bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relationship between changes in ploidy and stable cellular resistance to hydrogen peroxide
Authors: Spitz Douglas R. , Mackey Michael A. , Li Gloria C. , Elwell James H. , McCormick Michael L. , Oberley Larry W. 
Published: February 2005

AbstractStable hydrogen peroxide (H2O2)‐resistant variants of the Chinese hamster ovary HA‐1 line have been isolated by culturing cells in progressively increasing concentrations of H2O2 (>200 days, in 50–800 μM H2O2). Increases in catalase activity in these variant cell lines were shown to correlate with increased H2O2 resistance. Stable (>240 days) H2O2‐resistant cell lines, seven quasidiploid (21–22 chromosomes/cell) and six quasitetraploid (40–44 chromosomes/cell) were clonally isolated from the 800 μM adapted H2O2‐resistant variants which were heterogeneous with respect to ploidy. The H2O2 dose‐modifying factors (DMFs) were 3, 5, 8, 13, 15, 26, and 27 for the seven quasidiploid cell lines, and 21, 32, 38, 40, 42, and 49 for the six quasitetraploid cell lines. The mean DMF was 14±10 for the former and 37±10 for the latter. Our data show that on the average the quasitetraploid cell lines were significantly more resistant to H2O2‐mediated cell killing than the quasidiploid cell lines derived from the same mixed population of 800 μM H2O2‐adapted cells. When catalase activities (k units/cell) of the HA‐1 cells and three of the clonally derived cell lines (two quasidiploid and one quasitetraploid) were determined and plotted vs. H2O2–DMF, a positive linear correlation was obtained (correlation coefficient = 0.99). This result was further confirmed when immunoreactive catalase protein/cell was detected by Western blots. Our data show that chronic exposure of cells to H2O2 stress (800 μM) was accompanied by increases in quasitetraploid cells within the population. Quasitetraploid cell lines derived from this population demonstrated increased stable H2O2‐resistance which may be related to stable increases in the expression of catalase.
Establishment and partial characterization of SV40 virus‐immortalized hepatocyte lines of normal and lethal mutant mice carrying a deletion on chromosome 7
Authors: Paul Dieter , Kwon Byoung S. , Höhne Martin , Tönjes Ralf , Haq Asifa K. , Hoffmann Birgit 
Published: February 2005

AbstractDeletions in chromosome 7 of the mouse have been shown to cause failure of expression of various hepatocyte‐specific genes in newborn deletion homozygotes, including the gene encoding tyrosine amino transferase (TAT) (EC 2.6.1.5) (Gluecksohn‐Waelsch, 1979). Primary liver cultures of newborn albino deletion mutant mice (C14CoS/C14CoS) and of phenotypically normal mice (C14CoS/Cch or Cch/Cch) were infected with SV40 virus and multiplying hepatocytes selected in arginine‐deficient medium containing epidermal growth factor (EGF), insulin, and hydrocortisone (HC). Resulting normal (NMH‐ch) and mutant (NMH‐m14) hepatocyte lines expressing integrated viral transforming sequences did not senesce, they multiplied autonomously of EGF in medium with insulin plus HC, and they retained hepatocyte‐specific functions. Both lines synthesized arginine and contained albumin and alpha‐fetoprotein (AFP) mRNAs. TAT‐specific mRNA was detected in normal but not in mutant hepatocyte lines. A fragment of the mouse tyrosinase gene, known to map at the albino locus (c) within the region deleted in the C14CoS mutant, hybridized with a 2.5 kb EcoRI fragment of normal NMH‐ch DNA, whereas this fragment was undetectable in mutant NMH‐m14 DNA. These immortalized hepatocyte lines reflect important properties of normal and mutant liver tissues from which they were derived. The deletion mutant mouse cell lines may be useful for complementation studies involving sequences corresponding to the deletions that encode regulatory gene(s) involved in the control of inducible expression of certain hepatocyte‐specific genes such as TAT.
Will heat‐stable proteins nonspecifically protect cells from thermal stress?
Authors: Prenninger Siegfried W. , Li Gloria C. 
Published: February 2005

AbstractIn cell‐free systems, stress‐resistant proteins nonspecifically stabilize stress‐susceptible proteins. This mechanism has been suggested to contribute to thermotolerance in cells (Minton et al.: Proc. Natl. Acad. Sci. USA, 79:7107–7117,1982). To test this hypothesis, red‐blood‐cell‐mediated microinjection was used to transfer macromolecules into monolayers of CHO cells. We introduced the heat‐stable proteins fetuin and ovomucoid into RBCs during hypotonic hemolysis and then fused the RBCs to CHO cells with polyethylene glycol as fusogen. Fetuin and ovomucoid were successfully transferred into 36–55% of the CHO cells as demonstrated by fluorescence of FITC‐conjugated proteins. The plating efficiency of these CHO cells after fusion ranged from 35% to 60%. Three hours after fusion, CHO cells microinjected with fetuin or ovomucoid were exposed to 43°C for 0–180 min or 45°C for 0–40 min, and thermal survival was determined. There was no difference in cell survival between control untreated cells, control cells fused with nonloaded RBCs, and cells fused with RBCs loaded with fetuin or ovomucoid.While our results do not support the hypothesis that heat‐stable proteins nonspecifically protect cells from thermal stress, several posslble explanations are provided for this observation.
Biosynthesis of proteoglycans by proliferating and differentiating normal human keratinocytes cultured in serum‐free medium
Authors: Rahemtulla Firoz , Moorer Candace M. , Wille John J. 
Published: February 2005

AbstractNormal human keratinocytes (NHK) were cultured in serum‐free medium, containing low (0.1 mM) or high (2 mM) calcium, to obtain proliferating and differentiating cultures, respectively. Proteoglycan (PG) synthesis of proliferating and differentiating NHK was investigated. Cultures were labeled with 35S‐sulfate, and the PGs were extracted from medium and cell layer. The newly synthesized PGs were isolated by ion‐exchange chromatography on a column of DEAE‐Sephacel. The molecular properties of the PGs and the size and composition of glycosami‐noglycans (GAGs) were determined. In general, the PGs are of relatively small size (Mr 70,000‐120,000). The PGs of proliferating cultures are larger in molecular size than the PGs of differentiating cultures, and this is due to the degradation of the GAG chains. The molecular weight of the GAG chains of proliferating NHK ranged from 4,800 to 22,000, and the range for GAGs from differentiating cultures varied from 2,800 to 9,600. By compositional analysis, these PGs proved to contain heparan sulfate, chondroitin sulfate, and dermatan sulfate as determined by nitrous acid degradation, and chondroitinase ACII and ABC digestion. No significant differences were found in the overall GAG composition of the medium secreted PGs of proliferating and differentiating cultures. In contrast, cell‐associated PGs of differentiating cells had higher levels of heparan sulfate than those of proliferating cells.
Characterization of the receptor for insulin‐like growth factor II in bone cells
Authors: Mohan Subburaman , Linkhart Thomas , Rosenfeld Ron , Baylink David 
Published: February 2005

AbstractWe have previously shown that insulin‐like growth factor II (IGF‐II) is produced by bone cells and that IGF‐II stimulates cell proliferation and collagen synthesis in bone cells. We now extend these in vitro findings by demonstrating specific IGF‐II binding to bone cells derived from newborn mouse calvaria and embryonic chick calvaria. The kinetics of [125]I IGF‐II binding in embryonic chick calvaria cells showed time and temperature dependence. Scatchard analysis of [125]I IGF‐II binding to chick calvaria cells showed an apparent Kd of 1.4 × 1010 M, with a calculated receptor site concentration of 40,000/cell. The specificity characteristics showed that IGF‐II was significantly more potent than IGF‐I or insulin in displacing IGF‐II tracer. Competition for binding of [125]I IGF‐II by unlabeled IGF‐II showed a dose‐dependent displacement between 0.5 and 25 ng/ml. Fifty percent displacement of [125]I IGF‐II binding to chick and mouse calvarial cells was achieved at 1‐2 ng/ml; 90% of specific binding of [125]I IGF‐II was displaceable in the presence of 125 ng/ml of unlabeled IGF‐II. IGF‐I showed less than 5% cross reactivity for displacement of [125]I IGF‐II binding to chick and mouse bone cells. Type II receptor inhibitory antibodies, R‐II‐PAB1 inhibited the binding of [125]I IGF‐II to mouse bone cells and H‐35 rat hepatoma cells (which contain type II but not type I receptors) in a dose‐dependent manner. R‐II‐PAB1 also inhibited basal cell proliferation as well as IGF‐II‐, IGF‐I‐, and fibroblast growth factor (FGF)‐induced cell proliferation in mouse bone cells. In chick calvaria bone cells and TE89 human osteosarcoma cells, R‐II‐PAB1 inhibited neither binding of [125]I IGF‐II nor IGF‐ll‐induced cell proliferation. These results together with our findings that IGF‐II increased chick bone cell proliferation in the presence of maximal doses of IGF‐I suggest that at least part of the mitogenic action of IGF‐II is mediated through type II rather than type I receptors in bone cells.
Reduction of adenine nucleotide content of clone 4 mdck cells: Effects on multiplication, protein synthesis, and morphology
Authors: Ladino C. , Schneeberger E. E. , Rabito C. A. , Lynch R. D. 
Published: February 2005

AbstractThe antitumor agent hadacidin (N‐formyl‐hydroxyamino‐acetic acid), at 4 mM, inhibited the multiplication of clone 4 Madin Darby canine kidney (MDCK) cells within 24 hr. Growth resumed rapidly upon replacement of hadacidin with aspartate, an observation consistent with the drug's action as a competitive inhibitor of adenylosuccinate synthetase, an enzyme in adenine nucleotide biosynthesis. Data indicate that the drug‐treated cells were arrested in S phase of the cell cycle. Accompanying inhibition of multiplication was a 16‐fold increase in the area occupied by the cells and a refractoriness to release by treatment with trypsin. None of these changes occurred when 0.5 mM adenosine was included in the incubation mixture containing the inhibitor. Hadacidin decreased the adenosine triphosphate (ATP) and cyclic adenosine monophosphate (cAMP) content of the cells as well as the rate at which 3H‐leucine was incorporated into protein. In the presence of 1 mM dibutyryl cAMP and theophylline, the drug had no effect on cell division and protein synthesis. The data suggest that, in clone 4 MDCK cells, the effects of hadacidin are mediated by diminishing the level of cAMP.
Coupling of bradykinin receptors to phospholipase C in cultured fibroblasts is mediated by a G‐protein
Authors: Etscheid Beth G. , Villereal Mitchel L. 
Published: February 2005

AbstractIn cultured foreskin fibroblasts, bradykinin stimulates inositol phosphate generation, arachidonic acid release, and Na+/H+ exchange, with doses of 1‐3 nM yielding half‐maximal stimulation. Binding of 3H‐bradykinin to these cells demonstrates a single receptor site with a Kd of 2.0 nM and a Bmax of 91 fmoles/mg protein. Bradykinin analogs of the B2 type inhibit this binding. GTP synergizes with bradykinin to stimulate phosphatidylinositol turnover in permeabilized fibroblasts and GTP‐γ‐S decreases the Bmax of bradykinin binding to fibroblast membranes, indicating that a G‐protein couples the receptor to phospholipase C. Pretreatment of fibroblasts with either cholera or pertussis toxin enhances bradykinin stimulation of inositol phosphate accumulation.
Volume changes of an endothelial cell monolayer on exposure to anisotonic media
Authors: Mazzoni Michelle C. , Lundgren Evy , Arfors Karl‐E. , Intaglietta Marcos 
Published: February 2005

AbstractThe osmotic process plays an important role in controlling the distribution of water across cell membranes and thus the cell volume. A system was designed to detect the volume changes of an endothelial cell monolayer when cells were exposed to media with altered osmolalities. Electrodes housed in a flow chamber measured the resistance of ionic media flowing over a cultured cell layer. Assuming the cell membrane acts as an electrical insulator, volume changes of the cell layer can be calculated from the corresponding changes in chamber resistance. The media used in the experiments had osmolalities in the range 120–630 mmol/kg. When cells were exposed to hypertonic media, there was rapid shrinkage with an approximate 30% reduction in total cell volume for a twofold increase in osmolality. On exposure to hypotonic media, the cells initially swelled with an approximate 20% volume increase for a decrease in osmolality by half. With sustained exposure to low osmolality media, there was a gradual and partial return of cell volume towards isotonic values that started 10 minutes after and was complete within 30 minutes of the osmolality alteration. This finding suggests regulatory volume decrease (RVD); however, no regulatory volume increase (RVI) was observed with the continued exposure to hypertonic media over 45 minutes.
Establishment and characterization of a unique human cell line that proliferates dependently on GM‐CSF, IL‐3, or erythropoietin
Authors: Kitamura Toshio , Tange Tsuyoshi , Terasawa Takashi , Chiba Shigeru , Kuwaki Tomoaki , Miyagawa Kiyoshi , Piao Yun‐Feng , Miyazono Kohei , Urabe Akio , Takaku Fumimaro 
Published: February 2005

AbstractWe have established a novel cell line, designated as TF‐1, from a patient with erythroleukemia, which showed complete growth dependency on granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) or on interleukin‐3 (IL‐3) and carried a homogeneous chromosomal abnormality (54X). Erythropoietin (EPO) also sustained the short‐term growth of TF‐1, but did not induce erythroid differentiation. These three hematopoietic growth factors acted on TF‐1 synergistically. Transforming growth factorβ and interferons inhibited the factor‐dependent growth of TF‐1 cells in a dose‐dependent fashion, and monocyte‐colony stimulating factor and interkeukin‐1 enhanced the GM‐CSF‐dependent growth of TF‐1. Ultrastructural studies revealed some very immature features in this cell line. Although TF‐1 cells do not express glycophorin A or carbonyl anhydrase I, the morphological and cytochemical features, and the constitutive expression of globin genes, indicate the commitment of TF‐1 to erythroid lineage. When induced to differentiate, TF‐1 entered two different pathways. Specifically, hemin and delta‐arninolevulinic acid induced hemoglobin synthesis, whereas TPA induced dramatic differentiation of TF‐1 into macrophage‐like cells. In summary, TF‐1 is a cell lineof immature erythroid origin that requires GM‐CSF, IL‐3, or EPO for its growth and that has the ability to undergo differentiation into either more mature erythroid cells or into macrophage‐like cells. TF‐1 is auseful tool for analyzing the human receptors for IL‐3, GM‐CSF, and EPO or the signal transduction of these hemopoietic growth factors.
Nutritional folate deficiency in chinese hamster ovary cells I. Characterization of the pleiotropic response and its modulation by nucleic acid precursors
Authors: Borman Linda S. , Branda Richard F. 
Published: February 2005

AbstractNutritional folate deficiency in Chinese hamster ovary (CHO)‐K1 cells inhibited population growth rate and caused growth arrest within 3 days of culture in Fol‐medium [without folate, hypoxanthine (Hx), and thymidine (TdR)]. Coincident with impaired population growth was a transient delay in cell cycle progression through S phase and an increase in cell size. The growth‐arrested population of predominantly G1 phase cells exhibited an increased adhesion to the culture substratum. There was a time‐dependent loss of cell reproductive capacity. All these various perturbations of cellular phenotype induced by folate deficiency were prevented by the addition of folate or a combination of TdR and Hx to the Fol‐medium. However, the singular presence of each nucleotide precursor differentially affected the pleiotropic response. The addition of Hx to Fol‐medium exacerbated the aforementioned abnormalities, producing a threefold increase in mean cell volume, a 72 hr accumulation of cells in the S phase of the cell cycle, and a rapid demise in cell clonogenicity. Unexpectedly, we found reduced cell adhesion in these cultures. In contrast, folate‐deficient cells supplemented with TdR exhibited a general amelioration of cell perturbations with respect to cell size, cell cycle distribution, and reproductive viability. Notably, such populations were not released from growth inhibition or subsequent growth arrest, and the cells became elongated and highly adherent with time. When cell populations from each of the three conditions of folate‐deficient culture were released from growth arrest by addition of complete medium, the respective profiles of synchronous cell cycle progression were distinctive.
Statin, a nonproliferation‐specific protein, is associated with the nuclear envelope and is heterogeneously distributed in cells leaving quiescent state
Authors: Wang Eugenia 
Published: February 2005

AbstractStatin, a protein of 57,000 daltons, is present primarily in the nuclei of nonproliferating cells of terminally differentiated tissues or of in vitro aged fibroblast cultures. In young growing cells, the protein can be induced to appear in the nuclei once the cell‐cycle traverse is blocked by various tissue culture manipulations, such as serum starvation; this expression, however, can be rapidly removed by addition of serum. The disappearance of statin in cells leaving the quiescent state is not uniform along the periphery of the nucleus; it can be distributed in various patterns, such as caps, nodules, patches, or irregular granules. This unusual distribution seems to suggest that preferential sites exist at the region of the nuclear envelope where statin presence may residually remain. The concentration of statin at the nuclear envelope region in cells at GO‐quiescent phase is confirmed by the intense staining of fluorescent antibody at the periphery of isolated rat liver nuclei. Further examination of the isolated nuclei reveals that the protein is associated with the lamina compartment of the nuclear envelope; this is evidenced by the results of immunoblotting experiments showing statin presence in the fraction enriched for lamins A‐C. Immunogold labelling studies show that the protein is located in the general area of the nuclear envelope. These results suggest that statin in GO‐quiescent cells is located predominantly at the nuclear envelope region and that in this vicinity there may exist geometrically sites of statin concentration as evidenced by the heterogeneous distribution in those cells experiencing the departure from the quiescent state.
Stabilization by heparin of acidic fibroblast growth factor mitogenicity for human endothelial cells in vitro
Authors: Mueller Stephen N. , Thomas Kenneth A. , Salvo Jerry Di , Levine Elliot M. 
Published: February 2005

AbstractThe effects of heparin and other glycosaminoglycans (GAGs) on the mitogenicity and stability of acidic fibroblast growth factor (aFGF) were studied. The mitogenic activity of aFGF was assayed utilizing cultured adult human endothelial cells (AHECs) isolated from iliac arteries and veins as target cells. In most experiments, aFGF purified from bovine brain was employed; in some experiments recombinant bovine aFGF was used and qualitatively similar results were obtained. In the presence of heparin, bovine aFGF at doses between 0.5 and 1.0 ng/ml (30‐60 pM) elicited half the maximum AHEC growth over a 4‐day period depending on the cell line tested; in the absence of heparin, significant growth was not observed at aFGF concentrations less than 10‐20 ng/ml. This effect of heparin was dose‐dependent over the range 0.1‐10 μg/ml (half‐maximum dose, 2 μg/ml). The mitogenic activity of bovine aFGF for AHECs decreased by 50% after preincubation in culture medium without cells at 37°C for 2 ½ to 3 hours. In contrast, the mitogenic activity of bovine aFGF preincubated in the presence of heparin‐containing culture medium without cells was dramatically stabilized (half‐life 24‐29 hours). These effects also were observed in serum‐free medium. Several GAGs structurally related to heparin such as chondroitin‐4‐sulfate, chondroitin‐6‐sulfate, dermatan sulfate, and hyaluronic acid neither potentiated nor stabilized aFGF mitogenic activity. However, heparan sulfate from bovine lung was found to be nearly as active as heparin in both these effects. These data suggest that the binding and stabilization of mitogens by extracellular and tissue‐associated heparan sulfates might play important roles in the regulation of AHEC growth.
HSP70‐related proteins in bovine skeletal muscle
Authors: Guerriero Vince , Raynes Deborah A. , Gutierrez Jesus A. 
Published: February 2005

AbstractConstitutive expression of HSP70‐related proteins was detected in a variety of bovine tissues using a specific antibody. All tissues contained a 73 kilodalton protein. A lower molecular weight form (72 kilodaltons) that co‐migrated on two‐dimensional gels with the stressed‐induced HSP70 was present in high levels in bovine skeletal muscle, but absent from rat skeletal muscle. Two‐dimensional gel analysis revealed several isoforms for both the 73 and 72 kilodalton forms. Purification of HSP70‐related proteins from bovine skeletal muscle, thymus gland and rat skeletal muscle demonstrated that the antibody recognized all the forms present in the tissue homogenates. The two proteins are similar but distinct as detected by one‐dimensional peptide mapping. The lower molecular form was not present in fetal tissue but was detectable in newborn animals, suggesting that the levels are regulated during development.
Elastin repeat peptides as chemoattractants for bovine aortic endothelial cells
Authors: Long Marianna M. , King Vickie J. , Prasad Kari U. , Freeman Bruce A. , Urry Dan W. 
Published: February 2005

AbstractCultured bovine aortic endothelial cells migrate toward a concentration gradient of repeating elastin peptides, specifically the repeating nonamers Gly‐Phe‐Gly‐Val‐Gly‐Ala‐Gly‐Val‐Pro and Gly‐Leu‐Gly‐Val‐Gly‐Ala‐Gly‐Val‐Pro and the repeating hexamer Val‐Gly‐Val‐Ala‐Pro‐Gly. Dose‐response experiments demonstrate that the peak of activity occurs at 8 × 10‐8 M for the nonapeptides and 1 × 10‐8 M for the hexapeptide. Checkerboard assays establish that the movement is chemotaxis and not chemokinesis. Because of the concentration difference in the responsiveness between the nonapeptide and the hexapeptide, the cells can differentiate between the two types of repeats. The positive control for the chemo‐taxis studies was fibronectin.