Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| comparative analysis of proteins selectively released from cell nuclei of different eukaryotic species under conditions of mild hydrolysis by nucleases. | nuclei of cultured chinese hamster fibroblasts, dechoryonized eggs of drosophila melanogaster, calf thymocytes and mouse spleen were digested with micrococcal nuclease or dnase i under conditions when about 15-20% of nuclear dna is hydrolyzed. proteins released from the nuclei with this dna were analyzed by electrophoresis in polyacrylamide gels in the presence of sds and the most prominent components were purified in each case. it is shown that these components derived from different species ha ... | 1980 | 6251362 |
| transformation of mammalian cells with an amplifiable dominant-acting gene. | we have transferred a mutant hamster gene coding for an altered dihydrofolate reductase to wild-type cultured mouse cells by using total genomic dna from methotrexate-resistant chinese hamster ovary a29 cells as donor. by demonstrating the presence of hamster gene sequences in transformants we have provided direct evidence for gene transfer. transformants selected for increased resistance to methotrexate contain increased amounts of the newly transferred gene. we have used this mutant dhfr gene ... | 1980 | 6251468 |
| identification of 5-methylcytosine in dna fragments immobilized on nitrocellulose paper. | a method to identify 5-methylcytosine (m5cyt) in dna immobilized on nitrocellulose paper by using antibody against m5cyt raised in rabbits is described. immobilized restriction fragments of dna are incubated first with purified antibody against m5cyt and then with goat anti-rabbit igg labeled with 125i. restriction fragments containing m5cyt are visualized by autoradiography. by using this method, a heavily methylated fragment of about 1700 base pairs was identified in nuclear dna fom chinese ha ... | 1980 | 6251470 |
| comparative gene mapping: order of loci on the x chromosome is different in mice and humans. | for comparative studies we have used the somatic cell hybridization approach to regionally map genes on the mouse x chromosome. fibroblasts from a mouse with the balanced reciprocal translocation t(xd;16b5)16h were fused with a chinese hamster cell line (v79/380-6) deficient in activity of the enzyme hypoxanthine phosphoribosyltransferase (hprt). interpecific cell hybrids were initially selected for retention of the mouse translocation chromosome carrying the hprt gene. subsequently, hybrid clon ... | 1980 | 6251472 |
| dna of simian virus 40 mutates chinese hamster cells. | infection of chinese hamster cells with sv 40 dna gives rise to mutants resistant both to s-axaguanine (ag) and aminopterin (ap). this mutagenic effect can be raised when facilitating dna uptake of cells by a helper agent. the extent of muyagenic action depends further on the concentration of dna applied to the cells, with 2 micrograms/ml being more effective than 10 micrograms/ml, as well as on the period of incubation of infected cells before onset of mutant selection (mutation expression time ... | 1980 | 6251786 |
| the specific organisation of satellite dna sequences on the x-chromosome of mus musculus: partial independence of chromosome evolution. | dna was isolated from a chinese hamster/mouse hybrid cell line containing a single mouse chromosome, the x-chromosome, and digested with a variety of restriction endonucleases known to cut mouse satellite dna. after agarose gel electrophoresis and transfer to nitrocellulose, hybridisation was carried out to a radioactive mouse satellite dna probe. in this manner the organisation of satellite sequences at an individual chromosome was determined. we have found that the organisation of centromeric ... | 1980 | 6253924 |
| altered synthesis and processing of oligosaccharides of vesicular stomatitis virus glycoprotein in different lectin-resistant chinese hamster ovary cell lines. | to determine the particular intracellular steps in the glycosylation of the vesicular stomatitis virus (vsv) glycoprotein that were altered in several lectin-resistant cho cell lines, vsv-infected parental and mutant cells were pulse-labeled for 30 and 120 min with [3h]mannose and [3h]glucosamine. cell-associated viral glycopeptides were analyzed by gel filtration combined with specific glycosidase digestions and compared with the corresponding mature virion oligosaccharides. the intracellular g ... | 1980 | 6255177 |
| simian virus 40-chinese hamster kidney cell interaction. v. cooperative effect of 5-iodo-2'-deoxyuridine and mitomycin c in the enhancement of virus replication in infected cells. | a cooperative effect of 5-iodo-2'-deoxyuridine and mitomycin c which amplified (10- to 50-fold) their stimulating effect on simian virus 40 replication was obtained in infected chinese hamster kidney cells. the results indicate that these drugs act at different levels to modify the permissiveness of cells to simian virus 40. | 1980 | 6255213 |
| structure and organization of the highly repeated and interspersed 1.3 kb ecori-bg1ii sequence family in mice. | ecori digestion of total mouse dna yields a prominant 1.3 kb fragment amounting to between 1 and 2% of the mouse genome. the majority of the 1.3 kb ecori fragments have a single bg1ii site 800 bp from one end. this ecori-bg1ii sequence family shows hindiii and haeiii sequence heterogeneity. we have cloned representatives of the ecori-bg1ii gene family in charon 16a and studied their structure and organization within the genome. the cloned 1.3 kb fragments show the expected restriction enzyme pat ... | 1980 | 6255440 |
| control of sv40 replication by a simple chromosome in monkey-hamster cell hybrids. | somatic cell hybrids produced between cercopithecoid monkey and chinese hamster cells were used to assay susceptibility to sv40 viral infection in an attempt to define the primate factors that determine permissiveness to viral replication. these cell hybrids, which differed in their primate chromosome complement, were found to differ also in their ability to sustain viral replication. a correlation was found between an elevated sv40 viral replication and the presence of the chromosomes 11 in the ... | 1980 | 6255616 |
| enhanced sensitivity of tumorigenic cells to rapid rounding induced by phenylalaninol. | this study describes a rounding reaction induced in mammalian cells by the addition of phenylalaninol. in the chinese hamster ovary tsh1 line the rounding occurred rapidly with a half time of 1 min at 25 mm phenylalaninol. after the removal of phenylalaninol, the rounding was reversed, leading to the reflattening of the cells with a half-time of 3.5 min. rounding was inhibited by dibutyryl-camp and testosterone, and reflattening by cytochalasin b. either in the case of the tsh1 line and its grow ... | 1980 | 6257353 |
| structure of the abelson murine leukemia virus genome and the homologous cellular gene: studies with cloned viral dna. | circular double-stranded dna produced after infection of mouse cells with abelson murine leukemia virus (a-mulv) was isolated and cloned in the phage vector charon 21a. the resulting clones of the a-mulv genome show homology to the ends of moloney mulv and to a 3.5 kb central region containing sequences unique to abelson virus. a 2.3 kb restriction fragment containing only a-mulv-specific sequences was subcloned in the plasmid vector pbr322 and used as a probe for the cellular gene that had been ... | 1980 | 6257398 |
| isolation and characterization of a pseudomonas aeruginosa mutant producing a nontoxic, immunologically crossreactive toxin a protein. | nitrosoguanidine mutagenesis of pseudomonas aeruginosa strain pao-1 yielded a mutant strain, pao-pr1, which produced a protein that was immunologically indistinguishable from native toxin a and was nontoxic for cultured chinese hamster ovary cells. in contrast to native toxin, the cell-associated and extracellular crossreactive material (crm), designated "crm protein," possessed no adenosine diphosphate-ribosylating activity. this crm protein comigrated with native toxin a on sodium dodecyl sulf ... | 1980 | 6261247 |
| separation of human and chinese hamster arylsulfatases a and b by two-directional polyacrylamide gel electrophoresis. | two-directional or 'mirrow' polyacrylamide gel electrophoresis permits one simultaneously to separate and detect human and chinese hamster arylsulfatases a and b. such a separation was not possible in conventional one-dimensional polyacrylamide gel systems. the amount of each enzyme present could be quantitated by scanning at 515 nm after incubation of the gel in nitrocatechol sulfate. direct comparisons showed that this system is at least as sensitive as a cellogel-methylumbelliferone sulfate m ... | 1980 | 6103805 |
| molecular mechanisms involved in the production of chromosomal aberrations. ii. utilization of neurospora endonuclease for the study of aberration production by x-rays in g1 and g2 stages of the cell cycle. | chinese hamster ovary cells (cho) were x-irradiated in g1 and g2 stages of the cell cycle and subsequently neurospora endonuclease (ne) (e.c.3.1.4), an enzyme which is specific in cleaving single-stranded dna, was introduced into the cells, after making the cells permeable by treatment with inactivated sendai virus. with this treatment all classes of x-ray-induced chromatid aberrations increased in g2 cells, whereas in g1 cells an increase in chromosome type of aberrations was found, associated ... | 1980 | 6244487 |
| distribution of endogenous murine leukemia virus dna sequences among mouse chromosomes. | we used mouse-chinese hamster somatic cell hybrids which lose mouse chromosomes to examine the distribution of murine leukemia virus dna sequences in the genome of a/hej mice. we analyzed total cellular dna from various hybrid clones for the presence of viral sequences by molecular hybridization and used the southern blot hybridization procedure to identify viral dna in cellular restriction endonuclease fragments. our results show that murine leukemia virus dna sequences are distributed among ma ... | 1980 | 6245275 |
| ubiquitous, interspersed repeated sequences in mammalian genomes. | dna base sequence comparisons demonstrate that the principal family of 300-nucleotide interspersed human dna sequences, the repetitive double-strand regions of hela cell heterogeneous nuclear rna, and specific rna polymerase iii in vitro transcripts of cloned human dna sequences are all representatives of a closely related family of sequences. a segment of approximately 30 residues of these sequences is highly conserved in mammalian evolution because it is also present in the interspersed repeat ... | 1980 | 6246492 |
| the synergistic effects of sv40 and budr on induction of gene mutations and chromosomal aberrations in chinese hamster cells. | the induction of chromosomal aberrations and gene mutations was studied in chinese hamster cells after separate and combined treatment with budr and sv40. separate treatment of cells with budr or virus infection increased the yield of chromosomal aberrations and reversions from glutamine requirement, expressed at 40 degrees c (a ts mutant), to prototrophy. the combined effect of the incorporation of budr into one dna strand, and a subsequent infection by sv40 was additive as regards the percenta ... | 1980 | 6247650 |
| atp enhances cyclic amp accumulation by intact p388 mouse lymphoma cells. | one of the characteristics of malignant cells is a poor response to hormones and a low level of cyclic amp. whilst this is true of intact p388 mouse lymphoma cells, high levels of adenylate cyclase (atp pyrophosphate-lyase (cyclizing), ec 4.6.1.1) activity can be measured in particulate preparations of these cells. when atp is added to the incubation medium of intact lymphoma cells, the cyclic amp level is enhanced. this effect of atp is not mediated by adenosine, nor is it enhanced by naf. the ... | 1980 | 6248129 |
| mutagenicity testing in mammalian cells. ii. validation of multiple drug-resistance markers having practical application for screening potential mutagens. | chinese hamster ovary (cho) cell lines heterozygous at both the adenine phosphoribosyltransferase (aprt) and thymidine kinase (tk) loci were used for single-step selection of spontaneous and induced mutants resistant to 8-azaadenine (aar), 6-thioguanine (tgr), ouabain (ouar), or 5-fluorodeoxyuridine (fudrr). mutation data are reported for direct mutagens (ems, ethyl methanesulfonate; mnng, n-methyl-n'-nitro-n-nitrosoguanidine; nqo, 4-nitroquinoline 1-oxide) and promutagens (dmn, dimethylnitrosam ... | 1980 | 6449664 |
| assignment of pgm3 to the long arm of human chromosome 6. studies using chinese hamster x human cell hybrids containing a human 6/15 translocation. | hybrids derived from the fusion of thymidine kinase deficient chinese hamster cells and human cells carrying a 6/15 translocation, 46,xx,t(6;15)(cen;p13), were analyzed for the expression of human pgm3, glo and me1. the results show that pgm3 and me1 are on the long arm and glo is on the short arm of human chromosomes 6. | 1980 | 6450030 |
| studies on the cytopathogenicity of entamoeba histolytica. | we have explored the interaction of virulent and avirulent e. histolytica (hm1 and 303 respectively) with human polymorphonuclear leukocytes (pmns) and chinese hamster ovary (cho) cells. pmns exhibit chemotaxis to both hml and 303. on contact with hml, pmns degranulate and die (trypan blue uptake); incubation at a ratio of 100 pmns per ameba for 40 minutes revealed 70 per cent pmn death with 84 per cent hml viability. 303s are often ingested by pmns on contact; after incubation as above, only 1 ... | 1980 | 6258505 |
| absence of arsenite mutagenicity in e coli and chinese hamster cells. | because exposure to compounds of arsenic has been implicated as a cause of cancer, an investigation of the mutagenicity of sodium aresenite in e coli and in chinese hamster cells was performed. in the e coli system, trp + revertants were not induced by arsenite in a variety of experimental protocols including spot tests, treat and plate protocols, and fluctuation tests. the mutator effect of a tif-1 strain was partially blocked by arsenite. arsenite did not cause the induction of lambda prophage ... | 1980 | 6459229 |
| control of streptozotocin diabetes in chinese hamsters by cultured mouse islet cells without immunosuppression: a preliminary report. | 1980 | 6767141 | |
| mammary gland cell-mediated mutagenesis of mammalian cells by organ-specific carcinogens. | rat mammary gland cells have been used to activate chemical procarcinogens to mutagenic compounds in a culture system. mutagenesis was tested in chinese hamster v-79 cells that were cocultured with the mammary cells. the locus mutations tested for were resistance to ouabain and resistance to 6-thioguanine. mammary cells were separated into several fractions. fractions enriched in either epithelial or stromal cells could both mediate mutagenesis. the mutation frequency related to the density of t ... | 1980 | 6768455 |
| selective toxicity of 5-s-cysteinyldopa, a melanin precursor, to tumor cells in vitro and in vivo. | the effect of 5-s-cysteinyl-l-3,4-dihydroxyphenylalanine (cys-dopa), an intermediate in the pathway from l-3,4-dihydroxyphenylalanine (l-dopa) to pheomelanin, on the growth of eight human tumor cell lines in culture was compared to that of l-dopa. the tumor cell lines tested comprise two neuroblastomas (nb-1 and yt-nu), two amelanotic melanomas (hmv and seki), a gastric carcinoma (mkn-28), and three squamous cell carcinomas (hela-s3, kb, and a salivary gland carcinoma). cys-dopa at a concentrati ... | 1980 | 6771000 |
| the use of liver cell cultures in mutagenesis studies. | a sensitive cell-mediated assay has been developed for testing the mutagensis of liver carcinogens. mutagenesis was detected in chinese hamster v79 cells that were cocultivated with hepatocytes isolated after collagenase/hyaluronidase digestion of rat liver slices. mutations were characterized by resistance to ouabain and 6-thioguanine. seven of the nitrosamines, which are potent liver carcinogens, exhibited a mutagenic response. mutagensis with the carcinogens could be detected at micromolar do ... | 1980 | 6784635 |
| argininosuccinic acid synthetase deficiency in a hamster cell line and its complementation of argininosuccinic aciduria human fibroblasts. | unlike normal human cells, cultured fibroblasts from patients with argininosuccinic aciduria cannot synthesize arginine from citrulline because they have a deficiency of argininosuccinic acid lyase (asl). we have found that v79, a chinese hamster cell line, cannot grow on citrulline. although these cells show a normal uptake of citrulline and have levels of asl comparable to a human cell line (hela) which can grow in citrulline-containing medium, v79 cells have less than 5% of the argininosuccin ... | 1980 | 6777600 |
| preliminary studies on the ability of drosophila microsomal preparations to activate mutagens and carcinogens. | subcellular fractions from drosophila melanogaster, known to have several xenobiotic-metabolizing enzymatic activities, were investigated with respect to their ability to biotransform compounds that require metabolic activation before exerting mutagenic effects. nitrofurazone, dimethylnitrosamine, cyclophosphamide and 2-acetylaminofluorene were activated to mutagens upon incubation with drosophila microsomes or 20000 x g supernatant: mutagenicity was observed in chinese hamster ovary cells, esch ... | 1980 | 6777691 |
| [light and scanning electron studies on the morphology of the vaginal plug in laboratory animals]. | serial sections of vaginal plugs of mice, rats, guinea pigs and hamsters (cricetulus griseus) were studied by light microscopy as well as whole plugs and freeze-fractures by scanning electron microscopy. the vaginal plugs are encircled by a layer of superficial cells of the vaginal epithelium and consist of coagulated seminal fluid, containing irregular holes. the spermatoza are mainly localized inside bigger cavities. scanning electron microscopic study of freeze-fractured plugs reveals, that t ... | 1980 | 6893258 |
| assignment of a gene for succinate dehydrogenase to human chromosome 1 by somatic cell hybridization. | a chinese hamster cell mutant has been described with little or no activity of succinate dehydrogenase (soderberg et al., 1977). we described here the selection and characterization of human-hamster hybrids obtained from the fusion of these mutant cells and human lymphoblasts or ht1080 fibrosarcoma cells. the presence of human chromosome 1, identified by cytogenetic techniques and isozyme analysis, is correlated with the restoration of succinate dehydrogenase activity in the hybrids, and segrega ... | 1980 | 6934864 |
| dna-mediated cotransfer of unlinked mammalian cell markers into mouse l cells. | purified dna from three different types of mammalian cells was precipitated with calcium phosphate and added to mouse l cells deficient in thymidine kinase (tk). donor dna was prepared from three cell lines: (a) mouse cells transfected with uv-inactivated herpes simplex virus (hsv) type 1, or a purified fragment of hsv carrying the tk gene (b) human hela cells, and (c( cho, a cell line derived from chinese hamster ovaries. several hypoxanthine-aminopterin-thymidine resistant colonies were isolat ... | 1980 | 6932400 |
| effects of prospidine on survival and growth of mammalian cells in culture. | the effects of prospidine, chemically known as 3, 12-diaza-6,9 diazoniadispiro[5.2.5.2]hexadecane,3,12-bis(3-chloro-2-hydroxypropyl)-dichloride (nsc-166100), on cell viability, growth, and colony formation were investigated in several mammalian cell lines. cell cycle progression and the terminal point of action of the drug were monitored by flow cytometry. prospidine was cytostatic for two suspension cultures (friend leukemia and l1210 cells) at a concentration of 10 mg/ml during the first cell ... | 1980 | 6933266 |
| sister-chromatid exchange induction by metabolically activated retinoids in human diploid fibroblast cultures. | 13-cis-retinoic acid, retinyl-mthyl-ether, retinyl-phenyl-ether, retinyl-thio-ether and axerophthene each induced dose-dependent sister-chromatid exchanges (sce) in human diploid fibroblasts. the functional relationship between retinoid concentration and sce rate was similar in each of the 5 retinoids tested. the relationship reached a plateau at concentrations exceeding 8 micrograms/ml. alpha-naphthoflavone (anf), an inhibitor of p448-dependent mono-oxygenase, prevented the retinoid-induced inc ... | 1980 | 6933309 |
| prevalent deficiency in tumor cells of cycloheximide-induced cycle arrest. | mammalian cell growth is regulated by a process that is completed at a restriction point in the late g1 part of the cycle. this process is highly sensitive to serum concentration and to moderate inhibition of protein synthesis by cycloheximide (chm) or other agents. we have proposed that a cell must accumulate a labile protein in a critical amount before events related to its dna synthesis can start. the accumulation of this protein requires conditions suitable for growth, including sufficient a ... | 1980 | 6933461 |
| assignment of a human genetic locus to chromosome 5 which corrects the heat sensitive lesion associated with reduced leucyl-trna synthetase activity in ts025cl chinese hamster cells. | a heat-sensitive (hs) leucyl-trna synthetase (leurs) deficient cho mutant, ts025cl, was fused with human leukocytes and hybrids isolated in hat medium at the nonpermissive temperature. nineteen heat-resistant (hr) and 14 hs subclones were isolated from four independent primary hybrids and tested for the expression of 24 human isozymes which have been assigned to 17 human chromosomes. four hr independent subclones and three hs independent subclones were analyzed for the presence of human chromoso ... | 1980 | 6933703 |
| posttranslational modification of elongation factor 2 in diphtheria-toxin-resistant mutants of cho-k1 cells. | we have identified two types of mutants of chinese hamster ovary cells in which the unique adp-ribose attachment site in elongation factor 2 (ef-2) is altered, thereby rendering them resistant to diphtheria and pseudomonas toxins (toxr). the first is mutant in the gene for ef-2 and possesses a permanently altered, toxr gene product. the second lacks a component of a posttranslational modification system that converts toxr ef-2 to the toxin-sensitive (toxs) state. we postulate that this modificat ... | 1980 | 6928655 |
| cotransfer of linked eukaryotic genes and efficient transfer of hypoxanthine phosphoribosyltransferase by dna-mediated gene transfer. | the efficiency of dna-mediated transfer of the gene (hprt) for hypoxanthine phosphoribosyltransferase (hprt; imp: pyrophosphate phosphoribosyltransferase, ec 2.4.2.8) is dependent upon the recipient cell used. hprt has been transferred into mouse tg8 or chinese hamster chtg49 cells at a high frequency, similar to the frequency of the gene (tk) for thymidine kinase (tk; atp:thymidine 5'-phosphotransferase, ec 2.7.1.21) transfer into mouse lmtk- cells (i.e., 10(-6)). in contrast, the frequency of ... | 1980 | 6929511 |
| isolation and localization of dna segments from specific human chromosomes. | recombinant dna techniques have been combined with somatic cell genetic methods to identify, isolate, and amplify fragments of human dna localized at specific regions of human chromosome 11 selected as a model system. a library of genomic dna segments has been constructed, in lambda charon 4a bacteriophage, from the dna of a somatic cell hybrid carrying a portion of human chromosome 11 on a chinese hamster ovary cell background. using a nucleic acid hybridization technique that distinguishes hum ... | 1980 | 6930670 |
| drb resistance in chinese hamster and human cells: genetic and biochemical characteristics of the selection system. | stable mutants resistant to the nucleoside analog 5,6-dichloro-1-beta-d-ribofuranosyl benzimidazole (drb), which interferes with rna synthesis, have been selected in chinese hamster ovary (cho) and human diploid fibroblasts. in cho cells, upon treatment with the mutagen ethyl-methane sulfonate (ems), a linear dose--response between the concentration of mutagen and the frequency of drbr mutants was observed in the range of 20--300 micrograms/ml. the selection system did not show cell density or c ... | 1980 | 6930702 |
| expression of the human argininosuccinate synthetase gene in hamster transferents. | the structural gene for human argininosuccinate synthetase [l-citrulline:l-aspartate ligase (amp-forming), ec 6.3.4.5] was transferred to argininosuccinate synthetase-deficient chinese hamster cells via metaphase chromosomes isolated from human lymphoblast line mgl8d1, a constitutive overproducer of argininosuccinate synthetase, and from its repressible parent, mgl8b2. argininosuccinate synthetase expression was selected for in citrulline-containing medium, and the human origin of the argininosu ... | 1980 | 6933472 |
| branched-chain aminotransferase deficiency in chinese hamster cells complemented by two independent genes on human chromosomes 12 and 19. | branched-chain aminotransferase (bct) catalyzes the reversible transamination of the branched-chain alpha-keto acids to the branched-chain l-amino acids. since branched-chain l-amino acids (l-isoleucine, l-leucine, and l-valine) are essential for cell growth, cells which lack bct were unable to proliferate in media containing alpha-keto acids in place of the corresponding l-amino acids. chw-1102, a chinese hamster cell line, lacks bct and does not grow in alpha-keto acid media. somatic cell hybr ... | 1980 | 6933702 |
| high molecular weight polypeptides (270,000-340,000) from cultured cells are related to hog brain microtubule-associated proteins but copurify with intermediate filaments. | high molecular weight polypeptides (hmwps) of 270,000 to 340,000 were found to be major components of intermediate filaments prepared by triton x-100 extraction after spreading of rat glioma c6, hela, chinese hamster ovary, and simian virus 40-transformed chinese hamster lung cells. c6 hmwps were shown to resemble high molecular weight microtubule-associated proteins from hog brain by four criteria: (i) comigration in electrophoresis on high-resolution sodium dodecyl sulfate/polyacrylamide gels, ... | 1980 | 6933530 |
| assignment of the sorbitol dehydrogenase locus to human chromosome 15 pter leads to q21. | the locus for sorbitol dehydrogenase (sord, e.c. 1.1.1.14) has been shown to segregate with hexosaminidase a and mannose phosphate isomerase in a series of human-chinese hamster somatic cell hybrids. cytogenetic analysis supports the assignment to chromosome 15 and further defines the gene locus to the region 15pter leads to q21. | 1980 | 6933990 |
| chromosomal assignment of the gene for folylpolyglutamate synthetase to human chromosome 9. | an auxotrophic mutant, gat-, derived from the chinese hamster cell line cho-k1 and exhibiting multiple growth requirements for glycine, adenine, and thymidine, has been shown to be deficient in one of the folate-dependent enzymes, folylpolyglutamate synthetase (fpgs). this mutant was fused with normal human lymphocytes and human lymphoblasts and 41 gat+ primary hybrid clones were isolated in medium lacking glycine, adenine, and thymidine. in addition, 71 secondary clones were isolated after grow ... | 1980 | 6934068 |
| cholera toxin-like toxin released by salmonella species in the presence of mitomycin c. | several serotypes of salmonella were shown to release increased amounts of a cholera toxin-like toxin during culture in vitro with mitomycin c (mtc). filter-sterilized culture supernatants containing the toxin caused elongation of chinese hamster ovary cells, which could be blocked by heating the supernatants at 100 degrees c for 15 min or by adding mixed gangliosides or monospecific cholera antitoxin. when mtc was not added to the salmonella cultures, little or no toxin was detected in crude, u ... | 1980 | 7002788 |
| mutation and inactivation of cultured mammalian cells exposed to beams of accelerated heavy ions. iv. biophysical interpretation. | a biophysical analysis is made of the results of recent experiments which used accelerated heavy ions of 20 to 470 kev micron-1 to induce inactivation and mutation (resistance to 6-thioguanine) in cultured v79 chinese hamster cells and hf19 human diploid fibroblasts. it is shown that the discrete nature of the primary ions must be explicity taken into account before the numbers of induced lethal and mutagenic lesions can be deduced from the observed radiosensitivities. the measured numbers of le ... | 1980 | 6966263 |
| regional assignment of the gene locus for steroid sulfatase. | the gene locus for steroid sulfatase, deficiency of which causes x-linked ichthyosis, is assigned to xp11 leads to xpter by analysis of 24 man-chinese hamster somatic cell hybrids. high steroid sulfatase activity in a hybrid clone having retained only part of xq is explained by demonstration of an additional late-replicating human x chromosome. this observation confirms previous evidence for noninactivation of the sts locus. | 1980 | 6985463 |
| ph dependence of the phototoxic and photomutagenic effects of chlorpromazine. | the ph dependence of the phototoxic effects of chloropromazine (cpz) in escherichia coli, salmonella typhimurium and chinese hamster cells were studied at ph 6--8. all three biological systems displayed higher photosensitization of the drug at lower ph-values. in s. typhimurium the combined action of drug and light also showed mutagenic activity which correlated with toxicity when exposed at ph 7 or 8. when solutions of protein or dna and cpz were exposed to near ultraviolet (uv) light, the drug ... | 1980 | 6986208 |
| molecular dosimetry of the chemical mutagen ethyl methanesulfonate: quantitative comparison of mutation induction in escherichia coli, v79 chinese hamster cells and l5178y mouse lymphoma cells, and some cytological results in vitro and in vivo. | molecular dosimetry studies were carried out to measure the extent of binding of radio-labeled ethyl groups to the dna of escherichia coli, v79 chinese hamster cells and l5178y mouse lymphoma cells treated with ethyl methanesulfonate (ems). the results show that (1) the amount of ethylation of the dna is similar in these cells when treatment conditions are identical, (2) the relationship between dose to dna (ethylations per nucleotide) versus exposure (mm applied concentration) is non-linear in ... | 1980 | 6987499 |
| [organization of mammalian genome replication: data on the high rate of dna replication in replicons of structural heterochromatin]. | by the autoradiography, the increase of the mean rate of replication fork movement in dna was shown for human skin fibroblasts during s-period induced by reseeding the stationary culture; the portion of high-rate replicons growing parallel to the increase in numbers of cells, in which the constitutive heterochromatin was replicating. furthermore, the heterogeneity of replicons was investigated in regard to the rate of dna chain growth in asynchronous cell populations of human and three rodent sp ... | 1980 | 6998067 |
| biological studies of a baculovirus in a mammalian cell line. | in two of five experiments, replication (tcid50) was observed following inoculation of chinese hamster cells with autographa californica nuclear polyhedrosis virus (npv). radiolabeling experiments employing tritiated thymidine consistently resulted in a labeled entity which banded in sucrose gradients at a density of 1.24-1.25 g/ml, similar to that observed for a. californica npv in the permissive trichoplusia ni cell line. the labeled entity is believed to be a. californica npv, based on infect ... | 1980 | 6998919 |
| golden hamster pancreatic islets: a tissue rich in monoamine oxidase. | we compared the steady state monoamine oxidase (mao) activity of collagenase-isolated pancreatic islets of the golden hamster with the steady state mao activity of liver, kidney, median eminence, pituitary, acinar pancreas, and cerebral cortex. the mao activity of the islets (5384 +/- 412 pmol/mg protein . min) was 3-fold greater than the activity of the next highest tissue (liver) and 12.5 times greater than the activity of the acinar pancreas. this high mao activity was not due to collagenase ... | 1980 | 7000496 |
| mutagenicity of sulphonylureas. | the 11 derivatives of beta-cytotropic sulphonylureas commonly used in the treatment of diabetes mellitus were tested in vivo in the highly sensitive sister-chromatid exchange test. chlorpropamide and tolbutamide gave a positive reaction with a clear dose-response in chinese hamsters and mice. the two compounds gave a mutagenic response neither in the salmonella/mammalian-microsome mutagenicity test (with and without microsomal activation) nor in the chromosomal aberration test. in the micronucle ... | 1980 | 6990252 |
| cytogenetic effect of ortho-phenylenediamine in the mouse, chinese hamster, and guinea pig and of derivatives, evaluated by the micronucleus test. | the mutagenic potential of ortho-phenylenediamine--known by studies on salmonella typhimurium--was studied in mice, chinese hamsters and guinea pigs with the use of the micronucleus test. in bone marrow of all three species, chromosomal damage was detected following intraperitoneal injections of the test chemical, this damage was seen also after peroral administration to mice. four derivatives of ortho-phenylenediamine containing one or two methyl-, nitro- or chlorosubstituents in 4- or 5-positi ... | 1980 | 6992742 |
| validation and comparative studies on 180 chemicals with s. typhimurium strains and v79 chinese hamster cells in the presence of various metabolizing systems. | 1980 | 6993936 | |
| testing propafenone hydrochloride in the ames salmonella microsome system and in mammalian cytogenetic systems (bone marrow, spermatogonia). | 2'-(2-hydroxy-3-propylaminopropoxy)-3-phenyl-propiophenone-hydrochloride (propafenone-hcl, rytmonorm) was tested for mutagenic activity in the salmonella microsome system (ames test) and in mammalian cell systems. neither in the ames test (62.5-1000 microgram/plate) nor in the bone marrow cells and spermatogonia of chinese hamster (injected doses: 1.57, 3.13, 6.27 mg/kg) there is any evidence for an enhancement of mutation frequencies or chromosome aberration rates. also, the micronucleus rates ... | 1980 | 7011328 |
| chinese hamster lung cells synthesize and confine to the cellular domain a collagen composed solely of b chains. | the acid-soluble collagen extracted from cultured chinese hamster lung (chl) cell layers has been isolated after limited pepsin digestion and differential salt fractionation. polyacrylamide gel electrophoresis of this material under denaturing conditions showed the presence of collagen chains with an apparent molecular mass of 120,000 daltons both before and after reduction, indicating the absence of interchain disulfide bonds in the native molecule. when chromatographed on cm-cellulose under de ... | 1980 | 7001474 |
| chromosome aberration tests with chinese hamster cells in vitro with and without metabolic activation--a comparative study on mutagens and carcinogens. | chromosome aberration tests (ch-test) in vitro were carried out on more than 400 chemicals from our environment, which included carcinogens and other compounds such as food additives, medical drugs, pesticides and those used in laboratories or industries. all results were compared with those obtained by mutation assays with bacteria (ames test). nearly half of these chemicals tested were positive either in the ch-tests or in the ames tests. among the chemicals being positive in the ch-tests, how ... | 1980 | 7002106 |
| chromosomal events in carcinogenic initiation and promotion: implications for carcinogenicity testing and cancer prevention strategies. | we have provided experimental evidence in favour of the hypothesis that carcinogenesis is triggered by at least two chromosomal events, which must occur in a single diploid somatic cell in a specific time sequence: (i) specific recessive mutational or epigenetic chromosomal change(s) resulting in a heterozygous (m/+), latently premalignant state (initiation); this must be followed by (ii) a chromosomal rearrangement involving the affected locus, and leading to homozygosity (m/m) or hemizygosity ... | 1980 | 7002784 |
| enhancement of sister-chromatid exchange in chinese hamster ovary cells by nitrofurans. | the nitrofurans, n-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (fanft), n-[4-(5-nitro-2-furyl)-2-thiazolyl]acetamide (nfta), 2-amino-4-(5-nitro-2-furyl)thiazole (anft), 2-methyl-4-(5-nitro-2-furyl)thiazole (mnft), 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (af-2), nitrofurantoin, 5-nitro-2-furfurylidene diacetate and 5-nitro-2-furamidoxime were assayed for the enhancement of sister-chromatid exchange (sce) in chinese hamster ovary (cho) cells and for the mutagenic activity in salmonella typhimuriu ... | 1980 | 7003376 |
| human-specific nuclear protein that associates with the polar region of the mitotic apparatus: distribution in a human/hamster hybrid cell. | we describe the first example of a predominantly nuclear protein which during mitosis becomes part of the mitotic apparatus. this protein has been termed the nuclear-mitotic apparatus (numa) protein. in interphase cells numa protein is restricted to the nucleus and is a constituent of isolated nuclear matrices, but in mitotic cells it is observed by indirect immunofluorescence microscopy to be concentrated at the polar regions of the mitotic apparatus. this mitotic localization is dependent on t ... | 1980 | 7004645 |
| detection of regulatory receptors and distinctive surface markers. | cell sorting has been used as an approach to describing surface markers and functional receptors of hemopoietic stem cells and progenitors. significant enrichment of cfu-s was obtained with fluorescent cell sorting of human antihuman sperm-labelled bone marrow cells; significant enrichment of human cfu-c was obtained by cell sorting of hybridoma (kgp1)-labelled human bone marrow cells. significant changes in human bone marrow cfu-c, but not cfu-e were observed by fluorescence polarization after ... | 1980 | 7008870 |
| mutagenic activity of pyrazine derivatives: a comparative study with salmonella typhimurium, saccharomyces cerevisiae and chinese hamster ovary cells. | 1980 | 7009348 | |
| interaction of cytopathogenic toxin from clostridium difficile with cells in tissue culture. | partially purified cytopathogenic toxin from clostridium difficile induced morphological changes in five cell lines in tissue culture. the relative sensitivity scale of the cell lines was human lung and intestinal fibroblasts greater than chinese hamster ovary cells much greater than mouse adrenal cells greater than mouse neuroblastoma cells. the cytopathogenic effect did not occur in toxin-treated lung fibroblasts incubated at 0 degree c. pre-incubation of lung fibroblasts with 2,4-dinitropheno ... | 1980 | 7010532 |
| identification of a cytotoxin produced by legionella pneumophila. | culture filtrates of legionella pneumophila were cytotoxic for chinese hamster ovary cells. the cytotoxin was found to be methanol soluble, heat stable, and stable from ph 5 through 8. | 1980 | 6995339 |
| a flow cytometric study of chromosomes from rat kangaroo and chinese hamster cells. | chromosomes from rat kangaroo (ptk) and chinese hamster (chv 79) cells have been prepared for quantitative flow-cytometric analysis. the preparation time was otimized down to 30 (ptk) and 40 min (chv 79). dapi was used as a at-sensitive fluorescent dye to stain for monoparameter dna measurements. simultaneous two-parameter dna-protein analysis was carried out with dapi and sr 101 (as a general protein fluorochrome) in combination. the karyotype of the ptk cells with 13 (14) chromosomes was separ ... | 1980 | 6995409 |
| the induction of mutation and differentiation in mammalian cells by chemicals which initiate or promote tumor formation. | a cell-mediated mutagenesis assay was developed to predict the potential carcinogenic hazard of some environmental chemicals. in this assay, cells with appropriate markers for mutagenesis, such as the chinese hamster v79 cells, are co-cultivated with cells capable of metabolizing chemical carcinogens. use of this assay made it possible to demonstrate a relationship between the degree of carcinogenicity and mutagenicity of a series of polycyclic hydrocarbons, nitrosamines and aflatoxins, and to e ... | 1980 | 7030700 |
| value of passive immune hemolysis for detection of heat-labile enterotoxin produced by enterotoxigenic escherichia coli. | the method of passive immune hemolysis of evans and evans (infect. immun. 16:604-609, 1977) for detection of heat-labile enterotoxin produced by enterotoxigenic escherichia coli was modified. a total of 373 strains of e. coli were tested by this method using materials obtained by treating the cells with polymyxin b and rabbit antiserum against cholera enterotoxin, purified by affinity gel column coupled with purified cholera enterotoxin, in n-hydroxyethylpiperazine-n'-2-ethanesulfonic acid buffe ... | 1980 | 7031077 |
| a sensitive hepatocyte-mediated assay for the metabolism of nitrosamines to mutagens for mammalian cells. | a sensitive cell-mediated assay has been developed for testing mutagenesis in chinese hamster v79 cells by carcinogenic nitrosamines. mutations were characterized by resistance to ouabain and 6-thioguanine. since v79 cells do not metabolize nitrosamines, mutagenesis in the v79 cells was tested in the presence of primary hepatocytes capable of metabolizing nitrosamines. the hepatocytes were isolated after collagenase and hyaluronidase digestion of liver slices. all seven liver carcinogens of the ... | 1980 | 7188682 |
| in vitro thermochemotherapy of human colon cancer cells with cis-dichlorodiammineplatinum(ii) and mitomycin c. | the thermosensitivity of human colon adenocarcinoma (lovo) cells was investigated as a function of temperature and duration of heating in exponentially growing cultures. at 39-43 degrees, time-dependent survival followed a simple exponential function. do values decreased progressively with a rise in temperature, from do at 40 degrees = 38 hr to do at 42 degrees = 17 hr to do at 43 degrees = 1.5 hr. thus indicating relative thermoresistance of lovo cells compared to chinese hamster ovary cells. d ... | 1980 | 7188883 |
| [induction of chromosome aberrations in chinese hamster cells by oncogenic bovine adenovirus type 3]. | 1980 | 7190444 | |
| amino acid analysis and cell cycle dependent phosphorylation of an h1-like, butyrate-enhanced protein (bep; h1(0); ip25) from chinese hamster cells. | a fraction enriched in the butyrate-enhanced protein (bep) has been isolated from chinese hamster (line cho) cells by perchloric acid extraction and bio-rex 70 chromatography. amino acid analyses indicate that the composition of bep resembles that of cho h1; however, bep contains 11% less alanine than h1, and, in contrast to h1, bep contains methionine. treatment of bep with cyanogen bromide results in the cleavage of a small fragment of approximately 20 amino acids so that the large fragment se ... | 1980 | 7191324 |
| [inhibitory effect of homologous antiviral antibodies on viral cell destruction]. | experiments were performed on the model chinese hamster cell culture -- sindbis virus in which there develops an acute infection accompanied by active virus reproduction, cell rounding and detachment from the glass for 24--48 h. addition in the cultural medium of a 0.5% immune serum to the sindbis virus after its adsorption by the monolayer culture fully prevents the development of cytopathic changes and favours obtaining chronically infected cultures that produce the infection virus. the decrea ... | 1980 | 7191737 |
| cytotoxic effects of protease inhibitors on human cells. 2. effect of elastatinal. | effects of elastatinal, a protease inhibitor, on dna repair and its cytotoxicity were investigated in normal human, xeroderma pigmentosum and chinese hamster v79 cells. there were no effects of elastatinal on dna repair and uv-induced sister chromatid exchanges, and all 3 cell lines demonstrated essentially the same sensitivity to the cytotoxic effect of elastatinal. these results were quite different from those by antipain, another protease inhibitor, and caffeine. | 1980 | 7191773 |
| regional localization of the genes coding for human aco2, arsa, and naga on chromosome 22. | the segregation of the chromosome 22 markers aco2, arsa, and naga was studied in somatic cell hybrid clones. these hybrids were isolated following fusion of chinese hamster (e36 or a3) cells with leucocytes of donors carrying an (x;22) or (1;22) translocation. the results suggest the assignment of arsa and naga to the region 22q13 leads to 22qter and of aco2 to the region 22q11 leads to 22q13. | 1980 | 7192199 |
| lack of correlation between effects of tumor promoter tpa on plasminogen activator production, phosphatidyl choline synthesis, and hexose transport in mammalian cell culture systems. | we have investigated the effects of the tumor promoter 12-0-tetradecanoyl-phorbol-13-acetate (tpa) on plasminogen activator production, hexose transport and metabolism, and the incorporation of choline into the acid soluble pool and into phosphatidylcholine in suspension cultures of mouse l, mouse p388 leukemia, human hela, and chinese hamster ovary cells, and in monolayer cultures of baby hamster kidney (bhk), mouse 3t3, mouse 3t6, and mouse p388d1 macrophage-like cells. bhk, 3t3, p388d1, and p ... | 1980 | 7192288 |
| isolation and characterization of chinese hamster ovary cell variants defective in adhesion to fibronectin-coated collagen. | variant clones of chinese hamster ovary (cho) cells were selected for reduced adhesion to serum-coated tissue culture plates. these clones also displayed reduced adhesion to substrata composed of collagen layers coated with bovine serum or with fibronectin (cold-insoluble globulin). wild-type (wt) and adhesion variant (adv) cells grew at comparable rates in suspension culture, but the adhesion variants could not be grown in monolayer culture because of their inability to attach to the substratum ... | 1980 | 7193214 |
| cell migration through three-dimensional gels of native collagen fibres: collagenolytic activity is not required for the migration of two permanent cell lines. | three dimensional gels of native type i collagen fibres have been used as a substratum for the growth and migration of chinese hamster ovary cells (fibroblastoid cell line) and rpmi-3460 melanoma cells (tumorigenic cell line from syrian hamster). quantitative data concerning the migration of these cells from the gel surface into the 3-dimensional collagen gel matrix have been obtained. the migration of both cell types into the collagen gel matrix is not accompanied by the degradation of collagen ... | 1980 | 7194877 |
| sensitivity of several cell systems to acrylamide. | chick spinal ganglia, chick muscle cells combined with mouse spinal cord explants, c1300 neuroblastoma cells, chinese hamster ovary cells and newborn rat cerebral cells were exposed to various concentrations of acrylamide in culture. four morphological and 1 electrophysiological parameters were applied in order to score toxic effects. it appeared that the neurite formation of rat cerebral neurons was the most sensitive criterion showing an effect at 10(-7) m acrylamide. | 1980 | 7209998 |
| ultraviolet light induction of diphtheria toxin-resistant mutations in normal and dna repair-deficient human and chinese hamster fibroblasts. | the role of unrepaired dna lesions in the production of mutations is suspected of contributing to the initiation phase of carcinogenesis. since the molecular basis of mutagenesis is not understood in eukaryotic cells, development of new genetic markers for quantitative in vitro measurement of mutations for mammalian cells is needed. furthermore, mammalian cells, genetically deficient for various dna repair enzymes, will be needed to study the role of unrepaired dna lesions in mutagenesis. the re ... | 1980 | 7213317 |
| focus-forming ability and surface markers of hamster-human malignant lymphoma hybrids. | we have examined the properties of hybrid cells formed by polyethylene glycol-mediated fusion of the grc+l-73 line of chinese hamster ovary (cho) cells with peripheral blood cells from patients with chronic lymphocytic leukemia (cll) or with bone marrow cells from patients with malignant lymphoma. the results indicate that hybrid cells can be detected by their ability to form "foci" of characteristic morphology in the presence of a monolayer of parental cho cells and that clones isolated from su ... | 1980 | 7353077 |
| temporal sequence of replication of the chicken-specific dna in chinese hamster-chick red blood cell hybrids. | 1980 | 7351212 | |
| the beta-globin gene is on the short arm of human chromosome 11. | investigations on the regulation of human globin gene expression are assisted by a knowledge of the chromosomal location of the globin genes. previous studies have mapped the alpha-globin locus to human chromosome (hc) 16, and have shown that the human globin gene complex gamma-delta-beta co-segregates with lactate dehydrogenase a (ldh-a) and the presence of hc 11 in somatic cell hybrids. radioactively labelled globin complementary dna (cdna) probes were used in molecular hybridisation experimen ... | 1980 | 7354859 |
| isolation and characterization of 5-fluorouracil-resistant mutants of chinese hamster ovary cells deficient in the activities of orotate phosphoribosyltransferase and orotidine 5'-monophosphate decarboxylase. | a rapid, simple method for isolation of large numbers of chinese hamster ovary cell (cho-k1) mutants deficient in the final two enzymes of ump biosynthesis, orotate phosphoribosyltransferase (ec 2.4.2.10), and omp decarboxylase (ec 4.1.1.23) is described. the method takes advantage of the fact that cho-k1 cells require orotate phosphoribosyltransferase to activate the pyrimidine analog 5-fluorouracil to its active form; hence, mutants lacking thhe relevance of these observations to the metabolis ... | 1980 | 7368045 |
| mutagenic activity in drinking water. | drinking water samples concentrated by freeze drying were found to be mutagenic in a mammalian tissue culture assay using chinese hamster embryonic lung cells (v79). the mutagenicity could be enhanced by the promoter 12-o-tetradecanoyl-phorbol-13-acetate. the water itself was also shown to contain promoting chemicals. the mutation frequency of cells pretreated with low levels of benzo(a)pyrene was increased following subsequent exposure to the concentrated water sample. approaches to estimate th ... | 1980 | 7356093 |
| antifolate-resistant chinese hamster cells. evidence from independently derived sublines for the overproduction of two dihydrofolate reductases encoded by different mrnas. | a comparison by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the proteins synthesized by antifolate-sensitive (dc-3f) and -resistant (dc-3f/a3 and dc-3f/mq19) chinese hamster lung fibroblast cells has shown that an apparent molecular weight difference exists between the dihydrofolate reductases overproduced by the resistant sublines. translation in a rabbit reticulocyte lysate system of polysomal and cytoplasmic mrnas from the three sublines has shown that the overproduction of d ... | 1980 | 7356612 |
| resistance to methyl mercaptopurine riboside in cultured hamster cells. preliminary characterization of resistant cells and conditions affecting their selection in quantitative mutation studies. | cells resistant to high concentrations of methyl mercaptopurine riboside (mmpr), an anlogue of adenosine, were found at a frequency of about 6 x 10(-6) per viable cell in untreated cultures of v79 chinese hamster cells. resistant cells were selected less efficiently if purines were added to the mmpr-medium, but high cell densities had little effect upon selection. 6 independently-isolated spontaneous mmpr-resistant sublines were characterized by their resistance to the toxicity of different puri ... | 1980 | 7360156 |
| purification and properties of hamster liver ligandins, glutathione s-transferases. | glutathione s-transferases have been purified to homogeneity from chinese hamster liver. three enzyme forms were separated and designated forms i, ii, and iii in order of their elution from carboxymethylcellulose columns. the forms exhibit close physical similarities to glutathione s-transferases b (ligandin) of rat liver and epsilon of humam liver. however, enzyme kinetic analysis indicates that the hamster enzymes exhibit similar km values but higher vmax values towards common substrates compa ... | 1980 | 7371010 |
| regional mapping of ada and itp on human chromosome 20: cytogenetic and somatic cell studies in an x/20 translocation. | an apparently balanced de novo translocation between chromosomes x and 20, 46,x,t(x;20)(xp20q;xq20p), was identified in a severely retarded 13-year-old female with macrocephaly, bilateral overfolded pinnae, elbow contractures, clinodactyly, and seizures. budr-pulse studies show the normal x chromosome to be late replicating in both lymphocytes (50 cells) and skin fibroblasts (25 cells). an hprt deficient chinese hamster line was fused with lymphocytes from the patient, and hybrid lines were deri ... | 1980 | 7371431 |
| cytochemical studies of metaphase chromosomes by flow cytometry. | the cytochemical properties of metaphase chromosomes from chinese hamster and human cells were studied by flow cytometry. this technique allows precise quantitation of the fluorescence properties of individual stained chromosome types. chromosomes were stained with the following fluorescent dna stains: hoechst 33258, dapi, chromomycin a3, ethidium bromide, and propidium iodide. the relative fluorescence of individual chromosome types varied depending on the stain used, demonstrating that individ ... | 1980 | 7371453 |
| changes in the cell cycle during culture of mouse-chinese hamster cell hybrids. | cell cycle studies, using plm analysis, were carried out on a mouse-chinese hamster cell hybrid and its derivatives which stably retained all parental chromosomes during the year of study. parameter estimates were obtained from the plm curves, using conjugate gradient curve fitting procedures. the hybrid initially grew very slowly, and all phases (especially g1) were longer than those of either parent. during propagation, mean generation time decreased progressively, and the phase times approach ... | 1980 | 7372724 |
| effect of lead chromate on chromosome aberration, sister-chromatid exchange and dna damage in mammalian cells in vitro. | possible mutagenic activity of lead chromate in mammalian cells was studied using assays for chromosome aberrations and sister-chromatid exchanges in cultured human lymphocytes, and dna fragmentation as detected by alkaline-sucrose gradient sedimentation in cultured chinese hamster ovary (cho) cells. lead chromate caused dose-related increases in chromosome aberration and sister-chromatid exchange in human lymphocytes. no increase in dna damage was observed in cho cells, possibly due to the rela ... | 1980 | 7374664 |
| saccharin may act as a tumour promoter by inhibiting metabolic cooperation between cells. | the possible role of saccharin in the carcinogenic process is, at present, still unclear. carcinogenesis is a complex process involving, in many test systems, initiation and promotion phases. current evidence favours the hypothesis that initiation is due to a mutagenic event, while promotion (at least the early portion) is the result of epigenetic changes. although saccharin has been reported to be a weak mutagen in various in vitro test systems and a weak initiator in mouse skin, there is incre ... | 1980 | 7374758 |
| sister chromatid exchanges in human cells and chinese hamster cells. evidence that the rate of sister chromatid exchanges is a function of ploidy. | 1980 | 7379862 | |
| phagocytosis of nickel subsulfide particles during the early stages of neoplastic transformation in tissue culture. | cellular uptake of crystalline ni3s2 particles (a potent carcinogen) and amorphous nis particles (a noncarcinogen) were studied using light and electron microscopy. cultured syrian hamster embryo cells and chinese hamster ovary cells actively phagocytized ni3s2 particles (less than or equal to 5 micrometer) but did not take up nis particles (less than 5 micrometer). for example, within 30 min after addition of ni3s2 (high dose) to cell cultures, 12.5% of the cells contained nickel particles in t ... | 1980 | 7388819 |
| factors affecting the induction of chromosomal aberrations by cadmium in chinese hamster cells. | chinese hamster cells (line cho) were examined for cadmium-induced growth-rate pertubations and chromosomal aberrations. the threshold concentration of cd++ for the induction of chromosomal aberrations in cho cells cultured in f-10 medium supplemented with 15% newborn calf serum was determined to be 1 x 10(-6) m. cho cells grown in the presence of nontoxic levels of cd++ (2 x 10(-7) m) for 12 wk became resistant to toxic levels (2 x 10(-6) m) after this exposure. metaphase cells in these resista ... | 1980 | 7389413 |
| ultrastructural localization to 10 nm filaments of an insoluble 58k protein in cultured fibroblasts. | using a simple procedure, we have isolated a triton x-100 insoluble protein (58,000 mol wt) from cultured chinese hamster ovary (cho) cells, a fibroblastic cell line. the isolated protein, judged homogeneous by two-dimensional gel electrophoresis, was used to elicit antibodies in rabbits. the antiserum obtained is specific for the 58k protein as determined by immunoprecipitation from detergent solubilized 35s-labeled cho cells and by antibody labeling of sds solubilized swiss 3t3 cell extracts s ... | 1980 | 7391554 |
| large-scale isolation of uv-sensitive clones of cho cells. | we have isolated 54 ultraviolet light (uv) sensitive clones of chinese hamster ovary (cho) cells, including two from a parent cell line which is hypersensitive to ethyl methanesulfonate (ems) and is also sensitive to x rays. a replica plating technique was used for the isolation of two of the clones, and a semiautomated technique was used for the isolation of the other 52 clones. we have observed uv sensitization of up to 5-fold in the mutants relative to the parent in terms of the slopes of the ... | 1980 | 7404271 |
| expression of genes coding for non-histone chromosomal proteins in human-chinese hamster cell hybrids. an electrophoretic analysis. | the non-histone chromosomal (nhc) proteins of several human and hamster cell lines as well as human-hamster cell hybrids were investigated by one- and two-dimensional gel electrophoresis. in each type of human cell, over 90% of the 230 most prominent nhc proteins were indistinguishable electrophoretically from the nhc proteins of the hamster cells. of the roughly 10% which were distinct, 11 of the proteins may be human-specific, since they were found in each type of human cell examined. the nhc ... | 1980 | 7358723 |