摘要:

AbstractThe effect of cAMP on a monkey kidney cell line (CV‐1) noninfected and infected by SV40 was studied. No effect was found on either growth rate or cell morphology when concentrations up to 1 mMof 3′5′ cAMP were used. However, cAMP was found to increase the incorporation of3H‐thymidine into both cellular and viral DNA without a net increase in DNA synthesis. This increased incorporation was found to be related to an enhanced uptake of thymidine into the nucleotide pool which is reflected in an increase of phosphorylated nucleotides. This, coupled with a lack of effect of cAMP on endogenous deoxyribonucleotide production, produces an increased specific activity of the deoxyribonucleotide triphosphates, with a resultant increase in specific activity

ISSN:0021-9541    

DOI:10.1002/jcp.1040830202

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

年代:1974

数据来源: WILEY

摘要:

AbstractSera from different strains of mice injected with endotoxin induced clones (D+) from a cultured line of myeloid leukemic cells to undergo normal differentiation to mature granulocytes and macrophages. Other clones (D−) derived from the same cell line were not inducible by these sera to undergo normal cell differentiation. Sera from the same strains of mice that had not been injected with endotoxin, increased the cloning efficiency of D+and D−clones but did not induce differentiation. Endotoxin serum induced differentiation in D+cells at dilutions up to 1:64, but increased the cloning efficiency of these cells at dilutions up to 1:2048. The end point of the dilution of endotoxin serum that induced differentiation in D+cells, was also the end point that induced the formation of colonies with differentiation from normal bone marrow cells. The results indicate that serum from endotoxin treated animals can serve as a good in vivo source to induce normal differentiation in D+myeloid leukemic cells; that the progeny of a single leukemic cell was induced to undergo differentiation to both macrophages and granulocytes; that endotoxin serum contained two activities, one that increased cloning efficiency and the other that induced cell differentiation; and that the same material in endotoxin serum induced cell differentiation in normal and leukemic ce

ISSN:0021-9541    

DOI:10.1002/jcp.1040830203

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

年代:1974

数据来源: WILEY

摘要:

AbstractLeukemic myeloblasts induced by avian myeloblastosis virus in the chicken formed small compact (type II) colonies in semi‐solid agar medium. Normal yolk sac cells from 12‐day old embryos formed large diffuse (type I) colonies under the same conditions. Type I colony formation (but not type II) was strictly dependent upon the presence in the medium of a colony stimulating factor (CSF) present in fresh chicken serum or conditioned medium. Serum CSF levels were determined for normal, leukemic, and birds which had spontaneously regressed from myeloblastic leukemia. When type I colony formation was used as the assay, serum CSF levels of leukemic birds were found to be significantly lower than levels in either normal or regressed birds. When the same sera were tested for their ability to induce type II colonies, leukemic birds demonstrated a significantly higher CSF level than either normal or regressed sera. Regressed chickens had serum CSF levels similar to normal bi

ISSN:0021-9541    

DOI:10.1002/jcp.1040830204

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

年代:1974

数据来源: WILEY

摘要:

AbstractBalb/3T3 cells transformed in culture by chemical carcinogens were shown to multiply in a medium supplemented with 2% calf serum or with 10% agamma new‐born calf serum. The cell lines that multiply well in medium supplemented with 10% agamma serum produced a higher incidence of tumors in X‐irradiated weanling mice than the lines that multiply poorly. The difference in 2‐deoxy‐D‐glucose uptake into exponentially growing transformed and un‐transformed cells was 50–100%. In crowded cultures untransformed Balb/3T3 cells ceased taking up the sugar, while chemically transformed cells continued at the same rate even at high cell densities; thus, the difference became greater in crowded cultures. When the serum concentration in the media was reduced from 10% to 2%, untransformed Balb/3T3 cells took up the sugar at a reduced rate, while chemically transformed cells were only slightly affected; agamma new born calf serum supplemented medium had no effect on sugar uptake in any of the cells. When the serum concentration was changed from 2% to 10%, untransformed cells increased sugar uptake followed by cell division. The immediacy (within 15 min) of the response in the sugar uptake to 10% serum concentration suggested that the increased uptake rate and the consequent higher concentration of the sugar (D‐glucose in normal situation) within Balb/3T3 cells triggered the cell cycle. Chemical carcinogens appear to alter permanently the uptake mechanism for

ISSN:0021-9541    

DOI:10.1002/jcp.1040830205

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe effect of cell density on morphological transformation of chick embryo cells by Rous Sarcoma Virus (RSV) was examined in this study, and a cell density optimum for transformation was found. Less than 10% of the transformed foci appearing at the optimum density (2.5 × 104cells per cm2) developed at high cell densities, and the diameters of the foci (an indication of the number of cells per focus) decreased with increasing cell density. No correlation was found between the decrease in transformation at high cell densities and the effect of cell density on the initial rate of cell proliferation, although dissociation of transformation from incorporation of radioactive precursors into nucleic acids could not be established. Redistribution of cells infected at high density showed that only a small proportion of successfully infected cells developed into foci. The results indicate that transformation of cells containing the RSV genome can be suppressed by physiological factors accompanying high cell density

ISSN:0021-9541    

DOI:10.1002/jcp.1040830206

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

年代:1974

数据来源: WILEY

摘要:

AbstractViral infection by vesicular stomatitis virus (VSV) as well as cellular protection against it were studied in cultured human diploid fibroblast cells (WI38 strain) of varying senescence (passage) level. Full protection against viral infection can be achieved by pretreatment of cells with an interferon inducer (complex of polycytidylate and polyinosinate) or by pretreatment with concentrates of interferon itself. The late passages (over 45) require higher concentration of both agents than the medium passages (25–45); a complete failure of protective mechanisms occurs only close to cellular death. Furthermore, effects of confluency and of duration of induction impulse were studied. WI38 cells are sensitive to VSV infection through their entire life span; however, during the last passage before their death by senescence, VSV replication is significantly decreased. It is concluded that even in relatively senescent cells (a) protection mechanisms which were not used previously can be activated, (b) synthesizing machinery necessary for efficient support of viral replication is sustained, and (c) release of lysosomal enzymes ending the viral replication does not begin sooner than with cells of earlier passage leve

ISSN:0021-9541    

DOI:10.1002/jcp.1040830207

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

年代:1974

数据来源: WILEY

摘要:

AbstractA series of Chinese hamster cell lines were tested and found to be able to proliferate in the absence of added bicarbonate and carbondioxide if hypoxanthine and uridine were present in the medium. Conversely, cells incapable of salvaging one of these precursors, such as hypoxanthine‐guanine phosphoribosyltransferase (HGPRT−) deficient cells did not multiply under these conditions.We describe another variant capable of utilizing hypoxanthine and uridine which has an absolute requirement for exogenous CO2/NaHCO3for growth. These cells appear to be defective in the complete oxidation of pyruvate to carbondioxide, and indications are that the entry of pyruvate into the Krebs cycle is affec

ISSN:0021-9541    

DOI:10.1002/jcp.1040830208

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

年代:1974

数据来源: WILEY

摘要:

AbstractConditions have been established for the separation of viable mouse lymphoid cells by continuous free‐buffer film preparative electrophoresis. The detailed electrophoretic distribution profiles of T and B lymphocytes from mouse spleen and thoracic duct have been determined. Cell surface θ‐antigen was used as a marker for T cells, and high surface‐density of immunoglobulin as a marker for B cells. Spleen cells from athymic “nude” mice were also studied.In the unselected normal spleen cell populations B lymphocytes are heterogeneous, about 60% being of low mobility with the remainder distributing broadly, and extending into the highest mobility fractions. T lymphocytes are predominantly of high mobility. Lymphoid cells lacking markers of either the B or T lineage are of intermediate mobility. There is only partial separation of T and B cells because of the extensive overlap between the populations.The high mobility B cells, which separate along with T cells, include a substantial proportion of large cells, and include cells with high surface density of immunoglobulin. The majority of these large B cells can be selectively eliminated by their adherence on passage through a glass‐bead column.By pre‐selecting the 50% non‐adherent lymphocytes from spleen as the starting material, a very sharp and more extensive separation of B and T cells can be achieved, with 100% pure B cells and 90% pure T cells in many fractions. However these samples are not representative of the total T and B cell populations of spleen.In thoracic duct lymph high mobility B‐cells are absent, there is little overlap between T and B cell mobility. 100% pure T and B cel

ISSN:0021-9541    

DOI:10.1002/jcp.1040830209

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

年代:1974

数据来源: WILEY

摘要:

AbstractNet fluxes of sodium and potassium were studied in Ehrlich mouse ascites tumor cells during contact with the agglutinating protein, concanavalin A. This lectin altered cation transport markedly at concentrations of 20–105 μg/ml (6–47 μg/mg cell protein). Whereas control cells extruded sodium and maintained or accumulated potassium against electrochemical gradients, in the presence of concanavalin A there was rapid net sodium entry and potassium loss. After 10–20 minutes in concanavalin A, sodium extrusion began and potassium loss diminished but these events were prevented by ouabain. The alterations in cation content induced by concanavalin A are unlikely to be the result only of agglutination since soybean agglutinin caused much smaller changes although it agglutinated the cells equal

ISSN:0021-9541    

DOI:10.1002/jcp.1040830210

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe activities of the constant proportion enzymes of the Embden‐Meyerhof chain (triose phosphate isomerase (TIM), glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH), phosphoglycerate kinase (PGK), phosphoglycerate mutase (PGM) and enolase (ENOL)), and the activity of lactic dehydrogenase (LDH) were studied in developing red (trapezius) and white (longissimus) muscles of the pig from a fetal stage to 24 weeks postnatal. Both muscles were differentiated by two weeks postnatal in the sense that they had reached the adult level of enzyme activity. Enzyme activities were two‐ to three‐fold greater in thelongissimusthan in thetrapezius. Enzyme activity ratios based on GAPDH were not consistent in the fetal and day 1 samples but were consistent during later stages of growth. Ratios of enzyme activity based on activity at 105 days gestation revealed that TIM, PGK and PGM are grouped and follow the same pattern, but GAPDH and ENOL are quite different from each other and from the pattern shown by TIM, PGK and PGM. The constant proportion concept in developing muscle is therefore q

ISSN:0021-9541    

DOI:10.1002/jcp.1040830211

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

年代:1974

数据来源: WILEY