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Biomedical subjects

S Pal

Publications and source records attributed to S Pal.

At least 145 records · Page 8Linked to original sources
PubMed1993

Effect of intravenous nitroglycerin on heparin dosage requirements in coronary artery disease.

Patients admitted to the coronary care unit who received both intravenous nitroglycerin and heparin were studied to evaluate heparin dosage requirements. Physicians ordered all nitroglycerin and heparin doses as well as coagulation studies without knowledge of this study. Activated partial thromboplastin time (APTT) values obtained during steady-state heparin administration were considered therapeutic if the ratio of APTT/APTT-baseline was > or = 1.5. Sixty patients with myocardial infarction or unstable angina were included in the study. The initial therapeutic heparin dose of 1,014 +/- 151 units/hour produced an APTT ratio of 2.0 +/- 0.5. At the time of the initial therapeutic dose, the nitroglycerin dose was 110 +/- 108 micrograms/min. There was a significant correlation between the initial therapeutic dose and both total (r = 0.56; p = 0.0001) and lean (r = 0.26; p < 0.05) body weight. Comparison of patients with nitroglycerin doses < and > or = 100 micrograms/min revealed a significant difference in the initial therapeutic dose (971 +/- 147 vs 1,077 +/- 136 U/hour, p < 0.01), but not the initial therapeutic dose standardized to total body weight (14.0 +/- 2.5 vs 13.5 +/- 2.7 U/kg/hour). Similarly, analysis of variance revealed a significant difference in the initial therapeutic dose (p < 0.05), but not the initial therapeutic dose standardized to weight among 5 different nitroglycerin dosage ranges (10 to 533 micrograms/min). Neither aspirin use, thrombolytic therapy nor decreasing or discontinuing the nitroglycerin dose significantly affected heparin requirements. Thus, contrary to prior reports, clinically significant heparin resistance induced by nitroglycerin was not found.

Aged↗
PubMed1993

Activation of UDP-galactose:globotriaosylceramide alpha 1-3-galactosyltransferase during PC12D cell differentiation induced by galactosylceramide.

We measured the activities of UDP-galactose:globotriaosylceramide alpha 1-3-galactosyltransferase (alpha-GalTase) and protein kinase C (PKC) in PC12D pheochromocytoma (PC12D) cells which were induced to differentiation by nerve growth factor (NGF), forskolin (FRK), staurosporine (STP), retinoic acid (RA), 2-chloroadenosine (ClAd), and/or galactosylceramide (GalCer). NGF, STP, FRK, and RA were found to be stimulators for the PKC activity, whereas ClAd appeared to be an inhibitor of the enzyme. At the concentration of 25 microM, GalCer having normal fatty acids was found to be a stimulator, whereas GalCer having hydroxy fatty acids was ineffective in modulating the PKC activity. Interestingly, all stimulators of PKC activities, including GalCer having normal fatty acids, appeared to be activators for the alpha-GalTase activity. On the other hand, GalCer having alpha-hydroxy fatty acids had no effect and ClAd was found to be a potent inhibitor for the alpha-GalTase activity. These data suggest that alpha-GalTase activity during PC12D cell differentiation may be regulated by a PKC-dependent process.

Alkaloids↗
PubMed1993

Effects of blood flow, curved boundary and environmental conditions on temperature distribution in a two dimensional model of human skin and subcutaneous tissues.

A mathematical model for the study of the effects of blood flow, metabolic heat production, various environmental conditions and the presence of a curved boundary on the temperature distribution (TD) in a two dimensional model of human skin and subcutaneous tissues (SST) is presented. Based on physiological properties, the interfaces between epidermis-dermis (IED) and dermis-subcutaneous tissues (IDS) have been considered to be irregular and the regions of these layers have been divided into 109 triangular elements of various sizes which are connected with each other by 70 nodes. The results computed from this thermobiological mathematical model, using Galerkin's finite element technique, have been exhibited graphically. The effects of various environmental conditions, blood flow and metabolic heat production are found to be nonuniform on TD at the nodes situated at the same depth in SST. This nonuniformity in TD almost disappears at the nodes situated in dermis nearest to IDS except for the two of the six combinations, considered in the present study, in which highest values of blood flow and metabolic heat production have been considered. The rate of fall of temperature with respect to thickness (towards the skin surface) is higher at the straight boundary (SB) than at the curved boundary (CB). The temperature increases with respect to width (from SB to CB) in epidermis and dermis but decreases in subcutaneous tissues. This increase or decrease of temperature is more pronounced at the nodes situated near to, or at CB. The trend of these temperature profiles in SST reflects the dependence of TD not only on the environmental conditions and biophysical variables but also on the geometry of SST.

Body Temperature Regulation↗
PubMed1993

Biochemical and immunological studies on soluble antigens of Entamoeba histolytica.

The soluble antigens of Entamoeba histolytica trophozoites were analysed in detail by biochemical and immunochemical methods. The antigen was highly complex and heterogeneous as revealed by Sephacryl S-300 column chromatography, which showed four distinct fractions. The molecular mass of fractions FI, FII, FIII and FIV was 660, 170, 65 and 13 kDa, respectively. Protein was the major constituent in crude soluble antigen (CSA) and fractions FI and FII (67%, 80% and 90%, respectively). Polysaccharide was predominant in the FIII fraction (59%). Antigenic activity observed after different physico-chemical treatments revealed that CSA and FI antigens were predominantly glycoprotein in nature. However, the antigenicity of FIII antigen was greatly reduced after sodium meta-periodate treatment, whereas no alteration in reactivity was discerned after trypsin treatment. Sodium dodecyl sulphate-polyacryl-amide gel electrophoresis (SDS-PAGE) analysis demonstrated nearly 28 Coomassie blue bands for CSA and 20, 16, 15 and 3 polypeptide bands for the FI, FII, FIII and FIV fractions, respectively. The molecular mass of the polypeptides of these bands ranged from 210 to 20 kDa. Antigenic activity was observed in CSA and in the first three fractions, both in counter immunoelectrophoresis (CIEP) and in enzyme-linked immunosorbent assay (ELISA). However, the highest antigenic activity was noted in fraction FI. Major immunoreactive polypeptides of CSA and FI antigens against whole trophozoite antibody were observed in the 10- to 170-kDa regions. However, major differences in the immunoreactivity of the two antigens were noted at 116 and 14 kDa for FI antigen and at 84, 30 and 20 kDa for CSA.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Dipeptidyl peptidase I from goat brain: purification, characterization and its action on Leu-enkephalin.

Brain dipeptidyl peptidase (DPP) I has been purified 2990-fold to apparent homogeneity shown by a single protein band in electrophoreses at pH 4.5, 8.4 and in SDS-PAGE at pH 7.2. The purification techniques included homogenization of brain acetone powder, autolysis at pH 4.2, 30-80% (NH4)2SO4 fractionation. Sephadex G-100 column chromatography, heat treatment at 65 C. organomercurial affinity chromatography. CM-Sephadex cation-exchange chromatographies at pH 5.6 and 5.0 and anion-exchange chromatography on DEAE-Sephadex at pH 6.8. The enzyme hydrolysed synthetic substrate Gly-Arg-4-methoxy-beta-naphthyl-amide maximally at pH 6.0. The Km values for Gly-Arg-beta-naphthylamide and Gly-Arg-4-methoxy-beta-naphthylamide substrates were 0.10 mM and 0.14 mM respectively. The enzyme was inhibited by thiol inhibitors like p-chloromercuribenzoic acid, iodoacetic acid, iodoacetamide and microbial inhibitors leupeptin and antipain. Molecular weight estimations on a calibrated Sephadex G-200 column afforded a value of 180,000 Da while in denaturing conditions on sodium dodecyl sulphate polyacrylamide gel electrophoresis, the subunit molecular weight was 22,000 Da. The subunit structure of the native enzyme was unfolded in presence of different concentrations of urea. In 8 M urea, the enzyme dissociated completely into monomers of 25,000 Da but 6, 5 and 4 M urea concentrations revealed the existence of dimers, tetramers and hexamers. Leu-enkephalin. Tyr-Gly-Gly-Phe-Leu was degraded by DPPI into Tyr-Gly and Gly-Phe-Leu with no further degradation of the newly generated tripeptide.

Amino Acid Sequence↗
PubMed1993

A selective colorimetric assay for cathepsin L using Z-Phe-Arg-4-methoxy-beta-naphthylamide.

Among the intracellular proteinases, the thiol proteinases such as cathepsin B (EC 3.4.22.1), cathepsin H (EC 3.4.22.16) and cathepsin L (EC 3.4.22.15) which act at slightly acidic pHs are more likely to play an important role in lysosomal protein catabolism. Out of these, cathepsin L plays a major role primarily because it has high degradative activity on cellular and matrix proteins. However, the studies on cathepsin L in crude homogenates and subcellular fractions have always been hampered by the lack of a specific substrate to exclusively measure the activity of this proteinase. The only synthetic substrate alpha-N-benzyloxycarbonyl-L-Phe-L-Arg-4-methoxy-beta-naphthylamide (Z-Phe-Arg-NNapOMe) which is hydrolysed by cathepsin L is hydrolysed equally well by cathepsin B. This substrate was manipulated to act as a selective substrate for cathepsin L. In presence of 4 M urea at pH 5.0, cathepsin B (the only other cathepsin which also hydrolyses Z-Phe-Arg-NNapOMe) was inactivated and, therefore, under these conditions, the enzyme activity quantitated by using this substrate is only due to cathepsin L. Using this newly-developed colorimetric assay method specific for cathepsin L, the subcellular and regional distribution of this proteinase were established in goat brain tissue. About 80% cathepsin L activity was recovered in the lysosomal fraction thus establishing its lysosomal nature. Among the various brain parts, highest activity was found in cerebrum followed by cerebellum, pituitary body, pons-varolli, thalamus, medulla-oblongata and hypothalamus.

Amino Acid Sequence↗
PubMed1993

Tumor inhibition and hematopoietic stimulation in mice by a synthetic copper-ATP complex.

The hematologic effect of [Cu3(ATP)(2)6H2O]2-, a synthetic copper-ATP complex (Cu-ATP) having antitumor activity, was investigated in normal and Ehrlich ascites carcinoma-bearing mice. Cu-ATP (25 mg/kg) induced appreciable tumor inhibition and prolonged host survival which were accompanied by elevated levels of hemoglobin, platelet and lymphocytes while total WBC count and bone marrow cellularity remained unaffected. In normal mice the compound elicited marrow and splenic hypercellularity with a greater number of granulocyte progenitors and elevated levels of peripheral WBC, RBC and platelets. In addition, the total number of CFU-S of these treated animals was increased and these pluripotent stem cells differentiate preferentially towards granulocyte lineage. The results indicate that Cu-ATP does not adversely affect hematopoiesis while it inhibits tumor growth; on the contrary, it has a stimulatory effect on murine granulocytopoiesis.

Adenosine Triphosphate↗
PubMed1993

Mapping of a surface-exposed B-cell epitope to the variable sequent 3 of the major outer-membrane protein of Chlamydia trachomatis.

A B-cell epitope, AEFPLDIT, was located to the variable sequent 3 of the major outer-membrane protein (MOMP) using the monoclonal antibody L3-1, raised to the Chlamydia trachomatis serovar L3 MOMP. By Western blot and inclusion immunofluorescence assay the monoclonal antibody recognized all the C complex and C-related complex serovars of C. trachomatis, except serovar C. Dot-blot and ELISA data using native elementary bodies indicated that the epitope was surface exposed. The monoclonal antibody, at concentrations of 10 and 100 micrograms per 10(7) chlamydial inclusion-forming units, was able to neutralize the infectivity of chlamydia in an in vivo assay but did not neutralize chlamydia in vitro or in a mouse toxicity assay. A peptide corresponding to the variable sequent 3 has previously been shown to also elicit a T-cell response; thus, careful consideration should be given to inclusion of this region of the major outer-membrane protein in a subunit vaccine.

Amino Acid Sequence↗
PubMed1993

Effects of antibody isotype and host cell type on in vitro neutralization of Chlamydia trachomatis.

Monoclonal antibodies (MAbs) E-4, E-21, and DIII A3, which recognize the same or similar overlapping peptides in the variable domain IV of the major outer membrane protein of Chlamydia trachomatis but differ in isotype, were used in a complement-independent (CI) in vitro neutralization assay. These MAbs had previously been shown to neutralize chlamydial infectivity in HeLa 229 cells in a complement-dependent assay. In this report, all three MAbs neutralized chlamydial infectivity in HaK cells in a CI assay. However, when HeLa cells were used as the host cell, MAb E-4 (immunoglobulin G2b [IgG2b]) and MAb DIII A3 (IgG2b) failed to neutralize infectivity, while MAb E-21 (IgG1) neutralized chlamydial infectivity. These findings are consistent with the proposal that because of the presence of Fc gamma RIII receptors, HeLa cells facilitate infectivity and thus block neutralization through the uptake of an IgG2b-chlamydia complex. Since Fc gamma RIII receptors do not bind or bind poorly to IgG1, neutralization of C. trachomatis by MAb E-21 in HeLa cells is also corroborative evidence for the role of Fc gamma RIII receptors in this interaction. A fivefold enhancement of infectivity was seen when 10 and 1 micrograms of MAb E-4 per ml were tested in a CI assay with HeLa cells. In performing CI neutralization synergy studies in HeLa cells with MAbs E-4 and E-21, antagonism between MAbs E-4 and E-21 was observed at MAb E-4 concentrations of 10 and 1 micrograms/ml for all concentrations of MAb E-21 tested (10 to 0.1 micrograms/ml). When HaK cells were used in the same studies, no antagonism between the MAbs was found. In addition, when HeLa cells were used in a CI assay, polyclonal serum raised to a peptide representing variable domain IV of the major outer membrane protein inhibited the neutralizing ability of MAb E-21. The blocking of neutralization and the enhancement of infectivity by chlamydia-specific antibodies seen in this investigation with HeLa cells may have important clinical implications for developing preventive strategies for chlamydial infections.

Amino Acid Sequence↗
PubMed1993

Analysis of the immune response in mice following intrauterine infection with the Chlamydia trachomatis mouse pneumonitis biovar.

A Swiss Webster white mouse model of salpingitis was used to characterize the immune response following an intrauterine infection with the Chlamydia trachomatis mouse pneumonitis biovar. Western blot (immunoblot) analyses of the serum samples showed that the immunodominant bands corresponded to molecular masses of 72, 60, 42, and 28 kDa and to the lipopolysaccharide. Antibodies to the 60-kDa heat shock protein and to the 60-kDa cysteine-rich protein were detected at 2 and 3 weeks postinfection, respectively. Neutralization was observed in an in vitro assay with serum samples as early as the 3rd day postinfection and remained high for the 7 weeks of observation. The mice were mated in the 7th week following infection. Of the infected experimental mice, 71.4% were found to be either unilaterally or bilaterally infertile, whereas only 27.4% of the noninfected control mice were found to be infertile.

Animals↗
PubMed1993

Effect of some pesticides/weedicides on cathepsin B activity and lysosomal membrane.

The in vitro inhibitory effects of various weedicides and pesticides on goat brain cathepsin B and their labilizing potency on the lysosomal membrane were quantitated. Endosulfan an organochlorine insecticide inhibited the enzymic activity to approximately 50% at 7 mM concentration followed by methyl parathion, aldrin, melathion and benzene hexachloride (BHC) in that order. Among the weedicides, butachlor was found to be most inhibitory (approximately 50% activity was lost at 6 mM) followed by isoproturone (28%) and anilophos (19%). When the labilizing/stabilizing potency of all these drugs was observed on lysosomal membrane it was found that none of these was capable of stabilizing the membrane. At 40 degrees C and 1 mM drug concentration, aldrin, endosulfan, melathion and anilophos were found to be strong labilizers of the lysosomal membrane. Others like isoproturone, BHC and methyl parathion had moderate labilizing effect. The labilization potency of the drugs was temperature dependent and was less pronounced at 25 degrees C as compared to 40 degrees C.

Animals↗
PubMed1992

Investigation on glutamine amidohydrolase (EC 3.5.1.2) and glutamine aminotransferase (EC 2.5.1.15) activity in liver and plasma of EAC-bearing mice following glutaminase therapy.

The anti-neoplastic activity of bacterial glutaminase on Ehrlich ascites tumor-bearing mice was studied by determining the reduction in the tumor cell count and extension of life span of the host after therapy. The therapeutic effect of glutaminase in relation to change in activity of glutaminolytic enzymes (glutamine amidohydrolase (GNase) and glutamine aminotransferase (GAt)) in liver and plasma were also studied. Bacterial glutaminase was shown to be effective in lowering the tumor burden with increased life span of the host. Glutamine amidohydrolase activity in the liver and plasma was raised significantly with increased tumor burden, whereas GAt activity remained unchanged. Following glutaminase therapy, this high level of GNase activity decreased in comparison to the untreated control. These changes were not seen when normal mice were treated with the same enzyme. Thus alteration in the enzyme levels, particularly GNase was observed to have some correlation with progression of the tumor growth.

Animals↗
PubMed1992

Frequency of antigen-specific B cells during experimental ocular Chlamydia trachomatis infection.

Chlamydia-specific antibody-secreting cells have been identified in conjunctiva and draining cervical lymph nodes by an ELISPOT assay in a cynomolgus monkey model of trachoma. These local sites contained numbers of chlamydia-specific B cells that were higher than those in distant inguinal lymph nodes and peripheral blood. The numbers of chlamydia-specific immunoglobulin G-secreting B cells observed were 5 to 57 per 10(6) cells in conjunctiva and 24 to 996 per 10(6) cells in cervical lymph nodes during conjunctival infection or after challenge of immune monkeys with the chlamydial 57-kDa heat shock protein (hsp60). These studies demonstrate a large chlamydia-specific B-cell component in the conjunctiva during ocular chlamydial infection. These results are similar to our findings for chlamydia-specific T-cell responses.

Animals↗