In addition, aspirin increased the susceptibility of H. pylori to antimicrlbials including metronidazole, clarithromycin and amoxicillin. However, the mechanisms remained unknown.
A research team led by Prof. Wang from Peking University First Hospital of China addressed this issue and their results will be published on February 28, 2009 in the World Journal of Gastroenterology .
H. pylori reference strain 26695 and two metronidazole-resistant isolates of H. pylori were included in this study. The effect of aspirin on the permeability of the outer membrane of H. pylori was determined using [7-3H] tetracycline. The effects of aspirin on the expression of OMPs of H. pylori were also determined. Taqman-based real-time quantitative PCR was used to analyze the influence of aspirin on the expression of the related OMPs genes.
They found that the mutations in rdxA gene did not change in metronidazole resistant isolates treated with aspirin. The radioactivity of H. pylori increased when treated with aspirin, indicating that aspirin improved the permeability of the outer membrane of H. pylori . However, the expression of two OMP bands between 55 kDa and 72 kDa altered in the presence of aspirin. The expression of the mRNA of hopA, hopB, hopC, hopD, hopE and hefA, hefB, hefC of H. pylori did not change when treated with aspirin.
Their results indicated that although aspirin increases the susceptibility of H. pylori to metronidazole, it has no effect on the mutations of rdxA gene of H. pylori . Aspirin increases endocellular concentrations of antimicrobials and probably by altering the expression of the outer membrane proteins (OMP) of H. pylori . Their study will help understand the mechanisms of the resistance of H. pylori to antibiotics more intensively and discover a more effective eradication regimen in clinical practice.
wjgnet/
The BDNF gene is characterized by a variant that codes for either the valine (Val) or methionine (Met) amino acids. Individuals carry two copies of each gene, with the Val variant being more common. In the study, subjects carrying two copies of the VAL variant (Val/Val), were compared in their cortisol response to those carrying one copy of the Val and one of the Met (Val/Met).
When looking at the responses of the subjects in the stress testing, it was seen that the Val/Met men and women carriers had nearly equal cortisol levels. However, the men with the Val/Val variant had a higher cortisol response (and therefore a higher reaction to social stress) than the men carrying the Val/Met variant. For the women, surprisingly, the opposite was found: the Val/Val women had a lower cortisol response than the Val/Met women. Why the Val/Val variant produces opposite stress reactions (raising it for the males and lowering it for the females) remains an enigma.
Because of the predominance of the Val/Val type for both sexes, the males showed overall greater stress in the testing than the females.
The Hebrew University researchers point out that their investigation shows the importance of genotyping as an aid in helping to resolve paradoxical observations related to stress-related sex differences and also in providing new insight into understanding how depression and other psycho-neurological illnesses may be the result of a combination of stressful life events and genetic factors.
In conclusion, say the researchers, the study specifically indicates that women with the BDNF Val/Met genotype and men with the Val/Val may be particularly vulnerable to social stress mediated by brain stress system activity.
huji.ac.il/huji/eng/