Day: 02/10/2011

Phenotypic & genetic characterization of Bacillus cereus isolated from the acute diarrhoeal patients

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Bacillus cereus is one of the pathogens responsible for human diarrhoea, mainly due to consumption of contaminated food. The present study was undertaken to determine the occurrence of B. cereus among diarrhoeal patients and its phenotypic and genetic characteristics that determine the virulence and clonal features.
Methods: Stool specimens were collected for two years from acute diarrhoeal patients attending the two referral hospitals in Kolkata. Presence of virulence genes in B. cereus was determined by PCR. Clonality was assessed by pulsed-field gel analysis (PFGE) by restriction digestion with SmaI and NotI enzymes. Enterotoxins were detected by haemolysin assay and using BCET-RPLA kit. Invasion assay was done on Hep-2 cell line. Antimicrobial susceptibility was tested by disc diffusion method.
Results: B. cereus was identified in 54 (3.5%) of the 1536 diarrhoeal cases studied. Majority of the isolates were susceptible to many antibiotics but showed resistant to amoxyclav and cephalosporins. Six genes covering the two different enterotoxic complexes determining the pathogenicity of B. cereus have been characterized by PCR. The nhe genes were detected in a higher proportion than hbl. Except in two, clonal diversity was noticed among 21 B. cereus isolates. Haemolytic enterotoxin was detected in 76 per cent of the isolates. Majority of the isolates (67%) produced in vitro enterotoxin (BCET) confirming its involvement in the infection.
Interpretation & conclusions: Though the presence of B. cereus was not high in patients with diarrhoea, several virulence factors confirm their association with diarrhoea. Distinct clonality was identified in majority of the isolates indicating their origin from different sources.

source: journal of ICMR

Is consuming sugar a problem if you have Alzheimer’s?

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A diet high in carbohydrates with a high glycemic index* is thought by some experts to contribute to the risk for Alzheimer’s disease. The arguments for this position include the following considerations:

  1. Most simply, a high sugar diet may increase the risk of obesity, and obesity is associated with harmful metabolic changes that increase the likelihood of Alzheimer’s disease.
  2. High sugar intake can increase the risk for developing diabetes mellitus, a disease associated with increased risk for Alzheimer’s disease.
  3. Even individuals without diabetes have been shown to develop altered sensitivity to insulin with high sugar intake, and one theory about Alzheimer’s disease suggests that resistance to insulin’s effects and lower levels of insulin-like growth factors in the brain may contribute to the development of this neurological condition.

Studies on animals have lent further support to the connection between sugar and Alzheimer’s disease. Mice bred to be at high risk for brain changes resembling Alzheimer’s disease showed memory impairment and higher levels of amyloid beta deposition in their brains when their water was sweetened with 10% sucrose. Evidence in human subjects suggests that a high sugar diet can interfere with cognition as well. Although the possible link between sugar and Alzheimer’s disease might someday lead to development of a new treatment, it is already sensible for Alzheimer’s disease patients (and truly for the rest of us as well) to monitor sugar intake and limit this to reasonable levels. Diets high in fiber, vegetables, nuts, and beans help regulate blood sugar and support health in a variety of ways. Further research will help to clarify the relationship between a diet high in carbohydrates that have a high glycemic index and Alzheimer’s disease risk.

* High glycemic index means that the carbohydrates are broken down rapidly into glucose or blood sugar. They provide quick energy but contain few nutrients and little fiber, and in large amounts they may damage cells.

source: Alzheimer’s foundatation

Moderate Aerobic Exercise In Older Adults Shown To Improve Memory

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A new study shows that one year of moderate physical exercise can increase the size of the brain’s hippocampus in older adults, leading to an improvement in spatial memory.

The project—conducted by researchers at the University of Pittsburgh, University of Illinois, Rice University, and Ohio State University—is considered the first study of its kind focusing on older adults who are already experiencing atrophy of the hippocampus, the brain structure involved in all forms of memory formation. The study, funded through the National Institute on Aging, appears in the Jan. 31 Proceedings of the National Academy of Sciences (PNAS).

The scientists recruited 120 sedentary older people without dementia and randomly placed them in one of two groups—those who began an exercise regimen of walking around a track for 40 minutes a day, three days a week, or those limited to stretching and toning exercises. Magnetic resonance images were collected before the intervention, after six months, and at the end of the one-year study.

The aerobic exercise group demonstrated an increase in volume of the left and right hippocampus of 2.12 percent and 1.97 percent, respectively. The same regions of the brain in those who did stretching exercises decreased in volume by 1.40 and 1.43 percent, respectively.

Spatial memory tests were conducted for all participants at the three intervals. Those in the aerobic exercise group showed improved memory function, when measured against their performance at the start of the study, an improvement associated with the increased size of the hippocampus. The authors also examined several biomarkers associated with brain health, including brain-derived neurotrophic factor (BDNF), a small molecule that is involved in learning and memory. They found that the increases in hippocampal size were associated with increased amounts of BDNF.

“We think of the atrophy of the hippocampus in later life as almost inevitable,” says Kirk Erickson, professor of psychology at the University of Pittsburgh and the paper’s lead author. “But we’ve shown that even moderate exercise for one year can increase the size of that structure. The brain at that stage remains modifiable.”

“The results of our study are particularly interesting in that they suggest that even modest amounts of exercise by sedentary older adults can lead to substantial improvements in memory and brain health,” says Art Kramer, director of the Beckman Institute at the University of Illinois and the senior author. “Such improvements have important implications for the health of our citizens and the expanding population of older adults worldwide.”

source:  the University of Pittsburgh

Antifungal prophylaxis in hematopoietic stem cell transplant recipients

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Antifungal prophylaxis in hematopoietic stem cell transplant recipients is a rapidly evolving field. For this prophylaxis to be beneficial and cost-effective, the risk of a life-threatening invasive fungal infection (IFI) should outweigh the risks of toxic effects and drug interactions introduced by the antifungal agent used. Not all hematopoietic stem cell transplant recipients have the same risk of IFIs. New prophylactic strategies using risk stratification and new broad-spectrum antifungals have the potential for reducing IFI-associated mortality in these patients. Further refinement of risk stratification and risk/benefit analysis (including pharmacoeconomic analysis) is needed. Stratification of IFI risk could be further sharpened based on emerging genetic and metabolic risk factors. However, 10 years after deciphering the human genome, it is unclear whether the genomic revolution would pay off for identifying the SCT recipients at highest risk for IFIs. Empiricism and reliance on institution-specific epidemiologic data are still expected to be a major part of the ‘art and science’ of risk stratification for fungal infections in SCT.

source: nature medicine

 

Monitoring Pulmonary Artery Pressure in Heart Failure Reduces Hospitalizations

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Using an implantable device to monitor pulmonary artery pressure and transmit the data wirelessly results in lower hospitalization rates for patients with heart failure, according to a Lancet study conducted by the device’s manufacturer.

Some 550 patients with New York Heart Association class III heart failure underwent implantation of the device. Roughly half the patients had their data transmitted daily to clinicians for active use (treatment group), while the rest had their data blocked from clinician access (control group). All patients continued to receive standard-of-care treatment for heart failure.

By 6 months, the rate of new hospitalizations related to heart failure — the primary outcome — was lower in the treatment group than among the controls (31% vs. 44%). The survival rates at 6 months were similar for both groups.

Calling the work “pioneering,” a commentator says the results suggest “that strong consideration should be given to [the device’s use] in appropriate patients.” He cautions, however, “these patients would be in the minority.”

Source: Lancet

Using an implantable device to monitor pulmonary artery pressure and transmit the data wirelessly results in lower hospitalization rates for patients with heart failure, according to a Lancet study conducted by the device’s manufacturer.

Some 550 patients with New York Heart Association class III heart failure underwent implantation of the device. Roughly half the patients had their data transmitted daily to clinicians for active use (treatment group), while the rest had their data blocked from clinician access (control group). All patients continued to receive standard-of-care treatment for heart failure.

By 6 months, the rate of new hospitalizations related to heart failure — the primary outcome — was lower in the treatment group than among the controls (31% vs. 44%). The survival rates at 6 months were similar for both groups.

Calling the work “pioneering,” a commentator says the results suggest “that strong consideration should be given to [the device’s use] in appropriate patients.” He cautions, however, “these patients would be in the minority.”

Source: Lancet