摘要:

AbstractThe interaction of human peripheral blood lymphocytes, monocytes, gram‐positive bacteria and human serum in the release of colony stimulating activity (CSA) has been studied. CSA was assayed by the soft agar technique using human and murine bone marrow cells. It has been demonstrated that gram‐positive organisms and their products can stimulate release of CSA by mononuclear cells. Human serum is also effective in promoting release of CSA. Release is further modulated by interactions between lymphocytes and monocytes, and lymphocytes may serve to control the modulation. The serum component is sensitive to temperature inactivation suggesting that it may have a specific physiologic role in regulation. Bacterial products, on the other hand, are not subject to temperature inactivation and require the presence of human serum for activity to be expres

ISSN:0021-9541    

DOI:10.1002/jcp.1040920202

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

年代:1977

数据来源: WILEY

摘要:

AbstractThe extent to which autolytic microbial enzymes are involved in the fate of microorganisms ingested by phagocytes has not been determined. It is known, however, that activation of degradative enzymes occurs during certain microbicidal events.We examined the possible role of the pneumococcal autolytic enzyme (an N‐acetylmuramyl‐L‐alanine amidase) in the loss of viability and degradation of pneumococci during phagocytosis by rabbit polymorphonuclear leukocytes. Three bacterial systems were compared: (a) wild type pneumococci with an active autolytic system; (b) wild type bacteria grown under conditions that block the endogenous autolytic activity and (c) a mutant strain defective in the major autolytic enzyme of this bacterium. No differences could be detected between the autolysis‐positive and negative bacteria in the rate of killing and in the fate of macromolecular cell constitutents during ingestion by rabbit peritoneal polymorphonuclear leu

ISSN:0021-9541    

DOI:10.1002/jcp.1040920203

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

年代:1977

数据来源: WILEY

摘要:

AbstractThe ability of D‐valine medium to inhibit fibroblasts in cultures derived from kidneys of various mammals has enabled the selective proliferation of epithelial cells in the absence of fibroblast overgrowth. Studies of these selected epithelial cells have demonstrated the presence of D‐amino acid oxidase, carbonic anhydrase, high levels of alkaline phosphatase and the renal specific pattern of lactate dehydrogenase. The presence of these renal enzymes suggests that the selected epithelial cells are of renal tubular origin and indicates that these differentiated functions are retained in cultured ce

ISSN:0021-9541    

DOI:10.1002/jcp.1040920204

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

年代:1977

数据来源: WILEY

摘要:

AbstractAlbumin in low concentrations (0.001–0.01 weight percent) was found to be an effective inhibitor of phagocytosis of polystyrene latex beads by rabbit polymorphonuclear leukocytes. Polyglutamic acid proved to be an inhibitor of latex uptake at even lower concentrations. Polylysine stimulates phagocytosis, maximal stimulation occurring at 0.002% polylysine. These findings are discussed with reference to the surface properties of latex particles and leukocytes, and particularly with reference to electrostatic interactions in phagocytosi

ISSN:0021-9541    

DOI:10.1002/jcp.1040920205

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

年代:1977

数据来源: WILEY

摘要:

AbstractEndothelial cells (EC) line the heart and blood vessels, and they are the principal cellular components of the microvasculature. The presence of circulating platelets is believed to be necessary to maintain the integrity of the capillary endothelium. Growing EC in culture provides an opportunity to simulate the in vivo situation and to study the response of these cells to platelets and platelet secretions. The addition of platelets at a concentration of 104‐105/mm3and substances which circulate in blood following injury (serotonin, thrombin, ADP, epinephrine, norepinephrine and histamine) stimulate endothelial proliferation from 150–1,000% of controls. That substances so diverse in form have similar effects suggests a common mode of action, such as mobilization of a second messenger. The influx of45calcium (45Ca++) in response to these agents was found to be 5 to 24 times that of controls. The stimulation of45Ca++influx appears to be dose‐dependent, and it is inhibited by pre‐incubation with lanthanum chloride and specific blocking agents. Calcium as a second messenger is implicated in a variety of cellular functions including division, secretion, motility and enzyme regulation. Thus, the theorized supportive role of platelets on endothelium may be dual and operate, at least at the initial level, by a common mechanism: to mobilize calcium for stimulus‐division following injury and for stimulus‐secretion in normal metabolic

ISSN:0021-9541    

DOI:10.1002/jcp.1040920206

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

年代:1977

数据来源: WILEY

摘要:

AbstractThe nucleoside transport of systems of hamster cells are susceptible to inhibition by S‐6‐substituted derivatives of mercaptonucleosides. The mechanism of interaction between the most potent inhibitor of the class, 6‐nitrobenzyl mercaptoinosine (NBMI) and the uridine transport system of hamster fibroblasts is studied in the present work. A kinetic description of the interaction is presented. Uridine transport is inhibited in a partially competitive fashion, leaving a substantial free fraction of the transport (20–30%) virtually insensitive to increasing concentrations of inhibitor. One interpretation compatible with the kinetic and chemical properties of the system assumes that binding of the inhibitor to carriers occurs at sites different from the substrate binding sites (allosteric binding). Such a binding induces a conformational change in the carrier as manifested in a reduced affinity to the substrate and a susceptibility to inhibition by organomercurials. The alternative interpretation postulates two parallel transport systems which display distinctly different susceptibilities to NBMI and to organomercurials. Experiments performed with non‐penetrating organomercurials show that the sulfhydryl groups related either to the alleged allosteric components or to additional carriers, are located superficially on the membrane. The binding of NBMI is reversible, the affinity is extremely high (Ki = 0.15 nMolar) and the rate of reaction could probably be diffusionally limited at low concentrations of reagent (activation energy 250 cal/mole, rate k = 1.3.108min−1. Molar−1). The high affinity properties of the probes are used to determine the number of NBMI binding sites. A value of 47,000 and 77,000 sites/cell was obtained by two separate methods.The possibility that allosteric properties are present in carrier systems are discussed in terms of current concepts of modulation of transport functions in biologi

ISSN:0021-9541    

DOI:10.1002/jcp.1040920207

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

年代:1977

数据来源: WILEY

摘要:

AbstractIn vitro moocyte‐macrophage colony‐forming cells (CFC) have been detected in the thymus (30/106cells) and in the cervical (22/106) and mesenteric (20/106) lymph nodes (LN) of the mouse. Thymus and LN derived CFC differed from bone marrow derived CFU‐c in several characteristic parameters: (1) sole specificity of PMUE to induce colony formation (CF), (2) apparent singular line of monocyte‐macrophage differentiation, (3) a marked 6‐ to 10‐day lag period prior to initiation of CF, and (4) significantly slower rates of appearance of colonies in culture after initiation of CF. Two of these parameters are shared with those CFC detected within alveolar space, peritoneal exudate and pleural effusion. These are the delay prior to CF and the singular monocyte‐macrophage differentiation. These similarities suggested that T‐CFC and LN‐CFC are probably of similar origin and represent, as suggested by Lin and Stewart ('74), a population of progenitor cells exclusively for mon

ISSN:0021-9541    

DOI:10.1002/jcp.1040920208

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

年代:1977

数据来源: WILEY

摘要:

AbstractWe have investigated factors controlling the rate of adhesion of suspension culture CHO cells to serum coated glass surfaces. Thus, we have examined (1) the effect of metabolic depletion via KCN treatment; (2) effects of colchicine and cytochalasin‐B, two drugs which are presumptive inhibitors of microtubule and microfilament activities, respectively; (3) effects of temperature on adhesion; (4) the correlation between changes in cell adhesion rate and alterations of lacteroperoxidase labelled cell surface proteins consequent to treatment with proteases.We have found that colchicine is completely without effect on the initial adhesion process in CHO cells, indicating that microtubules are not a determinant of adhesion kinetics. Cytochalasin‐B and depletion of ATP stores by KCN both diminish CHO cell adhesion, but seem to act in different ways. Treatment with cytochalasin‐B results in a dose dependent reduction in the initial slope of adhesion versus time curves, while KCN treatment produces a pronounced lag period during which little cell attachment takes place, followed by a relatively rapid rise to control levels of cell attachment.Analysis of CHO cell adhesion kinetics as a function of temperature reveals that the inhibition produced by low temperature seems similar to that produced by KCN. Thus at elevated (25°C) temperature, CHO cells adhere rapidly, while at 4°C adhesion is completely inhibited. However, at intermediate temperatures (10°C) a pronounced lag period followed by a rapid rise is noted, a result similar to that seen in KCN treated cells.Treatment of CHO cells with low doses (10 μg/ml) of crystalline trypsin results in the loss of several major cell surface proteins, without any appreciable effect on adhesion kinetics. High doses (100–1,000 μg/ml) of trypsin result in the cleavage of other proteins whose loss may be related to a parallel loss in adhesive ability. Some of the CHO cell surface proteins seem resistant to doses of trypsin (1,000 μg/ml) which completely abolish the ability of cells to adhere.Our observations on the effects of inhibitors, temperature, and surface proteolysis on CHO cell adhesion kinetics suggest the involvement of (a) microfilaments, (b) plasma membrane fluidity, and (c) a subclass of the surface proteins as important determinants of the adh

ISSN:0021-9541    

DOI:10.1002/jcp.1040920209

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

年代:1977

数据来源: WILEY

摘要:

AbstractAlkaline phosphatase is induced in cultured human choriocarcinoma cells by three inhibitors of DNA synthesis which alter DNA structure: 1‐β‐D‐arabinofuranosyl‐cytosine, mitomycin C, and phleomycin. No induction is observed with the inhibitors, hydroxyurea and thymidine, which do not alter DNA structure. Cyclic AMP, analogs of cyclic nucleotides, and sodium butyrate also induce alkaline phosphatase in these cells. Among the cyclic nucleotides tested, dibutyryl cyclic AMP is the best inducer, whereas dibutyryl cyclic GMP is a poor inducer.Induction of alkaline phosphatase by inhibitors of DNA synthesis or by exposure to dibutyryl cyclic AMP appears to utilize different mechanisms. Maximum induction is observed after simultaneous addition of both types of inducers at the concentrations found to be optimal for each inducer alone. Under these conditions, the induced activity is equal to or greater than the sum of the activities induced by each inducer. RNA synthesis and protein synthesis are required for induction.Dibutyryl cyclic AMP added to cultures of choriocarcinoma cells is not degraded in the culture medium, but is extensively degraded in the cells. Nevertheless, significant amounts of dibutyryl and monobutyryl cyclic AMP are found intracellularly throughout the experiment. Since the cellular uptake of dibutyryl cyclic AMP is extremely slow, the amount of butyrate released by intracellular degradation cannot account for the observed induction. Neither the rate of uptake nor the stability of dibutyryl cyclic AMP are changed by the addition of 1‐β‐D‐arabinofuranosyl‐cytosine to the culture medium. Furthermore, 1‐β‐D‐arabinofuranosyl‐cytosine inhibits the induction by sodium butyrate. The results indicate that butyrate is not the major mediator of inducti

ISSN:0021-9541    

DOI:10.1002/jcp.1040920210

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

年代:1977

数据来源: WILEY

摘要:

AbstractThrombin may stimulate the proliferation of resting fibroblasts by itself or by potentiating the mitogenic effects of other growth stimulating agents. When added alone to a dense quiescent culture of chick embryo fibroblasts in either a serum‐free or a low serum medium, thrombin stimulates these cells to proliferation at a rate comparable to that seen with 5% serum. In the case of rabbit corneal fibroblasts neither fibroblast growth factor nor thrombin is particularly effective as a growth stimulant when added alone but exhibited a pronounced synergism on cell proliferation when present together. Established cell lines in the resting state, including 3T3, SV‐3T3, 3T6, BHK‐21 and 3T3 injected with avian sarcoma virus strain B77 (B77‐3T3), are not responsive to thrombin alone. When the serum concentration in the medium equals or exceeds 2%, thrombin potentiates the mitogenic response of 3T3 cells to serum factors. With the exception of 3T3 and SV3T3 cells, the other cell lines show a potentiation of growth when thrombin is added to a low‐serum (0.5%) medium containing epidermal growth factor and prostaglandin F2α. The addition of thrombin to cultures of B77‐3T3 cells growing in the presence of epidermal growth factor and prostaglandin F2αdoes not increase the initial growth rate of these cells but increases significantly the final cell density of t

ISSN:0021-9541    

DOI:10.1002/jcp.1040920211

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

年代:1977

数据来源: WILEY