摘要:

AbstractA golgi‐enriched subfraction was obtained from porcine throid glands by differential centrifugation. When incubated in a suitable medium, these vesicles were able to concentrate iodide from the medium and bind it to protein. The iodination process was inhibited by methylmercapto‐imidazole and was increased by the addition of an H2O2generating system to the medium. Analysis of the protein content of the vesicles revealed the presence of 18 and 12–13 S thyroglobulin molecules, lacking mannose residues, and containing only monoiodotyrosine.It is concluded thatin vitro, iodination can begin before exocytosis, in the smooth‐surfaced vesicles derived from the golgi apparatus, as soon asN‐acetylglucosamine is incorporated onto the pre‐thyroglobul

ISSN:0263-6484    

DOI:10.1002/cbf.290060302

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe basolateral membrane of the jejunal enterocyte of the rat was separated by self‐orienting Percoll‐gradient centrifugation and further purified from brush border contamination. Pellets were analysed for Mg‐, Na‐ and (Na, K)‐ATPase activities. The uptake of 0·02MNaCl was also followed by the rapid micro‐filtration technique. Transintestinal transport of fluid and electrolytes, and cell water, Na and K were determined in thein vitroeverted and incubated jejunum.There is ouabain‐insensitive Na‐ATPase in addition to the well‐known (Na, K)‐ATPase in the basolateral membrane. These are differently inhibited by furosemide and ethacrynate. Na uptake by osmotically active basolateral membrane vesicles is enhanced by ATP and a further enhancement is obtained if there is intravesicular K. The ATP effect is inhibited differently by strophanthidin, furosemide and ethacrynate. In the everted sac preparation, transintestinal transport of Na and fluid still occurs when the Na/K pump is totally inhibited by ouabain.These experimental results suggest that there is also a ouabain‐insensitive Na pump, different from the Na/K pump, in th

ISSN:0263-6484    

DOI:10.1002/cbf.290060303

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractNuclei isolated from rat liver, incubated in the presence of liposomes of different phospholipids, undergo typical modifications: chromatin dispersion and reduction of the interchromatin granules in nuclei incubated with negatively charged liposomes and increase of the chromatin density and of the number and size of the interchromatin granules in nuclei incubated with neutral liposomes. The possibility that the observed modifications are caused by an impairment of the transport and translocation of ribonucleoproteins belonging to the inner nuclear matrix, is suggested by the results obtained by radiotracer techniques on the release of RNA from liposome‐incubated nucle

ISSN:0263-6484    

DOI:10.1002/cbf.290060304

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractIn addition to the well known effect of phenylhydrazine on red blood cells (methaemoglobin and Heinz body formation, autologous IgG binding, lipid peroxidation, etc.) an increased glucose utilization was observed. Measurement of14CO2formation from [1‐14C]‐glucose showed a maximum value at 2 mMphenylhydrazine followed by a progressive inhibition on increasing the drug concentration to 16 mM. Concomitantly we found a reduction in the reduced glutathione concentration but not a corresponding increase in the level of oxidized glutathione. Phenylhydrazine also causes ATP depletion. The ATP is in part dephosphorylated to ADP and AMP and in part converted to inosine monophosphate and hypoxanthine. Measurement of the cell content of reduced and oxidized pyridine nucleotides was also performed and showed a progressive increase in the reduced forms of these coenzymes. Thus phenylhydrazine promotes cellular ATP depletion followed by adenine nucleotide catabolism that is not efficiently counteracted by an increase in glucose utilization. The relevance of these data to the mechanism of phenylhydrazine‐induced anemia is disc

ISSN:0263-6484    

DOI:10.1002/cbf.290060305

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe interactions of octaethyleneglycol alkylethers (C10–C16), pentaethyleneglycol dodecylether, and dodecyl D‐maltoside with the human erythrocyte membrane were studied. All the amphiphiles protected erythrocytes against hypotonic haemolysis. At concentrations where the amphipiles protected erythrocytes against hypotonic haemolysis they reduced phosphate efflux. The potency of the amphiphiles, at equiprotecting concentrations, was correlated negatively to the length of the alkyl chain. Pottasium fluxes were increased by all the amphiphiles at protective concentrations. The relative potency of the amphiphiles varied but it was not simply related to the length of the alkyl chain. The only amphiphile affecting active potassium influx was octaethyleneglycol decylether which induced a slight decrease. It is concluded that the increase in passive cation fluxes caused by the amphiphiles is due to an increased permeability of the lipid bilayer induced through a nonspecific interaction of the amphiphiles with the bilayer. The effect of the amphiphiles on ion transport mediated by membrane proteins is proposed to be due to an alteration of the state of the transporting prot

ISSN:0263-6484    

DOI:10.1002/cbf.290060306

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractLuminol‐dependent chemiluminescence of normal human monocytes activated by zymosan is demonstrated to be inhibited by tetrahydrobiopterin in a concentration‐dependent manner. The reduced pterins tetrahydrobiopterin, dihydrobiopterin, and dihydroneopterin are all shown to be readily oxidized by the hydroxyl radical.The susceptibility of reduced pterins to free radical attack may explain the inhibition of chemiluminescence observed and an additional role of reduced pterins as free radical scavengers in tissues is conside

ISSN:0263-6484    

DOI:10.1002/cbf.290060307

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe activity and hormonal regulation of NAD‐ and NADP‐linked isocitrate dehydrogenase (EC.1.1.1.41 and EC.1.1.1.42, respectively) in the brain, liver and kidney cortex of female rats of various ages was investigated. The activity of NAD‐ICDH of brain was greater than extramitochondrial (‐c) or intramitochondrial (‐m) NADP‐ICDH. In contrast, liver c‐NADP‐ICDH was much higher than NAD‐ or m‐NADP‐ICDH, whereas in kidney cortex the activity of m‐NADP‐ICDH is dominant over both NAD‐ and c‐NADP‐ICDH in all the age group of rats studied. The activity of the NAD‐ICDH of brain and all the enzymes of liver and kidney cortex increases until adulthood (33‐weeks) and decreases thereafter in old rats (85‐weeks). In brain c‐NADP‐ICDH was much higher in immature (6‐weeks) rats and decreases with increasing age of the animal, whereas m‐NADP‐ICDH showed no significant change with the age of the rats. Bilateral ovariectomy decreases the level of all the three forms of enzyme in all the tissues of 6‐, 13‐ and 33‐week rats but failed to show any significant effect in 85‐week old rats. Exogenous administration of estradiol induces all the three forms of enzyme in all the tissues of ovariectomized r

ISSN:0263-6484    

DOI:10.1002/cbf.290060308

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractAs has been previously reported one surge in cytosolic calmodulin is produced between 4 and 12 h after a partial hepatectomy. Moreoever, a surge in cytosolic cyclic AMP and another in cyclic AMP‐dependent protein kinase activity can be detected during the late period of the prereplicative phase of liver regeneration after a partial hepatectomy. It is known that these three surges are involved in triggering DNA synthesis.By kinetic studies and by injecting transcription (actinomycin D) and translation (cycloheximide) inhibitors into hepatectomized rats we have demonstrated that the cyclic AMP‐dependent protein kinase surge is produced by new synthesis of the enzyme. In thyroparathyroidectomized rats subjected to a partial hepatectomy the calmodulin surge was similar to that observed in normal hepatectomized rats whereas the surge in cyclic AMP‐dependent protein kinase activity was strongly decreased suggesting that the cyclic AMP‐dependent protein kinase surge is not generated by the previous surge in cal

ISSN:0263-6484    

DOI:10.1002/cbf.290060309

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractCultured capillary endothelial cells, derived from bovine brain, and maintained on a plastic substratum synthesized predominantly interstitial collagens of which approximately 75 per cent were secreted into the medium. When grown on a native hydrated collagen type I gel, although no marked alteration in the ‘collagen synthetic pattern’ was observed, the overall level of collagen synthesis was increased by approximately 100 per cent. More dramatic, however, was the alteration in the distribution of these molecules between medium and cell layer. Interstitial collagens produced by cells grown on collagen gels were almost exclusively associated with the cell layer or collagenous gel. These studies, thus, demonstrate that an extracellular matrix may exert a considerable influence on the cellular synthetic activities and possibly cellular polarity of capillary endothelial ce

ISSN:0263-6484    

DOI:10.1002/cbf.290060310

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

ISSN:0263-6484    

DOI:10.1002/cbf.290060312

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY