摘要:

AbstractTotal and specific activity of cathepsin D (EC. 3.4.23.5) were measured in rat liver and brain from 1 to 98 days of age.The activity of cathepsin D in the liver of adult and newborn rats was the same while in the rat brain it was higher in adult than in newborn rats. In the liver maximum specific activity of cathepsin D occurred on the 10th postnatal day and minimum on the fourth day of age. In the brain maximum specific activity of the enzyme occurred on the 14th postnatal day. Total activity of cathepsin D increased after birth in rat liver and brain. These results are discussed in relation to the functional role of cathepsin D in the rat liver and the brain.

ISSN:0263-6484    

DOI:10.1002/cbf.290080303

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe lipid peroxidation product 4‐hydroxy‐2,3‐trans‐nonenal (HNE) has a spectrum of biological effects on different cell types depending on the concentrations tested. In particular micromolar HNE concentrations stimulate neutrophil migration and polarization whereas higher doses inhibit.In our experimental conditions, fMet‐Leu‐Phe (fMLP) increased CL production of both unstimulated and zymosan‐stimulated neutrophils, whereas cell stimulation with low HNE concentrations as well as zymosan addition to HNE incubated cells did not enhance light emission. In contrast 10−4M HNE reduced CL emission by unstimulated cells nearly to background values, completely depressed CL production by zymosan‐stimulated cells and reduced phagocytosis. Cysteine was found to be able to counteract the HNE effect by about 70 per cent. The possibility that this aldehyde could exert its inhibitory effect through the alkylation of NADPH‐oxidase SH‐groups is postulated. Moreover, our present data on differences observed between fMLP and HNE indicate a different chemotactic mechanism induced by these two classes of compounds and lead to the conclusion that the local functional features of the attracted c

ISSN:0263-6484    

DOI:10.1002/cbf.290080304

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractCirculating neutrophils isolated from patients 3–4 h after a myocardial infarction produced less\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm O}\frac{ \cdot }{{\rm 2}} $\end{document}compared with controls, when stimulated with phorbol myrystate acetate or formyl‐methionine‐leucine‐phenylalanine. Three days after the infraction the\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm O}\frac{ \cdot }{{\rm 2}} $\end{document}generation elicited by both stimuli further decreased markedly. Seven and 15 days after infarction the\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm O}\frac{ \cdot }{{\rm 2}} $\end{document}stimulated production was only slightly lower than or similar to the control values. The neutrophils of infarcted patients showed an augmented latency period before\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm O}\frac{ \cdot }{{\rm 2}} $\end{document}production compared with controls in response to exogenous stimuli, particularly three days after infarction. Electron microscopy revealed that the neutrophils isolated from the infarcted patients displayed signs of cell exhaustion with few alterations of the plasma membranes when stimulated with phorbol ester. In contrast, control neutrophils displayed alterations of the plasma membranes characteristic of active neutrophils. The results of this study indicate that the circulating neutrophils appear exhausted and functionally inhibited immediately after myocardial inf

ISSN:0263-6484    

DOI:10.1002/cbf.290080305

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractWe have previously demonstratedin vitrothat, in the endoplasmic reticulum and Golgi apparatus of mammary epithelial cells of lactating and pregnant mice, inositol 1,4,5‐trisphosphate releases Ca2+that has been stored in these organelles. In this study, we examined whether insulin and prolactin, essential for the growth of mammary gland and for lactation, influenced the activity of phosphatidylinositol‐specific phospholipase C in mammary cells. In the plasma membrane fraction of mammary epithelial cells of the DDY mouse strain 5 days after the start of lactation after the first pregnancy, and with phosphatidylinostol as substrate, it was shown that the activity of phospholipase C was enhanced by about four times in the presence of insulin compared with the control. Such enhancement was not found in the membrane fraction treated with prolac

ISSN:0263-6484    

DOI:10.1002/cbf.290080306

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractHuman fibroblasts from a patient homozygous for hexokinase (HK) deficiency and normal controls were submitted to different nutrient shifts to investigate the role of glucose metabolism on ATP levels. HK‐deficient cells maintained in the presence of both glucose andL‐glutamine had 20 per cent less ATP than controls and an ATP/ADP ratio of 18 instead of 37–40. Glucose alone was not able to maintain normal ATP levels neither in the controls nor in the HK‐deficient cells. However while in control cells the ATP/ADP ratio was not modified, it was reduced to 10 in HK deficiency. The effect of several hexoses on ATP levels was also investigated. Mannose, which is metabolized by HK phosphorylation, was the least efficient for ATP maintenance in HK‐deficient cells. In contrast galactose, which is metabolized by a specific galactokinase, provided ATP values close to those observed in the presence of glutamine. These results suggest that glucose metabolism is an important determinant in the maintenance of ATP levels in cultured cells and that glutamine, although being a good metabolic substrate, is not sufficient to maintain normal ATP conce

ISSN:0263-6484    

DOI:10.1002/cbf.290080307

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractExtracellular sodium is known to influence secretion by certain secretory cells, possibly by mobilizing calcium from cellular stores or by altering intracellular pH via regulation of a Na+‐H+antiport system. Using canine tracheal explants, we determined whether agents which alter sodium fluxes are capable of modulating basal or cholinergically‐induced secretion of mucus glycoconjugates. Methacholine, a cholinergic agonist, increased mucus secretion from explants incubated in the presence or absence of calcium, but had no effect on secretion when incubated in sodium‐deficient media, indicating (a) that cholinergically‐induced secretion can be mediated by mobilization of cellular calcium and (b) that extracellular sodium was required for this stimulatory effect. Several agents which increase intracellular sodium were tested for their effect on mucus secretion. Ouabain, a sodium pump inhibitor, and veratridine, a sodium channel activator, did not significantly affect control or methacholine‐induced secretion; gramicidin, a sodium ionophore, also had no effect on basal release. Tetrodotoxin, a sodium channel inhibitor, was also without effect on basal or methacholine‐stimulated mucus release. Agents which alter intracellular pH were also examined for their effects on basal or methacholine‐induced glycoconjugate secretion. Amiloride, which decreases intracellular pH by inhibiting Na+‐H+exchange, produced a 19 per cent increase in basal secretion (not statistically significant), but had no effect on methacholine‐induced secretion. An agent, 4,4′‐diisothiocyanostilbene‐2,2′‐disulfonic acid (DIDS), which decreases intracellular pH by inhibiting HCO3−−Cl−exchange, elicited decreases in both basal and methacholine‐induced secretion, but the inhibition did not reach statistical significance. Thus extracellular sodium is required for cholinergically‐induced glycoconjugate secretion from canine tracheal explants and the underlying mechanism does not involve sodium influx into the cell, but may possibly be mediat

ISSN:0263-6484    

DOI:10.1002/cbf.290080308

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe intracellular acid‐soluble purine and pyrimidine derivatives of myxamoebae‐swarm cells ofPhysarum flavicomumwere investigated during growth, microcyst formation, and during adenine‐inhibiton of encystment, using high performance liquid chromatography (HPLC). We also studied the incorporation of exogenous radioactive adenine into the acid soluble purine derivatives and S‐adenosyl‐sulphur compounds separated by HPLC. The most abundant ribonucleoside monophosphate was AMP in the growing and 15 h encysting cells (NC), while it was UMP in the 15 h adenine‐inhibited cells (AIC). ADP was the nucleoside diphosphate present in the greatest quantity in the growing and NC cells but it was CDP in the AIC. The nucleoside triphosphate in highest concentration was ATP, UTP, and GTP in growing, NC, and AIC, respectively. Guanosine was the most abundant nucleoside in all cells. The nucleobase occurring in greatest concentration was cytosine, cytosine and guanine, and adenine in the growing, NC, and AIC, respectively. The AMP content in the 15 h AIC was 2·1‐fold higher than that of adenosine. The 15 h NC had the lowest adenylate energy charge, a value of 0·54 ± 0·02, while the values for growing cells and the AIC were 0·62 ± 0.02 and 0·76 ± 0.01, respectively. [14C]‐Adenine labelling studies (15 h) revealed the occurrence of purine nucleotide interconversion, as the label was detected not only in adenosine, AMP, ADP, ATP, but also in guanine, guanosine, GMP, GDP, GTP, as well as, in inosine monophosphate and xanthosine monophosphate. The percentage incorporation of the radiolabelled adenine into AMP was higher than into adenosine. An increased intracellular level of guanine nucleotides is associated with the inhibition of encystment. The extracellular adenine, rather than internal adenine sources, appears to be the primary precursor of nucleotide for S‐adenosylmethionine synthesis during adenine

ISSN:0263-6484    

DOI:10.1002/cbf.290080309

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

ISSN:0263-6484    

DOI:10.1002/cbf.290080312

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

ISSN:0263-6484    

DOI:10.1002/cbf.290080313

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

ISSN:0263-6484    

DOI:10.1002/cbf.290080302

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY