Clastogenic effects of inorganic arsenic salts on human chromosomes in vitro.

Arsenic is well documented as a paradoxical human carcinogen. In West Bengal, several million people were found to be arsenic affected who were exposed to this metalloid principally through drinking water. The arsenic-contaminated drinking water contains both trivalent as well as pentavalent arsenic. In this study, the comparative in vitro cytogenetic effects of two inorganic salts of arsenic, trivalent sodium arsenite (NaAsO(2)) and pentavalent sodium arsenate (Na(2)HAsO4) in three different concentrations, were screened for damage to chromosome and cell division following exposure to human lymphocyte culture. The chromosome-breaking activities in cultured lymphocytes were significantly higher for the compounds with trivalent (NaAsO(2)) than with pentavalent arsenic (Na(2)HAsO(4)), as reflected by the higher chromosomal aberration percentage in the similar doses used. It suggests that sodium arsenite was considerably more clastogenic than sodium arsenate. Moreover, increases in chromosomal aberrations were proportional with the increased dose of exposure for both trivalent and pentavalent forms of arsenic.

Heavy metal blood levels and hearing loss in children of West Bengal, India.

INTRODUCTION: Heavy metals are a major environmental threat in India and there are several health risks associated with it. The aim of this study was to investigate the relationship between the blood levels of lead, cadmium, arsenic, and mercury and a sensoneurial hearing loss in children aged one to ten years. METHOD: Heavy metal blood levels were determined using inductively coupled plasma mass spectrometry, with appropriate quality control. RESULTS: We found significantly higher blood lead concentration (mg/L; Mean ± SE) in children with a hearing loss (53.2 ± 4.4) compared to healthy controls (38.4 ± 4.7)/P = 0 0.03/. CONCLUSION: Children's blood lead levels ≥ 50 mg/L compared to the levels < 10 mg/L were associated with increased probability of hearing loss (OR, 48.8; 95% CI, 41.9-55.6). The differences in the blood levels of cadmium, arsenic, and mercury between the children with a hearing loss and controls were statistically insignificant (P > 0.05).

Black tea (Camellia sinensis) as a chemopreventive agent in oral precancerous lesions.

Oral carcinoma is the most common malignancy found in adult Indian men and the third most common in adult Indian women. About half of all cases are found to be associated with precancerous lesions, chiefly leukoplakia. We wanted to explore the possible benefits of black tea (Camellia sinensis) administered to patients with oral leukoplakia. Eighty-two subjects with oral leukoplakia underwent micronuclei and chromosomal assays on exfoliated oral mucosal epithelium, after which they received black tea in a fixed regimen. The micronuclei assay was repeated at 6 months, and the chromosomal study at 1 year. After the first year, the first 15 patients entered onto this study showed a significant decrease in the micronuclei frequency and chromosomal aberrations, which correlated with the clinical improvement. Several in vitro and animal studies have suggested the efficacy of tea in the chemoprevention of cancer. To the best of our knowledge, this is the first report on the effect of black tea in oral leukoplakia.

Use of black tea in modulating clastogenic effects of arsenic in mice in vivo.

The concentration of arsenic in drinking water has far exceeded the permissible limit of 0.001 mg/L and has reached epidemic proportions, with a maximum of 3.7 mg/L in several districts of West Bengal and in the adjoining Bangladesh. Because inorganic arsenic is a documented human carcinogen, arsenic in drinking water may cause 200,000-270,000 deaths per year from cancer in India alone. Tea has a protective effect against the clastogenicity of arsenic. We investigated whether tea extracts could protect against the damage caused by arsenic in vivo. Our experiments were carried out with black tea in mice with the end points of incidence of chromosomal aberrations and damaged cells. Analysis of variance of chromosomal aberrations showed a significant difference in the toxic effects of arsenic, which were reduced by tea infusion. The frequency of chromosomal aberrations was close to the corresponding effects of tea alone. Continued dietary administration of black tea infusion protects against the chromosome-damaging effects of sodium arsenite at a statistically significant level. The degree of protection increases with duration of tea consumption, which may be attributed to the antioxidant and scavenging properties of tea infusion.

Interaction of different hemoglobinopathies in Eastern India with a view to establish genotype-phenotype correlation.

Analysis of the molecular basis of hemoglobinopathies provides an opportunity to define genotype-phenotype variations as well as establish the origin of mutation. The present study deals with a large cohort of 1,661 cases referred to the counseling unit and 889 individuals from random screening of the population of Tripura. Characterization of mutation in 291 cases (582 alleles) was performed by the PCR-ARMS method using genomic DNA. The haplotype of 56 beta(E) mutation-bearing chromosomes were identified by the RFLP-PCR method. Genotypes were constructed and correlated with hematological and clinical phenotypes. IVS-1nt 5 (G-->C) mutation was observed as the most frequent mutation, followed by codon 30 (G-->C). Production of HbE was significantly (P < 0.001) higher in nontransfusion-dependent Ebeta-thalassemia patients. beta(E) mutation was observed only on four haplotypes linked to framework 2. Type 2 haplotype was observed mainly from chromosomes of Tripura origin, but none from South Bengal. Homozygous E individuals with 1//1 genotype were significantly (P < 0.01) more anemic compared to individuals with 2//2 genotype. This work creates a database of hemoglobinopathy mutations for the population of Eastern India which will facilitate prenatal diagnosis and counseling. Am. J. Hum. Biol. 12:454-459, 2000. Copyright 2000 Wiley-Liss, Inc.

Increase in DNA damage in lymphocytes and micronucleus frequency in buccal cells in silica-exposed workers.

The alkaline single cell gel electrophoresis (comet assay) was applied to study the genotoxic properties of silica in human peripheral blood lymphocytes (PBL). The study was designed to evaluate the DNA damage of lymphocytes and the end points like micronuclei from buccal smears in a group of 45 workers, occupationally exposed to silica, from small mines and stone quarries. The results were compared to 20 sex and age matched normal individuals. There was a statistically significant difference in the damage levels between the exposed group and the control groups. The types of damages (type I -type 1V) were used to measure the DNA damage. The numbers of micronuclei were higher in the silica-exposed population. The present study suggests that the silica exposure can induce lymphocyte DNA damage and produces significant variation of micronuclei in buccal smear.

Molecular and hematological characterization of hemoglobin H disease in the Bengali population of Kolkata, India.

This article reports the incidence of hemoglobin H (HbH) disease among the nontribe Bengali population living in South 24-Parganas of West Bengal. Among 105 patients with unexplained anemia with moderate hematological parameters referred to our laboratory over a period of 2 years, 17 cases (16.19%) were found to have HbH disease identified by hemoglobin electrophoresis. Molecular investigation for two common mutations of α-thalassemia (-3.7α, -4.2α) was carried out in these 17 cases using DNA extraction followed by multiplex polymerase chain reaction. Presence of these common mutations were identified in 10 of the 17 cases. Of them, -3.7α homozygotes (-3.7α/-3.7α), -3.7α/-4.2α double heterozygotes, and -4.2α homozygotes (-4.2α/-4.2α) were found in three, five, and one patient, respectively. The South East Asian (- -SEA) mutation was searched for in one Chinese patient because this mutation is very common among the Chinese population, and he showed the presence of this mutation. Seven patients with HbH disease did not show any of these mutations. These patients may have other α mutations, which need to be studied further. The need to screen for α-thalassemia at the molecular level in patients with unexplained anemia and its implication in the future generation of our society have been discussed in this article.

Association of genotoxic effects of arsenic with haematological malignancy in West Bengal.

Arsenic is a naturally occurring metalloid that has been associated with increased incidence of human cancers in certain highly exposed populations. This present work aimed to study whether arsenic plays any role in the increased incidence of blood cancer among residents of West Bengal, India, which is one of the worst arsenic-affected areas of the world. Our study group included both blood cancer patients and age-, sex-matched healthy controls. We studied the arsenic concentration in the hair and nail samples of our study group. We found significantly higher arsenic concentration in the biological tissues of patients, which also correlated with their greater incidence of chromosomal aberrations. Thus, arsenic may act as a predisposing factor for blood cancer.

Incidence of anemia and effect of nutritional supplementation on women in rural and tribal populations of eastern and northeastern India.

Screening of women of child bearing age among the tribal and rural population of different north eastern and eastern states of India was performed. More than 50% of women in some areas were found to have anemia. As part of the study nutritional supplementation was given to a proportion of the anemic population, comparing the effects of Spirulina, a compound containing vitamins and micronutrients and an iron-folic acid-B12 supplement. Follow-up of the cases was done over a period of one year and the impact of supplementation and a comparison of the two compounds made.

Anemia and hemoglobinopathies in tribal population of Eastern and North-eastern India.

It is estimated that out of approximately 31.4 million people living in North-eastern India, about 8.1 million are tribal people of the hills and plains. Among four of the seven north-eastern states, tribal people are in majority. Arunachal Pradesh is made of approximately 24 major tribal groups, which constitute about 70% of the total population, Tripura 29% and in Assam constitutes 11%. A total of 1726 cases were randomly selected in this study, out of which 1263 cases were from North-east India, namely from Arunachal Pradesh, Assam, Tripura and the rest were from West Bengal. Hematological parameters were estimated and agarose gel electrophoresis for identification of the Hb variants was performed. DNA was isolated, amplified and analysed by PCR-ARMS technology. The incidence of anemia among the tribal people of Assam was 59.82%, in Arunachal Pradesh 53.77% and Tripura 57.45%. The presence of hemoglobinopathies and thalassemia account for anemia in a sizeable population of the north-eastern states in certain tribes and urgent health resources are needed to deal with this. HbE appears to be the commonest hemoglobin among the different tribes of north-east.

Alpha-thalassemia among tribal populations of Eastern India.

Five hundred and thirteen unrelated subjects belonging to various tribes of West Bengal, Arunachal Pradesh and Assam in Eastern India, were screened for the presence of alpha-thalassemia (thal) gene deletion(s) as a possible cause of unexplained anemia (Hb < 11 g/dL and/or MCH <28 pg, MCV < 78 fL). As reported earlier, beta-globin gene mutant alleles were found with a frequency of up to 20% in some tribes. In the present study, alpha-globin gene deletion alleles were found in 18% of subjects from West Bengal, 3.9% from Arunachal Pradesh and 3.84% from Assam tribesmen. Coexistence of alpha- and beta-globin gene abnormalities was observed in up to 18% of some tribal groups. The high inbreeding rate and lack of appropriate medical care make these populations particularly vulnerable.

Spectrum of beta-thalassemia mutations and their association with allelic sequence polymorphisms at the beta-globin gene cluster in an Eastern Indian population.

In this report, the spectrum of beta-thalassemia mutations and genotype-to-phenotype correlations were defined in large number of patients (beta-thalassemia carriers and major) with varying disease severity in an Eastern Indian population mainly from the state of West Bengal. The five most common beta-thalassemia mutations were detected, which included IVS1-5 (G-->C), codon 15 (G-->A), codon 26 (G-->A), codon 30 (G-->C), and codon 41/42 (-TCTT). These accounted for 85% in 80 beta-thalassemic alleles deciphered from 56 patients, including beta-thalassemia major and carriers, and 15% of alleles remained uncharacterized in these patients. Expression of the human beta-globin gene is regulated by an array of cis-acting DNA elements, including five DNase I hypersensitive sites (HSs) in the locus control region (LCR), promoters that incorporate certain silencer elements, and enhancers at 3' of the beta-globin gene. For detailed studies and to understand the molecular basis of beta-thalassemia, we studied two groups of subjects: a group of 12 patients from four families having beta-thalassemia major and carrier phenotype and a control group of 26 healthy individuals. In these two groups, we examined portions of the beta-globin gene locus control region HSs 1, 2, 3, and 4, which included the (CA)(x)(TA)(y) repeat motif, the (AT)(x)N(y)(AT)(z) repeat motif, the inverted repeat sequence TGGGGACCCCA, the promoter region of the (G)gamma-globin gene, an (AT)(x)(T)(y) repeat 5' of the silencer region, and the beta-globin gene and its 3' flanking region. We investigated the allelic sequence polymorphisms in these regions and their association with the beta-thalassemia mutations to know the possible genotype-phenotype relationship in beta-thalassemia patients. An analysis of cis-acting regulatory regions showed varied sequence haplotypes associated with some frequent beta-thalassemia mutations in this Eastern Indian population.

Study of the single nucleotide polymorphism (SNP) at the palindromic sequence of hypersensitive site (HS)4 of the human beta-globin locus control region (LCR) in Indian population.

LCR, a genetic regulatory element, was examined in beta-thalassemia patients who do not show any mutation in the beta-globin genes. We sequenced LCR-HS2, HS3, and HS4 in samples from 16 such patients from the Indian population and found only one SNP A-G in the inverted repeat in HS4. A significant association was observed between the G allele and occurrence of beta-thalassemia by Fisher's exact test. The AG and GG genotypes showed higher relative risk as compared to the AA genotype. We also observed linkage disequilibrium between the A/G polymorphism and the AT-rich motif of the LCR HS2 region, suggesting that the G allele could be an evolutionarily new mutation in the study population.