PMID(sorted ascending)
replicative bypass repair of ultraviolet damage to dna of mammalian cells: caffeine sensitive and caffeine resistant mechanisms.replicative bypass repair of uv damage to dna was studied in a wide variety of human, mouse and hamster cells in culture. survival curve analysis revealed that in established cell lines (mouse l, chinese hamster v79, hela s3 and sv40-transformed xeroderma pigmentosum (xp)), post-uv caffeine treatment potentiated cell killing by reducing the extrapolation number and mean lethal uv fluence (do). in the do reduction as the result of random inactivation by caffeine of sensitive repair there were mar ...1976967189
[protective effect of dna preparations on cell survival and yield of 8-azaguanine-resistant mutations in irradiated chinese hamster cells in culture]. 2013968015
effects of tritiated thymidine on cell population kinetics.this paper reports growth-kinetic data of chinese hamster tissue culture cells exposed at various times to differnt activities (0.05 muci/ml up to 10.0 muci/ml of tritiated thymidine. the analysis of the results aims at the determination of colony-size distribution and to the cellular capacity of reproduction after treatment which is reflected in the cell division spectrum within dialy intervals. the results of the growth-curves represented were converted into integrated curves of colony-size di ...1976968927
purine uptake by azaguanine-resistant chinese hamster this study the resistance of a number of lines of chinese hamster ovary cells to azaguanine is examined. those which are drug resistant by virtue of a deficiency of hypoxanthine-guanine phosphoribosyltransferase (hprt) fail to take up any exogenous hypoxanthine or azaguanine. a second class of drug resistant cells which grow in the reverse selective hat medium and have levels of hprt in the range of the wild type parent line take up these purines at lower rates than the nonresistant cells and ...1976972164
chromosome aberrations in oocytes of nmri mice and bone marrow cells of chinese hamsters induced with 3,4-benzpyrene.this paper deals with mutagenicity tests with 3,4-benzpyrene in mice oocytes of the strain nmri and chinese hamster bone-marrow cells. the mutagenic effect of this hydrocarbon was observed in both test systems. investigations of bone-marrow chromosomes clearly show dose-response curves.1976972619
chromosome breakage associated with organic mercury in chinese hamster cells in vitro [proceedings]. 1976972628
effects of halothane on dna synthesis and the presynthetic phase (g 1) in dividing fibroblasts.the effects of halothane on deoxyribonucleic acid (dna) synthesis and events preceding dna synthesis have been examined in chinese hamster fibroblasts in culture.dna synthesis was studied by the uptake of 3h-thymidine during short periods of incubation that minimized effects on cells in the presynthetic phase (g1). halothane produced slight but significant dose-related depression of 3h-thymidine uptake (20 per cent depression with 2 per cent halothane). in a separate series of experiments, synch ...1976973693
use of lipid vesicles as carriers to introduce actinomycin d into resistant tumor cells.unilamellar lipid vesicles have been used as a carrier vehicle to enhance the uptake of actinomycin d into an actinomycin d-resistant chinese hamster tumor cell line (dc-3f/adx). the dc-3f/adx cell line is resistant to actinomycin d as a result of its decreased capacity to transport actinomycin d across the plasma membrane and is able to grow in the presence of concentrations of actinomycin d that are cytotoxic for the sensitive parent cell line (dc-3f). incubation of resistant dc-3f/adx cells w ...1976975068
the effect of adriamycin and radiation on g2 progression.the effect of the dna-intercalating antibiotic adriamycin on the progression of chinese hamster ovary cells into mitosis, and on the delay induced by ionizing radiation, was studied using the mitotic cell selection procedure to monitor the rate of cell division. following the addition of adriamycin, the mitotic rate remained unaltered for a refractory period and then decreased to zero. this effect was concentration dependent with transition points between the s-g2 boundary for 0.1 mug/ml and lat ...1976975085
the isolation and preliminary characterization of somatic cell mutants resistant to the protein synthesis inhibitor-emetine.emetine reversibly inhibits protein synthesis in chinese hamster ovary (cho) cells. stable mutants which are 20-80 fold more resistant to the cytotoxic action of the drug can be isolated in a single step at a frequency of about 2-5 x 10(-7). the frequency of such mutants is increased 30-50 fold by ethyl methane sulphonate mutagenesis, and the spontaneous rate of mutation to emetine resistance as measured by luria-delbruck fluctuation analyses is 4.9 x 10(-7) mutations per locus per generation. p ...1976975243
human gene locations achieved by means of human-chinese hamster (cho-k1) auxotrophic cell hybridization. 1976975914
expression of human x-chromosomal markers in man-chinese hamster hybrids treated with isolated human chromosomes. 1976975919
proposed banding nomenclature for the chinese hamster chromosomes (cricetulus griseus). 1976975930
configurational changes in chromatids from helical to banded structures.induction of configurational changes in the helical chromatids of air dried chromosomes was used to explore the mechanism of g-banding. from the water-giemsa stained metaphase spreads of chinese hamster cells, chromosomes having clearly helical chromatids were selected and photographed. then the chromosomes were decolorized, treated with trypsin, and restained with saline-giemsa (1x ssc). such procedures were repeatedly carried out upon the same chromosomes. subsequent examination of the chromos ...1976976013
cytokinetic studies on the effect of hyperthermia on chinese hamster lung cells. 1976976291
quantitative evaluation of somatotrophic cells (sc) in the adenohypophysis of normal and diabetic male chinese hamsters.the pituitary of genetically diabetic chinese hamsters contains significantly (p less than 0.001) greater numbers of somatotrophes than pituitary of non-diabetics. this may play a role in the aetiopathology of diabetes in this species or at least contribute to the maintenance of hyperglycaemia.1976976637
the effect of prolonged hypoxia on growth and viability of chinese hamster cells. 2013977403
relevance of dimethylamine to mechanism studies of dic (dtic, nsc 45388).monolayer cultures of chinese hamster ovary (cho) cells take up the photo-decomposition products of dic more readily than dic itself. dimethylamine, an immediate product of this degradative pathway, can ultimately become associated with the dna, rna, and protein of the cells as demonstrated by selective enzymatic degradation of macromolecules and isopycnic centrifugation. the relevance of these observations to mechanism studies of dic is discussed.1976979914
combinations of hyperthermia (40 degrees, 45 degrees c) with radiation.incubation of chinese hamster cells at an elevated but sublethal temperature between fractions of radiation and/or pulses of hyperthermia at 45 degrees c strongly modified the effectiveness of cell killing. increasing the incubation temperature from 37 to 40 degrees c between fractions of hyperthermia at 45 degrees c followed by radiation substantially enhanced cell killing; while the opposite sequence (radiation leads to incubation at 40 degrees c leads to hyperthermia at 45 degrees c) resulted ...1976981627
repair of potentially lethan radiation damage: comparison of neutron and x-ray rbe and implications for radiation therapy.experiments with chinese hamster cells have shown that neutron irradiation does not result in repair of potentially lethal damage (pld), i.e., that which can be influenced by changes in environmental conditions following irradiation. since pld is presumed to be repaired in tumors but not in normal tissues, this absence of differential sparing of tumor cells relative to normal tissues--a feature characteristic of irradiation with x rays--represents an advantage of neutrons in addition to their re ...1976981675
a microsurgical technique for orthotopic ovarian transplantation in the chinese hamster.a microscopic surgical technique for the orthotopic transplantation of ovaries in the chinese hamster is described. the procedure, which uses microcauterization of the mesovarian stump and closure of the ovarian bursa with microvascular suture, resulted in a 75 to 80 percent surgical success rate in a series of 12 nondiabetic and 12 diabetic hamsters. applications include the production of prediabetic offspring, the study of intrauterine environmental effects on transplant-derived offspring, and ...1976982278
interaction between radiation and drug damage in mammalian cells. ii. the effect of actinomycin-d on the repair of the sublethal radiation damage in plateau phase cells.the effect of actinomycin-d (amd) on radiation damage repair was studied in plateau phase v79 chinese hamster cells. sublethal radiation damage repair, as demonstrated by survival fluctuations following two x-ray exposures separted by time, was observed in our plateau phase cells. plateau phase cells exposed to 0.01-0.04 mug/ml amd (a nontoxic regimen to 8 hours) between x-ray exposures were less able to repair sublethal damage. if plateau phase cells were plated at low dilutions into fresh medi ...1976985734
effects of actinomycin d on cell cycle kinetics and the dna of chinese hamster and mouse mammary tumor cells cultivated in vitro.actinomycin d produces changes in the cell cycle kinetics of chinese hamster (ha1) and mouse mammary tumor cells (emt6) cultivated in vitro. there was a reduced rate of progression of the cells through s phase and a g2 arrest, the duration and degree of which were drug dose dependent. the lethal effects of the drug on the two cell lines were comparable. at the molecular level, dna single-strand breaks (true breaks and/or alkali-labile bonds) appear initially. after drug removal, the extent of di ...1976986240
hypoxia-dependent reduction of 1-(2-nitro-1-imidazolyl)-3-methoxy-2-propanol by chinese hamster ovary cells and kht tumor cells in vitro and in vivo.incubation of chinese hamster ovary cells and kht murine fibrosarcoma tumor cells in the absence of oxygen with 1-[2-14c]nitro-1-imidazolyl)-3-methoxy-2-propanol, one of the most effective radiation sensitizers of hypoxic cells, results in the preferential reduction of 1-[2-14c]nitro-1-imidazolyl)-3-methoxy-2-propanol. the radioactivity associated with the acid-insoluble precipitate from cells incubated in nitrogen is about four times higher than that of cells incubated in air. when aqueous extr ...1976986241
[spontaneous and induced mutagenesis in a culture of chinese hamster cells].spontaneous and nitrosoguanidine (ng)-induced rate of reversions to glutamine independence was studied in cultured temperature-sensitive glutamine auxotrophs of chinese hamster cells. in 3 experiments the spontaneous rate of reversions varied from 0.8-10(-6) to 3.84-10(-6) per cell per generation. a dependence of the yield of ng-induced back mutations upon the time interval between the mutagenic treatment and the transfer to selective conditions (glutamine deficient medium, 40 degrees c) was est ...1976986338
chemical transformation of chinese hamster cells: ii. appearance of marker chromosomes in transformed cells.the chromosomes of 12 samples of cultured chinese hamster kidney and prostate cells (4 normal and 8 transformed), whose tissue culture properties have already been described (kirkland, 1976) have been examined for numerical change and for the appearance of abnormal markers. six transformed kidney subclones contained a consistent telocentric marker not present in the normal parental cell, and giemsa banding demonstrated this to be the centromere and the long (q) arm of the number 4 chromosome in ...1976986826
metabolic effects and mortality rate in diabetic chinese hamsters after long-term treatment with 5-methoxyindole-2-carboxylic acid (mica).chronic oral treatment of male diabetic chinese hamsters with 100 mg/kg/day 5-methoxyindole-2-carboxylic acid (mica) causes a depression of blood glucose in fasted animals and an improvement in the glucose profile in fed animals. glycogen levels in the liver and body weight are decreased. treated animals die at a higher rate than do controls. it is concluded that treatment with a potent inhibitor of gluconeogenesis like mica will not provide a useful tool in managing diabetes.1976989012
a surface glycoprotein modulating drug permeability in chinese hamster ovary cell mutants.chinese hamster ovary cells selected for resistance to colchicine display pleiotropic cross-resistance to a wide range of amphiphilic drugs. the drug-resistant phenotype is due to a membrane alteration which reduces the rate of drug permeation. surface labelling studies reveal that drug-resistant chinese hamster ovary cell membranes possess a carbohydrate-containing component of 170 000 daltons apparent molecular weight which is not observed in wild type cells. through studies of the metabolic i ...1976990323
[telomeric chromosome fusion in cells treated with colcemid and 5-bromdeoxyuridine].specific chromosomes with two or more centromeres were found in the tetraploid metaphases of the second mitotic division after combined treatment with coldemid (0.05 mug/ml) and 5-bromodeoxyuridine (50 mug/ml) for 24 hours in the aneuploid chinese hamster cell line. they were formed by telometric fusion of chromosomes and were absent in the cells treated with colcemid or 5-bromodeoxyuridine separately. a possible relation of this phenomenon to the telomeric association of chromosomes in the inte ...1976990480
stimulation of informosomal rna synthesis in cultured chinese hamster cells exposed to low levels of cadmium. 1976992074
short-term microcultures of lymphocytes from chinese hamster peripheral blood.a microtechnique for the culture of chinese hamster lymphocytes is described using cooke microtiter plates with 100,000 leucocytes in a culture volume of 0.1 ml and a culture time of three days. the culture media used were rpmi 1640 and trowell t8 supplemented with 20% foetal calf serum (fcs) and 2 mu pha. the cells were harvested with a skatron cell culture harvester using glass fibre filters. various technical aspects of the lymphocyte cultures from the chinese hamster are described. the relev ...1976993605
carbohydrate energy sources for chinese hamster cells in culture. 1976995956
carbon-13 nuclear magnetic resonance spectroscopy of suspensions of chinese hamster ovary cells specifically enriched with (methyl-13c)choline. 1976999821
modulation of membrane drug permeability in chinese hamster ovary cells.the kinetics of colchicine uptake into chinese hamster ovary cells have been investigated and found to be consistent with an unmediated diffusion mode. a variety of compounds such as local anesthetics and non-ionic detergents as well as drugs such as vinblastine, vincristine, daunomycin and actinomycin d potentiate the rate of colchicine uptake into these cells and into colchicine resistant mutants. in all cases, higher concentrations of these compounds were required to stimulate colchicine upta ...1976999943
chromosome distribution in a23 chinese hamster fibroblasts.this study deals with a systematic chromosome position analysis of 116 anti-mitotic and hypotonic treated a23 chinese hamster cells. no chromosome or pair of chromosomes was found to be located nearer the center or the periphery of the metaphase plate than would be expected by the reference distribution. the homologous chromosomes of pair 2 lie nearer to each other but they do not form a specific angle. the same relative position was shown for the chromosome groups 1-2, 1-e1 and 2-e5 (e standing ...19761001138
identification of late dna-replicating regions in chinese hamster chromosomes using a brdu-giemsa technique.asynchronous chinese hamster cells were labelled with brdu for 3 h prior to harvesting the metaphase cells. the late dna replicating sites became unifilarly brdu-substituted as compared to the earlier replicating sites having a normal dna constitution. those late replicating sites were identified by pale coloration or dot formation after treatment with 1.0 m na-phosphate solution (adjusted to ph 9.0 with supersaturated amount of nahco3 and at a temperature of 69-75 degrees c) and staining with g ...19761001156
rate of rna synthesis as a function of temperature in chinese hamster lung fibroblasts (v-79). 19761001370
comparative investigations on cytogenetic effects of x-irradiation on the germinal epithelium of male mice and chinese one short-term-experiment and one long-term-experiment spermatogonia of mice and chinese hamsters were compared for their sensitivity of x-ray induced chromosome aberrations. short-term-experiment: six hours after varying doses of x-rays the spermatogonia of both species were analysed and the number of induced chromatid breaks determined. at the dose range from 25-125 r the number of induced chromatid breaks per cell per roentgen is 0.01 in mice. in chinese hamsters this value is 0.0072. the ...19761002141
laser uv microirradiation of interphase nuclei and post-treatment with caffeine. a new approach to establish the arrangement of interphase chromosomes.laser uv microirradiation of chinese hamster interphase cells combined with caffeine post-treatment produced different patterns of chromosome damage in mitosis following irradiation of a small area of the nucleus that may be classified in three categories: i)intact metaphase figures, ii)chromosome damage confined to a small area of the metaphase spread, iii)mitotic figures with damage on all chromosomes. category iii might be the consequence of a non-localized distortion of nuclear metabolism. b ...19761002167
cytotoxic effects of hyperthermia and adriamycin on chinese hamster cells.chinese hamster cells, exposed to simultaneous hyperthermia (43 degrees c) and adriamycin (adm), were intially sensitized to the cytotoxic activity of adm. if the duration of the combined treatment exceeded about 30 minutes, however, the cells became refractory to additional killing by adm. if heat was applied before adm exposure, the cells also could be rendered insensitive; this state persisted so that 24 hours after a 50-minute exposure to 43 degrees c, the cells still showed considerable res ...19761003542
nature of 3,6-bis(5-chloro-2-piperidinyl)-2,5-piperazinedione-induced cytotoxicity in chinese hamster ovary cells.we sutdied the effect of 3,6-bis(5-chloro-2-piperidinyl)-2,5-piperazinedione (bcp) on various parameters of the replication cycle and cell grwoth on monolayer cultures of chinese hamster ovary cells. the results indicated that bcp had no effect on the g-s transition or the passage of cells from metaphase to g. however, bcp prolonged s- and g-phases because of its retarding effect on dna synthetis. bcp was more toxic to s-phase cells than to g or mitotic cells. as with other alkylating agents, ch ...19761003560
induction and isolation of cold-sensitive lines of chinese hamster cells. 19761004229
biochemical and electron-microscopic evidence that the subunit structure of chinese-hamster-ovary interphase chromatin is conserved in mitotic chromosomes.biochemical and electron microscopic studies demonstrate that the subunit structure of chinese hamster ovary cell interphase chromatin is conserved in mititic chromosomes. digestion of purified chromosomes or nuclei with micrococcal nuclease produces dna in discrete size classes, as visualized by polyacrylamide gel electrophoresis, which are common to the two materials. early in digestion the dna fragments are integral multiples of a monomer approximately 177 base pairs in length, whereas after ...19761009941
[changes in permeability and labeled thymidine incorporation into dna in a culture of chinese hamster cells exposed to mea and low temperatures]. 20131013308
carcinogenic effects of different nitroso-compounds in chinese hamsters: n-dibutylnitrosamine and n-nitrosomethylurea.three hundred and twenty chinese hamsters (cricetulus griseus) (ch) were subcutaneously (s.c.) treated with 1/5, 1/10 or 1/20 the mean lethal dose (ld50) of n-dibutylnitrosamine (dbn) or n-nitrosomethylurea (nmu). in several respects these two substances produced the same organotropy in the ch as in the syrian golden (sgh) and european hamsters (eh). dbn prolonged lung tumours and neoplasms of the injection site. nmu induced tumours of the injection site only.19761016942
selection of temperature-sensitive chl asparagyl-trna synthetase mutants using the toxic lysine analog, s-2-aminoethyl-l-cysteine.we developed a procedure, using the toxic lysine analog s-2-aminoethyl-l-cysteine (thialysine) as the selective agent, to obtain mutant chinese hamster lung (chl) fibroblasts with temperature-sensitive defects affecting protein synthesis. the procedure is efficient, rapid, and simple. using this selective system, we isolated six temperature-sensitive mutants that fail to grow (plating efficiencies less than 10-5) and synthesize protein at 39 degrees c. the temperature-sensitive phenotype of five ...19761017011
enhance anchorage independence and tumorigenicity of aneuploid chinese hamster cells with nearly doubled chromosome complements.the role of a cell's chromosome complement in its tumorigenic and anchorage-independent growth properties in vitro was investigated by injecting a chinese hamster cell line and its subclones into immunodeficient nude mice and by plating the cells in a semisolid medium containing methylcellulose. the parental wor-6 cell clone originally consisted of 89% 1s cells and 11% cells with a nearly double (2s) complement. tumors that developed from wor-6 were found to consis entirely or primarily of cells ...19761022225
carbohydrate metabolism in chinese-hamster cells. 19941022555
human gene locations achieved by means of human-chinese hamster (cho-k1) auxotrophic cell hybridization. 19761024644
expression of human x-chromosomal markers in man-chinese hamster hybrids treated with isolated human chromosomes. 19761024646
proposed banding nomenclature for the chinese hamster chromosomes (cricetulus grises). 19761024658
effect of carbohydrates on growth inhibition by d-mannosamine of glucosamine-requiring mutant cells of chinese hamster lung cells. 19761026666
the selection of chinese hamster cells deficient in oxidative energy metabolism.a selection scheme based on the nutritional requirements of a previously described respiration-deficient chinese hamster line has been used to isolate new mutants defective in oxidative energy metabolism. three of the primary characteristics of this type of mutant are (1) a strict dependency on the continued presence of glucose for survival; (2) a drastic reduction in the rate of oxygen consumption; (3) an inhibition of krebs cycle activity resulting in auxotrophy for asparagine and carbon dioxi ...19761027147
transfer of the human x chromosome to human--chinese hamster cell hybrids via isolated hela metaphase chromosomes.evidence is presented for the uptake of the human x chromosome by human-chinese hamster cell hybrids which lack h p r t activity, following incubation with isolated human hela s3 chromosomes. sixteen independent clonal cell lines were isolated in h a t medium, all of which contained a human x chromosome as determined by trypsin-giemsa staining. the frequency of h a t-resistant clones was 32 x 10(-6) when 10(7) cells were incubated with 10(8) hela chromosomes. potential reversion of the hybrid ce ...19761027148
mutant alleles for hypoxanthine phosphoriboxyltransferase: codominant expression, complementation, and segregation in hybrid chinese hamster cells.chinese hamster ovary cell mutants resistant to the purine analogs 6-thioguanine or 8-azaguanine have been isolated following mutagenesis with ethyl methane sulfonate. the activities of hypoxanthine phosphoribosyltransferase (hprt) in three such mutants have been found to exhibit an increased km for the substrate 5-phosphoribosyl-1-pyrophosphate. the isoelectric point of the mutant enzyme activity has also changed in two mutants. hybrid cells containing one mutant and one wild-type allele expres ...19761027153
asynchronous dna replication and asymmetrical chromosome loss in chinese hamster-mouse somatic cell hybrids.a number of parameters were measured in a series of 12 hybrid cell clones from chinese hamster and mouse cells to test the hypothesis that asymmetrical chromosome loss may result from asynchrony in the replication of the two parental sets of chromosomes. all clones tended to lose telocentric (mouse) chromosomes with culture time, irrespective of the starting ratio of parental chromosomes, and in all clones, biarmed (hamster) chromosomes appeared to complete dna replication slightly earlier than ...19761028157
reactivation of chick erythrocyte nuclei in heterokaryons with temperature-sensitive chinese hamster cells.chinese hamster cell line k12 is temperature-sensitive for the initiation of dna synthesis. k12 cells synchronized by serum deprivation were collected in early g1(g0). heterokaryons were formed by fusing chick erythrocytes with serum-starved k12 cells through the use of uv-irradiated sendai virus. at the permissive temperature (36.5 degrees c), erythrocyte nuclei in heterokaryons enlarged, the chromatin dispersed, and erythrocyte nuclei synthesized dna at about the same time as the k12 nuclei. a ...19761028158
biochemical genetics of chinese hamster cell mutants with deviant purine metabolism iii. isolation and characterization of a mutant unable to convert imp to amp.the isolation and characterization of a new mutant of chinese ovary cells (cho-k1) is described. this mutant, ade-h, has the following properties: (1) it forms a new genetic complementation group; (2) it specifically requires adenine for growth and will not grow on aminoimidazole carboxamide (aic) or hypoxanthine; (3) it accumulates imp; (4) it cannot synthesize adenine nucleotides; (5) its phenotype can be mimicked by treatment of cho-k1 (the wild type parental strain) with hadacidin, an inhibi ...19761028159
isolation and characterization of temperature-sensitive mutants of chinese hamster ovary cells after treatment with uv and x-irradiation.the isolation of ten conditionally lethal temperature-sensitive mutants of the chinese hamster ovary cell (cho-kl, pro-) by the budr-visible light selection procedure described. treatment with radiation at doses known to cause single gene mutation in mammalian cells increases the mutation frequency by a factor of at least 14. these mutants will grow with normal plating efficiency at 34.5 degrees but will not grow at 39.5 degrees. complementation analysis by two independent methods indicates that ...19761028162
expression of human hypoxanthine phosphoribosyl transferase in chinese hamster cells treated with isolated human chromosomes.chinese hamster cells deficient for the enzyme hypoxanthine phosphoribosyl transferase (hprt) were incubated with isolated human metaphase chromosomes and 21 colonies were isolated in hat medium. three different types of cell lines were established from these clones. first, 4 cell lines had 10-30% of normal chinese hamster hprt activity with the same electrophoretic mobility as human hprt. this hprt activity remains detectable during at least 8 weeks of growth of the cells in nonselective medium ...19761028163
differential staining of interspecific chromosomes in somatic cell hybrids by alkaline giemsa stain.staining of chromosome preparations of chinese hamster-human hybrid cells and mouse-chimpanzee hybrids with alkaline giemsa has yielded color differentiation of the interspecific chromosomes. bicolor chromosomes, indicating apparent translocations also are observed for each of these hybrids. the specific color differences observed provide a rapid means of recognizing and aiding in the identification of the interspecific chromosomes and apparent translocations in these somatic cell hybrids.19761028166
biochemical selection systems for mammalian cells: the essential amino acids.the essential amino acid requirement of cultured mammalian cells can be satisfied by 19 amino acid derivatives. this finding (a) confirms the results of animal nutritional studies and (b) identifies 19 essential amino acid derivatives and should permit the isolation of a new class of auxotrophic mutants. five naturally occurring auxotrophic markers have been detected in this survey; namely, inability to utilize cystathionine and citrulline in chinese hamster ovary (cho) cells, inability to metab ...19761028167
biochemical genetics of chinese hamster cell mutants with deviant purine metabolism. iv. isolation of a mutant which accumulates adenylosuccinic acid and succinylaminoimidazole carboxamide ribotide.the production, isolation, and characterization of a new complementation group (ade-i) of adenine-requiring mutant of chinese hamster cells (cho-k1) is described. this mutant accumulates two intermediates of purine biosynthesis, both of which contain an aspartate moiety. one of these is shown to be adenylosuccinic acid (amps) by chromatographic analysis, while evidence is presented that strongly suggests the other intermediate is succinylaminoimidazole carboxamide ribotide (saicar). thus, ade-i ...19761028168
isolation of mutants lacking branched-chain amino acid transaminase.variants of the chinese hamster ovary cell have been isolated which can no longer grow when valine, leucine, or isoleucine is replaced in the culture medium by its respective alpha-keto acid: alpha-ketoisovaleric acid, alpha-ketoisocaproic acid, or alpha-keto-beta-methylvaleric acid. these variants lack branched-chain amino acid transaminase activity. evidence is presented indicating these variants to be single gene mutants. genetic evidence is also presented confirming previous biochemical evid ...19761028171
isolation and partial characterization of three methotrexate-resistant phenotypes from chinese hamster ovary cells.three mechanisms for resistance to methotrexate (mtx) have been identified in chinese hamster ovary (cho) cells selected from resistance to this drug. first-step selections produce cells with either an apparent structural alteration in the enzyme dihydrofolate reductase (class i), or a decreased permeability to the drug (class ii). mutagenesis with ethyl methanesulfonate increases the proportion of mtx-resistant cells 5-10-fold. second-step selections to higher resistance using class i resistant ...19761028172
isolation of a factor causing morphological changes of chinese hamster ovary cells from the culture filtrate of vibrio parahaemolyticus.a factor changing chinese hamster ovary cells from an oval to a spindle shape was isolated from the culture filtrate of vibrio parahaemolyticus. it was partially purified by successive column chromatographies on diethylaminoethylcellulose, diethylaminoethyl-sephadex a-25, hydroxylapatite, and sephadex g-200. this factor was separated from thermostabl direct hemolysin and was heat labile.19761033156
the production and action of interferon in chinese hamster cells.the interferon system has been investigated in primary cell cultures established from chinese hamster embryos and new born pups. interferon synthesis was induced with sindbis virus, ultraviolet inrradiated newcastle disease virus (u.v.-ndv) and with polyriboinosine acid-polyribocytidylic acid complex [poly (ri). poly (rc)]. only u.v.-ndv induced significant production of interferon, maximum amounts being produced in 'aged' cells. its apparent mol. wt. was 25000. cho-ki cells, an established line ...19761033270
[development of spontaneous mutations in somatic mamalian cells and dna replication. ii. expression of gene mutations in cultured cells].the dependence of spontaneous rate and phenotypic expression of 6-mercaptopurine resistance mutations of dna replication synthesis was studied in cultured chinese hamster cells. spontaneous mutations arising with a constant rate per cell per time unit independently on dna replication rate were shown to be expressed only in the course of subsequent cell divisions. the frequency of n-nitrosomethylurea induced mutations in cells with reduced and normal dna replication rate is approximately the same ...19761034583
[protein sh-group concentration and rna synthesis during the process of induction of proliferation in the stationary phase of cell culture growth].the dynamics of intracellular protein sh-group (psh) content was studied cytochemically in the course of stimulation of cell proliferation in stationary cultures of an established chinese hamster cell line and of human diploid embryo fibroblasts. the results were compared with the pattern of rna synthesis during the prereplicative period. in chinese hamster cells immediately after medium changing in stationary cultures there is an augmentation of psh content in parallel withe the increase in rna ...19761034987
[changes in the cytochemical properties of chromatin after stimulating proliferation in a stationary culture of chinese hamster cells].the first part of the prereplicative period in stimulated for cell proliferation steady-state culture of chinese hamster cells was studied cytochemically. investigation of the binding pattern of basic dye acridine orange and actinomycin d with cell nuclei and the melting profile of chromatin in situ suggests that one of the early events occurring in the course of stimulation of cell proliferation in steady-state culture is chromatin activation, i.e. changes in its physicochemical properties resu ...19761034988
[duration of the mitotic cycle of chinese hamster cells cultured at 30--39 degrees].the duration of the mitotic cycle (t) at temperatures of 30, 33, 36 and 39 degrees c was studied in subline 237 of chinese hamster cells with the aid of the radioautographic method. t was the least at 39 degrees c and increased with reduction of the cultivation temperature. at the temperature range of 33--39 degrees c prolongation of t and its periods was "proportional" to the temperature under study. the characteristic curve gradient of t dependence on the temperature showed a sharp change in t ...19761035117
genetic characterization of methotrexate-resistant chinese hamster ovary a previous report, we described the selection and partial characterization of three methotrexate (mtx)-resistant chinese hamster ovary cells (cho) (1). class i cells contained an apparent structural alteration in dihydrofolate reductase. class ii cells had an alteration affecting the permeability of the drug. class iii cells, selected from class i cells, had an increased activity of the altered enzyme. in the work described here, it has been shown that the spontaneous mutation rate to class i ...19761035580
[damaging effect of 3h-uridine on tissue culture cells during the logarithmic and stationary phases of growth].the chinese hamster fibroblasts entered the stationary phase of growth after 5.5 days of cultivation. the induction of the culture proliferation occurred within the first 4 hrs of cultivation in the fresh nutrient medium. after addition of 3h-uridine in high concentration and with high specific activity (75 micron cu/m and 23 cu/mm), in the stationary phase a lesser number of cells with aberrations and a higher mitotic index were noted than in the logarithmic phase. 3h-uridine injured the cells ...19761036114
[on the simultaneous effects of ionising radiation and chemical agents on animal cells. 1st communication. cytogenetic studies on x-rays and isonicotinic acid hydrazide in the chinese hamster, cricetulus griseus (author's transl)].in bone marrow cells of chinese hamsters enhanced chromosome damage is observed after 48 h treatment of the animals with isoniazid (inh) combined with x-rays only at much higher doses than normally applied in human therapy. compared to x-ray-induced aberration levels, 125 mg/kg inh and 50 r given simultaneously increase the number of gaps and breaks, the latter being increased over-additively. this points to an interaction between both agents. the combined treatment changes the mitotic rate of t ...19761036915
relationship between experimental results in mammals and man. ii. cytogenetic analysis of bone-marrow cells after treatment of cytembena and cyclophosphamide- cytembena combination.cytogenetic analysis and the micronucleus test of bone-marrow cells was used to study the possible extrapolation of results from experimental animals to man. cytembena was given i.p. in doses of 5, 10, 20, 40 and 80 mg/kg body wt. to wistar rats and in doses of 20, 40 and 80 mg/kg body wt. to icr mice and to chinese hamsters. five patients with various types of malignancy, so far medically untreated, received 20 mg cytembena/kg body wt i.v. a combination of cytembena and cylophosphamide was appl ...19761037016
proceedings: cytotoxic effects of electromagnetic radiation on chinese hamster cells in culture. 19761047668
isolation of mammalian cell mutants deficient in glucose-6-phosphate dehydrogenase activity: linkage to hypoxanthine phosphoribosyl transferase.mutants of chinese hamster ovary cells deficient in glucose-6-phosphate dehydrogenase (d-glucose-6-phosphate: nadp 1-oxidoreducatse, ec activity were isolated after mutagenesis with ethyl methane sulfonate. the mutants were induced at frequencies of about 10-4 and do not differ in growth properties from wild-type cells. they were isolated by means of a sib selection technique coupled with a histochemical stain of colonies for enzyme activity. the lack of enzyme activity is not due to a ...19751054832
chromosome measurement and sorting by flow systems.a flow microfluorometer was used to measure metaphase chromosomes in suspension at rates up to 100,000 per min. chromosomes from cells of the chinese hamster m3-1 cell line were isolated, stained for dna with the fluorescent dye ethidium bromide, and analyzed for dna content. nine distinct peaks were resolved that correspond well with independent chromosomal dna measurements made with a high-resolution scanning cytophotometer. chromosomes were sorted from each peak by an electronic cell sorter. ...19751055399
hemoglobin synthesis in somatic cell hybrids: coexpression of mouse with human or chinese hamster globin genes in interspecific somatic cell hybrids of mouse erythroleukemia cells.somatic cell hybrids were derived by fusion of mouse erythroleukemia cells with fractionated human marrow enriched in erythroblasts, or with chinese hamster fetal liver erythroid cells. such interspecific hybrid cells, when isolated in suspension culture, had retained nearly all the mouse chromosomes and had lost most of the human or chinese hamster chromosomes. however, two such hybrids (one human, the other hamster) studied 4-6 weeks after fusion, were found to contain several non-mouse chromo ...19751058482
chinese hamster ovary cells selected for resistance to the cytotoxicity of phytohemagglutinin are deficient in a udp-n-acetylglucosamine--glycoprotein n-acetylglucosaminyltransferase activity.several clones of chinese hamster ovary cells resistant to the cytotoxicity of the phytohemagglutinin from phaseolus vulgaris show decreased binding of 125i-labeled phytohemagglutinin and contain decreased levels of a udp-n-acetylglucosamine--glycoprotein n-acetylglucosaminyltransferase (ec; udp-2-acetamido-2-deoxy-d-glucose:glycoprotein 2-acetamido-2-deoxy-d-glucosyltransferase) activity when compared to wild-type cells. the decrease in transferase activity varies from 45% to 96%, depe ...19751059116
inhibition of tubulin assembly by rna and other polyanions: evidence for a required protein.nonneural cell extracts contain a heat-stable, nondialyzable activity that will inhibit the spontaneous assembly in vitro of partially purified brain tubulin. the sensitivity of this inhibitory activity to ribonucleases but not to a variety of other hydrolytic enzymes indicates that the inhibitor is an rna. this conclusion is supported by the observation that purified rnas from sea urchins, chinese hamster ovary cells, and brain all inhibit spontaneous microtubule assembly in vitro. the syntheti ...19751059144
colchicine permeation is required for inhibition of concanavalin a capping in chinese hamster ovary cells.several antimitotic, tubulin-binding agents, such as colchicine, colcemid, and podophyllotoxin, inhibit the capping of fluorescent-labeled concanavalin a in chinese hamster ovary cells. by comparing the effects of these agents on parental cell lines on several independently selected colchicine-resistant mutants with decreased drug permeability, we have demonstrated that permeation of these drugs in required for inhibition of capping. these data support the hypothesis that these antimitotic agent ...19751060133
mutability of different genetic loci in mammalian cells by metabolically activated carcinogenic polycyclic hydrocarbons.the relationship between carcinogenesis and mutagenesis in mammalian cells has been determined with 10 polycyclic hydrocarbons with different degrees of carcinogenicity. mutagenesis was determined in chinese hamster cells with genetic markers that affect the surface membrane, nucleic-acid synthesis, and protein synthesis. the mutations were characterized by resistance to ouabain, 8-azaguanine, and temperature. mutagenesis by the carcinogens required metabolic activation and this was provided by ...19761061115
genetics of somatic mammalian cells: genetic, immunologic, and biochemical analysis with chinese hamster cell hybrids containing selected human chromosomes.through hybridization of specific chinese hamster cell auxotrophs with human cells and selection in media lacking the nutritional supplements required by the former cells, a series of stable hybrid clones can be prepared. these hybrids have genomes consisting of a common part--the complete or almost complete set of chinese hamster chromosomes, plus a variable part--one or a few human chromosomes. the identity of the human chromosomes can be varied by utilizing different chinese hamster auxotroph ...19761061117
identification of mutagenic metabolites of benzo(a)pyrene in mammalian cells.the mutagenicity of benzo[a]pyrene and 15 of its derivatives, which included phenols, the benzo[a]yrene-4,5-epoxide (the k-region epoxide), dihydrodiols, two isomeric 7,8-diol-9,10-epoxides, a 6-methyl derivative, and a 6-hydroxymethyl derivative, were tested with chinese hamster v79 cells in order to identify the mutagenic metabolites of benzo[a]pyrene. mutations were characterized by resistance to ouabain or 8-azaguanine. since v79 cells do not metabolize polycyclic hydrocarbons, mutagenesis w ...19761061161
dna strand breaks, repair, and survival in x-irradiated mammalian cells.the yields of unrepairable single-and double-strand breaks in the dna of x-irradiated chinese hamster cells were measured by low-speed neutral and alkaline sucrose density gradient sedimentation in order to investigate the relation between these lesions and reproductive death. after maximal single-strand remoining, at all doses, the number of residual single-strand breaks was twice the number of residual double-strand breaks. both double-strand and unrepairable single-strand breaks were proporti ...19761062792
cytological evidence for switches in polarity of chromosomal dna.from the types of ring chromosomes induced in x-irradiated chinese hamster ovary (cho) cells, we deduce the existence of switches in the polarity of chromosomal dna; if there is a continuous dna double helix along the full length of the chromosome then the polarity switches imply 3'-3' and 5'-5' phosphodiester linkages. the resolution of the method is such that we estimate that there is one polarity switch for every 10(9) normal 3'-5' phosphodiester bonds.19761062800
nucleus anomaly test and chromosomal analysis of bone marrow cells of the chinese hamster and dominant lethal test in male mice after treatment with fluorescent whitening agents.four fluorescent whitening agents (fwas) were tested for mutagenic activity after oral administration in the following three different mammalian test systems: (1) dominant lethal test in the male mouse; (2) cytogenetic studies on metaphase chromosomes from the bone marrow of the chinese hamster; (3) nucleus anomaly test in somatic interphase cells (bone marrow) of the chinese hamster. these investigations yielded no evidence of dominant lethal effects of any of the four compounds on the progeny ...19751064545
selenium is an essential trace nutrient for growth of wi-38 diploid human fibroblasts.the trace element selenium is essential for clonal growth of diploid fibroblasts from human fetal lung (wi-38) in media containing small amounts of serum protein. maximum growth stimulation is obtained when 30 nm neutralized selenious acid is added to a synthetic medium containing 1.5 mg/ml of dialyzed fetal bovine serum protein (equivalent to a 3% serum concentration). serum appears to be a source of selenium in most culture media, since higher concentrations of serum protein or whole serum mas ...19761064872
enhancement of postreplication repair in chinese hamster cells.alkaline sedimentation profiles of pulse-labeled dna from chinese hamster cells showed that dna from cells treated with n-acetoxy-acetylaminofluorene or ultraviolet radiation was made in segments smaller than those from untreated cells. cells treated with a small dose (2.5 mum) of n-acetoxy-acetylaminofluorene or (2.5 j-m-2) 254-nm radiation, several hours before a larger dose (7-10 mum) of n-acetoxy-acetylaminofluorene or 5.0 j.m-2 of 254 nm radiation, also synthesized small dna after the secon ...19761065893
a purine auxotroph deficient in phosphoribosylpyrophosphate amidotransferase and phosphoribosylpyrophosphate aminotransferase activities with normal activity of ribose-5-phosphate aminotransferase.three enzyme reactions have been reported to catalyze the synthesis of phosphoribosylamine in eukaryotic cells. these activities are glutamine phosphoribosylpyrophosphate (p-rib-p-p) amidotransferase [amidophosphoribosyl-transferase; 5-phosphoribosylamine: pyrophosphate phosphoribosyltransferase (glutamate-amidating) ec], ammonia p-rib-p-p aminotransferase, and ammonia ribose-5-phosphate aminotransferase. a purine auxotroph derived from a cell line of chinese hamster fibroblasts was sho ...19761065900
5-bromodeoxyuridine-dna strand symmetry and the repair of photolytic breaks in chinese hamster cell chromosomes.experiments described in this report quantiate the black light sensitivities of chinese hamster lung (chl) cells containing brdurd-dna of defined composition. cesium chloride equilibrium gradient centrifugation provides estimates both of the percent thymidine replacement by brdurd and of the symmetry (unifilar versus bifilar) of brdurd incorporation into the chromosomal dna duplexes. radiation damage to brdurd-substituted chl cell dna and its repair in situ also have been assessed by alkaline su ...19761069276
quantized generation time in mammalian cells as an expression of the cellular clock.the distribution of possible generation times in mammalian cells does not appear to be continous within the limits of range for each cell type; rather, generation time is quantized in multiples of 3-4 hr. synchronous cultures of chinese hamster v79 cells were prepared using manual and automated methods to select and stage mitotic cells. using synchronous cultures and time-lapse video tape microscopy, it was possible to show that generation times within a population of mitotically selected cells ...19761069287
study of markers of human erythroid differentiation in hybrid cells.somatic cell hybrids exhibiting co-expression of the globin genes of two species were generated by fusion of mouse erythroleukemia cells with chinese hamster or human marrow erythroid cells. in contrast, extinction of the mouse globin genes occurred in hybrids formed between the erythroleukemia cells and human fibroblasts. direct detection of the human globin genes in human x mouse fibroblast hybrids was achieved by annealing of dna from these cells to human globin complementary dna. this method ...19761071439
interaction of gamma-ray and neutron effects on the proliferative capacity of chinese hamster cells.the loss of reproductive capacity of chinese hamster cells has been studied using 60co gamma-rays and dt neutrons singly or combined in fixed proportions. surviving fractions were measured down to 2 times 10-4. interaction between the effects produced by neutrons and gamma-rays in the mixed irradiations has been demonstrated. the results are compared with those predicted by the cellular inactivation model developed by katz and co-workers from their delta-ray theory of track structure.19751078820
survival of synchronized chinese hamster cells exposed to radiation of different linear-energy transfer.chinese hamster v79 cells were exposed to ionizing radiations of a wide range of linear-energy transfer (let), including 145kv x-rays and six different heavy ions accelerated in the berkeley heavy-ion linear accelerator. the let of the ions ranged from 19 kev/um to 2000 kev/um. survival curves were determined for both synchronized and asynchronous cells, using survival of colony-forming capacity as the end-point. results with asynchronous cultures were similar to results reported previously for ...19751079018
a temperature-sensitive auxotropic variant of chinese hamster ovary cells. 20041079492
the oxygen-enhancement ratio for reproductive death induced by 3h or 125i damage in mammalian cells.the oxygen-enhancement ratio (o.e.r.) for 3h- and 125i-induced cell death at 4 degrees c was determined in cultured chinese hamster cells. the o.e.r. for cell death induced by 3h-thymidine was 3-2, essentially the same value as that previously reported for x-ray induced cell death. for cell death induced by 125i-iododeoxyuridine (125idurd), the o.e.r. was less than 1-4. the lower o.e.r. for 125i-induced death was not due to the presence of the base analogue itself, since cells that had incorpora ...19751081976
dip and dip+2 as glutathione oxidants and radiation sensitizers in cultured chinese hamster cells.two diamide analogues, diazene dicarboxylic acid bis (n'-methylpiperazide) or dip, and its bis-n'-methyl iodide salt, or dip + 2, were tested for their ability to penetrate cultured chinese hamster cells and oxidize intracellular glutathione. dip penetrated the cells at a reasonable rate at 18 degrees c, 160 nmoles being required to oxidize the endogenous glutathione of 2 x 10(6) cells, but it penetrated very slowly at 0 degrees c. dip +2 did not effectively oxidize glutathione in chinese hamste ...19751081977
carcinogenesis in tissue culture 25: reduced tumorigenicity of alkaline phosphatase-constitutive variants from chinese hamster ovary cells.several subclones with high alkaline phosphatase (alp) activity were isolated from alp-negative chinese hamster ovary cells (cho-k1). when inoculated into cheek pouch membranes of syrian golden hamsters treated with anti-hamster thymocyte serum (ats), alp-negative cho-k1 cells produced progressively growing tumors, whereas the cells of alp-positive subclones did not, although small nodules were formed temporarily. the animals injected cho-k1 cells died of tumor by 35 days after grafting, and met ...19751083437
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