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Biomedical subjects

S Gupta

Publications and source records attributed to S Gupta.

At least 1,315 records · Page 73Linked to original sources
PubMed1989

Correlation of IgM anti-hepatitis D virus (HDV) to HDV RNA in sera of chronic HDV.

One hundred forty-four serum samples from 52 patients with chronic hepatitis D virus infection were analyzed for hepatitis D virus RNA by dot-blot hybridization using hepatitis D virus cDNA probe labeled with 32P. The results were correlated with the presence of serum IgM anti-hepatitis D virus and hepatitis D antigen in liver biopsy specimens when available. Although there was a trend of positive correlation between serum hepatitis D virus RNA and IgM anti-hepatitis D virus, no statistical significance could be found. In the serum samples with hepatitis D virus RNA, 32% were found to be negative for IgM anti-hepatitis D virus. Therefore, in chronic hepatitis D virus, absence of IgM anti-hepatitis D virus does not rule out active viral infection, as suggested by previous studies. There was a strong correlation between serum hepatitis D virus RNA and hepatic hepatitis D virus antigen. These data indicate that detection of hepatitis D virus RNA in serum samples is a reliable noninvasive marker of active viral infection.

Antibodies, Viral↗
PubMed1989

Voltage-sensitive ion channels in human B lymphocytes.

Human tonsillar B cells were found to contain type n K+ channels, and have K+ channel densities somewhere between those of murine B cells and those of human T cells. Unlike human T lymphocytes, some human B lymphocytes were able to increase K+ channel density in response to mitogenic activation, but the increases were smaller than those observed in murine B lymphocytes. Some mitogen-stimulated human B cells increased in size, but, unlike murine B cells, cell size was not related to K+ channel density. There may be a down-regulation of K+ channel density in human B cells treated with SAC for 6 days, while no such effect occurs in murine B cells. A fraction of human B cells possess inward current channels (probably Na+ channels) that are similar to channels sometimes seen in human T cells, but not seen in murine B cells.

Animals↗
PubMed1989

Astrocytes and intracerebral immune responses.

The astrocyte is the most abundant cell within the central nervous system (CNS). This cell subserves a multiplicity of important functions that contribute to the process of neural development as well as to the integrity of normal brain function. Adding to the already exhaustive list of capabilities, the astrocyte has now been demonstrated to function as an intracerebral antigen presenting cell. These findings are serving to revise our view of the brain as an immunoprivileged site and perhaps will shed some light on the pathogenetic mechanisms involved in a number of CNS disorders of immune dysregulation. In this review we provide some perspective on the regulatory mechanisms that influence astrocyte immune functions. Specifically, we address the role played by the major histocompatibility complex (MHC) antigens as well as adhesion molecules in the initiation of brain immune responses.

Animals↗
PubMed1989

Frequent endoscopic variceal sclerotherapy increases risk of complications. Prospective randomized controlled study of two treatment schedules.

In an effort to determine the optimal dose and frequency of chronic endoscopic variceal sclerotherapy, a prospective randomized controlled study comparing two treatment schedules of sclerotherapy was carried out over a 21-month period. Patients with variceal hemorrhage were randomly assigned to receive sclerotherapy at weekly intervals using injection volumes of greater than 15 cc at each treatment or at mean intervals of three days using volumes of less than 10 cc per treatment. Esophageal perforation occurred in three patients (15%) in the small-dose, frequent-injection group as compared to none in the large-dose weekly treatment group (P = 0.07), leading to premature termination of the study. The mean time to rebleeding was significantly shorter in the small-dose, frequent-treatment group (P = 0.05). Variceal obliteration was achieved in a mean of 66% of patients in both groups with no difference in the time to obliteration or the frequency of other complications. Sclerotherapy offered at less than weekly intervals is less effective and is associated with an increased frequency of serious and life threatening complications.

Adult↗
PubMed1989

Regional differences in concentrations of regulatory peptides in human colon mucosal biopsy.

The study was undertaken to examine regional differences in the concentrations of five regulatory peptides in the human colonic mucosa. Biopsies were obtained during routine colonoscopy from 33 patients whose colonic mucosa was macroscopically and histologically normal. Regulatory peptides were extracted, and measured by specific radioimmunoassays. Concentrations of three peptides that are present predominantly in endocrine cells within colonic mucosa increased significantly towards the rectum: Mean concentrations of peptide YY, enteroglucagon, and somatostatin were about three times greater in the rectum than in the cecum. However, concentrations of two peptides that are present in mucosal nerve fibers diminished significantly towards the rectum: Mean rectal concentrations of vasoactive intestinal peptide and peptide histidine methionine were both about 0.6 of mean cecal concentrations. Concentrations of all five peptides were lower in biopsies taken from colonic polyps than in normal colonic mucosa. Regional differences in colonic mucosal concentrations of regulatory peptides probably reflect differences in the physiological functions of different parts of the colon.

Adolescent↗
PubMed1989

The management of extensive corrosive esophageal strictures: do not dilate and procrastinate.

Corrosive strictures of the esophagus are difficult to treat, however, prompt and appropriate management of corrosive burns to the esophagus can prevent the formation of strictures. In a developing country like India, where facilities for early treatment are not easily available, strictures are an inevitable consequence. If the strictures are extensive, dilatational therapy proves ineffective and offers no substantial benefit to the patients. Twenty patients with extensive corrosive strictures of the esophagus were surgically managed; by esophageal bypass in 13 and esophagectomy in 7. Surgical treatment restored normal swallowing in all the patients. The common post-operative complications to occur were: pulmonary complications, anastomotic leak and stricture, gastric outlet obstruction and reflux esophagitis. For extensive corrosive strictures of the esophagus, we advocate early surgical treatment rather than prolonged dilatational therapy.

Adolescent↗
PubMed1989

Presacral neurilemoma (schwannoma)--report of a rare case.

A rare case of presacral neurilemoma is reported herein. Despite the large size of the tumor and the extensive destruction of the sacrum, the patient was almost asymptomatic. Accurate diagnosis depends on careful rectal examination and computerized axial tomography is the most useful single investigation. Surgery is the only treatment and for large lesions, the abdominal approach is usually preferred. Recurrence is rare and patients live a long, symptom free life even after partial resection.

Humans↗
PubMed1989

Pharmacodynamics of amlodipine: hemodynamic effects and antianginal efficacy after atrial pacing.

The hemodynamic effects and antianginal efficacy of 10 mg amlodipine administered intravenously were assessed for 45 minutes in 18 subjects with stable angina pectoris. After amlodipine the heart rate was increased from 75 +/- 12 beats/min to 80 +/- 15 beats/min (p less than 0.05) for at least 15 minutes, with a decrease in systemic vascular resistance of 1091 +/- 205 to 815 +/- 390 dynes/sec/cm5 and a decrease in mean arterial pressure at 30 minutes from 99 +/- 11 to 91 +/- 10 (p less than 0.05). There was no change in dp/dt or dp/dt/IP or in cardiac output, wedge pressure, or pulmonary artery pressure. In the parallel placebo group (n = 8) there was no change in any of the hemodynamic parameters. Time to pacing-induced angina was increased in the treated group (n = 12) from 6 +/- 3.2 minutes before the dose to 8.2 +/- 4 minutes after the dose (p less than 0.01) compared to the control subjects who were given saline solution, in whom the time increased from 7 +/- 1.5 minutes before the dose to 7.5 +/- 2.2 minutes after the dose (n = 9). The double product at an equivalent pacing time to the initial onset of angina was reduced after therapy from 15,590 +/- 1490 to 14,100 +/- 1193 with a reduction in ST segment shift from 11.9 +/- 9.4 mm2 to 6.2 +/- 5.6 mm2 (p less than 0.05). Amlodipine after intravenous use has a vasodilator effect and also increases the anginal threshold without deleterious negative inotropic effects.

Amlodipine↗
PubMed1989

Potentiation of immunosuppressive effects of cyclosporin A by 1 alpha,25-dihydroxyvitamin D3.

Both cyclosporin A (CsA) and 1 alpha,25-dihydroxyvitamin D3 (vitamin D3) inhibit T-cell functions. Because CsA has a dose-related systemic toxicity, there is a need for approaches by which the dosage of CsA could be reduced while maintaining the required immunosuppression. Therefore, we examined for any potentiating effect of vitamin D3 on CsA-induced suppression of T cell functions in vitro. Peripheral blood mononuclear cells were stimulated with phytohemagglutinin in the presence or absence of various concentrations of CsA (1.6-13.2 micrograms/ml) or vitamin D3 (10(-10)-10(-7) M) or both together and [3H]thymidine incorporation (TdR), interleukin 2 (IL-2) production, IL-2 receptor (IL-2R) expression, and the response to exogenous recombinant IL-2 (rIL-2) on TdR were measured. IL-2 production was measured on CTLL cell line and IL-2R expression with anti-Tac monoclonal antibody using FACScan. There was a dose-dependent inhibition of TdR, IL-2 production, and IL-2R expression by CsA. Vitamin D3 inhibited TdR and IL-2 production in a dose-dependent manner but had no significant (P greater than 0.1) effect on IL-2R expression. Recombinant IL-2 had no effect on CsA-induced inhibition of TdR, whereas rIL-2 completely reversed the vitamin D3-induced inhibition of TdR. A significantly (P less than 0.05) increased inhibition of TdR and IL-2 production was observed when two agents were used together as compared to expected inhibition by the addition of each agent separately. A consistent synergism was observed between all concentrations of CsA used and vitamin D3 (10(-8) and 10(-7) M). This study shows that the potentiation of immunosuppressive effects of CsA by vitamin D3 could be used as an approach to reduce the dosage of CsA in clinical use without compromising immunosuppression, thus preventing or minimizing the dose-related toxic effects of CsA.

Calcitriol↗
PubMed1989

Antispermatogenic effect of embelin, a plant benzoquinone, on male albino rats in vivo and in vitro.

Embelin, the active principle of the seeds of Embelia ribes Burm, has been isolated and the purity established. Daily subcutaneous administration of the compound at a dose of 20 mg/kg body weight to male albino rats for 15 or 30 days revealed an inhibition of: a) epididymal motile sperm count, b) fertility parameters such as pregnancy attainment and litter size, and c) the activities of the enzymes of glycolysis and energy metabolism. These changes were reversible, as seen after 15 and 30 days of recovery. Addition of embelin to epididymal sperm suspensions caused a dose- and duration-dependent inhibition of spermatozoal motility and the activities of the enzymes of carbohydrate metabolism. Light and scanning electron microscopy showed that both in vivo and in vitro treatment with the drug causes profound morphological changes in spermatozoa such as: a) decapitation of the spermatozoal head, b) discontinuity of the outer membranous sheath in the mid-piece and the tail region, and c) alteration in the shape of the cytoplasmic droplet in the tail.

Animals↗
PubMed1989

The induction of intercellular adhesion molecule 1 (ICAM-1) expression on human fetal astrocytes by interferon-gamma, tumor necrosis factor alpha, lymphotoxin, and interleukin-1: relevance to intracerebral antigen presentation.

Antigen presentation reactions are dependent upon the expression of the class II major histocompatibility antigens (MHC), the T-cell receptor, and the presented antigen. Recent studies demonstrate that such processes also require the presence of adhesion molecules such as lymphocyte functional antigen 1 (LFA-1) and its cell surface ligand, intercellular adhesion molecule 1 (ICAM-1). It has been suggested that the brain astrocyte can function as a facultative antigen presenting cell (APC). This hypothesis is based upon the ability to induce the expression of the class II MHC antigens on astrocytes, and on their ability to present myelin basic protein to encephalitogenic T-cells in vitro. The best in vivo data showing that astrocytes serve as intracerebral APCs is the finding that astrocytes in multiple sclerosis plaques are DR+ (class II MHC in human). However, it still remains to be resolved whether the in vivo expression of the MHC antigens in disease states is instrumental to antigen presentation mechanisms or whether these cell surface glycoproteins are expressed secondary to brain immune responses. If astrocytes function as immunocompetent APCs within the brain, it would seem that they would also be able to express molecules important for intercellular adhesion. Here, we present the first data that indicates that human astrocytes are capable of expressing ICAM-1 in response to cytokines that either induce or upregulate the expression of DR. In essence, cytokines derived from different cell types seem to exert similar pleiotropic effects on the modulation of MHC and ICAM-1 expression on astrocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Antigen-Presenting Cells↗
PubMed1989

Non-linear phenomena in host-parasite interactions.

The paper examines non-linear dynamical phenomena in host-parasite interactions by reference to a series of different problems ranging from the impact on transmission of control measures based on vaccination and chemotherapy, to the effects of immunological responses targeted at different stages in a parasite's life-cycle. Throughout, simple mathematical models are employed to aid in interpretation. Analyses reveal that the influence of a defined control measure on the prevalence or intensity of infection, whether vaccination or drug treatment, is non-linearly related to the magnitude of control effort (as defined by the proportion of individuals vaccinated or treated with a drug). Consideration of the relative merits of gametocyte and sporozoite vaccines against malarial parasites suggests that very high leves of cohort immunization will be required to block transmission in endemic areas, with the former type of vaccine being more effective in reducing transmission for a defined level of coverage and the latter being better with respect to a reduction in morbidity. The inclusion of genetic elements in analyses of the transmission of helminth parasites reveals complex non-linear patterns of change in the abundance of different parasite genotypes under selection pressures imposed by either the host immunological defences or the application of chemotherapeutic agents. When resistance genes are present in parasite populations, the degree to which abundance can be suppressed by chemotherapy depends critically on the frequency and intensity of application, with intermediate values of the former being optimal. A more detailed consideration of the impact of immunological defences on parasite population growth within an individual host, by reference to the erythrocytic cycle of malaria, suggests that the effectiveness of a given immunological response is inversely related to the life-expectancy of the target stage in the parasite's developmental cycle.

Animals↗
PubMed1989

Effect of histamine and its antagonists on the course of Nippostrongylus brasiliensis in rats.

The involvement of histamine in the rejection of Nippostrongylus brasiliensis (nematode) from rats harbouring 18 to 20-day-old infections was investigated. Parenteral administration of histamine delayed worm rejection. A similar effect was observed with histamine depletor, compound 48/80, and the prostaglandin synthesis inhibitor indomethacin. Antihistaminics, mepyramine and pyribenzamine failed to alter the course of infection, and neither did the histamine synthesis inhibitor, semicarbazide. Pretreatment of rats with the H1 histamine receptor antagonist, mepyramine, effectively antagonized histamine-induced worm retention, whereas the H2 histamine receptor antagonist cimetidine had a negligible effect. The results suggest that histamine or histamine depletors do not have any apparent role in self-cure mechanism; rather they support parasitism.

Animals↗
PubMed1989

Detection of hepatitis delta virus in serum and liver tissue by molecular hybridization. Validation of a rapid spot-hybridization technique.

Serologic tests for detection of delta hepatitis virus (HDV) antigen and antibody have recently been supplemented with a Northern blot hybridization assay for HDV RNA. However, this technique is cumbersome for analysis of multiple samples. In order to simplify detection of HDV RNA, the authors have tested a spot-hybridization method with a new HDV cDNA probe. Their method has proved to be rapid, sensitive, and specific for HDV RNA even when less ultracentrifugation was used for recovering serum RNA. Results for HDV RNA were concordant by both spot and Northern blot hybridization in 12 serum samples from patients with known delta hepatitis, whereas in seven cases spot-hybridization was superior in detecting liver HDV RNA. The concordance between HDV RNA by spot hybridization and delta antigen was complete, whereas that between delta IgM (44% overall) or IgG (67% overall) was less strong. The authors' observations indicate that this new technology permits detection of HDV RNA with relative ease and could be applicable to the evaluation of large numbers of cases with delta hepatitis.

Animals↗
PubMed1989

Thermogravimetric analysis of urinary stones.

Routine thermogravimetric (TG) analysis of 501 upper urinary calculi from the State of Jammu and Kashmir is described. The technique is simple, rapid and quantitative, and the equipment is easily maintained. The technique was found to be helpful in 95.4% of urinary stones and it is suggested that TG analysis may be employed as a technique of first choice in the routine quantitative analysis of all urinary calculi.

Calcium Oxalate↗