摘要:

AbstractNeoplastic cell lines exhibit RNA synthesis and process patterns which are related to phenotypic attributes more complex than merely the rate of proliferation. Mouse neuroblastoma cells of the same genotype but different differentiated states have different ribosomal RNA precursor processing patterns, while plasmacytoma cells of different genotypes but the same differentiated state have the same pre‐ribosomal RNA processing pattern. In addition, our observations indicate that chromatin‐associated RNA is involved in cytodifferentiation and is closely related to phenotypic variability. When neuroblastoma cells are induced to differentiate, there is a 2‐ to 3‐fold increase in the labeling of chromatin‐associated RNA. Both of the differentiated cell lines, human myeloma and mouse neuroblastoma, have slow‐labeling, stable chromatin‐associated RNA while this same fraction from HeLa cells is labeled rapidly an

ISSN:0021-9541    

DOI:10.1002/jcp.1040910102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractA permanent, clonal strain of rat pituitary tumor cells (GH3‐cells) spontaneously synthesizes and secretes prolactin (rPRL) and growth hormone (rGH) into the culture medium. The rates of hormone production (μg extracellular hormone/mg cell protein/24 hours) and synthesis (vida infra) as well as the rate of [3H]thymidine incorporation into DNA (DNA synthesis) have been studied.During logarithmic growth rPRL and rGH production increased to 160 and 250% of the value at day 2 after plating, while during the plateau phase of cell growth hormone production decreased to initial values. The fluctuations in rPRL production could be fully explained by variations in the rate of rPRL synthesis: [3H]leucine incorporated into rPRL as measured with immunoprecipitation and polyacryl‐amide gel electrophoresis. Also the rates of synthesis and production of rGH showed parallel changes during exponential and plateau phase of growth, but this hormone was probably degraded intracellularly. The relative reduction in the rate of synthesis of rPRL and rGH during the plateau phase of growth corresponded closely to the fall in the rate of DNA synthesis. The reduction in rPRL synthesis could not be explained through an inhibition by extra‐cellular rPRL accumulation or by cell to cell interaction occurring in dense cultures.The intracellular concentrations of both hormones were unaltered during logarithmic growth, but rose to 500% for rPRL and 200% for rGH during the plateau phase.In spite of the marked variations in basal rPRL and rGH production, the GH3cultures of different ages were equally able to increase rPRL and decrease rGH production in response to thyrotropin releasing hormone (3 X 10−7M) and 17β‐estrad

ISSN:0021-9541    

DOI:10.1002/jcp.1040910103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractThe expression of extracellular fibrinolytic activity in untransformed 3T3 cell cultures depends on the growth state of the cells. Actively growing 3T3 cultures exhibit a relatively high level of fibrinolysis, which decreases progressively as the cells become confluent and density‐inhibited. The low level of fibrinolytic activity in confluent 3T3 cultures is due to a diminution in secretion of plasminogen activator since the intracellular level of plasminogen activator remains high. The amount of plasminogen activator observed in growing 3T3 cultures varies depending upon whether the cells are passaged with trypsin/EDTA solution, or with the Ca++selective chelating agent, ethylene‐bis (oxyethylenenitrilo) tetraacetic acid (EGTA). However, in cells passaged using either agent, the amount of plasminogen activator secreted is always greatest when the cells are actively growing and decreases thereafter. In contrast to confluent 3T3 cultures, dense cultures of SV40‐virus transformed 3T3 cells continued to secrete relatively large amounts of plasminogen activator. The ability to decrease secretion of plasminogen activator as cells become dense may be an important characteristic of cells which demonstrate density‐dependent inhibition of cell multiplication i

ISSN:0021-9541    

DOI:10.1002/jcp.1040910104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractA series of variant lines that utilize multiple pentoses for growth in place of glucose have been isolated from an 8‐azaguanine resistant line of Novikoff hepatoma cells (N1S167). These variants utilize for growth ribose, xylose, arabinose, and/or deoxyribose. The variants growing on pentose containing medium (a) exhibit a density dependent cessation of growth, (b) have a morphology change to a more flattened cell type, (c) become binucleated in the presence of cytochalasin B, and (d) show an altered sensitivity to trypsin treatmen

ISSN:0021-9541    

DOI:10.1002/jcp.1040910105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractThe increase in tyrosine aminotransferase activity which occurs in rat hepatoma tissue culture (HTC) cells in response to cyclic AMP analogs has been shown to be an enzyme induction, similar to the larger response observed in certain other hepatoma cells and in liver. A specific antibody to tyrosine aminotransferase has been used to show that the number of enzyme molecules and the rate of enzyme synthesis are increased by N6,O2′‐dibutyryl cyclic AMP in HTC cells. The effect on tyrosine aminotransferase is also produced by various 8‐substituted derivatives of cyclic AMP and occurs whether or not the enzyme has been preinduced with a glucocorticoid. The response of the enzyme is greater when HTC cells are maintained in monolayer than in suspension cultures. Neither cell growth nor serum is required for the res

ISSN:0021-9541    

DOI:10.1002/jcp.1040910106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractCell division, neurite formation and acetylcholinesterase activity were examined in a clone (NBA2) of mouse neuroblastoma cells maintained for up to 120 hours in medium with pH values between 6.6 and 8.0. Growth rate decreased as pH was reduced from 7.8 to 6.6. Generation time at pH 7.4 was 25 hours, while the rate of cell division was negligible at pH 6.6. The total number of cells at stationary phase was less at the lower pH values. Neurite formation was enhanced markedly as the pH was reduced from 7.4 to 6.6. Acetylcholinesterase activity was 5‐ to 8‐fold greater in cells exposed to medium at pH 6.6 than in cells maintained in medium at pH 7.4. The reduction in the rate of cell division and increases in neurite formation and acetylcholinesterase activity at pH 6.6 were reversible upon exposure of the cells to pH 7.4 medium. Cell viability was greater than 90% at all medium pH values over a period of 120 hours. Uncloned T‐59 mouse neuroblastoma cells were affected similarly by changes in pH. These results show that manipulation of the environmental pH can reversibly alter growth, neurite formation, and acetylcholinesterase activity of mouse neuroblastoma cells in cu

ISSN:0021-9541    

DOI:10.1002/jcp.1040910107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractA method, based on the differing capacities of cells to adhere to a column of polyester fibres, has been described for separating human bone marrow cells into a nonadherent and an adherent fraction. The effect of this cell separation procedure on colony formation by erythroid progenitor cells was investigated. In contrast to the unseparated population, it was found that erythropoietin‐dependent erythroid colony formation by nonadherent cells could be considerably enhanced by the addition of leukocyte conditioned medium to the cultures. Similar erythroid enhancing activity was also detected in a partially purified preparation of granulocytic colony stimulating activity obtained from human embryo kidney culture supernatants.Erythroid colony formation in the absence of added erythropoietin, by non‐adherent bone marrow cells from patients with polycythemia rubra vera, were also enhanced by the addition of LCM to the cultures. This finding suggests that the enhancing factor in LCM may not be dependent on the presence of erythropoietin in the cultures for its activity.While the cellular mechanisms by which leukocyte conditioned medium enhances eyrthroid growth remain to be determined, the data presented provides strong evidence for the view that the plating efficiency of erythroid progenitor cells is determined not only be the concentration of erythropoietin, but also by the presence of leukocyte conditioned medium in the cultu

ISSN:0021-9541    

DOI:10.1002/jcp.1040910108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractWhole serum and elevated pH previously had been found to stimulate both cell multiplication and hyaluronic acid production by chick embryo fibroblasts in culture. In a study to determine whether cell multiplication and hyaluronic acid production both respond to a single well‐defined substance, insulin was found to stimulate, and cortisol to inhibit both processes coordinately. It appears, therefore, that multiplication and differentiated function in fibroblasts respond to a common underlying regulatory signal.Inhibition of ribosomal RNA synthesis by actinomycin D does not prevent serum stimulation of hyaluronic acid production, but inhibition of total RNA synthesis does. If total RNA synthesis is inhibited only after the hyaluronic acid production has reached a new high level, it continues at that level for the next five hours. The stimulatory treatment causes an increase in the activity of the enzyme hyaluronate synthetase. Inhibition of protein synthesis prevents any increase in hyaluronic acid production, and reduces the basal level of production.Reduction of the availability of Mg2+in the medium coordinately inhibits DNA synthesis and hyaluronic acid production. The results are discussed in the light of a model for coordinate control of growth and metabolism based on the availability of Mg2

ISSN:0021-9541    

DOI:10.1002/jcp.1040910109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractThe effects of 2‐deoxyglucose (DOG), an inhibitor of glycolysis, on guinea pig polymorphonuclear leukocytes (PMN) obtained from peritoneal exudates was examined. ATP levels in PMN were reduced by 40% by one hour following an incubation with 2‐deoxyglucose. When complement (C3) coated14C‐staphylococcus aureus, C3 coated lipopolysaccharide‐paraffin oil droplets (LPSPO),14C‐pneumococcus opsonized with IgG, or albumin coated paraffin oil droplets opsonized with IgG were added to cell suspensions containing DOG, the phagocytizing rate was 1,310 ± 55 cpm/5 x 106cells/15 minutes, 6 ± 2 μg paraffin oil (PO)/107cells/minute, 2,250 ± 175 cpm/1 x 106cells/20 minutes or 0.037 ± 0.01 mg PO/107cells/minute compared to control values of 5,970 ± 275 cpm/5 x 106cells/15 minutes, 35 ± μg PO/107cells/15 minutes, 4,510 ± 200 cpm/1 x 106cells/20 minutes and 0.067 ± 0.01 mg PO/107cells/minute. In parallel studies the phagocytic index for latex was 0.74 ± 0.28 in DOG compared to control of 2.36 ± 1.13 and the phagocytic rate of albumin coated paraffin oil droplets was 0.029 ± 0.01 mg PO/107PMN/minute in DOG compared to control of 0.048 mg PO/107cells/minute. When ATP levels were maintained by the simultaneous addition of 5 mM glucose or pyruvate to media containing DOG, latex ingestion was improved to 1.15 ± 0.3 with glucose and 1.59 ± 0.64 with pyruvate and albumin coated particles to 0.045 ± 0.01 mg PO/107PMN/minute with pyruvate. There was no improvement in the uptake of either the C3 dependent particles or IgG coated Pneumococci in media containing DOG and glucose and/or pyruvate. Following the removal of DOG from the extracellular medium and the addition of pyruvate or glucose, phagocytosis of C3 dependent LPS‐PO was restored to normal values. Neither the binding of C3 or IgG coated particles to the PMN nor the lateral movement of glycoprotein utilizing concanavalin A capping was affected by DOG. Thus, the presence of DOG in the PMN containing adequate amounts of ATP will selectively and reversibly inhibit those surface events required for phagocytosis of C3 and IgG bound particles but not latex particles or albumin particles which n

ISSN:0021-9541    

DOI:10.1002/jcp.1040910110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractThe physiology and pharmacology of a depolarizing dopamine response was studied in the vertebrate neuronal somatic cell hybrid TCX11. The average resting membrane potential was −50 mV (S.D. = ±7) with a membrane resistance of 40.5 mOhms (S.D. = ±8) as determined from intracellular recordings. Depolarizing current pulses did not elicit an action potential. Cells displayed a linear current‐voltage relationship when artificially depolarized up to +30 mV. Iontophoretically applied dopamine elicited a depolarizing response with a conductance increase and a reversal potential of −15 mV (S.D. = ±4.7). Experiments altering medium ion concentrations demonstrated the conductance increase was to sodium and most likely potassium. The dopamine agonist ET495 (Piribedil) and the analogue epinine mimicked dopamine, while closely related biogenic amines, with the exception of noradrenaline, elicited no response. Apomorphine also elicited a depolarizing response but was much less efficacious than Piribedil. Noradrenaline was less potent than dopamine and appeared to act at the dopamine receptor. Methylation (3‐methoxytyramine) or absence of the 3‐hydroxy group (tyramine) of dopamine resulted in total loss of activity. The dopamine antagonists chlorpromazine, trifluoperazine, promazine, and bulbocapnine reversibly blocked the response to dopamine at medium concentrations less than 5 μM. The adrenergic antagonist phentolamine blocked the response while phenoxybenzamine only reduced the response at higher concentrations. The acetylcholine antagonists α‐bungarotoxin, hexamethonium, and scopolamine did not block the dopamine response. Both d‐tubocurarine and atropine acted as antagonists.Collectively, these results demonstrate the presence of a receptor on a cultured cell line that is specific for dopamine, mediates a depolarizing and conductance increase response to dopamine, and displays the pharmacology most closely associated with

ISSN:0021-9541    

DOI:10.1002/jcp.1040910111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY