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Biomedical subjects

S Gupta

Publications and source records attributed to S Gupta.

At least 1,477 records · Page 82Linked to original sources
PubMed1985

A comparative study on the translation of cardiovirus RNAs in rabbit reticulocyte lysates.

In rabbit reticulocyte lysates the RNAs of encephalomyocarditis (EMC) virus, mengovirus, and Mous-Elberfeld (ME) virus directed the synthesis of similar sets of products. Moreover, the viral protease synthesized from any one of the three viral RNAs could cause cleavage of the viral capsid precursor proteins synthesized from any of the three RNAs. However, the three RNAs differed in their dependence on tRNA supplementation (to the lysates) for effective translation. In the absence of tRNA supplementation, synthesis of 5'-derived proteins of EMC viral RNA proceeded normally, but little synthesis of the proteins coded by the remaining portion of the viral genome occurred. In the case of mengoviral RNA, omission of tRNA supplementation caused mostly a generalized reduction of the synthesis of all viral proteins. In contrast, synthesis of ME viral proteins stopped almost completely in the absence of tRNA supplementation.

Animals↗
PubMed1985

Accessory cell function of cells of the mononuclear phagocyte system isolated from mycobacterial granulomas.

Epithelioid cells from BCG-induced granulomas and macrophages from Mycobacterium leprae-induced granulomas were examined for their ability to act as accessory cells for T-cell proliferation to mitogen (Con A) and antigen (PPD). The granuloma cells were separated on a FACS using monoclonal antibody specific to guinea pig macrophages. Epithelioid cells (which are Ia negative) were able to support proliferation to Con A but not to antigen. Cultures containing Ia positive granuloma macrophages from M. leprae sensitized animals did not show responsiveness to Con A or to PPD. Oil-induced peritoneal exudate macrophages from BCG or M. leprae immunized animals were able to act as accessory cells for both mitogen and antigen proliferation. The nonresponsiveness of cultures containing epithelioid cells stimulated with PPD or M. leprae granuloma macrophages stimulated with Con A was not due to suboptimal or supraoptimal accessory cell:lymphocyte ratios.

Animals↗
PubMed1985

Immunological status of trophoblastic neoplasia.

Six cases of choriocarcinoma, 17 of vesicular mole, 20 normal pregnant females in the first trimester of pregnancy, and 20 normal nonpregnant women wih previous normal obstetrical history were evaluated quantitatively for cell-mediated immunity by response to 2:4 dinitrocholorobenzene and recall antigens. Serum immunoglobulins were estimated in all cases. Suppression of cell-mediated immunity was marked in choriocarcinoma as compared to vesicular mole. Serum IgG levels were significantly diminished in cases of vesicular mole, indicating diminished humoral immunity. Follow-up after 3 months of treatment with surgery and chemotherapy resulted in marked improvement of cell-mediated immunity.

Candida↗
PubMed1985

Malignant fibrous histiocytoma of solitary jejunal diverticulum.

A rare case of malignant fibrous histiocytoma arising from a solitary jejunal diverticulum leading to its perforation is described in a 37-year-old male. The patient presented with peritonitis and on exploration revealed perforation of a jejunal diverticulum containing a soft, friable mass. Biopsy from the mass revealed a malignant fibrous histiocytoma. This appears to be the first description in literature of a malignant fibrous histiocytoma with that particular localization.

Adult↗
PubMed1985

Ion channels in lymphocytes.

The advent of the gigaohm-seal recording technique has enabled the study of the electrical properties of small cells, such as individual lymphocytes. Recent studies using this technique in combination with standard immunological and biochemical techniques indicate that cells of the immune system may utilize ion channels, similar in properties to those described in nerve and muscle, in the process of activation. For example, potassium channels may be required for T-lymphocyte mitogenesis and calcium channels for antibody production. This article summarizes these recent reports.

Animals↗
PubMed1985

Autologous mixed lymphocyte reaction in man. XIII. Characterization of the T-T autologous mixed lymphocyte reaction.

In this study we have demonstrated that in the T-TA autologous mixed lymphocyte reaction (AMLR), OKT4+ T cells are the major responders; however, in the presence of additional interleukin-2 (IL-2), OKT8+ T cells also respond by proliferation. Both OKT4+ and OKT8+ T cells, activated in the T-non-T AMLR, act as stimulators in the T-TA AMLR. OKT4+ T cells activated in the T-TA AMLR suppress the proliferative response of the fresh T-non-T AMLR; control OKT4+ cells show no immunoregulatory activity in this system. In contrast, control OKT8+ T cells spontaneously suppress the proliferation of the T-non-T AMLR, but activation of OKT8+ T cells in the T-TA AMLR does not result in a further increase in the suppressor activity of OKT8+ T cells. In summary, in the T-non-T and T-TA AMLR phenotypically similar T-cell subpopulations proliferate but express distinct immunoregulatory functions and perhaps regulate the tempo of the AMLR.

Antibodies, Monoclonal↗
PubMed1985

Action of diethylcarbamazine citrate on protective immunity in rats infected with Nippostrongylus brasiliensis.

Rats made immune to Nippostrongylus brasiliensis and treated with diethylcarbamazine citrate (DEC) orally (250 mg/kg X 6) exhibited significant suppression of functional immunity. Similarly, administration of compound 48/80 (100 micrograms/rat i.p.) made the immune rats susceptible to challenge infection. Treatment of rats, with 22-day infection with compound 48/80, histamine (20 mg/rat, per os), or L-histidine (20 mg/rat, orally s.c.) did not accelerate worm expulsion. A massive complement-dependent adherence of peritoneal cells (1 X 10(8], isolated from immune DEC-treated and untreated rats, to infective larvae (L3) was observed. Likewise, heavy congregation of normal peritoneal cells to larvae was noticed when the cells were incubated with sera obtained from immune, DEC-treated or untreated rats. The rats receiving mesenteric lymph node cells (125 X 10(6) i.v.) or sera (0.5 ml or 1 ml X 3 i.p.), obtained from immune DEC-treated rats and challenged with infective larvae developed 50% more worms than those which received cells or serum from untreated immune donors. DEC appears to cause suppression of functional immunity and worm expulsion is not histamine mediated.

Animals↗
PubMed1985

Voltage-dependent ion channels in T-lymphocytes.

The gigaohm seal 'patch-clamp' technique has recently enabled exploration of the electrical properties of cells of the immune system. In this paper we review progress made to date in cataloguing the ion channels present in the cell membranes of T-lymphocytes and present new data on the types of ion channels present in a number of human and murine T-cell-derived cell lines. The ion channels thus far described in these cells are strikingly similar to those found in nerve and muscle cells. Voltage-gated potassium channels resembling delayed rectifier potassium channels in excitable cells are present in most T-lymphocytes, T-lymphocyte-derived cell lines and macrophages. Sodium channels indistinguishable from those in excitable cells are present in a small fraction of T-cells and T-cell lines, and in some natural killer cells. Calcium channels have been reported in B-lymphocyte-derived cell lines, but have not been found in T-lymphocytes or in any T-cell-derived cell line. Potassium channels are required for activation of T-lymphocytes by mitogen, allogeneic cells, or by antigen, for lysis of target cells by natural killer cells, and may be involved in the triggering mechanism for activation of T-cells. The prevailing conception of early events in T-lymphocyte activation, the 'calcium hypothesis', involves an elevation of cytoplasmic free calcium levels as the proposed 'second messenger' in activation, giving rise to a cascade of subsequent events resulting eventually in cell division. A major focus of this paper is to evaluate specific mechanisms which have been proposed to account for experimental evidence, both in the literature and also presented here, pertaining to the calcium hypothesis. One such mechanism involves calcium channels, which have been postulated to account for the early calcium influx in activated T-lymphocytes. Since calcium channels have not been detected in T-cells, we explore the possibility that existing data can be accounted for without calcium channels. In particular, we show that many of the effects of 'calcium channel antagonists' such as verapamil, nifedipine, diltiazem and some polyvalent cations, can be accounted for by their blocking of voltage-gated potassium channels.

Animals↗
PubMed1985

Is the pattern of inflammatory bowel disease different in the elderly?

The clinical course of inflammatory bowel disease in elderly patients has been reviewed. The natural history of ulcerative colitis and Crohn's disease in the elderly is similar to that in the young with the usual wide spectrum of severity of disease. Such inflammatory bowl disease responds well to medical treatment in the majority of elderly patients, and surgical intervention is only required rarely for complications or unresponsive disease. Reports of a more serious clinical course in older patients were not substantiated.

Aged↗
PubMed1985

Deficient concanavalin-A-induced suppressor-cell activity in patients with bronchial asthma, allergic rhinitis and atopic dermatitis.

Concanavalin-A (Con-A)-induced suppressor activity against the proliferative response of autologous lymphocytes to phytohaemagglutinin (PHA) was examined in the peripheral-blood lymphocytes from fourteen patients with bronchial asthma, ten patients with allergic rhinitis and eleven patients with atopic dermatitis and compared with eleven simultaneously studied healthy normals. Eight of fourteen patients (57%) with bronchial asthma, eight of ten patients (80%) with allergic rhinitis and five of eleven patients (45%) with atopic dermatitis demonstrated deficient Con-A-induced suppressor function. Abnormal suppressor-cell functions could play an important role in the pathogenesis of atopic states.

Asthma↗
PubMed1985

Monoclonal antibody-defined beta 2-microglobulin-positive mononuclear cells in acquired immune deficiency syndrome.

In healthy heterosexuals, by means of a monoclonal antibody against beta 2-microglobulin (beta 2m) and fluorescence-activated cell sorter analyser (FACS analyser), we observed two populations of beta 2m+ mononuclear cells (MNC); a large population with high-intensity cells and a small population of relatively low-intensity cells. Because elevated beta 2m levels have been shown in the sera of patients with acquired immune deficiency syndrome (AIDS), we examined the proportions of beta 2m+ MNC in AIDS and AIDS-related complex (ARC). The proportions and numbers of high-fluorescence intensity beta 2m+ MNC were significantly (P less than 0.05) decreased in AIDS and ARC when compared with those of asymptomatic homosexuals and healthy heterosexuals. The proportion and number of total beta 2m+ MNC (both high- and low-intensity beta 2m+) in ARC were comparable to those of control groups; however, the numbers of total beta 2m+ MNC were significantly (P less than 0.01) reduced only in the AIDS group. This relative deficiency of high-intensity beta 2m+ MNC appears to be due to a shift from high-intensity beta 2m+ to low-intensity beta 2m+ MNC. A linear correlation was observed between the deficiency of high-intensity beta 2m+ cells and T helper to T suppressor phenotype cell ratios.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Immunological profile in children with minimal change nephrotic syndrome.

Peripheral blood from patients with active stage of minimal change nephrotic syndrome (MCNS) was examined for concanavalin A (ConA)-inducible suppressor T cell activity, proliferative response to phytohemagglutinin (PHA) and in the autologous (AMLR) and allogeneic (MLR) mixed lymphocyte reaction, proportions of T cells with receptors for IgM (Tu) or IgG (T gamma) and the levels of serum immunoglobulin M, G and A. Six of 9 patients with MCNS studies showed deficiency of ConA-induced suppressor cell activity. In the AMLR, only one of 9 patients with MCNS demonstrated depressed proliferative response (p less than 0.05). In the allogeneic MLR, T cells from 5 of 9 patients with MCNS demonstrated poor proliferative response when stimulated with normal control non-T cells. Five of 9 patients with MCNS had depressed proliferative response to PHA. The proportion of total T cells, Tu cells and T gamma cells in the patient group were comparable to healthy control group. Serum IgG was significantly decreased in 7 of 11 patients. This study demonstrates multiple immunological abnormalities in patients with MCNS that might play a role in its pathogenesis.

Adolescent↗
PubMed1985

A voltage-gated potassium channel in human T lymphocytes.

Human peripheral T lymphocytes were studied at 20-24 degrees C using the gigaohm seal recording technique in whole-cell or outside-out patch conformations. The predominant ion channel present under the conditions employed was a voltage-gated K+ channel closely resembling delayed rectifier K+ channels of nerve and muscle. The maximum K+ conductance in ninety T lymphocytes ranged from 0.7 to 8.9 nS, with a mean of 4.2 nS. The estimated number of K+ channels per cell is 400, corresponding to a density of about three channels/micron2 apparent membrane area. The activation of K+ currents could be fitted by Hodgkin-Huxley type n4 kinetics. The K+ conductance in Ringer solution was half-maximal at -40 mV. The time constant of K+ current inactivation was practically independent of voltage except near the threshold for activating the K+ conductance. Recovery from inactivation was slow and followed complex kinetics. Steady-state inactivation was half-maximal at -70 mV, and was complete at positive potentials. Permeability ratios, relative to K+, determined from reversal potential measurements were: K+(1.0) greater than Rb+(0.77) greater than NH4+(0.10) greater than Cs+ (0.02) greater than Na+(less than 0.01). Currents through K+ channels display deviations from the independence principle. The limiting outward current increases when external K+ is increased, and Rb+ carries less inward current than expected from its relative permeability. Tail current kinetics were slowed about 2-fold by raising the external K+ concentration from 4.5 to 160 mM, and were 5 times slower in Rb+ Ringer solution than in K+ Ringer solution. Single K+ channel currents had two amplitudes corresponding to about 9 and 16 pS in Ringer solution. Replacing Ringer solution with isotonic K+ Ringer solution increased the unitary conductance and resulted in inward rectification of the unitary current-voltage relation. Comparable effects of external K+ were seen in the whole-cell conductance and instantaneous current-voltage relation. Several changes in the K+ conductance occurred during the first few minutes after achievement of the whole-cell conformation. Most are explainable by dissipation of a 10-20 mV junction potential between pipette solution and the cytoplasm, and by the use of a holding potential more negative than the resting potential. However, inactivation of K+ currents became faster and more complete, changes not accounted for by these mechanisms. K+ efflux through open K+ channels in intact lymphocytes, calculated from measured properties of K+ channels, can account for efflux values reported in resting lymphocytes, and for the increase in K+ efflux upon mitogenic stimulation.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗