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a mutant of chinese hamster ovary cells resistant to alpha-methyl- and alpha-difluoromethylornithine.we describe a mutant of chinese hamster ovary cells which is resistant to elevated levels of alpha-methylornithine and alpha-difluoromethylornithine, reversible and enzyme-activated irreversible inhibitors, respectively, of the enzyme ornithine decarboxylase (odc). the mutant cells have significantly elevated levels of enzyme activity compared to wild-type cells, but several of the physical parameters of the enzyme are completely normal: michaelis-menten parameter, km, affinity for the analog, a ...19816794163
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 ...19817225286
modulation of surface proteins by calcium in chinese hamster lung cells. 19817202558
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 ...19817197401
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 ...19817195982
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. 19817022191
laser microirradiation of chinese hamster cells at wavelength 365 nm: effects of psoralen and caffeine. 19817010411
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 ...19816965100
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 ...19817213739
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 ...19816783122
response of chinese hamster ovary cells to anticancer drugs under aerobic and hypoxic conditions. 19817470389
elastatinal and leupeptin: effects on u.v.-induced mutation and sister-chromatid exchanges in chinese hamster cells.microbial protease inhibitors elastatinal and leupeptin were tested for cytotoxicity and for effects on spontaneous and u.v.-induced 6-thioguanine-resistant (6tgr) mutation and sister-chromatid exchange (sce) in v79 chinese hamster cells. continuous treatment with elastatinal exhibited marked cytotoxicity, while leupeptin was almost non-cytotoxic. elastatinal rapidly induced cytotoxic effects as a function of its concentration and time of exposure. near maximum cytotoxicity was reached after exp ...19817273311
investigation of the effects of the phorbol ester tpa on carcinogen-induced forward mutagenesis to 6-thioguanine-resistance in v79 chinese hamster cells.12-o-tetradecanoyl-phorbol-13-acetate (tpa) was tested for its effect on n'-methyl-n'-nitro-n-nitrosoguanidine (mnng) induced forward mutagenesis to 6-thioguanine resistance (6tgr) in v79 chinese hamster cells. using a replating assay, no effect of tpa on the recovery of 6tgr mutants was observed. previous reports of tpa enhancement of carcinogen-induced forward mutagenesis using the in situ mutagenesis assay, can be explained in terms of the influence of metabolic co-operation on mutant recover ...19817273287
[comparative studies on the radiosensitizing action of 4-nitroimidazole and metronidazole (author's transl)].after the 2-nitroimidazole derivatives, misonidazole, and the 5-nitroimidazole derivative, metronidazole, had been tried in clinical radiotherapy, it seemed necessary to test substances from the group of 4-nitroderivatives of the imidazole on their effectiveness as hypoxic radiosensitizers. therefore, the influence of 1-(2'-hydroxyethyl)-2-methyl-4-nitroimidazole vs. metronidazole on the semiconservative dna synthesis prior to the following irradiation on leukemia cells l5178y, on the reproducti ...19817271431
inhibition of metabolic cooperation between mammalian cells in culture by tumor promoters.the influence of phorbol-related tumour promoters and non-promoters on metabolic cooperation between wild-type and mutant chinese hamster cells has been studied. the recovery, in medium containing 8-azaguanine, of hypoxanthine phosphoribosyl transferase-deficient (hprt-) v79 cells co-cultured with an excess (2 x 10(6) per 9 cm petri-dish) of wild-type cells was determined in the presence and absence of each compound. under the latter conditions (solvent treatment only) metabolic cooperation cons ...19817273309
pretreatment of chinese hamster v79 cells with mnu increases survival without affecting dna repair or mutagenicity.exposure of chinese hamster v79 cells to a non-toxic dose of n-methyl-n-nitrosourea, followed at intervals by exposure to toxic challenging doses of the same agent, resulted in increased survival of colony forming ability when these cells were compared with matched control cells that only received the challenging dose. the extent of the increase was dependent on the time interval between exposures, and rose to a maximum of about two-fold 5 days after the initial dose, declining slowly to control ...19817273289
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 ...19817448783
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.19817296528
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 ...19817274639
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 ...19817194346
radiation-induced division delay in chinese hamster ovary fibroblast and carcinoma cells: dose effect and ploidy. 19817193334
n-carbamoyloxyurea-resistant chinese hamster ovary cells with elevated levels of ribonucleotide reductase activity.we describe the isolation and characterization of a chinese hamster ovary cell line selected for resistance to n-carbamoyloxyurea. using the mammalian cell permeabilization assay developed in our laboratory, a detailed analysis of the target enzyme, ribonucleotide reductase (ec 1.17.4.1), was carried out. both drug-resistant and parental wild-type cells required the same optimum conditions for enzyme activity. the ki values for n-carbamoyloxyurea inhibition of cdp reduction were 2.0 mm for ncr-3 ...19817012160
effect of membrane lipid perturbers on the temperature dependence of repair of sublethal and potentially lethal radiation damage.the repair of sublethal radiation damage (sld) in chinese hamster (v79) cells was investigated as a function of temperature in the presence and absence of the membrane lipid perturbers, butylated hydroxytoluene (bht) or adamantanone, which decrease the viscosity of the membrane lipids. addition of 0.01 mm bht to the cells significantly increased the amount of repair of sld over controls from 0 to 25 degrees c but not from 30 to 37 degrees c. the amount of repair of sld decreased as a function of ...19816971830
chinese hamster polyadenylated messenger ribonucleic acid: relationship to non-polyadenylated sequences and relative conservation during messenger ribonucleic acid processing.we have further analyzed the metabolism of specific messenger ribonucleic acid (mrna) sequences within the cytoplasmic and nuclear rna of chinese hamster ovary (cho) cells by using a set of previously constructed complementary deoxyribonucleic acid (dna) clones (harpold et al., cell 17:1025-1035, 1979) as specific molecular probes in a variety of rna:dna hybridization experiments. the majority of the labeled mrna complementary to each of the nine clones was found in the polyribosomes, with some ...19816152853
large heterogeneous nuclear ribonucleic acid has three times as many 5' caps as polyadenylic acid segments, and most caps do not enter polyribosomes.the rate of synthesis in chinese hamster cells of 5' cap structures, m7 gpppnmp, in large (greater than 700 bases) heterogeneous nuclear ribonucleic acid (rna) molecules is two to three times faster than the synthesis of 3'-terminal polyadenylic acid segments. as judged by presence of caps, newly synthesized polysomal messenger rna, exclusive of messenger rna the size of histone messenger rna, is more than 90% in the polyadenylated category. it appears, therefore, that between half and two-third ...19816152852
the overall morphology of neuromuscular junctions as revealed by scanning electron microscopy.skeletal neuromuscular junctions (nmjs) of vertebrates were examined by scanning electron microscopy after removal of connective tissue components by hcl hydrolysis. in addition to the surface texture of nmjs, the subsynaptic organization of the sarcolemma was visualized in specimens in which nerve endings were detached from the muscle surface. a remarkable morphological variability between animal species was observed. the nmjs in the frog sartorius muscle consisted of longitudinal ribbon-like e ...19816118394
cyclic amp-dependent phosphorylation in intact cells and in cell-free extracts from chinese hamster ovary cells. studies with wild type and cyclic amp-resistant mutants. 19816256374
characterization of cyclic amp-resistant chinese hamster ovary cell mutants lacking type i protein kinase.a group of three mutants of chinese hamster ovary cells (10260, 10265, and 10223) which are resistant to cyclic amp (gottesman, m. m., lecam, a., bukowski, m., and pastan i. (1980) somatic cell genet. 6, 45-61) have been characterized in this work. by genetic analysis, these mutants are all recessive and fall into two complementation groups. cycl amp-stimulated protein kinase activity in crude extracts of these mutants using histone as a substrate is decreased to 10 and 7% (complementation group ...19816256373
phosphorylation of nuclear and dna-binding proteins in proliferating and quiescent mammalian cells.the dependence of cell proliferation on nuclear protein phosphorylation was studied with exponential-phase and stationary-phase cultures of chinese-hamster ovary cells. nuclear proteins were fractionated, according to their dna-binding affinities, by using sequential extractions of isolated nuclei with increasing concentrations of nacl. when viable whole cells were labelled with h332po4, phosphorylation of nuclear proteins was found to be lower in quiescent cells than in proliferating cells. pho ...19816272725
recovery of chinese hamster cells from mercuric chloride exposure.the effects of chronic treatments with hgcl2 on cell survival, dna replication, and cell progression in cultured chinese hamster ovary cells were investigated. the ability of these cells to recover from the effects was also characterized. exposure of cells to 4 x 10(-5) m hgcl2 for 30 min killed about 50% of the cells, and this proportion did not increase with continued exposure up to 24 h. the rate of dna replication was reduced to 28% of the control rate in the presence of hgcl2. however, when ...19817265301
isolation and partial characterization of mutagen-sensitive and dna repair mutants of chinese hamster fibroblasts.through a new approach, we have sought to isolate ultraviolet light (uv)-sensitive and dna repair mutant chinese hamster fibroblasts. the procedure consisted of 1) mutation induction by 5-bromodeoxyuridine (brd u)-blacklight and uv treatments; 2) incorporation of 3h-thymidine in repair-proficient cells at high temperature (38.5 degrees c) following uv damage; 3) cold holding (4.0 degrees c) of these cells to induce tritium killing; and 4) recovery and testing of repair-deficient and uv-sensitive ...19817262053
topographic examination of sister chromatid differential staining by nomarski interference microscopy and scanning electron microscopy.brdu-substituted chinese hamster chromosomes were treated with a hog na2hpo4 solution and stained with giemsa to produce sister chromatid differential staining (scd). the process of scd was examined with the nomarski differential interference microscope and the scanning electron microscope. after the na2hpo4 treatment alone, unifilarly brdu-substituted (tb) chromatids appeared somewhat more severely collapsed than the bifilarly substituted (bb) chromatids. subsequent giemsa staining, however, br ...19817261710
localization and metabolic activity of ribosomal genes in chinese hamster meiotic and mitotic chromosomes. 19817261681
morphometric analysis of autonomic neuropathology in the abdominal sympathetic trunk of the ketonuric diabetic chinese hamster.fibers from the infradiaphragmatic portion of the sympathetic trunk of ketonuric diabetic chinese hamsters were quantitatively analyzed by light and electron microscopy to determine frequency distribution and numerical density. myelinated and unmyelinated fibers displayed a significant reduction in diameter which was exacerbated by increased duration of ketonuria. mean numerical density of myelinated fibers was reduced whereas that of unmyelinated fibers was increased. the alterations in sympath ...19817223372
the accumulation of three specific proteins related to glucose-regulated proteins in a temperature-sensitive hamster mutant cell line k12.a temperature-sensitive mutant k12 isolated from an established line of chinese hamster fibroblasts has been identified as a cell-cycle mutant blocked in g1 (roscoe et al., '73a,b). while characterizing the phenotype of k12 in more detail, we observed that k12 cells are highly sensitive to the concentration of glucose in the culture medium as well as the temperature of incubation. although overall cellular metabolism remains intact for at least 24 hours after shifting the cells to the nonpermiss ...19817204505
the potentiation of adenine toxicity to chinese hamster cells by coformycin: suppression in mutants with altered regulation of purine biosynthesis or increased adenylate-deaminase activity.when added to medium containing coformycin (2 microm or above), adenine is lethal to chinese hamster fibroblasts at the concentration inhibiting de novo purine biosynthesis (debatisse and buttin, '77b). rescue by hypoxanthine suggested that cells die of imp starvation when the analog can turn off deamination of both adenosine and adenylate. as predicted from this hypothesis, two classes of variants resistant to the mixture of coformycin + adenine have been isolated: class 1 variants have altered ...19817204504
[chinese hamster cells mutant for the hypoxanthine-guanine phosphoribosyltransferase locus. ii. characteristics of the hybrids revealing intragenic complementation].after polyethylene glycol treatment of gprt- mutant cells, 12 clones were isolated on the atg medium showing intragenic complementation. karyological analysis confirmed the hybrid nature of the clones isolated. the gprt activity in the hybrid clones, as assessed in vitro, exceeded the sum of parental activities. in vivo incorporation of 14c-hypoxanthine showed the gprt activity in the hybrids to be an order of magnitude higher than in the mutant parental cells. moreover, the gprt activity in the ...19817198601
stage-dependent changes of chromosomal radiosensitivity in primary oocytes of the chinese hamster. 19817197612
structure of kinetochore fibers: microtubule continuity and inter-microtubule bridges.to understand how microtubules interact in forming the mitotic apparatus and orienting and moving chromosomes, the precise arrangement of microtubules in kinetochore fibers in chinese hamster ovary cells was examined. individual microtubules were traced, using high voltage electron microscopy of serial 0.25 micron sections, from the kinetochore toward the pole. microtubule arrangement in kinetochore fibers in untreated mitotic cells and in cells recovering from colcemid arrest were similar in tw ...19817196830
the effect of 1 mhz ultrasound on the proliferation of synchronized chinese hamster v-79 cells. 19817256977
simultaneous exposure of chinese hamsters to ethanol and cigarette smoke: cytogenetic aspects.chinese hamsters (cricetulus griseus) were treated with ethanol, with cigarette smoke and with both. during the experimental period of 12 weeks a control group of animals (c) received water ad libitum, another water drinking group received a cigarette smoke treatment during the last 4 weeks (s). another group received 20% (v/v) ethanol during the whole experimental period as the only liquid supply (e), and one group with the same ethanol treatment was simultaneously treated with cigarette smoke ...19817256788
cleavage of cell surface proteins by thrombin.this study was based on our previous findings that the mitogenic action of thrombin on cultured fibroblasts can result from interaction of thrombin with the cell surface in the absence of internalization, and that the proteolytic activity of thrombin is required for stimulation of cell division. this prompted us to look for thrombin-mediated cleavages using 2-dimensional gel electrophoresis of labeled cell surface proteins. surface membrane components were labeled by 3 procedures: 1) proteins we ...19817253649
a system for determining the pharmacology of indirect radiation sensitizer drugs on multicellular spheroids.we have characterized some of the physiology of multicellular spheroids of different sizes grown from chinese hamster lung fibroblast (v79) cells. among the parameters studied were oxygen tension distributions within the spheroid. this was achieved using ultramicroelectrodes with tip diameters of 1-5 mu and a perfusion system whereby environmental conditions such as flow, temperature, and chemical makeup of the milieu could be measured and controlled. plateau po2 values of less than 10 mm hg wer ...19817249257
the mutation studies of mutagen-sensitive and dna repair mutants of chinese hamster fibroblasts.we have previously reported the isolation and partial characterization of dna repair and/or mutagen-sensitive mutant chinese hamster cell strains. here we present the results of a detailed study of the ultraviolet light (uv)-induced mutability of one of these strains, uvs-7, and provide preliminary mutability data on two additional lines, uvr-23 and uvs-40. uvs-7 in extremely deficient in unscheduled dna synthesis (uds) but only slightly more sensitive to uv than the parental line. when examined ...19817238440
single-stranded molecules in dna preparations from cultured mammalian cells at different moments of cell cycle.long single-stranded dna molecules have been observed at electron microscope in dna preparations from synchronized chinese hamster cells. the amount of single strandedness in parental dna increases following a prolonged block of dna synthesis by hydroxyurea as judged by the results obtained using an improved hydroxyapatite chromatography (hanania et al., 1975). as far as newly replicated dna is concerned, an increase of the single strand amount has been observed in dna preparations from cells ac ...19817227043
protein-depleted chromosomes. i. structure of isolated protein-depleted chromosomes.protein-depleted isolated chinese hamster chromosomes have been obtained by different protein extraction procedures and examined by electron microscopy and sds-polyacrylamide gel electrophoresis. salt-resistant centromeric and telomeric structures are visible in protein-depleted chromosomes and the protein-depleted chromosomes appear to have a regular, longitudinal pattern in critical point dried preparations. the scaffold-like structure of protein-depleted chromosomes is highly affected by the ...19817196312
[patterns in the x-ray induction of mutations in resistance to 5-thioguanine in chinese hamster cell cultures studied using cysteamine].x-ray induction of 5-thioguanine resistance mutations and the protective effect of cysteamine were studied in cultured cells of chinese hamster clone 431. expression of mutations was studied for 8--10 days of post-irradiated growth, when cells surviving radiation at doses 200, 400, 600, 800 r were passing from 3 to 12 generations. the maximum frequency of induced mutations was found after 3-5 generations. after reaching the maximum, the number of registered mutations decreased with the number of ...19817195858
amplification and loss of dihydrofolate reductase genes in a chinese hamster ovary cell line.during stepwise increases in the methotrexate concentration in culture medium, we selected chinese hamster ovary cells that contained elevated dihydrofolate reductase levels which were proportional to the number of dihydrofolate reductase gene copies (i.e., gene amplification). we studied the dihydrofolate reductase levels in individual cells that underwent the initial steps of methotrexate resistance by using the fluorescence-activated cell sorter technique. such cells constituted a heterogeneo ...19817346712
antiproliferative activity of protocatechualdehyde on chinese hamster cells grown in culture.the mode of cytotoxic action of protocatechualdehyde on v79 cells was examined. the cytotoxicity of protocatechualdehyde on v79 cells was time- and cell cycle-dependent. the lethal action is selective for the cells at s phase only. the cells lethally damaged at s phase seemed to complete their dna synthesis, although the rate of dna synthesis became lower and the duration of s phase was prolonged. some cells arriving at g2 phase directly entered the next s phase without cell division and died of ...19817341336
induction of chromosome shattering by ultraviolet irradiation and caffeine: comparison of whole-cell and partial-cell irradiation.synchronized and asynchronously growing cells of a v79 sub-line of the chinese hamster were either whole-cell irradiated ( gamma, 254 nm) or laser-uv-microirradiated ( gamma, 257 nm). post-incubation with caffeine (1-2 mm) often resulted in chromosome shattering, which was a rare event in the absence of this compound. in experiments with caffeine, the following results were obtained. shattering of all the chromosomes of a cell (generalized chromosome shattering, gcs) was induced by whole-cell ir ...19817335101
metabolism and intracellular localization of a fluorescently labeled intermediate in lipid biosynthesis within cultured fibroblasts.in this paper we report on the uptake and distribution of an exogenously supplied fluorescent phosphatidic acid analogue by chinese hamster fibroblasts. under appropriate in vitro incubation conditions, 1-acyl-2-(n-4-nitrobenzo-2-oxa-1,3-diazole)-aminocaproyl phosphatidic acid was rapidly and preferentially transferred from phospholipid vesicles to cells at 2 degrees c. however, unlike similar fluorescent derivatives of phosphatidylcholine and phosphatidylethanolamine that remain restricted to t ...19817328126
centriole cycle in chinese hamster ovary cells as determined by whole-mount electron microscopy.in interphase chinese hamster ovary (cho) cells, the centrosome is attached to the nucleus very firmly. this nuclear-centrosome complex is isolated as a coherent structure by lysis and extraction of cells with triton x-100 in a low ionic strength medium. under these conditions, the ultrastructure of the centrioles attached to the nucleus can be discerned by electron microscopy of whole-mount preparations. the structural changes of the centrioles as a function of the cell cycle were monitored by ...19817328123
the induction of sister-chromatid exchanges in chinese hamster ovary cells by k-region epoxides and some dihydrodiols derived from benz[a]anthracene, dibenz[a,c]anthracene and dibenz[a, h]anthracene.experiments were performed to investigate the effects of 3 polycyclic aromatic hydrocarbons, benz[a]anthracene, dibenz[a,c]anthracene and dibenz[a,h]anthracene and k-region epoxides and some of their related dihydrodiols on the chromosomes of chinese hamster ovary cells in vitro. of the 3 hydrocarbons only benz[a]anthracene showed any activity in inducing sister-chromatid exchanges. the k-region epoxide and the 3,4-dihydrodiol have been found to be more active than the corresponding k-region or ...19817199618
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
mutagenicity and cytotoxicity of haloethanes as studied in the cho/hgprt system.when haloethanes were being tested as direct-acting agents in the chinese hamster ovary cell/hypoxanthine-guanine phosphoribosyl transferase (cho/hgprt) system, ethylene dibromide (etbr2) exhibited more cytotoxic and mutagenic activity than ethylene dichloride (etcl2), and the mixed halogenated congener ethylene bromochloride (etbrcl) had an intermediate effect. on a molar basis, the relative mutagenic activity of etbr2 : etbrcl : etcl2 was approximately 100 : 6 : 1. cell survival was reduced to ...19817035935
accessibility of metaphase chromosomes from chinese hamster ovary cells to dnase ii. 19816271596
quantitative aspects of the formation and loss of dna interstrand crosslinks in chinese hamster cells following treatment with cis-diamminedichloroplatinum(ii) (cisplatin). ii. comparison of results from alkaline elution, dna renaturation and dna sedimentation studies.the formation of interstrand crosslinks in the dna of cis-diamminedichloroplatinum(ii) (cisplatin)-treated chinese hamster cells has been demonstrated by three independent, highly sensitive techniques: namely those of alkaline elution, renaturation of crosslinked dna and alkaline sucrose gradient velocity sedimentation. simultaneous measurement of dna break frequency by the first two methods and a computer model combined with the third enabled the calculation of crosslink frequency after applica ...19816169370
enhanced radiation-induced killing of chinese hamster cells by dideoxythymidine. 19817302124
induction of sister chromatid exchanges and chromosome aberrations in cultured mammalian cells by n-nitrosocimetidine.n-nitrosocimetidine (nc) induces significant numbers of sister chromatid exchanges (sce) and chromosome aberrations in cultured chinese hamster ovary (cho) cells even at a concentration of 1.2 x 10(-7) m. its effectiveness in sce induction is about two thirds that of the gastric carcinogen n-methyl-n'-nitro-n-nitrosoguanidine (mnng). these results constitute further evidence that nc possesses carcinogenic activity.19817296544
wound healing in normal and diabetic chinese hamsters.wound healing was examined in normal and diabetic, non ketotic chinese hamsters by morphological and morphometric methods. dermal, perforating wounds were made in the ears of the hamsters and the response to injury was evaluated in tissue biopsies. the response in normal hamsters was characterized by vascular and cellular migration and pronounced infiltration of polymorphonuclear leukocytes into the area closest to the wound (zone 1). the transition region (zone 2) between wounded and non-wounde ...19817286499
reversal of resistance to methotrexate by hyperthermia in chinese hamster ovary cells.our chinese hamster ovary cells are extremely resistant to methotrexate (mtx) (100% survival after 500 microgram/ml for 13 hr). however, exposure to 43 degrees (but not 41 degrees or 42 degrees) for 1 hr sensitizes the cells to mtx so that a 50% cell kill in excess of that due to hyperthermia occurs. treatment of cells at 43 degrees increases net mtx uptake by about 30% at 30 min but causes a substantial reduction after 1 hr. this negative effect is greater in cells continually heated at 43 degr ...19817284991
selection of mutant chinese hamster ovary cells altered glycoproteins by means of tritiated fucose suicide.mutant chinese hamster ovary cells altered in glycoproteins have been isolated by selecting for ability to survive exposure to [6-3h]fucose. mutagenized wild-type cells were permitted to incorporate [3h]fucose to approximately 1 cpm of trichloroacetic acid-insoluble radioactivity per cell and then frozen for several days to accumulate radiation damage. the overall viability of the population was reduced by 5- to 50-fold. four consecutive selection cycles were carried out. the surviving cells wer ...19817202113
effects of retinoids on plating efficiency, sister-chromatid exchange (sce) and mitomycin-c-induced sce in cultured chinese hamster cells.the effects of 5 retinoids, namely, all-trans-retinol (rol), all-trans-retinoic acid (ra), all-trans-retinal (ral), all-trans-retinyl acetate (rac), and ro. 10-9359-tmmp ethyl retinoate on plating efficiency, sister-chromatid exchange (sce) and on mitomycin-c (mmc)-induced sce were studied in chinese hamster v79 cells. all the retinoids caused reduction of plating efficiency in a dose-dependent manner but the degree of plating efficiency reduction varied considerably among the retinoids studies. ...19817199117
regulation of ribonucleotide reduction by deoxyribonucleotides in intact chinese hamster ovary cells.the ribonucleotide reductase model of thelander and reichard, which is based on studies of the purified enzyme, has been tested in cultured chinese hamster ovary k-1 cells. deoxyribonucleoside triphosphate concentrations were manipulated by the use of drugs or naturally occurring deoxyribonucleosides, and ribo- and deoxyribo-nucleoside triphosphate concentrations were measured. the results are consistent with the hypothesis that dttp inhibits cdp reduction and stimulates gdp reduction, and that ...19817032674
effects of altered ribonucleotide concentrations on ribonucleotide reduction in intact chinese hamster ovary cells.the effect of changes in ribonucleoside triphosphate concentrations on those of deoxyribonucleotides has been determined in chinese hamster ovary k-1 cells. ribonucleoside triphosphate concentrations were manipulated by the use of drugs or naturally occurring purines or pyrimidines. changes in the concentration of each ribonucleoside triphosphate led to changes in the concentration of each corresponding deoxyribonucleoside triphosphate. the relationships between the concentrations of ctp and dct ...19817032673
most of the g1 period in hamster cells is eliminated by lengthening the s period.two chinese hamster cell lines, g1+-1 and cho, have been grown in the presence of low concentrations of hydroxyurea to determine how a slowing dna synthesis (i.e., a lengthening of the s period) affects the length of the g1 period. hydroxyurea concentrations of approximately 10 microm do not alter the generation times of these cell lines but do cause increases in s with corresponding decreases in g1. in both cell lines, 10 microm hydroxyurea reduces g1 to an absolute value of 1 hr, which represe ...19816947230
low molecular weight rnas transcribed in vitro by rna polymerase iii from alu-type dispersed repeats in chinese hamster dna are also found in vivo.an alu-type dispersed repeat previously identified in a cloned fragment of chinese hamster dna [haynes, s. r., toomey, t. p., leinwand, l. & jelinek, w. r. (1981) mol. cell. biol. 1, 573-583] serves as a template for cell-free transcription of discrete low molecular weight rnas by rna polymerase iii [rna nucleotidyltransferase (dna-directed), ec 2.7.7.6]. a class of analogous rnas has been isolated from growing chinese hamster cells by hybridization of total low molecular weight nuclear rnas to ...19816796957
replication of viral dna sequences integrated within the chromatin of sv40-transformed chinese hamster lung cells.to determine when during s phase integrated viral dna sequences in several tsa sv40-transformed chinese hamster cell clones replicate, we pulse-labeled cultures with brdurd and subsequently collected mitotic cells during sequential time intervals. restriction endonuclease mapping indicated that each of the three sv40-transformed chinese hamster lung cell clones contained a single viral dna sequence at a different, but in each case unique, chromosomal site. dna was extracted from each population ...19816277496
regulation of carbohydrate metabolism in cultured mammalian cells: energy provision in a glycolytic mutant.the metabolism of radioactively labelled d-glucose, l-glutamine, and l-glutamate has been determined in a glycolytic mutant of chinese-hamster ovary cells, r1.1.7, and in its parent, cho-k1. the complete oxidation of glucose via the tca-cycle is negligible in both cell types, but there is significant oxidation of carbon-1. cho-k1 cells derive most of their energy from glycolysis and are independent of respiration in the short term. r1.1.7 cells are respiration-dependent and are rapidly killed by ...19816118187
quantitative aspects of the formation and loss of dna interstrand crosslinks in chinese hamster cells following treatment with cis-diamminedichloroplatinum(ii) (cisplatin). i. proportion of dna-platinum reactions involved in dna crosslinking.the presence of interstrand crosslinks in the dna of cis-diamminedichloroplatinum(ii) (cisplatin)-treated chinese hamster cells was demonstrated by the formation of a species of hybrid-labelled dna in cells that had been density and radioactively prelabelled with a combination of [3h]thymidine and 2'-deoxy-5-bromouridine (brdurd) prior to treatment. the extent of crosslinking and of total binding of platinum to the dna increased linearly with dose over a wide range of concentrations of cisplatin ...19817197159
genetic analysis of tumorigenesis: ix suppression of anchorage independence in hybrids between transformed hamster cell lines.in many hybrid cell systems fusion of normal cells to tumorigenic cells suppresses the transformed phenotype. we have now examined the expression of anchorage independence, one characteristic of the transformed phenotype, in hybrids between different anchorage-independent chinese hamster fibroblasts. examination of many different crosses was facilitated by a rapid screening procedure. instead of isolating individual hybrid clones, the fraction of hybrid cells that were anchorage independent was ...19817323949
flurbiprofen, a non-steroid anti-inflammatory agent, protects cells against hypoxic cell radiosensitizers in vitro.overnight exposure of chinese hamster cells (v79-753b) to 5 x 10(-5) m flurbiprofen (2-(2-fluoro-4-biphenyl)propionic acid) in vitro reduced the cytotoxic effects of misonidazole, 1-methyl-4-nitro-5-phenoxysulphonylimidazole (nsc 38087) and nitrofurantoin, both in air and in hypoxia at 37 degrees c. flurbiprofen did not alter the cells' uptake of 14c-misonidazole, nor did it affect the radiosensitivity of aerobic or anaerobic cells, or the degree of hypoxic-cell radiosensitization produced by th ...19817317272
the extent of histone acetylation induced by butyrate and the turnover of acetyl groups depend on the nature of the cell line.cells possessing widely different physiological and morphological features have been treated with substances known to stimulate the differentiation of erythroleukemia cells. only short fatty acids are capable of causing a hyperacetylation of the core histones and of enhancing the level of an h1-like protein in chinese hamster ovary cells. while the time courses of a butyrate-mediated acetylation are similar for all cells, the maximum histone acetyl contents are much higher for the transformed ce ...19817308217
the effect of combinations of nitroaromatic and nitroxyl radiosensitizers on the radiation survival response of chinese hamster cells, v.79-753b, in vitro. 19817302142
the effect of reduced ph on the induction of thermotolerance.the effect of low ph on thermotolerance induction was studied in chinese hamster ovary cells. the thermotolerance ratio (ttr), defined as the ratio of the do of a subsequent heat survival curve following heat challenge to the do of the single-dose heat survival curve, was found at ph 7.2 to be maximal at 3.6 seven hours following a 10-min 45 degrees initial heat dose. when heating and induction times were at ph 6.6, the ttr ws reduced to 3.1. when the ph was reduced to 6.6 only during the induct ...19817291581
contribution of incorporated 5-bromodeoxyuridine in dna to the frequencies of sister-chromatid exchanges induced by inhibitors of poly-(adp-ribose)-polymerase.3-aminobenzamide and benzamide, two potent inhibitors of poly-(adp-ribose)-polymerase increase the frequencies of sces in chinese hamster ovary cells in a dose-dependent manner. sces were studied in cells in which the inhibitors were present either during the first cell cycle or the second cell cycle or both. most of the induced sces were found to be formed during the second cell cycle in which bu-containing dna was used as template for dna synthesis. in cells which were pregrown for 4 cell cycl ...19817199115
the a, asc, and l systems for the transport of amino acids in chinese hamster ovary cells (cho-k1). 19817287709
the mannose 6-phosphate receptor of chinese hamster ovary cells. isolation of mutants with altered receptors. 19816270122
quantitative analysis of purine and pyrimidine metabolism in chinese hamster ovary cells.a detailed quantitative study of purine and pyrimidine metabolism in logarithmically growing chinese hamster ovary cells has been performed. direct measurements of the ribonucleoside and deoxyribonucleoside triphosphate pool sizes have been made, and the pathways and rates of metabolism of adenine, hypoxanthine, guanine, guanosine, deoxyadenosine, and deoxyguanosine and of uridine, cytidine, deoxycytidine, deoxyuridine, and thymidine have been determined.19817317815
[hereditary changes in gene activity as 1 of the causes of phenotypic heterogeneity in 8-azaguanine-resistant chinese hamster cells (cho-k1)].eight chinese hamster clones (cho-k1) growing at the 30 mg/ml concentration of 8-azaguanine (ag) were studied. clones were differentiated by their resistance to ag and to 6-thioguanine, by their plating efficiency on hat medium, and by the level of hypoxantine incorporation in cells. the differences in phenotypic properties were shown to be associated with variability in hypoxanthine-guanine phosphoribosyltransferase (hprt) activity. hprt michaelis constant (km) for hypoxanthine and phosphoribos ...19817314248
hypoxanthine and thymidine compete for transport in chinese hamster fibroblasts. 19817305383
insulin binding in cultured chinese hamster kidney epithelial cells. the effects of glucose concentration in the medium and tunicamycin.an epithelial cell line established from a chinese hamster kidney, chk-ace, was separated into two sublines, chk-ace-100 and chk-ace-400, by 18 successive passages in medium containing 100 and 400 mg/dl glucose, respectively. binding of chk-ace-100 and chk-ace-400 cell to 125i-labeled insulin showed similar ph and time dependency; 125i-labeled insulin, concentration differed in the two sublines, however. degradation of 125i-labeled insulin, as determined by its ability to bind insulin antibody a ...19817028131
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
determination of deoxyribonucleoside triphosphates using dna polymerase: a critical evaluation.there are more than twenty appreciably different deoxyribonucleoside triphosphate assays using dna polymerase in the literature. therefore, each aspect of this method has been critically evaluated, including the purity of the substrates and of dna polymerase, the reaction conditions, product isolation, and the effect of cell extracts on the assay. the final method uses a phosphatase-free dna polymerase preparation, 2'-damp to inhibit the 3' leads to 5' exonuclease of dna polymerase i, and includ ...19817317818
[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
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