Publications

membranolytic activity of detergents as studied with cell viability tests.	the membranolytic activity of 12 chosen detergents upon ehrlich ascites tumour and chinese hamster lung cells were studied with the fluorescein diacetate and the dye exclusion tests of cell viability. it was found that all these tests give reproducible and concordant results when non-ionic detergents are used but for ionic detergents only the fluorescein diacetate test can be applied. membranolytic activity of the detergents appeared to be uncorrelated with their capacity of membrane solubilizat ...	1978	658833
repair of alkylated dna in chinese hamster cells measured by loss of enzyme-sensitive sites in isolated dna.		1978	666813
altered growth properties of chinese hamster cells exposed to 1-methylguanine and 7-methylguanine.	primary chinese hamster embryo cell cultures generally yield cell lines with a finite lifetime in culture. however, if early-passage cells are exposed chronically to either of two normal degradation products of transfer rna, 1-methylguanine or 7-methylguanine, they are converted to continuous lines with altered growth characteristics and morphology. the continuous cell lines have saturation densities 2- to 10-fold higher than did finite control cultures, and some have the ability to grow in soft ...	1978	667823
assignment of nadh-cytochrome b5 reductase (dia1 locus) to human chromosome 22.	nadh-cytochrome b5 reductase (dia1, ec. 1.6.2.2) from human fibroblasts and from chinese hamster cells, both identified by immunologic studies, were clearly distinguished after polyacrylamide gel isoelectro-focusing followed by staining for nadh diaphorase activity. in thirteen independent man-hamster hybrids, the human enzyme dia1 presented a positive correlation with the human chromosome g22. eight hybrids were dia1(+) g22(+) and five hybrids were dia1(-) g22(-). these data agree with the rece ...	1978	669708
structure of the altered oligosaccharide present in glycoproteins from a clone of chinese hamster ovary cells deficient in n-acetylglucosaminyltransferase activity.	clone 15b cells, derived from chinese hamster ovary cells and deficient in a specific udp-n-acetylglucosamine:glycoprotein n-acetylglucosaminyltransferase activity, synthesize glycoproteins with altered oligosaccharide units. glycopeptides prepared from these glycoproteins contain large quantities of a glycopeptide with the composition (man)5(glcnac)2-asn whereas parent cells have only small amounts of this glycopeptide. the structure of the glycopeptide was determined by the combination of meth ...	1978	681360
assignment of the genes for triose phosphate isomerase to chromosome 6 and tripeptidase-1 to chromosome 10 in mus musculus by somatic cell hybridization.	evidence is presented for the assignment of the gene for triose phosphate isomerase to mus musculus chromosome 6 and tripeptidase-1 to chromosome 10 by synteny testing and chromosome assignment in chinese hamster x mouse somatic cell hybrid clones. neither tpi nor trip-1 were expressed concordantly with any known isozyme markers in 45 hybrid clones (13 primary and 32 secondary). karyotypic analysis of 21 clones showed that the expression of tpi and chromosome 6 were concordant in all cases as wa ...	1978	566475
assignment of a mus musculus gene for triosephosphate isomerase to chromosome 6 and for glyoxalase-i to chromosome 17 using somatic cell hybrids.	chinese hamster x mouse hybrid cells segregating mouse chromosomes have been used to assign a gene for triosephosphate isomerase (tpi-1, ec 5.3.1.1, mckusick no. 19045) to mouse chromosome 6, and a gene for glyoxalase-i (glo-1, ec 4.4.1.5, mckusick no 13875) to mouse chromosome 17. the genes for tpi-1 and lactate dehydrogenase b are syntenic in man and probably so in the dog. it is therefore likely that they are syntenic also in the mouse. it is of interest then that there is a mouse gene, ldr-1 ...	1978	566476
mutagenesis by n-acetoxy-2-acetyl aminofluorene of chinese hamster v79 cells is unaffected by caffeine.	8-azaguanine (azg)- and 6-thioguanine (tg)-resistant cells (mutants) were induced in chinese hamster v79-4 cells by 0.1--2.5 microgram/ml n-acetoxy-2-acetyle aminofluorine (acaaf) treatments in the presence of 5% fetal bovine serum (fbs). the frequency of resistant colonies increased from 1 to 47 per 10(5) survivors. the effect of caffeine (50--200 microgram/ml) during the mutagenesis expression period was determined by adding caffeine 1--24 h after acaaf. the medium was replaced after 48 h expo ...	1978	566636
the action of af 2 on cultured hamster and human cells under aerobic and hypoxic conditions.	af 2 (2-(2-furyl)-3-(5-nitro-furyl)acrylamide) was toxic to chinese hamster v 79 cells and normal human fibroblasts in aerobic media. however, the toxicity of the drug was increased many times by hypoxia. similarly, the frequency of af 2-induced azaguanine- and ouabain-resistant mutants of v 79 cells was much higher in hypoxia than under aerobic conditions. both hamster v 79 cells and human fibroblasts metabolized af 2 and other nitrofurans rapidly only under hypoxic conditions. human fibroblast ...	1978	566638
colchicine-like effect of diethylstilbestrol (des) on mammalian cells in vitro.	diethylstilbestrol (des), a synthetic estrogen, showed colchicine-like effects in vitro on cells of the cell lines such as chinese hamster fibroblast of thymus origin (cht), rat liver (dl), rat erythroblastic leukemia (eden-1/tc) and hela-s3. metaphase arrest was induced 3 h after treatment with 15 microgram/ml of des and polyploid or polynucleated cells were prominently observed more than 24 h after treatment. the arrest, however, was reversible when the agent was removed from the medium. tetra ...	1978	661838
time and cell systems as variables in fusion experiments with polyethylene glycol.	cell hybridization was done between a monolayer of b14-150 chinese hamster cells and a suspension of either mouse leukemia cells or normal human lymphocytes. cell contact was obtained by centrifugation of the suspension cells onto the monolayer cells in a culture plate. cell fusion was done by means of polyethylene glycol (peg). the optimum time for peg exposure as well as the yield of hybrid cells differed markedly with the different combinations.	1978	566713
properties of the thymidine transport system of chinese hamster ovary cells as probed by nitrobenzylthioinosine.	the transport of thymidine into chinese hamster ovary cells grown in suspension culture was measured under conditions in which thymidine was not metabolized, namely, when cells had been depleted of atp. the system transporting thymidine was saturable (kztm = 70 micron), rapid 50% of transmembrane equilibrium level attained within 8 sec), and was apparently shared by other nucleosides, but not thymine or hypoxanthine. 6([4-nitrobenzyl]thio)-9-beta-d-ribofuranosylpurine, "nitrobenzylthioinosine", ...	1978	568178
increased escherichia coli enterotoxin detection after concentrating culture supernatants: possible new enterotoxin detectable in dogs but not in infant mice.	the heat-stable enterotoxin (st) of escherichia coli can be detected by infant mouse or dog intestinal loop tests. these tests differ in that the dog assay uses concentrated culture supernatants and is based on measurements of net intestinal absorption, whereas the mouse test uses unconcentrated supernatants and depends on gross fluid accumulation. to compare the relative sensitivities of these assays, culture supernatants of randomly selected e. coli isolates from 34 bangalee diarrhea patients ...	1978	370144
replica plating and in situ enzymatic assay of animal cell colonies established on filter paper.	we have developed a simple technique for the replica plating of chinese hamster ovary (cho) cells. in this procedure cells are allowed to divide for 8-16 days between the plastic surface of a petri dish and a disc of whatman no. 50 filter paper, weighted down with glass beads. the culture medium can be replaced when necessary without disturbing the growing colonies. cells from each developing colony grow into the fibers of the paper, while others remain attached to the plate. the cell colonies t ...	1978	349559
determination of corynebacterium diphtheriae toxigenicity by a colorimetric tissue culture assay.	chinese hamster ovary (cho) cell cultures in microtiter wells are sensitive to growth inhibition and killing by picogram quantities of diphtheria toxin. in the absence of biologically active toxin, the cho cell culture produces sufficient acidic metabolites to change the phenol red ph indicator from pink to yellow within 56 h. in the presence of 10 pg of toxin per well, growth inhibition can be observed microscopically within 24 h. diphtheria toxin can be qualitatively assayed from culture super ...	1978	415068
bromodeoxyuridine tablet methodology for in vivo studies of dna synthesis.	5-bromodeoxyuridine (brdu) tablets with different physical characteristics are useful in a wide variety of studies requiring detection of dna replication in vivo. these tablets can effect a high substitution of brdu in dna, thereby permitting sister chromatid differentiation in chromosomes stained with 33258 hoechst alone or in conjunction with giemsa. baseline and cyclophosphamide-induced in vivo sister chromatid exchange frequencies in mouse spleen, marrow, and thymus were measured and found t ...	1978	356290
enterotoxigenicity of enteropathogenic serotypes of escherichia coli isolated from infants with epidemic diarrhea.	enteropathogenic serotypes of escherichia coli which have been incriminated by epidemiological evidence as responsible for epidemics of acute diarrhea in infants are often found to be nontoxigenic when tested by conventional systems such as y1-adrenal, chinese hamster ovary, and suckling mouse assays. twelve such strains, representing four different enteropathogenic serotypes, were examined for their capacity to elaborate toxic materials which alter water transport. ultrafiltration fractions pre ...	1978	361562
use of human-liver microsomes from kidney-transplant donors for the induction of chromatid aberrations and sister-chromatid exchanges by means of pre-carcinogens in chinese hamster cells in vitro.	samples of two human livers taken during operation of kidney donor patients were processed for microsome fractions and used for metabolization of cyclophosphamide (cp) and dimethylnitrosamine (dmn) in combination with the nadph-generating system. rat-liver microsomes were checked for comparison. induction of chromatid aberrations and sister-chromatid exchanges in a newly isolated clone of chinese hamster fibroblasts served as indicators of activity. human s-9 fractions standardized on protein co ...	1978	362179
mutagenicity of industrial compounds. vii. styrene and styrene oxide: ii. point mutations, chromosome aberrations and dna repair induction analyses.	the possible genetic effects produced by styrene have been investigated by means of different methodologies in several biological organisms: (a) the induction of point mutation has been investigated in salmonella typhimurium (reverse mutation), in the yeast schizosaccharomyces pombe (forward mutation), both in vitro and in vivo, in the host-mediated assay of mice, and in the chinese hamster cell line grown in vitro (v-79) (forward mutation); (b) the induction of chromosome mutation has been inve ...	1978	366743
persistence of the fc cytophilic antibody receptor in macrophage hybrid cells.	hybrid cell clones were obtained from mouse macrophase/ehrlich ascites cell fusions which showed the 'fc' cytophilic antibody receptor site, phagocytosis and motility typical of macrophages. with continued growth of the clones for 11 weeks, the receptor became undetectable but could be unmasked by dilute trypsin treatment; subsequent remasking of the receptor could be prevented with cycloheximide treatment of the hybrid cells. these hybrids produced cystic anaplastic tumours in neonatal irradiat ...	1978	400978
entrapment of metaphase chromosomes into phospholipid vesicles (lipochromosomes): carrier potential in gene transfer.	transfer of genes from one type of cultured mammalian cell to another by using isolated metaphase chromosomes has been reported with a frequency of one per 10(6)-10(8) cells. very recently a rate of 16/10(6) has been reported with chinese hamster ovary cells [spandidos, d. a. & siminovitch, l. (1977) proc. natl. acad. sci. usa 74, 3480-3484]. to increase the frequency of gene transfer, we isolated metaphase chromosomes from hypoxanthine guanine phosphoribosyltransferase (hgprt) positive cells, e ...	1978	349565
sensitization of ultraviolet radiation damage in bacteria and mammalian cells.	bacteria (serratia marcescens) and mammalian cell (chinese hamster v79-379a) were irradiated in monolayers with ultraviolet light at 254 nm or 365 nm in the presence or absence of radiosensitizing drugs. at 254 nm, killing is very efficient (d37 approximately 1 j m-2 exposure, or approximately 6 x 10(4) photons absorbed by dna per bacterium), and sensitizers have no effect. at 365 nm, cells are not killed in buffer, but are inactivated in the presence of nifurpipone or misonidazole. lethal expo ...	1978	354675
thermal enhancement of the effectiveness of gamma radiation for induction of reproductive death in cultured mammalian cells.	the induction by gamma radiation of reproductive death in cultured cells derived from a rat ureter carcinoma (ruc-2) and from chinese-hamster lung tissue (ch-v79) was shown to be enhanced by hyperthermic treatments at 41, 43 and 45 degrees c. the degree of enhancement was found to depend on the line of cells studied, the temperature employed and the level of damage considered. the influence of accumulating sublethal damage was decreased by hyperthermia, and the final slope of the radiation survi ...	1978	309451
host range restriction of vaccinia virus in chinese hamster ovary cells: relationship to shutoff of protein synthesis.	chinese hamster ovary cells were found to be nonpermissive for vaccinia virus. although early virus-induced events occurred in these cells (rna and polypeptide synthesis), subsequent events appeared to be prevented by a very rapid and nonselective shutoff of protein synthesis. within less than 2 h after infection, both host and viral protein syntheses were arrested. at low multiplicities of infection, inhibition of rna synthesis with cordycepin resulted in failure of the virus to block protein s ...	1978	310474
the effect of bromodeoxyuridine on the segregation of the chicken-specific hprt gene from chinese hamster-chick red blood cell somatic hybrids.	the segregation of the chick-specific hprt gene was studied in three chinese hamster-chick red blood cell hybrid lines. the three lines showed individual segregation kinetics, the segregation taking place in an exponential-like fashion. bromodeoxyuridine becomes incorporated into the nuclear dna and increases the spontaneous segregation rate.	1978	299650
assay method for vibrio cholerae and escherichia coli enterotoxins by automated counting of floating chinese hamster ovary cells in culture medium.	as chinese hamster ovary (cho) cells on plastic proliferate, many cells float off into the medium instead of piling up after they form a monolayer. fewer cells were floating in the medium when cho cells were incubated with cholera toxin at a concentration as low as 10 pg/ml. the toxin increased the adhesiveness of the cells forming confluent monolayers so that the floating cells accumulated on the adherent monolayers. on the basis of this finding, a simple, quantitative assay method for cholera ...	1978	350897
effect of different treatments on the activity of the heat labile enterotoxin of escherichia coli f11(p155).	a whole cell lysate preparation of the escherichia coli strain f11(p155) was treated with the following agents: heat (60 degrees c for 30 minutes), pronase, lipase, amylase, formalin (0.1%), sodium lauryl sulfate (0.05%) and sarkosyl nl30 (0.05%). except for the amylase treatment, the treated whole cell lysate was inactivated when tested in rabbit gut loops or on chinese hamster ovary cells. the preparations treated with heat or formalin could be used to produce a neutralizing antiserum or could ...	1978	352492
effects of asbestos on epithelioid cell lines.	the in vitro effects of asbestos fibers on the growth and viability of cho cells, an epithelioid cell line derived from chinese hamster ovary, and on k-22 cells, an epithelial cell line derived from rat liver, have been studied. relatively low concentrations of asbestos (10 micrograms/ml) were quite cytotoxic to both cell types. a sample of chrysotile asbestos was more toxic than samples of crocidolite or amosite. the toxic factor could not be extracted from the asbestos and toxicity occurred on ...	1978	233816
diphtheria toxin has the properties of a lectin.	the inhibition of protein synthesis in chinese hamster v79 cells by diphtheria toxin is antagonized by the lectins concanavalin a, succinylated concanavalin a, and wheat germ agglutinin but not by proteus vulgaris phytohemagglutinin or abrus agglutinin. the effects of concanavalin a and wheat germ agglutinin are reversed by methyl alpha-mannoside and n-acetylglucosamine, respectively. the inhibition of diphtheria toxin as a function of concanavalin a concentration fits a model of competitive inh ...	1978	272642
tumorigenicity and its suppression in cybrids of mouse and chinese hamster cell lines.	the effect of cytoplasm upon the expression of tumorigenicity was examined with a pair of mouse and a pair of chinese hamster cell lines, in intraspecies cybrids formed by reciprocal fusions between either tumorigenic or nontumorigenic cells and cytoplasms derived from them. with the mouse cells, 3t3 and the simian virus 40-transformed line svt2, the cybrid clones were tumorigenic when svt2 cells were fused with 3t3 cytoplasts, but not in the reciprocal fusion. with the hamster cells, chef/18 an ...	1978	276880
chimeric toxins: toxic, disulfide-linked conjugate of concanavalin a with fragment a from diphtheria toxin.	a disulfide-linked conjugate of concanavalin a (con a) and fragment a from diphtheria toxin has been synthesized and shown to be toxic for hela (human), chinese hamster ovary (cho), and sv3t3 (murine) cells. the conjugate was constructed by first coupling cystamine to con a with a carbodiimide reagent and then reacting the modified con a with reduced fragment a under conditions promoting disulfide interchange. the desired conjugate, obtained in nearly 50% yield relative to input of fragment a, w ...	1978	281682
inducers of dna synthesis present during mitosis of mammalian cells lacking g1 and g2 phases.	the cell cycle analysis of chinese hamster lung fibroblast v79-8 line by the premature chromosome condensation method has confirmed the absence of measurable g1 and g2 periods. sendai virus-mediated fusion of mitotic v79-8 cells with g1 phase hela cells resulted in the induction of both dna synthesis and premature chromosome condensation in the latter, indicating the presence of the inducers of dna synthesis above the critical level not only throughout s phase, as it is in hela, but also during ...	1978	283413
study on the mutagenicity of conjugated estrogens in human, animal and bacterial systems.	conjugated estrogens were studied for mutagenicity (and implied carcinogenicity) in two strains of s. typhimurium, two normal and three neoplastic human lymphoid cell lines (the latter from burkitt's lymphoma patients) in cell culture and a chinese hamster cell line in diffusion chambers implanted into mice. no significant increase in mutation rate or chromosome aberrations were noticed after exposure to conjugated estrogens.	1978	217940
new region of the simian virus 40 genome required for efficient viral transformation.	viable mutants of simian virus 40 with deletions in three regions of the virus genome (map coordinates 0.21-0.17, 0.59-0.54, and 0.67-0.74) have been tested for their ability to transform rat fibroblasts to anchorage independence. only those mutants whose deletions occur between 0.59 and 0.55 in the proximal part of the early region are defective in transforming ability. the most severely defective of these transform with less than one-hundredth the efficiency of wild type. they retain their def ...	1978	209467
homologous genes for enolase, phosphogluconate dehydrogenase, phosphoglucomutase, and adenylate kinase are syntenic on mouse chromosome 4 and human chromosome 1p.	it is possible to generate interspecific somatic cell hybrids that preferentially segregate mouse chromosomes, thus making possible mapping of mouse genes. therefore, comparison of the linkage relationships of homologous genes in man and mouse is now possible. chinese hamster x mouse somatic cell hybrids segregating mouse chromosomes were tested for the expression of mouse enolase (eno-1; ec 4.2.1.11, mckusick no. 17245), 6-phosphogluconate dehydrogenase [pgd; ec 1.1.1.44, mckusick no. 17220], p ...	1978	209463
reexpression of hprt activity following cell fusion with polyethylene glycol.	polyethylene glycol-1000 (peg-1000) induced fusion of hprt (e.c. 2.4.2.8) deficient chinese hamster cells with alpha-galactosidase a (e.c. 2.3.1.22) deficient cells from a patient with fabry's disease yielded hybrids which contained both human and hamster hprt, g6pd (e.c. 1.1.1.49), and aprt (e.c. 2.4.2.7) and chinese hamster alpha-galactosidase b. thus peg-1000 mediated somatic cell fusion led to reexpression of chinese hamster hprt. it did not restore the expression of human alpha-galactosidas ...	1978	209782
shedding of the glycoprotein from vesicular stomatitis virus-infected cells.	in a culture of chinese hamster ovary cells infected with vesicular stomatitis virus, there is specific shedding of viral antigens into the medium. this shedding appears to be unrelated to progeny formation or to cell lysis. although all five of the virus-specific proteins are detected in the extracellular soluble fraction, the major antigen is the gs protein. this protein has a molecular weight of 54,000. indirect analysis of the content of sialic acid as well as peptide analysis of the gs and ...	1978	211264
assignment of the receptor for ecotropic murine leukemia virus to mouse chromosome 5.	the gene for the receptor for ecotropic murine leukemia virus (rev) has been assigned to mouse chromosome 5. this determination was made possible by an analysis of somatic cell hybrids between mouse and chinese hamster cells. the parents of these hybrids were a/hej or mus poschiavinus peritoneal exudate cells or balb/c primary embryo fibroblasts and e36, a chinese hamster lung fibroblast deficient in hypoxanthine guanine phosphoribosyltransferase. segregation of mouse chromosomes in these hybrid ...	1978	212501
cytogenetic studies of a simian virus 40 temperature-sensitive mutant-transformed chinese hamster cell clone at the permissive and nonpermissive temperature.	a clone of chinese hamster embryo cells transformed by tsa58, the temperature-sensitive mutant of simian virus 40, was analyzed for chromosome abnormalities at the permissive temperature (37 degrees c) and nonpermissive temperature (40.5 degrees c). trypsin-giemsa-banded metaphases were analyzed 1 week after the temperature shift. the metaphases from cells at both temperatures were pseudodiploid, with numerous chromosome changes primarily affecting chromosomes no. 1 and 2. other chromosomes (no. ...	1978	212571
simian virus 40 a gene function: dna content analysis of chinese hamster cells transformed by an early temperature-sensitive virus mutant.	replication of two chinese hamster embryo cell lines transformed by an early temperature-sensitive mutant of simian virus 40, tsa58, was examined by flow microfluorometry and autoradiography of [3h]thymidine-labeled cells in order to determine whether transformed cell dna synthesis is initiated by the virus a gene. at the permissive temperature (37 degrees), cells transformed by the mutant were like the wild-type virus transformants in appearance, colony-forming ability, high saturation density, ...	1978	212747
a herpes simplex virus 1 integration site in the mouse genome defined by somatic cell genetic analysis.	transfection experiments with hsv 1 in which one uses herpes simplex virus (hsv) thymidine kinase (tk) as a selectable prototrophic marker yield two classes of transformed cells: stable and unstable. in this report, we test the hypothesis that the stability phenotype can be explained by virus genome integration into a recipient cell chromosome. the method of analysis is by means of somatic cell genetics. we have isolated a series of microcell hybrids between a tk- chinese hamster cell line and a ...	1978	214240
aanlysis of dcmp deaminase and cdp reductase levels in hamster cells infected by herpes simplex virus.	several enzymatic activities involved in the biosynthetic pathways of nucleotides, including thymidine kinase, which has been used as a biochemical marker in studies of gene transfer, are induced by herpes simplex virus (hsv). the utility of additional markers prompted us to reanalyze the effects of hsv infection on the activities of two other enzymes for which direct selective methods can be devised: dcmp deaminase and cdp reductase. for this purpose, mutant chinese hamster (la1) cells devoid o ...	1978	209209
molecular dosimetry of the chemical mutagen ethyl methanesulfonate in escherichia coli and in v-79 chinese hamster cells.		1978	209321
localization of the binding site for cell attachment in the alpha1(i) chain of collagen.	certain cells such as cho (chinese hamster ovary) and fibroblasts attach to a substrate of type i collagen via proteins that link the cell surface to collagen. serum contains a glycoprotein, c-cap (collagen cell attachment protein), that can mediate this adhesion. previously, we established that alpha1(i)-cb7 (cyanogen bromide peptide 7), which lies within residues 552 to 822 of collagen, contains a major binding site for c-cap(alpha1(i)-cb7 has been renumbered to account for an additional tripl ...	1978	209046
localization of a gene for human alpha-galactosidase b (= n-acetyl-alpha-d-galactosaminidase) on chromosome 22.	the localization of the structural gene for human alpha-galactosidase b (= n-acetyl-alpha-galactosaminidase) was investigated by means of man-chinese hamster and man-mouse somatic cell hybrids. the hybrid clones were analyzed for chromosomes and for a large number of known enzyme markers. the lysates of the hybrid cells were treated with sepharose-coupled antihuman alpha-galactosidase b and the activity of the adsorbed enzyme was measured on the sepharose beads as n-acetyl-alpha-galactosaminidas ...	1978	215508
direct fluorescent assay of urokinase and plasminogen activators of normal and malignant cells: kinetics and inhibitor profiles.	a direct rate assay for plasminogen activator has been developed using a synthetic fluorogenic peptide substrate, 7-(n-cbz-glycylglycylargininamido)-4-methylcoumarin trifluoroacetate. the assay correlates well with the standard 125i-labeled fibrin plate assay using highly purified urokinase, culture fluids from wi-38, chinese hamster vary or hela cells, or rous sarcoma virus-transformed chick fibroblasts as the source of plasminogen activator. the assay is sensitive, rapid, and linear throughout ...	1978	204931
a host range difference between herpes simplex virus types 1 and 2.	the infectivities of several strains of herpes simplex virus type 1 and type 2 were measured by plating on established human and chinese hamster cell lines. whereas all the type 1 strains reproducibly showed a 10(4)-fold lower titre on the chinese hamster cells, the type 2 strains showed only a 10- to 100-fold lower titre. this host range difference has been used in the analysis of recombinants between type 1 and type 2 viruses.	1978	206659
mutagenesis of chinese hamster cells in vitro by combination treatments with methyl methanesulfonate and n-acetoxy-2-acetylaminofluorene.	mutational synergism was examined in chinese hamster v79 cells exposed to methyl methanesulfonate followed by n-acetoxy-2-acetylaminofluorene (acaaf) at different time intervals. treatment with 500 micron methyl methanesulfonate resulted in 95% survival of cloning ability and induced approximately 4 azaguanine-resistant mutants/10(5) survivors. seven micron acaaf produced 10 times as many mutants, and the survival was 7%. lethal synergism was observed for methyl methanesulfonate treatments follo ...	1978	208770
expression of "early" and "late" viral functions in a somatic cell hybrid between a mouse cell and a spontaneous yielder sv 40-transformed chinese hamster cell.	a somatic cell hybrid (cl. 6d) was originated from the fusion of mouse 3t3-4e) and spontaneous yielder sv 40-transformed chinese hamster (chk/svlp ag) cells. during the early stages of its history, the c1. 6d hybrid underwent a rapid chromosome loss, preferentially loosing hamster chromosomes. this was not a constant tendency of the hybrid cells. as the parental chk)svlp ag cells, the hybrid cells were always found 100 per cent sv40 t-antigen positive. while chk/svlp ag cells infectious sv 40 dn ...	1978	204268
cotransfer of thymidine kinase and galactokinase genes by chromosome-mediated gene transfer.	the chinese hamster genes for thymidine kinase (atp:thymidine 5'-phosphotransferase, ec 2.7.1.75) and galactokinase (atp:d-galactose 1-phosphotransferase, ec 2.7.1.6) have been cotransferred to mouse cells by chromosome-mediated gene transfer. hamster metaphase chromosomes were incubated with mouse b82 cells and 22 independent colonies were isolated in a selective medium. all of the 12 colonies analyzed expressed the donor form of thymidine kinase; the hamster form of galactokinase was also expr ...	1978	204939
specific changes in the oligosaccharide moieties of vsv grown in different lectin-resistnat cho cells.	the carbohydrate moieties of the g glycoprotein of vesicular stomatitis virus (vsv) grown in three distinct lectin-resistant (lecr) chinese hamster ovary (cho) cell lines have been compared by fine structural analysis of radiolabeled glycopeptides. the mutant wgariii, selected for resistance to wheat germ agglutinin (wga), produces vsv containing g glycoprotein specifically lacking in sialic acid. the mutant phari, selected for resistance to phytohemagglutinin (pha) and previously shown to lack ...	1978	207434
assignment of the gene for adenosine kinase to chromosome 14 in mus musculus by somatic cell hybridization.	evidence is presented for the assignment of the gene for adenosine kinase to mus musculus chromosome 14 by synteny testing and karyotypic analysis of mouse x chinese hamster somatic cell hybrid clones. adok and two enzymes previously mapped to mouse chromosome 14, np and es-10, were expressed concordantly in 29 hybrid clones. chromosome analysis confirmed this assignment. syntenic evidence is also presented using several clones of a gene transfer system in which the gene for human hprt had integ ...	1978	206412
human bronchus-mediated mutagenesis of mammalian cells by carcinogenic polynuclear aromatic hydrocarbons.	cultured human bronchial explants activated benzo[alpha]pyrene (bzap) into electrophilic metabolites that bind to dna in bronchial epithelial cells. promutagenic and mutagenic metabolites of bzap were also released into the culture medium. an increase in mutation frequency for ouabain resistance was found in chinese hamster v-79 cells when they were cocultivated with bronchial explants in the presence of bzap. the proximate carcinogenic form of bzap, the 7,8-diol [(+/-)-r7,t8-dihyroxy-7,8-dihydr ...	1978	148049
liver cell-mediated mutagenesis of mammalian cells by liver carcinogens.	a cell-mediated mutagenesis assay using primary cultures of rat liver cells and v79 chinese hamster cells has been developed. liver carcinogens and their structural analogues were studied. mutations in the v79 cells were characterized by resistance to ouabain. cocultivation of the liver cells and v79 cells in the presence of the carcinogens n-nitrosodimethylamine, n-nitrosodiethylamine, and aflatoxin b1 caused the induction of ouabain-resistant mutants of v79 cells. in the absence of liver cells ...	1978	149308
molecular mechanisms involved in the production of chromosomal aberrations. i. utilization of neurospora endonuclease for the study of aberration production in g2 stage of the cell cycle.	chinese hamster ovary cells (cho) were x-irradiated in g2 stage of the cell cycle and immediately treated, in the presence of inactivated sendai virus, with neurospora endonuclease (e.c. 3.1.4.), an enzyme which is specific for cleaving single-stranded dna. with this treatment, the frequencies of all types of chromosome aberrations increased when compared to x-irradiated controls. these results are interpreted as due to the conversion of some of the x-ray induced single-stranded dna breaks into ...	1978	83535
functional heterogeneity of transferrin-bound iron: iron uptake by cell suspensions from bone marrow and liver and by cell cultures of fibroblasts and lymphoblasts.	according to the hypothesis of fletcher and huehns, functional differences exist between both iron-binding sites of transferrin. the site designated a should mainly be involved in the delivery of iron to erythroid cells, whereas site b should donate its iron preferentially to cells involved in the absorption and storage of iron. in the present study this hypothesis could be confirmed by in vitro experiments with various cell types. iron transferrin preincubated with rat bone marrow cells donates ...	1978	101008
absence of mutagenicity of praziquantel, a new, effective, anti-schistosomal drug, in bacteria, yeasts, insects and mammalian cells.	praziquantel (embay 8440, droncit) a new, effective anti-schistosomal drug, was tested in various short-term assays that have shown a predictive value for the detection of potential carcinogens. indicator organisms s. typhimurium strains, s. pombe, s. cerevisiae, cultured v79 chinese hamster cells or human heteroploid cells and drosophila melanogaster were treated with praziquantel. the induction of reverse and forward mutations, mitotic gene conversions, x-linked recessive lethals, sister-chrom ...	1978	106268
growth of infective forms of trypanosoma (t.) brucei on buffalo lung and chinese hamster lung tissue culture cells.	infective cultures of trypanosoma (t.) brucei (strain 427) have been initiated and maintained on chinese hamster lung tissue culture cells and buffalo lung tissue culture cells. by changing daily one-third of the rpmi-1640 plus 20% fetal bovine serum medium, the cell numbers can be maintained at 2--4 x 10(6) cells/ml. the cultured trypanosomes on these two tissue culture cell types were infective to mice and morphologically similar to bloodstream slender trypomastigotes in having a subterminal k ...	1978	31773
interspecies interactions of arboviruses. iii. competition for virus envelope antigens in mixed getah and sindbis virus populations.	interactions of getah and sindbis virus populations in mixed infections of 5 tissue systems were competitive or neutral. the type of interaction is regulated by the host cell and virus population density. on reproduction in mouse brains and spev cell cultures the mixed population exhibited antigenic markers of getah virus; in syrian hamster kidney and chick embryo cell cultures those of sindbis virus; and in chinese hamster kidney cell cultures the antigenic markers of both viruses. mixed popula ...	1978	29465
gamma-glutamyltransferase in human diploid fibroblasts and other mammalian cells.	gamma-glutamyltransferase was determined in wi-38 human diploid fibroblasts and compared to enzyme levels determined in several other mammalian cell lines including: fibroblast-like cells from human skin, tibia and foreskin; epithelial-like cells from human, bovine and monkey kidney; and transformed cells (chinese hamster ovary, hela s3 and sv-40 transformed wi-38). transformed cells had the lowest activity found followed in increasing order by fibroblasts, human and bovine epithelial cells and ...	1978	27446
a new immunochemical method for the quantitative measurement of specific gene products in man-rodent somatic cell hybrids.	an immunochemical method has been developed for the quantitative determination of species-specific gene products, for instance alpha-galactosidase and n-acetyl-alpha-galactosaminidase, in man-rodent hybrid cells and in the parental cell lines. antisera raised against the purified enzymes are covalently coupled to sepharose 4b. the gene products are specifically removed from a cell lysate by incubating with the appropriate sepharose-coupled antiserum. after centrifugation followed by washing of t ...	1978	83282
[modified method of differential staining of sister chromatids].	a modified method of obtaining differential staining of sister chromatids is described. it is simple, rapid, and effective, and at the same time inexpensive and accessible, since it allows one to use available reagents. when 5-bromdeoxyuridine was administered 24 hours before fixation into the chinese hamster cell culture the percentage of metaphases with a differential chromatid staining constituted 95--98, and when this substance was administered 28 hours before fixation into the human lymphoc ...	1978	75748
sister-chromatid exchanges induced in rabbit lymphocytes by 2-aminofluorene and 2-acetylaminofluorene after in vitro and in vivo metabolic activation.	because short in vitro treatments of chinese hamster cells with 2-aminofluorene and 2-acetylaminofluorene did not increase sces even in the presence of a metabolic activation system, experiments were carried out with rabbits to see if in vivo activation occurred. rabbits injected with 2-af could activate the compound and a transient dose-dependent increase in sces was found in peripheral lymphocytes cultured at various times after the injection. with 2-aaf, however, the response was more variabl ...	1978	745622
cellular and molecular studies on globin gene expression.	globin gene expression has been studied with the use of a combination of cell and molecular biology techniques. with a somatic cell hybrid between mouse erythroleukemia (mel) and human erythroid cells, human and mouse globin genes can be coexpressed in the same hybrid cell. somatic cell hybridization between mel cells and nonerythroid cells (e.g., human fibroblasts) results in hybrid cells that cannot be induced to produce hemoglobin of any type. molecular hybridization of cellular dna and rna w ...	1978	748760
toward the development of a standard reference cholera antitoxin.	the need for a reference cholera antitoxin to serve as a standard for the calibration of cholera enterotoxin and toxoid as well as for measurement of the antitoxin response in animals and patients was recognized by the nih cholera advisory committee, niaid, dhew, usa. two cholera antitoxins have been used for several years as provisional references, but neither was considered to embody all of the properties of an ideal standard. accordingly, a lot of cholera antitoxin was prepared by immunizatio ...	1978	753669
dna single-strand lesions due to 'sunlight' and uv light: a comparison of their induction in chinese hamster and human cells, and their fate in chinese hamster cells.		1978	674395
the incorporation of homologous and heterologous hypoxanthine-guanine phosphoriboxyltransferase into mutant cells.	experiments are described leading to partial compensation of a deficiency in the enzyme hypoxanthine-guanine phosphoribosyltransferase in mutant cells by supplying the cells with exogenous purified enzymes. deae-dextran is an effective helper agent, whereas poly (l-lysine), lysolecithin and amphotericin b seem to inhibit the entry of the enzymes of their activity. enzyme preparation from chinese hamster was found to have different effects in different mutant cell lines. in mutant chinese hamster ...	1978	563735
mutagenicity studies with praziquantel, a new anthelmintic drug, in mammalian systems.	praziquantel, a new anthelmintic drug with antischistosomal and anticestodal properties, was tested in comparison with a placebo control and a 'positive control' with cyclophosphamide in mammalian test system in vivo for potential mutagenic effects. the test systems used and the tested doses of praziquantel were: (1) dominant lethal test on male nmri mice, 12 mating periods of 4 days each, 1 x 1200 mg/kg bw by mouth; (2) dominant lethal test on female nmri mice, treatment during pre-estrus, 1 x ...	1978	580366
mutagenicity and carcinogenicity of 8-mop/uva in cell cultures.	hgprt-deficient mutants of chinese hamster cells and human skin fibroblasts are selected with 6-thioguanine after treatment with the combination 8-mop and uva. calculation based on this study indicate that 1.7 x 10(-5) mutants will be induced in the epidermis per session of puva therapy. induction of cell-transformation was observed in c3h and 3t3 mouse cells.	1978	719181
ghost-mediated transfer of human hypoxanthine-guanine phosphoribosyl transferase into deficient chinese hamster ovary cells by means of polyethylene glycol-induced fusion.		1978	689099
assignment of peptidase s (peps) to chromosome 4 in man using somatic cell hybrids.	a starch gel electrophoretic procedure is described that resolves peptidase s (peps) as well as the peptidases a, b, and c in man-rodent, rodent-rodent, and primate-rodent interspecific somatic cell hybrids. the interspecific peps cell hybrid phenotype can be resolved into a pattern which suggests that peps is composed of five or six identical subunits. results are presented supporting assignment of the peps locus to chromosome 4 in man using man-mouse and man-chinese hamster somatic cell hybrid ...	1978	689684
genetic analysis of tumorigenesis: i. expression of tumor-forming ability in hamster hybrid cell lines.	two new fibroblasts cell lines from a male chinese hamster embryo are described: one tumorigenic in nude mice (chef 16-2) and the other not (chef 18-1). both lines have a stable diploid mode and mean of 22 with 10 pairs of homologous autosomes. the cell lines differ unambiguously in cloning ability in methylcellulose, colony morphology, and tumorigenicity; the expression of these traits was examined in a set of 18-1 x 16-2 hybrid clones. the results show initial suppression of tumorigenicity and ...	1978	694725
assignment of the gene for glyoxylase i to mouse chromosome 17 by somatic cell genetics.	evidence is presented for the assignment of the gene for glyoxylase i to mouse chromosome 17 using mouse x chinese hamster somatic cell hybrids. glo i was not expressed concordantly with any known marker enzymes which represented 11 linkage groups. the presence of chromosome 17 and expression of glo i were concordant in 31/31 clones. glo i is thus linked to the h-2 histocompatibility locus in the mouse.	1978	569476
replicon sizes in mammalian cells as estimated by an x-ray plus bromodeoxyuridine photolysis method.	a new method is described for estimating replicon sizes in mammalian cells. cultures were pulse labeled with [3h]thymidine ([3h]tdr) and bromodeoxyuridine (brdurd) for up to 1 h. the lengths of the resulting labeled regions of dna, lobs, were estimated by a technique wherein the change in molecular weight of nascent dna strands, induced by 313 nm light, is measured by velocity sedimentation in alkaline sucrose gradients. if cells are exposed to 1,000 rads of x-rays immediately before pulse label ...	1978	570067
surface functions during mitosis i: phagocytosis, pinocytosis and mobility of surface-bound con a.	phagocytosis, pinocytosis and the surface distribution of concanavalin a (cona) have been analyzed during mitosis in several mammalian cell lines. use of the bisbenzimidazole dye, hoechst 33258, for chromosome staining after gentle fixation made possible the rapid identification and correlation of mitotic phase with surface properties. phagocytosis of both opsonized and nonopsonized particles is markedly depressed in mitotic cells of the mouse macrophage cell line j774.1. the uptake of opsonized ...	1978	719746
increased tissue conductance and ion transport in guinea pig ileum after exposure to staphylococcus aureus delta-toxin in vitro.	prior studies had shown that staphylococcus aureus delta-toxin was able to inhibit water absorption in guinea pig ileum and to elevate the cyclic amp content of this tissue, but was unable to elicit certain cyclic amp-mediated changes in y-1 adrenal or chinese hamster ovary cells. because water movement passively follows the net movement of electrolytes in the gut, this study investigated the effect of delta-toxin on ion transport in guinea pig ileum maintained in vitro. the transmural potential ...	1978	711309
growth of infective forms of trypanosoma rhodesiense in vitro, the causative agent of african trypanosomiasis.	a new approach to the culture of african trypanosomes led to the growth of the infective forms of the causative agent of human african trypanosomiasis. infective cultures of trypanosoma rhodesiense were initiated and maintained in vitro on chinese hamster lung cells. by changing daily one-third of the hepes-buffered rpmi 1640 medium containing 20 percent fetal bovine serum, the trypanosome numbers increased to 3 x 10(6) to 5 x 10(6) cells per milliliter. after 80 days in vitro at 37 degrees c, t ...	1978	715441
induced segregation of human syntenic genes by 5-bromodeozyuridine + near-visible light.	chromosome-breaking agents have been used in two different procedures for promoting segregation of syntenic genes on human chromosome 12. in method a, a human-chinese hamster cell hybrid containing the single human chromosome 12 was treated either with 5-bromodeoxyuridine brdu + near-visible light or with x-rays. in method b, normal human fibroblasts were treated with brdu + near-visible light followed by their fusion with a chinese hamster glycine-requiring cell mutant cho-k1/gly-a. since the h ...	1978	684558
hypoxanthine phosphoribosyltransferase from chinese hamster brain and human erythrocytes.		1978	692400
aconitase (e.c. 4.2.1.3) mitochondrial locus mapped to human chromosome 22: studies with chinese hamster--human somatic cell hybrids.	three separate somatic cell fusions were made between chinese hamster lines and human lymphocytes containing (1) a 3/4 translocation, (2) an x/9 translocation, and (3) a 17/9 translocation. eleven independently derived hybrids showed that only human chromosome 22 was consistently present when human aconm was expressed and absent when human aconm was not expressed. these studies assign a gene for human aconm to chromosome 22, and are consistent with prior gene-mapping results.	1978	728065
genetic analysis of cell malignancy--evidence from somatic cell genetics.	when normal nontumorigenic cells are fused with tumorigenic cells some of the resulting hybrids are nontumorigenic in respect to their ability to grow in immune-deficient nude mice. comparison of the chromosome content of nontumorigenic with tumorigenic hybrids, as well as with the cells of tumors which develop from the latter, reveals that in normal human x tumorigenic chinese hamster hybrid crosses, two specific human chromosomes of the nontumorigenic parental line are very likely responsible ...	1978	728675
responses of mammalian metaphase chromosomes to endonuclease digestion.	digestion of fixed metaphase chromosomes by endonucleases (micrococcal nuclease and dnase ii) under optimal digestion conditions followed by giemsa staining produces sharp banding patterns identical to g-bands. in 3h-thymidine labeled, synchronized metaphase cells of the chinese hamster (cho line), the band induction is accompanied by the removal of dna. the single strand specific nuclease s1 and dnase i do not produce such banding patterns.	1978	743903
cytogenetic effects of inhaled ozone.	we have repeated as closely as possible the experiments of zelac et al., who observed significantly elevated levels of chromosome aberrations in short-term cultures of peripheral lymphocytes from chinese hamsters that had inhaled ozone. unlike zelac et al., we observed no increase in chromosome-type aberration levels, though a small increase in chromatid-aberration levels similar to that reported for exposed human subjects by merz et al. was seen. no increase in the levels of any chromosomal abe ...	1978	745619
isolation of mutant mammalian cells altered in polyamine transport.	chinese hamster ovary and rat myoblast cells resistant to the toxic action of methylglyoxal bis guanylhydrazone (mgbg), an antimitotic agent and inhibitor of polyamine synthesis, have been isolated by single step selection. mutagenesis with ethyl methanesulfonate increases the recovery of the variants at least 30-fold. intracellular accumulation of mgbg is greatly reduced in resistant cells. this property is accompanied by a 99% decrease in the uptake of all three naturally occurring polyamines. ...	1978	730773
excorporation efficacy with ca-dtpa of 241am and 252cf in the skeleton, liver, and kidney of the rat and syrian and chinese hamsters: lack of correlation with the biological half-times.		1978	734050
[electron microscopic study of mammalian somatic cell fusion under the action of polyethylene glycol].	an electron microscope study of heterokaryons and synkaryons, obtained after the treatment of suspension of human embryonic fibroblasts and cultured fibroblasts of chinese hamster (clone m151) with polyethylene glycol (pec, m. v. 6000) has shown that in 15 minutes after the administration of peg, the cell agglutination and disappearance of plasma membranes between cells takes place. it is not obvious, however, how per is passing through the cell envelope, but the similar action of pef towards th ...	1978	734774
assignment of the gene for dipeptidase 2 to mus musculus chromosome 18 by somatic cell hybridization.	evidence is presented for the assignment of the gene for dipeptidase 2 to mus musculus chromosome 18 by synteny testing and karyotypic analysis of chinese hamster x mouse somatic cell hybrid clones. dip-2 and chromosome 18 were expressed concordantly in 24/24 clones examined (ten primary clones and 14 secondary clones). synteny testing indicated that dip-2 was not expressed concordantly with the expression of any marker enzymes.	1978	736882
assignment of a human galactose-1-phosphate uridylyltransferase gene (galt1) to chromosome 9 in human-chinese hamster somatic cell hybrids.		1978	752475
[in vitro effect of asbestos fibers on short-term cultures of human lymphocytes].	the endocellular incorporation of asbestos fibres seems to be capable to induce on chinese hamster cell cultures numerical and structural chromosome aberrations. in the present study asbestos fibres have been added at different concentrations to human cultured lymphocytes which have been harvested at 48 and 72 h, respectively. the results do not show significant difference in the distribution of chromatid and chromosome-type aberrations between the control cultures and the cultures treated with ...	1978	755418
brefeldin a-induced increase of sphingomyelin synthesis. assay for the action of the antibiotic in mammalian cells.	brefeldin a leads to an increase of sphingomyelin in chinese hamster ovary cells. the antibiotic is known to cause a dramatic morphological change of the endomembrane system in various mammalian cells resulting in a redistribution of golgi resident proteins to the endoplasmic reticulum (lippincott-schwartz, j., donaldson, j. g., schweizer, a., berger, e. g., hauri, h. p., yuan, l. c., and klausner, r. d. (1990) cell 60, 821-836). a strict correlation was found between the brefeldin a-induced inc ...	1978	1544889
an analysis of concanavalin a-mediated agglutination in two chinese hamster ovary subclones whose surface phenotypes respond to maintenance in medium supplemented with dibutyryl cyclic amp. v. biochemical composition of the plasma membrane.	we have used two chinese hamster ovary subclones whose surface phenotype has been extensively investigated with regard concanavalin a-mediated cell-cell agglutination and concanavalin a-induced receptor site clustering to investigate what changes in membrane composition, if any, can be correlated with the concanavalin a-detected changes in surface phenotype. these cell clones are uniquely disposed for this purpose since maintenance of the cells under different growth conditions produces changes ...	1978	218629
kinetics of dna repair in ultraviolet-irradiated and n-acetoxy-2-acetylaminofluorene-treated mammalian cells.	repair kinetics after saturating doses of ultraviolet radiation (uv), n-acetoxy-2-acetylaminofluorene (aaaf), and combinations of both agents were studied in human fibroblasts proficient and deficient in excision repair, and in chinese hamster cells (v-79) deficient in excision repair. three techniques were used: unscheduled dna synthesis, photolysis of dna repaired in the presence of bromodeoxyuridine (brdurd), and measurements of sites sensitive to a uv-endonuclease. the repair rate appears to ...	1978	19431355
tyrosyltubulin ligase and colchicine binding activity in synchronized chinese hamster cells.	tyrosyltubulin ligase (ttl) was found to be present in cho and v79 chinese hamster cells grown in tissue culture. the enzyme is soluble and requires potassium, magnesium, and atp for maximum activity and requires tubulin as a substrate. ttl was analyzed through the cell cycle of v79 and cho chinese hamster cells. the enzyme showed two peaks of activity in v79 cells at 4 h and 7 h after mitotic selection, corresponding to the early s and mid to late s phases of the cell cycle. in cho cells the en ...	1978	567652
conjugation of methotrexate to poly(l-lysine) increases drug transport and overcomes drug resistance in cultured cells.	methotrexate and [(3)h]methotrexate were conjugated through a carbodiimide-catalyzed reaction to a 70,000 molecular weight poly(l-lysine) in molar ratios of approximately 13 to 1. the cellular uptake of labeled conjugate was far in excess of the uptake of free drug in cells that were either proficient or deficient in methotrexate transport. the conjugate markedly inhibited the growth of pro(-)3 mtx(rii) 5-3 chinese hamster ovary cells, which are known to be drug resistant by virtue of a deficien ...	1978	279001
messenger rna synthesis in synchronized chinese hamster ovary cells.	chinese hamster ovary cells were synchronized without inhibitors by mitotic selection and labelled in g1, s or g2 phase by incubation for 90 min with [3h]- or [14c]uridine. purified polyribosomes were extracted with phenol and the polyadenylated mrna prepared by poly(u)-sepharose chromatography. poly-adenylated [3h]uridine-labelled mrna from the g1 phase of the cell cycle was compared by exponential polyacrylamide gel electrophoresis in formamide with [14c] uridine-labelled polyadenylated nrna f ...	1978	667072
effects of cis-platinum(ii) diamminedichloride on survival and the rate of dna synthesis in synchronously growing chinese hamster v79-379a cells in the absence and presence of caffeine inhibited post-replication repair; evidence for an inducible repair mechanism.	the mechanism by which cis-platinum(ii)diamminedichloride, (cis-pt(ii)), inhibited dna synthesis was investigated using synchronously growing chinese hamster v79-379a cells. the progression of g1 phase treated cells into s phase was not inhibited. however the rate of dna synthesis throughout the s phase was depressed in a dose dependent manner compared to a control. the peak rate of dna synthesis was delayed and the duration of the s phase was extended resulting in a dose dependent delay in the ...	1978	699192
hyperthermic radiosensitization of synchronous chinese hamster cells: relationship between lethality and chromosomal aberrations.		1978	569879
ribonucleotide reductase from wild type and hydroxyurea-resistant chinese hamster ovary cells.	the kinetic properties of partially purified ribonucleotide reductase from chinese hamster ovary cells have been investigated. double reciprocal plots of velocity against substrate concentration were found to be linear for three the substrates tested, and yielded apparent km values of 0.12 mm for cdp, 0.14 mm for adp and 0.026 mm for gdp. hydroxyurea, a potent inhibitor of ribonucleotide reduction, was tested against varying concentrations of ribonucleotide substrates and inhibited the enzyme ac ...	1978	568630
genetic characterization of hydroxyurea-resistance in chinese hamster ovary cells.	hydroxyurea is an excellent selective agent for obtaining drug-resistant mutants. at a frequency of approximately 1 x 10(-5) it was possible to select, in a single step, colonies that exhibited significant resistance to the cytotoxic effects of the drug. these hydroxyurea-resistant cell lines maintained their resistant phenotype after extensive cultivation in the absence of the drug. reconstruction experiments indicated that the expression of hydroxyurea-resistance and the frequency of drug-resi ...	1978	568629
[chromosome aberrations and sister chromatid exchanges following exposure of cultured chinese hamster cells to ftorafur and 5-fluorouracil].		1978	363505