bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intracellular production of reactive oxygen species in human neutrophils following activation by the soluble stimuli FMLP, dioctanoylglycerol and ionomycin
Authors: Follin Per , Johansson Agneta , Dahlgren Claes 
Published: May 2005

AbstractThe stimuli, sn‐1, 2‐dioctanoylglycerol; (DG8) the calcium specific inophore, ionomycin, and the chemotactic peptide formylmethionyl‐leucyl‐phenylalanine (FMLP) can interact with normal human neutrophils and activate their superoxide/hydrogen peroxide generating NADPH‐oxidase. In response to the peptide as well as DG8, the neutrophils produced both superoxide (O2−) and hydrogen peroxide (H2O2). Since interaction between the cells and ionomycin was not associated with any notable superoxide production and hydrogen peroxide was induced only in the presence of azide, a potent inhibitor of the hydrogen peroxide‐consuming enzymes catalase and myeloperoxidase, we conclude that this stimulus can generate oxygen metabolites intracellularly. Since the DG8‐induced production of hydrogen peroxide was increased in the presence of azide, whereas the FMLP‐induced response was largely unaffected, we concluded that the three stimuli differ in their capacity to generate oxygen metabolites intracellularly.The use of sn‐1,2‐didecanoylgylycerol (DG10) as stimulating agent did not result in any detectable activation of the NADPH‐oxidase. However, preincubation caused an increased (primed) response during stimulation with the chemotactic peptide FMLP. The response of primed neutrophils to FMLP proceeds with a time‐course different from that seen in normal cells. From the results presented on FMLP‐induced activity in the presence of azide, we conclude that FMLP causes normal cells to produce oxygen radicals which are released from the cells. However, the primed cells are also capable of generating oxygen metabolites that are retained inside the cells. In fact, measurement of the intracellularly generated metabolites discloses this to be the predominant part of the response.
Studies of the proliferation and differentiation of immature myeloid cells in vitro: 4: Preculture proto‐oncogene expression and the behaviour of myeloid leukemia cells in vitro
Authors: Yin Mo Ying , Gao Xue Zhi , Wang Zique , Preisler Harvey D. 
Published: May 2005

AbstractStudies were conducted to determine the relationship between the pretherapy characteristics of leukemia cells and their behaviour during culture in vitro. Leukemia cells which proliferated well in vitro also proliferated well in vivo. Cells which manifested myeloid or monocytic differentiation in vivo tended to manifest differentiation along these lines in vitro. Cells which manifested high levels of expression of c‐fms, c‐fes, or triose phosphate isomerase prior to culture were likely to differentiate in vitro, with high levels of c‐fes expression being related to myeloid maturation. These observations suggest that differentiation at the molecular level prior to culture is a requisite for leukemia cell differentiation in vitro. The same may be true for differentiation in vivo under the influence of exogenously administered agents such as cytotoxic chemotherapy or recombinant growth factors.
Metabolic labelling and partial characterization of glycophospholipids in pancreatic islet cells
Authors: Albor Amador , Cáamara Javier , Mato José M. , Malaisse Willy J. , Verde Isabel Val 
Published: May 2005

AbstractInsulin action is thought to be mediated by an inositol‐, glucosamine‐ and galactose‐containing oligosaccharide liberated by phosphodiesterase hydrolysis of a glycosyl‐phosphatidylinositol. This oligosaccharide inhibits insulin biosynthesis and secretion in pancreatic islets. In the present study, two main glycolipids (peak I and II) were resolved by sequential TLC of lipids extracted from islet cells labelled with tritiated glucosamine, galactose or myristate. The two glycolipids displayed comparable sensitivity to β‐galactosidase but differed from one another by their sensitivity to phosphatidylinositol‐specific phospholipase C. Moreover, structural heterogeneity within each peak was suggested by their partial resistance to nitrous acid deamination. These findings support the presence in islet cells of glycolipids similar to those currently considered as a possible postreceptor target for insulin in other cell types.
Effect of chronic ethanol consumption on postnatal development of renal (Na + K)‐ATPase in the rat
Authors: Rodrigo Ramón , Vergara Leoncio , Oberhauser Ernesto 
Published: May 2005

AbstractRenal (Na + K)‐ATPase was studied to ascertain whether it follows the pattern of adaptation of membrane‐bound enzymes that are inhibited by acute ethanol exposure and develop greater activity after chronic ethanol treatment. A colony of rats was given 20 per cent (v/v) ethanol as sole drinking solution throughout gestation, lactation and following weaning. (Na + K)‐ATPase and ouabain‐insensitive Ca2+‐ATPase activities were determined; regional distribution of these enzymes was assessed in renal cortex and outer medulla. Control rats drank tap water.(Na + K)‐ATPase in whole homogenate of kidney increased with age in controls and ethanol‐fed rats, but the latter showed higher values at every age studied. Between 15 and 60 days of age, the control group showed 2‐fold increases in cortex and 5‐fold in outer medulla, whereas ethanol‐fed rats reached a 3‐fold increase in the enzyme activity in both renal regions. Ca2+‐ATPase showed the same time course in developing kidney of both groups. Chronic ethanol treatment of adult rats resulted in an increase of (Na + K)‐ATPase activity in cortex and outer medulla, but no change in other ATPases.Since an earlier maturational development of renal (Na + K)‐ATPase was displayed by ethanol‐fed rats, underlying mechanisms that may account for these results are discussed.
Simultaneous changes in various mechanisms that mediate the cell incorporation of folate compounds account for low levels of resistance to methotrexate
Authors: Cavalcanti F. , Calvo N. , Grau‐Oliete M. R. , Rivera‐Fillat M. P. 
Published: May 2005

AbstractChanges in the mechanisms of folate incorporation were studied in cells treated with low concentrations of methotrexate in order to evaluate their contribution to the development of resistance to antifolate drugs. The uptake of methotrexate via reduced‐folate system, the membrane‐associated high‐affinity folate binding capacity and the activity, levels and affinity for methotrexate of dihydrofolate reductase were measured in L5178 murine leukemic lymphoblasts and in a subline, MTX/R16, 16 times more resistant to methotrexate which was isolated after a short exposure to the antifolate. Various simultaneous changes were characterized in MTX/R16 cells which co‐participated in the development of resistance: a decreased affinity of the carrier for methotrexate uptake via the reduced‐folate system of entry, the increase of dihydrofolate reductase activity and levels and a two‐fold increased expression of a membrane‐associated high‐affinity folate‐binding protein (mFBP). The increase of the mFBP expression, besides ensuring the growth of resistant cells by its contribution to the reduced folate intake, also participates in the methotrexate resistance by the internalization of folate cofactor which would compete with methotrexate hindering the effective inhibition of dihydrofolate reductase by the antifolate.
Identification of multi‐drug resistant cells in sensitive friend leukemia cells by quantitative videomicrofluorimetry
Authors: Lahmy S. , Salmon J. M. , Vigo J. , Viallet P. 
Published: May 2005

AbstractThe cellular resistance to cytotoxic drugs, particularly to anthracyclines, remains a major problem in cancer chemotherapy. A number of biochemical mechanisms have been described, one of them being a lower accumulation of drugs in resistant cells. The accumulation of Ho33342 in sensitive and resistant Friend leukemia cells was studied by quantitative fluorescence image analysis, a method which allows investigations to be made on living tissues and cells. The intensity of fluorescence is related to the amount of Ho33342 accumulated into the cells and has been found to be more intense in sensitive cells than in resistant ones. Moreover, the retention of this vital dye was inversely related to the degree of resistance in the three resistant cell lines. The addition of verapamil, which is known to reverse resistance to anthracyclines, resulted in an increase of the amount of Ho33342 accumulated in the resistant cells. Ho33342 presents a higher quantum yield than any other anthracyclines, such as adriamycin and can be used as a microfluorimetric probe to identify the resistant cells in a heterogeneous cell population.
The effects of monensin on blood‐borne arrest and glycosylation of BL/VL3 lymphoma cells
Authors: Di Virgilio Sergio , Rampelberg Murielle , Greimers Roland , Schnek Georges , Hooghe Robert 
Published: May 2005

AbstractWe have previously shown that inhibitors of N‐glycan processing alter both the cell surface carbohydrates and the homing properties in lymphoid cells. We have now studied the effects of the ionophore monensin (MON) on these parameters.Arrest in the spleen of [111In]‐labelled BL/VL3 murine T lymphoma cells, injected intravenously was clearly reduced if the cells had been cultured for 24 h in the presence of monensin (0·1–1·0 μg ml−1).We have characterized glycopeptides from BL/VL3 murine T lymphoma cells. Following labelling with tritiated precursors (fucose, mannose, galactose, glucosamine), surface glycopeptides from BL/VL3 murine T lymphoma cells, were released by trypsin and separated by gel filtration on Bio‐Gel P6 and by affinity chromatography on immobilized lectins.After treatment with MON, a class of high molecular mass glycopeptides was no longer found. There were less complex and more high mannose glycans, as a consequence of a reduction of terminal glycosylation (sialylation, fucosylation or incorporation of N‐acetyl‐glucosamine). Similar findings were obtained with immunoprecipitated Thy‐1 antigen. However, as estimated by flow cytometry analysis, the cell surface expression of Thy‐1 was not reduced in MON‐treated cells. Taken together our results show that cell surface oligosaccharides are modified dramatically, but that at least, certain cell surface antigens are present in normal amounts. It is tempting to speculate that changes in glycosylation account for the abnormal homing properties of MON‐treated cells.
Stimulation of human platelets with concanavalin a involves phospholipase C activation
Authors: Torti Mauro , Balduini Cesare , Ramaschi Giuseppe , Sinigaglia Fabiola 
Published: May 2005

AbstractIn response to concanavalin A, cytoplasmic calcium movement was observed in human platelets, both in the presence of 1 mM Ca2+ or 1 mM EGTA in the medium. Concanavalin A also caused the activation of inositide turnover and the production of inositol phosphates, suggesting that activation of phospholipase C occurs. The mechanism by which concanavalin A stimulates phospholipase C does not depend on GTP‐binding transducers, because it was not inhibited by GDPβS, while experiments performed in the presence of cytochalasin B suggested a role for membrane glycoprotein IIb‐IIIa‐cytoskeleton interaction in this process. Ca2+‐proteases and Na +/H+ antiport also seemed to be related to concanavalin A‐induced phospholipase C activation, as suggested by experiments performed in the presence of leupeptin and amiloride.
Added ATP influences some responses of rat synaptosomes to glutamate
Authors: Galzigna L. , Bianchi M. , Rizzo V. , Battistin T. , Scarpa M. , Rigo A. 
Published: May 2005

AbstractATP added externally to rat synaptosomes activated uptake of both Ca2+ and glutamate which was partially accounted for by the uptake phenomena of synaptic vescles and mitochondria, as shown by using specific inhibitors of the latter. Increasing concentrations of glutamate stimulated Ca2+ entry linearly, as shown by using 45Ca or a Ca‐specific electrode. The processes of glutamate and Ca2+ uptake shared some common features and their ATP‐dependence may be correlated with an ouabain‐insensitive synaptosomal ectonucleotidase activity measured by a 31P‐NMR or a luminometric technique. The ATP hydrolysis catalysed by the synaptosomes was activated by both Ca2+ and glutamate. The present synaptosomal activities may represent a model for studying the modulatory effects of ATP on the glutamatergic neurotransmission.
Proliferating cell nuclear antigen (PCNA/cyclin) in plant proliferating cells: Immunohistochemical and quantitative analysis using autoantibody and murine monoclonal antibodies to PCNA
Authors: Daidoji Hideyuki , Takasaki Yoshinari , Nakane Paul K. 
Published: May 2005

AbstractProliferating‐cell nuclear antigen (PCNA), also known as cyclin, is synthesized in proliferative cells and recently was identified as DNA polymerase‐delta auxiliary protein. In this paper, the association of PCNA to the proliferative cells of plants was analysed using both autoantibodies to PCNA obtained from a patient with systemic lupus erythematosus (SLE) and murine monoclonal antibodies.By immunohistochemical analysis, nuclei of cells around the growing point in soybean root tips reacted strongly with autoantibodies to PCNA in the serum from a patient with SLE. The plant PCNA in root tip cells was purified by ammonium sulfate fractionation, DEAE chromatography, and affinity chromatography. The partially purified plant PCNA was tested by immunoblotting and a 34 kD polypeptide reacted with both the human anti‐PCNA autoantibody and a mouse monoclonal antibody against human PCNA (TOB 7). In addition, the purified plant PCNA reacted with both antibodies in enzyme‐linked immunosorbent assay (ELISA). The binding of anti‐PCNA serum to the animal PCNA was blocked by the plant PCNA in this ELISA. The association of PCNA with growing cells in plants was further confirmed by quantitative sandwich type ELISA using two murine monoclonal antibodies to PCNA, TOB7 and TO17. Those results suggested that PCNA in both plant and animal cells had the same immunological and biochemical characteristics and the plant PCNA might play an important role in cell growth, existing as it does in proliferating plant cells.The concentration of PCNA in soybean germ extract before germination was less than 5 ng ml−1 (protein concentration, 6·8 mg ml−1), but that of the root tip stem including the growing point increased to 887 ng ml−1 (protein concentration 3·8 mg ml−1) in the second day after germination.
Modifications of adhesion properties and proteoglycan structure in rat embryo fibroblast cultures with increasing passages
Authors: Pippia P. , Formato M. , Sciola L. , Tilloca G. , Bardoni A. , Pallavicini G. , Passi A. , Rindi S. , Salvini R. , De Luca G. 
Published: May 2005

AbstractAdhesion properties of rat embryo fibroblast cultures and proteoglycans (PGs) produced both in the growth medium and in the cell layer were investigated with increasing passages. Both cell–cell and cell–substrate adhesion increased with increasing subculture number. Cell adhesion properties were improved by cell treatment with chondroitinase ABC. The increase in subculture number was coupled with a constant increase of PG molecular size, which was particularly evident in cell layer extracts. The ratio HS–PGs/DS–PGs increased with increasing passages. PG modifications are likely to represent evidence of changes in extracellular matrix organization and could play a role in the increase of cell adhesion properties.
Ornithine decarboxylase and ornithine decarboxylase‐inhibiting activity in rat thymocytes
Authors: Stefanelli Claudio , Rossoni Carmen , Ferrari Fabrizia , Flamigni Flavio , Caldarera Claudio M. 
Published: May 2005

AbstractIsolation of thymocytes from rat thymus resulted in the disappearance of the high activity of ornithine decarboxylase (ODC) that characterizes the thymus of young rats, together with the appearance of an antizyme‐like ODC inhibiting activity, which showed a chromatographic profile that resembled that of dexamethasone‐treated rat thymus. Omission of serum or addition of dexamethasone or spermidine did not affect appreciably the extent of the antizyme‐like activity. On the other hand, a variety of hormonal effectors, i.e. insulin, glucagon, adrenalin and T3, as well as the phorbol ester, PMA or the mitogen, concanavalin A (Con A) induced ODC activity in cultured thymocytes together with the disappearance of the antizyme‐like activity. A paradoxical, transient induction of ODC was caused by the transcriptional inhibitor, actinomycin D. Complexed ODC was detected in rat thymus, but not in thymocytes, either quiescent or stimulated by mitogens. These results indicate that thymic lymphocytes can express either ODC activity or its inhibitor depending on the hormonal and proliferative status of the cells.
Phosphate efflux from jejunal enterocytes of the rat: Effect of phosphate concentration gradient and pH
Authors: Al‐Sawan S. , Skillen A. W. 
Published: May 2005

AbstractThe effect of variation in the intracellular and extracellular phosphate concentration on the Pi efflux across the basolateral membrane of pre‐loaded enterocytes has been examined. Efflux rate constants for Pi fell from 0·89 h−1 to 0·68 h−1 as the extracellular Pi concentration was increased from 0·5 mM to 5 mM. As the intracellular Pi concentration was raised from 0·5 to 3 mM the rate constant dropped from 0·95 h−1 to 0·77 h−1. The findings are indicative of the presence of Pi‐specific transporter at the basolateral membrane. The efflux rate constant of Pi at pH 7·1 was higher than that at pH 7·4 suggesting that the Pi flux across the basolateral membrane of enterocytes follows a similar pattern towards pH changes as do fluxes across the brush‐border membrane.
Normal and Ha‐ras‐1 oncogene transformed buffalo rat liver (BRL) cells show differential resistance to cytoskeletal protein inhibitors
Authors: Theodoropoulos P. A. , Gravanis A. , Saridakis I. , Stournaras C. 
Published: May 2005

AbstractIn the present study, using immunofluorescence microscopy, we have demonstrated that normal and Ha‐ras‐1 transformed Buffalo rat liver (BRL) cells which were exposed to cytoskeletal protein inhibitors, showed a differential resistance of their microfilament and microtubule networks. One hour exposure of normal BRL cells to 10−5 M cytochalasin B provoked a clear and already total breakdown of actin filaments. However, at this concentration of cytochalasin B, the microfilaments of transformed BRLHO6T1–1 cells were not seriously affected; a higher cytochalasin B concentration (≥ 2 × 10−5 M) was required to induce a significant breakdown of microfilaments in these transformed cells. The two cell lines also demonstrated differential microtubule stability when they were treated with either colchicine or triethyllead. Three hours exposure to 10−6 M of either antimicrotubule agents was sufficient to disrupt the microtubules of normal BRL cell, without affecting their counterparts in the transformed BRLHO6T1–1 cells. A 10‐fold higher drug concentration (10−5 M) was required to induce microtubular breakdown in the transformed BRL cells. The differential stability of microfilaments and microtubules in normal and transformed BRL cells that was observed could not be attributed to a differential internalization of the agents, as shown by experiments on the uptake of [3H]‐cytochalasin B and triethyllead. In addition, the transformed BRLHO6T1–1 cells did not express altered actin and tubulin isoforms, as demonstrated by isoelectric focusing followed by immunoblotting analysis. We conclude that the transformation of BRL cells with the Ha‐ras‐1 oncogene results in a greater stability of microfilaments and microtubules, leading to a structurally firmer cell shape. Transformed BRLHO6T1–1 cells offer an interesting model for the study of the molecular and cellular mechanisms by which oncogenic transformation alters cytoskeletal structures.
Ethanol‐induced inhibition of ventricular protein synthesis in vivo and the possible role of acetaldehyde
Authors: Siddiq Tahir , Richardson Peter J. , Mitchell William D. , Teare Julian , Preedy Victor R. 
Published: May 2005

AbstractWe have determined the extent to which acute ethanol administration perturbs the synthesis of ventricular contractile and non‐contractile proteins in vivo. Male Wistar rats were treated with a standard dose of ethanol (75 mmol kg−1 body weight; i.p.). Controls were treated with isovolumetric amounts of saline (0·15 mol 1−1 NaCl). Two metabolic inhibitors of ethanol metabolism were also used namely 4‐methylpyrazole (alcohol dehydrogenase inhibitor) and cyanamide (acetaldehyde dehydrogenase inhibitor) which in ethanol‐dosed rats have been shown to either decrease or increase acetaldehyde formation, respectively. After 2·5 h, fractional rates of protein synthesis (i.e. the percentage of tissue protein renewed each day) were measured with a large (i.e. ‘flooding’) dose of L‐[4‐3H]phenylalanine (150 μmol (100 g)−1 body weight into a lateral vein). This dose of phenylalanine effectively floods all endogenous free amino acid pools so that the specific radioactivity of the free amino acid at the site of protein synthesis (i.e. the amino acyl tRNA) is reflected by the specific radioactivity of the free amino acid in acid‐soluble portions of cardiac homogenates. The results showed that ethanol alone and ethanol plus 4‐methylpyrazole decreased the fractional rates of mixed, myofibrillar (contractile) and sarcoplasmic (non‐contractile) protein synthesis to the same extent (by approx. 25 per cent). Profound inhibition (i.e. 80 per cent) in the fractional rates of mixed, myofibrillar and sarcoplasmic protein synthesis occurred when cyanamide was used to increase acetaldehyde formation. There was also a significant decrease in cardiac DNA content. The results suggest that acute ethanol‐induced cardiac injury in the rat may be mediated by both acetaldehyde and ethanol.
Change of liver metabolism of 1,2‐dibromoethane during simultaneous treatment with carbon tetrachloride
Authors: Chiarpotto E. , Biasi F. , Aragno M. , Scavazza A. , Danni O. , Albano E. , Poli G. 
Published: May 2005

AbstractThe combination of carbon tetrachloride (CCl4) and 1,2‐dibromoethane (DBE) in isolated rat hepatocytes led to a significant potentiation of both lipid peroxidation and of plasma membrane damage observed after a single treatment with CCl4. Such a synergistic effect appeared to be related to the CCl4‐induced shift of DBE metabolism from the cytosolic conjugation with glutathione towards the microsomal transformation into toxic intermediates. In fact, CCl4 significantly inactivated hepatocyte total GSH‐transferase, i.e. the DBE detoxification pathway. Furthermore, while the microsomal metabolism of CCl4 was not affected by the simultaneous presence of DBE, the amount of DBE reactive metabolities covalently bound to hepatocyte protein was significantly enhanced in the presence of CCl4.