bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanisms of interaction between human skin fibroblasts and elastin: Differences between elastin fibres and derived peptides
Authors: Groult V. , Hornebeck W. , Ferrari P. , Tixier J. M. , Robert L. , Jacob M. P. 
Published: May 2005

Abstract3H‐Labelled kappa‐elastin peptides (kE:75 kDa molecular weight) were shown to bind to confluent human skin fibroblast (HSF) cultures in a time‐dependent and saturable manner. Scatchard analysis indicated the presence of high affinity binding sites with kD = 2·7 × 10−10 M and 19 000 sites per cell. Binding of kE to its receptor on HSF accelerates and intensifies the adhesion of insoluble elastin fibres (iE) to confluent HSF. Optimal effect was attained for a kE concentration of 0·3 × 10−9 M close to kD. This stimulatory effect of kE on the binding of iE to HSF could be inhibited by neomycin, retinal and pertussis toxin, substances which act at different levels of the transduction mechanism following the activation of the receptor and the subsequent triggering of cell biological events (chemotaxis, modification of calcium fluxes). The stimulation of iE adhesion to HSF induced by kE as well as kE binding to the cells could by inhibited by lactose and laminin but not by Arg‐Gly‐Asp‐Ser (RGDS) peptides. This indicates that the elastin peptide receptor on HSF possesses lectin‐like properties and shares homology with the laminin receptor as also shown for other cell types. None of the substances tested, that is inhibitors of the transduction mechanism, lactose, laminin and Arg‐Gly‐Asp‐Ser (RGDS) peptides were shown to interfere significantly with the binding of iE (in the absence of added kE) to confluent HSF. The proteins adhering strongly to elastin fibres were isolated by a sequential extraction procedure and the final hydrochloride guanidinium‐DTT extract was analysed by SDS–PAGE under reducing conditions, Western blots using specific antibodies against several connective tissue proteins and affinity for [3H]‐kE following nitrocellulose electro‐transfer of proteins. Fibronectin, vitronectin, tropoelastin(s), and a 120 kDa cysteine rich glycoprotein previously designated as elastonectin were identified. Among these proteins, [3H]‐kE was found to bind exclusively to a 65 kDa protein that could be eluted selectively from elastin fibres with a neutral buffer containing 100 mM lactose. Therefore the elastin peptide receptor on human skin fibroblasts shares properties with the elastin receptor characterized from other cell types. Conformational differences between elastin peptides and elastin fibres could explain the differences in the mechanisms of interactions between elastin fibres and elastin peptides with HSF in culture. The stimulatory effect of elastin‐derived peptides on the adhesion of elastin fibres to HSF could have implications in the oriented biosynthesis of elastin fibres.
Mitochondrial nucleotide translocase from skeletal muscle of halothane sensitive pigs: An electrophoretic study
Authors: Ayoub S. , Berson G. , Rock E. , Younes A. 
Published: May 2005

AbstractATP translocation into mitochondria isolated from halothane‐sensitive pig (HP) muscle was dramatically reduced compared with normal pigs (NP). To determine if this was due to a decreased amount of ATP translocase in the mitochondrial membranes, or a structural modification of this protein, an electrophoretic study was undertaken. Total proteins and purified translocase preparations from (NP) and (HP) mitochondria were analysed by SDS gel electrophoresis. In the two type of mitochondria no significant differences were observed either in the amount of ATP translocase or in the molecular weight. Also, neither nonequilibrium pH gradient gel electrophoresis nor the analysis of peptides produced by limited proteolysis revealed any structural difference between the two types of protein. On the basis of these results, the depressed translocase activity observed in (HP) mitochondria cannot be explained by a reduced amount of the nucleotide translocase, nor a structural alteration of this protein. Possible inhibition of (HP) translocase activity by Ca2+ accumulation or by other mechanisms is discussed.
A comparative study of the effects of the diamine oxidase inhibitor aminoguanidine, with or without dietary restriction, on the nucleic acid and protein composition of cardiac and type I and type II skeletal muscles of the rat
Authors: Siddiq Tahir , Preedy Victor R 
Published: May 2005

AbstractIt has been proposed that the diamine oxidase inhibitor aminoguanidine may be a potential therapeutically important anabolic agent. An investigation was therefore made into the effects of aminoguanidine treatment with or without nutritional restriction, on cardiac and skeletal muscles containing mainly of either Type I (i.e. soleus) or Type II fibres (i.e. plantaris) or a mixture of Type I and II fibres (i.e. gastrocnemius).After 3 weeks, dietary restrictions reduced cardiac weight, protein, RNA and DNA contents by between 31 per cent and 36 per cent. Similar, but smaller, reductions were observed in the soleus (18–31 per cent), plantaris (22–34 per cent) and gastrocnemius (22–34 per cent).Aminoguanidine had no effect on the heart of the rats fed ad libitum, nor did it alter the response to dietary restriction. Treatment with aminoguanidine had no overt anabolic effect on skeletal muscle, but a reduction in DNA content was observed.It was concluded that cardiac protein and nucleic acid contents are more sensitive to dietary deprivation than either anaerobic or aerobic skeletal muscles. Furthermore, aminoguanidine does not appear to promote growth or reduce catabolism as previous studies have suggested.
Reduced neutrophil superoxide generation and plasma lipoperoxide levels in pigs fed with cod liver oil
Authors: Guarnieri Carlo , You‐Zhou Li , Roth Elizabeth , Biagi Pierluigi , Ussia Giovanni , Baccarini Elisabetta , Farruggia Francesco , Anderson Gary L. , Barker John H. , Galletti Giovanni 
Published: May 2005

AbstractCirculating neutrophils, isolated from pigs fed for 8 weeks with a diet supplemented with CLO, had an accentuated n‐3 fatty acid incorporation into the plasma membrane, as evidenced by an approximately four‐fold greater n‐3/n‐6 ratio as compared with the control diet group. Moreover, the neutrophils of the CLO fed pigs produced less superoxide when stimulated with PMA or f‐MLP, as well as showing a more prolonged latency period before O2−‐generation. In the plasma of pigs fed with CLO there were higher levels of thiobarbituric reactive material and lipofuscin, while the content of GSSG was similar in both dietary groups.The results of this study indicate that dietary supplementation with CLO reduces the activation of circulating neutrophils and favours the presence in the plasma of lipoperoxides.
Relation between hyaluronan and sulphated glycosaminoglycan synthesis and degradation in cultured embryonic fibroblasts. Effect of concanavalin a and ammonium chloride administration
Authors: Carinci P. , Locci P. , Evangelisti R. , Marinucci L. , Rossi L. , Becchetti E. 
Published: May 2005

AbstractIn order to evaluate the relationship between glycosaminoglycan (GAG) synthesis and degradation, the effect of NH4Cl, which inhibits lysosomal degradation, on GAG production was analysed in vitro in concanavalin A (Con A) stimulated fibroblasts from 7 and 14‐day‐old chick embryos. 35SO4 incorporation into total proteoglycan (PG), 3H incorporation into individual GAG classes, β‐N‐acetyl‐D‐glucosaminidase and β‐D‐glucuronidase activity were determined. The results indicate a correlation between Con A and NH4Cl effects: NH4Cl induced a reduction principally in the GAG classes most stimulated by Con A. Thus HA and DS are much more stimulated by Con A and inhibited by NH4Cl than are CS and HS.
Hepatic selective adjustments in short‐term cold exposed rats
Authors: Iossa S. , Barletta A. , Liverini G. 
Published: May 2005

AbstractThe metabolic adjustments which occur in rat liver cells during the first days of cold exposure have been investigated. We have measured both mitochondrial mass and oxidative capacities as well as ATP production after five and 10 days of cold exposure. In addition, we have measured plasma membrane Na+/K+‐ATPase activity. Cold exposure elicited a significant increase in mitochondrial mass as well as in state 3 oxidative rates and ATP production in isolated mitochondria using various substrates. Moreover, our results show that Na+‐pumping activity significantly increased after both five and 10 days of cold exposure.Our results suggest that during the first days of cold exposure liver cells undergo alterations which are useful for survival in the cold.
Metabolic activity in isolated hepatocytes from cold exposed rats subjected to 24‐hour fasting
Authors: Iossa S. , Barletta A. , Liverini G. 
Published: May 2005

AbstractThe aim of this work was to study the metabolic activity in isolated hepatocytes from control rats and rats exposed for 15 or 30 days to cold, all subjected to 24‐h fasting. Hepatocyte oxygen consumption was used as an index of metabolic activity. The results show that 24‐h fasting induces a decrease in energy expenditure at the level of the liver in cold‐exposed rats but not in control animals.
Balancing of energy‐consuming processes of K 562 cells
Authors: Siems Werner G. , Schmidt Heike , Gruner Stefan , Jakstadt Manuela 
Published: May 2005

AbstractA balance of ATP‐consuming processes in human erythroleukemia (K 562) cells by use of the decreased 14CO2 formation from [1‐14C]‐glutamate following inhibition of energy‐requiring processes is presented. This method was tested on Ehrlich mouse ascites tumour cells and was used in suspensions of K 562 cells with a low cell content. More than 90 per cent of the ATP produced by oxidative phosphorylation could be accounted for in K 562 cells. Protein synthesis consumed about 35 per cent, Na+/K+‐ATPase about 20 per cent and transcription processes 5–10 per cent of the total ATP. The share of the Ca2+‐dependent reactions was notably high at 25 per cent in comparison with Ehrlich mouse ascites tumour cells, reticulocytes or hepatocytes. ATP consumption by DNA synthesis was assessed at 5–10 per cent. Only less than 10 per cent of the consumption of ATP produced oxidatively remained for other cellular reactions. The degree of coupling of K 562 cells was high in comparison with that of other eukaryotic cell types.
In situ localization of male germ cell‐associated kinase (mak) mRNA in adult mouse testis: Specific expression in germ cells at stages around meiotic cell division
Authors: Koji Takehiko , Jinno Atsushi , Matsushime Hitoshi , Shibuya Masabumi , Nakane Paul K. 
Published: May 2005

AbstractBiochemical analysis of the male germ cell‐associated kinase (mak) gene, which was isolated recently by using weak cross‐hybridization with the v‐ros tyrosine kinase gene, revealed that the gene was highly expressed in mammalian testicular germ cells, but not in ovarian cells. In order to identify the cells which express the mak gene in more detail, we localized mak mRNA in frozen sections of mouse testis by non‐radioactive in situ hybridization. In this study, we utilized thymine–thymine (T‐T) dimerized mak cDNA as a haptenic, non‐radioactive probe, and the signal was detected enzyme‐immunohistochemically by using an anti‐T‐T antibody. As a result, mak mRNA was localized intensely in late pachytene (stage X) and diplotene (stage XI) spermatocytes, and faintly in dividing spermatocytes (stage XII) and early round spermatids (stage I–II), suggesting that the gene may play an important role in the phase around meiotic cell division, but not throughout the entire meiosis.
Kinetics of expression of prion protein in uninfected and scrapie‐infected N2a mouse neuroblastoma cells
Authors: Pfeifer Karin , Bachmann Michael , Schröder Heinz C. , Forrest Jock , Müller Werner E. G. 
Published: May 2005

AbstractThe scrapie prion protein, PrPSc, is formed from its isoform, the cellular PrPc. There is evidence available indicating that PrPSc is necessary component of the infectious prion particle to cause a series of transmissible spongiform encephalopathies. We have used immunocytochemistry and RNA blotting techniques to investigate if infection with prions results in an increased PrP gene expression. For the experiments we used N2a cells which had been infected with prions (ScN2a cells). We demonstrated by confocal laser scanning microscopy that PrP‐protein was present in the nucleus (predominantly in the nucleoli) of ScN2a cells. Analysis of the PrP‐mRNA levels both in N2a‐ and in ScN2a cells using cDNA encoding PrPc revealed no marked alteration of the mRNA steady state level between the two cell strains. Likewise, in run‐off experiments no changes in either PrP‐specific transcription or in general transcriptional activity were found. The half‐life of PrP‐mRNA was found to be identical in both cell strains (7 h). Taken together, these results show that PrPSc and /or PrPc is present in the nucleus (nucleoli) of ScN2a cells but does not display and effect on the expression of the PrP gene.
Proliferation‐associated increase in sensitivity of mammary epithelial cells to inositol‐1,4,5‐trisphosphate
Authors: Enomoto Koh‐ichi , Furuya Kishio , Yamagishi Shunichi , Maeno Takashi 
Published: May 2005

AbstractInjection of D‐myo‐inositol‐1,4,5‐trisphosphate (IP3) was found to induce a transient increase of intracellular Ca2+ concentration in cancerous mammary cells (MMT060562) and in normal mammary cells treated with epidermal growth factor. Responses to injection of either D‐myo‐inositol‐1,4‐bisphosphate (IP2) or D‐myo‐inositol‐1,3,4,5‐tetrakisphosphate (IP4) were small or absent. Furthermore, normal mammary cells cultivated with low‐protein serum replacement alone or in the presence of differentiation‐inducing hormones (insulin + cortisol + prolactin) were less sensitive to IP3.Thapsigargin induced a transient increase of Ca2+ due to the release of Ca2+ from an intracellular pool. There was no difference in the peak heights of the thapsigargin‐induced Ca2+ increase when mammary cells were cultivated in the presence or absence of epidermal growth factor or insulin + cortisol + prolactin. These findings suggest that the releasable intracellular Ca2+ pool remained unchanged whereas sensitivity to IP3 increases during the proliferation stage.Mechanical stimulus of a mammary cell induces an increase of intracellular Ca2+ in the stimulated cell. A certain stimulating factor is released from the mechanically stimulated cell into the extracellular space, and it induces an increase of Ca2+ in surrounding cells.18 In contrast, the IP3‐induced Ca2+ increase in both cancerous and epidermal growth factor‐treated normal mammary cells did not spread to adjacent cells. Therefore, increase of Ca2+ is not sufficient to account for the release of stimulating substances from mammary cells in the mechanically‐induced spreading response.
9‐Hydroxybenfluron induced inhibition of proliferation and metabolism in hela cells
Authors: Jantovà S. , Horàkovà K. 
Published: May 2005

AbstractThe highest concentration of 9‐hydroxybenfluron (HBF) tested, namely 4·05 μmol1−1, induced immediate cytotoxic effects which were manifested by total inhibition of cell proliferation after only 24 h of culture. In a certain proportion of the cells cytolytic effects were observed at longer times of culture. Lower concentrations of HBF induced toxicity that was concentration‐ and time‐dependent.The toxic effect appeared to occur in two phases. Cells, which had lost their ability to divide, did not stop their metabolism in which glutamine was the main source of energy. The results suggest that HBF primarily interferes with one of the phases of the cell cycle and only secondarily influences energy processes. Because benfluron (BF) and HBF have similar effects, it is suggested that the cytotoxicity of BF can be ascribed to the influence of its metabolite, HBF.
Hexose metabolism in pancreatic islets: Succinate dehydrogenase activity in islet homogenates
Authors: Rasschaert Joanne , Malaisse Willy J. 
Published: May 2005

AbstractSuccinate dehydrogenase activity was measured in rat pancreatic islet homogenates incubated in the presence of [1,4‐14C]succinate, the reaction velocity being judged through the generation of 14CO2 in the auxiliary reactions catalysed by pig heart fumarase and chicken liver NADP‐malate dehydrogenase. In the presence of 1·0 mM succinate, the reaction velocity averaged 5·53 ± 0·44 pmol min−1 μg−1 islet protein. The Km for succinate was close to 0·4 mM and the enzymic activity was restricted to mitochondria. These kinetic results indicate that, under the present experimental conditions, the activity of succinate dehydrogenase does not vastly exceed that of either NAD‐isocitrate dehydrogenase or the 2‐ketoglutarate dehydrogenase complex, at least when the latter enzymes are activated by ADP and/or Ca2+. Nevertheless, the activity of succinate dehydrogenase is sufficient to account for the increase in O2 uptake evoked in intact islets by the monomethyl ester of succinic acid. It could become a rate‐limiting step of the Krebs cycle in models of B‐cell dysfunction.
Effect of diets containing adenosine, guanosine, inosine or xanthosine on the nucleotide content of Artemia. Influence of mycophenolic acid
Authors: Sillero Antonio , Sillero María A. Günther , Hernandorena Arantxa 
Published: May 2005

AbstractArtemia uses the stored diguanosine tetraphosphate as a source of adenine and guanine nucleotides during development from the encysted gastrula to the free swimming larva. Further development of the larvae depends on a dietary source of purine rings. We have investigated the growth of Artemia in axenic cultures supplemented with 0·6 mg ml−1 of adenosine, guanosine, inosine or xanthosine. The total protein and soluble nucleotide content of Artemia grown in the presence of adenosine, guanosine or inosine was very similar, around (2 A260 units and 500 mg protein) and (4 A260 units and 1000 mg protein) after 4 and 6 days of postlarval development, respectively. The nucleotide pattern of those extracts subjected to HPLC were almost identical, the major peaks corresponding to ATP, ADP and AMP. Other nucleotides, not well characterized, were also present in those extracts. Mycophenolic acid (10 μg ml−1) inhibited the growth of Artemia (as measured by their protein and soluble nucleotide content) in the presence of adenosine and inosine as the purine source, and had no appreciable effect in the presence of guanosine. A quantitative analysis of the chromatographic peaks obtained from Artemia grown in the presence of any of the three nucleosides ± mycophenolic acid showed that the effect of the antibiotic on each one of the chromatographic peaks was very similar, suggesting that Artemia, and probably other organisms as well, tend to maintain a balance between all nucleotides and to adjust the overall level to the limiting step(s) in their rates of synthesis/interconversion. Xanthosine was not able to support the development of Artemia.
Lectin binding and uptake and glycoprotein characterization of isolated porcine aortic endothelial and smooth muscle cells
Authors: Schumacher Udo , Vischer Peter , Völker Wolfgang , Engelmann Bernd 
Published: May 2005

AbstractEndothelial and smooth muscle cells were isolated from porcine aorta and kept in short‐term culture. To determine the terminal carbohydate composition of the plasma membranes from both cell populations, the cells were incubated with a panel of fluorescein‐labelled lectins. Both cell populations shared a number of terminal carbohydrates, but the N‐galactosamine specific lectin Wistaria floribunda agglutinin labelled only the endothelial cells. A lectin which selectively labelled smooth muscle cells was not found. Western blot analysis of isolated endothelial cell membrane glycoproteins indicated that most membrane glycoproteins are labelled by Wistaria floribunda agglutinin.
Modifications of proteoglycans produced by human skin fibroblast cultures during replicative senescence
Authors: Passi A. , Albertini R. , Bardoni A. , Rindi S. , Salvini R. , Pallavicini G. , De Luca G. 
Published: May 2005

AbstractThe properties of proteoglycans (PGs) produced by normal human skin fibroblast were investigated with increasing passage. The increase of subculture number was associated with a constant increase in PG molecular size, which was particularly evident in cell layer extracts. In the cell layer, the ratio of DS‐PGs/HS‐PGs was markedly higher in early passage cultures. Moreover, the cell layer from young cells contained lower amounts of radioactivity incorporated into the most hydrophobic PG populations, suggesting that the PG core protein might also undergo significant modification with increasing subcultures. There was no significant difference in energy charge value between early and late passage cultures, whereas the NAD/NADH ratio was found to decrease markedly in senescent cells.
Stimulation of phosphatidylcholine biosynthesis by hemicholinium‐3, a potent inhibitor of choline uptake in human leukemic monocyte‐like U937 cells
Authors: Chu Arthur J. 
Published: May 2005

AbstractThe effect of hemicholinium‐3 (HC‐3) on choline uptake and phosphatidylcholine (PC) biosynthesis was examined in human leukemic monocyte‐like U937 cells. HC‐3 inhibited [3H]choline uptake in a dose‐ and time‐dependent manner. After a 3 h treatment, HC‐3 (100 μM) decreased choline uptake by as much as 80 per cent (p < 0·0001; n = 4). Reduction of incorporation of label into PC was also detected in a dose‐dependent manner; the extent of inhibition, however, was always 10–20 per cent less than that observed in the total uptake. At 3 h HC‐3 decreased the incorporation into PC by 65 per cent (p < 0·0001; n = 5). Kinetic studies in vivo showed that HC‐3 inhibited total uptake and incorporation into PC differently, suggesting that the labelling of PC is not simply dictated by [3H]choline uptake. In separate experiments, cells were pretreated with 100 μM HC‐3 for 3 h. After washing, the inhibitory effect on total uptake was no longer observed, while a 20 per cent stimulation of the incorporation into PC was obtained in these pretreated cells. In pulse‐chase studies, the cells were prelabelled with [3H]choline for 30 min and chased with HC‐3 for up to 3 h; the results showed a significant stimulation of incorporation into PC in a longer chase with 100 μM HC‐3. After a 3 h treatment, the cytosolic CTP:cholinephosphate cytidylytransferase (CT) was activated by 56 per cent, while choline kinase (CK) was inhibited slightly. The stimulation of CT was not simply due to the intact HC‐3 molecule, and there was no redistribution of CT between cytosol and microsomes. Taken together, the results suggest that HC‐3 activates PC biosynthesis apart from the inhibitory effect on choline uptake.