• Volume 14, Issue 4

      December 1989,   pages  329-410

    • Effect of experimentally induced thyrotoxicosis on oxidative energy metabolism in rat heart mitochondria

      S S Katyare F R Billimoria

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      Treatment of rats with T3 resulted in a significant decrease in body weight, while the heart weight increased. T4 treatment had less marked effect on body weights but resulted in decreased heart weights. Serum T4 levels decreased significantly with simultaneous increase of T3 level following T3 treatment, whereas with T4 treatment, levels of both T4 and T3 increased in the serum. Low doses of T3 (0.5 µg ) caused decrease in mitochondrial protein content while high dose of T4 (1 µg), caused significant increase in mitochondrial mass. The state 3 respiration rates were significantly depressed following T3 and T4 treatments, in a substrate specific manner with the effects being more pronounced with T3; these responses with T4 were dose-dependent for succinate and ascorbate + N,N,N′,N′-tetramethyl-p-phenylenedíamme. State 4 respiration rates also exhibited similar corresponding changes. ADP/O ratios were not changed but ADP-phosphorylation rates were decreased significantly particularly so with the T3-treated animals. Treatment with T3 also resulted in lowering of intramitochondrial cytochrome contents. Similar effects were seen also with higher doses of T4. The results thus indicate that T3- and T4- thyrotoxicosis results in impaired energy metabolism in heart mitochondria.

    • Altered kinetic properties of rat heart mitochondrial enzymes following experimental-thyrotoxicosis

      B N Dave F R Billimoria S S Katyare

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      Effects of T3- and T4-induced thyrotoxicosis on temperature-dependent Arrhenius kinetics of succinate oxidase and Mg2+- and Mg2+ + 2,4-dinitrophenol-dependent ATPase activities in rat heart mitochondria were examined, For succinate oxidase system, treatment with T3 and T4 caused increase in the energy of activation in high temperature range in a dose-dependent manner. For low temperature range, increase in energy of activation was apparent only with higher doses of the hormones; with low doses a small but reproducible decrease was evinced. The phase transition temperature decreased significantly under these conditions. For the Mg2+- and Mg2++2,4-dintro-phenol-dependent-ATPase activities, the activation energy values in high temperature range decreased in general. Activation energy values in low temperature range recorded a generalized increase in the Mg2+-ATPase enzyme system while the value did not change significantly for the Mg2+ + 2,4-dinitrophenol-ATPase; phase transition temperature registered a small but reproducible decrease under these conditions. The results are suggestive of increased membrane fluidization possibly through increased proportion of unsaturated fatty acids. The differential effects seen for succinate oxidase and ATPase systems are consistent with different lipid protein domains of these enzyme systems.

    • Protease inhibitors from jackfruit seed (Artocarpus integrifolia)

      A V Bhat T N Pattabiraman

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      Protease inhibitory activity in jackfruit seed (Artocarpus integrifolia) could be separated into 5 fractions by chromatography on DEAE-cellulose at pH 7.6. A minor fraction (I) that did not bind to the matrix, had antitryptic, antichymotryptic and antielastase activity in the ratio 24:1.9:1.0. Fraction II bound least tightly to the ion exchanger eluting with 0.05 M NaCl and could be resolved into an elastase/chymotrypsin inhibitor and a chymotrypsin/trypsin inhibitor by chromatography on either immobilized trypsin or phenyl Sepharose CL-4B. Fractions III and IV eluted successively with 0.10 M NaCl and 0.15 M NaCl from DEAE-cellulose, inhibited elastase, chymotrypsin and trypsin in the ratio 1.0: 0.53:0.55 and 1.0:8.9:9.8 respectively. Fraction V, most strongly bound to the matrix eluting with 0.3 M NaCl and was a trypsin/chymotrypsin inhibitor accounting for 74% of total antitryptic activity. This inhibitor was purified further. The inhibitor with a molecular weight of 26 kd was found to be a glycoprotein. Galactose, glucose, mannose, fucose, xylose, glucosamine and uronic acid were identified as constitutent units of the inhibitor. Dansylation and electrophoresis in the presence of mercaptoethanol indicated that the inhibitor is made up of more than one polypeptide chain. The inhibitor combined with bovine trypsin and bovine α-chymotrypsin in a stoichiometric manner as indicated by gel chromatography. It had very poor action on subtilisin BPN′, porcine elastase, pronase,Streptomyces caespitosus protease andAspergillus oryzae protease. It powerfully inhibited the caseinolytic activities of rabbit and horse pancreatic preparations and was least effective on human and pig pancreatic extracts. Modification of amino groups, guanido groups and sulphydryl groups of the inhibitor resulted in loss of inhibitory activity. Reduction of disulphide bridges, reduction with sodium borohydride and periodate oxidation also decreased the inhibitory activity.

    • Protein deficiency and age related alterations in rat peritoneal macrophage lipids

      J P Machaiah U K Vakil

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      The effects of dietary protein restriction and age on the thioglycollate elicited peritoneal macrophage lipid constituents were studied. Impact of subtle changes in lipid components on macrophage functions have been assessed. Lipid profiles of macrophages recovered from rats fed 20 and 4% protein diets and stock diet fed rats (0 and 3 wk) were comparable qualitatively. Quantitative analysis however revealed significant decrease in phospholipids (30–40%) and consequent elevation of cholesterol/phospholipid molar ratios in the protein depleted and young rats (0 wk), compared to the protein fed groups. The protein deficient and the young rats also exhibited accumulation of certain neutral lipids and reduction in triglycerides. Analysis of fatty acid methyl esters of macrophage phospholipids revealed the predominance of long chain polyunsaturated fatty acids even when oleic (C18:1) and linoleic (C18:2) formed the bulk of unsaturated fatty acids in the diet. However, the long chain poly unsaturated fatty acid content, particularly the docosahexaenoic acid (C22:6n-3) was greatly reduced in the protein depleted and 0 wk rats. Observed changes in the long chain polyunsaturated fatty acids of macrophage phospholipids may be of physiological significance as they modulate the immunological functions of the cell.

    • Effect of epinephrine on thein vitro biosynthesis of fibrinogen

      A K Roy R Bhadra A G Datta

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      In anin vitro rat liver slice incubation system, the synthesis of fibrinogen, when measured by immunoprecipitation technique was stimulated in the presence of epinephrine. An increase in poly (A)+ RNA content of the liver slice was also observed after epinephrine treatment. Thisin vitro experiment demonstrated that epinephrine stimulatedde novo synthesis of fibrinogen by acting directly on the liver.

    • Histochemical observations on the crown skin of male baya: Lipids, lipase and phosphomonoesterases

      A V R L Narasimhacharya V C Kotak

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      Histochemical studies on localisation of lipids, lipase and phosphomonoeste-rases in the crown skin of male baya during non-breeding and breeding seasons were carried out. The results indicated a high turnover rate for lipid synthesis and its utilisation, increased acid and alkaline phosphatase activities in the crown skin of breeding male baya as compared to that in non-breeding season. It is surmised that crown skin of male baya becomes metabolically hyperactive during breeding season aiding processes such as cell growth and proliferation, keratinization and production of coloured feathers related to breeding.

    • Effects of postnatal treatment with naloxone on plasma gonadotropin, prolactin, testosterone and testicular functions in male rats

      P Anandalaxmi E Vijayan

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      Opioid peptides are implicated in the control of gonadotropin and prolactin secretion. The role of opioid antagonist naloxone and its effects on plasma gonadotropin, prolactin, testosterone levels and testicular hyaluronidase, acid phosphatase, [3H]uridine and thymidine incorporation, RNA, DNA and protein concentrations were evaluated in rats after administration of naloxone beginning day 1 through 21 and autopsied on 45, 60 and 90 days of age. Plasma gonadotropin and testosterone levels were significantly elevated after naloxone treatment. Testicular hyaluronidase and acid phosphatase activity increased till 60 days post treatment and declined thereafter. Concentrations of RNA and protein did not change significantly but the concentration of DNA declined at 45 and 60 days of age. These results suggest that endogenous opioid peptides exert regulatory influence on gonadotropin secretion which in turn control the testicular function in the male rat.

    • Acknowledgements

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