Publications
| Title | Abstract | Year(sorted descending) Filter | PMID Filter |
|---|
| radiosensitization of hypoxic mammalian cells in vitro by some 5-substituted-4-nitroimidazoles. | the efficiencies of various 5-substituted-4-nitroimidazoles as radiation sensitizers have been determined in hypoxic chinese hamster cells irradiated in vitro. compared with published data on the sensitizing properties of substituted 2-nitro- and 5-nitroimidazoles, some of the 4-nitro derivatives show unusually high sensitizing efficiencies defined as the concentrations required to give an enhancement ratio of 1.6. the equilibrium one-electron reduction potentials of the compounds (e17) were mea ... | 1981 | 6974144 |
| selection of specific wheat germ agglutinin-resistant (wgar) phenotypes from chinese hamster ovary cell populations containing numerous lecr genotypes. | three distinct chinese hamster ovary mutants selected for resistance to wheat germ agglutinin were previously described by this laboratory. in this paper, evidence is provided that each phenotype occurs at a similar frequency in an unmutagenized population of chinese hamster ovary cells. two novel wheat germ agglutinin resistance phenotypes (wgar), which also appear to occur at similar frequencies were uncovered in the course of these studies. one mutant type belongs to a new, recessive compleme ... | 1981 | 9279382 |
| changes in dna distributions and ploidy of cho cells as a function of time in culture. | chinese hamster ovary (cho) cells maintained in continuous culture for 3 to 5 months may undergo subtle changes in drug sensitivity response, growth kinetics, plating efficiencies, et cetera. our studies done independently in two different laboratories, using flow cytometry, indicate that the dna histogram patterns change at about 11 wk, from populations with an approximate diploid dna content to populations also composed of triploid and tetraploid cells. chromosome counts also change from distr ... | 1981 | 7327601 |
| mutagenicity of n-alkyl-n-(alpha-acetoxyalkyl) nitrosamines in v79 chinese hamster cells in relation to alkylating activity. | mutation to ouabain resistance and cytotoxicity were tested in v79 chinese hamster cells after the cells had been treated for 2.5 hr with a series of n,n-dialkylnitrosamines (alkyl=methyl, ethyl, propyl, butyl or tert-butyl) monosubstituted at the alpha-carbon with an acetoxy group. the effects of the length of alkyl chain and the mode of substitution with the acetoxy group on the cytotoxicity and mutagenicity were examined. in the series of n-alkyl-n-(acetoxy-methyl) nitrosamines with an acetox ... | 1981 | 7308664 |
| s phase-specific synthesis of dihydrofolate reductase in chinese hamster ovary cells. | we investigated the cell cycle modulation of dihydrofolate reductase (dhfr; tetrahydrofolate dehydrogenase, 7,8-dihydroxyfolate:nadp+ oxidoreductase, ec 1.5.1.3) levels in methotrexate-resistant chinese hamster ovary cells synchronized by mitotic selection. dna content and dhfr concentration were analyzed throughout the cell cycle by standard biochemical techniques and by double fluorescence staining utilizing the fluorescence-activated cell sorter. we found an s phase-specific period of dhfr bi ... | 1981 | 6946445 |
| purification and properties of two distinct groups of adh isozymes from chinese hamster liver. | two major classes of alcohol dehydrogenase isozymes have been purified from chinese hamster liver. the two isozyme classes have the same subunit molecular weights but different electrophoretic mobilities. they have a similar range of substrates but different krom values and sensitivities to the inhibitor pyrazole. the adhs are immunologically related as determined by ouchterlony double diffusion experiments. these results suggest that the isozymes are encoded by different structural gene loci de ... | 1981 | 6794566 |
| enhanced cytotoxicity of antineoplastic agents following prolonged exposure to misonidazole. | chinese hamster v79 cells cultured in vitro were used to investigated the cytotoxicity of various anti-cancer drugs subsequent to a prolonged treatment of the cells with misonidazole (miso). the sensitivity of the cells to bleomycin (blm), melphalan or cis-platinum (cis-ddp) was significantly increased by prior incubation with miso under hypoxic conditions. when cysteamine, a radical scavenger, was present during the pretreatment with miso, this enhancement of cytotoxicity was greatly reduced. t ... | 1981 | 6168277 |
| fine structure of the parotid gland of chinese hamster (cricetulus griseus). | the parotid gland of chinese hamster was examined by light and electron microscopy. the parotid acinar cells contained acidophile granules and reacted with the periodic acid-schiff (pas) reagent but failed to stain with alcian blue (ab). the acini were composed of light, dark and specific light cells containing secretory granules of various sizes and densities. intercalated duct cells were composed exclusively of light cells and contained a few vesicles, fine granules and polygonal granules. str ... | 1981 | 7318929 |
| [repair of dna-protein cross-links induced by antineoplastic alkylating agents]. | the bifunctional and antitumor alkylating agents embichin and its aromatic derivatives sarcolysin and chlorfenacyl remarkably differ in dna-protein cross-links induction in chinese hamster cell cultures in vitro. the differences involve the concentration necessary for cross-linkage, the time of cross-links emergence, and their reparation. since all three compounds have the same alkylating group, it is obvious that the differences seen in the cross-linkage arise from the structure of aromatic gro ... | 1981 | 7295949 |
| [karyotypic structure of chinese hamster clone cell populations in prolonged culture]. | the karyotypic structure of some clones and subclones of chinese hamster cells has been studied (cho-ki). 60-80% of all the clonal cells demonstrated the identical karyotype (the main structural variant of karyotype - msvk). the distribution of cells according to the number of chromosomes does not vary within 90 passages of clone cultivation (about 300 cell generations) and 35 passages of subclone cultivation (more than 100 cell generations). in two of three clones the frequencies of cells with ... | 1981 | 7281231 |
| metabolism of 9-beta-d-xylofuranosyladenine by the chinese hamster ovary cell. | 1981 | 6270533 | |
| effects of ethionine on the replicational fidelity in v79 chinese hamster cells. | the possibility that ethionine, the ethyl analog of methionine and potent liver carcinogen, exerts its action by blocking the methylation of dna and thereby rendering the post-replicative methylation instructed error-avoidance system inoperative was investigated. while the results are not directly supportive for the existence of such a repair system in v79 chinese hamster cells, effects of ethionine were found. following the exposure of ethionine-treated cells to ems an increase in cell killing ... | 1981 | 7266562 |
| spontaneous sister-chromatid exchanges in chinese hamster cells in vivo and in vitro. | the incidence of sister-chromatid exchanges (sces) was studied in chinese hamster cells. the cells used were an established cell line (don), an aneuploid secondary culture still exhibiting contact inhibition of growth, a primary culture, bone-marrow cells in vivo, a don-derived clone having ring chromosomes, and endoreduplicated don cells. the frequency of sces in the presence of bromodeoxyuridine (budr) increased in the following order: bone-marrow cells less than don less than secondary cultur ... | 1981 | 7266561 |
| a spectrum response study on single strand dna breaks, sister chromatid exchanges, and lethality induced by phototherapy lights. | little information is available on the effect of visible light from commercial fluorescence lamps, commonly used in the treatment of neonatal hyperbilirubinemia, on parameters related to genetic damage in eucaryotic cells. the present study was undertaken to determine whether or not visible light of different wavelengths had any differential effects on the frequency of dna breaks (frank breaks plus alkaline labile lesions), dna replication, frequency of sister chromatid exchanges, and survival i ... | 1981 | 7254946 |
| isolation of somatic cell mutants defective in the biosynthesis of phosphatidylethanolamine. | an in situ autoradiographic assay for cdp-ethanolamine:1,2-sn-diacylglycerol ethanolamine phosphotransferase (ec 2.7.8.1) activity in chinese hamster ovary cells was developed and used to screen approximately 10,000 individual mutagen-treated colonies attached to filter paper (esko, j. d., and raetz, c. r. h. (1978) proc. natl. acad. sci. u. s. a. 75, 1190-1193). a variant (strain 40.11) was isolated in which the ethanolamine phosphotransferase specific activity in vitro was 6-10-fold less than ... | 1981 | 6267019 |
| isolation of chinese hamster cell mutants defective in the receptor-mediated endocytosis of low density lipoprotein. | 1981 | 6275086 | |
| differential induction by cadmium of a low-complexity ribonucleic acid class in cadmium-resistant and cadmium-sensitive mammalian cells. | the chinese hamster ovary (cho) cell line and the subline cdr20f4 have been used to compare cadmium-induced ribonucleic acid (rna) synthesis in cadmium-sensitive and cadmium-resistant cells, respectively. gel electrophoresis of the cell-free translation products directed by polyadenylated [poly(a+)] messenger rna (mrna) from cadmium-induced cdr20f4 cells revealed four low molecular weight species (mr 7000-21 000), including metallothionein, whose synthesis was not detected after translation of e ... | 1981 | 6170314 |
| toxicity of 4'-(9-acridinylamino)methanesulfon-m-anisidide in exponential- and plateau-phase chinese hamster cell cultures. | the antitumor acridine derivative 4'-(9-acridinylamino)methanesulfon-m-anisidide (m-amsa) is at present being evaluated in phase 2 clinical trials. exposure of exponential-phase chinese hamster v79-171b cells to physiologically attainable concentrations of m-amsa for 60 min generates survival curves with little or no threshold region and an initial d0 of 0.245 +/- 0.019 (s.d.) microm under standard conditions of assay. a minor subpopulation of apparently drug-resistant cells is revealed at low s ... | 1981 | 6894713 |
| cell-free synthesis of putative type v procollagen chains programmed by chinese hamster lung cell mrna. | a messenger rna fraction isolated from cultured chinese hamster lung (chl) cells programs in a cell-free system prepared from wheat germ the efficient incorporation of [14c] proline into newly synthesized protein with a significant fraction of the incorporated substrate being digestible with bacterial collagenase. this reaction requires both subcellular fractions, an energy source, and is inhibited by the antibiotic puromycin. the relative amount of collagenase-digestible to non-digestible cell- ... | 1981 | 6286232 |
| [the frequency of sister chromatid exchanges in v79 chinese hamster cells exposed to heavy metals]. | 1981 | 7316766 | |
| cytosolic 25-hydroxycholesterol binding activity of chinese hamster ovary cells. | 1981 | 7283442 | |
| laser-uv-microirradiation of chinese hamster cells: the influence of the distribution of photolesions on unscheduled dna synthesis. | 1981 | 7280047 | |
| [effect of various pharmacologic preparations on the viability of chinese hamster fibroblasts in vitro]. | the effect of the physiologically active substances (histamine, serotonin) and their antagonists (bicarfene, cyproheptadine and preparation 407) on the growth of chinese hamster fibroblasts in vitro has been studied. the cell survival evaluated from the number of colonies grown by the 7th day of cultivation served as criterion for the action of the substances under study. determination of amines in fibroblast extracts was made by spectrofluorometry. it has been discovered that chinese hamster fi ... | 1981 | 7272495 |
| integrity of mitochondria in a mammalian cell mutant defective in mitochondrial protein synthesis. | a defect in mitochondrial protein synthesis has previously been identified in the respiration-deficient chinese hamster lung fibroblast mutant v79-g7. the present work extends the characterization of this mutant. a more sensitive analysis has shown that mutant mitochondria synthesize all mitochondrially encoded peptides, but in significantly reduced amounts. this difference is also seen when isolated mitochondria are tested for in vitro protein synthesis. to distinguish between a defect in the t ... | 1981 | 6265473 |
| effects of aclacinomycin on cell survival and cell cycle progression of cultured mammalian cells. | the effects of aclacinomycin (acm; nsc 208734) on cell viability, growth, and colony formation were investigated in suspension (friend leukemia and l1210) and adherent (chinese hamster ovary) cell systems. cell cycle progression and the effect of the drug on various transition points in the cell cycle (i.e. g1 to s phase, through a window in early s phase and g2 phase to mitosis) were monitored by flow cytometry. formation of chinese hamster ovary cell colonies was inhibited by 50% following 24 ... | 1981 | 6166368 |
| comparison of the effects of hydrogen peroxide and x-ray irradiation on toxicity, mutation, and dna damage/repair in mammalian cells (v-79). | hydrogen peroxide is not detectably mutagenic at the hypoxanthine-guanine phosphoribosyl transfer locus (measured as 6-thioguanine resistance) in v-79 chinese hamster lung cells, yet is cytotoxic with a do dose of 240 mum. x-ray, by contrast, is both mutagenic and cytotoxic with a do dose of 260 rad for cytotoxicity. the number of dna single-strand breaks induced at equitoxic doses is much greater for hydrogen peroxide than it is for x-ray. single-strand breaks are repaired with initial t 1/2 va ... | 1981 | 7272307 |
| fluctuation analyses of spontaneous mutations to 6-thioguanine resistance in chinese hamster ovary cells in culture. | fluctuation analyses of the spontaneous appearance of 6-thioguanine (tg)-resistant mutants in cultured chinese hamster ovary (cho) cells were performed to investigate (1) whether the resistance is induced by the selective agent or is the result of a mutation which occurs prior to the tg selection and (2) to estimate the spontaneous mutation rate at the hypoxanthine--guanine phosphoribosyl transferase (hgprt) locus. the potential problem of phenotypic delay was minimized by allowing an adequate e ... | 1981 | 7196493 |
| giant cell formation produced by laser microbeam irradiation of chromatin in chinese hamster cells. | 1981 | 7195821 | |
| activity of 4'-(9-acridinylamino)methanesulfon-m-anisidide against chinese hamster cells in multicellular spheroids. | the cytotoxic activity of 4'-(9-acridinylamino)methanesulfon-m-anisidide (m-amsa), a novel acridine derivative with clinical antitumor activity, has been examined in multicellular spheroids grown from chinese hamster v79-171b cells. m-amsa is much less effective against cells within these tumor-like structures than it is against exponential-phase v79-171b cells in monolayer cultures, the initial d0 of the survival curve for the latter being approximately 10-fold lower than for the former followi ... | 1981 | 7018670 |
| n-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide, a calmodulin antagonist, inhibits cell proliferation. | n-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (w-7) and its derivatives are putative calmodulin antagonists that bind to calmodulin and inhibit ca2+/calmodulin-regulated enzyme activities. autoradiographic studies using tritiated w-7 showed that this compound penetrates the cell membrane, is distributed mainly in the cytoplasm, and inhibits proliferation of chinese hamster ovary k1 (cho-k1) cells. cytoplasmic [3h]w-7 was excluded completely within 6 hr after removal of [3h]w-7 from the cult ... | 1981 | 6945588 |
| evidence indicating that inactivation of 3-hydroxy-3-methylglutaryl coenzyme a reductase by low density lipoprotein or by 25-hydroxycholesterol requires mediator protein(s) with rapid turnover rate. | the half-life (t 1/2) of 3-hydroxy-3-methylglutaryl coenzyme a (hmg-coa) reductase of chinese hamster ovary cells grown in fetal calf serum medium is approximately 2 h. when cells are switched to grow in delipidated serum medium (del-m) for more than 24 h, the t 1/2 of the enzyme is found to be drastically altered to approximately 13 h. exposure of low density lipoprotein (ldl) (100 micrograms of protein/ml) or 25-hydroxycholesterol (1 microgram/ml) to cells grown in del-m suppresses reductase a ... | 1981 | 7240196 |
| effects of metabolic inhibitors on cel lethality and mutation induction in chinese hamster cells. ii. the effect of posttreatment with non-toxic concentrations of thymidine. | the ability of posttreatment exposure to non-toxic concentrations of thymidine (tdr) to enhance the lethal effects of a number of alkylating agents, x-rays and uv and the lethal and mutagenic effects of n'-ethyl-n-nitrosourea (enu) and n-methyl-n-nitrosourea (mnu) has been examined in v79 cell lines. tdr posttreatment enhanced the cytotoxic effects of ethyl methanesulphonate (ems), mnu and enu but not of uv or x-rays and increased both the spontaneous and mnu- and enu-induced frequencies of azag ... | 1981 | 7249152 |
| effects of metabolic inhibitors on cell lethality and mutation induction in chinese hamster cells. i. inhibitors of de novo purine synthesis and a comparison with the effects of caffeine. | the effect of pre- and posttreatment incubation of uv-irradiated and ethyl methanesulphonate (ems) treated cells with non-toxic concentrations of inhibitors of de novo purine synthesis (dnps) on expression of potentially lethal and premutational damage at the hypoxanthine-guanine phosphoribosyl transferase (hgprt) locus in v79 cells has been examined. the concentrations of inhibitors used were shown to profoundly perturb de novo dna synthesis, by measurements of [14c]formate uptake, and cell cyc ... | 1981 | 7249151 |
| glycogen synthase activity in chinese hamster ovary cells. studies with wild-type and mutant cells defective in cyclic amp-dependent protein kinase. | glycogen synthase (ec 2.4.1.11) activity was studied in cell extracts from wild-type chinese hamster ovary (cho) cells and three mutants resistant to cyclic amp effects on cell shape and cell growth. based on the capacity of crude extracts to phosphorylate exogenous histone, two of the mutants appeared to have altered cyclic amp-dependent protein kinase (ec 2.7.1.37) and one of them had apparently normal amounts of kinase activity. glycogen synthase activity was present in comparable amounts in ... | 1981 | 6266497 |
| neutral amino acid transport systems in chinese hamster ovary cells. | the neutral amino acid transport systems a, asc, and l have been characterized in the chinese hamster ovary cell. system a, defined by its sodium ion dependency and inhibition by 2-methylaminoisobutyric acid, was found to be extremely sensitive to the ph of the external medium and to increase in response to starvation for amino acids. system asc, identified by its sodium ion dependency and intolerance of n-methylation of substrates, was found to be relatively insensitive to external ph and nutri ... | 1981 | 7240147 |
| metabolism of ubiquitinated histones. | in animal chromatin, a fraction of the histone 2a's and 2b's is covalently attached to the protein ubiquitin through an isopeptide linkage. the ubiquitin moieties of the h2a's and h2b's are found to be in rapid equilibrium with the pool of free ubiquitin, both in dividing cells such as l1210 and chinese hamster ovary cells and in nondividing cells such as unstimulated lymphocytes. the synthesis of ubiquitin and the formation of ubiquitinated histones are not linked to dna synthesis. all ubiquiti ... | 1981 | 6263895 |
| induction of polyamine limitation in chinese hamster ovary cells by alpha-methylornithine. | chinese hamster ovary (cho) cells in culture were limited for polyamines through the use of alpha-methylornithine (alpha mo), a competitive inhibitor of ornithine decarboxylase. initial exposure of the cells to the inhibitor caused growth rate and intracellular polyamine content to decline continuously. reseeding the alpha mo-treated cells into medium containing the inhibitor resulted in steady-state (exponential) growth at cell densities below 5 x 10(3) cells/cm2, at a rate approximately twofol ... | 1981 | 7195909 |
| a comparison of the fixation of x-ray or heat damage in chinese hamster cells exposed to anisotonic salt solutions. | 1981 | 6972934 | |
| recovery after exposure to near-ultraviolet light of cells containing 5-bromodeoxyuridine. | the survival of synchronized v79 chinese hamster cells irradiated with near-ultraviolet light after a 1-h labeling with 5-bromodeoxyuridine (brdurd) is highly dependent upon the cell's position in the cell cycle at the time of irradiation (hagan, m., and m. m. elkind. biophys. j. 1979. 27:75-86). in this report, we show that cells irradiated in the same s phase after brdurd incorporation demonstrate an ability to repair sublethal damage, in contrast to the lack of an increase in survival with do ... | 1981 | 7248467 |
| the application of rapid-lysis techniques in radiobiology. iv. the effect of glycerol and dmso on chinese hamster cell survival and dna single-strand break production. | 1981 | 7244125 | |
| the effect of dexamethasone on the radiation survival response and misonidazole-induced hypoxic-cell cytotoxicity in chinese hamster cells v-79-753b in vitro. | overnight exposure of chinese hamster cells, v-79-753b, to microgram quantities of the synthetic corticosteroid, dexamethasone, resulted in a decrease in sensitivity towards radiation, both in air and in hypoxia. the effect was dose-modifying and the oxygen enhancement ratio did not change appreciably. similarly, when dexamethasone-treated hypoxic cells were irradiated in the presence of misonidazole, a hypoxic cell radiosensitizer, there was a decrease in radiation sensitivity compared with unt ... | 1981 | 7237030 |
| the effects of fibronectin on the adhesion and migration of chinese hamster ovary cells on collagen substrata. | data are presented indicating that the adhesion of chinese hamster ovary cells (cho) to films of denatured type i collagen occurs by a fibronectin-dependent mechanism, whereas the adhesion of these cells to 3-dimensional gels of native type i collagen fibres may occur by either a rapid, fibronectin-dependent mechanism or by a slower, fibronectin-independent mechanism, whereas the adhesion of these cells to 3-dimensional gels of native type i collagen fibres may occur by either a rapid, fibronect ... | 1981 | 7198128 |
| simplification of the cho/hgprt mutation assay through the growth of chinese hamster ovary cells as unattached cultures. | a novel technique for the growth of chinese hamster ovary (cho) cells as unattached cells on the nontissue culture plates was applied to the cho/hgprt mutation assay, using ems and mnng as mutagens. the subculturing procedures for the unattached cultures involved less time and effort than those for the conventional attached cultures since trypsinization was not required for cell detachment. no significant difference in the maximum mutation frequency was observed for cells grown as unattached or ... | 1981 | 7196496 |
| evidence for coordinate expression of 3-hydroxy-3-methylglutaryl coenzyme a reductase ad low density lipoprotein binding activity. | a chinese hamster ovary cell mutant that requires both cholesterol and unsaturated fatty acids for growth (limanek, j. s., chin, j., and chang, t. y. (1978) proc. natl. acad. sci. u. s. a. 75, 5452-5456) has been further characterized with respect to its dependence on cholesterol. upon removal of serum lipids from the growth medium, the activity of the important cholesterogenic enzyme 3-hydroxy-3-methylglutaryl coenzyme a (hmg-coa) reductase and the low density lipoprotein (ldl) binding activity ... | 1981 | 7240205 |
| glucose starvation alters lipid-linked oligosaccharide biosynthesis in chinese hamster ovary cells. | the effect of glucose deprivation on the synthesis of lipid-linked oligosaccharides by chinese hamster ovary cells has been studied. when these cells are placed in serum-free dulbecco's minimal essential medium devoid of glucose, there is a rapid cessation of the synthesis of the usual glc3man9glcnac2 lipid-linked oligosaccharide and the accumulation of a smaller species with the composition man9glcnac2. this latter compound is the glucosylated and transferred to protein where it is subsequently ... | 1981 | 7240203 |
| the role of energy in hyperthermia-induced mammalian cell inactivation: a study of the effects of glucose starvation and an uncoupler of oxidative phosphorylation. | when cultured chinese hamster cells were exposed to 43 degrees c hyperthermia, effects due to glucose deprivation and to the presence of the uncoupler of oxidative phosphorylation, carbonylcyanide-3-chlorophenylhydrazone, during the 43 degrees c treatment proved to be strongly accelerated compared to the effects at normal temperature (37 degrees c). this strongly indicates that the availability of energy plays an important role in the response of these cells to hyperthermia. one of the reasons c ... | 1981 | 7195908 |
| mutagen-induced resistance to mycophenolic acid in hamster cells can be associated with increased inosine 5'-phosphate dehydrogenase activity. | cell variants resistant to the cytotoxic effect of mycophenolic acid, an inhibitor of imp dehydrogenase (imp:nad+ oxidoreductase, ec 1.2.1.14), were selected by a one-step procedure from chinese hamster v79 cells. the frequency of these variants was increased in a dose-dependent manner after treatment with the mutagen n-methyl-n'-nitro-n-nitrosoguanidine and after an expression time of 8 days. the degree of resistance in five of the six isolated cell variants was associated with a comparable inc ... | 1981 | 6114490 |
| synthesis and behaviour of small rna species of cho cells submitted to a heat chick. | incubation of chinese hamster ovary (cho) cells for 1 hour at 43 degrees c results in an inhibition of high molecular weight rna synthesis while most of the ow molecular weight rnas are still synthesized. in cells returned to 37 degrees c, the transcription of high molecular weight rna is reinitiated after 7 h recovery. the synthesis of snrna a, c, d which are transcribed by rna polymerase b (ii) is inhibited in cells incubated at 43 degrees c while the synthesis of 4s, 5s, l and k components is ... | 1981 | 6164991 |
| [influence of adriamycin upon the radiation effect on chinese hamster cells (author's transl)]. | during combined treatment of chinese hamster cells in vitro with adriamycin and irradiation, there appear interactions between the two treatment modalities, v79 cells showing interaction in an additive sense, b14 cells in the sense of synergistic interaction. the capacity for interaction can persist for a long while, and even may be transmitted to the offspring of surviving cells. treatment with adriamycin does not influence the fractionation effect or the recovery from sublethal radiation damag ... | 1981 | 7245270 |
| thermotolerance in chinese hamster cells under oxic conditions after chronic culture under hypoxia. | 1981 | 7236493 | |
| fixation of potentially lethal radiation damage in chinese hamster cells by anisotonic solutions, polyamines, and dmso. | 1981 | 7220804 | |
| kinetics of mutation and sister-chromatid exchange induction by ethyl methanesulfonate in chinese hamster ovary cells. | 1981 | 7195461 | |
| use of solubilizing agents to study radiosensitization in vitro by compounds of low water solubility. | a major disadvantage in studying the effects of chemicals on the radiation response of mammalian cells in vitro can be the poor water solubility of the chemicals. using chinese hamster cells we have overcome this problem by using dimethyl sulphoxide and ethanol as co-solvents. from studies using these co-solvents and misonidazole as a standard we have demonstrated that these co-solvents have no effect on sensitizing efficiency and cytotoxicity. a number of poorly water soluble 2-nitroimidazoles ... | 1981 | 6972928 |
| enhanced internalization of ricin in nigericin-pretreated chinese hamster ovary cells. | biochemical and electron microscopic autoradiographic studies with [125i] ricin have revealed that nigericin-pretreated chinese hamster ovary cells are more efficient than untreated cells in the internalization of the toxin into the cells. these results suggest that the enhanced rate of internalization of ricin in nigericin-pretreated cells may account for the enhancement of cytotoxicity of ricin in chinese hamster ovary cells by nigericin. | 1981 | 6965109 |
| internalization of ricin in chinese hamster ovary cells. | internalization of ricin into chinese hamster ovary cells has been investigated. combined treatment with galactose and pronase at 0 degrees c resulted in a complete release of surface-bound [125i]ricin into the media. galactose-pronase-resistant cell-bound [125i]ricin represents internalized ricin molecules inside the cells. the internalization process is time, temperature, and concentration dependent. the ph optimum of internalization of ricin is about ph 7. sodium dodecyl sulfate-polyacrylamid ... | 1981 | 6965107 |
| genetic diversity of uv-sensitive dna repair mutants of chinese hamster ovary cells. | mutant lines of chinese hamster ovary cells that show hypersensitivity to killing and mutagenesis by uv light were analyzed by genetic complementation analysis to determine whether defects in different gene loci might underlie a common cellular phenotype,. to facilitate rapid screening of mutant clones, a procedure was devised that allowed presumptive complementation to be assessed on the basis of the frequency of uv-resistant cells after fusion by polyethylene glycol. four classes were identifi ... | 1981 | 6943579 |
| correlation between the half-wave reduction potentials of nitroheterocycles and their mutagenicity in chinese hamster v79 spheroids. | toxicity and dna damage by nitroheterocycles has previously been correlated with their redox potentials. resistance to 6-thioguanine was measured using chinese hamster v79 cells grown in suspension culture as three-dimensional cell clusters of "spheroids". since diffusion gradients of oxygen and other nutrients are largely responsible for the growth properties of spheroids, cells grown as spheroids might better simulate cells exposed to mutagens in vivo. the log of the concentration inducing 10 ... | 1981 | 6790977 |
| carboxyl terminal tyrosine metabolism of alpha tubulin and changes in cell shape: chinese hamster ovary cells. | 1981 | 6271126 | |
| the mechanisms of endoreduplication. | chinese hamster cells, don line, were treated with concanavalin a (cona), calcium ionophore a23187 (a23187), colchicine, sodium fluoride (naf), 6-thiopurine, dibutyryl cyclic amp (db-camp), and other nucleotides, alone or in combination. a23187 itself did not induce endoreduplication but did so in combination with cona. naf could induce endoreduplication and the combination of naf and cona showed a synergistic effect. db-camp suppressed the inducing activity of cona. the findings that various ch ... | 1981 | 6266650 |
| aminoimidazole carboxamide ribonucleoside toxicity: a model for study of pyrimidine starvation. | aminoimidazole carboxamide ribonucleoside (aic-r), a purine precursor, has biphasic effects on the growth of chinese hamster fibroblasts. at 200 microm aic-r cell growth is almost completely arrested, while at 50 and 700 microm aic-r cell growth is comparable to that observed in the absence of nucleoside. the growth inhibition produced by aic-r is the consequence of inhibition of the orotate phosphoribosyltransferase-orotidylic decarboxylase (oprt-odc) reactions, as evidenced by a 87% reduction ... | 1981 | 6166628 |
| distinct mechanisms of hypoxanthine and inosine transport in membrane vesicles isolated from chinese hamster ovary and balb 3t3 cells. | both enzyme-mediated group translocation and facilitated diffusion have been proposed as mechanisms by which mammalian cells take up purine bases and nucleosides. we have investigated the mechanisms for hypoxanthine and inosine transport by using membrane vesicles from chinese hamster ovary cells (cho), balb/c 3t3 and sv3t3 cells prepared by identical procedures. uptake mechanisms were characterized by analyzing intravesicular contents, determining which substrates could exchange with the transp ... | 1981 | 7225383 |
| preparation and characterization of a cell-free system from chinese hamster ovary cells that translates natural messenger ribonucleic acid and analysis of intermediary reactions. | 1981 | 6168209 | |
| effect of tumor promoter 12-o-tetradecanoyl-phorbol 13-acetate on induction of sister-chromatid exchanges in chinese hamster v79 cells treated with mutagens. | the effect of a tumor promoter, 12-o-tetradecanoyl-phorbol 13-acetate (tpa) alone and in combination with mitomycin c (mmc) or cyclophosphamide (cpp) on the induction of sister-chromatid exchanges (sce) in chinese hamster v79 cells was investigated. tpa alone at various doses and durations caused no increase of sce frequency. mmc either at the dose of 0.03 or 0.003 microgram/ml alone or in combination with tpa (2 microgram/ml) all caused a significant increase of sce frequencies. there was no di ... | 1981 | 7300845 |
| [autoradiography of the dna of lysed, uv-irradiated cells in chinese hamster cultures differing in uv sensitivity]. | 1981 | 7256858 | |
| toxic and clastogenic effects of the polyfunctional alkylating agent n,n,n'-tri(beta-chloroethyl)-n'-(p-formylphenyl)-propylenediamine 1,3 (tfp) in the presence and absence of sodium borohydride in v79 chinese hamster cells. | 1981 | 7242556 | |
| analysis of vinblastine-sensitive sites in certain g-banded chromosomes of d-6 cells of the chinese hamster. | 1981 | 7242553 | |
| potential radiosensitizing agents. 2. synthesis and biological activity of derivatives of dinitroimidazole with oxiranes. | a series of 1-substituted 2,4-dinitroimidazole analogues have been synthesized and tested for their radiosensitizing ability for selectively sensitizing hypoxic mammalian cells to the lethal effect of radiation. the reaction of 2,4-(5)-dinitroimidazole (1) with a variety of oxiranes upon heating in absolute ethanol yielded the expected 1-substituted 2,4-dinitroimidazoles (2) and also resulted in the formation of a novel class of isomeric nitroimidazo[2,1-b]oxazoles 3 and 4) by intramolecular cyc ... | 1981 | 7241517 |
| chinese hamster ovary mutant uv-1 is hypomutable and defective in a postreplication recovery process. | cho-uv-1 is a mutant of the chinese hamster cell cho-k1 hypersensitive to killing by ultraviolet light but with normal resistance to x-ray. it is also hypersensitive to killing by ethyl methane sulfonate. hybrid clones formed bu fusing uv-1 and chinese hamster lung cells display the normal ultraviolet resistance of the latter. the sensitive phenotype behaves, therefore, in a genetically recessive manner. ultraviolet sensitivity of uv-1 is not associated with a deficiency in excision repair. alka ... | 1981 | 7197403 |
| genetic polymorphisms and gene expression variations at enzyme loci in chinese hamster cell lines. | a series of chinese hamster cell lines commonly used in somatic cell genetics research was examined for variations in either expression or electrophoretic mobility of 43 enzyme gene products by starch gel electrophoresis followed by histochemical staining. stable variations in the qualitative expressions of the creatine kinase b and adenylate kinase 1 (ak1) loci were detected among the cell lines and verified in subclones. all ten cell lines examined were deficient in the expression of the lacta ... | 1981 | 7197402 |
| reduction of 1-beta-d-arabinofuranosylcytosine and adriamycin cytotoxicity following cell cycle arrest by anguidine. | the protein synthesis inhibitor anguidine induced a frozen cell cycle state in exponentially growing chinese hamster ovary cells, as demonstrated by serial dna flow cytometric measurements in the absence and presence of colcemid as a stathmokinetic agent. the minimally effective concentration of anguidine for induction of cell cycle arrest was 0.1 microgram/ml. as demonstrated by tritiated thymidine labeling index and dna flow cytometric investigations in the presence of colcemid, a 4-hr exposur ... | 1981 | 7214318 |
| capillary basement membrane thickening associated with the small intestine of the ketonuric diabetic chinese hamster. | morphometric evaluation of intestinal capillary basement membranes demonstrated a significant thickening in those of ketonuric diabetic chinese hamsters compared to age-matched nondiabetic controls. a highly significant correlation was found between increased capillary basement membrane thickness and progression of ketonuria. age was also positively related to elevation in capillary basement membrane thickness of control and diabetic hamsters. capillary basement membrane thickness of diabetic an ... | 1981 | 7206632 |
| design of a statistical method for the analysis of mutagenesis at the hypoxanthine-guanine phosphoribosyl transferase locus of cultured chinese hamster ovary cells. | mutagenesis data collected in the mammalian cell cho/hgprt assay were analyzed to study the distribution of the experimental errors associated with the test. the data neither followed the widely assumed poisson distribution nor satisfied the usual statistical assumptions of normality and homogeneous variance of experimental errors. we transformed the data by using the power formula y = (x + a) gamma where x is the observed mutation frequency, y is the transformed frequency, and a and gamma are c ... | 1981 | 7196495 |
| mutator phenotypes in mammalian cell mutants with distinct biochemical defects and abnormal deoxyribonucleoside triphosphate pools. | recent studies of in vitro dna synthesis have shown that fidelity of replication is influenced by the relative concentrations of deoxyribonucleoside triphosphates (dntps). several investigators have used reconstituted prokaryotic replication systems to copy defined natural templates and have shown that specific incorporation errors can be induced by an appropriate bias of the precursor pools. the recent demonstration of mutator phenotypes among mutant chinese hamster ovary cell lines with altere ... | 1981 | 7017732 |
| antimitotic and cytotoxic activity of cis-dichlorobis-(cyclohexylamine)platinum(ii) on chinese hamster ovary cells. | the antimitotic and cytotoxic effects of cis-dichlorobis(cyclohexylamine)-platinum(ii) (cis-had) which among pt complexes used as antitumoral drugs shows the highest therapeutic index (ti) have been compared to those os cis-dichlorodiamine platinum(ii) (cis-ddp), the most commonly used drug of this group, using chinese hamster ovary cell cultures (cho line). dna synthesis inhibition, mitotic index, cell viability, chromosome aberrations and cell survival have been taken into account. the data in ... | 1981 | 7194152 |
| selective killing of methotrexate-resistant cells carrying amplified dihydrofolate reductase genes. | a method for the selective killing of methotrexate (mtx)-resistant cells has been developed. the selection is based on the incorporation of tritiated deoxyuridine into the dna of mtx-resistant cells but not normal mtx-sensitive cells in the presence of the drug. a chinese hamster ovary cell mutant that overproduces dihydrofolate reductase was used as an example of a mtx-resistant cell line. in this system, a 10,000-fold enrichment for wild-type mtx-sensitive cells could be achieved after 24 hr o ... | 1981 | 7194140 |
| cell cycle kinetics of chinese hamster (cho) cells treated with the iron-chelating agent picolinic acid. | spontaneously transformed (tumorigenic) chinese hamster cells (line cho) do not exhibit picolinic acid-sensitive g1 and g2 cell cycle arrest points observed in normal and virus-transformed cells. rather, picolinic acid arrests cho cells in s phase only and produces culture growth behaviour similar to that produced by hydroxyurea. prolonged treatment with picolinic acid permits a slow but significant traverse of cells through s phase. thus, like hydroxyurea, picolinic acid is not a useful agent f ... | 1981 | 7016329 |
| segregation of recessive phenotypes in somatic cell hybrids: role of mitotic recombination, gene inactivation, and chromosome nondisjunction. | somatic cell hybrids heterozygous at the emetine resistance locus (emtr/emt+) or the chromate resistance locus (chrr/chr+) are known to segregate the recessive drug resistance phenotype at high frequency. we have examined mechanisms of segregation in chinese hamster cell hybrids heterozygous at these two loci, both of which map to the long arm of chinese hamster chromosome 2. to follow the fate of chromosomal arms through the segregation process, our hybrids were also heterozygous at the mtx (me ... | 1981 | 6965251 |
| inhibition of induced ornithine decarboxylase activity in chinese hamster cells by gamma radiation, far ultraviolet light and psoralen plus near-ultraviolet light: a comparative study. | inhibition by radiation of the transcriptionally controlled induction of ornithine decarboxylase (odc) was studied in plateau-phase chinese hamster cells. the effects of gamma radiation, far ultraviolet (254nm, uv-c) light and psoralen plus near-u.v. light (360nm, puv-a) were compared. increasing doses of all three treatments caused an exponential decrease in the capacity for odc induction. this was preceded by a large shoulder region in the case of puv-a. there was no shoulder for gamma radiati ... | 1981 | 6972363 |
| gamma radiation inhibits the appearance of induced ornithine decarboxylase activity in chinese hamster cells. | ornithine decarboxylase activity of chinese hamster cells (odc, ec 4.1.1.17) can be induced in plateau phase by change of medium. exposure of the cells to gamma radiation before induction reduces the amount of odc activity induced. the dose-response curve is exponential with a d0 of 106 krad. exposure of budr-substituted cells is more effective in reducing odc induction at high doses, with a d0 of 38 krad. cells can recover from the reduction incurred by 74 krad if enzyme induction is delayed fo ... | 1981 | 6972362 |
| analysis of glycosaminoglycan from diabetic and normal chinese hamster cells. | diabetic and normal cell lines from chinese hamster kidneys were cultured in media containing 35so4 and 3h-glucosamine. glycosaminoglycans (gag) were extracted and analyzed from the media, trypsin, and cell pellet by enzymatic and electrophoretic procedures. significant increases in the hyaluronic acid content were noted in all three fractions of diabetic gags when compared with normals. in addition, an increased heparan sulfate content and decreased chondroitin sulfate amounts were noted in dia ... | 1981 | 6785129 |
| modulation of surface proteins by calcium in chinese hamster lung cells. | 1981 | 7202558 | |
| formation and fate of heterokaryons involving embryonal carcinoma cells. | we have shown that murine embryonal carcinoma (ec) cells will readily fuse to non-ec cells following treatment with polyethylene glycol (peg). heterokaryons were detected by autoradiography and by the induction of premature chromosome condensation (pcc). those heterokaryons formed between ec cells and certain of the non-ec cell types did not proliferate to form viable hybrids. for example, hybrids were not recovered from ec/hela heterokaryons in spite of the fact that both ec/3t3 and hela/3t3 he ... | 1981 | 7197401 |
| clastogenic activity of caramel and caramelized sugars. | cultured chinese hamster ovary (cho) cells were exposed for 3 h to caramelized solutions of the sugars sucrose, glucose, mannose, arabinose, maltose and fructose. each of these caramelized sugars induced a relatively high frequency of chromosome breaks and exchanges in the treated cells. the non-caramelized sugars did not increase the frequency of chromosome aberrations. a potent clastogenic effect was also observed when a commercially used caramel powder was assayed. up to 54% of all examined m ... | 1981 | 7195982 |
| the use of chinese hamster ovary cells to quantify specific locus mutation and to determine mutagenicity of chemicals. a report of the gene-tox program. | 1981 | 7022191 | |
| laser microirradiation of chinese hamster cells at wavelength 365 nm: effects of psoralen and caffeine. | 1981 | 7010411 | |
| microcell-mediated cotransfer of genes specifying methotrexate resistance, emetine sensitivity, and chromate sensitivity with chinese hamster chromosome 2. | many selectable mutants of somatic chinese hamster cells have been described, but very few of the mutations have been mapped to specific chromosomes. we have utilized the microcell-mediated gene transfer technique to establish the location of three selectable genetic markers on chromosome 2 of chinese hamster. microcells were prepared from the methotrexate-resistant mtxriii line of flintoff et al. (somatic cell genet. 2:245-261, 1976) and fused to wild-type cho cells, and microcell hybrids (tran ... | 1981 | 6965250 |
| predominance of core histones in formation of dna--protein crosslinks in gamma-irradiated chromatin. | chromatin and a subunit of chromatin containing a complex of dna and the core histones--h2a, h2b, h3, and h4--have been prepared from cultured chinese hamster cells. comparison of the formation of radiation-induced dna--protein crosslinks in whole chromatin with that in the dna--core histone complex has demonstrated that the core histones are the specific proteins involved in crosslinking. gamma irradiation of the chromatin subunit in the presence of radical scavengers has shown the hydroxyl rad ... | 1981 | 6941278 |
| isolation and preliminary characterization of bleomycin-resistant mutants from chinese hamster ovary cells. | stable mutants resistant to an anticancer antibiotic, bleomycin-a2, were selected in chinese hamster ovary (cho) cell either spontaneously or after ethylmethane sulfonate mutagenesis. fluctuation analysis showed that bleomycin resistance occurs in cho at a rate of 6.50--6.58 x 10(-7) mutations per cell per generation. bleomycin-a2-resistant cell lines exhibited increased resistance to bleomycin analogs--bleomycin-a5, -b2, -b4, and pepleomycin. colchicine, mitomycin c, and ultraviolet light irrad ... | 1981 | 6163788 |
| cytotoxicity of metronidazole (flagyl) and misonidazole (ro-07-0582): enhancement by lactate. | the cytotoxic activity of metronidazole (flagyl) and misonidazole (miso) to hypoxic chinese hamster ovary (cho) cells suspended in standard medium in sealed vials and in gassed spinner flasks has been investigated. flagyl (5 mm) was only cytotoxic at high initial cell densities. however, when lactate (20 mm) was included in the medium the cytotoxicity of flagyl at low cell densities was considerable, and similar to that of misonidazole under the same conditions. the relevance of this "lactate ef ... | 1981 | 7225286 |
| inhibition of dna synthesis and cell cycle in chinese hamster cells by sterol-binding polyene amphotericin b. | amphotericin b, a sterol-binding polyene antibiotic, was found to inhibit dna synthesis more than protein or rna synthesis of asynchronous cultures of chinese hamster v79 cells. dna synthesis in the asynchronous v79 cells was inhibited to 40--60% of the control activity in the presence of 50 micrograms/ml amphotericin b. however, addition of 50 micrograms/ml of polyene immediately after to onset of dna synthesis (early s phase) caused a drastic reduction of dna synthesis (below 10--20% of the co ... | 1981 | 7213739 |
| acid glycohydrolase in chinese hamster with spontaneous diabetes. vii. the lack of short-term glucose-effect in cultured kidney cells. | an epithelial cell line, designated chk-ace, was established from the kidney of a spontaneously diabetic chinese hamster from the highly inbred ac line. chk-ace was separated into two sublines, chk-ace-100 and chk-ace-400, by successive passages in 100 and 400 mg/dl glucose respectively. extra- and intracellular activities of n-acetyl-beta-d-glucosaminidase and beta-d-galactosidase were measured in these cultures after exposure to varying concentrations of glucose (100, 200, 300 and 400 mg/dl) f ... | 1981 | 6783122 |
| response of chinese hamster ovary cells to anticancer drugs under aerobic and hypoxic conditions. | 1981 | 7470389 | |
| selection and characterization of chinese hamster ovary cell mutants resistant to melphalan (l-phenylalanine mustard). | melphalan (alkeran) is an alkylating agent commonly used in the treatment of multiple myeloma and other neoplasia. we have isolated melphalan-resistant (melr) chinese hamster ovary cells in vitro. stably resistant clones were observed with a frequency of about 10(-7) after a single drug exposure. two clones, melr1 and melr6, were studied in detail, and their phenotypes were compared to a colchicine-resistant membrane permeability mutant (chrc5) isolated previously by ling and thompson (j. cell p ... | 1981 | 7448783 |
| the effect of non-phorbol promoters as compared with phorbol myristate acetate on sister chromatid exchange induction in cultured chinese hamster cells. | the effect of 5 unrelated chemicals with different promoting potencies on sister chromatid exchange (sce) induction in v79 cells was investigated. two powerful promoters--12-o-tetradecanoylphorbol-13-acetate (tpa) and anthralin; a moderate promoter--iodoacetic acid (iaa); two weak promoters--ethyl phenylpropiolate (epp) and cantharidin--all induced similar and low numbers of sce. these results do not support the hypothesis that enhanced mitotic recombination is responsible for tumour promotion. | 1981 | 7296528 |
| rapid cell surface appearance of endocytic membrane proteins in chinese hamster ovary cells. | lactoperoxidase was used to selectively radiolabel endocytic membrane. cho cells were incubated with enzyme at 37 degrees c for 10 min to permit lactoperoxidase internalization. radioiodination was done at 4 degrees c. about 90% of the radioiodinated products pelleted at 100,000 x g. from 12 to 15 different electrophoretic species were detected by one-dimensional gel electrophoresis. when cells labeled by internalized lactoperoxidase were warmed to 37 degrees c, the incorporated radioactivity wa ... | 1981 | 6965100 |
| selection of aphidicolin-resistant cho cells with altered levels of ribonucleotide reductase. | chinese hamster ovary cells were initially selected for resistance to aphidicolin at 0.3 microgram/ml. serial cultivation with aphidicolin at concentrations up to 5.0 micrograms/ml yielded a series of mutants with increasing resistance. the most resistant mutant isolated was 44 times more resistant to aphidicolin than the parental cho. the alpha-polymerases, assayed in the cytoplasmic extracts of the mutants, did not increase in specific activity or differ from the parental cho in their sensitiv ... | 1981 | 6794165 |
| isolation and characterization of a uv-sensitive hypermutable aphidicolin-resistant chinese hamster cell line. | aphidicolin is a specific inhibitor of dna polymerase alpha and blocks dna synthesis in vivo. the inhibition of purified alpha-polymerase has been shown to be competitive with dctp but not with the other three deoxynucleoside triphosphates (dntps). in order to study the various roles that the alpha-polymerase might play in dna replication and/or repair, we have attempted to isolate chinese hamster v79 cells that are resistant to aphidicolin. four resistant mutants were isolated from brdu--black ... | 1981 | 6794164 |
| sister-chromatid exchanges are not directly related to 6-thioguanine-resistant mutations induced by ultraviolet radiation in v79 chinese hamster cells. | a comparison of the effects of caffeine on ultraviolet (uv)-induced sister-chromatid exchanges (sces) and 6-thioguanine-resistant (6-tgr) mutations was attempted in order to study how the sce mechanism correlates with mutagenesis. the linear uv dose-mutation relation indicated that the presence of 1mm caffeine during the 6-day expression period prior to the 6-tg selection did not alter the 6-tgr mutation induction rate. however, 1mm caffeine synergistically elevated the rate of uv-induced, immed ... | 1981 | 7274639 |
| inhibition of growth of proline-requiring chinese hamster ovary cells (cho-k1) resulting from antagonism by a system amino acids. | cho-k1 requires proline for growth. two proline-independent revertants were isolated--k1-j and k1-6. cho-k1 pro- is much more sensitive than the pro+ cell lines to inhibition of growth by addition to the medium of amino acids and amino acid analogues that are transported through the a system. in contrast, pro+ cells are as sensitive as, or in some cases slightly more sensitive than, pro- cells to glycine, basic amino acids, and to amino acids that are mainly transported by the l system. the a sy ... | 1981 | 7194346 |
| radiation-induced division delay in chinese hamster ovary fibroblast and carcinoma cells: dose effect and ploidy. | 1981 | 7193334 |