bluuebunny/crossref_metadata_2025_split huggingface dataset:
Glucose and amino acid metabolism in neonatal rat skeletal muscle in tissue culture
Authors: Pardridge William M. , Duducgian‐Vartavarian Luiza , Casanello‐Ertl Delia , Jones Michael R. , Kopple Joel D. 
Published: February 2005

AbstractThe characteristics of glucose and amino acid metabolism over a 98‐hour incubation period were studied in a primary culture of neonatal rat skeletal muscle cells. The cells formed large myotubes in culture, were spontaneously highly contractile, and had cell phosphocreatine levels exceeding ATP concentrations. Medium glucose fell from 7.2±0.2 to 1.5±0.1 mM between 0 and 98 hours; intracellular glucose was readily detectable, indicating glycolysis was limited by phosphorylation, not glucose transport. Alanine levels in the medium increased from 0.06±0.01 to 0.82±0.04 mM between 0 and 48 hours and decreased to 0.72±0.04 mM by 98 hours. The period of net alanine production correlated with the rise in the cell mass action ratio of the alanine aminotransferase reaction. Cell aspartate, glutamate, and calculated oxalacetate levels were inversely related to the cell NADH/NAD+ ratio, as represented by the intracellular lactate/pyruvate ratio (r=0.78–0.88). The branched chain amino acids (leucine, isoleucine, valine) were actively utilized, e.g., medium leucine fell from 0.70±0.01 to 0.30±0.06 mM between 0 and 98 hours. In addition, arginine and serine consumption was observed in conjunction with ornithine, proline, and glycine production. Conclusions: (1) A major driving force for the high rates of alanine production by skeletal muscle cells in tissue culture is the active utilization of branched chain amino acids. (2) Intracellular aspartate and glutamate pools are linked, probably via the malate‐aspartate shuttle, to the cell NADH/NAD+ redox state. (3) Muscle cells in tissue culture metabolize significant amounts of arginine and serine in association with the production of ornithine and proline, and these pathways may possibly be related to creatine production.
Density‐dependent and adaptive regulation of glucose transport in primary cell cultures of the R3230AC rat mammary adenocarcinoma
Authors: Gay Roger J. , Hilf Russell 
Published: February 2005

AbstractTransport of 3‐O‐methyl‐(1‐3H)‐D‐glucose (3‐OMG) was studied in primary cell cultures of the R3230AC rat mammary adenocarcinoma. Fastest rates of carrier‐mediated 3‐OMG transport (vc) were temporally associated with fastest cell growth, as were the rates of 3H‐labeled thymidine, uridine, and leucine incorporation into macromolecules. The decrease in vc for 3‐OMG observed as cultured cells approached quiescence was due to a 4‐fold decrease in Vmax with the Km remaining relatively constant (4–9mM). Provided adequate time was allowed for cells to adapt, (6–12hr), the vc for 3‐OMG transport was found to be inversely related to the concentration of glucose in the medium. Within 6 hours after switching cells from standard growth medium (5mM glucose) to medium containing no glucose (5 mM fructose), a 2‐fold increase in vc for 3‐OMG transport was observed in both fast and slow growing cells. The glucose‐starvation induced increase in 3‐OMG transport was due to an increase in Vmax; the Km remained constant, and was not significantly influenced by the presence of serum (10%) or insulin (5 m̈g/ml) or by [5 mM] galactose, mannose, fructose, 2‐deoxy‐D‐glucose, 3‐OMG, or mannitol. Readdition of glucose (5 mM) to transport‐activated cells (deprived of glucose for 9–11 hr) resulted in a rapid return of 3‐OMG transport to basal levels. In the presence of cycloheximide (10 m̈g/ml) or actinomycin D (10 m̈g/ml), this glucose‐induced decline in carrier function was largely blocked. In fast‐growing cells, the addition of either of these inhibitors, in the presence or absence of glucose, resulted in an initial rise in the rates of 3‐OMG transport, followed by a linear decrease. Compared to fast‐growing cells, the cycloheximide‐induced increase in 3‐OMG transport was greater and longer sustained in slow‐growing cells. Regardless of their growth rate, cell cultures preincubated in medium containing glucose and cycloheximide exhibited decreases in 3‐OMG transport when transferred to medium containing fructose, with or without actinomycin D. Slow‐growing cells preincubated in medium containing fructose and cycloheximide exhibited an increase in 3‐OMG transport when switched to medium containing fructose, whereas similarly treated fast growing cell cultures displayed a slight decrease. These experiments suggest that the adaptive regulation of glucose transport in these mammary tumor cell cultures occurred at the transcriptional level and was influenced by the rates of cellular growth. A model in which a metabolite of glucose acts to enhance the synthesis or stabilization of a mRNA species specific for a putative carrier inactivator protein is proposed.
The effect of mouse lung granulocyte‐macrophage colony‐stimulating factor and other colony‐stimulating activities on the proliferation and differentiation of murine bone marrow cells in long‐term cultures
Authors: Williams Neil , Burgess Antony W. 
Published: February 2005

AbstractThe roles of colony‐stimulating factors in long‐term bone marrow cultures were studied and compared. After single additions of high concentrations of unpurified colony‐stimulating activities to the cultures, rapid deterioration of the cultures was observed. This appears to result from contaminants in the stimulatory preparations. Cultures to which one purified colony‐stimulating factor (CSF) from endotoxin mouse lung‐conditioned medium was added did not run down ten weeks after addition and were found to be the same as the controls. The deterioration of the cultures to which unpurified stimulators were added could not be accounted for by accelerated granulopoiesis leading to subsequent exhaustion of the cultures. The inability of purified CSF to affect the cellularity of the suspension cells did not result from instability or masking of the activity in the cultures, nor did CSF preferentially stimulate the cells within the adherent layer. The suspension cells responded to purified CSF after separation from the adherent cells. The data suggest that if CSFs are marrow stimulators, their effects in turn may be stringently regulated within the marrow.
Inhibitors of RNA synthesis and passage of chick embryo fibroblasts through the G1 period
Authors: Chadwick David E. , Ignotz George G. , Ignotz Ronald A. , Lieberman Irving 
Published: February 2005

AbstractEvents that are essential for progression through the G1 period begin immediately or shortly after resting chick embryo cells are given fresh medium with serum. The following observations support the contention that the critical events include the production of non‐ribosomal RNAs: (1) Addition to the “shift‐up” medium of either of two inhibitors of RNA formation, comptothecin or 5, 6‐dichloro−1‐β‐D‐ribofuranosylbenzimidazole, delays the onset of DNA replication by about the length of time the cells are exposed to the drugs. (2) Although entry into the S phase is delayed by the inhibitors, the slopes of the DNA response curves are identical to that of control cultures. (3) Neither drug reduces significantly the rate of overall protein synthesis. Observations (2) and (3) are taken to mean that expansion of the G1 period is not due to cell damage. (4) A third inhibitor of RNA synthesis, cordycepin, also delays passage of stimulated cells throgh the G1 phase, but, in this case, the length of the delay period is greater than that of the exposure period. (5) A low dose of actinomycin D does not impede movement towards the S phase, even though the synthesis of preribosomal RNA is considerably reduced.The possibility is considered that the essential G1 molecules are mRNAs.
The permeability of the human red cell to deuterium oxide (heavy water)
Authors: Karan Daniel M. , Macey Robert I. 
Published: February 2005

AbstractUsing a stopped‐flow device, the osmotic water permeability of human red cells to D2O and H2O was studied as a function of temperature and under the influence of the sulfhydryl reagent paracholoromercuribenzene sulfonic acid (PCMBS), an inhibitor of water transport. The ratio, permeability (D2O)/permeability (H2O) at each temperature can be predicted simply by assuming that permeability varies inversely with macroscopic viscosity. When water permeability is inhibited with PCMBS, this dependency on viscosity vanishes; the inhibited permeabilities in D2O and H2O are indistinguishable.
Patterns of chromosome segregation in chinese hamster × mouse cell hybrids between permanent cell lines and thymus cells
Authors: Lasserre Chantal , Jami Jacques , Aviles Dominique 
Published: February 2005

AbstractHybrids between a tumorigenic Chinese hamster cell line (DC3F‐aza) and normal mouse thymus cells very rapidly lost most of their mouse chromosomes, whereas hybrids between tumorigenic mouse cell lines (either Cl.1D of L cell line origin, or PCC4‐aza1 teratocarcinoma cells) and normal Chinese hamster thymus cells lost most of their hamster chromosomes. From three such fusion experiments, 20 cell lines were developed which all followed the same evolution, namely, the elimination of the majority of the chromosomes contributed by the normal thymus cell. In some hybrids, the elimination process resulted in the total absence of intact chromosomes contributed by the thymus cell parent. Such hybrids were distinguished from revertant parental cells growing in the selective hybrids were distinguished from revertant parental cells growing in the selective medium by the presence of at least one enzyme in their cell extracts which displayed the electrophoretic mobility of the enzyme of the thymus cell parent. These observations, together with data from other reports, suggest that, as a rule, interspecific cell hybrids which develop upon fusion between normal diploid cells and tumorigenic cell lines maintain the chromosomes of the latter and eliminate preferentially many or most of the chromosomes contributed by the normal cell parents, independent of the respective species of the parental cells.
The responses of hemopoietic precursor cells in mice to bacterial cell‐wall components
Authors: Staber Fritz G. , Johnson Gregory R. 
Published: February 2005

AbstractThe influence upon differnt cellular and humoral parameters of hemopoiesis of three structurally unrelated, highly purified bacterial cell‐wall components (BCWC) was investigated. The spleens of C57BL/6 mice assayed 6 days after the injection of either lipid A or outer‐membrane lipoportein, but not murein, showed a marked increase in granulocyte‐macrophage, eosinophil, and megakaryocyte progenitor cell levels. The number of pluripotent hemopoietic stem cells (CFU‐S) also increased in the spleens of mice treated with either lipid A or lipoprotein. Similar results were obtained following the injection of lipoprotein or lipid A into CBA or C57BL/6.nu mice. Genetically anemic Wf/Wf mice were found to have spontaneously elevated numbers of splenic progenitor cells, which increased further after the injection of lipid A. The proportions of the different splenic progenitor cell types were similar in both untreated and lipid A treated Wf/Wf mice, and in normal littermate controls.When tested in vitro, unfractionated or partially purified post‐lipid A serum was found to stimulate the growth of granulocyte‐macrophage progenitor cells (GM‐CFC), but no detectable stimulation of eosinohphil, megakryocyte, or erythroid progenitor cells was observed. The data suggest that the rise in splenic levels of the different progenitor cells is not mediated by the corresponding types of CSF, but more likely by proliferation and differentiation of CFU‐S.
Tumor promoter modulation of epidermal growth factor‐ and nerve growth factor‐induced adhesion and growth factor binding of PC‐12 pheochromocytoma cells
Authors: Chandler Charles E. , Herschman Harvey R. 
Published: February 2005

AbstractNerve growth factor (NGF) has previously been shown to increase the rate of adhesion of PC‐12 pheochromocytoma cells to cell culture dishes. This increase in the rate of adhesion was postulated to be important in NGF‐mediated neurite outgrowth. We now report that epidermal growth factor (EGF) is also able to increase the rate of adhesion of PC‐12 cells to cell culture dishes, but does not elicit neurite outgrowth. The dose‐response curve for EGF is bell‐shaped, in contrast to the more classically shaped dose‐response curve obtained with NGF.Tetradecanoyl‐phorbol‐acetate (TPA), a potent tumor promoter, blocks the EGF‐induced increase in adhesion rate of PC‐12 cells, but does not alter the NGF‐induced increase in adhesion rate. TPA shifts the EGF binding curve to the right for PC‐12 cells, but does not alter maximal EGF binding at saturating concentrations of EGF. The binding of NGF to PC‐12 cells is not affected by TPA. NGF‐induced neurite formation by PC‐12 cells is unaffected by TPA, in contrast to the previously reported delay of neurite outgrowth of serum‐deprived neuroblastoma cells and NGF‐exposed chick embryonic ganglia cells.NGF and EGF both cause a decrease in the number of short microvilli and an increase in the number of long microvilli on PC‐12 cells. TPA blocks the decrease in the number of short microvilli in EGF‐treated cells, but not in NGF‐treated cells. Long microvilli formation is blocked by TPA in both conditions, suggesting the latter are not involved in the increased adhesion rates.
Phorbol myristate acetate induced neutrophil autotoxicity
Authors: Tsan Min‐Fu 
Published: February 2005

AbstractThe viability of neutrophils in the condition under which they kill neoplastic cells was studied. In the presence of phorbol myristate acetate (PMA) the 51Cr‐release by human neutrophils was markedly stimulated. The PMA‐induced 51Cr‐release by neutrophils correlated well with the number of nonviable neutrophils as determined by the uptake of trypan blue. Phorbol myristate acetate had no effect on the 51Cr‐release by lymphocytes, LPC‐1 myeloma cells, ovarian ascites tumor cells, or neutrophils from a patient with chronic granulomatous disease. This suggests that the effect of PMA is not due to its nonspecific toxic effect; instead, it is dependent on the reactive oxygen species produced by the normal neutrophils. Catalase, cytochrome C, histidine, and methionine inhibited the PMA‐induced 51Cr‐release by human neutrophils, whereas superoxide dismutase, myeloperoxidase inhibitors, and some hydroxyl radical scavengers or singlet oxygen quenchers had no effect. The clumping of neutrophils induced by PMA was also important in the PMA‐induced 51Cr‐release by human neutrophils.
Effect of arachidonic acid and the chemotactic factor F‐Met‐Leu‐Phe on cation transport in rabbit neutrophils
Authors: Sha'Afi R. I. , Naccache P. H. , Alobaidi T. , Molski T. F. P. , Volpi M. 
Published: February 2005

AbstractA detailed examination of the effects of exogenous arachidonate on cation metabolism in rabbit neutrophils was undertaken. Arachidonic acid stimulates the movement of 45Ca into and out of the neutrophils with a net result, in the presence of extracellular calcium, of increasing the steady‐state level of 45Ca. Arachidonate also increases the uptake of 22Na. These effects of arachidonate are specific to these cations, concentration‐dependent, and sensitive to lipoxygenase inhibitors. At the concentrations used in this study arachidonate does not influence the permeability of human erythrocytes to 45Ca. Furthermore, both arachidonic acid and F‐Met‐Leu‐Phe release calcium from a previously unexchangeable intracellular pool and the effect of the two stimuli are not additive. Arachidonic acid‐dependent, but not F‐Met‐Leu‐Phe‐dependent, calcium release is sensitive to lipoxygenase inhibitors. These two stimuli thus appear to release is sensitive to lipoxygenase inhibitors. These two stimuli thus appear to release calcium from the same pool(s) by separate mechanisms. The results summarized above are consistent with the hypothesis that one or more arachidonate metabolites are involved in the mechanism underlying the chemotactic factor induced permeability changes in rabbit neutrophils.
N‐Carbamoyloxyurea‐resistant Chinese hamster ovary cells with elevated levels of ribonucleotide reductase activity
Authors: Hards Robert G. , Wright Jim A. 
Published: February 2005

AbstractWe describe the isolation and characterization of a Chinese hamster ovary cell line selected for resistance to N‐carbamoyloxyurea. Using the mammalian cell permeabilization assay developed in our laboratory, a detailed analysis of the target enzyme, ribonucleotide reductase (EC 1.17.4.1), was carried out. Both drug‐resistant and parental wild‐type cells required the same optimum conditions for enzyme activity. The Ki values for N‐carbamoyloxyurea inhibition of CDP reduction were 2.0 mM for NCR‐30A cells and 2.3 mM for wild‐type cells, while the Ki value for ADP reduction was 2.3 mM for both cell lines. Although the Ki values remained essentially unchanged, the Vmax values for NCR‐30A cells were 1.01 nmoles dCDP formed/5 × 106 cells/hour and 1.83 nmoles dADP/5 × 106 cells/hour, while those for the wild‐type cells were 0.49 nmoles dCDP produced/5 × 106 cells/hour and 1.00 nmoles dADP/5 × 106 cells/hour. This approximate twofold increase in reductase activity at least partially accounts for a 2.6‐fold increase in D10 value for cellular resistance to N‐carbamoyloxyurea exhibited by NCR‐30A cells. The NCR‐30A cell line was also cross‐resistant to the antitumor agents, hydroxyurea and guanazole. No differences in Ki values for inhibition of CDP and ADP reduction by these two drugs were detected and cellular resistance could be entirely accounted for by the elevation in activity of the reductase in the NCR‐30A cell line. The properties of N‐carbamoyloxyurea‐resistance cells indicate they should be useful for further investigations into the regulation of mammalian enzyme activity.
Methionine utilization in long‐term human lymphoid cell lines
Authors: Guarini L. , Sturman J. A. , Gaull G. E. , Beratis N. G. 
Published: February 2005

AbstractLong‐term lymphoid cell lines (LTL) cultured under normal conditions use methionine primarily for protein synthesis, although a significant proportion is converted to S‐adenosylmethionine (SAM) and used for synthesis of the polyamines, spermidine, and spermine. When LTL are cultured under conditions of high cell density, there is an initial phase of rapid protein synthesis and accumulation of SAM as found under normal culture conditions, but this soon ceases. Polyamine synthesis is small under these conditions, despite the presence of relatively large amounts of SAM.
The production and localization of laminin in cultured vascular and corneal endothelial cells
Authors: Gospodarowicz D. , Greenburg G. , Foidart J. M. , Savion N. 
Published: February 2005

AbstractThe production and localization of laminin, as a function of cell density (sparse versus confluent cultures) and growth stage (actively growing versus resting cultures), has been compared on the cell surfaces of cultured vascular and corneal endothelial cells. Comparison of the abilities of the two types of cells to secrete laminin and fibronectin into their incubation medium reveals that vascular endothelial cells can secrete 20‐fold as much laminin as can corneal endothelial cells. In contrast, both cell types produce comparable amounts of fibronectin. Furthermore, if one compares the secretion of laminin and fibronectin as a function of cell growth, it appears that the laminin released into the medium by either vascular or corneal endothelial cells, is a function of cell density and cell growth, since this release is most pronounced when the cells are sparse and actively growing, and decreases by 10‐ and 30‐fold, respectively, when either vascular or corneal endothelial cell cultures become confluent. With regard to fibronectin secretion, no such variation can be seen with vascular endothelial cell cultures, regardless of whether they are sparse and actively growing or confluent and resting. Corneal endothelial cell cultures, demonstrated a twofold increase in fibronectin production when they were confluent and resting as compared to when they were sparse and actively growing. When the distribution of laminin versus fibronectin within the apical and basal cell surfaces of cultured corneal and vascular endothelial cells is compared, one can observe that unlike fibronectin, which in sparse and subconfluent cultures can be seen to be associated with both the apical cell surface. In confluent cultures, laminin can be found associated primarily with the extracellular matrix beneath the cell monolayer, where it codistributes with type IV collagen.
Effect of glucose on aspartate and glutamate synthesis by human diploid fibroblasts
Authors: Zielke H. Ronald , Sumbilla Carlota M. , Ozand Pinar T. 
Published: February 2005

AbstractThe quantity of aspartate, but not of glutamate, synthesized by human diploid fibroblasts (HDF) was inversely proportional to the glucose concentration. Forty hours after confluent cells were refed with media containing 1.5 mM or 55 μM glucose, the aspartate concentration was 8 μM in medium high in glucose and 28 μM in medium low in glucose; glutamate was 350 μM at both glucose levels. The label incorporation from [U‐14C] glutamine (0.8 C/ml) into aspartate after 40 hours in 1.5 mM glucose medium was less than 1000 DPM/ml and into glutamate 540,000 DPM/ml. The respective label incorporation into aspartate in 55 μM glucose medium was 118,000 DPM/ml and into glutamate 450,000 DPM/ml. In media with 1.5 mM glucose, label incorporation into both aspartate and glutamate was observed from [6‐14C] glucose, [3‐14C] pyruvate, and [1‐14C] pyruvate. Since [1‐14C] pyruvate labeled aspartate in 1.5 mM glucose medium, whereas [U‐14C] glutamine did not, the observations support a cystolic pathway of aspartate synthesis from glycolytic intermediates in the presence of glucose. However, when the glucose concentration is decreased, glutamine appears to be the primary carbon source for aspartate synthesis. Therefore, both the quantity and the pathway of aspartate synthesis in HDF are functions of the glucose concentration. It is postulated that increased accumulation of aspartate in the media of HDF at confluency may be explained by decreased availability of acetyl CoA or of NADH.
Gonadotropin stimulation of pregnenolone metabolism in Chinese Hamster Ovary cells in culture
Authors: Evain Daniele , Anderson Wayne B. , Saez Jose M. 
Published: February 2005

AbstractTo determine if Chinese Hamster Ovary (CHO) cells in culture are able to metabolize steroids, CHO cells were incubated in defined medium with [14C]pregnenolone. As shown, [14C]pregnenolone is metabolized to progesterone and other δ53β steroids; this steroidogenic response is appreciably enhanced upon exposure of the cells to 50 nM gonadotropins (human chorionic gonadotropin and follicle‐stimulating hormone). The primary metabolites that accumulate in the medium upon treatment with gonadotropins are 16α‐17β‐dihydroxydehydroepiandrosterone. Exposure of the CHO cells to gonadotropins induces significant increases in the activities of 16α‐hydroxylase, 17α‐hydroxylase, and 17–20 lyase. Similar results are obtained when the CHO cells are treated with 0.1 mM 8‐bromocyclic AMP, indicating that the gonadotropin enhancement of steroid metabolism is a cyclic AMP‐mediated process. CHO cells apparently lack the cholesterol desmolase complex since 14C‐cholesterol is not utilized by these cells to produce other steroid metabolites. These results indicate that CHO cells offer an in vitro system for the study of certain aspects of gonadotropin stimulation of steroidogenesis.