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Biomedical subjects

S Mazumder

Publications and source records attributed to S Mazumder.

16 recordsLinked to original sources
PubMed2001

Topical use of Sucralfate Cream in second and third degree burns.

This clinical study was undertaken to test the efficacy of topical Sucralfate Cream in second and third degree burns. Topical Sucralfate Cream has been used on a wide variety of lesions from radiation proctitis and dermatitis to keratoconjunctivitis with remarkable results. The study was carried out in two phases. The first phase comprised 60 patients, 30 of whom were treated with Sucralfate Cream while the other 30 were treated with other topical antimicrobial agents. Twenty-one of the patients in the study group had second-degree burns and nine patients' third degree burns. In the second phase, a double blind study was carried out on 25 patients where one area of burns was treated with Sucralfate Cream while another control area of the same patient was treated with a placebo ointment, containing the excipients used during preparation of the Sucralfate Cream, without Sucralfate. In the first phase, it was seen that the period of epithelialisation of second degree burns in the study group treated with Sucralfate Cream was 18.8 days compared with 24.6 days with other topical agents. This difference is statistically significant with a P value of <0.00001. In the double blind study, also healing in the areas treated with Sucralfate was more rapid than those treated with bland placebo ointment. The difference in the two rates of healing was statistically significant with a P value of 0.00067. Histopathological studies were also carried out in 10 patients of phase I of the trial. Sucralfate Cream promotes rapid epithelialisation of second degree burns with minimal said effects and offers another topical agent in the burn care specialist's armamentarium.

Administration, Topical↗
PubMed2000

Cyclin E induction by genotoxic stress leads to apoptosis of hematopoietic cells.

Cyclin E is essential for progression through the G1 phase of the cell cycle and initiation of DNA replication by interacting with, and activating its catalytic partner, the cyclin-dependent kinase 2 (Cdk2). We found a substantial increase in cyclin E mRNA, accompanied by increased production of cyclin E protein and cyclin E/Cdk2 kinase activity in multiple myeloma and lymphoma cells following irradiation. Cyclin E expression increased early in a time and dose-dependent manner, with a three-fold induction reached 8 h following gamma-irradiation. Run-on analyses indicated a predominantly transcriptional regulation of cyclin E. Stable overexpression of cyclin E, but not cyclin D1, sensitized IM-9 cells to gamma-irradiation-induced apoptosis; in contrast, a dominant-negative Cdk2, prevented apoptosis. Irradiation of cyclin E overexpressing cells led to an enhanced caspase activation and exposure of the phosphatidylserine on the plasma membrane, two key markers of apoptosis, events which were completely abolished in cells expressing a dominant-negative Cdk2. This study identifies cyclin E as a target for activation by ionizing radiation and which plays a functional role in apoptosis of hematopoietic cells. Oncogene (2000) 19, 2828 - 2835

Apoptosis↗
PubMed2000

Nitric oxide: the "second messenger" of insulin.

Incubation of various tissues, including heart, liver, kidney, muscle, and intestine from mice and erythrocytes or their membrane fractions from humans, with physiologic concentration of insulin resulted in the activation of a membrane-bound nitric oxide synthase (NOS). Activation of NOS and synthesis of NO were stimulated by the binding of insulin to specific receptors on the cell surface. A Lineweaver-Burk plot of the enzymatic activity demonstrated that the stimulation of NOS by insulin was related to the decrease in the Km for L-arginine, the substrate for NOS, with a simultaneous increase of Vmax. Addition of NG-nitro-L-arginine methyl ester (LNAME), a competitive inhibitor of NOS, to the reaction mixture completely inhibited the hormone-stimulated NO synthesis in all tissues. Furthermore, NO had an insulin-like effect in stimulating glucose transport and glucose oxidation in muscle, a major site for insulin action. Addition of NAME to the reaction mixture completely blocked the stimulatory effect of insulin by inhibiting both NO production and glucose metabolism, without affecting the hormone-stimulated tyrosine or phosphatidyl-inositol 3-kinases of the membrane preparation. Injection of NO in alloxan-induced diabetic mice mimicked the effect of insulin in the control of hyperglycemia (i.e., lowered the glucose content in plasma). However, injection of NAME before the administration of insulin to diabetic-induced and nondiabetic mice inhibited not only the insulin-stimulated increase of NO in plasma but also the glucose-lowering effect of insulin.

Animals↗
PubMed2000

Biochemical profile of erythrocyte membrane of jaundiced neonates.

Studies in newborn humans have demonstrated alteration in the lipid, phospholipid and cholesterol content when compared with age-matched control. Membrane bound (Na+ + K+)ATPase activity is found to be significantly increased in jaundiced neonates. Alteration in membrane permeability characteristics in jaundiced neonates causes severe microenvironmental changes in red blood cell profile.

Birth Weight↗
PubMed1999

Stimulation of nitric oxide synthesis and protective role of insulin in acute thrombosis in vivo.

Administration of physiologic amounts of insulin in mice (200 microunits/g body weight) resulted in 9 fold increase of basal nitric oxide level from 0.51+/-0.1224 nmol/ml (mean+/-SD, n=12) to 4.45+/-0.645 nmol/ml after 30min of the injection of the hormone. Since NO is a potent inhibitor of platelet aggregation both in vitro and in vivo, we tested the possibility whether the administration of the hormone would result in the in vivo inhibition of thrombosis through the increase of NO level in the circulation. It was found that administration of insulin (200 microunits/g body weight) in mice protected >90%(p<0.00001, n=500) of these animals from death due to thrombosis in the coronary arteries induced by ADP injection in the heart. This effect of insulin in vivo was found to be directly related to the hormone induced increase of NO level in the system. The thromboprotective effect of insulin could not be achieved by using either prostacyclin, a well known antithrombotic agent or its stable probe prostaglandin E1 instead of insulin. The efficacy of insulin was neither related to the blood glucose level nor was the consequence of the hypoglycemic effect of the hormone. In contrast, inhibition of insulin induced increase of NO level resulted in the complete loss of the thromboprotective effect of the hormone. These results suggest that insulin besides being a hypoglycemic hormone could also be a potent antithrombotic humoral factor.

Adenosine Diphosphate↗
PubMed1999

Ionizing radiation-induced, Bax-mediated cell death is dependent on activation of cysteine and serine proteases.

Bcl-2 family proteins and interleukin-1-beta converting enzyme/Caenorhabditis elegans cell death gene-3 (ICE/CED-3) family proteases (caspases) represent the basic regulators of apoptosis. However, the precise mechanism by which they interact is unclear. In this study, we found that gamma-radiation-induced apoptosis of leukemia cells was associated with activation of multiple caspases and bax up-regulation. Membrane changes and caspase activities were suppressed by specific caspase inhibitors. Similarly, the serine protease inhibitors z-Ala-Ala-Asp-cmk (AAD) and tosyl-lysine chloromethyl ketone (TLCK) also prevented caspase activation and poly(ADP-ribose) polymerase cleavage in vivo but had no effect on caspase activity in vitro. TLCK also prevented bax up-regulation as a result of its inhibitory effect on p53 function. Inhibitors of caspases and serine proteases partially prevented cell death, suggesting a caspase involvement in Bax-mediated cell death. We propose an ordering of signaling events in Bax-mediated cell death, including steps upstream and downstream of p53 and bax up-regulation.

Apoptosis↗
PubMed1998

Mutational analysis of the human immunodeficiency virus type 1 Vpu transmembrane domain that promotes the enhanced release of virus-like particles from the plasma membrane of mammalian cells.

Human immunodeficiency virus type 1 Vpu is a multifunctional phosphoprotein composed of the N-terminal transmembrane (VpuTM) and C-terminal cytoplasmic domains. Each of these domains regulates a distinct function of the protein; the transmembrane domain is critical in virus release, and phosphorylation of the cytoplasmic domain is necessary for CD4 proteolysis. We carried our experiments to identify amino acids in the VpuTM domain that are important in the process of virus-like particle (VLP) release from HeLa cells. VLPs are released from the plasma membrane of HeLa cells at constitutive levels, and Vpu expression enhanced the release of VLPs by a factor of 10 to 15. Deletion of two to five amino acids from both N- and C-terminal ends or the middle of the VpuTM domain generated mutant Vpu proteins that have lost the ability to enhance VLP release. These deletion mutants have not lost the ability to associate with the wild-type or mutant Vpu proteins and formed complexes with equal efficiency. They were also transported normally to the Golgi complex. Furthermore, a Vpu protein having the CD4 transmembrane and Vpu cytoplasmic domains was completely inactive, and Vpu proteins harboring hybrid Vpu-CD4 TM domains were also defective in the ability to enhance the release of VLPs. When tested for functional complementation in cotransfected cells, two inactive proteins were not able to reconstitute Vpu activity that enhances the release of Gag particles. Coexpression of functional CD4/Vpu hybrids or wild-type Vpu with inactive mutant CD4/Vpu proteins revealed that mutations in the VpuTM domain could dominantly interfere with Vpu activity in Gag release. Taken together, these results demonstrated that the structural integrity of the VpuTM domain is critical for Vpu activity in the release of VLPs from the plasma membrane of mammalian cells.

Amino Acid Sequence↗
PubMed1997

Effect of zinc supplementation on cell-mediated immunity and lymphocyte subsets in preschool children.

OBJECTIVE: In a zinc supplementation trial (with a significant impact on diarrheal morbidity), to evaluate effect of zinc supplementation on cellular immune status before and after 120 days of supplementation. DESIGN: A double blind, randomized controlled trial with immune assessment at baseline and after 120 days on supplement. SETTING: Community based study in an urban slum population. SUBJECTS: Randomly selected children (zinc 38, control 48), had a Multitest CMI skin test at both times. In 66 children (zinc 22, control 34), proportions of CD3, CD4, CD8, CD16, CD20 cells and the CD/CD8 ratio were also estimated using a whole blood lysis method and flowcytometry. INTERVENTION: Zinc gluconate to provide elemental zinc 10 mg daily and 20 mg during diarrhea. MAIN OUTCOME RESULTS: Regarding CMI, the percentage of anergic or hypoergic children (using induration score) decreased from 67% to 47% in the zinc group, while in the control group it remained unchanged (73% vs 71%) (p = 0.05). The percentage of children deteriorating between first and second tests was significantly lower in the zinc group (13% vs 33%, p = 0.03). Regarding lymphocyte subsets, the zinc group had a significantly higher rise in the geometric means of CD3 (25%, p = 0.02), CD4 (64% p = 0.001), and CD4/CD8 ratio (73% p = 0.004) with no difference in CD8 and CD20. The rise in CD4 was significantly higher in the zinc as compared to the control group; the ratio of geometric means was 1.45 (95% CI, 1.03-2.01). CONCLUSION: Zinc supplementation improves cellular immune status, which may have been one of the mechanisms for observed impact of zinc supplementation on diarrheal morbidity.

Child, Preschool↗
PubMed1993

Immunomodulation of human T cell responses with receptor selective enkephalins.

The delta-opioid receptor selective [2-D-penicillamine-5-D-penicillamine] enkephalin (DPDPE) and the mu receptor selective Tyr-D-Orn-Phe-Asp-NH2 (TOPA) were found respectively, to have marked immunostimulant and immunosuppressant activities in both normal subjects and patients suffering from leprosy and tuberculosis. Antigen specific lymphoproliferation and numbers of rosette forming T cells were significantly (P < 0.05) enhanced on in vitro treatment with Met-enkephalin. This was further increased (P < 0.001) in the presence of the delta selective DPDPE. In contrast, treatment with mu selective TOPA inhibited lymphoproliferation substantially (P < 0.01) and rosette formation to a lesser extent.

Adjuvants, Immunologic↗
PubMed1992

Allosteric modulation of Leishmania donovani plasma membrane Ca(2+)-ATPase by endogenous calmodulin.

The plasma membrane of the human pathogen Leishmania donovani possesses a high-affinity transmembrane Ca(2+)-ATPase that has its catalytic site oriented toward the cytoplasmic milieu (Ghosh, J., Ray, M., Sarkar, S., and Bhaduri, A. (1990) J. Biol. Chem. 265, 11345-11351). When the enzyme is studied in its more authentic, physiologically relevant, membrane-associated form, it exhibits pronounced sigmoidal kinetics with Ca2+ (K0.5 approximately 700 nM) in a trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid buffering system that effectively complexes all available Mg2+. Addition of exogenous Mg2+ (60 microM) completely abolishes sigmoidicity and establishes strictly hyperbolic kinetics, and the Km for Ca2+ reduces to 100 nM. Mg2+ can be replaced by heterologous calmodulin. The exclusive dependence of the enzyme on only Ca2+ for its activity and its positive allosteric modulation by Mg2+ distinguish this enzyme from other well-characterized plasma membrane Ca(2+)-ATPases. Employing this Ca(2+)-ATPase as the assay system, a soluble endogenous activating protein factor was purified that, by several criteria, corresponds to authentic calmodulin. The parasite calmodulin shifts the kinetics to hyperbolic kinetics, increases the Vmax 2-fold, and most important lowers the Km (approximately 100 nM) to a physiological level. The interaction with endogenous calmodulin thus converts the enzyme from a totally inactive to a fully active state.

Adenosine Triphosphate↗
PubMed1989

Mechanism of complement-independent and antibody-mediated killing of Leishmania donovani promastigotes.

Immune serum raised against flagellar fraction of Leishmania donovani isolate UR6 has profound lethal effect on the in vitro growth of the parasite. Lethal effect of immune serum was also examined using two other isolates of L. donovani, namely DD8 and AG83. It was observed that immune serum is equally effective against UR6 and DD8 but has no effect on AG83 promastigotes. Parasite killing is mediated by Leishmania-specific antibodies in the absence of complement or any other factors present in rabbit serum. Results indicate that the lethal effect of immune serum is due to impairment in membrane function leading to inhibition in uptake of essential nutrients needed for growth and survival of parasites.

Animals↗