bluuebunny/crossref_metadata_2025_split huggingface dataset:
The influence of progressive growth on the specific catalase activity of human diploid cell strains. III. Experiments bearing on the mechanism responsible for change in specific activity
Authors: Pan Yue‐Liang , Krooth Robert S. 
Published: February 2005

AbstractIt was shown previously that the specific catalase activity of human diploid cell strains falls immediately after subculture and then progressively rises in an exponential fashion. In this paper evidence is presented suggesting that the rise in catalase activity cannot be due to an accumulation within the cell of a small molecule which enhances enzyme activity in cell‐free extracts. It is also shown that activity per cell, as well as per unit cell protein, rises as the culture grows.The rate of fall of specific catalase activity immediately after subculture is greater if the cells are at a low population density than if they are at a high one. The rate of fall can be made more sharp by increasing the frequency with which the cultures are fed.It is shown that used medium, which has previously been incubated with cultured cells of the same strain, does not significantly change either the rate of fall of specific catalase activity following subculture, or the rate of its subsequent rise. It is postulated, as one possibility, that the cells liberate into the medium an enhancer of cell catalase activity which is highly labile. The steady state concentration of this enhancer in the medium might be expected to increase as the culture grew, but to decrease when the cells are subcultured into fresh medium or when the frequency of feedings is increased.
Sugar penetration into human blood platelets
Authors: McDonagh R. P. , Burns M. J. , Delaimi K. E. , Faust R. G. 
Published: February 2005

AbstractThe relative rates of penetration of pentoses and hexoses into human blood platelets were studied with a photoelectric densimeter. It was concluded that pentoses enter human platelets by free diffusion whereas hexoses penetrate into these cells by an altered diffusion process.
Membrane glycoprotein biosynthesis: Changes in levels of glycosyl transferases in fibroblasts transformed by oncogenic viruses
Authors: Bosmann H. Bruce , Hagopian Arpi , Eylar E. H. 
Published: February 2005

AbstractFibroblasts transformed by oncogenic viruses were found to have greater enzymic activities of four membrane glycoprotein:glycosyl transferases on a cell or protein basis then two non‐transformed fibroblastic lines. These enzymes are responsible for the synthesis of membrane glycoproteins; each of the four transferases studied, the polypeptide:N‐acetylgalactosaminyl, glycoprotein:galactosyl, fetuin:fucosyl and PSM:fucosyl transferases, was more than twice as active in the transformed cell lines using both endogenous and added receptor. The most pronounced differences occurred with the doubly (SV‐PY‐3T3) transformed fibroblasts in all cases; with the N‐acetylgalactosaminyl and galactosyl transferases the increase was 8–16 fold over the non‐transformed cells. It was demonstrated that these results do not arise from a changed level of glycosidase activities.
Optimal oxygen tension for human lymphocytes in culture
Authors: Andersen V. , Hellung‐Larsen P. , Sørensen S. F. 
Published: February 2005

AbstractHuman lymphocytes stimulated with phytohaemagglutinin in vitro show maximal 14C‐thymidine incorporation when the gas phase of the cultures contains 20% O2. The rate of DNA synthesis is more affected by hyperoxic conditions than by hypoxia. Cell viability, defined by dye exclusion, is considerably less dependent on pO2 than is cellular replication.
The metabolism of pyrimidine compounds by Tetrahymena pyriformis
Authors: Wykes J. R. , Prescott D. M. 
Published: February 2005

AbstractThe pyrimidine requirements for growth of T. pyriformis and for reversal of the growth inhibition caused by folate deprivation have been studied. The effects of thymidine and 5‐fluorodeoxyuridine have been shown to be quantitatively different from the effects of these compounds on growth and the rate of DNA synthesis in mammalian cells. Labelled nucleosides added to the medium have been found to be converted to the corresponding bases with the exception of deoxycytidine, which is first deaminated to deoxyuridine. As a result no deoxynucleosides other than thymidine specifically label DNA.The results allow deductions to be made concerning the enzymes involved in pyrimidine utilization by this organism. It is suggested that pyrimidine utilization is always channeled through uracil in the case of those compounds that can supply the pyrimidine requirement for growth.
The dilution factor of intravenously injected hemopoietic stem cells
Authors: Matioli Gastone , Vogel Helmut , Niewisch Helgard 
Published: February 2005

AbstractIn order to measure the total number of stem cells present in a given preparation, it is necessary to know the fraction of stem cells which settle in the spleen and form macroscopically visible colonies. The intravenous injection does not allow a direct measurement of this fraction. However, its value is established by injecting stem cells directly into the spleen, thus minimizing the dilution of stem cells through the circulation. It has been measured with this procedure, that only 4% of intravenously injected stem cells form spleen colonies.
The continued requirement for inducer for the development of macrophage and granulocyte colonies
Authors: Paran Michael , Sachs Leo 
Published: February 2005

AbstractRat bone marrow cells were seeded as mass cultures or for cloning together with inducer required for colony formation, and at various times after seeding, the cells were re‐seeded for cloning either with or without inducer. The results indicate that the development of both macrophage (M) and granulocyte (G) colonies requires a continued supply of the inducer. No M or G colonies were produced when the inducer was replaced by erythropoietin.
The single cell origin of normal granulocyte colonies in vitro
Authors: Paran Michael , Sachs Leo 
Published: February 2005

AbstractIt has been shown by re‐cloning of colonies formed in vitro from rat bone marrow cells, that normal granulocyte colonies can originate from single cells. No mixed macrophage (M) and granulocyte (G) colonies were obtained after re‐cloning either M or G colonies. The results indicate, that clones of normal granulocytes and macrophages can be obtained in vitro, and that the mixed primary M and G colonies formed after seeding hematopoietic cells from animals presumably originate from a mixture of M and G cells.
Effect of exogenous ATP on the volume of TA3 ascites tumor cells
Authors: Stewart Carleton C. , Gasic Gabriel , Hempling Harold G. 
Published: February 2005

AbstractWhen exogenous ATP is added to suspensions of TA3 ascites tumor cells suspended in Ca++ and Mg++ free media, a significant increase in cell volume can be measured. This increase is reversible upon addition of Ca++ and/or Mg++ back to the media.The enlargement of these cells is temperature sensitive and specific for ATP; no other nucleotides, EDTA or ouabain were effective. The evidence suggest that this phenomena may be due to an alteration in membrane permeability and that the regulation of membrane permeability is an energy dependent process.
The effect of exogenous ATP on the electrolyte content of TA3 ascites tumor cells
Authors: Hempling H. G. , Stewart Carleton C. , Gasic Gabriel 
Published: February 2005

AbstractIn the presence of 1 mM ATP in the external medium, TA3 mouse ascites tumor cells showed a dramatic loss of potassium and gain of sodium down their respective concentration gradients. The volume changes detected by size discrimination with the Coulter counter have been adequately confirmed by densimetric techniques. Further, some experiments were so designed that net losses of both ions occurred and the cell shrank in response to ATP, a response which was predictable if the volume change was produced by a loss of cell water. We believe that ATP produces a major change in the passive permeability of the membrane to these ions and the effect may be due to a response of a contractile protein in the membrane to ATP.
Development of the mouse hematopoietic system. II. Estimation of spleen and liver “stem” cell number
Authors: Barker Jane E. , Keenan Mary Ann , Raphals Lisa 
Published: February 2005

AbstractColony‐forming cells (CFU), which have the general properties of hemopoietic “stem” cells, appear to be augmented in the mouse fetal liver from 12–18 days gestation and then decrease in the newborn. This finding suggests that few, if any, hemopoietic “stem” cells remain in the adult liver, an organ which appears to be unable to function erythropoietically, even at times of severe crises. In the spleen, and active adult as well as embryonic hematopoietic organ, the total number of CFU increases from 18 days gestation until at least 7 days after birth.Spleen and liver CFU augmentation seems to occur in cojunction with an analogous expansion of non‐hematopoietic cells. The data suggests, in fact, that while there is an increase in the total number of liver CFU, there is also a dilution of liver CFU in the total cell population at successively later gestational ages.
Discrepancies between precursor uptake and DNA synthesis in mammalian cells
Authors: Smets L. A. 
Published: February 2005

AbstractThe incorporation of tritiated thymidine and deoxycytidine into DNA of x‐irradiated mammalian cells was studied. Both inhibition and stimulation were found due to pool changes rather than to effects on DNA synthesis, indicating that precursor uptake can be a misleading method to measure DNA synthesis rate.
Mitochondrial damage and inhibition of respiration in animal cell cultures treated with Triton WR‐1339
Authors: Zimmerman Eugene M. , Vaituzis Zigfridas , Hetrick Frank M. 
Published: February 2005

AbstractInhibition of cellular respiration by treatment with the nonionic detergent Triton WR‐1339 was found to be related to the cytotoxic response of cell to the surfactant. Respiration of sensitive cell lines (AV‐3 and HeLa) markedly inhibited by Triton concentrations as low as 125 μgm/ml. Conditionally sensitive lines (BHK‐21 and L‐929) were affected by 500 μgm/ml while the respiration of insensitive cultures (primary rat and chick embryo cells) was unaffected by this concentration. Macrocyclon, a cyclic analogue of Triton, failed to alter the respiration rate of any of the above cell cultures.The levels of isocitric and succinic dehydrogenases in sensitive and conditionally sensitive cells were depressed within 2 hours after treatment with 500 μgm/ml of Triton was initiated and by 6 hours the activity was only 25% of the untreated controls. Similar results were obtained with mitochondrial preparations from these cells. Enzyme levels in insensitive cells were unaffected by Triton treatment.Mitochondrial damage was the most striking characteristic noted in treated cells examined by electron microscopy. The mitochondria were quite distorted and had lost most of their cristae formation. This mitochondrial damage was seen in all cell types examined although the rate at which it occurred varied. With sensitive cultures, damage was pronounced within 6 hours after the addition of Triton while mitochondria from conditionally sensitive cells were not grossly affected until 48 hours and they appeared to repair the damage following the removal of Triton.
Curves of osmotic fragility calculated from the isotonic areas and volumes of individual human erythrocytes
Authors: Canham Peter B. 
Published: February 2005

AbstractTheoretical osmotic fragility curves were calculated and drawn by computer using the van't Hoff equation and the isotonic areas and volumes of 1000 individual erythrocytes. We studied the influence on the calculated curves of theoretically altering the fraction of the volume which was osmotically active from 50 to 70%, and of altering the permissible stretch before hemolysis from zero to 10%. With the two assumptions–that the membrane does not stretch before hemolysis, and that the osmotically active fraction of the cell volume is 0.58–it was possible to duplicate the general shape of the standard fragility curve; the exact NaCl concentration, however, at which there was 50% hemolysis was approximately 0.1 gm/100 ml higher than found in vitro. The calculated osmotic fragility curves can be made quantitatively similar to in vitro ones if the following statements are true: the osmotically active volume is 58%, the permissible stretch of the membrane without lysis is 6%, the cell membrane resists a slight osmotic pressure gradient of approximately 0.1 atmospheres, and hemolysis is an all or nothing phenomenon. This set of values for the relevant factors is sufficient but not unique in causing the superposition of the calculated and experimental curves. The frequency distribution of the cells according to the hemolytic salt concentrations (the sodium chloride concentration at which an individual cell just hemolyzes) was skewed positively and was leptokurtic for each of the seven normal subjects studied.
Hemoglobin and ferritin synthesis in erythroid cells in prolonged marrow cell cultures
Authors: Gabuzda Thomas G. , Silver Ruth K. , Melvin Mary , Windus Constance , Sachs Carl 
Published: February 2005

AbstractA method is described which maintains viable erythroid cells in tissue culture for periods from nine to twenty days. These cells appear predominantly as small round cells with scanty cytoplasm. They synthesize both heme and globin and are relatively more numerous free in suspension than in the adherent monolayer. Ferritin isomorph may serve as a convenient marker in tissue culture of cells of erythroid origin, suggesting that such cells may persist despite a completely transformed appearance and a loss of the ability to produce hemoglobin.
Studies on colony formation in vitro by mouse bone marrow cells. I. Continuous cluster formation and relation of clusters to colonies
Authors: Metcalf Donald 
Published: February 2005

AbstractColony formation in vitro by mouse bone marrow cells following stimulation by human urine was analysed over a 7‐day incubation period. There was a linear increase with time in the number of cell aggregates (clusters) developing in such plates. Early in the incubation period all clusters were granulocytic although later macrophage clusters developed. Although most fully developed colonies were composed of macrophages, mapping and transfer studies showed that at least half of these had initially arisen early in the incubation period as granulocytic clusters.
Control of multiplication of uninfected rat cells and rat cells converted by murine sarcoma virus
Authors: Temin Howard M. 
Published: February 2005

AbstractThe rate of multiplication of rat embryo fibroblasts in monolayer culture depends upon the amount of multiplication‐stimulating activity in the culture medium, as well as the efficiency of stimulation by and utilization of this activity. Multiplication‐stimulating activity is defined by its capacity to stimulate DNA synthesis and cell division in stationary populations of cells. Usually, multiplication stimulating activity is supplied as serum in cell culture media, but rat cells also produce it.A comparison of multiplication of uninfected and Murine Sarcoma virus‐converted rat cells showed that converted cells multiplied at a greater rate than did uninfected cells, with the use of less or the same amount of multiplication‐stimulating activity; the converted cells produced cells produced an inhibitor of multiplication‐stimulating activity, and the efficiency of stimulation of DNA synthesis was similar for uninfected and converted cells. It appears that in the presence of serum the efficiency of utilization of multiplication‐stimulating activity is greater for converted cells than for uninfected rat cells.
Nuclear alterations in mammalian cells induced by L‐canavanine
Authors: Hare J. D. 
Published: February 2005

AbstractMammalian cells treated four hours with the L‐arginine analogue, L‐canavanine (Cana), develop alterations in nuclear architecture characterized by the formation of irregular aggregates of nucleoplasmic contents, frequently attached to the nuclear membrane. On the basis of previous studies showing that Cana is incorporated into nuclear proteins and inhibits DNA synthesis over similar periods of exposure, it is postulated that the formation of canavanyl protein‐DNA aggregates interfere with DNA replication.
Evidence for the existence of multipotential lympho‐hematopoietic stem cells in the adult rat
Authors: Nowell Peter C. , Hirsch Bruce E. , Fox Dianne H. , Wilson Darcy B. 
Published: February 2005

AbstractRats were given near‐lethal doses of x‐ray to produce clones of hemic cells marked by radiation‐induced chromosome abnormalities. Subsequently, bone marrow from these rats was injected into lethally irradiated mice to form erythropoietic spleen colonies; and peripheral blood lymphocytes from the same rats were stimulated to proliferate in a mixed lymphocyte interaction (MLI), an immunological response to histocompatibility isoantigens.Chromosome markers indicated that in several instances the cells of an erythroid spleen colony and a proportion of the lymphocytes reacting in the MLI were progeny of the same stem cell in the donor rat. In addition, lymphocytes of the same radiation‐marked clone were shown to proliferate in response to several different histocompatibility isoantigens. The data indicate the presence in the adult rat of a primitive lymphohematopoietic stem cell capable of yielding both erythroid and lymphoid progeny. The findings also suggest that immunological specificity is determined during lymphoid differentiation, subsequent to the stem cell stage.
Density distribution analysis of In vivo and In vitro colony forming cells in developing fetal liver
Authors: Moore M. A. S. , McNeill T. A. , Haskill J. S. 
Published: February 2005

AbstractThe technique of buoyant density separation in gradients of Bovine Serum Albumin has been used to separate in vivo and in vitro colony forming cells (C.F.C.'s) in hemopoietic tissue of mouse fetal liver. Differences in the density distribution profiles showed that the in vivo and in vitro C.F.C.'s were different cell populations but the existence of an “out‐of‐phase” density association suggested that the two cell types were closely related.Complex density heterogeneity of both cell populations was observed at later stages of liver development and was similar to that seen in adult marrow. A homogeneous population of in vivo and in vitro C.F.C.'s occupied a very light density position in 10.5 day fetal liver. The subsequent development of density heterogeneity was associated with progressive acquisition of higher density subpopulations. Transfer experiments showed the capacity of the lightest density cells from the earliest stage of liver hemopoiesis, to generate higher density colony forming cells in the environment of the adult marrow. Density determined differences in seeding efficiency of in vivo C.F.C.'s were observed but no evidence was obtained for differences in either in vivo or in vitro colony morphology in different density subpopulations.
Calcium transport and distribution in ehrlich mouse ascites tumor cells
Authors: Levinson Charles , Blumenson Leslie E. 
Published: February 2005

AbstractData from isotopic uptake experiments were used to measure calcium fluxes and compartment sizes in ascites tumor cells. The data were analyzed with two kinetic models, A and B. In 80% of the experiments model A, which is based on one exchangeable calcium compartment, was rejected in favor of Model B, which predicts two exchangeable compartments. A statistical evaluation of the model's performance, when fit to the experimental data was used to select between the two models.The results show that calcium was distributed between three cellular compartments in the ratio, non‐exchangeable (88%): rapidly exchanging (7%): slowly exchanging (5%). The undirectional fluxes suggested that calcium transport could be described as a series system with the temporal sequence: environment ⇄ rapidly exchanging ⇄ slowly exchanging.
The interaction of mengo virus ribonucleic acid with L, HeLa and human diploid cells: A comparative study
Authors: Tovell Dorothy R. , Garbutt Elizabeth W. , Yaremko Louise , Colter John S. 
Published: February 2005

AbstractA study, designed to define the optimal conditions for infecting L, HeLa and human diploid cells with Mengo RNA, showed that the three cell types differ with respect to (a) the concentration of sucrose (in PBS) that produces maximum stimulation of infectious center (I.C.) formation (0.6 M, 1.2 M and 1.0 M for L, HeLa and human diploid cells respectively) and (b) the optimal combination of sucrose and dimethyl‐sulfoxide (DMSO). With all three cell types, diethylaminoethyldextran (DEAE‐D) was found to produce maximum stimulation of I.C. formation when present, in PBS, at a concentration of 100 μg/ml. Direct comparisons of I.C. formation in the three cell types using the sucrose, sucrose‐DMSO and PBS‐DEAE‐D media optimal for each revealed that (a) the best medium for titration in L and HeLa cells is PBS containing 100 μg DEAE‐D/ml, (b) DMSO produces a 4–8 fold increase in I. C. formation in L cells, but is only marginally effective in HeLa cells, and (c) the optimal medium for titration in human diploid cells is sucrose‐DMSO. The results of studies of the “uptake” of 3H‐Mengo RNA showed that there is no correlation between the amount of RNA that becomes cell associated and the number of I.C.'s that are produced in the cell population.
A kinetic study of the genetic control of hemopoietic progenitor cells assayed in culture and In vivo
Authors: Sutherland D. J. A. , Till J. E. , McCulloch E. A. 
Published: February 2005

AbstractThe kinetics of growth of bone marrow cells from normal or genetically anemic mice (Sl/Sld and W/Wv) were studied in irradiated normal and genetically anemic hosts. The parameters followed included total cellularity, the number of peroxidase positive cells, and the number of cells capable of forming colonies in vivo (CFU‐S) or in culture (CFU‐C). The results of these experiments demonstrate that W and Sl defects alter the growth of CFU‐C and peroxidase‐positive cells to a modest degree; that the defects are more obvious when studied in spleen rather than in bone marrow; and that there is no additivity of W and Sl defects.Nineteen irradiated recipients of marrow from W/Wv mice were studied after three to six months. Of these, 18 showed host‐type erythrocytes, while in one mouse the erythrocytes had the size distribution of W/Wv cells. This finding indicated that occasionally genetically defective stem cells may repopulate irradiated hosts.
Beneficial effects of embryo extract on cultured rabbit cartilage cells
Authors: Ham Richard G. , Murray Louann W. , Sattler Gerald L. 
Published: February 2005

AbstractGrowth and the expression of cartilage‐like differentiation by adult rabbit chondrocytes is stimulated greatly by the Sephadex G‐25 macromolecular fraction of chicken embryo extract (CEEM). A small amount of fetal bovine serum or the macromolecular fraction of fetal bovine serum (FBSM) is also needed for growth. Medium F12 supplemented with CEEM plus FBSM supports moderate clonal growth of the rabbit chondrocytes with excellent expression of differentiated properties. The effects of CEEM on growth and the expression of differentiation have been quantitated by measurement of radioactive sulfate incorporation and total protein synthesis.