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FDA Approves Vaccine For Seasonal Influenza
The US Food and Drug Administration (FDA) announced yesterday that it has approved a vaccine for 2009-2010 seasonal influenza in the United
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How Microbial Neighbors Settle Differences
Even microbes are governed by the principle of supply and demand - at least at the genetic level. Not all of their gene products, the blueprints for proteins, are required at all times. That means most of their genes only become active when they are needed, as is the case in higher organisms. In the simplest case, a transcription factor will activate the gene in question at the right time. Genes that are regulated in a somewhat more complex manner, on the other hand, are kept inactive by a repressor that is removed only when the gene is needed. Which of these two regulation mechanisms will develop is a question of demand, along the lines of a "use-it-or-lose-it" principle: if genes are frequently active, then, as a rule, they will be directly induced. Genes that encode more rarely used proteins, on the other hand, tend to be kept inactive by repressors. LMU physicist Ulrich Gerland and Professor Terence Hwa of the University of California have now demonstrated using computer simulations and theoretical analyses that another - indeed opposing - principle also comes into play: "wear-and-tear". According to this principle, direct activation can lead to harmful changes. "Which of the two principles prevails depends on evolutionary criteria such as the population size and the periods over which environmental changes take place," says Gerland. "Our study may serve as a useful basis for more detailed studies of the evolution of regulatory systems." (PNAS Early Edition, 22 Mai 2009)
News of the day
H1N1 Death Toll Doubles Over Last Month; First Vaccine Trial Begins
The worldwide death toll from the H1N1 (swine flu) virus has doubled in the past month, reaching over 700, the WHO announced Tuesday, the AP/Google.com reports. "WHO did not give a breakdown of the deaths Tuesday. But as of last week, the U.S. reported 263 deaths, Canada reported 45 deaths and Britain had 29. According to WHO"s last update on July 6, there were 119 deaths in Mexico," the news service writes. "Yet even Tuesday"s figure of 700 deaths may seriously underestimate the true toll, experts say, because not all swine flu cases are being picked up due to testing limitations" (Jordans, 7/21).
Diagnostics

'Tasting' Mechanism Used By Airway Cells To Detect And Clear Harmful Substances

The same mechanism that helps you detect bad-tasting and potentially poisonous foods may also play a role in protecting your airway from harmful substances, according to a study by scientists at the University of Iowa Roy J. and Lucille A. Carver College of Medicine. The findings could help explain why injured lungs are susceptible to further damage. The study, published online July 23 in Science Express, shows that receptors for bitter compounds that are found in taste buds on the tongue also are found in hair-like protrusions on airway cells. In addition, the scientists showed that, unlike taste cells on the tongue, these airway cells do not need help from the nervous system to translate detection of bitter taste into an action that expels the harmful substance. The hair-like protrusions, called motile cilia, were already known to beat in a wave-like motion to sweep away mucus, bacteria and other foreign particles from the lungs. The study is the first to show that motile cilia on airway cells not only have this "clearing" function, but also use the receptors to play a sensory role. The researchers also found that when the receptors detect bitter compounds, the cilia beat faster, suggesting that the sensing and the motion capabilities of these cellular structures are linked. "On the tongue, bitter substances trigger taste cells to stimulate neurons, which then evoke a response -- the perception of a bitter taste. In contrast, the airway cells appear to use a different mechanism that does not require nerves," said Alok Shah, a UI graduate student and co-first author of the study. "In the airways, bitter substances both activate the receptors and elicit a response -- the increased beating of the cilia -- designed to eliminate the offending material." Shah and co-first author Yehuda Ben-Shahar, Ph.D., an assistant professor of biology at Washington University who was a postdoctoral fellow at the UI when the study was conducted, worked in the lab of senior study author Michael Welsh, M.D. (photo, upper left), UI professor of internal medicine and molecular physiology and biophysics, who holds the Roy J. Carver Chair of Internal Medicine and Physiology and Biophysics. Welsh also is a Howard Hughes Medical Institute investigator. "These findings suggest that we have evolved sophisticated mechanisms to guard ourselves from harmful environmental stimuli," Ben-Shahar said. "Our work also suggests that losing cilia in the lungs, due to smoking or disease, would result in a reduced general ability to detect harmful inhaled chemicals, increasing the likelihood of further damaging an injured lung." In addition to Ben-Shahar, Shah and Welsh, the UI team included Thomas Moninger, assistant director of the UI Central Microscopy Research Facility, and Joel Kline, M.D., UI professor of internal medicine. The study was funded by grants from the National Institutes of Health. Jennifer Brown University of Iowa


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