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Biomedical subjects

C Mandal

Publications and source records attributed to C Mandal.

64 records · Page 4Linked to original sources
PubMed1978

Kinetic studies on the interaction of gold (III) with nucleic acids. IV. RNA-Au (III) system.

The kinetics of the interaction of Au(III) with whole yeast RNA has been studied using UV-spectrophotometry. The reaction is second order with respect to the nucleotide unit of RNA and first order with respect to Au(III) in the respective stoichiometry of 2 : 1. The effects of initial composition, temperature, ionic strength, pH and chloride ion on the kinetics have been studied. Activation energy is found to be 11.5 kcal/mol. Effect of ionic strength indicates that both the positively charged and neutral species of Au(III) take part in the rate limiting step, the former being dominant at low ionic strength. A plausible mechanism has been proposed which involves the interaction of two nucleotide units of RNA with one species of Au(III) in the rate limiting step.

Chemical Phenomena↗
PubMedDate not supplied

Production of highly specific polyclonal and monoclonal antibodies using estradiol-3-O-carboxymethyl ether as hapten.

The preparation of high affinity and high specificity polyclonal and monoclonal antibodies to estradiol is described. Monoclonal antibodies were derived from BALB/c mice hyperimmunized with estradiol-3-O-carboxymethyl ether conjugated to bovine serum albumin. Spleen cells were hybridized with mouse myeloma cells. Quite a few monoclonal antibodies showed very good affinity for estradiol. Extended immunization and hyperimmunization were essential for producing a greater number of positive clones secreting high affinity antibodies. Binding constants of the antisera and their cross-reactivities with related steroids were calculated. Both polyclonal and monoclonal antibodies showed very high affinity for estradiol exhibiting little or no cross-reactivities with structurally related steroids indicating that this site of linkage is a good choice for discriminating between differences at the 16-17 position in the D-ring. This monoclonal antibody (44.28.6), having negligible cross-reactivity with estriol and estrone, can be used for diagnostic purposes.

Animals↗
PubMedDate not supplied

The polyclonal activation of lymphocytes and T cell mitogenicity by a unique sialic-acid-binding lectin from the hemolymph of Achatina fulica snail.

A unique sialic-acid-binding lectin, AchatininH, isolated from the hemolymph of Achatina fulica snail was found to be strongly mitogenic, as monitored by [3H]thymidine incorporation assay, to rat and human lymphocytes. However, the degree of mitogenic response varied with the type of cell population. As indicated, this lectin induced proliferation of purified T lymphocytes and rat thymocytes, whereas it was less mitogenic towards peripheral lymphocytes of pregnant rats and was not mitogenic towards B lymphocytes. Furthermore, the mitogenic response was inhibited by the sialic-acid-containing disaccharide, a strong inhibitor of this lectin. This suggests that lymphocyte cell surface molecules containing sialic acid residues are important for this interaction and may have a structure similar to that of AchatininH receptors. Although this lectin showed strong mitogenicity towards lymphocytes, it showed very weak leucoagglutination. Surprisingly, PHA-induced blastogenesis was inhibited by the same dose of AchatininH as caused mitogenic activity in resting lymphocyte culture. The degree of suppression was higher for the lymphocytes isolated from pregnant rat blood compared to the non-pregnant control. Since the 51Cr-uptake assay and the cell viability test results negate the potential cytotoxic activity of this protein, the immunosuppression induced in the presence of PHA by AchatininH may be the additive effect of two mitogens causing an increased cell-density-dependent arrest. AchatininH does not have complement-like activity, but induces potent polyclonal activation of B cells as measured by the reverse hemolytic plaque assay.

Adult↗
PubMedDate not supplied

Development and characterization of five monoclonal antibodies against neuronal cell surface antigens--evaluation of their use in cell separation by affinity chromatography.

Five monoclonal antibodies directed against rat neuronal cell surface proteins have been isolated and characterized following fusion of mouse SP2/O-Ag-14 myeloma cells and spleen cells from BALB/c mice immunized with neuron-specific membrane proteins. The antibodies displayed cell specificity in binding and elicited precipitation of different polypeptides from total neuronal cell surface proteins. These antibodies are of potential use in the isolation of a neuronal subpopulation by immunoaffinity chromatography. The work represents the application of hybridoma technology for the isolation of specific types of neuronal populations.

Animals↗
PubMedDate not supplied

Effect of environmental pollutants on the C-reactive protein of a freshwater major carp, Catla catla.

C-reactive proteins (CRP) have been affinity purified to electrophoretic homogeneity from the sera of major carp, Catla catla before and after exposure to environmental pollutants. Exposure to these pollutants elevate the levels of circulating CRPs to 2.8-3.5 times the normal values. Kinetic studies of metal intoxication indicate that a unique molecular variant of CRP is present in the serum at the peak level of acute phase induction, and this variant coexists with normal CRPs. Carbohydrate analysis and lectin binding reveals that these CRPs are glycoproteins differing significantly in total carbohydrate contents. Their electrophoretic mobilities in native gel are different but become identical on desialylation and deglycosylation implying that the molecular variants vary in the glycan parts. All these forms of CRP contain two nonidentical subunits of Mr 22 and 29 kDa. Examination of their immunological crossreactivity demonstrate their similarity in overall molecular topology but their differences in the quantitative extent of binding are reflected.

Animals↗
PubMedDate not supplied

Investigation on interaction of Achatinin, a 9-O-acetyl sialic acid-binding lectin, with lipopolysaccharide in the innate immunity of Achatina fulica snails.

Achatinin, a 9-O-acetyl sialic acid (9-O-AcSA) binding lectin, has been demonstrated to be synthesized in amoebocytes of Achatina fulica snails. This lectin was affinity-purified from Achatina amoebocytes lysate (AAL); it appeared as a single band on native polyacrylamide gel electrophoresis (PAGE) and showed 16 identical subunits of M.W. 15 kDa on sodium dodecyl sulphate (SDS)-PAGE. It was found to be homologous with an earlier reported lectin, Achatinin-H, derived from hemolymph of A. fulica snails (Sen, G., Mandal, C., 1995. The specificity of the binding site of Achatinin-H, a sialic-acid binding lectin from Achantia fulica. Carbohydr. Res., 268, 115-125). Homology between both lectins was confirmed by their similar electrophoretic mobilities, carbohydrate specificity and cross reactivity on immunodiffusion. Achatinin showed in vitro calcium dependent binding to two 9-O-acetylated sialoglyoconjugates (9-O-AcSG) on lipopolysaccharide (LPS) (Escherichia coli 055: B5) of M.W. 40 kDa and 27.5 kDa, which was abolished following de-O-acetylation. Based on the previously defined narrow sugar specificity of Achatinin towards 9-O-AcSAalpha2-->6GalNAc [Sen, G., Mandal, C., 1995. The specificity of the binding site of Achatinin-H, a sialic-acid binding lectin from Achatina fulica. Carbohydr. Res., 268, 115-125], we conclude that LPS contains this lectinogenic epitope at the terminal sugar moiety. The Achatinin-mediated hemagglutination inhibition of rabbit erythrocytes by LPS further confirmed it. The lectin exhibited bacteriostatic effect on Gram-negative bacteria E. coli, DH5alpha and C600. AAL was earlier reported to undergo coagulation in presence of pg level of LPS (Biswas, C., Mandal, C., 1999. The role of amoebocytes in the endotoxin-mediated coagulation in the innate immunity of Achatina fulica snail, Scand. J. Immunol. 49, 131-138). We now demonstrate that Achatinin participates in LPS-mediated coagulation of AAL as indicated by enhanced release of Achatinin from the LPS stimulated amoebocytes and most importantly, by exhibiting a 77% decline in the coagulation of AAL when depleted of Achatinin. Level of Achatinin sharply declined (17-fold) following injection of LPS (20 microg per snail) to the snails, which was reversible by simultaneous injection of LPS and leupeptin implying the presence of LPS-mediated serine protease activity in Achatinin. This was substantiated when purified Achatinin in vitro showed serine protease activity in the presence of LPS followed by its complete blockage in the presence of leupeptin and phenyl methyl sulphonyl fluoride. Therefore, Achatinin, an abundantly available lectin at multiple sites of A. fulica, by virtue of its interaction with LPS, essentially plays a crucial role in the innate immune protection of A. fulica snails.

Animals↗
PubMedDate not supplied

O-acetyl sialic acid binding lectin as a probe for detection of subtle change on cell surface induced during acute lymphoblastic leukemia (ALL) and its clinical application.

A novel probe, a 9-O-acetylated sialic acid binding lectin, namely achatininH (ATNH) has been used for the detection of changes on the cell surface during acute lymphoblastic leukemia (ALL). ATNH does not agglutinate normal human erythrocytes, however it is capable of agglutinating erythrocytes and peripheral blood mononuclear cells (PBMC) of patients suffering from ALL. The differential expression of a key receptor, 9-O-acetylated sialo glyco conjugate (9-O-AcSG), on PBMC was observed using a simple lymphoproliferative assay (LA). The extent of expression of 9-O-AcSG was used as an index to distinguish ALL patients of different clinical stages and assess the probability of relapse. The amount of ATNH needed for maximum stimulation served as a tool to indirectly measure the extent of expression of 9-O-AcSG on PBMC surface. The acetylated sialo glycoconjugate was expressed at a very high concentration during acute phase of the disease. Subsequently it decreased during treatment persisted during maintenance therapy and reappeared with relapse. PBMC of normal human donors required 80 times more ATNH in comparison to the untreated acute phase ALL patients. No cross reactivity was found in non Hodgkin's lymphoma, chronic myelogenous leukemia and thalassaemia patients.

Agglutination Tests↗