Segmental differences in Slc26a3-dependent Cl- absorption and HCO3- secretion in the mouse large intestine in vitro in Ussing chambers

The anion exchanger slc26a3 (DRA), which is mutated in congenital chloride-losing diarrhea, is expressed in the apical membrane of the cecum and middle-distal colon but not in the proximal colon of rodent large intestines. To elucidate the functional roles of DRA, we measured unidirectional 36Cl- and 22Na+ fluxes and HCO3- secretion in vitro in each of these segments using DRA-KO mice. Robust Cl- absorption, which was largely abolished after DRA deficiency, was present in the cecum and middle-distal colon but absent in the proximal colon. Na+ absorption was present in all three segments in both the control and DRA-KO mice. The luminal-Cl--dependent HCO3- secretions in the cecum and middle-distal colon were abolished in the DRA-KO mice. In conclusion, DRA mediates Cl- absorption and HCO3- secretion in the mouse cecum and middle-distal colon, and may have roles in H2O absorption and luminal acid/base regulation in these segments.

Interferon-alpha therapy in patients dually infected with hepatitis C virus and GB virus C/hepatitis G virus--virological response of HGV and pretreatment HGV viremia level

BACKGROUND/AIMS

The response to interferon-alpha (IFN) therapy of recently isolated GB virus C and hepatitis G virus (HGV) is still unclear. To investigate the biochemical and virological response to IFN therapy in patients with chronic hepatitis C virus (HCV) infection concomitantly infected with HGV, 196 patients with HCV who had received IFN therapy were retrospectively studied.

METHODS

HGV and HCV RNA were detected by reverse transcription nested polymerase chain reaction (RT-PCR). Serum HGV RNA levels were quantified by competitive RT-PCR. The HGV genotype was detected by restriction fragment length polymorphism analysis using the PCR products.

RESULTS

Of 196 patients, 16 (8.2%) were positive for both HCV and HGV RNA before IFN therapy. There were no significant clinical and virological differences between the patients with dual infection and those with only HCV infection. During the therapy, a decrease or loss of serum HGV RNA level was observed in these patients. Six months after cessation of the therapy, five of 16 patients became negative for HGV RNA by RT-PCR. The pretreatment HGV RNA level of the patients who lost HGV RNA after cessation of IFN was low (median=10(3) copies/ml), compared to the level (median=10(7) copies/ml, p<0.01) in the patients with positive HGV RNA after the therapy. The HGV genotype of these 16 patients was the same type.

CONCLUSIONS

These data suggest that: 1) there is no significant difference in response to IFN therapy between patients with dual and single infection; 2) HGV shows sensitivity to IFN therapy; and 3) in the patients who show a low pretreatment HGV RNA level, serum HGV RNA becomes undetectable by RT-PCR after cessation of IFN therapy.

Interferon-alpha therapy for individuals with normal serum alanine aminotransferase levels before treatment

While interferon (IFN) therapy is approved for patients with chronic hepatitis C infection, the effectiveness of IFN therapy for anti-hepatitis C virus (HCV)-positive individuals with normal ALT levels remains poorly understood. Twenty-five individuals (M:F = 9:16; age = 51.8 +/- 15.1 years) who showed a normal alanine aminotransferase (ALT) level (< 30 IU/L) at least 6 months before treatment and were positive for both anti-HCV and serum HCV-RNA by reverse transcription polymerase chain reaction (RT-PCR) were studied. Of these, 16 received IFN therapy for 24 weeks (780 million units total IFN-alpha 2b) and nine were followed for 12 months as controls. The serum HCV-RNA level was determined by bDNA assay and HCV genotype was detected by enzyme immunoassay. All were shown to have chronic hepatitis by liver biopsy. Six (37.5%) of 16 individuals lost serum HCV-RNA by RT-PCR 6 months after cessation of therapy (complete response; CR), while the remaining individuals were defined as non-responders (NR). Of the six individuals in the CR group, five had HCV type 2 infection, compared with none of 10 individuals in the NR group (P < 0.01). There was a trend towards a lower pretreatment viraemia level in the CR group than in the NR group. These data suggest that IFN therapy for individuals with HCV type 2 infection and normal ALT levels was effective.

Usefulness and limitation of phylogenetic analysis for hepatitis C virus core region: application to isolates from Egyptian and Yemeni patients

We report here the nucleotide sequences of the core region of HCV isolates from Egyptian and Yemeni patients and the method for classifying these HCV isolates by phylogenetic analysis. Sequence comparison suggested that the genotypes of these isolates were the same. Preliminary phylogenetic analysis of the HCV core region indicated that the genotypes of both isolates were 1c. However, an additional phylogenetic tree of the HCV core region constructed using a greater number of HCV isolates than that used in the preliminary analysis and on the basis of alignment of nucleotide sequences in an appropriate length indicated that the genotypes of these isolates were 4 and not 1c. For a more detailed analysis, the nucleotide sequences of the HCV E1 region as well as the core region for the same Yemeni patient were determined. A phylogenetic tree of the E1 region confirmed that the genotype of the HCV isolate from the Yemeni patient was 4. These data indicate that even when classifying HCV isolates using phylogenetic analysis, the misclassification would occur if care is not taken regarding the number and sequence lengths of the isolates included in the analysis.

Hepatitis C virus (HCV) subtype prevalence in Chiang Mai, Thailand, and identification of novel subtypes of HCV major type 6

Subtype analysis of hepatitis C viruses (HCVs) obtained from patients with chronic liver disease in Chiang Mai, Thailand, was performed. Of 46 HCV isolates, 13 (28%) were shown to belong to HCV subtype 3a (HCV-3a), 10 (22%) to belong to HCV-1a, 7 (15%) to belong to HCV-1b, 1 (2%) to belong to HCV-3b, and 1 (2%) to belong to a variant group, as determined from partial nucleotide sequences of the NS5B region of the viral genome. Analysis of 5' untranslated region sequences identified five other isolates (11%) of HCV type 1 and two other isolates (4%) of type 3. Detailed phylogenetic positions for the variant described above and those previously obtained from blood donors and drug addicts in Chiang Mai were determined by a six-parameter neighbor-joining method on the basis of core, E1, and NS5B region sequences. The results revealed that those sequence variants represent novel subtypes of HCV type 6. The HCV type 6 isolates appear to be antigenically different from isolates of HCV types 1 and 2, as determined by a serotyping method that utilizes recombinant peptides corresponding to a portion of the NS4 protein. The significance of subtype analysis around this area is discussed.