Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| methods to evaluate the effects of toxic materials deposited in the lung on immunity in lung-associated lymph nodes. | intratracheal instillation of sheep red blood cells (srbc) induced a primary immune response in lung-associated lymph nodes of chinese hamsters and fischer-344 rats. few or no anti-srbc antibody forming cells (afc) were found in the spleen or cervical lymph nodes after intratracheal immunization. the number of afc was significantly suppressed in the lung-associated lymph nodes from hamsters exposed by inhalation of 239puo2 and in rats exposed by intratracheal instillation of benzo(a)pyrene (bap) ... | 1979 | 548254 |
| transcription and hybridization of 125i-crna from flow sorted chromosomes. | metaphase chromosomes from the chinese hamster cell line m3-1 were separated by means of a flow sorter. two chromosome fractions were used for this study: a, which consisted of 95% pure chromosome no. 1, and b, which was 90% pure chromosome no. 2. the dna of 10(6) chromosomes of each type was purified, and a 125i-crna transcript was synthesized in a reaction containing e. coli rna polymerase and carrier-free 125i-ctp (1.7 ci/mumole). the crna product synthesized with template dna from 10(5) sort ... | 1979 | 428270 |
| organ-specific mutations in chinese hamsters induced by chemical carcinogens. | 1979 | 293496 | |
| possible mutagenic activity of saccharin. | a mutagenic effect of saccharin in chinese hamsters, using the in vivo sce test, was observed when massive overdoses were administered; cyclamate was not mutagenic. | 1979 | 499424 |
| proliferation of lung and airway cells induced by nitrogen dioxide. | proliferation of lung cells of chinese hamsters was examined in several regions of the lung parenchyma and ciliated airway epithelium after a 24-h exposure to 28.2 mg/m3 (15 ppm) nitrogen dioxide (no2). label was retained 3 wk after the injection of [3h]thymidine, and autoradiographic methods were used to localize the site of retention. by 24 h after administration of [3h]thymidine, parenchymal areas, exclusive of airways, showed an increased labeling index, indicative of cell death and replacem ... | 1979 | 513156 |
| effect of continuous low-dose insulin treatment on subsequent incidence of diabetes in genetically prediabetic chinese hamsters. | in an attempt to prevent the onset of diabetes, young, genetically prediabetic (but not yet hyperglycemic) chinese hamsters were treated continuously with insulin via minipump for 4 wk beginning 1 wk before the predicted age of onset of glucosuria (age 7 wk). continuous insulin infusion which increased the plasma insulin levels by 70%, did not cause hypoglycemia, nor did it reduce the incidence or severity of diabetic symptoms over the ensuing year of observation. in fact, early treatment with e ... | 1979 | 446913 |
| endocrine factors contributing to the ethanol preferences of rodents. | groups of c57 bl/6j mice (alcohol preferring) and dba/2j mice (alcohol avoiding) were fasted for 24 hours and administered glucose. at 30, 120 and 300 minutes after glucose, the c57 bl/6j mice had significantly higher levels of plasma glucose than the dba/2j strain. these differences were observed in comparable groups given either forced access or no access to alcohol. in ad lib fed animals never exposed to alcohol, c57 bl/6j mice had higher levels of plasma insulin than dba/2j mice. plasma leve ... | 1979 | 572551 |
| the effect of lucanthone on the radiation response of intestinal stem cells in chinese hamsters. | crypt microcolony assay was used to determine the effect of lucanthone on the radiation response of intestinal stem cells in chinese hamsters . the dq of the crypt microcolony radiation--survival curve was maximally reduced by 205 rads when lucanthone injection preceded irradiation by 10 hours and was reduced by 140 rads when injection followed irradiation by 5 hours. on simultaneous injection and irradiation, dq was reduced by only 20 rads; when injection and irradiation were separated by appro ... | 1979 | 760168 |
| absence of povidone-iodine-induced mutagenicity in mice and hamsters. | povidone-iodine usp was tested for mutagenicity in mice by the dominant lethal assay or micronucleus test and in chinese hamsters by the bone marrow test. none of the three tests revealed any evidence of mutagenic effect. | 1979 | 758440 |
| [an assessement of the in vivo sister chromatid exchange (sce)-test using various cytostatics (author's transl)]. | five cytostatics of different chemical structure and pharmacological action were used on chinese hamsters (bone marrow cells) to test the efficiency and validity of the in vivo sister chromatid exchange (sce)-test as an indicator of mutagenicity. these model substances, all of which had previously shown a mutagenic effect in one or the other of the various in vivo test systems, gave positive results in this test, too, with the exception of bleomycin. on the basis of the lowest effective dose and ... | 1979 | 546426 |
| mutagenicity of polycyclic hydrocarbons iii. monitoring genetic hazards of benz(a)anthracene. | mutagenicity tests (micronucleus test and chromosome aberrations) have been performed with benz (a) anthracene in spermatogonia and bond marrow cells of chinese hamsters and in nmri mice oocytes. mutagenic effects of the polycyclic hydrocarbon could be demonstrated. | 1979 | 532719 |
| the influence of ethanol treatment of cytogenetic effects in bone marrow cells of chinese hamsters by cyclophosphamide, aflatoxin b1 and patulin. | chromosomes were investigated from the bone marrow of chinese hamsters which received 10% (v/v) ethanol as the only liquid supply for a period of 9 weeks. at the end of the ethanol drinking period 1 group of animals received 2 oral doses of 80 mg/kg cyclophosphamide (cp), a second group received 2 oral doses of 25 mg/kg aflatoxin b1 (afb1), a third group 2 oral doses of 20 mg/kg patulin (pa). the 2 applications were separated by 24 h. the intake of ethanol had no effect on the bone marrow chromo ... | 1979 | 473226 |
| effect of diet limitation on development of diabetes in non-hyperphagic prediabetic chinese hamsters. | 1979 | 386727 | |
| organotropic mutagenesis in tissues of chinese hamsters induced by chemical carcinogens. | in order to investigate the relationship between mutation and carcinogenesis in vivo, a method has been developed in which somatic mutation can be studied in specific organs of chinese hamsters after acute dosing with chemical carcinogens. in preliminary experiments an increase in mutation was detected in cultures derived from lung tissue of hamsters after intraperitoneal dosing with the direct-acting mutagen and weak carcinogen, ethyl methanesulphonate, or with diethylnitrosamine, a carcinogen ... | 1979 | 223525 |
| isolated metaphase chromosomes. ii. proteins of chinese hamster chromosomes. | the proteins on metaphase chromosomes theoretically may be distributed ubiquitously throughout the karyotype, may be present uniquely on individual chromosomes or classes of chromosomes, or may exist in any combination of the above. separation of chromosomes according to size using sucrose velocity gradients in high capacity zonal centrifuge rotors allows sufficient fractionation of the genome to indicate the distribution of proteins within the karyotype. flow cytometric analysis and direct micr ... | 1979 | 374609 |
| flow-system measurement of cell impedance properties. | a flow-system technique has been developed that detects the high-frequency resistance and capacitance changes in a sensing orifice due to the passage of cells through the orifice. the resistance and capacitance changes are related to cell properties such as size, plasma membrane capacitance, and electrical resistivity of the cell interior. the relationship between measured impedances and cellular properties is discussed, and the prototype instrument for making such measurements is described. the ... | 1979 | 374580 |
| correlation between nuclear morphology and rate of deoxyribonucleic acid synthesis in a normal cell line. | chinese hamster fibroblasts were investigated for the existence of correlations between proliferative activity and nuclear morphology. as a proliferative parameter, the rate of dna synthesis of individual cells was determined by quantitative 14c-autoradiography. in a second step the images of the feulgen-stained nuclei were digitized for extraction of features of morphology and texture. these features were correlated with the corresponding dna synthesis rate values. the following relationships w ... | 1979 | 374574 |
| micromethod for chromosome preparations from chinese hamster lymphocytes. | chromosome preparations from chinese hamster lymphocytes were made by culturing for 2 to 6 days 50,000 to 800,000 lymphocytes in flat-bottomed cooke microtiter plates in 0.1 or 0.2 ml roswell park memorial institute-1640 medium (rpmi-1640) supplemented with 5--40 microliters pha/ml, 20% fetal calf serum (fcs), and 40 microns 2-mercaptoethanol. depending on blood volume and cell concentrations used, it was possible to obtain up to 1400 well-spread metaphases from one venepuncture. | 1979 | 374003 |
| alterations in glycohydrolase activities in streptozotocin-diabetic chinese hamsters (cricetulus griseus). | 1. six weeks after the injection of streptozotocin at 125 mg/kg i.p. in the av line nondiabetic chinese hamsters, the animals showed hyperglycemia, increased kidney, pancreas and stomach weights and stomach glucagon contents and depletion of insulin and glucagon in the pancreas. 2. plasma beta-d-galactosidase and n-acetyl-beta-d-glucosaminidase were elevated; whereas alpha-d-glucosidase was decreased and alpha-d-galactosidase remained unchanged in the plasma. 3. in the kidney, streptozotocin-dia ... | 1979 | 318416 |
| emetine resistance in chinese hamster cells is linked genetically with an altered 40s ribosomal subunit protein, s20. | emr-2 is an emetine-resistant (emr) chinese hamster ovary cell mutant that contains a single electrophoretically altered ribosomal protein, a component of its 40s ribosomal subunit [boersma, d., mcgill, s., mollenkamp, j. & roufa, d.j. (1979) j. biol. chem. 254, in press]. this report describes a genetic experiment designed to test linkage between the genes that specify the altered ribosomal protein, s20*, and emetine resistance in emr clones that segregated from cultures of emr-2 cells hybridiz ... | 1979 | 284357 |
| transfer rna isoacceptors in cultured chinese hamster ovary cells. | 1979 | 255210 | |
| acid glycohydrolase in chinese hamster (cricetulus griseus) with spontaneous diabetes--v. subcellular distribution in the kidney. | 1. seven renal glycohydrolases were measured in four subcellular fractions prepared from highly inbred aglycosuric (av-line) and glycosuric (xa-line) chinese hamsters. 2. alpha-d-galactosidase and beta-d-galactosidase were highest in the nuclear (n) and supernatant (s) fractions; both fractions showed reduced activities in the xa animals. 3. alpha-d-mannosidase was chiefly a particulate enzyme and its decrease in xa animals was evident in n, lysosomal-mitochondrial (lm) and mitochondrial-microso ... | 1979 | 233812 |
| endogenous cyclic amp does not modulate transport of hexoses, nucleosides, or nucleobases in chinese hamster ovary cells. | in a previous study we have demonstrated that neither extracellular nor intracellular cyclic adenosine monophosphate (amp) levels directly affect the uptake of nucleosides, nucleobases, or hexoses by various types of cultured mammalian cells. uptake of these nutrients into cells, however, involves two processes operating in tandem: facilitated transport across the membrane and intracellular phosphorylation; and uptake rates generally reflect the rates of substrate phosphorylation rather than of ... | 1979 | 230391 |
| relative mutagenicity of nucleoside virostatic drugs in chinese hamster ovary cells. | 1979 | 118651 | |
| [thiophosphamide induction of sister chromatid exchanges at various phases in the cell cycle of a chinese hamster cell culture]. | influence of three concentrations of thiophosphamide (thiotepa) on the formation of sister chromatid exchanges (sce) has been studied at different phases during 2 cell cycles in cultured chinese hamster cells. it is shown that the frequency of sce does not differ from the control level under the effect of the mutagen on cells in the g2 phase of the first cell cycle from the moment of harvesting. thiophosphamide induces the same number of sce at s, g1 stages of the first cell cycle and g2 of the ... | 1979 | 115751 |
| in vivo method for sister chromatid exchanges in chinese hamster foetal and bone marrow cells. | 1979 | 91592 | |
| naphthol as-bi (7-bromo-3-hydroxy-2-naphtho-o-anisidine) phosphatase and naphthol as-bi beta-d-glucuronidase in chinese hamster ovary cells: biochemical and flow cytometric studies. | conditions for the biochemical and flow cytometric assay of 7-bromo-3-hydroxy-2-naphtho-o-anisidine phosphatase and beta-d-glucuronidase activities in chinese hamster ovary cells were studied. in the biochemical assay, the ph optimum for the phosphatase activity was ph 4.6 with a km of 10(-5) m; the ph optimum for beta-d-glucuronidase activity was ph 5.0 with a km of 2 x 10(-5) m. for intact cells the derived constants were 3 to 10 times higher. the rate of hydrolysis of both substrates was also ... | 1979 | 35565 |
| purification of p-glycoprotein from plasma membrane vesicles of chinese hamster ovary cell mutants with reduced colchicine permeability. | 1979 | 500733 | |
| 86rb+ fluxes in chinese hamster ovary cells as a function of membrane cholesterol content. | steady-state fluxes of 86rb+ (as a tracer for k+) were measured in chinese hamster ovary cells (cho-k1) and a mutant (cr1) defective in the regulation of cholesterol biosynthesis; the membrane cholesterol content of this mutant was varied by growing it on a range of cholesterol supplements to lipid-free medium (sinensky, m. (1978) proc. natl. acad. sci. u.s. 75, 1247--1249). analogous to previous findings in ascites tumor cells, 86rb+ influx in the parent strain was differentiated into a ouabain ... | 1979 | 508750 |
| effects of heat shock on gene expression and subcellular protein distribution in chinese hamster ovary cells. | incubation of chinese hamster ovary (cho) cells for one hour at 43 degrees c results in several obvious changes in protein distribution and protein synthesis. one major protein of the cytoplasm (molecular weight 45,000 daltions), also present as a minor component in the nucleus, rapidly disappeared while several proteins, especially high molecular weight peptides, were induced by heat shock. localization of the proteins in the cytoplasm, extra-nucleolar chromatin and nucleolar bodies has been ca ... | 1979 | 537909 |
| cytogenetic effects of antituberculosis antibiotic rifampin on chinese hamster ovary cells. | 1979 | 540994 | |
| induction of sister-chromatid exchanges in chinese hamster ovary cells by thiol and hydrazine compoudns. | cysteine, cysteamine and glutathione all induce sister-chromatid exchanges (sces) in chinese hamster ovary (cho) cells when applied to cell cultures at concentrations between 10(-4) and 10(-2) m. acute exposure of cells th thiol compound for a period of 2--3 h resulted in a unique dose--response relationship in each instance. this consisted of two peak sce frequencies, one at either extreme of the concentration range. each peak corresponded to a 2--3-fold increase over the spontaneous level. a c ... | 1979 | 522883 |
| the effect of caffeine on cytotoxicity, mutagenesis, and sister-chromatid exchanges in chinese hamster cells treated with dihydrodiol epoxide derivatives of benzo[a]pyrene. | the effect of caffeine on chinese hamster v79 cells after treatment with the highly mutagenic (+/-)-7 beta,8 alpha-dihydroxy-9 alpha, 10 alpha-7,8,9,10-tetrahydrobenzo[a]pyrene, and the weaker mutagen (+/-)-7 beta,8 alpha-dihydroxy-9 beta,10 beta-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene, b[a]p-deiol-epoxide ii, was studied at both the biological and molecular levels. caffeine, at nontoxic dose levels, caused a synergistic reduction in cell survival induced by both isomers and also inhibited dna e ... | 1979 | 522876 |
| a comparison of cytotoxicity, ouabain-resistant mutation, sister-chromatid exchanges, and nascent dna synthesis in chinese hamster cells treated with dihydrodiol epoxide derivatives of benzo[a]pyrene. | chinese hamster v79 cells were treated with either (+/-)-7 beta, 8 alpha-dihydroxy-9 alpha, 10 alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (b[a]p-diol epoxide i) or (+/-)-7 beta,8 alpha-dihydroxy-9 beta,10 beta-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (b[a]p-diol epoxide ii) and the nascent dna was labeled with [me-3h]thymidine. the cells were harvested for determination of cytotoxicity, sister-chromatid exchanges (sce), ouabain-resistant (or) mutations and the size of newly synthesized daughte ... | 1979 | 522875 |
| modification by cysteamine of ultrasound lethality to chinese hamster v-79 cells. | 1979 | 515353 | |
| a cadmium-resistant variant of the chinese hamster (cho) cell with increased metallothionein induction capacity. | 1979 | 510415 | |
| effects of caffeine on purine metabolism and ultraviolet light-induced lethality in cultured mammalian cells. | caffeine, at doses which enhance the killing action of ultraviolet light, inhibits both de novo synthesis and the utilization of exogenous purines in cultured cho-k1, a chinese hamster ovary cell line. the decrease in synthesis was measured as inhibition by caffeine of the accumulation of phosphoribosylformylglycineamide or of phosphoribosylaminoimidazolecarboxamide, the fourth and ninth intermediates, respectively, in the de novo biosynthetic pathway. the effect is dose dependent, with a caffei ... | 1979 | 498124 |
| retinol inhibition of ornithine decarboxylase induction and g1 progression in chinese hamster ovary cells. | 1979 | 498118 | |
| elimination of metabolic cooperation in chinese hamster cells by a tumor promoter. | wild-type chinese hamster v79 cells (6-thioguanine-sensitive) reduce the recovery of 6-thioguanine-resistant cells when they are cultured together at high densities, through a form of intercellular communication (metabolic cooperation). cooperation is inhibited by 12-o-tetradecanoyl phorbol-13-acetate, rescuing the 6-thioguanine-resistant cells. these results may be useful in the study of an aspect of the mechanism of tumor promotion and in assaying for promoters. | 1979 | 493994 |
| precursor-product relationships between thymidine nucleotides and dna in mammalian cells. ii. studies with dtdp and dttp on cells partially lysed by brij-58. | cells from chinese hamster ovary cell cultures were partially lysed with brij-58 and incubated in a reaction mixture containing deoxyribonucleoside triphosphates and permitting semiconservative dna replication. the reaction mixture was supplemented with [3h]dttp and [14c]dtdp or, alternatively, with [14c]dttp and [3h]dtdp, and at different times, 3h and 14c specific activities of dttp and dtdp, as well as 3h/14c ratios in dna were determined. isotope ratios in dna were in good agreement with tho ... | 1979 | 508757 |
| effects of various oxygenated sterols on cellular sterol biosynthesis in chinese hamster lung cells resistant to 25-hydroxycholesterol. | the effects of a wide variety of oxygenated sterols upon sterol biosynthesis and hydroxymethylglutaryl-coa reductase (mevalonate: nadp+ oxidoreductase (coa-acylating), ec 1.1.1.34) activity in a wild-type clone and in a 25-hydroxycholesterol-resistant clone of chinese hamster lung (dede) cells are described. derivatives of cholesterol which were oxygenated in the 6, 7 or 15 positions of the sterol nucleus or in the 20, 22, 24 or 25 positions of the sterol side chain were shown to be potent inhib ... | 1979 | 508785 |
| asparaginyl-trna aminoacylation levels and asparagine synthetase expression in cultured chinese hamster ovary cells. | 1979 | 40971 | |
| dna crosslinking, sister-chromatid exchange and specific-locus mutations. | chinese hamster ovary cells were treated with the dna-crosslinking chemicals, mitomycin c (mmc) and porfiromycin (por), and their monofunctional derivative decarbamoyl mitomycin c (dcmmc). after exposure, the cells were studied for the induction of sister-chromatid exchanges (sces) and mutations at the hypoxanthine phosphoribosyltransferase and adenine phosphoribosyltransferase loci. the frequency of sces varied significantly in successive sampling intervals, requiring the weighting of each inte ... | 1979 | 522865 |
| mutagenicity of metal cations in cultured cells from chinese hamster. | the mutations at the hypoxanthine-guanine phosphoribosyl transferase (hgprtase) locus in chinese hamster v79 cells induced by metal cations were examined by the development of resistance to 8-azaguanine (8ag). the spontaneous frequency of 8ag resistance was 5.8 per 10(6) cells, and the frequency was enhanced to 2-6 times that of the control by treatment of cells with the chlorides of beryllium and manganese. about 75% of 8ag-resistant colonies were sensitive to amethopterin, and 86% of the resis ... | 1979 | 514305 |
| reversible inactivation of autosomal alleles in chinese hamster cells. | evidence is presented which suggests that a cho-derived thymidine kinase (tk) heterozygote, ts201, can reversibly inactivate the wild type tk allele, and that this event may result in simultaneous inactivation of a linked allele, galactokinase (glk). the clone ts201 was isolated as a revertant of a stable tk- 5-bromodeoxyuridine (brdu)-resistant mutant of cho. the reacquired tk activity differed from that of the wild type with respect to km and heat resistance, supporting the contention that ts2 ... | 1979 | 511955 |
| relationship between sister chromatid exchange and mutagenicity, toxicity and dna damage. | reciprocal exchanges of dna in sister chromatids (sces) are induced by various carcinogens and mutagens, although the quantitative relationship between the number of mutations and sces induced varies among chemicals. nevertheless, the analysis of sce production by various agents is often proposed as a sensitive and quantitative assay for genetic damage of the sort leading to mutation and cancer. in v-79 chinese hamster cells we have been measuring dna damage by alkaline elution, mutation inducti ... | 1979 | 503206 |
| thermosensitization by sulfhydryl compounds of exponentially growing chinese hamster cells. | the effect of various sulfhydryl compounds on the survival of exponentially growing monolayer cultures of chinese hamster cells (ha1) heated to temperatures of 37-43 degrees was examined. concentrations of cysteamine which were nontoxic or minimally toxic at room temperature or 37 degrees became increasingly toxic at elevated temperatures, greatly potentiating the killing produced by heat alone in the absence of cysteamine. this enhancement of hyperthermia-induced cell killing increased with inc ... | 1979 | 498092 |
| effect of salt solutions on the radiosensitivity of mammalian cells as a function of the state of adhesion and the water structure. | the radiation isodose survival curve of attached chinese hamster (v79) cells, subjected to a wide concentration range of salt or sucrose solutions, is characterized by two maxima separated by a minimum. cells are radioprotected at the maxima (high and low hypertonic salt concentrations) while they are radiosensitized at the minimum (intermediate hypertonic salt concentrations). both cations and anions can alter the cellular radiosensitivity above and beyond the (osmotic) effect observed for cell ... | 1979 | 397199 |
| epidermal growth factor stimulation of dna synthesis is potentiated by compounds that inhibit its clustering in coated pits. | we have used inhibitors of receptor-mediated endocytosis to investigate the mechanism and function of epidermal growth factor uptake by cultured cells. when rhodamine-labeled epidermal growth factor is bound to cell surface receptors on confluent monolayers of balb/c 3t3 cells, it rapidly collects in cell surface clusters and is internalized. the clustering of occupied receptors requires ca(2+) and is inhibited by primary alkylamines; both of these properties are shared by the enzyme transglutam ... | 1979 | 42903 |
| the biosynthesis of the major lipid-linked oligosaccharide of chinese hamster ovary cells occurs by the ordered addition of mannose residues. | 1979 | 489594 | |
| deficiency of arginine and lysine causes increase in the frequency of sister chromatid exchanges. | an increase in the rate of sister chromatid exchanges (sce) was found when v79 chinese hamster cells were exposed to increasingly severe degrees of arginine and lysine deficiency. the data suggest a possible function of chromosomal proteins, and of histones in particular, in the maintenance of the low normal rate of sce. | 1979 | 511161 |
| initiation of dna replication in chromosomes of chinese hamster ovary cells. | the initiation of dna replication and the subsequent chain elongation were studied using chinese hamster ovary cells synchronized at the beginning of s phase. the cells were synchronized by a combination of mitotic selection and treatment with 5-fluorodeoxyuridine (fdu). the use of this drug at a concentration of 10(-5) m was found to effectively prevent the leakage of cells into s phase. reversal of the fdu block by supplying thymidine resulted in the synchronous onset of initiation at multiple ... | 1979 | 160308 |
| folate-dependent enzymes in cultured chinese hamster ovary cells: evidence for mutant forms of folylpolyglutamate synthetase. | 1979 | 583488 | |
| hypoxanthine transport by chinese hamster lung fibroblasts: kinetics and inhibition of nucleosides. | 1979 | 543723 | |
| inhibition by trioxalen (psoralen) plus near-ultraviolet light of the induction of ornithine decarboxylase in chinese-hamster cells. | trioxalen (trimethylpsoralen) plus near-u.v. light, a potent inhibitor of dna and rna synthesis, inhibits the induction of ornithine decarboxylase in stationary-phase v79 fibroblasts. it does not affect the translation of pre-existing mrna. the method, in view of its high degree of specificity and precise timing, is a better choice for inhibiting rna synthesis than the commonly used chemical inhibitors and precursor analogues. | 1979 | 534483 |
| enhancement of the chromosome-damaging action of ascorbate by transition metals. | freshly prepared ascorbate inhibited mitosis and induced chromosome aberrations in cultured chinese hamster ovary cells. cu(ii) and mn(ii) (10(-4) or 10(-5) m) enhanced both actions. fe(ii) and fe(iii) (10(-4) or 10(-5) m) reduced or abolished the mitosis-inhibiting action of ascorbate. at 10(-4) m, fe(ii) and fe(iii) strongly enhanced the chromosome-damaging capacity of ascorbate. up to 100% of all examined metaphase plates had multiple chromosome exchanges or breaks. since the cytostatic and c ... | 1979 | 476651 |
| radiolysis of chromatin extracted from cultured mammalian cells: formation of dna-protein cross links. | chromatin extracted from chinese hamster lung fibroblasts has been examined for the formation of radiation-induced dna-protein cross links, using a membrane filter assay. the relative efficiencies of the aqueous radical intermediates, oh., eaq- and o2-, were investigated. cross links were found in gamma-irradiated isolated chromatin and in chromatin irradiated in the cell before isolation. when isolated chromatin was irradiated under conditions in which the chromosomal proteins were dissociated ... | 1979 | 317599 |
| fixation of potentially lethal radiation damage by post-irradiation exposure of chinese hamster cells to 0.5 m or 1.5 m nacl solutions. | the effect of 0.05 m and 1.5 m nacl treatments on cho cells during and after irradiation has been examined. treatment with either hypotonic or hypertonic salt solutions during and after irradiation resulted in the fixation of radiation damage which would otherwise not be expressed. the half time for fixation was 4 to 5 min, and the increased expression of the potentially lethal damage by anisotonic solutions was mainly characterized by large decreases in the shoulder of the survival curve, as we ... | 1979 | 317597 |
| a nutritional test for the low density lipoprotein receptor in chinese hamster fibroblasts. | 1979 | 227721 | |
| comparison of the properties of the alcohol dehydrogenases from wild-type and mutant chinese hamster somatic cells. | alcohol dehydrogenases (alcohol: nad oxidoreductase, e.c. 1.1.1.1.) from allyl alcohol-resistant and wild-type chinese hamster cells were purified using gel filtration, ion-exchange, and affinity-column chromatography. both enzymes exhibited the same isozyme band patterns on electrophoresis and isoelectric focusing. physicochemical properties of the two enzymes such as ph and temperature optima, km values, and temperature stability were found to be the same within the experimental errors. the ge ... | 1979 | 44189 |
| adaptation of thymidine utilization to changing rates of dna synthesis in the cell cycle. | in synchronous cultures of p-815 murine mastocytoma and of chinese hamster ovary (cho) cells, the relative contribution of exogenous thymidine to dna synthesis was studied by comparing rates of (3h)thymidine incorporation with the rate of dna synthesis as derived from incorporation of (3h)thymidine (10(-5) m) in the presence of amethopterin. in synchronous p-815 cultures, time-dependent variations of dna synthesis rates were in close agreement with those of (3h)thymidine incorporation rates at c ... | 1979 | 117296 |
| regulation of endogenous virus production by bromodeoxyuridine and dibutyryl cyclic amp in chinese hamster ovary cells. | either dibutyryl cyclic amp or bromodeoxyuridine can enhance rna type-c virus production in chinese hamster ovary cells. the resultant effect of simultaneous treatment of cells with 1 mm cyclic amp and 65 mum bromodeoxyuridine is greater than their additive effects when used separately. the increase in virus production does not seem to involve viral gene amplification, but correlates with an increase in viral rna transcription. the virus is also shown immunologically to be unique to the chinese ... | 1979 | 90523 |
| a concanavalin a-resistant chinese hamster ovary cell line is deficient in the synthesis of [3h]glucosyl oligosaccharide-lipid. | in this report we present an initial determination of the biochemical defect present in a chinese hamster ovary cell line selected for resistance to concanavalin a. membranes of this mutant, b211, incorporated at least 10-fold less mannose from gdp-[14c]mannose into oligosaccharide-lipid than membranes of the wild type. in the presence of dolichol phosphate, membranes of the mutant and wild type exhibited similar rates of synthesis of number of early intermediates, namely, mannosylphosphoryldoli ... | 1979 | 479186 |
| inhibitory effect of guanyl nucleotides toward adenylate cyclase activity of chinese hamster ovary cell membranes activated in vitro by cholera toxin. | 1979 | 479151 | |
| comparison of complexity and diversity of polyadenylated polysomal and informosomal messenger ribonucleic acid from chinese hamster cells. | the sequence complexity and relative abundance of cytoplasmic polyadenylated polysomal (ribosome-bound) mrna and cytoplasmic polyadenylated informosomal (ribosome-free) mrna were analyzed in exponentially growing chinese hamster cells (line cho) using the technique of cdna hybridization to excess poly(a)+ mrna. polysomal and informosomal mrnas had similar complexities ( approximately 8300 mrna species), but both the fraction of mrna and the number of sequences comprising the mrna abundance class ... | 1979 | 486422 |
| a partial characterization of dna fragments protected from nuclease degradation in histone depleted metaphase chromosomes of the chinese hamster. | a small proportion (0.1-0.5%) of the total dna content of native chinese hamster metaphase chromosomes is protected from nucleolytic degradation following the removal of histones by extraction with either 0.2 n hcl or 2 m nacl, and remains attached to the nonhistone protein core. acid extraction followed by dnase i digestion leads to small fragments of 10-30 bases. salt extraction followed by micrococcal nuclease digestion gives approx. 140 b.p. fragments which are undistinguishable in size from ... | 1979 | 493144 |
| different chinese hamster cell lines express a g1 period for different reasons. | previous studies from our laboratory have shown that the absence of g1(g1-condition) in two lines of chinese hamster cells is dominant over the presence of g1(g1+condition) in a variety of intraspecific cell hybrids. g1+ mutants or variants cna be isolated from g1- cells following mutagenesis and selection. these g1+ mutants fall into multiple complementation groups based on their abilities to form g1- cell hybrids with one another. this is evidence that different mutants have g1 intervals for d ... | 1979 | 531733 |
| intercellular adhesion as a function of the cell cycle traverse. | intercellular adhesion is assumed to play an important role in a multitude of biological phenomena governing cellular behavior. the rate of intercellular adhesion as a function of the cell cycle traverse has been investigated using, in the monolayer assay, synchronized chinese hamster ovary-k1 cells. results obtained demonstrate that cells in g1 adhere to g1 cells at twice the rate that s cells adhere to each other. g1 cells adhere to s cells at an intermediate rate. the additive adhesiveness se ... | 1979 | 511931 |
| differential radiosensitivity of two mammalian cell lines after hyperthermic pretreatment. | hyperthermia in combination with 60co-gamma-therapy not only increases the radiosensitivity of mammalian cells, it also can create a greater selectivity between individual cell populations. tw established chinese hamster cell lines (v79 and b14f28) showed a similar radiosensitivity at 37 degrees c, but exhibited a marked difference in their response to 60co-gamma-rays when they were pretreated with mild hyperthermia (1 hour at 42 degrees c): about 50% of each cell type survived a dose of 400 rad ... | 1979 | 505472 |
| enhancement of excision-repair efficiency by conditioned medium from density-inhibited cultures in v79 chinese hamster cells: evidence for excision repair as an error-free repair process. | conditioned medium from density-inhibited v79 chinese hamster cell cultures, given as a post-treatment to uv-irradiated homologous cells, was demonstrated to reduce the lethal action of ultraviolet light by temporarily blocking dna replication. since the increased survival was not affected by various non-toxic concentrations of caffeine, such protective effect would be attributable to the prolonged intervention of excision repair before dna replication during the post-treatment period. the influ ... | 1979 | 503101 |
| synergistic biological effects of ultrasound and ionizing radiations evaluated in vitro. | the effects of diagnostic ultrasound on growing asynchronous cultures of chinese hamster ovarian cells were evaluated, with particular attention to possible synergism with ionizing radiations. measurements of cellular growth rate/survival and changes in morphology indicated that synergistic biological effects were absent. | 1979 | 472256 |
| isolation and characterization of cho cell mutants with altered asparagine synthetase. | two asparagine auxotrophic mutants (n3, n4) were isolated from the gat- strain of chinese hamster ovary cells, using a selection procedure modified from that of goldfarb et al. (1). the defect in these mutants is due to a deficiency in asparagine synthetase activity. n3, in particular, had no measurable enzyme activity. complementation analysis by peg-mediated cell fusion showed that the auxotrophic phenotype behaved as a recessive trait; complementation was obtained between n3 or n4 and the pse ... | 1979 | 43600 |
| chromatid breaks induced in chinese hamster cells by low doses (12--100 rad) of pi--mesons. | monolayer cultures of the fibroblast-like chinese hamster cell-line 19/1 were irradiated in the g2-phase of the cell cycle by pi--mesons (6 rad/min peak-pion dose rate). frequencies of induced single- and isochromatid breaks, acentric fragments and interchanges were compared with data obtained from 140 kv x-rays. the rbe-values were for the pion dose peak between 0.8--1.2 and for the pion dose plateau 0.5--0.9. whereas for single chromatid breaks there was no significant difference between x-ray ... | 1979 | 504558 |
| biological effects of negative pions in monolayers and spheroids of chinese hamster cells. | the therapeutic value of pion irradiation was critically challenged by examining, in a cell culture system, various parameters of biological significance such as relative biological efficiency (rbe), oxygen enhancement ratio (oer), dna-break formation, changes in cell cycle kinetics and regrowth. in all parameters, pions were superior to conventional low-let radiation. | 1979 | 504557 |
| cell survival over the depth profile after irradiation with a negative pion beam. | the colony-forming ability of chinese hamster fibroblast cells in vitro has been investigated throughout the depth dose profile of a negative pion beam. in the peak and 2 cm beyond, the rbe for macroclones (more than 50 cells per clone) was 1.3 and in the plateau region 0.8--1.0. all of the microclones (2-49 cells per clone) were observed as well. the rbe values are the same for peak and somewhat higher for plateau and post peak than found in cell survival studies referring to macroclones. | 1979 | 504556 |
| the effect of cis-platinum on the repair of radiation damage in plateau phase chinese hamster (v-79) cells. | 1979 | 575118 | |
| survival and kinetics of chinese hamster ovary cell subpopulations induced by adriamycin and radiation. | 1979 | 528270 | |
| adriamycin uptake in v79 and adriamycin resistant chinese hamster cells. | 1979 | 528269 | |
| relationship between dna alkylation and specific-locus mutation induction by n-methyl- and n-ethyl-n-nitrosourea in cultured chinese hamster ovary cells (cho/hgprt system). | chinese hamster ovary (cho) cells in culture were utilized to determine the cytotoxicity, specific-locus mutation induction, and dna alkylation which result from treatment of the cells with a range of concentrations of n-methyl-n-nitrosourea (mnu) or n-ethyl-n-nitrosourea (enu). with [3h]mnu over the concentration range 0.43--13.7 mm, methylation of dna was found to increase linearly, with a mean value of 56.7 pmol residue per mumol nucleoside per mm. with [1-3h]enu over the concentration range ... | 1979 | 509687 |
| anomalous dose-response characteristics induced by caffeine in ultraviolet-irradiated v79--79 chinese hamster cells. | 1979 | 504354 | |
| a quantitative comparison of the mutagenicity of carcinogenic polycyclic hydrocarbon derivatives in cultured mammalian cells. | the mutagenicity of a series of reactive polycyclic hydrocarbon derivatives has been studied using chinese hamster (v79) cells in culture and, as a mutational marker, resistance to the purine analogue 8-azaguanine. the compounds were compared by relating mutation frequency to the dose applied (mutagenic effectiveness) to induced cytotoxicity (mutagenic efficiency) and to the extent of reaction of the hydrocarbon with dna (absolute mutagenic efficiency). in each case anti-benzo(alpha)pyrene (bp)- ... | 1979 | 489163 |
| binding of concanavalin a to chinese hamster ovary cells after storage in liquid nitrogen. | 1979 | 487848 | |
| production of mrna in chinese hamster cells: relationship of the rate of synthesis to the cytoplasmic concentration of nine specific mrna sequences. | we constructed cloned dna sequences complementary to unselected mrnas [poly(a)+ cytoplasmic rna] from chinese hamster ovary cells and used them in rna:dna hybridization experiments. each cloned dna hybridized a single mrna from 1.3-3.5 kb in length. the relative rates of labeling (transcription rates) of nuclear rna complementary to each individual dna segment varied approximately 10 fold. the relative cytoplasmic concentration of the same specific rna sequences in the mrna after an equilibrium ... | 1979 | 487428 |
| the effect of a tumor promotor, 12-o-tetradecanoyl-phorbol-13-acetate (tpa), on sister-chromatid exchange formation in cultured chinese hamster cells. | the tumor promoter 12-o-tetradecanoyl-phorbol-13-acetate (tpa) does not increase the sister-chromatid exchange (sce) frequency in either chinese hamster ovary (cho) or lung (v 79) cells which are cultured in the presence of 5-bromodeoxyuridine. moreover, tpa does not alter the induction of sces in cho cells by mitomycin c during the first 3 cycles following addition of the alkylating agent. these sce induction data do not by themselves support the hypothesis that tumor promotion by tpa depends o ... | 1979 | 481459 |
| induction of 8-azaguanine- and ouabain-resistant mutants by cyclophosphamide and 1-(pyridyl-3)-3,3-dimethyltriazene in chinese hamster cells cultured in diffusion chambers in mice. | a host-mediated assay is described for induction of 8-azaguanine-resistant (azgr) and ouabain-resistant (ouar) mutants in chinese hamster v79 cells cultured in diffusion chambers (dc) in c3h mice. injection of the hosts with the indirect mutagen/carcinogen cyclophosphamide (cpp) or 1-(pyridyl-3)-3,3-dimethyltriazene (pydt) caused a dose-dependent increase in mutation frequency at the loci of azgr and ouar in the v79 target cells. plating efficiency of v79 cells in dc in mice was decreased depend ... | 1979 | 481447 |
| chinese hamster ovary cell population density affects intracellular concentrations of calcium-dependent regulator and ability of regulator to inhibit adenylate cyclase activity. | the adenylate cyclase activity [atp pyrophosphate-lyase (cyclizing), ec 4.6.1.1] of crude chinese hamster ovary cell membranes was inhibited 30-40% by low concentrations (6-600 ng/ml) of calcium-dependent regulator (cdr). this inhibitory effect was lost at concentrations of cdr above 600 ng/ml. the adenylate cyclase activity of membranes prepared from low population density chinese hamster ovary cells was not appreciably altered by cdr. however, with increasing cell population density there was ... | 1979 | 226991 |
| interactions of the carcinogen 4-nitroquinoline 1-oxide with the non-protein thiols of mammalian cells. | the carcinogen 4-nitroquinoline 1-oxide (4-nqo) was found to rapidly deplete non-protein thiols (npsh) from ehrlich ascites tumor cells and v79 chinese hamster fibroblasts. the effects of npsh on 4-nqo metabolism were studied by measuring 4-hydroxyaminoquinoline 1-oxide formation, cn- -insensitive oxygen consumption, and reduction of ferricytochromes c + c1 in normal cells and in cells pretreated with the thiol reagent n-ethylmaleimide. removal of thiols before treatment with 4-nqo resulted in i ... | 1979 | 110443 |
| neurogenesis in the basal forebrain of the chinese hamster (cricetulus griseus). i. time of neuron origin. | the time of neuron origin has been determined in the basal ganglia and related basal forebrain structures of the chinese hamster with the aid of 3h-thymidine autoradiography. large-celled structures like the globus pallidus, nucleus of the horizontal limb of the diagonal band of broca as well as large cells in the rostral part of the substantia innominata, in the caudate-putamen-complex and in the olfactory tubercle arise early (e12--e16), whereas medium-sized and small cells in the basal forebr ... | 1979 | 475002 |
| dependence of mammalian dna replication on dna supercoiling. ii. effects of novobiocin on dna synthesis in chinese hamster ovary cells. | novobiocin, an inhibitor of gyrase-induced dna supercoiling and dna replication in prokaryotes, inhibited the incorporation of dna precursors into dna in both intact and permeable chinese hamster ovary cells; much higher concentrations were required for permeable cells, in which no new replicons were initiated. nucleoids were prepared from cells that were incubated for 60 min with 200 micrograms/ml novobiocin, made permeable, and incubated with 0--50 micrograms/ml ethidium bromide. sedimentation ... | 1979 | 465492 |
| dependence of mammalian dna replication on dna supercoiling. i. effects of ethidium bromide on dna synthesis in permeable chinese hamster ovary cells. | chinese hamster ovary cells labelled with [14c]thymidine were made permeable, incubated with various concentrations of the intercalating dye ethidium bromide, and centrifuged through neutral sucrose gradients. the gradient profiles of these cells were qualitatively similar to those obtained by centrifuging dna from untreated, lysed permeable cells through gradients containing ethidium bromide. the sedimentation distance of dna had a biphasic dependence on the concentration of ethidium bromide, s ... | 1979 | 465491 |
| emetine-resistant chinese hamster cells. the identification of an electrophoretically altered protein of the 40 s ribosomal subunit. | 1979 | 447708 | |
| phosphorylation of the 10-nm filament protein from chinese hamster ovary cells. | 1979 | 447707 | |
| respiration-deficient chinese hamster cell mutants: biochemical characterization. | we have previously classified 35 of our respiration-deficient mutants into seven complementation groups and one "overlapping" mutant which does not complement mutants from groups i and ii. in this paper we report on the biochemical characterization of representatives of complementation groups i, ii, vii, and the "overlapping" mutant. we show that these mutants all have a defect in complex i of the electron-transport chain. the general features of these mutants are: (1) a low rate of o2 consumpti ... | 1979 | 494059 |
| cadmium-induced alterations in rna metabolism in cultures of chinese hamster cells sensitive to and resistant to the cytotoxic effects of cadmium. | a variant population (cdr) of cultured chinese hamster cells (line cho) was derived that is more than 100 times as resistant to the cytotoxic effects of cd2+ than is the parent population. the effects on rna metabolism of exposure to sublethal concentrations of cd2+ were studied in cho and cdr. exposure to 2 x 10(-7) m cdcl2 for 24 h resulted in increased polysome content (1.2 times) and increased uridine or adenosine incorporation into heterogeneous nuclear rna (1.2-1.4 times) and messenger rna ... | 1979 | 490682 |
| [variability of chinese hamster clones in resistance to 8-azaguanine]. | the stability of the 8-azaguanine resistance marker during the number of cell generations has been analyzed for 63 clones of chinese hamster cells. the resistant clones analyzed were spontaneous or induced after the treatment of parent cells by 5-budr, ems, or histone h1. the clones have revealed different levels of ag-resistance as well as different ability to maintain the above level, under the cultivation in the drug-free medium. subclones, isolated from the unstable clone, were found to be d ... | 1979 | 483396 |
| mutagenicity, cytotoxicity and dna crosslinking in v79 chinese hamster cells treated with cis- and trans-pt(ii) diamminedichloride. | the mutagenicity and cytotoxicity of cis- and trans-pt(ii) diamminedichloride (pdd) were examined in v79 chinese hamster lung cells and compared with effects on dna measured by alkaline elution. dna--protein crosslinks and dna interstrand crosslinks were detected following doses of cis-pdd which reduced cell survival 80--90% and which produced a mutant frequency of 3 x 10(-4) at the hgprt locus. equitoxic doses of trans-pdd were much less mutagenic than cis-pdd. at equitoxic doses, trans-pdd pro ... | 1979 | 481452 |
| chromosomal aberrations induced by maleic hydrazide and related compounds in chinese hamster cells in vitro. | the cytotoxic effects and chromosomal abnormalities induced by maleic hydrazide (mh) and its salts were investigated in cultured v79 cells. mh, and its potassium (k-mh) and diethanolamine (dea-mh) salts were tested. mh was 5--14 times more cytotoxic than its salts and almost 4.5 times less toxic than the related compound, hydrazine dihydrochloride (hdc). mh salts had very weak cytotoxicity; the ld50 values on v79 cells on exposure for 3 h in vitro were (in microgram/ml) 1100 (mh), 12 000 (dea-mh ... | 1979 | 481451 |
| chromosomal aberrations and sister-chromatid exchanges in chinese hamster cells treated in vitro with hexavalent chromium compounds. | chinese hamster cells (cho line) were treated in vitro for 30--39 h with hexavalent chromium compounds (k2cr2o7 and na2cro7), at concentrations ranging from 0.1 to 1.0 microgram of cr6+ per ml, in medium containing budr. chromosomal aberrations and sister-chromatid exchanges were scored on budr-labelled 2nd division metaphases, collected at the end of treatment and stained with giemsa. treatment with mitomycin c 0.009--0.030 microgram/ml) was carried out as a control for the responsiveness of th ... | 1979 | 481449 |
| facilitation by pyrimidine deoxyribonucleosides and hypoxanthine of mutagenic and cytotoxic effects of monofunctional alkylating agents in chinese hamster cells. | hypoxanthine (hx), thymidine (tdr) and deoxycytidine (cdr), at concentrations of 10(-5) m increased the yield of 8-azaguanine-resistant (azgr) mutants induced by n-methyl-n'-nitro-n-nitrosoguanidine (mnng) in cultured chinese hamster v79 cells. the cytotoxicity of mnng was increased 2-fold in the presence of hx, and more than 10-fold in the presence of tdr. this cytotoxic effect of tdr was abolished by equal concentrations of cdr, which by itself did not increase the cytotoxicity of mnng. howeve ... | 1979 | 481439 |
| combined effects of x irradiation and hyperthermia (42 and 44 degrees c) on chinese hamster v-79 cells in vitro. | 1979 | 472127 |