RESUMO
Background: elevated level of plasma homocysteine has been related to various diseases. Patients with hyperhomocysteinemia can develop hepatic steatosis and fibrosis. We hypothesized that oxidative stress induced by homocysteine might play an important role in pathogenesis of liver injury. Also, the cellular response designed to combat oxidative stress is primarily controlled by the transcription factor Nrf2, a principal inducer of anti-oxidant and phase II-related genes
Methods: hepG2 cells were treated with homocysteine in different time periods. Glutathione content was measured by flowcytometry. Using electrophoretic mobility shift assay [EMSA] and Western-blotting, anti-oxidant response element [ARE]-binding activity of Nrf2 for heme ocygenase-1 [HO-1] was demonstrated. Real time RT-PCR and Western-blotting were performed to evaluate whether homocysteine was able to induce mRNA and protein expression of HO-1
Results: the role of Nrf2 in cellular response to homocysteine is substantiated by the following observations in HepG2 cells exposed to homocysteine [i] Western-blotting revealed that Nrf2 is strongly stabilized and became detectable in nuclear extracts. [ii] EMSA demonstrated increased binding of Nrf2 to oligomers containing HO-1 promoter-specific ARE-binding site. [iii] Real time RT-PCR and Western-blotting revealed increased mRNA and protein expression of inducible gene HO-1 after treatment with Homocysteine
Conclusion: data presented in the current study provide direct evidence that the immediate cellular response to oxidative stress provoked by homocysteine is orchestrated mainly by the Nrf2-ARE pathway. Therefore, induction of Nrf2-ARE-dependent expression of HO-1 could be a therapeutic option for hepatic cells damage induced by homocysteine. Iran. Biomed. J. 17 [2]: 93-100, 2013
RESUMO
To identify and classify Iranian isolates of diarrheagenic Escherichia coli E. coli on the basis of presence of virulence genes and to determine antibiotic susceptibility of isolated strains. The current cross-sectional study was conducted in 2005 at the Pasteur Institute, Tehran, Iran. One hundred and ninety-three diarrheagenic E. coli isolated from diarrheal patients in different regions of Iran were included in current study. Virulence factor genes for diarrheagenic E. coli were detected by polymerase chain reaction. Of the 193 diarrheagenic E. coli detected by PCR, 86 44.5% were Shiga toxin-producing E. coli STEC, 74 38.4% enteropathogenic E. coli EPEC, 19 9.8% enteroaggregative E. coli, and 14 7.3% enterotoxigenic E. coli isolates. Susceptibility to 12 clinically important antimicrobial agents was determined for 193 strains of diarrheagenic E. coli. A high incidence of resistance to tetracycline 63%, ampicillin 62%, streptomycin 56%, amoxicillin/clavulanic acid 44.5%, trimethoprim/sulfamethoxazole 39.5%, and cephalothin 37% was observed. The STEC and EPEC strains with high resistance to tetracycline and ampicillin, but highly susceptible to quinolones are among the most important causative agent of diarrhea in Iran. This study suggests that antimicrobial resistance is widespread among E. coli strains colonizing Iranian patients. Guidelines for appropriate use of antibiotics in developing countries require updating