ISSN:0263-6484    

DOI:10.1002/cbf.290030102

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

摘要:

AbstractSome aldehydes, produced during lipid peroxidation of liver lipids, are able to inhibit the respiration of mitochondria and of intact cells both in normal hepatocytes and in Yoshida hepatoma. In mitochondria, the respiratory stimulation produced by addition of ADP and dinitrophenol is decreased more in hepatoma than in normal liver. Two‐ to four‐fold higher concentrations of aldehydes are needed to obtain the same degree of inhibition in normal liver mitochondria as in tumorous organs. The effect of aldehydes on intact cell respiration is absent or very low in hepatocytes, but it is consistently observed in hepatoma ce

ISSN:0263-6484    

DOI:10.1002/cbf.290030103

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

摘要:

AbstractMethylglyoxal inhibits cell division, exerting an antiproliferative action on tumour cells. Supernatants from ascites hepatoma cell homogenate, previously incubated with the aldehyde, showed a decrease in colchicine binding activity dependent on methylglyoxal concentration. In contrast,in vivotreatment of tumour‐bearing rats apparently did not cause a significant impairment of microtubular protein, suggesting that the aldehyde interaction with microtubules cannot be considered responsible for its carcinostatic actio

ISSN:0263-6484    

DOI:10.1002/cbf.290030104

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe binding and uptake of insulin in perfused rat liver has been investigated with specifically labelled125I‐A14‐tyrosyl insulin as a tracer and compared with a commercially available iodo‐insulin preparation. The commercial preparation did not show saturation uptake kinetics and the clearence from the perfusate remained low and constant throughtout a wide concentration range. A14 labelled insulin showed saturation kinetics and high clearence at low carrier concentration, falling rapidly with increasing carrier concentration and reaching a steady state value of 1 ml/min. These results emphasize the importance of using specifically labelled insulin in physiological and biochemical studies of hepatic insulin metabolism.Perfusion with A14 tyrosine‐labelled insulin at 4°C showed apparent saturation with binding to the plasma membrane fraction. Perfusion at 37°C also showed apparent saturation with uptake predominantly to the ligandosome fraction. These results implicate the plasma membrane‐ligandosome pathway in the hepatic uptake of insulin at both physiological and pharmacological concentrations of

ISSN:0263-6484    

DOI:10.1002/cbf.290030105

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

摘要:

AbstractPig thyroid Golgi vesicles incubated in a suitable medium were able to concentrate iodide from the medium. This trapping required the integrity of the vesicles, was time‐ and temperature‐dependent, and was inhibited by a competitive inhibitor of iodide active transport (perchlorate), suggesting a facilitated transport mechan

ISSN:0263-6484    

DOI:10.1002/cbf.290030106

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

摘要:

AbstractIn rat pancreatic islet membranes exposed to [α–32P]NAD, cholera toxin stimulated the labelling of three peptides with Mr close to 22000, 42000 and 48000, respectively. In the islets, the toxin‐stimulated ADP‐ribosylation of the heavy form of the Ns α‐subunit predominated over that of the light from, in mirror image of the situation found in the exocrine pancreas. When intact islets were preincubated with cholera toxin, the adenylate cyclase activity of a subcellular particulate fraction was increased. The responsiveness of adenylate cyclase to GTP was also augmented, but that to NaF was decreased. In intact islets, the production of cyclic AMP and the glucose‐stimulated release of insulin were also enhanced after pretreatment with cholera toxin. These findings reveal the presence in pancreatic islets of the guanyl nucleotide regulatory protein of adenylate cyclase, with an unusual predominance of the heavy from of the N

ISSN:0263-6484    

DOI:10.1002/cbf.290030107

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

摘要:

AbstractIn the early stage of mammary gland involution, biochemically detectable lysosomal damage occurs. The mechanism(s) underlying this damage is not well understood. We found that α‐lactalbumin from mouse milk induced the release of enzymes from the lysosomes of mouse mammary epithelial cellsin vitro, and this induction also occurred with bovine α‐lactalbumin. This enzyme release was accelerated by the addition of whey proteins with a molecular weight of 50 000 to 60 000. We also found that the lysosomal membrane of mammary epithelial cells had a strong affinity for α‐lac

ISSN:0263-6484    

DOI:10.1002/cbf.290030108

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

摘要:

AbstractWe previously reported that α‐lactalbumin combines with the lysosomal membrane of mammary epithelial cells and that it acts to release lysosomal enzymes. However, the details of this combination within the cells remained undetermined. We now report that125I‐bovine‐α‐lactalbumin in the medium entered mouse mammary epithelial cells, and about 13 per cent of the α‐lactalbumin that entered the cell bound to lysosomes. About 75 per cent of the α‐lactalbumin that reached the lysosome was tightly bound to the lysosomal membrane. It appears that α‐lactalbumin in the secretory vesicles does not migrate out, because murine and bovine whey did not induce the release of Gol

ISSN:0263-6484    

DOI:10.1002/cbf.290030109

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

摘要:

AbstractExplants of pig kidney cortex and medulla release a catabolin‐like factor (CLF). The CLF of both kidney cortex and medulla can be precipitated with ammonium sulphate, mainly in the 60–95 per cent fraction. By gel chromatography the kidney CLF showed a major active fraction at a molecular weight of around 22 500.Whole glomeruli and dissociated glomerular cells in culture also released into the medium a CLF that could be bioassayed in live cartilage but displayed no effect on dead cartilage. The possible role of such a local hormone is discus

ISSN:0263-6484    

DOI:10.1002/cbf.290030110

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe specificity of Kirkman‐Robbins hepatoma and hamster liver non‐histone chromatin proteins has been studied by comparing polypeptide patterns in polyacrylamide gel electrophoresis and by their immunological activity in the complement fixation test. Non‐histone proteins were separated from DNA with a polyethylene glycol‐dextran mixture and fractionated by hydroxylapatite chromatography into three classes named NHCP1, NHCP2, and NHCP3. Electrophoretic analysis indicated that among the non‐histone proteins of Kirkman‐Robbins hepatoma and hamster liver differences mainly of a quantitative nature can be observed. However, the polypeptides with molecular weight 25 000, 31 000, 36 000, 73 000 in NHCP1; 20 000, 40 000 in NHCP2 and 20 000, 32 000, 38 000, 44 000, 75 000, 80 000 in NHCP3 were found to be specific for hepatoma chromatin. Application of antibodies against NHCP1, NHCP2 and dehistonized chromatin of Kirkman‐Robbins hepatoma revealed that the highest specificity of NHCP2 eluted from hydroxylapatite with 100 mMphosphate buffer at pH 6·8. The NHCP1 of hepatoma shares some common antigenic determinants with analogous proteins of liver. On the other hand non‐histone proteins specific for heptoma dehistonized chromatin can be localized in the NHCP3 and partially in the

ISSN:0263-6484    

DOI:10.1002/cbf.290030111

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY