bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of a brewer's yeast extract on growth and glucose metabolism of cells in culture
Authors: Høstmark Arne T. , Alexander Jan , Grønnerød Ole , Askevold Rolf , Von Kraemer Bryn Monica 
Published: February 2005

AbstractBrewer's yeast preparations influence glucose metabolism in vivo and in isolated tissues. We have studied the effect of a brewer's yeast extract on glucose metabolism and grwoth of rat hepatoma and human embryonic cells. Growth of the rat hepatoma cells was very much stimulated by the extract in a concentration‐dependent manner. Glucose uptake was, on the other hand, appreciably inhibited, and lactate uptake completely abolished by the extract. Insulin stimulated cell growth and inhibited lactate uptake but did not affect the glucose level. Insulin and the extract had additive effects on growth and lactate uptake of the hepatoma cells. The inhibition by the brewer's yeast extract of glucose uptake was, however, antagonized by insulin. Niacin or Cr3+, which are suggested to be components of a “glucose tolerance factor” of brewer's yeast, did not affect growth or glucose and lactate uptake. The glucose uptake of the human embryonic cells was strongly inhibited by the brewer's yeast extract. Cell growth and lactate production were not influenced by the extract or by insulin; however, when both insulin and extract were present simultaneously, a slight stimulation of growth and inhibition of lactate production was observed. The results indicate that brewer's yeast can have appreciable direct effects on cells and that not all of these effects are “insulin‐like”.
The effect of membrane‐fluidizing agents on the adhesion of CHO cells
Authors: Juliano R. L. , Gagalang E. 
Published: February 2005

AbstractTreatment of CHO cells with drugs which are known to increase membrane lipid fluidity reduced the cells' ability to adhere to protein coated substrates. The concentrations of local anesthetics, nonionic detergents or aliphatic alcohols required to reduce CHO cell adhesion by 50% were similar to those reported to block nerve conduction, indicating that these drugs can affect the membrane at physiologically significant concentrations. Nonionic detergents and aliphatic alcohols, but not local anesthetics, caused increases in the fluidity of CHO plasma membranes (measured by fluorescence polarization) at concentrations which inhibited cell adhesion. The adhesion versus temperature profile had a sigmoidal shape, suggesting that a temperature dependent cooperative process such as a lipid phase transition, might be involved. However, the temperature profile for CHO membrane fluidity manifested no discontinuities, indicating the absence of any discrete phase transitions of the lipid matrix. This observation, coupled with the result that the inhibition of CHO cell adhesion produced by low temperatures was not relieved by drugs which can increase membrane fluidity, suggests that the reduced adhesion seen at low temperature is probably not due to reduced lipid fluidity.
Serum‐dependent regulation of α‐aminoisobutyric acid uptake in bovine granulosa cells
Authors: Allen W. Ross , Nilsen‐Hamilton Marit , Hamilton Richard T. , Gospodarowicz Denis 
Published: February 2005

AbstractThe removal of serum from the medium of ovarian granulosa cells in exponential or confluent stages of growth results in a rapid and pronounced decrease in the rate of transport of the non‐metabolizable amino acid, α‐aminoisobutyric acid. This decrease is rapidly and completely reversed by the addition of serum. The decrease and its reversal are insensitive to inhibitors of RNA and protein synthesis and are unaffected by a number of other metabolic inhibitors. The serum requirement cannot be replaced by peptide hormones known to stimulate cell division and secretion by these cells. These data are consistent with a model of post‐translational control of AIB transport by a high‐molecular‐weight component of serum.
A comparative study of glycosaminoglycans in cultures of human, normal and malignant glial cells
Authors: Glimelius B. , Norling B. , Westermark B. , Wasteson Å. 
Published: February 2005

AbstractThe glycosaminoglycans (GAG) of human cultured normal glial and malignant glioma cell lines were studied using 35S‐sulphate or 3H‐glucosamine as markers. 35S‐labelled GAG were assayed by precipitation with cetylpyridinium chloride; 3H‐labelled sulphated GAG and 3H‐labelled hyaluronic acid were quantitated after separation on a DEAE‐cellulose column. The net production of GAG and the distribution, composition and turnover of GAG were similar in all of the normal cell lines tested, but showed a great variability in the malignant cell lines. Most of the glioma cell lines produced more hyaluronic acid and less sulphated GAG than the normal cell lines, but exceptions were noted. The GAG of the trypsin susceptible (pericellular) pool of normal glial cells consisted mainly of heparan sulphate with only minor amounts of other GAG. The analogous material of most glioma cells showed hyaluronic acid as the major GAG. Material liberated by trypsin from EDTA‐detached cells (membrane fraction) was enriched in heparan sulphate as compared to the entire pericellular pool. Substrate attached material (SAM) left with the plastic dish after EDTA treatment of normal cultures was rich in heparan sulphate, whereas SAM of glioma cells lacked heparan sulphate or showed greatly reduced amounts of this component. Release of newly synthesized GAG to the extracellular medium was a rapid process in the normal cells but was more or less delayed in the glioma cells. The extracellular medium of the malignant glioma cultures was consistently poor in dermatan sulphate, as compared to that of normal cultures.
Gonadotropin stimulation of cyclic AMP levels in Chinese Hamster Ovary cells in culture
Authors: Evain Daniele , Anderson Wayne B. 
Published: February 2005

AbstractWhen Chinese Hamster Ovary (CHO) cells, incubated in serum‐free medium, are exposed to gonadotropins a transient increase in the intracellular concentration of cyclic AMP is observed. Maximum accumulation of cyclic AMP is noted 30 minutes after addition of either human chorionic gonadotropin (hCG) or follicle stimulating hormone (FSH). Within one to two hours after hormone addition, the intracellular concentrations of cyclic AMP have returned to basal levels. The enhancement of intracellular cyclic AMP levels by hCG is hormone concentration dependent, with maximal stimulation observed at 10 μg/ml hCG.The exogenous addition of gonadotropins also slows the growth rate of CHO cells. This effect on growth seems to be mediated through cyclic AMP since the growth rate of a mutant of CHO cells defective in the catalytic subunit of cyclic AMP dependent protein kinase is only slightly decreased.
Active cell aggregation by immature rat Sertoli cells in primary culture: A role for cell surface glycoproteins
Authors: Bordy Michael J. , Berger Sheldon , Desjardins Claude , Davis John C. 
Published: February 2005

AbstractFollicle stimulating hormone (FSH) stimulates “colony formation” by immature rat Sertoli cells in primary culture. “Colony formation” involves cell aggregation. Consequently, the involvement of cell surface glycoproteins in cell aggregation was investigated by treatment of dissociated 10‐day rat testis cells with sodium metaperiodate, glucosamine, various lectins, tunicamycin, and puromycin. Treatment of control cultures with 5 μM glucosamine stimulated cell aggregation; however, glucosamine did not affect FSH‐stimulated cultures. Treatment of dissociated testis cells with 5 μM sodium metaperiodate, 10 μg/ml castor bean agglutinin (ricin), or 2.5 μg/ml horseshoe crab agglutinin inhibited FSH stimulation of cell aggregation. A similar inhibition of cell aggregation was observed following addition of 10 μg/ml puromycin or tunicamycin to culture media from 0‐ to 18‐hours incubation. Treatment with soybean agglutinin, concanavalin A, or wheat germ agglutinin had no effect. The galactose‐specific lectins, Ricin, Ricinus communis agglutinin I, and Bendeirea simplicifolia agglutinin, inhibit the FSH stimulation of 3H‐aminoacid incorporation as well as cell aggregation in 24‐hour cultres. The inhibition of cell aggregation by sodium metaperiodate treatment was reversed with 5 μM sodium borohydride reduction. Sodium metaperiodate treatment did not alter cell viability (as assayed with trypan blue dye exclusion), did not alter cell attachment, nor significantly decrease 125I‐FSH binding by cultured testis cells. The results suggest that FSH stimulation of cell aggregation by immature rat Sertoli cells requires cell surface glycoprotein interactions. Furthermore, the specificity of lectin inhibition suggests that glycoproteins with terminal galactose and sialic acid residues are required for the FSH induction of cell aggregation.
Selection and characterization of a variant of murine L5178Y lymphoma resistant to local anesthetics
Authors: Yau Tom M. , Kim S. C. , Crissman H. A. 
Published: February 2005

AbstractA variant of murine L5178Y lymphoma resistant to procaine hydrochloride (PH) was selected by exposing the cells to gradual increments of PH in the growth medium until the cell grew exponentially in the presence of 1.5 mM PH. Using cinephotomicrography, it was observed that the majority of cells that initially succumbed to PH failed to undergo successful mitosis. With respect to chromosomal, cell size distribution and flow microfluorometric analyses, the PH‐resistant cells are very similar to a spontaneous tetraploid cell line (R1T) previously cloned. The isolated cells, designated R1/P, were also found to be cross‐resistant to analogues of PH, namely, lidocaine, tetracaine and dibucaine. The naturally‐occurring tetraploid cell line (R1T) was also found to be more resistant to local anesthetics, although not to the same extent as R1/P cells. Since the enzyme that hydrolyzes procaine appears to be absent in all these lymphoid cell lines, the difference in resistance does not appear to depend on differences in the ability of these cells to remove the agent. It is suggested that an alteration in the structure and/or function of the plasma membrane in R1/P cells have rendered them either less sensitive to the membrane‐perturbing effects of the local anesthetics or less permeable to local anesthetics molecules. The ability of local anesthetics to affect membranes and cytoskeleton structures may play a role in the genesis and/or selection of these cell variants.
Expression of malignancy in hybrids between normal and malignant cells
Authors: Croce Carlo M. , Barrick Joan , Linnenbach Alban , Koprowski Hilary 
Published: February 2005

AbstractSomatic cell hybrids between either normal human fibroblasts, phenotypically normal mouse fibroblasts or mouse peritoneal macrophages and HT1080 human diploid fibrosarcoma cells were studied for their ability to form tumors in nude mice. The results of this study indicate that tumorigenic behavior is expressed as a dominant trait in both human‐human and mouse‐human hybrid cells.
Isolation of rat hepatoma cell variants selectively resistant to dexamethasone inhibition of plasminogen activator
Authors: Seifert Sarah Carlson , Gelehrter Thomas D. 
Published: February 2005

AbstractGlucocorticoids induce several phenotypic changes in rat hepatoma cells in tissue culture, including the inhibition of plasminogen activator activity. Variant cell lines resistant to dexamethasone inhibtion of plasminogen activator activity have been isolated using an agar‐fibrin overlay technique to identify colonies with fibrinolytic (plasminogen activator) activity. The variants are resistant to concentrations of dexamethasone 1,000 times that necessary to completely inhibit plasminogen activator activity in wild‐type cells. The variant phenotype has been inherited in a stable manner for more than 300 generations in continuous culture in the absence of dexamethasone. These variants are unique in that the resistance is not secondary to defective or absent glucocorticoid receptors but is due to a lesion specific for regulation of plasminogen activator. Fluctuation analyses support the hypothesis that resistance to dexamethasone arises randomly and is not induced by dexamethasone. Because HTC cells are heteroploid and karyotypically highly variable, variants are thought to arise primarily by chromosomal segregation events. These variants provide a valuable tool for studying the mechanism of hormonal regulation of plasminogen activator as well as the role of proteases in hormonal regulation of membrane functions.
Regulation of protein synthesis in mitotic HeLa cells
Authors: Tarnowka Miroslaw A. , Baglioni Corrado 
Published: February 2005

AbstractMitotic HeLa cells (M cells) synthesize protein at about 25% of the rate of S phase cells. This decrease in protein synthesis is due to a reduction in the rate of initiation. However, extracts prepared from M cells are almost as active in protein synthesis as S cell extracts. Both cell extracts are quite active in in vitro initiation of protein synthesis. Moreover, two steps in initiation, binding of Met‐tRNAf to 40S ribosomal subunits and binding of mRNA to ribosomes, show similar activity in both extracts. The difference in protein synthesizing activity observed in vivo is largely eliminated in the preparation of cell‐free systems. The ribosomes of M cells contain small mot wt RNA, which inhibits protein synthesis in vitro. This RNA, which has possibly a nuclear origin, may be a cause of the reduction in the rate of protein synthesis in M cells.
Regulation of surface antigen expression in Paramecium primaurelia. II. Role of the surface antigen itself
Authors: Capdeville Yvonne 
Published: February 2005

AbstractIn the wild‐type strains, 156 and 168, of Paramecium primaurelia, the alleles G156 and G168 expressed at medium temperature specify two immunologically distinguishable surface antigens 156G and 168G, whose phenotypic expression shows allelic exclusion, the majority of heterozygotes being phenotypically [156G] while a small minority is phenotypically [156G–168G]. At high temperature, the antigens coded by another locus, generally the D locus, are expressed. This system, displaying both intergenic and interallelic exclusion, provides favourable material to analyze the respective roles of the genome, of the antigens expressed and of the environmental conditions, in particular temperature, on the regulation of the expression of surface antigens.This analysis was carried out by studying the variations of the expression of surface antigens as a function of temperature, culture medium and previously expressed antigens in different genetic situations (a) in homozygotes: the wild‐type strains 156 and 168, and the isogenized strains “G156 isogenic 168” carrying the G156 allele in a 168 genetic background; (b) in heterozygotes of the two phenotypic classes of heterozygotes, [156G] and [156G–168G]. The results show that (1) the thermal stability of the expression of a given surface antigen and its rate of re‐appearance at the cell surface depend on its own specificity: (2) in heterozygotes [156G–168G], the stability of the expression of the antigen 156G is modified and “adjusted” to that of the less stable surface antigen 168G, and (3) the surface antigen itself exerts a positive control on the maintenance of its own expression.An interpretative model of “transmembranous control” is proposed to account for the regulation of the expression of surface antigens in Paramecium.
Control of the Balb/c‐3T3 cell cycle by nutrients and serum factors: Analysis using platelet‐derived growth factor and platelet‐poor plasma
Authors: Stiles C. D. , Isberg R. R. , Pledger W. J. , Antoniades H. N. , Scher C. D. 
Published: February 2005

AbstractMuch controversy regarding the relationship between nutrients and serum in regulation of cell growth can be reconciled by recognizing that serum contains multiple factors which regulate different events in the cell cycle. Serum was fractioned into a platelet‐derived growth factor (PDGF), which induces cells to become competent to synthesize DNA, and plasma which allows competent cells to traverse G0/G1 and enter the S phase. Nutrients are not required for the cellular response to PDGF; however amino acids are required for plasma to promote the entry of PDGF‐treated, competent cells into S phase. The nutrient independent, PDGF‐modulated, growth regulatory event (competence) is located 12 hours prior to the G1/S phase boundary in quiescent, density‐arrested Balb/c‐3T3 cells. The nutrient dependent, plasma‐modulated event is located six hours prior to the G1/S phase boundary and corresponds in time to a plasma dependent growth arrest point. Moreover, plasma controls the concentration of amino acids required for DNA synthesis. Infection of density‐arrested Balb/c‐3T3 cells with SV40 overrides both the nutrient independent and the nutrient dependent growth regulatory events.
Stimulation of endothelial cell proliferation by precursors of thymidylate
Authors: McAuslan B. R. , Reilly W. , Hannan G. N. 
Published: February 2005

AbstractBovine corneal and aortal endothelial cell cultures were established from primary explants and subcultured for at least 40 passages. With both cell, exogenous thymidine, folate or folinate markedly increased the proliferation of these cells and decreased their serum requirement in Medium 199.Medium 199 supplemented with thymidine was particularly useful for cell survival at low densities; clones were readily produced when single cells were plated as low as 0.07 cells. cm−2. In contrast to the results of others, neither fibroblast growth factor nor epidermal growth factor were necessary for cell proliferation or survival at low densities.
Effect of temperature on protein and immunoglobulin synthesis and secretion in two mouse myeloma cell lines
Authors: Craig Nessly 
Published: February 2005

AbstractProtein synthesis in differentiated MOPC‐21 and MPC‐11 mouse myeloma cells was studied to determine the basis for the differences in the temperature and actinomycin D sensitivity of translation between non‐differentiated mouse L‐cells and differentiated rabbit reticulocytes. The temperature dependence of total protein synthesis was similar to that of L‐cells and reticulocytes, being biphasic in Arrhenius plots with apparent activation energies of approximately 25 and 42 kcal/mol, above and below 25°C. The dependence of the secretion process was different since it was not biphasic, having a single activation energy of about 22 kcal/mol. Myeloma polysomes were like L‐cell polysomes in their response to lower temperature and reached a minimum level of 50% at 15°C. This response was also found for the specific polysomes synthesizing the IgG H‐ and L‐chains. In the presence of actinomycin D, myeloma polysomes declined exponentially with a half‐life of ∼6 hours. These two L‐cell‐like responses were not found in reticulocytes. Translation of both the IgG mRNAs and the non‐IgG mRNAs was reduced by lower temperatures and actinomycin D, even though the L‐chain mRNA was slightly more resistant, suggesting that this mRNA is slightly more efficient. The results of these experiments suggest that the translational differences between L‐cells and reticulocytes are not mRNA dependent, but are cell type differences.
A new cell surface marker of aging in human diploid fibroblasts
Authors: Aizawa Shinichi , Mitsui Youji 
Published: February 2005

AbstractThe relationship of cell surface changes to proliferative decline of human diploid fibroblasts was investigated using the concanavalin A‐mediated red blood cell adsorption assay. The amount of the red blood cells adsorbed to human diploid fibroblasts via concanavalin A increased continously from the early phases of cell passage up through cell senescence, while the amount of 3H‐concanavalin A binding did not change to a significant extent. The red blood cell adsorption is not a function of cell cycle phase and time spent in culture. Cocultivation of young cells with old cells also did not affect the adsorption capacity of respective cells. Thus, the concanavalin A‐mediated red blood cell adsorption can be expected to serve as a new cell surface marker for aging in vitro. Using this marker, it was revealed that transient cell size or 3H‐thymidine incorporating capacity do not have a direct relationship with the division age of a cell. Small rapidly dividing cells in old populations resemble large slowly dividing or nondividing cells of the same populations and differ from small rapidly dividing cells in young populations, in terms of cell surface properties.
The inhibition by xanthine phosphodiesterase inhibitors of the induction of alkaline phosphatase activity in HeLa cells: Relationship of enzyme activity to cyclic AMP concentrations
Authors: Wharton Walker , Goz Barry 
Published: February 2005

AbstractThe three xanthine derivatives, caffeine, theophylline and 3‐isobutyl‐1‐methyl‐xanthine (IBMX) produced dose‐dependent increases in cyclic AMP concentrations in HeLa cells after long term treatment. Only IBMX produced increases over the first 60 minutes, with a peak of approximately 5‐fold control values five to 10 minutes after the addition of the drug. About four hours after the addition of either 0.67 or 1.0 mM IBMX there was a second peak in the concentration of cyclic AMP which was at least as large and usually larger than the peak observed at five to ten minutes. Neither caffeine nor theophylline increased cyclic AMP concentrations above control values until one hour after addition of the compounds, and there was no indication of a peak in the concentration at four hours. Between 24 and 72 hours, all three compounds produced elevations in cyclic AMP levels that were steadily maintained. At any given concentration, the order of potency was IBMX > theophylline > caffeine. If the xanthine derivatives were removed from the medium after 24 hours of treatment, the cyclic AMP concentrations fell to control levels within one hour. Treatment with 5‐iodo‐2′‐deoxyuridine (IdUrd) or hydrocortisone alone did not change the levels of cyclic AMP, nor did the presence of these inducers of alkaline phosphatase activity alter the effects of the xanthine derivations on cyclic AMP concentrations. The data showed a significant correlation between the magnitude of the increase in cyclic AMP concentrations over the period from 24 to 72 hours and the degree of inhibition by the xanthine derivatives of the induction of alkaline phosphatase activity.
High affinity concanavalin a binding to sterol‐depleted L cells
Authors: Marshall Jan D. , Heiniger Hans‐Jörg , Waymouth Charity 
Published: February 2005

AbstractBinding of Concanavalin A to mouse L cells which were grown in serum free, chemically defined medium and depleted of their membrane sterol by blocking their de novo sterol synthesis was investigated. Kinetic analysis of binding data implied positive cooperativity, with two different affinities for Con A, in both experimental and control cultures. The amount of Con A bound to the cell surface at saturation was approximately 0.5 picomoles per mg cellular protein in controls and approximately 1.0 picomoles per mg cellular protein in 25‐hydroxycholesterol treated cultures (which had a reduced sterol concentration of up to 50% in their plasma membranes). This phenomenon was reversed when cholesterol or mevalonate was added to the inhibited cultures to compensate for their inability to synthesize sterol. Our findings indicate that lectin binding to specific glycoprotein receptors is influenced by membrane lipid composition.