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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) ...1979548254
organ-specific mutations in chinese hamsters induced by chemical carcinogens. 1979293496
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.1979499424
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 ...1979513156
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 ...1979446913
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 ...1979572551
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 ...1979760168
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.1979758440
[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 ...1979546426
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.1979532719
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 ...1979473226
effect of diet limitation on development of diabetes in non-hyperphagic prediabetic chinese hamsters. 1979386727
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 ...1979223525
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 ...1979374609
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 ...1979374580
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 ...1979374574
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.1979374003
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 ...1979318416
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 ...1979284357
transfer rna isoacceptors in cultured chinese hamster ovary cells. 1979255210
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 ...1979233812
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 ...1979230391
relative mutagenicity of nucleoside virostatic drugs in chinese hamster ovary cells. 1979118651
[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 ...1979115751
in vivo method for sister chromatid exchanges in chinese hamster foetal and bone marrow cells. 197991592
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 ...197935565
mutations of chinese hamster somatic cells from 2-deoxygalactose sensitivity to resistance.in chinese hamster somatic cells, the spontaneous change of phenotype from 2-deoxygalactose sensitivity to resistance was studied using fluctuation test experiments à la luria and delbrück (1943) for four chinese hamster cell strains derived from v79. the results are consistent with true mutational events. the mutation rates are in the range of 1 to 3.5 x 10(-5) per cell per generation. the relationship between the 2-deoxyglactose resistance and the galactokinase markers is discussed.1979488705
oer and rbe for negative pion beams of different peak widths.experimental data on survival curves for pion because of different peak widths under aerobic and hypoxic conditions are reported. metabolic depletion of oxygen by the chinese hamster cells (line v79) was used to obtain hypoxia. the results indicate that the rbe at the beam entrance (plateau) is approximately 1.0. when the bragg peaks were broadened to widths of 1.3, 7.8, and 10.5 cm (at the 80% dose level), the rbe (50% cell survival) at the peak centres was 1.7, 1.6, and 1.2, respectively. the ...1979465928
[pathology of mitosis after cellular recovery from a metaphase block].the experiments in chinese hamster fibroblast-like cells have shown that the c-mitosis inducing agents (colchicine, colcemid and low temperature) produce evident stathmokinetic and radiomimetic effects. by the reversibility moment of the former the latter becomes apparent, manifesting in bridge accumulation. this form of pathology is likely to be caused by the disturbance of the cellular nucleoprotein metabolism in c-mitosis.1979465693
the metabolically mediated dna damage and subsequent dna repair by 4-chlorobiphenyl in chinese hamster ovary cells.the metabolism of [3h]-4-chlorobiphenyl (cb) by chinese hamster ovary cell cultures resulted in the formation of lipophilic hydroxylated metabolites, trichloroacetic acid soluble conjugates and covalent macromolecular adducts. the major lipophilic metabolite was chromatographically similar to 4'-chloro-4-biphenylol. the intracellular macromolecules were fractionated into protein, rna and dna. although protein was the major target of covalent interaction with [3h]-cb and contributes 85% of the ma ...1979451338
nuclear protein synthesis at permissive and non-permissive temperatures in a chinese hamster ovary cell line with a temperature-sensitive defect in cytoplasmic non-mitochondrial protein synthesis. 1979446528
effects of hyperthermia (41.5 degrees) on chinese hamster ovary cells analyzed in motisis.the mitotic cells from an asynchronous population of chinese hamster ovary cells exposed to 41.5 degrees for 7 hr were examined by light and electron microscopy to determine if there were any morphological abnormalities related to cell death or lengthening of metaphase induced by hyperthermia. all components of the mitotic apparatus were formed during exposure to heat, and the mitotic apparatus was functional as demonstrated by eventual cell division. however, heat caused the nuclear envelope to ...1979445391
interaction between radiation and drug damage in mammalian cells. iii. the effect of adriamycin and actinomycin-d on the repair of potentially lethal radiation damage.we have studied the effects of actinomycin-d (amd) and adriamycin (adrm) on the repair of radiation damage in chinese hamster cells (v79) in plateau phase growth. suppression of potentially lethal damage repair (pldr) was observed in the presence of non-toxic levels of amd and minimally toxic levels of adrm. the suppression of pldr by amd persisted as long as the drug was present. removal of amd was followed by prompt repair of potentially lethal injury suggesting that suppression of pldr by amd ...1979314429
rescue of marker phenotypes: effects of budr sensitization, hypoxia and high let.the survival curve of colony-forming ability of chinese hamster wg3h cells has been compared with the dose-response curve for the expression of an active thymidine kinase (tk) gene from these cells. the tk+ phenotype was measured by hybrid colony formation after fusion of wg3h (tk+) cells with chinese hamster a23 (tk-) cells. the tk+ survival data fitted a multi-target curve up to 3 krad of 137 cs irradiation, when a highly resistant fraction of hybrid colonies was seen at about 1 per cent survi ...1979314426
relationship between histidyl-trna level and protein synthesis rate in wild-type and mutant chinese hamster ovary cells.a preliminary investigation was carried out to determine how conditional lethal mutants affected in particular aminoacyl-trna synthetases may be used to study the role of trna charging levels in protein synthesis. the relationship between rate of protein synthesis and level of histidyl-trna in wild-type cultured chinese hamster ovary cells was determined using the analogue histidinol to inhibit histidyl-trna synthetase activity. this response was compared with that obtained using a mutant strain ...1979256567
the induction of sister chromatid exchanges by dihydrodiols derived from 7,12-dimethylbenz[a]anthracene and 3-methylcholanthrene.the in vitro induction of sister chromatid exchanges (sces) in chinese hamster ovary (cho) cells by the polycyclic hydrocarbons, 7,12-dimethylbena[a]anthracene and 3-methylcholanthrene and some of the related dihydrodiols was investigated. increased numbers of sces were seen in the chromosomes of cells exposed to non-k-region dihydrodiols. the most active compounds were the 3,4-dihydrodiol of 7,12-dimethylbenza[a]anthracene and the 7,8- and 9,10-dihydrodiols of 3-methylcholanthrene: the parent h ...1979110440
regulated synthesis of rna polymerase ii polypeptides in chinese hamster ovary cell lines.rna polymerase ii polypeptides present in [35s]methionine-labeled chinese hamster ovary (cho) cell extracts have been quantitatively immunoprecipitated with an anti-calf thymus rna polymerase ii serum. analyses of the immunoprecipitates on sodium dodecyl sulfate polyacrylamide gels indicated that the immunoprecipitated polymerase ii of both wild type cho cells and the alpha-amanitin-resistant mutant ama1 had polypeptides of molecular weight 214,000, 140,000, 34,000, 25,000, 23,000, 20,500, and 1 ...1979438182
characterization of postribosomal aminoacyl-trna synthetases in cultured chinese hamster ovary cells. 1979454608
g1 phase chinese hamster v79-379a cells are inherently more sensitive to platinum bound to their dna than mid s phase or asynchronously treated cells. 1979475817
cell-mediated mutagenesis in cultured chinese hamster cells by polycyclic hydrocarbons: mutagenicity and dna reaction related to carcinogenicity in a series of compounds.three polycyclic hydrocarbons, benz(a)anthracene, 3-methylcholanthrene and 7,12-dimethylbenz(a)anthracene, have been studied in a cell-mediated mutagenesis system using bhk 21 cells to metabolize the hydrocarbons and v-79 cells as targets for detecting induced cytotoxicity and mutation. in large-scale experiments, the dna of v-79 cells was analyzed by column chromatography to determine the nature and true extent of reaction of hydrocarbons with dexoyribonucleosides. products with dna formed by t ...1979110710
platinum-induced mutations to 8-azaguanine resistance in chinese hamster ovary cells.6 platinum (pt) compounds were compared in suspension cultured chinese hamster ovary (cho-s) cells with respect to their inhibition of growth, their reduction of cloning efficiency, and their induction of mutants resistant to 200 microm (30 micrograms/ml) 8-azaguanine (8-ag) and 3 mm ouabain (oua), respectively. the toxicity of these compounds can be ranked by the medium concentrations which decrease suspension growth/or cloning efficiency by 50%: cis-pt(nh3)2-cl2 (0.9/1.5 microm) greater than p ...1979460295
the cytotoxic, mutagenic and clastogenic effects of chromium-containing compounds on mammalian cells in culture.examples of chromic and chromate salts have been examined for their effects on a cultured chinese hamster cell line. the responses studied were cytotoxicity, mutagenesis and clastogenesis. chromate (hexavalent chromium) salts of both high and medium water solubility were active in producing all three classes of response, whereas an insoluble chromate salt and a soluble chromic (trivalent chromium) salt were inactive. in addition to illustrating the value of using mammalian cells in culture for s ...1979460294
sister chromatid exchanges induced by inhaled anesthetics.there is sufficient evidence that anesthetics may cause cancer to justify a test of their carcinogenic potential. baden, et al., using the ames test, a rapid and inexpensive genetic indicator of carcinogenicity, have shown that among currently used anesthetics fluroxene alone caused bacterial mutations. the authors used the sister chromatid exchange (sce) technique, another rapid assay of mutagenic-carcinogenic potential. the frequency of sister chromatid exchanges in chinese hamster ovary cells ...1979453561
enhancement of thermal killing by polyamines. iii. synergism between spermine and gamma radiation in hyperthermic chinese hamster cells. 1979451160
differential effect of procaine on irradiated mammalian cells in culture.hela and v-79 chinese hamster cells temporarily stored in ampoules were treated with the local anesthetic procaine. postirradiation treatment increased lethality in hela cells depending on drug concentration, duration of treatment and cell density, as measured by colony-forming ability upon plating. if present during irradiation only, procaine protected from irradiation. in v-79 cells procaine potentiated radiation lethality only in freshly trypsinized cells. procaine effect was thus cell type s ...1979441343
effect of continuous insulin infusion with an implantable seven-day minipump in the diabetic chinese hamster. 1979436792
excision repair of cis-diamminedichloroplatinum(ii)-induced damage to dna of chinese hamster cells.platinum was lost from the dna of cis-diamminedichloroplatinum(ii) [cis-pt(ii)]-treated exponentially growing chinese hamster v79-379a cells with a half-life of 28 hr. by contrast, platinum was lost from the dna of cells treated in stationary-phase culture with a half-life of 4 days. cells treated in and allowed to remain as a stationary-phase culture maintained an intact and apparently viable appearance. when the stationary-phase culture was diluted with fresh medium, cell division occurred, an ...1979427811
the relevance of a caffeine post-treatment to sce incidence induced in chinese hamster cells. 1979113671
immunological detection of cell surface components related with aggregation of chinese hamster and chick embryonic cells. 1979110634
two-dimensional electrophoretic analysis of concanavalin-a binding components in the plasma membranes of chinese hamster fibroblasts. 1979456578
neurogenesis in the amygdaloid nuclear complex in a rodent (the chinese hamster). 1979421144
higher order structure of chromosomes.isolated chinese hamster metaphase chromosomes were resuspended in 4 m ammonium acetate and spread on a surface of distilled water or 0.15 to 0.5 m ammonium acetate. the dna was released in the form of a regular series of rosettes connected by interrossette dna. the mean length of the rosette dna was 14 micron, similar to the mean length of 10 micron for chromomere dna of drosophila polytene chromosomes. the mean interrosette dna was 4.2 micron. sds gel electrophoresis of the chromosomal nonhist ...1979456198
mutagenesis of chinese hamster cells is facilitated by thymidine and deoxycytidine. 1979431725
cytotoxic effects of procaine, lignocaine and bupivacaine.cytotoxic effects of procaine, lignocaine and bupivacaine were investigated on cultures of chinese hamster lung fibroblasts. cell growth was inhibited over 24 h exposures with an ed50 of 0.17% for procaine, 0.07% for lignocaine and 0.02% for bupivacaine. cell survival (measured as colony-forming ability) was reduced over 24 h exposure with an ed50 of 0.21% for procaine, 0.09% for lignocaine and 0.06% for bupivacaine. morphological changes included vacuolation, cell rounding and retraction from t ...1979465252
effect of cell growth rate and dose fractionation on chemically-induced ouabain-resistant mutations in chinese hamster v79 cells.chinese hamster v79 cells were grown in medium containing either 10% or 2% fcs during the expression time following exposure to mnng. the lower serum concentration was used to reduce the rate of cell replication, thereby allowing more time for dna repair prior to "fixation" of the mutagenic lesion. in addition, fractionated and continuous exposures to mnng and mam, respectively, were carried out to determine their effect on the number of induced ouabain-resistant mutants. the results indicated t ...1979460287
growth and morphology of colonies of chinese hamster ovary cells growing on agar is affected by insulin.as a model for the effect of hormones and growth factors on three-dimensional growth of mammalian cells, we have analyzed the effect of insulin on the three-dimensional growth and morphology of chinese hamster ovary (cho) colonies grown on the surface of agar. sequential photographs in dark-field illumination of growing colonies have been analyzed with computer-assisted techniques. in this analysis the entire shape of each colony in a sizeable population (up to 10(5) colonies per experiment) can ...1979287027
calcium-mediated cell surface changes in chinese hamster cells. 1979220066
rapid isolation of metaphase chromosomes containing high molecular weight dna.metaphase chromosomes with high molecular weight dna were isolated from chinese hamster ovary (cho) cells in a neutral buffer containing polyamines and chelators. the individual, unfixed chromosomes retained their centromeric and secondary constrictions, distinct sister chromatids, and complex banding patterns. the dna from these chromosomes was 100-fold larger (2 x 10(8) daltons) than dna from chromosomes isolated by other procedures. these characteristics indicate preservation during isolation ...197939081
alteration in structure of multifunctional protein from chinese hamster ovary cells defective in pyrimidine biosynthesis.a combined genetic, biochemical, and immunological approach has clarified structural relationships involving the first three enzymes of de novo pyrimidine biosynthesis. a procedure involving antibody and protein a-sepharose was used to isolate the enzymes carbamoyl-phosphate synthase [atp:carbamate phosphotransferase (dephosphorylating, amido-transferring), ec 2.7.2.9], aspartate transcarbamoyltransferase (carbamoylphosphate:l-aspartate carbamoyltransferase, ec 2.1.3.2), and dihydro-orotase (l-5 ...197936610
quantitation of antibody binding to cell surface antigens by x-ray fluorescence spectrometry.an x-ray spectrometric method has been developed to quantitate antibody bindng to whole cell surfaces in order to obtain a distribution of binding within a population of cells. the method involves incubation of target cells with ferritin-labeled antibody. analysis of prepared samples in a modified transmission electron microscope with an x-ray detector and data analysis equipment, yields quantitative results on the binding of labeled antibody to individual cells. the binding of anti-2,4-dinitrop ...1979435491
circular dichroic and sedimentation studies of phosphorylated h1 from chinese hamster cells. 1979427101
detachment variants of chinese hamster cells. hyaluronic acid as a modulator of cell detachment. 1979218830
characterization of naturally occurring auxotrophic mammalian cells.in a previous study, several cultured cell lines were detected which are naturally occurring auxotrophs. in this investigation, the enzyme deficienceis involved are described. it is demonstrated that the chinese hamster cell lines cho(k1), yh21, rjk-36, and chw-1102 are deficient in cystathionase and argininosuccinate synthetase. in addition, cho (k1) and chw-1102 were found to lack argininosuccinate lyase. chw-1102 cells were also found to be unable to proliferate in medium containing branched- ...1979483124
respiration-deficient chinese hamster cell mutants: genetic characterization.we present here genetic experiments with a series of chinese hamster cell mutants defective in oxidative energy metabolism. the mutations were all shown to be recessive in intraspecies hybrids. thirty-five mutants were sorted into eight complementation groups, but one of these mutants failed to complement representatives of two distinct complementation groups. the possibility was raised that this is a cell carrying two mutations or a deletion. because of the greatly different frequencies with wh ...1979483122
biochemical genetics of chinese hamster cell mutants with deviant purine metabolism: isolation and characterization of a mutant deficient in the activity of phosphoribosylaminoimidazole synthetase.a new purine-requiring mutant of chinese hamster ovary cells (cho-kl) is described. this mutant, ade-g, grows on aminoimidazole carboxamide, hypoxanthine, or adenine. it complements all eight of our other previously described ade- mutants. biochemical analysis of de novo purine synthesis in whole cells suggests that ade-g is capable of the first four reactions of de novo purine biosynthesis and that it synthesizes and accumulates phosphoribosylformylglycinamidine (fgam). direct enzyme assay in c ...1979483121
effects of hyperthermia and x irradiation on sister chromatid exchange (sce) frequency in chinese hamster ovary (cho) cells. 1979441255
the effect of hexose on chloramphenicol sensitivity and resistance in chinese hamster cells. 1979438306
characterization of cell lines showing growth control isolated from both the wild type and a leucyl-trna synthetase mutant of chinese hamster ovary cells.the genetic approach to the problem of cellular growth control is limited by the availability of recessive mutations in cell lines which are capable of growth control in vitro. the cho cell line has yielded many recessive mutations including, for example, tsh1, a temperature sensitive leucyl-trna synthetase mutant, which under non-permissive conditions rapidly shuts down protein synthesis and generates uncharged trna. both cho and tsh1 are transformed, however, and do not respond to environmenta ...1979438301
the importance of ornithine as a precursor for proline in mammalian cells.ornithine aminotransferase catalyzes the reversible transamination of l-ornithine to delta1-pyrroline-5-carboxylate, the immediate precursor of proline. the direction and flux through this pathway in mammalian cells has not been established. glutamate has generally been considered to be the most important precursor for proline biosynthesis, but recent studies in xiphoid cartilage indicate that a significant fraction of cellular proline is derived from ornithine. using newly isolated mutant chine ...1979438294
failure of caffeine to influence induced mutation frequencies and the independence of cell killing and mutation induction in v79 chinese hamster cells.using v79 chinese hamster cells and a replating assay, no effect of caffeine post-treatment on spontaneous or uv- or ems-induced mutation frequencies to 8-azaguanine resistance was demonstrable. however, considerable potentiation of cell killing was observed. previous reports that caffeine enhances induced mutation frequencies are explained by an artefact in the situ method used; a similar artefact may also explain the cumulative in situ mutation dose-response curves. furthermore, the relationsh ...1979431556
[effect of the inhibition of a synthesis processes in the s-period on the subsequent course of mitosis in a synchronized chinese hamster cell culture].the transcription of all nuclear rna and rrna was inhibited in the synchronized chinese hamster cell culture by actinomycin d and protein synthesis was suppressed by pyromycin during the first and the second parts of the s period of the mitotic cycle. a decrease of the mitotic cell activity was revealed during the first and second waves of cell proliferation after the synchronization irrespective of the time of the antibiotic administration. at the same time there was noticed an increase of such ...1979427282
the discrete-time kinetic model analysis of dna content distributions in experimental tumour cells.a method was developed to analyse and characterize fmf measurements of dna content distribution, utilizing the discrete time kinetic (dtk) model for cell kinetics analysis. the dtk model determines the time sequence of the cell age distribution during the proliferation of a tumor cell population and simulates the distribution pattern of the dna content of cells in each age compartment of the cell cycle. the cells in one age compartment are distributed and spread into several compartments of the ...1979371812
karyotype and tumorigenicity of 1-methylguanine-transformed chinese hamster cells.chinese hamster embryo cells transformed with the trna catabolite 1-methylguanine were characterized by giemsa-banded karyotyping and by their tumorigenic potency in athymic nude mice. all seven 1-methylguanine-transformed cell lines were hyperdiploid with a modal chromosome number of 23. three of these lines had an additional marker chromosome derived from the long (q) arm of chromosome no. 4, and they had alterations of chromosome no. 5 as well. two of these three cell lines were tumorigenic. ...1979283292
diethyldithiocarbamate enhancement of radiation and hyperthermic effects on chinese hamster cells in vitro. 1979220663
biochemical genetic analysis of pyrimidine biosynthesis in mammalian cells. ii. isolation and characterization of a mutant of chinese hamster ovary cells with defective dihydroorotate dehydrogenase (e.c. 1.3.3.1) activity.a mutant (a204) of chinese hamster ovary cells (cho-k1), which is deficient in dihydroorotate (dho) dehydrogenase (e.c. 1.3,3.1) activity, has been isolated by a replica plating procedure. the mutant does not show a requirement for exogenously added pyrimidines. examination of intact cells shows that the mutant accumulates a large amount of carbamyl aspartate and is markedly but not totally deficient in biosynthesis of orotate from earlier precursors of pyrimidine biosynthesis, including asparta ...1979220270
mutation induction by 5-fluorodeoxyuridine in synchronous chinese hamster cells.chinese hamster ovary cells synchronized by mitotic detachment were treated with 5-fluorodeoxyuridine (fdurd), 0.2 micrograms/ml, at various times in the cell cycle. fdurd treatment in the early s period induced resistance to 6-thioguanine. treatment of asynchronous cells with fdurd caused little increase in 6-thioguanine resistance over the spontaneous frequency. mitotic selection thus enhances the probability of a cell being in the portion of s period receptive to mutation. these observations ...1979154970
biochemical genetic analysis of pyrimidine biosynthesis in mammalian cells: iii. association of carbamyl phosphate synthetase, aspartate transcarbamylase, and dihydroorotase in mutants of cultured chinese hamster cells.carbamyl phosphate synthetase (ec 2.7.2.9), aspartate transcarbamylase (ec 2.1.3.2), and dihydroorotase (ec 3.5.2.3), the first three enzymes in de novo pyrimidine synthesis in chinese hamster ovary cell strain kl (cho-kl), cose diment through a glycerol gradient. when an extract from urd- a, a pyrimidine-requiring auxotroph reduced in all three activities, is run on a glycerol gradient, the enzyme activities appear in two peaks higher in the gradient, a peak of aspartate transcarbamylase separa ...197939353
response of cells to hyperthermia under acute and chronic hypoxic conditions.the lethal response of chinese hamster cells heated to 42 degrees was determined following 0 to 30 hr culturing under hypoxic conditions. oxygenated and acutely hypoxic cells were equally sensitive to hyperthermia; however, sensitivity increased with the time of culturing under hypoxic conditions prior to treatment. three hr at 42 degrees resulted in a surviving fraction of approximately or equal to 0.1 under acute hypoxic conditions and less than 0.001 for cells cultured for 30 hr under oxygen- ...197934477
radioprotection by dmso of mammalian cells exposed to x-rays and to heavy charged-particle beams.populations of g1-phase chinese hamster cells in stirred suspensions containing various concentrations of dmso were irradiated with 250 kv x-rays or various heavy charged-particle beams. chemical radioprotection of cell inactivation was observed for all let values studied. when cell survival data were resolved into linear and quadratic components, the extent and concentration dependence of dmso protection were found to be different for the two mechanisms. the chemical kinetics of radioprotection ...1979572979
sterol synthesis in variant chinese hamster lung cells selected for resistance to 25-hydroxycholesterol. cross-resistance to 7-ketocholesterol, 20alpha-hydroxycholesterol, and serum.two lines of chinese hamster lung (dede) cells which are resistant to the killing effect of 25-hydroxycholesterol, and which grow to confluence in its presence, have been isolated. one of the resistant lines exhibited a high to normal growth rate and normal levels of 3-hydroxy-3-methylglutaryl coenzyme a (hmg-coa) reductase (mevalonate:nadp+ oxidoreductase (coa-acylating), ec 1.1.1.34) activity and sterol synthesis in the presence of concentrations of 25-hydroxycholesterol that caused nearly com ...1979762093
potentially lethal damage versus sublethal damage: independent repair processes in actively growing chinese hamster cells. 1979441249
a study of the repair of potentially lethal and sublethal radiation damage in chinese hamster cells exposed to extremely hypo- or hypertonic nacl solutions. 1979441248
ribosomal transcriptional complexes in subnuclear fractions of chinese hamster ovary cells after short-term actinomycin d treatment. 1979430587
the effect of amino acids on the temperature sensitive phenotype of the mammalian leucyl-trna synthetase mutant tshl and its revertants.the temperature sensitive leucyl-trna synthetase mutant tshl and two revertants have been compared to the parental chinese hamster ovary cells with respect to the effects of amino acid concentrations in the medium on growth. elevating the leucine concentration 30- or 100-fold allowed tshl to grow exponentially at 38.5 degrees c, normally the nonpermissive temperature. partial revertants that had recovered some enzyme activity required smaller supplements for growth. measurements of the leucine p ...1979422660
structure-activity relationships in the development of hypoxic cell radiosensitizers. ii. cytotoxicity and therapeutic ratio.this paper describes measurements of the aerobic cytotoxicity of 42 nitroaromatic and nitroheterocyclic compounds towards chinese hamster cells in vitro. the results of acute and chronic exposure were quantified, and the concentration c required to achieve a standard response estimated. fitting the data to an equation of the form - log c = b0 + b1e, where e is the one-electron reduction potential, explained 47 and 71 per cent of the variance in the acute and chronic aerobic cytotoxicity respecti ...1979312784
structure-activity relationships in the development of hypoxic cell radiosensitizers. i. sensitization efficiency.the efficiency of 35 nitroaromatic and nitroheterocyclic compounds in radiosensitizing hypoxic chinese hamster cells in vitro was determined. the concentration c of the compound required to achieve an enhancement ratio of 1.6 was measured, and the redox and partition properties were quantified as the one-electron reduction potential at ph 7, e, and the octanol: water partition coefficient, p, respectively. most of the compounds studied were 2-nitroimidazoles, but some 4- and 5-nitromidazoles, 5- ...1979312783
emetine resistance in chinese hamster cells. analysis of ribosomal proteins prepared from mutant cells. 1979762080
the initiation and elongation steps in protein synthesis: relative rates in chinese hamster ovary cells during and after hyperthermic and hypothermic shocks.the relative rates of the initiation and elongation phases of protein synthesis have been determined in heat- and cold-shocked cho cells from measurements of the incorporation of 35s-methionine into n-terminal and internal positions of growing peptides by a modified edman degradation. when the cells are shifted from 37 degrees c to temperatures between 10 degrees c and 34 degrees c, the rate of initiation is at first reduced more extensively than that of elongation. after 20 to 30 minutes at the ...1979762195
isolation and cell cycle analysis of temperature-sensitive mutants from chinese hamster cells.mutants temperature-sensitive for growth have been isolated from the established line of chinese hamster fibroblasts wg1a. these mutants, together with the ones previously isolated by roscoe et al. ('73), have been characterized with regard to their cell cycle properties. most of them become arrested in the g1 phase of the cell cycle when incubated under restrictive conditions. by performing temperature shift experiments with synchronous cultures, the execution steps of most of the mutated funct ...1979762193
[effect of polyethyelene glycol on proliferation of cultured chinese hamster cells].chinese hamster cells in suspension were treated with peg 4000 for 20 min. it was found that cell size began to diminish already when a 5% peg solution was used, and reached the minimal value in a 20% peg solution. a pronounced cell death was observed when peg concentration exceeded 20%, but cells that survived retained their proliferation potential. it is concluded that the cell death results from hypoosmotic shock when cell suspension in peg solution is diluted.1979571153
a simple method for producing different growth fractions in vitro for use in anti-cancer drug studies.a simple technique has been used experimentally to produce in vitro chinese hamster ovary cells with growth fractions ranging from 0 to 100%. known numbers of exponentially growing and plateau-phase tissue culture cells were mixed in various proportions to yield the desired final growth fraction. cells attach to the culture flask surface within 1 hr of mixing. treatment at that time with the nitrosourea compounds, ccnu and meccnu, resulted in differential drug survival sensitivities that were de ...1979570456
gene mutation and sister chromatid exchange in chinese hamster cells.the mutation in hypoxanthine phosphoribosyl transferase gene and the induction of sister chromatid exchange (sce) were comparatively studied treating chinese hamster ovary cells with the mutagens ethylmethanesulphonate. n-methyl-n'-nitro-n-nitrosoguanidine, mitomycin c and x-ray. all the agents exerted strong mutagenic effects and showed a dose-dependent relationship for the induction of sces.1979555171
the effect of hydroxyurea on synchronized chinese hamster ovary cells irradiated by ultraviolet light. 1979550666
nucleolar organizing regions of normal chinese hamster and chw cell line chromosomes.the chromosome preparations from fibroblasts of normal male and female chinese hamsters and the cell line chw were stained with agno3. the silver stain was usually localized at the telomeres of autosomes. the marker chromosome m1 in the chw cell line has ag-nor near the centre of the long arm, which indicates that either the long arms of two number 5 chromosomes fused at the telomeres or the intact telomeric region of one chromosome fused with one with a deleted telomere. the variation of ag-nor ...1979527380
enhancement of thermal killing by polyamines. iv. effects of heat and spermine on protein synthesis and ornithine decarboxylase activity.protein synthesis is shown to be very heat-sensitive in chinese hamster cells. it is shut off completely following 15-20 min at 42 degrees c whereas rna and dna syntheses are affected only after much longer exposure times. cells recover from inhibition of protein synthesis upon transfer to 37 degrees c. the degree of recovery is inversely related to the duration of heat exposure and it fits cell survival quantitatively. cells which become temporarily heat-resistant by prior heat-treatment, are a ...1979498061
an ultrastructural study of morphogenesis of fibrogranular complex and centriole in ductuli efferentes of chinese hamster.an ultrastructural study of ciliated epithelial cells in the ductuli efferentes of young and adult hamsters has revealed that these cells possess dense granules, dense granule clusters, dense bodies and fibrogranular complexes as reservoirs or precursors for ciliogenesis. the dense granules are first seen in the centrosomal region. later, many dense granules and dense granule clusters appear in the apical portion of the epithelial cells where, subsequently, dense bodies are also found. finally, ...1979494233
sister chromatid exchanges in vivo in chinese hamster embryonic liver cells exposed transplacentally to brdu. 1979477415
microspectrofluorometric analysis of surface antigens of murine melanoma and hamster peritoneal cell hybrids: comparisons of species antigenicity, chromosome number, and tumorigenicity.somatic cell hybrids from viral fusions of murine melanoma (pazg) x chinese hamster peritoneal cells (ch) were compared with respect to surface antigenicity, karyotype and tumorigenicity. one line, f57-(9), which arose from the hybridization of two ch cells and one pazg cell, had slight (6%) ch chromosome loss but 80%pazg chromosome loss after 10 months in culture. these cells expressed ch antigens strongly and pazg antigens weakly. in comparison, another hybrid, f57-(7), formed from one ch and ...1979471422
cytogenetic properties of chinese hamster v79-e cells: g-banding, c-banding, nucleolar organizer regions, and sister chromatid exchanges.a line of the chinese hamster v79 strain, denominated as v79-e, is cytogenetically characterized. it has a modal chromosome number of 22. chromosome morphology, g- and c-banding reveal strong differences from the normal complement of the chinese hamster presumably caused by rearrangements of chromosome segments during the past 20 years of in vitro culture. 4 chromosomes possess terminal nucleolar organizer regions. spontaneous sister chromatid exchanges occur with a frequency of 0.38 sister chro ...1979446595
studies on 1-beta-d-arabinofuranosyl cytosine-resistant mutants of chinese hamster fibroblasts: iii. joint resistance to arabinofuranosyl cytosine and to excess thymidine--a semidominant manifestation of deoxycytidine triphosphate pool expansion.variants isolated from mutagenized chinese hamster fibroblasts by a single cycle of exposure to ara-c distributed into two classes: (1) deoxycytidine (dc) kinase deficient clones with a high level of resistance, this phenotype was recessive in hybrids; and (2) clones exhibiting joint resistance to thymidine (dt) and to "low" ara-c concentration, this phenotype was accounted for by an increased dctp pool. the incorporation of exogenous dc into macromolecules was markedly altered in these variants ...1979432758
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