PMID(sorted ascending)
proceedings: chromosome aberrations in metaphase ii oocytes of chinese hamsters (cricetulus griseus). 19751186737
proceedings: chromosome analysis in spermatocytes of mice and chinese hamsters. 19751186750
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 ...19751186764
turnover of plasma membrane polypeptides in nonproliferating cultures of chinese hamster ovary cells and human skin fibroblasts. 19751190794
cho cell repair of single-strand and double-strand dna breaks induced by gamma- and alpha-radiations.neutral and alkaline sucrose gradient sedimentation analysis was used to measure double- and single-strand breaks in the dna of chinese hamster ovary (cho) cells exposed to either gamma- or alpha-radiation. after irradiation, cells were incubated for 15-180 min to test the ability of the cell to rejoin the dna breaks. essentially complete rejoining was observed for single-strand breaks induced by gamma- or alpha-doses below 20 krad and for double-strand breaks induced by gamma doses below 60 kra ...19751191188
damage-repair studies of the dna from x-irradiated chinese hamster cells.sedimentation studies of the dna-containing material released from chinese hamster cells lysed on top of an alkaline sucrose gradient have shown these principal points: (1) after short lysis periods (e.g. approximately 60 min, approximately 25 degrees c), the dna label from unirradiated cells sediments as a two-peaked pattern. the relative positions of these peaks are strongly dependent on centrifugal force. (2) with increasing lysis time, dna lost from one peak (the "complex", the peak containi ...19751191191
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. 19751192805
alpha-galactosidase in man-chinese hamster somatic cell hybrids. 19751192822
evidence for synteny between the human loci for galactose-1-phosphate uridyl transferase and aconitase in man-chinese hamster somatic cell hybrids. 19751192837
synteny relationship between the human loci for hexosaminidase-a, mannose phosphate isomerase, and pyruvate kinase-3 studied in man-chinese hamster somatic cell hybrids. 19751192838
electrophoretic pattern of hypoxanthine phosphoribosyltransferase produced in chinese hamster cells following incorporation of human chromosomes. 19751192840
sister chromatid exchanges and lack of isolabeling in chinese hamster chromosomes. 19751193131
flow microfluorometric analysis of isolated chinese hamster chromosomes. 19751193141
cell cycle-dependent surface changes in chinese hamster cells grown in suspension culture. 19751193160
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 ...19751194364
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 ...19751194365
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 ...19751194375
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.19751196299
the inactivation of chinese hamster cells by x rays: synchronized and exponential cell populations. 19751197645
the inactivation of chinese hamster cells by x rays: the effects of chemical modifiers on single- and double-events. 19751197646
effect of heat and radiation on synchronous chinese hamster cells: killing and repair. 19751197661
x-ray-induced inhibition of dna synthesis in chinese hamster ovary, human hela, and mouse l cells. 19751197664
folate-dependent enzymes in cultured chinese hamster ovary cells: induction of 5-methyltetrahydrofolate homocysteine cobalamin methyltransferase by folate and methionine. 19751200638
effect of volatile anaesthetics on cell survival as measured by colony forming ability.chinese hamster fibroblast cells in stirred suspension cultures were exposed to volatile anaesthetic agents for 3 hr or for 24 hr. cell viability was measured as colony forming ability and was found to be reduced, in a dose related manner, by halothane, chloroform, methoxyflurane, trichloroetheylene and diethyl ether.19751201160
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 ...19751202037
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 ...19751202331
[differential reaction of condensed and diffuse chromatin to polyamines. ii. effect of putrescine on the chromatin of mitotic chromosomes].the response of euchromatin and heterochromatin to putrescine was studied using chinese hamster mitotic chromosomes with heterochromatic segments delayed in condensation due to budr treatment. these heterochromatic segments did not react to the condensing effect of putrescine looking during metaphase still more elongated. additional decondensed segments occurred in chromosomes. this is interpreted as the condensing effect of putrescine on euchromatic segments which accelerates transition of the ...19751202681
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- ...19751203255
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. 19751203469
evidence for synteny between the human loci for galactose-1-phosphate uridyl transferase and aconitase in man-chinese hamster somatic cell hybrids. 19751203497
synteny relationship between the human loci for hexosaminidase-a, mannose phosphate isomerase, and pyruvate kinase-3 studied in man-chinese hamster somatic cell hybrids. 19751203498
electrophoretic pattern of hypoxanthine phosphoribosyltransferase produced in chinese hamster cells following incorporation of human chromosomes. 19751203500
drug resistance and membrane alteration in mutants of mammalian cells.independent colchicine-resistant (chr) mutants of chinese hamster ovary cells displaying reduced permeability to colchicine have been isolated. a distinguishing feature of these membrane-altered mutants is their pleiotropic cross-resistance to a variety of unrelated compounds. genetic characterization of the chr lines indicate that colchicine resistance and cross-resistance to other drugs are of a dominant nature in somatic cell hybrids. revertants of chr have been isolated which display decreas ...19751203765
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 ...19751204605
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 ...19751207709
variations in sensitivity of synchronized chinese hamster cells to oxic and anoxic x-ray exposures.v-79 chinese hamster cells in monolayer cultures on glass surfaces were synchronized by treatment with hydroxyurea and exposed at different times thereafter to x-rays in the air or in oxygen-free argon. survival determinations indicated that the oxygen enhancement ratio oer as expressed by the ratio of the respective d0 values varied over a narrow range in the different phases of the cell cycle. these changes resulted from cyclic alterations in both aerobic and anaerobic d0 values, and perhaps i ...19751214926
proceedings: interaction of ionizing radiation with a platinum complex in chinese hamster cells. 19751220777
proceedings: different radiosensitivity of chinese hamster fibroblasts for chromatid breaks in g2/prophase. dependence on let. 19751220789
[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.19751221572
[effect of temperature on the occurrence and repair of radiaiton-induced damage to v. faba and chinese hamster cells].keeping of irradiated cells at the temperature differing from the optimal one affects differently the stages of the cellular cycle and survival rate revealing the protection in g2 at 4 degrees c and increasing the number of cells with aberrations at the expense of interchromosome chromide translocations. caffein decreased the survival rate of cells kept in suspension at 4 degrees c.20141221576
proceedings: cytogenetic analysis of 3-chinuclidylbenzilate, 3-chinuclidinol and benactyzine in bone marrow of chinese hamster. 19751221784
experimental prevention of diabetes in prediabetics: studies of chinese hamsters. 19751222533
[hereditary infertility in male white chinese hamsters (cricetulus griseus milne edwards 1867)].in the chinese hamster (cricetulus griseus) a white mutant (ws) with a dark dorsal stripe was observed. while the white females reproduced normally, the white males were always found to be infertile. the testicular weight of the white chinese hamster was approximately a quarter of that of the normal grey animals. in the seminiferous tubules of sexually mature white animals, spermatogenic cells were practically always absent. the tubules were lined with sertoli cells and contained foamy cytoplasm ...19751224832
[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 ...19751225406
detection of possible heteroduplexes in somatic chinese hamster cells dna by molecular autoradiography. 19751227397
[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 ...19751227981
effect of carbohydrates on the growth of d-glucosamine-requiring mutant cells of chinese hamster lung cells. 19751230456
a glucosamine-requiring mutant of chinese hamster lung cells. 19751230461
["ultra-fast" repair of single-stranded breaks in dna in gamma-irradiated chinese hamster cells]. 20051231090
temperature-sensitive mutants of a chinese hamster cell line. i. selection of clones with defective macromolecular biosynthesis.temperature-sensitive clones have been selected from a mutagenized culture of chinese hamster lung cells by a procedure involving bromodeoxyuridine (brdu) incorporation and irradiation with black light. the selection procedure used in these studies was adapted from methods developed by others to yield mutants that cease dna replication within a short time after they are transferred to nonpermissive temperature. after mutagenesis with ethyl methanosulfonate ten clones survived the selection proce ...19751232024
[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 ...19751232030
diabetogenic effects of n-nitrosomethylurea with special regard to species variations.the effect of n-nitrosomethylurea on the blood-glucose and the pancreatic islet light microscopic picture was studied in the chinese hamsters, golden hamsters, guinea pigs, mice, rats and sand rats. the chinese hamsters were most susceptible. only in this species did a dose of 50 mg/kg body weight cause blood-glucose elevations and pancreatic islet damage. at a dose of 100 mg/kg body weight of n-nitrosomethylurea, blood-glucose elevations were recorded in the golden hamster together with damage ...19751233304
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 ...19751235055
stable alterations at the cell membrane of chinese hamster ovary cells resistant to the cytotoxicity of phytohemagglutinin.chinese hamster ovary (cho) cells selected for resistance to the cytotoxicity of phytohemagglutin (pha) have been found to exhibit stable alterations at their plasma membranes. the pha-resistant (phar) cells bind markedly less 125i-pha than do sensitive cho cells and also exhibit an increased sensitivity to the cytotoxicity of concanavalin a, a lectin of different receptor specificity. mutagenesis with ethylmethanesulfonate increases the proportion of phar cells 20- to 100-fold. pha-resistant ce ...19751235899
biochemical genetics of chinese hamster cell mutants with deviant purine metabolism: biochemical analysis of eight mutants.purine biosynthesis was studied in 8 mutants of chinese hamster cells which require purines for growth and in wild-type cells which do not show this nutritional requirement. of these, 6 mutants, ade-b, ade-d, ade-e, ade-f, gat-, and at-, were shown to accumulate metabolic intermediates not accumulated by wild-type cells. these intermediates were shown to be compounds unique to the adenylic acid biosynthetic pathway by the following criteria: (a) their radioisotopic labeling properties, (b) their ...19751235902
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 ...19751235904
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 ...19751235908
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 ...19751235910
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 ...19751235911
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 ...19751235912
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 ...19751235913
isolation of cold-sensitive chinese hamster cells.six cold-sensitive variants have been isolated from chinese hamster ovary cells by the budr-visible light selection technique. the properties of one of these lines have been studied in detail. this line stops dividing immediately after a shift from 39 degrees c to 33 degrees c though its doubling time at 39 degrees c is only slightly longer than that of wild-type cells. the rates of dna and protein synthesis are severely reduced at 33 degrees c, but the rate of rna synthesis is not significantly ...19751237784
proceedings: comparative studies on spermatogonia of mice and chinese hamsters after x-ray treatment. 19751237786
[role of atp in dna repair of gamma-irradiated chinese hamster cells]. 20131237917
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.19751238161
investigations into the mechanism of action of anti-tumour platinum compounds: time- and dose-dependent changes in the alkaline sucrose gradient sedimentation profiles of dna from hamster cells treated with cis-platinum (ii) diamminedichloride.under the conditions of low speed centrifugation used in this study, the proportion of radioactively labelled dna from chinese hamster v79-379a cells sedimenting to the 700s region of an alkaline sucrose gradient was increased in a dose-dependent manner by prior treatment of the cells for 2 h with cis-platinum (ii) diamminedichloride [cis-pt(ii)]. this increase was at the expense of material sedimenting in the 400-650s region. this profile was not modified by a 2-h post-treatment incubation prio ...19751238177
regional mapping of the human no. 1 and x chromosome in interspecific cell hybrids using an x/1 translocation.fibroblasts from a carrier of an x/1 translocation, 46,xy,t(x;1)(q28;q31), were fused with chinese hamster cells. the resulting hybrids were analyzed for human no. 1 and x-chromosome markers. the data indicate that the loci for pgm1, pgd, pph, and guk1 are situated either in the long arm proximal to a break point in band 1q31 or in the short arm. the loci for pep-c, fh, and guk1 are located distal to the break point. hprt and g6pd are probably situated distal to a break point in band q28 of the ...19751238234
a comparison of the 8-azaguanine and ouabain-resistance systems for the selection of induced mutant chinese hamster cells.the forward mutation selection system based on resistance to 8-azaguanine has been widely used with cells cultured from a diversity of species and with a variety of mutagens. ouabain resistance is an alternative selective system. both systems show a substantial influence of expression time on the number of resistant variants observed after addition of the selective agent such that the frequency reaches a maximum which is dose dependent, and then declines rapidly. metabolic cooperation has been p ...19751240591
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 ...19751240592
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 ...19751240593
[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 ...19751241178
[a further study of the mutation process in chinese hamster cells in vitro].spontaneous mutagenesis and mutagenesis induced by chemical mutagens in culture chinese hamster cells were investigated. appearance of mutations controlling the resistance to 6-mercaptopurine (6m) and reverse mutations to sensitivity was studied. the rate of spontaneous mutations of 6m resistance in cells studied was found to be sufficiently stable: it was independent on the repeated freezing of these cells and the duration of their cultivation. 5-bromodeoxyuridine (budr) has been shown to induc ...19751241539
[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 ...19751241540
[dna replication and the development of spontaneous mutations in the somatic cells of mammals. i. the relationship between the outcome of gene mutations and the duration of cell life].the reduction of serum concentration in culture medium to 0,1% was proposed as a method of slowing division and dna replication in chinese hamster cells in vitro. under these conditions the rate of dna replication was reduced by more than one order of magnitude, while cell viability remained high enough (about 10%) for a long period up to 30 days. the spontaneous mutation rate to 6-mercaptopurine resistance, as calculated per day in cells with reduced dna replication rate, was comparable to that ...19751241543
[the effect of cysteamine on x-ray induction of mutations resulting in resistance to 8-azaguanine in chinese hamster cells in vitro].the survival of chinese hamster cell was increased after the administration of cisteamine (at doses of 1,25; 2,5 and 5,0 mm/ml) in the culture for 15--20 min. before x-irradiation (600r). in the same experiment the protector decreased the rate of induced ag-resistance gene mutations.19751241544
[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 ...19751241545
[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 ...19751241546
[development of 0-methylhydroxylamine induced mutations causing resistance to 8-azaguanine in chinese hamster cells].the dependence of the yield of mutations of the resistance to 8-azaguanine induced with 0-methylhydroxylamine on the number of cell generations that have passed by the time of the creation of selective conditions and the existence of a phenotypic lag period is established. the highest rate of mutations is found after 8-azaguanine treatment in two generations. as the number of generations increased, the number of detectable mutations decreased. a dependence is observed between the induced mutatio ...19751241683
[the effect of 0-methylhydroxylamine on the chromosomes of chinese hamster cells].0-methylhydroxylamine increases the frequency of all kinds of aberrations in chinese hamster cells, except chromatid exchange. the percentage of aberrant metaphases and the average number of breakages per cell increases by 5,5-6 times as compared with the control. omha proves to be very effective inducer of chromosome aberrations. since omha induces, except gene mutations, also chromosome aberrations, there are reasons to suppose that its effect is connected not only with transitions, but also w ...19751241684
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 ...19751242300
method for testing mutagenic effects of chemicals on spermatogonia of the chinese hamster: results obtained with cyclophosphamide, saccharin, and cyclamate.the action of different cyclophosphamide doses on spermatogonia of the chinese hamster was examined. two oral treatments at an interval of 24 h were carried out and spermatogonia were prepared for examination 24 or 48 h after the second dose. accordingly the effects of 5 oral cyclophosphamide doses given on five consecutive days were tested on spermatogonia and preparations were made 24 or 72 h after the last treatment. the results so obtained form the basis of reference for findings following o ...19751243659
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.19761244326
phosphorylation of ribosome-associated proteins during the mammalian cell cycle. unique phosphorylation of a specific protein during mitosis.chinese hamster ovary cells in monolayer culture were incubated with [32p] phosphate. ribosome-associated proteins, including both structural proteins and those tightly bound to washed, centrifuged ribosomes, were isolated and separated by electrophoresis on sodium dodecyl sulfate-polyacrylamide gels. the electrophoretic pattern showed five major regions or peaks of 32p radioactivity which represented phosphorylated ribosome-associated proteins with molecular weights of 17 500, 23 000, 30 000, 3 ...19761244853
the response of chinese hamster ovary cells to fast neutron radiotherapy beams. i. relative biological effectiveness and oxygen enhancement ratio. 19761246571
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 ...19761250244
the cytogenetic effect of an x-ray contrast medium in chinese hamster cell cultures.chinese hamster cell cultures were treated with different concentrations of joduron, a water-soluble iodized x-ray contrast medium. the cytogenetic effect was analysed for a treatment period of 2 or 16 h. jorudron primarily acts on the mitotic apparatus of the cell. the type of damage ranges from different forms of initial "c-mitosis" to unpolarized stathmokinesis. additionally, structural chromosome damage, mainly of the chromatid type, was observed, especially after a joduron treatment for 2 h ...19761250248
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.19761250414
increased cell killing by metronidazole and nitrofurazone of hypoxic compared to aerobic mammalian cells.nitromidazole and nitrofuran derivatives comprise a large family of compounds, some of which have been shown to be hypoxic cell specific radiosensitizers in vivo and in vitro. the effects of metronidazole (2-methyl-5-nitroimidazole-1-ethanol) and nitrofurazone (5-nitro-2-furaldehyde semicarbazone) were studied on cell viability in vitro in the presence of air or nitrogen in the absence of radiation. exponential-phase chinese hamster ovary cells were placed in suspension culture in complete mediu ...19761253180
inhibition by caffeine of post-replication repair in chinese hamster cells treated with cis platinum (ii) diamminedichloride: the extent of platinum binding to template dna in relation to the size of low molecular weight nascent dna.treatment of chinese hamster lung v79-379a cells with the anti-tumour agent cis platinum (ii) diamminedichloride, (cis pt(ii)), resulted in an immediate recuction in the rate of dna synthesis. sedimentation of newly synthesised dna through alkaline sucrose gradients revealed it to be approximately the same size as that obtained from untreated cells. in contrast, in the presence of 0.75 mm caffeine, the rate of dna synthesis rapidly returned to control levels, although sedimentation analysis show ...19761253338
sequence of centromere separation of mitotic chromosomes in chinese hamster.chromosome preparation in late metaphase cells from bone marrow of colcemid treated male chinese hamsters were used to analyse the sequence of separation of sister centromeres. chromatids of chromosomes 2 and 1 are the first ones to separate at centromeres, followed by members of group b, d and c. some acrocentric chromosome is always the last one to separate at the centromere. the data point to a possible correlation between the position of a centromere in the separation sequence in the genome ...19761253649
non-histone protein synthesis during g1 phase and its relation to dna replication.the kinetics of non-histone chromosomal protein (nhcp) synthesis were studied in chinese hamster ovary (cho) plateau phase cells stimulated to proliferate and were compared to nhcp synthesis kinetics in two populations of synchronous g1 traversing cells. in all cases, nhcp synthesis rates increase 3- to 5-fold as cells traversed g1 and attained maximum values one hour before semi-conservative dna replication began. similar to results in synchronous g1 cells, the molecular weight distributions of ...19761254652
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 ...19761256059
effects of laser uv-microirradiation (lambda = 2573 a) on proliferation of chinese hamster cells. 19761257404
the effect of hyperthermia on the repair of radiation damage in plateau phase cells.hyperthermia (41 degrees c for 1 hr.) completely inhibited both sublethal and potentially lethal radiation damage repair by plateau phase cells taken from v79 chinese hamsters. this suggests that there may be disadvantages in combining x-ray and heat therapies for the treatment of tumors.19761257447
hydroxyurea does not prevent synchronized g1 chinese hamster cells from entering the dna synthetic period. 19761259759
independent fluctuations of cytidine and adenosine diphosphate reductase activities in cultured chinese hamster fibroblasts.the activities of cdp and adp reductases were determined throughout the cell cycle of chinese hamster fibroblasts synchronized by partial deprivation of isoleucine. both enzyme activities were increased in s phase as compared to g1 phase. cdp reductase increased about 8-fold while adp reductase increased about 2.5-fold. the ratio of cdp to adp reductase was 0.26 at the g1 and early s phases of the cell cycle; the ratio was increased to 0.83 by late s phase. addition of actinomycin d or cyclohexi ...19761260052
quantification of mitochondria during the cell cycle of chinese hamster cells. 19761261614
selection and characterization of chinese hamster ovary cells resistant to the cytotoxicity of lectins.chinese hamster ovary (cho) cells selected in a single step for resistance to the cytotoxicity of the lectin from red kidney beans (pha) behave as authentic somatic cell mutants. the pha-resistant (phar) phenotype is stable in the absence of selection; its frequency in a sensitive-population is increased several-fold by mutagenesis; and it behaves recessively in somatic cell hybrids. the activity of a specific glycosyl transferase which transfers n-acetylglucosamine (glcnac) to terminal alpha-ma ...19761262042
alpha-amanitin resistance of rna polymerase ii in mutant chinese hamster ovary cell lines.a number of mutant chinese hamster ovary (cho) cell lines resistant to the cytotoxic action of alpha-amanitin have been isolated. the alpha-amanitin sensitivity of the different mutant cell lines varied widely, but correlated well with the alpha-amanitin sensitivity of the rna polymerase ii activity in each of these mutant cell lines. in comparison with the rna polymerase ii of wild-type cells, three mutants, ama39, ama6, and amal, required respectively 2- to 3-fold, 8- to 10-fold, and about 800 ...19761262341
formation of thymidine kinase and deoxycytidylate deaminase in synchronized cultures of chinese hamster cells temperature-sensitive for dna synthesis.cytosol thymidine kinase (tk) and deoxycytidylate (dcmp) deaminase formation was investigated in synchronized cultures of k12 chinese hamster cells which have a temperature-sensitive lesion affecting the initiation of dna synthesis. enzyme formation was found to be cycloheximide-sensitive and also temperature-dependent. beginning at about six hours after addition of medium with 10% calf serum to serum-depleted k12 cultures, cytosol tk and dcmp deaminase activities increased when the cultures wer ...19761262406
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