bluuebunny/crossref_metadata_2025_split huggingface dataset:
Metabolic effects of acetaminophen. Studies in the isolated perfused rat liver
Authors: Itinose Ana Maria , Sakuno Marlene Leiko Doi , Bracht Adelar 
Published: May 2005

AbstractThe effects of acetaminophen on the metabolism of the isolated perfused rat liver were investigated. The following results were obtained:

Acetaminophen increased glucose release and glycolysis from endogenous glycogen (glycogenolysis).
Oxygen uptake, gluconeogenesis from either pyruvate or fructose and glycogen synthesis were inhibited.
In isolated rat liver mitochondria acetaminophen decreased state III and state IV respiration; it also decreased the ADP/O ratio and the respiratory control ratio.
The action of acetaminophen on glycogenolysis was not affected by N‐acetylcysteine; this compound, however, increased glycogen synthesis.
The effects of acetaminophen are reversible.
It was concluded that glycogen depletion by acetaminophen can be produced by two mechanisms. The first, as previously demonstrated by several workers, depends on irreversible binding of a reactive metabolite. The second, however, is reversible and depends primarily on an inhibition of mitochondrial energy metabolism.
Cytochrome P450 in highly purified suspension of nonparenchymal liver cells
Authors: Rich K. , Lodola A. 
Published: May 2005

AbstractRat liver nonparenchymal cells (NPC) were prepared by pronase digestion and purified on discontinuous gradients on Nycodenz. Morphological and biochemical characterization of cell suspensions showed that they were free of contamination by hepatocytes. We have confirmed the usefulness of pyruvate kinase activity in monitoring the degree of hepatocyte contamination of NPC and we have derived an equation which allows this carry‐over to be calculated. Using highly purified suspensions of NPC we have shown that they contain glucose‐6‐phosphatase in low but detectable levels. Spectrophotometric studies showed that they contain cytochrome P450, with a specific content of 24 +/− 5 pmole mg−1 cell protein. A potential source of error in previous studies was recognized; namely that peroxidase, present in NPC in high concentration, is able to mask the absorption due to cytochrome P450. Both the presence and inducibility of this enzyme in NPC prepared from rats pretreated with phenobarbital or 3‐methylcholanthrene have been confirmed using Western blot analysis.
Synthesis of proteoglycans and hyaluronic acid by long‐term cultures of testicular cells from immature and pubertal rats
Authors: Rodríguez J. Pablo , Minguell José J. 
Published: May 2005

AbstractLong‐term cultures of somatic testicular cells derived from immature and pubertal rats were used to study the synthesis of proteoglycans (PG) and hyaluronic acid (HA). Labelled PG and HA in the culture medium, membrane‐associated and intracellular pools were characterized by gel fitration, ion exchange chromatography and selected enzymatic and chemical treatments. Somatic cells synthesize a PG containing both heparan and chondroitin/dermatan sulfate (CS/DS) chains and a PG containing only CS/DS chains. No major qualitative changes in the type of PG were observed in cells derived from immature and pubertal animals. However, significant age‐dependent differences in the cell distribution pattern of PG and HA were determined. This may have implications in the regulation of spermatogenesis.
Evidence for a differential distribution of reducing equivalents from NADPH in cartilage
Authors: Nahir A. M. , Boussidan F. , Shomart D. 
Published: May 2005

AbstractIt has been suggested that the NADPH, generated from the activity of glucose 6‐phosphate dehydrogenase, may be utilized by two different routes, namely either for biosynthetic purposes (type 2) or for microsomal respiration (type 1). This concept has been tested in the rabbit ear model in which an injection of papain into the rabbit causes loss of proteoglycans of the auricular matrix followed by its restoration over the following eight days. It is shown that whereas the type 1 pathway was either unaltered or diminished, the doubling of the glucose 6‐phosphate dehydrogenase activity was related solely to the type 2 pathway.
Identification of a nuclear antigen with molecular weight of 48 000 differentially expressed in tumour and normal cells
Authors: Krajewska Wanda M. , Lipińska Anna , Marszałek Małgorzata , Kiliańska Zofia , Wojtkowiak Zbigniew , Kłyszejko‐Stefanowicz Leokadia 
Published: May 2005

AbstractA non‐histone protein with mol. wt of 48 000 differentially expressed in normal and tumour cells was identified using immunological criteria. Antibodies were raised against a component specific for Kirkman‐Robbins hepatoma of mol. wt about 48 000 separated from hepatoma non‐histone proteins by preparative electrophoresis in polyacrylamide gel. It was demonstrated by immunoblotting that Morris hepatoma 7777 and Ehrlich ascites cells share an antigenic non‐histone protein with Kirman‐Robbins hepatoma. Tumour cells when compared with normal cells, i.e. hamster and rat liver, are characterized by significant enrichment of this component. Intracellular distribution of the polypeptide with mol. wt 48 000 suggests that this component may be a structural protein the biosynthesis of which increases or the antigenic determinants of which change in tumour cells.
Influence of 4‐hydroxynonenal on chemiluminescence production by unstimulated and opsonized zymosan‐stimulated human neutrophils
Authors: Di Mauro C. , Cavalli G. , Amprimo M. C. , Paradisi L. , Scano G. , Curzio M. , Dianzani M. U. 
Published: May 2005

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 10−4 M 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 cells may be different.
Reduced oxidative activity of circulating neutrophils in patients after myocardial infarction
Authors: Guarnieri Carlo , Melandri Giovanni , Caldarera Ilaria , Scheda Mauro , Ligabue Amedeo , Guizzardi Sandro , Branzi Angelo 
Published: May 2005

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 infarction.
Extracellular sodium is required for methacholine‐induced secretion of mucus glycoconjugates from canine tracheal explants
Authors: Barsigian Carl , Barbieri Edward J. 
Published: May 2005

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 mediated by alterations in intracellular pH.
Effects of vanadate on 6‐phosphofructo 2‐kinase activity and fructose 2,6‐bisphosphate levels in cultured rat hepatocytes
Authors: Miralpeix Montserrat , Katz Norbert R. , Bartrons Ramon 
Published: May 2005

AbstractThe presence of vanadate in primary cultures of rat hepatocytes produced a significant increase in the concentration of fructose 2,6‐bisphosphate and in the activity of 6‐phosphofructo 2‐kinase. Compared with insulin, vanadate had a more potent action on the metabolite increase, but a similar effect on the 6‐phosphofructo 2‐kinase activity. Both the insulin‐ and the vanadate‐dependent enhancements of 6‐phosphofructo 2‐kinase were inhibited by cycloheximide which specificially blocks protein synthesis on the translational level, suggesting that the increase of the enzyme activity was due to induction rather than to a change in the catalytic activity.
Efflux of inorganic phosphate from rat hepatocytes: Lack of effect of insulin
Authors: Parkash Mukesh , Butterworth Peter J. 
Published: May 2005

AbstractEfflux of Pi from rat hepatocytes suspended in phosphate free‐medium was studied by chemical assay of released Pi and by monitoring the loss in radioactivity of cells pre‐labelled with [32P]‐Pi. The release follows first‐order kinetics fairly closely with a rate constant of 7 × 10−3min−1 approximately. Insulin at a concentration of 10−8M had no effect on the rate of Pi release and it is concluded therefore, that the insulin‐stimulated accumulation of Pi described in the literature is the result of hormone action on Pi uptake by liver rather than on its release.
Mitoxantrone toxicity on ehrlich ascites tumour cells: Inhibition of the transplasma membrane redox activity
Authors: Medina Miguel Angel , Luque Pilar , De Castro Ignacio NÚñez 
Published: May 2005

AbstractThis study focused on the potent cytotoxic effect that mitoxantrone produces on Ehrlich ascites tumour cells. Host mice treated with mitoxantrone showed a life span three times higher than control non‐treated host mice. Mitoxantrone also showed a potent cytotoxic effect on Ehrlich cells incubated in vitro for only a few hours. Studies on the effect of mitoxantrone on a plasma membrane redox system showed that mitoxantrone inhibits this activity, which is apparently related to cell proliferation.
Inositol lipids in friend erythroleukemia cells: Evidence for changes in nuclear metabolism after differntiation
Authors: Capitani S. , Billi A. M. , Bertagnolo V. , Previati M. , Mazzoni M. , Neri L. M. , Manzoli F. A. 
Published: May 2005

AbstractThe incorporation of 32Pi into phospholipids was studied in Friend erythroleukemia cells either induced or not to erythroid differentiation with 4 mM hexamethylenebisacetamide (HMBA). The effect of the differentiating agent on the recovery of radiolabelled phospholipids was compared in whole cells, isolated nuclei and nuclear matrix after in vivo labelling for 1 hr. The procedure employed for the isolation of nuclei was demonstrated to allow only negligible lipid redistribution caused by cell manipulations. Among the lipids extractable from nuclei, acidic phospholipids, and particularly polyphosphoinositides, were more represented than in whole cells, while small differences were found in the other phospholipid classes examined. The comparison between the uninduced and induced condition showed that the relative amounts of nuclear inositol lipids were modified by HMBA treatment of the cells, with a decreased recovery of phosphatidylinositol 4,5 bisphosphate.These results indicate that phosphatidylinositol and its phosphorylation products synthesized in vivo show a different metabolism in nuclei and whole cells. They appear to be tightly bound nuclear components, also present in membrane‐deprived nuclei and nuclear matrix, and are probably related to the nuclear events involved in erythroid differentiation.
Effects of rGM‐CSF on leukemia cell proliferation and on the incorporation of cytosine arabinoside into DNA
Authors: Gao Xue Zhi , Yin Moying , Wang Zique , Raza Azra , Preisler Harvey D. 
Published: May 2005

AbstractIn vitro studies of the effects of recombinant granulocyte macrophage‐colony stimulating factor (rGM‐CSF) on freshly obtained human leukemia cells were conducted to determine if there is a relationship between the effects of this growth factor on the proliferative characteristics of leukemia cells and on their incorporation of cytosine arabinoside (araC) into DNA. While rGM‐CSF was found to be able to stimulate both leukemia cell proliferation and araC incorporation, for individual leukemia specimens there was no consistent relationship among these effects. In some specimens proliferation was stimulated without an increase in araC incorporation. The reverse was also observed. These studies demonstrate the difficulty in identifying assays capable of predicting the clinical effects of growth factors on leukemia cells in patients since the effect in vitro vary with the assay.
Experimental studies on the mechanism of action of 4‐Hydroxy‐2,3‐trans‐nonenal, a lipid peroxidation product displaying chemotactic activity toward rat neutrophils
Authors: Rossi Maria Armida , Curzio Marina , Mauro Clelia Di , Fidale Fulvio , Garramone Andrea , Esterbauer Hermann , Torrielli Mario , Dianzani Mario Umberto 
Published: May 2005

AbstractThe effects of 4‐hydroxy‐2,3‐trans‐nonenal (HNE) and nonanal on the activity of phosphoinositide‐specific phospholipase C of rat neutrophils have been studied in parallel with their action on neutrophil oriented migration. Concentrations of HNE ranging from 10−7 to 10−5 M significantly stimulated the oriented migration of rat polymorphonuclear leukocytes. HNE stimulated both the basal and GTP gamma S‐induced phospholipase C activity when used at concentrations between 10−8 and 10−6 M. Nonanal was devoid both of chemotactic activity and of any action on phospholipase C activity. The effect of GTP gamma S on the stimulation of phospholipase C induced by HNE was higher when the lowest dose of the aldehyde was used; the finding of an additive effect between 10−8 M HNE and 2 × 10−5 M GTP gamma S suggests that the two compounds may share a final common pathway of action.These results suggest that the chemotactic activity of HNE might be mediated, like that of other more well‐known chemoattractants, by the stimulation of phosphoinositide‐specific phospholipase C.
Tellurite effect on ATPase activity of contractile membrane protein
Authors: Mirčevová Libuše , Kodíček Milan 
Published: May 2005

AbstractThe effect of tellurite on ATPase activity of the contractile membrane protein in human erythrocytes was studied. Tellurite, even at a concentration of 0·01 mM, inhibited 25 per cent of the saponin‐stimulated ATPase activity of the contractile membrane protein; the inhibition increased with increasing tellurite concentration, and was reversible. On the other hand, in erythrocytes preincubated with tellurite, the ATPase activity of the membrane contractile protein, non‐stimulated by saponin, increased, and the increase was further enhanced by washing the erythrocytes. The behaviour is analogous to the tellurite effect on erythrocyte morphology: incubation of erythrocytes with tellurite caused morphological changes which were more pronounced after removing the tellurite by washing. The complex effect of tellurite is discussed.
The effect of ligands on the uptake of iron by cells in culture
Authors: Jonas S. K. , Riley P. A. 
Published: May 2005

AbstractUptake of iron by a mammalian epithelial cell line (CNCM I‐221) was shown to be dependent on the nature of the iron complex. Iron uptake was demonstrated by cytochemical staining and determination of redox‐reactive iron in cell lysates. Three classes of ligands were investigated: (i) low molecular weight hydrophilic compounds, represented by ethylenediamine‐tetraacetic acid (EDTA) and other charged ligands such as adenosine phosphates (ATP, ADP, AMP) and diethylenetriaminepentaacetic acid (DTPA), (2) low‐molecular weight lipophilic ligands such as 8‐hydroxyquinoline (8‐HQ) and (3) a high molecular mass ligand, dextran. Iron complexed to 8‐HQ accumulated intracellularly, the uptake rate of iron being 4·16 fmoles cell−1 h−1 of exposure at 37°C or 3·86 fmoles cell−1 h−1 at 4°C. Iron‐dextran was endocytosed and retained in phagosomes. The uptake rate of iron following exposure to iron dextrans was found to be 5°6 fmoles cell−1 h−1 of exposure at 37°C. In contrast to iron/8‐HQ, uptake of iron dextran by cells was inhibited at 4°C. Iron complexed to low molecular weight hydrophilic ligands was not taken up by cells.Cytotoxicity was measured by reduction of plating efficiency or tritiated thymidine incorporation. These tests showed that toxic effects of added iron were demonstrable only in cells exposed to the complex with 8‐HQ.
Phorbol myristate acetate inhibits phosphoinositol lipid‐specific phospholipase C activity via protien kinase C activation in conditions inducing differentiation in HL‐60 cells
Authors: Cost Hélène , Barreau Patricia , Basset Michèle , Le Peuch Christian , Geny Blandine 
Published: May 2005

AbstractWe have studied, in streptolysin O‐permeabilized HL‐60 cell membrane preparations, the effects of phorbol 12‐myristate 13‐acetate (PMA) on polyphosphoinositide‐specific phospholipase C (PLC) activity and on terminal differentiation towards macrophagic‐like cells. We showed that terminal differentiation was induced when differentiating concentrations of the drug were present for only 1–2 h in the culture medium. Conditions inducing differentiation also inhibited PLC activity for a long lasting period (at least 5 h). When terminal differentiation affected only part of the cell population, inhibition of phospholipase C activity was found to be less marked and reversible over the period studied. Moreover in experiments done in an HL‐60 clone resistant to PMA, no inhibition of PLC activity was provoked by this tumour promotor.In order to study the involvement of protein kinase C in this process, we measured modifications of PLC activity by PMA in the presence of two different protein kinase C inhibitors, staurosporine and H‐7. They both prevented the inhibition of PLC activity by PMA indicating that this inhibition is likely to be related to the effect of PMA on protein kinase C activity. This was also confirmed by the fact that active protein kinase C, by itself, was able to decrease PLC activity when added to membrane preparations or to streptolysin O‐permeabilized control HL‐60 cells.These results indicate that PMA acts in inhibiting phospholipase C activity through its effect on protein kinase C activation and/or on protein kinase C translocation to the plasma membrane and that terminal differentiation, might be related to changes in both protein kinase C and PLC activities.
Inhibitory action of melatonin and structurally related compounds on testosterone production by mouse leydig cells in vitro
Authors: Persengiev S. , Kehajova J. 
Published: May 2005

AbstractThe possible effect of melatinin, 5‐methoxytryptamine, 5‐methoxytryptophol, 6‐chloromelatonin and 2‐iodomelatonin on testosterone production by Leydig cells in vitro was investigated. The ability of individual indoles to inhibit testosterone production was found to depend on the concentration used. The relative inhibitory potency of the compounds tested was: 6‐chloromelationin > 2‐iodomelatonin > melatonin > 5‐methoxytryptamine > 5‐methoxytryptophol. The results revealed that natural indoles which are synthesized in the pineal gland and their halogenized derivatives are capable of influencing directly testosterone production by Leydig cells. Also, these results demonstrated that melatonin exerts its remarkable antigonadotrophic effects, at least in part, through the direct decrease of testosterone production. Moreover, 6‐chloromelationin and 2‐iodomelatonin, which are reported to inhibit melatonin binding to target tissues, possess properties of biological melatonin analogues under the conditions of the model system used.
Protamine‐induced permeability changes in the neutrophil plasma membrane as the basis of activation of exocytosis
Authors: Elferink J. G. R. 
Published: May 2005

AbstractProtamine induces a gradual change in plasma membrane permeability in rabbit neutrophils, which is evident from the increase of indol fluorescence, and the leakage of quin2 from quin2‐loaded neutrophils. The influx of extracellular Ca2+ into the neutrophil provides an explanation for exocytosis which occurs in the presence of Ca2+ and protamine. The dependence of exocytosis on Ca2+ concentration follows the same pattern as is observed in neutrophils permeabilized by other means. In the absence of Ca2+, and in the presence of protamine, La3+ has an activating effect on exocytosis. At higher concentrations La3+ inhibits exocytosis that occurs in the presence of Ca2+ and protamine, as do some other metal ions. The resemblance between the membrane effects of a number of toxins, as reported in literature, and protamine‐induced membrane damage suggests that they occur via the same mechanism.