bluuebunny/crossref_metadata_2025_split huggingface dataset:
The regulation of mononuclear phagocyte entry into S phase by the colony stimulating factor CSF‐1
Authors: Tushinski Robert J. , Stanley E. Richard 
Published: February 2005

AbstractCSF‐1 is a hemopoietic growth factor that specifically regulates the survival, proliferation, and differentiation of mononuclear phagocytic cells. Populations of adherent bone marrow‐derived macrophages (BMM) devoid of CSF‐1 producing cells were used to study regulation by CSF‐1 of macrophage entry into S phase. More than 95% of BMM possess the CSF‐1 receptor. It was shown that 93–98% of BMM are cycling (S phase 8–9 hr, doubling time 24–28 hr) when cultured in the presence of CSF‐1. BMM incubated with 15% FCS in the absence of CSF‐1 or in the presence of CSF‐1 concentrations inducing survival without proliferation enter a quiescent state. This state is characterized by a reduction in the synthesis of DNA (98%), total protein (35%), ribosomal protein (76%), and histone (96%) compared with the synthetic rate of these components in exponentially growing cells. Addition of CSF‐1 to BMM rendered quiescent by removal of CSF‐1 stimulated entry into S phase with a lag period of ∼12 h. This lag period is reduced to 8 hr in BMM made quiescent at concentrations of CSF‐1 inducing survival without proliferation, an effect which may be related to the expected higher protein content of these cells (Tushinski and Stanley, J. Cell. Physiol., 116:67–75). Neutralization of CSF‐1 by antibody at different times during the lag period indicates that CSF‐1 is required for almost the entire lag period for the entry of any cells into S phase. In BMM rendered quiescent by removal of both serum and CSF‐1, purified CSF‐1 without serum stimulated entry of cells into S phase, whereas serum alone was ineffective. The results are consistent with a primary regulatory role of CSF‐1 in mononuclear phagocyte proliferation, survival, and function.
Synergism between hemopoietic growth factors (HGFs) detected by their effects on cells bearing receptors for a lineage specific HGF: Assay of hemopoietin‐1
Authors: Bartelmez S. H. , Stanley E. Richard 
Published: February 2005

AbstractThe preceding paper describes a new approach to the detection and assay of growth factors for developmentally early multipotent hemopoietic cells (Bartelmez et al., J. Cell. Physiol., 1985). This approach, involving measurement of the increase in the number of receptors for the mononuclear phagocyte specific hemopoietic growth factor (HGF), colony stimulating factor‐1 (CSF‐1), in cultures of developmentally early murine cells incubated with putative HGFs, has been used to define and assay hemopoietin‐1. Hemopoietin‐1 (Mr ∼ 20,000) is found in the medium derived from serum‐free cultures of cells of the human urinary bladder carcinoma line 5637. In contrast to both hemopoietin‐2 and CSF‐1, which also stimulate an increase in CSF‐1 receptor numbers in cultures of developmentally early hemopoietic cells, hemopoietin‐1 alone has no detectable effect. However, hemopoietin‐1 exhibits dramatic synergism wth CSF‐1. In the presence of CSF‐1, hemopoietin‐1 stimulates the proliferation of developmentally earlier cells than those that respond to either CSF‐1 alone or hemopoietin‐2 alone or their combination. These cells proliferate for at least 3 days with no alteration of the average CSF‐1 receptor density. However, by 5 days of incubation, the progeny of developmentally early hemopoietic cells that have proliferated in response to hemopoietin‐1 + CSF‐1 exhibit an approximately tenfold increase in the average CSF‐1 receptor density per cell, which immediately precedes their differentiation to adherent mononuclear phagocytes. As hemopoietin‐1 does not possess colony stimulating or burst promoting activities for murine bone marrow cells, but acts on multipotent hemopoietic cells, the analysis of the mechanism of its synergistic effects with HGFs such as CSF‐1 are of special relevance to the regulation of early events in hemopoiesis.
Selenium deficiency in cultured adrenocortical cells: Restoration of glutathione peroxidase and resistance to hydroperoxides on addition of selenium
Authors: Hornsby Peter J. , Pearson Doran W. , Autor Anne P. , Aldern Kathy A. , Harris Sandra E. 
Published: February 2005

AbstractCultured bovine adrenocortical cells were previously shown to be functionally deficient in selenium and vitamin E when grown in medium supplemented with fetal bovine serum. In the present experiments, the lack of significant bioavailable amounts of selenium in the medium was demonstrated by the finding of only low levels of glutathione peroxidase in the cultured cells (0.008 U/mg protein compared with 0.045 U/mg protein in fresh adrenocortical tissue). When 20 nM selenium as selenite was added to the cultured adrenocortical cells, glutathione peroxidase activity increased continuously over 72 h, with a total increase of about eightfold over this period. Over the same time‐course, the highest concentration of cumene hydroperoxide tolerated by the cells without cell death increased progressively from 10 μM to 50 μM. Addition of 1μM α‐tocopherol also increased the amount of cumene hydroperoxide tolerated to 50 μM. Cell death was measured by cloning efficiency after removal of cumene hydroperoxide. Addition of either selenium or α‐tocopherol had little effect on the growth rate of the cells over six passages, even when residual vitamin E was removed from the serum by extraction with ether and residual low molecular weight selenium compounds were removed by dialysis. It is concluded that combined deficiency of selenium and vitamin E, at least in the presence of other components of fetal bovine serum, has little effect on the ability of the cells to survive under normal conditions, as evidenced by continued long‐term proliferation. However, the low levels of glutathione peroxidase resulting from selenium deficiency cause an increase susceptibility to peroxide‐mediated toxicity. The combined deficiency of selenium and vitamin E impairs the ability of cells to survive under adverse conditions, as well as altering mitochondrial functions, as previously demonstrated.
Utilization and formation of amino acids by chicken epiphyseal chondrocytes: Comparative studies with cultured cells and native cartilage tissue
Authors: Ishikawa Yoshinori , Chin J. E. , Hubbard H. Lee , Wuthier Roy E. 
Published: February 2005

AbstractUtilization and production of amino acids by primary cultures of chicken growth plate epiphyseal chondrocytes grown in Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum were investigated in both short‐term (6–72 h) and long‐term (3–24 day) cultures. Comparative studies were made on levels of free amino acids in chicken blood plasma and serum, and in extracellular fluids from different regions of growth plate cartilage and from two types of muscle. Chondrocytes rapidly consumed glutamine from the medium, and to lesser extents, various other amino acids. In contrast, free ammonia, alanine, glycine, glutamate, proline, and aspartate were released into the medium. The utilization of certain amino acids changed, depending on the stage of culture. Initially glutamate was released into the medium but after confluency was consumed. Conversely, histidine, lysine, and phenylalanine were initially utilized but later were released into the medium. Levels of total free amino acids in extracellular fluids of cartilage and muscle were higher than those in plasma and serum, while in cartilage the levels increased progressively from the resting to the hypertrophic zones. In these sequential regions certain amino acids increased proportionally, whereas others decreased. These interrelationships generally correlated closely with metabolism of amino acids by the cultured chondrocytes. They indicate that significant differences in amino acid metabolism exist between tissue areas and are reflected in the extracellular fluid composition. Accordingly, adjustment of specific amino acids may optimize culture conditions, enabling more normal phenotypic expression in vitro.
Analysis of a mutant expressing temperature‐sensitive changes of cell size in Tetrahymena
Authors: Palissa Harriet , Seyfert Hans‐Martin , Cleffmann Günter 
Published: February 2005

AbstractA temperature‐sensitive mutant of Tetrahymena expresses an increase in cell volume by a factor of 2.5 upon shift to restrictive temperature. Cellular amounts of protein, RNA, and DNA increase at roughly the same proportions. The mutant cell size is attained by cessation of divisions immediately after temperature shift for a period of time which is about equal to one generation time. During this time cell growth and DNA replication continue at virtually unchanged rates. Maintained at the restrictive temperature the mutant cells divide at the same rate as the wild‐type cells. Upon return to the permissive temperature, cell size is reduced by the combined effects of an accelerated division rate together with a decelerated growth rate.
Retinoids antagonize the induction of ornithine decarboxylase activity by phorbol esters and phospholipase C in rat tracheal epithelial cells
Authors: Jetten Anton M. , Shirley Jill E. 
Published: February 2005

AbstractIn this study we examined the action of phorbol esters, several phospholipases and retinoids on the induction of ornithine decarboxylase (ODC) activity in rat tracheal epithelial cells. 12‐O‐Tetradecanoylphorbol‐13‐acetate (TPA) induces ODC activity in these cells in a dose‐and time‐dependent manner. This induction is inhibited by cycloheximide indicating a requirement for protein synthesis. Tracheal epithelial 2C5 cells contain two binding sites for phorbol esters, one with a high affinity KD,1 = 4.58 nM and one with a low affinity KD,2 = 344.8 nM. The ability of several phorbol esters to induce ODC correlates well with the described efficacy with which they bind to the receptor and is in agreement with the concept that phorbol ester receptors are involved in the induction of ODC. There is strong evidence that the phorbol ester receptor is the protein kinase C for which diacylglycerol is the physiological ligand. Treatment of cells with phospholipase C generates diacylglycerol and induces ODC activity in a dose‐ and time‐dependent manner. Treatment with phospholipase A2 or D has no effect on ODC activity. These results support the concept that activation of protein kinase C is related to the induction of ODC activity. The induction of ODC by TPA as well as by phospholipase C is inhibited by retinoids. Specific cytosolic binding proteins for retinoids might be involved in at least some of the responses to these compounds. To examine whether the binding proteins are involved in the inhibition of ODC we determined the presence of these binding proteins and the structure‐activity relationship of retinoids. Both retinol and retinoic acid‐binding proteins can be detected in 2C5 cells, their levels are 1.06 and 3.36 pmoles/mg protein, respectively. The ability of several retinoids to inhibit ODC induction correlates well with their binding activity and support a role for these binding proteins in the action of retinoids on ODC induction.
Transport by the (Na+, K+) ATPase: Modulation by differentiation inducers and inhibition of protein synthesis in the MDCK kidney epithelial cell line
Authors: Kennedy Brian G. , Lever Julia E. 
Published: February 2005

AbstractMDCK kidney epithelial cell cultures exposed to the differentiation inducer hexamethylene bisacetamid (HMBA) for 24 hours exhibited a 50% decrease in transport activity per (Na+, K+)‐ATPase molecule (turnover number) but an unchanged number of pump sites (Kennedy and Lever, 1984). Inhibition of protein synthesis by either 10 μM cycloheximide or 2 μM emetine blocked the inhibitory effects of HMBA on Na+/K+ pump efficiency assessed by measurements of [3H]‐ouabain binding to intact cells, (Na+, K+) ATPase activity of detergent‐activated cell extracts, and ouabain‐sensitive Rb+ uptake. In the absence of inducer treatment, inhibition of protein synthesis increased Na+/K+ pump turnover number by twofold while maintaining Na+/K+ pump activity per cell at a constant level. Intracellular Na+ levels were decreased after cycloheximide treatment; therefore, pump stimulation was not due to substrate effects. Furthermore, cycloheximide effects of Rb+ uptake could be dissociated from effects on tight junctions. These observations suggest that the transport activity of the (Na+, K+) ATPase is tightly regulated by factors dependent on protein synthesis.
Variable expression of Qa‐m7, Qa‐m8, and Qa‐m9 antigenic determinants on primitive hemopoietic precursor cells
Authors: Harris R. A. , Sandrin M. S. , Sutton V. R. , Hogarth P. M. , McKenzie I. F. C. , Penington D. G. 
Published: February 2005

AbstractUsing monoclonal antibodies, we have analysed the distribution of three recently described Qa antigenic determinants (Qa‐m7, Qa‐m8 and Qa‐m9) on murine clonable hemopoietic progenitor cells and spleen colony‐forming units (CFU‐S). Cytotoxicity experiments showed that Qa‐m7 was expressed on almost all the progenitor cells (colony‐forming cells, CFC) of megakaryocytes (MEG‐CFC), erythroid cells (E‐CFC), B lymphocytes (BL‐CFC), and mixed colonies (MIX‐CFC) as well as day 13 CFU‐S, and a major proportion of granulocyte‐macrophage colony‐forming cells (GM‐CFC) and day 8 CFU‐S. Experiments using four sources of granulocyte‐macrophage colony‐stimulating activity suggested differential expression of Qa‐m7 on subpopulations of GM‐CFC, those preferentially forming macrophage colonies having lowest Qa‐m7 antigen density. Immune rosetting techniques demonstrated the selective expression of Qa‐m8 on approximately 50% of MEG‐CFC, MIX‐CFC and day 13 CFU‐S, a pattern similar to that of Qa‐m2. In contrast, Qa‐m9 was not detected on any of the primitive hemopoietic precursors assayed. The results demonstrate the complexity of the Qa antigenic system, and suggest a possible role for these antigens in hemopoietic differentiation.
Two distinct mechanisms for the interaction of cells with fibronectin substrata
Authors: Schwarz M. A. , Juliano R. L. 
Published: February 2005

AbstractFibronectin (Fn) was adsorbed onto neutral, sulfonated, imine‐conjugated or gelatin coated polystyrene latex beads. In all cases, the Fn coated beads bound effectively to Chinese hamster ovary (CHO) cells in suspension. However, the binding of Fn coated neutral or positively charged imine conjugated bead was inhibited by low concentrations of heparin or heparan sulfate or by treatment of the cells with Flavobacterium heparanase. By contrast, binding of Fn coated sulfonated or gelatin beads was insensitive to inhibition by heparin and to heparanase treatment of cells. Adhesion of CHO cells to Fn coated tissue culture plastic was not sensitive to heparin, whereas adhesion of CHO cells to Fn‐coated imine‐conjugated plastic was sensitive to heparin. These observations imply that the functional status of Fn can be modulated by the nature of the surface to which the Fn is adsorbed. They further imply that, under some circumstances, the heparin/heparan sulfate binding domains of Fn can play a role in the attachment of Fn to the cell membrane via membrane proteoglycans. Under other circumstances, the interaction of Fn with the cell may primarily involve other receptors for Fn, presumably cell surface glycoproteins.
Production of insulin‐like growth factor‐II (MSA) by endoderm‐like cells derived from embryonal carcinoma cells: Possible mediator of embryonic cell growth
Authors: Nagarajan Lalitha , Anderson Wayne B. , Nissley S. Peter , Rechler Matthew M. , Jetten Anton M. 
Published: February 2005

AbstractThe present study was carried out to determine if an insulin‐like growth factor (IGF) type activity might be produced by embryonal carcinoma‐derived cells. The cell line used to condition growth medium for the isolation of secreted growth factors was a newly established Dif 5 cell type. Dif 5 cells are a differentiated endoderm‐like cell type derived from F9 embryonal carcinoma cells (which possess properties similar to mouse embryonic stem cells) following extensive exposure to retinoic acid. When growth medium conditioned by Dif 5 cells is chromatographed on Sephadex G‐75 in 1 M acetic acid two peaks of activity are observed which compete for specific [125I]iodo multiplication stimulating activity (MSA) binding to PYS cells. MSA is the rat homologue of human IGF‐II. The high molecular weight fraction (Mr ˜ 60K) apparently corresponds to IGF‐binding protein as determined by its ability to bind [125I]iodo‐MSA. The low molecular weight fraction (Mr ˜ 8K) is biologically active as this fraction stimulates [3H]thymidine incorporation into serum‐starved chick embryo fibroblasts. Radioimmunoassay data indicate that the IGF‐like activity produced by Dif 5 cells is more closely related to IGF‐II than to IGF‐I. Undifferentiated embryonal carcinoma stem cell lines (F9, Nulli, and PCC4) produced little of this MSA‐like activity, while PYS‐2 (parietal endoderm‐like) cells produced about 16 ng MSA/106 cells/24 hr as determined by radioimmunoassay. Dif 5 and PSA‐5E (visceral endoderm‐like) cells, are found to secrete significant amounts of MSA into the growth medium (30–50 ng MSA/106 cells/24 hr). These findings offer further support to a proposal that MSA (IGF‐II) produced by endoderm cells, particularly visceral endoderm, may serve as an early embryonic growth factor.
Residual inhibition of epidermal growth factor binding by pancreatic secretagogues and phorbol ester in rat pancreas
Authors: Korc Murray , Magun Bruce E. 
Published: February 2005

AbstractCholecystokinin‐octapeptide (CCK8) inhibits 125I‐labeled epidermal growth factor (EGF) cell‐associated radioactivity in pancreatic acini, ostensibly as a result of its ability to mobilize cellular Ca2+. The phorbol ester tetradecanoyl phorbol acetate (TPA), a compound that activates protein kinase C, mimics the inhibitory action of CCK8. In the present study we examined the relationship between occupancy of the cholecystokinin (CCK) receptor, the subsequent inhibition of EGF binding, and the potential role of C‐kinase activation in mediating this inhibition. Proglumide and dibutyryl cyclic GMP (dbGMP), two distinct competitive antagonists of CCK8, reversed the inhibitory actions of CCK8. Analysis of steady‐state saturation kinetics of 125I‐EGF binding indicated that CCK8 decreased the apparent affinity of the EGF receptor, mainly as a result of a marked decrease in the amount of internalized ligand. TPA also inhibited 125I‐EGF internalization. Removal of CCK8 and TPA from incubation medium did not abolish their inhibitory actions. Carbachol, but not bombesin, exerted a similar residual inhibitory effect. It is suggested that in addition to acting via Ca2+, certain pancreatic secretagogues may also act through C‐kinase to regulate EGF binding.
Phosphate uptake by primary renal proximal tubule cell cultures grown in hormonally defined medium
Authors: Waqar M. Anwar , Seto Janny , Chung Soon Dong , Hiller‐Grohol Sue , Taub Mary 
Published: February 2005

AbstractThe uptake of labeied inorganic phosphate into primary rabbit kidney proximal tubule cells has been examined. Phosphate was accumulated into the primary proximal tubule cells against a concentration gradient. This accumulation was sensitive to inhibition by metabolic inhibitors. The dependence of phosphate uptake on the extracellular phosphate concentration was examined. Similarities were observed between primary proximal tubule cells and the LLC‐PK1 cell line in these regards. These phosphate uptake data were then plotted on a Lineweaver‐Burke plot. A nonlinear plot was obtained, which suggested that phosphate uptake occurs by means of a Na+ dependent, carrier mediated process, as well as by another Na+ independent mechanism. The pH dependence of phosphate uptake was also examined. Unlike previous observations with LLC‐PK1 cells, optimal phosphate uptake occurred at pH 6.5. However, this difference between the two cell culture systems may possibly be explained by differences in uptake conditions. The dependence of phosphate uptake on the extracellular NaCl concentration was examined at three different pH values. The rate of phosphate uptake at pH 7.0 was observed to saturate at a lower NaCl concentration than at either pH 6.0 or pH 6.5. Furthermore, the optimal rate of phosphate uptake at pH 7.0 was observed to be higher than at the other two pH values studied when the NaCl concentration was below 120 mM. However, when the NaCl concentration was raised to 150 mM, optimal phosphate was observed to occur at pH 6.5 rather than at pH 7.0. These observations may be explained if the pH affects not only the rate of phosphate uptake but also the affinity of the phosphate uptake system for sodium. Phosphate uptake was also observed to be sensitive to several agents, Na2·SO4 and NaSCN, which affect the membrane potential. As observed with phosphate uptake by LLC‐PK1 (and renal brush border membrane vesicles), phosphate uptake was highly sensitive to inhibition by the phosphate analogue arsenate. Novel observations were that the phosphate analogue vanadate and its cellular metabolite vanadyl stimulated the initial rate of phosphate uptake.
Amiloride in differentiation and commitment of Friend erythroleukemia cells
Authors: Lubin Martin 
Published: February 2005

AbstractDimethylsulfoxide (DMSO) converts almost all of the undifferentiated murine erythroleukemia cells (MEL or Friend cells, clone 745A) in a culture to differentiated cells that contain high levels of hemoglobin and that stop growing after a limited number of cell divisions. Contrary to other reports—that amiloride strongly inhibits DMSO‐induced differentiation in MEL cells—in this laboratory, inhibition by amiloride, tested with DMSO over a range of concentrations in two kinds of media and at various cell densities, was found to be only weak or absent. Similarly, amiloride did not inhibit induction by N, N′‐hexamethylene bis‐acetamide (HMBA). As expected from previous findings with other cell systems, amiloride inhibited protein synthesis and cell multiplication.
Voltage‐sensitive cyanine dye fluorescence signals in lymphocytes: Plasma membrane and mitochondrial components
Authors: Wilson H. Alexander , Seligmann Bruce E. , Chused Thomas M. 
Published: February 2005

AbstractThe origin of the cyanine dye fluorescence signal in murine and human peripheral blood leukocytes was investigated using the oxa‐ and indo‐carbo‐cyanines di‐O‐C5(3). and di‐l‐C5(3). Fluorescence signals from individual cells suspended with nanomolar concentrations of the dyes were measured in a flow cytometer modified to permit simultaneous four‐parameter analysis (including two‐color fluorescence or fluorescence polarization measurements). The contributions of mitochondrial membrane potential (Ψm) and plasma membrane potential (Ψpm) to the total voltage‐sensitive fluorescence signal were found to depend on the equilibrium extracellular dye concentration, manipulated in these experiments by varying the ratio of dye to cell density. Hence, conditions could be chosen that amplified either the Ψm or the Ψpm component. Selective depolarization of lymphocytes or polymorphonuclear leukocytes (PMN) in mixed cell suspensions demonstrated that defining the partition of dye between cells and medium is requisite to assessing the heterogeneity of cell responses by cyanine dye fluorescence. At extracellular dye concentrations exceeding 5 nM in equilibrated cell suspensions, both mitochondrial and plasma membrane dye toxicity were observed. In murine splenic lymphocytes, plasma membrane toxicity (dye‐induced depolarization) was selective for the B lymphocytes. Certain problems in calibration of Ψpm with valinomycin at low dye concentrations and perturbations of Ψpm by mitochondrial inhibitors are presented. These findings address the current controversy concerning Ψm and Ψpm measurement in intact cells by cyanine dye fluorescence. The finding of selective toxicity at low cyanine dye concentrations suggest that purported differences in resting Ψm among cells or changes in Ψpm with cell activation may reflect varible susceptibility to dye toxicity rather than intrinsic cell properties.