Publications
| Title | Abstract | Year(sorted descending) Filter | PMID Filter |
|---|
| 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 |
| isolation and characterization of amphotericin b-resistant cell lines in chinese hamster cells. | amphotericin b is a polyene macrolide antibiotic which interacts specifically with sterols in mammalian cell membranes. amphotericin b-resistant (ambr) lines of stable phenotype have been isolated from cultured chinese hamster (v79) cells. three ambr clones (ambr-1, -2 and -3) isolated independently after treatment with nitrosoguanidine were resistant to greater than or equal to microgram/ml of the antibiotic, while dna synthesis as well as the colony-forming ability of the parental v79 cells wa ... | 1978 | 667948 |
| dose-rate effects of ethyl methanesulfonate on survival and mutation induction in cultured chinese hamster cells. | the dose-rate effects of ethyl methanesulfonate (ems) on the survival and induction of mutations in chinese hamster don cells were investigated. the most effective time of exposure to ems for reducing the surviving fraction of cells was 4 h, shorter and longer exposure times being less effective. the threshold or minimal concentration of ems giving a surviving fraction of 0.5 was 0.05 mg/ml. the minimal effective time of exposure to ems for cell death was 1 h. corrected survival curves showed th ... | 1978 | 209325 |
| characterization of ultraviolet light-induced ouabain-resistant mutations in chinese hamster cells. | ouabain-resistant mutations in chinese hamster cells have been quantitatively characterized. the mutation frequencies were found to be induced curvilinearly with treatments of increasing doses of ultraviolet light (uv). for the range of uv doses tested (5--20 j/m(2)), the observed frequency, y, as a function of uv dose x, follows a curvilinear function, y = (-28 + 13.37 x--1.52x(2) + 0.08x(3)) . 10(-6). the frequencies of uv-induced mutations were directly correlated with cell survival, indicati ... | 1978 | 149923 |
| [repair of dna--protein cross-links in cultivated chinese hamster cells]. | 1978 | 567116 | |
| altered aminoacyl-trna synthetase complexes in g1-arrested chinese hamster ovary cells. | aminoacyl-trna synthetase complexes existing in chinese hamster ovary (cho) cells were shown to undergo alterations as a function of the growth state of the cell. the distribution pattern for 13 particulate postribosomal aminoacyl-trna synthetases in 10-30% (w/v) exponential sucrose gradients was determined for the enzymes from cho cells as they exist under three different culture conditions: exponential growth, g1 arrest induced by isoleucine deficiency, and g1 arrest induced by leucine deficie ... | 1978 | 678523 |
| an in vitro analysis of the dominance of emetine sensitivity in chinese hamster ovary cell hybrids. | the behavior of ribosomes derived from emtr x emts hybrid cells in in vitro protein synthesis is similar to that observed with a 1:1 mixture of ribosomes from emtr and emts cells. when mrna (bm virus rna) is present in limiting amounts (rna/ribosome molar ratio = 0.1), protein synthesis in either mixture is sensitive to emetine. in contrast, when mrna is present in excess (rna/ribosome molar ratio = 2), the emetine resistant as well as the sensitive components are both expressed in the mixtures. ... | 1978 | 649617 |
| sister chromatid exchange induced by promutagens/carcinogens in chinese hamster cells cultured in diffusion chambers in mice. | 1978 | 674231 | |
| the symmetry of radiation-induced chromatid exchanges in relation to the cell cycle in chinese hamster cells in vivo and in vitro. | the symmetry of radiation-induced chromatid exchanges was studied in relation to the cell cycle in chinese hamster cells in vivo and in vitro. both in vivo and in vitro, the ratio between symmetrical and asymmetrical chromatid exchanges was about 1 to 1 during g2 and s phase of the cell cycle. | 1978 | 672920 |
| enrichment and visualization of small replication units from cultured mammalian cells. | dna from cultured chinese hamster cells has been fractionated to yield a population of dna enriched for replicating molecules. molecules containing replication structures were analyzed by electron microscopy, and replicon size was estimated. the enrichment procedure takes advantage of single-stranded regions characteristic of replicating molecules, and the greater affinity of mercuric ion for single-stranded rather than native dna. after interaction with low concentrations of hgcl2, dna with bou ... | 1978 | 567225 |
| induction of sister-chromatid exchanges in chinese hamster ovary cells treated in vitro with non-k-region dihydrodiols of 7-methylbenz[a]anthracene and benzo[a]pyrene. | studies were carried out on the incidence of sister-chromatid exchanges induced in chinese hamster ovary cells by in vitro treatment with the polycyclic aromatic hydrocarbons 7-methylbenz[a]anthracene and benzo[a]pyrene and with related k-region and non-k-region dihydrodiols. appreciable increased in the incidence of sister-chromatid exchanges were apparent in cells treated with non-k-region dihydrodiols: the most active compounds were 3,4-dihydro-3,4-dihydroxy-7-methylbenz[a]anthracene and 7,8- ... | 1978 | 566850 |
| inverted repeated dna from chinese hamster ovary cells studied with cloned dna fragments. | fragments from the dna of chinese hamster ovary cells produced by restriction endonuclease ecori were cloned in charon 16a lambda bacteriophage and examined for the ability to hybridize in situ with 32p-labeled double-stranded regions from heterogeneous nuclear rna (hnrna). of 235 clones tested, 87 (37%) contained sequences that hybridized with the double-stranded hnrna. nine of these were examined for the presence of inverted repeat dna structures (ir-dna) by electron microscopy. all nine conta ... | 1978 | 275835 |
| evidence for structural gene alterations affecting aminoacyl-trna synthetases in cho cell mutants and revertants. | aminoacyl-trna synthetase (aars) activities in extracts of mutant strains of the chinese hamster ovary line (cho) were examined for alterations in thermal stability. mutants having low activity for metrs, asnrs, or glnrs contained aarss that were inactivated much more rapidly upon heating than those from wild-type cells. revertant lines, isolated from cultures of these mutants (asn-5, met-2, and gln-2) after treatment with nitrosoguanidine or ethyl methanesulfonate, had thermolabilities intermed ... | 1978 | 684557 |
| studies on phenotypic variation between chinese hamster kupffer cell lines. ii. correlation relationships and coordinate control of enzyme activities. | 1978 | 679986 | |
| studies on phenotypic variation between chinese hamster kupffer cell lines. i. quantitative variation of enzyme activities. | 1978 | 679985 | |
| biochemical and genetic approaches to the study of mammalian mitochondrial trnas. | the possible existence of mammalian mitochondrial asparaginyl-trna has been examined using a variety of approaches. [3h]asparagine was incorporated into protein by mitochondria of the chinese hamster ovary (cho) cell line asn-7, which has a temperature-sensitive cytosolic asparaginyl-trna synthetase, either in the presence of cycloheximide or at a nonpermissive temperature. isolated mitochondria of cho thymidine kinase minus (tk-) cells also incorporated the amino acid into protein. in each case ... | 1978 | 667700 |
| genetic analysis of a chinese hamster cell line lacking a g1 phase. | 1978 | 658159 | |
| enhancement of the synthesis of specific cellular polypeptides in a temperature-sensitive chinese hamster cell line (k12) defective for entry into s phase. | temperature-sensitive chinese hamster cells (k12) have been shown to be defective for the initiation of new rounds of dna replication when incubated at the restrictive temperature (40.5 degrees). by temperature shift experiments with synchronous cultures, we have marked out the step at which the mutation is expressed as the four hours preceding the initiation of dna synthesis. the block imposed by the mutation has been shown to be irreversible. in order to approach the biochemical characterizati ... | 1978 | 649666 |
| carcinogenicity and mutagenicity of benz(a)anthracene diols and diol-epoxides. | benz(a)anthracene (ba) and its five possible trans-dihydrodiols were evaluated for determination of their skin tumor-initiating activity and their mutagenic activity in chinese hamster v79 cells. in addition, the skin tumor-initiating abilities of five diol-epoxides of ba were tested. results showed (+/-)-trans-3,4-dihydroxy-3,4-dihydrobenz(a)anthracene (ba 3,4-dihydrodiol) to be approximately 10 times more mutagenic than was ba and about 20 times more mutagenic than were the other possible dihy ... | 1978 | 647680 |
| enhancement of postreplication repair in ultraviolet-light-irradiated chinese hamster cells by irradiation in g2 or s-phase. | postreplication repair in synchronous chinese hamster cells was determined after split doses of ultraviolet (uv) radiation. repair was enhanced by irradiation of cells in g2 or s-phase with a small dose of uv radiation at least 1.5 h before a three-fold larger dose of uv. there was significantly greater enhancement when the first dose was given in g2 than when it was given in the s-phase 0.5-1.5 h before the test dose. these data indicate that enhancement of postreplication repair does not requi ... | 1978 | 667307 |
| late s phase cells (chinese hamster ovary) induce early s phase dna labeling patterns in g1 phase nuclei. | cells (chinese hamster ovary) in g1 phase were fused with cells in late s phase to determine if a cell in late s phase can induce dna synthesis in the nucleus of a g1 cell and, if so, to determine if the dna synthesis so induced in a g1 phase nucleus has an autoradiographic pattern characteristic of early or of late s phase synthesis. the results indicate (i) that 89% of the g1 nuclei in late-s/g1 binucleates synthesized dna, while only 2% of the control unfused g1 cells synthesized dna, and (ii ... | 1978 | 277928 |
| [effect of inhibitors of rna and protein synthesis on the course of mitosis in a synchronized culture of chinese hamster cells]. | the synthesis period of various types of rna and proteins during the interphase related to the immediate after synchronization mitosis was investigated on teh synchronized culture of chinese hamster cells with inhibitors. analysis of mi and forms of mitosis pathology indicated the proteins functionally related to the cell division to be mainly synthesized during the second half of the interphase. the most important action of pyromycin during this time is the induction of c-mitosis on account of ... | 1978 | 566594 |
| interpretation of survival-curve data for chinese hamster cells, line v-79 using the multi-target, multi-target with initial slope, and alpha, beta equations. | 1978 | 308056 | |
| polyfunctional radiosensitizers iv. the effect of contact time and temperature on sensitization of hypoxic chinese hamster cells in vitro by bifunctional nitroxyl compounds. | three biradical nitroxyl compounds have been shown to modify the slope and shoulder region of the hypoxic cell survival curve of v79 cells to different degrees. the amount of sensitization produced by these compounds is dependent on the cell-drug contact time at both 20 degree and 37 degree c whereas sensitization by the monoradical nitroxyl, nppn, is independent of these factors. the results suggest that biradicals may modify cellular biochemistry in such a way as to change the repair capacity ... | 1978 | 277261 |
| rapid-mixing studies of the mechanisms of chemical radiosensitization and protection in mammalial cells. | a continuous flow, rapid-mixing system has been constructed to measure the degree of radiosensitization or protection observable after incubation of chinese hamster ovary cells at room temperature for periods from about 5 to 1000 ms with a number of radiation modifiers. in agreement with adams et al. (1975) full sensitization by oxygen is obtained in only a few tens of milliseconds. misonidazole (10 mm) sensitizes at very nearly the steady-state level (e.r. approximately 2.3) in about 300 ms. si ... | 1978 | 277254 |
| cytotoxic effect of 5-thio-d-glucose on chronically hypoxic cells in multicell spheroids. | the effect of 5-thio-d-glucose on chronically hypoxic cells in the multicell spheroids of chinese hamster v79 cells was investigated. the radiation survival curves of spheroid cells indicated that most of the chronically hypoxic cells in the spheroids could be eliminated by incubating the spheroids with 5-20 mm of 5-thio-d-glucose or 17 hours. histological studies also demonstrated that 5-thio-d-glucose preferentially kills the hypoxic cells located in the inner part of the spheroids. | 1978 | 277213 |
| genetic analysis of the g1 period: isolation of mutants (or variants) with a g1 perior from a chinese hamster cell line lacking g1. | cells of the chinese hamster line v79-8 multiply without a g1 period (i.e., they are g1(-)) and have an average generation time of 9.5 hr. after mutagenesis and selection we have derived five stable mutants (or variants) of this line that have longer generation times. in each case the increase in generation time is due solely to the introduction of a g1 period into the cell cycle, with no measurable effect on s, g2, or m. fusions among these five g1(+) mutant lines and another presumably nonmuta ... | 1978 | 275858 |
| 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 | |
| [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 |
| 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 |
| growth arrest of chinese hamster ovary cells in serum-free medium: changes in cell morphology and the intracellular and prostaglandin-induced levels of cyclic amp. | when chinese hamster ovary (cho) cells are shifted from medium which contains serum into serum-free medium, they complete one cell doubling and arrest in the g1 phase of the cell cycle. during the first 72 hr of arrest, there is little change in intracellular adenosine 3':5'-phosphate (camp) level, and the cells retain their usual epithelial-like morphology. after 96 hr, the camp level doubles, the magnitude of the prostaglandin e1-induced changes in camp increases threefold, and the cells conve ... | 1978 | 214460 |
| alteration in morphology of chinese hamster ovary cells by ni3s2 and dibutyryl camp. | 1978 | 210534 | |
| characterization of virus-like particles released from the hamster cell line cho-k1 after treatment with 5-bromodeoxyuridine. | simple biochemical measurements have been shown to seriously overestimate the production of c-type particles by chinese hamster ovary (cho) cells treated with 5-bromodeoxyuridine. first, most particle-bound dna polymerase activity released by induced cells was associated with particles which had a different density from c-type particles. second, when labelled with radioactive uridine, induced cho cells released small amounts of particle-bound radioactivity. most of the radioactivity, however, wa ... | 1978 | 77893 |
| genetic and biochemical characterization of mutants of cho cells resistant to the protein synthesis inhibitor trichodermin. | mutants resistant to the protein synthesis inhibitor trichodermin have been selected in chinese hamster ovary (cho) cells. the mutants vary in their stability from those which rapidly lose their resistance to others which are relatively stable after prolonged growth in nonselective medium. protein synthesis in extracts from the latter class of mutants (trir) is resistant to the inhibitory action of trichodermin as compared to similar extracts from wild-type cells. after dissociation into subunit ... | 1978 | 694724 |
| sister chromatid exchanges induced by cyclophosphamide in v79 cells cultured in diffusion chambers in mice. | chinese hamster cells v79 were cultured in diffusion chambers (dc) and implanted into mice. an exponential growth was observed from the 2nd to 4th day after implantation. the maximum growth was reached on the 6th day. after that, cell growth and viable cell counts decreased. three days after implantation of dc with v79 cells, the hosts received 6 hourly injections of 0.2 ml of 5-bromodeoxyuridine (budr) solution at concentrations of 0.125 to 1.0 x 10(-2) m. dc were removed for chromosome and sis ... | 1978 | 661842 |
| genetic effects of crocidolite asbestos in chinese hamster lung cells. | chinese hamster lung cells cultured in the presence of crocidolite asbestos displayed inhibition of cell growth. cell death was directly associated with the phagocytosis of larger fibres as observed with the aid of trypan blue. water soluble components of crocidolite did not appear to inhibit cell growth. chromosomal aberrations were induced by the asbestos. the aberrations were confined mainly to structural aberrations--breaks and fragments. electron-microscopic preparation indicated that asbes ... | 1978 | 661841 |
| 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 |
| inhibitory effect of d-mannosamine on the growth of d-glucosamine-requiring mutant strain of chinese hamster lung cells. | 1978 | 669979 | |
| 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 |
| dna single-strand lesions due to 'sunlight' and uv light: a comparison of their induction in chinese hamster and human cells, and their fate in chinese hamster cells. | 1978 | 674395 | |
| effect of alkane tumor-promoting agents on chemically induced mutagenesis in cultured v79 chinese hamster cells. | linear alkanes of specific chain length between 6 and 16 carbon atoms, an aryl derivative of dodecane, and a phorbol diester were tested in a cell culture system for relative ability to enhance mutagenesis induced by a chemical carcinogen, methylazoxymethanol acetate (mam). mutation frequencies at the ouabain-resistance locus were measured. results indicated an excellent correlation between the relative activities of the above compounds in enhancing mutagenesis in the in vitro culture system and ... | 1978 | 633409 |
| mutagenicity studies with praziquantel, a new anthelmintic drug, in mammalian systems. | praziquantel, a new anthelmintic drug with antischistosomal and anticestodal properties, was tested in comparison with a placebo control and a 'positive control' with cyclophosphamide in mammalian test system in vivo for potential mutagenic effects. the test systems used and the tested doses of praziquantel were: (1) dominant lethal test on male nmri mice, 12 mating periods of 4 days each, 1 x 1200 mg/kg bw by mouth; (2) dominant lethal test on female nmri mice, treatment during pre-estrus, 1 x ... | 1978 | 580366 |
| ghost-mediated transfer of human hypoxanthine-guanine phosphoribosyl transferase into deficient chinese hamster ovary cells by means of polyethylene glycol-induced fusion. | 1978 | 689099 | |
| sister chromatid exchanges and growth inhibition induced by the flame retardant tris(2,3-dipromopropyl) phosphate in chinese hamster cells. | the effects of the flame retardant tris(2,3-dibromopropyl) phosphate (tris-bp) on growth, sister chromatid exchanges (sce), and chromosome aberrations of chinese hamster v79 cells cultured either in vitro or in diffusion chambers (dc) implanted into mice were studied. tris-bp caused a dose- and time-dependent reduction of cell growth as measured by colony-forming activities. a significant dose-dependent increase in sce was observed in v79 cells either in the cultures treated with tris-bp or in d ... | 1978 | 642035 |
| saccharin-induced sister chromatid exchanges in chinese hamster and human cells. | since the induction of sister chromatid exchanges in cultured cells has been shown to be the most sensitive mammalian system to detect the effects of mutagenic carcinogens, chinese hamster ovary cells and human lymphocytes were exposed to the sodium saccharin found to induce bladder cancer in rats. both that saccharin and a highly purified extract of it increased the yield of sister chromatid exchanges in both types of cells. the results, which were repeatable and statistically highly significan ... | 1978 | 644315 |
| the effect of isoniazid (inh) on chinese hamster and mouse spermatogonia. | acute and chronic treatment of chinese hamsters and mice with 5, 25 and 125 mg/kg isoniazid (inh) given by oral intubation did not enhance the chromosomal aberration frequencies in spermatogonia. the structural and numerical aberration rates remained in the range of spontaneous events even after the chronic treatment over 12 weeks with 3 x 125 mg/kg inh per week. this dose is much higher than normally used for prevention and therapy in man (3--16 mg/kg). | 1978 | 649167 |
| nucleus anomaly test in chinese hamster and in rat after treatment with isoniazid. | nucleus anomaly test in chinese hamsters and in rats treated with isoniazid (inh) was carried out according to a standard protocol in two different laboratories. these comprised both short-term studies, in which the tests were performed on animals killed 6, 12, 24, 36, or 48 h after the second of two consecutive doses of 5, 25, or 125 mg/kg inh given at an interval of 24 h, and long-term studies in animals treated with 25 mg/kg inh thrice weekly for 12 weeks. as a rule, each group consisted of a ... | 1978 | 649174 |
| assignment of the genes for triose phosphate isomerase to chromosome 6 and tripeptidase-1 to chromosome 10 in mus musculus by somatic cell hybridization. | evidence is presented for the assignment of the gene for triose phosphate isomerase to mus musculus chromosome 6 and tripeptidase-1 to chromosome 10 by synteny testing and chromosome assignment in chinese hamster x mouse somatic cell hybrid clones. neither tpi nor trip-1 were expressed concordantly with any known isozyme markers in 45 hybrid clones (13 primary and 32 secondary). karyotypic analysis of 21 clones showed that the expression of tpi and chromosome 6 were concordant in all cases as wa ... | 1978 | 566475 |
| assignment of a mus musculus gene for triosephosphate isomerase to chromosome 6 and for glyoxalase-i to chromosome 17 using somatic cell hybrids. | chinese hamster x mouse hybrid cells segregating mouse chromosomes have been used to assign a gene for triosephosphate isomerase (tpi-1, ec 5.3.1.1, mckusick no. 19045) to mouse chromosome 6, and a gene for glyoxalase-i (glo-1, ec 4.4.1.5, mckusick no 13875) to mouse chromosome 17. the genes for tpi-1 and lactate dehydrogenase b are syntenic in man and probably so in the dog. it is therefore likely that they are syntenic also in the mouse. it is of interest then that there is a mouse gene, ldr-1 ... | 1978 | 566476 |
| time and cell systems as variables in fusion experiments with polyethylene glycol. | cell hybridization was done between a monolayer of b14-150 chinese hamster cells and a suspension of either mouse leukemia cells or normal human lymphocytes. cell contact was obtained by centrifugation of the suspension cells onto the monolayer cells in a culture plate. cell fusion was done by means of polyethylene glycol (peg). the optimum time for peg exposure as well as the yield of hybrid cells differed markedly with the different combinations. | 1978 | 566713 |
| mutagenesis by n-acetoxy-2-acetyl aminofluorene of chinese hamster v79 cells is unaffected by caffeine. | 8-azaguanine (azg)- and 6-thioguanine (tg)-resistant cells (mutants) were induced in chinese hamster v79-4 cells by 0.1--2.5 microgram/ml n-acetoxy-2-acetyle aminofluorine (acaaf) treatments in the presence of 5% fetal bovine serum (fbs). the frequency of resistant colonies increased from 1 to 47 per 10(5) survivors. the effect of caffeine (50--200 microgram/ml) during the mutagenesis expression period was determined by adding caffeine 1--24 h after acaaf. the medium was replaced after 48 h expo ... | 1978 | 566636 |
| properties of the thymidine transport system of chinese hamster ovary cells as probed by nitrobenzylthioinosine. | the transport of thymidine into chinese hamster ovary cells grown in suspension culture was measured under conditions in which thymidine was not metabolized, namely, when cells had been depleted of atp. the system transporting thymidine was saturable (kztm = 70 micron), rapid 50% of transmembrane equilibrium level attained within 8 sec), and was apparently shared by other nucleosides, but not thymine or hypoxanthine. 6([4-nitrobenzyl]thio)-9-beta-d-ribofuranosylpurine, "nitrobenzylthioinosine", ... | 1978 | 568178 |
| assignment of the gene for glyoxylase i to mouse chromosome 17 by somatic cell genetics. | evidence is presented for the assignment of the gene for glyoxylase i to mouse chromosome 17 using mouse x chinese hamster somatic cell hybrids. glo i was not expressed concordantly with any known marker enzymes which represented 11 linkage groups. the presence of chromosome 17 and expression of glo i were concordant in 31/31 clones. glo i is thus linked to the h-2 histocompatibility locus in the mouse. | 1978 | 569476 |
| replicon sizes in mammalian cells as estimated by an x-ray plus bromodeoxyuridine photolysis method. | a new method is described for estimating replicon sizes in mammalian cells. cultures were pulse labeled with [3h]thymidine ([3h]tdr) and bromodeoxyuridine (brdurd) for up to 1 h. the lengths of the resulting labeled regions of dna, lobs, were estimated by a technique wherein the change in molecular weight of nascent dna strands, induced by 313 nm light, is measured by velocity sedimentation in alkaline sucrose gradients. if cells are exposed to 1,000 rads of x-rays immediately before pulse label ... | 1978 | 570067 |
| persistence of the fc cytophilic antibody receptor in macrophage hybrid cells. | hybrid cell clones were obtained from mouse macrophase/ehrlich ascites cell fusions which showed the 'fc' cytophilic antibody receptor site, phagocytosis and motility typical of macrophages. with continued growth of the clones for 11 weeks, the receptor became undetectable but could be unmasked by dilute trypsin treatment; subsequent remasking of the receptor could be prevented with cycloheximide treatment of the hybrid cells. these hybrids produced cystic anaplastic tumours in neonatal irradiat ... | 1978 | 400978 |
| determination of corynebacterium diphtheriae toxigenicity by a colorimetric tissue culture assay. | chinese hamster ovary (cho) cell cultures in microtiter wells are sensitive to growth inhibition and killing by picogram quantities of diphtheria toxin. in the absence of biologically active toxin, the cho cell culture produces sufficient acidic metabolites to change the phenol red ph indicator from pink to yellow within 56 h. in the presence of 10 pg of toxin per well, growth inhibition can be observed microscopically within 24 h. diphtheria toxin can be qualitatively assayed from culture super ... | 1978 | 415068 |
| the incorporation of homologous and heterologous hypoxanthine-guanine phosphoriboxyltransferase into mutant cells. | experiments are described leading to partial compensation of a deficiency in the enzyme hypoxanthine-guanine phosphoribosyltransferase in mutant cells by supplying the cells with exogenous purified enzymes. deae-dextran is an effective helper agent, whereas poly (l-lysine), lysolecithin and amphotericin b seem to inhibit the entry of the enzymes of their activity. enzyme preparation from chinese hamster was found to have different effects in different mutant cell lines. in mutant chinese hamster ... | 1978 | 563735 |
| effect of different treatments on the activity of the heat labile enterotoxin of escherichia coli f11(p155). | a whole cell lysate preparation of the escherichia coli strain f11(p155) was treated with the following agents: heat (60 degrees c for 30 minutes), pronase, lipase, amylase, formalin (0.1%), sodium lauryl sulfate (0.05%) and sarkosyl nl30 (0.05%). except for the amylase treatment, the treated whole cell lysate was inactivated when tested in rabbit gut loops or on chinese hamster ovary cells. the preparations treated with heat or formalin could be used to produce a neutralizing antiserum or could ... | 1978 | 352492 |
| increased escherichia coli enterotoxin detection after concentrating culture supernatants: possible new enterotoxin detectable in dogs but not in infant mice. | the heat-stable enterotoxin (st) of escherichia coli can be detected by infant mouse or dog intestinal loop tests. these tests differ in that the dog assay uses concentrated culture supernatants and is based on measurements of net intestinal absorption, whereas the mouse test uses unconcentrated supernatants and depends on gross fluid accumulation. to compare the relative sensitivities of these assays, culture supernatants of randomly selected e. coli isolates from 34 bangalee diarrhea patients ... | 1978 | 370144 |
| chimeric toxins: toxic, disulfide-linked conjugate of concanavalin a with fragment a from diphtheria toxin. | a disulfide-linked conjugate of concanavalin a (con a) and fragment a from diphtheria toxin has been synthesized and shown to be toxic for hela (human), chinese hamster ovary (cho), and sv3t3 (murine) cells. the conjugate was constructed by first coupling cystamine to con a with a carbodiimide reagent and then reacting the modified con a with reduced fragment a under conditions promoting disulfide interchange. the desired conjugate, obtained in nearly 50% yield relative to input of fragment a, w ... | 1978 | 281682 |
| replica plating and in situ enzymatic assay of animal cell colonies established on filter paper. | we have developed a simple technique for the replica plating of chinese hamster ovary (cho) cells. in this procedure cells are allowed to divide for 8-16 days between the plastic surface of a petri dish and a disc of whatman no. 50 filter paper, weighted down with glass beads. the culture medium can be replaced when necessary without disturbing the growing colonies. cells from each developing colony grow into the fibers of the paper, while others remain attached to the plate. the cell colonies t ... | 1978 | 349559 |
| entrapment of metaphase chromosomes into phospholipid vesicles (lipochromosomes): carrier potential in gene transfer. | transfer of genes from one type of cultured mammalian cell to another by using isolated metaphase chromosomes has been reported with a frequency of one per 10(6)-10(8) cells. very recently a rate of 16/10(6) has been reported with chinese hamster ovary cells [spandidos, d. a. & siminovitch, l. (1977) proc. natl. acad. sci. usa 74, 3480-3484]. to increase the frequency of gene transfer, we isolated metaphase chromosomes from hypoxanthine guanine phosphoribosyltransferase (hgprt) positive cells, e ... | 1978 | 349565 |
| assay method for vibrio cholerae and escherichia coli enterotoxins by automated counting of floating chinese hamster ovary cells in culture medium. | as chinese hamster ovary (cho) cells on plastic proliferate, many cells float off into the medium instead of piling up after they form a monolayer. fewer cells were floating in the medium when cho cells were incubated with cholera toxin at a concentration as low as 10 pg/ml. the toxin increased the adhesiveness of the cells forming confluent monolayers so that the floating cells accumulated on the adherent monolayers. on the basis of this finding, a simple, quantitative assay method for cholera ... | 1978 | 350897 |
| sensitization of ultraviolet radiation damage in bacteria and mammalian cells. | bacteria (serratia marcescens) and mammalian cell (chinese hamster v79-379a) were irradiated in monolayers with ultraviolet light at 254 nm or 365 nm in the presence or absence of radiosensitizing drugs. at 254 nm, killing is very efficient (d37 approximately 1 j m-2 exposure, or approximately 6 x 10(4) photons absorbed by dna per bacterium), and sensitizers have no effect. at 365 nm, cells are not killed in buffer, but are inactivated in the presence of nifurpipone or misonidazole. lethal expo ... | 1978 | 354675 |
| bromodeoxyuridine tablet methodology for in vivo studies of dna synthesis. | 5-bromodeoxyuridine (brdu) tablets with different physical characteristics are useful in a wide variety of studies requiring detection of dna replication in vivo. these tablets can effect a high substitution of brdu in dna, thereby permitting sister chromatid differentiation in chromosomes stained with 33258 hoechst alone or in conjunction with giemsa. baseline and cyclophosphamide-induced in vivo sister chromatid exchange frequencies in mouse spleen, marrow, and thymus were measured and found t ... | 1978 | 356290 |
| enterotoxigenicity of enteropathogenic serotypes of escherichia coli isolated from infants with epidemic diarrhea. | enteropathogenic serotypes of escherichia coli which have been incriminated by epidemiological evidence as responsible for epidemics of acute diarrhea in infants are often found to be nontoxigenic when tested by conventional systems such as y1-adrenal, chinese hamster ovary, and suckling mouse assays. twelve such strains, representing four different enteropathogenic serotypes, were examined for their capacity to elaborate toxic materials which alter water transport. ultrafiltration fractions pre ... | 1978 | 361562 |
| use of human-liver microsomes from kidney-transplant donors for the induction of chromatid aberrations and sister-chromatid exchanges by means of pre-carcinogens in chinese hamster cells in vitro. | samples of two human livers taken during operation of kidney donor patients were processed for microsome fractions and used for metabolization of cyclophosphamide (cp) and dimethylnitrosamine (dmn) in combination with the nadph-generating system. rat-liver microsomes were checked for comparison. induction of chromatid aberrations and sister-chromatid exchanges in a newly isolated clone of chinese hamster fibroblasts served as indicators of activity. human s-9 fractions standardized on protein co ... | 1978 | 362179 |
| mutagenicity of industrial compounds. vii. styrene and styrene oxide: ii. point mutations, chromosome aberrations and dna repair induction analyses. | the possible genetic effects produced by styrene have been investigated by means of different methodologies in several biological organisms: (a) the induction of point mutation has been investigated in salmonella typhimurium (reverse mutation), in the yeast schizosaccharomyces pombe (forward mutation), both in vitro and in vivo, in the host-mediated assay of mice, and in the chinese hamster cell line grown in vitro (v-79) (forward mutation); (b) the induction of chromosome mutation has been inve ... | 1978 | 366743 |
| host range restriction of vaccinia virus in chinese hamster ovary cells: relationship to shutoff of protein synthesis. | chinese hamster ovary cells were found to be nonpermissive for vaccinia virus. although early virus-induced events occurred in these cells (rna and polypeptide synthesis), subsequent events appeared to be prevented by a very rapid and nonselective shutoff of protein synthesis. within less than 2 h after infection, both host and viral protein syntheses were arrested. at low multiplicities of infection, inhibition of rna synthesis with cordycepin resulted in failure of the virus to block protein s ... | 1978 | 310474 |
| the effect of bromodeoxyuridine on the segregation of the chicken-specific hprt gene from chinese hamster-chick red blood cell somatic hybrids. | the segregation of the chick-specific hprt gene was studied in three chinese hamster-chick red blood cell hybrid lines. the three lines showed individual segregation kinetics, the segregation taking place in an exponential-like fashion. bromodeoxyuridine becomes incorporated into the nuclear dna and increases the spontaneous segregation rate. | 1978 | 299650 |
| thermal enhancement of the effectiveness of gamma radiation for induction of reproductive death in cultured mammalian cells. | the induction by gamma radiation of reproductive death in cultured cells derived from a rat ureter carcinoma (ruc-2) and from chinese-hamster lung tissue (ch-v79) was shown to be enhanced by hyperthermic treatments at 41, 43 and 45 degrees c. the degree of enhancement was found to depend on the line of cells studied, the temperature employed and the level of damage considered. the influence of accumulating sublethal damage was decreased by hyperthermia, and the final slope of the radiation survi ... | 1978 | 309451 |
| inducers of dna synthesis present during mitosis of mammalian cells lacking g1 and g2 phases. | the cell cycle analysis of chinese hamster lung fibroblast v79-8 line by the premature chromosome condensation method has confirmed the absence of measurable g1 and g2 periods. sendai virus-mediated fusion of mitotic v79-8 cells with g1 phase hela cells resulted in the induction of both dna synthesis and premature chromosome condensation in the latter, indicating the presence of the inducers of dna synthesis above the critical level not only throughout s phase, as it is in hela, but also during ... | 1978 | 283413 |
| effects of asbestos on epithelioid cell lines. | the in vitro effects of asbestos fibers on the growth and viability of cho cells, an epithelioid cell line derived from chinese hamster ovary, and on k-22 cells, an epithelial cell line derived from rat liver, have been studied. relatively low concentrations of asbestos (10 micrograms/ml) were quite cytotoxic to both cell types. a sample of chrysotile asbestos was more toxic than samples of crocidolite or amosite. the toxic factor could not be extracted from the asbestos and toxicity occurred on ... | 1978 | 233816 |
| study on the mutagenicity of conjugated estrogens in human, animal and bacterial systems. | conjugated estrogens were studied for mutagenicity (and implied carcinogenicity) in two strains of s. typhimurium, two normal and three neoplastic human lymphoid cell lines (the latter from burkitt's lymphoma patients) in cell culture and a chinese hamster cell line in diffusion chambers implanted into mice. no significant increase in mutation rate or chromosome aberrations were noticed after exposure to conjugated estrogens. | 1978 | 217940 |
| diphtheria toxin has the properties of a lectin. | the inhibition of protein synthesis in chinese hamster v79 cells by diphtheria toxin is antagonized by the lectins concanavalin a, succinylated concanavalin a, and wheat germ agglutinin but not by proteus vulgaris phytohemagglutinin or abrus agglutinin. the effects of concanavalin a and wheat germ agglutinin are reversed by methyl alpha-mannoside and n-acetylglucosamine, respectively. the inhibition of diphtheria toxin as a function of concanavalin a concentration fits a model of competitive inh ... | 1978 | 272642 |
| tumorigenicity and its suppression in cybrids of mouse and chinese hamster cell lines. | the effect of cytoplasm upon the expression of tumorigenicity was examined with a pair of mouse and a pair of chinese hamster cell lines, in intraspecies cybrids formed by reciprocal fusions between either tumorigenic or nontumorigenic cells and cytoplasms derived from them. with the mouse cells, 3t3 and the simian virus 40-transformed line svt2, the cybrid clones were tumorigenic when svt2 cells were fused with 3t3 cytoplasts, but not in the reciprocal fusion. with the hamster cells, chef/18 an ... | 1978 | 276880 |