Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| activity of citrinin metabolized by rat and human microsome fractions in clastogenicity and sce assays on chinese hamster v79-e cells. | the mycotoxin citrinin is a potent inducer of chromosomal aberrations in the clastogenicity assay on v79-e cells when metabolized by rat and human liver microsomes. rat and human liver microsomes, standardized on protein content, activate citrinin at equal levels. 5 x 10(-4) m citrinin induces complex translocations in a high frequency as well as defects of chromosomal coiling. higher concentrations are cytotoxic, lower ones are almost inactive. after metabolization of mycotoxin by rat-kidney mi ... | 1979 | 481457 |
| the effect of a tumor promotor, 12-o-tetradecanoyl-phorbol-13-acetate (tpa), on sister-chromatid exchange formation in cultured chinese hamster cells. | the tumor promoter 12-o-tetradecanoyl-phorbol-13-acetate (tpa) does not increase the sister-chromatid exchange (sce) frequency in either chinese hamster ovary (cho) or lung (v 79) cells which are cultured in the presence of 5-bromodeoxyuridine. moreover, tpa does not alter the induction of sces in cho cells by mitomycin c during the first 3 cycles following addition of the alkylating agent. these sce induction data do not by themselves support the hypothesis that tumor promotion by tpa depends o ... | 1979 | 481459 |
| the effect of aphidicolin on adenovirus dna synthesis. | aphidicolin inhibits adenovirus dna replication in hela cells and in a cell-free, infected, nuclear extract in which viral dna is elongated. the compound inhibits alpha dna polymerase, extensively purified from hela cells, but has little or no effect on the beta or gamma dna polymerases similarly purified. aphidicolin does not affect thymidine uptake by cells nor does synthesis as it also inhibits dna replication in uninfected cells. the inhibition by aphidicolin is reversible if the drug is rem ... | 1979 | 482131 |
| biochemical genetics of chinese hamster cell mutants with deviant purine metabolism: isolation and characterization of a mutant deficient in the activity of phosphoribosylaminoimidazole synthetase. | a new purine-requiring mutant of chinese hamster ovary cells (cho-kl) is described. this mutant, ade-g, grows on aminoimidazole carboxamide, hypoxanthine, or adenine. it complements all eight of our other previously described ade- mutants. biochemical analysis of de novo purine synthesis in whole cells suggests that ade-g is capable of the first four reactions of de novo purine biosynthesis and that it synthesizes and accumulates phosphoribosylformylglycinamidine (fgam). direct enzyme assay in c ... | 1979 | 483121 |
| respiration-deficient chinese hamster cell mutants: genetic characterization. | we present here genetic experiments with a series of chinese hamster cell mutants defective in oxidative energy metabolism. the mutations were all shown to be recessive in intraspecies hybrids. thirty-five mutants were sorted into eight complementation groups, but one of these mutants failed to complement representatives of two distinct complementation groups. the possibility was raised that this is a cell carrying two mutations or a deletion. because of the greatly different frequencies with wh ... | 1979 | 483122 |
| characterization of naturally occurring auxotrophic mammalian cells. | in a previous study, several cultured cell lines were detected which are naturally occurring auxotrophs. in this investigation, the enzyme deficienceis involved are described. it is demonstrated that the chinese hamster cell lines cho(k1), yh21, rjk-36, and chw-1102 are deficient in cystathionase and argininosuccinate synthetase. in addition, cho (k1) and chw-1102 were found to lack argininosuccinate lyase. chw-1102 cells were also found to be unable to proliferate in medium containing branched- ... | 1979 | 483124 |
| [variability of chinese hamster clones in resistance to 8-azaguanine]. | the stability of the 8-azaguanine resistance marker during the number of cell generations has been analyzed for 63 clones of chinese hamster cells. the resistant clones analyzed were spontaneous or induced after the treatment of parent cells by 5-budr, ems, or histone h1. the clones have revealed different levels of ag-resistance as well as different ability to maintain the above level, under the cultivation in the drug-free medium. subclones, isolated from the unstable clone, were found to be d ... | 1979 | 483396 |
| misonidazole and mtdq in combination: cytotoxic and radiosensitizing properties in hypoxic mammalian cells. | a combination of misonidazole and mtdq (6,6'-methylene-bis-2,2,4 trimethyl-1,2-dihydroquinoline) has been tested for its radiation-sensitizing properties and cytotoxicity, using chinese hamster v79 cells cultured in vitro. both compounds sensitize hypoxic cells to the effects of x-rays, and when used in combination their sensitizing properties are additive. by contrast, the presence of mtdq completely inhibits the cytotoxicity that misonidazole exhibits towards hypoxic cells. these experiments s ... | 1979 | 486306 |
| comparison of complexity and diversity of polyadenylated polysomal and informosomal messenger ribonucleic acid from chinese hamster cells. | the sequence complexity and relative abundance of cytoplasmic polyadenylated polysomal (ribosome-bound) mrna and cytoplasmic polyadenylated informosomal (ribosome-free) mrna were analyzed in exponentially growing chinese hamster cells (line cho) using the technique of cdna hybridization to excess poly(a)+ mrna. polysomal and informosomal mrnas had similar complexities ( approximately 8300 mrna species), but both the fraction of mrna and the number of sequences comprising the mrna abundance class ... | 1979 | 486422 |
| production of mrna in chinese hamster cells: relationship of the rate of synthesis to the cytoplasmic concentration of nine specific mrna sequences. | we constructed cloned dna sequences complementary to unselected mrnas [poly(a)+ cytoplasmic rna] from chinese hamster ovary cells and used them in rna:dna hybridization experiments. each cloned dna hybridized a single mrna from 1.3-3.5 kb in length. the relative rates of labeling (transcription rates) of nuclear rna complementary to each individual dna segment varied approximately 10 fold. the relative cytoplasmic concentration of the same specific rna sequences in the mrna after an equilibrium ... | 1979 | 487428 |
| binding of concanavalin a to chinese hamster ovary cells after storage in liquid nitrogen. | 1979 | 487848 | |
| difference between diploid and aneuploid chinese hamster cells in replication at mid-s-phase. | following partial synchronization of the heteroploid chinese hamster cell line v-79 and of normal diploid lung fibroblasts of the chinese hamster in culture, their dna replication during s-phase aws compared by means of a brdu-incorporation/thymidine pulse technique and hoechst-giemsa differential staining of metaphase chromosomes. this comparison indirectly shows the s-phase of the heteroploid cells of v-79 to be 2 h shorter than the diploid cell s-phase. when the thymidine pulse is applied to ... | 1979 | 487906 |
| mutations of chinese hamster somatic cells from 2-deoxygalactose sensitivity to resistance. | in chinese hamster somatic cells, the spontaneous change of phenotype from 2-deoxygalactose sensitivity to resistance was studied using fluctuation test experiments à la luria and delbrück (1943) for four chinese hamster cell strains derived from v79. the results are consistent with true mutational events. the mutation rates are in the range of 1 to 3.5 x 10(-5) per cell per generation. the relationship between the 2-deoxyglactose resistance and the galactokinase markers is discussed. | 1979 | 488705 |
| cycloheximide-resistance in chinese hamster ovary cells and human fibroblast cells. cytogenetic and biochemical characterization. | cycloheximide(chm)-resistant mutant chinese hamster ovary (cho) and human cells were induced with n-nitrosomethylurea (nmu) and ethyl methanesulfonate (ems); the mutants were viable and showed unlimited growth in the presence of chm (7 x 10(-7) m), whereas this concentration inhibits protein synthesis in vivo as well as in vitro. no numerical or structural chromosomal aberrations were found in the mutant cells. in vitro analysis shows that the ribosomes confer resistance against cycloheximide. | 1979 | 489015 |
| a quantitative comparison of the mutagenicity of carcinogenic polycyclic hydrocarbon derivatives in cultured mammalian cells. | the mutagenicity of a series of reactive polycyclic hydrocarbon derivatives has been studied using chinese hamster (v79) cells in culture and, as a mutational marker, resistance to the purine analogue 8-azaguanine. the compounds were compared by relating mutation frequency to the dose applied (mutagenic effectiveness) to induced cytotoxicity (mutagenic efficiency) and to the extent of reaction of the hydrocarbon with dna (absolute mutagenic efficiency). in each case anti-benzo(alpha)pyrene (bp)- ... | 1979 | 489163 |
| chromosome breaking activity of human feces and its enhancement by transition metals. | chloroform-methanol extracts from human fecal samples were found to contain compounds which induce chromosome aberrations in chinese hamster ovary cells. the induction of chromosome aberrations is stimulated by cu2+ or mn2+ and inhibited by fe2+ or fe3+. addition of catalase to the fecal extract or the mixture of fecal extract and mn2+ reduced the frequency of chromosome aberrations. these properties are indicative of hydroxyradical producing agents. | 1979 | 489168 |
| the biosynthesis of the major lipid-linked oligosaccharide of chinese hamster ovary cells occurs by the ordered addition of mannose residues. | 1979 | 489594 | |
| correlation between cell cycle duration and rna content. | the metachromatic fluorochrome acridine orange was used to differentially stain dna and rna in chinese hamster ovary (cho) cells and in mitogen-stimulated human lymphocytes during their progression through the cell cycle. green and red fluorescence of individual cells, representing cellular dna and rna, respectively, was measured by flow cytometry. cho cells were synchronized by selective detachment at mitosis. their rate of progression through g1 and subsequently through s phase correlated with ... | 1979 | 489667 |
| cadmium-induced alterations in rna metabolism in cultures of chinese hamster cells sensitive to and resistant to the cytotoxic effects of cadmium. | a variant population (cdr) of cultured chinese hamster cells (line cho) was derived that is more than 100 times as resistant to the cytotoxic effects of cd2+ than is the parent population. the effects on rna metabolism of exposure to sublethal concentrations of cd2+ were studied in cho and cdr. exposure to 2 x 10(-7) m cdcl2 for 24 h resulted in increased polysome content (1.2 times) and increased uridine or adenosine incorporation into heterogeneous nuclear rna (1.2-1.4 times) and messenger rna ... | 1979 | 490682 |
| a partial characterization of dna fragments protected from nuclease degradation in histone depleted metaphase chromosomes of the chinese hamster. | a small proportion (0.1-0.5%) of the total dna content of native chinese hamster metaphase chromosomes is protected from nucleolytic degradation following the removal of histones by extraction with either 0.2 n hcl or 2 m nacl, and remains attached to the nonhistone protein core. acid extraction followed by dnase i digestion leads to small fragments of 10-30 bases. salt extraction followed by micrococcal nuclease digestion gives approx. 140 b.p. fragments which are undistinguishable in size from ... | 1979 | 493144 |
| elimination of metabolic cooperation in chinese hamster cells by a tumor promoter. | wild-type chinese hamster v79 cells (6-thioguanine-sensitive) reduce the recovery of 6-thioguanine-resistant cells when they are cultured together at high densities, through a form of intercellular communication (metabolic cooperation). cooperation is inhibited by 12-o-tetradecanoyl phorbol-13-acetate, rescuing the 6-thioguanine-resistant cells. these results may be useful in the study of an aspect of the mechanism of tumor promotion and in assaying for promoters. | 1979 | 493994 |
| respiration-deficient chinese hamster cell mutants: biochemical characterization. | we have previously classified 35 of our respiration-deficient mutants into seven complementation groups and one "overlapping" mutant which does not complement mutants from groups i and ii. in this paper we report on the biochemical characterization of representatives of complementation groups i, ii, vii, and the "overlapping" mutant. we show that these mutants all have a defect in complex i of the electron-transport chain. the general features of these mutants are: (1) a low rate of o2 consumpti ... | 1979 | 494059 |
| characterization of the diphtheria toxin-resistance system in chinese hamster ovary cells. | variations in two general classes of diphtheria toxin-resistant mutants which may be selected from chinese hamster ovary (ch0-k1) cells and the conditions for their selection are described. the resistance of class i mutants can be overcome with increasing concentrations of toxin. their entire complement of ef-2 is susceptible to adp-ribosylation by toxin. class i includes those strains in which resistance resides at the level of the plasma membrane. the resistance of class ii, translational, mut ... | 1979 | 494060 |
| an ultrastructural study of morphogenesis of fibrogranular complex and centriole in ductuli efferentes of chinese hamster. | an ultrastructural study of ciliated epithelial cells in the ductuli efferentes of young and adult hamsters has revealed that these cells possess dense granules, dense granule clusters, dense bodies and fibrogranular complexes as reservoirs or precursors for ciliogenesis. the dense granules are first seen in the centrosomal region. later, many dense granules and dense granule clusters appear in the apical portion of the epithelial cells where, subsequently, dense bodies are also found. finally, ... | 1979 | 494233 |
| enhancement of thermal killing by polyamines. iv. effects of heat and spermine on protein synthesis and ornithine decarboxylase activity. | protein synthesis is shown to be very heat-sensitive in chinese hamster cells. it is shut off completely following 15-20 min at 42 degrees c whereas rna and dna syntheses are affected only after much longer exposure times. cells recover from inhibition of protein synthesis upon transfer to 37 degrees c. the degree of recovery is inversely related to the duration of heat exposure and it fits cell survival quantitatively. cells which become temporarily heat-resistant by prior heat-treatment, are a ... | 1979 | 498061 |
| thermosensitization by sulfhydryl compounds of exponentially growing chinese hamster cells. | the effect of various sulfhydryl compounds on the survival of exponentially growing monolayer cultures of chinese hamster cells (ha1) heated to temperatures of 37-43 degrees was examined. concentrations of cysteamine which were nontoxic or minimally toxic at room temperature or 37 degrees became increasingly toxic at elevated temperatures, greatly potentiating the killing produced by heat alone in the absence of cysteamine. this enhancement of hyperthermia-induced cell killing increased with inc ... | 1979 | 498092 |
| retinol inhibition of ornithine decarboxylase induction and g1 progression in chinese hamster ovary cells. | 1979 | 498118 | |
| effects of caffeine on purine metabolism and ultraviolet light-induced lethality in cultured mammalian cells. | caffeine, at doses which enhance the killing action of ultraviolet light, inhibits both de novo synthesis and the utilization of exogenous purines in cultured cho-k1, a chinese hamster ovary cell line. the decrease in synthesis was measured as inhibition by caffeine of the accumulation of phosphoribosylformylglycineamide or of phosphoribosylaminoimidazolecarboxamide, the fourth and ninth intermediates, respectively, in the de novo biosynthetic pathway. the effect is dose dependent, with a caffei ... | 1979 | 498124 |
| sperm-cell multinucleates in chinese hamster ovary cells penetrated with rat spermatozoa. | 1979 | 498198 | |
| mutants of chinese hamster ovary (cho) cells with altered colcemid-binding affinity. | clones of cho cells stably resistant to colcemid have been isolated in the presence of the nonionic detergent tween 80 after mutagen treatment. successive single-step selections for increasing resistance were performed resulting in lines after three selection steps about 10 fold more resistant to colcemid than the parental cells. three observations indicate that these colcemid-resistant (cmr) mutants are different from the colchicine-resistant permeability mutants isolated previously. first, the ... | 1983 | 498276 |
| two-dimensional analysis of proteins associated with heterogenous nuclear rna in various animal cell lines. | the protein complement of heterogenous nuclear rna . protein particles from human hela, mouse l and chinese hamster (cho) cells has been analysed by two-dimensional gel electrophoresis using the two techniques described by o'farrell [j. biol. chem. (1975) 250, 4007--4021 and cell (1977) 12, 1133--1142]. over a hundred individual spots habe been reproducibly detected both l-[35s]methionine. large similarities, especially in the 25 000--40 000 mr cluster of basic protein, were found among these th ... | 1979 | 499201 |
| activity of both mouse and chinese hamster ribosomal rna genes in somatic cell hybrids. | 1979 | 499371 | |
| possible mutagenic activity of saccharin. | a mutagenic effect of saccharin in chinese hamsters, using the in vivo sce test, was observed when massive overdoses were administered; cyclamate was not mutagenic. | 1979 | 499424 |
| inhibition of cholesterol biosynthesis in chinese hamster ovary cells by 4,4,10 beta-trimethyl-trans-decal-3 beta-ol. a specific 2,3-oxidosqualene cyclase inhibitor. | 1998 | 500643 | |
| purification of p-glycoprotein from plasma membrane vesicles of chinese hamster ovary cell mutants with reduced colchicine permeability. | 1979 | 500733 | |
| induction of ouabain-resistant mutation and sister chromatid exchanges in chinese hamster cells with chemical carcinogens mediated by human pulmonary macrophages. | pulmonary macrophages (pam) metabolically activated benzo[a]pyrene [b(a)p] and its proximate carcinogenic metabolite, (+/-)trans 7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene (7,8-diol), to ultimate mutagens that were detected in cocultivated chinese hamster v79 cells. increases in the frequency of ouabainresistant (o(r)) mutations and sister chromatid exchanges were found in v79 cells only when they were cocultivated with both pam and the chemical procarcinogens. 7,8-diol caused higher frequencies of ... | 1979 | 500808 |
| enhancement of excision-repair efficiency by conditioned medium from density-inhibited cultures in v79 chinese hamster cells: evidence for excision repair as an error-free repair process. | conditioned medium from density-inhibited v79 chinese hamster cell cultures, given as a post-treatment to uv-irradiated homologous cells, was demonstrated to reduce the lethal action of ultraviolet light by temporarily blocking dna replication. since the increased survival was not affected by various non-toxic concentrations of caffeine, such protective effect would be attributable to the prolonged intervention of excision repair before dna replication during the post-treatment period. the influ ... | 1979 | 503101 |
| relationship between sister chromatid exchange and mutagenicity, toxicity and dna damage. | reciprocal exchanges of dna in sister chromatids (sces) are induced by various carcinogens and mutagens, although the quantitative relationship between the number of mutations and sces induced varies among chemicals. nevertheless, the analysis of sce production by various agents is often proposed as a sensitive and quantitative assay for genetic damage of the sort leading to mutation and cancer. in v-79 chinese hamster cells we have been measuring dna damage by alkaline elution, mutation inducti ... | 1979 | 503206 |
| anomalous dose-response characteristics induced by caffeine in ultraviolet-irradiated v79--79 chinese hamster cells. | 1979 | 504354 | |
| cell survival over the depth profile after irradiation with a negative pion beam. | the colony-forming ability of chinese hamster fibroblast cells in vitro has been investigated throughout the depth dose profile of a negative pion beam. in the peak and 2 cm beyond, the rbe for macroclones (more than 50 cells per clone) was 1.3 and in the plateau region 0.8--1.0. all of the microclones (2-49 cells per clone) were observed as well. the rbe values are the same for peak and somewhat higher for plateau and post peak than found in cell survival studies referring to macroclones. | 1979 | 504556 |
| biological effects of negative pions in monolayers and spheroids of chinese hamster cells. | the therapeutic value of pion irradiation was critically challenged by examining, in a cell culture system, various parameters of biological significance such as relative biological efficiency (rbe), oxygen enhancement ratio (oer), dna-break formation, changes in cell cycle kinetics and regrowth. in all parameters, pions were superior to conventional low-let radiation. | 1979 | 504557 |
| chromatid breaks induced in chinese hamster cells by low doses (12--100 rad) of pi--mesons. | monolayer cultures of the fibroblast-like chinese hamster cell-line 19/1 were irradiated in the g2-phase of the cell cycle by pi--mesons (6 rad/min peak-pion dose rate). frequencies of induced single- and isochromatid breaks, acentric fragments and interchanges were compared with data obtained from 140 kv x-rays. the rbe-values were for the pion dose peak between 0.8--1.2 and for the pion dose plateau 0.5--0.9. whereas for single chromatid breaks there was no significant difference between x-ray ... | 1979 | 504558 |
| differential radiosensitivity of two mammalian cell lines after hyperthermic pretreatment. | hyperthermia in combination with 60co-gamma-therapy not only increases the radiosensitivity of mammalian cells, it also can create a greater selectivity between individual cell populations. tw established chinese hamster cell lines (v79 and b14f28) showed a similar radiosensitivity at 37 degrees c, but exhibited a marked difference in their response to 60co-gamma-rays when they were pretreated with mild hyperthermia (1 hour at 42 degrees c): about 50% of each cell type survived a dose of 400 rad ... | 1979 | 505472 |
| 86rb+ fluxes in chinese hamster ovary cells as a function of membrane cholesterol content. | steady-state fluxes of 86rb+ (as a tracer for k+) were measured in chinese hamster ovary cells (cho-k1) and a mutant (cr1) defective in the regulation of cholesterol biosynthesis; the membrane cholesterol content of this mutant was varied by growing it on a range of cholesterol supplements to lipid-free medium (sinensky, m. (1978) proc. natl. acad. sci. u.s. 75, 1247--1249). analogous to previous findings in ascites tumor cells, 86rb+ influx in the parent strain was differentiated into a ouabain ... | 1979 | 508750 |
| precursor-product relationships between thymidine nucleotides and dna in mammalian cells. ii. studies with dtdp and dttp on cells partially lysed by brij-58. | cells from chinese hamster ovary cell cultures were partially lysed with brij-58 and incubated in a reaction mixture containing deoxyribonucleoside triphosphates and permitting semiconservative dna replication. the reaction mixture was supplemented with [3h]dttp and [14c]dtdp or, alternatively, with [14c]dttp and [3h]dtdp, and at different times, 3h and 14c specific activities of dttp and dtdp, as well as 3h/14c ratios in dna were determined. isotope ratios in dna were in good agreement with tho ... | 1979 | 508757 |
| effects of various oxygenated sterols on cellular sterol biosynthesis in chinese hamster lung cells resistant to 25-hydroxycholesterol. | the effects of a wide variety of oxygenated sterols upon sterol biosynthesis and hydroxymethylglutaryl-coa reductase (mevalonate: nadp+ oxidoreductase (coa-acylating), ec 1.1.1.34) activity in a wild-type clone and in a 25-hydroxycholesterol-resistant clone of chinese hamster lung (dede) cells are described. derivatives of cholesterol which were oxygenated in the 6, 7 or 15 positions of the sterol nucleus or in the 20, 22, 24 or 25 positions of the sterol side chain were shown to be potent inhib ... | 1979 | 508785 |
| relationship between dna alkylation and specific-locus mutation induction by n-methyl- and n-ethyl-n-nitrosourea in cultured chinese hamster ovary cells (cho/hgprt system). | chinese hamster ovary (cho) cells in culture were utilized to determine the cytotoxicity, specific-locus mutation induction, and dna alkylation which result from treatment of the cells with a range of concentrations of n-methyl-n-nitrosourea (mnu) or n-ethyl-n-nitrosourea (enu). with [3h]mnu over the concentration range 0.43--13.7 mm, methylation of dna was found to increase linearly, with a mean value of 56.7 pmol residue per mumol nucleoside per mm. with [1-3h]enu over the concentration range ... | 1979 | 509687 |
| sister chromatid exchanges induced in cultured mammalian cells by chromate. | chromate compounds induced sister chromatoid exchanges (sces) and chromosome aberrations in cultured mammalian cells. similar increases in sce frequency were observed in human fibroblasts exposed to the compounds k2cr2o7 and k2cro4. marked increases in sce frequency in cells exposed to chromate for a 48-h period were detected at concentrations between 10(-7) and 10(-6) m. chromosome aberrations (primarily chromatid breaks) were also produced in human cells exposed to k2cro4 at concentrations bet ... | 1979 | 509691 |
| effects of styrene oxide on chromosome aberrations, sister chromatid exchange and hepatic drug biotransformation in chinese hamsters in vivo. | in vivo inhalation exposure to styrene oxide (25, 50, 75 and 100 ppm) for 2, 4 or 20 days (25 ppm only) had no effects on chromosomal aberration rates or sister chromatid exchange (sce) frequencies (brdu/labelling performed in vitro) in the bone marrow cells of chinese hamsters. the only positive response in aberration frequency was obtained when styrene oxide was injected in lethal concentration (500 mg/kg body weight, i.p.) into the animal. one animal out of six showed slightly elevated sce va ... | 1979 | 509693 |
| a cadmium-resistant variant of the chinese hamster (cho) cell with increased metallothionein induction capacity. | 1979 | 510415 | |
| deficiency of arginine and lysine causes increase in the frequency of sister chromatid exchanges. | an increase in the rate of sister chromatid exchanges (sce) was found when v79 chinese hamster cells were exposed to increasingly severe degrees of arginine and lysine deficiency. the data suggest a possible function of chromosomal proteins, and of histones in particular, in the maintenance of the low normal rate of sce. | 1979 | 511161 |
| culture of adult rat lung cells: benzo(a)pyrene metabolism and mutagenesis. | a method is described for obtaining and culturing large numbers of lung cells from normal adult male rats. the lungs were perfused in situ to remove blood cells and then perfused via the trachea with a trypsin-collagenase solution to initiate tissue digestion. the tissue was further digested in the enzyme solution and approximately 2 x 10(8) viable lung cells were obtained per animal. primary cultures contained a mixed cell population. through eight subcultures about 70% of the cell population p ... | 1979 | 511205 |
| intercellular adhesion as a function of the cell cycle traverse. | intercellular adhesion is assumed to play an important role in a multitude of biological phenomena governing cellular behavior. the rate of intercellular adhesion as a function of the cell cycle traverse has been investigated using, in the monolayer assay, synchronized chinese hamster ovary-k1 cells. results obtained demonstrate that cells in g1 adhere to g1 cells at twice the rate that s cells adhere to each other. g1 cells adhere to s cells at an intermediate rate. the additive adhesiveness se ... | 1979 | 511931 |
| reversible inactivation of autosomal alleles in chinese hamster cells. | evidence is presented which suggests that a cho-derived thymidine kinase (tk) heterozygote, ts201, can reversibly inactivate the wild type tk allele, and that this event may result in simultaneous inactivation of a linked allele, galactokinase (glk). the clone ts201 was isolated as a revertant of a stable tk- 5-bromodeoxyuridine (brdu)-resistant mutant of cho. the reacquired tk activity differed from that of the wild type with respect to km and heat resistance, supporting the contention that ts2 ... | 1979 | 511955 |
| proliferation of lung and airway cells induced by nitrogen dioxide. | proliferation of lung cells of chinese hamsters was examined in several regions of the lung parenchyma and ciliated airway epithelium after a 24-h exposure to 28.2 mg/m3 (15 ppm) nitrogen dioxide (no2). label was retained 3 wk after the injection of [3h]thymidine, and autoradiographic methods were used to localize the site of retention. by 24 h after administration of [3h]thymidine, parenchymal areas, exclusive of airways, showed an increased labeling index, indicative of cell death and replacem ... | 1979 | 513156 |
| mutagenicity of metal cations in cultured cells from chinese hamster. | the mutations at the hypoxanthine-guanine phosphoribosyl transferase (hgprtase) locus in chinese hamster v79 cells induced by metal cations were examined by the development of resistance to 8-azaguanine (8ag). the spontaneous frequency of 8ag resistance was 5.8 per 10(6) cells, and the frequency was enhanced to 2-6 times that of the control by treatment of cells with the chlorides of beryllium and manganese. about 75% of 8ag-resistant colonies were sensitive to amethopterin, and 86% of the resis ... | 1979 | 514305 |
| amosite, chrysotile and crocidolite asbestos are mutagenic in chinese hamster lung cells. | chinese hamster lung cells cultured in the presence of amosite, chrysotile or crocidolite displayed inhibition of cell growth. phagocytosis of asbestos by cells was observed. amosite and chrysotile appeared to be twice as toxic as crocidolite based on an equal weight/volume basis. induction of 6-thioguanine resistance was studied. after treatment at 10 microgram/cm2 for 24 h, and with a 48-h expression time, numerically the cells did not change significantly from 6-thioguanine-sensitive to 6-thi ... | 1979 | 514306 |
| modification by cysteamine of ultrasound lethality to chinese hamster v-79 cells. | 1979 | 515353 | |
| induction of sister chromatid exchanges in chinese hamster cells by the reducing agents bisulfite and ascorbic acid. | sister chromatid exchanges (sces) are induced in chinese hamster cells by a 2--3-h exposure to ascorbic acid or bisulfite in the concentration range 10(-4)--10(-2) m. this activity of these 2 chemicals was intensified when cell cultures were exposed to each agent for longer time periods (24 h). the divalent metal cation, cu2+, was effective in potentiating the ability of ascorbic acid to induce sces and toxicity, suggesting that the autooxidation of ascorbic acid was involved in this action. the ... | 2013 | 516076 |
| detection of small amounts of human dna in human-rodent hybrids. | a method of measuring semi-quantitatively small amounts of human dna in irradiated human x mouse and irradiated human x chinese-hamster somatic cell hybrids is described. one method uses molecular hybridization of cell dna bound to nitrocellulose filters with a crna probe to cot 0--1 human dna. alternatively hybrid cell dna is reassociated in solution with a cot 0--1 fraction of nick-translated human dna. formamide buffers give specificity to the reaction. the detection limit of the filter metho ... | 1979 | 521473 |
| dna crosslinking, sister-chromatid exchange and specific-locus mutations. | chinese hamster ovary cells were treated with the dna-crosslinking chemicals, mitomycin c (mmc) and porfiromycin (por), and their monofunctional derivative decarbamoyl mitomycin c (dcmmc). after exposure, the cells were studied for the induction of sister-chromatid exchanges (sces) and mutations at the hypoxanthine phosphoribosyltransferase and adenine phosphoribosyltransferase loci. the frequency of sces varied significantly in successive sampling intervals, requiring the weighting of each inte ... | 1979 | 522865 |
| a comparison of cytotoxicity, ouabain-resistant mutation, sister-chromatid exchanges, and nascent dna synthesis in chinese hamster cells treated with dihydrodiol epoxide derivatives of benzo[a]pyrene. | chinese hamster v79 cells were treated with either (+/-)-7 beta, 8 alpha-dihydroxy-9 alpha, 10 alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (b[a]p-diol epoxide i) or (+/-)-7 beta,8 alpha-dihydroxy-9 beta,10 beta-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (b[a]p-diol epoxide ii) and the nascent dna was labeled with [me-3h]thymidine. the cells were harvested for determination of cytotoxicity, sister-chromatid exchanges (sce), ouabain-resistant (or) mutations and the size of newly synthesized daughte ... | 1979 | 522875 |
| the effect of caffeine on cytotoxicity, mutagenesis, and sister-chromatid exchanges in chinese hamster cells treated with dihydrodiol epoxide derivatives of benzo[a]pyrene. | the effect of caffeine on chinese hamster v79 cells after treatment with the highly mutagenic (+/-)-7 beta,8 alpha-dihydroxy-9 alpha, 10 alpha-7,8,9,10-tetrahydrobenzo[a]pyrene, and the weaker mutagen (+/-)-7 beta,8 alpha-dihydroxy-9 beta,10 beta-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene, b[a]p-deiol-epoxide ii, was studied at both the biological and molecular levels. caffeine, at nontoxic dose levels, caused a synergistic reduction in cell survival induced by both isomers and also inhibited dna e ... | 1979 | 522876 |
| cytotoxicity and mutagenicity of alkylating agents in cultured mammalian cells (cho/hgprt system): mutagen treatment in the presence or absence of serum. | cytotoxicity and mutation induction at the hypoxanthine-guanine phosphoribosyl transferase locus in chinese hamster ovary cells (cho/hgprt system) were measured for a range of concentrations of 6 alkylating agents [methyl and ethyl methanesulfonate (mms, ems), n-methyl- and n-ethyl-n'-nitro-n-nitrosoguanidine (mnng, enng), and methyl- and ethyl-nitrosourea (mnu, enu)] to determine the effect of the presence or absence of serum during the time of mutagen treatment. cultures were treated with the ... | 2004 | 522878 |
| induction of sister-chromatid exchanges in chinese hamster ovary cells by thiol and hydrazine compoudns. | cysteine, cysteamine and glutathione all induce sister-chromatid exchanges (sces) in chinese hamster ovary (cho) cells when applied to cell cultures at concentrations between 10(-4) and 10(-2) m. acute exposure of cells th thiol compound for a period of 2--3 h resulted in a unique dose--response relationship in each instance. this consisted of two peak sce frequencies, one at either extreme of the concentration range. each peak corresponded to a 2--3-fold increase over the spontaneous level. a c ... | 1979 | 522883 |
| nucleolar organizing regions of normal chinese hamster and chw cell line chromosomes. | the chromosome preparations from fibroblasts of normal male and female chinese hamsters and the cell line chw were stained with agno3. the silver stain was usually localized at the telomeres of autosomes. the marker chromosome m1 in the chw cell line has ag-nor near the centre of the long arm, which indicates that either the long arms of two number 5 chromosomes fused at the telomeres or the intact telomeric region of one chromosome fused with one with a deleted telomere. the variation of ag-nor ... | 1979 | 527380 |
| adriamycin uptake in v79 and adriamycin resistant chinese hamster cells. | 1979 | 528269 | |
| survival and kinetics of chinese hamster ovary cell subpopulations induced by adriamycin and radiation. | 1979 | 528270 | |
| the mechanism of action of cis-dichloro-bis (isopropylamine) trans dihydroxyplatinum iv (chip) on chinese hamster and c3h mouse tumor cells and its interaction with x-irradiation. | 1979 | 528286 | |
| different chinese hamster cell lines express a g1 period for different reasons. | previous studies from our laboratory have shown that the absence of g1(g1-condition) in two lines of chinese hamster cells is dominant over the presence of g1(g1+condition) in a variety of intraspecific cell hybrids. g1+ mutants or variants cna be isolated from g1- cells following mutagenesis and selection. these g1+ mutants fall into multiple complementation groups based on their abilities to form g1- cell hybrids with one another. this is evidence that different mutants have g1 intervals for d ... | 1979 | 531733 |
| mutagenicity of polycyclic hydrocarbons iii. monitoring genetic hazards of benz(a)anthracene. | mutagenicity tests (micronucleus test and chromosome aberrations) have been performed with benz (a) anthracene in spermatogonia and bond marrow cells of chinese hamsters and in nmri mice oocytes. mutagenic effects of the polycyclic hydrocarbon could be demonstrated. | 1979 | 532719 |
| inhibition by trioxalen (psoralen) plus near-ultraviolet light of the induction of ornithine decarboxylase in chinese-hamster cells. | trioxalen (trimethylpsoralen) plus near-u.v. light, a potent inhibitor of dna and rna synthesis, inhibits the induction of ornithine decarboxylase in stationary-phase v79 fibroblasts. it does not affect the translation of pre-existing mrna. the method, in view of its high degree of specificity and precise timing, is a better choice for inhibiting rna synthesis than the commonly used chemical inhibitors and precursor analogues. | 1979 | 534483 |
| adaptation of the influenza virus a2-pol 29/69 to the cells of the chinese hamster lung (chl) and to the cells bhk-21. | in the course of research of the possibilities of adapting the influenza virus serotype a 2-pol 29/69 to bhk-21 and chl cells its production was established in the investigated combinations. an indication of virus replication is an increase in infectious and haemagglutination titres within 48 h after infection and gradual increase in haemadsorption. observation of the influence of trypsin (10 microgram/ml) indicates that trypsin increases the capability of viruses to penetrate the cells. the cyt ... | 1979 | 535814 |
| cytotoxicity of glucose analogues in v79 multicell spheroids. | 2-deoxy-d-glucose (2dg) and 5-thio-d-glucose (5tg) are glucose antimetabolites that are known to be selectively toxic to hypoxic cells grown as single cells or as monolayer cultures. these analogues were toxic to chinese hamster v79 cells grown as multicell spheroids even under aerobic conditions. when spheroids, 500- to 600-microns diameter, were exposed to 7.5 mm of these chemicals for 3 days, the number of clonogenic cells per spheroid dropped to 50% for 5-thio-d-glucose and 20% for 2-deoxy-d ... | 2004 | 535913 |
| effects of heat shock on gene expression and subcellular protein distribution in chinese hamster ovary cells. | incubation of chinese hamster ovary (cho) cells for one hour at 43 degrees c results in several obvious changes in protein distribution and protein synthesis. one major protein of the cytoplasm (molecular weight 45,000 daltions), also present as a minor component in the nucleus, rapidly disappeared while several proteins, especially high molecular weight peptides, were induced by heat shock. localization of the proteins in the cytoplasm, extra-nucleolar chromatin and nucleolar bodies has been ca ... | 1979 | 537909 |
| rapid induction of epithelial hyperplasia and lymphoplasmacytosis in the chinese hamster (cricetulus griseus) by mineral and pristane oil. | 2004 | 538262 | |
| cytogenetic effects of antituberculosis antibiotic rifampin on chinese hamster ovary cells. | 1979 | 540994 | |
| selecting interspecific human-mouse and chinese hamster-mouse hybrids using a new half-selection technique with a polyene antibiotic. | interspecific human-mouse and chinese hamster-mouse hybrids were isolated from polyethylene glycol fused cells by a new half-selection technique employing a structurally modified polyene macrolide antibiotic, amphotericin b methyl ester (ame), and hat media. unfused parental cells were killed as a result of innate sensitivity to ame or their genetic deficiency, absence of thymidine kinase (tk-) or hypoxanthine guanine-phosphoribosyl transferase (hgprt-). in contrast, hybrid colonies were isolate ... | 1979 | 541268 |
| isolation and characterization of tunicamycin resistant mutants from chinese hamster ovary cells. | stable clones selected for resistance to tunicamycin (tm) have been isolated from chinese hamster ovary (cho) cells. the tmr phenotype is stable for more than nine months in the absence of the drug. the morphology of tmr mutant varies from epitheloid to abnormally elongate. the mutants do not display cross-resistance for cona but are slightly cross-resistant to pha. biochemically labeled membrane proteins and glycoprotein of vesicular stomatitis virus (vsv) grown in the tmr mutants revealed that ... | 1979 | 541348 |
| hypoxanthine transport by chinese hamster lung fibroblasts: kinetics and inhibition of nucleosides. | 1979 | 543723 | |
| genetic transmission of moloney leukemia virus: mapping of the chromosomal integration site. | mice genetically transmitting the exogenous moloney leukemia virus (balb/mo) have been previously derived. these animals carried one copy of moloney virus dna (m-mulv) in their germ line and transmitted the virus as a single mendelian gene to the next generation. homozygous balb/mo mice were used to genetically map the m-mulv locus. embryo fibroblasts were fused to established chinese hamster cells and somatic cell hybrids were selected. segregation of mouse chromosomal markers in the hybrids wa ... | 1979 | 544367 |
| destruction of bacterial viruses in serum by heat and radiation under conditions that sustain the ability of serum to support growth of cells in suspended culture. | methods for inactivating bacterial viruses in serum were developed through the use of heat and ionizing radiation, and the effects of these treatments on the growth rates of cultured cells were tested. viruses chosen for this study were the radiation-resistant bacteriphage f2 and heat-resistant phage t4. the viabilities of these phages were reduced more than 2 and 4 orders of magnitude, respectively, by a treatment at 60 degrees c for 30 min followed by 420 krads of ionizing radiation. simultane ... | 1979 | 544633 |
| production of monoclonal antibodies against a cell surface concanavalin a binding glycoprotein. | concanavalin a-binding (con-a)-binding cell surface glycoproteins were isolated, via con a-affinity chromatography, from triton x-100-solubilized chinese hamster ovary (cho) cell plasma membranes. the con a binding glycoproteins isolated in this manner displayed a significantly different profile on sodium dodecyl sulfate--polyacrylamide gels than did the triton-soluble surface components, which were not retarded by the con-a-sepharose column. [125i]-con a overlays of the pooled column fractions ... | 1979 | 544930 |
| direct linkage of thrombin to its cell surface receptors in different cell types. | when 125i-thrombin was incubated with foreskin fibroblasts, cervical carcinoma cells or fibrosarcoma cells of human origin, or with secondary chick embryo cells or chinese hamster lung cells, it became directly linked to its cell surface receptors. the thrombin-receptor complex (th-r) was derived exclusively from a pool of 125i-thrombin that had become specifically bound to the cell surface. the linkage was probably covalent, since the complex was resistant to boiling in sodium dodecyl sulfate a ... | 1979 | 544938 |
| somatic cell genetic analysis of transgenome integration. | the site of association of the human transgenome and host murine chromosomes was determined in several subclones of a stable human/mouse transformed cell line. chromosomes were transferred from each of three transformed subclones into chinese hamster recipient cells, and selection was applied for the expression of human transgenome-encoded hprt. a series of trispecific microcell hybrids was isolated and characterized for each subclone. evidence is presented that, within a given transformed subc ... | 1979 | 545718 |
| genetic and adaptive differences in the expression of drug resistance in hybrid cells. | hybrids between chinese hamster cells were isolated and maintained in media that were selective or nonselective for markers present in the parent cells (hgprt and tk deficiencies, respectively). segregation frequencies for resistance to azaguanine (azg), thioguanine (thg), or bromodeoxyuridine (brdu) could be enhanced for some groups of hybrids if the stock cells were maintained under nonselective conditions rather than in hat medium. in these populations the expression of resistance was dominan ... | 2005 | 545725 |
| studies on chinese hamster ovary mutants showing multiple cross-resistance to oxidative phosphorylation inhibitors. | several stable chinese hamster ovary (cho) mutants were selected after ethylmethane sulfonate mutagenesis for resistance to oligomycin, ruatmycin, venturicidin, or antimycin. these mutants shared a number of common properties. they exhibited cross-resistance to those drugs which act on oxidative phosphorylation, irrespective of the structure and site of action of the drug. all the mutants showed a reduced ability to grow in suspension and to reach high saturation densities. they were also unable ... | 2005 | 545726 |
| [an assessement of the in vivo sister chromatid exchange (sce)-test using various cytostatics (author's transl)]. | five cytostatics of different chemical structure and pharmacological action were used on chinese hamsters (bone marrow cells) to test the efficiency and validity of the in vivo sister chromatid exchange (sce)-test as an indicator of mutagenicity. these model substances, all of which had previously shown a mutagenic effect in one or the other of the various in vivo test systems, gave positive results in this test, too, with the exception of bleomycin. on the basis of the lowest effective dose and ... | 1979 | 546426 |
| protection after x-irradiation by 1,4-dithiothreitol of two mammalian cell types in vitro. | 1,4-dithiothreitol (dtt) was found to diminish the amount of chromosomal breakage in leucocyte cultures of the marsupial potorous tridactylus and in the don strain of chinese hamster cells (lhi). the maximum decrease of damage in potorous lymphocytes was to 54% of that of the irradiated cells without dtt treatment, and to 64% in the case of the chinese hamster cells. for both cell types, it was shown that the most significant effect of dtt was due to its presence in the first 30 min post irradia ... | 2005 | 546598 |
| methods to evaluate the effects of toxic materials deposited in the lung on immunity in lung-associated lymph nodes. | intratracheal instillation of sheep red blood cells (srbc) induced a primary immune response in lung-associated lymph nodes of chinese hamsters and fischer-344 rats. few or no anti-srbc antibody forming cells (afc) were found in the spleen or cervical lymph nodes after intratracheal immunization. the number of afc was significantly suppressed in the lung-associated lymph nodes from hamsters exposed by inhalation of 239puo2 and in rats exposed by intratracheal instillation of benzo(a)pyrene (bap) ... | 1979 | 548254 |
| the effect of hydroxyurea on synchronized chinese hamster ovary cells irradiated by ultraviolet light. | 1979 | 550666 | |
| gene mutation and sister chromatid exchange in chinese hamster cells. | the mutation in hypoxanthine phosphoribosyl transferase gene and the induction of sister chromatid exchange (sce) were comparatively studied treating chinese hamster ovary cells with the mutagens ethylmethanesulphonate. n-methyl-n'-nitro-n-nitrosoguanidine, mitomycin c and x-ray. all the agents exerted strong mutagenic effects and showed a dose-dependent relationship for the induction of sces. | 1979 | 555171 |
| subribosomal particles of cultured chinese hamster cells. identification of ring-shaped structures with 21s protein particles. | 1992 | 556990 | |
| glycoprotein synthesis in a temperature-sensitive chinese hamster cell cycle mutant. | 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 at the non-permissive temerature (40degreesc). synchronized cells shifed to 40degreesc 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 ( approximately 10 hours after termination of serum starvation) a ... | 1977 | 557044 |
| altered morphology and increased cell adhesiveness of chinese hamster ovary cells cultured on fibrin. | chinese hamster ovary cells cultivated on fibrin exhibited different characteristic from cells growing on plastic. while sparsely plated cells on plastic dishes had an epithelioid morphology, cells on fibrin assumed a round shape and then converted to a stretched form with protruded processes that increased with cell density. within a few days, cells fibrinolysed adjacent fibrin and returned to the morphology seen in plastic dishes. when fibrinolysis was inhibited by epsilon-aminocaproic acid (e ... | 1977 | 557051 |
| nonrandom distribution of chromosomal proteins during cell replication. | the distribution of chromatin-associated proteins in replicating chinese hamster ovary cells has been examined using the method described by taichman and freedlender (taichman, l., and freedlender, e.f. (1976), biochemistry 15, 447). cells are grown for several generations in [14c]lysine and thymidine, and then for one generation in the presence of [3h]lysine and 5-bromodeoxyuridine (brudrib) and a further generation in cold amino acid and brudrib. this protocol produces equal amounts of unifila ... | 1977 | 557988 |
| [effect of suboptimal temperature on the mitotic regime]. | a two-hour treatment of chinese hamster cells with a suboptimal temperature of 21 degrees c leads to a decrease of the mitotic index and to a delay in division at the metaphase. cooling causes a sharp rise of the pathological mitosis, represented mainly by the forms of pathology connected with the disorganization of the mitotic apparatus, such as c-mitosis and dispersion of chromosomes in the metaphase. after being transferred to the optimal temperature conditions the cells completely restored t ... | 1977 | 558014 |
| the kinetics of contact inhibition in mammalian cells. | to elucidate the process of contact inhibition in mammalian cells, we investigated the kinetics of growth arrest in [3h]thymidine labelled embryonic chinese hamster (cricetulus griseus l.) cells after the addition of various concentrations of unlabelled cells. it was observed that after the contact inhibition concentration had been reached, the cells grew undisturbed for one more generation. in the following 24 hr the concentration fell back to the level at the beginning of the experiment and st ... | 1977 | 558054 |
| coordinate regulation of protein synthesis and messenger rna content during growth arrest of suspension chinese hamster ovary cells. | we have found chinese hamster ovary cells, cultured in suspension, are subject to growth control by serum. when suspended in medium containing 0.5% serum the cells becomes reversibly arrested in the beginning of the g1 phase of the cell cycle and can be maintained in this viable, nonproliferating state for several days. this system was used to examine the regulation of protein synthesis with growth rate. in particular, the experiments addressed the question whether mrna content is the principal ... | 1977 | 558201 |
| influenza virus infection of a cell-cycle mutant of chinese hamster ovary cells. | 1977 | 558282 |