Publications

chromatid breaks induced in chinese hamster cells by low doses (12--100 rad) of pi--mesons.	monolayer cultures of the fibroblast-like chinese hamster cell-line 19/1 were irradiated in the g2-phase of the cell cycle by pi--mesons (6 rad/min peak-pion dose rate). frequencies of induced single- and isochromatid breaks, acentric fragments and interchanges were compared with data obtained from 140 kv x-rays. the rbe-values were for the pion dose peak between 0.8--1.2 and for the pion dose plateau 0.5--0.9. whereas for single chromatid breaks there was no significant difference between x-ray ...	1979	504558
biological effects of negative pions in monolayers and spheroids of chinese hamster cells.	the therapeutic value of pion irradiation was critically challenged by examining, in a cell culture system, various parameters of biological significance such as relative biological efficiency (rbe), oxygen enhancement ratio (oer), dna-break formation, changes in cell cycle kinetics and regrowth. in all parameters, pions were superior to conventional low-let radiation.	1979	504557
cell survival over the depth profile after irradiation with a negative pion beam.	the colony-forming ability of chinese hamster fibroblast cells in vitro has been investigated throughout the depth dose profile of a negative pion beam. in the peak and 2 cm beyond, the rbe for macroclones (more than 50 cells per clone) was 1.3 and in the plateau region 0.8--1.0. all of the microclones (2-49 cells per clone) were observed as well. the rbe values are the same for peak and somewhat higher for plateau and post peak than found in cell survival studies referring to macroclones.	1979	504556
the effect of cis-platinum on the repair of radiation damage in plateau phase chinese hamster (v-79) cells.		1979	575118
survival and kinetics of chinese hamster ovary cell subpopulations induced by adriamycin and radiation.		1979	528270
adriamycin uptake in v79 and adriamycin resistant chinese hamster cells.		1979	528269
relationship between dna alkylation and specific-locus mutation induction by n-methyl- and n-ethyl-n-nitrosourea in cultured chinese hamster ovary cells (cho/hgprt system).	chinese hamster ovary (cho) cells in culture were utilized to determine the cytotoxicity, specific-locus mutation induction, and dna alkylation which result from treatment of the cells with a range of concentrations of n-methyl-n-nitrosourea (mnu) or n-ethyl-n-nitrosourea (enu). with [3h]mnu over the concentration range 0.43--13.7 mm, methylation of dna was found to increase linearly, with a mean value of 56.7 pmol residue per mumol nucleoside per mm. with [1-3h]enu over the concentration range ...	1979	509687
anomalous dose-response characteristics induced by caffeine in ultraviolet-irradiated v79--79 chinese hamster cells.		1979	504354
a quantitative comparison of the mutagenicity of carcinogenic polycyclic hydrocarbon derivatives in cultured mammalian cells.	the mutagenicity of a series of reactive polycyclic hydrocarbon derivatives has been studied using chinese hamster (v79) cells in culture and, as a mutational marker, resistance to the purine analogue 8-azaguanine. the compounds were compared by relating mutation frequency to the dose applied (mutagenic effectiveness) to induced cytotoxicity (mutagenic efficiency) and to the extent of reaction of the hydrocarbon with dna (absolute mutagenic efficiency). in each case anti-benzo(alpha)pyrene (bp)- ...	1979	489163
binding of concanavalin a to chinese hamster ovary cells after storage in liquid nitrogen.		1979	487848
production of mrna in chinese hamster cells: relationship of the rate of synthesis to the cytoplasmic concentration of nine specific mrna sequences.	we constructed cloned dna sequences complementary to unselected mrnas [poly(a)+ cytoplasmic rna] from chinese hamster ovary cells and used them in rna:dna hybridization experiments. each cloned dna hybridized a single mrna from 1.3-3.5 kb in length. the relative rates of labeling (transcription rates) of nuclear rna complementary to each individual dna segment varied approximately 10 fold. the relative cytoplasmic concentration of the same specific rna sequences in the mrna after an equilibrium ...	1979	487428
the effect of a tumor promotor, 12-o-tetradecanoyl-phorbol-13-acetate (tpa), on sister-chromatid exchange formation in cultured chinese hamster cells.	the tumor promoter 12-o-tetradecanoyl-phorbol-13-acetate (tpa) does not increase the sister-chromatid exchange (sce) frequency in either chinese hamster ovary (cho) or lung (v 79) cells which are cultured in the presence of 5-bromodeoxyuridine. moreover, tpa does not alter the induction of sces in cho cells by mitomycin c during the first 3 cycles following addition of the alkylating agent. these sce induction data do not by themselves support the hypothesis that tumor promotion by tpa depends o ...	1979	481459
induction of 8-azaguanine- and ouabain-resistant mutants by cyclophosphamide and 1-(pyridyl-3)-3,3-dimethyltriazene in chinese hamster cells cultured in diffusion chambers in mice.	a host-mediated assay is described for induction of 8-azaguanine-resistant (azgr) and ouabain-resistant (ouar) mutants in chinese hamster v79 cells cultured in diffusion chambers (dc) in c3h mice. injection of the hosts with the indirect mutagen/carcinogen cyclophosphamide (cpp) or 1-(pyridyl-3)-3,3-dimethyltriazene (pydt) caused a dose-dependent increase in mutation frequency at the loci of azgr and ouar in the v79 target cells. plating efficiency of v79 cells in dc in mice was decreased depend ...	1979	481447
chinese hamster ovary cell population density affects intracellular concentrations of calcium-dependent regulator and ability of regulator to inhibit adenylate cyclase activity.	the adenylate cyclase activity [atp pyrophosphate-lyase (cyclizing), ec 4.6.1.1] of crude chinese hamster ovary cell membranes was inhibited 30-40% by low concentrations (6-600 ng/ml) of calcium-dependent regulator (cdr). this inhibitory effect was lost at concentrations of cdr above 600 ng/ml. the adenylate cyclase activity of membranes prepared from low population density chinese hamster ovary cells was not appreciably altered by cdr. however, with increasing cell population density there was ...	1979	226991
interactions of the carcinogen 4-nitroquinoline 1-oxide with the non-protein thiols of mammalian cells.	the carcinogen 4-nitroquinoline 1-oxide (4-nqo) was found to rapidly deplete non-protein thiols (npsh) from ehrlich ascites tumor cells and v79 chinese hamster fibroblasts. the effects of npsh on 4-nqo metabolism were studied by measuring 4-hydroxyaminoquinoline 1-oxide formation, cn- -insensitive oxygen consumption, and reduction of ferricytochromes c + c1 in normal cells and in cells pretreated with the thiol reagent n-ethylmaleimide. removal of thiols before treatment with 4-nqo resulted in i ...	1979	110443
neurogenesis in the basal forebrain of the chinese hamster (cricetulus griseus). i. time of neuron origin.	the time of neuron origin has been determined in the basal ganglia and related basal forebrain structures of the chinese hamster with the aid of 3h-thymidine autoradiography. large-celled structures like the globus pallidus, nucleus of the horizontal limb of the diagonal band of broca as well as large cells in the rostral part of the substantia innominata, in the caudate-putamen-complex and in the olfactory tubercle arise early (e12--e16), whereas medium-sized and small cells in the basal forebr ...	1979	475002
dependence of mammalian dna replication on dna supercoiling. ii. effects of novobiocin on dna synthesis in chinese hamster ovary cells.	novobiocin, an inhibitor of gyrase-induced dna supercoiling and dna replication in prokaryotes, inhibited the incorporation of dna precursors into dna in both intact and permeable chinese hamster ovary cells; much higher concentrations were required for permeable cells, in which no new replicons were initiated. nucleoids were prepared from cells that were incubated for 60 min with 200 micrograms/ml novobiocin, made permeable, and incubated with 0--50 micrograms/ml ethidium bromide. sedimentation ...	1979	465492
dependence of mammalian dna replication on dna supercoiling. i. effects of ethidium bromide on dna synthesis in permeable chinese hamster ovary cells.	chinese hamster ovary cells labelled with [14c]thymidine were made permeable, incubated with various concentrations of the intercalating dye ethidium bromide, and centrifuged through neutral sucrose gradients. the gradient profiles of these cells were qualitatively similar to those obtained by centrifuging dna from untreated, lysed permeable cells through gradients containing ethidium bromide. the sedimentation distance of dna had a biphasic dependence on the concentration of ethidium bromide, s ...	1979	465491
emetine-resistant chinese hamster cells. the identification of an electrophoretically altered protein of the 40 s ribosomal subunit.		1979	447708
phosphorylation of the 10-nm filament protein from chinese hamster ovary cells.		1979	447707
respiration-deficient chinese hamster cell mutants: biochemical characterization.	we have previously classified 35 of our respiration-deficient mutants into seven complementation groups and one "overlapping" mutant which does not complement mutants from groups i and ii. in this paper we report on the biochemical characterization of representatives of complementation groups i, ii, vii, and the "overlapping" mutant. we show that these mutants all have a defect in complex i of the electron-transport chain. the general features of these mutants are: (1) a low rate of o2 consumpti ...	1979	494059
cadmium-induced alterations in rna metabolism in cultures of chinese hamster cells sensitive to and resistant to the cytotoxic effects of cadmium.	a variant population (cdr) of cultured chinese hamster cells (line cho) was derived that is more than 100 times as resistant to the cytotoxic effects of cd2+ than is the parent population. the effects on rna metabolism of exposure to sublethal concentrations of cd2+ were studied in cho and cdr. exposure to 2 x 10(-7) m cdcl2 for 24 h resulted in increased polysome content (1.2 times) and increased uridine or adenosine incorporation into heterogeneous nuclear rna (1.2-1.4 times) and messenger rna ...	1979	490682
[variability of chinese hamster clones in resistance to 8-azaguanine].	the stability of the 8-azaguanine resistance marker during the number of cell generations has been analyzed for 63 clones of chinese hamster cells. the resistant clones analyzed were spontaneous or induced after the treatment of parent cells by 5-budr, ems, or histone h1. the clones have revealed different levels of ag-resistance as well as different ability to maintain the above level, under the cultivation in the drug-free medium. subclones, isolated from the unstable clone, were found to be d ...	1979	483396
mutagenicity, cytotoxicity and dna crosslinking in v79 chinese hamster cells treated with cis- and trans-pt(ii) diamminedichloride.	the mutagenicity and cytotoxicity of cis- and trans-pt(ii) diamminedichloride (pdd) were examined in v79 chinese hamster lung cells and compared with effects on dna measured by alkaline elution. dna--protein crosslinks and dna interstrand crosslinks were detected following doses of cis-pdd which reduced cell survival 80--90% and which produced a mutant frequency of 3 x 10(-4) at the hgprt locus. equitoxic doses of trans-pdd were much less mutagenic than cis-pdd. at equitoxic doses, trans-pdd pro ...	1979	481452
chromosomal aberrations induced by maleic hydrazide and related compounds in chinese hamster cells in vitro.	the cytotoxic effects and chromosomal abnormalities induced by maleic hydrazide (mh) and its salts were investigated in cultured v79 cells. mh, and its potassium (k-mh) and diethanolamine (dea-mh) salts were tested. mh was 5--14 times more cytotoxic than its salts and almost 4.5 times less toxic than the related compound, hydrazine dihydrochloride (hdc). mh salts had very weak cytotoxicity; the ld50 values on v79 cells on exposure for 3 h in vitro were (in microgram/ml) 1100 (mh), 12 000 (dea-mh ...	1979	481451
chromosomal aberrations and sister-chromatid exchanges in chinese hamster cells treated in vitro with hexavalent chromium compounds.	chinese hamster cells (cho line) were treated in vitro for 30--39 h with hexavalent chromium compounds (k2cr2o7 and na2cro7), at concentrations ranging from 0.1 to 1.0 microgram of cr6+ per ml, in medium containing budr. chromosomal aberrations and sister-chromatid exchanges were scored on budr-labelled 2nd division metaphases, collected at the end of treatment and stained with giemsa. treatment with mitomycin c 0.009--0.030 microgram/ml) was carried out as a control for the responsiveness of th ...	1979	481449
facilitation by pyrimidine deoxyribonucleosides and hypoxanthine of mutagenic and cytotoxic effects of monofunctional alkylating agents in chinese hamster cells.	hypoxanthine (hx), thymidine (tdr) and deoxycytidine (cdr), at concentrations of 10(-5) m increased the yield of 8-azaguanine-resistant (azgr) mutants induced by n-methyl-n'-nitro-n-nitrosoguanidine (mnng) in cultured chinese hamster v79 cells. the cytotoxicity of mnng was increased 2-fold in the presence of hx, and more than 10-fold in the presence of tdr. this cytotoxic effect of tdr was abolished by equal concentrations of cdr, which by itself did not increase the cytotoxicity of mnng. howeve ...	1979	481439
combined effects of x irradiation and hyperthermia (42 and 44 degrees c) on chinese hamster v-79 cells in vitro.		1979	472127
characteristics of concanavalin a-resistant chinese hamster ovary cells and certain revertants.	clones of chinese hamster ovary (cho) cells were isolated by single-step selection for resistance to killing concanavalin a (cona) and certain cellular and membrane properties were examined. the cona-resistant isolates were only about 2-fold more resistant than wild type cells to the selecting lectin, but exhibited pleiotropic temperature-sensitivity for growth, markedly altered morphology and adherence, and significant difference in susceptibility to other agents such as colchicine. two reverta ...	1979	468920
transformed cells have lost control of ribosome number through their growth cycle.	previous studies on the synthesis and function of the protein synthetic machinery through the growth cycle of normal cultured hamster embryo fibroblasts (ha) were extended here to a series of four different clonal lines of polyoma virus-transformed ha cells. under our culture conditions, these transformed cells could enter a stationary phase characterized by no mitotic cells, very low rates of dna synthesis, and arrest in a post-mitotic pre-dna synthetic state. cellular viability was initially h ...	1979	468917
differential metabolism of mannose by chinese hamster cell lines.		1979	446534
effects of hyperthermia (45 degrees) on macromolecular synthesis in chinese hamster ovary cells.		1979	445469
induction of thermotolerance by multiple heat fractions in chinese hamster ovary cells.		1979	445450
genetic analysis of tumorigenesis: iv. chromosome reduction and marker segregation in progeny clones from chinese hamster cell hybrids.	hybrid cells produced by the fusion of pairs of cells, one a tumorigenic derivative of chef/16 and the other a nontumorigenic derivative of chef/18, give rise to clones which are largely tetraploid, but rare reduced hybrids with chromosome counts in the diploid range have been recovered from tumors of hybrid origin. this paper describes the recovery in cell culture of reduced hybrids in the diploid range by selection with 5-bromodeoxyuridine (brdu) or methylcellulose as well as by growth in cult ...	1979	291130
codominant translational mutants of chinese hamster ovary cells selected with diphtheria toxin.	diphtheria toxin-resistance markers in two translational mutants, ch-re1.22c, possessing no toxin-sensitive ef-2 (class iia), and ch-re1.32, with 50% toxin-sensitive and 50% toxin-resistant ef-2 (class iib), behaved codominantly in somatic cell hybrids. there was no complementation in hybrids formed between the two resistant mutants. the mutant parents and their hybrids, except those formed by fusion of ch-re1.32 and wild-type cells, grew in the presence of toxin. to explain these results we sug ...	1979	291128
changes in repair competency after 5-bromodeoxyuridine pulse labeling and near-ultraviolet light.	synchronized v79 chinese hamster cells, pulse-labeled with 5-bromodeoxyuridine (brdurd), show marked changes in the sensitivity to near-ultraviolet light during the cell cycle. cells are least sensitive during the remainder of the s-phase after the brdurd pulse. they become maximally sensitive in the next cell cycle when the brdurd-labeled dna presumably serves as the template for replication. this is followed by a return to relative insensitivity during the remainder of the s-phase, the increas ...	1979	262378
enhanced proliferation of endogenous virus in chinese hamster cells associated with microtubules and the mitotic apparatus of the host cell.	chinese hamster ovary cells harbour intracytoplasmic virus-like particles of type a which are closely associated with sites of microtubule formation. we report here the enhanced proliferation of these particles and their release at the cell membrane by using either 5-bromodeoxyuridine or dibutyryl cyclic amp. the extracellular mature particles are similar in morphology to retroviruses of type b. close association of the type a virus precursors with microtubule organizing centres, i.e. kinetochor ...	1979	228000
sister chromatid exchange induction resulting from systemic, topical, and systemic-topical presentations of carcinogens.	chinese hamster cheek pouch mucosal cells were examined for in vivo sister chromatid exchange formation resulting from the exposure of animals to carcinogens presented in three manners: systemic, topical, and systemic-topical combination. the systemic presentation of cyclophosphamide (5 or 10 mg/kg) through i.p. injection resulted in an increase in sister chromatid exchanges from 4.8 to 9.9 per cell. topical application of 7,12-dimethylbenz(a)anthracene (0.5% in mineral oil, 0.1 ml) resulted in ...	1979	109193
analysis of polypeptide turnover rates in chinese hamster ovary cell plasma membranes using two-dimensional electrophoresis.		1979	447629
difference between diploid and aneuploid chinese hamster cells in replication at mid-s-phase.	following partial synchronization of the heteroploid chinese hamster cell line v-79 and of normal diploid lung fibroblasts of the chinese hamster in culture, their dna replication during s-phase aws compared by means of a brdu-incorporation/thymidine pulse technique and hoechst-giemsa differential staining of metaphase chromosomes. this comparison indirectly shows the s-phase of the heteroploid cells of v-79 to be 2 h shorter than the diploid cell s-phase. when the thymidine pulse is applied to ...	1979	487906
effects of methotrexate on thymidine triphosphate levels in chinese hamster cell cultures.		1979	454460
isolated metaphase chromosomes. ii. proteins of chinese hamster chromosomes.	the proteins on metaphase chromosomes theoretically may be distributed ubiquitously throughout the karyotype, may be present uniquely on individual chromosomes or classes of chromosomes, or may exist in any combination of the above. separation of chromosomes according to size using sucrose velocity gradients in high capacity zonal centrifuge rotors allows sufficient fractionation of the genome to indicate the distribution of proteins within the karyotype. flow cytometric analysis and direct micr ...	1979	374609
flow-system measurement of cell impedance properties.	a flow-system technique has been developed that detects the high-frequency resistance and capacitance changes in a sensing orifice due to the passage of cells through the orifice. the resistance and capacitance changes are related to cell properties such as size, plasma membrane capacitance, and electrical resistivity of the cell interior. the relationship between measured impedances and cellular properties is discussed, and the prototype instrument for making such measurements is described. the ...	1979	374580
correlation between nuclear morphology and rate of deoxyribonucleic acid synthesis in a normal cell line.	chinese hamster fibroblasts were investigated for the existence of correlations between proliferative activity and nuclear morphology. as a proliferative parameter, the rate of dna synthesis of individual cells was determined by quantitative 14c-autoradiography. in a second step the images of the feulgen-stained nuclei were digitized for extraction of features of morphology and texture. these features were correlated with the corresponding dna synthesis rate values. the following relationships w ...	1979	374574
micromethod for chromosome preparations from chinese hamster lymphocytes.	chromosome preparations from chinese hamster lymphocytes were made by culturing for 2 to 6 days 50,000 to 800,000 lymphocytes in flat-bottomed cooke microtiter plates in 0.1 or 0.2 ml roswell park memorial institute-1640 medium (rpmi-1640) supplemented with 5--40 microliters pha/ml, 20% fetal calf serum (fcs), and 40 microns 2-mercaptoethanol. depending on blood volume and cell concentrations used, it was possible to obtain up to 1400 well-spread metaphases from one venepuncture.	1979	374003
alterations in glycohydrolase activities in streptozotocin-diabetic chinese hamsters (cricetulus griseus).	1. six weeks after the injection of streptozotocin at 125 mg/kg i.p. in the av line nondiabetic chinese hamsters, the animals showed hyperglycemia, increased kidney, pancreas and stomach weights and stomach glucagon contents and depletion of insulin and glucagon in the pancreas. 2. plasma beta-d-galactosidase and n-acetyl-beta-d-glucosaminidase were elevated; whereas alpha-d-glucosidase was decreased and alpha-d-galactosidase remained unchanged in the plasma. 3. in the kidney, streptozotocin-dia ...	1979	318416
emetine resistance in chinese hamster cells is linked genetically with an altered 40s ribosomal subunit protein, s20.	emr-2 is an emetine-resistant (emr) chinese hamster ovary cell mutant that contains a single electrophoretically altered ribosomal protein, a component of its 40s ribosomal subunit [boersma, d., mcgill, s., mollenkamp, j. & roufa, d.j. (1979) j. biol. chem. 254, in press]. this report describes a genetic experiment designed to test linkage between the genes that specify the altered ribosomal protein, s20*, and emetine resistance in emr clones that segregated from cultures of emr-2 cells hybridiz ...	1979	284357
transfer rna isoacceptors in cultured chinese hamster ovary cells.		1979	255210
acid glycohydrolase in chinese hamster (cricetulus griseus) with spontaneous diabetes--v. subcellular distribution in the kidney.	1. seven renal glycohydrolases were measured in four subcellular fractions prepared from highly inbred aglycosuric (av-line) and glycosuric (xa-line) chinese hamsters. 2. alpha-d-galactosidase and beta-d-galactosidase were highest in the nuclear (n) and supernatant (s) fractions; both fractions showed reduced activities in the xa animals. 3. alpha-d-mannosidase was chiefly a particulate enzyme and its decrease in xa animals was evident in n, lysosomal-mitochondrial (lm) and mitochondrial-microso ...	1979	233812
endogenous cyclic amp does not modulate transport of hexoses, nucleosides, or nucleobases in chinese hamster ovary cells.	in a previous study we have demonstrated that neither extracellular nor intracellular cyclic adenosine monophosphate (amp) levels directly affect the uptake of nucleosides, nucleobases, or hexoses by various types of cultured mammalian cells. uptake of these nutrients into cells, however, involves two processes operating in tandem: facilitated transport across the membrane and intracellular phosphorylation; and uptake rates generally reflect the rates of substrate phosphorylation rather than of ...	1979	230391
relative mutagenicity of nucleoside virostatic drugs in chinese hamster ovary cells.		1979	118651
[thiophosphamide induction of sister chromatid exchanges at various phases in the cell cycle of a chinese hamster cell culture].	influence of three concentrations of thiophosphamide (thiotepa) on the formation of sister chromatid exchanges (sce) has been studied at different phases during 2 cell cycles in cultured chinese hamster cells. it is shown that the frequency of sce does not differ from the control level under the effect of the mutagen on cells in the g2 phase of the first cell cycle from the moment of harvesting. thiophosphamide induces the same number of sce at s, g1 stages of the first cell cycle and g2 of the ...	1979	115751
in vivo method for sister chromatid exchanges in chinese hamster foetal and bone marrow cells.		1979	91592
naphthol as-bi (7-bromo-3-hydroxy-2-naphtho-o-anisidine) phosphatase and naphthol as-bi beta-d-glucuronidase in chinese hamster ovary cells: biochemical and flow cytometric studies.	conditions for the biochemical and flow cytometric assay of 7-bromo-3-hydroxy-2-naphtho-o-anisidine phosphatase and beta-d-glucuronidase activities in chinese hamster ovary cells were studied. in the biochemical assay, the ph optimum for the phosphatase activity was ph 4.6 with a km of 10(-5) m; the ph optimum for beta-d-glucuronidase activity was ph 5.0 with a km of 2 x 10(-5) m. for intact cells the derived constants were 3 to 10 times higher. the rate of hydrolysis of both substrates was also ...	1979	35565
organ-specific mutations in chinese hamsters induced by chemical carcinogens.		1979	293496
possible mutagenic activity of saccharin.	a mutagenic effect of saccharin in chinese hamsters, using the in vivo sce test, was observed when massive overdoses were administered; cyclamate was not mutagenic.	1979	499424
proliferation of lung and airway cells induced by nitrogen dioxide.	proliferation of lung cells of chinese hamsters was examined in several regions of the lung parenchyma and ciliated airway epithelium after a 24-h exposure to 28.2 mg/m3 (15 ppm) nitrogen dioxide (no2). label was retained 3 wk after the injection of [3h]thymidine, and autoradiographic methods were used to localize the site of retention. by 24 h after administration of [3h]thymidine, parenchymal areas, exclusive of airways, showed an increased labeling index, indicative of cell death and replacem ...	1979	513156
effect of continuous low-dose insulin treatment on subsequent incidence of diabetes in genetically prediabetic chinese hamsters.	in an attempt to prevent the onset of diabetes, young, genetically prediabetic (but not yet hyperglycemic) chinese hamsters were treated continuously with insulin via minipump for 4 wk beginning 1 wk before the predicted age of onset of glucosuria (age 7 wk). continuous insulin infusion which increased the plasma insulin levels by 70%, did not cause hypoglycemia, nor did it reduce the incidence or severity of diabetic symptoms over the ensuing year of observation. in fact, early treatment with e ...	1979	446913
endocrine factors contributing to the ethanol preferences of rodents.	groups of c57 bl/6j mice (alcohol preferring) and dba/2j mice (alcohol avoiding) were fasted for 24 hours and administered glucose. at 30, 120 and 300 minutes after glucose, the c57 bl/6j mice had significantly higher levels of plasma glucose than the dba/2j strain. these differences were observed in comparable groups given either forced access or no access to alcohol. in ad lib fed animals never exposed to alcohol, c57 bl/6j mice had higher levels of plasma insulin than dba/2j mice. plasma leve ...	1979	572551
the effect of lucanthone on the radiation response of intestinal stem cells in chinese hamsters.	crypt microcolony assay was used to determine the effect of lucanthone on the radiation response of intestinal stem cells in chinese hamsters . the dq of the crypt microcolony radiation--survival curve was maximally reduced by 205 rads when lucanthone injection preceded irradiation by 10 hours and was reduced by 140 rads when injection followed irradiation by 5 hours. on simultaneous injection and irradiation, dq was reduced by only 20 rads; when injection and irradiation were separated by appro ...	1979	760168
absence of povidone-iodine-induced mutagenicity in mice and hamsters.	povidone-iodine usp was tested for mutagenicity in mice by the dominant lethal assay or micronucleus test and in chinese hamsters by the bone marrow test. none of the three tests revealed any evidence of mutagenic effect.	1979	758440
[an assessement of the in vivo sister chromatid exchange (sce)-test using various cytostatics (author's transl)].	five cytostatics of different chemical structure and pharmacological action were used on chinese hamsters (bone marrow cells) to test the efficiency and validity of the in vivo sister chromatid exchange (sce)-test as an indicator of mutagenicity. these model substances, all of which had previously shown a mutagenic effect in one or the other of the various in vivo test systems, gave positive results in this test, too, with the exception of bleomycin. on the basis of the lowest effective dose and ...	1979	546426
mutagenicity of polycyclic hydrocarbons iii. monitoring genetic hazards of benz(a)anthracene.	mutagenicity tests (micronucleus test and chromosome aberrations) have been performed with benz (a) anthracene in spermatogonia and bond marrow cells of chinese hamsters and in nmri mice oocytes. mutagenic effects of the polycyclic hydrocarbon could be demonstrated.	1979	532719
the influence of ethanol treatment of cytogenetic effects in bone marrow cells of chinese hamsters by cyclophosphamide, aflatoxin b1 and patulin.	chromosomes were investigated from the bone marrow of chinese hamsters which received 10% (v/v) ethanol as the only liquid supply for a period of 9 weeks. at the end of the ethanol drinking period 1 group of animals received 2 oral doses of 80 mg/kg cyclophosphamide (cp), a second group received 2 oral doses of 25 mg/kg aflatoxin b1 (afb1), a third group 2 oral doses of 20 mg/kg patulin (pa). the 2 applications were separated by 24 h. the intake of ethanol had no effect on the bone marrow chromo ...	1979	473226
effect of diet limitation on development of diabetes in non-hyperphagic prediabetic chinese hamsters.		1979	386727
organotropic mutagenesis in tissues of chinese hamsters induced by chemical carcinogens.	in order to investigate the relationship between mutation and carcinogenesis in vivo, a method has been developed in which somatic mutation can be studied in specific organs of chinese hamsters after acute dosing with chemical carcinogens. in preliminary experiments an increase in mutation was detected in cultures derived from lung tissue of hamsters after intraperitoneal dosing with the direct-acting mutagen and weak carcinogen, ethyl methanesulphonate, or with diethylnitrosamine, a carcinogen ...	1979	223525
binding site on macrophages that mediates uptake and degradation of acetylated low density lipoprotein, producing massive cholesterol deposition.	resident mouse peritoneal macrophages were shown to take up and degrade acetylated (125)i-labeled low density lipoprotein ((125)i-acetyl-ldl) in vitro at rates that were 20-fold greater than those for the uptake and degradation of (125)i-ldl. the uptake of (125)i-acetyl-ldl and its subsequent degradation in lysosomes were attributable to a high-affinity, trypsin-sensitive, surface binding site that recognized acetyl-ldl but not native ldl. when (125)i-acetyl-ldl was bound to this site at 4 degre ...	1979	218198
regional localization of the gene for human phosphoribosylpyrophosphate synthetase on the x chromosome.	sixty-eight independent hybrid clones were isolated after irradiated normal human lymphocytes were fused with chinese hamster fibroblasts lacking hypoxanthine-guanine phosphoribosyltransferase activity. the cells were grown under selective conditions requiring retention of the x chromosome-linked locus for human hypoxanthine-guanine phosphoribosyltransferase. the frequency and patterns of cotransference of human phosphoribosylpyrophosphate synthetase with the selected marker and with additional ...	1979	218284
biosynthesis of lipid-linked oligosaccharides. isolation and structure of a second lipid-linked oligosaccharide in chinese hamster ovary cells.	previous work has shown that vesicular stomatitis virus-infected chinese hamster ovary cells contain a major high molecular weight lipid-linked oligosaccharide which is transferred en bloc to protein during the formation of the asparagine-linked complex-type oligosaccharides of the vesicular stomatitis virus g protein (tabas, i., schlesinger, s., and kornfeld, s. (1978) j. biol. chem. 253, 716-722). we now report the characterization of a second, lower molecular weight lipid-linked oligosacchari ...	1979	218953
genes controlling receptors for ecotropic and xenotropic type c virus in mus cervicolor and mus musculus.	gene loci controlling cell surface receptors for murine leukemia virus were studied by using murine x chinese hamster hybrid cells. hybrids which exclusively segregate murine chromosomes were made by fusing mus cervicolor and mus musculus lymphocytes to hamster fibroblasts. sensitivity to moloney murine leukemia virus infecotion and specific binding of the envelope glycoprotein of rauscher murine leukemia virus (gp70) cosegregate and isozyme analysis show an association with chromosome 5 in both ...	1979	219245
phosphorylation of t-antigen and control t-antigen expression in cells transformed by wild-type and tsa mutants of simian virus 40.	chinese hamster lung (chl) cells transformed by wild-type simian virus 40 (cell line chlwt15) or transformed by the simian virus 40 mutants tsa30 (cell lines chla30l1 and chla30l2) or tsa239 (cell line chla239l1) were used to determine the rates of turnover and synthesis of the t-antigen protein and the rate of turnover of the phosphate group(s) attached to the t-antigen at both the permissive and restrictive temperatures. the phosphate group turned over several times within the lifetime of the ...	1979	219256
regional asssignments of the loci ak3, acons, and ass on human chromosome 9.	experiments are described in which human cells carrying balanced reciprocal translocations involving four different regions of chromosome 9 were fused with a chinese hamster cell line and the resulting hybrids used to obtain subchromosomal assignments of the loci ass, ak3, and acons. ass was localized on the distal portion of the long arm of chromosome 9, in the region 9q34 leads to 9qter, and ak3 and acons on the short arm, in the region 9pter leads to 9p13.	1979	219990
coordinate overproduction of orotate phosphoribosyltransferase and orotidine-5'-phosphate decarboxylase in hamster cells resistant to pyrazofurin and 6-azauridine.	cells resistant to pyrazofurin and 6-azauridine have been selected from a simian virus 40-transformed syrian hamster line and from a chinese hamster lung line. by increasing the concentrations of inhibitors in several steps, mutant cells from both lines have been obtained which resist high concentrations (1 to 5 mm) of the two inhibitors separately or together. orotidine-5'-phosphate decarboxylase (ec 4.1.1.23), the sixth and last enzyme in ump biosynthesis, is inhibited by the nucleoside monoph ...	1979	220255
karyology and tumorigenicity of a simian virus 40-transformed chinese hamster cell clone.	a pseudodiploid clone of chinese hamster cells tranformed in vitro with simian virus 40 (sv40) was isolated from soft agar and injected into nude mice through three successive passages with a short in vitro cultivation between each animal inoculation. the original clone and the three subsequent tumor populations were characterized in regard to sv40 t antigen staining, modal chromosome number, and giemsa-banded karyotype. all tumor cell lines maintained the pseudodiploid mode, as well as the posi ...	1979	220269
gonadotropin stimulation of cyclic amp levels in chinese hamster ovary cells in culture.	when chinese hamster ovary (cho) cells, incubated in serum-free medium, are exposed to gonadotropins a transient increase in the intracellular concentration of cyclic amp is observed. maximum accumulation of cyclic amp is noted 30 minutes after addition of either human chorionic gonadotropin (hcg) or follicle stimulating hormone (fsh). within one to two hours after hormone addition, the intracellular concentrations of cyclic amp have returned to basal levels. the enhancement of intracellular cyc ...	1979	222777
the roles of the simian virus 40 tumor antigens in transformation of chinese hamster lung cells.	simian virus 40 mutants and deletions between 0.54 and 0.59 map units direct the synthesis of defective 20k t antigens (crawford et al., 1978). these deletion mutants transformed actively growing chl cells nearly as efficently as did wild-type virus, in either the focus formation assay or the growth in soft agar assay. in contrast, when chl cells were in a resting state during infection, the transformation frequency of the mutants relative to wild-type dropped approximately 50 fold. the presence ...	1979	225037
extension of branching processes from hybrids of brain and chinese hamster ovary cells.		1979	225185
loss of epidermal growth factor requirement and malignant transformation.	serum provides growth factors that regulate and limit the growth of normal cells in tissue culture. animal cells that are malignantly transformed usually exhibit diminished serum requirements for growth in culture. we have used a defined, serum-free medium to determine which of these growth factors becomes dispensable for the growth of transformed syrian and chinese hamster fibroblast cells. the medium's four growth factors-epidermal growth factor (egf), insulin, fibroblast growth factor, and tr ...	1979	226990
escherichia coli heat-labile enterotoxin: dna-directed in vitro synthesis and structure.	escherichia coli heat-labile enterotoxin was synthesized in a cell-free system directed by dna of the plasmid p307. synthesis of the toxin, assayed by the elongation induced in chinese hamster ovary cells, was strongly stimulated by cyclic amp and occurred at physiological levels of mg2+ only when the polyamine spermidine was present. activity was abolished by heat and antisera prepared against the enterotoxins of both e. coli p263 and vibrio cholera. tritium-labeled enterotoxin was purified by ...	1979	228267
roles of the simian virus 40 tumor antigens in transformation of chinese hamster lung cells: studies with simian virus 40 double mutants.	simian virus 40 mutants containing both a tsa mutation (rendering the 90,000 molecular weight [90k] t-antigen thermolabile) and a deletion between 0.54 and 0.59 map units (reducing the size and the amount of the 20k t-antigen) were used to transform chinese hamster lung cells. the frequencies of transformation by the double mutants were comparable to that of the tsa mutant alone by both the focus and agar assays except when the cells were serum depleted before infection. growth-arrested cells we ...	1979	229242
enhancement of oxygen toxicity by diethyldithiocarbamate on chinese hamster and mouse cells.		1979	231599
expression of galactose-1-p-uridyltransferase in chinese hamster x human galactosemia somatic cell hybrids.	lymphocytes from a patient with classic galactosemia (galt deficiency) were hybridized with a chinese hamster cell line. electrophoretic valuation of galt in 31 independently derived interspecific hybrid clones failed to demonstrate expression of the human galt gene even when human chromosome 9 was present. possible mechanisms for this lack of expression are presented.	1979	231967
quantitative electron microscopy of intracytoplasmic type a particles at kinetochores of metaphase chromosomes isolated from chinese hamster and murine cell lines.	we have successfully isolated and spread individual chromosomes of cho-ki cells for electron microscopic karyotyping. controlled preparation permitted a quantitative evaluation of the association between endogenous intracytoplasmic type a virus precursor particles and the centromeric region (kinetochores) of isolated chromosomes at prophase and metaphase. our results suggest the transfer of type a particles from the cytoplasmic to the centromeric regions during early metaphase in conjunction wit ...	1979	232135
expression of simian virus 40 gene a affects tubulin stability.	the stability of tubulins present in crude extracts of untransformed balb/c-3t3 mouse fibroblasts, chinese hamster lung cells, and various of their simian virus 40 transformants was assessed by measurement of their individual colchicine-binding decay rates. in all cases studied the decays followed the kinetics of first-order reactions, and rates were reduced at low temperatures and by vinblastine sulfate. under all assay conditions, including different temperatures and protein concentrations, t ...	1979	232186
in vitro transformation of primary chinese hamster cells by minichromosomes from simian virus 40.	purified sv 40 dna and sv 40 minichromosomes, either isolated from sv 40 infected cells (nami) or reconstituted from viral dna and the h1 depleted calf thymus histone fraction (remi), were tested for their ability to transform primary chinese hamster lung (chl) cells. using the agar suspension technique as the transformation assay, an approximately 200 fold increase in transformation activity for nami in comparison with the sv 40 dna and an approximately 50 fold increased activity in comparison ...	1979	232409
increased mutation rates in doubly viral transformed chinese hamster cells.	an untransformed parental chinese hamster cell line, one polyoma transformed clone, and two clones containing both sv40 and polyoma dna were tested for the appearance of variants resistant to 6-thioguanine or oubain. the frequency of such variants was found to be highest in doubly transformed cells. the mutation rate at these loci was correlated with the level of transformation. the mutants observed were stable and had low reversion frequencies with no gross cytogenetic changes. these results es ...	1979	232576
measurement of mutagenesis in mammalian cells.	a method using mammalian cells in vitro for detection and quantitation of mutagenic actions that appears to be useful for screening for carcinogenesis and genetic damage by environmental agents is presented. the method involves use of stable human--chinese hamster ovary hybrid cells that have retained a single human chromosome not necessary for cell reproduction. forward mutations are detected in genes necessary for production of specific human cell surface antigens. such mutants form colonies i ...	1979	286318
dna-mediated transfer of the adenine phosphoribosyltransferase locus into mammalian cells.	in this report, we demonstrate the feasibility of transforming mouse cells deficient in adenine phosphoribosyltransferase (aprt; amp:pyrophosphate phosphoribosyltransferase, ec 2.4.2.7) to the aprt+ phenotype by means of dna-mediated gene transfer. transformation was effected by using unfractionated high molecular weight genomic dna from chinese hamster, human, and mouse cells and restriction endonuclease-digested dna from rabbit liver. the transformation frequency observed was between 1 and 10 ...	1979	286319
isolation of lysosomal alpha-mannosidase mutants of chinese hamster ovary cells.	a method is presented for detection of lysosomal hydrolase activity in situ in colonies of chinese hamster ovary cells. this method was used to screen for mutants deficient in lysosomal alpha-mannosidase. mutagenized cells were replicated onto filter papers [esko, j. d. & raetz, c. r. h. (1978) proc. natl. acad. sci. usa 75, 1190-1193] and allowed to divide for 11-14 days; cells on the filter replicas were lysed, and the filters were incubated with 4-methylumbelliferyl-alpha-d-mannopyranoside at ...	1979	287030
germ line integration of moloney leukemia virus: identification of the chromosomal integration site.	the chromosomal integration site of the structural gene of moloney murine leukemia virus (m-mulv) in the genome of balb/mo mice was mapped genetically. these mice transmit the exogenous m-mulv as an endogenous virus at a single mendelian locus. two independent experimental approaches were used: (i) non-virus-producing fibroblasts prepared from homozygous balb/mo embryos were fused to chinese hamster wg3-h-o cells. in an analysis of 30 independent mouse-chinese hamster cell hybrid clones, the seg ...	1979	287034
assignment of the gene for cytoplasmic superoxide dismutase (sod-1) to a region of chromosome 16 and of hprt to a region of the x chromosome in the mouse.	in the search for homologous chromosome regions in man and mouse, the locus for cytoplasmic superoxide dismutase (sod-1; superoxide:superoxide oxidoreductase, ec 1.15.1.1) is of particular interest. in man, the sod-1 gene occupies the same subregion of chromosome 21 that causes down syndrome when present in triplicate. although not obviously implicated in the pathogenesis, sod-1 is considered to be a biochemical marker for this aneuploid condition. using a set of 29 mouse-chinese hamster somatic ...	1979	291939
regional localization of human gene loci on chromosome 9: studies of somatic cell hybrids containing human translocations.	somatic cell hybrids were derived from the fusion of (1) chinese hamster cells deficient in hypoxanthine guanine phosphoribosyltransferase (hprt) and human cells carrying an x/9 translocation and (2) chinese hamster cells deficient in thymidine kinase (tk) and human cells carrying a 17/9 translocation. several independent primary hybrid clones from these two series of cell hybrids were analyzed cytogenitically for human chromosome content and electrophoretically for the expression of human marke ...	1979	292306
resistance against cycloheximide in cell lines from chinese hamster and human cells is conferred by the large subunit of cytoplasmic ribosomes.	cell lines from chinese hamster ovary [cho-k1-d3] and human fibroblast cells [46, xx, 18p-] were mutagenized with n-nitrosomethylurea followed by a selection for cycloheximide resistance. two mutants resistant against the drug were selected from either wildtype. 80s ribosomes and their ribosomal subunits were isolated from all mutant and wildtype cells. 80s ribosomes reassociated from the isolated subunits were as active as isolated 80s couples in the poly (u) dependent poly (phe) synthesis. hyb ...	1979	292826
hybrid mammalian cells assemble hybrid ribosomes.	hybrid cell lines formed by fusion of mouse 3t3 cells and chinese hamster ovary (cho) cells resistant to emetine, which have an altered 40s ribosomal protein, are generally sensitive to emetine. from most hybrid lines it was possible to select sublines resistant to emetine. the ribosomal components of three lines were studied: a34, an emetine-sensitive hybrid; a34/r3, an emetine-resistant derivative of a34; and a72, an emetine-sensitive hybrid that did not give rise to emetine-resistant sublines ...	1979	293661
amplified dihydrofolate reductase genes in unstably methotrexate-resistant cells are associated with double minute chromosomes.	selection of mammalian cells in progressively increasing concentrations of methotrexate results in selective amplification of dna sequences coding for dihydrofolate reductase (tetrahydrofolate dehydrogenase, 5,6,7,8-tetrahydrofolate:nadp+ oxidoreductase, ec 1.5.1.3). in some cell variants the amplified genes are stable with growth in the absence of methotrexate, whereas in other variants the amplified genes are lost from the population. we have previously reported that in a stably amplified vari ...	1979	293670
genetic and biochemical analysis of the a1 cell-surface antigen associated with human chromosome 11.	a highly versatile system for genetic, biochemical, and immunological analysis of human cell surface components has been developed using a human-chinese hamster somatic cell hybrid containing chromosome 11 as its only human chromosome. this system lends itself to studies such as identification of human cell surface antigens and other genetic markers, regional gene mapping of these markers on chromosome 11, mutational analysis of these markers, and exploration of distribution of these antigens in ...	1979	293736
influence of crystallization habit of minerals on in vitro cytotoxicity.	four samples of cummingtonite-grunerite series in various crystallization habits were tested in vitro. the cytotoxicity to chinese hamster ovary cells and hemolysis to sheep erythrocytes were inversely proportional to the structural faults and surface defects of the minerals. at a comparable surface area, asbestiform grunerite (uicc amosite), semi-asbestiform cummingtonite, acicular cummingtonite, and acicular grunerite were found to be cytotoxic and hemolytic in a decreasing order. the influenc ...	1979	294214
lipid-saccharide intermediates and glycoprotein biosynthesis in a temperature-sensitive chinese hamster cell mutant.	the characterization of a temperature-sensitive chinese hamster cell mutant has been continued with the aim of localizing the apparent defect in glycoprotein synthesis (tenner et al., '77). although the mutation is lethal, a demonstration of the ability of the mutant cells to support proliferation of mengo virus at the nonpermissive temperature indicates that the general metabolic processes of the cells remain intact at a time when glycoprotein synthesis is severely depressed. a quantitative stu ...	1979	217883
effectiveness of 0.3 kev carbon ultrasoft x-rays for the inactivation and mutation of cultured mammalian cells.	carbon k characteristic ultrasoft x-rays of energy 0.278 kev were found to be effective in inducing inactivation and mutation to thioguanine resistance in cultured v79 chinese hamster cells and human diploid fibroblasts. these x-rays act as a probe of the sensitive sites within the cells since they produce low-energy photoelectron tracks of range about 7 nm; this is an order of magnitude smaller than those produced by the 1.5 kev aluminium x-rays used in previous studies. a detailed interpretati ...	1979	315385
mutation and inactivation of cultured mammalian cells exposed to beams of accelerated heavy ions. i. irradiation facilities and methods.	this paper, which is the first of four covering the inactivation of clonogenic capacity and induction of mutation in cultured mammalian cells, deals briefly with the general aims of the work and describes the irradiation techniques used. human diploid fibroblasts and v79 chinese hamster cells were irradiated as monolayers with ions of helium, boron or nitrogen at let's in the range 20 to 479 kev micrometer-1 in h2o. the physical aspects of the irradiation including measurement of ion energies, d ...	1979	315387