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Biomedical subjects

P C Sen

Publications and source records attributed to P C Sen.

At least 55 records · Page 3Linked to original sources
PubMed1989

Effect of exogenous 5-hydroxytryptamine on pathogenicity of Entamoeba histolytica in experimental animals.

In an effort to find out the mechanism(s) operative in enhancing the pathogenicity of E. histolytica in hosts under heat stress reported earlier, effect of 5-hydroxytryptamine (5-HT) on the virulence of the parasite was examined in just weaned Charles Foster strain of albino rats. Pathogenicity of 10 strains of E. histolytica, from various forms of intestinal amoebiasis, grown in modified Boeck and Drbohlav's medium was assessed by caecal scoring. Administration of 5-HT in infected animals significantly enhanced the pathogenicity of all the seven strains tested. Treatment of the host with the 5-HT precursor L-tryptophan also increased the caecal scores examined with three strains of E. histolytica. Prior blocking of tissue 5-HT receptors by administration of methysergide almost completely abolished the pathogenicity enhancing effect of 5-HT treatment. This suggested that 5-HT itself and not any of its metabolites was responsible for the observed increase in pathogenicity of E. histolytica on 5-HT treatment of the host.

Animals↗
PubMed1988

Identification and characterization of a Mg2+-dependent and an independent Ca+2-ATPase in microsomal membranes of rat testis.

Rat testicular microsomal membrane fraction contains both Mg+2-dependent and Mg+2-independent Ca+2-ATPase activity. The latter activity is about two times higher than the former. Calcium ion required for maximum activation of Mg+2-independent Ca+2-ATPase in 3.0 mM, whereas for the dependent one it is 2.5 mM. Both the enzymes are resistant to cold shock upto seven days. Histidine and imidazole buffers are found to be the most suitable for dependent and independent enzyme activities, respectively. The pH optima for dependent one is 7.5, whereas for the independent one it is 8.5. Temperature optima for the former is 37 degrees C and for latter one it is 40 degrees C. Among all the nucleotides tested, ATP is found to be the best substrate for both the enzymes. The optimum concentration of ATP for dependent and independent enzyme activities are 3.0 mM and 1.5 mM respectively. Divalent metal ions like Zn+2, Ba+2 and Mn+2 have been found to inhibit Mg+2-dependent Ca+2-ATPase activity whereas Mg+2-independent Ca+2-ATPase activity is inhibited by the divalent ions except zinc which is found to stimulate the enzyme activity. Both the enzymes are inhibited by vanadate, EDTA and EGTA. I50, for vanadate is 0.05 and 0.125 mM for dependent and independent activities, respectively. Sulfhydryl groups modifying agents e.g., NEM, DTNB and chlorpromazine are found to affect the enzyme activities in different ways. Thus NEM and chlorpromazine are found to inhibit and DTNB stimulate the enzyme activities in both the cases.

Animals↗
PubMed1988

Purification and characterization of a low molecular weight basic protein from marine turtle egg white.

The egg white of marine turtle (Caretta caretta Linn.) and one species of tortoise (Geomyda trijuga trijuga Schariggar) contain a low molecular weight basic protein. It has been purified to homogeneity from the egg white of marine turtle and characterized in terms of its major physicochemical and chemical properties. The molecular weight of this protein calculated from gel filtration, sodium dodecyl sulfate-gel electrophoresis in the presence of urea, sedimentation-diffusion data, and amino acid composition is 4300. Its isoelectric point is at pH 11.1 and intrinsic viscosity is 0.038 dl g-1 in 0.2 M NaCl. It has a Stokes radius of 12.6 A and a diffusion coefficient of 16.50 x 10(-7) cm2 s-1. Analysis of the far-ultraviolet circular dichroic spectrum has shown that the basic protein contains 27% beta-pleated sheet and little or no alpha-helix. It possesses a single polypeptide chain of 40 amino acid residues with three disulfide bonds. It lacks serine, methionine, phenylalanine and carbohydrate moiety. It binds to DNA and stimulates ATPase activity due to its strong basicity. The complex of DNA-basis protein is partially resistant to the action of DNase.

Amino Acids↗
PubMed1988

The interaction of chloroquine with transport ATPase and acetylcholine esterase in microsomal membranes of rat in vitro and in vivo.

Chloroquine, an antimalarial drug has been found to inhibit Na+, K+-ATPase activity in vitro in the microsomal membranes of rat brain on time, temperature and concentration dependent manner. There have been stimulation of Na+,K+-ATPase, Ca+2-ATPase and acetylcholine esterase activities in vivo studies at lower concentration of drug or shorter period of treatment with the drug, whereas higher concentrations or longer periods of treatment lead to inhibition in the microsomal membranes of different organs.

Acetylcholinesterase↗
PubMed1986

Persistent stimulation of lens fiber cell Na,K-ATPase by sodium thiocyanate.

The Na,K-ATPase partially purified from porcine lens fiber cells (Sen and Pfeiffer, 1982) is stimulated fourfold (specific activity) by treatment with sodium thiocyanate. The optimum conditions are 1.5 M NaSCN, 2 mg protein ml-1 reaction mixture, pH 7.0, with incubation continued for 30 min at 23 degrees C. Sodium docecyl sulphate-gel electrophoresis and [3H]ouabain binding studies indicate that the extent of purity is not increased significantly by the procedure. The high-activity preparation has elevated phospholipid:protein and phosphatidylethanolamine:sphingomyelin ratios compared with the deoxycholate-extracted starting material. The cholesterol:phospholipid ratio and phospholipid acyl group composition are not significantly altered by SCN- treatment. Measurements of 1,6-diphenyl-1,3,5-hexatriene fluorescence polarization show that SNC- treatment produces approximately a 5 degrees C decrease in a membrane phase transition temperature. The phase transition also affects the activation energy of the Na,K-ATPase reaction and probably reflects the onset of the gel to liquid crystalline transition rather than the midpoint location of the transition per se. p-Nitrophenylphosphatase activity and Na,K-ATPase activity in the gel state membrane are also increased by SCN- treatment. Increased specific activity may result, in part, from a membrane fluidity-dependent enzyme activation but is also due, in part, to the expression of latent enzyme activity. Using ouabain-binding data and the specific activity of the activated preparation, it can be shown that the turnover number of the fiber cell enzyme is approximately 1% of that observed in most other tissues.

Animals↗
PubMed1986

Immunodiagnosis of filariasis.

The sensitivity and specificity of the enzyme-linked immunosorbent assay (ELISA), the indirect haemagglutination (IHA) test and the counter-current immuno-electrophoresis test (CIEP) were assessed in the diagnosis of filariasis. Positive reactions were observed in 91% and 86% of cases by ELISA and IHA respectively. CIEP detected only 31.5% of cases. Cross-reaction due to intestinal nematodes was observed in 80% of cases by both ELISA and IHA whereas with CIEP cross-reaction was observed in 10% of cases. The microfilaria count was inversely proportional to the antibody titre among asymptomatic carriers. ELISA was the most sensitive test, followed by IHA and then CIEP. CIEP, though it detected only a small number of cases, was observed to be the most specific.

Antigens, Helminth↗
PubMed1985

Effect of levamisole on bacterial index in BL and LL leprosy.

A 150 mg levamisole tablet once in every fortnight along with specific antileprosy drugs were administered to ten patients each in BL and LL groups of leprosy. A similar number of patients in each group receiving only specific antileprosy treatment served as controls. After 11/2 years of study a more significant improvement was noted in the bacteriological status in the levamisole-treated group. Thus, levamisole can be used as an effective adjunct for quicker recovery in lepromatous patients.

Adult↗