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initiation points for dna replication in nontransformed and simian virus 40-transformed chinese hamster lung cells.randomly growing chinese hamster lung cells were pulse-labeled with 3h-thymidine, and the replicating forks of individual dna fibers were visualized by autoradiography. when grown in complete medium, wild-type sv40-transformed cells had more forks per unit length of dna than nontransformed cells. in isoleucine-depleted medium, wild-type sv40-transformed cells had fewer forks per unit length than those few nontransformed cells (1-3% of the population) which continued dna replication. cells transf ...1977196764
synteny of the genes for thymidine kinase and galactokinase in the mouse and their assignment to mouse chromosome 11.we have studied the expression of mouse galactokinase in human-mouse somatic cell hybrids segregating mouse chromosomes. since concordant segregation of the expression of mouse galactokinase and the presence of mouse chromosome 11 were observed in the hybrid clones, we conclude that the gene for mouse galactokinase is located on mouse chromosome 11. we have also investigated the expression of mouse galactokinase in somatic cell hybrids between thymidine kinase-deficient chinese hamster cells and ...1977196814
effect of staphylococcus aureus delta toxin on chinese hamster ovary cell morphology and y-1 adrenal cell morphology and steroidogenesis.since staphylococcus aureus delta toxin previously had been shown to increase the cyclic adenosine 3',5'-monophosphate (camp) content of guinea pig ileum, the effect of delta toxin on such camp-mediated responses as morphogenesis and steroidogenesis in cultured tissue cells was examined. in contrast to cholera toxin, delta toxin did not cause spindling of chinese hamster ovary cells. unlike adrenocorticotropin or cholera toxin, delta toxin was unable to cause rounding of y-1 adrenal cells or to ...1977197006
gene mapping in mus musculus by interspecific cell hybridization: assignment of the genes for tripeptidase-1 to chromosome 10, dipeptidase-2 to chromosome 18, acid phosphatase-1 to chromosome 12, and adenylate kinase-1 to chromosome 2.chinese hamster x mouse somatic cell hybrids segregating mouse chromosomes were examined for their mouse chromosome content using trypsin-giemsa (gtg) banding and hoechst 33258 staining techniques. simultaneously, they were scored for the presence of 24 mouse enzymes. the results confirm the assignments of 11 genes previously mapped by sexual genetics: dip-1 and id-1 to chromosome 1; pgm-2 and pgd to 4; pgm-1 to 5; gpi-1 to 7; gr-1 to 8; mpi-1 and mod-1 to 9; np-1 and es-10 to 14. they also conf ...1977198184
chromosomal alterations in a chinese hamster cell line transformed in vitro by sv40 virus. 1977200554
a comparison of camp phosphodiesterases in normal, malignant, and somatic cell hybrids.hybrids (pcm) between a malignant mouse lymphoma suspension cell line (p388f-36) and a normal chinese hamster fibroblastic cell line (ch23) have already been isolated in this laboratory. investigations were carried out on the camp phospodiesterases of the parents and two of these hybrids--pcm2 and pcm3. pcm3 shows a rather unusual growth characteristic in that a considerable proportion of the cells exist at any one time either in suspension or only loosely attached to the substratum, the remaini ...1977201244
an investigation of the homology of guanylate kinase isozymes in mammals and further evidence for multiple guk gene loci.guanylate kinase in the red cells of 63 different mammalian species was studied by electrophoresis and multiple molecular forms of the enzyme were found in all species. two species were investigated in more detail. using molecular weight estimates as a criterion of homology, the fallow deer and the chinese hamster were found to have isozymes that corresponded to isozyme e, f, and g of man. variation in the guanylate kinase isozymes was detected in a small population of orangutans. results sugges ...1977201245
virus production with a newly developed microcarrier system.primary cell cultures as well as established lines have been grown on a recently developed microcarrier configuration that overcomes the problem of toxicity attendant on earlier developments in this technology. virus yields from these cells propagated on the new microcarriers have been measured. microcarrier-grown cells, when compared to roller-bottle-grown cells, gave virus yields on a per-cell basis that varied from slightly greater with the sindbis virus-chinese hamster ovary cells and polio- ...1977202193
assignment of the genes for thymidine kinase and galactokinase to mus musculus chromosome 11 and the preferential segregation of this chromosome in chinese hamster/mouse somatic cell hybrids. 1977204065
transfer of the human genes coding for thymidine kinase and galactokinase to chinese hamster cells and human-chinese hamster cell hybrids.cotransfer of two linked human genes, coding for the enzymes thymidine kinase (tk) and galactokinase (gak) was demonstrated following incubation of chinese hamster tk-deficient cells with isolated human chromosomes. the 5 colonies which were isolated all expressed a stable tk-positive phenotype. cotransfer of the human genes coding for tk and gak has also been observed in experiments in which isolated human chromosomes were incubated with tk-deficient human-chinese hamster cell hybrids. these re ...1977204067
microcell-mediated transfer of murine chromosomes into mouse, chinese hamster, and human somatic cells.in this report, we describe the production and characterization of proliferating hybrid cell populations generated by fusion of murine microcells with intact mouse, chinese hamster, and human recipient cells. the microcell hybrids so produced contained one to five intact murine chromosomes derived from the microcell donor. these transferred chromosomes were maintained as functioning genetic elements in the hybrid cells. our results firmly establish subnuclear particle-mediated chromosome transfe ...1977264685
assignment of the major histocompatibility complex to a region of the short arm of human chromosome 6.interspecific cell hybrids containing defined parts of human chromosome 6 were used for regional mapping of gene loci previously assigned to chromosome 6: the human leukocyte antigens (hla) region, phosphoglucomutase-3 (pgm3; alpha-d-glucose-1,6-bisphosphate:alpha-d-glucose-1-phosphate phosphotransferase, ec 2.7.5.1) and malic enzyme-1 [malic dehydrogenase(decarboxylating) (nadp+), l-malate:nadp+ oxidoreductase (oxaloacetate-decarboxylating), ec 1.1.1.40]. human fibroblasts containing a balanced ...1977265561
serial transfer of a human gene to rodent cells by sequential chromosome-mediated gene transfer.the human hypoxanthine phosphoribosyl-transferase (imp:pyrophosphate phosphoribosyltransferase, ec 2.4.2.8) gene (hprt) has been serially transferred to mouse cells and then to chinese hamster fibroblasts by two cycles of metaphase chromosome isolation and incubation with recipient cells. human metaphase chromosomes were incubated with mouse a9 cells deficient in hypoxanthine phosphoribosyltransferase, and independent colonies expressing the human species form of this gene were isolated in a sel ...1977268645
stable association of the human transgenome and host murine chromosomes demonstrated with trispecific microcell hybrids.trispecific microcell hybrids were prepared by transferring limited numbers of chromosomes from a human/mouse gene-transfer cell line to a chinese hamster recipient line. the donor cells employed were murine l-cells that stably expressed the human form of the enzyme hypoxanthine phosphoribosyltransferase. karyotypic, zymographic, and back-selection tests of the resulting human/mouse/chinese hamster microcell hybrids provided strong genetic evidence for a stable association of the human transgeno ...1977269444
assignment of the human gene for galactose-1-phosphate uridyltransferase to chromosome 9: studies with chinese hamster-human somatic cell hybrids.chinese hamster-human somatic cell hybrids were analyzed for the expression of human galactose-1-phosphate uridyltransferase (galt; udpglucose:alpha-d-galactose-1-phosphate uridyltransferase, ec 2.7.7.12) by electrophoresis and for the presence of human chromosomes cytogenetically with the aid of q-banding. three of the 10 randomly chosen independently derived primary hybrid lines showed the presence of human galt. human chromosome 9 was consistently present in the hybrid lines expressing human ...1977271990
cyclic amp and insulin release.the role of cyclic adenosine-3',5'-monophosphate (camp) for insulin secretion has been investigated. in isolated islets of langerhans from the rat, glucose increases camp concomitant with insulin secretion. stimulation of these two parameters is likewise reversible in parallel. the minimal and maximal concentrations of glucose eliciting camp and insulin responses are similar. isomers and epimers of glucose influence insulin and camp in a parallel fashion as do sulfonylurea compounds (tolbutamide ...1977210617
rescue of marker phenotypes mediated by somatic cell hybridization.the effect of irradiation prior to virus-induced cell fusion on the frequency of hybrid production has been measured as a function of radiation dose. the chinese hamster line wg3h (hgprt-) was crossed with the tk- mutants; chinese hamster a23 or mouse 3t34e, and hybrids were selected in hat medium. irradiation of one (marker rescue) or both (mutual rescue) partners before fusion yielded qualitatively different results. after x-irradiation marker rescue curves were of single-hit type, with d0 val ...1977300369
comparison of three mammalian cell-lines with respect to their sensitivities to hyperthermia, gamma-rays and u.v.-radiation.three types of cultured mammalian cells, from a rat ureter carcinoma (ruc-2), from a mouse mammary carcinoma (m8013), and from a chinese hamster lung cell-line (ch-v79), have been compared with respect to various treatments. using cloning assay, the sensitivity of these cell-lines was measured for ionizing radiation, u.v.-light and for temperatures of 41 degrees, 42 degrees, 43 degrees, 44 degrees and 45 degrees c. ruc-2 cells are the least sensitive to these treatments, except for 45 degrees c. ...1977301514
inactivation and mutation of cultured mammalian cells by aluminium characteristic ultrasoft x-rays. ii. dose-responses of chinese hamster and human diploid cells to aluminium x-rays and radiations of different let.the induction of inactivation and mutation to thioguanine-resistance of two types of cultured mammalian cells, v79 chinese hamster and hf19 human diploid, was studied after irradiation with aluminium k characteristic ultrasoft x-rays, helium ion track intersections of different let, 42 mev d-be neutrons, and hard x- or gamma-rays. the form of the dose-response curves was different for the two cell-types, and there was an overall difference in radiosensitivity, the human cells being the more sens ...1977301865
inactivation and mutation of cultured mammalian cells by aluminium characteristic ultrasoft x-rays. iii. implication for theory of dual radiation action.microdosimetric distributions for aluminium k characteristic ultrasoft x-rays and 4he ion tract intersections are calculated and used to analyse recent biological results obtained with these radiations. results on inactivation and mutation-induction to thioguanine resistance of both v79 chinese hamster cells and hf19 human diploid fibroblasts in vitro are analysed in terms of the kellerer-rossi "theory of dual radiation action". the small quantum energy of the aluminium x-ray photons and the ver ...1977301870
effect of salt solutions on radiosensitivity of mammalian cells. iii. treatment with hypertonic solutions.v79 chinese hamster cells were treated with hypertonic solutions of nacl or kcl and irradiated rat various times before, during, or after exposure to the solution. in solutions of molarities between 0-2 and 0-5 m, the cellular radiosensitivity increases with the molarity of the bathing solution. at these molarities, the hypertonic solution need not be present during irradiation to sensitize cells. furthermore, radiosensitivity of cells could be increased by exposing cells for longer times to the ...1977302244
the expression and relation of hla, beta2-microglobulin and receptor for marmoset red blood cells on man/mouse and man/chinese hamster hybrid cells.the expression of hla, human and mouse beta2-microglobulin (beta2m), p red blood cell antigen and a receptor for marmoset red blood cells (marbc) were studied on 18 man/mouse and man/chinese hamster hybrids. a positive correlation was found between the expression of hla, p, and the receptor for marbc, which we interpret as a possible synteny between these different loci. we studied 3 hybrid clones where hla antigens are still expressed despite the absence of human beta2m and where redistribution ...197766148
studies on sex chromosomes of four hamster species: cricetus cricetus, cricetulus griseus, mesocricetus auratus, and phodopus sungorus.in this paper, we present an analysis of the sex chromosomes of four hamster species after application of different staining techniques. the mitotic x chromosomes show a striking similarity in g-banding pattern but rather great differences in their c-banding patterns. a presumably homologous euchromatic segment that exhibits two distinct g-bands appears in the x chromosome of each species. the y chromosome of cricetus cricetus is in contrast to those of the other species, because it reveals a re ...197767011
neutralization of salmonella toxin-induced elongation of chinese hamster ovary cells by cholera antitoxin.a partially purified preparation of the delayed skin permeability factor from salmonella typhimurium caused chinese hamster ovary cells to elongate. the elongation effect and the skin test activity were blocked by monospecific rabbit antisera against cholera toxin and against the b fragment of cholera toxin,197767084
pretreatment of hamster cells with phenethyl alcohol alters cell surface glycoproteins and inhibits vesicular stomatitis virus growth.chinese hamster ovary cells cultured in the presence of phenethyl alcohol exhibit obvious changes in cell surface galactose and galactosamine glycoproteins as determined by the galactose-oxidase[3h]borohydride technique and sds gel electrophoresis. cells pretreated with phenethyl alcohol (drug was removed before infection) were not as effective as hosts for vesicular stomatitis virus as untreated cultures. a minimum pretreatment time with 0.1% phenethyl alcohol of about 8 h was required before a ...197768807
identification of a chromosome that controls malignancy in chinese hamster cells.a chromosome that controls malignancy in chinese hamster cells has been identified by analysis of the giemsa banding pattern of a malignant cell line transformed by simian virus 40 (sv40), non-malignant revertants from this line, segregants from the revertants that were again malignant and a cell line transformed by methylcholanthrene. the malignant cell line transformed by sv40 was near diploid and had gained additional material of chromosome 3. revertants with a suppression of malignancy and m ...197773545
further studies on hybrid cell-surface antigens associated with human chromosome 11.a new human immunogenetic cell-surface activity associated with human chromosome 11 in the al human-chinese hamster ovary cell hybrid is described. like a1, but not a2, it is present on the human erythrocyte. by mutagenesis and selection, specific, stable, variants of the al hybrid have been prepared exhibiting various combinations of a1, a2, a3, and lactic dehydrogenase a activities. the antigens of the al system can be demonstrated by the horseradish peroxidase system which offers a promising ...197774861
purine mutants of mammalian cell lines: iii. control of purine biosynthesis in adenine phosphoribosyl transferase mutants of cho cells.spontaneous and mutagen-induced 2,6-diaminopurine-resistant mutants of chinese hamster ovary (cho-k1) cells were isolated. such mutants fell into two classes: spontaneous and ethylmethane-sulfonate-induced mutants had approximately 5% wild-type adenine phosphoribosyl transferase (aprt) activity, whereas icr-170g-induced mutants had barely detectable aprt activity. since it has been reported that human hypoxanthine-guanine phosphoribosyl transferase (hgprt) (lesch-nyhan syndrome) and aprt mutants ...197775575
mutation induction by the antischistosomal drug f30066 in various test systems.the genetic activity of furapromidium (f30066), an antischistosomal drug, was studied in salmonella typhimurium, saccharomyces cerevisiae, neurospora crassa and cultured chinese hamster cells. the results show that f30066 induces gene mutations in s. typhimurium, n. crassa and chinese hamster cells. this compound also causes gene conversions in s. cerevisiae.1977138086
folate-dependent enzymes in cultured chinese hamster cells: folypolyglutamate synthetase and its absence in mutants auxotrophic for glycine + adenosine + thymidine. 197718110
regional assignment of seven genes on chromosome 1 of man by use of man-chinese hamster somatic cell hybrids. i. results obtained after hybridization of human cells carrying reciprocal translocations involving chromosome 1.regional localization studies of genes coding for human pgd, pph1, pgm1, ugpp, guk1, pep-c, and fh, which have been assigned to chromosome 1, were performed with man-chinese hamster somatic cell hybrids, informative hybrids that retained fragments of the human chromosome 1 were produced by fusion of hamster cells with human cells carrying reciprocal translocations involving chromosome 1. analysis of the hybrids that retained one of the translocation chromosomes or de novo rearrangements involvin ...197718324
mutagenesis by simian virus 40. ii. changes in substrate affinities in mutant hypoxanthine-guanine phosphoribosyl transferase enzymes at different ph values.a number of 8-azaguanine-resistant clones selected from chinese hamster cells infected with sv 40, and supposed to originate by virus infection was investigated to demonstrate and analyze genetic alterations occurring in the cells after infection. all resistant clones tested showed reduced but detectable activity levels of the enzyme hypoxanthine-guanine phosphoribosyltransferase. the extent of reduction in the activity was not identical for different substrates. in all the clones tested, sponta ...197721348
effects of temperature and antibody on the cyclid growth of vesicular stomatitis virus.to see the effects of temperature on the interrelated cyclic production of standard and defective interfering (di) particles of vesicular stomatitis virus, a temperature-sensitive (ts) g114 mutant was passaged successively at different temperatures and the production of the two types of viral particles as well as the ability of chinese hamster ovary cells to survive each passage was continuously monitored. when the temperature was nonpermissive for standard virus, the synthesis of both standard ...1977189064
assembly of viral membranes. i. association of vesicular stomatitis virus membrane proteins and membranes in a cell-free system.we report here an in vitro system designed to study the interactions of vesicular stomatitis virus (vsv) proteins with cellular membranes. we have synthesized the vsv nucleocapsid (n) protein, nonstructural (ns) protein, glycoprotein (g protein), and membrane (m) protein in a wheat germ, cell-free, protein-synthesizing system directed by vsv 12 to 18s rna. when incubated at low salt concentrations with purified cytoplasmic membranes derived from chinese hamster ovary cells, the vsv m andg protei ...1977189082
assignment of the integration site for simian virus 40 to chromosome 17 in gm54va, a human cell line transformed by simian virus 40.gm54va human cells transformed by simian virus 40 (sv40) were fused with peritoneal macrophages obtained from three different mouse strains. all 27 hybrid clones studied were positive for sv40 tumor antigen in 100% of their cells and contained human chromosome 17. human chromosome 17 was the only human chromosome present in five of the hybrid clones. fusion of gm54va cells and either thymidine kinase (ec 2.7.1.75)-deficient mouse or chinese hamster fibroblasts resulted in the growth in hypoxanth ...1977189310
variation in enterotoxigenicity of escherichia coli.the possibility that the variable severity of diarrheal disease due to enterotoxigenic escherichia coli might be explained by quantitative differences in the activity of heat-labile enterotoxin was examined. the amount of toxin secreted by 13 enteropathogenic strains of e. coli was quantitated by measurements of the toxin-dependent increase in adenosine 3':5'-cyclic phosphate (cyclic amp) in chinese hamster ovary cells. the activity ranged from 150 pmol of cyclic amp/ml per mg of protein to 4,04 ...1977190329
mutagenicity testing in industry.the aims of authorities, university and industrial scientists are outlined. the prime feature remains: how important are the achieved results for estimating the mutagenic risk to humans? the various methods available for the testing of chemical substances for mutagenicity are compared. their usefulness to estimate the mutagenic risk are considered and the disadvantages and advantages of such methods are discussed. the industrial toxicologist must apply those methods which permit the most accurat ...1977578711
small numbers in mutagenicity tests.experimental control material for statistical analysis of the results of the micronuclei test in the mouse (nmri strain) and the chinese hamster and for the host-mediated assay in the mouse (nmri strain) using auxotrophic bacterial strains are presented. the binomial distribution of the micronuclei makes it possible to analyse the sample size according to the formula of cochran and cox (1957). for the host-mediated assay, the experimental principles are given which make it possible to evaluate t ...1977578712
cyto-enetic investigations of mammals. comparison of the genetic activity of cytostatics in mammals.mutagenicity tests have been performed with cp, ip and tp. there is an increase of mutagenic activity from tp to ip to cp 8 h after the second intraperitoneal application. this has been confirmed by analysis of bone marrow chromosomes of mice, rats and chinese hamsters. the maximum mutagenic activity of all three cytostatics was found 12 h after the second injection. thereafter the aberration rate induced by cp decreased quickly. the inactivation of ip and tp and the elimination of chromosome ab ...1977578713
influenza virus infection of a cell-cycle mutant of chinese hamster ovary cells. 1977558282
human beta-glucuronidase: assignment of the structural gene to chromosome 7 using somatic cell hybrids.beta-glucuronidase (gus) has become an important enzyme model for the genetic study of molecular disease, enzyme realization, and therapy, and for the biogenesis and function of the lysosome and lysosomal enzymes. the genetics of human beta-glucuronidase was investigated utilizing 188 primary man-mouse and man-chinese hamster somatic cell hybrids segregating human chromosomes. cell hybrids were derived from 16 different fusion experiments involving cells from ten different and unrelated individu ...1977559490
dna repair in v-79 cells treated with combinations of ultraviolet radiation and n-acetoxy-2-acetylaminofluorene.earlier experiments on human cells showed that n-acetoxy-2-acetylaminofluorene mimics ultraviolet radiation in biological and repair characteristics and that the amount of repair from a combined treatment was additive. chinese hamster v-79 cells are less proficient than human cells in excision repair of pyrimidine dimers resulting from irradiation. we therefore investigated the combined effects of both agents on repair in v-79 cells to see whether they follow the same pattern as in human cells. ...1977560253
replication of minute virus of mice in chinese hamster ovary fibroblasts.minute virus of mice (mvm), a parvovirus, replicates in chinese hamster ovary (cho) cells. although replication of the virus cannot readily be detected by haemagglutination, it can be measured by plaque assay on mouse strain lm cells.1977560425
segregation of human hypoxanthine phosphoribosyltransferase activity from somatic cell hybrids isolated from fusion of mouse gene transfer cells with chinese hamster cells. 1977561300
effects of wheat germ agglutinin on membrane transport.(1) low concentrations of wheat germ agglutinin are cytotoxic toward several tissue culture lines, including chinese hamster ovary cells, swiss 3t3 cells, mouse l cells and baby hamster kidney cells. the ld50 ranged from 1 to 5 microgram wheat germ agglutinin per ml. similar concentrations of the lectin inhibited the transport of the non-utilizable amino acids alpha-aminoisobutyric acid and cycloleucine and inhibited the uptake of thymidine. in contrast, 2-deoxy-d-glucose uptake was not altered ...1977561616
turnover of tubulin and the n site gtp in chinese hamster ovary cells.radioactively labeled tubulin from chinese hamster ovary (cho) cells can be isolated by co-polymerization with nonradioactive porcine brain microtubule protein. 75% of the soluble tubulin in cho extracts co-polymerizes with the porcine protein through several cycles, without preferential loss of either cho or porcine subunits. after phosphocellulose chromatography of the co-polymerized microtubules, the cho tubulin is radiochemically homogeneous, as judged by sds-polyacrylamide gel electrophores ...1977562716
intrachromosomal gene mapping in man: the gene for tryptophyl-trna synthetase maps in region q21 leads to qter of chromosome 14.a gene for tryptophanyl-trna synthetase (ec 6.1.1.2), the enzyme which attaches tryptophan to its trna, has previously been assigned to human chromosome 14 by analysis of man-mouse somatic cell hybrids. we report here a method for the electrophoretic separation of chinese hamster and human tryptophanyl-trna synthetases and its application to a series of independently derived chinese hamster-human hybrids in which part of the human chromosome 14 has been translocated to the human x chromosome. wh ...1977564085
streptozotocin-induced diabetes in the chinese hamster. biochemical and endocrine disorders.streptozotocin treatment (125 mg/kg) in the chinese hamster induced hyperglycaemia, hypoinsulinaemia, hyperglucagonaemia and changes in body, liver, pancreas, stomach, kidney and adipose tissue weights. the pancreatic reserves of insulin and glucagon in the diabetic animals were low, but stomach glucagon high. these animals showed high levels of phosphoenolpyruvate carboxykinase and low levels of glucokinase, hexokinase, isocitrate dehydrogenase and malic enzyme, but normal levels of pyruvate ki ...1977590651
cytotoxicity of commonly used solvents at elevated temperatures.at 43 degrees c (but not at 41 degrees c), organic solvents used to dissolve water-insoluble chemotherapeutic agents become themselves lethal to cells. this finding is not unique to chinese hamster cells (ha-1); mouse mammary sarcoma cells (emt-6) behave similarly. the solvent concentrations involved are in the range of those needed to make drug solutions. hence experiments measuring drug-cell interactions at elevated temperatures must include controls which independently measure solvent effects ...1977591566
a fluence response study of lethality and mutagenicity of white, black, and blue fluorescent light, sunlamp, and sunlight irradiation in chinese hamster ovary cells.under a set of defined experimental conditions, the fluence response of chinese hamster ovary (cho) cells to various light sources was studied by measuring single-cell survival and mutation to 6-thioguanine (tg) resistance. fluorescent white, black, and blue lights were sightly lethal and mutagenic. sunlamp light was highly lethal and mutagenic, exhibiting these biological effects within 15 sec of exposure under conditions recommended by the manufacturer for human use. lethal and mutagenic effec ...1977593289
chromosome stability in cho cells.the established cell line derived many years ago from chinese hamster ovary (cho cells) has been studied for the extent of chromosomal variation. because this cell line is used extensively for genetic studies, the contribution of chromosome variability to genetic variability has also been examined. the quasidiploid cho cells were found to have a banded karyotype somewhat altered from that of the chinese hamster from which the line was derived. however, most of the genome could be accounted for a ...1977601677
regional assignment of seven genes on chromosome 1 of man by use of man-chinese hamster somatic cell hybrids. ii. results obtained after induction of breaks in chromosome 1 by x-irradiation.the position of genes coding for pgd, pph1, ugpp, guk1, pgm1, pep-c, and fh on human chromosome 1 was investigated by analysis of karyotype and enzyme phenotypes in man-chinese hamster somatic cell hybrids carrying aberrations involving chromosome 1. suitable hybrid cell lines were obtained by x-irradiation of hybrid cells carrying an intact chromosome 1 and by fusion of human cells from a clonal population carrying a translocation involving chromosome 1 with chinese hamster cells. the latter hu ...1977318153
mannosidosis: assignment of the lysosomal alpha-mannosidase b gene to chromosome 19 in man.human alpha-mannosidase activity (alpha-d-mannoside mannohydrolase, ec 3.2.1.24) from tissues and cultured skin fibroblasts was separated by gel electrophoresis into a neutral, cytoplasmic form (alpha-mannosidase a) and two closely related acidic, lysosomal components (alpha-mannosidase b). human mannosidosis, an inherited glycoprotein storage disorder, has been associated with severe deficiency of both lysosomal alpha-mannosidase b molecular forms. chromosome assignment of the gene coding for h ...1977318154
the effect of respiratory carcinogenesis on systemic humoral and cell-mediated immunity of syrian golden hamsters.the effect of intratracheal instillation of benzo(a)pyrene and its noncarcinogenic analog benzo(a)pyrene on the systemic humoral and cell-mediated immune response of syrian golden hamsters was evaluated. hamsters treated with the carcinogen had a transient suppression of the splenic plaque-forming cell response to sheep erythrocytes, compared with analog-treated controls. the numbers of direct (immunoglobulin m) and indirect (immunoglobulin g) plaque-forming cells were suppressed at the 9th week ...1977318605
enterotoxigenic escherichia coli isolated from patients at a hospital in dacca.enterotoxigenic strains of escherichia coli, a significant cause of acute, watery, cholera-like diarrhea, were isolated from 23 of 65 patients with diarrhea in whom no other enteric pathogens were found during one week (november 1974) at the cholera research hospital, dacca, bangladesh. diarrhea associated with enterotoxigenic strains of e. coli occurred primarily in adults but affected persons of all age groups and could not be distinguished from cholera or from other cholera-like diarrhea on c ...1977320276
microsome-mediated mutagenesis in v79 chinese hamster cells by various nitrosamines.a microsome-mediated mutagenesis system has been established with the v79 chinese hamster cell line. the cells, grown in monolayer, were treated with various nitrosamines in the presence of a postmitochondrial fraction ((s15) from rat liver and a reduced nicotinamide adenine dinucleotide-generating system for 1 hr, washed and incubated for 2 to 3 hr in fresh culture medium, and then plated for toxicity and mutagenicity assays. mutation was determined by resistance to 20mug 8-azaguanine per ml. i ...1977321116
diarrhea due to escherichia coli in the rabbit: a novel mechanism.a strain of escherichia coli o15 (rdec-1) isolated from several rabbits with diarrhea was examined to determine (1) whether the strain could produce diarrhea when administered by the orogastric route to other rabbits and (2) whether this strain was invasive or enterotoxigenic. strain rdec-1 produced diarrhea in 48 of 62 rabbits when given by the orogastric route in doses that ranged from 1.5 x 10(2) to 4 x 10(10) bacteria. the organism did not give a positive result in the 18-hr ileal loop or se ...1977321703
characterization of the chinese hamster ovary cell assay for the enterotoxins of vibrio cholerae and escherichia coli and for specific antisera, and toxoid.the morphologic change in chinese hamster ovary (cho) cells that is associated with increased intracellular concentrations of adenosine 3':5'-cyclic phosphate (cyclic amp) provided a highly sensitive assay for the heat-liable enterotoxins of vibrio cholerae and escherichia coli. the similarity between the responses of cho cells and those of intestinal mucosa to enterotoxins was demonstrated by the inhibition of these effects by the ganglioside galactosyl-n-acetylgalactosaminyl [sialosyl] lactosy ...1977323378
mutagenicity of polycyclic hydrocarbons. ii. monitoring genetical hazards of chrysene in vitro and vivo.mutagenicity tests were performed with chrysene in the salmonella/microsome test, nmri-mice oocytes, bone-marrow cells and spermatogonia of chinese hamsters. only in mice oocytes was a weak but significant increase of structural chromosome aberrations observed. correlations were found between weak carcinogenic and observed weak mutagenic activities of chrysene in vitro and in vivo.1977327309
mutagenicity and cytotoxicity of benz[alpha]anthracene diol epoxides and tetrahydro-epoxides: exceptional activity of the bay region 1,2-epoxides.three diastereomeric pairs of diol epoxides, two tetrahydro-epoxides, and the k-region oxide of the polycyclic aromatic hydrocarbon benz[a]anthracene were evaluated for mutagenic activity in strain ta 100 of salmonella typhimurium and in line v79-6 of chinese hamster lung cells. the two diastereomeric 1,2-epoxides of the trans-3,4-dihydrodiol of benz[a]anthracene are 15 to 35 times more mutagenic to the bacteria and 65 to 125 times more mutagenic to the mammalian cells than are the diastereomeri ...1977331315
mutagenicity of isomeric diol-epoxides of benzo[a]pyrene and benz[a]anthracene in s. typhimurium ta98 and ta100 and in v79 chinese hamster cells.pairs of isomeric vicinal diol-epoxides derived from benzo[a]pyrene 7,8- and 9,10-dihydrodiols and from benz[a]anthracene 8,9-dihydrodiol were tested for their abilities to revert salmonella typhimurium strains ta98 and ta100 to histidine prototrophy and to induce the formation of 8-azaguanine- or of ouabain-resistant v79 chinese hamster cells. all six diol-epoxides were active in both bacterial strains, but 7beta,8alpha-dihydroxy-9beta,10beta-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (the syn iso ...1977333280
zinc and manganese contents of micro-dissected pancreatic islets of some rodents. a microchemical study in adult and newborn guinea pigs, rats, chinese hamsters and spiny mice.by a flameless atomic absorption spectrophotometry procedure, using a graphite furnace, it was possible to assay the contents of zinc and managanese in micro-dissected pancreatic islets of several rodents. interest was focused upon the islets of guinea-pigs, due to the fact that guinea-pig insulin lacks a histidine residue in the b10 position of the molecule which normally binds zinc (or other heavy metals) in the hexamer formation, probably involved in the storage of insulin. both the zinc and ...1977335757
escherichia coli heat-labile enterotoxin: comparison of antitoxin assays and serum antitoxin levels.the mouse adrenal tumor cells (y-1 strain) and the chinese hamster ovary cells, two routinely used tissue culture assays for escherichia coli heat-labile enterotoxin (lt), were used to detect serum antitoxin responses in culture-positive patients from several well-defined sources. there was no correlation between a significant antitoxin response and isolation of lt-producing e. coli in two "domestic" diarrheal outbreaks. serum samples from a third group of individuals in a rural cholera-endemic ...1977336543
toxin from the culture filtrate of shigella dysenteriae that causes morphological changes in chinese hamster ovary cells and is distinct from the neurotoxin.a toxin that causes morphological changes in chinese hamster ovary cells was isolated from a culture filtrate of shigella dysenteriae 1. it was partially purified by successive column chromatography on diethylaminoethyl-cellulose, bio-gel a-5m, and hydroxylapatite. the toxin was separated from neurotoxin by diethylaminoethyl-cellulose column chromatography and was not lethal for mice.1977336549
inhibition of mammalian ribonucleotide reductase by a dinucleotide produced in eucaryotic cells.hs3, a highly phosphorylated dinucleoside originally purified from the fungus achlya, has been isolated from chinese hamster ovary cells undergoing glutamine starvation. the hs3 compounds obtained from the fungal and mammalian sources exhibited similar physical and chemical properties. this unusual dinucleotide may be an important regulator of eucaryotic ribonucleoside diphosphate reductase activity; for 50 micrometer hs3, isolated from either mammalian or fungal cells, significantly inhibited c ...1977338619
assignment of the structural genes for the alpha subunit of hexosaminidase a, mannosephosphate isomerase, and pyruvate kinase to the region q22-qter of human chromosome 15.concordant segregation of the expression of the alpha subunit of human hexosaminidase a, human mannosephosphate isomerase, and pyruvate kinase was observed in somatic cell hybrids between either thymidine kinase-deficient mouse cells or thymidine kinase-deficient chinese hamster cells and human white blood cells carrying a translocation of the distal half (q 22-qter) of the long arm of chromosome 15 to chromosome 17. a positive correlation was established between the expression of these human ph ...1977341373
characterization of alpha-galactosidase isoenzymes in normal and fabry human-chinese hamster somatic cell hybrids.the alpha-galactosidases in normal man-chinese hamster somatic cell hybrids were investigation with antibodies specific for human alpha-galactosidase a and antibodies specific for chinese hamster alpha-galactosidase. it was found that an isoenzyme in hybrid cells, which has an electrophoretic mobility between that of human alpha-galactosidase a and chinese hamster alpha-galactosidase, contains immunologic determinants of both human and chinese hamster origin, suggesting that it is a heteropolyme ...1977404232
assay of escherichia coli heat-labile enterotoxin with vero cells.the continuous cell line of african green monkey kidney, vero, showed characteristic morphological changes in response to culture filtrates from toxigenic strains of escherichia coli. the response compared favorably with that of y-1 (mouse adrenal) and cho (chinese hamster ovary) cells. vero cells were the simplest and most economical to maintain in the laboratory.1977405326
selection and characterization of cells resistant to diphtheria toxin and pseudomonas exotoxin a: presumptive translational mutants.two classes of diphtheria toxin-resistant variants were selected from chinese hamster ovary (cho-k1) cells: permeability variants, in which uptake of toxin was impaired, and a new class of cytoplasmic variants, which were cross-resistant to pseudomonas exotoxin. ef-2 prepared from the cytoplasmic variants was resistant to adp-ribosylation by either toxin. the evidence presented suggests that these are translational variants possessing a mutationally altered ef-2 gene product. these studies also ...1977408012
localization of neurotensin-immunoreactive cells in the small intestine of man and various mammals.antibodies against synthetic bovine neurotensin were raised in rabbits and used to demonstrate neurotensin-immunreactive cells by immunohistochemical methods. in the jejunum and ileum of all species investigated (man, dog, monkey, cat, rabbit, sheep, rat, mouse, hamster, chinese hamster, gerbil, pig and guinea pig) cells were present in the mucosa, which reacted specifically with antineurotensin serum using the indirect immunofluorescence and peroxidase-antiperoxidase methods. in the monkey tupa ...1977409699
characterization of residual hexosaminidase activity in sandhoff's disease using man-chinese hamster cell hybrids.to obtain information about the nature of the residual hexosaminidase activity in sandhoff's disease, hybrid cell lines between fibroblasts from a patient with sandhoff's disease and chinese hamster cells were isolated. in these hybrid cell lines, a heteropolymeric isoenzyme was detected that is composed of human alpha- and chinese hamster hexosaminidase subunits. due to the electrophoretic and immunological behavior of the heteropolymeric molecules in interspecies hybrids with normal fibroblast ...1977413781
regional localization of a beta-galactosidase locus on human chromosome 22.human white blood cells with an x/22 translocation [46, xx, t(x;22)(q23;q13)] were fused with chinese hamster cells. the isolated hybrids were analyzed for human chromosomes and 21 enzyme markers. an electrophoretic technique for studying the beta-galactosidase isoenzymes in man-chinese hamster hybrid cells was developed. immunological studies showed that the beta-galactosidase marker studied in these hybrids did contain immunological determinants of human origin. furthermore the results provide ...1977414365
the effect of adriamycin on cell cycle progression and dna replication in chinese hamster ovary cells.administration of[3h]aflatoxin b2 (2,3-dihydroaflatoxin b1)(afb2) to male rats resulted in levels of hepatic dna- and ribosomal (r)rna-aflatoxin adducts that were about 1% of those for rats given [3h]aflatoxin b1(afb1). the levels of hepatic protein-aflatoxin adducts were 35 to70% as great for afb2-treated as compared to afb1-treated rats...1977830405
chromosome replication in somatic hybrids of mouse and temperature sensitive chinese hamster cells. 1977833213
characterization of beta-d-n-acetylhexosaminidase isoenzymes in man-chinese hamster somatic cell hybrids.a series of man-chinese hamster hybrids were investigated with the use of an anti-chinese hamster hexosaminidase serum, a specific anti-human hex a serum and an anti-human hex b serum. the expression of human hex a was found to be dependent on the presence of hex b. a heteropolymeric molecule is formed independently of hex b, which consists of chinese hamster and specific hex a moieties. it has an electrophoretic mobility nearly identical to hex a. a relationship between the absence and presence ...1977835571
th induction of thioguanine-resistant mutants of chinese hamster cells by gamma-rays.the induction of mutation to purine analogue resistance was assessed in chinese hamster v79-4 cells exposed to gamma-radiation. after irradiation, the cells were grown in non-selective medium for different time intervals before respreading into medium containing 0.5-0.7 mug/ml thioguanine. in some experiments colonies arising in thioguanine-medium were counter-selected in medium containing the glutamine analogue azaserine, which distinguishes mutants with very little activity of the enzyme hypox ...1977840237
liver homogenate-mediated mutagenesis in chinese hamster v79 cells by polycyclic aromatic hydrocarbons and aflatoxins.several chemical carcinogens that require metabolic activation have been examined for their cytotoxic and mutagenic activity in chinese hamster v79 cells. mutagenic activity was measured as the induced frequency of 6-thioguanine-resistant colonies. metabolic activation was provided by the 9000 g supernatant fraction of rat liver plus cofactors. the cytotoxicity and mutagenicity of aflatoxin b1 and b2, benzo(a)pyrene, 3-methylcholanthrene, 7,12-dimethylbenz(a)anthracene, dibenz(a,h)-anthracene, d ...1977840239
single strand breakage and repair in eukaryotic dna as assayed by s1 nuclease.a sensitive new approach for measuring the repair of single strand breaks in dna induced by low doses of gamma irradiation was tested in cultured fibroblasts from chinese hamster lung, human afflicted with ataxia telangiectasia or fanconi's anemia and in normal cells of early and late passages. the assay is based on the increasing rate of strand separation of dna duplexes in alkali for molecules with increasing numbers of single strand scissions. dna strand separation is shown to follow the rela ...1977840643
study on cytological effects of carofur -- a new mutagen.chinese hamster cells (line v-79) and human leukocytes in vitro and mice of the cba strain were treated with carofur (also called nifurprazinum), an antibacterial agent of pharmaceutical importance. at concentrations as low as 20 ppm, the in vitro treatments of cells of chinese hamster and human lymphocytes expressed chromosome aberrations, almost exclusively of deletion type. this effect resembles that of fluorodeoxyuridine but may not necessarily reflect the same basic mechanism involved. when ...1977846486
neutral amino acid transport systems of tissue culture cells.we have studied the interactions among a varied group of neutral amino acids for uptake into two different animal tissue culture cell lines. 3t3 mouse cells and chinese hamster ovary cells were used in these studies. the results showed that the affinities of the amino acids clustered into two groups, one including amino acids such as glycine, alanine, and alpha-aminoisobutyric acid and the other group included amino acids such as leucine and phenylalanine. the specificities and properties of the ...1977853037
synthesis of newcastle disease virus polypeptides in a wheat germ cell-free system.we have isolated 18s rna from cytoplasmic extracts of newcastle disease virus-infected chinese hamster ovary cells and tested its ability to direct protein synthesis in extracts derived from wheat germ. the products of the cell-free reaction directed by this rna contain polypeptides that comigrate with np, m,f, and 47k roteins from virions. in addition, the products contain a polypeptide (67k) that migrates on polyacrylamide gels slightly faster than the hn protein from virions. tryptic peptide ...1977853567
response of extremely hypoxic cells to hyperthermia: survival and oxygen enhancement ratios.chinese hamster v79 cells and mouse emt6 cells were made extremely hypoxic with a chamber technique that relies upon gas exchange rather than respiration-assisted oxygen depletion. cells in these chambers were treated with heat (43degrees c) or heat plus x-irradiation, and colony-forming ability was determined. hyperthermia: (a) kills exponentially growing v79 cells more efficiently than plateau-phase cells; (b) kills euoxic and extremely hypoxic cells equally; and (c) radiosensitizes euoxic and ...1977860045
selective incorporation of l-3,4-dihydroxyphenylalanine by s-91 cloudman melanoma in vitro.the incorporation of precursors of the biopigment melanin into melanotic and amelanotic s-91 cloudman melanoma, mouse fibroblast l-929, and chinese hamster ovary cells was studied. tyrosine did not selectively accumulate in pigmented cells compared to that in nonpigmented control cells. inhibition of protein synthesis with cycloheximide provided an estimate of the partition of tyrosine between protein (95%) and pigment biosynthesis (5%). l-3,4-dihydroxyphenylalanine, a more proximal precursor of ...1977861938
structural repeat units of chinese hamster ovary chromatin. evidence for variations in repeat unit dna size in higher eukaryotes.dna lengths in the structural repeat units of chinese hamster ovary (cho) and chicken erythrocyte chromatin were compared by analyzing the sizes of dna fragments produced after treatment of nuclei with staphylococcal nuclease. the repeat length of cho chromatin (173 +- 4 bp) is about 20 base pairs (bp) smaller than that of chicken erythrocyte chromatin (194 +- 8 bp). repeat lengths of rat liver and calf thymus chromatin were found to be about 10 bp shorter than that of chicken erythrocyte chroma ...1977866190
the units of dna replication in the mammalian chromosomes: evidence for a large size of replication units.the replication of chromosomal dna in human and chinese hamster cell populations has been studied by means of the dna fiber autoradiography. it was found that the rate of dna replication for one fork in human cells varies from 0.2 to 0.9 micron/min, the average being 0.6 micron/min. in the chinese hamster cells the rate dna replication is greater, varying from 0.3 to 1.2 micron/min, the average being 0.8 micron/min. there are no clusters containing a great number of replication units in human an ...1977870295
the metabolic activation of 7-methylbenz(a)anthracene: the induction of malignant transformation and mutation in mammalian cells by non-k-region dihydrodiols.four different dihydrodiols derived from 7-methylbenz(a)anthracene have been tested, together with the parent hydrocarbon, for their ability to induce the in vitro malignant transformation of mouse m2 fibroblasts and mutations in v79 chinese hamster cells. in the transformation tests withe the non-k-region dihydrodiols, the 3,4-diol was the most active dihydrodiol tested and the 8,9-diol was also more active than 7-methylbenz(a)anthracene itself; the 1,2-diol showed only slight activity. the k-r ...1977873646
rapid assays for evaluating the drug sensitivity of tumor cells.assays that assess the ability of cells to incorporate labeled precursors into acid-precipitable material in the presence of adriamycin, daunorubicin, puromycin, vinblastine, melphalan, or methotrexate were investigated as an approach to the detection of resistant cells in human tumor samples. each assay was evaluated with suitable drug-resistant chinese hamster ovary cell lines and normal human fibroblasts to determine whether the assays reflected the drug sensitivity of these lines. moreover, ...1977875055
reverse transformation of chinese hamster ovary cells by a factor produced by vibrio parahaemolyticus. 1977875243
pre-implantation embryos of chinese hamster. i. incidence of karyotype anomalies in 226 control embryos.karyotyes were determined in 226 pre-implantation embryos (4--8-cell stages) of chinese hamster. the study was carried out under controlled natural breeding conditions, without superovulation and with the embryos developing in their mothers. a total of 5.3% karyotypically abnormal embryos were found. over half, 3.1%, were due to ploidy mutations, 5 cases of triploidy and 2 cases of haploidy. only 0.9% genome mutations were present, consisting of one autosomal trisomy and one autosomal monosomy. ...1977876265
l-dopa: selective toxicity for melanoma cells in vitro.in a study of the effect of l-dopa, an intermediate in the biosynthesis of the pigment melanin, on the growth of human and murine melanoma cells a highly selective inhibition of growth was observed for pigmented cell lines (s91a and human melanoma) as compared to the nonpigmented control cells (amelanotic melanoma s91b, mouse fibroblast l929, and chinese hamster ovary). there was a correlation between toxicity and the extent of incorporation of radioactively labeled l-dopa by each line.1977877570
regional chromosomal localization of the human gene for galactose-1-phosphate uridyltransferase.in the progeny of somatic cell hybrids formed by fusion of human lymphocytes and chinese hamster mutant cells, a single human chromosome a2 was selectively retained when grown in appropriate medium. spontaneous breakage of this chromosome in different hybrid subclones led to the assignment of the gene for galactose-1-phosphate uridyltransferase to the centromeric region of this chromosome (2q11 leads to 2q14). this gene is shown to be syntenic to the previously mapped genes for acid phosphatase ...1977885547
synteny between glycinamide ribonucleotide synthetase and superoxide dismutase (soluble).the auxotrophic mutant ade -c derived from chinese hamster ovary cell cho-k1 lacks the enzyme glycinamide ribonucleotide synthetase and requires exogenous supplement of purines for growth. cells from this mutant were fused with normal human lymphocytes, and the resulting hybrids were isolated in purine-deficient medium. a total of 32 primary clones and 49 secondary clones were analyzed for various isozyme markers. cytogenetic analysis with chromosome banding was also performed in some hybrid clo ...1977889603
malignant transformation and mutagenesis in mammalian cells induced by vicinal diol-epoxides derived from benzo(a)pyrene.benzo[a] pyrene and the syn- and anti-isomers of the 7,8-diol 9,10-oxide and of the 9,10-diol 7,8-oxide derived from this hydrocarbon have been tested for their abilities to induce malignant transformation in m2 mouse fibroblasts and mutagenesis in v79 chinese hamster cells. the anti-isomer of the 7,8-diol 9,10-oxide induced more mutations and transformation than did the other three vicinal diol-epoxides. the two 9,10-diol 7,8-oxides were moderately mutagenic but did not induce any transformatio ...1977890685
assignment of the gene for enolase to mouse chromosome 4 using somatic cell hybrids.somatic cell hybrids between mouse peritoneal macrophages (mpm) and human fibrosarcoma cells (ht-1080) or chinese hamster cells (a3) were analyzed by starch-gel electrophoresis for the expression of murine enolase. data obtained indicate that the locus for enolase is on chromosome 4 in the mouse.1977891258
metabolic behaviour of nonhistone chromosomal proteins in proliferating and in resting fibroblasts.the metabolism of nonhistone chromosomal proteins was studied in two lines of cells showing a different degree of contact inhibition: human diploid fibroblasts, which are easily contact-inhibited, and chinese hamster fibroblasts, which had been made to stop proliferating by fasting. by following the 3h414c ratio of [3h]tryptophan-labelled nonhistone chromosomal proteins and [14c]thymidine-labelled dna in chase experiments three main groups of these proteins could be detected with respect to thei ...1977891550
the deposition of 241am and 252cf in the skeleton of chinese hamster, syrian hamster and the rat. 1977893106
the pineal complex and its relationship to other epithalamic structures.the pineal complex of rodents is made up of a pineal gland which developmentally always originates from the area between the habenular and posterior commissure and a pineal sac which is continuous with the choroid plexus of the third ventricle. at the light-microscopic level, this sac appears to be identical to the choroid plexus. the pineal sac abuts the deep and superficial pineal glands of the golden hamster. in the pet mouse, gerbil, kangaroo rat, and chinese hamster, the sac is contiguous w ...1977899706
two-step chromosomal control of tumorigenicity of chinese hamster cells in nude mice.a simple method for microinjecting isolated chromosomes into a single living cell under an inverted microscope has been developed. of the 368 injected cells, 85 were able to form a colony and could be cloned. clones of chinese hamster v79 cells microinjected with chromosomes isolated from murine d56 cells [v79 (d56) cells] were tested for tumorigenicity in immunodeficient nude mice and for colony-forming ability in soft agar. untreated recipient v79 cells were highly tumorigenic and had a high c ...1977914396
a quantitative assay of mutation induction at the hypoxanthine-guanine phosphoribosyl transferase locus in chinese hamster ovary cells (cho/hgprt system): utilization with a variety of mutagenic agents.the induction of mutation by a variety of mutagens has been measured utilizing the hypoxanthine-guanine phosphoribosyl transferase (hgprt) locus in chinese hamster ovary (cho) cells (cho/hgprt) system). these mutagens include physical agents such as uv light and x-rays, and chemicals such as alkylating agents, icr-191, and metallic compounds. this system can also be modified for study of the mutagenicity of promutagens such as dimethylnitrosamine (dmn) which require biotransformation for mutagen ...1977917031
responses of proliferating and non-proliferating chinese hamster cells to cytotoxic agents.the effects of various cytotoxic chemicals, as measured by viable cell counts, colony-forming ability and proliferative capacity, have been studied using chinese hamster cells in exponential and plateau (stationary) phases of growth. the proliferating cells were altogether more sensitive to the action of the drugs than non-proliferating cells. however, imuran (azathioprine) a purine antimetabolite, was more effective against the plateau-phase cells. the observed response of cells to imuran could ...1978638016
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