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purification and chemical characterization of the heat-labile enterotoxin produced by enterotoxigenic escherichia coli.heat-labile enterotoxin (lt) produced by a human strain of enterotoxigenic escherichia coli (286c(2)) was purified to homogeneity from ph extracts of fermentor-grown cells by ultrafiltration, (nh(4))(2)so(4) fractionation, hydrophobic chromatography on norleucine-sepharose 4b, hydroxylapatite chromatography, and bio-gel p-150 filtration. purified lt preparations exhibited biological activity comparable to that of cholera toxin in four bioassays specific for the two enterotoxins (y-1 adrenal tumo ...197939893
mechanism of action of yersinia enterocolitica enterotoxin.enterotoxin derived from three clinical isolates of yersinia enterocolitica was compared with the heat-stable enterotoxin of escherichia coli. both toxins were biologically active in infant mice examined at 2 h and in ligated rabbit ileal loops at 6 h. neither substance, however, produced changes in ligated ileal loops at 18 h or in chinese hamster ovary or y1 adrenal tissue cultures. in addition, both y. enterocolitica enterotoxin concentrated approximately 20 times by ammonium sulfate precipit ...197939894
human gene mapping and cancer biology.the topics covered in this paper include: (i) a somatic cell genetics approach for measuring the individual variability in the susceptibility to dna damage/repair at the level of specific chromosomal sites; (ii) a rationale for a selective chemotherapy and/or immunotherapy of chromosomally unbalanced tumours; and (iii) studies on complementation for sister chromatid exchange (sce) in roden-human hybrids. preliminary studies indicate that the 'radiation co-transfer method' for gene mapping can be ...1979258171
[interaction of lambda bacteriophages with mammalian cells. ii. elucidation of the role of interacting components].the study of 3h-thymidine labelled bacteriophage lambda c185757 uptake by hela, rh and chinese hamster cell revealed the lack of cells or phage specificity in the phage interaction with cells. the phage uptake is shown to be an active process depending on the cell state. the mechanism of "protective" action of calcium chloride is found to be as follows: the calcium phosphate precipitate formed in phosphate-containing media absorbs the phage, thus increasing its concentration on the cell surface, ...1979572596
cytogenetic characterization of chinese hamster-sheep somatic cell hybrids.the methods used to characterize cytogenetically chinese hamster x sheep somatic cell hybrids have been reported. g and c banding patterns on hybrid metaphases allowed the discrimination between hamster and sheep chromosomes, and in addition to establish the unidirectional loss of sheep chromosomes in hybrid cells.1979575764
chromosomal imbalance in ovulated oocytes from syrian hamsters (mesocricetus auratus) and chinese hamsters (cricetulus griseus).chromosomes were studied in ovulated oocytes from syrian hamsters (mesocricetus auratus) and chinese hamster (cricetulus griseus) to assess the degree of chromosomal imbalance after first meiotic division of oogenesis. only one hyperploid oocyte among 307 studied was detected in the former, and none in oocytes from the latter species. structural chromosome alterations, single chromatids due to presegregation, and diploid chromosome sets resulting from meiotic blockage were not observed. the horm ...1979761487
structural studies of the major high mannose oligosaccharide units from chinese hamster ovary cell glycoproteins.the major high mannose-type glycopeptides present in chinese hamster ovary cells have the compositions (man)9(glcnac)2-asn, (man)8(glcnac)2-asn, and (man)6(glcnac)2-asn. the structures of these glycopeptides were determined by the combination of methylation analysis, acetolysis, smith periodate degradation, and alpha- and beta-mannosidase digestion. their complete structures are: manalpha1 leads to 2manaalpha1 leads to 6(manalpha1 leads to 2manalpha1 leads to 3)manalpha1 leads to 6(manalpha1 lea ...1979762159
adaptation of the staphylococcal coagglutination technique for detection of heat-labile enterotoxin of escherichia coli.protein a-containing staphylococci coated with specific antiserum were tested for heat-labile enterotoxin of escherichia coli. the immunological cross-reactivity of e. coli heat-labile enterotoxin with vibrio cholerae toxin (choleragen) was the basis for sensitizing stabilized suspensions of the cowan i strain of staphylococcus aureus with anticholeragen. unconcentrated culture supernatant fluid containing e. coli heat-labile enterotoxin produced macroscopic agglutination when mixed with sensiti ...1979372214
further study of the genetic toxicity of gentian violet.the genetic toxicity of gentian violet was studied with the ames and the rosenkranz bacterial assays as well as the cytogenetic assays (chinese hamster ovary cells in vitro in the presence of rat-liver s-9 fractions, the chicken-embryo and mouse-bone-marrow cells in vivo). gentian violet was found to be toxic but not mutagenic in the ames assay. however, it was active in the rosenkranz assay causing reparable dna damage. the presence of s-9 in the in vitro cytogenetic assay and in the bacterial ...1979372796
mutagenicity of some n- and o-acyl derivatives of n-hydroxy-2-aminofluorene in v79 chinese hamster cells.mutagenicity of 4 n- and o-acyl derivatives of n-hydroxy-2-aminofluorene (acyl: acetyl or myristoyl residue) was examined in v79 chinese hamster cells in the absence of a metabolic activation system. n-myristoyloxy-n-acetyl-2-aminofluorene (n-myo-aaf) was toxic and weakly mutagenic, inducing 8-azaguanine-resistant (azar) mutants in v79 chinese hamster cells in a concentration-dependent fashion; while n-acetoxy-n-myristoyl-2-aminofluorene (n-aco-myaf) and n-myristoyloxy-n-myristoyl-2-aminofluoren ...1979373878
slit-scan flow cytometry of mammalian chromosomes.a flow cytometer has been constructed which measures total fluorescence and the distribution of fluorescence along isolated, stained mammalian chromosomes. in this device, chromosomes flow lengthwise at 4 m/sec through a 1-micrometer thick laser beam. the fluorescence from each chromosome is recorded at 10 nsec intervals; the sequence of recorded values represents the distribution of fluorescence along the chromosome and is stored in the memory of a waveform recorder. the total fluorescence of e ...1979374608
comparison of the induction by cigarette smoke condensates of sister-chromatid exchanges in chinese hamster cells and of mutations in salmonella typhimurium.three cigarette smoke condensates were tested for the induction of sister-chromatid exchanges in ovary cells of the chinese hamster and for mutations in salmonella typhimurium. in the sister-chromatid exchange test an effect was obtained that was not enhanced by the inclusion of a system for metabolic activation. in the salmonella test, an effect was only obtained by including rat-liver homogenates derived from rats treated with inducers of the enzyme systems necessary for metabolic activation. ...1979375084
chromosomal aberration tests on 29 chemicals combined with s9 mix in vitro.a metabolic activation system with rat-liver microsome fraction plus cofactors (s9 mix) was applied to chromosomal aberration tests in vitro for the screening of chemical mutagens or carcinogens in the environment. dialkylnitrosamines only induced chromosomal aberrations in chinese hamster cells (chl) when treated with s9 mix. the incidence of chromosomal aberrations in chl varied with experimental conditions, e.g. incubation time, recovery time, components of s9 mic and inducers used for prepar ...1979375085
carcinogenicity of 2-hydroxybenzo(a)pyrene and 6-hydroxybenzo(a)pyrene in newborn mice.benzo(a)pyrene (bp), 2-hydroxybenzo(a)pyrene (2-hobp), and 6-hydroxybenzo(a)pyrene (6-hobp) were tested for tumorigenicity by i.p. injection into newborn mice. the mice were treated sequentially with 200, 400, and 800 nmol of compound on the first, eighth and fifteenth day of life, and the animals were killed at 24 weeks of age. treatment with 2-hobp caused about 4-fold more pulmonary tumors than bp, while 6-hobp had little or no tumorigenic activity. newborn mice treated with 2-hobp, bp, and 6- ...1979376121
tubulin and calmodulin. effects of microtubule and microfilament inhibitors on localization in the mitotic apparatus.indirect immunofluorescence was used to determine the distribution of calmodulin in the mitotic apparatus of rat kangaroo ptk2 and chinese hamster ovary (cho) cells. the distribution of calmodulin in ptk2 cells was compared to the distribution of tubulin, also as revealed by indirect immunofluorescence. during mitosis, calmodulin was found to be a dynamic component of the mitotic apparatus. calmodulin first appeared in association with the forming mitotic apparatus during midprophase. in metapha ...1979379022
in vitro mutagenicity and cell transformation screening of phenylglycidyl ether.phenylglycidyl ether (1,2-epoxy-3-phenoxy propane) (pge) was tested for genetic activity in bacterial and mammalian tests. it was active in the salmonella/microsome mutagenicity test. concentration-dependent mutagenicity was demonstrated in s. typhimurium strains ta1535 and ta100 with and without rat s9, but not in strains ta98, ta1537, or ta1538. these results suggest pge, is a direct-acting mutagen causing base substitutions. phenylglycidyl ether did not induce 6-thioguanine-resistant mutants ...1979379639
comparison of assay of coliform enterotoxins by conventional techniques versus in vivo intestinal perfusion.thirty-six strains of coliform bacteria were tested for enterotoxigenicity both by conventional assays, including the y-1 adrenal and chinese hamster ovary cell assays for heat-labile toxin and the suckling mouse assay for heat-stable toxin, and by determining the ability of graded concentrations of ultrafiltrate high- or low-molecular-weight toxin preparations to induce water secretion during in vivo perfusion in the rat jejunum. the ultrafiltrates of all 18 strains isolated from persons with i ...1979383611
mutagenicity of 8-ethoxycaffeine in vitro. induction of point mutations in the salmonella/microsome test and of sister-chromatid exchanges as well as chromosomal aberrations in chinese hamster ovary cells (cho line).the caffeine derivative 8-ethoxycaffeine (eoc) was tested in 3 different test systems in vitro. each experiment was carried out with and without s9 mix. incubation temperatures were 20 and 37 degrees c. (1) in the salmonella/microsome test, eoc behaved as a pro-mutagen in the salmonella typhimurium strain ta1535. no mutagenic activity was found in experiments without s9 mix. the influence of temperature was negligible. the mutagenic activity of eoc depended mainly on the mammals used to prepare ...1979384216
defective calcium handling and insulin release in islets from diabetic chinese hamsters.in pancreatic islets from normal chinese hamsters preloaded with 45ca2+, glucose-induced biphasic insulin release was associated with increased 45ca2+ efflux; islets from diabetic hamsters showed decreased insulin release and no increase in 45ca2+ efflux. the lack of stimulated 45ca2+ efflux persisted even when glucose-induced insulin release was potentiated by 3-isobutyl-1-methylxanthine. since glucose-stimulated 45ca2+ uptake by diabetic islets was not impaired, a defect in intracellular ca2+ ...1979384998
mutagenic activity of rhodamine dyes and their impurities as detected by mutation induction in salmonella and dna damage in chinese hamster ovary cells.commercial rhodamine dyes 6g and b induce his+ reversion mutations in salmonella and single-strand breaks in chinese hamster ovary cells, as detected by alkaline sucrose sedimentation. aroclor 1254-induced rat liver homogenate (s9) is required for production of genetic activity by these dyes. rhodamine 6g induces both frameshift and base substitution mutations, whereas rhodamine b induces only frameshift mutations. rhodamine 6g is genetically more active and more toxic than is rhodamine b in bot ...1979387214
differences in mutagenicity and cytotoxicity of (+)- and (-)-benzo[a]pyrene 4,5-oxide: a synergistic interaction of enantiomers.in order to study the biological effects of (+)- and (-)-benzo[a]pyrene 4,5-oxide, a synthesis of these molecules has been developed based on the resolution of (+/-)-cis-4,5-dihydroxy-4,5-dihydrobenzo[a]pyrene. the (-) enantiomer of benzo[a]pyrene 4,5-oxide was 1.5- to 5.5-fold more mutagenic than the (+) enantiomer in strains ta 98, ta 100, ta 1537, and ta 1538 of salmonella typhimurium and in chinese hamster v79 cells. in studies with v79 cells, the (-) enantiomer of benzo[a]pyrene 4,5-oxide w ...1979388437
micrococcus luteus uv-endonuclease-sensitive sites and sister-chromatid exchanges in chinese hamster ovary cells. 1979390381
in vitro mutagenicity and cell-transformation screening of n-(2,3-epoxy-propyl)-phthalimide.n-(2,3-epoxy-propyl)-phthalimide (epp) was tested for genetic activity in the salmonella/microsome mutagenicity test. concentration-dependent mutagenicity was demonstrated in s. typhimurium strains ta1535, ta1537 and ta100 with and without rat s9. it was inactive in strain ta1538, and active without rat s9 in ta98 at the high dose. epp induced 6-thioguanine-resistant mutants of chinese hamster ovary cells in the absence of an exogenous activating system. epp produced dose-dependent enhancement o ...1979390395
mutagenicity studies of 4-(2-carboxyethyl) phenyl trans-4-aminomethylcyclohexane carboxylate hydrochloride (dv-1006). a new antiulcer drug.an antiulcer drug, 4-(2-carboxyethyl) phenyl trans 4-aminomethylcyclohexane carboxylate hydrochloride (dv-1006), was studied for mutagenicity using bacterial systems, in vitro and in vivo cytogenetics, and dominant lethal tests. no mutagenicity of dv-1006 was observed either in the rec-assay on bacillus subtilis or in the salmonella/microsome test (ames test). in in vitro cytogenetics, dv-1006 had no effects on the chromosomes of chinese hamster cells at cytotoxic doses. rats were treated singly ...1979391178
critical importance of microsome concentration in mutagenesis assay with v79 chinese hamster cells.for optimum mutagensis in v79 chinese hamster cells, the amount of liver postmitochondrial fraction in the assay was found to be of critical importance, depending on the chemicals being tested. benzo[a]pyrene (bp) required lower (1-5%) concentrations of the liver 15 000 x g supernatant (s15) from methylcholanthrene pretreated rats for a maximum induction of cytotoxicity and mutagenicity, as determined by 8-azaguanine- and ouabain-resistance. a sharp peak of mutagenicity and cytotoxicity was indu ...1979392309
[recent developments of instrument assisted chromosome analysis with quantimet 720 (author's transl)].the system looks in a short time automatically for good metaphase spreadings. two routines are described which evaluate the relocated metaphases in a semi-automatic way. one routine classifies human chromosomes, using the chromosome area and area ratio of the chromosome arms. the other routine classifies the chromosomes of the chinese hamster. in this routine statistical inputs for chromosome aberrations are possible.1979396456
in vitro mutagenicity and cell transformation screening of caprolactam.caprolactam was tested for genetic activity in bacterial and mammalian screens. it was inactive in the following tests: a) salmonella/microsome mutagenicity; b) chinese hamster ovary cell mutagenicity (induction of 6-thioguanine mutants); c) enhancement of sa7 virus transformation of primary hamster embryo cells, when administered before or after virus, and; d) chemical transformation of secondary hamster embryo cells.1979399920
antibodies against chromosomal hmg proteins stain the cytoplasm of mammalian cells.antibodies specific to protein hmg-1 were purified by affinity chromatography on sepharose columns to which hmg-1 was covalently bound. immunofluorescence studies with these antibodies reveal that hmg-1 or components which immunologically cross-react with hmg-1 are present in the cytoplasm of chinese hamster v-79, rat liver tr-12 and bovine trachea ebtr-nbl-4 cells. at selected antibody concentrations, the fluorescence present in the cytoplasm is more intense than that observed in the nucleus. t ...1979369705
mitomycin c stimulates production of a toxin in shigella species that causes morphological changes in chinese hamster ovary cells.shigella dysenteriae produced a toxin that caused morphological changes in chinese hamster ovary cells which was different from the neurotoxin (y. takeda, k. okamoto, and t. miwatani, infect. immun. 18:546--548, 1977). it was found that the toxin was produced not only by s. dysenteriae but also by s. flexneri, s. boydii, and s. sonnei. the production of the toxin was stimulated by the addition of 1 microgram of mitomycin c per ml to the culture in the early logarithmic growth phase.1979370009
selective toxicity of 6-hydroxydopa for melanoma cells.the growth inhibitory effect of 6-hydroxydopa, a cytotoxic analog of l-dopa, was studied in melanotic and amelanotic cloudman melanoma, mouse fibroblast l929 and chinese hamster ovary cells. a marked sensitivity of pigmented cells to 6-hydroxydopa was observed with a 10-fold increase in sensitivity of pigmented cells. sensitivity correlated with the capacity of cells to incorporate radiolabeled exogenous l-dopa. the drug affected primarily dna and rna synthesis with greater inhibition observed i ...1979422870
the in vitro and in vivo reaction at the n7-position of guanine of the ultimate carcinogen derived from benzolalpyrene.the previously reported reaction at n2- and n7- of guanine following addition of 7 alpha,8 beta-dihydroxy-9 beta, 10 beta-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (anti-bpde) to an aqueous solution of dna has been studied in more detail. the extent of reaction and the relative yields of n2- and n7-products was measured over the range of ph 4--7. the depurination following reaction at the n7-position of guanine was found to have a half-life of 3 h. reaction of the isomeric 7 alpha,8 beta-dihydroxy ...1979428016
visualization of the interphase chromosomes of ornithogalum virens and muntiacus muntjak.a technique for visualizing "interphase chromosomes" was applied to nuclei of the angio-spermous plant, ornithogalum virens (2 n = 6), and the male mammal, muntiacus munjak (2 n = 7), in an attempt to correlate the numbers of "chromosomes" visible during interphase with the respective diploid chromosome numbers. the alterations in chromosome structure observed during g1, s, and g2 periods were comparable to those previously reported in allium cepa and chinese hamster (cho line) cells [33], but f ...1979428620
purine and pyrimidine transport and phosphoribosylation and their interaction in overall uptake by cultured mammalian cells. a re-evaluation.the zero-trans uptake of purines and pyrimidines was measured in suspensions of novikoff rat hepatoma, mouse l, p388 mouse leukemia, and chinese hamster ovary cells by a rapid kinetic technique which allows the determination of uptake time points in intervals as short as 1.5 s. kinetic parameters for purine/pyrimidine transport were determined by measuring substrate influx into cells in which substrate conversion to nucleotides was negligible either due to lack of the appropriate enzymes or to d ...1979429288
identification of a mouse gene required for binding of rauscher mulv envelope gp70.mouse chromosome segregating somatic cell hybrids were established between a mouse thymic leukemai cell line (grsl) and chinese hamster e36 cells. the grsl cells specifically bound purified rauscher leukemia virus gp70 while the e36 cells exhibited no binding. the hybrids selectively bound ruascher gp70 depending on the presence of a mouse cellular gene for the ecotropic murine luekemia gp70 receptor. a syntenic relationship was observed between the dip-3 chromosome marker (on chromosome 5) and ...1979432756
a ts mutant isolated from chl cells: inhibition of dna replication at nonpermissive temperature.a mutant chinese hamster cell clone has been isolated from an s phase culture. this clone, ts154, could not replicate dna at nonpermissive temperature (39 degrees c), although it synthesized dna normally at permissive temperature (33 degrees c). after transfer to 39 degrees, ts154 cells replicated dna semiconservatively through precisely two complete rounds and divided twice before they ceased dna synthesis and further growth. the mutation in ts154 affects dna replication specifically, as its ra ...1979432760
cis-platinum(ii) diamine dichloride causes mutation, transformation, and sister-chromatid exchanges in cultured mammalian cells.the anti-tumor agent cis-platinum(ii) diamine dichloride caused dose-dependent toxicity in v79 chinese hamster cells and in secondary syrian hamster embryo cells. chromosome aberrations were induced and positive dose--response relationships were observed for induction of sister-chromatid exchanges and 6-thioguanine-resistant mutations in v79 cells and morphologic transformation of secondary syrian hamster embryo cells. the findings suggest that this chemical is a potential human carcinogen.1979440327
the influence of testicular microanatomy on the potential genetic dose from internally deposited 239pu citrate in chinese hamster, mouse, and man. 1979441246
thymidine transport in cultured mammalian cells. kinetic analysis, temperature dependence and specificity of the transport system.the transport of thymidine has been characterized kinetically and thermodynamically in novikoff rat hepatoma cells grown in culture and, less extensively, in mouse l cells, chinese hamster ovary cells, p388 murine leukemia cells and hela cells. that the characterizations pertained to the transport system per se was ensured, (i) by employing recently developed methods for rapid sampling of cell/substrate mixtures in order to follow isotope movements within a few seconds after initial exposure of ...1979444518
dna fork displacement rates in synchronous aneuploid and diploid mammalian cells.dna fork displacement rates were measured in chinese hamster ovary cells (cho), human hela cells and human diploid fibroblasts. for cho cells two independent techniques were used: one based on cscl equilibrium density gradients and the other on 313 nm photolysis of incorporated bromodeoxyuridine (brdurd). both methods indicated that there was no significant variation in fork displacement rates in cho cells as they progressed through s phase. asynchronous cho cultures displayed the same average v ...1979444527
stages in the prenatal development of the chinese hamster (cricetulus griseus).a system of staging embryos is described for the chinese hamster (cricetulus griseus). this system of staging, based on streeter's developmental horizons in human embryos, comprises three sets of criteria: 1) data on postconceptional age, size and number of somites, 2) external characteristics and 3) internal characteristics. a comparison has been made with data in mouse (theiler, 1972) as well as in primates. it seems that the order of organogenesis, i.e. the sequence in which individual organs ...1979453550
association of human chromosome 14 with a ts defect in g1 of chinese hamster k12 cells.somatic cell hybrids between human lymphoblastoid cells (raji) and temperature-sensitive chinese hamster cells (k12) were selected from monolayer cultures in mem at 40 degrees c. a total of 21 hybrid clones were isolated and karyotyped. all clones contained a near complete set of chinese hamster chromosomes and 1 to 5 human chromosomes. human chromosome 14 present in the hybrid cells of all clones; and was the only human chromosome retained in 10 clones. the presence of human chromosome 14 in hy ...1979455493
induction of sister-chromatid exchanges in human lymphocytes and chinese hamster cells exposed to aflatoxin b1 and n-methyl-n-nitrosourea.the effect of a 1-h exposure to aflatoxin b1 (afb1) in inducing sister-chromatid exchange in chinese hamster ovary (cho) cells and human lymphocytes in the presence or absence of mixed function oxidase ("s9 mix") was compared. cho cells were also exposed to a graded series of doses of n-methyl-n-nitrosourea, a powerful inducer of sce whose action was independent of the presence or absence of s9 mix. cho and human cells showed a close correlation in response to sce induction by afb1 and in both c ...1979460293
the excision of n-methyl-n-nitrosourea-induced lesions from the dna of chinese hamster cells as measured by the loss of sites sensitive to an enzyme extract that excises 3-methylpurines but not o6-methylguanine.an enzyme extract from micrococcus luteus excises 3-methyladenine and 3-methylguanine but not o6-methylguanine, 7-methylguanine, 1-methyladenine or 7-methyladenine from dna reacted with n-methyl-n-nitrosourea. the extract was used to detect lesions in the dna of chinese hamster cells treated in culture with n-methyl-n-nitrosourea. it was concluded that 3-methyladenine is excised from these cells with a half-life of about 2.3 h.1979467426
mutagenicity of quercetin and kaempferol on cultured mammalian cells.mutagenic activity of quercetin and kaempferol on v79 chinese hamster cells was investigated. quercetin was proved to have mutagenicity not only by metabolic activation system using rat liver microsomes, but also by direct application method. kaempferol was mutagenic by metabolic activation system, but its activity by direct method seemed very low. these data suggest that the tested flavonoids seem to be metabolized for exerting their mutagenic activity and v79 cells themselves have an enzymic a ...1979467892
mutagenicity of vinyl chloride, vinylidene chloride and chloroprene in v79 chinese hamster cells.the mutagenicity of vinyl chloride, vinylidene chloride (1,1-dichloroethylene) and chloroprene (2-chloro-1,3-butadiene) was tested in v79 chinese hamster cells in the presence of a 15 000 x g liver supernatant from phenobarbitone-pre-treated rats and mice. mutations in terms of 8-azaguanine and ouabain resistance were induced in a dose-related fasion by exposure to vapour of vinyl chloride in the presence of liver supernatant from phenobarbitone-pretreated rats. vapours of vinylidene chloride an ...1979470972
mutagenicity testing on chinese hamster v79 cells treated in the in vitro liver perfusion system. comparative investigation of different in vitro metabolising systems with dimethylnitrosamine and benzo[a]pyrene.a comparative study of three in vitro metabolising systems was performed in combination with chinese hamster v79 cells, at which point mutation to 6-thioguanine resistance was scored. the three metabolising systems used were: (1) rat liver microsomal fraction (s9-mix); (2) feeder layer of primary embryonic golden hamster cells, according to hubermann's system; (3) in vitro perfusion of rat liver according to the system of beije et al. as model substances dimethylnitrosamine (dmn) and benzo[a]pyr ...1979476853
regional assignment of human genes tpi1, gapdh, ldhb, shmt, and pepb on chromosome 12.karyological analysis was performed on a series of human-chinese hamster cell hybrids containing deletions of human chromosome 12. chromosome breakage was produced by treatment of the cells with either x-rays or 5-bromodeoxyuridine and near-visible light. the hybrid clones were analyzed for the presence or absence of the following five human gene markers known to be located on chromosome 12: triosephosphate isomerase-1 (tpi1), glyceraldehyde-3-phosphate dehydrogenase (gapdh), lactate dehydrogen ...1979477403
pattern of segregation of chicken hprt phenotype in chinese hamster-chick red blood cell hybrids.the pattern of segregation of hypoxanthine phosphoribosyltransferase (hprt, e.c. 2.4.2.8) was determined in synchronized chinese hamster-chick red blood cell hybrids. three hybrid lines were synchronized at the g1-s boundary. bromodeoxyuridine pulses were subsequently applied throughout the s phase, and the frequency of the segregant clones was determined. it was found that the segregation of the chicken-specific hprt phenotype associated with the loss of a chromosome was potentiated by bromodeo ...1979477410
insensitivity of a ricin-resistant mutant of chinese hamster ovary cells to fusion induced by newcastle disease virus.the role of membrane components in the interaction of cells with newcastle disease virus (ndv) was studied using a ricin-resistant mutant of chinese hamster ovary cells (cho-15b), in which there is a deficiency in distal saccharides at the plasma membrane. compared to the parental wild type, the mutant was shown to be 4- to 10-fold less sensitive to either fusion from without or fusion from within induced by ndv. the mutant and wild type were nearly indistinguishable with respect to other intera ...1979480463
vitamin c is positive in the dna synthesis inhibition and sister-chromatid exchange tests.ascorbate caused a dose-dependent increase in sister-chromatid exchanges (sces) in chinese hamster ovary (cho) cells and in human lymphocytes. moreover, in the dna synthesis inhibition test with hela cells, ascorbate gave results typical of dna-damaging chemicals. catalase reduced sce induction by ascorbate, prevented its cytotoxicity in cho cells, and prevented its effect on hela dna synthesis. ascorbate reduced induction of sce in cho cells by n-methyl-n'-nitro-n-nitrosoguanidine (mnng) by dir ...1979481430
mutagenicity of 8-methoxypsoralen and long-wave ultraviolet irradiation in v-79 chinese hamster cells. a first approach to a risk estimate in photochemotherapy.the effect of 8-methoxypsoralen (8-mop) and long-wave ultraviolet irradiation (uva) on cell killing and mutation induction was studied in v-79 chinese hamster cells. no effect was observed after treatment with 8-mop alone (50 microgram/ml, 4 h), uva alone (9000 j/m2), or 8-mop metabolized by rat-liver microsomes. combined treatment with 8-mop and uva induced both cell killing and mutation. this was also observed under conditions approaching patient treatment with puva photochemotherapy with resp ...1979481433
activity of citrinin metabolized by rat and human microsome fractions in clastogenicity and sce assays on chinese hamster v79-e cells.the mycotoxin citrinin is a potent inducer of chromosomal aberrations in the clastogenicity assay on v79-e cells when metabolized by rat and human liver microsomes. rat and human liver microsomes, standardized on protein content, activate citrinin at equal levels. 5 x 10(-4) m citrinin induces complex translocations in a high frequency as well as defects of chromosomal coiling. higher concentrations are cytotoxic, lower ones are almost inactive. after metabolization of mycotoxin by rat-kidney mi ...1979481457
the effect of aphidicolin on adenovirus dna synthesis.aphidicolin inhibits adenovirus dna replication in hela cells and in a cell-free, infected, nuclear extract in which viral dna is elongated. the compound inhibits alpha dna polymerase, extensively purified from hela cells, but has little or no effect on the beta or gamma dna polymerases similarly purified. aphidicolin does not affect thymidine uptake by cells nor does synthesis as it also inhibits dna replication in uninfected cells. the inhibition by aphidicolin is reversible if the drug is rem ...1979482131
misonidazole and mtdq in combination: cytotoxic and radiosensitizing properties in hypoxic mammalian cells.a combination of misonidazole and mtdq (6,6'-methylene-bis-2,2,4 trimethyl-1,2-dihydroquinoline) has been tested for its radiation-sensitizing properties and cytotoxicity, using chinese hamster v79 cells cultured in vitro. both compounds sensitize hypoxic cells to the effects of x-rays, and when used in combination their sensitizing properties are additive. by contrast, the presence of mtdq completely inhibits the cytotoxicity that misonidazole exhibits towards hypoxic cells. these experiments s ...1979486306
cycloheximide-resistance in chinese hamster ovary cells and human fibroblast cells. cytogenetic and biochemical characterization.cycloheximide(chm)-resistant mutant chinese hamster ovary (cho) and human cells were induced with n-nitrosomethylurea (nmu) and ethyl methanesulfonate (ems); the mutants were viable and showed unlimited growth in the presence of chm (7 x 10(-7) m), whereas this concentration inhibits protein synthesis in vivo as well as in vitro. no numerical or structural chromosomal aberrations were found in the mutant cells. in vitro analysis shows that the ribosomes confer resistance against cycloheximide.1979489015
chromosome breaking activity of human feces and its enhancement by transition metals.chloroform-methanol extracts from human fecal samples were found to contain compounds which induce chromosome aberrations in chinese hamster ovary cells. the induction of chromosome aberrations is stimulated by cu2+ or mn2+ and inhibited by fe2+ or fe3+. addition of catalase to the fecal extract or the mixture of fecal extract and mn2+ reduced the frequency of chromosome aberrations. these properties are indicative of hydroxyradical producing agents.1979489168
correlation between cell cycle duration and rna content.the metachromatic fluorochrome acridine orange was used to differentially stain dna and rna in chinese hamster ovary (cho) cells and in mitogen-stimulated human lymphocytes during their progression through the cell cycle. green and red fluorescence of individual cells, representing cellular dna and rna, respectively, was measured by flow cytometry. cho cells were synchronized by selective detachment at mitosis. their rate of progression through g1 and subsequently through s phase correlated with ...1979489667
characterization of the diphtheria toxin-resistance system in chinese hamster ovary cells.variations in two general classes of diphtheria toxin-resistant mutants which may be selected from chinese hamster ovary (ch0-k1) cells and the conditions for their selection are described. the resistance of class i mutants can be overcome with increasing concentrations of toxin. their entire complement of ef-2 is susceptible to adp-ribosylation by toxin. class i includes those strains in which resistance resides at the level of the plasma membrane. the resistance of class ii, translational, mut ...1979494060
sperm-cell multinucleates in chinese hamster ovary cells penetrated with rat spermatozoa. 1979498198
two-dimensional analysis of proteins associated with heterogenous nuclear rna in various animal cell lines.the protein complement of heterogenous nuclear rna . protein particles from human hela, mouse l and chinese hamster (cho) cells has been analysed by two-dimensional gel electrophoresis using the two techniques described by o'farrell [j. biol. chem. (1975) 250, 4007--4021 and cell (1977) 12, 1133--1142]. over a hundred individual spots habe been reproducibly detected both l-[35s]methionine. large similarities, especially in the 25 000--40 000 mr cluster of basic protein, were found among these th ...1979499201
activity of both mouse and chinese hamster ribosomal rna genes in somatic cell hybrids. 1979499371
induction of ouabain-resistant mutation and sister chromatid exchanges in chinese hamster cells with chemical carcinogens mediated by human pulmonary macrophages.pulmonary macrophages (pam) metabolically activated benzo[a]pyrene [b(a)p] and its proximate carcinogenic metabolite, (+/-)trans 7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene (7,8-diol), to ultimate mutagens that were detected in cocultivated chinese hamster v79 cells. increases in the frequency of ouabainresistant (o(r)) mutations and sister chromatid exchanges were found in v79 cells only when they were cocultivated with both pam and the chemical procarcinogens. 7,8-diol caused higher frequencies of ...1979500808
sister chromatid exchanges induced in cultured mammalian cells by chromate.chromate compounds induced sister chromatoid exchanges (sces) and chromosome aberrations in cultured mammalian cells. similar increases in sce frequency were observed in human fibroblasts exposed to the compounds k2cr2o7 and k2cro4. marked increases in sce frequency in cells exposed to chromate for a 48-h period were detected at concentrations between 10(-7) and 10(-6) m. chromosome aberrations (primarily chromatid breaks) were also produced in human cells exposed to k2cro4 at concentrations bet ...1979509691
effects of styrene oxide on chromosome aberrations, sister chromatid exchange and hepatic drug biotransformation in chinese hamsters in vivo.in vivo inhalation exposure to styrene oxide (25, 50, 75 and 100 ppm) for 2, 4 or 20 days (25 ppm only) had no effects on chromosomal aberration rates or sister chromatid exchange (sce) frequencies (brdu/labelling performed in vitro) in the bone marrow cells of chinese hamsters. the only positive response in aberration frequency was obtained when styrene oxide was injected in lethal concentration (500 mg/kg body weight, i.p.) into the animal. one animal out of six showed slightly elevated sce va ...1979509693
culture of adult rat lung cells: benzo(a)pyrene metabolism and mutagenesis.a method is described for obtaining and culturing large numbers of lung cells from normal adult male rats. the lungs were perfused in situ to remove blood cells and then perfused via the trachea with a trypsin-collagenase solution to initiate tissue digestion. the tissue was further digested in the enzyme solution and approximately 2 x 10(8) viable lung cells were obtained per animal. primary cultures contained a mixed cell population. through eight subcultures about 70% of the cell population p ...1979511205
amosite, chrysotile and crocidolite asbestos are mutagenic in chinese hamster lung cells.chinese hamster lung cells cultured in the presence of amosite, chrysotile or crocidolite displayed inhibition of cell growth. phagocytosis of asbestos by cells was observed. amosite and chrysotile appeared to be twice as toxic as crocidolite based on an equal weight/volume basis. induction of 6-thioguanine resistance was studied. after treatment at 10 microgram/cm2 for 24 h, and with a 48-h expression time, numerically the cells did not change significantly from 6-thioguanine-sensitive to 6-thi ...1979514306
detection of small amounts of human dna in human-rodent hybrids.a method of measuring semi-quantitatively small amounts of human dna in irradiated human x mouse and irradiated human x chinese-hamster somatic cell hybrids is described. one method uses molecular hybridization of cell dna bound to nitrocellulose filters with a crna probe to cot 0--1 human dna. alternatively hybrid cell dna is reassociated in solution with a cot 0--1 fraction of nick-translated human dna. formamide buffers give specificity to the reaction. the detection limit of the filter metho ...1979521473
the mechanism of action of cis-dichloro-bis (isopropylamine) trans dihydroxyplatinum iv (chip) on chinese hamster and c3h mouse tumor cells and its interaction with x-irradiation. 1979528286
adaptation of the influenza virus a2-pol 29/69 to the cells of the chinese hamster lung (chl) and to the cells bhk-21.in the course of research of the possibilities of adapting the influenza virus serotype a 2-pol 29/69 to bhk-21 and chl cells its production was established in the investigated combinations. an indication of virus replication is an increase in infectious and haemagglutination titres within 48 h after infection and gradual increase in haemadsorption. observation of the influence of trypsin (10 microgram/ml) indicates that trypsin increases the capability of viruses to penetrate the cells. the cyt ...1979535814
selecting interspecific human-mouse and chinese hamster-mouse hybrids using a new half-selection technique with a polyene antibiotic.interspecific human-mouse and chinese hamster-mouse hybrids were isolated from polyethylene glycol fused cells by a new half-selection technique employing a structurally modified polyene macrolide antibiotic, amphotericin b methyl ester (ame), and hat media. unfused parental cells were killed as a result of innate sensitivity to ame or their genetic deficiency, absence of thymidine kinase (tk-) or hypoxanthine guanine-phosphoribosyl transferase (hgprt-). in contrast, hybrid colonies were isolate ...1979541268
isolation and characterization of tunicamycin resistant mutants from chinese hamster ovary cells.stable clones selected for resistance to tunicamycin (tm) have been isolated from chinese hamster ovary (cho) cells. the tmr phenotype is stable for more than nine months in the absence of the drug. the morphology of tmr mutant varies from epitheloid to abnormally elongate. the mutants do not display cross-resistance for cona but are slightly cross-resistant to pha. biochemically labeled membrane proteins and glycoprotein of vesicular stomatitis virus (vsv) grown in the tmr mutants revealed that ...1979541348
genetic transmission of moloney leukemia virus: mapping of the chromosomal integration site.mice genetically transmitting the exogenous moloney leukemia virus (balb/mo) have been previously derived. these animals carried one copy of moloney virus dna (m-mulv) in their germ line and transmitted the virus as a single mendelian gene to the next generation. homozygous balb/mo mice were used to genetically map the m-mulv locus. embryo fibroblasts were fused to established chinese hamster cells and somatic cell hybrids were selected. segregation of mouse chromosomal markers in the hybrids wa ...1979544367
destruction of bacterial viruses in serum by heat and radiation under conditions that sustain the ability of serum to support growth of cells in suspended culture.methods for inactivating bacterial viruses in serum were developed through the use of heat and ionizing radiation, and the effects of these treatments on the growth rates of cultured cells were tested. viruses chosen for this study were the radiation-resistant bacteriphage f2 and heat-resistant phage t4. the viabilities of these phages were reduced more than 2 and 4 orders of magnitude, respectively, by a treatment at 60 degrees c for 30 min followed by 420 krads of ionizing radiation. simultane ...1979544633
production of monoclonal antibodies against a cell surface concanavalin a binding glycoprotein.concanavalin a-binding (con-a)-binding cell surface glycoproteins were isolated, via con a-affinity chromatography, from triton x-100-solubilized chinese hamster ovary (cho) cell plasma membranes. the con a binding glycoproteins isolated in this manner displayed a significantly different profile on sodium dodecyl sulfate--polyacrylamide gels than did the triton-soluble surface components, which were not retarded by the con-a-sepharose column. [125i]-con a overlays of the pooled column fractions ...1979544930
direct linkage of thrombin to its cell surface receptors in different cell types.when 125i-thrombin was incubated with foreskin fibroblasts, cervical carcinoma cells or fibrosarcoma cells of human origin, or with secondary chick embryo cells or chinese hamster lung cells, it became directly linked to its cell surface receptors. the thrombin-receptor complex (th-r) was derived exclusively from a pool of 125i-thrombin that had become specifically bound to the cell surface. the linkage was probably covalent, since the complex was resistant to boiling in sodium dodecyl sulfate a ...1979544938
somatic cell genetic analysis of transgenome integration.the site of association of the human transgenome and host murine chromosomes was determined in several subclones of a stable human/mouse transformed cell line. chromosomes were transferred from each of three transformed subclones into chinese hamster recipient cells, and selection was applied for the expression of human transgenome-encoded hprt. a series of trispecific microcell hybrids was isolated and characterized for each subclone. evidence is presented that, within a given transformed subc ...1979545718
methods to evaluate the effects of toxic materials deposited in the lung on immunity in lung-associated lymph nodes.intratracheal instillation of sheep red blood cells (srbc) induced a primary immune response in lung-associated lymph nodes of chinese hamsters and fischer-344 rats. few or no anti-srbc antibody forming cells (afc) were found in the spleen or cervical lymph nodes after intratracheal immunization. the number of afc was significantly suppressed in the lung-associated lymph nodes from hamsters exposed by inhalation of 239puo2 and in rats exposed by intratracheal instillation of benzo(a)pyrene (bap) ...1979548254
transcription and hybridization of 125i-crna from flow sorted chromosomes.metaphase chromosomes from the chinese hamster cell line m3-1 were separated by means of a flow sorter. two chromosome fractions were used for this study: a, which consisted of 95% pure chromosome no. 1, and b, which was 90% pure chromosome no. 2. the dna of 10(6) chromosomes of each type was purified, and a 125i-crna transcript was synthesized in a reaction containing e. coli rna polymerase and carrier-free 125i-ctp (1.7 ci/mumole). the crna product synthesized with template dna from 10(5) sort ...1979428270
organ-specific mutations in chinese hamsters induced by chemical carcinogens. 1979293496
possible mutagenic activity of saccharin.a mutagenic effect of saccharin in chinese hamsters, using the in vivo sce test, was observed when massive overdoses were administered; cyclamate was not mutagenic.1979499424
proliferation of lung and airway cells induced by nitrogen dioxide.proliferation of lung cells of chinese hamsters was examined in several regions of the lung parenchyma and ciliated airway epithelium after a 24-h exposure to 28.2 mg/m3 (15 ppm) nitrogen dioxide (no2). label was retained 3 wk after the injection of [3h]thymidine, and autoradiographic methods were used to localize the site of retention. by 24 h after administration of [3h]thymidine, parenchymal areas, exclusive of airways, showed an increased labeling index, indicative of cell death and replacem ...1979513156
effect of continuous low-dose insulin treatment on subsequent incidence of diabetes in genetically prediabetic chinese hamsters.in an attempt to prevent the onset of diabetes, young, genetically prediabetic (but not yet hyperglycemic) chinese hamsters were treated continuously with insulin via minipump for 4 wk beginning 1 wk before the predicted age of onset of glucosuria (age 7 wk). continuous insulin infusion which increased the plasma insulin levels by 70%, did not cause hypoglycemia, nor did it reduce the incidence or severity of diabetic symptoms over the ensuing year of observation. in fact, early treatment with e ...1979446913
endocrine factors contributing to the ethanol preferences of rodents.groups of c57 bl/6j mice (alcohol preferring) and dba/2j mice (alcohol avoiding) were fasted for 24 hours and administered glucose. at 30, 120 and 300 minutes after glucose, the c57 bl/6j mice had significantly higher levels of plasma glucose than the dba/2j strain. these differences were observed in comparable groups given either forced access or no access to alcohol. in ad lib fed animals never exposed to alcohol, c57 bl/6j mice had higher levels of plasma insulin than dba/2j mice. plasma leve ...1979572551
the effect of lucanthone on the radiation response of intestinal stem cells in chinese hamsters.crypt microcolony assay was used to determine the effect of lucanthone on the radiation response of intestinal stem cells in chinese hamsters . the dq of the crypt microcolony radiation--survival curve was maximally reduced by 205 rads when lucanthone injection preceded irradiation by 10 hours and was reduced by 140 rads when injection followed irradiation by 5 hours. on simultaneous injection and irradiation, dq was reduced by only 20 rads; when injection and irradiation were separated by appro ...1979760168
absence of povidone-iodine-induced mutagenicity in mice and hamsters.povidone-iodine usp was tested for mutagenicity in mice by the dominant lethal assay or micronucleus test and in chinese hamsters by the bone marrow test. none of the three tests revealed any evidence of mutagenic effect.1979758440
[an assessement of the in vivo sister chromatid exchange (sce)-test using various cytostatics (author's transl)].five cytostatics of different chemical structure and pharmacological action were used on chinese hamsters (bone marrow cells) to test the efficiency and validity of the in vivo sister chromatid exchange (sce)-test as an indicator of mutagenicity. these model substances, all of which had previously shown a mutagenic effect in one or the other of the various in vivo test systems, gave positive results in this test, too, with the exception of bleomycin. on the basis of the lowest effective dose and ...1979546426
mutagenicity of polycyclic hydrocarbons iii. monitoring genetic hazards of benz(a)anthracene.mutagenicity tests (micronucleus test and chromosome aberrations) have been performed with benz (a) anthracene in spermatogonia and bond marrow cells of chinese hamsters and in nmri mice oocytes. mutagenic effects of the polycyclic hydrocarbon could be demonstrated.1979532719
the influence of ethanol treatment of cytogenetic effects in bone marrow cells of chinese hamsters by cyclophosphamide, aflatoxin b1 and patulin.chromosomes were investigated from the bone marrow of chinese hamsters which received 10% (v/v) ethanol as the only liquid supply for a period of 9 weeks. at the end of the ethanol drinking period 1 group of animals received 2 oral doses of 80 mg/kg cyclophosphamide (cp), a second group received 2 oral doses of 25 mg/kg aflatoxin b1 (afb1), a third group 2 oral doses of 20 mg/kg patulin (pa). the 2 applications were separated by 24 h. the intake of ethanol had no effect on the bone marrow chromo ...1979473226
effect of diet limitation on development of diabetes in non-hyperphagic prediabetic chinese hamsters. 1979386727
organotropic mutagenesis in tissues of chinese hamsters induced by chemical carcinogens.in order to investigate the relationship between mutation and carcinogenesis in vivo, a method has been developed in which somatic mutation can be studied in specific organs of chinese hamsters after acute dosing with chemical carcinogens. in preliminary experiments an increase in mutation was detected in cultures derived from lung tissue of hamsters after intraperitoneal dosing with the direct-acting mutagen and weak carcinogen, ethyl methanesulphonate, or with diethylnitrosamine, a carcinogen ...1979223525
acetylation of spermidine in chinese hamster ovary cells. 19807213369
synthesis of the n-linked oligosaccharides of glycoproteins. assembly of the lipid-linked precursor oligosaccharide and its relation to protein synthesis in vivo.the asparagine-linked oligosaccharides of chick embryo fibroblast glycoproteins were previously shown to derive from a common lipid-linked precursor, glc3man9glcnac2. the formation of this precursor oligosaccharide was examined in intact chick embryo fibroblasts, nil-8 cells, and chinese hamster ovary cells. the labeling kinetics and compositions of the lipid-linked oligosaccharides were examined, and the results indicate that lipid-linked man5glcnac2 is rapidly assembled (< 1.5 min) and then ex ...19807440570
the use of a quantimet image analysis system to analyse trypsin banding patterns of v79/4 (ah1) chinese hamster chromosomes.a quantimet image-analysis system was programmed to identify and print out banding patterns from g-banded chromosome spreads of a clone derived from the established cell line v79/4 (chinese hamster fibroblasts), designated v79/4(ah1).19807202638
comparative studies of zinc metabolism in cultured chinese hamster cells with differing metallothionein-induction capacities.previous work in our laboratory led to the isolation of a cadmium (cd)-resistant variant (cd(r)2c10) of the line cho chinese hamster cell having a 10-fold greater resistance to the cytotoxic action of cd(2+) compared with the cho cell. this resistance was attributed to an increased capacity of the cd(2+)-resistant cd(r)2c10 subline to induce synthesis of the cd(2+)- and zn(2+)-binding protein(s), metallothionein(s) (mt). evidence that cd(2+) behaves as an analog of the essential trace metal, zn( ...198024271403
a genetic complementation study of purine analogue resistance in chinese hamster fibroblasts. 19807464849
relationship between chemical damage of dna and mutations in mammalian cells. i. dose-response curves for the induction of 6-thioguanine-resistant mutants by low doses of monofunctional alkylating agents, x-rays and uv radiation in v79 chinese hamster cells.the shape of the dose-response curve for mutations induced at low doses of mutagenic agents in mammalian cells was studied. with the exception of x-rays and mms, which are very toxic in relation to their mutagenic potency, dose-response studies with ems, mnu, enu and uv radiation were performed at doses giving about 100% survival. the results from several experiments were pooled for each agent to get higher resolution power at low doses, and the result was compared with what could be expected wh ...19807464843
in vivo interaction of anti-cancer drugs with misonidazole or metronidazole: cyclophosphamide and bcnu.the addition of misonidazole (miso) or metronidazole (metro) to treatment with cyclophosphamide (cy) increased delay to regrowth of 2 experimental tumours. the effect was observed for large an small tumours, was present for doses of miso that are ineffective for killing hypoxic cells, and required that it be given with, or shortly before cy. mice receiving combined treatment had more weight loss and myelosuppression than those receiving cy alone, and the therapeutic index was lower. miso caused ...19807459221
a proposed operational model of thermotolerance based on effects of nutrients and the initial treatment temperature.the phenomenon of thermotolerance in mammalian cells has been extensively documented in the literature. because of its potential clinical importance as well as the fundamental biological interest, we pursued additional studies investigating ph and nutritional effects. split-dose experiments were performed using plateau phase chinese hamster ha-1 cells. the effects of the nutritional environment during the initial 43 degrees incubation and the second 43 degree treatment on the induction of thermo ...19807438083
inhibition of mutagenesis in chinese hamster v-79 cells by antioxidants.the mutagenicity of benzo(a)pyrene (bp) on chinese hamster v-79 cells cocultivated with x-irradiated hamster embryo cells was inhibited by phenolic antioxidants, such as tert-butyl-4-hydroxyanisole (bha) and butyl-hydroxytoluene (bht), but not by disulfiram and its related compounds such as tetraethylthiuram disulfide, diethyldithiocarbamic acid and dimethyldithiocarbamic acid. the mutagenicity of bp on v-79 cells was reduced 44% by bha and 25% by bht. bha inhibited bp-induced mutagenesis, but n ...19807292522
selection of mitotic chinese hamster ovary cells from microcarriers. 19807224150
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