Publications
| Title | Abstract | Year(sorted descending) Filter | PMID Filter |
|---|
| mutagenicity and cytotoxicity of congeners of two classes of nitroso compounds in chinese hamster ovary cells. | the induction of mutation by certain nitrosamidines and nitrosamides has been quantitated utilizing the hypoxanthine--guanine phosphoribosyl transferase (hgprt) locus in chinese hamster ovary cells. dose--response relationships for cytotoxicity and mutagenicity are presented for n-methyl-n-nitrosourea (mnu), n-ethyl-n-nitrosourea (enu), n-butyl-n-nitrosourea (bnu), n-methyl-n'-nitro-n-nitrosoguanidine (mnng), and n-ethyl-n'-nitro-n-nitrosoguanidine (enng). based on the concentration of each agen ... | 1978 | 661840 |
| [characteristics of mitosis pathology in a chinese hamster cell culture with disorders of the protein-synthesizing system]. | disturbance of protein synthesis with puromycin and transcription of chromosomal and ribosomal rna with actinomycin d was followed by marked changes in the normal course of mitosis. there was noted an increase in number of colchicin-like mitoses (c-mitoses), and particularly, sometimes, fragmentation of their cytoplasm with the formation of cluster-like structures. it is suggested that development of c-mitosis was connected not only with destruction in the mitotic apparatus formation system, but ... | 1978 | 656611 |
| cell-cycle-specific chromosome damage following treatment of cultured chinese hamster cells with 4'-[(9-acridinyl)-amino]methanesulphon-m-anisidide-hcl. | the induction of chromosome damage in chinese hamster (line cho) cells by 4'-[(9-acridinyl)-amino]methanesulphon-m-anisidide-hcl (mac) (nsc-141549) was studied in cell populations growing exponentially and at various stages of the cell cycle following release from isoleucine-deficient g1-arrest. autoradiographic analysis demonstrated that cells in s-phase at time of drug addition (2 microgram mac/ml for 2 hr) were delayed 8 hours before entering mitosis. cells in g1 at the time of mac treatment ... | 1978 | 642032 |
| kinetic response of cultured chinese hamster cells to treatment with 4'-[(9-acridinyl)-amino]methanesulphon-m-anisidide-hcl. | 1978 | 642031 | |
| effect of lucanthone hydrochloride on the radiation response of intestine and bone marrow of the chinese hamster. | a sublethal dose of 100 mg lucanthone hydrochioride/kg (miracil d, nilodin; nsc-14574) administered ip into chinese hamsters [median lethal dose for 30-day survival (ld50/30) of 315 mg/kg] reduced the radiation tolerance of the small intestine and had little or no effect on the radiation tolerance of the bone marrow. lucanthone hydrochloride was administered at various times before and after whole-body 60co gamma-irradiation. the median lethal dose for 7-day survival (ld50/7), indicative of deat ... | 1978 | 642024 |
| dna synthesis and cell survival after x-irradiation of mammalian cells treated with caffeine or adenine. | the expression of the transient depression in the rate of dna synthesis normally observed after exposure of randomly-dividing chinese hamster v-79 or chinese hamster cho cells to ionizing radiation can be postponed or diminished by a post-irradiation treatment with 1.0 to 1.0 mm adenine or 1.5 mm caffeine. caffeine may exert its effect by creating additional sites for replication in irradiated cells. cells treated with caffeine or adenine for 2 or 4 hours after exposure to 3000 rad of 300 kvp x- ... | 1978 | 306981 |
| radiolysis of chromatin extracted from cultured mammalian cells: production of alkali-labile strand damage in dna. | chromatin has been isolated from cultured chinese-hamster lung fibroblasts as an expanded aqueous gel. the dna in isolated chromatin has been examined by sedimentation on alkaline sucrose gradients. the average molecular weight of the dna has been determined to be 50 million. gamma-irradiation of isolated chromatin degrades the dna to lower molecular weight. the yield of single-strand breaks in the dna is 0.02 single-strand breaks per krad-10(6) dalton, calculated from a dose-range of &--400 kra ... | 1978 | 306978 |
| quantitative initiation of microtubule assembly by chromosomes from chinese hamster ovary cells. | the microtubule nucleating capacity of chromosomes was tested in vitro in lysates of chinese hamster ovary cells. colcemid-blocked mitotic cells were lysed with the detergent triton x-100, incubated with exogenous porcine brain tubulin, attached to electron microscope grids and observed as whole-mounts. under suitable conditions, greater than 98% of the chromosomes gave rise to microtubules at their kinetochore regions, thus unequivocally demonstrating that chromosomes are competent to initiate ... | 1978 | 299651 |
| comparative mutagenicity of alkylsulfate and alkanesulfonate derivatives in chinese hamster ovary cells. | mutation induction and cell killing produced by selected alkylsulfates and alkanesulfonates have been quantitated using the chinese hamster ovary/hypoxanthine--guanine phosphoribosyl transferase (cho/hgprt) system. dose--response relationships of cytotoxicity and mutagenicity are presented for two alkylsulfates [dimethylsulfate (dms), diethylsulfate (des)] and three alkyl alkanesulfonates [methyl methanesulfonate (mms), ethyl methanesulfonate (ems), and isopropyl methanesulfonate (ipms)]. under ... | 1978 | 207981 |
| dna replication in ultraviolet light irradiated chinese hamster cells: the nature of replicon inhibition and post-replication repair. | 1978 | 650688 | |
| partial purification of centrosomes from chinese hamster ovary cells. | 1978 | 639866 | |
| ultraviolet light and x-ray damage interaction in chinese hamster cells. | 1978 | 566940 | |
| dna replication in x-irradiated chinese hamster cells made permeable to deoxyribonucleoside triphosphates. | 1978 | 566939 | |
| effect of salt solutions on the radiosensitivity of mammalian cells. iv. treatment with nacl solutions containing ouabain, nem, pnap, cysteamine or dmso. | the effects of a wide concentration range of nacl solutions containing either ouabain, ethanol, para-nitroacetophenone (pnap), n-ethylmaleimide (nem), cysteamine or dimethyl sulphoxide (dmso) on cellular radiosensitivity have been examined. ouabain and nem treatment increased the radiosensitivity of v79 chinese hamster cells, but the action of these chemicals did not depend on the concentration of nacl. pnap increased cellular radiosensitivity with increasing nacl concentration reaching a maximu ... | 1978 | 305908 |
| effects of neocarzinostatin on mammalian nuclei: release of nucleosomes. | when chinese hamster cell nuclei (line cho) were reacted with neocarzinostatin and its dna was analyzed on non-denaturing agarose gel electrophoresis, a series of bands with a multiplicity of 175 base pairs was obtained. a similar result was also obtained when the dna samples were electrophoresed under denaturing gels. our results suggest that the linker dna between nucleosomes is the susceptible site to the drug and that neocarzinostatin can be used to study the chromatin structure. | 1978 | 147106 |
| effect of damage to early, middle, and late-replicating dna on progress through the s period in chinese hamster ovary cells. | 1978 | 631218 | |
| the rate of deoxyribonucleic acid synthesis by cultured chinese-hamster ovary cells. an application of isotope-dilution analysis. | the rate of dna synthesis is exponentially growing cells was determined by isotopedilution analysis of the incorporation of [me-3h]thymidine. thymidine concentrations greater than 7 micrometer were used so that the rate-limiting step governing incorporation would be at the level of dna polymerase rather than at the level of thymidine kinase [sjostrom & forsdyke (1974) biochem. j. 138, 253-262]. in early exponential phase the rate determined by isotope-dilution analysis closely correlated with th ... | 1978 | 348202 |
| collagen biosynthesis by cultured chinese hamster lung cells. cell-free synthesis of procollagen alpha chains. | cell-free extracts from the htl clone of cultured chinese hamster lung cells efficiently promote the incorporation of proline into newly synthesized material, 50% of which is digestible to small peptides by highly purified bacterial collagenase. the synthesis of the these products occurs under optimal protein synthesis conditions and is inhibited by puromycin. sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the cell-free synthesized material reveals a major collagenase sensitive pea ... | 1978 | 204330 |
| enhancement of repair replication in mammalian cells by hydroxyurea. | the effect of hydroxyurea on dna repair replication has been studied in chinese hamster ovary cells. mitotic cells were treated with uv irradiation, methyl methanesulfonate or nitrogen mustard and incuated in the presence of each of the 4 [3h] deoxyribonucleosides plus brdurd and fdurd for 2 h. the amount of repair replication was quantitated on cscl gradients and similar values were obtained for each nucleoside. in all cases addition of hu during the incubation period increased these values app ... | 1978 | 740011 |
| absence of interaction between x-rays and uv light in inducing ouabain- and thioguanine-resistant mutants in chinese hamster cells. | chinese hamster ovary cells were irradiated with x-rays at times from 0 to 17 h before being irradiated with ultraviolet (uv) light. no synergism was observed between the two radiations for the production of mutants resistant to either ouabain or 6-thioguanine. these experiments were designed to test whether x-rays induced an error-prone repair system that would increase the frequency of mutations produced by uv light, but no such system was detected. | 1978 | 740009 |
| modification of uv-induced mutation frequencies in chinese hamster cells by dose fractionation, cycloheximide and caffeine treatments. | chinese hamster (v79) cells were irradiated with a fractionated regime of ultraviolet light (uv1 + uv2). the fractionation of a uv dose always increased the colony-forming ability but reduced (or it did not change) the mutation frequencies. treatment with cycloheximide between the two uv irradiations resulted in two types of effects, depending on the protocols used. long exposures to cycloheximide (i.e., greater than 6 h) for the entire period between uv1 and uv2 or partial treatment of cyclohex ... | 1978 | 740008 |
| search for dna interchange corresponding to sister chromatid exchanges in chinese hamster ovary cells. | chinese hamster ovary cells (cho) grown for one cycle in bromodeoxyuridine (brdu) contain a small amount (0.5%) of unusually dense double stranded dna. this dense dna has been previously interpreted as being bifilarly substituted with brdu and hence evidence that sister chromatid exchange (sce) formation proceeds via the holliday model of recombination. however, the amount of this dense dna is 100 times greater than that expected based on the sce frequency in similarly cultured cho cells, and it ... | 1978 | 724509 |
| 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 |
| synthesis of poly(adenosine diphosphate ribose) in synchronized chinese hamster cells. | 1978 | 363436 | |
| cytoplasmic transfer of resistance to antimycin a in chinese hamster cells. | a mutant subline of v79 chinese hamster cells resistant to antimycin a (ant) was obtained by treatment with ethyl methanesulfonate followed by serial selection in ant-containing medium. clonal derivatives of the resistant line are less susceptible than parent cells to growth inhibition by ant in mass populations and show a higher plating efficiency in graded levels of inhibitor. resistance to ant is stable in drug-free medium and follows a pattern of incomplete dominance in hybrids between resis ... | 1978 | 281710 |
| amplified dihydrofolate reductase genes are localized to a homogeneously staining region of a single chromosome in a methotrexate-resistant chinese hamster ovary cell line. | methotrexate-resistant chinese hamster ovary cells selected for high resistance by progressive increments of methotrexate in the culture medium have levels of dihydrofolate reductase (tetrahydrofolate dehydrogenase, 7,8-dihydrofolate: nadp+ oxidoreductase, ec 1.5.1.3) 200 times that of sensitive cells and a corresponding increase in the number of copies of the dihydrofolate reductase gene. the resistant cells contain an expanded region on the second chromosome (homogeneously staining region) tha ... | 1978 | 281704 |
| mammalian cell mutant requiring cholesterol and unsaturated fatty acid for growth. | a mutant requiring both cholesterol and oleate for growth has been isolated from mutagenized chinese hamster ovary cells. by comparison with wild-type cells, sterol and unsaturated fatty acid biosynthetic activities in the mutant cells grown in fetal calf serum medium appear to be nearly intact. however, whole-cell radioactive acetate, mevalonate, dihydrolanosterol, and stearate incorporation studies show that sterol synthesis from acetate, lanosterol demethylation, and fatty acid desaturation a ... | 1978 | 281693 |
| cell killing and kinetic effects of diglycolaldehyde on dividing and nondividing mammalian cells in vitro. | the effects of the anticancer drug diglycolaldehyde (nsc-118994) were studied on chinese hamster ovary cells growing in vitro. dividing cells, specifically those in s-phase, were more sensitive to the drug than were nondividing cells, although a large fraction of nondividing cells was also killed by doses up to 800 microgram/ml. dose-dependent effects on cell progression kinetics were observed in all phases of the cell cycle except in mitosis, during which treated cells progressed at control rat ... | 1978 | 280715 |
| suppression of the frequencies of sister chromatid exchanges in bloom's syndrome fibroblasts by co-cultivation with chinese hamster cells. | the effect of co-cultivation of bloom's syndrome fibroblasts with chinese hamster ovary cells (cho) on the incidence of sister chromatid exchanges (sces) was studied. the results show that suppression of the frequency of sces in bloom's syndrome cells occurs only if cell to cell contact is present with cho cells, without any effect on the sce frequency in the latter. it is suggested that possible genetic heterogeneity between different bloom's syndrome patients can be studied using the method of ... | 1978 | 730162 |
| membrane lipid modification of chinese hamster ovary cells. thermal properties of membrane phospholipids. | 1978 | 701264 | |
| hybridization of cultured chinese hamster kupffer cells possessing quantitative differences in enzyme activities. | 1978 | 568558 | |
| role of adenine phosphoribosyltransferase in adenine uptake in wild-type and aprt- mutants of cho. | adenine uptake in cultured chinese hamster fibroblasts showed biphasic saturation kinetics. the transport system was highly specific for adenine and was competitively inhibited by adenosine. utilizing mutant clones of chinese hamster fibroblasts that have either reduced or negligible adenine phosphoribosyltransferase (aprt) activity, we found that (1) adenine was not accumulated against a concentration gradient in the absence of aprt activity and (2) after rapid initial uptake equal to that of t ... | 1978 | 743195 |
| bromodeoxyuridine-induced mutations in synchronous chinese hamster cells: temporal induction of 6-thioguanine and ouabain resistance during dna replication. | mutations were induced in synchronous chinese hamster cells by bromodeoxyuridine (budr) incorporated into cells for one-hour periods in the cell cycle. there was a very pronounced temporal dependence during the first half of the dna synthesis period for the induction of damage leading to 6-thioguanine (6tg) and ouabain resistance. no mutants above background were induced by exposure to budr in g1 and g2 cells, and very few mutants were induced in the latter part of the dna synthesis period. the ... | 1978 | 730050 |
| effect of caffeine on ultraviolet mutagenesis in v79 chinese hamster cells. | 1978 | 729970 | |
| protective effect of hyperthermia against the cytotoxicity of actinomycin d on chinese hamster cells. | hyperthermia is being tested as an adjuvant to chemotherapy for clinical use. we elected to study the interaction of heat at 43 degrees c with actinomycin d (amd) (0.5 microgram/ml) in tissue culture using plateau phase chinese hamster cells. the simultaneous administration of 43 degrees c and amd produces more than additive cytotoxicity if the duration of exposure is less than 30 minutes; however, this is quickly reversed with longer exposures with the cells developing resistance to further cyt ... | 1978 | 709551 |
| effects of cis-platinum(ii) diamminedichloride on survival and the rate of dna synthesis in synchronously growing chinese hamster v79-379a cells in the absence and presence of caffeine inhibited post-replication repair; evidence for an inducible repair mechanism. | the mechanism by which cis-platinum(ii)diamminedichloride, (cis-pt(ii)), inhibited dna synthesis was investigated using synchronously growing chinese hamster v79-379a cells. the progression of g1 phase treated cells into s phase was not inhibited. however the rate of dna synthesis throughout the s phase was depressed in a dose dependent manner compared to a control. the peak rate of dna synthesis was delayed and the duration of the s phase was extended resulting in a dose dependent delay in the ... | 1978 | 699192 |
| hyperthermic radiosensitization of synchronous chinese hamster cells: relationship between lethality and chromosomal aberrations. | 1978 | 569879 | |
| 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 |
| 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 |
| [chromosome aberrations and sister chromatid exchanges following exposure of cultured chinese hamster cells to ftorafur and 5-fluorouracil]. | 1978 | 363505 | |
| induction of ornithine decarboxylase activity in a temperature-sensitive cell cycle mutant of chinese hamster cells. | we have investigated the induction of ornithine decarboxylase (l-ornithine carboxy-lyase, ec 4.1.1.17) activity in a temperature-sensitive cell cycle mutant of chinese hamster fibroblasts. this activity is not induced at the nonpermissive temperature, although the synthesis of the majority of proteins is normal. from a combination of studies with inhibitors of mrna synthesis and maturation (alpha-amanitin, and cordycepin) and of proteins synthesis (cycloheximide, diphtheria toxin, and emetine), ... | 1978 | 283409 |
| measurements of dna damage in chinese hamster cells treated with equitoxic and equimutagenic doses of nitrosoureas. | the dna of v-79 chinese hamster cells was examined by alkaline elution following treatment of cultures with eight different nitrosoureas. drug incubations were performed under consistent biological conditions of equal toxicity and equal mutation induction at the hypoxanthineguanine phosphoribosyltransferase locus. the goals of this study were to determine whether dna damage could be detected in cells treated with biologically relevant doses of nitrosoureas and to determine whether the type and n ... | 1978 | 150942 |
| the induction of sister-chromatid exchanges in chinese hamster ovary cells by prolonged exposure to 2-acetylaminofluorene and s-9 mix. | 1978 | 714074 | |
| low molecular weight rnas hydrogen-bonded to nuclear and cytoplasmic poly(a)-terminated rna from cultured chinese hamster ovary cells. | a group of rnas 90--100 nucleotides long were isolated by melting them from poly(a)-terminated nuclear or cytoplasmic rna from cultured chinese hamster ovary cells. conditions that favor hydrogen bond formation allowed the reassociation of these low molecular weight rnas with poly(a)-terminated rna. the nuclear poly(a)-terminated molecules contained 1.3 moles of the low molecular weight rnas per mole of poly(a), while the cytoplasmic poly(a)-terminated rna contained only one seventh as much. the ... | 1978 | 699042 |
| a heavy particle comparative study. part iii: oer and rbe. | the results of a comparative study of heavy particles of interest in radiotherapy are reported in four parts. in this part iii, cell-survival measurements under aerobic and hypoxic conditions were made for various heavy particle beams. for heavy charged-particle beams, the measurements were made at the beam entrance (plateau), peak centre (10 cm wide peaks), and distal peak (1 cm from dose fall-off). chinese hamster cells (v79) were used. metabolic depletion was used to obtain hypoxia. the resul ... | 1978 | 698514 |
| diphtheria-toxin-resistant mutants of cho cells affected in protein synthesis: a novel phenotype. | stable mutants highly resistant to the protein-synthesis-inhibitor diphtheria toxin have been selected in chinese hamster ovary (cho) cells. protein synthesis in extracts of mutant cells is resistant to the inhibitory action of diphtheria toxin, indicating that the lesion has affected the protein-synthesis machinery. however, about 50% of the elongation factor-2 (ef-2) activity in the mutant cells can still be adp-ribosylated by diphtheria toxin, and this remaining ef-2 activity is similar to th ... | 1978 | 694729 |
| [relationship between dose rate and oxygen effect (author's transl)]. | chinese hamster cells were exposed to 60co gamma-rays using dose rates between 3.64 and 0,01 gy/min under euoxic or chronically hypoxic conditions of growth in order to clarify the relationship of the oxygen enhancement ratio (oer) to the dose rate. it turned out that the d0 of dose-effect curves from cells irradiated under euoxic conditions was increasing from 1.35 to 4.5 gy with decreasing dose rates, whereas the curves from cells irradiated under chronically hypoxic conditions were not much i ... | 1978 | 684787 |
| differences in the toxicity and metabolism of the 2-nitroimidazole misonidazole (ro-07-0582) in hela and chinese hamster ovary cells. | 1978 | 679180 | |
| 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 |
| a system for studying effects of microwaves on cells in culture. | an improved design of the fluid-filled waveguide-exposure chamber is described for studying effects of microwave radiation on cells in vitro. the system with a micropipette sample holder may be used as a prototype to isolate the apparent nonthermal factor of microwave radiation on cells in culture from those effects resulting from cell temperature rise. this system also allows more precise calibration of incident and absorbed microwave energies. compared with control, somatic cells of the chines ... | 1978 | 255162 |
| mutagenicity of thymidine to cultured chinese hamster cells. | 1978 | 566859 | |
| chinese hamster lung cell polysomes direct the synthesis of a single molecular weight species of procollagen alpha chains. | polysomes prepared from cultured chinese hamster lung cells direct the synthesis of procollagen alpha chains in an heterologous cell-free system containing the postribosomal supernatant fraction prepared from wheat germ. total protein synthesis requires both subcellular components and an exogenous energy source, and is inhibited by the antibiotics puromycin and aurin tricarboxylic acid. the ratio of collagenase-digestible to nondigestible material produced depends upon the wheat germ and not the ... | 1978 | 209044 |
| influence of ronidazole on chromosomes of the chinese hamster in vivo. | 1978 | 711063 | |
| mutation to ouabain-resistance in chinese hamster cells: induction by ethyl methanesulphonate and lack of induction by ionising radiation. | the spontaneous frequency of mutants resistant to growth inhibition by ouabain (ouar mutants) was found to be about 5:10(-5) per viable cell in uncloned cultures of chinese hamster v79-4 cells. in freshly-isolated clones or cultures started from a few cells this frequency was initially reduced to about 1.10(-6) in 1 mm ouabain. no increase in the frequency of ouar mutants was found in cultures treated with gamma-rays despite exploration of such variables as radiation dose, ouabain concentration, ... | 1978 | 692542 |
| evidence for functional hemizygosity at the emtr locus in cho cells through segregation analysis. | the hypothesis of functional hemizygostiy at the emetine-resistant (emtr, a non-x-linked recessive marker) locus in chinese hamster ovary (cho) cells has been examined by segregation analysis. the frequencies and the rates of segregation of the emtr and thgr (thioguanine-resistant, an x-linked recessive mutation) markers were determined from hybrids constructed between an emtr-thgr cho cell line and various other chinese hamster lines (v79, m3-1, cho, gm7s, chw and chl). thgr segregants were obt ... | 1978 | 688393 |
| induction and isolation of frameshift mutants in cultured chinese hamster don cells. | induction, isolation and characterization of frameshift mutants were studied by using a chinese hamster don (chd) cell line. icr-191, known to be a potent frameshift mutagen, was used for the induction of frameshift mutations. the drug (10(-5) m), as well as n-methyl-n'-nitro-n-nitrosoguanidine (mnng) and ethyl methanesulfonate (ems), increased significantly the frequency of forward mutations from 8-azaguanine (8-ag) sensitivity (8-ags) to resistance (8-agr) over the untreated control to an exte ... | 1978 | 672930 |
| effects of heat on the centrosomes of chinese hamster ovary cells. | chinese hamster ovary cells were heated either at 45.5 degrees for 15 min or at 42 degrees for 1 hr and then were either fixed immediately or allowed to recover at 37 degrees for intervals of up to 12 hr. in addition control cells and cells heated at 45.5 degrees for 15 min were immediately subjected to a cell fractionation procedure that yielded partially purified centrosome preparations. in 100% of the cells fixed and examined immediately after heating, the centrosomes were damaged. the osmiop ... | 1978 | 667824 |
| 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 |
| conjugation of methotrexate to poly(l-lysine) increases drug transport and overcomes drug resistance in cultured cells. | methotrexate and [(3)h]methotrexate were conjugated through a carbodiimide-catalyzed reaction to a 70,000 molecular weight poly(l-lysine) in molar ratios of approximately 13 to 1. the cellular uptake of labeled conjugate was far in excess of the uptake of free drug in cells that were either proficient or deficient in methotrexate transport. the conjugate markedly inhibited the growth of pro(-)3 mtx(rii) 5-3 chinese hamster ovary cells, which are known to be drug resistant by virtue of a deficien ... | 1978 | 279001 |
| messenger rna synthesis in synchronized chinese hamster ovary cells. | chinese hamster ovary cells were synchronized without inhibitors by mitotic selection and labelled in g1, s or g2 phase by incubation for 90 min with [3h]- or [14c]uridine. purified polyribosomes were extracted with phenol and the polyadenylated mrna prepared by poly(u)-sepharose chromatography. poly-adenylated [3h]uridine-labelled mrna from the g1 phase of the cell cycle was compared by exponential polyacrylamide gel electrophoresis in formamide with [14c] uridine-labelled polyadenylated nrna f ... | 1978 | 667072 |
| inhibitory effect of d-mannosamine on the growth of d-glucosamine-requiring mutant strain of chinese hamster lung cells. | 1978 | 669979 | |
| chinese hamster cell lines resistant to the cytotoxic action of fluoride. | the proliferation and efficiency of colony formation of a chinese hamster ovary cell line, cho, was found to be inhibited by concentrations of fluoride greater than or equal to 10(-3) m. from mutagenized populations of cho cells, clones were isolated that were from 1.6 to 13 times more resistant than the wild-type to the cytotoxic action of fluoride. the resistant clones were found to be stable in the absence of selection. the fluoride sensitivity of wild-type and fluoride resistant clones was n ... | 1978 | 657004 |
| cytological effects of microwave radiation in chinese hamster cells in vitro. | cytological effects were investigated in the chinese hamster cell line (cho-k1) exposed to microwave radiation of 2450 mhz frequency and incident power of 25 to 200 w for a period of 30 min. nuclear vacuoles, pycnotic and decondensed chromosomes were observed in cells exposed to 25 w under elevated temperature conditions (uncontrolled temp). in addition a significant increase in chromosomal breakages/cell was observed. cells exposed to relatively higher power, 75-200 w, under hypothermic conditi ... | 1978 | 657002 |
| chromosomal damage and mutations after exposure of chinese hamster cells to high concentrations of oxygen. | 1978 | 642965 | |
| 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 |
| cytogenetic study in spermatocytes of mice and chinese hamsters after treatment with isoniazid (inh). | meiotic chromosomes of spermatocytes from inh-treated male mice and chinese hamsters were analysed for chromosome aberrations in diakinesis-metaphase i and metaphase ii. the experiments were performed in two laboratories while a third laboratory participated in the chromosome evaluation. no enhancement of chromosome aberrations could be observed after acute treatment of early primary spermatocytes or chronic treatment of spermatogonia with inh. | 1978 | 649168 |
| sex- and line-dependent differences of renal alpha-galactosidase and beta-galactosidase activities in two highly inbred lines of chinese hamsters with spontaneous diabets. | 1978 | 202977 | |
| 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 |
| 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 |
| 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 |
| 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 |
| the effect of adriamycin on cell cycle progression and dna replication in chinese hamster ovary cells. | administration of[3h]aflatoxin b2 (2,3-dihydroaflatoxin b1)(afb2) to male rats resulted in levels of hepatic dna- and ribosomal (r)rna-aflatoxin adducts that were about 1% of those for rats given [3h]aflatoxin b1(afb1). the levels of hepatic protein-aflatoxin adducts were 35 to70% as great for afb2-treated as compared to afb1-treated rats... | 1977 | 830405 |
| chromosome replication in somatic hybrids of mouse and temperature sensitive chinese hamster cells. | 1977 | 833213 | |
| characterization of beta-d-n-acetylhexosaminidase isoenzymes in man-chinese hamster somatic cell hybrids. | a series of man-chinese hamster hybrids were investigated with the use of an anti-chinese hamster hexosaminidase serum, a specific anti-human hex a serum and an anti-human hex b serum. the expression of human hex a was found to be dependent on the presence of hex b. a heteropolymeric molecule is formed independently of hex b, which consists of chinese hamster and specific hex a moieties. it has an electrophoretic mobility nearly identical to hex a. a relationship between the absence and presence ... | 1977 | 835571 |
| th induction of thioguanine-resistant mutants of chinese hamster cells by gamma-rays. | the induction of mutation to purine analogue resistance was assessed in chinese hamster v79-4 cells exposed to gamma-radiation. after irradiation, the cells were grown in non-selective medium for different time intervals before respreading into medium containing 0.5-0.7 mug/ml thioguanine. in some experiments colonies arising in thioguanine-medium were counter-selected in medium containing the glutamine analogue azaserine, which distinguishes mutants with very little activity of the enzyme hypox ... | 1977 | 840237 |
| liver homogenate-mediated mutagenesis in chinese hamster v79 cells by polycyclic aromatic hydrocarbons and aflatoxins. | several chemical carcinogens that require metabolic activation have been examined for their cytotoxic and mutagenic activity in chinese hamster v79 cells. mutagenic activity was measured as the induced frequency of 6-thioguanine-resistant colonies. metabolic activation was provided by the 9000 g supernatant fraction of rat liver plus cofactors. the cytotoxicity and mutagenicity of aflatoxin b1 and b2, benzo(a)pyrene, 3-methylcholanthrene, 7,12-dimethylbenz(a)anthracene, dibenz(a,h)-anthracene, d ... | 1977 | 840239 |
| single strand breakage and repair in eukaryotic dna as assayed by s1 nuclease. | a sensitive new approach for measuring the repair of single strand breaks in dna induced by low doses of gamma irradiation was tested in cultured fibroblasts from chinese hamster lung, human afflicted with ataxia telangiectasia or fanconi's anemia and in normal cells of early and late passages. the assay is based on the increasing rate of strand separation of dna duplexes in alkali for molecules with increasing numbers of single strand scissions. dna strand separation is shown to follow the rela ... | 1977 | 840643 |
| study on cytological effects of carofur -- a new mutagen. | chinese hamster cells (line v-79) and human leukocytes in vitro and mice of the cba strain were treated with carofur (also called nifurprazinum), an antibacterial agent of pharmaceutical importance. at concentrations as low as 20 ppm, the in vitro treatments of cells of chinese hamster and human lymphocytes expressed chromosome aberrations, almost exclusively of deletion type. this effect resembles that of fluorodeoxyuridine but may not necessarily reflect the same basic mechanism involved. when ... | 1977 | 846486 |
| neutral amino acid transport systems of tissue culture cells. | we have studied the interactions among a varied group of neutral amino acids for uptake into two different animal tissue culture cell lines. 3t3 mouse cells and chinese hamster ovary cells were used in these studies. the results showed that the affinities of the amino acids clustered into two groups, one including amino acids such as glycine, alanine, and alpha-aminoisobutyric acid and the other group included amino acids such as leucine and phenylalanine. the specificities and properties of the ... | 1977 | 853037 |
| synthesis of newcastle disease virus polypeptides in a wheat germ cell-free system. | we have isolated 18s rna from cytoplasmic extracts of newcastle disease virus-infected chinese hamster ovary cells and tested its ability to direct protein synthesis in extracts derived from wheat germ. the products of the cell-free reaction directed by this rna contain polypeptides that comigrate with np, m,f, and 47k roteins from virions. in addition, the products contain a polypeptide (67k) that migrates on polyacrylamide gels slightly faster than the hn protein from virions. tryptic peptide ... | 1977 | 853567 |
| response of extremely hypoxic cells to hyperthermia: survival and oxygen enhancement ratios. | chinese hamster v79 cells and mouse emt6 cells were made extremely hypoxic with a chamber technique that relies upon gas exchange rather than respiration-assisted oxygen depletion. cells in these chambers were treated with heat (43degrees c) or heat plus x-irradiation, and colony-forming ability was determined. hyperthermia: (a) kills exponentially growing v79 cells more efficiently than plateau-phase cells; (b) kills euoxic and extremely hypoxic cells equally; and (c) radiosensitizes euoxic and ... | 1977 | 860045 |
| selective incorporation of l-3,4-dihydroxyphenylalanine by s-91 cloudman melanoma in vitro. | the incorporation of precursors of the biopigment melanin into melanotic and amelanotic s-91 cloudman melanoma, mouse fibroblast l-929, and chinese hamster ovary cells was studied. tyrosine did not selectively accumulate in pigmented cells compared to that in nonpigmented control cells. inhibition of protein synthesis with cycloheximide provided an estimate of the partition of tyrosine between protein (95%) and pigment biosynthesis (5%). l-3,4-dihydroxyphenylalanine, a more proximal precursor of ... | 1977 | 861938 |
| structural repeat units of chinese hamster ovary chromatin. evidence for variations in repeat unit dna size in higher eukaryotes. | dna lengths in the structural repeat units of chinese hamster ovary (cho) and chicken erythrocyte chromatin were compared by analyzing the sizes of dna fragments produced after treatment of nuclei with staphylococcal nuclease. the repeat length of cho chromatin (173 +- 4 bp) is about 20 base pairs (bp) smaller than that of chicken erythrocyte chromatin (194 +- 8 bp). repeat lengths of rat liver and calf thymus chromatin were found to be about 10 bp shorter than that of chicken erythrocyte chroma ... | 1977 | 866190 |
| the units of dna replication in the mammalian chromosomes: evidence for a large size of replication units. | the replication of chromosomal dna in human and chinese hamster cell populations has been studied by means of the dna fiber autoradiography. it was found that the rate of dna replication for one fork in human cells varies from 0.2 to 0.9 micron/min, the average being 0.6 micron/min. in the chinese hamster cells the rate dna replication is greater, varying from 0.3 to 1.2 micron/min, the average being 0.8 micron/min. there are no clusters containing a great number of replication units in human an ... | 1977 | 870295 |
| the metabolic activation of 7-methylbenz(a)anthracene: the induction of malignant transformation and mutation in mammalian cells by non-k-region dihydrodiols. | four different dihydrodiols derived from 7-methylbenz(a)anthracene have been tested, together with the parent hydrocarbon, for their ability to induce the in vitro malignant transformation of mouse m2 fibroblasts and mutations in v79 chinese hamster cells. in the transformation tests withe the non-k-region dihydrodiols, the 3,4-diol was the most active dihydrodiol tested and the 8,9-diol was also more active than 7-methylbenz(a)anthracene itself; the 1,2-diol showed only slight activity. the k-r ... | 1977 | 873646 |
| rapid assays for evaluating the drug sensitivity of tumor cells. | assays that assess the ability of cells to incorporate labeled precursors into acid-precipitable material in the presence of adriamycin, daunorubicin, puromycin, vinblastine, melphalan, or methotrexate were investigated as an approach to the detection of resistant cells in human tumor samples. each assay was evaluated with suitable drug-resistant chinese hamster ovary cell lines and normal human fibroblasts to determine whether the assays reflected the drug sensitivity of these lines. moreover, ... | 1977 | 875055 |
| reverse transformation of chinese hamster ovary cells by a factor produced by vibrio parahaemolyticus. | 1977 | 875243 | |
| pre-implantation embryos of chinese hamster. i. incidence of karyotype anomalies in 226 control embryos. | karyotyes were determined in 226 pre-implantation embryos (4--8-cell stages) of chinese hamster. the study was carried out under controlled natural breeding conditions, without superovulation and with the embryos developing in their mothers. a total of 5.3% karyotypically abnormal embryos were found. over half, 3.1%, were due to ploidy mutations, 5 cases of triploidy and 2 cases of haploidy. only 0.9% genome mutations were present, consisting of one autosomal trisomy and one autosomal monosomy. ... | 1977 | 876265 |
| l-dopa: selective toxicity for melanoma cells in vitro. | in a study of the effect of l-dopa, an intermediate in the biosynthesis of the pigment melanin, on the growth of human and murine melanoma cells a highly selective inhibition of growth was observed for pigmented cell lines (s91a and human melanoma) as compared to the nonpigmented control cells (amelanotic melanoma s91b, mouse fibroblast l929, and chinese hamster ovary). there was a correlation between toxicity and the extent of incorporation of radioactively labeled l-dopa by each line. | 1977 | 877570 |
| regional chromosomal localization of the human gene for galactose-1-phosphate uridyltransferase. | in the progeny of somatic cell hybrids formed by fusion of human lymphocytes and chinese hamster mutant cells, a single human chromosome a2 was selectively retained when grown in appropriate medium. spontaneous breakage of this chromosome in different hybrid subclones led to the assignment of the gene for galactose-1-phosphate uridyltransferase to the centromeric region of this chromosome (2q11 leads to 2q14). this gene is shown to be syntenic to the previously mapped genes for acid phosphatase ... | 1977 | 885547 |
| synteny between glycinamide ribonucleotide synthetase and superoxide dismutase (soluble). | the auxotrophic mutant ade -c derived from chinese hamster ovary cell cho-k1 lacks the enzyme glycinamide ribonucleotide synthetase and requires exogenous supplement of purines for growth. cells from this mutant were fused with normal human lymphocytes, and the resulting hybrids were isolated in purine-deficient medium. a total of 32 primary clones and 49 secondary clones were analyzed for various isozyme markers. cytogenetic analysis with chromosome banding was also performed in some hybrid clo ... | 1977 | 889603 |
| malignant transformation and mutagenesis in mammalian cells induced by vicinal diol-epoxides derived from benzo(a)pyrene. | benzo[a] pyrene and the syn- and anti-isomers of the 7,8-diol 9,10-oxide and of the 9,10-diol 7,8-oxide derived from this hydrocarbon have been tested for their abilities to induce malignant transformation in m2 mouse fibroblasts and mutagenesis in v79 chinese hamster cells. the anti-isomer of the 7,8-diol 9,10-oxide induced more mutations and transformation than did the other three vicinal diol-epoxides. the two 9,10-diol 7,8-oxides were moderately mutagenic but did not induce any transformatio ... | 1977 | 890685 |
| assignment of the gene for enolase to mouse chromosome 4 using somatic cell hybrids. | somatic cell hybrids between mouse peritoneal macrophages (mpm) and human fibrosarcoma cells (ht-1080) or chinese hamster cells (a3) were analyzed by starch-gel electrophoresis for the expression of murine enolase. data obtained indicate that the locus for enolase is on chromosome 4 in the mouse. | 1977 | 891258 |
| metabolic behaviour of nonhistone chromosomal proteins in proliferating and in resting fibroblasts. | the metabolism of nonhistone chromosomal proteins was studied in two lines of cells showing a different degree of contact inhibition: human diploid fibroblasts, which are easily contact-inhibited, and chinese hamster fibroblasts, which had been made to stop proliferating by fasting. by following the 3h414c ratio of [3h]tryptophan-labelled nonhistone chromosomal proteins and [14c]thymidine-labelled dna in chase experiments three main groups of these proteins could be detected with respect to thei ... | 1977 | 891550 |
| the deposition of 241am and 252cf in the skeleton of chinese hamster, syrian hamster and the rat. | 1977 | 893106 | |
| the pineal complex and its relationship to other epithalamic structures. | the pineal complex of rodents is made up of a pineal gland which developmentally always originates from the area between the habenular and posterior commissure and a pineal sac which is continuous with the choroid plexus of the third ventricle. at the light-microscopic level, this sac appears to be identical to the choroid plexus. the pineal sac abuts the deep and superficial pineal glands of the golden hamster. in the pet mouse, gerbil, kangaroo rat, and chinese hamster, the sac is contiguous w ... | 1977 | 899706 |
| two-step chromosomal control of tumorigenicity of chinese hamster cells in nude mice. | a simple method for microinjecting isolated chromosomes into a single living cell under an inverted microscope has been developed. of the 368 injected cells, 85 were able to form a colony and could be cloned. clones of chinese hamster v79 cells microinjected with chromosomes isolated from murine d56 cells [v79 (d56) cells] were tested for tumorigenicity in immunodeficient nude mice and for colony-forming ability in soft agar. untreated recipient v79 cells were highly tumorigenic and had a high c ... | 1977 | 914396 |