what's the buzz..

what's the buzz..

How antibiotics enable gut infections

 
A new study could help pinpoint ways to counter the effects of the antibiotics-driven depletion of friendly, gut-dwelling bacteria.

Justin Sonnenburg, PhD, assistant professor of microbiology and immunology at the Stanford University School of Medicine and the senior author of the study said that the study specifically supports the suggestion that our resident microbes hold pathogens at bay by competing for nutrients.  The particular nutrients Sonnenburg’s team looked at were sialic acid and fucose, a couple of members of the sugar family.

Researchers experimented on mice that had been born and bred in a germ-free environment. These mice's guts were devoid of bacteria, unlike normal mice, which harbour hundreds of bacterial species in their bowels just as humans do. Into these germ-free mice the investigators introduced a single bacterial strain, Bacteroides thetaiotaomicron.

Introducing one friendly and one pathogenic bacterial strain into the guts of the formerly germ-free mice, the scientists were able to show that, in this approximation of an antibiotic-decimated gut-microbe ecosystem, the levels of sialic acid soared to high levels in the absence of a complete set of intestinal microbes that ordinarily would keep those levels from climbing.

In the presence of these sugars and absence of competition, both pathogens were able to replicate more rapidly. B. theta generated a sialic-acid surplus that, in the absence of the other hundreds of normal bacterial species, were bequeathed to the pathogenic strains.

Aerosols and greenhouse gas have same effect on rainfall

The effect of greenhouse gases and aerosols on spatial patterns of rainfall change are similar, regardless of their distinct properties, a new study has revealed.

A team of scientists from the University of Hawaii at Manoa’s International Pacific Research Center (IPRC) and Scripps Institution of Oceanography has provided important new insights based on results from experiments with three state-of-the-art climate models.

Even though aerosols and greenhouse gases are concentrated in vastly different regions of the earth, all three models revealed similar regional effects on rainfall over the ocean.

Lead-author Shang-Ping Xie, a professor of climate science and first Roger Revelle Chair in Environmental Science at Scripps noted that both aerosol-induced and greenhouse-gas-induced changes in rainfall appear to be mediated by the spatial patterns of sea surface temperature.

"Although much of the aerosol research has focused on microphysical processes, over the ocean the climate response to aerosols appears to be insensitive to details of the micro-processes in clouds," Xie said.

The researcher added that the climate changes induced by greenhouse gases and by aerosols share a common set of ocean-atmospheric feedback structures, explaining the spatial resemblance between the two types of response.

Big belly raises death risk in heart attack survivors

High waist circumference, severe obesity has been linked with the greatest risk of death in heart attack survivors, according to a research.

 Professor Tabassome Simon said that the impact of obesity on long term mortality and cardiovascular complications in the general population has been the object of recent debate and much emphasis has also been given to the deleterious role of abdominal obesity.  Simon said that at the time of a heart attack, early mortality tends to be lower in obese patients, a phenomenon well known in critical care situations and described as the ‘obesity paradox’.

At 5 years, absolute mortality was highest in the leanest patients (BMI less than 22 kg/m2) and lowest in patients with BMI between 25 and 35 kg/m2 (i.e. overweight and mild obesity). Patients with severe obesity (BMI = 35 kg/m2) had a markedly increased mortality after 3 years. Severe abdominal obesity (waist circumference more than 100 cm in women and more than 115 cm in men) was also associated with increased long-term mortality.

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