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Biomedical subjects

T Chakrabarti

Publications and source records attributed to T Chakrabarti.

At least 37 records · Page 2Linked to original sources
PubMed2003

Genotoxic effects of PAH containing sludge extracts in Chinese hamster ovary cell cultures.

OBJECTIVE: Many studies have been conducted in order to evaluate the genotoxicity of chemicals and waste materials, which utilized in vivo test protocols. The use of animals for routine toxicity testing is now questioned by a growing segment of society. METHODS: Keeping the above fact in mind, we have conducted in the present study the genotoxicity evaluation of oily sludge samples generated from a petroleum refinery and petrochemical industry and ETP sludge from petroleum refinery using DNA damage, chromosomal aberration, p53 protein induction and apoptosis in short term in vitro mammalian Chinese Hamster Ovary cell cultures. RESULTS: It is evident from the results that the oily sludge compounds derived from petroleum refinery and petrochemical industry could cause DNA damage, chromosomal aberration, p53 protein accumulation and apoptotic cell death on exposure to oily sludge extracts in the presence of metabolic activation system (S-9 mix), however, ETP sludge extract could not cause significant genotoxicity in comparison to oily sludge extract and negative control. CONCLUSION: The effect may be attributed to polycyclic aromatic hydrocarbons present in the samples as evidenced from GC-MS.

Animals↗
PubMed2002

Multi-level screening of a proposed hazardous waste treatment and disposal facility site--a case study.

A comprehensive environmental assessment (EA) is a pre-requisite before the site for developing a hazardous waste treatment and disposal facility (HWTDF) is selected. However, the resource limitations, especially for developing countries, often dictate that the detailed EA be restricted to those sites, which are constraint free and have low hazard potentials. Thus, a preliminary screening exercise for assessing the suitability of site for developing the HWTDF needs to be carried out to avoid huge costs involved in detailed EA. While screening a HWTDF site, various factors such as present land use, ecologically sensitive areas, geology and hydrogeology of the area, the quality and quantity of wastes, engineered safeguards, and the operational procedures that need to be adopted. are required to be addressed. In this paper, a multi-level screening criteria employing Remote Sensing, Constraint Mapping, Groundwater Pollution Potential Index (DRASTIC Index), and the Site Ranking was used to assess the suitability of a proposed site for the development of HWTDF. The study helped to identify various constraints at the proposed site and their significance on the development of the HWTDF.

Developing Countries↗
PubMed2002

Pseudomonas indica sp. nov., a novel butane-utilizing species.

The taxonomic position of two butane-utilizing bacteria was studied using a polyphasic approach. Biochemical and physiological characteristics indicated these to be members of the genus Pseudomonas, showing more similarity to Pseudomonas mendocina than to any other species. The major fatty acids found in these two strains also pointed to their similarity to P. mendocina. On the other hand, DNA-DNA hybridization studies with seven related Pseudomonas species belonging to the gamma-Proteobacteria and the deltaTm values of reassociated molecules clearly showed that these two strains do not belong to any of the seven species tested. The 16S rRNA gene was sequenced and compared with the sequences available in the GenBank database. Phylogenetic analysis using the region covering positions 31-1488 (Escherichia coli numbering) confirmed these observations and placed these two strains as members of the authentic Pseudomonas, but not in any existing species of the genus. On the basis of biochemical characteristics, fatty acid profiles, DNA-DNA reassociation and deltaTm values, as well as 16S rRNA gene sequence analyses, these two isolates were shown to belong to one species but to have characteristics distinct from those of validly described species of Pseudomonas (sensu stricto). These strains, therefore, should be recognized as a novel species, for which the name Pseudomonas indica sp. nov. is proposed. The type strain is strain IMT37T (= MTCC 3713T = DSM 14015T).

Base Sequence↗
PubMed2001

Quantitative structure-activity relationships based on functional and structural characteristics of organic compounds.

In the present quantitative structure-activity relationship (QSAR) modeling, organic compounds, including priority pollutants, have been considered and classified based on their functional and structural characteristics. Five physico-chemical characteristics have been used to develop a QSAR model for Pimephales promelas, by means of multiple regression analysis. Collinearity diagnostics was carried out using two different approaches based on condition index and K correlation index. The outlier analysis was carried out using the variable subsets obtained through both the approaches. An attempt has been made to justify the deletion of outliers in each group referring to their physico-chemical characteristics. The expressions obtained by using both approaches provide almost the same prediction accuracy, however, the latter approach resulted in expressions with reduced number of molecular descriptors. The QSARs obtained through this exercise would certainly assist in designing environment-friendly molecules with lower toxicity.

Animals↗
PubMed2001

A novel gene encoding a 54 kDa polypeptide is essential for butane utilization by Pseudomonas sp. IMT37.

Twenty-three propane- and butane-utilizing bacteria were isolated from soil samples collected from oilfields. Three of them have been identified as Rhodococcus sp. IMT35, Pseudomonas sp. IMT37 and Pseudomonas sp. MT40. SDS-PAGE analysis of the membrane of Rhodococcus sp. IMT35 revealed the presence of at least four polypeptides induced by propane. Polyclonal antibody raised against a 58 kDa polypeptide from Rhodococcus sp. IMT35 specifically detected bacteria which were actively utilizing propane or butane. Immunoscreening of a genomic library in lambdagt11 with this antibody resulted in isolation of a clone containing a 4.9 kb EcoRI genomic DNA fragment. This 4.9 kb DNA fragment was found to hybridize specifically with organisms which could grow on propane or butane. This fragment could therefore be used as a probe for detection of such bacteria. A 2.3 kb fragment having an ORF encoding a polypeptide of 54 kDa was identified by screening a genomic library of Pseudomonas sp. IMT37 with this 4.9 kb EcoRI fragment. The sequence of the ORF (designated orf54) was found to be novel. Primer extension and S1 nuclease mapping showed that transcription of the ORF starts at base 283 and it had sequences upstream similar to that of a Pseudomonas promoter (-12, -24 type). Disruption of the ORF by a kanamycin ('kan') cassette prevented the organism from growing on any alkane but did not affect its ability to utilize the respective alkanols and acids, indicating that alcohol dehydrogenase and subsequent steps in the pathway remained unaltered. The mutants had no detectable level of butane monooxygenase activity. Therefore, the product of this gene plays a crucial role in the first step of the pathway and is an essential component of monooxygenase. The findings imply that this bacterium either employs a common genetic and metabolic route or at least shares the product of this gene for utilization of many alkanes.

Bacterial Proteins↗
PubMed1998

Detection of HIV seropositivity during an outbreak of Japanese encephalitis in Manipur.

An epidemic outbreak of Japanese encephalitis (JE) occurred during mid 1995. Sixteen serum samples from patients with history of febrile headache, convulsions, mental confusion, neck rigidity etc. were sent to the Department of Virology, School of Tropical Medicine, Calcutta, in August, 1995. Twelve (75%) showed HIV antibody against JEV. Out of these 12 sera showing HIV antibody titre between 1:40 and 1:160, eight (66.6%) showed IgM antibody, giving the presumptive diagnosis of recent JEV infection. Five of these 16 sera showed HIV seropositivity (31.25%). Concomitant JEV and HIV infection could be detected in 3 cases. However, in 2 sera HIV titre were less than 1:20. This is probably the first documentation of concomitant JEV and HIV infection in the eastern India.

Adolescent↗
PubMed1997

HCV activity in Calcutta--a serological study.

HCV infection, a global public health problem is quite prevalent in India. In the present study conducted during February-July 1996 a total of 153 samples of different age groups and of both sexes were tested by ELISA for detection of Anti-HCV antibody. Anti-HCV was found in 13% of multi-transfused cases and in 8.8% cases with multiple needle-stick injury. Maximum seropositivity (20%) could be observed amongst males between 31-40 yrs. age group. HCV activity was noted more in males (13%) than in females (8.2%) and more relatively in subjects without a history of jaundice (11.5%) than those having the features of jaundice (10.5%). An increasing trend has also been observed amongst the multi-transfused cases in Calcutta.

Adolescent↗
PubMed1996

An in vitro qualitative assay for the detection of antibodies to HIV type 1/2 contained in human saliva.

There is ample evidence that saliva contains secretory antibody against most infections. Therefore, saliva has been recommended as a non invasive, safe and effective alternative to serum, for HIV antibody testing. The present study attempted comparative evaluation of antibody detection by serum and saliva specimens in laboratory by ELISA and Western Blot for diagnosis of HIV infection in the Indian situation. From a study of 42 test sera it is concluded that test apart from its simplicity and reproducibility, is almost free from any false positive and false negative reactions.

Blotting, Western↗
PubMed1994

Plasmid-determined degradative metabolism and halophilism of Vibrio parahaemolyticus.

A set of 25 Kanagawa(+) and Kanagawa(-) strains of V. parahaemolyticus was studied for their ability to degrade hydrocarbons in minimal media. All strains gave positive results with respect to crystal violet (CV), methyl violet, liquid paraffin, benzene, naphthalene and phenol. The CV double ring (CVDR) response had earlier appeared to be a significant pathogenic marker [Chakrabarti et al, Indian J Med Res, 85 (1987) 508]. The CVDR response was found also to be a biodegradative marker, and correlates perfectly well with polymyxin resistance and low level of halophilism (4% NaCl). All these markers (characters) were found to be controlled by a single plasmid in the wild type. Elimination of the plasmid, as confirmed by gel electrophoresis studies, resulted in loss of CVDR response, polymyxin resistance, and acquisition of halophilism at a higher level (> 7%). The massive drainage of industrial effluents, rich in hydrocarbons, in the estuarine areas in many countries might have altered the ecosystem in favour of V. parahaemolyticus and its emergence as a new biodegradative and enterotoxigenic pathogen, contaminating fauna and flora in the littoral sea regions, with increased changes of communicability to humans.

Plasmids↗
PubMed1988

Effects of irrigation with raw and differentially diluted sewage and application of primary settled sewage-sludge on wheat plant growth, crop yield, enxymatic changes and trace element uptake.

An increase in the concentration of Cu, Zn, Cr and Mn, and a decrease in the activities of aspartate amino transferase, alanine amino transferase and peroxidase were observed in the different fractions of wheat plants, following raw and differentially diluted (66% and 50%) sewage irrigation and dry primary settled sewage-sludge amendments of soils. The grain enrichment efficiencies for Cu, Zn and Mn were significantly low under all experimental conditions. On the other hand, the grain enrichment efficiency for Cr was low under all sewage irrigation conditions only. Except in the earheads of wheat plants from sludge-amended soil, catalase activities were significantly low in roots, stems and earheads of wheat plants, under all other treatment conditions investigated. The decrease in the proteinase activity was statistically significant in roots and earheads of sewage-irrigated plants; the activity in the stem was low following irrigation with raw and 66% sewage only. Proteinase activity was also significantly low in all fractions of wheat plants harvested from soil amended with 20 tonnes of sludge per hectare. The observed results appear to be due to an overall decrease in the metabolic status of the plants following sewage irrigation and sludge amendment of soils. Grain yields, however, were not reduced despite this metabolic effect.

Journal Article↗
PubMed1984

Clustering of genes for L-fucose dissimilation by Escherichia coli.

Aerobic and anaerobic L-fucose utilization by Escherichia coli involves an inducible trunk pathway mediated by a permease, an isomerase, a kinase, and an aldolase. Tn5 insertion mutants of a parental strain expressing this pathway constitutively were used to map the positions of the structural genes by transduction. Results from this and previous studies show that all of the structural genes of the L-fucose trunk pathway map between eno and argA at minute 60.2 of the chromosome.

Chromosome Mapping↗
PubMed1984

Constitutive activation of L-fucose genes by an unlinked mutation in Escherichia coli.

Wild-type Escherichia coli cannot grow on L-1,2-propanediol; mutants that can do so have increased basal activity of an NAD-linked L-1,2-propanediol oxidoreductase. This enzyme belongs to the L-fucose system and functions normally as L-lactaldehyde reductase during fermentation of the methylpentose. In wild-type cells, the activity of this enzyme is fully induced only anaerobically. Continued aerobic selection for mutants with an improved growth rate on L-1,2-propanediol inevitably leads to full constitutive expression of the oxidoreductase activity. When this occurs, L-fuculose 1-phosphate aldolase concomitantly becomes constitutive, whereas L-fucose permease, L-fucose isomerase, and L-fuculose kinase become noninducible. It is shown in this study that the noninducibility of the three proteins can be changed by two different kinds of suppressor mutations: one mapping external to and the other within the fuc gene cluster. Both mutations result in constitutive synthesis of the permease, the isomerase, and the kinase, without affecting synthesis of the oxidoreductase and the aldolase. Since expression of the fuc structural genes is activated by a protein specified by the regulator gene fucR, and since all the known genes of the fuc system are clustered at minute 60.2 of the chromosome, the external gene in which the suppressor mutation can occur probably has an unrelated function in the wild-type strain. The internal suppressor mutation might be either in fucR or in the promoter region of the genes encoding the permease, the isomerase, and the kinase, if these genes belong to the same operon.

Escherichia coli↗
PubMed1975

Genetic hybridization at the unlinked thy and str loci of Streptococcus.

The sanguis and pneumoniae species of Streptococcus were used as recipients in transformations from str+ to str-r and from thy- to thy+. The str-r mutations in the two species had been previously shown to be allelic. Homology of the thy- mutations in the two species was demonstrated in the similar phenotypic properties they conferred (death in the absence of thymidine, lack of thymidylate synthetase). The str and thy loci are unlinked in each species.--- When the two species are transformed by both homospecific and heterospecific DNA, the efficiency is always lower in the heterospecific cross. The efficiency of heterospecific transformation is considerably lower at the thy than at the str locus. DNA was extracted from recipients that had integrated markers of heterospecific origin. When such hybrid DNA is tested on the original recipient species, the heterospecific markers are usually as efficient as homospecific markers. When tested on the original donor species, however, the hybrid DNA is usually more efficient than heterospecific DNA. This is true for both thy and str transformation. -- -- Forty independent thy+ hybrids were obtained in the cross of sanguis thy- recipients with pneumoniae thy+ DNA. These hybrids fall into a number of classes based upon the relative efficiency with which their extracted DNA's are able to transfer the thy+ marker into pneumoniae thy- cells. The most efficient of these DNA's exhibits about 20% of the efficiency of homospecific pneumoniae thy+ DNA and three orders of magnitude greater efficiency than heterospecific sanguis thy+ DNA. Thus, very little of the inefficiency of heterospecific transformation of the thy locus is ascribable to a classic restriction mechanism. Rather, the wild-type thy+ loci in the two species appear to differ at multiple sites, and independent heterospecific transfers result in differential extents of integration of these sites. On this basis, the thy+ loci of the two species differ at a greater number of sites than do the respective str+ loci.

Alleles↗