Genetic polymorphism of glutathione S-transferase P1 (GSTP1) in Delhi population and comparison with other global populations.

Glutathione S-transferases (GSTs) belong to a super family of phase II detoxification enzymes, which play an important role in protecting cells from damage caused by endogenous and exogenous compounds by conjugating reactive intermediates with glutathione to produce less reactive water-soluble compounds. In the present study, we determined the frequencies of two polymorphisms in exon 5 and exon 6 of GSTP1 gene in 500 normal individuals from Delhi. GSTP1 polymorphism was analysed by PCR-RFLP using amplification refractory mutation system (ARMS) assay. Two polymorphic sites in GSTP1 (Ile105 â†’ Val105; Ala114 â†’ Val114) have been analysed simultaneously, which results in four alleles: GSTP1*A (wild-type Ile105; Ala114), GSTP1*B (Val105; Ala114), GSTP1*C (Val105; Val114) and GSTP1*D (Ile105; Val114). The GSTP1 allele frequency in Delhi population was 0.663, 0.248, 0.069, and 0.020 for GSTP1*A, GSTP1*B, GSTP1*C, and GSTP1*D respectively. The frequency of Ile105 and Val105 allele was 0.683 and 0.317 respectively and it was calculated for the purpose of comparison with published data where all the four alleles were not analysed. GSTP1 alleles from Delhi population were compared with reported frequencies from all over India, and from other ethnic groups worldwide. This study would provide a basic database for future genetic studies.

Genetic polymorphisms of GSTM1 and GSTT1 genes in Delhi and comparison with other Indian and global populations.

The glutathione S-transferases (GSTs) are involved in the metabolism of many xenobiotics, including an array of environmental carcinogens, pollutants, and drugs. Genetic polymorphisms in these genes may lead to inter- individual variation in susceptibility to various diseases. In the present study, GSTM1 and GSTT1 polymorphisms were analysed using a multiplex polymerase chain reaction in 500 normal individuals from Delhi. The frequency of individuals with GSTM1 and GSTT1 null genotypes were 168 (33.6%) and 62 (12.4%) respectively, and 54 (10.8%) were having homozygous null genotype for both the genes GSTM1 and GSTT1 simultaneously. The studied population was compared with reported frequencies from other neighbouring state populations, as well as with those from other ethnic groups; Europeans, Blacks, and Asians. The prevalence of homozygous null GSTM1 genotype is significantly higher in Caucasians and Asians as compared to Indian population. The frequency of GSTT1 homozygous null genotypes is also significantly higher in blacks and Asians. We believe that due to large number of individuals in this study, our results are reliable estimates of the frequencies of the GSTM1, GSTT1 in Delhi. It would provide a basic database for future clinical and genetic studies pertaining to susceptibility and inconsistency in the response and/or toxicity to drugs known to be the substrates for GSTs.

Parasite killing in malaria non-vector mosquito Anopheles culicifacies species B: implication of nitric oxide synthase upregulation.

BACKGROUND: Anopheles culicifacies, the main vector of human malaria in rural India, is a complex of five sibling species. Despite being phylogenetically related, a naturally selected subgroup species B of this sibling species complex is found to be a poor vector of malaria. We have attempted to understand the differences between vector and non-vector Anopheles culicifacies mosquitoes in terms of transcriptionally activated nitric oxide synthase (AcNOS) physiologies to elucidate the mechanism of refractoriness. Identification of the differences between genes and gene products that may impart refractory phenotype can facilitate development of novel malaria transmission blocking strategies. METHODOLOGY/PRINCIPAL FINDINGS: We conducted a study on phylogenetically related susceptible (species A) and refractory (species B) sibling species of An. culicifacies mosquitoes to characterize biochemical and molecular differences in AcNOS gene and gene elements and their ability to inhibit oocyst growth. We demonstrate that in species B, AcNOS specific activity and nitrite/nitrates in mid-guts and haemolymph were higher as compared to species A after invasion of the mid-gut by P. vivax at the beginning and during the course of blood feeding. Semiquantitative RT-PCR and real time PCR data of AcNOS concluded that this gene is more abundantly expressed in midgut of species B than in species A and is transcriptionally upregulated post blood meals. Dietary feeding of L-NAME along with blood meals significantly inhibited midgut AcNOS activity leading to an increase in oocyst production in An. culicifacies species B. CONCLUSIONS/SIGNIFICANCE: We hypothesize that upregulation of mosquito innate cytotoxicity due to NOS in refractory strain to Plasmodium vivax infection may contribute to natural refractoriness in An. culicifacies mosquito population. This innate capacity of refractory mosquitoes could represent the ancestral function of the mosquito immune system against the parasite and could be utilized to understand the molecular basis of refractoriness in planning effective vector control strategies.

Comparative evaluation of hepatitis C virus infection in serum and liver tissue of patients with chronic liver disease by reverse transcription-polymerase chain reaction.

OBJECTIVE: To undertake a comparative evaluation of diagnostic modalities used in the detection of hepatitis C virus (HCV) infection by serum antibody in ELISA and HCV-RNA in the serum as well as in the liver tissue of the same patients with chronic liver disease by reverse transcription-polymerase chain reaction (RT-PCR). METHODS: Thirty-five subjects comprising 30 cases of cirrhosis of the liver and five cases of chronic hepatitis were included in the study group. The criteria for including the subjects in the study were the availability and quality of serum and liver samples. Serologic ELISA tests for HCV antibody as well as HBsAg and anti-HBc IgG for hepatitis B virus (HBV) were performed on the patient's sera, while RT-PCR was carried out with RNA extracted from both serum and liver biopsies of the patients. Primer sequences selected from the conserved NS5 region of the HCV genome were used in RT-PCR. RESULTS: Of 30 cases of cirrhosis studied, five (16.6%) were anti-HCV antibody positive, while seven (23.3%) were positive for HCV RNA in serum and 10 (33.3%) were positive in liver tissue. One of the anti-HCV antibody-positive patients was negative for HCV RNA in both liver and serum by PCR. All seven patients who showed positivity for HCV RNA in serum were also positive for HCV RNA in the liver. Another three cirrhosis cases (10%) found to be HCV positive in liver tissue were negative for both antibody and HCV RNA in serum. Of the five cases of chronic hepatitis, two (40%) were found to be positive by all three tests. HCV was found to be more prevalent in HBV-infected cases (8/18; 44.5%). However, two of the three cirrhotic patients who showed HCV positivity only in liver PCR tested negative for HBV surface antigen. CONCLUSIONS: RT-PCR detection of HCV RNA in liver tissue is of significant clinical importance and is more reliable than RT-PCR in serum or antibody tests by ELISA. RT-PCR can effectively complement antibody tests for reliable diagnosis, since assessment of HCV positivity by a single test seems to be inadequate. The frequent association of HCV infection with HBV suggests that hepatitis B and C viruses may share similar modes of transmission in India.