TitleAbstractYear(sorted ascending)
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 ...1978150942
the induction of sister-chromatid exchanges in chinese hamster ovary cells by prolonged exposure to 2-acetylaminofluorene and s-9 mix. 1978714074
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 ...1978699042
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 ...1978698514
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 ...1978694729
[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 ...1978684787
differences in the toxicity and metabolism of the 2-nitroimidazole misonidazole (ro-07-0582) in hela and chinese hamster ovary cells. 1978679180
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 ...1978567096
a system for studying effects of microwaves on cells in 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 ...1978255162
mutagenicity of thymidine to cultured chinese hamster cells. 1978566859
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 ...1978209044
influence of ronidazole on chromosomes of the chinese hamster in vivo. 1978711063
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, ...1978692542
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 ...1978688393
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 ...1978672930
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 ...1978667824
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 ...1978567652
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 ...1978279001
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 ...1978667072
responses of proliferating and non-proliferating chinese hamster cells to cytotoxic agents.the effects of various cytotoxic chemicals, as measured by viable cell counts, colony-forming ability and proliferative capacity, have been studied using chinese hamster cells in exponential and plateau (stationary) phases of growth. the proliferating cells were altogether more sensitive to the action of the drugs than non-proliferating cells. however, imuran (azathioprine) a purine antimetabolite, was more effective against the plateau-phase cells. the observed response of cells to imuran could ...1978638016
the aggregation of chinese hamster cells. aggregate size distributions and temperature dependence. 1978631210
the distribution of moderately repeated dna sequences among chinese hamster chromosomes. 1978631209
cytological effects of 1-(2-nitro-1-imidazolyl)-3-methoxy-2-propanol (misonidazole) on hypoxic mammalian cells in vitro.hypoxic chinese hamster v-79 cells were examined for light-microscope morphology, progression through the cell cycle, chromosomal aberrations, and viability, after incubation with the 2-nitroimidazole, misonidazole [1-(2-nitro-1-imidazolyl)-3 methoxy-2-propanol]. cytological examination of cells up to 42 hr after incubation with the drug at 37 degrees indicated that increasing contact time and increasing drug concentrations interfered with cell attachment and progressively slowed cell progressio ...1978626969
induction of thermotolerance in chinese hamster ovary cells by high (45 degrees) or low (40 degrees) hyperthermia. 1978626962
mutagenicity of heterocyclic nitrogen mustards (icr compounds) in cultured mammalian cells.the mutagenicity of six heterocylic nitrogen mustards (icr compounds) has been determined in a cultured mammalian cell system by use of resistance to the purine analog 6-thioguanine to select for mutation induction at the hypoxanthine-guanine phosphoribosyltransferase locus in chinese hamster ovary cells. the six compounds tested are icr 191, 170, 292, 372, 191-oh, and 170-oh. the first four contain a single 2-chloroethyl group (nitrogen half-mustard) on the side chain and are mutagenic, with th ...1978626955
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 ...1978621224
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 ...1978566474
the selection of wild-type revertants from methotrexate permeability 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 ...1978566473
long-term culture of chinese hamster kupffer cell lines isolated by a primary cloning step. 1978564778
reduction of beta-galactosidase in the ketotic chinese hamster kidney.kidneys from normal, diabetic-nonketotic and ketotic chinese hamsters were homogenized, fractionated and assayed for beta-glucosidase, and beta-galactosidase activities. the kidneys of the ketotic animals were enlarged but the protein content in each subcellular fraction was similar in all three groups of animals. beta-glucosidase was found chiefly in the soluble fraction and no difference was observed in these animals. beta-galactosidase was distributed in both cytoplasmic and particulate fract ...1978417989
preparation and identification of partially fractionated chinese hamster chromosomes. 1978344049
defective regulation of cholesterol biosynthesis and plasma membrane fluidity in a chinese hamster ovary cell mutant.a chinese hamster ovary cell mutant resistant to killing by 25-hydroxycholesterol is shown to be defective in the regulation of cholesterol synthesis by exogenous cholesterol. when grown with various cholesterol supplements in delipidized serum, the mutant cell exhibits a variation in cholesterol content and plasma membrane fluidity that is not observed in the parental cell type.1978274716
histone phosphorylation and chromatin structure during mitosis in chinese hamster cells. 1978206429
the effect of bleomycin and its combined effect with radiation on cultured chinese hamster cells v-79. 197875797
toxicity, radiation sensitivity modification, and metabolic effects of dehydroascorbate and ascorbate in mammalian cells.dehydroascorbate, an electron affinic metabolite of vitamin c, sensitized ehrlich ascites tumor cells, in vivo, to radiation and was selectively toxic to v79 chinese hamster lung cells under hypoxic conditions (without radiation). the radiosensitization may involve both the electron affinic nature of dehydroascorbate as well as its ability to oxidize the intracellular nad(p)h and non-protein sulfhydryl. dehydroascorbate's oxidation of nad(p)h required higher concentrations than other sulfhydryl ...197823385
action of heparin on mammalian nuclei. ii. cell-cycle-specific changes in chromatin organization correlate temporally with histone h1 phosphorylation.the interaction of the polyanion heparin with the inner histones of chromatin has been used to detect changes in chromatin organization associated with cell-cycle traverse. synchronized populations of chinese hamster cells were obtained either in early g1 or near the g1/s boundary. the rate of interaction of heparin with chromatin-associated inner histones was measured using nuclei isolated from synchronized cell populations in different phases of the cell cycle. a g1-specific decrease in rate o ...1978626747
acid glycohydrolase in chinese hamster with spontaneous diabetes ii. n-acetyl-beta-d-hexosaminidase in plasma and tissues.excessively high activity of n-acetyl-beta-d-hexosaminidase (2-acetamido-2-deoxy-beta-d-glucoside acetamidodeoxy-glucohydrolase, ec was found in the plasma of hereditary diabetic xa line animals, which however showed similar activity of this enzyme in both 12 00 x g supernatant and precipitate fractions of kidney homogenates as the nondiabetic m line animals. 0.1% triton x-100 extracts of kidney, spleen, hind leg muscle, cheek pouch and spinal cord of xa and m line animals also showed ...1978623771
alcohol dehydrogenase mutants of chinese hamster somatic cells resistant to allyl alcohol.alcohol dehydrogenase (alcohol: nad oxidoreductase, e.c. mutants of chinese hamster somatic cells were isolated as resistant to allyl alcohol (allr). the allr phenotypes of the mutant clones were reproducible with high fidelity and stable over long intervals of growth in the absence of the selecting drug. several mutants, adh-1, adh-2, adh-9 and adh-13, resistant to allyl alcohol were characterized. they have between 15 and 40% of the alcohol dehydrogenase activity of the wild-type cel ...1978640376
[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 ...1978565630
effects of hyperthermia on survival and progression of chinese hamster ovary cells. 1978563767
the radiation response of cultured mammalian v79-s171 cells exposed to a wide concentration range of sulphate salt solutions.the radiation response of chinese hamster cells (v79) exposed to a wide concentration range of li2so4, na2so4 or k2so4 has been examined and compared with the radiation response of cells treated in an identical manner with licl, nacl, or kcl solutions. at hypotonic salt concentrations, cells were radiosensitized by both the chloride and sulphate salts. at high salt concentrations, approximately greater than 0.9 m, a radioprotective effect was observed with both chloride and sulphate salts. at in ...1978305425
studies with bleomycin and misonidazole on aerated and hypoxic cells.bleomycin is a chemotherapuetic drug used primarily in the treatment of squamous-cell carcinoma, while misonidazole is an effective radiosensitizer and potent cytotoxic agent selectively affecting hypoxic cells. v79 chinese hamster cells were used to investigate the cytotoxicity of bleomycin (blm) under aerated and hypoxic conditions as a function of drug concentration. at a lowered temperature of 17.5 degrees c, or at an elevated temperature of 42.5 degrees c, hypoxic cells are more sensitive t ...197875740
heterogeneity in chinese hamster ribosomal dna.a discrete heterogeneity has been detected in chinese hamster ribosomal dna after eco r1 digestion of total dna followed by a southern transfer and hybridization with [125i]18s or [125i]28s ribosomal rna. digestion with eco r1 produces three fragments, 4.3, 6.0 and 9.5 x 10(6) daltons respectively, which hybridize with 18s rna. the smallest fragment also hybridizes with 28s rna. either length heterogeneity or sequence heterogeneity (i.e. presence of an additional eco r1 site in some of the rdna ...1978624239
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 ...1978618867
cyclic amp levels and types i and ii cyclic amp-dependent protein kinase activity in synchronized cells and in quiescent cultures stimulated to proliferate.cyclic amp as well as the specific activity of cyclic amp-dependent protein kinase decreased from the first two hours after chinese hamster ovary cells in plateau phase were stimulated to proliferate by tripsinization of confluent cultures and dilution in fresh media. from two to five hours after this stimulation, the cyclic amp level and the specific activity of cyclic amp-dependent protein kinase increased two-fold. there was a 40--50% increase in the degree of activation of cyclic amp-depende ...1978202331
[cytotoxicity test on medical drugs--chromosome aberration tests with chinese hamster cells in vitro (author's transl)]. 1978750044
plasma membrane proteins and glycoproteins from chinese hamster cells sensitive and resistant to actinomycin d.plasma membrane proteins and glycoproteins have been isolated from chinese hamster cells of the spontaneously transformed dc-3f parental cell line and the dc-3f/ad x line with a high level of acquired resistance to actinomycin d. plasma membrane preparations from both cell lines band at 1.16 g/ml after isopycnic centrifugation. we present evidence to indicate differences in the leucylpeptide backbones of the antibiotic-sensitive cells and the drug-resistant dc-3f/ad x cells. in addition, there a ...1978748679
lipopolysaccharide effects on sensitive and resistant variant chinese hamster ovary cell lines.chinese hamster ovary (cho . k1 . pro) cell growth was inhibited by addition of a gram-negative bacterial lipopolysaccharide (lps) to the cell culture medium. growth inhibition began after three or four days of incubation, was dose-dependent up to a maximum at an lps concentration of 500 microgram/ml and was accompanied by cell shape changes and enhanced cytoplasmic vacuolization. formation of bizarre cho . k1 . pro cell shapes and vacuole formation were most pronounced after seven days of incub ...1978748676
unusually thick filaments in intrafusal muscle fibers of the chinese hamster. 1978744920
organization of mammalian chromosomal dna: supercoiled and folded circular dna subunits from interphase cell nuclei.chinese hamster cells (line v79/4) in the g2 phase of the mitotic cycle were lysed onto neutral sucrose gradients and the released chromosomal dna was characterized according to its size and shape by sedimentation velocity studies. using the intercalating agent, ethidium bromide, in the gradients and the induction of dna single- and double-strand breaks by irradiation, the dna was proved to be released into the gradient in supercoiled circular subunits whose homogenous size corresponds to 2.8 . ...1978735613
growth retardation in chinese hamster v-79 cells exposed to 1 mhz ultrasound. 1978734793
studies of the diphtheria toxin receptor on chinese hamster cells.concanavalin a, wheat germ agglutinin and the ovalbumin glycopeptide are all inhibitors of the cytotoxic effect of diphtheria toxin on chinese hamster cells. ovalbumin glycopeptide loses its inhibitory property after treatment with beta-n-acetylglucosaminidase. this demonstrates the importance of the glycopeptide structure for the mechanism of inhibition. the glycopeptide may be a toxin cell-surface receptor analogue. diphtheria toxin-resistant mutants were isolated in order to search for cells ...1978732311
effect of weak magnetic fields on growth of cells in tissue culture.normal chinese hamster v79 cells were grown in vitro for more than one year in a magnetic field of 10(-7) tesla to test recently hypothesized effects of weak magnetic fields on biological systems. no significant difference was observed between growth rate in such fields and that in the ambient geomagnetic field.1978724808
use of a chinese hamster ovary cell line with a temperature sensitive defect in cytoplasmic protein synthesis to examine protein synthesis associated with cell nuclei. 1978710698
characterization of sister chromatid exchange induction by 8-methoxypsoralen plus near uv light.the combination of 8-methoxypsoralen and near uv light is highly effective in inducing sister chromatid exchanges (sces) in chinese hamster ovary cells. appreciable increases in sces can be effected by treatments compatible with cell survival, and effects of a single dose of alkylation persist over multiple generations. both the frequency and location of sces induced at different times within the dna synthesis period varies in a manner indicating that exchange induction is restricted to regions ...1978668416
biological toxicity of auger emitters: molecular fragmentation versus electron irradiation.two hypotheses have been advanced to explain the extreme biological toxicity of dna associated 125i: (a) high local concentrations of radiation energy from low energy auger electron; (b) charge-induced molecular fragmentations in the dna. to distinguish between these two hypotheses an attempt was made to evaluate the molecular events associated with electron capture decay, to calculate the microdistribution of radiation energy after 125i decay, and to relate the microdosimetry data to the biolog ...1978639556
mutants of cho cells resistant to the protein synthesis inhibitor emetine: genetic and biochemical characterization of second-step mutants.second-step mutants highly resistant to the protein synthesis inhibitor emetine (emt(rii) have been selected from emetine resistant (emt(ri)) chinese hamster ovary cells described earlier. the frequency of the emt(rii) mutants was increased 50- to 75-fold after mutagenesis, and none of these highly resistant mutants could be selected in one step using wild-type cells. like the emt(ri) mutants, the increased resistance of emt(rii) mutants results from another lesion in the polyribosomal fraction, ...1978628886
six complementation classes of conditionally lethal protein synthesis mutants of cho cells selected by 3h-amino acid.using a tritiated amino acid suicide procedure designed specifically to select conditional protein synthesis mutants, we have isolated and characterized a large number of such mutants of chinese hamster ovary cells. all of the mutants are genetically stable and behave as recessives in somatic cell hybrids. most of the new mutants are phenotypically dependent on the concentration of a specific amino acid as well as on temperature. in addition to identifying many additional leucyl- and asparagyl-t ...1978628883
comparative effects of adenine analogs upon metabolic cooperation between chinese hamster cells with different levels of adenine phosphoribosyltransferase activity. 1978622085
alpha-amanithin-resistant mutants of chinese hamster ovary (cho) cells.spontaneous and ems-induced alpha-amanitin-resistant cho cells have been isolated and characterized. dna-dependent rna polymerase ii in cell-free extracts from a mutant (arm-1) was partially resistant to alpha-amanitin. growing mutants for several generations in the presence or absence of alpha-amanitin did not change the pattern of inhibition. the mutants grew with a lag following transfer to medium with or without alpha-amanitin. the mutants have an altered rna polymerase ii, and possibly an a ...1978622084
a possible difference in the mechanism of replication of moderately repeated nucleotide sequences in chinese hamster ovary cells. 1978620691
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 ...1978618896
[repair of dna--protein cross-links in a culture of chinese hamster cells. possible molecular mechanisms]. 1978569570
[phenomenon of premature chromatin condensation following fusion of chinese hamster cells using polyethyleneglycol]. 1978567115
[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 ...1978567074
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 ...1978565274
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.1978565273
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 ...1978565272
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 ...1978565271
the in vivo induction of sister chromatid exchanges in the bone marrow of the chinese hamster. ii.n-nitrosodiethylamine (den) and n-isopropyl-alpha-(2-methyl-hydrazino)-p-toluamide (natulan), two carcinogenic compounds with specific mutagenicity problems.n-nitrosodiethylamine (den) and n-isopropyl-alpha-(2-methylhyadrazino)-p-toluamide (natulan) were examined with the in vivo sce method of vogel and bauknecht. only natulan showed a positive effect with a significant increase of induced sce between 10 and 25 mg/kg b.w. the six-point curve of the dose effect was of the plateau type. with den only a slight increase with high doses could be obtained, which was not significant when 50 or 100 cells were counted. compared with the results of other test ...1978342947
the effects of ultra-high dose rates on survival and sublethal repair in chinese-hamster cells. 1978304852
lethality in mammalian cells due to hyperthermia under oxic and hypoxic conditions.from several studies of hyperthermia there have been reports that hypoxic cells are more sensitive to heat than their oxic counterparts. experimental techniques in this investigation eliminate the effect of ph, trypsinization and cell attachment, when assaying the effects of hyperthermia on cells. under hypoxic conditions, hela s3 and chinese hamster cell-lines do not have an increased sensitivity to heat compared with oxic cells. hela s3 cells are protected against heat by hypoxia. light-micros ...1978304850
difference in renal alpha-galactosidase levels in male and female chinese hamsters (cricetulus griseus).1. the activity of alpha-galactosidase was found to be significantly higher in the kidney of female than that of male chinese hamsters in a highly inbred colony but its activity in liver, heart and spleen remained similar between female and male animals. 2. partially purified renal alpha-galactosidase by sequential column chromatography on sepharose 6b and deae-sepharose cl-6b showed identical elution profiles, ph optima (4.5), kms (4.4 mm) and heat-inactivation curves between enzymes of male an ...1978233797
the role of butyrate in the reverse transformation reaction in mammalian cells.the reverse transformation reaction of chinese hamster ovary cells from compact, epithelial-like, randomly growing, heavily knobbed, lectin reactive cells into stretched, tighly adherent, smooth-surfaced, lectin resistant, fibroblast-like cells normally elicited by dibutyryl camp can be produced to its complete extent by n6-monobutyryl camp or 8-bromo-camp, o2'-monobutyryl camp is ineffective as is camp itself in the absence of an inhibitor of phosphodiesterase activity. in the presence of a pho ...1978201654
sexually differentiated activity and isozymes of renal beta-galactosidase in the chinese hamster. 197830661
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 ...1978567683
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.1978649168
sex- and line-dependent differences of renal alpha-galactosidase and beta-galactosidase activities in two highly inbred lines of chinese hamsters with spontaneous diabets. 1978202977
organ-specific mutations in chinese hamsters induced by chemical carcinogens. 1979293496
possible mutagenic activity of saccharin.a mutagenic effect of saccharin in chinese hamsters, using the in vivo sce test, was observed when massive overdoses were administered; cyclamate was not mutagenic.1979499424
proliferation of lung and airway cells induced by nitrogen dioxide.proliferation of lung cells of chinese hamsters was examined in several regions of the lung parenchyma and ciliated airway epithelium after a 24-h exposure to 28.2 mg/m3 (15 ppm) nitrogen dioxide (no2). label was retained 3 wk after the injection of [3h]thymidine, and autoradiographic methods were used to localize the site of retention. by 24 h after administration of [3h]thymidine, parenchymal areas, exclusive of airways, showed an increased labeling index, indicative of cell death and replacem ...1979513156
effect of continuous low-dose insulin treatment on subsequent incidence of diabetes in genetically prediabetic chinese an attempt to prevent the onset of diabetes, young, genetically prediabetic (but not yet hyperglycemic) chinese hamsters were treated continuously with insulin via minipump for 4 wk beginning 1 wk before the predicted age of onset of glucosuria (age 7 wk). continuous insulin infusion which increased the plasma insulin levels by 70%, did not cause hypoglycemia, nor did it reduce the incidence or severity of diabetic symptoms over the ensuing year of observation. in fact, early treatment with e ...1979446913
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 ...1979572551
the effect of lucanthone on the radiation response of intestinal stem cells in chinese hamsters.crypt microcolony assay was used to determine the effect of lucanthone on the radiation response of intestinal stem cells in chinese hamsters . the dq of the crypt microcolony radiation--survival curve was maximally reduced by 205 rads when lucanthone injection preceded irradiation by 10 hours and was reduced by 140 rads when injection followed irradiation by 5 hours. on simultaneous injection and irradiation, dq was reduced by only 20 rads; when injection and irradiation were separated by appro ...1979760168
absence of povidone-iodine-induced mutagenicity in mice and hamsters.povidone-iodine usp was tested for mutagenicity in mice by the dominant lethal assay or micronucleus test and in chinese hamsters by the bone marrow test. none of the three tests revealed any evidence of mutagenic effect.1979758440
[an assessement of the in vivo sister chromatid exchange (sce)-test using various cytostatics (author's transl)].five cytostatics of different chemical structure and pharmacological action were used on chinese hamsters (bone marrow cells) to test the efficiency and validity of the in vivo sister chromatid exchange (sce)-test as an indicator of mutagenicity. these model substances, all of which had previously shown a mutagenic effect in one or the other of the various in vivo test systems, gave positive results in this test, too, with the exception of bleomycin. on the basis of the lowest effective dose and ...1979546426
mutagenicity of polycyclic hydrocarbons iii. monitoring genetic hazards of benz(a)anthracene.mutagenicity tests (micronucleus test and chromosome aberrations) have been performed with benz (a) anthracene in spermatogonia and bond marrow cells of chinese hamsters and in nmri mice oocytes. mutagenic effects of the polycyclic hydrocarbon could be demonstrated.1979532719
the influence of ethanol treatment of cytogenetic effects in bone marrow cells of chinese hamsters by cyclophosphamide, aflatoxin b1 and patulin.chromosomes were investigated from the bone marrow of chinese hamsters which received 10% (v/v) ethanol as the only liquid supply for a period of 9 weeks. at the end of the ethanol drinking period 1 group of animals received 2 oral doses of 80 mg/kg cyclophosphamide (cp), a second group received 2 oral doses of 25 mg/kg aflatoxin b1 (afb1), a third group 2 oral doses of 20 mg/kg patulin (pa). the 2 applications were separated by 24 h. the intake of ethanol had no effect on the bone marrow chromo ...1979473226
effect of diet limitation on development of diabetes in non-hyperphagic prediabetic chinese hamsters. 1979386727
organotropic mutagenesis in tissues of chinese hamsters induced by chemical order to investigate the relationship between mutation and carcinogenesis in vivo, a method has been developed in which somatic mutation can be studied in specific organs of chinese hamsters after acute dosing with chemical carcinogens. in preliminary experiments an increase in mutation was detected in cultures derived from lung tissue of hamsters after intraperitoneal dosing with the direct-acting mutagen and weak carcinogen, ethyl methanesulphonate, or with diethylnitrosamine, a carcinogen ...1979223525
mutations of chinese hamster somatic cells from 2-deoxygalactose sensitivity to chinese hamster somatic cells, the spontaneous change of phenotype from 2-deoxygalactose sensitivity to resistance was studied using fluctuation test experiments à la luria and delbrück (1943) for four chinese hamster cell strains derived from v79. the results are consistent with true mutational events. the mutation rates are in the range of 1 to 3.5 x 10(-5) per cell per generation. the relationship between the 2-deoxyglactose resistance and the galactokinase markers is discussed.1979488705
oer and rbe for negative pion beams of different peak widths.experimental data on survival curves for pion because of different peak widths under aerobic and hypoxic conditions are reported. metabolic depletion of oxygen by the chinese hamster cells (line v79) was used to obtain hypoxia. the results indicate that the rbe at the beam entrance (plateau) is approximately 1.0. when the bragg peaks were broadened to widths of 1.3, 7.8, and 10.5 cm (at the 80% dose level), the rbe (50% cell survival) at the peak centres was 1.7, 1.6, and 1.2, respectively. the ...1979465928
[pathology of mitosis after cellular recovery from a metaphase block].the experiments in chinese hamster fibroblast-like cells have shown that the c-mitosis inducing agents (colchicine, colcemid and low temperature) produce evident stathmokinetic and radiomimetic effects. by the reversibility moment of the former the latter becomes apparent, manifesting in bridge accumulation. this form of pathology is likely to be caused by the disturbance of the cellular nucleoprotein metabolism in c-mitosis.1979465693
the metabolically mediated dna damage and subsequent dna repair by 4-chlorobiphenyl in chinese hamster ovary cells.the metabolism of [3h]-4-chlorobiphenyl (cb) by chinese hamster ovary cell cultures resulted in the formation of lipophilic hydroxylated metabolites, trichloroacetic acid soluble conjugates and covalent macromolecular adducts. the major lipophilic metabolite was chromatographically similar to 4'-chloro-4-biphenylol. the intracellular macromolecules were fractionated into protein, rna and dna. although protein was the major target of covalent interaction with [3h]-cb and contributes 85% of the ma ...1979451338
nuclear protein synthesis at permissive and non-permissive temperatures in a chinese hamster ovary cell line with a temperature-sensitive defect in cytoplasmic non-mitochondrial protein synthesis. 1979446528
effects of hyperthermia (41.5 degrees) on chinese hamster ovary cells analyzed in motisis.the mitotic cells from an asynchronous population of chinese hamster ovary cells exposed to 41.5 degrees for 7 hr were examined by light and electron microscopy to determine if there were any morphological abnormalities related to cell death or lengthening of metaphase induced by hyperthermia. all components of the mitotic apparatus were formed during exposure to heat, and the mitotic apparatus was functional as demonstrated by eventual cell division. however, heat caused the nuclear envelope to ...1979445391
interaction between radiation and drug damage in mammalian cells. iii. the effect of adriamycin and actinomycin-d on the repair of potentially lethal radiation damage.we have studied the effects of actinomycin-d (amd) and adriamycin (adrm) on the repair of radiation damage in chinese hamster cells (v79) in plateau phase growth. suppression of potentially lethal damage repair (pldr) was observed in the presence of non-toxic levels of amd and minimally toxic levels of adrm. the suppression of pldr by amd persisted as long as the drug was present. removal of amd was followed by prompt repair of potentially lethal injury suggesting that suppression of pldr by amd ...1979314429
rescue of marker phenotypes: effects of budr sensitization, hypoxia and high let.the survival curve of colony-forming ability of chinese hamster wg3h cells has been compared with the dose-response curve for the expression of an active thymidine kinase (tk) gene from these cells. the tk+ phenotype was measured by hybrid colony formation after fusion of wg3h (tk+) cells with chinese hamster a23 (tk-) cells. the tk+ survival data fitted a multi-target curve up to 3 krad of 137 cs irradiation, when a highly resistant fraction of hybrid colonies was seen at about 1 per cent survi ...1979314426
relationship between histidyl-trna level and protein synthesis rate in wild-type and mutant chinese hamster ovary cells.a preliminary investigation was carried out to determine how conditional lethal mutants affected in particular aminoacyl-trna synthetases may be used to study the role of trna charging levels in protein synthesis. the relationship between rate of protein synthesis and level of histidyl-trna in wild-type cultured chinese hamster ovary cells was determined using the analogue histidinol to inhibit histidyl-trna synthetase activity. this response was compared with that obtained using a mutant strain ...1979256567
the induction of sister chromatid exchanges by dihydrodiols derived from 7,12-dimethylbenz[a]anthracene and 3-methylcholanthrene.the in vitro induction of sister chromatid exchanges (sces) in chinese hamster ovary (cho) cells by the polycyclic hydrocarbons, 7,12-dimethylbena[a]anthracene and 3-methylcholanthrene and some of the related dihydrodiols was investigated. increased numbers of sces were seen in the chromosomes of cells exposed to non-k-region dihydrodiols. the most active compounds were the 3,4-dihydrodiol of 7,12-dimethylbenza[a]anthracene and the 7,8- and 9,10-dihydrodiols of 3-methylcholanthrene: the parent h ...1979110440
Displaying items 1701 - 1800 of 26566