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Biomedical subjects

S Vaidya

Publications and source records attributed to S Vaidya.

At least 55 records · Page 3Linked to original sources
PubMed1992

Frequency of hepatitis B, C and D and human immunodeficiency virus infections in multi-transfused thalassemics.

Of forty multi-transfused thalassemia patients (26 males, 14 females; mean age 8.1 +/- 5.3 years, range 1-35) with no clinical or biochemical evidence of liver disease, HBsAg, anti-hepatitis C virus and anti-human immunodeficiency virus antibodies were present in 18 (45%), 7 (17.5%) and 1 (2.5%) cases respectively. Three of the 18 (16.7%) HBsAg positive patients were anti-delta antibody positive. Our results indicate that more than 50% of multi-transfused thalassemia patients show serological evidence of one or more of hepatitis B, C and D and human immunodeficiency virus infection.

Adolescent↗
PubMed1992

The effect of erythropoietin in normal healthy volunteers and pediatric patients with burn injuries.

BACKGROUND: Surgical procedures result in blood loss that can require replacement transfusions. Such therapy may result in multiple adverse sequelae, including transmission of infectious diseases and immune impairment. Alternative therapies are therefore desirable. METHODS: We evaluated the ability of recombinant human erythropoietin (rEPO) to increase red blood cell production in both normal healthy volunteers and patients with burn injuries. The effect of rEPO on immune function in the volunteers was also evaluated. The volunteers received 150 units/kg rEPO daily for 7 days, with immune function and hematopoiesis assayed on days 0, 7, and 14. The patients with burn injuries received either 500 units/kg/day rEPO with iron supplementation or merely the iron. RESULTS: rEPO increased erythropoiesis in both the volunteers and the patients with burn injuries. Failure to provide iron supplementation to the volunteers resulted in significant depletion of iron stores with a concomitant impairment in immune function that paralleled the iron depletion. CONCLUSIONS: rEPO therapy offers the potential to increase red blood cell production in surgical patients. Failure to provide iron supplementation in patients receiving rEPO can lead to a rapid depletion of iron stores and may contribute to an immune dysfunction.

Adult↗
PubMed1991

Entrapment of proteins by aggregation within sephadex beads.

When a protein is aggregated by chemical crosslinking inside Sephadex beads of appropriate pore size, it gets trapped inside the beads. The above approach was used for immobilization of beta-galactosidase, acid phosphatase, trypsin, and concanavalin A. It was found to be a simple, convenient, and fast method for immobilization of proteins.

Acid Phosphatase↗
PubMed1991

HLA and epidermolysis bullosa: evidence for independent assortment of Weber-Cockayne subtype of epidermolysis bullosa and HLA complex.

The purpose of this study was to examine the genetic linkage (but not the association) between HLA complex and Weber-Cockayne Subtype of epidermolysis bullosa (EBS-WC). We HLA typed 44 members of three multi-generation families in which 24 members have the clinical evidence of EBS-WC. The patterns of inheritance of various HLA haplotypes and the disease were mathematically analyzed to estimate frequency of recombination (i.e. genetic distance) between HLA complex and the disease by calculating Lod Scores for each family separately as well as all for three families combined. Our results show that only one family had a positive Lod Score. The Lod Scores for the remaining two families as well as the combined Lod Score for all three families were negative. These data suggest that odds are against the genetic linkage between HLA complex and Weber-Cockayne Subtype of epidermolysis bullosa and in favor of independent assortment of the disease and HLA complex.

Chromosome Mapping↗
PubMed1991

Suppression of graft-versus-host reaction in severe combined immunodeficiency with maternal-fetal T cell engraftment.

Simultaneous engraftment of maternal T cells and T cells from unrelated transfusion donor in an infant with severe combined immunodeficiency disease (SCID) was identified by HLA typing blood lymphocytes of the patient, her triplet siblings, parents, and the platelet donor from whom the patient received nonirradiated platelet transfusion. T cell grafts from both the mother and platelet donor were stable for several months, but the graft-versus-host reactions (GvHR) remained mild and immune function was deficient. We hypothesize that immunosuppressive effects of a maternal-fetal GvHR may have modified the expected lethal GvHR from platelet donor's T cells.

Agammaglobulinemia↗
PubMed1991

HLA and epidermolysis bullosa. Association between the HLA complex and recessive dystrophic epidermolysis bullosa.

BACKGROUND AND DESIGN: --Epidermolysis bullosa refers to a group of genetic diseases characterized by marked skin fragility and blister formation following minor mechanical trauma. The patients with recessive dystrophic epidermolysis bullosa (RDEB) are the most severely affected with marked internal and external blistering, scarring, and death at an early age, secondary to malnutrition, septicemia, and/or metastatic squamous cell carcinoma. An association between RDEB and HLA antigens was explored in 28 patients with RDEB and their family members. RESULTS: --Our data demonstrate that susceptibility to develop RDEB may be associated with the HLA complex. The gene frequencies of DR4 and DQw3 were much higher in the patients than expected. These increases were likely due to statistically significant excess of DR4 and DQw3 homozygotes in the patients. In addition, the observed frequencies of two HLA haplotypes: Bw62, DR4, DQw3 and Bw60, DR4, DQw3 were significantly higher than expected. CONCLUSION: --If these observations are confirmed in the larger series of patients, the association between RDEB and HLA complex may have clinical utility in genetic counseling of siblings of child-bearing age who are at risk of being carriers of RDEB.

Adolescent↗
PubMed1990

Double-negative (CD4- CD8-) T cells with an alpha/beta T cell receptor. Non-MHC-restricted cytolytic activity and lymphokine production.

T cell lines with a novel phenotype (CD3+ TCR-alpha/beta+ CD4- CD8-) were developed from the peripheral blood of a patient with a combined immunodeficiency and tissue injury resembling graft-vs-host disease. One of these IL-2-dependent T cell lines demonstrated non-MHC-restricted cytolytic function against tumor targets, syngeneic and allogeneic fibroblasts, and PHA blasts from allogeneic donors. The other cell line only became cytotoxic in the presence of lectin or anti-CD3 antibody. The two cell lines also differed in their expression of the T-200 gene products CD45RO (gp180) and CD45RA (gp220). Both cell lines produced tumor necrosis factor-alpha and -beta and IFN-gamma activity when activated with mitogens or PMA and IL-1. The in vitro functions of these T-cell lines suggest a potential role for alpha/beta double-negative T lymphocytes in tissue injury resembling graft-vs-host disease.

Antigens, CD↗
PubMed1989

Contributions and clinical significance of IgM and autoantibodies in highly sensitized renal allograft recipients.

The contributions of auto and IgM antibodies in the levels of serologic reactivities of 30 highly sensitized patients were assessed by autologous T cell crossmatches at 4 degrees C and 22 degrees C and dithiothreitol (DTT) reduction of IgM antibodies. The range of panel reactivities of sera from these patients was 30-100%, median 55%. A monthly screen of these sera against a 30-member T cell panel was performed with and without addition of DTT (final concentration = 0.005 M). The results were divided into 3 groups. Group 1 consisted of 17 sera whose PRA values did not change following the DTT treatment. Also none of these sera had autoantibodies, suggesting that these sera contained DTT-resistant (IgG) antibodies, most likely directed against allogeneic targets. Group 2 consisted of 10 sera whose PRA values declined substantially (20-42%) following the DTT treatment, but only 1 serum derived from a patient with systemic lupus erythematosus had autoantibodies. These results suggested that although these sera contained IgM and IgG antibodies, these antibodies were most likely directed at allogeneic target structures with only one exception. Group 3 consisted of 3 sera that became completely unreactive to panel lymphocytes following the DTT treatment. All 3 sera had autoantibodies that were also removed with DTT, suggesting that these sera contained predominantly IgM antibodies directed at autologous target cells. All 3 patients from whom these sera were derived received successful kidney transplants across donor-specific positive T cell crossmatches that became negative following the DTT treatment. We conclude that although 13 out of 30 patients have IgM antibodies, only a small subset of these patients have autoantibodies. Renal transplantation in the presence of auto/IgM antibodies may be safe.

Antilymphocyte Serum↗
PubMed1989

Heterogeneity of CD4-positive human T-cell clones which recognize the surface protein antigen of Rickettsia typhi.

Immunity to the typhus group of rickettsiae is largely dependent on the effector function of several classes of T lymphocytes, including those which produce gamma interferon. Since the surface protein antigen (SPA) derived from typhus group rickettsiae has been shown to be an effective immunogen in animal models, human T-cell clones specific for the SPA of Rickettsia typhi were isolated and tested for their antigenic specificity, as well as for their ability to produce gamma interferon. Eighteen CD4-positive clones specific for the SPA of R. typhi exhibited considerable diversity in their response to the SPAs derived from two strains of Rickettsia prowazekii and from Rickettsia canada. The vast majority of clones also recognized the SPAs from R. prowazekii but not from R. canada. Two heteroclitic clones demonstrated significantly higher proliferative responses to the SPAs derived from one or both of the R. prowazekii strains than to the SPA of R. typhi, and one clone demonstrated a significantly higher response to the SPA of R. typhi than to the other SPAs. All 18 clones produced gamma interferon in response to SPA stimulation. We conclude that the SPAs from typhus group rickettsiae can elicit both a diverse T-cell response in humans and the efficient stimulation of gamma interferon-mediated immunity.

Antigens, Bacterial↗
PubMed1989

Further studies on the influence of dibutyryl cAMP, theophylline and prostaglandin E1 on composition and biosynthesis of phospholipids in Microsporum gypseum.

Exogenous supplementation of dibutyryl cAMP and cAMP modulators like theophylline and prostaglandin E1 in the growth medium of Microsporum gypseum lead to increase in the levels of phosphatidylcholine and lysophosphatidylcholine and thereby in total phospholipid content. These observations were further confirmed by the increased incorporation of [32P]orthophosphoric acid into total phospholipid and [14C]choline into phosphatidylcholine and lysophosphatidylcholine. The activity of sn-glycerol-3-phosphate acyltransferase, the enzyme involved in phospholipid synthesis, was stimulated in the presence of dibutyryl cAMP, theophylline and PGE1 supporting the increased synthesis of phospholipids.

Alprostadil↗
PubMed1989

Influence of supplementation of saturated alkanes on the membrane properties of Microsporum gypseum.

Microsporum gypseum cells grown on saturated alkanes of different chain lengths (C10, C12, C14, C16 and C18) exhibited increased levels of total phospholipids and sterols. A significant increase in the content of phosphatidylcholine was observed in alkane-grown cells. Increased saturation of phospholipid fatty acid was observed with all the alkanes studied, which was mainly due to the decreased amount of C18:1 and C18:2 with concomitant increase in the levels of palmitic acid. The affinity for glycine changed in alkane-supplemented cells as compared to glucose-grown cells. 1-Anilino-naphthalene-8-sulphonate (ANS) binding to the spheroplast membrane demonstrated increased binding sites in supplemented cells. These results are discussed in terms of the effect of altered lipid composition on the membrane structure and function of this fungus.

Alkanes↗
PubMed1988

Effect of dibutyryl cyclic AMP on lipid synthesis in Microsporum gypseum.

The influence of intracellular levels of cAMP on the lipid synthesis of Microsporum gypseum has been examined by exogenous supplementation of dibutyryl cAMP and its activators/inhibitors. Incorporation of [14C]acetate into various lipid fractions of M. gypseum was markedly enhanced in the presence of dibutyryl cAMP and its modulators, probably as a consequence of increased intracellular cAMP levels, which, in turn, affected the lipid biosynthesis. Increased activities of phosphatidic acid phosphatase, glycerol kinase, ethanolamine kinase and choline kinase in the presence of these additives supports the enhanced synthesis of phospholipids and suggests that lipid biosynthesis is being controlled by cAMP in M. gypseum.

Alprostadil↗