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  • 1995-1999
  • 1975-1979  (630)
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  • 1977  (630)
  • Life and Medical Sciences  (630)
  • 101
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 92 (1977) 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 102
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 92 (1977), S. 169-175 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Albumin 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 phagocytosis.
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  • 103
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The 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 = 1.3.108 min-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 biological membranes.
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  • 104
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 92 (1977), S. 249-255 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have compared membrane transport of lysine and adenosine by rabbit lung macrophages in suspension and adherent to glass cover slips. The rapid sampling techniques employed permitted measurements to be made over intervals as short as 10 seconds. Suspended cells transported both nutrients at a faster rate, although the Km values for the two transport systems remained unchanged. Colchicine, cytochalasin B and adenosine did not interfere with the enhancement.
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  • 105
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Transformation of mouse 3T3 cells by SV40 results in a specific membrane modification which renders cells resistant to the killing action of the lipophilic antibiotic Amphotericin B. This alteration is under genetic cellular control and is specific for SV40 transformation since transformation with polyoma or mouse sarcoma viruses does not confer resistance to the antibiotic. Analogous resistance is induced by SV40 transformation of primary human fibroblast cells. The acquired resistance is not due to decreased binding of Amphotericin B and is partially reversed if cells are grown in the presence of cholesterol. The results are interpreted as a specific change of sterol structure of the membrane or the loss of a minor cholesterol fraction responsible for the killing action of the antibiotic.
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  • 106
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 92 (1977), S. 293-301 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Protein synthesis and degradation were studied throughout a growth cycle of Vero cells. The rate of protein synthesis, measured as the rate of amino acid incorporation, reached a maximum at the mid-exponential phase and declined to 10-30% of the maximum in the stationary phase. The rate of protein degradation, measured as the release of radioactive amino acids from uniformly labelled cellular proteins, did not vary in the growth cycle. The amount of protein per cell, measured by an isotopic method, remained constant when normalized to account for the variation in the proportion of actively dividing cells in the cell population during the growth cycle. Cellular protein was determined using this method since it was found that the chemical determination of the amount of protein in the monolayer was not accurate during the early stage of the growth cycle. This was due to a significant amount of serum protein adsorbed to the cells. In this study we were able to show that, in Vero cells, protein synthetic activity is correlated with the rate of cell division, and variations in the rate of synthesis alone are sufficient to meet the changing requirements for cellular protein in a growth cycle.
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  • 107
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 92 (1977), S. 309-318 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Rat thymocytes can be separated into two subpopulations by centrifugation for 20 minutes at 1,600 g in an 18/26/36% (w/v) discontinuous gradient of bovine serum albumin. Approximately 13% of the cells band at the 18/26% interface (light cells) while the remaining cells band at the 26/36% interface (heavy cells). In vitro and in vivo studies of 3H-thymidine incorporation indicate that the light cells are 2- to 3-fold enriched in the rapidly dividing lymphoblast subpopulation of thymocytes as compared to heavy cells. Light cells transport the non-metabolizable glucose analogue 3-O-methylglucose (3-MeGlc) approximately four times faster than heavy cells. The time course of 3-MeGlc uptake is biphasic for light, heavy and unfractionated thymocytes. While the half-times of the rapid (1 minute) and slow (20-45 minute) phases of uptake are similar for all three types of cells, the contributions of the rapid phase to total uptake are 50% for light cells, 20% for unfractionated thymocytes and 10% for heavy cells. The results show that 3-MeGlc transport activity differs markedly within certain thymocyte subpopulations. The correlation between the contributions of the rapid phase of uptake and the proportion of lymphoblasts in the thymocyte fractions suggests that the lymphoblast and small lymphocyte subpopulations might be responsible for the rapid and slow phase of 3-MeGlc uptake, respectively.
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  • 108
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 92 (1977), S. 319-332 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The role of glucose uptake in control of cell growth was studied by experimentally varying the rate of glucose uptake and examining the subsequent effect on initiation and cessation of cell proliferation. The rate of glucose uptake was varied by adjusting the concentration of glucose in the culture medium. This permitted analysis of two changes in rate of glucose uptake which are closely related to the regulation of cell growth: (1) the rapid increase in glucose uptake that can be detected within several minutes after mitogenic stimulation of quiescent fibroblasts and (2) the decrease in glucose uptake which accompanies growth to a quiescent state.Quiescent cultures of mouse 3T3, human diploid foreskin and secondary chick embryo cells were switched to fresh serum-containing medium with either the normal amount of glucose or a reduced level that lowered the rate of glucose uptake below the rate characteristic of quiescent control cells. The subsequent increases in cell number were equal in both media, demonstrating that the increase in glucose uptake, commonly observed after mitogenic stimulation, was not necessary for initiation of cell division. Measurements of intracellular D-glucose pools after serum stimulation of quiescent cells revealed that the increase in glucose uptake was not accompanied by a detectable change in the intracellular concentration of glucose.Nonconfluent growing cultures of mouse 3T3, human diploid foreskin and secondary chick embryo cells were switched to low glucose media, lowering the rate of glucose uptake below levels observed for quiescent cells. This did not affect rates of DNA synthesis or cell division over a several-day period. Thus, the decrease in glucose uptake, which usually occurs at about the same time as the decrease in DNA synthesis as cells grow to quiescence, does not cause the decline in cell proliferation. Experiments indicated that there was no set temporal relationship between the decline in glucose uptake and DNA synthesis as cells grew to quiescence. The sequence was variable and probably depended on the cell type as well as culture conditions. Measurements of intracellular D-glucose pools in secondary chick embryo cells demonstrated that the internal concentration of glucose in these cells did not significantly vary during growth to quiescence. Taken together, our results show that these fluctuations in the rate of glucose uptake do not lead to detectable changes in the intracellular concentration of glucose and that they do not control cell proliferation rates under usual culture conditions.
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  • 109
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 92 (1977), S. 425-435 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Three different temperature sensitive mutants derived from the Syrian hamster cell line BHK 21 were found to have greatly reduced DNA synthesis at the non-permissive temperature. These mutants are distinct by complementation analysis and behave at the non-permissive temperature as cell cycle traverse defective mutants. Microfluorometric analysis of mutant populations arrested at the non-permissive temperature shows an accumulation of cells with G1 DNA content. Mutants ts 13 and ts HJ4 synchronized in G1 by serum or isoleucine deprivation and shifted to the non-permissive temperature at the time of release do not enter the S phase, while in the case of mutant ts 11 preincubation at the non-permissive temperature before release is required to completely prevent its entry into S. Ts 13 and ts 11 are able to traverse the S phase at the non-permissive temperature when synchronized at the boundary G1/S; in this case, preincubation of ts 11 at the non-permissive temperature before release does not affect the ability of these cells to perform DNA synthesis. On the other hand, ts HJ4 appears to traverse S only partially when tested under similar conditions. Temperature shift experiments of mutant populations at different times after isoleucine synchronization suggest that ts 13 and ts 11 are blocked at the non-permissive temperature in early G1, whereas ts HJ4 is probably affected near the initiation of DNA synthesis, or in some early S function.
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  • 110
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 92 (1977), S. 487-487 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 111
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 93 (1977) 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 112
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Multipotential stem cells of a murine teratocarcinoma are resistant to typical infection with either polyoma virus (PV) or Simian virus 40 (SV40). Differentiated progeny of the stem cells are susceptible to infection in a manner identical to other mouse somatic cells, i.e., they are permissive for PV and nonpermissive for SV40. The early interactions between the stem cells (embryonal carcinoma or EC cells) and SV40 and PV were studied. Virions adsorbed to and penetrated into the cytoplasm and nucleus of EC cells, but did not induce expression of T antigen in the EC nuclei. Purified SV40 DNA was capable of inducing T antigen in differentiated teratocarcinoma cells but not in EC cells. Virus could not be rescued from EC cells previously exposed to SV40. The resistance of the stem cells to infection apparently involves a block in the infectious cycle after adsorption and penetration but before T antigen induction.
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  • 113
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 93 (1977), S. 205-212 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A chromosome that controls malignancy in Chinese hamster cells has been identified by analysis of the Giemsa banding pattern of a malignant cell line transformed by simian virus 40 (SV40), non-malignant revertants from this line, segregants from the revertants that were again malignant and a cell line transformed by methylcholanthrene. The malignant cell line transformed by SV40 was near diploid and had gained additional material of chromosome 3. Revertants with a suppression of malignancy and malignant segregants from these revertants were near triploid. The malignant segregants also showed a gain of material of chromosome 3 compared to the non-malignant revertants from which they were derived. Malignancy of these cells was associated with the ability to form colonies in agar. Cells of a line transformed by methylcholanthrene were malignant, formed almost no colonies in agar and the only chromosome change from the normal diploid chromosome banding complement was the addition of a long arm of chromosome 3. The results indicate that chromosome 3 carries gene(s) that control malignancy in Chinese hamster cells in cell lines transformed by a viral or a chemical carcinogen and that malignancy was induced in both cell types by an increase of these genes.
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  • 114
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Several clones of dexamethasone-resistant cells, which could not differentiate even in a high concentration of dexamethasone, were isolated from glucocorticoid-sensitive myeloid leukemic cells. Some of them were shown to be deficient in steroid binding to specific cytoplasmic receptors, while the others contained glucocorticoid-specific cytoplasmic receptors that might be the same as those in sensitive cells. One of the resistant clones was found to be almost completely deficient in nuclear acceptor sites for cytoplasmic steroid-receptor complexes. The remaining clones were also characterized by significantly reduced amounts of nuclear-bound glucocorticoid. These results suggest that resistibility to glucocorticoids in the resistant clones of myeloid leukemic cells is due mainly to a defect in some steps of intracellular transfer of the steroid. Dexamethasone-sensitive cells, which could differentiate in the presence of dexamethasone, could be also induced to differentiate by protein factor(s) in ascitic fluid. Although all the resistant cells showed a low response to ascitic fluid, some of them showed 10-fold enhancement of phagocytic activity which is a typical character of differentiated cells. These results suggest that response to steroids is not directly correlated with that to protein inducer(s).
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  • 115
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 93 (1977), S. 363-374 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have found cyclic AMP in the large, heterotrichous ciliate Stentor coeruleus in amounts per milligram protein similar to those found in another ciliate, Tetrahymena pyriformis. The possible function of cyclic AMP in Stentor was first examined by determining its effects on oral regeneration, the process by which Stentor can replace a missing oral apparatus in eight to ten hours. Once begun (by brief exposure to a 15% sucrose solution, causing shedding of the oral apparatus) regeneration follows eight specific morphological stages visible with the dissecting microscope. Continuous exposure of regenerating cells to either N6, 2′-0-dibutyryl adenosine cyclic 3′:5′-monophosphate (DBC) or theophylline begun at the onset of oral regeneration (stage 0) caused delays in the completion of regeneration. The delays induced by DBC occurred in the early stages prior to stage 5. Regenerating cells exposed to DBC or theophylline at various stages of development were delayed, even at stages 5 and 6. Both DBC and theophylline reversibly bleached the cortical pigment of the cells. Guanosine 3′:5′-cyclic monophosphate (cyclic GMP), AMP, GMP, and sodium butyrate neither delayed oral regeneration nor bleached the cortical pigment. Excess extracellular calcium ions alone had no effect on oral regeneration, but 10 mM calcium and DBC caused more delay than DBC alone. Thus, the delay of oral regeneration in Stentor caused by cyclic AMP may involve calcium ions.To determine if cyclic AMP can retard in situ ciliary regeneration by Stentor, as it does in Tetrahymena, a new technique, more accurate than past methods, was developed to monitor ciliary regrowth. Using this procedure we found that both DBC and theophylline significantly delayed the in situ ciliary regeneration by Stentor.
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  • 116
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 90 (1977), S. 9-14 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The way in which the lectins concanavalin A (Con A) and Ricinus communis agglutinin (Ricin) alter the K+ content of Ehrlich ascites tumor cells was investigated. Unidirectional and net fluxes were determined in unwashed cells during a time course following lectin addition. Total influx, ouabain sensitive influx, Mg++- and Na+-K+-ATPase activity were all unaffected. Cell ATP content was normal for at least 19 minutes after exposure to Con A. Early after contact with Ricin or Con A efflux was stimulated 2-3-fold, resulting in net K+ loss, but after 20 minutes efflux had returned to normal. Ricin and Con A acted similarly although Ricin was present at only 1/50 the concentration of Con A. When the findings are evaluated together with previous work it is suggested that a particular membrane glycoprotein may be concerned in the efflux alteration observed.
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  • 117
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 90 (1977), S. 41-52 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Low passage BHK 21/13 cells contain two cell surface enzymes, a nucleotide pyrophosphatase and a monophosphoester hydrolase, which together hydrolyze exogenous UDP-galactose to free galactose. During serial passage, BHK cells successively lose both enzymes. Concomitant with the loss of these enzymatic activities, changes in cell morphology, as well as in the serum requirement for the initiation of DNA synthesis, were observed. Clonal sublines of BHK cells were isolated, which differed qualitatively in their ability to hydrolyze UDP-galactose. Clonal BHK sublines, which exhibited both enzymatic activities on their cell surface, resembled low passage BHK cells in morphology and serum requirement for the initiation of DNA synthesis. Sublines not containing these enzymes resembled BHK cells of high passage cultures. The ability of intact BHK cells to hydrolyze exogenous nucleotide sugars may serve as an indicator for the progression of BHK cells from a normal to a more transformed state.
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  • 118
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 90 (1977), S. 127-137 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The application of roller-bottle cell culture techniques and a relatively simple purification scheme has led to the isolation of milligram quantities of a polypeptide cell multiplication stimulating activity (MSA) from Buffalo rat liver cell conditioned medium. We have characterized the apparently homogeneous MSA with respect to its biological activity, its N-terminal amino acid residue, and its amino acid composition, and have tested the MSA for growth-promoting activity in a number of cell types.
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  • 119
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 90 (1977), S. 161-167 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The thermodynamic parameters ΔH°, ΔF°, ΔS° and the pH dependence of the interaction between steroids and the glucose carrier in human erythrocytes have been studied. The results indicate that, according to the structure of the steroids, hydrophilic as well as hydrophobic bonds can be involved in the association. For the binding of the C-21-steroids to the carrier the polarity rule has been observed to be valid. On the basis of the thermodynamic parameters it has been found that in the association process of the steroids with the carrier, simultaneous randomization of ordered water molecules is important.
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  • 120
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 90 (1977), S. 179-191 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Somatic cell hybrids of mouse L-cells with rat HTC cells were studied for their growth properties in vitro and tumorigenicity in vivo. Three hybrid clones were selected for detailed study. All were delayed in tumor formation in nude mice compared with the parent lines despite their varied growth properties in vitro.One clone was sensitive to density dependent inhibition of growth (DDIG) and had a relatively low saturation density. A second clone was not sensitive to DDIG and had a higher saturation density. The third clone had atypical morphology, was insensitive to DDIG, and had a relatively high saturation density. All of the clones studied produced colonies suspended in agarose gel which were much smaller than those of the parents incubated for the same period of time. Only the pattern of growth in agarose gel corresponded to the delayed tumor formation in vivo of the hybrids. Sensitivity to DDIG and saturation density were not consistent with tumor growth.The hybrid clone that was sensitive to DDIG was the only one of the three that had a nearly complete set of chromosomes derived from each of the parents. The chromosome numbers of all three clones were unchanged after growth in agarose or as tumors in the nude mice.
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  • 121
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In resting, non-growing human diploid fibroblasts the amount of rRNA is reduced 1.8-fold, cytoplasmic polysomes are disaggregated, and the level of poly-A RNA (mRNA) is reduced 1.8-fold in relation to growing cells. The distribution of poly-A RNA is altered in resting, non-growing cells so that an average of 64% of the total cytoplasmic poly-A RNA sediments along with particles lighter than 80S (prepolysomal) in sucrose density gradients. By comparison, in growing cells only 30% of the cytoplasmic poly-A RNA sediments in the prepolysomal region. In SDS sucrose gradients, the sedimentation profile of the prepolysomal poly-A RNA from resting cells resembles that of polysomal poly-A RNA from those cells. In contrast, the average size of prepolysomal poly-A RNA from growing cells is much smaller than that of the polysomal poly-A RNA from those cells. These data are compatible with the possibility that resting cell prepolysomal poly-A is untranslated mRNA. Also consistent with this interpretation are experiments which demonstrate that one-quarter to one-third of the prepolysomal poly-A RNA of resting cells is recruited into polysomes in the presence of cycloheximide.
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  • 122
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 90 (1977) 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 123
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A variant subline of Chinese hamster cells (line CHO) was isolated that had increased resistance to detachment from the substratum. Comparisons between parental and variant cells of the complex carbohydrates liberated during trypsin detachment showed that the variant cells synthesized little or no hyaluronic acid. These cells also had reduced amounts of other complex carbohydrates in the cell periphery. However, parental and variant cells did not differ in morphology, growth control, or cyclic AMP concentration. Profound changes in the physical and chemical nature of the cell periphery, in themselves, evidently are insufficient to cause changes in many aspects of cell behavior.
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  • 124
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 90 (1977), S. 415-422 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Age-related changes in the cytokinetics of human diploid cells in vitro have been compared in normal cultures and in cultures in which lifespan has been prolonged by the addition of hydrocortisone to the medium. For both cultures, with advancing age the fraction of cells in the actively proliferating pool decreased and the intercellular variation in cell cycle times increased. The average cell cycle time was prolonged during aging due almost entirely to changes in the duration of G1. The duration of S remained constant, while a small delay in G2 was observed in late passage cells near the end of their lifespan. Although the same pattern of change in proliferative parameters occurred in both control and hydrocortisone-treated cultures, the changes were somewhat delayed in the presence of the steroid. The results are interpreted in terms of several cell cycle models and suggest that the events controlling cell proliferation are sensitive to hydrocortisone modulation during the G1 and possibly the G2 periods.
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  • 125
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effect of granulocyte-macrophage colony stimulating factor (GM-CSF) on the synthesis of RNA in liquid cultures of mouse bone marrow, spleen, thymus, peritoneal, peripheral blood leukocytes and lymph node cells was investigated. GM-CSF appeared to stimulate RNA-synthesis in syngeneic bone marrow cells within ten minutes of adding it to the culture. In the presence of GM-CSF bone marrow cultures maintained their initial rate of RNA synthesis for approximately ten hours. GM-CSF had no apparent effect on the uptake of 3H-uridine into bone marrow cells. This stimulation was still observed in the presence of puromycin and cycloheximide, but was abrogated by actinomycin D. The magnitude of the stimulation was not affected by the density of cells between 1 and 20 × 106 cells/ml but was slightly smaller at 0.1 and 40 × 106 cells/ml. Increasing concentration of GM-CSF (up to 2 × 105 units per ml) led to increased stimulation of RNA synthesis in bone marrow cells, but a significant stimulation could be detected at concentrations as low as 800 units/ml.GM-CSF did not significantly stimulate RNA synthesis in spleen, thymus, mesenteric or subcutaneous lymph node cells. However a small stimulation was observed in peripheral blood leukocytes and peritoneal cells.Autoradiographic studies showed that GM-CSF stimulated RNA synthesis in blast cells, myelocytes, metamyelocytes and polymorphs. Nucleated erythroid cells showed no increased labeling with GM-CSF. Labeling in lymphoid-like cells was highly variable but the level of labeling did not appear to be influenced by GM-CSF.
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  • 126
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Further evidence of mRNA in HeLa cells with a half-life two hours or less is given. A kinetic model of RNA synthesis in HeLa cells is described in which equilibration of label occurs first into the acid soluble pool (evidence is given that this pool feeds RNA synthesis) and thence in nuclear and cytoplasmic molecules. The measured accumulation of label in nuclear and cytoplasmic poly(A) is examined with the model and parameters were found which are consistent with the quantitative transfer of nuclear poly(A) to the cytoplasm. The strengths and limitations of the model are discussed.
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  • 127
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    Journal of Cellular Physiology 91 (1977) 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 128
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    Journal of Cellular Physiology 90 (1977), S. 553-563 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The kinetics of Cl--SO4-2 exchange in Ehrlich ascites tumor cells was investigated in an attempt to determine the stoichiometry of this process.When tumor cells, equilibrated in Cl--free, 25 mM SO4-2 medium are placed in SO4-2-free, 25 mM Cl- medium, both the net amount and rate of Cl- uptake far exceeds SO4-2 loss. Addition of the anion transport inhibitor SITS (4-acetamido-4′-isothiocyano-stilbene-2,2′-disulfonic acid) greatly reduces sulfate efflux (97%), but has no measurable effect on chloride uptake. Addition of furosemide, a Cl- transport inhibitor, reduces chloride uptake 94% but is without effect on sulfate efflux. These findings suggest that a chloride permeability pathway exists distinct from that utilized by SO4-2.SITS, when added to furosemide treated cells, further reduces chloride uptake as well as inhibiting sulfate efflux, and under these experimental conditions, a linear relationship exists between SITS-sensitive, net chloride uptake and sulfate loss. The slope of this line is 1.05 (correlation coefficient = 0.996) which suggests the stoichiometry of Cl--SO4-2 exchange is 1:1. Assuming a 1:1 stoichiometry, measurement of the initial chloride influx and initial sulfate efflux indicate that 92% of net chloride uptake is independent of sulfate efflux.Taken altogether, these results support the contention that the tumor cell possesses a permeability pathway which facilitates the exchange of one sulfate for one chloride. Under conditions where anion transport is not inhibited, this coupling is obscured by a second and quantitatively more important pathway for chloride uptake. This pathway is SITS-insensitive, although partially inhibited by furosemide.
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  • 129
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    Journal of Cellular Physiology 90 (1977), S. 511-519 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cell adhesion and spreading were studied on sulphonated polystyrene dishes in serum-free saline (Mn, Na, Cl, buffer) i.e., without an intervening protein layer. Spreading as a function of surface charge density, SCD, peaked around 2-10 negative charges per square nanometer, corresponding to a monomolecular layer of sulphonate ions. At optimal SCD, macrophages, BHK-C13 and whole mouse embryo secondary cells all showed considerable spreading, even in monovalent saline-more so than on a conventional tissue-culture surface. But outside this narrow range of SCD, or on protein-coated surfaces, the divalent cation was indispensable.The biphasic effect of sulphonation on cell adhesion is consistent with the theory that a substratum need not be biochemically specific, provided it is physicochemically polar, rigid and dense. According to this theory, polystyrene of sub-optimal SCD would not be sufficiently polar, while supra-optimal sulphonation would produce a hydrogel surface, lacking in local rigidity and density, due to osmotic swelling. The principle of polymer exclusion, by a surface hydrogel layer, is also consistent with observations on the inhibitory effects of adsorbed proteins-viz., albumin, collagen, serum and cellular exudate, respectively-contrasted with the ready attachment of cells to a bare, optimally charged substratum, in this minimal in vitro system.
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  • 130
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    Journal of Cellular Physiology 91 (1977), S. 79-88 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Whole 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+.
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  • 131
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    Journal of Cellular Physiology 91 (1977), S. 103-118 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The 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 dopamine receptors.
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  • 132
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    Journal of Cellular Physiology 91 (1977), S. 169-179 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Parenchymal cells were isolated from adult rat liver with an enzyme perfusion technique. The single-cell suspension, representing 40-50% of the liver's hepatocytes was suspended in medium and maintained in primary culture for up to four days. The cells were found to carry out glycogen synthesis for the first eight hours in culture after which time the accumulated glycogen was gradually degraded. The ability of the liver cell cultures to accumulate glycogen was found to be dependent upon the metabolic state of the animal prior to cell isolation. Cells prepared during the feeding period from animals on the 8 + 16 feeding schedule had markedly different capacities for glycogen accumulation. Changes in glycogen metabolism were found to be due, in part, to changes in the fraction of cells involved in metabolism at any given time. High concentrations of glucose stimulated the cells to deposit glycogen but the response was reduced the longer the cells were in culture over a 3-day period. This loss of glycogen synthesizing capacity appears to be due to a decrease in glycogen synthetase activity. The activities of pyruvate kinase, hexokinase and aldolase also decrease during the culture period.
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  • 133
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    Journal of Cellular Physiology 91 (1977), S. 193-199 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Experiments were performed to investigate the presence of colony-forming units (CFU) in the mouse embryonic yolk sac during the developmental period in which the yolk sac is the sole hemopoietic organ. Injection of yolk sac cell suspensions from normal embryos into syngeneic, lethally irradiated adult recipients evoked a very low number of spleen colonies. However, prior cultivation of yolk sacs in vitro caused a dramatic increase in the spleen colony-forming capacity-as high as 84-fold-following 48 hours in culture. The yolk sac origin of the spleen colonies was confirmed by: (a) Chromosomal marker analysis; (b) dose-response analysis; (c) demonstrating that the above colonies were not of endogenous origin induced by the mere injection of grafted cells. We conclude that the yolk sac contains many precursors of colony-forming cells which though undetectable by immediate grafting apparently become activated in culture by an as yet unknown induction process.
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  • 134
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    Journal of Cellular Physiology 91 (1977), S. 209-223 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A colchicine-resistant clone, CHRE5, has been isolated in a single step from a mutagenized culture of Chinese hamster ovary cells. Its resistance correlates with reduced colchicine permeability. At the same time, CHRE5 cells display a pattern of cross-resistance to unrelated drugs similar to other membrane-altered drug-resistant mutants previously described (Ling and Thompson, 1974). However, CHRE5 cells also express a cold-sensitivity for growth in that at 34° they do not double in number while at 38.5° they grow with a doubling time of about 22 hours. Employing synchronous cultures, the cold sensitive block in CHRE5 cells has been determined to be located prior to S in the G1 phase of the cell cycle. Mutant cells at 33.5° are not able to initiate DNA synthesis, however, cells already synthesizing DNA are able to complete the whole course of S. This cold sensitive block is reversed by shifting cells back to the higher temperature. Additonal clones with the CHRE5 phenotype have been isolated from non-mutagenized cultures of wild-type cells. Moreover, partial revertants of CHRE5 with increased ability to grow at 34° have been isolated and found to display increased colchicine sensitivity. These results are consistent with the hypothesis that the two phenotypes observed in CHRE5, namely, an altered plasma membrane (reduced drug permeability) and an altered ability to initiate DNA synthesis are the result of the same mutation.
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  • 135
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    Journal of Cellular Physiology 91 (1977), S. 239-248 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cytochalasin B (CB) was able to compete with tritiated cytochalasin D (3H-CD) for binding sites in HEp-2 cells. The pattern of inhibition suggested that CB associates with a low affinity class of CD binding sites. Glucose and maltose did not inhibit binding of 3H-CD to isolated HEp-2 plasma membrane. Inhibition of hexose transport by CD was negligible, but CD did not block the potent inhibition of this transport by CB. These results indicate that CD does not bind to the high affinity CB receptor reportedly associated with the hexose transport system, and that this receptor cannot mediate the morphological effects of CD. Both CD and CB induced contraction-zeoisis in HEp-2 cells; CB was less potent than CD, and their effects appeared to be additive. It was concluded that the high affinity binding sites for CD and CB are different, but that these congeners share a low affinity site. Both high and low affinity sites for CD appear to mediate its morphological effects; only the low affinity class appears to be involved for CB. Possible identification of the common low affinity binding site as actomyosin (detailed in Tannenbaum et al., 1977) is further discussed.
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  • 136
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    Journal of Cellular Physiology 91 (1977), S. 271-287 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Reuber (H35) hepatoma cells were grown in medium containing 10 -5M bromodeoxyuridine (BrdU), which was incorporated into their DNA. Cell growth rate was unaffected by BrdU for the first two generations, after which it was reduced by about 50%. The effect of BrdU incorporation on the activities of several enzymes with rapid turnover rates was examined to test the hypothesis that the synthesis of such enzymes will be preferentially inhibited by BrdU. Tyrosine amino-transferase (TAT) activity decreased by 70% within two generations whereas thymidine kinase activity remained at control values. PEP carboxykinase activity was unchanged during the first generation in BrdU-containing medium but, during the second, its activity increased by at least 30%. Ornithine decarboxylase levels decreased by about 50% only after two generations in the presence of BrdU. There appeared to be no simple relationship between turnover rates and the effect of BrdU on enzyme activity. Incorporation of BrdU was found to inhibit the induction of both TAT and PEP carboxykinase by dexamethasone and to enhance the inhibition of cell growth by this steroid. These results are discussed with respect to possible mechanisms of gene expression and development in both normal and neoplastic cells.
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  • 137
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Calf serum as well as rat and mouse sera has a factor that stimulates hyaluronic acid synthesis in cultured rat fibroblasts. Such a factor was partially purified from calf serum and characterized. It has a molecular weight of approximately 150,000. The activity of the factor is lost by treatment with pronase and by periodate oxidation. It is suggested, therefore, that the factor is a glycoprotein. Its susceptibility to α-mannosidase and affinity for Con A-Sepharose may suggest that the factor contains a mannose residue(s) which is essential for the activity to induce hyaluronic acid synthesis.
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  • 138
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Propranolol, in the presence of calcium, causes marked K efflux from human red blood cells (high K, low Na). The studies reported here indicate this effect of propranolol is specific for K and does not represent a nonspecific permeability increase for intracellular cations to leave the cell. Amphotericin-treated human RBC's (high Na, low K) and dog RBC's (high Na, low K) both gain K and increase in size when incubated in a K-medium containing propranolol and calcium. No effect was noted when cat RBC's (high Na, low K) were similarly treated. Propranolol, independent of added calcium, also inhibited the normally increased Na efflux observed when dog RBC's are suspended in K-medium. These species differences in response to propranolol thus may serve as a focus for elucidating the mechanism by which this drug alters normal membrane physiology. The unique drug effect on Na permeability of canine erythrocytes also may be a useful probe for the study of dog RBC volume regulation.
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  • 139
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    Journal of Cellular Physiology 91 (1977), S. 335-344 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A liquid culture system is described whereby proliferation of haemopoietic stem cells (CFU-S), production of granulocyte precursor cells (CFU-C), and extensive granulopoiesis can be maintained in vitro for several months. Such cultures consist of adherent and non-adherent populations of cells. The adherent population contains phagocytic mononuclear cells, “epithelial” cells, and “giant fat” cells. The latter appear to be particularly important for stem cell maintenance and furthermore there is a strong tendency for maturing granulocytes to selectively cluster in and around areas of “giant fat” cell aggregations. By “feeding” the cultures at weekly intervals, between 10 to 15 “population doublings” of functionally normal CFU-S regularly occurs. Increased “population doublings” may be obtained by feeding twice weekly. The cultures show initially extensive granulopoiesis followed, in a majority of cases, by an accumulation of blast cells. Eventually both blast cells and granulocytes decline and the cultures contain predominantly phagocytic mononuclear cells.Culturing at 33°C leads to the development of a more profuse growth of adherent cells and these cultures show better maintenance of stem cells and increased cell density.When tested for colony stimulating activity (CSA) the cultures were uniformly negative. Addition of exogenous CSA caused a rapid decline in stem cells, reduced granulopoiesis and an accumulation of phagocytic mononuclear cells.
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  • 140
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    Journal of Cellular Physiology 92 (1977), S. 23-31 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Depletion of Mg2+ in the growth medium for chicken embryo fibroblasts produces a large decrease in DNA synthesis as measured by 3H-thymidine incorporation, and concomitant decreases in cellular K+ and Mg2+ and increases in Na+ and Ca2+. In cells grown in media containing 0.2 mM Ca2+, graded reduction of Mg2+ from 0.8 mM (control) to 0.016 mM produced graded decreases in DNA synthesis to 10% of control at 0.016 mM Mg2+. Concomitantly, cell cations showed graded changes, Na+ increasing to 227%, K+ decreasing to 52.5%, Mg2+ decreasing to 57.5% and Ca2+ increasing to 153.5% of control. The effects of Mg2+ depletion on DNA synthesis and cell cation content exhibited a dependence on Ca2+ concentration, the effects being larger at low Ca2+ concentration. Use of inorganic pyrophosphate in the growth medium as a selective complexor of Mg2+ caused a marked decrease in DNA synthesis which was accompanied by changes in cellular cation content similar to those produced by direct Mg2+ depletion.The effects of Mg2+ depletion on cell cation content are explainable in terms of changes in membrane permeability caused by rapid external surface exchange of bound divalent cations. Among the several interpretations of the data in terms of possible mechanisms by which changes in external Mg2+ concentration may affect cell metabolism, the most consistent with known properties of the system is the concept of a central role for intracellular free Mg2+ in the coordinate control of growth and metabolism in animal cells.
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  • 141
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A permanent cell line C2M of mouse melanoma B16 was highly melanized in a modified Eagle's MEM supplemented with 10% calf serum, when the medium contained 1 mM galactose and 10 mM pyruvate instead of 5.5 mM glucose. The activity of the key enzyme for melanogenesis, tyrosinase (EC 1.14.18.1), of living cells cultured in the galactose-pyruvate medium was consistently 27 times higher than that of cells in normal MEM. This high level of tyrosinase activity was maintained in the stationary phase, in contrast to the activity of cells in normal medium, which decreased sharply in the stationary phase. It seems likely that tyrosinase activity is suppressed by the presence of glucose rather than stimulated by galactose.This modified medium should be useful for obtaining a high level of tyrosinase activity in living cells in culture and in cell-free extracts.
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  • 142
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    Journal of Cellular Physiology 92 (1977), S. 221-231 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Alkaline 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 induction by dibutyryl cyclic AMP.
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  • 143
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    Journal of Cellular Physiology 92 (1977), S. 257-263 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Local anesthetics inhibit the exchange transport of glucose in human erythrocytes. All compounds tested showed a competitive inhibition except lidocaine and baycaine causing a non-competitive one. Moreover the transport system can bind two inhibitor molecules to one transport site as described for tetracaine and oxybuprocaine.
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  • 144
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Five clones of mouse neuroblastoma cells able to grow in hypoxanthine-aminopterin-thymidine containing medium were isolated from a hypoxanthine-guanine phosphoribosyltransferase (HGPRT; EC 2.4.2.8; IMP: pyrophosphate phosphoribosyltransferase) deficient cell line. These hypoxanthine-aminopterin-thymidine resistant revertant clones had 45-55% of wild-type cell HGPRT activity. Kinetic studies indicated that the HGPRT in revertant clones had a reduced maximal velocity as compared to wild type cells based on cell protein. Apparent Km values of HGPRT for hypoxanthine and 5-phosphoribosyl-1-pyrophosphate were similar in wild-type and revertant cells. Heat inactivation studies demonstrated a similar heat lability for HGPRT in revertant and wild-type cells. An antibody fraction prepared from serum of rabbits immunized with HGPRT partially purified from mouse liver was used to measure the amount of cross-reacting material in normal and revertant clones. The revertant clones had one-half the amount of cross-reacting material present in wild-type cells, based on a given amount of cell protein. These data indicate that the revertant cells may contain fewer HGPRT molecules with unaltered catalytic activity.
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  • 145
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    Journal of Cellular Physiology 92 (1977) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 146
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    Journal of Cellular Physiology 92 (1977), S. 345-352 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Receptors for the steroid hormone dexamethasone have been analyzed in clones of myeloid leukemic cells which differ in their ability to be induced by dexamethasone to form C3 and Fc rosettes, to synthesize and secrete lysozyme and form macrophages. The receptor dependent nuclear binding of (3H)-dexamethasone has been measured in intact cells. As found with other glucocorticoid receptors, saturation of nuclear binding occurred at 4 × 10-8 M (3H)-dexamethasone. The specificity of the receptors for only certain steroids was shown by the competition of nuclear binding by prednisolone, progesterone and testosterone, but not by the inactive steroid androstenedione. Nuclear bound hormone-receptor complexes were released from the nucleus by treatment with deoxyribonuclease, indicating that the complexes were associated with DNA-containing structures.The amount of nuclear binding of receptors was similar in all clones examined, including those which could not be induced for rosette, lysozyme or macrophages. The non-responding clones were also similar to the responding clones in the kinetics of binding, hormone concentration dependence of binding and association with DNA-containing structures. The results indicate that the non-responding clones of myeloid leukemic cells did not have detectable defects in the number, nuclear transport, or association with DNA of their steroid receptors.
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  • 147
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    Journal of Cellular Physiology 92 (1977), S. 353-364 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Exponentially growing Balb/3T3 mouse fibroblasts contain protein populations with slow and fast turnover. These two stability classes were labelled selectively with 3H-leucine. The intracellular degradation of the proteins was then followed as the release into the medium of radioactive leucine.The degradation rate of both stability classes of protein is increased by about 55% in cultures whose growth is inhibited by high cell density. Serum-deprivation, which also halts cell growth, accelerates protein breakdown to a smaller extent, the increase for relatively stable and unstable proteins being 30% and 13%, respectively.The density-dependent increase in protein breakdown is also found in BHK21 cells but not in chick fibroblasts. Protein degradation in Balb/3T3 cells transformed by simian virus 40 is affected by serum-deprivation but not by cell density.The proteins which are relatively stable during growth were shown to become less stable in density-inhibited or serum-deprived cultures, and vice versa.Cycloheximide inhibits protein degradation to a variable extent. Dibutyryl adenosine-3′,5′-cyclic monophosphate has no effect on the protein degradation under the conditions investigated here.
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  • 148
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    Journal of Cellular Physiology 92 (1977), S. 381-400 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The quantitative dependence of the initiation of DNA synthesis in nonreplicating cultures of human diploid fibroblasts (HDFs) on the concentration of fresh serum present in the stimulating medium has been analyzed. A simple formal analysis of the system suggested that the theory of dissociation reactions should lead to a model analogous to the Michaelis-Menten formulation. Accumulation of enough data for statistical analysis became possible by innovations in the culture techniques and isotope incorporation methods. The data were shown to conform to this model, and parameters Vm and K′m were calculated, together with appropriate statistical functions, from a weighted linear regression of the double reciprocal transformation of the data. Several variables in the culture system were assessed for their effects on the kinetic parameters. The results were consistent with the hypothesis that Vm is a measure of the maximum population of cells capable of responding to the stimulation, and K′m is an estimate of the interaction between the mitogenic factors in serum and the cell surface.Different strains of HDFs had different parameter values. Of several culture variables tested, the Vm was found to be influenced by the type of serum used, and by overall cell density as well as density variations within the monolayer. K′m showed significant changes only in response to cell density, and the evidence suggests that the affinity of cells for serum factors decreases as the cell density increases in confluence.
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  • 149
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A method involving short pulses of 5-bromodeoxyuridine (brUdRib) followed by irraidation with 313 nm light was used to locate the time of replication of certain genes during the cell cycle of two cell lines, AF8 and AL106. AF8, a temperature-sensitive mutant of BHK21/13 cells, grows at 33°C but not at 39.5°C. AL106, a hybrid clone of tsAF8 and SV-40 transformed Lesch-Nyhan fibroblasts (LNSV), which retains all hamster chromosomes and one human chromosome (No. 3), has the ability to grow at 39.5°C. AF8 and AL106 cells synchronized at the G1-S boundary were released from their block and pulsed with brUdRib for 2-hour periods during the S phase. The cells were subsequently irradiated with 313 nm light. Colony-forming efficiency and revertants frequency were studied. Incorporation of brUdRib during the early S phase (0-4 hours from the begining of S), decreased the colony-forming efficiency of AL106 cells both at 33°C and 39.5°C, and also of AF8 cells at 33°C. No AF8 colonies grew at the nonpermissive temperature regardless of the treatment. Thus the time of replication of genes responsible for colony-forming ability was the same in tsAF8 at the permissive temperature and in AL106 at both temperatures. The time of replication of the genes responsible for the ts function in AF8 cells was located by determining the revertants frequency in synchronized AF8 cells pulsed with brUdRib and irradiated during 1- to 2-hour periods of the S phase. Back-mutants were scored by counting the number of clones capable of growing at 39.5°C (nonpermissive for AF8 cells). The highest frequency of induced back-mutations occurred in synchronized AF8 cells pulsed with brUdRib (and irradiated) between two to four hours from the begining of the S phase. Exposure to brUdRib during other periods of the S phase or during G1 had no effect on the reversion rate.This method can be used to locate the time of replication (in S) of ts genes in other temperature-sensitive mutants or of other specific genes in other conditional mutants.
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  • 150
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    Journal of Cellular Physiology 92 (1977), S. 401-405 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Human cell lines derived from a melanoma and a colon carcinoma, and cultures of human melanocytes and intestinal epithelial cells, as well as a mouse mesenchymal non-neoplastic cell line and a malignant subline of the same have been quantitatively studied in tissue culture for their sensitivity to thymidine. All three tumor lines produced solid tumors when injected into nude thymus-deficient mice. No tumors were obtained by injecting cells of the human normal long-term cultures or of the non-neoplastic mouse line.The tumor-producing lines showed a greater sensitivity to the lethal effects of high concentrations of thymidine than their non-tumor-producing counterparts. Less than 23% of the tumor cells survived 72 hours in the presence of 1 mg/ml of thymidine, in contrast to 60% or more of the non-tumor cells.Colony formation was much more inhibited by thymidine and the differential between normal and tumor cells was even more pronounced. Tumor cells which also were treated for 72 hours with 1 mg/ml of thymidine and then plated in fresh medium formed very few colonies. If the plating efficiency of the untreated controls is considered as 100%, 4.3% or less of the treated tumor cells formed colonies, in contrast to 33% or more of the non-tumor cells.
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  • 151
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    Journal of Cellular Physiology 92 (1977), S. 437-445 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A mutant clone resistnat to dibutyryl cyclic AMP was isolated from S49 mouse lymphoma cells. The mutant expressed a form of cyclic AMP-dependent protein kinase distinguishable from wild type kinase by its decreased sensitivity to activation by cyclic AMP and its increased thermal lability. Hybrids formed between mutant and wild type cells were resistant to dibutyryl cyclic AMP and expresed both mutant and wild type activities in about equal amount. The parent mutant cells also appeared to express wild type kinase activity, but at a lower level. We conclude that wild type S49 cells have and expression two identical alleles for the regulatory subunit of protein kinase, one of which has undergone mutation in the mutant cells.
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  • 152
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    Journal of Cellular Physiology 92 (1977), S. 469-480 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A morphologically detectable cell coat, composed of glycoprotein, glycolipid, and glycosaminoglycan, is present on the external surface of most vertebrate cells. We have invetigated the composition and organization of glycosaminoglycans in the cell coat of cultured human embryo fibroblasts by labeling cells with 3H-glucosamine and Na235SO4 and subsequently treating cultures with specific enzymes. Components released were identified by chromatography and specific enzymatic digestion. In situ incubation with leech hyaluronidase (4 μg/ml) removed only hyaluronic acid from the cell surface whereas testicular hyaluronidase (0.5 mg/ml) removed both hyaluronic acid and chondroitin sulfate. Trypsin (0.1 mg/ml) released a large mass of glycopeptides in addition to hyaluronic acid, chondroitin sulfate, and heparan sulfate. The affinity of the cell coat for the cationic dye, ruthenium red, was reduced by leech hyaluronidase treatment. Sequential enzyme digestions of the cell surface showed that hyaluronic acid could be removed without the concomitant or subsequent release of sulfated glycosaminoglycans, suggesting that the hyaluronic acid is not a structural backbone for glycosaminoglycan complexes of the external cell surface.
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  • 153
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    Journal of Cellular Physiology 93 (1977), S. 17-24 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Normal diploid human fibroblasts, cultured at high density (1-2 × 105 cells per cm2) release two growth promoting activities into the culture medium. The fibroblast proliferation activity-conditioned medium facilitates the attachment of low density cells to the substrate. That activity resides in a non-dialyzable material that is sensitive to proteolytic inactivation. A second activity is dialyzable and can be recovered in the dialysate. In the presence of serum it stimulates cell growth. After 168 hours of incubation conditioned medium cultures contain five times more cells than are present in comparable cultures without conditioned medium. A reproducible biological assay for each activity is described.
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  • 154
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    Journal of Cellular Physiology 93 (1977), S. 309-311 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Fractions from a Sephadex gel filtration of homogenized Ascidia nigra blood cell lysate were analyzed for vanadium by atomic absorption spectroscopy. The results were unaffected by temperature from 4-21°C, and by ionic strength in the range 0.09-1.0 M (NaCl). Appreciable loss of vanadium in the supernatant was experienced above pH 2.2. Experiments at pH 2.1 under anaerobic conditions show that the green chromogen and the vanadium-containing bands elute separately. Under these experimental conditions, the vanadium-containing species is of relatively low (⋍ 1,000) molecular weight.
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  • 155
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    Journal of Cellular Physiology 93 (1977), S. 57-67 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The surfaces of cells from the early embryo of the chick were examined using electron microscope techniques for the visualization of concanavalin A-binding sites. Horseradish peroxidase and Ferritin labelled concanavalin A were used to determine the distribution of the binding sites. All surfaces of the epiblast and hypoblast layers which were accessible to concanavalin A showed the presence of binding sites in stage 1 embryos. The ventral surface of the epiblast showed a high lectin affinity which may reflect the development of a basal lamina on this surface. The individual hypoblast cells at this stage showed a non-uniform distribution of binding sites, having a greater affinity on the dorsal surface than the ventral. By the time of primitive streak formation (stage 4-5) the dorsal surface of the epiblast displayed increased binding sites, while the frequency of sites on the ventral surface of the endoblast was reduced. The latter may reflect a change from one cell population to another, which occurs in the lower layer of the embryo at this time. No consistent correlation could be drawn between changes in motility of cells actually invaginating through the primitive streak and changes in affinity for concanavalin A. An overall increase in affinity of the dorsal surface of the epiblast was revealed by Ferritin and may reflect the changes in surface structure occurring in readiness for the morphogenetic migrations of gastrulation.
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  • 156
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    Journal of Cellular Physiology 93 (1977), S. 99-104 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Laser microirradiation of neonatal rat (1 to 2-day-old) ventricular cells in tissue culture results in overt changes in contractility. The intracellular study of their ongoing electrical activity prior to, during, and after laser microirradiation demonstrates that definite membrane alteration occurs concomitantly with induced contractile responses. Although all ventricular cells are depolarized by laser microirradiation, the ultimate response elicited seems to differ according to the type of myocardial cell impaled. Typical fibrillation potentials were induced mainly in pacemaker cells.
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  • 157
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    Journal of Cellular Physiology 93 (1977), S. 69-79 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The role of the nucleus in bringing about the induction of tyrosine aminotransferase (TAT) by glucocorticosteroid hormone and its deinduction upon steroid removal has been studied in enucleated rat hepatoma tissue culture cells (FU5-5). Both processes require the presence of the nucleus. However, cytoplasts from preinduced cells show an intial rapid decline in enzyme activity immediately after enucleation followed by maintenance of a constant level of activity. This initial decline in enzyme activity can be partially prevented by trypan blue, an inhibitor of lysosomal activity. This suggests that the early fall in enzyme activity could be due to an increase in the level of lysosomal activity immediately after enucleation. The subsequent constant level of activity seems due to maintenance rather than synthesis and degradation since it is not affected by cycloheximide. The absence of degradation applies to other kinds of proteins in enucleated FU5-5 cells and enucleated mouse fibroblast L cells. Thsese experiments suggest that some kind of labile RNA or protein dependent on the presence of the nucleus is required for the degradation of all classes of proteins in diferent kinds of cells.
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  • 158
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Colchicine inhibited the initiation of DNA synthesis by hepatocytes in vivo and by WI-38 and C3H10T 1/2 cells in vitro. All three cell types were most sensitive to colchicine when it was administered at the time of, or shortly after, proliferative activation (by partial hepatectomy or medium-serum change). WI-38 and C3H10T 1/2 cells became less sensitive to colchincine as the time between proliferative activation and addition of the drug was increased. Hepatocytes, on the other hand, showed a second stage of sensitivity immediately before the onset of DNA synthesis. Ongoing DNA synthesis was not inhibited by colchicine in any of the cell types. The two prereplicative stages of colchicine sensitivity in liver were also sensitive to vincristine but not to lumicolchicine, an analogue of colchicine which does not bind to tubulin. The data obtained with these drugs indicates that microtubules may be involved in the prereplicative stages of cell proliferation, but non-specific binding to other membrane proteins cannot be ruled out. Colchicine (at a dose of 50 μg/100 g of body weight), which when injected 30 minutes after hepatectomy delayed the initiation of DNA synthesis for at least 14 hours, delayed the induction of ornithine decarboxylase (at the beginning of prereplicative development) by only two hours. Thus, the inhibitory action of colchicine on the initiation of DNA synthesis does not appear to be mediated by inhibition of polyamine synthesis.
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  • 159
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Short term, carrier mediated transport of D-glucose, L-leucine and L-lysine by guinea pig peritoneal macrophages was characterized. Analysis of the amino acid transport demonstrated two-limbed double reciprocal plots suggesting two transport systems for each amino acid. The low concentration limb of the curves established a Km of 0.1 mM for L-leucine and 0.05 mM for L-lysine; Vmax values were 2.0 and 2.85 nmole/mg protein/90 seconds, respectively. Leucine and lysine were shown to be competitive inhibitors of each other. Further competition studies revealed that other amino acids also had affinity for these carriers. Amino acid transport was found to be sensitive to sulfhydryl active compounds. Colchicine treatment of peritoneal macrophages did not inhibit the transport of the amino acids tested. Preloading macrophages with latex beads or heat-killed staphylocci by phagocytosis stimulated 2-deoxy-D-glucose (2-dOG) uptake markedly, but had no measurable effect on amino acid transport. Although total transport of 2-dOG increased in post-phagocytic macrophages, the kinetics of the system were not altered significantly. The Km for both pre- and post-phagocytic transport of 2-dOG was shown to be 1.2 mM and the Vmax was shown to increase from a pre-phagocytic value of 20 nmoles/mg protein/90 seconds to a post-phagocytic 27 nmoles/mg protein/90 seconds. Phagocytosis of heat-killed staphylococci by guinea pig polymorphonuclear leukocytes (PMNs), however, did not cause an augmentation in hexose transport in the cells. The presence of colchicine during phagocytosis did not alter subsequent uptake of amino acids by the macrophages.
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  • 160
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The hydrolysis of ATP and AMP by enzymes located on the external side of the plasma membrane (ecto-ATPase and ecto-AMPase) was studied in mouse myeloid leukemic cells, normal early myeloid cells, and normal mature granulocytes and macrophages. Nine clones of myeloid leukemic cells were used belonging to three groups that differ in their ability to be induced to differentiate by the differentiation-inducing protein MGI. These three groups consisted of MGI+D+ that can be induced to undergo complete differentiation, MGI+D+ that can be induced to partially differentiate and MGI-D- with no induction of differentiation. The ecto-ATPase activity of normal early myeloid cells was similar to that of normal mature granulocytes and macrophages and higher than that of any of the leukemic cells. Among the leukemic cells, the MGI-D- cells had the highest level of ecto-ATPase activity.The behaviour of ecto-AMPase differed from that of ecto-ATPase. Some MGI-D- clones had a higher ecto-AMPase activity than normal cells and MGI+D- and MGI+D+ cells showed no detectable activity. Neither the ecto-ATPase nor ecto-AMPase activities changed after induction of differentiation in normal early myeloid or MGI+D+ leukemic cells. The results indicate that the myeloid leukemic cells had a decreased ability to hydrolyse external ATP, that there can be an independent regulation of ecto-ATPase and ecto-AMPase and that neither of these enzyme activities changed during differentiation.
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  • 161
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    Journal of Cellular Physiology 93 (1977), S. 395-405 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: DBcAMP reversibly arrests cultivated Cloudman melanoma cells in the late S and G2 phases of the cell cycle. This is supported by the measurement of DNA synthesis by autoradiography and measurement of cellular DNA by two methods - the diphenylamine reaction and microspectrophotometry of Feulgen stained cells. We also present evidence that (1) cell division is prevented if DBcAMP is added as late in the cycle as early S phase. (2) The inhibition of cell division does not appear to be caused by products of tyrosine oxidation. (3) The increase in cell size that occurs in the presence of DBcAMP reflects continued synthesis of protein in the absence of cell division.
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  • 162
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    Journal of Cellular Physiology 93 (1977), S. 213-225 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: During the initial ten hours of growth in lymphocytes stimulated by phytohemagglutinin, the cells are converted from a state in which over 70% of all ribosomes are inactive free ribosomes, to one in which over 80% of ribosomes are in polysomes or in native ribosomal subunits. In this initial period, there was a neglible increase in total ribosomal RNA due to increased RNA synthesis, and abolition of ribosomal RNA synthesis with low concentrations of actinomycin D did not interfere with polysome formation. Therefore, the conversion is accomplished by the activation of existing free ribosomes rather than by accumulation of newly synthesized particles. The large free ribosome pool of resting lymphocytes is thus an essential source of components for accelerated protein synthesis early in lymphocyte activation, before increased synthesis can provide a sufficient number of new ribosomes. Free ribosomes accumulate once more after 24 to 48 hours of growth, when RNA and DNA synthetic activity are maximal. This reaccumulation of inactive ribosomes at the peak of growth activity may represent preparation for a return to the resting state where cells are again susceptible to stimulation.Activation of free ribosomes to form polysomes appears to involve modification of at least two steps: (a) dissociation of free ribosomes with stabilization as native subunits, and (b) adjustment of a rate-limiting step at initiation.
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  • 163
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    Journal of Cellular Physiology 93 (1977), S. 237-246 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study involves the use of fibroblast growth factor (FGF) as a substitute for exogenous serum to examine the early transport changes which occur when quiescent 3T3 cells re-initiate active growth. FGF, in nanogram amounts, together with insulin and dexamethasone, can induce mitogenesis and mitosis in 3T3 cells GO-arrested by holding in growth medium containing 0.8% calf serum. In terms of quiescent cell transport activity enhancement, FGF is 300,000-fold more effective than fresh serum, on a protein basis. In addition, very short exposure of serum-depleted cells to FGF indicates that a distinct temporal or time sequence exists in the transport system activation process. For example, uptake of α-aminoisobutyric acid (AIB) and uridine are stimulated very rapidly, whereas hypoxanthine uptake does not respond until much later. Closer analysis shows that AIB uptake is maximally enhanced within zero to two minutes after FGF addition to cells. Finally, the stimulatory effect of FGF on transport system activities is specific in terms of the proliferative state of the cells to which it is added, and in terms of the uptake systems which respond to it.
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  • 164
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    Journal of Cellular Physiology 93 (1977), S. 285-292 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The distribution of polyamines between the nucleus and the cytoplasm, and the role of the nucleus in polyamine metabolism, have been studied using cells enucleated with cytochalasin B. Spermidine and spermine were found in the nuclear and the cytoplasmic fractions of L929 cells; their concentration was 3-fold higher in the former fraction. Ornithine decarboxylase activity was only found in the cytoplasm, and this activity could be stimulated in enucleated cells by the addition of fresh medium. These cells synthesized putrescine actively, but the putresoine made was not converted to spermidine, and accumulated to relatively high concentrations. Similarly, methionine did not act as a precursor to spermidine in enucleated cells, in contrast to whole cells, although it was incorporated into cell protein. Spermidine synthesis, unlike putrescine synthesis, appears to be completely dependent on a nuclear component.
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  • 165
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    Journal of Cellular Physiology 90 (1977), S. 1-8 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Novikoff rat hepatoma cells were propagated in suspension cultures containing 0.5 to 10 μC of 3H-methyl-thymidine, 3H-5-uridine, 3H-G-adenosine or 3H-8-adenine. The presence of the 3H-labeled precursors caused an inhibition of cell replication which was due to a delay or arrest of the cells in G2 and M. The degree of inhibition was proportional to the amount of radioactivity incorporated into nucleic acids. Almost immediate and complete inhibition resulted from incubation with 10 μC 3H-thymidine/ml. The presence of 0.5 μC 3H-thymidine/ml caused a significant increase in the relative proportion of cells in G2 + M, even though the population doubling time of the culture appeared to be unaltered.
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  • 166
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The quantitative assay described in the preceding paper (Pessac et al., 1977) was used to study the effects of serum and various proteins on isotypic adhesion of chick embryo neural retina cells. Fetal bovine, chicken, horse, rabbit and human sera promoted cell adhesion to the same extent. The same sera also enhanced isotypic adhesion of cells from other organs showing that the cell adhesion promoting activity of sera was not organ specific. Neural retina (NR) cell collection in serum supplemented medium was not modified by protein synthesis or metabolic inhibitors and was temperature dependent with a maximum at 38°C. The higher temperature does not seem to be required for repair of the cell surface after dissociation, but for the process of adhesion itself. Various serum fractions and egg albumin showed a cell adhesion promoting activity similar to that of sera.
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  • 167
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    Journal of Cellular Physiology 90 (1977), S. 53-59 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Heparan sulfate from the surface of a variety of mouse cells at different cell densities was examined by ion-exchange chromatography. The results of this analysis show that: 1The heparan sulfate from new isolates of Swiss 3T3 cells transformed SV40 virus (a DNA tumor virus) elutes from DEAE-cellulose at a lower ionic strength than that from the parent cell type. This finding confirms our earlier observation with an established SV40-transformed cell line (Underhill and Keller, 1975) and eliminates the possibility that this change is caused by extended passage in culture.2For both parent and transformed 3T3 cells, the heparan sulfates from low and high density cultures were the same as judged by chromatography on DEAE-cellulose. This result demonstrates that the transformation-dependent change which we have observed is independent of cell density.3The heparan sulfate from Balb/c 3T3 cells transformed with Kirsten murine sarcoma virus (an RNA tumor virus) elutes from DEAE-cellulose prior to that from parent Balb/c 3T3 cells. This result extends the transformation dependent change in heparan sulfate to the Balb/c 3T3 cell line and to cells transformed with an RNA virus.
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  • 168
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    Journal of Cellular Physiology 90 (1977), S. 61-70 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Several types of cultured fibroblasts, including chick embryo, human and mouse, were killed by the addition of sodium ascorbate at final concentrations of 0.05-0.25 mM to cultures at the time of inoculation or to attached cells. Ascorbate did not affect the attachment of cells to the substratum. The effect on chick embryo fibroblasts was visible by fours hours and by six hours almost all cells had swelled and were becoming detached. By 24 hours detached cells had either lysed or become crenated in appearance. Other end-diol reducing agents and also glutathione and cysteine were effective while gulonolactone, a non-reducing analogue of ascorbate, was ineffective. Preincubation of medium containing ascorbate but no cells, conditions which result in degradation of the vitamin, led to loss of toxicity, indicating that a degradation product was not the lethal agent and that a component of the medium was not converted to a lethal substance. The lethal effect of both ascorbate and glutathione was prevented by the addition of catalase to the medium, suggesting that H2O2 formed by intracellular reactions and then excreted into the medium was the cytotoxic agent. This conclusion was supported by the findings that 0.05 mM H2O2 added to chick embryo fibroblasts was lethal and that the effect of this compound on cellular morphology was almost identical to that of ascorbate.
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  • 169
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    Journal of Cellular Physiology 90 (1977), S. 71-78 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Hybrid clones were obtained between a mouse cell line (3TP) and a temperature-sensitive Chinese hamster cell line (K12) unable to grow at 40° because of a ts defect apparently located at the G1/S transition. The great majority of hybrid clones grew at 40°, showing the ts defect to be “recessive.” Chromosome DNA replication was analyzed in some detail in three hybrid clones with balanced complements. Although the S period of these hybrids was longer than that of K12, DNA replication in mouse and hamster chromosomes started and ended synchronously. Upon prolonged culture, mouse chromosomes were lost as they are in hybrids involving a non ts Chinese hamster partner, in which case asynchronous chromosome replication appears to be the rule. It seems therefore that asynchronous replication is not the determining factor in chromosome loss from cell hybrids.
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  • 170
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 90 (1977), S. 91-103 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effects of ACTH and 8-Br-cAMP on growth and replication of a functional mouse adrenal tumor cell line (Y-1) were investigated. ACTH and 8-Br-cAMP both inhibited DNA synthesis and replication when added to randomly growing cell cultures. ACTH addition and serum deprivation each arrested cells in G1; an additional point of arrest in G2 occurred with 8-Br-cAMP. Cells whose growth was arrested in G1 by ACTH had a significantly larger volume and protein and RNA content compared to cells arrested in G1 by serum deprivation. When ACTH or 8-Br-cAMP was added with serum to cells arrested by serum deprivation, the wave of DNA synthesis and cell division seen with serum was abolished. ACTH and 8-Br-cAMP had no effect on the serum-induced increases in protein and RNA content, rates of leucine incorporation into protein and uridine incorporation into RNA, and RNA polymerase I activity observed in cells during the pre-replicative period. Partial inhibition of the serum-induced increase in uridine transport occurred. ACTH and cAMP do not appear to inhibit replication by generalized negative pleiotypic effects but rather to inhibit the initiation of DNA synthesis more specifically. The ACTH-arrested Y-1 cell resembles an in vivo hypertrophied adrenal cortical cell.
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  • 171
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Sodium, potassium, iron and sulfur contents of single human red cells were measured using electron microprobe microanalysis. Three preparative procedures were compared, and the most reliable technique was found to be spraying of cells onto polished pyrolytic graphite by atomization. Primary standards were prepared by adjusting the intracellular electrolyte content of red cells, eliminating the need to correct for X-ray absorption. Samples were stable under the electron beam during analysis, and could be stored for long periods of time. Strong correlations were found between the X-ray intensities of iron and sulfur and between potassium and sodium. X-ray intensities of potassium and sodium were found to be directly proportional to internal ionic content. Large populations of single cells could be analyzed and the distribution of their elemental content studied.
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  • 172
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    Journal of Cellular Physiology 90 (1977), S. 145-160 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A temperature-sensitive mutant of Chinese hamster cells is described which has two interesting properties: (1) it is a cell cycle mutant and (2) glycoprotein synthesis appears to be affected at the non-permissive temperature (40°C). Synchronized cells shifted to 40°C in the beginning of their G1 phase do not incorporate [3H]-thymidine into DNA during the expected S-phase, but once DNA synthesis has been initiated (∼ 10 hours after termination of serum starvation) a shift to 40°C no longer leads to an arrest of DNA synthesis. Flow microfluorimetric analysis of DNA content/cell supports this conclusion and indicates that a majority of cells become arrested in the G1 phase of the cell cycle when a non-synchronized population of cells is transferred to 40°C. Apparently at all times in the cell cycle there is a drastic reduction of incorporation of labeled sugars (particularly fucose) into glycoproteins. The uptake of fucose and its conversion to GDP-fucose appears to be normal at 40°C. Chromatographic analysis indicates that all classes of glycoproteins are affected, and we do not find any evidence for partially completed oligosaccharides at 40°C. Overall protein synthesis is not reduced at the nonpermissive temperature during the time interval under consideration and the number of polysomes attached to membranes (RER) is also normal at 40°C. This suggests that the defect is at an early step in the synthesis or regulation of synthesis of glycoproteins. The mutation is a recessive mutation in hybrid cells and mutagen induced revertants can be obtained which grow normally at 40°C and in which glycoprotein synthesis at 40°C is restored to normal, wild type levels.
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  • 173
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    Journal of Cellular Physiology 90 (1977), S. 225-231 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Endothelial cells from bovine aorta and human umbilical vein and fibroblasts from human foreskin were cultured and subsequently evaluated for ability to metabolize serotonin (5-HT) to 5-hydroxyindoleacetic acid (5-HIAA). Cells were incubated for three hours with 4 × 10-6 M [14C] 5-HT creatinine sulfate. [14C] 5-HIAA was separated from labeled 5-HT by column chromatography and measured by scintillation counting. Production of 5-HIAA by bovine aorta cells was 39.0 ± 7.5 (S.E.M., n = 6) nmoles per 109 cells per hour. Production of 5-HIAA was markedly inhibited by the presence of 10-4 M iproniazid (an inhibitor of monoamine oxidase) or 10-4 M imipramine (an inhibitor of amine transport). 5-HIAA was the only product of 5-HT metabolism detected by thin layer chromatography. Production of 5-HIAA by human umbilical vein endothelial cells was 5.4 ± 2.0 nmoles per 109 cells per hour (n = 5) and by human foreskin fibroblasts was 3.9 ± 1.4 nmoles per 109 cells per hour (n = 5). The results obtained during incubation in the presence and absence of inhibitors indicate that bovine aorta endothelial cells maintained in tissue culture are able to transport serotonin with subsequent production of 5-HIAA. By contrast, human umbilical vein endothelial cells and fibroblasts exhibited relatively low rates of 5-HT uptake and metabolism.
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  • 174
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    Journal of Cellular Physiology 90 (1977), S. 233-240 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cultured mouse and human cells were arrested in their growth by artificially depriving them of phosphate. The quiescent cells could be stimulated to synthesize DNA and to divide by addition to the growth medium of insulin, dialyzed serum and/or the full concentration of phosphate. In order to gain insight into mechanisms by which insulin and serum stimulate growth, the inhibitory effects of antimitotic agents were examined. Of the inhibitors tested, vinblastine and cytocalasin B abolished the growth promoting activity of insulin, while colchicine inhibited the activity of both serum and insulin. The present results suggest that insulin-stimulated growth is mediated by a different pathway than serum-stimulated growth and is sensitive to mechanisms that occur at various times prior to insulin addition.
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  • 175
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    Journal of Cellular Physiology 90 (1977), S. 253-263 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A protease from Tetrahymena pyriformis inactivated eight of nine commercially available enzymes tested, including lactate dehydrogenase, isocitrate dehydrogenase (TPN-specific), glucose-6 phosphate dehydrogenase, D-amino acid oxidase, fumarase, pyruvate kinase, hexokinase, and citrate synthase. Urate oxidase was not inactivated. Inactivation occurred at neutral pH, was prevented by inhibitors of the protease, and followed first order kinetics. In those cases tested, inactivation was enhanced by mercaptoethanol. Most of the enzyme-inactivating activity was due to a protease of molecular weight 25,000 that eluted from DEAE-Sephadex at 0.3 M KCl. A second protease of this molecular weight, which was not retained by the gel, inactivated only isocitrate dehydrogenase and D-amino acid oxidase. These two proteases could also be distinguished by temperature and inhibitor sensitivity. Two other protease peaks obtained by DEAE-Sephadex chromatography had little or no enzyme inactivating activity, while another attacked only D-amino acid oxidase.At least six of the enzymes could be protected from proteolytic inactivation by various ligands. Isocitrate dehydrogenase was protected by isocitrate, TPN, or TPNH, glucose-6-dehydrogenase by glucose-6-P or TPN, pyruvate kinase by phosphoenolypyruvate or ADP, hexokinase by glucose, and fumarase by a mixture of fumarate and malate. Lactate dehydrogenase was not protected by either of its substrates or coenzymes. Citrate synthase was probably protected by oxalacetate.Our data suggest that the protease or proteases discussed here may participate in the inactivation or degradation of at least some enzymes in Tetrahymena. Since the inactivation occurs at neutral pH, this process could be regulated by variations in the cellular levels of substrates, coenzymes, or allosteric regulators resulting from changes in growth conditions or growth state. Such a mechanism would permit the selective retention of enzymes of metabolically active pathways.
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  • 176
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    Journal of Cellular Physiology 90 (1977), S. 307-320 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: When Vero cells, a line derived from an African Green Monkey kidney, are grown under conditions where the saturation density is limited by serum, they deplete the growth medium of a factor necessary for cell division. The factor is a component of serum. When Vero cells are plated at low density (2 × 104/cm2) in this depleted growth medium (after dialysis against serum-free Dulbecco's Modified Eagle's Medium) they initiate an unbalanced program of growth. Protein synthesis proceeds at the same rate as parallel cells in fresh serum, and the cells accumulate protein as a function of time. DNA synthesis is also initiated in these cells, and the amount of DNA per cell increases for the next four days after plating. However the cells quickly stop dividing. Measurements of DNA per cell using microspectrofluorometry show that the cells are accumulating in the late S and G2 period during this time. Thus we conclude that these cells cannot pass through a transition point in G2. When fresh serum is added to cells after three days in depleted growth medium, they divide before they begin to synthesize DNA. This further confirms that they are in late S and G2. Cell division is promoted in Vero cells in depleted growth medium by bovine fetuin, and to a lesser extent by bovine albumin. Cell division is not promoted by insulin, hydrocortisone, dexamethasone, linolenic acid, calcium, and trypsin inhibitor from ovomucoid. From these data we conclude that transit through G2 requires the presence of an extracellular factor.
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  • 177
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    Journal of Cellular Physiology 90 (1977), S. 337-350 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Balb/C 3T3 cells entered the quiescent G0 state following serum deprivation. On addition of fresh serum, more than 95% of the culture resumed growth, but with asynchronous kinetics. If hydroxyurea were added just before the first cells reached S phase, at least 90% of the cells accumulated at the Gl/S border over the next ten hours. When the block was removed, the culture moved synchronously into S phase. As the cells traversed S, the replication kinetics of three classes of rapidly renaturing DNA were analyzed. Main band highly repeated DNA and foldback DNA replicated continuously. In contrast, satellite DNA replication did not commence until three hours into S, whereupon its rate of synthesis increased very rapidly, reaching a maximum within the next two hours. These results are discussed in the light of earlier work utilizing other methods of cell synchronization.
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  • 178
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    Journal of Cellular Physiology 90 (1977), S. 361-374 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: 5-azacytidine at concentrations higher than 5 μM inhibited the differentiation of a rat myoblast line in vitro. It was also somewhat cytotoxic at this level. Variants resistant to the cytotoxic effect of 5-azacytidine were obtained which were simultaneously unable to differentiate into myotubes and exhibited altered morphology. These characteristics were retained by the variants when subcultured in the absence of the drug for over 700 generations. Several of the azacytidine resistant cells were more susceptible than the parental line to the lethal action of 5-bromodeoxyuridine and adenosine, but not that of cytosine arabinoside, ouabain or 8-azaguanine.The variants were capable of transporting uridine, thymidine and 5-azacytidine. The uridine kinase activity was one-half to one-third of that in the parental cells but it was not missing completely in any of the variants. Two independently isolated variants selected for detailed study showed a 2- to 3-fold increase in the activity of orotidylic acid decarboxylase. This enzyme in the variants in contrast to that of the parental cells was completely insensitive to the inhibitory effect of a nucleotide generated from ATP and 5-azacytidine in cell extracts (probably 5-azacytidine monophosphate). These observations point to the possibility that 5-azacytidine resistance arises in myoblasts due to an alteration of the components of two target pathways of this drug, viz., the de novo pyrimidine pathway and an undefined sequence leading to the synthesis of membrane components.
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  • 179
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The metabolic flow of trace amounts of D-[14C]-galactose was followed in cultures of transformed and untransformed hamster cells over a period ranging from five minutes to two hours. The results of chromatographic and enzymatic analyses of the soluble pools are described. Non-glycolytic cells (previously deprived of sugar for periods of up to 24 hours) convert D-galactose to galactose-1-phosphate and uridine diphosphoglucuronic acid in 10 to 20 minutes. In the same short assay time, glycolytic cells which have been maintained for 24 hours in media containing glucose or galactose convert D-galactose to uridine diphosphogalactose and uridine diphosphoglucose (ratio 1.4:1). Longterm deprivation of sugar also results in 3- to 4-fold increases in the uptake of galactose. In addition, the incorporation of galactose label into chloroform-methanol soluble material appears to be influenced by the culture conditions of the untransformed cells while incorporation in the transformed cells appears unaffected. When cycloheximide is included in the maintenance medium for extended periods, the non-glycolytic cells also show increases in galactose uptake rates but the glucose-fed, glycolytic cells lose uptake ability. UDPhexose is the main galactose metabolic peak in the soluble pools of the cycloheximide-treated, glycolytic and the cycloheximide-treated, non-glycolytic cells. The results of these experiments suggest that uptake of galactose and its subsequent metabolism are under separate control.
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  • 180
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    Journal of Cellular Physiology 91 (1977), S. 119-129 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper presents evidence that a protein characteristic of differentiated liver cells, liver alkaline phosphatase, is synthesized by the Chang liver cell line. Liver alkaline phosphatase was demonstrated by immumochemical assay, 32P-labeling and polyacrylamide gel electrophoresis, immunofluorescence microscopy, and the fluorescence-activated cell sorter. The synthesis of the liver enzyme by the Chang liver cells is interpreted to indicate fidelity of the Chang cells to their origin from human liver tissue. Chang liver cells also synthesize a phosphatase which is similar if not indentical to the placental alkaline phosphatase. Since a placental-type alkaline phosphatase has been observed in a number of non-trophoblastic cell lines and also in some neoplasms, it does not seem reliable as an index of the origins of the cell line. Because of the claims that Chang liver cells are actually HeLa cells, HeLa cells were studied in tandem with the Chang cells. The results showed that the HeLa cells do not make the liver type phosphatase. The data are discussed in relation to the question of HeLa cell contamination of the Chang cell line and the validity of criteria normally used to identify cell lines.
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  • 181
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    Journal of Cellular Physiology 91 (1977) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 182
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Using a series of cold-sensitive variants of chemically transformed BHK-21 cells, revertants to the normal phenotype derived from a dimethylnitrosamine transformed clone of BHK-21 as well as revertants to the normal phenotype derived from polyoma transformed BHK-21 cells we have demonstrated that the surface phenotype described by enhanced agglutinability with Con A and WGA can be dissociated from the transformed phenotype described by anchorage independence (growth in semisolid medium). Specifically we have demonstrated that the surface characteristic of enhanced agglutinability may be found in a variety of cell lines which fail to display an ability to grow in agar. Our work clearly shows that the two phenotypes described are not concomitantly controlled and tends to suggest that the phenotype of enhanced lectin agglutinability may be dissociated from the transformed phenotype.
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  • 183
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    Journal of Cellular Physiology 91 (1977), S. 289-296 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The total membrane fraction of a chick embryo fibroblast (CEF) homogenate accumulates calcium in an energy-dependent manner. This activity can be dissociated into azide-sensitive and azide-insensitive components. The azide-sensitive component of calcium uptake is believed to represent mitochondrial calcium uptake. The azide-insensitive component of calcium uptake is enhanced by the presence of a calcium trapping agent such as oxalate, and cannot utilize, ADP, inorganic phosphate and a Krebs cycle substrate to support uptake. The distribution of the azide-insensitive calcium uptake in subcellular fractions suggests that this uptake occurs in other than mitochondrial membranes. The membranes most likely to contribute to the azide-insensitive component of calcium uptake are the endoplasmic reticulum and plasma membrane. A microsomal preparation from CEF cells is essentially devoid of the azide-sensitive calcium uptake activity. This microsomal activity is similar in characteristics to the sarcoplasmic reticulum of skeletal muscle. However the specific activity of CEF microsomal calcium uptake system is much less than that found in the skeletal muscle system. The transport of calcium by these membranes provide a mechanism for the regulation of cytosol calcium levels and may play a role in the control of movement and growth of cultured cells.
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  • 184
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    Journal of Cellular Physiology 91 (1977), S. 297-303 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The relation between intracellular pH and the mitotic cycle of Physarum polycephalum was studied by two independent techniques. Both techniques revealed a long term cycling of intracellular pH which has the same period as the mitotic cycle. Qualitative detection of the changes in intracellular pH was made by measuring the changes in fluorescence of 4-methylesculetin which had been absorbed by the plasmodium. Quantitative measurements of intracellular pH were made throughout the mitotic cycle with antimony micro pH electrodes. The cycle of intracellular pH is sinusoidal in appearance. The maximum intracellular pH (pH 6.6) occurred at, or very near to, mitosis, and was approximately 0.6 pH units higher than the minimum pH, which occurred near the middle of the mitotic cycle.
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  • 185
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    Journal of Cellular Physiology 91 (1977) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 186
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effects of Fibroblast Growth Factor (FGF) and Epidermal Growth Factor (EGF) on the proliferation of bovine vascular endothelial cells has been examined. FGF induces the initiation of DNA synthesis and cell proliferation in cloned endothelial cells of fetal and adult origin at concentrations as low as 1 ng/ml and is saturating at 50 ng/ml. EGF had no effect over the same range of concentrations. The mitogenic effect of FGF is blocked by a crude extract of cartilage. Platelet extract is also mitogenic for vascular endothelial cells although to a lesser extent than the purified FGF. In contrast to vascular endothelial cells, both EGF and FGF are mitogenic for vascular smooth muscle cells although EGF is less mitogenic than FGF at 100 ng/ml. The mitogenic effect of EGF and FGF on vascular smooth muscle is not blocked by the addition of a crude extract of cartilage, thus demonstrating the specificity of the chalone like effect of cartilage crude extract for endothelial cells.
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  • 187
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    Journal of Cellular Physiology 91 (1977), S. 409-416 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Electron microprobe analyses of calcium distribution in the ciliated protozoan, Spirostomum ambiguum, indicated several calcium rich sites. One site was an endoplasmic distribution of calcium coincident with phosphorus which corroborates previous findings of hydroxyapatite deposits within Spirostomum. These apatite deposits were distributed throughout the endoplasm, but not within the nuclei or the contractile vacuole. Calcium was also detected within the cortical region. Cortical calcium was in greater concentration in the anterior portion of the organism and decreased towards the posterior end (region containing the contractile vacuole). Phosphorus and potassium were also detected as gradients from the anterior end, whereas magnesium was detected in the same density throughout the cortical region. Line scans of cortical regions suggested (1) distributions of calcium within mitochondria and/or vesicles, and (2) calcium associated with bundles of microfilaments.
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  • 188
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    Journal of Cellular Physiology 91 (1977), S. 429-440 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effect of serum stimulation on unidirectional and net K flux and their relationship to the initiation of DNA synthesis has been investigated in mouse 3T3 fibroblasts. Stimulation of quiescent 3T3 cells with 20% serum results in the initiation of S phase approximately ten hours after serum addition. During transition from G1 to S phase distinct changes in K transport and cellular K content occur. Total unidirectional K influx undergoes an immediate 2-fold increase upon serum addition, an observation in qualitative agreement with previous results (Rozengurt and Heppel, 1975). This total increase in unidirectional K influx represents a proportional increase in the active, ouabain sensitive component and the K-K exchange component. The initial increase in total flux is followed by a gradual decline over a 16-hour period to levels approaching those of quiescent cells. Following the initial increase in unidirectional K influx is an approximately 75% increase in cell K on a per milligram protein basis or a 40% increase on a per volume basis. This increase peaks at four to five hours and then declines to initial levels at 10 to 14 hours. Populations of quiescent cells given 20% serum plus 0.5 mM ouabain simultaneously are totally blocked from entering S phase, as determined by the appearance of 3H-thymidine labeled nuclei. However, if the ouabain is removed after six hours these cells then undergo the same changes in unidirectional K influx and content as serum stimulated cells with entrance into S phase retarded by five to six hours. If ouabain is added to serum stimulated cells at six hours, after the increase in K transport and K content have occurred, entrance into S phase is not entirely blocked. In cells stimulated with serum and 0.5 mM dBcAMP plus 1 mM theophylline simultaneously, entrance into S phase is greatly reduced as compared to serum stimulation only. However, the early and late changes in K flux and K content are not substantially altered. This indicates that the K transport events associated with G1 and early S phase are not directly regulated by changes in cAMP levels which follow serum stimulation.
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  • 189
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    Journal of Cellular Physiology 91 (1977), S. 473-473 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 190
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    Journal of Cellular Physiology 91 (1977), S. 459-472 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Persistent infection of murine neuroblastoma cells with a relatively non-cytopathic virus, lymphocytic choriomeningitis virus (LCMV), significantly lowered the cells' concentrations of choline acetyl transferase (CAT) and acetylcholine esterase (ACHE), enzymes which make or degrade acetylcholine. Quantities of acetylcholine enzymes remained depressed during the observation period of more than two years. This cellular luxury function was turned off without observable alterations in the cells' vital functions - growth rates, protein and RNA synthesis. Cloning experiments showed that CAT and ACHE levels were altered in the majority of LCMV infected neuroblastoma cells in culture and not limited to a specific subpopulation. Cells persistently infected with virus also contained receptors for neurotoxin A and α bungarotoxin. Six months after becoming infected, neuroblastoma cells having significant alterations in luxury functions stopped making infectious virus. Instead these cells now produced a defective interfering virus component.Similar events to those seen in vitro with neuroblastoma cells also occurred in vivo. Mice inoculated with LCMV at birth carried high titers of LCMV in brain tissues and viral antigens in neuronal cells as adults. Some of these mice also showed significant alterations in their ability to make and degrade acetylcholine when compared to age and sex matched controls.
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  • 191
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    Journal of Cellular Physiology 92 (1977), S. 77-90 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The rate of uridine uptake in Tetrahymena declines by an order of magnitude by two hours after shiftdown to a non-nutrient buffer. This alteration in uptake properties cannot be accounted for by an increase in the intracellular pool of uridine, an increase in apparent Km for uptake or a decline in the rate in which uridine is processed intracellularly.It is argued that the decrease in uridine uptake is due to a reduction in numbers of functional transport molecules exposed at the cell surface and is a reflection of a developmentally related cell surface transformation.In addition, the putative decline in functional transport molecules cannot be entirely explained by metabolic turnover of these molecules in the absence of replacement, nor does it require the synthesis of new protein. We discuss the possibility that a shift in equilibrium between accessible and inaccessible transporters is operating.Finally, a close correlation between conditions which elicit the transport alteration and those which allow the development of mating competency suggests that the two phenomena may be coordinately regulated.
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  • 192
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An enriched population of early myeloid cells has been obtained from normal mouse bone marrow by injection of mice with sodium caseinate and the removal of cells with C3 (EAC) rosettes by Ficoll-Hypaque density centrifugation. This enriched population had no EAC or Fc (EA) rosettes and contained 87% early myeloid cells stained for myeloperoxidase and/or AS-D-chloroacetate esterase, 7% cells in later stages (ring forms) of myeloid differentiation and 6% unstained cells, 2% of which were small lymphocytes. After seeding in agar with the macrophage and granulocyte inducer MGI, the enriched population showed a cloning efficiency of 14% when removed from the animal and of 24% after one day in mass culture. Both the enriched and the unfractionated bone marrow cells gave the same proportion of macrophage and granulocyte colonies.The normal early myeloid cells were induced to differentiate by MGI in mass culture in liquid medium to mature granulocytes and macrophages. The sequence of granulocyte differentiation was the formation of EA and EAC rosettes followed by the synthesis and secretion of lysozyme and morphological differentiation to mature cells. D+ myeloid leukemic cells with no EA or EAC rosettes had a similar morphology to normal early myeloid cells and showed the same sequence of differentiation. The induction of EA and EAC rosettes occurred at the same time in both the normal and D+ leukemic cells, but lysozyme synthesis and the formation of mature granulocytes was induced later in the leukemic than in the normal cells. The results indicate that selection for non-rosette-forming normal early myeloid cells also selected for myeloid colony forming cells, that these normal early myeloid cells can form colonies with differentiation to macrophages and granulocytes, that normal and D+ myeloid leukemic cells have a similar sequence of differentiation and that the normal cells had a greater sensitivity for the formation of mature cells by MGI.
    Additional Material: 7 Ill.
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  • 193
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    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 92 (1977), S. 115-128 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Previous studies have shown that growth to quiescence of fibroblast-like cells is accompanied by a large decrease in the rate of phosphate uptake. Since 3T3 cells can be arrested in the G1 (or G0) phase of the cell cycle by lowering the concentration of phosphate in the medium, we examined the possibility that the decline in phosphate uptake observed during growth to quiescence might be a key event in the inhibition of DNA synthesis and cell division.The experimental approach consisted of controlling the rate of phosphate uptake by varying the phosphate concentration in the medium. Kinetic experiments showed that phosphate uptake in both growing and quiescent cells was partly accounted for by simple diffusion as well as carrier-mediated uptake. In fact, diffusion of phosphate into the growing cells was 2.5-fold greater than in the quiescent cells.When phosphate uptake was measured in 3T3 cells plated at different initial densities, we found an inverse relationship between phosphate uptake and cell density, showing that phosphate uptake was correlated with growth rate and did not decline simply as a consequence of time in culture.Measurements of phosphate demonstrated that the lowered rate of phosphate uptake by quiescent cells was not due merely to a reduction of phosphate in the medium. To check the possibility that release of a previously described transport inhibitor might account for the decline in phosphate uptake observed as cells grow to quiescence, we removed media from growing and non-growing cultures and tested its ability to support phosphate uptake. We found that the medium from growing cultures supported a higher rate of phosphate uptake than the medium from the quiescent cultures did, indicating that a transport inhibitor was being released. In addition, we found that the amount of inhibitor released was proportional to the concentration of phosphate in the medium.To directly determine if the decline in phosphate uptake was a key event in the decline in DNA synthesis as cells grew to quiescence, we switched growing cultures to a medium with low phosphate immediately after cell attachment. This lowered the rate of phosphate uptake to a level below that of quiescent cells grown in the usual concentration of phosphate. This was done for 3T3, Polyoma virus-transformed 3T3, human diploid foreskin, and secondary chick embryo cells. Measurements of DNA synthesis and cell number showed that this lowered rate of phosphate uptake had virtually no effect on cell growth, directly demonstrating that the decline in phosphate uptake observed during growth to confluency was not causing the decline in DNA synthesis. In addition, measurements of intracellular phosphate pool size showed that changes in phosphate uptake were not directly paralleled by changes in intracellular phosphate pool size, and that intracellular phosphate pool size was not regulating DNA synthesis or cell division during growth to quiescence.
    Additional Material: 9 Ill.
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  • 194
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The 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 expressed.
    Additional Material: 8 Ill.
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  • 195
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The 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 leukocytes.
    Additional Material: 2 Ill.
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  • 196
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    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 92 (1977), S. 203-207 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In vitro moocyte-macrophage colony-forming cells (CFC) have been detected in the thymus (30/106 cells) 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 monocyte-macrophages.
    Additional Material: 3 Ill.
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  • 197
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 92 (1977), S. 233-239 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Thrombin 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 F2α does not increase the initial growth rate of these cells but increases significantly the final cell density of these cultures.
    Additional Material: 4 Ill.
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  • 198
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The proliferative activity of diploid human WI-38 cells in sparse cultures depends on the extracellular concentration of free (or physiologically available) calcium, and cultivation in a medium having a calcium concentration of 0.1 mM or less gradually, but reversibly, arrest their proliferative development in the prereplicative (G1) phase of the cell cycle. Calcium's proliferative control of this cell type is eliminated by proliferative and morphological transformation by the oncogenic SV-40 virus, and the proliferative activity of SV-WI-38 cells in sparse cultures is unaffected by variation of the extracellular free calcium concentration between 0.00 and 1.25 mM.
    Additional Material: 4 Ill.
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  • 199
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    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 92 (1977), S. 285-291 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The activities of pyruvate carboxylase and phosphoenolpyruvate carboxykinase were measured in cultured human fibroblasts. Considerable variation was observed in strains derived from different individuals. The activities of both enzymes throughout the culture cycle were measured in two strains. In these strains the specific activities of the enzymes increased during log phase and remained constant during the stationary phase. However, one cell strain exhibited a high activity of pyruvate carboxylase which remained unchanged throughout the culture cycle, suggesting that this enzyme may be regulated differently in different strains of cultured human cells. Familial studies suggest that the observed variations in pyruvate carboxylase activity may be due to a genetic polymorphism.
    Additional Material: 2 Ill.
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  • 200
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mice of the C3H/HeJ strain exhibit low inflammatory and immunological responses to certain bacterial lipopolysaccharide (LPS) preparations. Lymphocytes from C3H/HeJ mice also show defective LPS-induced mitogenesis. We tested the colony stimulating activity (CSA) response of C3H/HeJ mice. As controls we used mice of the congenic C3HeB/FeJ strain, which are good responders to LPS. Serum was obtained three hours after intravenous administration of LPS. Serum CSA was determined in agar cultures of bone marrow cells from AKR mice. The serum CSA response of C3H/HeJ to 10 μg LPS was approximately 8-fold lower than that of control C3HeB/FeJ mice. In contrast, both strains showed similar serum CSA-induced by Poly I:poly C. Peritoneal macrophage cultures were also incubated with 0.1-10.0 μg LPS and culture media assayed for CSA. The response of C3H/HeJ macrophages was about 6-fold lower than that of macrophages obtained from the control mice. The results show that the lower responsiveness of C3H/HeJ mice to LPS also extends to the production of CSA. The in vitro findings indicate that the postulated defect in the LPS receptor of B lymphocytes may also be present on macrophages.
    Additional Material: 1 Ill.
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