| the units of dna replication in the mammalian chromosomes: evidence for a large size of replication units. | the replication of chromosomal dna in human and chinese hamster cell populations has been studied by means of the dna fiber autoradiography. it was found that the rate of dna replication for one fork in human cells varies from 0.2 to 0.9 micron/min, the average being 0.6 micron/min. in the chinese hamster cells the rate dna replication is greater, varying from 0.3 to 1.2 micron/min, the average being 0.8 micron/min. there are no clusters containing a great number of replication units in human an ... | 1977 | 870295 |
| the pineal complex and its relationship to other epithalamic structures. | the pineal complex of rodents is made up of a pineal gland which developmentally always originates from the area between the habenular and posterior commissure and a pineal sac which is continuous with the choroid plexus of the third ventricle. at the light-microscopic level, this sac appears to be identical to the choroid plexus. the pineal sac abuts the deep and superficial pineal glands of the golden hamster. in the pet mouse, gerbil, kangaroo rat, and chinese hamster, the sac is contiguous w ... | 1977 | 899706 |
| 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 |
| somatic cell chromosome interconnections in trypan preparations of chinese hamster testicular cells. | | 1976 | 944637 |
| 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 |
| profiles of brain glycosidase activity in cuprizone-fed syrian hamsters and in scrapie-affected mice, rats, chinese hamsters and syrian hamsters. | | 1976 | 943426 |
| 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 |
| selective isolation of reversible cold sensitive variants from chinese hamster ovary cell cultures. | variants of the chinese hamster ovary cell line cho-ki (attcccl61)which grow almost normally at 38.5c but very poorly or not at all at 30c were obtained after treatment with mutagens and application of an indirect selection procedure. two kinds of variants were recovered. in the first of these, the cold sensitive phenotypw is expressed completely only at low cell densities. at higher cell desity, growth continues at the nonpermissive temperature, but at a reduced rate. in the second class, t ... | 1976 | 956283 |
| articular cartilage of diabetic chinese hamsters. | investigations were carried out in order to determine whether animals with spontaneous diabetes are prone to develop skeletal lesions comparable to those found in diabetic human subjects. the present report deals with the ultrastructure of the cartilage of the hip joint of diabetic chinese hamsters and nondiabetic control animals. in the diabetic animals, chondrocytes of the femoral head showed atrophy of the endoplasmic reticulum, bizarre mitodhoncria, and huge lipid inclusions, which are chang ... | 1976 | 946390 |
| 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 |
| a quantitative assay of mutation induction at the hypoxanthine-guanine phosphoribosyl transferase locus in chinese hamster ovary cells (cho/hgprt system): utilization with a variety of mutagenic agents. | the induction of mutation by a variety of mutagens has been measured utilizing the hypoxanthine-guanine phosphoribosyl transferase (hgprt) locus in chinese hamster ovary (cho) cells (cho/hgprt) system). these mutagens include physical agents such as uv light and x-rays, and chemicals such as alkylating agents, icr-191, and metallic compounds. this system can also be modified for study of the mutagenicity of promutagens such as dimethylnitrosamine (dmn) which require biotransformation for mutagen ... | 1977 | 917031 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| [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 |
| 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 |
| 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 |
| 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 ... | 1975 | 1058482 |
| [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 |
| [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 |
| 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 |
| 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 ... | 1975 | 1059144 |
| human gene locations achieved by means of human-chinese hamster (cho-k1) auxotrophic cell hybridization. | | 1976 | 1024644 |
| expression of human x-chromosomal markers in man-chinese hamster hybrids treated with isolated human chromosomes. | | 1976 | 1024646 |
| 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 |
| 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 |
| 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 ... | 1975 | 1083437 |
| sub-unit structure of soluble and mitochondrial malic enzyme: demonstration of human mitochondrial enzyme in human-mouse hybrids. | 1. malic enzyme has been examined by starch-gel electrophoresis in human cultured fibroblasts and in 60 brain samples. the polymorphism of mem has been confirmed and the electrophoretic pattern suggests that this enzyme, like mes, is a tetramer. 2. the appearance of the soluble and mitochondrial malic enzymes in mouse and chinese hamster is described, and the identity of the enzymes in man, mouse and hamster has been established from a study of interspecific somatic cell hybrids. in man and in h ... | 1975 | 1088824 |
| mutagenicity of the food additive af-2, a nitrofuran, in escherichia coli and chinese hamster cells in culture. | | 1975 | 1093019 |
| a technic for the collection of peritoneal cells from laboratory animals. | a simple method was devised for the collection of peritoneal cells from rats, chinese hamsters, and mice using a special glass pipette. cell collection was performed by lavage on the intact unanesthetized animal within 30-60 sec, and it yielded 5-20 million cells per rat and 0.3-2.5 million cells per mouse or chinese hamster. the procedure can be repeated on different occasions in the same animal without apparent adverse effects. | 1975 | 1094186 |
| requirement for cell dispersion prior to selection of induced azaguanine-resistant colonies of chinese hamster cells. | with v79 chinese hamster cell cultures treated with a mutagen, the maximum frequency of colonies resistant to 8-azaguanine (azg) was attained when the cells were dispersed after a suitable expression time before adding the selection medium. v79-4 cells were exposed to 500 mum mms, 7 mum afaa, or 10 mum mnng and allowed to multiply before being reseeded at 4 times 10-4 cells/60 mm dish and selected with 10 mu-g/ml azg. maximum frequencies of 4 times 10-5, 4 times 10-4, and 2.4 times 10-3 were obt ... | 1975 | 1093934 |
| studies of the mechanisms of radiosensitization of bacterial and mammalian cells by diamide. | diamide sensitizes bacterial and mammalian cells to radiation by at least two mechanisms. sensitization of v79-gl1 chinese hamster cells is due mainly to a reduction of a reduction of the survival-curve shoulder, is observed both in oxygen and in hypoxia,and is additive to the sensitization of hypoxic cells by some nitroimidazoles. in contrast, sensitization of the radioresistant organism, micrococcus sodonensis, which has apronounced shoulder, is entirely dose-modifying. in a rapid-mix study us ... | 1975 | 1093986 |
| the mutagenicity of saccharin. | seventeen different reports are available dealing with the mutagenic effects of saccharin. many of these are short abstracts, carrying incomplete information. mainly tested as its sodium salt, saccharin has been found to be weakly mutagenic in salmonella at very high doses, in drosophila at moderate doses, and in mice at moderate to high doses. the compound is a weak chromosome breaker in onion root tips and in chinese hamster cells. for most of these, and for other test systems as well, a numbe ... | 1975 | 1095924 |
| excision-repair of gamma-ray-damaged thymine in bacterial and and mammalian systems. | the selective excision of products of the 5,6-dihydroxy-dihydrothymine type (t') from gamma-irradiated or oso4-oxidized dna or synthetic poly[d(a-t)] was observed with crude extracts of escherichia coli and isolated nuclei from human carcinoma hela s-3 and chinese hamster ovary cells. the results with e. coli extracts allow the following conclusion: (1) the uvra-gene product is not required for t' excision. (2) radiation-induced strand breakage is not required for product excision. (3) experimen ... | 1975 | 1103854 |
| mutagenic and cytotoxic activity of benzol[a]pyrene 4,5-, 7,8-, and 9,10-oxides and the six corresponding phenols. | the benzo[a]pyrene 4,5-, 7,8-, and 9,10-oxides and the six corresponding phenols (4-, 5-, 7-, 8-, 9-, and 10-hydroxybenzo[a]pyrene) have been tested for mutagenic and cytotoxic activity in bacteria and in a mammalian cell culture system. benzo[a]pyrene 4,5-oxide (k-region) was highly mutagenic in two histidine-dependent strains (ta1537 and ta1538) of salmonella typhimurium which detect frameshift mutagens. in contrast, benzo[a]pyrene 7,8- and 9,10-oxides were less than 1% as mutagenic as the 4,5 ... | 1975 | 1103140 |
| distribution of 18+28s ribosomal genes in mammalian genomes. | in situ hybridization with 3h 18s and 28s ribosomal rna from xenopus laevis has been used to study the distribution of dna sequences coding for these rnas (the nucleolus organizing regions) in the genomes of six mammals. several patterns of distribution have been found: 1) a single major site (rat kangaroo, seba's fruit bat), 2) two major sites (indian muntjac), 3) multiple sites in centromeric heterochromatin (field vole), 4) multiple sites in heterochromatic short arms (peromyscus eremicus), 5 ... | 1975 | 1104290 |
| 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 |
| 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 |
| [differential reaction of condensed and diffuse chromatin to polyamines. i. reaction of interphase nuclei chromatin to putrescine]. | condensation of the interphase nuclei chromatin under putrescine treatment was studied in cultured human fibroblasts 46, xx: 47, xxx: 49, xxxxy, and aneuploid cells of the chinese hamster. the effect was tested separately for diffuse and condensed chromatin. putrescine treatment did not affect the percentage of cell nuclei with x-chromatin bodies in the human cell strains while significantly increasing the percentage of nuclei with coarse chromatin network and chromocenters. in cultured chinese ... | 1975 | 1145759 |
| membrane-mediated drug resistance and phenotypic reversion to normal growth behavior of chinese hamster cells. | development of resistance to actinomycin d, daunomycin, or vincristine in chinese hamster cells growing in vitro resulted in reversion to or retention of normal phenotypes in comparison to spontaneously transformed drug-sensitive parent populations. sublines resistant or cross-resistant to actinomycin d showed reduced uptake of antibiotic in proportion to degree of resistance. the cells with acquired resistance were either weakly tumorigenic or nontumorigenic when tested in the cheek pouches of ... | 1975 | 1159844 |
| quantitative comparison of techniques used to measure complement-mediated cytotoxicity of nucleated cells. | ?the cytotoxicity of nucleated cells by specific antibody and complement can be guantitated in vitro by several methods. trypan blue exclusion, 51-cr release, inhibition of uptake of 3-h-thymidine, and inhibition of colony formation are the four assays that we used to guantitatively compare the c-mediated cytotoxicity of chinese hamster lung (chl) cells. chl cells were sensitized with either guinea pig or rabbit anti-chl antisera, and exposed to guinea pig, human, or rabbit c. we found that the ... | 1975 | 1117130 |
| 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 ... | 1975 | 1064545 |
| heavy-ion irradiation of human and chinese hamster cells in vitro. | | 1975 | 1167420 |
| the interactions of benzo(a)pyrene with cell membranes: uptake into chinese hamster ovary (cho) cells and fluorescence studies with isolated membranes. | the interactions of benzo(a)pyrene (b(a)p) with the cell surface membrane were studied by measuring b(a)p uptake into intact mammalian cells and by determining b(a)p fluorescence in the presence of isolated cell surface membranes. it was found that 0.19 mu-g b(a)p were taken up by 10-6 chinese hamster ovary (cho) cells after 30 min exposure to a solution containing 0.59 mu-g/ml. culture conditions were found to markedly alter b(a)p uptake. low cell culture densities resulted in a four-fold incre ... | 1975 | 1170030 |
| metabolism of the polyadenylate sequence of nuclear rna and messenger rna in mammalian cells. | the poly(a) sequences at the 3' end of mrna and nuclear rna molecules of mouse sarcoma and chinese hamster cells are subject to an elongation process distinct from de novo synthesis. this process continues in cells treated with a high level of actinomycin d to block transcription. this results in the labeling of the steady-state poly(a) population in the cytoplasm and of unusually long poly(a) segments in the nucleus. in cells incubated with 3h-adenosine in the absence of drug treatment, cytopla ... | 1975 | 1170955 |
| high-speed quantitative karyotyping by flow microfluorometry. | we describe a new flow-system technique for high-speed quantitative karyotyping. metaphase chromosomes are isolated from cells, stained with a dna-specific fluorochrome, and individually measured for stain content at rates up to 10(5)/min in a flow microfluorometer. the resulting distribution contains quantitative information about the relative frequency of occurrence and the chromosomal dna content of the measured chromosomes. such analyses of chinese hamster chromosomes are in good agreement ... | 1975 | 1170959 |
| relationship between experimental results in mammals and man. i. cytogenetic analysis of bone marrow injury induced by a single dose of cyclophosphamide. | the extrapolation of experimental results to man was studied by cytogenetic bone marrow analysis and micronucleus test in mice, rats and chinese hamsters. furthermore, the frequency of chromosomal aberrations was compared with the frequencies of polychromatic erythrocytes containing micronuclei. cyclophosphamide (cy) was given intraperitoneally at the doses of 5, 10, 20, 40 and 80 mg/kg b.w. to icr mice and wistar rats and at the doses of 10, 20, 40, 80, 120 and 160 mg/kg b.w. to chinese hamster ... | 1975 | 1143298 |
| membrane effects of cytochalasin b. competitive inhibition of facilitated diffusion processes in rat hepatoma cells and other cell lines and effect on formation of functional transport sites. | cytochalasin b competitively inhibits the transport of 2-deoxy-d-glucose and thymidine in a number of different cell lines (novikoff rat hepatoma cells, mouse l, s180 and ki-msv-transformed balb/3t3 cells, and human hela cells). the apparent km values for the transport of these substrates as well as the apparent ki values for the inhibition by cytochalasin b are very similar for the various cell lines, and the effect is readily and completely reversed by removal of the chemical. thymidine trans ... | 1975 | 1165581 |
| [some patterns of rna synthesis in the proliferation induction process in a stationary culture of chinese hamster cells]. | an increase in the incorporation of eh-uridine into rna and in the cell membrane permeability for 3h-uridine in stationary culture cells after medium replenishment were found to be parallel. increase in the rna synthesis occurs practically in all cells stimulated to proliferate and is not accompanied by swelling nucleii, as demonstrated by measuring the projected areas of nucle on fixed cells. the rise in rna synthesis as a response to proliferative stimulus is pronounced at every cell density b ... | 1975 | 1135947 |
| differential potentiation by nystatin of the effect of antibiotics on yeast and mammalian cells. | the effect of the polyene antibiotic nystatin, used in combination with several other antibiotics, on the membranes of candida albicans sc#8169 (yeast) cells and of chinese hamster ovary and 3t3 (mammalian) cells was investigated. it was concluded from determinations of the viability of the yeast cells and from measurements of deoxyribonucleic acid synthesis by the mammalian cells that nystatin acts synergistically with several antibiotics on yeast cells, but not on cho and 3t3 cells. this selec ... | 1975 | 1171651 |
| mutation induction in chinese hamster v79 cells by two vinyl chloride metabolites, chloroethylene oxide and 2-chloroacetaldehyde. | chloroethylene oxide and 2-chloroacetaldehyde, two possibly carcinogenic metabolities of vinyl chloride in mammals, caused a dose-dependent induction of 8-azaguanine- and ouabain-resistant mutants in chinese hamster v79 cells in vitro. up to one-hundred-fold higher concentrations of 2-chloroethanol or monochloroacetic acid, a urinary vinyl chloride metabolite in rats and man, were inactive. | 1975 | 1176210 |
| biochemical and immunological studies of purified mouse beta-galactosidase. | beta-galactosidase (ec 3.2.1.23) has been purified from the livers of c57bl/6j mice. the enzyme migrated as a single band of protein on polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. the molecular weight of the denatured and reduced enzyme was 63,000. the native form of beta-galactosidase appeared to be a tetramer of 240,000 at ph 5.0, which was reversibly dissociated at alkaline ph to a dimer with apparent molecular weight of 113,000. multiple charge isomers of be ... | 1975 | 1176446 |
| cholera toxin effects on cell growth accompanied by selective alterations in metabolite uptake and modification of cell surface proteins. | exposure of chinese hamster ovary cells to cholera toxin at or below mug levels causes a marked morphological changes and increased adhesion and orientation of the cells. such changes are paralleled by alterations in surface proteins as indicated by the cholera toxin-mediated modifications detectable by lactoperoxidase-catalyzed radioiodination of outer proteins. mild tryptic treatment of cells prelabeled with [3h]glucosamine revealed a different kinetics of release of external glycoproteins in ... | 1975 | 1182696 |
| adenine phosphoribosyltransferase and hypoxanthine-guanine phosphoribosyltransferase immunoprecipitation reactions in human-mouse and human-hamster cell hybrids. | male new zealand white rabbits were immunized with human adenine phosphoribosyltransferase (aprt) and hypoxanthine-guanine phosphoribosyltransferase (hgprt), which were purified about 2000-fold and 800-fold, respectively, from erythrocytes by deae-cellulose chromatography, ammonium sulfate precipitation and preparative polyacrylamide gel electrophoresis. specific immunoprecipitations of aprt and hgprt were achieved with the antisera that were obtained and by using polyethylene glycol as a substi ... | 1975 | 1184004 |
| cell surface structure of rodent sperm heads. | replicas of critical point dried rodent sperm were examined by transmission electron microscopy. the surface of rat sperm heads appeared to be coated with regularly spaced 90a lamellar material. the plasma membrane overlying the acrosomal region of guinea pig spermatozoa displayed a regular scalloped array of lamellar structures. in replicas, the surface of chinese hamster spermatozoa appeared coated by an array of small tubles and vesicles in the region overlaying the acrosome. it was possible ... | 1975 | 1110344 |
| mutagenesis and genetic analysis with chinese hamster auxotrophic cell markers. | chinese hamster ovary cells were treated with various physical and chemical mutagens and subject to the bromodeoxyuridine plus visible light procedure for isolation of auxotrophic mutants. more than 200 auxotrophs have been isolated which require exogenous supplement of various nutrilites for growth, such as glycine, adenine, thymidine, inositol, etc. fifty-five of these have been characterized by complementation tests and were shown to constitute 15 different loci. all these auxotrophs are high ... | 1975 | 1171046 |
| laboratory studies of a lymphocytic choriomeningitis virus outbreak in man and laboratory animals. | investigation of an outbreak of prolonged febrile illness in medical center personnel at the university of rochester school of medicine and dentistry revealed lymphocytic choriomeningitis (lcm) virus to be the causative agent. syrian or golden hamsters (mesocricetus auratus) were found to be the only animals involved in maintaining the virus and were the source of human infections. isolations of lcm virus were made from autopsy specimens of 13 of 46 (28%) golden hamsters. virus isolations were m ... | 1975 | 1163529 |
| responses to arginine of the perfused pancreas of the genetically diabetic chinese hamster. | nonketotic, genetically diabetic cinese hamsters show subnormal pancreatic insulin release and impaired suppression of glucagon in response to glucose. to study the pancreatic effects of other agents, dynamic insulin and glucagon release was measured from the in vitro perfused pancreases of normal and diabetic chinese hamsters in response to various combinations of arginine (20mm), glucose (100 or 150 mg. per 100 ml.), and theophylline (10 mm). theophylline alone caused identical insulin and glu ... | 1975 | 1116650 |
| localization of human gene loci using spontaneous chromosome rearrangements in human-chinese hamster somatic cell hybrids. | analysis of human-chinese hamster somatic cell hybrids with spontaneously derived chromosome structural changes has provided data for the regional and subregional localization of gene loci which have previously been assigned to human chromosomes 2, 12, and x. correlation of the expression of human gene loci with the human chromosome complements present in somatic cell hybrids indicates that the cytoplasmic malate dehydrogenase (mdh1) locus is in the 2p23yields2pter region, and red cell acid phos ... | 1975 | 1172370 |
| in vivo cytogenetic investigations in bone marrow cells of rats, chinese hamsters and mice treated with 6-mercaptopurine. | the chromosome-damaging effect of 6-mercaptopurine (6-mp) was investigated in bone marrow cells of rats, chinese hamsters, and mice after single intraperitoneal injections of doses from 3.125 to 250 mg/kg, and after multiple applications of 10, 25, 50, and 125 mg/kg. the optimal time of investigation after single administration in these studies was 48 hrs after treatment for all 3 species. a nearly linear dose-response relationship with a low quadratic component was observed. the "critical dose" ... | 1975 | 1173752 |
| mammalian cell transformation and cell-mediated mutagenesis by carcinogenic polycyclic hydrocarbons. | the introduction of a polycyclic hydrocarbon such as benzo(alpha)pyrene (bp) into normal golden hamster embryo cell cultures results, in addition to cytotoxicity, in malignant cell transformation. studies on the effect of different doses of bp on the normal cells showed that the frequency of transformed colonies was directly related to the dose of the carcinogen. analysis of this dose-response curve suggests a one-event ("one-hit") response for transformation by this carcinogen. the one-event re ... | 1975 | 1186764 |
| mapping the xga red blood cell antigen in human-chinese hamster cell hybrids. the xg locus is possibly located on the short arm of the x chromosome. | | 1975 | 1192805 |
| alpha-galactosidase in man-chinese hamster somatic cell hybrids. | | 1975 | 1192822 |
| synteny relationship between the human loci for hexosaminidase-a, mannose phosphate isomerase, and pyruvate kinase-3 studied in man-chinese hamster somatic cell hybrids. | | 1975 | 1192838 |
| cycloheximide resistance in chinese hamster cells. iii. characterization of cell-free protein synthesis by polysomes. | two clones were selected for mass cultivation from 18 phenotypically stable chm-resistant cho clones. the polysomes isolated from these two clones were compared with cho wildtype polysomes and rat liver polysomes in a cell-free protein synthesis system for their ability to incorporate amino acids. chm had an inhibitory effect on the protein synthesis activity of cho wildtype and rat liver polysomes, but had no effect on the polysomes obtained from either of the mutant cho clones. | 1975 | 1196299 |
| electrophoretic pattern of hypoxanthine phosphoribosyltransferase produced in chinese hamster cells following incorporation of human chromosomes. | | 1975 | 1192840 |
| selective depletion of chromosomes in a stable mouse-chinese hamster hybrid cell line using antisera directed against species-specific cell surface antigens. | a chromosomally-stable mouse-chinese hamster hybrid cell line was subjected to five rounds of selection with cytotoxic antisera raised in rabbits against either the parental mouse 3t3 cells or the parental chinese hamster wg-1 cells. routine karyological analysis of clones isolated at each stage of serum selection revealed that treatment with either serum resulted in a limited loss of chromosomes (compared to the untreated hybrid cell cultured in parallel) and that the pattern of chromosome loss ... | 1975 | 1202037 |
| preparation of peritoneal cell metaphases of rats, mice and chinese hamsters after mitogenic stimulation with magnesium sulfate and/or aluminum hydroxide. | a new cytogenetic system in vivo is presented using peritoneal cells, collected from unanesthetized rats, mice and chinese hamsters, 48 h after an i.p. injection of a mitogen. the test is useful for periodic monitoring of chromosome aberration rates in the investigation of such problems as aging and chronic effects of mutagens and carcinogens. among the 2 mitogens tested, aluminum hydroxyde was more efficient than magnesium sulfate in all 3 species. the rat is considered to be the most suitable ... | 1975 | 1202331 |
| evidence for synteny between the human loci for galactose-1-phosphate uridyl transferase and aconitase in man-chinese hamster somatic cell hybrids. | | 1975 | 1192837 |
| turnover of plasma membrane polypeptides in nonproliferating cultures of chinese hamster ovary cells and human skin fibroblasts. | | 1975 | 1190794 |
| synteny relationship between the human loci for hexosaminidase-a, mannose phosphate isomerase, and pyruvate kinase-3 studied in man-chinese hamster somatic cell hybrids. | | 1975 | 1203498 |
| electrophoretic pattern of hypoxanthine phosphoribosyltransferase produced in chinese hamster cells following incorporation of human chromosomes. | | 1975 | 1203500 |
| x-ray-induced inhibition of dna synthesis in chinese hamster ovary, human hela, and mouse l cells. | | 1975 | 1197664 |
| mapping the xga red blood cell antigen in human-chinese hamster cell hybrids. the xg locus is possibly located on the short arm of the x chromosome. | | 1975 | 1203469 |
| [characteristics of somatic cell hybrids (mouse x chinese hamster) with different ratios of parental species chromosome sets. iv. electrophoretic analysis of several enzymes of the dehydrogenase class]. | electrophoretic mobilities in polyacrylamide gel of five dehydrogenases: nadp-dependent malate dehydrogenase (nadp-mdh), 6-phosphogluconate dehydrogenase (6pgd), alcohol dehydrogenase (adh), glucose-6-phosphate dehydrogenase (g6pd) and glutamate dehydrogenase (gdh) were investigated in a series of mouse x chinese hamster somatic cell hybrids. seven hybrid lines with different ratio of chromosome sets of hamster and mouse: 1:1, 2:1, 3:1 and 1:2 respectively were studied. nadp-mdh and 6pgd of both ... | 1975 | 1232030 |
| evidence for synteny between the human loci for galactose-1-phosphate uridyl transferase and aconitase in man-chinese hamster somatic cell hybrids. | | 1975 | 1203497 |
| incorporation of isolated chromosomes and induction of hypoxanthine phosphoribosyltransferase in chinese hamster cells. | evidence is presented for the uptake of radioactive-labeled isolated chinese hamster chromosomes following incubation with chinese hamster cells. metaphases were found which contained radioactive labeled chromosomes in a very low frequency, and in some of the labeled chromosomes only one chromatid was labeled. incubation of hypoxanthine phosphoribosyltransferas (hprt)-deficient chinese hamster cells with chromosomes isolated from hprt+ chinese hamster or human cells resulted in the appearance of ... | 1975 | 1235904 |
| genetics of somatic cell surface antigens. iii. further analysis of the al marker. | the al antigen present on the surface of various human somatic cells, and on those hybrids of human and chinese hamster ovary cells which have retained human chromosome number 11, has been resolved into at least two separate antigenic activities, a1 and a2. specific antisera active against each antigen separately have been prepared. by treatment of the original al+ hybrid with mutagenic agents and selection in particular antisera, stable clones are preparable whose phenotypic behavior correspond ... | 1975 | 1235908 |
| synteny between the pro+ marker and human glutamate oxaloacetate transaminase. | chinese hamster ovary cells with a specific auxotrophy for proline were fused with human cells from a variety of sources and the resulting hybrids analyzed for human genetic markers. of 63 hybrid clones examined, 27 possessed both proline and cytoplasmic glutamate oxaloacetate transaminase markers; 36 had neither; and no clones were found possessing one and not the other. these results constitute evidence that the proline and glutamate oxalocetate transaminase markers are syntenic. evidence for ... | 1975 | 1235910 |
| chinese hamster x mouse hybrid cells segregating mouse chromosomes and isozymes. | hybrid cells are readily formed by fusing clonal chinese hamster cells to fresh, noncultured, adult mouse spleen cells followed by isolation in selective medium. the vast majority of such hybrids retain chinese hamster chromosomes and isozymes while segregating mouse chromosomes and isozymes. the growth, plating efficiency, ease of karyology, and rapid segregation of mouse markers allows linkage tests in primary clones. analysis of 13 isozymes showed 12 to be asyntenic and on epair (pgd-pgm2) to ... | 1975 | 1235911 |
| gene linkage analysis in the mouse by somatic cell hybridization: assignment of adenine phosphoribosyltransferase to chromosome 8 and alpha-galactosidase to the x chromosome. | somatic cell hybridization techniques were applied to gene linkage analysis in the laboratory mouse. cells of an established line of chinese hamster lung fibroblasts were fused with mouse embryo fibroblasts and with mouse peritoneal macrophages obtained from different inbred strains. from 3 hybridization experiments, 123 primary and secondary clones were isolated in hat selective medium and 24 were back-selected in 8-azaguanine. hybrid clones were characterized for the expression of 16 murine is ... | 1975 | 1235912 |
| [characteristics of structural chromosome aberrations induced by type 1 adenovirus in human and chinese hamster cells in vitro]. | adenovirus multiplies in both studied cultures. in the chinese hamster cells infection is of slowed down, cyclic character. in this case a short subcultivation of cells infected with the virus and the study of the damage distribution in groups of chromosomes are possible. no selectivity was found with respect to the damage of certain group chromosomes. | 1975 | 1221572 |
| [presence of biologically active glutamyl peptide in rabbit bone marrow]. | the presence of chromatographically pure and biologically active glutamylpeptide in the rabbit bone marrow was shown and methods of its isolation were given. the substances had an unusual circular dichroism contrary to that of the natural proteins. in a concentration of 10(-5) m the isolated peptide decreased the survival of the chinese hamster culture cells to 30%. it was analogous to the peptide isolated formerly from plants by a number of physical and chemical characteristics; the latter poss ... | 1975 | 1225406 |
| [dependence of immune cytolysis of cells infected with western equine encephalomyelitis virus upon the cell cycle stages]. | in the first few hours after inoculation of chinese hamster cells with western equine encephalomyelitis virus the mitotic activity of the cells did not change significantly but mitoses stopped mainly in the stage of metaphase and had all signs of pathological mitoses. treatment of the cells for 1 hour with the homologous antiviral immune serum and complement resulted in destruction and death of practically all cells except those in the state of mitosis. in the latter specific fluorescence of vir ... | 1975 | 1241178 |
| [characteristics of somatic cell hybrids (mouse x chinese hamster) with a different ratio of chromosome sets from the parent species. ii. thymidine kinase activity]. | the activity of thymidine kinase (tk) was studied in series of somatic cell hybrids between the mouse cell line 3t3-4e (tk-) and chinese hamster cells m-15-1 (hgprt-). four groups of hybrid lines with different ratio of parental chromosome sets have been investigated: 1) three lines containing one hamster and one mouse chromosome set (1 hs+1 ms); 2) one line with 2 hs+1 ms; 3) one line containing 3 hs+1 ms and 4) one line containing 1 hs+2 ms. mixtures of extracts from the parental cells were sh ... | 1975 | 1241540 |
| [characteristics of somatic cell hybrids (mouse x chinese hamster) with ratios of chromosome sets different from the parent species. iv. an electrophoretic analysis of several enzymes of the dehydrogenase class]. | electrophoretic mobilities in polyacrylamide gel of five dehydrogenases: nadp-dependent malate dehydrogenase (nadp-mdh), 6-phosphogluconate dehydrogenase (6pgd), alcohol dehydrogenase (adh), glucose-6-phosphate dehydrogenase (g6pd) and glutamate dehydrogenase (gdh) were investigated in a series of mouse x chinese hamster somatic cell hybrids. seven hybrid lines with different ratio of chromosome sets of hamster and mouse: 1 : 1, 2 : 1, 3 : 1 and 1 : 2 respectively were studied. nadp-mdh and 6pgd ... | 1975 | 1241545 |
| acrylonitrile biotransformation in rats, mice, and chinese hamsters as influenced by the route of administration and by phenobarbital, skf 525-a, cysteine, dimercaprol, or thiosulfate. | female wistar rats, conventional albino mice, and chinese hamsters were given a single dose of acrylonitrile, 0.5 or 0.75 mm/kg body weight. the elimination in the urine of thiocyanate, which is the main metabolite of acrylonitrile, indicated a decreasing proportion of biotransformation after oral (over 20%), intraperitoneal, or subcutaneous (2 to 5%), and intravenous (1%) administration in rats. oral administration of acrylonitrile in hamsters and mice was also followed by higher biotransformat ... | 1975 | 1242300 |
| 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 |