摘要:

AbstractA high molecular weight glycoprotein (450 000) was obtained from thrombin‐treated duck thrombocytes by barium citrate adsorption technique followed by heparin‐agarose affinity chromatography. Amino acid composition (high number of acidic amino acids and cystine) as well as carbohydrate contents (1·3 per cent hexosamine, 0·9 per cent sialic acid and 1·5 per cent hexose) showed similarity to mammalian platelet thrombos

ISSN:0263-6484    

DOI:10.1002/cbf.290060102

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe study of the influence of the age of the animals (13 to 53 weeks) on the rate of ethanol metabolismin vivoand the total activity of liver alcohol dehydrogenase and microsomal ethanol oxidizing system showed a progressive decline with age. These effects were observed concomitantly with a diminution in the content of cytochrome P‐450 and microsomal functions related to oxidative and free‐radical mediated reactions, namely, NADPH oxidase activity, NADPH‐dependent oxygen uptake and NADPH‐ort‐butyl hydroperoxide‐induced chemiluminescence. It is concluded that ageing is accompanied by a diminution in the total oxidative activity of the liver tissue, which would explain the depression in basal and ethanol‐induced lipid peroxidation found in the oldest group of

ISSN:0263-6484    

DOI:10.1002/cbf.290060103

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractTriggered polymorphonuclear leucocytes (PMNL) can decrease the elastase inhibitory capacity of serum by inactivating the main inhibitor of elastase alpha‐1‐proteinase inhibitor (alpha‐1‐PI). Maximal inactivation occurs with stimuli that release myeloperoxidase from PMNL along with hydrogen peroxide. Specific protection of alpha‐1‐PI function is obtained with antioxidants that interfere with this system. PMNL that are activated with phorbol myristate acetate release hydrogen peroxide but not myeloperoxidase, and only inactivate alpha‐1‐PI in the presence of exogenously‐added PMNL‐derived supernatants which contain this enzyme. Cell‐free inactivation requires both active enzyme and hydrogen peroxide, and is greatest at pH 6·2, the pH optimum for myeloperoxidase‐catalysed inactivation of alpha‐1‐PI. This data supports the notion that leucocyte myeloperoxidase may act to suppress the antiprotease screen afforded by alpha‐1‐PI by generating hypochlorous acid in the presence of chloride and respiratory burst‐derived hydrogen peroxide, and in the microenvironment of lowered pH associated with degranulation. Pulmonary emphysema seems to be associated with an imbalance between elastase and its inhibitors at the lung surface. PMNL are likely to play an important role in the pathogenesis of emphysema since they contain both elastase, which can solubilize connective tissue elastin, and the constituents of an oxidative system which can inactive the most

ISSN:0263-6484    

DOI:10.1002/cbf.290060104

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractHuman urinary bladder carcinoma cells (JTC‐32) retain a low alkaline phosphatase activity. Prednisolone or a hypertonic concentration of NaCl caused a moderate increase in the activity (10‐ to 15‐fold of control), but dibutyryl cAMP or butyrate did not. Examination of the combined effect of these four agents revealed that they acted synergistically in any combination. When the cells were incubated with the four agents together, the enzyme activity increased 60‐ to 250‐fold. Serum also contributed to this synergistic increase. These agents slightly inhibited cell growth and protein synthesis. The enzyme induction was completely inhibited by cycloheximide or actinomycin D. The synergistic effect of the four agents on the enzyme activity was also observed in other strains of carcinoma cells, human urinary bladder carcinoma cells (JTC‐30) and monkey hepatocarcinoma cells (NCLP‐6E). Thus, it is concluded that the coexistence of the four agents provides general and superior conditions for the induction of alkaline phosphatase in cultured ca

ISSN:0263-6484    

DOI:10.1002/cbf.290060105

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractFlow cytometric perpendicular and forward light scatters have been employed to evaluate whether the changes in chromatin organization due to ionic strength, Mg++concentration and pH, visible in electron microscopy, can be monitored by flow cytometry.The average intensity of the perpendicular light scatter signal increased as nuclear chromatin became decondensed by lowering the ionic strength or releasing H1 histone at low pH values.These results indicate that flow cytometry signals and in particular the perpendicular light scatter allow the detection of the conformational transitions in chromatin and may therefore be useful for studying cell cycle associated morphological changes in isolated nuclei.

ISSN:0263-6484    

DOI:10.1002/cbf.290060106

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractBy differential sucrose gradient centrifugation of pig kidney chromatin in the presence or absence of Na‐EDTA and under varying ionic strength conditions, three nucleosome‐like subpopulations with different buoyant densities can be obtained. These particles, on the basis of their histones and HMG protein pattern, of the 5‐methylcytosine level of their DNA and of the RNA polymerase activity associated with them, can be considered as originating from chromatin fractions differently involved in gene expression.Two‐dimensional electrophoresis of the tightly‐bound non‐histone proteins shows a distinct pattern for each subpopulation, such protein components being notably present in restricted numbers but in high amounts in the subpopulation which was apparently derived from condensed hete

ISSN:0263-6484    

DOI:10.1002/cbf.290060107

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe i.p. administration of 60 mg kg−1body weight of lindane, the γ‐isomer of hexachlorocyclohexane, to fed rats led to an enhancement of hepatic lipid peroxidation after 24 h of treatment. This was evidenced by significant increases in the hepatic production and biliary release of thiobarbituric acid reactive substances, and in the biliary release of glutathione disulphide. Under these conditions, the content of cytochrome P450 was enhanced concomitantly with increases in the total microsomal oxygen uptake, superoxide radical generation and (+)‐catechin (cyanid‐3‐ol) sensitive respiration. The glutathione status of hepatocytes was altered by lindane as the content and biliary release of glutathione disulphide was drastically augmented, leading to a decrease in the cellular and biliary GSH/GSSG ratios. It is suggested that lindane treatment leads to an induced oxidative capacity, which, in turn, alters the glutathione status of the li

ISSN:0263-6484    

DOI:10.1002/cbf.290060108

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractAlkaline phosphatase and 5′‐nucleotidase activities were analysed cytophotometrically in cryostat sections of female rat liver after partial hepatectomy. Alkaline phosphatase activity increased rapidly after operation up to a maximum seven‐fold rise at 24 h in comparison with sham operated or control rats. There was no indication of preferential localization of alkaline phosphatase activity in either periportal or pericentral areas at any time point in control rats, sham operated rats or hepatectomized rats. Microscopical observation revealed that (a) all alkaline phosphatase activity was present at the bile canalicular surface of hepatocytes and (b) hepatocytes in mitosis did not show any increase in activity. These findings indicate that the high alkaline phosphatase activity after partial hepatectomy is not involved primarily in proliferation processes because cell division mainly takes place periportally. It may be needed for enhanced bile secretion by conversion of intracellular phosphorylcholine into choline which can be transported into the bile. The intracellular phosphorylcholine level is high after operation due to changes in phospholipid metabolism. 5′‐Nucleotidase appeared to be three times higher pericentrally than periportally under normal conditions. Partial hepatectomy caused a 40 per cent decrease in activity in pericentral areas and only a small decrease periportally. It has been suggested that 5′‐nucleotidase plays a role in breakdown of messenger RNA and its activity in control liver could be considerably lower periportally because plasma protein synthesis mainly takes place in this area. 5′‐Nucleotidase activity may well be decreased after operation for accumulation of messenger RNA for enhanced plasma protein synthesis in order to compensate for 67 per cent of the liver cell functions lost during pa

ISSN:0263-6484    

DOI:10.1002/cbf.290060109

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractEffect of methotrexate (MTX) on mitochondrial oxygen uptake, oxidative phosphorylation and on the activity of several enzymes linked to respiratory chain was studied. MTX was able to inhibit state III respiration activated by ADP and to decrease the respiratory coefficient with the substrates α‐ketoglutarate and glutamate; these effects became pronounced when mitochondria were pre‐incubated with MTX for 10 min. No effect was observed on ATPase activity of undamaged or broken mitochondria; the same was true for NADH‐oxidase, NADH‐dehydrogenase, NADH‐cytochrome c reductase, succinate oxidase, and cytochrome c oxidase activity. The effect on the steady‐state of cytochrome b, as well as, the inhibitory effect on state III of respiration with NAD+‐linked substrates, offers a reasonable possibility to suggesting that the inhibition site of MTX could be in a place anterior to cytochrome b region, and not linked to res

ISSN:0263-6484    

DOI:10.1002/cbf.290060110

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

ISSN:0263-6484    

DOI:10.1002/cbf.290060113

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY