bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pharmacological evidence for cell surface control of oral regeneration in Stentor coeruleus
Authors: Maloney Michael S. 
Published: February 2005

AbstractThis study suggests that membrane perturbations can affect oral morphogenesis in Stentor, possibly by a mechanism involving calcium ions. Exposure of regenerating Stentor to micromolar concentrations of the membrane active local anesthetics dibucaine, tetracaine, or procaine greatly delayed the progress of oral regeneration. In the case of tetracaine and dibucaine the greatest delays were observed in the early stages of regeneration prior to stage 4, when the majority of essential synthetic activity is occurring. The effects of dibucaine were generally readily reversible upon removal of the cells from the drug, with some residual effects occurring at higher dibucaine concentrations. Regenerating cells in the presence of dibucaine and excess extracellular calcium were not delayed, suggesting that the effects of dibucaine were reversible by calcium ions. The effects of tetracaine were not reversible by calcium ions, however. Exposure of regenerating cells to medium either lacking in, or containing an excess of, extracellular calcium had no effect on the time required to complete oral regeneration. The plant lectin, phytohemagglutinin, can also delay oral regeneration. The possible implications of these findings on the control of oral regeneration are discussed.
The growth requirements of SV40 virus transformed Balb/C‐3T3 cells in serum‐free monolayer culture
Authors: Rockwell G. A. , Sato G. H. , McClure D. B. 
Published: February 2005

AbstractThe growth requirements of SV40 transformed Balb/c‐3T3 cells have been studied in the absence of serum. For growth in serum‐free medium, the cells require (i) insulin, (ii) transferrin, and (iii) cis‐unsaturated fatty acids added in combination with fatty acid free bovine serum albumin. The growth rate, saturation density, and morphology of cells grown in this serum‐free medium are the same as those of cells grown in serum supplemented medium. This mixture also supports the growth of SV40 transformed Swiss‐3T3 cells and SV40 transformed primary mouse embryo cells, but does not support the growth of untransformed Balb/c‐3T3 cells.The addition of fibronectin to this mixture allows routine subculture, repeated passage, and indefinite propagation of SV40 transformed Balb/c‐3T3 cells. Cells grown in this medium for a period of two months retain their ability to induce tumors when injected into athymic nude mice.
Formation of sulfhydryl groups in the culture medium by human diploid fibroblasts
Authors: Bannai Shiro , Ishii Tetsuro 
Published: February 2005

AbstractWhen human diploid fibroblasts IMR‐90 are cultured in routinely used medium (Eagle's basal medium supplemented with 10% fetal calf serum), sulfhydryl compounds appear in the medium. The major component of these sulfhydryl compounds is cysteine, and it is shown that a part of medium cystine is converted into cysteine by the cells. It is also shown that the sulfhydryl groups of serum albumin, which are masked and barely detectable before the culture, are restored. Probably cysteine formed by the cells reacts with serum albumin to give rise to the protein sulfhydryl groups via sulfhydryl–disulfide exchange reactions. Total sulfhydryl concentrations in the medium are maintained in a considerable level throughout the culture, and a possible physiological function of these sulfhydryl groups is discussed.
Facilitated transport of uracil and 5‐fluorouracil, and permeation of orotic acid into cultured mammalian cells
Authors: Wohlhueter Robert M. , McIvor R. Scott , Plagemann Peter G. W. 
Published: February 2005

AbstractThe mode of permeation of uracil, 5–fluorouracil, and orotic acid into cells has been investigated in four established cell lines (Novikoff rat hepatoma, P388 mouse leukemia, mouse L, and Chinese hamster ovary cells) in attempts to assess the rate‐determining step(s) in their incorporation into the nucleotide pool and nucleic acids. Uracil and 5–fluorouracil shared a saturable transport system (Km = 5 to 15 mM) capable of rapid equilibration of these substrates across the cell membrane (t1/2 at 25 in first‐order range of concentration = 25 to 58 sec). Thus it seems unlikely that transport is limiting the incorporation hypoxanthine. Only the non‐ionized form of fluorouracil was a substrate for the transporter; exclusion of charged pyrimidines may explain why orotate was not a substrate at physiological pH. Orotate permeated the cell membrane much more slowly (t1/2 = 2890 to 6930 sec); its permeation was apparently non‐mediated and rate‐determining in the conversion of extracellular orotate to intracellular nucleotides.
Adhesion sites of murine fibroblasts on cold insoluble globulin‐adsorbed substrata
Authors: Murray Ben A. , Ansbacher Riva , Culp Lloyd A. 
Published: February 2005

AbstractThe attachment and detachment behavior of three mouse fibroblast cell lines adhering to plastic tissue culture substrata coated with the serum protein cold‐insoluble globulin (CIg) resembles that seen on the usual serumcoated substrata. The transformed cell line SVT2 spreads more extensively on the CIg‐coated than on the serum‐coated substratum, while the nontransformed Balb/c 3T3 line and concanavalin A‐selected “revertant” of SVT2 are equally well spread on both substrata. In all three cases, immunofluorescence microscopy using antibodies to CIg suggests that the cells are more tightly apposed to the CIg‐coated substratum than to the serum‐coated substratum.Substrate‐attached material (SAM), which contains cell‐substratum adhesion sites and which is left after EGTA‐mediated detachment of cells, is enriched for cell surface fibronectin and glycosaminoglycans (GAG). When cells are seeded onto CIg‐coated substrata rather than serum‐coated substrata, there is an increased deposition of GAG but a comparable deposition of cellular proteins. The protein distribution of the two types of SAM are identical as analyzed by sodium dodecyl sulfate/polyacrylamide gel electrophoresis, including fibronectin content. This indicates that substratum‐bound CIg cannot functionally substitute for cell surface fibronectin in these adhesion sites. Analysis of the GAG deposited on CIg‐coated substrata reveals that hyaluronate and the chondroitins are increased to a much greater extent than heparan sulfate; however, the ratio of hyaluronate to the various chondroitin species is invariant. These data provide further evidence that hyaluronate and the chondroitins are deposited in adhesion sites in well‐defined stoichiometric proportions, possibly as supramolecular complexes, and that CIg may mediate adhesion of cells in the serum layer by binding to GAG‐containing proteoglycans.
Effects of ouabain and ortho vanadate on transport‐related properties of the LLC‐PK1 renal epithelial cell line
Authors: Mullin James M. , Diamond Leila , Kleinzeller Arnost 
Published: February 2005

AbstractUptake of α‐methyl‐D‐glucoside (AMG) by LLC‐PK1 cells is inhibited by the uncoupler p‐trifluoro‐methoxyphenyl‐hydrazone (FCCP) and by the absence of extracellular Na+, indicating that the transport system is energy‐ and Na+ ‐dependent. We have previously demonstrated that transport of AMG by LLC‐PK1 cells proceeds against a concentration gradient and is phlorizin‐sensitive (Mullin et al., '80). Uptake of AMG was also inhibited by ouabain (OUA) but not by ortho‐vanadate (VAN). Rubidium uptake also was affected by OUA but not by VAN. VAN, however, caused collapse of the three‐dimensional domes of confluent LLC‐PK1 monolayers much more rapidly and thoroughly than OUA. Since domes are presumably dependent upon the Na+ pump, yet VAN is not acting on transport‐related functions of the OUA‐sensitive (Na+ + K+)‐ATPase, we hypothesize a direct effect of VAN on the water permeability of these cells. We also suggest that OUA does not act on these cells until domes collapse in normal course, and access of the OUA to the extracellular surface of antiluminal membranes is then achieved.
Construction of viable mouse‐human hybrid cells by nuclear transplantation
Authors: Hightower Margaret J. , Lucas Joseph J. 
Published: February 2005

AbstractViable interspecies cytoplasmic‐nuclear hybrid cells were constructed by fusion of karyoplasts prepared from the highly tumorigenic A9 mouse fibroblast cell line and cytoplasts prepared from the Detroit 532 normal human diploid cell strain. The identity of the hybrid cells was ascertained using a variety of morphological, immunological, and genetic criteria, including: nuclear pattern of staining with the fluorochrome Hoechst 33258, appearance of the actin‐myosin containing cytoskeleton, presence of fibronectin, and resistance to azaguanine and diphtheria toxin. About 90% of the hybrid cells were viable, that is, capable of division. Changes in the morphology of the hybrid cells, apparently nuclear directed, were observed before cell division occurred. Using the techniques described here, large numbers of interspecies hybrid cells suitable for many types of biochemical analyses can be routinely produced.
A hemopoietic cell line dependent upon a factor in pokeweed mitogen‐stimulated spleen cell conditioning medium
Authors: Hasthorpe Suzanne 
Published: February 2005

AbstractA continously growing cell line (FMP1.1) has been isolated, which is dependent upon a factor in PWCM for both growth and survival. FMP1.1 appears to be a mast cell, since IgE receptors are present and their graunles react specifically with a mast cell granule stain. The factor in PWCM may be a glycoprotein and has biochemical properties in common with PWCM factors, which stimulate at least four other lineages of hemopoietic colonyforming cell. This line provides a pure population of cells as a model for studying molecular events of hemopoietic precursor cell growth and differentiation.
Shedding of mitotic cells from the surface of multicell spheroids during growth
Authors: Landry Jacques , Freyer James P. , Sutherland Robert M. 
Published: February 2005

AbstractDuring the growth of EMT6/Ro mammary tumor multicell spheroids, a large number of cells are shed into the suspension medium. The rate of cell shedding was 218 cells per square millimeter of spheroid surface per hour, or up to 1.5% of the total spheroid cell content per hour. Shed cells had a clonogenic capacity equal to that of exonential monolayer cultures and were further characterized by volume distribution, mitotic index, flow cytoflurometry, and autoradiography. The results indicated that cells are released from the spheroid surface at mitosis, presumably due to a loosening of the cell‐to‐cell attachment during this cycle phase. These mitotic cells, when placed in monolayer culture, attached and grew synchronously with a cell cycle time of about 13 hours. Shed cells kept in suspension culture had a similar cell cycle time, but these cells reaggregated immediately after mitosis. The results indicated that cell shedding and reaggregation both occur near the time of mitosis and are intrinsic factors regulating the initiation and subsequent growth of multicell spheroids. Although these studies were done with spheroids cultured in vitro, shedding of mitotic cells may play an important role in the in vivo process of metastasis.
The accumulation of three specific proteins related to glucose‐regulated proteins in a temperature‐sensitive hamster mutant cell line K12
Authors: Lee Amy Shiu 
Published: February 2005

AbstractA temperature‐sensitive mutant K12 isolated from an established line of Chinese hamster fibroblasts has been identified as a cell‐cycle mutant blocked in G1 (Roscoe et al., '73a, b). While characterizing the phenotype of K12 in more detail, we observed that K12 cells are highly sensitive to the concentration of glucose in the culture medium as well as the temperature of incubation. Although overall cellular metabolism remains intact for at least 24 hours after shifting the cells to the nonpermissive temperature (40.5°C), the incorporation of 3H‐leucine into three specific cellular proteins of molecular weights 94, 78, and 58 K daltons is greatly increased. We have analyzed the K12 proteins by two‐dimensional, isoelectric focusing (IEF) sodium dodecyl sulfate (SDS) gel electrophoresis and found that the set of proteins which is overproduced by K12 cells at 40.5°C is the same as that produced at 35.0°C in medium depleted of glucose or supplemented with 10 mM glucosamine. In addition, the increased synthesis of these proteins cannot be suppressed by the addition of N‐acetylglucosamine to the medium. The relation ship of these proteins to the glucose‐regulated proteins in the chick embryo fibroblast system (Shiu et al., '77) is discussed.
The biotin requirement of HeLa cells
Authors: Dakshinamurti K. , Chalifour L. E. 
Published: February 2005

AbstractWe have examined the effect of alterations in the biotin content of the medium on the growth, viability, biotin content, and the activities of biotin‐dependent and biotin‐independent enzymes of the HeLa cells. The inclusion in the growth medium of avidin, which almost irreversibly binds with biotin (Kd, 10−15 M), results in an increase in cellular biotin content and biotin enzyme activity over that seen when the cells are grown in a biotin‐depleted medium. The addition of avidin‐bound biotin to the growth medium led to a forty‐fold increase in cellular biotin when compared to the inclusion of an equivalent amount of free biotin in the medium. HeLa cells are able to internalize avidin‐bound biotin. Biotin is released from this complex to function as the prosthetic group of biotin enzymes. HeLa cells do have a nutritional requirement for biotin.
Cellular responses to stress: Comparison of a family of 71–73‐kilodalton proteins rapidly synthesized in rat tissue slices and canavanine‐treated cells in culture
Authors: Hightower Lawrence E. , White Fredric P. 
Published: February 2005

AbstractCultured rat embryo cells exposed to the L‐arginine analogue L‐canavanine rapidly accumulated a major 71 kilodalton polypeptide and several minor ones (110, 95, 88, and 78 kilodaltons). Canavanine‐treated cultures contained elevated levels of translatable mRNA encoding P71, and the stimulated synthesis of this protein was blocked by actinomycin D, suggesting that P71 is inducible. Rat embryo cells maintained under routine culture conditions synthesized only trace amounts of P71; however, they accumulated an abundant 73 kilodalton protein that was closely related to P71. No kinetic evidence of a precursor‐product relationship between P73 and P71 was found. The peptide map of P71 from cultured cells was identical to the map of proteins with the same electrophoretic mobility isolated from incubated slices of rat telencephalon. Previous studies (White, ′80a, b, c) have shown that the latter proteins are rapidly synthesized by cells associated with cerebral microvessels in incubated brain slices, but are not detectable in vivo. Herein we present evidence that the synthesis of P71 is not unique to brain slices. Incubated slices of heart, lung, thymus, kidney, spleen, and liver all accumulated an abundant 71 kilodalton size class. The peptide maps of P71 obtained from brain, heart, lung, and thymus tissue were similar. The stimulated synthesis of P71 in brain, heart, and lung slices was inhibited strongly by the addition of actinomycin D at the start of incubation. The 71–73 kilodalton proteins of canavanine‐treated rat embryo cells and incubated slices from seven different organs were compared in detail on two‐dimensional poly‐acrylamide gels. Eight charge variants were detected in extracts of lung, spleen, and thymus tissue, four in liver and heart, three in kidney, and two different pairs of variants in extracts of brain tissue and cultured cells. The possible significance of the rapid synthesis of a similar small set of proteins in tissue slices and cultured cells in response to a variety of physical, chemical, and biological stimuli is discussed in terms of cellular responses to traumatic injury and metabolic stress.
Interferon induction in marrow‐derived macrophages: Regulation by L cell conditioned medium
Authors: Fleit Howard B. , Rabinovitch Michel 
Published: February 2005

AbstractMouse bone marrow cells grown in medium enriched with L cell conditioned medium (LCM) as a source of colony stimulating factor (CSF) yield populations of adherent macrophages which are quite sensitive to induction of interferon (IFN) by viral and nonviral inducers. We examined the role of LCM in the sensitivity of marrow macrophage cultures to IFN induction. Removal of LCM from the cultures for as little as 3 hours markedly reduced the IFN titers induced by a double stranded ribopolynucleotide (poly I:C) or a lipopolysaccharide (LPS), while induction by Newcastle disease virus (NDV) was unaffected. Addition of anti‐CSF serum to LCM medium also reduced IFN titers in response to poly I:C but had no effect on NDV induction. The inhibitory effect of anti‐CSF indicates that the LCM requirement is at least partially related to the colony stimulating activity of the medium. We postulate that CSF regulates the initial interaction of macrophages with poly I:C or LPS rather than the synthesis and secretion of interferon by the phagocytes. Nearly complete restoration of IFN induction with poly I:C was obtained when LCM deprived cultures were reincubated with LCM medium previously conditioned by marrow cultures.
DNA synthesis in primary cultures of adult rat hepatocytes in a defined medium: Effects of epidermal growth factor, insulin, glucagon, and cyclic‐AMP
Authors: McGowan Joan A. , Strain Alastair J. , Bucher Nancy L. R. 
Published: February 2005

AbstractEpidermal growth factor (EGF) especially in combination with insulin and glucagon, has been shown to stimulate DNA synthesis in liver cells, both in the whole animal and in cell cultures. As a further development we have found that in primary monolayer cultures of freshly isolated adult rat liver parenchymal cells, in which contamination with nonparenchymal cells was negligible, DNA synthesis was substantially stimulated by these substances. In control cultures, incorporation of [3H]thymidine into DNA and labeling of nuclei in autoradiographs was low. The stimulation by EGF was enhanced by insulin and glucagon, whereas these hormones by themselves exhibited only limited activity. These observations were made in cultures of hepatocytes that were never exposed to serum, even during cell isolation and plating. Hence for stimulation of DNA synthesis under these conditions neither serum factors nor interactions with other types of cells or their products were required. The effects of glucagon were reproduced by substances that elevate intracellular concentration of cyclic‐AMP, including cholera toxin, isoproterenol, and methylisobutylxanthine. These various substances, expecially EGF, glucagon, or cyclic‐AMP, altered the morphological characteristics of the cultures during early stages, promoting cellular spreading and aggregation.
Nucleoside requirements for the in vitro growth of bovine aortic endothelial cells
Authors: Fenselau Allan , Kaiser Donald , Wallis Katheleen 
Published: February 2005

AbstractThe nutritional needs of cultured fetal bovine aortic endothelial cells were studied with regard to their nucleotide metabolism. When Medium 199 containing calf serum was supplemented with up to 5μg/ml of the deoxyribo‐ or ribonucleosides found in DNA or RNA, the rate of endothelial cell growth increased. The effect was entirely attributable to the pyrimidine nucleosides. The combination of deoxythymidine and deoxycytidine was much more effective than either deoxyribonucleoside used alone or than the combination of uridine and cytidine. Addition of deoxythymidine and deoxycytidine (each at 1 μg/ml) to the medium supported the growth of endothelial cell cultures from initially sparse populations (ca. 50 cells/cm2), even at low concentrations (1%) of fetal bovine serum. The pyrimidine deoxyribonucleosides on their own were unable to stimulate cell growth; other bonafide growth stimulatory factors, such as those present in serum, serum dialysates, or retinal extracts, were needed in the medium to signal the initiation of DNA synthesis and cell replication. The significance of these findings with respect to improving cell performance under in vitro conditions and controlling endothelial cell growth in vivo are discussed.
Collagen synthesis in human fibroblasts: Effects of ascorbic acid and regulation by hydrocortisone
Authors: Russell Shirley B. , Russell James D. , Trupin Kathryn M. 
Published: February 2005

AbstractThe effects of hydrocortisone and ascorbic acid on collagen and noncollagen protein synthesis, and on growth were examined in fibroblasts derived from normal human dermis. When the medium was supplemented with 0.28 mM ascorbic acid, the apparent rate of collagen production increased 2‐‐3 fold over the culture cycle. Ascorbic acid also caused a small increase in the apparent rate of synthesis of noncollagen protein and an elevation in growth rate and maximum cell density. Growth was not required for the increase in collagen production since addition of ascorbate to confluent cultures induced a similar increase. Hydrocortisone (1.5 μM) blocked the ascorbate‐related increase in collagen production during growth and in confluent cultures. The hormone simultaneously increased the apparent rate of noncollagen protein production and maximum cell density, suggesting that the effect on collagen synthesis was specific. Inhibition of collagen production by hydrocortisone was observed only in the presence of ascorbate, while the increase in growth and noncollagen protein production occurred in the presence and absence of the vitamin.
Folate polyglutamate and monoglutamate accumulation in normal and SV40‐transformed human fibroblasts
Authors: Hoffman Robert M. , Coalson Dennis W. , Jacobsen Stephen J. , Erbe Richard W. 
Published: February 2005

AbstractFolate polyglutamate and monoglutamate accumulation was measured in normal diploid and SV40‐transformed human fibroblasts by Sephadex G‐10 gel filtration chromatography. The cells were first depleted of folates and then provided with limiting amounts of [3H]‐folic acid in order that the cells would accumulate only forms of folate necessary for proliferation. Both the normal and the transformed cells accumulated monoglutamate and polyglutamate forms, but by 72 hours of labeling the transformed cells contained 3–10 times more polyglutamate than the normal cells. The growth rates for the normal and transformed cells were similar at this limiting folic acid concentration. Thus, if folate polyglutamates are more important for the proliferation of SV40‐transformed cells than the normal cells, then inhibition of polyglutamate formation may be an important potential target for chemotherapy.