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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)

Researchers Profile Gene Activity In Acutely Ill Idiopathic Pulmonary Fibrosis Patients
New research may help doctors pinpoint when patients with idiopathic pulmonary fibrosis (IPF) are becoming dangerously ill. The findings may also point the way to interventions that could sustain the lives of IPF patients until life-saving transplants could be performed.
News of the day
Spiration Presents Results Of Two Analyses Of Methods For Evaluating Effectiveness Of Bronchial Valve Treatment For Severe Emphysema
Spiration, Inc., a developer of novel medical devices designed to benefit patients with severe and chronic conditions of the lung, presented results of two analyses of methods used for evaluating U.S. Pilot Study effectiveness of bronchial valve treatment for severe emphysema at the annual American Thoracic Society (ATS) International conference taking place in San Diego May 15 to 22, 2009.
Public Health

Promising Antimicrobial Attacks Virus, Stimulates Immune System

A promising antimicrobial agent already known to kill bacteria can also kill viruses and stimulate the innate immune system, according to researchers at National Jewish Health. In a paper appearing online June 4 in the Journal of Investigative Dermatology, Michael Howell, PhD, Assistant Professor of Pediatrics, and his colleagues demonstrated that the synthetic compound CSA-13 can kill vaccinia virus in cell cultures and in mice. Additionally, they showed that CSA-13 stimulates cells to produce their own antimicrobial proteins. "This compound is demonstrating broad effectiveness," said Dr. Howell. "While our experiments were designed to test its ability to attack the vaccinia virus, its immune-stimulating ability was a surprising observation." CSA-13 is one of a class of compounds known as ceragenins, which were developed by Brigham Young University Professor Paul Savage to mimic antimicrobial proteins that occur naturally in the body. The ceragenins are smaller than antimicrobial proteins, and are not as vulnerable to degradation in the body. They have previously been shown to be effective against a variety of bacterial species. Dr. Howell and his colleagues wanted to learn if CSA-13 could fight vaccinia virus infections. Vaccinia virus is closely related to the organism that causes smallpox and is used in smallpox vaccines. However, millions of people in the United States who have had eczema are susceptible to a serious and potentially fatal complication of the vaccination, known as eczema vaccinatum, which occurs when the vaccinia virus infects the skin. Dr. Howell is part of a team, led by Professor of Allergy and Clinical Immunology Donald Leung, MD, PhD, that is seeking protection against this complication so that eczema patients could receive the vaccination in case of a bioterrorist attack with smallpox. CSA-13 demonstrated effectiveness against vaccinia in three different tests. When CSA-13 and vaccinia virus were directly incubated together, the CSA-13 killed more than 96% of the virus at a 25 micromolar concentration. When CSA-13 was added to cells infected with vaccinia, it both reduced vaccinia virus gene expression and allowed more of the infected cells to survive. Finally, the researchers infected immune-compromised mice with vaccinia virus, then applied CSA-13 onto their skin. The CSA-13 reduced the number of skin lesions caused by vaccinia virus. "These experiments definitively showed for the first time CSA-13 can effectively fight vaccinia virus infections," said senior author Dr. Leung. Within their experiments, the researchers found that, in addition to directly killing the virus, CSA-13 also stimulated cells to produce their own antimicrobial proteins, LL-37 and HBD-3. Dr. Howell and colleagues have previously shown that these antimicrobial proteins also exhibit antiviral activity against vaccinia virus. "We knew from our plaque assays, that CSA-13 was directly killing the virus," said Dr. Howell. "But these experiments show that it also stimulates cells to produce their own antimicrobial proteins, which contribute to its disease-fighting capabilities. Our next step is to learn how CSA-13 stimulates cells" own innate immune defenses." This research was funded entirely by the National Institutes of Health. Adam Dormuth National Jewish Medical and Research Center


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