The researchers found in mice that accumulation of cholesterol in the liver depletes a powerful antioxidant. The depleted cells are left sensitive to inflammatory factors that cause damage to the liver, they found. The buildup of other forms of fat in the liver, including free fatty acids and triglycerides, were insufficient to spark the events leading to worsening disease.
The findings suggest a key role for the type, as opposed to the amount, of fat in susceptibility to the liver condition known as nonalcoholic steatohepatitis (NASH), said José Fernandez-Checa and Carmen García-Ruiz of Consejo Superior de Investigaciones Científicas (CSIC) in Barcelona.
"To avoid the progression of liver disease, it may be important to eat less and be more conscious of the lipid content of the diet, particularly cholesterol," Fernandez-Checa said. Supplements that boost levels of glutathione--the antioxidant that becomes depleted in animals whose livers accumulate cholesterol--might also be beneficial, he added.
"These data also support a potential therapeutic role of statins in NASH development," he added. Statins are a class of drugs used to lower cholesterol in those at risk of cardiovascular disease.
Characterized by fat accumulation, inflammation, and liver damage, NASH affects 2%–5% percent of Americans. An additional 10%–20% percent of Americans have fat in their liver, but no inflammation or liver damage. Both conditions are becoming more prevalent, possibly due to the rise of obesity.
The accumulation of lipids in the liver cells, mostly in the form of fatty acids and triglycerides, had been considered the first step in the development of fatty liver disease, the researchers said. However, disease progression usually does not occur in the absence of a second hit that promotes oxidative stress, inflammation, cell death, and fibrosis.
In the current study, the researchers examined the connection between fat type and liver disease progression in mice with high levels of particular lipids in the liver as a result of their diet or genetic modifications that left them obese or unable to handle cholesterol properly.
In every case, mice with high levels of cholesterol in their livers became increasingly susceptible to two inflammatory factors known as cytokines, they found. The cholesterol accumulated specifically in the cellular powerhouses known as mitochondria, where it caused a drop in glutathione. Treatments that selectively depleted liver cells of glutathione produced symptoms that mirrored the effects of high liver cholesterol, they reported.
In obese mice, treatment with the cholesterol-lowering drug Atorvastatin prevented the cholesterol increase in mitochondria and restored antioxidant levels, offering protection from liver damage.
The new findings represent some of the first evidence for a role of cholesterol in delivering the "second hit" that leads to full-blown NASH, Fernandez-Checa said.
Earlier studies that found a poor correlation between blood cholesterol levels and fatty liver disease had led to some doubt about cholesterol's role, he added. Cholesterol metabolism is a complicated process, however, such that blood levels might not always reflect the amount of cholesterol in the liver, he said.
New catalyst controls activation of a carbon-hydrogen bond
21.11.2017 | Emory Health Sciences
The main switch
21.11.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
15.11.2017 | Event News
15.11.2017 | Event News
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21.11.2017 | Physics and Astronomy
21.11.2017 | Physics and Astronomy
21.11.2017 | Life Sciences