摘要:

AbstractThe role of microtubules in mitogen‐induced human lymphocyte activation and proliferation was examined. The effect of colchicine, a microtubule‐disrupting agent, was compared with taxol, a microtubule‐stabilizing drug, and with isaxonine (N‐isopropyl‐amino‐2‐pyrimidine orthophosphate), a proposed microtubular‐active drug. Lymphocyte proliferation, assessed by measuring the increase in the number of cells in mitogen‐stimulated cultures, was completely suppressed by both colchicine and taxol (100 nM) whereas significant inhibition by isaxonine required much higher concentrations (5 mM). In order to characterize the inhibition, initial lymphocyte blast transformation and subsequent DNA synthesis were investigated. Neither colchicine nor taxol inhibited lymphocyte blast transformation assessed by quantitating the change in volume of the stimulated cells after a 24‐hour incubation. In contrast, isaxonine (2–5 mM) suppressed blast transformation. Initial DNA synthesis, evaluated by measuring the cumulative incorporation of [3H]thymidine between 30 and 48 hours of culture, was inhibited in a concentration‐dependent manner by both isaxonine and colchicine but not by taxol. Electron microscopic studies confirmed that both taxol and colchicine (10 nM) arrested the responding lymphocytes in mitosis, and that isaxonine inhibited initial activation. These results suggest that normal microtubule function is only necessary for cell division and that drug effects on blast transformation and initial DNA synthesis are un

ISSN:0021-9541    

DOI:10.1002/jcp.1041160202

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe effects of hemin (Fe‐protoporphyrin) and Co‐protoporphyrin on cellular growth have been investigated principally in cultured fibroblasts, but also in myoblasts and hepatocytes from chick embryos. In the presence of horse serum in the culture medium, which by itself did not stimulate cell growth appreciably, Co‐protoporphyrin stimulated cell attachment while hemin stimulated cell proliferation of fibroblasts. When Co‐protoporphyrin and hemin were added together, the most potent stimulation of cell growth, consisting of increases in cell attachment and rapid cell proliferation, was observed. These findings indicate that the two metalloporphyrins have differential and complementary effects on cellular growth in culture, with synthetic Co‐protoporphyrin principally affecting cellular attachment and Fe‐protoporphyrin stimulating cellular pr

ISSN:0021-9541    

DOI:10.1002/jcp.1041160203

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

年代:1983

数据来源: WILEY

摘要:

AbstractIn an effort to determine whether the Na+‐dependent Pitransport system of Ehrlich ascites tumor cells exhibits specificity for H2PO4−or HPO4−2, Pifluxes were determined by measuring32PiPiself‐exchange. Three experimental approaches were employed. First, the effect of pH on steady‐state Pitransport at 0.5 and 5 mM was studied. Second, the relationship between Pitransport and Piconcentration (0.25–9.2 mM) at pH 5.6 and 7.9 was determined. Third, the dependence of Pitransport on [H2PO4−] (0.05–4.2 mM) at constant [HPO4−2] (0.5 mM), and the converse, [HPO4−2] (0.06–4.5 mM) at constant [H2PO4−] (0.5 mM), was evaluated. Ks(apparent half‐saturation constant) and Jmax(maximal transport rate) were calculated by two methods: weighted linear regression (WLR) and a nonparametric procedure. The dependence of Piflux on pH indicates that optimum transport occurs at pH 6.9. Pitransport decreases as pH is reduced when extracellular Piis either 0.5 or 5 mM. However, at pH 7.9, Piflux is reduced only in 0.5 mM Pi. At pH 5.6, H2PO4−comprises 93% of the total Pipresent, and the calculated Ksis 0.055 ± 0.026 mM (WLR). This is the same as the Ksdetermined from the initial phase of the flux vs. [H2PO4−] relationship (0.056 ± 0.020 mM). However, at pH 7.9 (where 94% of Piis HPO4−2), the measured Ksis 0.58 ± 0.11 mM (WLR), which is ten times higher than at pH 5.6. This value is also five times greater than the Kscalculated from the flux vs. [HPO4−2] curve (0.106 ± 0.16 mM). Kinetic parameters calculated by the nonparametric method, though somewhat different, gave similar relative results. Taken together, these results support two conclusions: (1) H2PO4−is the substrate for the Na+‐dependent Pitransport system of the Ehrl

ISSN:0021-9541    

DOI:10.1002/jcp.1041160204

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe recruitment into the cycling state of resting Yoshida AH 130 hepatoma cells was studied with respect to its dependence on respiration in an experimental system wherein the overall energy requirement for this recruitment can be supplied by the glycolytic ATP. The G1‐S transition of these cells, unaffected by 2,4‐dinitrophenol (DNP) at concentrations which uncouple the respiratory phosphorylation, is impaired either by blocking the electron flow to oxygen by antimycin A or by adding an excess of some oxidizable substrates, chiefly pyruvate and oxalacetate. An experimental analysis, focused on pyruvate activity, showed that the inhibition of cell recruitment into S is not related to the depressing effects of this substrate on aerobic glycolysis of tumor cells, nor is it modified by forcing, in the presence of DNP, pyruvate oxidation through the tricarboxylic acid cycle as well as the overall oxygen consumption. Addition of suitable concentrations of preformed purine bases (mainly adenine), completely removes the block of the G1‐S transition produced either by the excess of oxidizable substrates or by antimycin A. These findings indicate the existence of a respiration‐linked step in purine metabolism, which restricts the above transition and is equally impaired by blocking the respiratory chain or by saturating it with an excess of reducing equivalents derived from unrelated oxidations. The inhibitory effects of pyruvate and antimycin A can be largely removed by the addition of folate and tetrahydrofolate, suggesting that the respiration‐linked restriction point of tumor cell cycling involves the folate metabolism and its connections to purine

ISSN:0021-9541    

DOI:10.1002/jcp.1041160205

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

年代:1983

数据来源: WILEY

摘要:

AbstractDifferences between the behavior of cultured rat skin fibroblasts and that of a line of transformed rat sarcoma cells incorporated into a polymerized collagen lattice were examined. Fibroblast‐populated collagen lattices (FPCL) were manufactured. Within 24 to 48 hr after manufacture, both cell lines reduced lattice size by a process known as lattice contraction. Contraction occurred more rapidly in both cell lines when the media were supplemented with 25% serum rather than the usual concentration of 10% serum. Similar growth patterns were observed with transformed cells within collagen lattices and on plastic surfaces. Normal rat fibroblasts were found to contract lattices faster than transformed cells. At the end of a 2‐week period, the final contracted size of the transformed cell lattice was the same as that of normal cell lattices. The cellular density of transformed cells within the FPCL was eight times greater than that of FPCL made with normal rat cells. Normal rat fibroblasts elongated and flattened more, and organized the collagen matrix to a greater degree, than did transformed cells. In this instance, therefore, lattice contraction was shown to be linked more to the process of fibroblast elongation and collagen fiber organization than to cell number or dens

ISSN:0021-9541    

DOI:10.1002/jcp.1041160206

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe effect of epinephrine was tested on the proliferation of rat arterial smooth muscle cells (SMC) in secondary cultures. Epinephrine added daily to the culture medium caused a striking stimulation of growth. The effect increased with time and was dose‐dependent. Maximal stimulation was observed at a concentration of 1010−5M and after 72 hours. At higher concentrations (10−3M) epinephrine exhibited toxic effects on SMC. When SMC were maintained quiescent by deprivation of serum, the subsequent addition of epinephrine required serum to significantly enhance growth. This growth stimulation increased with serum concentration (from 0.1 % to 10%). All the adrenergic agonists tested were found to stimulate SMC growth, with an activity classified by decreasing order as follows: norepinephrine>epinephrine>isoproterenol. Finally, this mitogenic response of SMC to catecholamines was specific since it could be blocked by adrenergic blocking agents, phentolamine being more efficient than propranolol in that connection. The results suggest that epinephrine and other catecholamines may act as growth factors for aortic SMC, at least in rat, mostly through adrenorece

ISSN:0021-9541    

DOI:10.1002/jcp.1041160207

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

年代:1983

数据来源: WILEY

摘要:

AbstractLittle metabolic information is available for cells cultured from umbilical vascular tissue. These studies were undertaken to compare the metabolism of cells isolated from human umbilical arteries and veins with that of umbilical vascular segments. These studies also compared umbilical vascular cells to standard fibroblast preparations. Oxygen consumption by umbilical venous cells or tissues was greater than that for either arterial cells or tissues. Cellular adenosine triphosphate (ATP) content was greater in umbilical venous than arterial cells. However, an oxidation‐phosphorylation ratio (R) was constant for either arterial or venous cells. Oxygen consumption by vascular cells was greater than that by nonvascular cells, as was cellular ATP content. R for nonvascular cells was much greater than that for vascular cells, indicating loose coupling between oxygen consumption and cellular ATP content. Finally, cellular oxygen consumption was dependent upon cell density, and upon media serum content in vascular endothelial cells. We conclude therefore that the metabolism of umbilical vascular cells in culture reflects that of the parent tissue but is different from that of either vascular or nonvascular fibroblast

ISSN:0021-9541    

DOI:10.1002/jcp.1041160208

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

年代:1983

数据来源: WILEY

摘要:

AbstractSeveral properties of embryonal carcinoma (EC) cell lines, such as multipotent PCC4‐aza‐1 cells and nullipolent F9 cells originating from murine teratocarcinoma cells, were examined after treatment with 5‐azacytidine, which produces undermethylated DNA. Drug‐treated PCC4‐aza‐1 cells exhibited morphological changes and differentiated, whereas azacytidine‐treated F9 cells displayed no detectable morphological change. After treatment with 5 azacytidine, PCC4‐aza‐1 cells, whether or not they differentiated, as well as F9 cells, became permissive for polyoma even though both cell types are usually resistant to polyoma. In contrast, only the differentiated azacytidine‐treated PCC4‐aza‐1 cells became sensitive to SV40 infection, i.e., synthesized T antigen, despite the resistance normally shown by such cells to this viral infection. In some PCC4‐aza‐1 and F9 cells, drug treatment induced expression of H2 antigen but did not derepress plasminogen activator synthesis. These results suggest that undermethylation of certain cellular genes in PCC4‐aza‐1 and F9 cells is correlated with the establishment of Py permissivity, SV40 sensitivity, H2 antigen expression, and the triggering of a differentiation process. The relationship between the expression of these characters a

ISSN:0021-9541    

DOI:10.1002/jcp.1041160209

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

年代:1983

数据来源: WILEY

摘要:

AbstractIn serum‐free medium, insulin‐like growth factor‐I/somatomedin‐C (IGF‐I/SM‐C) was weakly mitogenic for adult human fibroblasts in culture. However, in the presence of 0.5% human hypopituitary serum (HHS), which by itself had little effect, there was a marked dose‐dependent response to IGF‐I/SM‐C with a 10‐ to 20‐fold increase in [3H]thymidine incorporation at 25 ng/ml IFG‐I/SM‐C. With the further addition of dexamethasone or hydrocortisone to the combination of IGF‐I/SM‐C + 0.5% HHS, there was a dramatic synergistic effect resulting in a 60‐ to 70‐fold increase in [3H]thymidine incorporation. This stimulation was two times greater than that seen with 20% FCS. In contrast, glucocorticoids had no effect in serum‐free medium or with HHS alone. These [3H]thymidine incorporation results were clearly supported by cell replication studies. Dose‐response curves for125I IGF‐I/SM‐C binding and IGF‐I/SM‐C stimulation of [3H]thymidine incorporation were similar with 1/2 maximal effects for both at 5 ng/ml. However, the striking synergism seen with glucocorticoids occurred in the absence of any glucocorticoid‐induced change in IGF‐I/SM‐C binding, indicating that the interaction of IGF‐I/SM‐C and glucocorticoids occurs at a postreceptor level. These data demonstrate that in the presence of a low concentration of HHS, IGF‐I/SM‐C and glucocorticoids stimulate comple

ISSN:0021-9541    

DOI:10.1002/jcp.1041160210

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

年代:1983

数据来源: WILEY

摘要:

AbstractWhen granulocyte colony‐stimulating factor (G‐CSF), purified to homogeneity from mouse lung‐conditioned medium, was added to agar cultures of mouse bone marrcw cells, it stimulated the formation of small numbers of granulocytic colonies. At high concentrations of G‐CSF, a small proportion of macrophage and granulocyte‐macrophage colonies also developed. G‐CSF stimulated colony formation by highly enriched progenitor cell populations obtained by fractionation of mouse fetal liver cells using a fluorescence‐activated cell sorter, indicating that G‐CSF probably acts directly on target progenitor cells. Granulocytic colonies stimulated by G‐CSF were small and uniform in size, and at 7 days of culture were composed of highly differentiated cells. Studies using clonal transfer and the delayed addition of other regulators showed that G‐CSF could directly stimulate theinitialproliferation of a large proportion of the granulocvte‐macrophage progenitors in adult marrow and also the survival and/or proliferation of some multipotential, erythroid, and eosinophil progenitors in fetal liver. However, G‐CSF was unable to sustain continued proliferation of these cells to result in colony formation. When G‐CSF was mixed with purified granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) or macrophage colony‐stimulating factor (M‐CSF), the combination stimulated the formation by adult marrow cells of more granulocyte‐macrophage colonies than either stimulus alone and an overall size increase in all colonies. G‐CSF behaves as a predominantly granulopoietic stimulating factor but has some capacity to stimulate theinitialproliferation of the same wide range of progen

ISSN:0021-9541    

DOI:10.1002/jcp.1041160211

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

年代:1983

数据来源: WILEY