Search PubMed⌕ Search

Biomedical subjects

A K Bhattacharya

Publications and source records attributed to A K Bhattacharya.

At least 19 recordsLinked to original sources
PubMed2000

A simple microbiological assay for the stereospecific differentiation of alpha and beta isomers of arteether.

A new rapid bioassay has been developed which can precisely differentiate between stereospecific alpha and beta isomers of the antimalarial drug arteether. This method was developed through the disc diffusion bioactivity tests wherein semisynthetically produced alpha arteether was able to inhibit the growth of E. coli strains which are defective in DNA gyrase enzyme. The wild type E. coli with intact DNA gyrase did not show this sensitivity to alpha arteether. The beta isomer of arteether was, however, ineffective against both the mutant and wild type strains. Direct experimental proof of gyrase involvement was obtained through mobilization of gyr genes by transformation of E. coli gyr- mutant strains with wild type gyrA clone pMK90 (carried on the thermo-inducible lambda Col E1 vector). This resulted in alpha arteether resistant and nalidixic acid sensitive phenotype clearly demonstrating the use of gyrA mutant strains in differentiating alpha and beta isomers of arteether by this simple bioassay.

Antimalarials↗
PubMed1996

Modulation of alpha 5 beta 1 and alpha V beta 3 integrins on the cell surface during mitosis.

One of the hallmarks of cells undergoing mitotic division is their rounded morphology and reduced adhesion to the substratum. We have studied and compared the attachment of interphase and mitotic cells to substrata coated with fibronectin and vitronectin. We have found that adhesion of mitotic cells, as compared to interphase cells, is significantly reduced to fibronectin, but is higher to vitronectin. These results correlate well with the expression of alpha 5 beta 1 and alpha V beta 3 integrins, the respective receptors for fibronectin and vitronectin, on the cell surface. Mitotic cells show higher levels of alpha V beta 3 and very low levels of alpha 5 beta 1 proteins on the cell surface as compared to interphase cells. This difference in the levels of these integrins also reflects in the total amounts of fibronectin and vitronectin present on the cell surface of these cells. We have further shown, by flow cytometry, that binding of vitronectin, or the synthetic peptide -GRGDSP-, causes an increase in the intracellular levels of Ca2+ in mitotic cells, but no change is seen in the interphase cells. Binding of fibronectin to either of these cells fails to elicit any response. One interesting feature of our results is that the levels of total, i.e., cytoplasmic plus membrane bound, alpha 5 beta 1 and alpha V beta 3 integrins of mitotic and interphase cells remain the same, thus implying an alteration in the distribution of integrin chains between the plasma membrane and the cytoplasm during the conversion of interphase cells into the mitotic phase.

Animals↗
PubMed1992

Foot and mouth disease in gayals (Bos gaurus frontalis) in Calcutta Zoo.

A brief description is given of an outbreak of foot and mouth disease in gayals (Bos gaurus frontalis) which occurred in Calcutta Zoo in October 1990. Four of the five affected animals died within ten days of onset of the disease. The disease did not spread to other animals in the Zoo.

Animals↗
PubMed1992

Percutaneous interstitial laser therapy of a patient with recurrent hepatoma in a transplanted liver.

We report in situ treatment, by focal hyperthermia, of a recurrent hepatoma in the transplanted liver of a 53-year-old man. Hyperthermia was generated by neodymium-yttrium-aluminum-garnet laser, which was delivered through a fiber placed inside a 19-gauge needle and inserted percutaneously into the liver under ultrasound guidance. The effect was monitored in real time by ultrasound and subsequently confirmed by computerized tomography and needle core biopsy. Objectively the tumor growth was halted for 3 months, indicating partial response to this minimally invasive treatment.

Carcinoma, Hepatocellular↗
PubMed1990

Effect of gamma-irradiation of Escherichia coli on cyclic AMP binding activity.

Cyclic AMP binding in the extract of E. coli was taken as a measure of cAMP receptor protein (CRP) present in the cells. The gamma-irradiation of cells caused a dose-dependent inhibition of cAMP binding activity indicating that CRP gene is affected by gamma-irradiation. The binding activity in cells irradiated with 240 Gy gamma-ray dose remained unaltered by post-irradiation incubation. This supports previous finding that the enhanced inhibition of the L-arabinose isomerase synthesizing capacity, following incubation of gamma-irradiated cells at higher doses, must be due to a different cause than the catabolite repression.

Cyclic AMP↗
PubMed1988

In vivo adenylate cyclase activity in ultraviolet- and gamma-irradiated Escherichia coli.

The incorporation of [14C]adenine into the cyclic AMP fraction by whole cells of Escherichia coli B/r was taken as a measure of the in vivo adenylate cyclase activity. This activity was significantly inhibited by irradiation of the cells either with 60Co gamma-rays or with UV light from a germicidal lamp, suggesting inhibition of cyclic AMP synthesis. The incubation of cells after irradiation with lower doses (50-100 Gy) of gamma-rays produced a significant increase of in vivo adenylate cyclase activity, whereas there was no significant change after higher doses (150 Gy and above). Dark incubation of cells after irradiation with UV light (54 J m-2) led to recovery of enzyme activity to the level measured in unirradiated cells. Thus it appears that the catabolite repression of L-arabinose isomerase induced by UV light, as well as gamma-irradiation, is due to reduced cyclic AMP synthesis in irradiated cells.

Adenylyl Cyclases↗
PubMed1986

Induction of L-arabinose isomerase in gamma-irradiated Escherichia coli.

Gamma irradiation of Escherichia coli B/r caused a dose-dependent inhibition of the capacity of the cells to synthesize L-arabinose isomerase in response to the inducer. At higher doses (18 krad and above), postirradiation incubation led to further inhibition of the capacity to synthesize L-arabinose isomerase, whereas cells receiving lower doses recovered from the damage to the enzyme synthesizing system following incubation. Cyclic AMP partially reversed the inhibitory effect on L-arabinose isomerase induction produced immediately after irradiation by all gamma-ray doses (up to 30 krad), but the enhanced inhibitory effect caused by induction in cells irradiated at higher doses could not be reversed by the nucleotide. It is suggested that although catabolite repression is partly responsible for causing the inhibition of the enzyme synthesizing capacity of the cells observed immediately after gamma irradiation, the enhanced inhibition caused by incubating cells irradiated at higher doses is not due to interference with the control mechanism regulated by catabolite repression.

Aldose-Ketose Isomerases↗
PubMed1983

Pattern of venous lactate and pyruvate after submaximal exercise in athletes training in different disciplines.

The differences in the distribution pattern of muscle fiber types between short-, middle-, and long-distance runners are well known. Since slow- and fast-twitch muscle fibers have different oxidative and glycolytic activities, lactate and pyruvate blood concentrations are expected to behave differently in athletes training in different sports disciplines after short exercise. Twenty-four well-trained athletes participated in the present study. The purpose of the investigation was to examine lactate and pyruvate blood concentrations during a 5-min treadmill exercise test at 6 km/h with a slope of 10% in short-, middle-, and long-distance runners and athletes of other disciplines (nonrunners). The highest and lowest post-exercise lactate and pyruvate levels were found in the short- and long-distance runners, respectively. In contrast to what was found in all other athletes, a decrease of the lactate-pyruvate ratio was observed in the middle-distance runners after exercise. The combination of both aerobic and anaerobic training in these athletes could account for this observation.

Adult↗
PubMed1982

Physical efficiency tests on Indian male "Kabaddi" inter-university players.

The participants of inter-university "Kabaddi" competition showed higher values of height, weight and surface area than average Indian population, indicating better attainment of growth in them. Further, the values of respiratory efficiency tests like, FEV1, MEFR and PEFR were also observed to be more in these players, probably due to training effect. The grip strength values were high in comparison to those of Indian football goalkeepers and hockey players.

Anthropometry↗