TitleAbstractYear(sorted ascending)
the action of transition metals on the genotoxicity of simple phenols, phenolic acids and cinnamic acids.simple phenols (catechol, 4-methyl catechol, resorcinol, phloroglucinol and pyrogallol), phenolic acids (p-hydroxybenzoic acid, protocatechuic acid, vanillic acid, gallic acid, syringic acid and salicylic acid), a phenylacetic acid (3,4-dihydroxyphenylacetic acid) and eugenol were assayed for clastogenic activity in chinese hamster ovary (cho) cells with and without the addition of a n s9 mixture, cu2+ (10-4m) and mn2+ (10-4m). all dihydroxylated and trihydroxylated phenolics induced chromatid b ...19817199376
selective toxicity of 5-(3,3-dimethyl-1-triazeno)imidazole-4-carboxamide toward hypoxic mammalian cells.the chemotherapeutic agent 5-(3,3-dimethyl-1-triazeno)-imidazole-4-carboxamide (dtic) is used in the treatment of malignant melanoma where response rates of 15 to 30% have been reported. some current interest exists in combining dtic chemotherapy with localized high-dose (800 rads)-per-fraction radiotherapy in the treatment of unresectable metastatic melanoma. the present work investigates the radiosensitizing and chemotherapeutic properties of dtic in an in vitro system using chinese hamster ov ...19817198008
the purification and immunocytochemical localization of the major iodinatable cell surface glycoproteins of chinese hamster ovary cells. 19817037801
the effect of hypo- and hypertonic nacl solutions on cellular damage resulting from combined treatments of heat and x-rays.the exposure of chinese hamster v79 cells to 0.05 or 1.5 m nacl immediately after combined treatment with heat and x-rays resulted in fixation of potentially lethal damage. the synergistic damage resulting from the interaction of heat and x-rays responded to anisotonic treatment like x-ray damage when heating was at 44.0 or 45.0 degrees c and like heat damage when heating was at 41.5 or 42.0 degrees c. when anisotonic treatment was given before heat plus x-ray exposure, sensitization occurred bu ...19816978300
poly(l-lysine) has different membrane transport and drug-carrier properties when complexed with heparin.methotrexate (mtx) conjugated to a mr 3000 poly(l-lys) markedly inhibits the growth of pro-3 mtxrii5-3 chinese hamster ovarian cells, a mutant line known to be drug resistant because of defective mtx transport. in these cells, membrane transport of [3h]mtx-poly(lys) is sharply decreased by addition of 0.5- to 2.5-fold heparin but remains at 15-20% of control in 2.5- to 50-fold heparin excess. heparin addition at first markedly inhibits but, at high concentration, restores the growth inhibitory e ...19816950400
a comparison of adriamycin and mamsa in vitro: cell lethality and sce studies.we have compared the actions of adm and mamsa in chinese hamster v79 cells in vitro, using cell survival and sister-chromatid exchange as end-points. equimolar concentrations of adm and mamsa show similar toxicities to exponentially growing cells, and both drugs are less effective in killing chronically hypoxic and plateau-phase cells. cytotoxicity to thermotolerant cells (41 degrees c for 16 h previously) shows little difference from that for exponential cells. pre-treating cells with misonidaz ...19816895696
early and late functions associated with the golgi apparatus reside in distinct compartments.enzymes that catalyze the two successive stages of golgi-associated processing of asparagine-linked oligosaccharides distributed differently when membranes from chinese hamster ovary cells were centrifuged in a sucrose density gradient. a mannosidase that removes only outer, alpha-1,2-linked mannose residues from the precursor oligosaccharides of the vesicular stomatitis viral g protein (to yield a "trimmed" oligosaccharide core) was separated from enzymes (galactosyl- and sialyltransferases) th ...19816801652
effects of short photoperiod on pituitary and testicular function in the chinese hamster, cricetulus griseus. 19816799010
effect of 7-con-o-methylnogarol on dna synthesis, survival, and cell cycle progression of chinese hamster ovary cells.the effect of 7-con-o-methylnogarol (7-omen) on the survival of exponentially growing and plateau-phase chinese hamster ovary cells was determined in a cloning assay. after 2 hr of exposure, the 50% lethal dose for exponential and plateau-phase cells was 0.3 and 1.5 microgram/ml, respectively. drug doses for cell progression studies were based upon drug lethality; therefore, higher doses were used for plateau than for exponential populations. the effect of 7-omen on cell progression was studied ...19816458356
effects of inhibitors of dna synthesis and protein synthesis on the rate of dna synthesis after exposure of mammalian cells to ultraviolet light.chinese hamster v-79 cells were treated with metabolic inhibitors o dna or protein synthesis for various intervals of time after exposure of 3.0 or 5.0 j m-2. after removal of the metabolic block(s) the rate of dna synthesis was followed by measuring the incorporation of [14c]thymidine into acid-insoluble material. a 2.5 or 5.0 h incubation with cycloheximide or hydroxyurea was effective in delaying the onset of the recovery in the rate of dna synthesis that normally becomes evident several hour ...19817306550
control of passive permeability of chinese hamster ovary cells by external and intracellular atp.external atp causes passive permeability change in several transformed cells, but not in untransformed cells. we studied the effect of external atp on the passive permeability of cho-k1 cells, a transformed clone of chinese hamster ovary cells. treatment of the cells with external atp alone did not produce a permeability change, and this was observed only when a mitochondrial inhibitor, such as rotenone or oligomycin, was present together with atp. these inhibitors reduced the concentration of i ...19817306546
[intraclonal heterogeneity and instability of cho-k1 chinese hamster cells in sensitivity to ultraviolet light and resistance to 8-azaguanine].the phenotypic instability of a 8-azaguanine (ag)-resistant clone a14--2c-1 was previously reported (abramyan et al., 1979) to be determined by genetic (replicative) instability. further, phenotype gene activity changes are characteristic of genetically instable "mutant", which may be "passed" from one locus to another. in the present work, some clones were isolated from clone a14-2c-1 differing in their sensitivity to lethal uv-radiation, lethal dose d37 differences being almost 6 times. during ...19817292604
biochemical and genetic characterization of respiration-deficient mutants of chinese hamster cells with a gal- phenotype.four chinese hamster somatic cell mutants a13g9, 34a13g32, 2a13g14, and v6ig15 with a gal- phenotype have the following characteristics: (1) a low respiration rate; (2) a reduced krebs cycle activity; (3) a low level of stimulation of oxygen consumption of mutant mitochondria by malate; (4) an absolute dependence on an ample supply of glucose to sustain a high rate of glycolysis; (5) a defect in the electron transport chain from nadh to coenzyme q; and (6) no appreciable activity of rotenone-sen ...19817292258
isolation and characterization of chinese hamster cell mutants resistant to the cytotoxic effects of chromate.stable mutants resistant to the toxic anion chromate have been isolated from a variety of chinese hamster cell lines. the mechanism of chromate toxicity is not known, but it must involve internalization via the sulfate transport pathway. all mutant lines had a defective sulfate transport system, showing a 10-fold reduction in the rate of uptake of radioactive sulfate into the cell. the chromate resistance phenotype in cho cell mutants behave recessively in somatic cell hybrids; in other cell lin ...19817292256
isolation and characterization of chinese hamster ovary cell mutants with altered sensitivity to high doses of tunicamycin.a mutant, ctm422, resistant to low dose of tunicamycin (tm) was isolated from chinese hamster ovary (cho) cells, and it showed 7- to 10-fold higher resistance to tm than cho. we further mutagenized ctm422, to isolate tm-high-resistant mutants which were resistant to about 100-fold higher dose of tm than cho. the tm-high-resistant mutants (n101 and n102) acquired about 4-fold higher cross-resistance to 2-deoxy-d-glucose than cho or ctm422, while both cho and ctm422 showed similar sensitivity to 2 ...19817292254
protection of heat induced cytoxicity by glycerol.glycerol, at concentrations of 2-10% is a potent hyperthermic (43 degrees - 45 degrees c)protector of cultured chinese hamster cells, v79. furthermore, the sensitization effect of low ph on heat death is also drastically reduced by the addition of glycerol into the culture medium. together with the known cellular effects of heat and the role of glycerol in various cellular structures and functions, the data suggest that microtubules and membranes may be involved in the expression of heat-induced ...19817287828
studies on the amount of single-stranded dna present in chinese hamster ovary cells during the repair of damage induced by x rays or methyl methanesulfonate. 19817280193
mutagenesis by chemical agents in v79 chinese hamster cells: a review and analysis of the literature. a report of the gene-tox program.the report reviews and evaluates the current literature (about 125 primary publications) on chemically induced specific locus mutations in the v79 chinese hamster lung cell line. the v79 cell is convenient to use for mutagenesis studies since it has a rapid growth rate, high plating efficiency, and a stable karyotype. mutation can be easily measured at either the hypoxanthine-guanine phosphoribosyl transferase or the na+/k+ atpase locus, both of which have been well characterized. other less-stu ...19817035931
structural and functional alterations in microtubule protein from chinese hamster ovary cell mutants.we have examined mutant lines of chinese hamster ovary cells that have increased resistance to the antimicrotubule drug colcemid. analysis of the functional properties of purified microtubule protein indicates that increased tolerance to the drug in vivo is reflected in altered properties of microtubules and tubulin in vitro. in this study, we have examined one series of related mutants and have found different microtubule alterations associated with each selection step. these changes include de ...19816946501
increased levels of threonyl-trna synthetase in a borrelidin-resistant chinese hamster ovary cell line.the growth of chinese hamster ovary cells in medium containing reduced concentrations of threonine is inhibited by borrelidin, a macrolide antibiotic. borrelidin-resistant clones have been isolated after ethyl methanesulfonate mutagenesis. one clone, 1c-1, has a 3-fold increased level of threonyl-trna synthetase [l-threonine:trnathr ligase (amp-forming), ec] as determined by both activity measurements and antiserum titrations. the levels of four other aminoacyl-trna synthetases and of tr ...19816946478
[gene mutation induction by benz(a)pyrene following metabolic activation].chinese hamster cells were made use of to study the effect of low doses of benz(a)pyrene on gene mutations during metabolic activation. the hgrpt mutant clones were selected on the basis of their resistance to 8-azaguanine. the raising of benz(a)pyrene concentration (from 5 g/ml) was followed by the enhanced mutagenic effect which was approximately 7-10 times greater than the spontaneous level at a concentration of 20-25 micrograms/kg.19816271305
transient activity of golgi-like membranes as donors of vesicular stomatitis viral glycoprotein in vitro.previous reports demonstrated that the vesicular stomatitis viral glycoprotein (g protein), initially present in membranes of a chinese hamster ovary mutant cell line (clone 15b) that is incapable of terminal glycosylation, can be transferred in vitro to exogenous golgi membranes and there glycosylated (e. fries and j. e. rothman, 1980, proc. natl. acad. sci. u. s. a. 77:3870-3874; and j. e. rothman and e. fries, 1981, j. cell biol. 89:162-168). here we present evidence that golgi-like membranes ...19816270159
[identification of isolated metaphase chromosomes. ii. a comparison with the recognizability of chromosomes in metaphase plates].the metaphase chromosomes (mc) isolated from the chinese hamster cells were identified with the aid of differential staining (g-bands). it was shown that differences in the relative recognizability of mc in metaphase plates and after their isolation are determined by changes in composition of isolated mc, rather than by those in staining capacity of mc after their isolation. the frequencies of identified mc are constant and independent upon the type of mc preparations and relation between identi ...19816170138
dna-mediated gene transfer of beta-aspartylhydroxamate resistance into chinese hamster ovary cells.cell lines that have high levels of resistance to beta-aspartylhydroxamate and elevated levels of asparagine synthetase activity were selected in two steps from chinese hamster ovary cells. resistance to beta-aspartylhydroxmate was transferred into sensitive cells by using total genomic dna derived from the dominant two-step mutants. the surviving colonies were characterized as transferants on the basis of transfer frequency, degree of resistance to beta-aspartylhydroxamate, increased level of a ...19816117859
antiproliferative activity of doxorubicin and aminoanthraquinone derivatives on chinese hamster ovary cells.a study of the antiproliferative activity of doxorubicin and several substituted aminoanthraquinone derivatives on chinese hamster ovary cells was conducted. doxorubicin and a derivative each inhibited cell proliferation at low concentrations, the latter being more potent than doxorubicin. a structure-activity relationship of these compounds is discussed in connection with an earlier postulated n-o-o triangulation hypothesis.19816101143
skin tumor-promoting activity of benzoyl peroxide, a widely used free radical-generating compound.benzoyl peroxide, a widely used free radical-generating compound, promoted both papillomas and carcinomas when it was topically applied to mice after 7,12-dimethylbenz[a]anthracene initiation. benzoyl peroxide was inactive on the skin as a complete carcinogen or as a tumor initiator. a single topical application of benzoyl peroxide produced a marked epidermal hyperplasia and induced a large number of dark basal keratinocytes, effects similar to those produced by the potent tumor promoter 12-o-te ...19816791284
formation of asymmetric phospholipid membranes via spontaneous transfer of fluorescent lipid analogues between vesicle populations.a method is presented for generating artificial lipid vesicles bearing an asymmetric distribution of either of the fluorescent lipid analogues 1-acyl-2-[6-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]caproyl]phosphatidylcholine or 1-acyl-2-[12[(7-nitro-2,1,3-benzoxadiazol-4-yl]amino]dodecanoyl]-phosphatidylcholine, in which the fluorescent lipid is located predominantly in either the outer or inner leaflet of the vesicle bilayer. the procedure is based on the observation that these lipid analogues u ...19817295659
actions of 3-deazaguanine and 3-deazaguanosine on variant lines of chinese hamster ovary cells. 19817295349
isolation of somatic cell mutants defective in the biosynthesis of in situ autoradiographic assay for cdp-ethanolamine:1,2-sn-diacylglycerol ethanolamine phosphotransferase (ec 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 ...19816267019
isolation of chinese hamster cell mutants defective in the receptor-mediated endocytosis of low density lipoprotein. 19816275086
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 ...19816170314
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 ...19819279382
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 ...19817327601
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 ...19817308664
isolation of hypoxanthine phosphoribosyltransferase-defective mutants in chinese hamster v79 cells by tritium suicide.tritium suicide was shown to be a highly efficient method for isolating mutants defective in hypoxanthine incorporation in the chinese hamster lung cell line v79. the tritium suicide procedure consisted of 3 kill cycles. survivors of one kill cycle were used for the next kill cycle. the kill cycles involved incorporation of [3h]hypoxanthine for 5 or 10 min, followed by storage of 3h-labelled cells at -70 degrees c for 4-10 days. 12 clones that survived the 3rd kill cycle were tested for incorpor ...19817278870
effect of different physiological conditions on the action of adriamycin on chinese hamster cells in vitro.chronically hypoxic cells were 5 times more resistant to adriamycin (adr) than exponentially growing oxic cells. on reoxygenation, resistance decreased slowly to reach the adr sensitivity of oxic cells after 24 h. with increasing ph, adr efficiency increased more in oxic than in chronically hypoxic cells. with increasing cell density, adr efficiency decreased linearly. the differences in adr efficiency under the various conditions were accompanied by differences in intracellular adr uptake. chro ...19817272189
combined radiation-protective and radiation-sensitizing agents: ii. radiosensitivity of hypoxic or aerobic chinese hamster fibroblasts in the presence of cysteamine and misonidazole: implications for the "oxygen effect" (with appendix on calculation of dose-modifying factors). 19817267995
chromosomal aberrations and sister-chromatid exchanges induced by gaseous nitrogen dioxide in cultured chinese hamster cells.effects of gaseous nitrogen dioxide (no2) on chromosomal morphology of cultured chinese hamster v79-h3 cells were investigated. chinese hamster cells were exposed to no2 gas in n2 gas at no2 concentrations of 0, 5, 10, 20, 50 and 100 ppm (v/v) for 10 min at a gas flow rate of 1000 ml/min. both chromosomal aberrations and sister-chromatid exchanges were increased depending on the no2 concentration. the effects of sodium nitrite (nano2) were also examined in comparison with those of gaseous no2, a ...19817197321
sister-chromatid exchange induction in chinese hamster ovary cells by 8-methoxypsoralen and brief pulses of laser light: assessment of the relative importance of 8-methoxypsoralen--dna monoadducts and crosslinks.brief (less than or equal to 20 nsec) 5-15 mj pulses of near-ultraviolet laser light were employed to promote, in a controlled manner, the reaction between 8-methoxypsoralen and the dna of chinese hamster ovary (cho) cells. according to johnston et al. [21], a single brief laser pulse should induce only monoadducts between 8 methoxypsoralen and dna, while multiple laser pulses are needed to induce 8-methoxypsoralen--dna crosslinks. in the present study, a single laser pulse was found sufficient ...19817196990
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 ...19816974144
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 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 ...19816946445
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 ...19816794566
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 ...19816168277
histones h1(o)a and h1(o)b are the same as cho histones h1(iii) and h1(iv): new features of h1(o) phosphorylation during the cell cycle.two histone h1 fractions [h1(i) and h1(ii)] and two histone h1(o) fractions (h1(o)a and h1(o)b) have been isolated from butyrate-treated chinese hamster (line cho) cells by guanidine hydrochloride gradient chromatography on bio-rex 70 ion-exchange resin. the fractions have been identified by electrophoresis and amino acid analyses. electrophoretic analysis of cyanogen bromide treated h1(o) in long acid-urea-polyacrylamide gels suggests that h1(o)a and h1(o)b differ, at least, within the 20-30 re ...19817284339
sensitivity of a mutator gene in chinese hamster ovary cell to deoxynucleoside triphosphate pool alterations.the thy- mutants of chinese hamster ovary cells have a 5- to 10-fold elevated pool of deoxycytidine 5'-triphosphate (dctp) and are auxotrophic for thymidine as an apparent consequence of a single mutation. thy is also a mutator gene, elevating the spontaneous rate of mutation 5- to 200-fold for at least two genetic markers. previous experiments suggested that this mutator activity was caused by the elevated pool of dctp in thy- cells. to test this, the dctp and deoxythymidine 5'-triphosphate (dt ...19819279378
cell cycle parameters of chinese hamster ovary cells during exponential, polyamine-limited growth.we have previously shown that chinese hamster ovary cells made polyamine deficient by treatment with alpha-methylornithine, an inhibitor of ornithine decarboxylase, grow exponentially in culture at low densities at one-half the rate observed in untreated (control) cultures. in this study, the cell cycle of polyamine-limited cells was examined by using thymidine autoradiography, mitotic index analysis, and fraction labeled mitoses analysis. we found that the longer doubling time of inhibitor-trea ...19819279373
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 ...19817318929
[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 ...19817295949
[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 ...19817281231
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 ...19817196493
giant cell formation produced by laser microbeam irradiation of chromatin in chinese hamster cells. 19817195821
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 ...19817018670
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 ...19816945588
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 ...19816894713
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- ...19816286232
metabolism of 9-beta-d-xylofuranosyladenine by the chinese hamster ovary cell. 19816270533
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 ...19816265473
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 ...19816166368
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 ...19817272307
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 ...19817240205
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 ...19817240203
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 ...19817240196
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 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 and one of them had apparently normal amounts of kinase activity. glycogen synthase activity was present in comparable amounts in ...19816266497
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 ...19817240147
metabolism of ubiquitinated 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 ...19816263895
[the frequency of sister chromatid exchanges in v79 chinese hamster cells exposed to heavy metals]. 19817316766
cytosolic 25-hydroxycholesterol binding activity of chinese hamster ovary cells. 19817283442
laser-uv-microirradiation of chinese hamster cells: the influence of the distribution of photolesions on unscheduled dna synthesis. 19817280047
[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 ...19817272495
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 ...19817248467
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. 19817244125
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 ...19817237030
the effects of fibronectin on the adhesion and migration of chinese hamster ovary cells on collagen 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 ...19817198128
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 ...19817196496
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 ...19817195909
a comparison of the fixation of x-ray or heat damage in chinese hamster cells exposed to anisotonic salt solutions. 19816972934
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 ...19816972928
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.19816965109
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 ...19816965107
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 ...19816943579
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 ...19816790977
carboxyl terminal tyrosine metabolism of alpha tubulin and changes in cell shape: chinese hamster ovary cells. 19816271126
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 ...19816266650
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 ...19816166628
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 ...19817225383
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 ...19817300845
[autoradiography of the dna of lysed, uv-irradiated cells in chinese hamster cultures differing in uv sensitivity]. 19817256858
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. 19817242556
analysis of vinblastine-sensitive sites in certain g-banded chromosomes of d-6 cells of the chinese hamster. 19817242553
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 ...19817241517
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 ...19817197403
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 ...19817197402
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 ...19817195908
kinetics of mutation and sister-chromatid exchange induction by ethyl methanesulfonate in chinese hamster ovary cells. 19817195461
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 ...19817194152
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 ...19817194140
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 ...19817016329
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 ...19816972363
gamma radiation inhibits the appearance of induced ornithine decarboxylase activity in chinese hamster cells.ornithine decarboxylase activity of chinese hamster cells (odc, ec 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 ...19816972362
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 ...19816785129
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