bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stimulation of motility in cultured bovine capillary endothelial cells by angiogenic preparations
Authors: Mullins Deborra E. , Rifkin Daniel B. 
Published: February 2005

AbstractSeveral angiogenic preparations that have been shown to stimulate plasminogen activator (PA) and collagenase production by cultured bovine capillary endothelial (BCE) cells were tested for their ability to stimulate BCE cell motility in the phagokinetic track assay. Bovine retinal extract, medium conditioned by 3T3‐F442A differentiated mouse adipocytes, SK HEP‐1 human hepatoma cell lysate, mouse sarcoma 180 cell lysate, and medium conditioned by mouse sarcoma 180 cells stimulated motility 68.7%, 48.5%, 140.9%, 56.5%, and 102.1%, respectively, relative to untreated cells. The motility‐stimulating activity of these preparations was dose dependent and linear over the 16‐h assay period. Several hormones and growth factors were tested for BCE cell motility‐stimulating activity, including insulin, vasopressin, fibroblast growth factor, and a partially purified preparation of sarcoma growth factor, and were found to be ineffective.12‐0‐tetradecanoyl‐phorbol‐acetate (TPA), a potent stimulator of both PA and collagenase activities in BCE cells, also did not stimulate motility, indicating that protease production is not sufficient to stimulate BCE cell motility in this assay. Neither SK HEP‐1 hepatoma cell lysate nor TPA was effective in stimulating motility in bovine aortic endothelial (BAE) cells. The inability of SK HEP‐1 hepatoma cell lysate to stimulate movement in BAE cells is consistent with the observation that angiogenesis occurs by sprouting of capillaries, not large vessels.
Isolation of a temperature‐sensitive FM3A mutant deficient in asparagine‐linked glycosylation by selecting for resistance to tritiated mannose suicide
Authors: Nishikawa Yoshihisa 
Published: February 2005

AbstractProtein glycosylation mutants in the mouse mammary carcinoma cell line FM3A were selected for ability to withstand exposure to [2‐3H]mannose at 39°C. G258, one of the mutant cells isolated, has been characterized. G258 cells were temperature‐sensitive for cell growth. Moreover, G258 cells showed temperature sensitivity for [3H]mannose incorporation into the TCA‐insoluble fraction. To study the biochemical basis of the defect in glycoprotein biosynthesis, the formation of lipid‐linked saccharides was examined. The results showed that the formation of lipid‐linked oligosaccharides was severely inhibited in G258 cells at 39°C. At 33°C, G258 cells synthesized Glc3Man9GlcNAc2‐PP‐Dol, the fully assembled lipid‐linked oligosaccharides, but at 39°C, G258 cells were able to synthesize merely the smaller lipid‐linked oligosaccharides (approximately up to Man3GlcNAc2‐PP‐Dol), but were unable to synthesize the larger lipid‐linked oligosaccharides.
Analysis of pure and mixed murine mast cell colonies
Authors: Pharr Pamela N. , Suda Toshio , Bergmann Karen L. , Avila Lobelia A. , Ogawa Makio 
Published: February 2005

AbstractMast cells have been proposed to originate from diverse sources, including connective tissues, macrophages, T lymphocytes, and hemopoietic cells. Evidence for a hemopoietic origin of mast cells includes the presence of mast cell precursors in spleen colonies and the presence of mast cells in hemopoietic colonies in culture. Here we report a detailed analysis of mouse spleen mixed hemopoietic colonies containing mast cells. All of the colonies in cultures plated at low cell densities were individually removed for analysis by May‐Grunwald‐Giemsa staining on day 15 of culture. Examination of five dishes which contained a total of 82 colonies showed 16 pure mast cell colonies and 36 mixed mast cell colonies. Sixteen different combinations of cell types were seen and were not distinguishable from each other in situ. The most diverse type of mixed colony contained macrophages (m), neutrophils (n), eosinophils (e), mast cells (Mast), megakaryocytes (M), erythroid cells (E), and blast cells. The clonal origin of mixed mast cell colonies was established by the replating of single cells obtained from blast cell colonies. Individual cells were removed with a micromanipulator, replated, and allowed to grow for 15 days. Cytospin preparations of 10 such colonies showed diverse combinations of cell lineages which were seen in the different types of mixed mast cell colonies described above. Replating studies of mixed mast cell colonies were carried out and a high incidence of replating was seen. Approximately one half of these colonies formed only mast cell colonies upon replating. Further studies showed that pure mast cell colonies could be serially replated four to five times. The replating efficiency of cells in the primary mast cell colonies varied over a wide range (2.5–44%) with an average replating efficiency of 13%. The data also revealed that cells containing metachromatic granules possess significant proliferative capacity. From these studies of pure and mixed mast cell colonies, we concluded (1) that mast cells are in wide variety of types of mixed colonies and that the in situ identification of mixed colonies is unreliable, (2) that mast cells are derived from pluripotent hemopoietic stem cells, and (3) that mast cells with metachromatic granules can have a high proliferating ability.
PGE1‐independent MDCK cells have elevated intracellular cyclic AMP but retain the growth stimulatory effects of glucagon and epidermal growth factor in serum‐free medium
Authors: Taub Mary , Devis Patricia E. , Grohol Sue Hiller 
Published: February 2005

AbstractProstaglandin E1 (PGE1), a component in the hormone‐supplemented, serumfree medium for the Madin Darby canine kidney (MDCK) cell line, has been proposed to increase MDCK cell growth by increasing intracellular cyclic AMP levels. The association between increased intracellular cyclic AMP and the growth stimulatory effect of PGE1 has been examined in normal MDCK cells and in PGE1‐independent variants of MDCK. These variant cells have lost the PGE1 requirement for long term growth in defined medium. Normal MCDK cells had almost twofold higher intracellular cyclic AMP levels during growth in Medium K‐1 (9.0 pmol/mg protein) than in Medium K‐1 minus PGE1. Furthermore, PGE1‐independent clone 1 had higher intracellular cyclic AMP levels in Medium K‐1 minus PGE1 than normal MDCK cells in Medium K‐1. This latter observation suggests that the PGE1 requirement for MDCK cell growth is associated with the low intracellular cyclic AMP levels of this cell line. An involvement of cyclic AMP in the growth response to PGE1 is supported by these observations, as well as by the growth stimulatory effects of other agents that affect cyclic AMP metabolism in MDCK cells. These agents include glucagon, isobutyl methylxanthine (IBMX), and dibutyryl cyclic AMP. The growth of PGE1‐independent clone 1 was inhibited rather than stimulated by PGE1. Similarly, PGE1‐independent cell growth was inhibited by IBMX and dibutyryl cyclic AMP. However, the growth response to one agent which increases cyclic AMP (glucagon) was retained in PGE1‐independent clone 1. This result suggests that the effect of glucagon is not associated with increases in intracellular cyclic AMP. The growth stimulatory effect of epidermal growth factor (EGF) on normal MDCK cells was also studied. Although EGF does not act via a cyclic AMP‐mediated mechanism, EGF increased normal MDCK cell growth and substituted for PGE1 in Medium K‐1. Thus, EGF and PGE1 could possibly affect similar growth‐related functions in MDCK cells, although by different pathways. This possibility was examined further, using PGE1‐independent clone 1. EGF, like glucagon, was still growth stimulatory to the PGE1‐independent cells. Consequently, the biochemical pathways by which EGF and PGE1 increase MDCK cell growth probably do not converge.
Clonal generation of multipotent and unipotent hemopoietic blast cell colonies in vitro
Authors: Keller Gordon , Holmes Wendy , Phillips Robert A. 
Published: February 2005

AbstractColonies with a unique compact morphology and displaying high replating potential develop in methycellulose cultures when bone marrow cells from hydroxyurea‐ or 5‐fluorouracil‐treated mice are cultured in the presence of syngeneic thymocytes. These compact colonies are clonal, originating from a single unit, the compact‐colony‐forming unit (CFU). Based on replating analysis, at least three groups of compact colonies exist: (1) those that do not replate, (2) those that replate and give only GM colonies, and (3) those that give rise to granulocyte‐macrophage (GM), erythroid (E), and mixed‐erythroid (MIX/E) colonies. Colonies in the last group have a mean size of 2,060 cells and generate an average of 244 colonies in secondary cultures. Velocity sedimentation studies showed the compact‐CFU to be similar in size to the MIX/E‐CFU, sedimenting at rates between 3.5 and 7 mm/hour. In addition to giving rise to large numbers of in vitro CFU, compact‐CFU are also able to generate day 8 spleen colony‐forming units (CFU‐S).
Partial characterization of the mitogenic action of pp60v‐src, the oncogenic protein product of the src gene of avian sarcoma virus
Authors: Durkin Jon P. , Whitfield James F. 
Published: February 2005

AbstractNRK cells infected with a temperature‐sensitive, transformation‐defective mutant of avian sarcoma virus (ASV), tsLA23, are transformed at 36°C, but at 40°C they behave as nontransformed cells because of the inactivation of the abnormally thermolabile pp60v‐src product of the virus' transforming src gene. At 40°C, these tsLA23‐NRK cells were arrested in G1/G0 by severe serum deprivation. They were induced to enter G1, initiate DNA synthesis 7 or 10 hours later, and then divide as (1) nontransformed cells by adding serum or platelet‐derived growth factor (PDGF) at 40°C, or (2) transformed cells by lowering the temperature to a pp60v‐src‐activating 36°C without adding exogenous growth factor(s). The level of pp60v‐src kinase activity rose dramatically in these serum‐deprived cells within 30 minutes of lowering the temperature to the permissive 36°C, and it fell just as rapidly when the cells were returned to the restrictive 40°C. As little as a 2‐hour exposure to 36°C, with an attendant 2‐hour burst of pp60v‐src kinase activity, was enough to stimulate serum‐deprived tsLA23‐NRK cells to transit G1 and initiate DNA replication, but not to divide. Much more prolonged pp60v‐src activity was needed for these serum‐deprived cells to complete their cycle and divide. The prereplicative development of quiescent tsLA23‐NRK cells stimulated by serum or PDGF was accompanied by greatly increased protein synthesis and slightly decreased protein degradation, but the pp60v‐src‐stimulated cells progressed through G1 and initiated DNA replication without appreciably affecting the protein synthetic machinery of the cell. The cells stimulated by the mitogenic action of pp60v‐src, like the cells stimulated by serum, needed to activate early prereplicative genes in order to initiate DNA replication. The needed RNA transcripts induced by serum and pp60v‐src were produced with comparable efficiency, although it took longer for pp60v‐src‐stimulated cells to translate these transcripts and to initiate DNA replication, probably because of their unstimulated protein‐synthetic machinery.
Induction of cytochrome P‐450 isozymes in rat hepatoma‐derived cell cultures
Authors: Frey Alan B. , Rosenfeld Melvin G. , Dolan William J. , Adesnik Milton , Kreibich Gert 
Published: February 2005

AbstractWe have investigated the responsiveness of established rat hepatocyte cell cultures to inducers of cytochrome P‐450. One Reuber hepatoma‐derived line (Fu5‐C8), which under normal culture conditions produces no detectable cytochrome P‐450(MC) or cytochrome P‐450(PB)—the major cytochrome P‐450 isozymes induced by 3‐methylcholanthrene and phenobarbital, respectively‐ was tested for the ability to accumulate either cytochrome P‐450 isozyme in response to treatment with various xenobiotics. By immune‐precipitation from [35S]‐methionine‐labeled cell extracts, using monospecific anticyto‐chrome P‐450(MC) antybody or monoclonal anticytochrome P‐450(PB) antibody, it was demonstrated that these cells possess the capability to synthesize cytochrome P‐450(MC) in response to 3‐methylcholanthrene treatment, while none of the drug treatments caused the synthesis of detectable quantities of cytochrome P‐450(PB). RNA extracted from Fu5‐C8 cells directed the in vitro synthesis of immune‐precipitable cytochrome P‐450(MC) only after treatment of the cells with 3‐methylcholanthrene Kinetic analysis of the response of these cells to 3‐methylcholanthrene induction revealed detectable levels of immune‐precipitable cytochrome P‐450(MC) 2 h after drug treatment with maximal induction occurring between 12 and 16 h of exposure. Another cell line (HF 1.5), obtained originally by hybridization of Fao X H5 variants of a Reuber H35 hepatoma, produces cytochrome P‐450(MC) and also cytochrome P‐450(PB) constitutively, as determined by specific immune‐precipitation from labeled cell extracts. Exposure of confluent monolayers to either phenobarbital or 3‐methylcholanthrene resulted in an induction of cytochrome P‐450(PB) or cytochrome F‐450(MC), respectively. Double‐labeling immunofluorescence studies indicate that all cells in the culture produce albumin and most of the cells produce cytochrome P‐450(MC), but only a subset of cells synthesize cytochrome P‐450(PB). Our results demonstrate that some continuously dividing hepatocyte cell cultures retain the capacity to respond to xenobiotics, including phenobarbital, a response which is typically exhibited by fully differentiated liver cells. Such established hepatocyte cell cultures should prove useful for investigating the mechanism of induction of cytochrome P‐450(PB).
Retinoic acid alters subcellular compartmentalization of ATP pools in 3T3 cells but not in HeLa cells
Authors: Schroder Edward W. , Rapaport Eliezer 
Published: February 2005

AbstractRetinoic acid (RA;β‐all‐trans) inhibits the proliferation of both murine 3T3 cells and human HeLa cells. Flow cytometric analyses of exponentially growing cultures show that 3T3 cells are inhibited during the S phase of their cell cycle, while HeLa cells show only a small increase in G1 phase cells. RA (10 μM) causes a 50% increase in total cellular adenosine triphosphate (ATP) pools of 3T3 cells, but not of HeLa cells. We have previously demonstrated that the effects of RA on cellular ATP pools of 3T3 cells are directly related to its inhibition of cellular growth, and now report data which provide a biochemical basis for this process. Established procedures were utilized to investigate the effects of RA on the functional compartmentalization of the nuclear ATP pool which serves as a precursor for RNA synthesis in these cells, and which is shown to be a small pool in comparison with cytoplasmic ATP pools. Expansion of total cellular ATP pools by 1 mM of exogenously supplied unlabeled adenosine is ineffective in reducing the subsequent incorporation of [3H]adenosine into RNA of 3T3 cells. Similar treatment of HeLa cells yields a modest reduction in the incorporation of [3H]adenosine into RNA. RA treatment of HeLa cells does not affect the preferential uptake of exogenous [3H] adenosine into the immediate precursor ATP pool for RNA synthesis. RA treatment of 3T3 cells markedly reduces the incorporation of [3H] adenosine into RNA, indicating a lesser degree of functional compartmentalization of the nuclear ATP pool. Similar conclusions are drawn from correlations of the specific radioactivities of total cellular [3H] ATP pools and the levels of incorporation of radioactive label into cellular RNA. In addition, pulse‐chase experiments show that RA‐treated 3T3 cells continue to incorporate radioactive label from pools prelabeled with [3H]adenosine despite the presence of a large excess of unlabeled adenosine in the chase medium. Control 3T3 and both control and RA‐treated HeLa cells cease to incorporate label immediately upon the start of the chase, suggesting that the functional precursor ATP pool for RNA synthesis is small and readily diluted. These data suggest that RA decreases the degree of functional compartmentalization for 3T3, but not HeLa cell ATP pools, and provides a probable mechanism for expansion of nuclear ATP pools of 3T3 cells. The expanded nuclear ATP pools may provide the biochemical mechanism for the inhibition of DNA synthesis during the S phase of the 3T3 cell cycle.
Changes in nuclear antigens during reactivation of chick erythrocyte nuclei in heterokaryons
Authors: Nyman Ulf , Lanfranchi Gerolamo , Bergman Mathias , Ringertz Nils R. 
Published: February 2005

AbstractReactivation of dormant chick erythrocyte (CE) nuclei was studied by fusing chick red cells with rat myoblasts, HeLa cells, and chick fibroblasts. Heterokaryons representing different stages of nuclear reactivation were fixed and examined for nuclear antigens using polyclonal patient autoantisera reacting with mammalian (human, mouse, and rat) nuclear envelope, nucleoplasm, and chromatin (DNA) antigens. Reactivation of CE nuclei was associated with marked changes in nuclear antigenicity. In rat myoblast and HeLa heterokaryons the CE nuclei acquired mammalian nucleoplasmic and nuclear envelope antigens in the corresponding nuclear subcompartments. Drastic changes in nuclear antigenicity were noted also in heterokaryons stained with DNA antisera. The compact chromatin of nuclei in mature chick erythrocytes showed little binding of DNA antibodies. Isolated nuclei on the other hand gave a strong immunofluorescence. CE nuclei in heterokaryons were strongly positive during the early stages of nuclear reactivation but then exhibited decreased reactivity. An unexpected finding was a marked reduction in the capacity of mammalian nuclei in heterokaryons to bind DNA‐antibodies. This observation is discussed in relation to the previous finding that in CE‐heterokaryons these nuclei often show reduced transcription and replication. The present results indicate that in heterokaryons both types of nuclei exchange macromolecules of regulatory importance via the common cytoplasm.
Regulation of thrombospondin secretion by cells in culture
Authors: Mumby Susanne M. , Abbott‐Brown Debbie , Raugi Gregory J. , Bornstein Paul 
Published: February 2005

AbstractThrombospondin (TS), a 450,000 molecular weight glycoprotein, is released from α‐granules of thrombin‐activated platelets and is secreted and incorporated into the extracellular matrix by several cell types in culture. We have examined the effects of cell density and transformation on the production of TS in cell culture. The levels of TS, per cell, in the culture medium of endothelial cells, smooth muscle cells, and fibroblasts were greater at lower cell densities; in fibroblasts the levels of two other extracellular matrix proteins, fibronectin and collagen, were unaffected by cell density. Our evidence indicates that the higher levels of TS in the culture medium, determined for lower‐density cells, were achieved by an increased secretion of the protein rather than by a reduction in degradation or incorporation into the extracellular matrix. TS production by normal and transformed Wl‐38 fibroblasts was the same, although the fibronectin level in the culture medium of the transformed cells was substantially decreased. These findings suggest that the production of TS by cells in culture is regulated in a different fashion from that of fibronectin or collagen.
Effects of sodium butyrate on growth and cell‐cycle kinetics of cultured rabbit articular chondrocytes
Authors: Larno Suzanne , Ronot Xavier , Adolphe Monique , Lechat Paul 
Published: February 2005

AbstractThe sodium salt of n‐butyric acid was found to inhibit the growth of asynchronous cultures of rabbit articular chondrocytes. This inhibitory effect was dose‐dependent between 1 mM and 5 mM, reversible, and accompanied by volume enhancement and modification of cellular morphology. Flow‐cytometric analysis showed that drug exposure led to a slowing‐down of the cell‐cycle progression; after 1 day's exposure, cells accumulated in G1, and after 2 or 3 days' treatment, in G2, without a blockage in M; the increase of cells in G2 was in fact due to an enhancement of binculeated cells. The treated cells had an increased RNA content. Articular chondrocytes seem to be target cells for sodium butyrate and therefore it represents a valuable biological tool for studying the mechanisms of their growth regulation.
Serum and substratum‐dependent coupled loss of differentiated and tumorigenic phenotypes in B16‐conv melanoma cells
Authors: Sato Seiji , Yamamoto Hiroaki , Yonezawa Minoru , Takeuchi Takuji 
Published: February 2005

AbstractClonal B16 mouse melanoma conv cells are tumorigenic spindle‐shaped cells (S‐type cells) exhibiting tyrosinase activity and melanosomes under usual culture conditions. When the cells passaged on glass substratum were plated for colony formation on plastic substratum in Eagle's minimum essential medium (MEM) with 10% calf bovine serum, most of them converted to fibroblastlike cells (F‐type cells) with the coupled loss of differentiated and tumorigenic phenotypes. However, they continued to be S‐type cells provided that they were plated on glass substratum. The conversion from S‐ to F‐type cell was not induced with high frequency even on plastic substratum when the concentration of calf serum in the medium was low (1–2%). These results indicate that both plastic substratum and serum factor are requisites for converting the phenotypic expression of the conv cells. Partial characterization of the serum factor indicates that it is adsorbable to plastic substratum, inactivated at 70°C for 10 min, salted out at 40% of saturated ammonium sulfate; in addition the factor seems to act on cells within 1 day after plating.
Junctional competence in clones of mammary epithelial cells, and modulation by conditioned medium
Authors: Stoker Michael 
Published: February 2005

AbstractColony‐forming epithelial cells exfoliated in human milk have been examined by immunofluorescence using antibodies to cytokeratins (tonofilaments), and to high molecular weight desmosomal core proteins. The cells may be classified by their ability to form junctional complexes with their neighbours. Those deficient in desmosomal junctions, called D − cells, grow into colonies of noncontiguous cells without desmosomes, and with a perinuclear network arrangement of cytokeratins. Junction forming, or D + cells, grow as contiguous cell sheets with abundant desmosomes and well developed bundles of tonofilaments. D − cells may also segregate D + cells among their progeny yielding mixed clones, and a gradual increase in the overall number of D + cells during culture. Established D + cells have surface markers characteristic of mammary epithelium and are presumably derived by exfoliation of luminal cells of the alveoli or ducts which contain desmosomal junctions. D − cells also possess mammary epithelial cell markers, but their origin is unknown. Medium conditioned by the Nil 8 line of hamster cells contains a junction‐promoting activity that accelerates the rate, or frequency, of segregation of D + cells from D − cells, so that milk cells grown in this medium predominently give closed colonies of D + cells. Medium conditioned by the MRC5 strain of human embryo lung cells, however, contains a junction‐inhibiting activity, which prevents new junction formation and probably destroys existing junctions, so that cells in this medium mostly grow as open colonies of cells with D − phenotype. It is hoped that studies with this experimental system will assist in the better understanding of normal and abnormal regulation of desmosomal junctions and their role in tissue integrity.