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S Bandyopadhyay

Publications and source records attributed to S Bandyopadhyay.

At least 127 records · Page 7Linked to original sources
PubMed1987

Cooperation between CD16(Leu-11b)+ NK cells and HLA-DR+ cells in natural killing of herpesvirus-infected fibroblasts.

We reported previously that natural killer (NK) cell-mediated lysis of cytomegalovirus-infected targets requires the presence of HLA-DR+ nonadherent peripheral blood mononuclear cells (NPBMC). In the present study we determined whether NK cell-mediated lysis of other herpesvirus-infected targets also requires HLA-DR+ cells. Depletion of either cluster designation (CD)16+ NK cells or HLA-DR+ cells from NPBMC significantly reduced their ability to lyse herpes simplex virus (HSV)- and varicella-zoster virus (VZV)-infected fibroblasts. When CD16- and HLA-DR- populations were mixed, lysis of both HSV- and VZV-infected targets was virtually completely restored, indicating that NK cells and HLA-DR+ cells were required for lysis to occur. Cell-free supernatants, obtained by incubating NPBMC or CD16- cells with HSV-o-VZV-infected targets, contained antiviral activity and stimulated HLA-DR-cells to mediate lysis of corresponding virus-infected targets. The addition of anti-interferon-alpha to supernatants abolished their ability to stimulate lysis. Thus, secretion of interferon-alpha by HLA-DR+ cells contributes to NK cell-mediated lysis of herpesvirus-infected targets.

Antigens, Differentiation↗
PubMed1987

Role of the heavy and light chains of botulinum neurotoxin in neuromuscular paralysis.

Botulinum neurotoxin (NT) is synthesized by Clostridium botulinum in any of seven antigenically distinct forms called types A-G. NT, when fully active, is a dichain protein, composed of two polypeptides, a heavy (H) and a light (L) chain (approximately 100,000 and approximately 50,000 Da, respectively) that are held together by noncovalent bonds and at least one disulfide bond. Two types of dichain NT, A and B, and their respective H and L chains were applied to nerve-muscle (NM) preparations (phrenic nerve-hemidiaphragm of the mouse), in order to develop a broader, comparative understanding of the neuroparalytic actions of NT types. It was found that the paralysis induced by dichain NT was delayed or antagonized if NM preparations were incubated with isolated and purified H chain prior to, or during, incubation with the parent, dichain NT. NM preparations preincubated with H chain and then washed free of unbound H chain became paralyzed after subsequent incubation with L chain. Paralysis did not occur if NM preparations were incubated first with L chain, washed, and then incubated with H chain. These observations suggest that the H chain binds with specific sites on the nerve terminal. This binding appears to permit the L chain, or some combination of the L and H chain, to bring about neuroparalysis through a mechanism very similar to that of the parent, dichain NT.

Animals↗
PubMed1987

The plantar nerves-lumbrical muscles: a useful nerve-muscle preparation for assaying the effects of botulinum neurotoxin.

The plantar nerves-lumbrical muscles (PL) of the hindpaw of the mouse is a preparation that is particularly useful for assaying the effects of botulinum neurotoxin (NT) on the mammalian neuromuscular junction. Each mouse provides a minimum of 4 and a maximum of 8 such preparations. The muscles are thin enough so that neuromuscular junctions can be easily located with Nomarski interference contrast optics for impaling with microelectrodes. The preparations are small enough so they can be sectioned transversely or longitudinally, in their entirety, for light and electron microscopy, or just the regions containing end-plates can be used. An examination of the responses of this preparation to types A and E NT reveal its exceptional suitability for experiments with NT. The small number of fibers and their arrangement permit assays of low concentrations of NT to proceed to complete and total paralysis in a convenient period of time.

Animals↗
PubMed1987

Unexpected binding of an octapeptide to the angiotensin II receptor.

An octapeptide, TBI-22 (Lys-Gly-Val-Tyr-Ile-His-Ala-Leu), inhibited binding of angiotensin II by a solubilized angiotensin receptor partially purified from rabbit liver. This inhibition appears to result from competition for binding to the same receptor. Radioiodinated TBI-22, like angiotensin II, bound to the solubilized receptor with an affinity such that the binding was inhibited 50% by unlabeled TBI-22 or angiotensin II at nanomolar concentrations. The binding reaction, like that for angiotensin II, required p-chloromercuriphenylsulfonic acid and was reversed in the presence of dithiothreitol. TBI-22 and angiotensin II share the sequence Val-Tyr-Ile-His; this tetrapeptide alone, however, did not inhibit binding of angiotensin II. Replacement of the tyrosine residue by aspartic acid in TBI-22 greatly reduced the ability of the peptide to compete with angiotensin II for binding, suggesting an important contribution of this residue to the configuration required for recognition by the receptor.

Amino Acid Sequence↗
PubMed1987

A comparison of plasma, white blood cell, red blood cell, and tissue distribution of amiodarone and desethylamiodarone in anesthetized dogs.

Desethylamiodarone (DA) is a major metabolite of amiodarone (AM), a Class III antiarrhythmic drug. The plasma pharmacokinetics and tissue distribution of AM and DA (10 mg/kg i.v.) were compared in anesthetized dogs. Plasma, white blood cell (WBC), red blood cell (RBC), liver, and skeletal muscle samples were obtained at frequent intervals up to 6 h after a single i.v. bolus of the two drugs. Drug concentrations in these and other tissues, i.e., lung, kidney, heart (right and left atrium, right and left ventricle, Purkinje fibers, and AV node), and femoral nerve were measured by a highly sensitive and specific high-pressure liquid chromatographic technique developed in our laboratory. Four different patterns of AM and DA uptake and washout could be identified in these experiments. The first pattern is biexponential decline in plasma drug levels with a rapid distribution phase (t1/2 alpha = 5.1 +/- 2.1 min for AM and 5.5 +/- 1.2 min for DA, respectively) and a slower elimination phase (t1/2 beta = 3.7 +/- 1.3 h for AM and 4.96 +/- 0.8 h for DA, respectively). The volume of distribution of DA was significantly larger than that of AM. The second pattern is that both WBCs and RBCs showed an initial uptake within 5 min followed by a biexponential decrease in drug levels, with t1/2 alpha similar to that in plasma but t1/2 beta significantly longer than in plasma. In both these types of cells, the elimination half-life for DA was significantly longer than that of AM. The third pattern is that in the liver there was a rapid uptake of both drugs with peak concentrations at 15 min; the decline in hepatic levels of AM was biexponential, but that of DA appeared to be monoexponential. In addition, in dogs given AM alone, the metabolite (DA) was easily detected in the liver from the earliest time of measurement, suggesting that the parent drug is rapidly metabolized to DA. In the experiments where DA was injected, two new peaks were also identified in the liver suggesting that DA was metabolized further in the liver. The fourth pattern was in the skeletal muscle, where AM uptake was relatively slow, reaching peak concentrations between 1.5-2 h followed by a monoexponential decline; however, DA was rapidly taken up by skeletal muscle, but the rate of decline appeared to be slower as compared to that of AM.(ABSTRACT TRUNCATED AT 400 WORDS)

Amiodarone↗
PubMed1987

Effects of interferons and interleukin 2 on natural killing of cytomegalovirus-infected fibroblasts.

The ability of nonadherent peripheral blood mononuclear cells of normal individuals to lyse noninfected and cytomegalovirus (CMV)-infected human fibroblasts was enhanced by preincubation with recombinant human alpha interferon (alpha-rIFN) or beta (beta-rIFN). In contrast, recombinant human gamma IFN (gamma-rIFN) augmented natural killing (NK) against both targets relatively poorly. Recombinant or natural human interleukin 2(IL-2) also augmented NK against noninfected and CMV-infected targets. Augmentation of NK by IFN or IL-2 could be blocked by the addition of corresponding antisera. IL-2-enhanced NK against CMV-infected targets was usually independent of alpha-IFN production.

Cytomegalovirus Infections↗
PubMed1986

Requirement for HLA-DR+ accessory cells in natural killing of cytomegalovirus-infected fibroblasts.

The role of HLA-DR+ cells in NK activity against CMV-infected FS4 foreskin fibroblasts and K562 erythroleukemia cells was examined. When nonadherent PBMC were depleted of either HLA-DR+ or Leu-11b+ cells by treatment with mAbs plus C, NK activity against CMV-FS4 target cells was markedly reduced. In contrast, depletion of HLA-DR+ cells had no effect on NK activity against K562 target cells. When HLA-DR-depleted cells were added to Leu-11b-depleted cells, NK activity against CMV-FS4 was restored. Negative selection experiments indicated that the HLA-DR+ cells contributing to NK activity against CMV-FS4 are not B or T cells, while negative and positive selection experiments excluded a role for monocytes. Experiments in which HLA-DR- and Leu-11b- cells were mixed in varying proportions indicated that NK(CMV-FS4) is mediated by Leu-11b+ cells, while HLA-DR+ cells provide an accessory function. Irradiation (50 GY) abolished the NK effector function of Leu-11b+ cells, but not the accessory function of HLA-DR+ cells. The NK activity against CMV-FS4 of HLA-DR- cells was restored by the addition of rIFN-alpha or of cell-free supernatants generated by coculturing PBMC or Leu-11b- cells with CMV-FS4. The ability of these supernatants to restore NK activity of HLA-DR- cells was completely abrogated by the addition of neutralizing amounts of antibody to IFN-alpha. In related experiments, neutralization of IFN-alpha in NK assays had little or no effect on NK activity against CMV-FS4, suggesting that the accessory function of HLA-DR+ cells might be mediated by alternative mechanisms in addition to the secretion of extracellular IFN-alpha.

Antigen-Presenting Cells↗
PubMed1986

Interleukin 2 enhances natural killing of varicella-zoster virus-infected targets.

Preincubation of peripheral blood non-adherent mononuclear cells with purified or recombinant interleukin 2 (IL-2) significantly enhanced natural killer (NK) activity against uninfected and varicella-zoster virus (VZV)-infected targets, while antibody-dependent cellular cytotoxicity (ADCC) against VZV-infected targets was not increased. Preincubation of effector cells with IL-2 had no effect on conjugate formation, but lysis of both targets was increased in single cell assays. IL-2-enhanced NK against VZV-infected targets was independent of gamma-interferon (gamma-IFN) production.

Adult↗
PubMed1984

Antitumor activity with nontoxic doses of protein A.

This report confirms our previous observation that IV inoculation of purified protein A causes regression of rat mammary adenocarcinomas. In treated tumors, we have obtained histological evidence of changes indicating tumor cell destruction. Protein A treatment does not cause reduction in the body weight or organ weights of rats; nor does it cause any decrease in activity of the enzymes of the microsomal mixed function oxidase system in the liver. Protein A stimulates peripheral white cell counts in normal rats, but not in tumor-bearing rats. We found that protein A infusion reduced (P less than 0.0005) the level of circulating plasma immune complex concentration. A homing study with 125I-labeled protein A indicated that liver, spleen, and kidney tissues are the major sites of protein A accumulation. Therefore, protein A seemed to exert its antitumor effects without causing any generalized toxicity to the system. It is postulated that the action of protein A may be related to its ability to cause a drastic reduction in circulating plasma immune complex concentration, thus potentiating the immune reactivity of the host observed earlier.

Adenocarcinoma↗
PubMed1984

Potentiation of surfactant release in fetal lung by thyroid hormone action.

Thyroid hormone has been shown to accelerate fetal lung development, but the mechanisms by which this hormone acts are yet unknown. Since this hormone may act indirectly by potentiating the action of endogenous catecholamines, we studied this mechanism by measuring beta-adrenergic receptors in fetal lung. Fetal rabbits at 27 days of gestation were treated with triiodothyronine (T3), 100 micrograms/100 g, in the presence and absence of propranolol, 200 micrograms/100 g, or actinomycin D, 20 micrograms/100 g. Fetuses were killed by decapitation either after 4 or 24 h of T3 treatment. The beta-adrenergic antagonist l-[3H]dihydroalprenolol was used to directly estimate the number and affinity of beta-adrenergic receptor in lung membranes. T3 increased the number of beta-adrenergic receptors in fetal lung, but the affinity of binding did not change. The enhancement of binding capacity after 4 h of T3 treatment was not inhibited by actinomycin D. However, 24-h T3-mediated stimulation was partially blocked by actinomycin D. In addition, T3 stimulated the catecholamine content, adenylate cyclase activity, and adenosine 3',5'-cyclic monophosphate content of lung. T3 increased the lecithin-to-sphingomyelin ratio, phosphatidylglycerol, and disaturated phosphatidylcholine content of the pulmonary lavage fluid. These parameters were completely inhibited by propranolol after 4 h and partially inhibited by actinomycin D after 24 h. Thus thyroid hormone enhances lung maturation by increasing the number of beta-adrenergic receptors in fetal lung.

Animals↗
PubMed1984

Thyroid hormone regulation of beta-adrenergic receptors and catecholamine sensitive adenylate cyclase in foetal heart.

The effect of thyroid hormone on the beta-adrenergic receptor in foetal cardiac membranes was analysed by measuring the binding of (-)[3H]DHA. The specific activities (per mg protein) of beta-adrenergic receptors decreased with advancing gestational age, whereas the total activities (per heart) increased under the similar conditions. The change in the binding affinities was not statistically significant. 1; 3,5,3'-L-triiodothyronine (T3) stimulated the (-)[3H]DHA binding capacities of the cardiac membranes of foetuses of all age groups. The enhancement in the receptor activity was completely inhibited actinomycin D or cycloheximide. The contents of epinephrine, norepinephrine and cAMP increased with advancing gestational age; but T3 had no significant effect on the catecholamines or cAMP. Similarly, the activities of the basal, NaF stimulated and Gpp(NH)p stimulated adenylate cyclase remained unaltered by T3, but the activities increased progressively with foetal maturity. The absolute values of catecholamine stimulated adenylate cyclase activities in the hearts of T3 treated foetuses were, however, higher compared to those in the untreated foetuses. The enhancement of the activities were totally blocked by the action of actinomycin D, cycloheximide or propranolol. Our results indicate that thyroid hormone enhances the number of beta-adrenergic receptor binding sites by synthesizing new receptor proteins resulting in increased catecholamine sensitivity.

Adenylyl Cyclases↗
PubMed1984

Adsorption of plasma from tumor-bearing hosts over protein A--containing nonviable Staphylococcus aureus Cowan I: possible mechanism of antitumor reactions.

Adsorption of autologous plasma over nonviable Staphylococcus aureus Cowan I (SAC) followed by reinfusion of the plasma causes regression of (a) chemically induced rat mammary adenocarcinomas (MA), and (b) canine transmissible venereal tumors (TVT) and spontaneously occurring dog tumors. Animal data are more impressive than that from trials in humans. Nine of 41 patients receiving perfusions of adsorbed plasma showed some partial objective response. Eight of these nine patients received multiple perfusions over a period of time. Twenty-one of 41 patients showed subjective responses. Adsorption of autologous plasma over non-protein A--containing S. aureus Wood 46 caused regression of MA. Adsorption of normal rat plasma with SAC, and infusion of this adsorbed plasma into mammary tumor--bearing rats, caused regression of MA. Intravenous infusion of purified protein A alone caused regression of both rat MA and canine TVT. Superimposed on this observation is the finding that, during plasma adsorption, bacterial moieties leach from SAC. It is possible that the immunostimulation observed in plasma-perfused hosts is due to the removal of plasma blocking agents on one hand, and introduction of the bacterial agents on the other.

Adenocarcinoma↗
PubMed1984

Effect of frequency of plasma adsorption over protein A-containing Staphylococcus aureus on regression of rat mammary adenocarcinomas: modification of antitumor immune response and tumor histopathology.

Adsorption of the plasma of Sprague-Dawley rats having 7, 12-dimethylbenzanthracene (DMBA)-induced primary mammary adenocarcinomas with protein A-containing Staphylococcus aureus Cowan I (SAC) and reinfusion of the adsorbed plasma caused significant (p less than 0.05) regression of mammary adenocarcinomas. Adsorption of plasma was done at different intervals--weekly, biweekly, and on alternate days. Of these protocols, alternate-day adsorptions induced very fast (within a week) tumor regression (p less than 0.001). Other protocols also produced tumor regression; however, the effect was delayed. In long-term studies, the responding animals showed fewer tumor nodules than did the untreated controls. The plasma of the treated animals showed (a) a reduction in blocking activity, (b) an increase in antibody- and complement-mediated cytotoxicity, and (c) potentiation of the cytotoxic activity of peripheral blood mononuclear cells (PBMCs). Histopathological analyses of biopsied sections of tumors from treated animals showed (a) disruption of tumor cell architecture, (b) loss of glandular structure, (c) shrinkage of epithelial cells, and (d) moderate mononuclear cell infiltration. Thus, adsorption of the plasma of DMBA tumor-bearing rats with SAC allows an indigenous immune mechanism to function against autochthonous tumors to control their growth and cause regression.

Adenocarcinoma↗
PubMed1983

Hematological changes produced in mice by ochratoxin A and citrinin.

The effect of 6 weekly injections of ochratoxin A (5 mg/kg) and citrinin (20 mg/kg) on the following hematological indices of mice was studied: erythrocyte sedimentation rate, hematocrit percentage, mean corpuscular values, red cell indices, platelet count, total count of bone marrow cells, differential count of bone marrow cells, total count of splenic cells, spleen weight, and serum calcium. These mycotoxins resulted in a significant decrease in platelet count and hematocrit values. On the other hand, they increased erythrocyte sedimentation rate, mean corpuscular values and red cell indices. Weight of the spleen and the splenic cell count decreased significantly in ochratoxin A and citrinin treated mice. Total count of bone marrow cells, erythrocyte precursors, leucocyte precursors and megakaryocyte precursors of femoral bone marrow decreased significantly in toxin treated mice. Calcium concentration in the serum of toxin treated mice also was decreased significantly.

Animals↗
PubMed1983

A new laboratory method for evaluating the relative solubility and erosion of dental cements.

A method for accelerating the dissolution and erosion of 'acidic' dental cements has been developed which gave relative solubilities in accordance with in vivo observations, in contrast to the conventional test. It involves subjecting 24-h-old specimens to a jet of dilute acid (lactic or citric) and determining weight loss. The relative ranking for 'acidic' cements in the apparatus and in vivo was: glass ionomer less than silicophosphate less than zinc phosphate less than polycarboxylate. The method was not valid for reinforced zinc oxide/eugenol/EBA cements. Of the two polycarboxylate cements studied, a brand which has the acid in the powder was found to be more soluble than the conventional material. It is proposed that the method be the basis of a new solubility/erosion test in national and international standards for 'acidic' dental cements.

Chemical Phenomena↗