bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cell properties after repeated transplantation of spontaneously and of SV40 virus transformed mouse cell lines. I. Growth in culture
Authors: McFarland V. W. , Mora P. T. , Schultz A. , Pancake S. 
Published: February 2005

Abstract“Spontaneously” or SV40 virus transformed AL/N mouse cell lines were passed repeatedly through syngeneic mice. Cell lines were re‐established in culture from minced pieces of tumors in the presence of concentrated fetal calf serum or from tumor cells dispersed by trypsin. The aim of this study was to compare the two cell lines in regard to the selection processes which operate during such procedures by characterization of the resulting cell lines. Measurements of growth in tissue culture on substratum showed no significant difference between any of the transformed cell lines. The SV40 transformed cells and its derivative cells had a low anchorage requirement for growth. The greatest anchorage requirement for growth was in the normal untransformed cells and in the derivative cells from the “spontaneously” transformed cells which were established from minced tumors. The spontaneously transformed cells and all derivative cells had high tumorigenicity in vivo (TD50 < 102). The SV40 transformed cells had no observable tumorigenicity (TD50 > 108), except when injected into irradiated mice (TD50 = 107). The derivative cell lines obtained from such a tumor had increased tumorigenicity (TD50 = 1–5 × 105 in the immunocompetent mice, 5 × 104 in the irradiated mice). The SV40 transformed derivative cells maintained their SV40 specific T antigen and their susceptibility to lysis by specific antiserum.
Isolation and characterization of revertant cell lines. VII. DNA synthesis and mitotic rate of serum‐sensitive revertants in non‐permissive growth conditions
Authors: Vogel Arthur , Pollack Robert 
Published: February 2005

AbstractThe ability to synthesize DNA and enter mitosis was studied in Balb/c and Swiss 3T3 cells, SV40 and MSV‐transformed 3T3 cells and revertants of these transformed cells in cultures of different serum concentrations and cell densities. Three ways were found by which cells were able to maintain a constant cell number in non‐permissive growth conditions: cessation of DNA synthesis, synthesis of DNA coupled with failure to enter mitosis, and the slow traverse of the cell cycle coupled with cell shedding.Growth control of the revertant of an MSV‐transformed Balb/3T3 cell most closely resembled that of Balb or Swiss 3T3. This line did not grow in 1% serum and did not synthesize DNA in either non‐permissive condition.Serum‐sensitive revertants of SV40‐transformed 3T3 cells are also unable to grow in 1% serum and also do not grow beyond confluence in 10% serum, but these cells differ from 3T3 in the manner in which this growth arrest is accomplished. In 1% serum, revertants synthesize DNA but do not enter mitosis. At confluence in 10% serum, they slowly traverse the cell cycle, with dividing cells replacing cells that are shed into the medium.
Neoplastic differentiation: Interaction of simian virus 40 and polyoma virus with murine teratocarcinoma cells in vitro
Authors: Swartzendruber D. E. , Lehman J. M. 
Published: February 2005

AbstractThe host‐virus interactions of Simian virus 40 (SV40) and polyoma virus (Py) with cell lines established from a teratocarcinoma were studied. The cells utilized in this study were the multipotential stem cell of the teratocarcinoma, embryonal carcinoma, and differentiated cells derived from embryonal carcinoma. Several lines of differentiated cells were established in vitro which included parietal yolk sac, epithelial, and spindle cell types. Embryonal carcinoma cells are not susceptible to infection by either SV40 or Py virus. However, differentiated cells are susceptible to infection by these viruses. The differentiated cells are permissive for Py virus replication and nonpermissive for SV40. Several continuously growing cell lines have been established from the SV40 infected cultures which express T antigen in 100% of the cells. The results indicate that undifferentiated embryonal carcinoma cells and their differentiated progeny respond quite differently to challenge with these two oncogenic DNA viruses.
The early effects of ouabain on potassium metabolism and rate of proliferation of mouse lymphoblasts
Authors: Cuff Joyce M. , Lichtman Marshall A. 
Published: February 2005

AbstractMurine lymphoblasts grown in suspension culture in the presence of ouabain showed a dose dependent and sequential decrease in 86Rb+ (K+ analogue) influx, cellular potassium content, and growth rate. An increase in eosin staining and a decrease in cell number was observed after two hours in the presence of 1 mM ouabain; 1 μM ouabain was without effect on any of the parameters measured. Ouabain inhibition was rapidly and completely reversible at concentrations that were not cytotoxic.
Somatic genetic analysis of cyclic AMP action: Selection of unresponsive mutants
Authors: Coffino Philip , Bourne Henry R. , Tomkins Gordon M. 
Published: February 2005

AbstractDibutyryl cyclic AMP and theophylline kill S49.1 mouse lymphoma tissue culture cells. When cells are grown in soft agar with these drugs, the few clones that survive are resistant to cytolysis. The rate of mutation to resistance is 1–3 × 10−7/cell/generation in both diploid and tetraploid cells. The incidence of mutants is increased by treatment with a chemical mutagen ICR 191. The mutation is consistently associated with greatly reduced or absent cytoplasmic cyclic AMP binding protein. These results suggest that a somatic mutation leads to a defect of the protein kinase regulatory subunit and that activity of this kinase is required for induction of cell death by cyclic AMP.
Control of normal differentiation of myeloid leukemic cells. VIII. Induction of differentiation to mature granulocytes in mass culture
Authors: Fibach Eitan , Sachs Leo 
Published: February 2005

AbstractThere are three types of myeloid leukemic cells, IR+D+, IR+D− and IR−D−. IR+D+ cells were induced to differentiate to granulocytes in mass culture in liquid medium by conditioned medium (CM) from cultures of lungs from mice injected with endotoxin. About 90% of the leukemic cells were induced to differentiate, 50% to mature granulocytes and 40% to intermediate stages. An efficient induction of granulocyte differentiation was also obtained with CM from primary cultures of rat embryo or human spleen and there was a lower activity with CM from various other sources. IR+D− cells were induced to differentiate to about 20% cells with intermediate stages but not to mature granulocytes; IR−D− cells could not be induced to differentiate to intermediate or mature stages. IR+D+ cells were induced to form intermediate stages of granulocyte differentiation, to phagocytose and to attach to the surface of the Petri dish, three days after incubation with CM. Optimum induction of mature granulocytes required six more days incubation with CM. Mature granulocytes induced from leukemic cells showed cytochemical properties and a morphology in the electron microscope similar to that of normal mature granulocytes. These induced granulocytes did not form leukemiac in animals or colonies in agar. The granulocytes induced from the myeloid leukemic cells, therefore, behaved like normal mature granulocytes.
Separation of subpopulations of in vitro colony forming cells from mouse marrow by equilibrium density centrifugation
Authors: Williams Neil , Van Engh Gerrit J. Den 
Published: February 2005

AbstractEquilibrium density centrifugation was used to characterise and separate subpopulations of mouse haemopoietic progenitor cells capable of producing colonies of granulocytes and macrophages in vitro. The material used to induce colony formation (CSF) was prepared from an extract of pregnant mouse uteri. This CSF preparation was found to be free of factors modifying the response. Under these culture conditions, in vitro colony forming cells (CFU‐c) were found to be relatively homogeneous in their buoyant density. This homogeneity was independent of CSF concentration. A heterogeneous density profile of CFU‐c was obtained when various cell fractions were cultured in the presence of CSF and rat blood lysate. The majority of the additional cells which responded to erythrocyte lysate were dense (modal density 1.080 g/cm3) compared to CFU‐c which respond to CSF alone (modal density 1.074 g/cm3). It is concluded that in vitro colonies induced by CSF and in vitro colonies grown in the presence of CSF and erythrocyte lysate reflect two different populations of CFU‐c.
Isolation and characterization of alkaline phosphatase‐constitutive variants from chinese hamster ovary cells (CHO‐K1)
Authors: Nose Kiyoshi , Katsuta Hajim 
Published: February 2005

AbstractPure clones with high alkaline phosphatase (ALP) activity were isolated from Chinese hamster ovary (CHO‐K1) cells which showed no detectable ALP activity. ALP‐positive cells appeared at the frequency of 10−4 in the N‐methyl‐N'‐nitro‐N‐nitrosoguanidine‐treated cell population.With respect for cellular morphology, plating efficiency and several other enzymatic activities, no distinct difference was found between the original CHO‐K1 cells and its ALP‐positive variants, although some alterations in karyotype were found.Levels of ALP activity in these clones was stably maintained during serial cultivation. Some of the enzymological properties of ALP in the isolated clones were similar to those in bone or kidney.
Autoradiographic studies of nicotinic acid utilization in human‐mouse heterokaryons and inhibition of utilization in newly‐formed hybrid cells
Authors: Rechsteine Martin , Hill Kim R. 
Published: February 2005

AbstractAlthough most mammalian cell lines can utilize either nicotinic acid or nicotinamide for the biosynthesis of nicotinamide adenine dinucleotide (NAD), thymidine kinase‐deficient, mouse 3T3–4F cells are unable to utilize nicotinic acid. When 3T3–4E cells were fused with human D98/AH2 cells, autoradiography showed that the resultant heterokaryons synthesized NAD from nicotinic acid at rates comparable to the human parental cell. The rate of nicotinic acid utilization in heterokaryons remained unchanged over the fourday period of study following cell fusion. In contrast to the results observed with heterokaryons, nicotinic acid utilization was markedly reduced in hybrid cells. Of 100 hybrid clones examined at four or five days following cell fusion, 60 utilized nicotinic acid at rates less than one tenth that of the parental human cell. Similar results were observed in hybrid clones at nine or ten days following fusion. Uniformly high rates of NAD biosynthesis were observed in hybrid clones with nicotinamide as the precursor. This excludes the possibility that the reduction in nicotinic acid utilization in hybrid cells is due to a general metabolic dysfunction. The biochemical mechanism by which nicotinic acid utilization is markedly reduced has not been determined with certainty, however, several observations suggest genetic suppression.
Stimulation of lactic acid production in chick embryo fibroblasts by serum and high pH in the absence of external glucose
Authors: Fodge D. W. , Rubin H. 
Published: February 2005

AbstractLactic acid production by chick embryo fibroblasts occurs in the absence of exogenous glucose. Fifteen to 50‐fold less lactic acid is formed in the absence of glucose than in its presence. Nevertheless, serum and pH stimulation enhances this residual lactic acid production to the same relative extent as when glucose is present. The amount of lactic acid formed cannot be accounted for by the catabolism of residual glucose in the medium since its concentration is less than one‐tenth that of the lactic acid eventually produced. Moreover, the residual glucose concentration remains constant or increases during the course of the experiment. To a large extent lactic acid accumulation in the absence of external glucose is dependent on the presence of amino acids in the medium, but amino acid transport is not affected by the stimulatory agents used in this study. The results suggest that treatments which stimulate cell multiplication also activate those enzymatic pathways which convert amino acids to pyruvic and thence to lactic acid.
The control of liver regeneration by parathyroid hormone and Calcium
Authors: Rixon R. H. , Whitfield J. F. 
Published: February 2005

AbstractFollowing partial hepatectomy in rats, there were two bursts of hepatocyte DNA‐synthetic and mitotic activity which were produced by two subpopulations having different rates of (nearly synchronous) proliferative development. Only about 50% of the cells in both subpopulations could initiate DNA synthesis and enter mitosis when exposed to the hypocalcemic conditions in the parathyroprivic rat for 24 hours before partial hepatectomy. The proliferatively incompetent hepatocytes in these hypocalcemic rats could be induced to initiate their DNA synthetic and mitotic activity by an intraperitoneal injection of the calcium‐mobilizing parathyroid hormone (50 USP units/100 g) as late as 12 hours after partial hepatectomy. Single intraperitoneal injections of calcium (0.25 mg/100 g) could also restore the proliferative competence of these hepatocytes, but only when injected at specific periods following partial hepatectomy. The injection of calcium 12 to 15 hours after partial hepatectomy induced hepatocytes in the first subpopulation to finish their development and enter mitosis, but did not affect the second, more slowly developing, subpopulation. Calcium had to be injected 25 hours after partial hepatectomy to stimulate proliferation in this second subpopulation. These data suggest that the hepatocytes which became proliferatively incompetent by prolonged exposure to a hypocalcemic environment are proliferatively activated by partial hepatectomy, but their proliferative development stops at a calcium‐dependent stage near the end of the pre‐replicative phase of development.
Maturation of membrane function: Transport of amino acid by rat erythroid cells
Authors: Wise W. C. 
Published: February 2005

AbstractThe membrane changes which occur during cellular maturation of erythroid cells have been investigated. The transport of α‐aminoisobutyric acid, alanine, and N‐methylated‐α‐aminoisobutyric acid have been studied in the erythroblastic leukemic cell, the reticulocyte, and the erythrocyte of the Long‐Evans rat. The dependence of amino acid transport on extracellular sodium concentration was investigated.Erythrocytes were found to transport these amino acids only by Na‐independent systems. The steady state distribution ratio was less than 1. Reticulocytes were found to transport α‐aminoisobutyric acid and alanine by Na‐dependent systems, but only small amounts of N‐methylated‐α‐aminoisobutyric acid. Small amounts of these amino acids were transported by Na‐independent systems. The steady state distribution ratio was greater than one for Na‐dependent transport. The erythroblastic leukemia cell, a model immature erythroid cell, showed marked Na‐dependence (>90%) for α‐aminoisobutyric acid and alanine transport, and >80% for the Na‐dependent transport of N‐methyl‐α‐aminoisobutyric acid. The steady state distribution ratio for the Na‐dependent transport was >4.In the erythroblastic leukemic cell, at least three Na‐dependent systems are present: one includes alanine and α‐aminoisobutyric acid, but excludes N‐methyl‐α‐aminoisobutyric acid; one is for α‐aminoisobutyric acid, alanine and also N‐methyl‐α‐aminoisobutyric acid; and one is for N‐methyl‐α‐aminoisobutyric acid alone. In the reticulocyte, the number of Na‐dependent systems are reduced to two: one for α‐aminoisobutyric acid and alanine; one for N‐methyl‐α‐aminoisobutyric acid. In the erythrocytes, no Na‐dependent transport was found. Therefore, maturation of the blast cell to the mature erythrocyte is characterized by a systematic loss in the specificity and number of transport systems for amino acids.
Exodus of 42K+ and 86Rb+ from rat thymic and human blood lymphocytes exposed to phytohemagglutinin
Authors: Segel George B. , Gordon Bruce R. , Lichtman Marshall A. , Hollander Marsha M. , Klemperer Martin R. 
Published: February 2005

AbstractWe have found that PHA produces an alteration in the lymphocyte membrane which allows 86Rb+ or 42K+ in prelabeled lymphocytes to exchange for cations present in washing solutions. These observations suggested that PHA might induce an increase in the exodus of intracellular potassium during incubation in physiologic media. We, therefore, examined 86Rb+ and 42K+ efflux from rat and human lymphocytes during incubation in tissue culture medium. The rate constant for efflux, Ke, was significantly increased by PHA.86Rb+ efflux was increased by 27% in rat thymic lymphocytes and by 78% in human blood lymphocytes following PHA treatment.
Bromodeoxyuridine induced variations in the level of alkaline phosphatase in several human heteroploid cell lines
Authors: Bulmer Deborah , Stocco Douglas , Morrow John 
Published: February 2005

AbstractThe level of alkaline phosphatase in a number of established cell lines of human origin can be modified by exposure to non‐lethal concentrations of bromodeoxyuridine (BRdU). In the several cell lines examined an inverse relationship between amount of induction and constitutive level of the enzyme was observed. Thus, the H.Ep 2 line, which had the highest basal level of enzyme, was reversibly repressed following exposure to the drug, whereas other cell lines with relatively low constitutive enzyme levels were induced to a maximum of 10‐fold following exposure. Initiation of induction required from 24 to 48 hours, and as short an exposure (“pulse”) as five hours was sufficient to produce induction.Exposure to visible light had no effect upon the repression of alkaline phosphatase in H.Ep 2 by BRdU. Induction did not occur in non‐dividing, serum starved cells. The time course of induction by BRdU and hydrocortisone was similar, and simultaneous exposure of the cells to both agents resulted in no greater induction than that observed with either drug alone.Experiments utilizing mitomycin C yielded significant induction in the presence of this agent alone, and somewhat less induction when both mitomycin C and BRdU were added simultaneously. These results suggest that DNA synthesis is required for BRdU‐mediated induction of alkaline phosphatase.
Substrate‐attached serum and cell proteins in adhesion of mouse fibroblasts
Authors: Culp Lloyd A. , Buniel Josefina F. 
Published: February 2005

AbstractThe effects of serum and coatings of substrate‐attached material (SAM, which remains tightly adherent to the substrate after EGTA‐mediated removal of cells) on the kinetics of attachment of DNA‐radiolabeled BALB/c 3T3, SV40‐transformed 3T3, and concanavalin A‐selected revertant cells to glass coverslips were studied. The presence of serum in the medium of attaching cells had a marked effect on (1) the initial time lag before stable attachment of cells, (2) the maximum level of attached cells, (3) the stability of attachment, and (4) pseudopodial spread of the cell over the substrate. These serum effects could be mimicked by measuring attachment in medium without serum and with use of serum‐preadsorbed or 3T3 SAM‐coated coverslips. Enzymatic treatment of serum‐preadsorbed substrates indicated that the factor(s) in serum which affects attachment is very trypsin‐sensitive. Serum preadsorption of substrates stimulated attachment of SVT2 cells in medium with serum in a manner very similar to the effects of 3T3 SAM coatings, while attachment of 3T3 or revertant cells was unaffected.Slab gel electrophoretic analysis (PAGE‐SDS gels) identified eight major serum proteins by Coomassie blue staining (a) which bind to the substrate in the absence of cells and (b) which persist on the substrate after growth to confluence of 3T3 or SVT2 cells; this suggests that major breakdown of serum‐adsorbed components does not occur during growth of normal or transformed cells. Seven radioactive SAM proteins were detected by autoradiography in 3T3 or SVT2 SAM electropherograms — two of which are high molecular weight components which correspond to the glucosamine‐radiolabeled hyaluronate proteoglycans observed previously; the remaining five are newly‐identified proteins in SAM (one of these proteins appears to be actin). 3T3 and SVT2 cells have unique proportions of these seven components.The data are consistent with the idea that normal or virus‐transformed cells do not attach directly to the culture substrate, but to specific classes of substrate‐adsorbed serum proteins via deposition of specific classes of cell surface proteins and polysaccharides.
Synthesis of immunoglobulin by substrate attached mouse myeloma cells
Authors: Bargellesi Antonio , Damiani Guido , Kuehl W. Michael , Scharff Matthew D. 
Published: February 2005

AbstractCultured mouse myeloma cells grow in suspension and synthesize and secrete large amounts of immunoglobulin. Mouse myeloma cells which attach to a plastic substratum have been obtained by mutagenesis and subsequent selection. Normal mouse myeloma cells will also attach to plastic tissue culture dishes pre‐treated with poly‐L‐lysine. The attached cells synthesize and secrete the same large amounts of immunoglobulin as the suspended cells.
The role of calcium in the inhibition of cAMP accumulation in epiphyseal cartilage cells exposed to physiological pressure
Authors: Bourret L. A. , Rodan G. A. 
Published: February 2005

AbstractA hydrostatic pressure of 60g/cm sq (0.85 psi) inhibits the accumulation of cAMP in cells isolated from the proliferative zone of chick‐tibia epiphyseal cartilage. The following findings indicate that this effect is mediated by a translocation of calcium: (i) the pressure enhances the cellular uptake of radio‐calcium; (ii) the pressure effect on cAMP can be simulated by the calcium‐ionophore A23187; (iii) the effects of pressure and A23187 are non‐additive; (iv) the pressure effect is not produced in the presence of ethylenebis‐(oxyethylenenitrilo)‐tetraacetic‐acid (EGTA); (v) the particulate adenyl cyclase activity of the proliferative zone is susceptible to non‐competitive calcium inhibition.Throughout this study cells from the hypertrophic zone of the same epiphyses were used as controls. In these cells the calcium uptake was enhanced by pressure, but the cAMP level was not affected by pressure, A23187 or EGTA. This change in responsiveness, which accompanies the maturation of the cartilage cells, was shown to be due to a decrease in the calcium‐inhibition of adenylate cyclase.
Unidirectional K+ fluxes in rat thymocytes stimulated by concanavalin A
Authors: Iversen Jens‐Gustav 
Published: February 2005

AbstractUnidirectional K+ fluxes were estimated in isolated rat thymocytes by 42K exchange kinetics. The cells were either preloaded with isotope and the release of it measured during incubation for one hour at 38°C, or the cellular uptake of isotope during a similar incubation was measured.The influx rate of untreated thymocytes was: 2.3·10−12 moles cm −2. S−1 and efflux rate: 1.8·10−12 moles cm −2· S−1·When con A was added to the cells, influx was raised 74% and efflux 65%. Maximal effect was obtained when the concentration of con A was 15 μg/ml, but concentrations as low as 0.75 μg/ml were effective.Hydrocortisone resistant thymocytes responded at least as well as untreated cells to con A, which also raised RNA synthesis rate in the former cells 2.5 times.Using an extracellular marker, 51CrEDTA, intracellular concentrations of some ions was estimated in the thymocytes after one hour incubation: Na+: 30 mmoles/kg water, K+: 177 mmoles/kg water and Cl−: 43 mmoles/kg water. Cellular water content: 69%. These values were not found significantly altered when con A was present.Since con A raised influx and efflux to the same extent and no net flux of K+ could be detected, it is proposed that both active and passive transport of K+ was increased by con A.The increased fluxes induced by con A, can apparently not be reversed by removal of con A from the incubation medium or by addition of the inhibiting hapten, α‐methyl‐D‐mannoside.