Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| mammalian cells with defective mitochondrial functions: a chinese hamster mutant cell line lacking succinate dehydrogenase activity. | a mutant cell line derived from chinese hamster fibroblasts is described which is defective in oxidative energy metabolism. glucose is continuously required in the medium. as a result of a block in the krebs cycle, these cells are auxotrophs for carbon dioxide and asparagine. several experiments support our conclusion that the mutant cells lack appreciable levels of succinate dehydorgenase activity. other components of the electron transport chain appear to be fully functional, although there is ... | 1977 | 558831 |
| an ultrastructural study of the recovery of chinese hamster ovary cells after freezing and thawing. | 1977 | 558864 | |
| cell cycle dependent changes in morphology. studied with a cold-sensitive mutant of chinese hamster ovary cells. | 1977 | 558900 | |
| control of glycoprotein synthesis. lectin-resistant mutant containing only one of two distinct n-acetylglucosaminyltransferase activities present in wild type chinese hamster ovary cells. | 1977 | 558978 | |
| human beta-glucuronidase: assignment of the structural gene to chromosome 7 using somatic cell hybrids. | beta-glucuronidase (gus) has become an important enzyme model for the genetic study of molecular disease, enzyme realization, and therapy, and for the biogenesis and function of the lysosome and lysosomal enzymes. the genetics of human beta-glucuronidase was investigated utilizing 188 primary man-mouse and man-chinese hamster somatic cell hybrids segregating human chromosomes. cell hybrids were derived from 16 different fusion experiments involving cells from ten different and unrelated individu ... | 1977 | 559490 |
| the pericentriolar material in chinese hamster ovary cells nucleates microtubule formation. | the structure and function of the centrosomes from chinese hamster ovary (cho) cells were investigated by electron microscopy of negatively stained wholemount preparations of cell lysates. cells were trypsinized from culture dishes, lysed with triton x-100, sedimented onto ionized, carbon-coated grids, and negatively stained with phosphotungstate. the centrosomes from both interphase and dividing cells consisted of pairs of centrioles, a fibrous pericentriolar material, and a group of virus-like ... | 1977 | 559676 |
| n-ethylmaleimide sensitization of x-irradiated hypoxic chinese hamster cells. | 1977 | 560026 | |
| dna repair in v-79 cells treated with combinations of ultraviolet radiation and n-acetoxy-2-acetylaminofluorene. | earlier experiments on human cells showed that n-acetoxy-2-acetylaminofluorene mimics ultraviolet radiation in biological and repair characteristics and that the amount of repair from a combined treatment was additive. chinese hamster v-79 cells are less proficient than human cells in excision repair of pyrimidine dimers resulting from irradiation. we therefore investigated the combined effects of both agents on repair in v-79 cells to see whether they follow the same pattern as in human cells. ... | 1977 | 560253 |
| replication of minute virus of mice in chinese hamster ovary fibroblasts. | minute virus of mice (mvm), a parvovirus, replicates in chinese hamster ovary (cho) cells. although replication of the virus cannot readily be detected by haemagglutination, it can be measured by plaque assay on mouse strain lm cells. | 1977 | 560425 |
| [effect of cysteamine on repair of individual dna breaks in an irradiated culture of chinese hamster cells]. | 2013 | 560703 | |
| [electron microscopic study of interphase in a culture of fibroblast-like cells]. | the analysis of the ultrastructural changes of fibroblast-like cells of chinese hamster at different periods of the cell cycle demonstrates that the most reliable morphological criteria for identification of different periods of the interphase are changes of the nuclear chromatin and nucleolus and the dynamics of development of the daughter centrioles. no prominent changes of the morphology of the protein-synthesizing apparatus during interphase were noted. | 1977 | 560735 |
| mutants of cho cells resistant to the protein synthesis inhibitors, cryptopleurine and tylocrebrine: genetic and biochemical evidence for common site of action of emetine, cryptopleurine, tylocrebine, and tubulosine. | stable mutants resistant to the protein synthesis inhibitors cryptopleurine and tylocrebine can be isolated in chinese hamster ovary (cho) cells, in a single step. the frequency of occurrence of cryptopleurine (cryr) and tylocrebrine (tylr) resistant mutants in normal and mutagenized cell populations is similar to that observed for emetine resistant (emtr) mutants. the cryr, tylr, and emtr mutants exhibit strikingly similar cross-resistance to the three drugs used for selection, to tubulosine an ... | 1977 | 560858 |
| effects of mercuric chloride on synchronized chinese hamster ovary cells: survival and dna replication. | chinese hamster ovary (cho) cells in vitro were treated with hgcl2 at various stages in the cell cycle and the effects of this chemical on cell survival, dna replication, and cell division were observed. in terms of survival the early g1 cells were the most sensitive to treatment, followed by late g1 and early s, while mid s and late s-g2 treated cells were the least sensitive. treatment with hgcl2 also resulted in reduced rates of dna replication and delays in cell division. the early g1 treate ... | 1977 | 560920 |
| [hybridization of chinese hamster cells sensitive to ultraviolet irradiation]. | resistance to uv-light was studied in two uv-sensitive aneuploid chinese hamster cell clones to different origin and degree of sensitivity, their respective polyploids and somatic cell hybrids. the karyotype of the parental clones, cell hybrids and polyploids was analyzed in parallel. a great variability of karyotypes was detected in hybrid cells. serial cultivation of hybrids was accompanied by chromosome loss. soon after fusion the hybrid clones proved to be more resistant to uv than the paren ... | 1977 | 561015 |
| segregation of human hypoxanthine phosphoribosyltransferase activity from somatic cell hybrids isolated from fusion of mouse gene transfer cells with chinese hamster cells. | 1977 | 561300 | |
| chromosome damage in chinese hamster cells sensitized to near-ultraviolet light by psoralen and angelicin. | the clastogenic effect of furocoumarins psoralen and angelicin in the presence of near-uv (320-380 nm) differs greatly, as do their modes of interaction with dna. psoralen, which requires only one-fifth as much light energy to produce the same lethal effect as angelicin at equimolar concentrations, is able to cross-link dna whereas angelicin cannot. the frequency of micronuclei which arise from chromosomal fragments shows the same differential effect as lethality. indeed aberrations account for ... | 1977 | 561302 |
| effects of wheat germ agglutinin on membrane transport. | (1) low concentrations of wheat germ agglutinin are cytotoxic toward several tissue culture lines, including chinese hamster ovary cells, swiss 3t3 cells, mouse l cells and baby hamster kidney cells. the ld50 ranged from 1 to 5 microgram wheat germ agglutinin per ml. similar concentrations of the lectin inhibited the transport of the non-utilizable amino acids alpha-aminoisobutyric acid and cycloleucine and inhibited the uptake of thymidine. in contrast, 2-deoxy-d-glucose uptake was not altered ... | 1977 | 561616 |
| sensitivity of different cell lines and of different phases in the cell cycle to hyperthermia. | the sensitivity of different cell lines (chinese hamster ovary, hela, l1210, and p388) to 43 degrees was compared chinese hamster ovary and hela cells were much less temperature sensitive than were l1210 or p388 cells. this difference persisted even when hela and l1210 cells were grown in the same medium and suggested that this was an inherent difference between the cell lines. of all the cell lines, 7-day l1210 ascites, maintained by transfer in mice, were the most sensitive. the greater sensit ... | 1977 | 561655 |
| chromosome loss is responsible for segregation at the hprt locus in chinese hamster cell hybrids. | the phenomenon of segregation of gene expression has been examined in intraspecific somatic cell hybrids. specifically, segregation at the hypoxanthine guanine phosphoribosyltransferase (hprt) locus has been studied in hybrids of chinese hamster cell lines. the role of chromosome segregation, or other chromosomal events has been assessed by detailed comparison of karyotypes in the 6-thioguanine resistant segregants with those of the parental hybrid lines. the results clearly demonstrate that los ... | 1977 | 562539 |
| turnover of tubulin and the n site gtp in chinese hamster ovary cells. | radioactively labeled tubulin from chinese hamster ovary (cho) cells can be isolated by co-polymerization with nonradioactive porcine brain microtubule protein. 75% of the soluble tubulin in cho extracts co-polymerizes with the porcine protein through several cycles, without preferential loss of either cho or porcine subunits. after phosphocellulose chromatography of the co-polymerized microtubules, the cho tubulin is radiochemically homogeneous, as judged by sds-polyacrylamide gel electrophores ... | 1977 | 562716 |
| clonal growth of chinese hamster cell lines in protein-free media. | a protein-free synthetic medium, mcdb 301, has been developed for clonal growth of chinese hamster ovary cell lines. medium f12 was developed originally for that purpose, but later failed to support good growth without small amounts of serum protein. growth was restored by the addition of nonphysiological amounts of commercially prepared thyroxine or smaller amounts of the trace element selenium. the thyroxine preparation was shown to contain sufficient selenium to account for all of its growth- ... | 1977 | 562838 |
| visualization of interphase chromosomes. | using a modified giemsa-banding technique we have observed what appear to be chromosomes during interphase in nuclei from allium cepa root tips and chinese hamster cells (cho line). during telophase through g1 chromosomes progressively uncoil and decondense. during s chromosomes are comparatively decondensed, but some segments have structure similar to chromosomes in g1 and g2. during g2 the chromosomes progressively recondense and coil in apparent preparation for prophase. although specific str ... | 1977 | 562895 |
| [replication of chromosomal dna in chinese hamster cells, cultivated at different temperatures]. | dna fiber autoradiography was used to measure the rate of replication and the size of replication units in chinese hamster cells cultured at 34, 37 and 39 degrees c. the average rate of dna replication per single fork is 0.6 mcm/min at 34 degrees and 0.8 mcm/min at 37 and 39 degrees. in contrast to the change in the rate of dna replication, no change was found in the size of replication units, which are more than 200 mcm at 31, 37 and 39 degrees. the change of the length of the s phase at variou ... | 1977 | 563118 |
| the incorporation of homologous and heterologous hypoxanthine-guanine phosphoriboxyltransferase into mutant cells. | experiments are described leading to partial compensation of a deficiency in the enzyme hypoxanthine-guanine phosphoribosyltransferase in mutant cells by supplying the cells with exogenous purified enzymes. deae-dextran is an effective helper agent, whereas poly (l-lysine), lysolecithin and amphotericin b seem to inhibit the entry of the enzymes of their activity. enzyme preparation from chinese hamster was found to have different effects in different mutant cell lines. in mutant chinese hamster ... | 1978 | 563735 |
| effects of hyperthermia on survival and progression of chinese hamster ovary cells. | 1978 | 563767 | |
| intrachromosomal gene mapping in man: the gene for tryptophyl-trna synthetase maps in region q21 leads to qter of chromosome 14. | a gene for tryptophanyl-trna synthetase (ec 6.1.1.2), the enzyme which attaches tryptophan to its trna, has previously been assigned to human chromosome 14 by analysis of man-mouse somatic cell hybrids. we report here a method for the electrophoretic separation of chinese hamster and human tryptophanyl-trna synthetases and its application to a series of independently derived chinese hamster-human hybrids in which part of the human chromosome 14 has been translocated to the human x chromosome. wh ... | 1977 | 564085 |
| biochemical genetics of chinese hamster cell mutants with deviant purine metabolism: characterization of chinese hamster cell mutants defective in phosphoribosylpyrophosphate amidotransferase and phosphoribosylglycinamide synthetase and an examination of alternatives to the first step of purine biosynthesis. | activities of the first three enzymes in the de novo purine biosynthetic pathway have been measured in cell-free extracts of the chinese hamster ovary cell (cho-k1) and two purine-requiring auxotrophs of this cell. ade-a has been found to be defective in phosphoribosylpryophosphate (prpp) amidotransferase while ade-c has been found to be defective in glycinamide ribonucleotide (gar) synthetase. neither enzyme deficiency is due to the presence of an excess of diffusible inhibitor, and mixed extra ... | 1977 | 564086 |
| long-term culture of chinese hamster kupffer cell lines isolated by a primary cloning step. | 1978 | 564778 | |
| hyperthermic treatment (43 degrees c) rapidly impedes attachment of fibroblasts to culture substrates. | hyperthermic (43 degrees c) exposure of chinese hamster fibroblasts for more than 30 min, either in suspension or as a monolayer, significantly inhibits their ability to attach to the culture substrate. this finding as well as the effect of hyperthermia on membrane proteins and on surface topology are rapidly expressed and differ from the inhibition of colony formation which is a later effect of hyperthermia on reproductive ability. | 1977 | 565256 |
| radionuclide toxicity in cultured mammalian cells: elucidation of the primary site of radiation damage. | synchronized suspension cultures of chinese hamster ovary cells (cho) were labeled with various doses of 3h-thymidine or 125i-iododeoxyuridine to evaluate the cytocidal effects of intranuclear radionuclide decay. damage produced by radionuclide decay outside the cell nucleus was studied on cells exposed to 125i labeled, monovalent concanavalin a. after labeling, the cells were resynchronized in g1-phase and incubated for 36 h at 4 degrees c to permit dose accumulation. cell lethality was evaluat ... | 1978 | 565271 |
| molecular suicide studies of 125i and 3h disintegration in the dna of chinese hamster cells. | the shape of the survival curve for cells inactivated by tritium decay in dna is modified by the presence of halogenated pyrimidines in the dna in a manner analogous to their effect on x-ray induced reproductive death. the large shoulder found for tritium suicide is removed completely by coincorporation of 10(-6) m iudr. the oxygen enhancement ratio for 125i and tritium disintegrations in unsynchronized chinese hamster cells was determined for cells permitted to accumulate damage from these even ... | 1978 | 565272 |
| cell survival and cytogenetic responses to 125i-udr in cultured mammalian cells. | the relative toxicity of dna precursors labeled with iodine-125, iodine-131, or hydrogen-3 was studied in exponentially growing chinese hamster cells. per decay, iodine-125 was found to be approximately 12 times as lethal as iodine-131 and 16 times as lethal as hydrogen-3. chromosomal aberrations induced in these cells by the three radionuclides occurred with the same relative efficacy as their lethal effects. | 1978 | 565273 |
| chromosome damage in chinese hamster cells produced by 125i-udr at the site of its incorporation. | metaphase chromosomal aberrations were produced by 125i-labeled iododeoxyuridine (125i-udr) incorporated into chinese hamster don cells at the end of the s-period of the cell cycle. chromosome damage and the number of autoradiographic silver grains were recorded for whole cells, for chromosome pairs no. 4 and no. 5, and for the x and the y chromosomes. the x and the y chromosomes, which label late in s, were at least twice as heavily labeled as chromosome pairs no. 4 and no. 5--two readily recog ... | 1978 | 565274 |
| [effect of temperature on the duration of mitosis in mammalian cells cultivated outside the body]. | nine cell strains of different origin were cultivated at 28--36 degrees with the interval of 2 degrees. during the phase of logarithmic culture growth, the duration of mitosis (tm) was determined by means of colchicine method. a strict temperatural dependence tm, obeyed to arrenius' law was revealed. temperature range within which arreinius' law is valid in different cell strains is not alike. cultivation of l cells and connective tissue cells from chinese hamster to 39, 41and 42 degrees demonst ... | 1978 | 565630 |
| the selection of wild-type revertants from methotrexate permeability mutants. | in a previous report, we described the selection and partial characterization of three distinct classes of methotrexate (mtx)-resistant chinese hamster ovary cells (cho) (1). class i cells contained a structural alteration in dihydrofolate reductase. class ii cells showed a alteration affecting the permeability of the drug. class iii cells, selected from class i cells, had an increased activity of the altered enzyme. in the work described here, the sensitivity of these lines to the diaminopyrimi ... | 1978 | 566473 |
| dominance of colchicine resistance in hybrid cho cells. | intraspecific hybrids of colchicine-sensitive with colchicine-resistant (chr) chinese hamster ovary cells were constructed, using six different colchicine-resistant clones from two independent series. in each instance, colchicine resistance was expressed in an incompletely dominant manner. some hybrid clones were examined further for the expression of the pleiotropic chr phenotype and for the cell surface p glycoprotein. these features of the colchicine-resistant phenotype were also expressed co ... | 1978 | 566474 |
| assignment of the genes for triose phosphate isomerase to chromosome 6 and tripeptidase-1 to chromosome 10 in mus musculus by somatic cell hybridization. | evidence is presented for the assignment of the gene for triose phosphate isomerase to mus musculus chromosome 6 and tripeptidase-1 to chromosome 10 by synteny testing and chromosome assignment in chinese hamster x mouse somatic cell hybrid clones. neither tpi nor trip-1 were expressed concordantly with any known isozyme markers in 45 hybrid clones (13 primary and 32 secondary). karyotypic analysis of 21 clones showed that the expression of tpi and chromosome 6 were concordant in all cases as wa ... | 1978 | 566475 |
| assignment of a mus musculus gene for triosephosphate isomerase to chromosome 6 and for glyoxalase-i to chromosome 17 using somatic cell hybrids. | chinese hamster x mouse hybrid cells segregating mouse chromosomes have been used to assign a gene for triosephosphate isomerase (tpi-1, ec 5.3.1.1, mckusick no. 19045) to mouse chromosome 6, and a gene for glyoxalase-i (glo-1, ec 4.4.1.5, mckusick no 13875) to mouse chromosome 17. the genes for tpi-1 and lactate dehydrogenase b are syntenic in man and probably so in the dog. it is therefore likely that they are syntenic also in the mouse. it is of interest then that there is a mouse gene, ldr-1 ... | 1978 | 566476 |
| [effect of inhibitors of rna and protein synthesis on the course of mitosis in a synchronized culture of chinese hamster cells]. | the synthesis period of various types of rna and proteins during the interphase related to the immediate after synchronization mitosis was investigated on teh synchronized culture of chinese hamster cells with inhibitors. analysis of mi and forms of mitosis pathology indicated the proteins functionally related to the cell division to be mainly synthesized during the second half of the interphase. the most important action of pyromycin during this time is the induction of c-mitosis on account of ... | 1978 | 566594 |
| mutagenesis by n-acetoxy-2-acetyl aminofluorene of chinese hamster v79 cells is unaffected by caffeine. | 8-azaguanine (azg)- and 6-thioguanine (tg)-resistant cells (mutants) were induced in chinese hamster v79-4 cells by 0.1--2.5 microgram/ml n-acetoxy-2-acetyle aminofluorine (acaaf) treatments in the presence of 5% fetal bovine serum (fbs). the frequency of resistant colonies increased from 1 to 47 per 10(5) survivors. the effect of caffeine (50--200 microgram/ml) during the mutagenesis expression period was determined by adding caffeine 1--24 h after acaaf. the medium was replaced after 48 h expo ... | 1978 | 566636 |
| the action of af 2 on cultured hamster and human cells under aerobic and hypoxic conditions. | af 2 (2-(2-furyl)-3-(5-nitro-furyl)acrylamide) was toxic to chinese hamster v 79 cells and normal human fibroblasts in aerobic media. however, the toxicity of the drug was increased many times by hypoxia. similarly, the frequency of af 2-induced azaguanine- and ouabain-resistant mutants of v 79 cells was much higher in hypoxia than under aerobic conditions. both hamster v 79 cells and human fibroblasts metabolized af 2 and other nitrofurans rapidly only under hypoxic conditions. human fibroblast ... | 1978 | 566638 |
| time and cell systems as variables in fusion experiments with polyethylene glycol. | cell hybridization was done between a monolayer of b14-150 chinese hamster cells and a suspension of either mouse leukemia cells or normal human lymphocytes. cell contact was obtained by centrifugation of the suspension cells onto the monolayer cells in a culture plate. cell fusion was done by means of polyethylene glycol (peg). the optimum time for peg exposure as well as the yield of hybrid cells differed markedly with the different combinations. | 1978 | 566713 |
| induction of sister-chromatid exchanges in chinese hamster ovary cells treated in vitro with non-k-region dihydrodiols of 7-methylbenz[a]anthracene and benzo[a]pyrene. | studies were carried out on the incidence of sister-chromatid exchanges induced in chinese hamster ovary cells by in vitro treatment with the polycyclic aromatic hydrocarbons 7-methylbenz[a]anthracene and benzo[a]pyrene and with related k-region and non-k-region dihydrodiols. appreciable increased in the incidence of sister-chromatid exchanges were apparent in cells treated with non-k-region dihydrodiols: the most active compounds were 3,4-dihydro-3,4-dihydroxy-7-methylbenz[a]anthracene and 7,8- ... | 1978 | 566850 |
| mutagenicity of thymidine to cultured chinese hamster cells. | 1978 | 566859 | |
| dna replication in x-irradiated chinese hamster cells made permeable to deoxyribonucleoside triphosphates. | 1978 | 566939 | |
| ultraviolet light and x-ray damage interaction in chinese hamster cells. | 1978 | 566940 | |
| [remote changes in the course of mitosis in synchronized cultures of chinese hamster cells following inhibition of rna and protein synthesis]. | the effect of inhibition of the synthesis of some types of rna and proteins was determined in the synchronized culture of chinese hamster cells at various stages of the interphase on the course of remote mitosis. analysis of mi and some forms of pathological cell division showed that the action of different doses of amd and pyromycin during the first part of the interphase provoked an identical effect--c-mitosis at the immediate and remote waves of cell division. suppression of the synthesis of ... | 1978 | 567074 |
| effects of chartreusin on cell survival and cell cycle progression. | chartreusin was lethal to both l1210 and p388 cells in culture with 90% of the cells being killed after a 24-hr exposure to 1.1 and 2.6 microgram/ml, respectively. the lethality of the drug increased in direct proportion to dose and exposure time. both l1210 and chinese hamster ovary cells in s phase were more sensitive to the lethality of the drug than were their corresponding non-s-phase cells. l1210 cells were partially synchronized by exposing an asynchronous culture to [methyl-3h]thymidine ... | 1978 | 567096 |
| [phenomenon of premature chromatin condensation following fusion of chinese hamster cells using polyethyleneglycol]. | 1978 | 567115 | |
| [repair of dna--protein cross-links in cultivated chinese hamster cells]. | 1978 | 567116 | |
| enrichment and visualization of small replication units from cultured mammalian cells. | dna from cultured chinese hamster cells has been fractionated to yield a population of dna enriched for replicating molecules. molecules containing replication structures were analyzed by electron microscopy, and replicon size was estimated. the enrichment procedure takes advantage of single-stranded regions characteristic of replicating molecules, and the greater affinity of mercuric ion for single-stranded rather than native dna. after interaction with low concentrations of hgcl2, dna with bou ... | 1978 | 567225 |
| tyrosyltubulin ligase and colchicine binding activity in synchronized chinese hamster cells. | tyrosyltubulin ligase (ttl) was found to be present in cho and v79 chinese hamster cells grown in tissue culture. the enzyme is soluble and requires potassium, magnesium, and atp for maximum activity and requires tubulin as a substrate. ttl was analyzed through the cell cycle of v79 and cho chinese hamster cells. the enzyme showed two peaks of activity in v79 cells at 4 h and 7 h after mitotic selection, corresponding to the early s and mid to late s phases of the cell cycle. in cho cells the en ... | 1978 | 567652 |
| mutagenicity of vinyl chloride. external chromosome studies on persons with and without vc illness, and on vc exposed animals. | chromosome analysis was undertaken on lymphocyte cultures taken from (1) six workers with estimated exposure to vc and four workers with monitored exposure to vc (employed in the basf); (2) 20 workers showing symptoms of vc illness with unknown exposure and one angiosarcoma case, due to vc exposure (not employed in the basf); and, (3) on bone marrow cells of chinese hamsters after inhalation of 2,500 ppm or 5,000 ppm, or after intraperitoneal injections of 300 mg/kg or 600 mg/kg. the proband gro ... | 1978 | 567683 |
| properties of the thymidine transport system of chinese hamster ovary cells as probed by nitrobenzylthioinosine. | the transport of thymidine into chinese hamster ovary cells grown in suspension culture was measured under conditions in which thymidine was not metabolized, namely, when cells had been depleted of atp. the system transporting thymidine was saturable (kztm = 70 micron), rapid 50% of transmembrane equilibrium level attained within 8 sec), and was apparently shared by other nucleosides, but not thymine or hypoxanthine. 6([4-nitrobenzyl]thio)-9-beta-d-ribofuranosylpurine, "nitrobenzylthioinosine", ... | 1978 | 568178 |
| hybridization of cultured chinese hamster kupffer cells possessing quantitative differences in enzyme activities. | 1978 | 568558 | |
| genetic characterization of hydroxyurea-resistance in chinese hamster ovary cells. | hydroxyurea is an excellent selective agent for obtaining drug-resistant mutants. at a frequency of approximately 1 x 10(-5) it was possible to select, in a single step, colonies that exhibited significant resistance to the cytotoxic effects of the drug. these hydroxyurea-resistant cell lines maintained their resistant phenotype after extensive cultivation in the absence of the drug. reconstruction experiments indicated that the expression of hydroxyurea-resistance and the frequency of drug-resi ... | 1978 | 568629 |
| ribonucleotide reductase from wild type and hydroxyurea-resistant chinese hamster ovary cells. | the kinetic properties of partially purified ribonucleotide reductase from chinese hamster ovary cells have been investigated. double reciprocal plots of velocity against substrate concentration were found to be linear for three the substrates tested, and yielded apparent km values of 0.12 mm for cdp, 0.14 mm for adp and 0.026 mm for gdp. hydroxyurea, a potent inhibitor of ribonucleotide reduction, was tested against varying concentrations of ribonucleotide substrates and inhibited the enzyme ac ... | 1978 | 568630 |
| effects of bouvardin (nsc 259968), a cyclic hexapeptide from bouvardia ternifolia, on the progression capacity of cultured chinese hamster. | 1978 | 569011 | |
| ultrastructural study of virus-like particles in chinese hamster lung cells. | virus-like particles were found in the e36 cells. one type, associated with centrioles, consisted of two concentric shells with a diam. of 50 to 60 nm. some of these particles were seen budding through the plasma membrane giving rise to a free immature particle showing two concentric shells and an outer envelope. concentration of the inner shell into a nucleoid results in a mature particle characterized by a nucleoid, mainly eccentrically located, surrounded by an intermediate layer and wrapped ... | 1978 | 569185 |
| assignment of the gene for glyoxylase i to mouse chromosome 17 by somatic cell genetics. | evidence is presented for the assignment of the gene for glyoxylase i to mouse chromosome 17 using mouse x chinese hamster somatic cell hybrids. glo i was not expressed concordantly with any known marker enzymes which represented 11 linkage groups. the presence of chromosome 17 and expression of glo i were concordant in 31/31 clones. glo i is thus linked to the h-2 histocompatibility locus in the mouse. | 1978 | 569476 |
| [repair of dna--protein cross-links in a culture of chinese hamster cells. possible molecular mechanisms]. | 1978 | 569570 | |
| hyperthermic radiosensitization of synchronous chinese hamster cells: relationship between lethality and chromosomal aberrations. | 1978 | 569879 | |
| quinacrine-enhanced killing response of cultured chinese hamster cells by x-rays. | 1978 | 569894 | |
| replicon sizes in mammalian cells as estimated by an x-ray plus bromodeoxyuridine photolysis method. | a new method is described for estimating replicon sizes in mammalian cells. cultures were pulse labeled with [3h]thymidine ([3h]tdr) and bromodeoxyuridine (brdurd) for up to 1 h. the lengths of the resulting labeled regions of dna, lobs, were estimated by a technique wherein the change in molecular weight of nascent dna strands, induced by 313 nm light, is measured by velocity sedimentation in alkaline sucrose gradients. if cells are exposed to 1,000 rads of x-rays immediately before pulse label ... | 1978 | 570067 |
| a simple method for producing different growth fractions in vitro for use in anti-cancer drug studies. | a simple technique has been used experimentally to produce in vitro chinese hamster ovary cells with growth fractions ranging from 0 to 100%. known numbers of exponentially growing and plateau-phase tissue culture cells were mixed in various proportions to yield the desired final growth fraction. cells attach to the culture flask surface within 1 hr of mixing. treatment at that time with the nitrosourea compounds, ccnu and meccnu, resulted in differential drug survival sensitivities that were de ... | 1979 | 570456 |
| [effect of polyethyelene glycol on proliferation of cultured chinese hamster cells]. | chinese hamster cells in suspension were treated with peg 4000 for 20 min. it was found that cell size began to diminish already when a 5% peg solution was used, and reached the minimal value in a 20% peg solution. a pronounced cell death was observed when peg concentration exceeded 20%, but cells that survived retained their proliferation potential. it is concluded that the cell death results from hypoosmotic shock when cell suspension in peg solution is diluted. | 1979 | 571153 |
| endocrine factors contributing to the ethanol preferences of rodents. | groups of c57 bl/6j mice (alcohol preferring) and dba/2j mice (alcohol avoiding) were fasted for 24 hours and administered glucose. at 30, 120 and 300 minutes after glucose, the c57 bl/6j mice had significantly higher levels of plasma glucose than the dba/2j strain. these differences were observed in comparable groups given either forced access or no access to alcohol. in ad lib fed animals never exposed to alcohol, c57 bl/6j mice had higher levels of plasma insulin than dba/2j mice. plasma leve ... | 1979 | 572551 |
| [interaction of lambda bacteriophages with mammalian cells. ii. elucidation of the role of interacting components]. | the study of 3h-thymidine labelled bacteriophage lambda c185757 uptake by hela, rh and chinese hamster cell revealed the lack of cells or phage specificity in the phage interaction with cells. the phage uptake is shown to be an active process depending on the cell state. the mechanism of "protective" action of calcium chloride is found to be as follows: the calcium phosphate precipitate formed in phosphate-containing media absorbs the phage, thus increasing its concentration on the cell surface, ... | 1979 | 572596 |
| radioprotection by dmso of mammalian cells exposed to x-rays and to heavy charged-particle beams. | populations of g1-phase chinese hamster cells in stirred suspensions containing various concentrations of dmso were irradiated with 250 kv x-rays or various heavy charged-particle beams. chemical radioprotection of cell inactivation was observed for all let values studied. when cell survival data were resolved into linear and quadratic components, the extent and concentration dependence of dmso protection were found to be different for the two mechanisms. the chemical kinetics of radioprotection ... | 1979 | 572979 |
| the effect of cis-platinum on the repair of radiation damage in plateau phase chinese hamster (v-79) cells. | 1979 | 575118 | |
| cytogenetic characterization of chinese hamster-sheep somatic cell hybrids. | the methods used to characterize cytogenetically chinese hamster x sheep somatic cell hybrids have been reported. g and c banding patterns on hybrid metaphases allowed the discrimination between hamster and sheep chromosomes, and in addition to establish the unidirectional loss of sheep chromosomes in hybrid cells. | 1979 | 575764 |
| mutagenicity testing in industry. | the aims of authorities, university and industrial scientists are outlined. the prime feature remains: how important are the achieved results for estimating the mutagenic risk to humans? the various methods available for the testing of chemical substances for mutagenicity are compared. their usefulness to estimate the mutagenic risk are considered and the disadvantages and advantages of such methods are discussed. the industrial toxicologist must apply those methods which permit the most accurat ... | 1977 | 578711 |
| small numbers in mutagenicity tests. | experimental control material for statistical analysis of the results of the micronuclei test in the mouse (nmri strain) and the chinese hamster and for the host-mediated assay in the mouse (nmri strain) using auxotrophic bacterial strains are presented. the binomial distribution of the micronuclei makes it possible to analyse the sample size according to the formula of cochran and cox (1957). for the host-mediated assay, the experimental principles are given which make it possible to evaluate t ... | 1977 | 578712 |
| cyto-enetic investigations of mammals. comparison of the genetic activity of cytostatics in mammals. | mutagenicity tests have been performed with cp, ip and tp. there is an increase of mutagenic activity from tp to ip to cp 8 h after the second intraperitoneal application. this has been confirmed by analysis of bone marrow chromosomes of mice, rats and chinese hamsters. the maximum mutagenic activity of all three cytostatics was found 12 h after the second injection. thereafter the aberration rate induced by cp decreased quickly. the inactivation of ip and tp and the elimination of chromosome ab ... | 1977 | 578713 |
| mutagenicity studies with praziquantel, a new anthelmintic drug, in mammalian systems. | praziquantel, a new anthelmintic drug with antischistosomal and anticestodal properties, was tested in comparison with a placebo control and a 'positive control' with cyclophosphamide in mammalian test system in vivo for potential mutagenic effects. the test systems used and the tested doses of praziquantel were: (1) dominant lethal test on male nmri mice, 12 mating periods of 4 days each, 1 x 1200 mg/kg bw by mouth; (2) dominant lethal test on female nmri mice, treatment during pre-estrus, 1 x ... | 1978 | 580366 |
| folate-dependent enzymes in cultured chinese hamster ovary cells: evidence for mutant forms of folylpolyglutamate synthetase. | 1979 | 583488 | |
| streptozotocin-induced diabetes in the chinese hamster. biochemical and endocrine disorders. | streptozotocin treatment (125 mg/kg) in the chinese hamster induced hyperglycaemia, hypoinsulinaemia, hyperglucagonaemia and changes in body, liver, pancreas, stomach, kidney and adipose tissue weights. the pancreatic reserves of insulin and glucagon in the diabetic animals were low, but stomach glucagon high. these animals showed high levels of phosphoenolpyruvate carboxykinase and low levels of glucokinase, hexokinase, isocitrate dehydrogenase and malic enzyme, but normal levels of pyruvate ki ... | 1977 | 590651 |
| cytotoxicity of commonly used solvents at elevated temperatures. | at 43 degrees c (but not at 41 degrees c), organic solvents used to dissolve water-insoluble chemotherapeutic agents become themselves lethal to cells. this finding is not unique to chinese hamster cells (ha-1); mouse mammary sarcoma cells (emt-6) behave similarly. the solvent concentrations involved are in the range of those needed to make drug solutions. hence experiments measuring drug-cell interactions at elevated temperatures must include controls which independently measure solvent effects ... | 1977 | 591566 |
| induction of sister chromatid exchanges in chinese hamster cells by carcinogenic mutagens requiring metabolic activation. | 1977 | 593288 | |
| a fluence response study of lethality and mutagenicity of white, black, and blue fluorescent light, sunlamp, and sunlight irradiation in chinese hamster ovary cells. | under a set of defined experimental conditions, the fluence response of chinese hamster ovary (cho) cells to various light sources was studied by measuring single-cell survival and mutation to 6-thioguanine (tg) resistance. fluorescent white, black, and blue lights were sightly lethal and mutagenic. sunlamp light was highly lethal and mutagenic, exhibiting these biological effects within 15 sec of exposure under conditions recommended by the manufacturer for human use. lethal and mutagenic effec ... | 1977 | 593289 |
| detection of chemically induced somatic mutation in chinese hamsters. | 1977 | 593291 | |
| the effect of cyclophosphamide on the centromere separation sequence in chinese hamster spermatogonia. | the sequence of centromere separation in spermatogonial chromosomes of untreated and cyclophosphamide-treated chinese hamsters is described. centromeres of chromosome 1 and 2 separated much earlier than all other chromosomes, especially 6-8. cyclophosphamide significantly inhibits the centromere separation in all chromosome groups but does not alter the sequence of separation. | 1977 | 598845 |
| effects of ultraviolet light on synchronized chinese hamster ovary cells; potentiation by hydroxyurea. | we have examined the effects of hydroxyurea on u.v.-irradiated chinese hamster cho-ki cells. ultraviolet irradiation followed by incubation with hydroxyurea causes only slight disruption of dna and chromosome structure in cho-ki cells compared with hela cells. there is, however, a clear potentiation by hydroxyurea of the u.v. killing of cho-ki cells, which is most pronounced at those points in the cycle which are reported to have small dna precursor pools. this potentiation is reduced when dna p ... | 1977 | 599176 |
| tyzzer's disease in the chinese hamster (cricetulus griseus). | 1977 | 599880 | |
| a search for allelic recombination in chinese hamster cell hybrids. | mutants resistant to 6-thioguanine were selected from cho cells which were either temperature sensitive or proline requiring. these mutants were stable and had low levels of hypoxanthine guanine phosphoribosyl transferase (hgprt). hybrids were selected which were heteroallelic at the hgprt locus and complementation between the mutants used was not observed. interallelic recombination at this locus would generate hgprt+ cells which could be selected in littlefield's hat medium. selection experime ... | 1977 | 600266 |
| chromosome stability in cho cells. | the established cell line derived many years ago from chinese hamster ovary (cho cells) has been studied for the extent of chromosomal variation. because this cell line is used extensively for genetic studies, the contribution of chromosome variability to genetic variability has also been examined. the quasidiploid cho cells were found to have a banded karyotype somewhat altered from that of the chinese hamster from which the line was derived. however, most of the genome could be accounted for a ... | 1977 | 601677 |
| complementation between mutants of cho cells resistant to a variety of plant lectins. | chinese hamster cell mutants resistant to the lectins pha, wga, ric, lca, and con a were previously grouped into 8--10 distinct phenotypes on the basis of their unique patterns of lectin resistance and lectin-binding properties. all but one of these classes of lectin-resistant (lecr) mutants behave recessively in somatic cell hybrids. one ricin-resistant class (ricrii) behaves dominantly. tests for complementation, by measuring the lectin-resistant properties of appropriate hybrids, show that se ... | 1977 | 601679 |
| segregation studies in cho hybrid cells: i. spontaneous and mutagen-induced segregation events of two recessive drug-resistant loci. | the process of segreation or phenotypic expression of two recessive drug-resistant loci from heterozygous chinese hamster ovary hybrid lines is examined. the spontaneous segregation rates of phytohaemagglutinin resistance (phar) and a temperature-dependent 8-azaguanine-resistant locus (azarts) from heterozygous quasitetraploid lines using luria-delbruck fluctuation analysis were 5 x 10(-5) and 10(-5) events/cell/generation, respectively. in quasihexaploid lines, the latter rates increased 40- an ... | 1977 | 605380 |
| variant chinese hamster cells resistant to the proline analog l-azetidine 2-carboxylic acid. | variants resistant to the toxic effects of the proline analog l-azetidine 2-carboxylic acid (azca) have been isolated from the chinese hamster tissue culture line g3 by a three-step selection procedure using increasing concentrations of azca. cells surviving each of the three selective steps have been examined for azca resistance and for proline uptake, biosynthesis, and degradation. the largest increment in azca resistance is acquired in the third step and is due to overproduction of proline as ... | 1977 | 605386 |
| mutants of chinese hamster ovary cells with altered glucose-6-phosphate dehydrogenase activity. | two mutant clones of a chinese hamster ovary cell line deficient in glucose-6-phosphate dehydrogenase (g6pd) activity have been characterized. in each case, there is evidence that a structural gene mutation has taken place. the first mutant produces 11% specific enzyme activity compared to wild-type parental cells, but this residual activity is much more heat sensitive than that of the wild type. the second mutant contains no residual activity, but a revertant was isolated that exhibits a partia ... | 1977 | 605387 |
| chromosome replication patterns in an established cell line (cho). | the chromosome replication patterns of the established cell line cho have been examined and compared with those of normal primary chinese hamster cells, using the budr-hoechst fluorescence technique developed by latt (1973). the results of this study indicate that the majority of cho chromosomes replicate normally. there are four clear-cut exceptions to this rule, three of which are most easily explained as undetected or misinterpreted structural rearrangements ot the cho genome. several other r ... | 1977 | 606507 |
| repair of the sublethal and mutational damage induced by x-rays in chinese hamster hai cells in vitro. | the ability of chinese hamster hai cells to repair damage related to cell death and mutational change induced by x-rays were examined by using a sensitive forward mutation system from prototrophic ch-hai cl 23 cells to auxotrophs. the results obtained from the split dose experiments seem to suggest that chinese hamster hai cells have the repair mechanisms for the sublethal and mutational damage induced by x-rays and that the repair mechanisms act in common for the repair of both cases of damage. | 1977 | 608187 |
| a method for the isolation of chinese hamster cell variants with an altered ability to utilise carbohydrates. | chinese hamster ovary cells (cho-k1) are able to utilise only a few carbohydrates for growth such as glucose, mannose, fructose and galactose. they do not grow on ribose, lactose, sucrose, glycerol, lactate, pyruvate, citrate, succinate, fumarate or malate nor on glycogenic or ketogenic amino acids. after mutagenesis and selection in glucose free medium supplemented with various, individual, growth substrates, we have isolated single-cell derived clones which are now able to grow on one of the f ... | 1977 | 610884 |
| properties of carbohydrate utilising variants of chinese hamster cells. | variants of chinese hamster ovary cells (cho-k1) have been isolated which can grow on one of the following carbohydrates: lactose, sucrose, ribose or lactate. the ribose+ clones grow at the same rate on glucose as the parental cells whereas the others grow more slowly. with the exception of one ribose+ clone all excrete lactic acid while growing on glucose; none excrete significant amounts of lactic acid while growing on the alternative energy source. wild-type cells and the variants accumulate ... | 1977 | 610885 |
| [induction of gene mutations and the lethal action of ultraviolet rays in synchronized chinese hamster cells]. | lethal and mutagenic effects of uv light were studied in two synchronized uv-sensitive chinese hamster cell clones differing in the degree of sensitivity (chs1, chs2). it is shown that the phase of mitosis is most resistant to the lethal effect of uv. the sensitivity of both cell clones increases in the pre-synthetic phase and reaches its maximum during the phase of dna synthesis. positive correlation of cell sensitivity to mutagenic and lethal action of uv was observed when studying induced mut ... | 1977 | 612481 |
| [rate of spontaneous chromosome aberration occurrence in cultured chinese hamster cells]. | the spontaneous chromosome mutation rate was studied in cultured aneuploid chinese hamster cells (clone 237(1)) using the method of slowing down the rate of cell division in a limiting medium containing 0.1% of serum. it was shown that during one cell generation (which lasted 14 days in limiting medium) the accumulation of chromosome aberrations with time took place. the data obtained are in keeping with the assumption of a linear dependence of this accumulation on time. the spontaneous chromoso ... | 1977 | 612482 |
| biochemical characterization of a mutant asparaginyl-trna synthetase from chinese hamster ovary cells. | the biochemical and physical properties of asparaginyl-trna synthetase from wild type chinese hamster ovary cells and a temperature sensitive mutant strain (lys 65a) are compared. the asparaginyl-trna synthetase in the mutant strain exhibits a greater temperature lability in vitro, a higher temperature-independent km for asparagine, and a lower temperature-dependent catalytic capacity than the enzyme from the wild type strain. the mutant enzyme shows no differences in its molecular weight, its k ... | 1978 | 618867 |
| adhesion and detachment characteristics of chinese hamster cell membrane mutants. | we have investigated the adhesion and detachment properties of wild-type chinese hamster cells and of variant lines, which possess altered cell surface glycoproteins as detected by galactose oxidase-[3h]borohydride labeling. the wild-type and variant lines tested all adhered to protein-coated glass surfaces at the same rate; however, the variant cells differed from wild type and from each other in terms of the ease with which they were detached by trypsinization. morphological differences betwee ... | 1978 | 618896 |
| a possible difference in the mechanism of replication of moderately repeated nucleotide sequences in chinese hamster ovary cells. | 1978 | 620691 | |
| assay of ribonucleotide reduction in nucleotide-permeable hamster cells. | ribonucleotide reduction was measured in chinese hamster ovary cells made permeable to nucleotides by treatment with the detergent tween-80. when compared to the respective ribonucleotide reductase activity in partially purified cell extracts, cdp and gdp reductase activities in permeabilized cells responded in a similar fashion to dithiothreitol, ph, mgcl2, fecl3, substrate concentration and the presence of positive or negative allosteric effectors. at low protein concentrations both cdp and gd ... | 1978 | 621224 |