Publications
| Title | Abstract | Year(sorted descending) Filter | PMID Filter |
|---|
| significance of dimers to the size of newly synthesized dna in uv-irradiated chinese hamster ovary cells. | dna synthesized after uv irradiation is smaller than that in unirradiated cells even when pulse-labeling times are increased to compensate for the overall reduction in the rate of dna replication. by isolating newly replicated dna, incubating it with dimer-specific endonuclease from micrococcus luteus, and analyzing it on alkaline sucrose gradients, we have been able to demonstrate that this dna is synthesized in segments corresponding in size to the interdimer distance on the parental strand. i ... | 1976 | 963196 |
| surface polypeptides of the chinese hamster ovary cell; an immunochemical study. | antibodies elicited by the injection of live chinese hamster ovary cells (cho) into rabbits precipitated four major components from detergent extracts of cho membranes. the four components, of molecular weights 200000, 125000, 95000 and 41000 daltons, corresponded to cell surface components identified by the lactoperoxide surface label technique. | 1976 | 944075 |
| behavioral development in three hamster species. | the preweaning behavioral development was compared in 3 hamster species: the golden (mesocricetus auratus), chinese (cricetulus griseus), and djungarian (phodopus sungorus). differences in the age of appearance of action patterns could not be summarized by simply ranking species on either precocity or developmental speed, nor were they eliminated by measuring age from conception. problems in the interpretation of species differences in the age of appearance of action patterns are discussed. | 1976 | 955290 |
| human gene locations achieved by means of human-chinese hamster (cho-k1) auxotrophic cell hybridization. | 1976 | 975914 | |
| expression of human x-chromosomal markers in man-chinese hamster hybrids treated with isolated human chromosomes. | 1976 | 975919 | |
| 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 ... | 1976 | 986241 |
| 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 ... | 1976 | 1001138 |
| 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 ... | 1976 | 1071439 |
| 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 ... | 1976 | 1009941 |
| the human gene for beta glucuronidase is on chromosome 7. | inconsistent assignments of the human gene for beta glucuronidase (gus) to chromosomes 7 and 9 have previously been reported. in this study, we have correlated the expression of human gus in 22 primary chinese hamster/human hybrid lines with quantitative cytogenetic analysis. eight hybrids were positive for human gus as manifested by a five-band pattern on electrophoresis. all of them contained a human chromosome 7 in 34% or more of cells, and seven of them had not retained chromosome 9. one hyb ... | 1976 | 941903 |
| profiles of brain glycosidase activity in cuprizone-fed syrian hamsters and in scrapie-affected mice, rats, chinese hamsters and syrian hamsters. | 1976 | 943426 | |
| cytogenetic effects of mutagens/carcinogens after activation in a microsomal system in vitro i. induction of chromosome aberrations and sister chromatid exchanges by diethylnitrosamine (den) and dimethylnitrosamine (dmn) in cho cells in the presence of rat-liver microsomes. | a rat-liver microsomal system in vitro has been used to activate two indirectly acting carcinogens, dmn and den. on activation, both compounds were extremely potent in inducing chromosomal aberrations as well as sister chromatid exchanges in chinese hamster cells. the implications of these findings and the potential utility of this technique to detect mutagens/carcinogens are discussed. | 1976 | 967188 |
| 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 ... | 1976 | 986240 |
| human gene locations achieved by means of human-chinese hamster (cho-k1) auxotrophic cell hybridization. | 1976 | 1024644 | |
| 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 ... | 1976 | 967189 |
| sister chromatid exchange as an assay for genetic damage induced by mutagen-carcinogens. ii. in vitro test for compounds requiring metabolic activation. | sister chromatid exchanges (sce's) which are easily seen by "harlequin chromosome" techniques can be readily induced in cultured chinese hamster ovary (cho) cells by low concentrations of mutagen-carcinogens that do not require metabolic activation. if the cells are simultaneously treated with cyclophosphamide which does require metabolic activation before it becomes mutagenic, and an activating system consisting of an extract of rat liver containing microsomes (s-9 mix) then numerous sce's are ... | 1976 | 796721 |
| mutagenicity and metabolism of vinyl chloride and related compounds. | the various adverse biological effects of vinyl chloride appear to be dependent upon the metabolic conversion of this compound into chemically reactive metabolites. the metabolism of vinyl chloride in mammals and in man, including the formation of monochloroacetic acid and some identified sulfur conjugates is reviewed. hepatic microsomal mixed function oxidases from rats, mice, and humans were equally effective in transforming vinyl chloride into alkylating agents in vitro. two of the enzyme rea ... | 1976 | 799962 |
| interpretative differences in cytogenetic analyses: preliminary results of a collaborative study. | in an effort to establish some of the parameters which influence differences in interpretation of chromosome aberrations, we initiated a collaborative study with 26 different laboratories located in the u.s., canada and europe. they include government, private industry, and academic institutions. three species were selected for study which vary in chromosome number and complexity of the karyotype. these were the chinese hamster, human, and african green monkey. each metaphase was preselected and ... | 1976 | 829598 |
| isolation and properties of heat-labile enterotoxin(s) from enterotoxigenic escherichia coli. | various techniques have been applied to the detection of skin reactivity associated with heat-labile escherichia coli enterotoxin in fermenter-grown cultures of enterotoxigenic strains in syncase medium and in trypticase soy broth. isolated products that were homogeneous, as determined by disc electrophoresis and sodium dodecyl sulfate gel electrophoresis, differed immunologically and in physicochemical characteristics depending on the strain and medium used, even though the products had similar ... | 1976 | 768386 |
| animal models of diabetes and obesity, including the pbb/ld mouse. | diabetes mellitus occurs in many animals species. however, only a few have been utilized in systematic studies designed to answer unsolved problems associated with the disorder in man such as molecular basis, pathogenesis of the vascular and neural lesions, and the roles of diet, exercise and obesity. among the animal models available, rodents have been studied most thoroughly for a number of reasons: a) short generation time (sexually mature at about 3 mo of age, gestation time 21 days) and lif ... | 1976 | 770197 |
| inhibition of human lymphoma cell-line colony formation by lymphocytes from patients with lymphoma and cancer hospital employees. | inhibition of human lymphoma cell-line colony formation (icf) was induced by peripheral blood lymphocytes (pbl) from patients with lymphoma and apparently healthy cancer hospital personnel. pbl from patients with non-lymphoma neoplasms and from normal blood bank donors did not elicit icf. icf was most marked when pbl were cocultivated for 24 hours in a ratio of 1000:i with target lymphoma cells that had been cultured for 24 hours before exposure. no significant icf was observed when target cells ... | 1976 | 779948 |
| mutagenicity and cytotoxicity of benzo(a)pyrene arene oxides, phenols, quinones, and dihydrodiols in bacterial and mammalian cells. | twenty-nine benzo(a)pyrene derivatives were tested for mutagenic acitivity without metabolic activation in salmonella typhimurium strains ta98, ta100, and ta1538 and in chinese hamster v79 cells. the compounds studied included 4 arene oxides, all 12 isomeric phenols, 5 quinones, and 8 dihydrodiols. benzo(a)pyrene 4,5-oxide was the most mutagenic of the compounds tested in both the bacterial and mammalian systems. the other arene oxides [benzo(a)pyrene 7,8-, 9,10-, and 11,12-oxides] were only wea ... | 1976 | 788898 |
| mutagenicity and cytotoxicity of benzo(a)pyrene benzo-ring epoxides. | four benzo-ring epoxides of the environmental carcinogen benzo(a)pyrene (bp) were tested for mutagenic and cytotoxic activity in 3 strains of salmonella typhimurium (ta1538, ta98, and ta100) and in chinese hamster v79 cells. although very unstable in aqueous solution, 7beta,8alpha-dihydroxy-0beta,10beta-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene (diol epoxide 1), with the 7-hydroxyl group on the same face of the molecule as the epoxide oxygen, was 1.5 to 4 times as mutagenic in the bacterial strain ... | 1976 | 788899 |
| mutagenicity of industrial compounds: styrene and its possible metabolite styrene oxide. | styrene and its presumed metabolite, styrene oxide, were tested for their mutagenic effect on a forward mutation system of yeast and of chinese hamster cells, and on a gene-conversion system of yeast. experiments with liver microsomal preparations and host-mediated assay with yeast were also carried out. styrene oxide was mutagenic in all test systems. styrene was mutagenic only in the host-mediated assay. | 1976 | 796697 |
| the mutagenicity of benzimidazole and benzimidazole derivatives. vi. cytogenetic effects of benzimidazole derivatives in the bone marrow of the mouse and the chinese hamster. | methyl benzimidazole-2-ylcarbamate (mbc) was mutagenic in mice by the micro-nucleus test. other benzimidazole derivatives, with the exception of the parent compound of mbc, benomyl, and the very closely related substance 2-benzimidazolylurea, did not produce micro-nuclei in mouse bone marrow. evidence is presented that mbc acts through inhibition of mitosis and that for this action the carbamoyl group is a necessary but not a sufficient condition. it is also demonstrated that for this particular ... | 1976 | 796698 |
| the effect of insecticides on chinese hamster cell cultures. | the effect of p,p'-isomers of ddt and its derivatives ddd, dde and dda on chinese hamster cells in culture was studied. at different concentrations and various times of treatment the proliferation rate was inhibited most strongly by ddd and ddt, whereas dde exhibited a markedly weaker influence. dda was the least toxic compound of the four. the cytogenetic effects were also different. again, dda induced the least damage. only enhanced gap rates but no chromosome breaks were observed. dde was mor ... | 1976 | 934173 |
| metaphase chromosome anomaly: association with drug resistance and cell-specific products. | large, homogeneously staining chromosome regions which lack the longitudinal differentiation ordinarily revealed by cytogenetic "banding" methods have been found in antifolate-resistant chinese hamster cells and also in human neuroblastoma cells established in vitro. the drug-resistant cells are characterized by excessive production of the target enzyme, dihydrofolate reducatase, while the human neuroblastoma cells have phenotypes of normal neuronal cells. the homogeneously staining region appea ... | 1976 | 942798 |
| expression of human x-chromosomal markers in man-chinese hamster hybrids treated with isolated human chromosomes. | 1976 | 1024646 | |
| aging changes in intervertebral discs and spondylosis in chinese hamsters. | vertebrae and intervertebral discs of chinese hamsters, a species of rodents that develop spontaneous diabetes, were investigated for age-linked changes and for the occurrence of spondylosis. aging changes in the intervertebral discs were similar in diabetic and nondiabetic animals. the incidence of spondylosis was significantly increased and its onset was accelerated in the diabetic animals. the mechanisms operative in the pathogenesis of the lesions and their relation to the human disease are ... | 1976 | 819318 |
| evaluation and re-evaluation of genetic radiation hazards in man. ii. the arm number hypothesis and the induction of reciprocal translocations in man. | the arm number hypothesis proposed by brewen and collagues in 1973 has been examined in the light of information thus far available from mammalian studies. in experiments with peripheral blood lymphocytes (radiation in vitro), a linear relationship between dicentric yield and the effective chromosome arm number of the species was obtained in the mouse, chinese hamster, goat, sheep, pig, wallaby and man. however, the data are not consistent with such a relationship in several primate species (ma ... | 1976 | 819823 |
| biochemical evidence of variability in the dna repeat length in the chromatin of higher eukaryotes. | biochemical evidence is presented which confirms that the dna repeat length in micrococcal nuclease (spleen endonuclease, nucleate 3'-oligonucleotidohydrolase, ec 3-1-4-7) digests of chinese hamster ovary chromatin is shorter than that of rat liver chromatin [j.l. compton, r. hancock, p. oudet, and p. chambon (1976) eur. j. biochem., in press]. a survey of available cells has shown that the dna repeat length of the chromatin of higher eukaryotes varies widely. a value of 196 base pairs was found ... | 1976 | 826906 |
| confirmation of the assignment of the locus determining ada to chromosome 20 in man: data on possible synteny of ada and itp in human-chinese hamster somatic cell hybrids. | 1976 | 828861 | |
| intrachromosomal gene mapping in man: assignment of nucleoside phosphorylase to region 14cen leads to 14q21 by interspecific hybridization of cells with a t(x;14) (p22;q21) translocation. | the structural gene for purine-nucleoside phosphorylase (np) has been assigned to a subregion of chromosome 14 by somatic cell hybridization of male and female cells containing the balanced translocation t(x;14) (p22;q21). peripheral lymphocytes were fused to a pseudodiploid hprt-deficient established chinese hamster cell line. 23 primary hybrid clones (10 derived from male and 13 from female cells) were isolated and maintained in hat selective medium. parallel subcultures from generations 16, 2 ... | 1976 | 829289 |
| 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 ... | 1976 | 1027148 |
| [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 ... | 1976 | 1034987 |
| 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 ... | 1976 | 1028157 |
| 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 ... | 1976 | 1028158 |
| 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 ... | 1976 | 1028163 |
| 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. | 1976 | 1028166 |
| 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. | 1976 | 1033156 |
| 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 ... | 1976 | 1033270 |
| [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 ... | 1976 | 1035117 |
| 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 ... | 1976 | 1061117 |
| 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 ... | 1976 | 1037016 |
| 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 ... | 1976 | 1061161 |
| 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 ... | 1976 | 1064872 |
| [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 ... | 1976 | 1036915 |
| a comparative analysis of the karyotypes of cricetus cricetus and cricetulus griseus. | this study presents a comparison of the mitotic chromosomes of the two species of hamsters cricetus cricetus (european hamster) and cricetulus griseus (chinese hamster), which have the same chromosome number of 2n=22.--g-banding procedure reveals striking similarities in both karyotypes and gives the possibility to analyse structural changes so that two examples for robertsonian rearrangement can be observed.--a remarkable kind of difference between the two karyotypes becomes obvious after c-ban ... | 1976 | 1269344 |
| lack of synergistic effect between x-ray and uv irradiation on the frequency of chromosome aberrations in pha-stimulated human lymphocytes in the g1 stage. | pha-stimulated human lymphocytes in the g1 stage were irradiated with uv radiation and x-rays, and the cells were analyzed for chromosomal aberrations in the first mitotic division. the frequency of dicentric chromosomes after single x-irradiation in the g1 stage was about twice the yield in the g0 stage. no increase in the yield of dicentrics was observed after combined irradiation with uv and x-rays. this is contrary to the finding for g0 lymphocytes, where a 2-fold increase of chromosome aber ... | 1976 | 1250244 |
| selective modification of cell surface proteins and thymidine transport in hamster cells exposed to cholera toxin. | the increased adherence and morphological response which occurs in chinese hamster ovary cells as a result of exposure to cholera toxin is paralleled by modification in the relative exposure of outer proteins. mild proteolysis treatment of the cells prelabeled with [3h] glucosamine reveals a markedly different kinetics of release of external glycopeptides as a result of exposure to cholera toxin. selective alterations in external tyrosyl-rich proteins can also be detected by lactoperoxidase-cata ... | 1976 | 1256059 |
| effect of room fluorescent light on the deterioration of tissue culture medium. | a major cause of tissue culture medium deterioration is exposure to room fluorescent light. riboflavin and tryptophan present in dulbecco's modified eagle's minimum essential medium, when exposed to light, yield toxic photoproducts responsible for loss of the ability of the medium to support clonal growth of human, mouse and chinese hamster cell lines. procedures for minimizing medium deterioration are discussed. | 1976 | 1244326 |
| organisation of the genes coding for 5s rna in the chinese hamster. | hybridisation of iodinated mouse 5s rna with chinese hamster dna fractionated on a cscl gradient, identifies two separate dna components that hybridise with the labelled probe. one component is slightly, and one considerably heavier than the main band dna. this suggests that the gene coding for 5s rna in the chinese hamster may constitute two distinct populations differing in g + c content of their adjacent spacer regions. | 1976 | 1250414 |
| localization of the structural genes for hexokinase-1 and inorganic pyrophosphatase on region (pter-->q24) of human chromosome 10. | concordant expression of human hexokinase-1 and inorganic pyrophosphatase was established in somatic cell hybrids between thymidine kinase-deficient chinese hamster cells and human fibroblasts carrying a translocation of the distal third of the long arm of chromosome 10 to chromosome 17. neither human hexokinase-1 nor human inorganic pyrophosphatase expression segregated concordantly with human cytoplasmic glutamic-oxaloacetic transaminase expression. | 1976 | 17494625 |
| specific uptake of labelled n-nitrosomethylurea in the pancreatic islets of chinese hamsters. | 1975 | 1100425 | |
| proceedings: comparative studies on spermatogonia of mice and chinese hamsters after x-ray treatment. | 1975 | 1237786 | |
| proceedings: chromosome analysis in spermatocytes of mice and chinese hamsters. | 1975 | 1186750 | |
| proceedings: frequency of chromosome aberrations in bone marrow cells of chinese hamsters after treatment with cyclophosphamide or caffeine alone or together. | 1975 | 1186722 | |
| proceedings: a correlated study in lymphocytes and bone marrow cells of chinese hamsters after nbu treatment. | 1975 | 1186718 | |
| lack of effect of blood sampling-induced haematopoiesis on in vivo chromosome damage by cyclohexylamine in chinese hamsters. | 1975 | 1176074 | |
| uptake of labelled-n-nitrosomethylurea in the pancreatic islets. | labelled n-nitrosomethylurea was injected intravenously into mice (c57/bi strain) and chinese hamsters. in whole-body autoradiograms the isotope was found to accumulate heavily in the islet tissue of the chinese hamsters but not in that of the mice. the selective uptake in the islet of chinese hamsters was most pronounced after one hour. a dose of 50 mg/kg body weight of non-labelled n-nitrosomethylurea caused hyperglycemia in the chinese hamsters while no hyperglycemia occurred in the mice at a ... | 1975 | 809906 |
| experimental prevention of diabetes in prediabetics: studies of chinese hamsters. | 1975 | 1222533 | |
| saccharin: lack of chromosome-damaging activity in chinese hamsters in vivo. | 1975 | 1132847 | |
| an ultrastructural study of pancreatic islet cell destruction by n-nitrosomethylurea. | an ultrastructural study of the early effects of intraperitoneal injection of 50 mg/kg body weight of n-nitrosomethylurea on the pancreatic islet tissue in chinese hamsters was performed. thirty minutes after injection there was slight dilatation of the endoplasmic reticulum and mitochondrial swelling in a few peripheral alpha2-cells near to capillaries and also in some beta-cells. after 1 hour these changes were more pronounced. after 3 hours, distinct nuclear pyknosis was seen in endocrine isl ... | 1975 | 1096530 |
| [in vitro induction of numerical changes in the karyotype of normal and transformed cells of dzhungarian and chinese hamsters]. | the comparative study of the frequency of colcemid-induced aneuploidy and polyploidy in cultured normal and transformed cells of djungarian hamster is described. the occurrence of variants with changed chromosome number is much higher in populations of sv40-transformed cell line (4/21) than in normal embryonic cultures. in transformed lines of djungarian and chinese hamsters (4/21 and v-79) the frequency of cells with changed chromosome number was found to be depend on the culture density: the p ... | 1975 | 1241546 |
| pancreaticoduodenal transplantation in juvenile syrian and chinese hamsters. | 1975 | 766272 | |
| effect of heat and radiation on synchronous chinese hamster cells: killing and repair. | 1975 | 1197661 | |
| cytological detection of mutagen-carcinogen exposure by sister chromatid exchange. | a staining technique that detects sister chromatid exchanges (sces) has been used to examine the response of chromosomes in cultured chinese hamster cells to a wide variety of mutagens-carcinogens. the test gives a very sensitive and rapid method for detecting chromosome mutagenicity of chemical agents and provides a powerful new method for detecting environmental mutagens. | 1975 | 52847 |
| a high resolution study of the dna replication patterns of chinese hamster chromosomes using sister chromatid differential staining technique. | chinese hamster cells were grown for 1+ and 2+ cell cycles in the presence of brdu and then treated by the sister chromatid differential staining technique (scd). those regions of a chromosome which had replicated twice in the presence of brdu were pale staining and by selecting appropriate metaphase cells an accurate reconstruction of the dna synthetic patterns was possible. a direct correlation between the staining intensity of the g bands and the order in which they replicate was found. dark ... | 1975 | 53130 |
| the effect of methylated oxypurines on the size of newly-synthesized dna and on the production of chromosome aberrations after uv irradiation in chinese hamster cells. | a comparison has been made, in chinese hamster cells, of the ability of various methylated oxypurines to inhibit post-replication repair of dna after uv irradiation and to potentiate uv-induced chromosome aberrations. dna synthesized in uv-irradiated cells contains gaps, which are subsequently sealed by a process termed post-replication repair. in rodent cells this process is inhibited by caffeine and its analogues. this has been quantitated by measuring the molecular weight of the dna synthesiz ... | 1975 | 1207709 |
| lack of specific correlation of the deoxycytidine triphosphate pool level with rate of dna synthesis. | the levels of the four deoxyribonucleoside triphosphate pools and the distribution of cells in the various phases of the cell cycle have been examined in chinese hamster cells as thymidine, present as a regular constituent in the growth medium, was removed in stages. the results indicate that: 1. duration of the dna synthetic phase was lengthened when thymidine was removed from the growth medium. 2. temporally correlated with lengthening of the dna synthetic phase upon thymidine removal was a 7- ... | 1975 | 1203255 |
| [conformational changes before and after dna synthesis increase cytogenetically lethal radiation damage]. | chinese hamster ovary fibroblasts were synchronized by mitotic selection and showed cytogenetic lethally acting radiation damages, which depended on age at irradiation time. the development of cell cultures was followed by counting of the killed cells in the 3rd daughter generation of the irradiated ones and by evaluation of the colony size spectra 73.5 h after innoculation. at a dose of 300 rads two narrow but high peaks of radiation sensitivity were induced, which appeared at the beginning and ... | 1975 | 1227981 |
| analysis of the replication pattern of chinese hamster chromosomes using 5-bromodeoxyuridine suppression of 33258 hoechst fluorescence. | chinese hamster fibroblasts were synchronized and given 5-bromodeoxyuridine for dna synthesis except during one hour of the s phase when thymidine was present in the medium. in the next mitosis, chromosomes stained with 33258 hoechst were banded in appearance when photographed by fluorescence microscopy. the bright regions corresponded to the chromosome segments replicated during the thymidine exposure in the s phase. the segments replicated together during any one hour produced three distinct p ... | 1975 | 53132 |
| isolation and characterization of variant clones of chinese hamster cells after treatment with irradiated 5-iodouridine. | variant clones were isolated from cultured chinese hamster don cells after treatment with irradiated 5-iodouridine. the following characters of a primary variant clone, c-11 and a secondary variant clone, c-24 were compared with those of the original clone c-1: colony-forming activity, growth rate in the presence of irradiated and unirradiated 5-iodouridine, distribution of chromosome numbers and cell cohesion. the variant clones c-11 and c-24 were partially resistant to unirradiated 5-iodouridi ... | 1975 | 1240593 |
| post-replication repair of dna in chinese hamster cells treated with cis platinum (ii) diamine dichloride. enhancement of toxicity and chromosome damage by caffeine. | the anti-tumor agent cis platinum (ii) diammine dichloride (cis pt(ii)) caused chromosomal abnormalities in chinese hamster v79-379a cells. the time of appearance of these abnormalities suggested that they arise as a consequence of dna synthesis on a damaged template. the yield and severity of chromosomal abnormalities was greatly enhanced by a non-toxic concentration of caffeine, and this enhancement was associated with a potentiation of cis pt(ii) induced cell death. these results suggest that ... | 1975 | 1240592 |
| schedule-dependent synergistic cytotoxicity of arabinofuranosylcytosine with adriamycin or 3,6-bis(5-chloro-2-piperidinyl)-2,5-piperazinedione in cultured cells. | the purpose of this study was to demonstrate that in vitro cell culture systems could serve a useful purpose in providing some guidelines in formulating drug schedules for combination cancer chemotherapy in the clinic. using monolayer cultures of chinese hamster ovary cells as the test system, we screened the combinations of 1-beta-d-arabinofuranosylcytosine (ara-c) + adriamycin, ara-c + 3,6 - bis(5 - chloro - 2 - piperidinyl) - 2,5 - piperazinedione, melphalan + 5-fluorouracil, and melphalan + ... | 1975 | 1182694 |
| 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 ... | 1975 | 1081977 |
| 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 ... | 1975 | 1081976 |
| 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 ... | 1975 | 1060133 |
| enhanced cell killing by bleomycin and 43 degrees hyperthermia and the inhibition of recovery from potentially lethal damage. | the effect of hyperthermia on bleomycin (bleo) toxicity and repair was studied in "unfed" monolayer cultures of chinese hamster cells. synergy of toxicities was observed with simultaneous exposure to bleo and 43 degrees. for example, when cells were exposed for 1 hr to bleo (40 mug/ml) at 43 degrees, survival was reduced to 4 x 10(-5); separately, hyperthermia and 37 degrees bleo exposure each resulted in a survival of 20%. heating at 43 degrees prior to drug exposure at 37 degrees also produced ... | 1975 | 52401 |
| cell cycle-dependent surface changes in chinese hamster cells grown in suspension culture. | 1975 | 1193160 | |
| concanavalin a as a selective agent in tissue culture for temperature-sensitive hamster cell lines. | a novel method for isolating chinese hamster cell cultures with temperature-sensitive growth properties is described. concanavalin a can be used as a selective agent in tissue culture to isolate lectin-resistant cell lines which exhibit colony-forming abilities at the nonpermissive temperature relative to the permissive temperature as low as 10(-4) to 10(-6). a general correlation exists between resistance to the lectin and temperature sensitivity. | 1975 | 1238161 |
| isolation and characterization of alkaline phosphatase-constitutive variants from chinese hamster ovary cells (cho-k1). | pure clones with high alkaline phosphatase (alp) activity were isolated from chinese hamster ovary (cho-k1) cells which showed no detectable alp activity. alp-positive cells appeared at the frequency of 10(-4) in the n-methyl-n'-nitrosoguanidine-treated cell population. with respect for cellular morphology, plating efficiency and several other enzymatic activities, no distinct difference was found between the original cho-k1 cells and its alp-positive variants, although some alterations in karyo ... | 1975 | 1194364 |
| selection and characterization of eight phenotypically distinct lines of lectin-resistant chinese hamster ovary cell. | clones resistant to the lectins phytohemagglutinin (pha), wheat germ agglutinin (wga), the agglutinin(s) from lens culinaris (lca), and ricin (ric) have been selected from parental auxotrophic chinese hamster ovary (cho) cells. the sensitivity to other lectins of these cells and of cho cells resistant to concanavalin a (cona) has been determined, and their activity of udp-n-acetyl-glucosamine glycoprotein n-acetyl-glucosaminyltransferase (glcnac-t) has been measured. at least 8 different phenoty ... | 1975 | 1182798 |
| cycloheximide resistance in chinese hamster cells. ii. induction of chm resistance in chinese hamster cells by n-nitrosomethylurea. | mutant chinese hamster ovarian (cho) cells with a resistance to 7-10(-7) and 8-10(-7) m cycloheximide (chm) were induced at mutation rates of 1.9-5.2-10(-3) and 1.6-1.8-10(-3) respectively after treatment with n-nitrosomethylurea (nmu) at 100 mug/ml. the induced mutation rates differed by two orders of magnitude from the spontaneous rate of mutation to chm resistance. | 1975 | 1177963 |
| interaction of phospholipid vesicles with cultured mammalian cells. ii. studies of mechanism. | the mechanism of interaction of artificially generated lipid vesicles (approximately 500 a diameter) with chinese hamster v79 cells bathed in a simple balanced salt solution was investigated. the major pathways of exogenous lipid incorporation in vesicle-treated cells are vesicle-cell fusion and vesicle-cell lipid exchange. at 37 degrees c, the fusion process is dominant, while at 2 degrees c or with energy depleted cells, exchange of lipids between vesicles and cells is important. the fusion me ... | 1975 | 1176535 |
| interaction of phospholipid vesicles with cultured mammalial cells. i. characteristics of uptake. | the interaction of monolayer cultures of chinese hamster v79 cells with artificially generated, unilamellar lipid vesicles (approximately 500 a diameter) was examined. vesicles prepared from a variety of natural and synthetic radiolabeled phosphatidyl cholines (lecithins) were incubated with v79 cells bathed in a simple balanced salt solution. after incubation, the cells were analyzed for exogenous lipid incorporation. large quantities (approximately 10(8) molecules/cell/h) of lecithin became ce ... | 1975 | 240860 |
| induction of chromosome changes in chinese hamster cells by exposure to asbestos fibres. | 1975 | 1161005 | |
| mitochondrial protein synthesis in a mammalian cell-line with a temperature-sensitive leucyl-trna synthetase. | the temperature-sensitive chinese hamster ovary cell mutant tsh1, has been shown previously to contain a temperature-sensitive leucyl-trna synthetase. at the non-permissive temperature of 40 degrees c cytosolic protein synthesis is rapidly inhibited. the protein synthesis which continues at 40 degrees c appears to be mitochondrial, since: (a) whole-cell protein synthesis at the permissive temperature of 34 degrees c is not inhibied by tevenel, the sulfamoyl analogue of chloramphenicol and a spec ... | 1975 | 1204605 |
| the inactivation of chinese hamster cells by x rays: the effects of chemical modifiers on single- and double-events. | 1975 | 1197646 | |
| the inactivation of chinese hamster cells by x rays: synchronized and exponential cell populations. | 1975 | 1197645 | |
| the nature of adriamycin-induced cytotoxicity in chinese hamster cells as revealed by premature chromosome condensation. | the short- and long-term effects of adriamycin treatment on the cell cycle kinetics and chromosome structure of chinese hamster ovary cells were investigated. adriamycin treatment, either pulse or continuous, did not delay the progression of g1 cells into s phase but did prolong the duration of s and g2 phases. this effect was dose dependent, and the prolongation of g2 period was greater than that of s. the frequency of chromosomal aberrations induced by adriamycin was studied in the mitotic as ... | 1975 | 1182695 |
| the carcinogenic effect of dimethylnitrosamine on the chinese hamster (cricetulus griseus). | three groups of chinese hamsters (20 males, 20 females/group) received weekly subcutaneous injections for life of dimethylnitrosamine (dmn) at dose levels 0.20, 0.10 and 0.05 of the ld50. eighty-two to 100% of the animals developed tumors of vascular origin. the neoplasms were primarily hepatic hemangioendotheliomas and their incidence was unrelated to dose or sex. although animals in the low dose group received a total dose which was one-third that of the highest dose group, their survival time ... | 1975 | 1235055 |
| a glucosamine-requiring mutant of chinese hamster lung cells. | 1975 | 1230461 | |
| effect of carbohydrates on the growth of d-glucosamine-requiring mutant cells of chinese hamster lung cells. | 1975 | 1230456 | |
| flow microfluorometric analysis of isolated chinese hamster chromosomes. | 1975 | 1193141 | |
| sister chromatid exchanges and lack of isolabeling in chinese hamster chromosomes. | 1975 | 1193131 | |
| the dose-response relationship for ultraviolet-light-induced mutations at the hypoxanthine-guanine phosphoribosyltransferase locus in chinese hamster ovary cells. | exposure of chinese hamster ovary (cho) cells clone k1bh4 to ultraviolet (uv) light at doses up to 86 ergs/mm2 did not significantly reduce cell survival, but uv doses of 86-648 ergs/mm2 produced an exponential cell killing. observed mutation frequency ro 6-thioguannine resistance induced by uv increases approximately in proportion to increasing doses up to 260 ergs/mm2 in a range of 5-648 ergs/mm2 examined. the pooled data of mutation frequency f(x) as a function of dose x from 0-260 ergs/mm2 i ... | 1975 | 1235913 |
| non-mendelian segregation in hybrids between chinese hamster cells. | mechanisms of segregation have been examined in hybrids between chinese hamster cells, where chromosome loss in comparison to other systems is minimal. hybrid cells were grown in hat medium and subjected to back selection with bromodeoxyuridine (budr) or azaguanine (azg). in azg or budr at 30 mug/ml, segregation began with a random high frequency event that gave rise to cells capable of growth in both hat and back selection medium, unlike the precursor hybrid or original parental cell types. bud ... | 1975 | 1194375 |
| a comparative study of the effects of lucanthone (miracil d) and actinomycin d on the chinese hamster cells grown in cultures. | chinese hamster cells of an established clone line grown in monolayers were incubated for up to two hours with either lucanthone (0.3-30 mug/ml) or actinomycin d (0.06-0.10 mug/ml) and subjected to radioautographic investigations with 3h-uridine during the period of treatment. at concentration of 9 mug/ml lucanthone selectively inhibited the synthesis of nucleolar (ribosomal) rna while the extranucleolar rna synthesis proceeded at a high level. similar results were obtained with 0.08 mug/ml acti ... | 1975 | 1194365 |
| factors affecting the quantitation of dose-response curves for mutation induction in v79 chinese hamster cells after exposure to chemical and physical mutagens. | using four common mutagens, ethyl methanesulphonate (ems), methyl methanesulphonate (mms), uv, and x-irradiation, the relationship between dose of mutagen, cellular lethality and frequency of 8-azaguanine resistant colonies in v79 chinese hamster cells has been examined. several factors affecting the recovery of mutants including inter and intra-clone metabolic co-operation have been quantitated and their influence on survival response curves examined. induced mutant frequencies were assayed by ... | 1975 | 1177958 |