bluuebunny/crossref_metadata_2025_split huggingface dataset:
An estradiol‐responsive mouse endometrial cell strain with inducible aryl hydrocarbon hydroxylase activity
Authors: Iannaccone Philip M. , Stols Lucy , Hollenberg Paul F. , Gurka David P. 
Published: February 2005

AbstractA mouse endometrial cell population has been isolated by mild tryptic digestion of the uterine lining. The cells were morphologically similar to endometrial gland cells in the intact mouse endometrial gland. The endometrial cells had a modal chromosome number of 66. The cells were adherent to glass as well as plastic and contained numerous large refractile, osmophilic, non‐membrane‐limited granules which stain with periodic acid‐Schiff reagent but do not stain with oil red O, Sudan black, or Alcian blue. Cell growth was responsive to 17β‐estradiol; cell number increased 1.34‐fold in 4 days in the presence of 10−8 M estradiol. The cells are not tumorigenic. The cells showed induction of aryl hydrocarbon hydroxylase (AHH) activity when 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) was added to the growth media for 24 h. AHH activity and its induction were investigated with cells grown in the presence and absence 10−8 M estradiol. Cells grown in media containing estradiol exhibited a 6.2‐fold induction by TCDD; cells grown without estradiol gave an 8.4‐fold induction of AHH activity. AHH activity and its induction by TCDD were demonstrated in cells grown with fetal calf serum that had been pretreated with dextran‐coated charcoal to remove endogenous steroids. Benzanthracene failed to induce AHH activity significantly.
Fibroblast contraction of collagen lattices in vitro: Inhibition by chronic inflammatory cell mediators
Authors: Ehrlich H. Paul , Wyler David J. 
Published: February 2005

AbstractFibroblast‐populated collagen lattices (FPCL), prepared in petri dishes with serum‐containing culture medium and incubated at 37°C, undergo progressive and symmetric contraction (reduction in size) over a period of days. The in vitro contraction process requires viable cells with intact cytoskeletal elements, is associated with cell elongation, and is believed to represent a fibroblast function which also occurs in vivo during wound healing and tissue fibrosis. We report that soluble mediators elaborated by chronic inflammatory cells cultured in vitro, when added to FPCL, inhibit lattice contraction. Granulomas, isolated from the liver of Schistosoma mansoni‐infected mice, secrete a factor(s) with an estimated molecular weight between 13,700 and 43,000 daltons (gel filtration: Sephadex G‐200) and pl = 6 (preparative isoelectrofocusing in granular gel) which inhibits lattice contraction but is not toxic to fibroblasts. Supernatants (cell‐free conditioned culture medium) of cultured macrophages isolated from these granulomas also contain this activity. The contraction inhibitory activity present in granuloma culture supernatants is abrogated by the addition of indomethacin to the lattices, while the addition of prostaglandin E2 (PGE2) alone to lattices inhibits contraction. Furthermore, culture supernatants interfere with fibroblast elongation in lattices. We propose that the ability of fibroblasts to contract collagen lattices in vitro and a fibrotic mass in vivo may be regulated by soluble products of chronic inflammatory cells, including macrophages. This process may be mediated by fibroblast‐derived prostaglandins which alter cytoskeletal functions and has implications for understanding regulation of tissue fibrogenesis in a variety of diseases.
Cytotoxic effects of dexamethasone restricted to noncycling, early G1‐phase cells of L1210 leukemia
Authors: Smets Lou A. , Bout Bram , Brouwer Marjoleine , Tulp Ab 
Published: February 2005

AbstractThe cytostatic and cytolytic effects of dexamethasone were studied as functions of cell cycle position in mouse L1210 leukemia cells. To this end, the cells were separated according to size by sedimentation at unit gravity in a specially designed sedimentation chamber. The fractions were analyzed by radioautography and flow cytophotometry. The size‐distributions obtained by 1g sedimentation coincided with cell‐cycle age distribution. With increasing fraction number, samples highly enriched in G1, S, and G2/M cells, respectively were obtained: the smallest cells being in early G1 and the largest in mitosis. In the presence of dexamethasone (10−6‐10−5 M), growth slowed down after a few cell cycles and the cells accumulated in early G1 phase. Lytic cell kill by continued exposure to the drug was confined to the fractions containing the small, early G1‐phase cells. These fractions were also enriched in noncycling cells that were not labeled by prolonged exposure to 3H‐thymidine. After removal of dexamethasone, the cells in S and G2/M phase completed cell cycle traverse but were retarded again in the G1 and early S phase of the next division cycle. The data suggest a memory effect for previous drug exposure. It is concluded that the cytostatic and cytolytic effects of dexamethasone are separate, though not unrelated events. Cytolysis is confined to the noncycling cells that in untreated populations can exit from the dividing compartment during a transitional phase of about 60 minutes subsequent to mitotic division. The cytostatic effects potentiate cytolysis by accumulating the cells in the early G1 phase and thus increasing the probability of their transit to the G0 compartment, sensitive for drug‐mediated cytolysis.
Cell membrane potential changes follow epstein‐barr virus binding
Authors: Rosenthal Ken S. , Shapiro Howard M. 
Published: February 2005

AbstractUpon binding to receptor‐bearing target cells, viruses cause cell membrane potential changes. Epstein‐Barr Virus causes a biphasic membrane potential change in receptor‐bearing B lymphocytes but not receptor‐negative T lymphocytes, as measured by flow cytometry of cyanine dye uptake. Membrane potential changes upon EBV binding to receptor‐bearing cells resemble electrical responses of other cells following ligand binding to transmembrane receptors.
Changes in the levels of viral and cellular gene‐transcripts in the cell cycle of SV40 transformed mouse cells
Authors: La Bella Franca , Brown Eric H. , Basilico Claudio 
Published: February 2005

AbstractWe have analyzed the regulation of transcription of integrated SV40 DNA and of five cellular genes during the cell cycle of two lines of SV40 transformed mouse 3T3 cells. These cells (ts SV3T3) are temperature sensitive for the expression of the transformed phenotype and at the nonpermissive temperature (39°C) become arrested in G1 at low serum concentrations. SV40 specific RNAs are not detected either in the nuclear or in the cytoplasmic poly(A+)RNA of quiescent cells, suggesting control at the level of transcription. After serum stimulation, however, viral transcription increases and reaches its maximum during S‐phase. The expression of a group of selected housekeeping genes has received parallel analysis to determine whether other cellular genes, beside the integrated SV40, are shut off in G1 arrested cells or are expressed in restricted periods of the cell cycle. We have found that, while the mRNAs for collagen, adenosinphosphoribo‐siltransferase (APRT) and the mouse major histocompatibility complex (H2) are present throughout the cell cycle, the genes coding for the multifunctional protein CAD and dehydrofolate reductase are cell‐cycle regulated.
Phosphatidylethanolamine synthesis in ethanolamine‐responsive and ‐nonresponsive cells in culture
Authors: Kano‐Sueoka T. , Errick J. E. , King D. , Walsh L. A. 
Published: February 2005

AbstractMammalian cells can be classified into two types based upon whether or not they show growth response to ethanolamine (Etn) in culture. The content of phosphatidylethanolamine (PE) in phospholipid and incorporation of radioactive Etn into the cells were examined in the Etn‐responsive and ‐nonrespponsive cells in order to elucidate the mechanisms of growth stimulation by Etn. In all Etn‐responsive cells tested, 5 μM Etn significantly altered the composition of cellular phospholipid compared to that grown without Etn, while Etn‐nonresponsive cells had a similar phospholipid composition whether the growth medium contained Etn or not. Using two rat mammary carcinoma cell lines, 64–24 (responsive type) and 22‐1 (nonresponsive type), further studies were carried out. In 64–24 cells there was a proportional increase in PE content as the dosage of Etn in the medium was increased. The increase in PE content leveled off at 10 μM. Further, the increase in PE content was correlated with increased rate of growth. In contrast, PE content or growth rate did not change at all in 22‐1 cells. In 64–24 cells radioactive Etn (0.1–50 μM) was incorporated four‐ to five‐fold more efficiently into phospholipid, and the aqueous pool of precursors of PE was ten times less as compared to 22‐1 cells, indicating that Etn‐responsive cells utilize Etn supplied in the medium to synthesize PE far more efficiently than Etn‐nonresponsive cells. De novo synthesis of PE must not be sufficient to support optimum growth in Etn‐responsive cells.
Transforming growth factors released from Kirsten sarcoma virus transformed cells do not compete for epidermal growth factor membrane receptors
Authors: Chua Chu Chang , Geiman Deborah , Ladda Roger L. 
Published: February 2005

AbstractKirsten murine sarcoma virus (KiMSV)‐transformed rat kidney cells (KNRK) release small polypeptides (M, 12,500–15,300) into the culture medium that are capable of stimulating normal rat kidney cells (NRK) to form colonies in soft agar. The transforming growth factors (TGFs) did not compete with epidermal growth factor (EGF) for its receptor and did not induce specific phosphorylation of EGF receptor on NRK cell membranes. These properties differ from the TGFs isolated by other investigators. Our data further establish the heterogeneity of the materials produced by transformed cells that induce transformation‐specific changes in normal cells.
Differential effect of αdifluoromethyl‐ornithine on the proliferation of balb 3T3 and chemically transformed 3T3 cells
Authors: Medrano Estela E. , Goldemberg Sara H. , Algranati I. D. 
Published: February 2005

AbstractIn order to study the effect of polyamine depletion on growth and proliferation of untransformed and chemically transformed cells, α‐difluoromethyl‐ornithine (DFMO) was added to cultures of 3T3 cells and their benzo[a]pyrene derivative BP‐3T3. Both types of cells stopped their proliferation after 72 hr of treatment with the inhibitor. When DFMO was removed and cells were cultivated afterwards in fresh medium without the drug, untransformed cells resumed growth after a lag period, whereas transformed cells were unable to proliferate unless exogenous polyamine was added. These alterations showed a strict correlation with intracellular polyamine pools, since after removal of DFMO from the culture medium, polyamine concentrations increased to almost normal values in 3T3 cells, but remained at low levels or decreased even more in the transformed cells BP‐3T3. The analysis by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis of labeled proteins of both cell extracts has indicated that the described control of cell proliferation by intracellular polyamine levels might be related to the synthesis of at least two proteins with molecular weights of about 36,000 and 55,000 daltons.
Evidence that a variety of cultured cells secrete protease nexin and produce a distinct cytoplasmic serine protease‐binding factor
Authors: Eaton Dan L. , Baker Joffre B. 
Published: February 2005

AbstractFour criteria were used to examine serum‐free conditioned cell culture medium for protease nexin (PN):(1) formation of SDS‐stable ∼77 K Da complexes between a medium component and [125l]thrombin; (2) acceleration by heparin of the rate of formation of these complexes; (3) cellular binding of these complexes; and (4) inhibition by heparin of the cellular binding of complexes. Listed in order of decreasing PN production, PN was detected in media conditioned by the following cell types: human foreskin fibroblasts (0.18 μg/106 cells), rat embryo heart muscle cells (0.13 μg/106 cells), mouse myotubes (0.1 μg/106 cells), monkey kidney epithelial cells, human fibrosarcoma cells, human lung fibroblasts, simian virus 40 (SV‐40)‐transformed human fibroblasts, human epidermoid carcinoma cells, bovine aortic endothelial cells (only after phorbol ester treatment), and mouse myoblasts. No PN was found in medium conditioned by mouse 3T3 cells, SV40 virus‐transformed 3T3 cells, human lymphoblasts, or mouse leukemia cells.Eleven of the cell types examined for secretion of PN were also examined for the presence of cytoplasmic thrombin‐binding factors. Lysates from all of these cell types contained a factor that formed ∼60–65 K Da sodium dodecyl sulfate (SDS)‐stable complexes with [125l] thrombin. This MW is significantly lower than that of [125l] thrombin‐PN complexes, indicating that the factor is distinct from PN. Nevertheless, PN and the cytoplasmic factor share similarities. Production of both PN (by HF cells and WI‐26 cells) and the cytoplasmic factor (by HF cells and 3T3 cells) are stimulated by epidermal growth factor and phorbol myristate acetate. Also, both PN and the cytoplasmic factor complex trypsin, plasmin, urokinase, and thrombin, but not pancreatic elastase. Because a number of the cells that produce PN or the cytoplasmic serine protease‐binding factor are known to produce plasminogen activators, both PN and the cytoplasmic factor could regulate plasminogen activator activity.
Abnormal behavior of cultured fibroblasts from nodule and nonaffected aponeurosis of Dupuytren's disease
Authors: Azzarone Bruno , Failly‐Crepin Christianne , Day‐garosjean Leela , Chaponnier Christine , Gabbiani Giulio 
Published: February 2005

AbstractVimentin‐positive, desmin‐negative cells were established in culture from the nodule and from apparently normal palmar aponeurosis of a patient with Dupuytren's disease and compared with normal human embryonic and adult fibroblasts or sarcomatous cells. Cells from the nodule display in vitro biological properties that are intermediate between those expressed by normal fibroblasts and sarcoma cells or cells from the nodule transformed with SV40 virus. Thus, they represent an interesting in vitro model of partially transformed human cells. This behavior is not evolutive and justifies the classification of Dupuytren's disease among the benign mesenchymal tumors. The production of high level of plasminogen activator probably explains the local reactive pathology, and could act as a mitogenic stimulus for the proliferation of the nodule itself. Cultures derived from the apparently normal palmar aponeurosis show some but not all the abnormal growth properties of cells from nodules; this may help to explain the onset of local recurrences. Our results suggest that Dupuytren's disease is not strictly local and limited to the nodules, but affects, at least partially, the whole aponeurosis. Dupuytren's nodules could be considered as a model of tumor progression in a benign situation.
Protease nexins: Cell‐secreted proteins that mediate the binding, internalization, and degradation of regulatory serine proteases
Authors: Knauer Daniel J. , Thompson James A. , Cunningham Dennis D. 
Published: February 2005

AbstractThe protease nexins (PN‐I, Mr ∼︁38,000; PN‐II, Mr ∼︁95,000; and PN‐III, Mr ∼︁31,000) are recently described cell‐secreted proteins that selectively link to regulatory serins proteases in the extracellular environment and mediate their cellular binding, internalization, and degradation. In the present studies we compared the protease nexins with respect to protease specificity, heparin sensitivity, and general mode of action. By competitive binding assays using [125l]‐thrombin, [125l]‐nerve growth factor‐γ(125l‐NGF‐γ), and [125l]‐epidermal growth factor binding protein (125l‐EGF‐binding protein), we characterized the nexins in terms of protease specificity and determined that PN‐I links to and mediates the cellular binding of thrombin or urokinase, whereas PN‐II and PN‐III preferentially link to and mediate the cellular binding of the EGF binding protein and NGF‐γ, respectively. In addition, whereas the ability of PN‐I to link to thrombin is strongly modulated by heparin, PN‐II and PN‐III are essentially unaffected by heparin. The linkage of each of the nexins to their respective proteases requires the catalytic site serine of the protease, judged by the inability of diisopropylphospho (DIP) derivatives of the proteases tested to link to their respective nexins. Subsequent to linkage, the nexin:protease complexes are bound to cells, rapidly internalized, and ultimately degraded via a monensin‐sensitive apparently lysosomal pathway, although each nexin:protease complex is degraded at its own characteristic rate. Importantly, the protease nexins provide the major pathway through which human fibroblasts interact with each of the serine proteases studied. Taken together, these data suggest that the nexins are a unique class of cell‐secreted proteins that enable cells to monitor and selectively regulate specific serine proteases in their environment.
Mechanism of action of leukotriene B4: Intracellular calcium redistribution in rabbit neutrophils
Authors: Naccache P. H. , Molski T. F. P. , Borgeat P. , Sha'afi R. I. 
Published: February 2005

AbstractThe possible involvement of membrane‐bound calcium in the mechanism of action of leukotriene B4 was examined using the fluorescent chelate probe, chlortetracycline. Leukotriene B4 was found to cause a rapid release of membrane‐bound calcium at physiologically relevant concentrations. This effect of leukotriene B4 is stereospecific and its magnitude is decreased upon the transformation of leukotriene B4 into its ω‐hydroxy and ω‐carboxy metabolites. The pool of calcium affected by leukotriene B4 appears to be the same as that released by other chemotactic factors such as formyl–methionyl–leucyl–phenylalanine (f‐Met‐Leu‐Phe). Similarly, preincubation with f‐Met‐Leu‐Phe results in a decreased responsiveness of the cells to the addition of leukotriene B4. These results extend further the analogy between the mechanism of action of peptidic and lipid chemotactic factors, and emphasize the central role of the intracellular redistribution of calcium, as inferred and monitored by chlortetracycline fluorescence and steady‐state isotopic flux studies, in neutrophil activation.
Increased uptake of thymidine in the activation of sea urchin eggs. III. Effects of aphidicolin
Authors: Nishioka David , Killian Christopher E. , Chacon Cecilia T. , Sgagias Magdalene K. 
Published: February 2005

AbstractUptake and phosphorylation of externally supplied [3H]‐thymidine are fully stimulated in fertilized sea urchin eggs exposed to 5.0 μg/ml aphidicolin. As in untreated controls, the rate of uptake in aphidicolin‐treated eggs increases greater than 50‐fold shortly after fertilization, and greater than 85% of the transported thymidine is immediately phosphorylated to the triphosphate. The intracellular levels of [3H]‐thymidine triphosphate (3H‐dTTP) resulting from an external supply of [3H]‐thymidine is therefore equal in aphidicolin‐treated and untreated fertilized eggs. Under the same experimental conditions, the incorporation of externally supplied [3H]‐thymidine into newly synthesized DNA of fertilized eggs is 90% inhibited by exposure to aphidicolin. The full availability of 3H‐dTTP in these eggs further suggests that aphidicolin inhibits specifically at the level of DNA synthesis. This inhibitory effect is proportional to the concentration of aphidicolin between 0 and 5.0 μg/ml. In the continuous presence of 5.0 μg/ml aphidicolin, fertilized eggs fail to undergo mitotic chromosome condensation, nuclear envelope breakdown, and cytokinesis, suggesting a dependent link between these processes and the completion of nuclear DNA synthesis.
Calcium stimulates ornithine decarboxylase activity in cultured mammalian epithelial cells
Authors: Langdon Robert C. , Fleckman Philip , McGuire Joseph 
Published: February 2005

AbstractOrnithine decarboxylase (ODC) activity usually rises to a peak a few hours after a trophic stimulus. The stimulation of ODC has been shown to depend on extracellular calcium in several in vitro eukaryotic systems. We have investigated the effect of calcium concentration on ODC activity and have found that ODC is stimulated when CaCl2 alone is added to calcium‐deprived cells. Epithelial cells from calf esophagus were cultured and grown until stratified. Replacement of medium with fresh serum‐free medium resulted in stimulation of ODC activity, which peaked at 4 hours and declined to basal level by 10 hours. Subsequent depletion of Ca2+ either by addition of ethylene glycol bis (β‐aminoethyl ether) N, N′‐tetraacetic acid (EGTA) or by replacement of medium with Ca2+‐free medium, resulted in obliteration of ODC activity 4 hours later. Conversely, cultures in which medium was replaced with Ca2+‐free medium and at 10 hours were repleted with Ca2+ (either by addition of CaCl2 or by replacement of medium with Ca2+‐containing medium) exhibited a pronounced elevation of ODC activity 4 hours later. ODC activity peaked at 6 hours after the addition of CaCl2 and declined by 8 hours. The effect was elicited by a wide range of concentrations of added Ca2+ from 0.1 mM to 4.0 mM, but was maximal at 1.0 mM. ODC activity was totally abolished if either cycloheximide (10 μg/ml) or putrescine (10 mM) was added to cultures immediately prior to Ca2+ addition. Actinomycin D (2, 5, or 10 μg/ml) added 30 minutes before Ca2+ did not prevent the stimulation of ODC by added Ca2+. Stimulation by Ca2+ is dependent on (1) absence of Ca2+ during the initial 10‐hour incubation and (2) duration of incubation in Ca2+‐free medium prior to Ca2+ replenishment. The results indicate that Ca2+ can increase ODC in epithelial cells exposed to Ca2+‐depleted medium and that the increase in ODC depends on protein synthesis but is not inhibited by actinomycin D.
Characterization of two populations of CFU‐S fractionated from mouse fetal liver by fluorescence‐activated cell sorting
Authors: Johnson G. R. , Nicola N. A. 
Published: February 2005

AbstractThe properties of spleen colony forming units (CFU‐S) contained in two murine fetal liver cell populations (pre‐colony‐forming cell (CFC) and CFC fractions) obtained after fluorescence‐activated cell sorting fractionation on the basis of pokeweed mitogen binding have been analyzed. Individual spleen colonies generated by both populations were examined to determine cellularity, differential cell morphology, as well as CFU‐S and in vitro CFC content. Spleen colonies from both populations contained approximately equal numbers of cells 7 days after transplantation; at 12 days, however, CFU‐S from the pre‐CFC fraction produced four times as many cells per colony than colonies from the CFC fraction. Although the frequency of spleen colonies containing CFU‐S was similar, in comparison to the CFC fraction, spleen colonies obtained from the pre‐CFC fraction contained higher absolute numbers of CFU‐S. This was most evident with CFU‐S assayed 12 days after transplantation of 12‐day spleen colony cells (pre‐CFC fraction, 84% of colonies contained CFU‐S, mean of 527 per colony; CFC fraction, 77% of colonies contained CFU‐S, mean of 41 per colony). Similarly, the in vitro CFC content of 7‐ or 12‐day spleen colonies was higher in colonies produced by pre‐CFC fraction CFU‐S. No significant differences were observed in either the proportion of CFU‐S in S‐phase or the morphology of spleen colonies produced by either cell population.