Prevalence and distribution of Helicobacter pylori cagA and vacA genotypes in the Moroccan population with gastric disease.

Helicobacter pylori infection is the etiologic agent of various gastric pathologies. The severity of disease outcome has been attributed to some H. pylori genotypes, which varies geographically. In Morocco, there are no data regarding the pattern of H. pylori genotypes; therefore, this is the first prospective study conducted in our country to investigate the genotype profiles (vacA and cagA) of H. pylori in patients with gastric pain. Endoscopic biopsies were obtained in patients attending the gastroenterology department of the Hospital University Hassan II of Fez for gastric pain and were directly used for H. pylori detection and genotyping by polymerase chain reaction (PCR). The SPSS software program was used to study the genotype correlation to different clinical outcomes. A total of 429 patients were included in this study, with an infection rate of 69.9%. cagA was detected in 42.3% of cases. However, vacA genotyping reveal a large predominance of s2m2. Infection with multiple strains was detected in 10.8% of cases and incomplete vacA was observed in 31.5%. In Morocco, vacA s1m1 was significantly associated to peptic ulcer diseases, while s2m2 was associated to gastritis. Moroccan H. pylori vacA genotype profiles differ from the Latin American, European, and South African profiles, with more similarities to the North African profile. Because of the small number of cases with gastric cancer, no correlations with H. pylori have been studied, so, further studies will be required in order to highlight the effects of those genes on this disease.

Analysis of T cell receptor beta chain expression by isoelectric focusing following gene amplification and in vitro translation.

We describe a new approach to analysis of T cell receptor diversity based on isoelectric focusing of in vitro translation products of amplified V region genes. The method is illustrated by analysis of V beta 2 profiles in peripheral blood lymphocytes from normal donors. The primers used for V beta 2 analysis spanned the V-(D-)J junction and included the segment from amino acid residue position 53 in the variable region to residue 132 of the constant region. The isoelectric focusing patterns display approximately 13-14 bands of varying intensity. Differences in expression of V beta 2-derived peptides were detected in comparisons of the isoelectric focusing profiles from different individuals, suggesting that the method may be useful for detecting genetically determined, immune response related or disease associated differences in Tcr V region expression. The major isoelectric focusing bands have been interpreted as representing groups of V beta 2 sequences sharing J beta region and NDN region charge similarity. Quantitative differences were detected in V beta 2 profiles of CD4 and CD8 T cell subpopulations indicating there may be selection for different charge characteristics in NDNJ sequences in the two T cell subsets. The method provides a new dimension for the detection of perturbations in the T cell repertoire.

Regulation of c-myc expression by sodium butyrate in the colon carcinoma cell line Caco-2.

The human colon carcinoma cell line Caco-2 spontaneously undergoes enterocytic differentiation in culture. We used sodium butyrate to modify differentiation and growth properties of this cell line and considered c-myc expression as a potential target. Degradation of normal c-myc mRNAs with a half-life of 20 min is not coupled to translation in this cell line, as determined by cycloheximide treatment. We show that butyrate reduces c-myc mRNA levels after a 30 min delay. Butyrate does not affect c-myc expression at the level of transcriptional initiation or elongation, as determined by run-on analysis, but at a post-transcriptional level. Cycloheximide blocks butyrate-dependent reduction of c-myc mRNA levels. Cross-linking experiments show that a 34 kDa protein binds specifically to the c-myc AU-rich instability determinant found in the 3'-untranslated region (ARE). Binding of this protein to the ARE is not modulated by butyrate or cycloheximide. These experiments suggest that butyrate induces a factor involved in c-myc mRNA degradation that differs from the known ARE-associated proteins. Post-transcriptional modification of gene expression could be one of the major targets for this anti-proliferative agent.

Regulation of C-fos expression by sodium butyrate in the human colon carcinoma cell line Caco-2.

We used sodium butyrate to modify the differentiation and growth properties of the Caco-2 colon adenocarcinoma cell line and considered c-fos proto-oncogene expression as a potential target. C-fos is induced by butyric acid very rapidly at a post-transcriptional level and is stimulated transcriptionally at later times. This transcriptional induction does not result in an increase in steady-state mRNA levels. We show by transient transfection assays that the ATF-CRE binding site located between -63 and -54 relative to the c-fos transcriptional start site is a target for butyrate-induced fos transcription. Furthermore, gel retardation assays show an increase in CRE binding activity in cells treated with butyrate. These results demonstrate that butyrate can affect specific transcription factors important for cell growth and differentiation at multiple levels of regulation.