bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhanced glucose consumption in erythrocytes under mechanical stress
Authors: Kodíček Milan 
Published: May 2005

AbstractIn this paper we study the question of whether the unique features of erythrocyte (biconcave shape, extremely high deformability etc.) result only from the specific structural characteristics of the membrane or whether the maintenance of these features is conditioned by the supply of chemical energy. It is shown that glucose, the main source of cell energy, is consumed at a markedly increased rate when there is appreciable mechanical stress of the cell. This observation supports the hypothesis that there is utilization of chemical energy for the mechanical needs of the membrane.
A microspectrofluorometric study of the effect of anthralin, an antipsoriatic drug, on cellular structures and metabolism
Authors: Kohen E. , Kohen C. , Morliere P. , Santus R. , Reyftamann J. P. , Dubertret L. , Hirschberg J. G. , Coulomb B. 
Published: May 2005

AbstractThe microspectrofluorometric approach has been used to investigate in single living cells in culture fundamental questions raised by the use of anthralin, a potent antipsoriatic drug. This method allows fluorescence determinations on the intracellular fate of the drug as well as the recognition of structural and metabolic alterations induced by the drug. In the absence of demonstrable adduct formation with DNA, the antipsoriatic, i.e. antiproliferative effect of anthralin, has been attributed to its action at the level of mitochondria or at the level of glucose‐6‐phosphate dehydrogenase which initiates the pentose phosphate shunt (cf. its prominent role in nucleic acid synthesis). Upon addition of 2·3 to 23 μ M anthralin to the L cell culture, the characteristic structure of the anthralin anion fluorescence spectrum is recognized almost immediately in the cytoplasm (much weaker in the nucleus) but disappears within minutes. The vital mitochondrial fluorescence probe dimethylaminostyryl‐pyridinium‐methyl‐iodine reveals striking structural alterations of the mitochondria within 15 min after addition of the drug. At the same time, there is a stimulation of the transient NAD(P)+ reduction observed upon microinjection into the L cell of the Krebs' cycle substrate malate, or the pentose cycle substrate 6‐phosphogluconate. Specially, the injection of the latter to anthralin‐treated cells suggests that upon release of the mitochondrial control, there is a tremendous disruption of metabolic activity which could have profound consequences on the proliferative activity of the cell.These findings, while they open new possibilities for the intracellular evaluation of therapeutic agents, create also a challenge in understanding the complex and dynamic interrelationships between intracellular organelles and bioenergetic or biosynthetic pathways.
Coxsackie B4 virus induces short‐term changes in the metabolic functions of mouse pancreatic islets in vitro
Authors: Szopa T. M. , Gamble D. R. , Taylor K. W. 
Published: May 2005

AbstractMouse pancreatic islets cultured in vitro were infected with a tissue culture‐adapted or a mouse pancreas‐adapted strain of Coxsackie B4 (CB4) virus. The effects of the viruses on the islets were assessed by examination of their biochemical functions. It was found that the mouse pancreas‐adapted strain of CB4 induced a ‘leakage’ of insulin from islets incubated at a basal (2 mmol l−1) glucose concentration, both at two and four days following infection. However, at a stimulatory concentration of glucose (20 mmol l−1) the rate of insulin secretion appeared to be normal in these islets. At two days the rate of total protein synthesis in islets infected with mouse pancreas‐adapted CB4, incubated at high glucose concentration, was reduced; at four days the degree of inhibition was more severe, the rate at basal glucose concentration falling to half that of the control islets and at the stimulatory glucose concentration to a quarter of the control islets. (Pro)insulin biosynthesis was also inhibited, the rate being reduced to less than half the mean control value in islets infected with mouse pancreas‐adapted CB4 virus at 20 mmol l−1 glucose at two days; at four days the rate was greatly reduced at both 2 and 20 mmol l−1 glucose. It is concluded from this study that (1) only certain strains of CB4 virus can infect mouse pancreatic islets in vitro and (2) that infection with strains of virus tropic for the islets leads to an impairment of metabolic functions of the B‐cells, and is not necessarily lytic.
In vitro measurement and adaptive response of Fe3+ uptake by mouse intestine
Authors: Raja Kishor B. , Bjarnason Ingvar , Simpson Robert J. , Peters Timothy J. 
Published: May 2005

AbstractIn order to define the importance of the mucosal uptake step in the intestinal regulation of iron absorption, unidirectional uptake rates of Fe3+ from a nitrilotriacetic acid chelate were measured in duodenal fragments from mice using an in vitro technique. [57Co]‐Cyanocobalamin was used as a marker of adherent incubation medium. Uptake showed saturation kinetics over the concentration range 18–450 μM. Uptake was increased in fragments from hypoxic, dietary iron‐deficient and pregnant mice. The enhanced uptake was due to an increase in Vappmax. However, the modest increase in uptake rates in pregnancy and the gross changes observed in iron‐deficiency make the hypoxic model the most convenient. The increase in uptake in hypoxic animals was located to the duodenal region and was not associated with changes in either total mucosal iron content or epithelial cell turnover. The rate of uptake of iron via the serosa did not change with hypoxia. This study implies that flux of Fe3+ across the brush border is subject to adaptive regulation. The hypoxic model is suitable for investigation into the regulation of iron homestasis.
Microtubular protein impairment by pentanal and hexanal
Authors: Miglietta Antonella , Gabriel Ludovica , Gadoni Elena 
Published: May 2005

AbstractPentanal and hexanal are some of the aldehydes produced by lipid peroxidation, that causes damage to several subcellular structures. Lipoperoxidation products may directly attack cytoskeletal structures, the integrity of which is required for secretion mechanisms, e.g. 4‐hydroxy‐alkenals alter microtubular integrity and function.Purified microtubular protein incubated with pentanal and hexanal at different concentrations revealed a tubulin–aldehyde interaction affecting the polymerization reaction and the colchicine‐binding activity.These reactions apparently do not involve sulphydryl groups, and the addition of mercaptoethanol does not protect microtubules from the action of aldehydes, the effect of which is however more homogeneous, as only small differences can be noticed among the various aldehyde concentrations used.
A multiparameter analysis of the perfused rat heart: Responses to ischemia, uncouplers and drugs
Authors: Fuchs Jürgen , Zimmer Guido , Bereiter‐Hahn Jürgen 
Published: May 2005

AbstractIn perfused rat hearts alterations of aortic flow and mitochondrial membrane potential resulting from uncoupling of oxidative phosphorylation, hypoxia and treatment with a cardioprotective drug (2‐mercaptopropionylglycine (MPG)) have been studied.Mitochondrial membrane potential was followed by surface fluorimetry on DASPMI stained hearts. This fluorochrome specifically stains mitochondria in living cells; fluorescence intensity is related to the electrochemical gradient.Aortic flow turned out to be a much more sensitive indicator of heart function than ventricular pressure or mitochondrial membrane potential. No direct relationship exists between mitochondrial membrane potential and ATP production under the different metabolic conditions. Two phases of hypoxic mitochondrial damage have been deduced: the first results in derangement of ATP synthases while membrane potential is maintained, the second in irreversible damage of mitochondrial membranes with loss of membrane potential.
Age‐dependent changes in in vivo ethanol metabolism and in the activity of hepatic enzymes involved in ethanol oxidation and microsomal functions
Authors: Fernandez V. , Kriz A. , Videla L. A. 
Published: May 2005

AbstractThe study of the influence of the age of the animals (13 to 53 weeks) on the rate of ethanol metabolism in vivo and the total activity of liver alcohol dehydrogenase and microsomal ethanol oxidizing system showed a progressive decline with age. These effects were observed concomitantly with a diminution in the content of cytochrome P‐450 and microsomal functions related to oxidative and free‐radical mediated reactions, namely, NADPH oxidase activity, NADPH‐dependent oxygen uptake and NADPH‐or t‐butyl hydroperoxide‐induced chemiluminescence. It is concluded that ageing is accompanied by a diminution in the total oxidative activity of the liver tissue, which would explain the depression in basal and ethanol‐induced lipid peroxidation found in the oldest group of rats studied.
Induction of alkaline phosphatase actvity by synergistic action of dibutyryl cyclic adenosine monophosphate, prednisolone, butyrate and sodium chloride in cultured cells
Authors: Sorimachi Kenji 
Published: May 2005

AbstractHuman urinary bladder carcinoma cells (JTC‐32) retain a low alkaline phosphatase activity. Prednisolone or a hypertonic concentration of NaCl caused a moderate increase in the activity (10‐ to 15‐fold of control), but dibutyryl cAMP or butyrate did not. Examination of the combined effect of these four agents revealed that they acted synergistically in any combination. When the cells were incubated with the four agents together, the enzyme activity increased 60‐ to 250‐fold. Serum also contributed to this synergistic increase. These agents slightly inhibited cell growth and protein synthesis. The enzyme induction was completely inhibited by cycloheximide or actinomycin D. The synergistic effect of the four agents on the enzyme activity was also observed in other strains of carcinoma cells, human urinary bladder carcinoma cells (JTC‐30) and monkey hepatocarcinoma cells (NCLP‐6E). Thus, it is concluded that the coexistence of the four agents provides general and superior conditions for the induction of alkaline phosphatase in cultured carcinoma cells.
Chromatin organization in isolated nuclei: Flow cytometric characterization employing forward and perpendicular light scatter
Authors: Papa Stefano , Maraldi N. M. , Matteucci A. , Santi P. , Vitale M. , Galanzi A. , Manzoli F. A. 
Published: May 2005

AbstractFlow cytometric perpendicular and forward light scatters have been employed to evaluate whether the changes in chromatin organization due to ionic strength, Mg++ concentration and pH, visible in electron microscopy, can be monitored by flow cytometry.The average intensity of the perpendicular light scatter signal increased as nuclear chromatin became decondensed by lowering the ionic strength or releasing H1 histone at low pH values.These results indicate that flow cytometry signals and in particular the perpendicular light scatter allow the detection of the conformational transitions in chromatin and may therefore be useful for studying cell cycle associated morphological changes in isolated nuclei.
Effects of insulin and dexamethasone on adenine nucleotide levels in cultured hepatocytes from adult rat
Authors: Gallo G. , Mazzei M. , Voci A. , Fugassa E. 
Published: May 2005

AbstractInsulin and dexamethasone, usually added to culture media, play an important role in maintaining the survival of functional hepatocytes. Adenine nucleotide concentrations and energy charge values of cultured hepatocytes were determined to investigate the relationship between the beneficial effects of these hormones and the energy status of the cells. The results indicate that insulin and dexamethasone are essential in maintaining the metabolic competence of cultured hepatocytes and that this correlates with the absolute concentration of ATP rather than with the energy charge.
Epidermal growth factor receptor numbers in male and female mouse primary hepatocyte cultures
Authors: Benveniste Robert , Danoff Theodore M. , Ilekis John , Craig H. Randall 
Published: May 2005

AbstractEpidermal growth factor receptors (EGF‐R) were measured in adult male and female mouse primary hepatocyte cultures. On culture day 1, female hepatocytes had significantly fewer EGF‐R than male hepatocytes (1·3 × 104 versus 6·2 × 105 per cell). Over the next three days, morphological changes consistent with progressive heptocyte dedifferentiation were observed. During this period, EGF‐R numbers progressively increased in female cultures and decreased in male cultures, and by day 4 the sexual difference in EGF‐R numbers was obliterated. These results indicate that a relationship exists between the degree of differentiation in hepatocyte cultures and the expression of EGF‐R on the cell surface.
Improved methods for separating hydrolytic granules of neutrophil leucocytes
Authors: Takano Y. , Imai K. , Kutsukake H. , Tanaka A. , Yamamoto K. 
Published: May 2005

AbstractHighly efficient methods for isolating two hydrolytic granules of neutrophils are described. Neutrophil obtained from guinea pig peritoneal exudate cells were washed extensively with isotonic sucrose and then treated with heparin. More than 95 per cent of the cells so treated were disrupted with a Dounce homogenizer. Since nuclei were broken, leaving other organelles intact, homogenates were incubated with DNase to reduce viscosity. Postnuclear supernatants were centrifuged on a discontinuous gradient of Percoll. Azurophil granules, high in β‐glucuronidase activity, sedimented at fractions of d = 1·081 and showed very little activity of other marker enzymes. High neutral α‐glucosidase activity was observed in granular fractions of d = 1·038 and it is suggested that this is a marker for specific granules of neutrophils.
Significance of γ‐glutamyl transpeptidase and thiols in amino acid uptake by rat pancreatic islets: Studies with glutamine and leucine
Authors: Ammon H. P. T. , Fuß A. , Verspohl E. J. 
Published: May 2005

AbstractThe importance of γ‐glutamyl transpeptidase, the key enzyme of the γ‐glutamyl cycle and of thiols for the uptake of amino acids into rat pancreatic islets was investigated. Both serine–borate, an inhibitor of γ‐glutamy transpeptidase, and serine which does not inhibit this enzyme, but probabaly is a competitive inhibitor of amino acid uptake, inhibited of glutamine. The inhibitory effect of serine‐borate was not greater than that of serine alone. The uptake of glutamine was not affected by either GSH (reduced glutathione) or diamide (a thiol oxidant). Niether substances affected the uptake of leucine. The results indicate that the uptake of glutamine by rat pancreatic islets is not dependent on the functioning of γ‐glutamyl transpeptidase and that thiols are not important for the uptake of the amino acids glutamine and leucine.
Glycolysis and glutaminolysis in perifused ehrlich ascites tumour cells
Authors: Segura J. A. , Medina M. A. , Alonso F. J. , Sanchez‐Jimenez F. , De Castro I. Núñez 
Published: May 2005

AbstractA perifusion system was designed in order to study glucose and glutamine metabolism by freshly harvested Ehrlich ascites tumour cells in steady state conditions. Cells were perifused in the presence of 5 mM glucose, 0·5 mM glutamine or 5mM glucose and 0·5 mM glutamine. The results in steady state reveal that both substrates glucose and glutamine are continuously wasted by tumour cells, excreting two moles of lactate per mol of glucose and one mol of glutamate and ammonia per mol of glutamine consumed into the medium. Glutamine consumption in the presence of glucose was higher than with glutamine alone.
Fatty acid composition of phospholipids in mitochondria and microsomes during diethylnitrosamine carcinogenesis in rat liver
Authors: Canuto Rosa A. , Biocca Maria E. , Muzio Giuliana , Dianzani Mario U. 
Published: May 2005

AbstractChanges in lipid composition and function of subcellular organelles have been described in transplanted and primary tumours. We examine here the fatty acid composition of individual phospholipids (PL) in hyperplastic nodules and primary hepatoma induced by diethylnitrosamine (DEN), compared to that of normal liver and of transplantable Yoshida AH‐130 hepatoma.Phosphatidylcholine and phosphatidylethanolamine fatty acid composition in mitochondria and microsomes from primary hepatoma were markedly different from normal liver; C18:0/C18:1 ratio was lower and the ratio between monounsaturated and polyunsaturated fatty acids was higher. Linoleic acid content of mitochondrial cardiolipin, usually very high in normal rat liver, was notably lower in primary hepatoma. Cholesterol/phospholipid ratio in both microsomes and mitochondria from DEN‐induced hepatoma was higher than in normal liver. Hyperplastic nodules showed no changes in cholesterol content whereas modifications in fatty acid composition were already observeable. These modifications of membrane structure may be related to the functional changes found in nodular cells.Changes in fatty acid composition of membrane phospholipids, occurring in both primary hepatoma and preneoplastic nodules, might be one of the causes for decreased rate of lipid peroxidation peculiar to these tissues.
Action of endogenous proteases on the distribution of tyrosinase isozymes in Harding–Passey mouse melanoma
Authors: Martinez J. H. , Solano F. , Lozano J. A. 
Published: May 2005

AbstractA high percentage of the total tyrosinase found in Harding–Passey mouse melanoma occurs as a soluble form. This paper shows that melanosomal tyrosinase can be solubilized by several endogenous proteases to yield active tyrosinase. This enzyme, once proteolitically solubilized, can be further degraded, leading to enzyme inactivation. The nature and specificity of the main proteases involved in the solubilization process change depending on the size and necrosis stage of the tumour. Cathepsin B could be the main protease responsible for the solubilization in small tumours (< 0·5 g). Large tumours are rich in necrotic cells, and cathepsin D and serine‐proteases are the main hydrolytic enzymes involved in the proteolytic action on mealanosomes. These results support the view that the high activity of tyrosinase found in the soluble fraction of malignant melanoma is mainly an artefact resulting from degradation of melanosomes by a variety of endogenous proteases, rather than the result of the actual occurrence of high levels of an independent cytosolic isozyme.
Atrial natriuretic peptide in heart and specific binding in organs from fetal and newborn rats
Authors: Hersey Roscoe M. , Nazir Munir A. , Whitney Kathleen D. , Klein Robert M. , Sale Robert D. , Hinton Debbie A. , Weisz Judith , Gattone Vincent H. 
Published: May 2005

AbstractTo assess the possibility that atrial natriuretic peptide plays a role in salt and water balance during early mammalian development, we examined hearts from fetal and neonatal rates for the presence of this peptide and presumed target tissues for their ability to bind the hormone. Immunohistochemistry was used to localize and radioimmunoassay to quantify this peptide in heart. Immunoreactive artrial natriuretic peptide was visualized in the fetal heart on day 17·5 post‐conception. It was distributed throughout the atrial appendages and free wall and, in ventricle, in the trabeculae carnae and chordae tendineae. The concentrations of immunoreactive atrial natriuretic peptide in atria of rats on day 19·5 post‐conception were one‐tenth of those in the adult. Levels of this peptide in fetal ventricle were low and virtually absent from the adult tissue. Specific binding of radiolabelled atrial natriuretic peptide measured by whole organ counting occurred in several organs from 19·5‐day fetal and neonatal rats. A number of these tissues, including the kidney, ileum, adrenal, lung and liver, are targets for and/or bind the peptide in adult rats. Specific binding in these tissues was localized using autoradiography at anatomical sites similar to those in adult organs. Specific binding was also seen in fetal but not neonatal skin. In the kidney, binding was associated with immature as well as mature glomeruli. These findings support the proposition that atrial natriuretic peptide may function in the perinatal rat as it does in the adult and, in addition, may play a unique role during fetal life.
Distribution of 3‐hydroxy‐3‐methylglutaryl‐CoA reductase in isolated villus and crypt cells of chick duodenum, jejunum and ileum
Authors: Iglesias José , Gonzalez‐Pacanowska Dolores , Caamaño Guillermo , Garcia‐Peregrin Eduardo 
Published: May 2005

Abstract3‐Hydroxy‐3‐methylglutaryl‐CoA reductase (EC 1.1.1.34), the major rate‐limiting enzyme of cholesterogenesis, was studied in epithelial cells isolated in a villus to crypt gradient from chick duodenum, jejunum and ileum, in order to resolve the apparent controversy that exists on the anatomical localization of sterol synthesis in the intestine. Consistent separation was demonstrated by using the marker enzymes alkaline phosphatase, specific to the villus cells, and thymidine kinase, specific to the crypt cells. No relative difference in stability was observed, as shown by the equal distribution of acid phosphatase. Cells were 90–95 per cent viable. The highest specific activity of reductase was located in the microsomal fraction (41 per cent of the total). The mitochondria had lower specific activity (8 per cent of the total). The distribution of reductase activity in epithelial cells of the villus–crypt axis was also studied. The specific activity in each cell fraction from chick duodenum was clearly lower than that in jejunum and ileum. The jejunal and ileal crypt regions showed lower specific activity than the villus cells. About 70 per cent of total reductase activity was found in cells from the upper and the mid villus fraction in each intestinal segment.
Dual inhibitory effect of bredinin
Authors: Kusumi T. , Tsuda M. , Katusunuma T. , Yamamura M. 
Published: May 2005

AbstractBredinin inhibition of cell growth was investigated in the mouse lymphoma cell line L5178Y. Bredinin caused the accumulation of IMP and the reduction of XMP. It was converted to the 5′‐phosphate within the cells. Bredinin 5′‐phosphate but not bredinin competitively inhibited both IMP dehydrogenase and GMP synthetase. Thus the inhibition of cell growth is probably due to bredinin 5′‐phosphate, which inhibits the consecutive enzyme reactions IMP dehydrogenase and GMP synthetase. These inhibitions result in the accumulation of IMP and the reduction of XMP.
Protein metabolism in the small intestine of the ethanol‐fed rat
Authors: Preedy Victor R. , Peters Timothy 
Published: May 2005

AbstractThe effects of chronic ethanol feeding on the small intestine were investigated in young rats. Rats were fed a nutritionally‐adequate liquid diet, containing 36 per cent of total energy as ethanol (treated, n = 7), or isovolumetric amounts of the same diet in which ethanol was substituted by isocaloric glucose (controls, n = 7). After six weeks the wet weight and total tissue contents of protein, RNA and DNA were significantly reduced by 21 per cent, 23 per cent, 16 per cent and 28 per cent respectively, (p < 0·014).Rates of protein synthesis were measured with L[43H]phenylalanine and fractional rates (defined as the percentage of constituent tissue protein synthesised each hour, i.e. ks, % h−1) were calculated from the specific radioactivity of free phenylalanine in both tissue homogenates and plasma. Ethanol‐feeding reduced ks by approx 10 per cent (p < 0·181). The amount of protein synthesized unit−1 RNA was also reduced by approx 15 per cent (p < 0·059) but the amount of protein synthesis unit−1 DNA was unaffected by ethanol‐feeding (p < 1·000). In contrast, the absolute rates of protein synthesis were reduced by approximately 30 per cent (p < 0·022).It was concluded that, as the small intestine contributes to approx. 20–25 per cent of whole body synthesis these results may have an important effect on whole body nitrogen homeostasis and may have implications for the gastrointestinal effects of ethanol seen during chronic alcoholic abuse.