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Biomedical subjects

P K Sarkar

Publications and source records attributed to P K Sarkar.

At least 19 recordsLinked to original sources
PubMed1995

Microflora of murcha: an amylolytic fermentation starter.

Murcha is a traditional starter, used commonly in Darjeeling hills and Sikkim in India to ferment a variety of starchy substrates in order to produce sweet-sour alcoholic beverages, called jnards. Murcha cakes are mildly acidic (pH 5.2) and contain 13% w/w moisture and 0.7% w/w ash (dry weight basis). A total of 194 bacterial, 190 yeast and 80 mould strains were isolated from 30 samples of murcha. The counts (cfu/g fresh weight) of micro-organisms in the samples were 2.0 x 10(7) to 4.2 x 10(8) for Pediococcus pentosaceus, 4.0 x 10(7) to 6.8 x 10(8) for Saccharomycopsis fibuligera, 2.0 x 10(6) to 7.2 x 10(7) for Pichia anomala, 1.0 x 10(6) to 4.1 x 10(7) for Mucor circinelloides and < 10 to 1.0 x 10(6) for Rhizopus chinensis. While all the species were prevalent in 100% of the samples, R. chinensis was detected in only 50% of them. Both the moulds but one yeast species, S. fibuligera had amylolytic activity.

Amylases↗
PubMed1994

A monoclonal antibody to a cytoskeletal protein selectively recognizing malignant neuroectodermal tumors.

Fusion of myeloma (P3X63-Ag 8.653) cells with spleen cells from BALB/c mice immunized with human neuroblastoma (SK-N-SH) cells yielded a hybridoma clone, referred to as 3XB7, with a unique pattern of reactivity to malignant neuroectodermal tumors except gliomas of low-grade malignancy. Indirect immunofluorescence staining under different conditions and Western blot analysis indicate that the 3XB7 MAb recognizes an intracellular cytoskeletal protein of M(r) 52K. Immunohistochemical studies with cryostat and paraffin-embedded sections from tumor biopsies revealed that the 3XB7 MAb specifically recognizes malignant neuroectodermal tumors and reacts negatively with other epithelial and mesenchymal tumors, e.g., carcinomas, lymphomas, and sarcomas as well as with normal adult and fetal brain tissues. Negative reaction was also observed with other small round cell tumors of childhood. Thus the 3XB7 antigen can be used for diagnosis of all stages of neuroblastomas, and its specific expression in gliomas with high-grade malignancy (grades III and IV) confer on it additional prognostic value.

Adult↗
PubMed1992

Effect of hypothyroidism on different forms of actin in rat cerebral neuronal cultures studied by an improved DNase I inhibition assay.

An improved DNase I inhibition assay for the filamentous actin (F-actin) and monomeric actin (G-actin) in brain cells has been developed. Unlike other methods, the cell lysis conditions and postlysis treatments, established by us, inhibited the temporal inactivation of actin in the cell lysate and maintained a stable F-actin/G-actin ratio for at least 4-5 h after lysis. The new procedure allowed separate quantitation of the noncytoskeletal F-actin in the Triton-soluble fraction (12,000 g, 10 min supernatant) that did not readily sediment with the Triton-insoluble cytoskeletal F-actin (12,000 g, 10 min pellet). We have applied this modified assay system to study the effect of hypothyroidism on different forms of actin using primary cultures of neurons derived from cerebra of neonatal normal and hypothyroid rats. Our results showed a 20% increase in the Triton-insoluble cytoskeletal F-actin in cultures from hypothyroid brain relative to normal controls. In the Triton-soluble fraction, containing the G-actin and the noncytoskeletal F-actin, cultures from hypothyroid brain showed a 15% increase in G-actin, whereas the F-actin remained unaltered. The 10% increase in total actin observed in this fraction from hypothyroid brain could be totally accounted for by the enhancement of G-actin. The mean F-actin/G-actin ratio in this fraction was about 30% higher in the cultures from normal brain compared to that of the hypothyroid system, which indicates that hypothyroidism tends to decrease the proportion of noncytoskeletal F-actin relative to G-actin.

Actins↗
PubMed1992

A simple biochemical approach to differentiate synaptosomes and non-synaptic mitochondria from rat brain.

A simple and rapid low speed density gradient centrifugation method has been described to isolate relatively pure synaptosomes and non-synaptic mitochondria from rat brain cerebral cortex. The purity of the fractions isolated were tested biochemically by considering some marker enzymes, i.e., lactate dehydrogenase, plasma membrane Na+K+ATPase and acetylcholinesterase for the synaptosomes and succinate dehydrogenase for the mitochondrial fraction. The adrenergic receptor properties in the synaptosomal membrane were evaluated by observing the effect of different beta- and alpha 2-adrenergic receptor agonists and antagonists as function of synaptic plasma membrane Na+K+ATPase activity. Isoproterenol (beta-agonist) and yohimbine (alpha 2-antagonist)-induced changes in the synaptosomal Na+K+ATPase activity were counteracted by beta-antagonist propranolol and alpha 2-agonist clonidine, respectively. In the non-synaptic mitochondria the corresponding effects were insignificant. The study illustrates an easy, rapid and low-speed preparatory method to obtain synaptosomal and non-synaptic mitochondrial fractions of high purity.

Animals↗
PubMed1991

Post-transcriptional regulation of tubulin mRNA in developing rat brain.

The transcriptional activity of tubulin genes during synaptogenesis in developing rat brain has been examined by 'nuclear run off assay'. For both alpha and beta tubulin genes, the relative rates of transcription were found to be high during the early phase of synaptogenesis (postnatal days 1-5) and declined 20-50% by the end of synaptogenesis (postnatal days 15-20). Comparison of the developmental alterations in the rates of transcription of both alpha and beta tubulin mRNA with the level of polysomal tubulin mRNA shows that the age related decline (70-80%) in the level of polysomal tubulin mRNA during synaptogenesis is much too large compared to the 20-25% decline in their transcription rates suggesting that tubulin mRNA levels in developing rat brain are regulated post-transcriptionally.

Aging↗
PubMed1991

Thyroidal stimulation of tubulin and actin in primary cultures of neuronal and glial cells of rat brain.

The influence of triiodothyronine (T3) on the level of tubulin and other proteins in primary cultures of neuronal (N) and glial (G) cells from rat brain has been investigated. Quantitation of tubulin by [3H]colchicine binding assay revealed that when cells from 1 day rat brain were cultured for 18 hr with physiological doses (0.5-5 nM) of T3, the hormone elicited 35-40% increase in the soluble (30,000 g supernatant) tubulin content of G cells only. This stimulation was age-dependent and occurred neonatally at a time corresponding to the onset of synaptogenesis. In mouse and chick brain also, [3H]colchicine binding assay showed a similar selective stimulation of the soluble tubulin content of G cells by T3 with virtually no effect on N cells. However, SDS-polyacrylamide gel electrophoresis of the total proteins in the 30,000 g supernatants from N and C cells of rat brain, labeled for 18 hr with [14C]leucine in the presence of T3, revealed that T3 elicited 2-3-fold enhancement of radiolabeled tubulin in the N cells which is relatively greater than the 1.5-fold increase seen in the G cells. Analysis of the autoradiograms of these labeled proteins also revealed that in addition to tubulin, T3 stimulated the accumulation of radiolabeled actin by 1.5- and 2-fold in N cells and G cells respectively. Similar electrophoretic analysis of the solubilized labeled proteins in the 30,000 g pellets from N and G cells indicated that the failure to detect the stimulation of tubulin in the 30,000 g supernatants from N cells by [3H]colchicine binding assay could be at least partly due to rapid translocation of the dimeric soluble tubulin into insoluble membrane fractions or due to presence of higher oligomeric forms of tubulin which are insensitive to [3H]colchicine binding assay.

Actins↗
PubMed1991

Tubulin gene expression during synaptogenesis in rat, mouse and chick brain.

Studies on tubulin gene expression in brains from three different species, viz rat, mouse and chick, varying with respect to their periods of synaptogenesis, show that the rise and fall in the level of tubulin during synaptogenesis is closely parallel to that of tubulin mRNA. In all three species, the onset of synaptogenesis is accompanied by a dramatic rise in the level of tubulin which continues till the midphase and then declines to adult level by the end of synaptogenesis. The chick alpha- and beta-tubulin coding region probes, pT1 and pT2, which have a 80-90% homology with rat/mouse sequences, were employed to determine the overall levels of alpha- and beta-tubulin mRNA in all samples. Quantitation of tubulin mRNA by dot hybridization revealed a closely parallel change in the levels of both alpha- and beta-tubulin mRNA. In analogy with that of tubulin, the mRNA levels in rat and mouse brain increased progressively from birth till postnatal day 5 and that in the chick brain increased from day 7 till day 11 of embryonic development. In all three cases, the peak levels of tubulin mRNA corresponded closely with the midphase of synaptogenesis and declined almost to adult levels by the end of synaptogenesis. The sudden decline in the level of tubulin as well as its mRNA during the middle of synaptogenesis suggests that the repression of tubulin gene expression is neither due to cessation of cell division nor cell differentiation. Instead, it is likely to be due to the autoregulatory property of tubulin which leads to rapid turnover of its own mRNA when a sufficient level of intracellular tubulin accumulates during the midphase of synaptogenesis.

Animals↗
PubMed1991

Ventriculo-pulmonary fistula. Case report, literature review and possible surgical approach to the infected LV suture line.

We describe a patient who developed a ventriculo-pulmonary fistula 2 years after resection of a left ventricular aneurysm, and mention the management of two further patients, one with a sinus, the other with a pseudo-aneurysm, both after left ventricular aneurysmectomy, to illustrate a possible surgical approach to a patient with a ventriculo-pulmonary fistula.

Female↗
PubMed1990

Successful control of atonic primary postpartum haemorrhage and prevention of hysterectomy, using i.v. prostaglandin E2.

Primary postpartum haemorrhage remains an important cause of maternal mortality and morbidity in England and Wales, despite the fact that avoidable causes can be identified in more than half the cases. The management of this potentially dangerous condition has been considered to be far from satisfactory. Conventional methods of management include the administration of oxytocin and ergometrine, and the use of bimanual compression. If these methods fail, surgical intervention, such as ligation of the hypogastric or internal iliac artery or even a hysterectomy, may be necessary. The full therapeutic potential of prostaglandin E2 in the management of atonic postpartum haemorrhage has not been widely recognised, even though it has been used successfully. We report one such case of atonic postpartum haemorrhage in which IV infusion of prostaglandin E2 was used with favourable results after conservative methods failed, thus avoiding a hysterectomy.

Adult↗
PubMed1989

Subtotal cystectomy and antirefluxing hepaticoduodenostomy for choledochus cyst in children.

Total cystectomy with Roux-en-Y hepaticojejunostomy for choledochus cyst often causes malabsorption and other problems as a result of jejunal biliary diversion bypassing the duodenum. Restoration of near normal anatomy can only return the normal physiological harmony and assure normality. A simple antirefluxing hepaticoduodenostomy has proved successful.

Anastomosis, Roux-en-Y↗