Ramesh Bamezai

Momordica charantia (Bitter Gourd) peel, pulp, seed and whole fruit extract inhibits mouse skin papillomagenesis

The present study was designed to elucidate the inhibitory potential of Momordica charantia (Bitter Gourd) peel, pulp, seed and whole fruit extract on mouse skin papillomagensis with the modulatory influence of biotransformation system enzymes. Topical application of Momordica whole fruit extract (100 microl/animal per day) during the peri-initiation stage (1 week before and 2 weeks after initiation) by 7,12-dimethylbenz[a]anthracene (DMBA) and/or during the tumor promotion stage reduced the (i) tumor burden to 4.26, 3.72 and 3.11 (positive control value: 5.42); (ii) cumulative number of papillomas to 81, 67 and 53 (positive control value: 103); and (iii) percent incidence of mice bearing papillomas to 100, 94 and 94, respectively (positive control value: 100). In a comparison of the anticarcinogenic efficacy of Momordica peel, pulp, seed and whole fruit extract (100 microl/animal per day), after topical treatment during the peri-initiation and during the tumor promotion stage, revealed the modulation of the (i) tumor burden (tumors/mouse) to 3.06, 3.61, 3.17 and 3.11; (ii) cumulative number of papillomas to 49, 65, 54 and 53; and (iii) percent incidence of mice bearing papillomas to 84, 100, 94 and 94, respectively. Significant elevation in the sulfhydryl (-SH) level was observed in the liver and skin tissues by the topical treatment of Momordica peel, pulp, seed and whole fruit extract. Elevation in the hepatic levels of cytosolic glutathione S-transferase (GST) and microsomal cytochrome b, was also observed by the topical treatment of Momordica peel, seed and whole fruit extract. The results suggest the maximum chemopreventive potential is in the Momordica peel. Equivocal efficacy is in the Momordica seed and whole fruit extract. Biotransformation system enzymes may be the cause of this reduced papillomagenesis.

Association study of major risk single nucleotide polymorphisms in the common regulatory region of PARK2 and PACRG genes with leprosy in an Indian population

Single nucleotide polymorphisms (SNPs) in the regulatory region shared by PARK2 and PACRG have been identified as major risk factors for leprosy susceptibility in two ethnically distinct populations. We investigated the association of six SNPs present in this regulatory region with leprosy susceptibility in an Indian population. Genotyping was performed by direct PCR sequencing in 286 leprosy patients and 350 healthy controls. Our results showed that T allele of SNPs PARK2_e01 (−2599) and 28 kb target_2_1 was significantly associated with susceptibility to leprosy per se (P=0.03 and 0.03, respectively). The T allele of SNPs PARK2_e01 (−2599) showed a significant recessive effect (P=0.04) in susceptibility to leprosy in Indian population as against the dominant effect of haplotype T-C of the major risk SNPs PARK2_e01 (−2599) and rs1040079 in Brazilian and Vietnamese population. However, after bonferroni corrections, these significant differences disappeared. Haplotype analysis also showed a lack of significant association of any haplotype with cases or controls. The noninvolvement of major risk SNPs in the regulatory region of PARK2 and PACRG locus with leprosy susceptibility in Indian population highlights the differential effect of these SNPs in regulating genetic susceptibility to leprosy in different populations.

Modulatory influence of arecoline on the phytic acid-altered hepatic biotransformation system enzymes, sulfhydryl content and lipid peroxidation in a murine system

The potential of arecoline alkaloid, by direct or translactational exposure, to modify the chemopreventive efficacy of phytic acid, via modulation of hepatic biotransformation system enzymes and antioxidant defence mechanism, was assessed in a murine system. Phytic acid (500 or 1000 mg/kg b.w. per day) induced a statistically significant increase in the hepatic levels of glutathione S-transferase (GST) and sulfhydryl (-SH) in murine females and suckling neonates. The elevated levels of hepatic cytochrome b5 (Cyt. b5), cytochrome P-450 (Cyt. P-450) and the depleted level of malondialdehyde (MDA) were observed in the lactating mice. Arecoline (20 mg/kg b.w. per day) alone did not modulate the hepatic GST and -SH levels although it induced a statistically significant increase in the levels of Cyt. b5, Cyt. P-450 and MDA in the murine system. Phytic acid-modulated hepatic levels of phase II components were depressed whereas phase I enzymes and lipid peroxides were further elevated by arecoline-plus-phytic acid treatment. The implications of direct or translactational modulation in the competing potential pathways of biotransformation system enzymes in the process of chemical carcinogenesis are discussed.

Functional IFNG polymorphism in intron 1 in association with an increased risk to promote sporadic breast cancer

Interferon (IFN)-γ is an important Th1 cytokine, which plays a role in immune surveillance and anti-tumor activity. A case-control study involving 54 sporadic breast cancer patients and 144 healthy controls was carried out to explore if the genotype variation of a proposed non-specific enhancer element with a dinucleotide (CA)n repeat in intron 1 has a role in the susceptibility to promote sporadic breast cancer. Genotype analysis carried out by single-strand length polymorphism and confirmed by sequencing showed an increased frequency of (CA)12 allele (P<0.001) and decreased frequencies of (CA)15 (P<0.01) and (CA)>15 (p<0.001) alleles in sporadic breast cancer patients as compared to controls. Further, in vitro reporter assays for (CA)12 and (CA)15 alleles suggested these to be associated with decreased and increased expressions, respectively, suggesting the (CA)12/(CA)12 background to act as one of the factors that could lead to low production of IFN-γ. The study concludes that such genetic background for a proposed non-specific enhancer element with (CA)n repeat within intron 1 of the IFNG gene might put the individuals with this genotype at higher risk to promote the development of sporadic breast cancer due to a resultant compromised immune surveillance.

Effect of arecoline on the curcumin‐modulated hepatic biotransformation system enzymes in lactating mice and translactationally exposed F1 pups

The present study assesses the potential of arecoline alkaloid to translactationally modify the chemopreventive efficacy of curcumin (diferuloyl methane) via neonatal modulation of hepatic biotransformation system enzymes. Curcumin (0.4 g/kg body wt/day) induced a significant increase in the hepatic levels of glutathione-S-transferase (GST), acid-soluble sulfhydryl (SH), cytochrome b5, and cytochrome P-450 in lactating dams and F1 pups at 14 or 21 days. Arecoline (20 mg/kg body wt/day) could not modulate the hepatic GST and SH levels, although significant induction was observed in the levels of cytochrome b5 and cytochrome P-450 in dams and suckling pups. Significant enhancement of hepatic GST, SH, cytochrome b5, and cytochrome P-450 levels was observed in groups treated with curcumin+arecoline. Curcumin-induced levels of GST and SH were depressed whereas cytochrome b5 and cytochrome P-450 were further elevated by curcumin+arecoline treatment. The elevated levels of Phase I enzymes were more significant with exposure to curcumin+arecoline than with arecoline exposure alone. Modulation in competing potential pathways of biotransformation system enzymes in lactating dams may affect the rate and extent of maternal detoxication and thus influence the passage of metabolites of administered xenobiotics to the suckling neonate.

Human mtDNA hypervariable regions, HVR I and II, hint at deep common maternal founder and subsequent maternal gene flow in Indian population groups

AbstractWe have analysed the hypervariable regions (HVR I and II) of human mitochondrial DNA (mtDNA) in individuals from Uttar Pradesh (UP), Bihar (BI) and Punjab (PUNJ), belonging to the Indo-European linguistic group, and from South India (SI), that have their linguistic roots in Dravidian language. Our analysis revealed the presence of known and novel mutations in both hypervariable regions in the studied population groups. Median joining network analyses based on mtDNA showed extensive overlap in mtDNA lineages despite the extensive cultural and linguistic diversity. MDS plot analysis based on Fst distances suggested increased maternal genetic proximity for the studied population groups compared with other world populations. Mismatch distribution curves, respective neighbour joining trees and other statistical analyses showed that there were significant expansions. The study revealed an ancient common ancestry for the studied population groups, most probably through common founder female lineage(s), and also indicated that human migrations occurred (maybe across and within the Indian subcontinent) even after the initial phase of female migration to India.

Analysis of Indian population based on Y-STRs reveals existence of male gene flow across different language groups.

A study of three different Y-specific microsatellites (Y-STRs) in the populations from Uttar Pradesh (UP), Bihar (BI), Punjab (PUNJ), and Bengal (WB), speaking modern indic dialects with its roots in Indo-Aryan language, and from South of India (SI), speaking the South Indian languages with their root in Dravidian language, has shown that the predominant alleles observed represent the whole range of allelic variation reported in different population groups globally. These results indicate that the Indian population is most diverse. The similarity between the allelic variants between the populations studied by others in Africa and Asia and in this study between WB, PUNJ, UP, BI, and SI are of interest. It demonstrates that these population groups, housed in eight states of the country in different geographic locations, broadly correspond with Indo-Aryan and Dravidian language families. Further, our analyses based on haplotype frequency of different marker loci and gene diversity reveals that none of the population groups have remained isolated from others. High levels of haplotype diversity exist in all the clusters of population. Nonsignificant results based on Markov chain steps and Slatkins linearized genetic distances indicate that there has been migration to and from in these population groups. However, some of the marginally significant interpopulation differences could be attributed to one or more of the castes with high diversity embedded within the population groups studied. Haplotype sharing between populations, F(ST) statistics, and phylogenetic analysis identifies genetic relatedness to be more between individuals belonging to two different states of India, WB and PUNJ, followed by UP and BI, whereas SI branched out separately.

DNA Methyltransferase1 (DNMT1) Isoform3 methylates mitochondrial genome and modulates its biology

Here we demonstrate localization of the isoform3 of DNA Methyltransferase1 (DNMT1) enzyme to mitochondria, instead of isoform1 as reported earlier. The fused DNMT1-isoform1, reported earlier to localize in mitochondria, surprisingly showed its exclusive presence inside the nucleus after its ectopic expression; and failed to localize in mitochondria. On the other hand, ectopically expressed DNMT1-isoform3 targeted itself to mitochondria and subsequently methylated CpG regions in the mitochondrial genome. In addition, overexpression of DNMT1-isoform3 affected mitochondrial biology and regulated its function. Under different conditions of oxidative and nutritional stress, this isoform was down-regulated, resulting in hypomethylation of mitochondrial genome. Our study reveals how DNMT1-isoform3, instead of isoform1, is responsible for mtDNA methylation, influencing its biology.

T-cell receptor-γ rearrangement and c-myb methylation in MNNG-exposed Bloom syndrome B-lymphoblastoid cells

The MNNG-exposed Bloom syndrome (BS) B-lymphoblastoid cell population (BS-MNNG), when analyzed for aberrant genetic variations, showed an illegitimate rearrangement at the TCR-gamma gene and hypermethylation at the c-myb protooncogene. The TCR-gamma rearrangement involved a Vgamma9 segment corresponding to a 4 kb band detected with a Jgamma-specific probe in HindIII-digested DNA samples from BS-MNNG cells only. These variations were not shown by unexposed BS cells or both MNNG-exposed and unexposed normal (GA3) B-lymphoblastoid cells.

Postnatal efficacy of Momordica charantia peel, pulp, seed and whole fruit extract in the detoxication pathway of suckling neonates and lactating mice.

The present study evaluates the postnatal efficacy of Momordica charantia peel, pulp, seed and whole fruit extract via assessing the modulation in the biotransformation system enzymes of suckling neonates and lactating mice. The peel, seed or whole fruit extract of Momordica (100 microl/animal/day) independently induced a significant increase in the hepatic levels of glutathione S-transferase (GST) and acid soluble sulfhydryl (-SH) after 14 or 21 days treatment in lactating dams (P < 0.01) and translactationally exposed neonates (P < 0.05). However, the elevation (P < 0.05) in hepatic cytochrome b5 (Cyt. b5) and cytochrome P-450 (Cyt. P-450) levels was observed only in the lactating dams treated with the respective extracts of peel, seed or whole fruit of Momordica. In lactating dams and suckling neonates the modulated levels of biotransformation system enzymes suggest the potential for the translactational passage of active principle(s) and/or metabolites of Momordica.