.
"It now seems likely that genetic factors, such as those important for diabetes and high cholesterol levels, are what determines why a small proportion of those with fatty liver develop NASH and its complications of cirrhosis and liver cancer," said Farrell.
In the new study, high responding opossums developed elevated cholesterol and fatty liver disease when fed a high cholesterol and high fat diet, whereas low responding opossums did not. High responders carry a mutated ABCB4 gene, which affects their ability to secrete excess cholesterol from the liver into bile which, in turn, transports the cholesterol to the intestines for excretion from the body. As a consequence, opossums with the mutated gene accumulate cholesterol in the liver and ultimately in the blood.
"We showed that the fatty livers of high responders contain a tremendous amount of cholesterol," said first author Jeannie Chan, Ph.D., of Texas Biomed. "The opossum is a new animal model for investigating the mechanism by which cholesterol mediates liver injury, which will lead to a better understanding of the role of dietary cholesterol in the development of NASH."
INFORMATION:
Co-authors on the study included Rampratap S. Kushwaha, Ph.D., Jane F. VandeBerg, and John L. VandeBerg, Ph.D., all of Texas Biomed; and Francis E. Sharkey, M.D., of the UT Health Science Center San Antonio.
Texas Biomed, formerly the Southwest Foundation for Biomedical Research, is one of the world's leading independent biomedical research institutions dedicated to advancing health worldwide through innovative biomedical research. Located on a 200-acre campus on the northwest side of San Antonio, Texas, the Institute partners with hundreds of researchers and institutions around the world, targeting advances in the fight against AIDS, hepatitis, malaria, parasitic infections and a host of other infectious diseases, as well as cardiovascular disease, diabetes, obesity, cancer, psychiatric disorders, and problems of pregnancy.
For more information on Texas Biomed, go to www.TxBiomed.org, or call Joe Carey, Texas Biomed's Vice President for Public Affairs, at 210-258-9437.
How does the world's smallest mammalian diver survive icy waters to catch its prey? A recent study of American water shrews to be presented at the Society for Experimental Biology meeting in Salzburg on 1st July has surprised researchers by showing that the animals rapidly elevate body temperature immediately before diving into cold water.
This behaviour is unexpected because lower body temperatures enable diving mammals to stay underwater for longer, so heating up doesn't make sense. This is because animals use up oxygen more quickly when they are warmer.
According ...
Using combined data from a trio of orbiting X-ray telescopes, including NASA's Chandra X-ray Observatory and the Japan-led Suzaku satellite, astronomers have obtained a rare glimpse of the powerful phenomena that accompany a still-forming star. A new study based on these observations indicates that intense magnetic fields drive torrents of gas into the stellar surface, where they heat large areas to millions of degrees. X-rays emitted by these hot spots betray the newborn star's rapid rotation.
Astronomers first took notice of the young star, known as V1647 Orionis, in ...
PHILADELPHIA — Finding biocompatible carriers that can get drugs to their targets in the body involves significant challenges. Beyond practical concerns of manufacturing and loading these vehicles, the carriers must work effectively with the drug and be safe to consume. Vesicles, hollow capsules shaped like double-walled bubbles, are ideal candidates, as the body naturally produces similar structures to move chemicals from one place to another. Finding the right molecules to assemble into capsules, however, remains difficult.
Researchers from the University of Pennsylvania ...
Unfair and exploitative political agreements allow Europeans to eat fish from the plates of developing countries, according to a study led by University of British Columbia researchers.
In the case of Madagascar, the European Union pays less than it did two decades ago while catching more fish. Since 1986, the EU's quotas for catching fish in Madagascar's waters have increased by 30 per cent while its access fees have decreased by 20 per cent. As a result, the total annual income for Madagascar decreased by almost 90 per cent between 1986 and 2010.
An international ...
A study led by Hospital for Special Surgery researchers has demonstrated that women who have a specific type of antibody that interferes with blood vessel function are at risk for adverse pregnancy outcomes and that other antibodies in the same family thought to cause pregnancy complications do not put women at risk.
The researchers say that many doctors may be unnecessarily treating some pregnant women who have antiphospholipid antibodies (aPLs) with anticoagulants, such as expensive heparin injections, which can cause bleeding and bone loss. The multicenter study appears ...
PHILADELPHIA— Being the top dog — or, in this case, the top gelada monkey — is even better if the alpha male is willing to concede at times to subordinates, according to a study by researchers from the University of Pennsylvania, the University of Michigan and Duke University.
Alpha male geladas who allowed subordinate competitors into their group had a longer tenure as leader, resulting in an average of three more offspring each during their lifetimes.
The findings, collected from data during a five-year period ending in January 2011 through the University of Michigan ...
A newly published article in Physical Review Letters eliminates one of the top unsolved theoretical problems in chemical physics as ranked by the National Research Council in 1995. Scientists now can more accurately predict the dynamic behavior of electrons in atoms and molecules in chemical reactions that govern a wide range of phenomena, including the fuel efficiency of combustion engines and the depletion of the atmospheric ozone.
The paper by David Mazziotti, professor in chemistry at the University of Chicago, solves what specialists call the "N-representability ...
Istanbul, 4 July 2012: A policy of single embryo transfer (SET) reduces the risk of perinatal mortality in infants born as a result of IVF and ICSI. The conclusion emerged from an analysis of more than 50,000 births recorded in the Australian and New Zealand Assisted Reproduction Technology Database between 2004 and 2008, where the introduction of an SET policy has been associated with a reduction in overall perinatal mortality for IVF and ICSI babies.
Results of the analysis were presented here today at the annual meeting of ESHRE (European Society of Human Reproduction ...
Istanbul, 4 July 2012: There is growing interest in a "freeze-all" embryo policy in IVF. Such an approach, which cryopreserves all embryos generated in a stimulated IVF cycle for later transfer in a non-stimulated natural cycle, would avoid any of the adverse effects which ovarian stimulation might have on endometrial receptivity during the treatment cycle. Ovarian stimulation has been shown to have adverse effects on endometrial receptivity and the risk of ovarian hyperstimulation syndrome (OHSS) is also increased when embryo transfer is performed in the stimulated cycle.
Freezing ...
Istanbul, 4 July 2012: Although the first successful preservation of fertility from the freezing, thawing and grafting of ovarian tissue was reported eight years ago,(1) the technique has remained experimental and confined to a few specialist centres. Now, with the announcement of a first pregnancy (and subsequent live birth) in Italy following the transplantation of ovarian tissue, there are indications that fertility preservation is moving into the mainstream of reproductive medicine and into a greater number of centres.(2)
"Fertility preservation is now a key component ...
