bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fidelity of protein synthesis does not decline during aging of cultured human fibroblasts
Authors: Wojtyk Roman I. , Goldstein Samuel 
Published: February 2005

AbstractTo ascertain whether the fidelity of protein synthesis declines during cellular aging in vitro, we have developed a cell‐free protein synthesizing system from cultured human fibroblasts which actively incorporates phenylalanine into acid‐insoluble material upon addition of poly (U). The accuracy of poly(U)‐directed protein synthesis was determined by comparing the ratio of leucine to phenylalanine incorporation in extracts of early‐ and late‐passage fibroblasts derived from normal persons and from subjects with two genetic disorders of premature aging, progeria, and Werner syndrome. The results show no decline in translational fidelity at late passage or in prematurely aging cells, and thus fail to support the error catastrophe theory of cellular aging.
Self‐maintenance capacity of CFU‐S
Authors: Schofield R. , Lord B. I. , Kyffin S. , Gilbert C. W. 
Published: February 2005

AbstractThe numbers of CFU‐S which developed in spleen colonies were measured 11 days after injection of irradiated mice with marrow from normal mice or mice which had been treated in one of a variety of ways. The broad spread of CFU‐S numbers, seen by other authors, in colonies derived from normal marrow was confirmed. However, the range and distribution of CFU‐S per colony was generally different in colonies derived from the marrow of mice which were recovering or had recovered from some form of depopulation. From the data obtained, the mean CFU‐S/colony, M1, and the probability of self‐renewal, p, of the CFU‐S were calculated. These values are used to calculate the number of cell cycles undergone during development of the colony and, by making certain assumptions, the cell cycle time of the CFU‐S. The plot of p against log M for the various samples measured should be linear if all CFU‐S proliferate at the same rate in a growing colony. It is not linear, however, so that CFU‐S obtained under different experimental conditions do not all undergo the same number of cycles. In general, treatments given to the mice result in a lowering of the capacity for self‐renewal of their CFU‐S and also to a shortening of their cell cycle time. Some of the possible implications of these findings are discussed.
Effects of linoleic acid on capping, lectin mediated mitogenesis, surface antigen expression, and fluorescent polarization in lymphocytes and BHK cells
Authors: Hoover Richard L. , Bhalla Deepak K. , Yanovich Saul , Inbar Michael , Karnovsky Morris J. 
Published: February 2005

AbstractThe incubation of linoleic acid with cells causes profound effects on membrane associated phenomenon. Using the fluorescent probe diphenyl hexatriene (DPH) to monitor lipid changes in the microenvironment of the cell surface, we find that linoleic acid reduces the polarization values (P) in mouse lymphocytes and BHK cells. Measurements on lipids extracted from the cells grown in linoleic acid produce similar results. We also find in the mouse lymphocyte that capping of Ig is inhibited and con A stimulated mitogenesis is unaffected. In contrast to the latter effect, LPS and PHA stimulated mitogenesis is inhibited and in the rat lymph node, con A stimulated mitogenesis, greatly enhanced. We also show that linoleic acid alters the binding of antibodies to the cell surface of EL‐4 lymphoma cells. These observations suggest that linoleic acid alters cellular function by interfering with protein/lipid interactions within the surface membrane.
Water permeability of mammalian cells as a function of temperature in the presence of dimethylsulfoxide: Correlation with the state of the membrane lipids
Authors: Rule G. S. , Law P. , Kruuv J. , Lepock J. R. 
Published: February 2005

AbstractThe water permeability of V‐79 Chinese hamster lung fibroblasts was determined by measuring the rate of cell shrinkage in hypertonic medium using a cell sizer. The water permeability appears to follow Arrhenius kinetics as a function of temperature with a sharp discontinuity at 21°C. An activation energy of 7.0±1.6 kcal/mole was found below 21°C and 22.8±3.1 kcal/mole above 21°C. The correlation time of rotation of the spin label 2,2‐dimethyl‐5‐dodecyl‐5‐methyloxazolidine‐N‐oxide was measured as a function of temperature in the cellular membranes, and shows a break at 20°C. A discontinuity was also found in the membrane to water partitioning of the spin label 2,2‐dimethyl‐5‐pentyl‐5‐butyloxazolidine‐N‐oxide near 20°C. These breaks may correspond to a membrane lipid phase transition. Dimethylsulfoxide, in the concentration range of 0.2–0.5 M, decreases the water permeability by a factor of two.
Differential effect of interferon on DNA synthesis, 2‐deoxyglucose uptake and ornithine decarboxylase activity in 3T3 cells stimulated by polypeptide growth factors and tumor promotors
Authors: Sreevalsan T. , Rozengurt E. , Taylor‐Papadimitriou J. , Burchell J. 
Published: February 2005

AbstractQuiescent 3T3 cells can be stimulated to enter S by defined factors. When used in combination, three polypeptide hormones (EGF, vasopressin, and insulin), or a tumor promotor and insulin, are very effective in stimulating DNA synthesis. Like serum, the defined factors also stimulate deoxyglucose uptake and induce the synthesis of ornithine decarboxylase during G1. The second stage of deoxyglucose uptake and the induction of ornithine decarboxylase are protein synthesis‐dependent events. When added with the growth factors, mouse interferon inhibits the synthesis of DNA and the induction of ornithine decarboxylase but has no effect on the uptake of deoxyglucose. Kinetic experiments comparing the effect of inhibitors of translation or transcription on induction of ornithine decarboxylase with the effect of interferon suggest that interferon may affect the synthesis of enzyme by inhibiting both transcription and translation of message. The findings provide further support for the proposition that interferon exerts a differential effect on mitogen‐stimulated events which are dependent on continuous protein synthesis.
X‐ray‐induced production of granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) by mouse spleen cells in culture
Authors: Onoda M. , Shinoda M. , Tsuneoka K. , Shikita M. 
Published: February 2005

AbstractSpleen cells were collected from normal mice and cultured in a medium containing 20% calf serum. Addition of lipopolysaccharide (LPS) in the culture significantly increased the production of granulocyte‐macrophage colony‐stimulating factor (GM‐CSF), and a maximum induction was attained in 5 days. Irradiation of the spleen cells with 300 to 3,000R X‐rays also enhacned the production of GM‐CSF, but there was a latent period of about 5 days before the factor appeared in the culture medium. The observed difference between LPS and X‐rays in the timing of inducing GM‐CSF production in the spleen cell culture was consistent with the difference in timing of the increase of spleen cell proliferation observed in animals after the administration of LPS or during recovery from damages by X‐irradiation. It was observed furthermore that the X‐ray‐induced GM‐CSF differed from the LPS‐induced GM‐CSF in its molecular properties; the X‐ray‐induced factor was represented by an acidic (pI=3.0) 70,000‐dalton species, while the LPS‐induced factor was much smaller in size (M.W. 20,000) and less acidic (pI=5.4). These results suggest that different mechanisms of GM‐CSF production operate in the spleen in response to either LPS or X‐rays.
Cyclic AMP levels in migrating and non‐migrating newt epidermal cells
Authors: Dunlap Mary K. 
Published: February 2005

AbstractCyclic AMP (cAMP) levels were measured in 8‐hour migrating wound epithelial and non‐migrating epithelial cells of the newt. Tissues were collected in vivo and in vitro with and without epidermal‐dermal separation by collagenase. Regardless of manner of collection and treatment, cAMP levels were always significantly higher in the migrating cells. Levels were also measured in 28‐hour and 36‐hour wound epithelia. There was a progressive decline in levels in wound epithelia between 8, 28, and 36 hours, suggesting that levels were in the process of returning to normal. When cells were treated with a dose of cAMP and theo‐phylline previously shown to inhibit migration, levels of cAMP were much higher than any migrating epithelium. The fact that cAMP inhibits migration, yet migrating cells have higher cAMP levels, seems contradictory at first, but possible explanations are advanced to account for the apparent discrepancy.
Sugar transport in the LLC‐PK1 renal epithelial cell line: Similarity to mammalian kidney and the influence of cell density
Authors: Mullin James M. , Weibel Josef , Diamond Leila , Kleinzeller Arnost 
Published: February 2005

AbstractCells of confluent cultures of the established pig renal epithelial line, LLC‐PK1, accumulate α‐methyl‐D‐glucoside against a concentration gradient. This transport system is strongly inhibited by phlorizin and 6‐deoxy‐D‐glucose, moderately inhibited by phloretin, and only weakly inhibited by 3‐0‐methyl‐D‐glucose, paralleling the situation in mammalian kidney. The time course for the uptake of α‐methyl‐D‐glucoside and for the carrier‐mediated but passive uptake of 3‐0‐methyl‐D‐glucose are identical to those seen in mammalian kidney. Subconfluent cultures of LLC‐PK1 cells are unable to accumulate α‐methyl‐D‐glucoside, and their transport of this glucose analog is less sensitive to phlorizin inhibition than is the transport system in confluent cultures. Transmission electron micrographs show that cells from subconfluent cultures lack the microvillous surface seen in cells from confluent cultures. Cell density is thus a factor in the occurrence of structural and functional differentiated properties related to transport in these cells.
Lactate: A major product of glutamine metabolism by human diploid fibroblasts
Authors: Zielke H. Ronald , Sumbilla Carlota M. , Sevdalian David A. , Hawkins Robert L. , Ozand Pinar T. 
Published: February 2005

AbstractHuman diploid fibroblasts metabolize up to 13% of the glutamine in tissue culture medium to lactate. Four μCi of glutamine‐U‐14C were added to media containing 5 mM or 65 μM glucose or medium containing no added glucose, but supplemented with purine and pyrimidine nucleosides (HGTU). Aliquots of the media were taken at daily intervals and were assayed for glucose, lactate, pyruvate, malate, citrate, aspartate, glutamine, and glutamate. The label incorporation into these compounds was determined, except for glutamine and glucose. The distribution of label from glutamine‐U14C in 5 mM glucose medium by day 4 was lactate (10.2%), glutamate (15.2%), citrate (1.9%), pyruvate (2.0%), malate (1.1%), and aspartate (< 0.1%). The accumulation of label in lactate and glutamate occurred continuously during the growth cycle. Malate, citrate, and aspartate accumulation occurred primarily in confluent cultures. The label in aspartate was seen only in stationary phase cells or when the glucose concentration was decreased to 65 μM or less; net aspartate accumulation was increased twofold in low glucose media. These data demonstrate an actively functioning pathway for the conversion of 4‐carbon TCA‐cycle intermediates to 3‐carbon glycolytic intermediates in human diploid fibroblasts.
Temperature dependent expression of polyoma virus in murine embryonal carcinoma cells
Authors: Dandolo L. , Vasseur M. , Kress C. , Aghion J. , Blangy D. 
Published: February 2005

AbstractAt 37°C, undifferentiated murine teratocarcinoma cells (PCC4) are resistant to infection with SV40 and Polyoma virus. When infection is carried out at 31°C, these cells become fully susceptible to a variety of polyoma virus strains, including wt, ts‐a, and hr‐t; they also display an increased susceptibility to polyoma virus mutants (PyE.C.) which have been selected for their ability to develop in PCC4 cells at 37°C (Vasseur et al., '80). However, expression of SV40 is still restricted at 31°C and no T antigen can be detected. PCC4 cells grown at 31°C express the characteristic embryonal surface antigen(s), but no H2 antigen, and do not produce plasminogen activator.PyE.C. mutants and other polyoma virus strains cannot develop at 37°C in nullipotent F9 embryonal carcinoma cells and restriction is not abolished at 31°C.The results indicate that: (i) Resistance of PCC4 cells to polyoma virus and to SV40 are not mediated by the same process; (ii) loss of restriction of polyoma in PCC4 cells does not require cell differentiation; (iii) F9 and PCC4 cells control polyoma virus expression through different mechanisms.
Differentiation and production of colony‐stimulating factor induced by immunostimulants in a leukemia cell line
Authors: Maeda Michiyuki , Ichikawa Yasuo , Azuma Ichiro 
Published: February 2005

AbstractImmunostimulants from various microorganisms were tested on a myeloid leukemia cell line (Ml) for the ability to induce production of CSF and to cause differentiation of these cells. Based on their activities, the compounds were divided into two general classes: those inducing extensive cellular differentiation and those devoid of this effect. The stimulants which were active in this regard always produced large quantities of CSF, whereas those devoid of a differentiating effect did not cause CSF production. Even the potent stimulants had no effect on the D− subline, in which the differentiation was not inducible.
Expression of the teratocarcinoma phenotype in hybrids between totipotent mouse teratocarcinoma and myeloma cells
Authors: Correani Alessandro , Croce Carlo M. 
Published: February 2005

AbstractWe have produced somatic cell hybrids between totipotent mouse teratocarcinoma and myeloma cells. These hybrids behave like the teratocar‐cinoma cell parent and express teratocarcinoma embryonal antigens. However, they also express the myeloma H‐2 antigens. The availability of these hybrids should make it possible to study the expression of already rearranged immunoglobulin genes during mouse development.
Growth response to insulin in mouse melanoma cells and fibroblast × melanoma hybrids
Authors: Coppock Donald L. , Covey Lori R. , Straus Daniel S. 
Published: February 2005

AbstractPG19 mouse melanoma cells arrest growth when they become confluent in medium containing low concentrations of serum. Under these conditions, insulin does not stimulate DNA synthesis in the mouse melanoma cells, whereas it does in mouse embryo fibroblats and fibroblast × melanoma hybrids. A detailed examination of the binding of insulin to the melanoma cells and fibroblast × melanoma hybrids in the presence of bacitracin has shown that they have approximately equal numbers of insulin receptors, and that these receptors have similar affinities for insulin. These results indicate that the unresponsiveness of the melanoma cells to the mitogenic action of insulin is not attributable to a lack of insulin receptors. Although insulin does not stimulate incorporation of 3Hthymidine into DNA in confluent cultures of the melanoma cells, it does stimulate uptake of α‐aminoisobutyrate, indicating that the insulin receptors are functional and that insulin elicits an acute response in these cells. In hormone‐supplemented serum‐free medium, insulin does not stimulate growth of the melanoma cells, while it does stimulate growth of the fibroblast × melanoma hybrid. This suggests that an acute response to insulin is not sufficient for stimulation of growth either in confluent growth‐arrested cells or in exponentially growing cells in serum‐free medium.
Vasopressin rapidly stimulates NA entry and NA‐K pump activity in quiescent cultures of mouse 3T3 cells
Authors: Mendoza Stanley A. , Wigglesworth Noel M. , Rozengurt Enrique 
Published: February 2005

AbstractAddition of (Arg) vasopressin to quiescent cultures of Swiss 3T3 cells rapidly stimulates an ouabain‐sensitive 86Rb uptake. In contrast the hormone has no significant effect on the rate of efflux of this cation from preloaded cells. The stimulation of 86Rb uptake is cycloheximide‐insensitive, occurs within minutes of hormone addition and results from an increase in the Vmax of the uptake system. Vasopressin stimulates ion uptake in a concentration‐dependent fashion (1‐100 ng/ml); oxytocin also stimulated the Na‐K pump but at significantly higher concentrations. The stimulation of the Na‐K pump by vasopressin is apparently mediated by an increase in Na entry into the cells, since the hormone (1) strikingly shifts the concentration dependence on Na+ of the Na‐K pump, (2) increases 22Na uptake, and (3) increases intracellular Na contents when the efflux of this ion is blocked by ouabain. Since vasopressin is a potent mitogen for Swiss 3T3 cells, the results provide further evidence in support of a possible role of monovalent ion fluxes in signalling the initiation of growth stimulation.
Intracellular analysis of sodium, potassium, and chloride in mouse erythrocytes
Authors: Benos D. J. 
Published: February 2005

AbstractRecently, Cameron et al. ('79) published measurements of intracellular solute amounts (expressed as mmoles per kilogram dry cell solids) obtained by energy dispersive electron probe microanalysis in different rodent tissues. In this communication, I wish to compare Cameron et al.'s ('79) erythrocyte values of Na, K, and Cl with those I have made using more conventional techniques of elemental analysis. This comparison is necessitated by Cameron et al.'s ('79) observation of extremely high intracellular sodium levels. If their findings are accurate, the possibility of a polymorphism with respect to intracellular Na levels therefore presents itself. If a polymorphism between different inbred strains of mice exists, and if, as in ruminants, this trait has a genetic basis, an examination of the genetic aspects of the control, differentiation, and the ultimate expression of the ion transport mechanisms responsible would undoubtedly provide insight into the molecular basis as well as the adpative dynamics of transport systems in general.
Oxidation of glucose by mouse peritoneal macrophages: A comparison of suspensions and monolayers
Authors: Lazdins Janis K. , Koech Davy K. , Karnovsky Manfred L. 
Published: February 2005

AbstractMacrophages, when maintained in vitro, take up glucose from the medium and oxidize it to CO2. The rate of oxidation of glucose varies considerably, depending on the physical state of the cell preparation. Cells in suspension oxidize glucose at a level six‐fold that of cells in monolayers. The differences cannot be attributed to change in the rates of transport of glucose. On the other hand, an increse in intracellular glycogen (about three‐fold) and free glucose plus glucose‐6‐P (many‐fold) was found in the cells prepared as monolayers. During subsequent incubation with glucose‐14C, this could be the cause of an isotope dilution effect and could explain the lower production of 14CO2 by the adherent cells. Since oxidation of glucose‐1‐14C to 14CO2 is used by many investigators to indicate the functional state of macrophages, we suggest close attention be paid to the system used, i.e., monolayers vs. suspensions.
Enzyme induction in a temperature‐sensitive cell cycle mutant of chinese hamster fibroblasts
Authors: Landy‐Otsuka Fyllis , Scheffler Immo E. 
Published: February 2005

AbstractA temperature‐sensitive (ts) cell cycle mutant of Chinese hamster fibroblasts with a block in G1 was investigated. Attention was on the expression of the activity of three enzymes: ornithine decarboxylase (ODC), S‐adenosylmethionine decarboxylase (SAMDC), and thymidine kinase (TK). ODC and SAMDC activities are normally induced in the middle of, or late in, the G1 phase, while TK activity starts to appear at the G1/S boundary. In the ts mutant released from serum starvation at the nonpermissive temperature (40.8°C), we find no effect on the expression of SAMDC activity, a significantly reduced level of ODC activity compared to the control at the permissive temperature (34°C), and no induction of TK activity. Results presented here and in a previous publication (Landy‐Otsuka and Scheffler, '78) suggest that the decrease in ODC activity is due to an effect of the nonpermissive temperature on a post‐transcriptional step, possibly a very rapid inactivation of the enzyme. The absence of TK activity, on the other hand, appears to be due to a block in transcription at the nonpermissive temperature.
Protein synthesis and degradation during expression of the temperature‐sensitive defect in ts A1S9 mouse L‐cells
Authors: Sparkuhl Joachim , Sheinin Rose 
Published: February 2005

AbstractThe involvement of altered protein metabolism in the expression of the temperature‐sensitive (ts) pleiotropic phenotype of ts A1S9 cells was investigated. Cells are ts in growth and DNA replication. They undergo decondensation of their heterochromatin, interruptions of chromatin synthesis, and changes in cell size and morphology at the non‐permissive temperature (npt) of 38.5°C. Whereas the rates of incorporation of 3H‐leucine, 35S‐methionine, and 3H‐fucose into proteins were unaffected at 38.5°C, net protein accumulation was greatly reduced. This imbalance resulted from a rapid increase in the rate of protein degradation at the npt. Enhancement of protein degradation was detected within 2‐4 hours after temperature upshift and constitutes the earliest metabolic alteration thus far observed during expression of the temperaturesensitive phenotype. The average half‐life of proteins preformed in ts A1S9 cells at 34°C was decreased four‐fold at the npt, and all major cytoplasmic proteins were affected equally. Enhanced protein degradation at the npt was shown to be sensitive to cycloheximide, ammonia, chloroquine, and vinblastine at concentrations that did not affect the basal protein degradation of normally cycling cells. Increased protein degradation at 38.5°C did not involve an equivalent increase in total cellular protease activity. The data obtained are compatible with a model that suggests that temperature inactivation of the ts A1S9 gene product results in activation of a lysosome‐mediated mechanism for the rapid degradation of cytoplasmic proteins.
Intracellular NAD+ content and ADP‐ribose polymerase activity of serum‐stimulated baby hamster kidney fibroblasts
Authors: Furneaux Henry M. , Pearson Colin K. 
Published: February 2005

AbstractWe have examined a number of events relating to ADP‐ribose metabolism during serum‐stimulated growth of BHK‐21/C13 fibroblasts. Both the intracellular NAD+ content and the ADP‐ribose polymerase activity were found to increase after serum stimulation of cells that were previously arrested by growth in low‐serum medium. NAD+ content increased about two‐fold, reaching a maximum of 4.2 nmol/μg of DNA 8 hr after serum step‐up. The polymerase exhibited a sharp rise in activity, reaching a peak at about 5 hr after step‐up; the activity declined below initial values by 10 hr, and then increased again to reach a plateau at 20 hr. We also report evidence which suggests a possible effect of ADP‐ribosylation on the activity of DNA‐dependent RNA polymerase I. The activity of this enzyme is diminished in isolated nuclei, and in a subsequent (NH4)2SO4 extract, when the nuclei are incubated with NAD+, the substrate for poly(ADP‐ribose) polymerase. This inhibitory effect on the RNA polymerase is abolished when nuclei are incubated also with nicotinamide, a powerful inhibitor of the poly(ADP‐ribose) polymerase.