| use of limited protocols to evaluate the genotoxicity of hazardous wastes in mammalian cell assays: comparison to salmonella. | dichloromethane extracts of four diverse hazardous wastes (coke plant, herbicide manufacturing, pulp and paper, and oil refining) were evaluated for mutagenicity in strains ta98 and ta100 of salmonella. these extracts also were tested for biological activity in short-term mammalian cell assays, including mutagenicity in l5178y/tk +/- mouse lymphoma cells, chromosomal aberrations and sister chromatid exchanges in chinese hamster ovary (cho) cells, morphological transformation in balb/c-3t3 cells, ... | 1987 | 3669103 |
| effects of sodium fluoride on uptake of t-2 mycotoxin in cultured cells. | we examined the effect of sodium fluoride on uptake of tritium-labeled t-2 toxin (molecules of toxin/cell) in chinese hamster ovary (cho) and african green monkey kidney (vero) cells. correlations were made to temperature (22 and 37 degrees c) and toxin concentration (0.001 and 0.01 microgram/ml) over time (0-180 min). as expected, toxin uptake increased in both cell types with increasing time and temperature. vero cells exhibited significant (p less than 0.05) increases in the rate (i.e. slope) ... | 1987 | 3672540 |
| priming of influenza mrna transcription is inhibited in cho cells treated with the methylation inhibitor, neplanocin a. | chinese hamster ovary cells were pretreated with neplanocin a, a potent inhibitor of rna methylation. analysis of polyadenylated rna from treated cells by high-pressure liquid chromatography revealed marked decreases of 2'-o-methylation within mrna cap structures and of internal n6-methyladenosine residues. in these neplanocin a-treated cells, influenza viral mrna accumulation was virtually abolished. cellular rna from neplanocin a-treated cells was substantially less efficient than rna from con ... | 1987 | 3674853 |
| expression and characterization of hydroxyindole o-methyltransferase from a cloned cdna in chinese hamster ovary cells. | we have used two kinds of expression systems to test whether the cloned cdna encoding hydroxyindole o-methyltransferase (hiomt) of the bovine pineal gland was functional or not. first, when mrna was synthesized in vitro by the sp6 system and injected into xenopus oocytes, the enzymatic activity was expressed in the oocytes. second, the cloned cdna was recombined to a vector under the control of the simian virus 40 early promoter and transfected to chinese hamster ovary (cho) cells. the enzymatic ... | 1987 | 3676708 |
| correction of alkylation hypersensitivity of cho-w27-1 cells by transfection with human dna. | chinese hamster cells of the mutant strain w27-1 which is hypersensitive to uv and monofunctional alkylating agents were transfected with human dna ligated to the bacterial xanthine-guanine phosphoribosyltransferase (gpt) gene. selection was performed for resistance to mycophenolic acid and finally for survival after treatment with high doses of methyl methanesulfonate. a gpt+ transfectant was generated (t38-2-7) which acquired resistance to methyl methanesulfonate and cross-resistance to n-meth ... | 1987 | 3677316 |
| novel cytogenetic expression of gene amplification in actinomycin d-resistant somatic cell hybrids: transfer of resistance by centric chromatin bodies. | sewatc13 mouse cells, resistant to 0.1 microgram/ml of actinomycin d (amd), were fused to amd-sensitive cells of the chinese hamster ovary cell line (cho). twenty-two hybrid clones were isolated and put into serial culture in the selective medium. unexpectedly, identifiable mouse chromosomes were found only in one of the hybrids. all the others had only hamster chromosomes and, in addition, numerous chromatin bodies (cbs), mostly small and irregularly shaped, but also larger, more chromosome-lik ... | 1987 | 3677923 |
| transfer of purine metabolites between cells through the medium and via cell contacts in cocultures of hgprt+ and hgprt- cells. | cells with and without hypoxanthine-guanine phosphoribosyltransferase (hgprt) activity were used to examine the transfer of purine metabolites through the medium and via cell contacts. hgprt- chinese hamster and human fibroblasts were able to incorporate 3h-labeled purine metabolite(s) from medium in which mouse hgprt+ b82 cells had been grown for 24 h with [3h]hypoxanthine, but mouse a9 fibroblasts that were deficient in hgprt, adenine phosphoribosyltransferase (aprt), and methylthioadenosine p ... | 1987 | 3678380 |
| some aspects of cytochrome p450-dependent denitrosation of n-nitrosamines. | the present paper deals with three aspects of cytochrome p450-dependent denitrosation of n-nitrosamines. (1) nitrate was found in addition to nitrite as a metabolic product of the denitrosation reaction when n-nitrosamines were incubated with a microsomal system. this could also be shown when nitric oxide was added to the microsomes. (2) in order to determine the amount of denitrosation in vivo, the nitroso group of n-nitroso-n-methylaniline was labelled with the 15n isotope and administered to ... | 1987 | 3679347 |
| effect of dietary selenium on biotransformation and excretion of mutagenic metabolites of n-nitrosodimethylamine and 1,1-dimethylhydrazine in the liver perfusion/cell culture system. | the mutagenicity of n-nitrosodimethylamine (ndma) and 1,1-dimethylhydrazine (udmh) has been studied in an isolated liver perfusion/cell culture system. the liver donors, male wistar rats, were either selenium (se)-deficient or had a physiologically adequate se status (se-supplemented). mutagenicity was measured in perfusate and bile with chinese hamster v79 cells as the genetic target. se deficiency increased the mutagenic effect of ndma in the perfusate, whereas no mutagenicity was detected in ... | 1987 | 3679364 |
| recently identified nitrite-reactive compounds in food: occurrence and biological properties of the nitrosated products. | various japanese foodstuffs are directly-acting mutagens in salmonella typhimurium ta100 after nitrite treatment. such mutagen precursors include tyramine and beta-carboline derivatives, isolated from soya sauce, and indole-3-acetonitrile, 4-methoxyindole-3-acetonitrile and 4-methoxyindole-3-aldehyde, isolated from fresh chinese cabbage. a mutagen produced from tyramine with nitrite was found to be 4-(2-aminoethyl)-6-diazo-2,4-cyclohexadienone (3-diazotyramine), and one produced from indole-3-ac ... | 1987 | 3679387 |
| mutagenicity and carcinogenicity of masheri, a pyrolysed tobacco product, and its content of tobacco-specific nitrosamines. | masheri, an indigenous pyrolysed tobacco product in india, was studied for its chemical, mutagenic and carcinogenic profile. masheri extract was found to be rich in n-nitrosamines and polycyclic aromatic hydrocarbons. it was highly mutagenic in the presence of an exogenous metabolic system in the ames test and in the micronucleus test, in a dose-dependent manner. it also induced 8-azaguanine-resistant mutants in chinese hamster v79 cells. on skin painting, it showed a weak carcinogenic effect in ... | 1987 | 3679422 |
| reevaluation of the evidence that an antibody to the insulin receptor is insulinmimetic without activating the protein tyrosine kinase activity of the receptor. | the immunoglobulin fraction of a polyclonal anti-insulin receptor antibody (b-10) derived from a patient with severe insulin resistance and acanthosis nigricans was tested for its ability to activate the protein kinase activity of the insulin receptor and to mimic insulin action in chinese hamster ovary cells expressing either wild type or kinase-deficient human insulin receptors. this antiserum had previously been reported to be insulinmimetic without activating the insulin receptor protein tyr ... | 1987 | 3680277 |
| structural characterization of natural human urinary and recombinant dna-derived erythropoietin. identification of des-arginine 166 erythropoietin. | recombinant human erythropoietin (rhepo) has been purified to apparent homogeneity from a chinese hamster ovary cell line expressing a cdna clone of the human gene. nh2-terminal sequencing of the recombinant hormone indicates that the 27-residue leader peptide is correctly and consistently cleaved during secretion of the recombinant protein into conditioned medium, yielding the mature nh2 terminus (ala-pro-pro-arg...). analysis of the cooh terminus of rhepo by peptide mapping and fast atom bomba ... | 1987 | 3680293 |
| a cloned human ribosomal protein gene functions in rodent cells. | cloned fragments of human ribosomal protein s14 dna (rps14) were transfected into cultured chinese hamster (cho) cells. transient expression assays indicated that dna with as little as 31 base pairs of upstream flanking sequence was transcribed into a polyadenylated, 650-base mrna that is largely bound to the polyribosomes. in these respects the exogenous human s14 message appeared to function normally in cho cells. interestingly, transcription of human rps14 did not require the tata sequence lo ... | 1987 | 3683397 |
| observations of cell function and morphology in the presence of silicone gel: an in vitro study. | the project described in this article used in vitro tissue culture techniques and flow cytometry to determine if there are alterations in cell morphology in those cells that have been placed in contact with a commercially available medical-grade silicone gel used in mammary implants. we were unable to demonstrate significant changes in cell cycle characteristics following in vitro exposure for 1 to 12 days using human fibroblasts, mouse fibroblasts, and chinese hamster ovary cells. | 1987 | 3688786 |
| expression of the cdna encoding for mouse sperm-specific lactate dehydrogenase c in chinese-hamster ovary cells. | the cloned cdna encoding for mouse sperm-specific lactate dehydrogenase c (ldh-c) was inserted immediately downstream to the mmtv 5' ltr promoter, and it was shown to synthesize mouse ldh-c polypeptide in chinese-hamster ovary cells. the mouse ldh-c subunit and the endogenous chinese-hamster ldh-a subunit formed in vivo a heterotetrameric ldh-a3c1 isoenzyme, and this novel isoenzyme exhibited enzymic activity utilizing lactate as substrate. | 1987 | 3689350 |
| mechanism of uptake of sulfonated metallophthalocyanines by cultured mammalian cells. | the uptake of several metallophthalocyanine tetrasulfonates by cultured chinese hamster cells was studied. uranyl- and chloraluminium were taken up at the highest rate followed by ni-, zn-, cu-, co- and dichlorosilicon-phthalocyanine tetrasulfonate. the uptake from the growth medium containing 10% serum in which only 15% of the dye is not bound to serum proteins was 5--18-fold slower than in the absence of serum, suggesting that most of the uptake is of free dye. using gel filtration to separate ... | 1987 | 3690510 |
| premature chromosome condensation induced by electrofusion. | premature chromosome condensation of g1, g2, and s-phase chromosomes has been achieved by the use of electrofusion in the fusion of chinese hamster ovary (cho) cells and hela cells and cho cells with human leukocytes. very high yields of heterokaryons, of over 80%, as well as elimination of adverse effects of chemical and viral fusion agents, facilitated induction of premature chromosome condensation of high quality. | 1987 | 3691182 |
| [gene amplification in murine leukemia cells with multiple drug resistance acquired in vivo]. | the p388rm and p388rx cell lines resistant to antracycline antibiotics were obtained as a result of chemotherapy of mice bearing p388 leukemia, by means of increasing dosages of rubomycin and ruboxyl, respectively. these cell lines possessed cross-resistance to vinblastine, vincristine, colchicine, actinomycin d and some other drugs. multidrug resistance (mdr) of p388rm and p388rx is due to decreased uptake of different cytotoxic compounds by the cells. development of resistance to rubomycin and ... | 1987 | 3692152 |
| [extracts of regenerating planarians regulate proliferation of vertebrate cells]. | the effects of extracts from intact and regenerating planarians on cell behaviour in culture were studied. the extracts were added to the culture of chinese hamster fibroblasts and to the primary culture of human lymphocytes. some extracts contained active agents which influenced the proliferation of fibroblasts increasing or decreasing the mitotic index. the extracts exerted no effect on the mitotic index of lymphocytes. when the extracts were added to the lymphocyte culture together with phyto ... | 1987 | 3696681 |
| [strengthening of the dna-protein complex during the stationary aging of cultured cells]. | accumulation of dna-protein crosslinks during "stationary phase ageing" (i.e. with the increase of non-proliferating period) of cultured transformed chinese hamster cells and normal embryonic diploid human fibroblasts was determined by the improved method of column chromatography using hydroxylapatite of 14c-valine, 14c-leucine and 3h-thymidine-labelled cell homogenates. such an accumulation, however, was not observed during "stationary phase ageing" of xeroderma pigmentosum human fibroblasts. p ... | 1986 | 3697488 |
| influence of hypoxia and an acidic environment on the metabolism and viability of cultured cells: potential implications for cell death in tumors. | hypoxia and an acidic environment are known to occur in regions of solid tumors and might be involved in the causation of necrosis. the viability and energy metabolism of cells in tissue culture were therefore investigated under hypoxic and/or acidic conditions. acute exposure of chinese hamster ovary (cho) cells or human bladder cancer mgh-u1 cells to hypoxia plus low ph (6.5 to 6.0) was cytotoxic in a time- and ph-dependent manner; surviving fraction was reduced to approximately 10(-4) followi ... | 1986 | 3698008 |
| mutagenicity of the mononitrobenzo[a]pyrenes in chinese hamster ovary cells mediated by rat hepatocytes or liver s9. | previous studies have shown that 1- and 3-nitrobenzo[a]pyrene (nbap) were mutagenic in the salmonella reversion assay without exogenous activation and that 1-, 3- and 6-nbap were mutagenic in the presence of hepatocytes or liver homogenate (s9). in the present study, 1-, 3- and 6-nbap were tested for mutagenicity in chinese hamster ovary (cho) cells under activation conditions similar to those used in the bacterial studies. none of the nbaps was mutagenic without exogenous activation and none wa ... | 1986 | 3698200 |
| aminoacylase-1 isoenzymes: a comparative study. | analysis of aminoacylase-1 (acy-1) zymograms from 21 species indicated one structural locus coding for one dimeric enzyme. among the various strains of five laboratory mammals (mesocricetus auratus, cricetulus griseus, mus musculus, rattus norvegicus, cavia porcellus) only in mus musculus-strains genetic variability was found. crosses segregating for acy-1b/acy-1c reveal a three-banded banding pattern typical for the heterozygous state of a dimeric enzyme. electrophoretic comparisons of all spec ... | 1986 | 3700124 |
| cell cycle regulation of transfected murine dihydrofolate reductase genes. | we have used the technique of dna-mediated gene transfer to introduce dihydrofolate reductase genes into dihydrofolate reductase-deficient chinese hamster ovary cells. the transferred sequences include: dihydrofolate reductase minigenes, dihydrofolate reductase cdna clones, and genomic dna from mouse cells with highly amplified dihydrofolate reductase genes. the hamster cells were capable of utilizing the murine transcription initiation sites, splice junctions, and polyadenylation sites in compl ... | 1986 | 3700422 |
| device of anoxic chamber system and repair of potentially lethal damage of anoxic cells in vitro. | in order to study radiation responses of anoxic plateau phase cells in vitro, an air-tight anoxic chamber was devised in which chinese hamster v-79 or swiss mouse nih3t3 cells were deoxygenated by replacing the air with saturatedly humidified n2 gas. the cells as adhered on the culture plate, which was contained in the anoxic chamber, were x-irradiated. the deoxygenated condition in the anoxic chamber was maintained as long as necessary. oxygen enhancement ratio obtained by the anoxic chamber wa ... | 1986 | 3705058 |
| the mitogenic activity of a heparin-binding fibronectin fragment (mr 35,000) produced by cathepsin d digestion. | fibronectin was partially digested using the lysosomal proteinase cathepsin d and the fragments produced tested for their effect on the rate of dna synthesis in quiescent chinese hamster fibroblasts (ch23). a mitogenically active digest was produced after digestion of fibronectin with cathepsin d for 2 to 3h at a 1:200 (w/w) ratio of enzyme to substrate at 37 degrees c. affinity chromatography of the active digest on both gelatin and heparin 4bcl columns demonstrated that the active fragment was ... | 1986 | 3707069 |
| cyclic amines are selective cytotoxic agents for pigmented cells. | we have shown that morpholine, a cyclic amine, exerts a selective inhibition of growth on melanocytic pigmented cell lines compared to nonpigmented cells. the id50 of morpholine for the pigmented b-16 cell line hfh was 1200 micrograms/ml, compared to values greater than 2400 micrograms/ml for baby hamster kidney, chinese hamster ovary and np, an unpigmented primate cell line. two other cyclic amines piperazine and piperidine, were similarly found to be selectively toxic to melanocytes. this sele ... | 1986 | 3708699 |
| a comparison of baseline and cyclophosphamide-induced sister chromatid exchanges in bone marrow and spleen cells of mouse and chinese hamster. | baseline sister chromatid exchange (sce) frequencies were investigated in bone marrow and spleen cells of mice and chinese hamsters. no significant difference in sce frequency was noted for bone marrow in both species and for bone marrow and spleen in mice on per cell and per pg dna basis. however, a significant difference was noted between species in spleen and between cell types in chinese hamsters. also, statistically significant differences were noted between species for both cell types when ... | 1986 | 3709427 |
| genetic toxicology of phthalate esters: mutagenic and other genotoxic effects. | the effects of dehp on sperm morphology and on peripheral blood micronuclei were studied for 12 weeks following five subacute ip injections of dehp at 1/6, 1/12, and 1/60 of the ld50 per day. sperm morphology was examined in both adult mice and rats, while peripheral blood micronuclei were scored in mice up to 4 weeks after treatment. in mice, dehp at 1/6 ld50 significantly depressed body weight gain for up to 12 weeks after treatment, and reduced epididymal sperm number by 4 weeks. numbers of m ... | 1986 | 3709450 |
| studies on the genetic effects of phthalic acid esters on cells in culture. | mono(2-ethylhexyl) phthalate (mehp) induced chromosome aberrations in cells of two culture lines, one derived from chinese hamster ovary cells (cho) and the other from rat liver cells (rl4). in cho cells, the clastogenicity of mehp was unaffected by the presence of an exogenous metabolic activation system (s-9 mix). 2-ethylhexanol, o-phthalic acid, and phthalic anhydride were without effect. cytochemical methods and assays for carnitine acetyltransferase and kcn-insensitive palmitoyl coa oxidati ... | 1986 | 3709451 |
| [change in cellular ph in hyperthermia and hypoxia]. | change of ph of cultivated cells (chinese hamster fibroblasts and pig embryonic kidney cells) was studied during their incubation under oxygenation conditions and at different temperatures using microfluorimetry with fluorescein diacetate. it was shown that phc was 7.0 at temperatures 22-37 degrees c. hyperthermia and hypoxia resulted in cell acidity. the effect was enhanced with an increase in the period of exposure to both agents. intracellular ph more acid values were noted in the effect of h ... | 1986 | 3713464 |
| selective gene amplification in mammalian cells after exposure to 60co gamma rays, 241am alpha particles, or uv light. | simian virus 40 wild type (sv40)-transformed chinese hamster embryo cells (co631) contain about five viral copies integrated per cell genome. these sv40 sequences were used as endogenous indicator genes to study the response of mammalian cells to radiation at the gene level. an increase in copy number was detected by dispersed cell blotting and southern analysis in combination with specific dna hybridization. all types of radiation tested induce a 15- to 25-fold amplification of sv40 sequences w ... | 1986 | 3714979 |
| changes in intracellular ph induced by hyperthermia and hypoxia. | the effect of hyperthermia on ph of cells cultivated at varying ph of the medium and under different conditions of oxygenation has been studied. chinese hamster fibroblasts and pig embryo kidney cells were used. the intracellular ph (phi) was determined by the microfluorimetric method using fluorescein diacetate. the required temperature (37 degrees c and 41 degrees c) was maintained by a warm stage in combination with a thermochamber. different conditions of oxygenation were achieved by placing ... | 1986 | 3722907 |
| quantitative analysis of polyenoic phospholipid molecular species by high performance liquid chromatography. | the quantitative analysis of phospholipid molecular species containing polyenoic fatty acids is described. dinitrobenzoyl derivatives of diacylglycerols prepared from phospholipids were separated into individual molecular species by reversed-phase high performance liquid chromatography (hplc) using a combination of two solvent systems and were quantified at 254 nm. thirty-six molecular species were resolved from the phosphatidylcholines of rat hearts, human platelets and chinese hamster v79-r ce ... | 1986 | 3724372 |
| regulation of dihydrofolate reductase in human breast cancer cells and in mutant hamster cells transfected with a human dihydrofolate reductase minigene. | the regulation of dihydrofolate reductase (dhfr) gene expression was studied in gene-amplified, estrogen-responsive human breast cancer cells (mtx mcf-7). previous studies have shown that estrogen increases, whereas tamoxifen decreases the rate of dhfr enzyme synthesis resulting in corresponding changes in the level of this enzyme. dhfr levels also increase following incubation with methotrexate (mtx), an effect which is dependent on both the concentration of extracellular drug and the duration ... | 1986 | 3724746 |
| plasmid carriage in vibrio vulnificus and other lactose-fermenting marine vibrios. | a total of 42 clinical and environmental isolates of vibrio vulnificus were examined for plasmid carriage. of these, only five (12%) harbored plasmids, which were of various molecular weights. in contrast, 20 of 32 (62.5%) unidentified lactose-fermenting vibrio spp. were found to possess plasmids with masses of 2.1 to 150 megadaltons. in these isolates, multiple plasmids were common, with an average of 2.25 plasmids per plasmid-containing strain. attempts to demonstrate a correlation with the pl ... | 1986 | 3729404 |
| comparison of dna lesions and cytotoxicity induced by calcium chromate in human, mouse, and hamster cell lines. | dna lesions, cytotoxicity, and cellular uptake of cacro4 were compared in chinese hamster ovary, in mouse embryo fibroblast c3h10t1/2, and in human osteosarcoma cells. the concentration of cacro4 that reduced colony formation by 50% was 2- or 3-fold less in human osteosarcoma cells than in c3h10t1/2 or chinese hamster ovary cells. alkaline elution studies showed that cacro4 induced dna single strand breaks in a concentration dependent manner in all three cell lines. however, the human cells exhi ... | 1986 | 3731109 |
| comparison of cellular effects of phomopsin and colcemid in chinese hamster cells in vitro. | the effects of the fungal toxin phomopsin a, which produces the disease lupinosis in farm animals fed on lupins infected with phomopsis leptostromiformis, were studied in cultures of chinese hamster cells. the results show that phomopsin a inhibits proliferation by blocking cells in metaphase, but that higher concentrations are needed than for colcemid, another mitotic poison. as with colcemid, there is an increase in both micronuclei formation and dna synthesis. unlike colcemid, phomopsin is al ... | 1986 | 3731879 |
| colonization and infection of athymic and euthymic germfree mice by campylobacter jejuni and campylobacter fetus subsp. fetus. | human clinical strains of campylobacter jejuni and campylobacter fetus subsp. fetus colonized the gastrointestinal tracts of both athymic (nu/nu) and euthymic (+/nu) germfree mice (balb/c). viable campylobacter spp. (10(9) to 10(10) cfu/g [dry weight] of cecum and colon contents) were isolated on day 3 after oral challenge, and similar large numbers of viable cells were evident at several intervals during a 10-month experiment. the stomachs and upper small intestines of nu/nu and +/nu mice that ... | 1986 | 3733222 |
| thrombin-induced vimentin phosphorylation in cultured human umbilical vein endothelial cells. | cultured human umbilical vein endothelial cells were stimulated with thrombin (1 unit/ml) for 15-30 s and then lysed with a solution of triton x-100 containing [gamma-32p]adenosine triphosphate. thrombin-stimulated human umbilical vein endothelial cells showed an enhanced incorporation of 32p into at least 12 different proteins as compared to control cells treated similarly. the observed enhanced phosphorylation required the active site of thrombin because diisopropylphosphoryl-thrombin had no e ... | 1986 | 3733715 |
| assignment of a human dna-repair gene associated with sister-chromatid exchange to chromosome 19. | the chinese hamster ovary (cho) cell mutant, em9, is defective in rejoining strand breaks, hypersensitive to chlorodeoxyuridine (cldurd), and has a high frequency of sister-chromatid exchange (sce). somatic cell hybrids constructed from fusion of em9 cells with normal human lymphocytes and fibroblasts, and selected in cldurd, extensively segregate human chromosomes but preferentially retain markers of human chromosome 19. the sce frequency in the hybrid clones is low as in normal cho cells, but ... | 1986 | 3736579 |
| uptake of irradiated human low density lipoprotein by cultured chinese hamster v79 cells. | specific binding and degradation of native and gamma-rays irradiated (100-2000 rad; 100 rad/min; 137cs) human low density lipoprotein by chinese hamster v79 cells and mouse peritoneal macrophage line, j774g were studied. low density lipoproteins were labeled with 125i for studying the specific binding and subsequent degradation. the specific binding and degradation of irradiated 125i-low density lipoproteins (mixed with irradiated native lipoprotein) by chinese hamster v79 cells are considerably ... | 1986 | 3741441 |
| inhibition of nucleoside and nucleobase transport and nitrobenzylthioinosine binding by dilazep and hexobendine. | the transport of 500 microm uridine by human erythrocytes and s49, p388 and l1210 mouse leukemia cells, chinese hamster ovary (cho) cells and novikoff rat hepatoma cells was inhibited strongly by dilazep and hexobendine with similar concentration dependence, but the sensitivity of transport in the various cell types varied greatly; ic50 values ranged from 5-30 nm for human erythrocytes and s49 and p388 cells to greater than 1 microm for cho and novikoff cells. the binding of nitrobenzylthioinosi ... | 1986 | 3741459 |
| oxygen concentration and the oer for acutely or chronically thiol deficient cells. | glutathione (gsh) is one of several intracellular hydrogen donating species thought to compete with o2, a damaging species, to repair radiation induced free radical damage. the o2 k factor was determined for normal chinese hamster v79 cells, v79 cells made acutely thiol deficient (no detectable gsh or npsh) using the gamma-glutamyl-cysteine synthetase enzyme inhibitor d,l-buthionine-s,r-sulfoximine (d,l-bso), or a human skin fibroblast cell line gm3877 which, because of the nature of its genetic ... | 1986 | 3744929 |
| sr-4233: a new bioreductive agent with high selective toxicity for hypoxic mammalian cells. | we have examined the effects of the benzotriazine di-n-oxide sr-4233 (3-amino-1,2,4-benzotriazine-1,4 dioxide) on a variety of aerobic and hypoxic cells in culture, and on tumors in mice. the cell lines used were chinese hamster ovary (ha-1), mouse 10t1/2, rif-1, and scc vii cells, and the human cell lines hct-8, ag1522, and a549. the effect of sr 4233 in combination with irradiation was also examined in the scc vii tumor growing in the flank of c3h mice using clonogenic assay (tumors excised 24 ... | 1986 | 3744945 |
| in vitro binding of 14c-misonidazole to hepatocytes and hepatoma cells. | the binding rate of 14c-misonidazole was determined for freshly isolated mouse hepatocytes, mouse hepatoma cells, emt-6 tumor cells, and v79 chinese hamster lung fibroblasts. at 10 microm drug concentration, the four different cell lines bound 14c-misonidazole at rates of 12.4, 29.9, 51.6, and 13.5 pmoles/10(6) cells/hr, respectively. this relative order of binding was observed over a drug concentration range of 10-100 microm. these data indicate that in extreme hypoxia, mouse hepatocytes do not ... | 1986 | 3744947 |
| clastogenicity in vitro of the na, k, ca and mg salts of saccharin; and of magnesium chloride; consideration of significance. | the sodium, potassium, calcium and magnesium salts of saccharin, and magnesium chloride, have been shown to be clastogenic to chinese hamster lung (chl) fibroblasts in vitro, but only at elevated dose levels (8-16 mg/ml). saccharin acid was inactive to the limits of its solubility (4 mg/ml). when the data are expressed in terms of ionic concentration, each salt showed a similar clastogenic potency. this suggests that ionic effects induced by these salts in the assay medium may be the critical de ... | 1986 | 3748054 |
| mutation induction and dna adduct formation by 1,8-dinitropyrene in chinese hamster ovary cells. | | 1986 | 3749046 |
| metabolism of t-2 mycotoxin by cultured cells. | t-2 mycotoxin is a small (i.e. mol. wt 466), non-protein toxin. we studied its metabolism in chinese hamster ovary (cho) cells, african green monkey kidney (vero) cells, human fibroblasts and mouse connective tissue cells (l-929). confluent cells were exposed to [3h]-t-2(0.01 micrograms/ml) for 1 hr at 37 degrees c. the toxin was removed, cells rinsed, and unlabeled culture media added for 4 hr (37 degrees c). cell monolayers were extracted and media and cell extracts were spotted on thin-layer ... | 1986 | 3750347 |
| differential expression of alpha-tubulin mrna in rat cerebellum as revealed by in situ hybridization. | nucleotide sequence analysis of two rat alpha-tubulin cdna clones showed a marked divergence in their 3'-untranslated regions. however, each of the alpha-tubulin isotypes shows a high interspecies homology in this region, when compared with an isotubulin sequence from human and chinese hamster. in situ hybridization of rat cerebellum with alpha-tubulin cdna revealed differential expression in various cell layers. the mitotically active cells in the external granular layer show the highest level ... | 1986 | 3753592 |
| sodium arsenite potentiates the clastogenicity and mutagenicity of dna crosslinking agents. | to see if sodium arsenite enhances the clastogenicity and the mutagenicity of dna crosslinking agents, chinese hamster ovary (cho) cells and human skin fibroblasts were exposed to cis-diamminedichloroplatinum (ii) (cis-pt(ii)) or 8-methoxypsoralen (8-mop) plus long-wave ultraviolet light (uva) and then to sodium arsenite. the results indicate that the clastogenicity of cis-pt(ii) and 8-mop plus uva are enhanced by the post-treatment with sodium arsenite. chromatid breaks and exchanges are predom ... | 1986 | 3753679 |
| quantitative and molecular analyses of radiation-induced mutation in as52 cells. | psv2gpt-transformed and wild-type chinese hamster ovary (cho) cell lines have been used to study radiation-induced mutation at the molecular level. the transformant, designated as52, was constructed from a hypoxanthine-guanine phosphoribosyl transferase (hprt)-deficient cho cell line and contains a single, functional copy of the escherichia coli xanthine-guanine phosphoribosyl transferase (xprt) gene (gpt) stably integrated into the chinese hamster genome. as52 and wild-type cho-k1-bh4 cells exh ... | 1986 | 3753799 |
| sequence and expression of human estrogen receptor complementary dna. | the mechanism by which the estrogen receptor and other steroid hormone receptors regulate gene expression in eukaryotic cells is not well understood. in this study, a complementary dna clone containing the entire translated portion of the messenger rna for the estrogen receptor from mcf-7 human breast cancer cells was sequenced and then expressed in chinese hamster ovary (cho-k1) cells to give a functional protein. an open reading frame of 1785 nucleotides in the complementary dna corresponded t ... | 1986 | 3753802 |
| radiosensitization, pharmacokinetics, and toxicity of a 2-nitroimidazole nucleoside (ra-263). | a 2-nitroimidazole nucleoside, 1-(2',3'-dideoxy-alpha-d-erythro-hex-2'-enopyranosyl)-2-nitroimida zole (ra-263), has been investigated for its radiosensitization, pharmacokinetics, and toxicity properties. the in vitro radiosensitization tests against hypoxic chinese hamster (v-79) cells demonstrated that ra-263 was a more potent radiosensitizer than misonidazole and at 2 mm concentration approached the oxic curve. significant in vitro radiosensitization activity was also observed in emt6 mammar ... | 1986 | 3754053 |
| biological and biochemical activities of the novel antitumor antibiotic pd 114,759 and related derivatives. | a complex of novel and exceptionally potent antibiotics has been evaluated for antitumor activity in vitro and in vivo and characterized with regard to their ability to cause dna strand scission. the major component, pd 114,759, was quite active against all in vitro tumor systems including the human tumors, mcf-7 breast, hct-8 colon, and a549 lung and the murine tumors m16/c mammary, lewis lung, pan 02 pancreas and l1210 leukemia. id50 values ranged from 2-57 pg/ml. in vivo this agent produced s ... | 1986 | 3754542 |
| [chinese hamster ovary (cho) and y1 cell tests in the routine detection of heat-labile endotoxin of escherichia coli]. | | 1986 | 3755268 |
| cryo-electron microscopy of vitrified chromosomes in situ. | chromosomes of metaphase-arrested chinese hamster ovary (cho) and hela cells were examined in situ, unfixed and unstained, by cryo-electron microscopy. in hydrated, vitrified cryo-sections, chromosomes exhibit a characteristic homogeneous, grainy texture, which, on optical diffraction, gives rise to a broad reflection corresponding to 11 nm. no superstructure or periodic order is discernible. these observations suggest that the chromosome is formed by the compact association of 11 nm filaments, ... | 1986 | 3755397 |
| toxicity and dna damage induced by 1-nitropyrene and its derivatives in chinese hamster lung fibroblasts. | 1-nitropyrene and its chemically synthesised derivatives were investigated for their cytotoxicity and ability to induce dna-strand breaks in chinese hamster lung fibroblasts. both 1-nitrosopyrene (0.25-60 micrograms/ml) and 1-aminopyrene (0.25-25 micrograms/ml) were cytotoxic, and induced the formation of dna lesions, which were measured as dna single-strand breaks after sedimentation in alkaline sucrose-density gradients. higher doses of 1-aminopyrene (25-60 micrograms/ml) inhibited the formati ... | 1986 | 3755797 |
| metal-induced dna damage and repair in human diploid fibroblasts and chinese hamster ovary cells. | cloning efficiency and dna strand breaks induction were compared in human diploid fibroblasts (hsbp) and chinese hamster ovary (cho) cells treated with various metal salts. cadmium (cd2+), nickel (ni2+) and chromate (cr2o7) reduced the cloning efficiency of hsbp cells more than that of cho cells whereas the reverse was true after treatment with mercury (hg2+), manganese (mn2+) and cobalt (co2+). the effects on cloning efficiency did not consistently correlate with dna strand breaking activity as ... | 1986 | 3757145 |
| hepatic effects of phthalate esters and related compounds--in vivo and in vitro correlations. | the hepatic effects of phthalate esters and related compounds on peroxisomal and microsomal enzyme activities were investigated in the intact animal and in primary hepatocyte cultures. in vitro studies with a series of phthalate monoesters demonstrated structure activity differences in the induction of the specific peroxisomal marker kcn-insensitive palmitoyl-coa oxidation and also of carnitine acetyltransferase. these effects could be reproduced in vivo, and potency differences were also observ ... | 1986 | 3757955 |
| browning reaction systems as sources of mutagens and antimutagens. | heated food systems contain hundreds of chemical compounds, some being mutagenic and others being antimutagenic. studies have indicated that foods exposed to drying, frying, roasting, baking, and broiling conditions possess net mutagenic activity as assessed by the ames/salmonella/microsome mutagenicity test and the chromosome aberration assay with chinese hamster ovary (cho) cells. with the above-mentioned heat treatment of food, nonenzymic browning reactions are generally proceeding at rapid r ... | 1986 | 3757959 |
| measurement of glycinamide ribonucleotide synthetase activity in intact human fibroblasts and chinese hamster ovary cells. | an intact cell assay system based on tween 80 permeabilization was used to investigate glycinamide ribonucleotide (gar) synthetase activity in human fibroblasts and chinese hamster ovary cells. optimal conditions for the assay of the enzyme were determined with regards to atp, mgcl2, nh4cl and ribose-5'-phosphate concentrations as well as ph. using the optimal assay conditions, the vmax values as determined by lineweaver-burke double reciprocal plots were found to be 5.19 nmol gar formed/5 x 10( ... | 1986 | 3757984 |
| the human c-reactive protein gene (crp) and serum amyloid p component gene (apcs) are located on the proximal long arm of chromosome 1. | the genes encoding two pentraxins, c-reactive protein (crp) and serum amyloid p component (sap), are located on the proximal long arm of human chromosome 1. mapping of the crp and sap genes between the centromere and band q32 was achieved by southern blot analysis of dna from a panel of human x chinese hamster somatic cell hybrids carrying defined fragments of human chromosome 1. both genes were localized more precisely between bands q12 and q23 by in situ hybridization to human metaphase chromo ... | 1986 | 3759147 |
| inhibition of human excision dna repair by inorganic arsenic and the co-mutagenic effect in v79 chinese hamster cells. | we investigated the lethal, uv killing-potentiating and repair-inhibiting effects of trivalent arsenic trioxide (as2o3) and pentavalent sodium arsenate (na2haso4) in normal human and xeroderma pigmentosum (xp) fibroblasts. the presence of as2o3 for 24 h after uv irradiation inhibited the thymine dimer excision from the dna of normal and xp variant cells and thus the subsequent unscheduled dna synthesis (uds): excision inhibitions were partial, 30-40%, at a physiological dose of 1 microgram/ml an ... | 1986 | 3762570 |
| dna repair genes of mammalian cells. | in the chinese hamster ovary (cho) cell line, various mutations affecting dna repair have been obtained. mutants that belong to 5 genetic complementation groups for ultraviolet (uv) sensitivity and resemble the cells from individuals having the cancer-prone genetic disorder xeroderma pigmentosum (xp) were previously identified. each mutant is defective in the incision step of nucleotide excision repair and hypersensitive to bulky dna lesions. these uv mutants can be divided into two subgroups; o ... | 1986 | 3767840 |
| purification and characterization of adenine phosphoribosyltransferase from mouse mammary carcinoma fm3a cells in culture. | adenine phosphoribosyltransferase has been purified to apparent homogeneity from mouse mammary tumor fm3a cells. the purified enzyme, with a specific activity of 20.6 x 10(6) units/g protein at 30 degrees c, was homogeneous as judged by polyacrylamide gel electrophoresis and ouchterlony double immunodiffusion analysis. the native enzyme had a molecular weight of 44,000 and a subunit composition of 23,000. apparent km values for adenine and 5-phosphoribosyl-1-pyrophosphate (prib-pp) were 6.6 micr ... | 1986 | 3768421 |
| assignment of a human beta-crystallin gene to 17cen-q23. | the gene map assignment of a human beta-crystallin gene to 17cen-q23 has been made using a bovine probe in the study of human-mouse and human-chinese hamster somatic cell hybrids containing parts of human chromosome 17. | 1986 | 3770741 |
| production of chinese hamster monoclonal antibody to a human cell-surface antigen using a hamster-human somatic cell hybrid as antigen. | hybridomas producing monoclonal antibody (mab) of predefined specificity were isolated from a chinese hamster that had received injections of a chinese hamster-human somatic cell hybrid. a standard method for the production of murine hybridomas was used to produce chinese spleen lymphocyte x murine plasmacytoma hybridomas, and they were screened for complement-mediated cytotoxicity against a panel of chinese hamster-human somatic cell hybrids and agglutination of human erythrocytes. two hybridom ... | 1986 | 3770776 |
| 24,25-epoxysterol metabolism in cultured mammalian cells and repression of 3-hydroxy-3-methylglutaryl-coa reductase. | in view of the potential importance of 24,25-epoxysterols as intracellular regulators of 3-hydroxy-3-methylglutaryl-coa reductase, the c-24 epimers of 24,25-oxidolanosterol and 24,25-epoxycholesterol were tested for their biological activity and metabolism in cell cultures. all four compounds produced repression of the reductase in cultured mouse fibroblasts (l cells), and both 24(s)- and 24(r),25-epoxycholesterol exhibited high affinity binding to the cytosolic oxysterol-binding protein. howeve ... | 1986 | 3771561 |
| cb 1954 (2,4-dinitro-5-aziridinyl benzamide) becomes a dna interstrand crosslinking agent in walker tumour cells. | walker tumour cells were shown to be uniquely sensitive to cb 1954 when compared with other cells in vitro. cb 1954 forms dna-dna interstrand crosslinks in a time-dependent manner in walker tumour but not chinese hamster cells. the absence of interstrand crosslinks in hamster cells was not due to a lack of uptake of drug but rather to a failure to convert (probably by bioreduction) cb 1954 to the required reactive difunctional intermediate. | 1986 | 3778483 |
| dna interaction and mutagenicity of the plastic stabilizer di-n-octyltin dichloride. | the organo-metallic compound di-n-octyltin dichloride (dotc) is used as an additive to plastics. since it is, therefore, present in the human environment, its long-term toxicity, particularly its genotoxic potential, is of concern. in the present studies, the agent was shown to interact with the dna of cultured v79 chinese hamster cells. though the compound did not induce mutagenesis in the salmonella-microsome assay and dna repair in primary rat hepatocytes, it did induce mutagenesis in v79 chi ... | 1986 | 3778564 |
| quantitative analysis of cellular glutathione by flow cytometry utilizing monochlorobimane: some applications to radiation and drug resistance in vitro and in vivo. | an assay using a bimane derivative has been developed to detect free glutathione (gsh) in individual viable cells by flow cytometry. monochlorobimane [syn-(clch2ch3)-1,5-diazabicycla[3.30]acta-3,6-diene-2,8-dio ne], itself nonfluorescent, reacts with gsh to form a highly fluorescent derivative. high pressure liquid chromatography analysis showed that, using specific staining conditions, the only low molecular weight fluorescent derivative formed in chinese hamster ovary cells was that formed wit ... | 1986 | 3779630 |
| asn-linked oligosaccharides in lectin-resistant tumor-cell mutants with varying metastatic potential. | mdw4, a wheat germ agglutinin-resistant mutant of the metastatic murine tumor mday d2 has previously been shown to be poorly metastatic when injected intravenously and non-metastatic when injected subcutaneously into syngeneic mice. w4eb8, a bandeiraea simplicifolia (bsii) lectin-selected subline of mdw4 has previously been shown to be intermediate between that of mday-d2 and mdw4 cell for sensitivity to lectin and metastatic phenotype when injected intravenously into mice. the asn-linked oligos ... | 1986 | 3780748 |
| an in vitro lung epithelial cell system for evaluating the potential toxicity of inhalable materials. | assays have been developed using a lung epithelial cell strain, lec, for evaluating the cytotoxicity and genotoxicity of gases, vapours, particles and fibres. lec was derived from an adult male fischer 344 rat and was cultured continuously in vitro for over 60 passages. the cells had an epithelial morphology, a near-diploid modal chromosome number of 43-44, and properties of untransformed cells. lamellar inclusion bodies were found in the cytoplasm, suggesting that lec originated from the type i ... | 1986 | 3781412 |
| characteristics of a lysosomal membrane transport system for tyrosine and other neutral amino acids in rat thyroid cells. | tyrosine countertransport was used to demonstrate the existence of a carrier system for neutral amino acids in the lysosomal membrane of frtl-5 thyroid cells. in addition to tyrosine, the carrier system recognized the neutral amino acids leucine, histidine, phenylalanine, and tryptophan. cystine and lysine, amino acids for which a lysosomal carrier system has been demonstrated, showed no competition with tyrosine for countertransport. the tyrosine system showed stereospecificity and cation indep ... | 1986 | 3782156 |
| transcription and translation of mitochondrial dna in interspecific somatic cell hybrids. | we examined the mitochondrial transcription and translation products of somatic cell hybrids constructed by the fusion of chinese hamster and mouse cells. the hybrid cell lines oac-k, oac-l, and oac-m contain approximately equal amounts of hamster and mouse mitochondrial dna and produced mitochondrial rrna from both parental species in the same ratio. cell lines oac-k, oac-l, and oac-m also produced poly(a)+ mouse mitochondrial rna transcripts comparable in complexity and quantity to poly(a)+ rn ... | 1986 | 3785185 |
| primary structure of human ribosomal protein s14 and the gene that encodes it. | chinese hamster ribosomal protein s14 cdna was used to recognize homologous human cdna and genomic clones. human and chinese hamster s14 protein sequences deduced from the cdnas are identical. two overlapping human genomic s14 dna clones were isolated from a charon 28 placental dna library. a fragment of single-copy dna derived from an intron region of one clone was mapped to the functional rps14 locus on human chromosome 5q by using a panel of human x chinese hamster hybrid cell dnas. the human ... | 1986 | 3785212 |
| transfection of a human gene for the repair of x-ray- and ems-induced dna damage. | em9 cells are a line of chinese hamster ovary cells that are sensitive to killing by ethylmethanesulfonate (ems) and x ray, since they are unable to repair the dna damage inflicted by these agents. through dna-mediated gene transfer, human dna and a selectable marker gene, psv2neo, were transfected into em9 cells. resistant clones of transfected cells were selected for by growth in ems and g418 (an antibiotic lethal to mammalian cells not containing the transfected neo gene). one primary clone ( ... | 1986 | 3786675 |
| chromatid repulsion associated with roberts/sc phocomelia syndrome is reduced in malignant cells and not expressed in interspecies somatic-cell hybrids. | different cell types from a female patient with roberts/sc phocomelia syndrome were evaluated quantitatively for the presence of repulsion of heterochromatin and satellite regions of mitotic chromosomes. whereas ebv-transformed lymphoblasts from an established cell line revealed these phenomena at frequencies equal to those in pha-stimulated lymphocytes and cultured skin fibroblasts, aneuploid cells from a metastatic melanoma displayed them at 50% lower frequency. cocultivation of the patient's ... | 1986 | 3788975 |
| differential toxicity of cis- and trans-diamminedichloroplatinum(ii) toward mammalian cells: lack of influence of any difference in the rates of loss of their dna-bound adducts. | dna-bound adducts formed by cis- or trans-diamminedichloroplatinum(ii) (cis-ddp or trans-ddp, respectively) have very different effects on dna synthesis and cell cycle progression in chinese hamster cells. when the loss of platinum from the dna of cells treated with pulsed doses of these isomers was corrected for the different effects they produced on dna replication and cell cycle progression, then adducts formed by either agent were lost slowly from dna and at comparable rates. the kinetics of ... | 1987 | 3791217 |
| cytotoxicity and mutagenicity of low intensity, 248 and 193 nm excimer laser radiation in mammalian cells. | the cytotoxicity of 193 and 248 nm excimer laser radiation was compared to that produced by a germicidal lamp (predominantly 254 nm) using chinese hamster ovary cells (cho), and a human diploid fibroblast line, ag-1522a. excimer laser radiation at 248 nm (3.5 x 10(2) w/m2) and germicidal radiation (5.3 x 10(-5) w/m2) caused toxicity in both cell lines, with the ag-1522a cells (d37 = 7-8 j/m2) being slightly more sensitive than the cho cells (d37 = 11 j/m2). incident 193 nm radiation was less cyt ... | 1987 | 3791231 |
| genetic analysis of a mouse t complex locus that is homologous to a kidney cdna clone. | a mouse kidney cdna clone, pmk174, identifies restriction fragment length polymorphisms (rflps) that map to two unlinked loci. one, designated d17rp17, has been mapped near quaking, (qk), on chromosome 17 using three sets of recombinant inbred (ri) strains. a study of several t haplotypes resulted in the identification of t-specific alleles of d17rp17 that map to the proximal half of the t complex. neither t-specific nor wild-type d17rp17 alleles are present in chromosomes carrying either the t ... | 1986 | 3792827 |
| cytotoxic and enterotoxic activities of campylobacter jejuni are not specified by tetracycline resistance plasmids pmak175 and pua466. | the 45-kilobase tetracycline resistance plasmids pmak175 and pua466 from campylobacter jejuni were examined using curing and mating experiments. however, these plasmids encoded neither cytotoxin production, as determined in vero cells, nor enterotoxin activity, as determined in chinese hamster ovary cells. | 1987 | 3793867 |
| imaging intracellular elemental distribution and ion fluxes in cultured cells using ion microscopy: a freeze-fracture methodology. | a freeze-fracture methodology was standardized for tissue culture cells to study intracellular distribution of diffusible elements with ion microscopy. chinese hamster ovary (cho) and normal rat kidney (nrk) cells grown on a silicon substrate were sandwiched using another smooth surface (silicon, glass, mica) in the presence of spacers and fast frozen in liquid nitrogen slush. the sandwich was fractured by prying the two halves apart under liquid nitrogen. this procedure produced large areas on ... | 1986 | 3795262 |
| repair-deficient xeroderma pigmentosum cells made uv light resistant by fusion with x-ray-inactivated chinese hamster cells. | xeroderma pigmentosum (xp) is an autosomal recessive human disease, characterized by an extreme sensitivity to sunlight, caused by the inability of cells to repair uv light-induced damage to dna. cell fusion was used to transfer fragments of chinese hamster ovary (cho) chromosomes into xp cells. the hybrid cells exhibited uv resistance and dna repair characteristics comparable to those expressed by cho cells, and their dna had greater homology with cho dna than did the dna from xp cells. control ... | 1986 | 3796587 |
| chromosome-mediated gene transfer of multidrug resistance. | multidrug resistance can be transferred from drug-resistant lz chinese hamster cells to drug-susceptible mouse lta cells by chromosome-mediated gene transfer. analysis of genomic dna demonstrated the transfer of multiple copies of a dna domain which is amplified in the donor multidrug-resistant cells. the transfer of 10 to 15 copies of the chinese hamster gene was sufficient to produce a multidrug-resistant phenotype. chromosome transferents exhibited overexpression of an mrna of approximately 5 ... | 1986 | 3796594 |
| identification of temperature-sensitive dna- mutants of chinese hamster cells affected in cellular and viral dna synthesis. | we described a strategy which facilitates the identification of cell mutants which are restricted in dna synthesis in a temperature-dependent manner. a collection of over 200 cell mutants temperature-sensitive for growth was isolated in established chinese hamster cell lines (cho and v79) by a variety of selective and nonselective techniques. approximately 10% of these mutants were identified as ts dna- based on differential inhibition of macromolecular synthesis at the restrictive temperature ( ... | 1986 | 3796611 |
| monoclonal antibodies against metallothioneins and metalloproteins. | monoclonal antibodies against rabbit metallothioneins (mt) were prepared by in vitro immunization of mouse lymphocytes with a mixture of the two forms of metallothionein mt1 and mt2. six igm antibodies (tn1,3,4,5,6,7) which bind to metallothionein were characterized. antibody tn3 is specific for rabbit mt1 and does not react with any other mt's tested. tn5 is specific for both rabbit mt1 and mt2. tn7 is specific for rabbit mt2 but not mt1 and cross-reacts also with chinese hamster, mouse and rat ... | 1986 | 3796622 |
| interactions of nitrilotriacetic acid (nta) with cr(vi) compounds in the induction of gene mutations in cultured mammalian cells. | we used the v79 chinese hamster cell line to detect the induction by nta of 6-thioguanine resistance, due to mutation at the hgprt locus, with direct and indirect mutagens as positive controls. nta was tested within the 10(-4)-1.5 x 10(-2) m concentration range: although it was cytotoxic above the 10(-2) m dose, it did not increase the frequency of mutations at any of the tested concentrations, independently of metabolic activation (rat-liver s9 fraction). nta is known to dissolve heavy metals a ... | 1987 | 3796669 |
| purification and characterization of enolase from neuroblastoma cell line ng108. | neuroblastoma cell line ng108 (a hybrid from chinese hamster and mouse) produces high levels of enolase. using ion-exchange chromatography and gel filtration, we have purified the enzyme (about 19 fold purification) and characterized it. the purified enzyme is a dimer of 90,000 m.wt. and is stable at room temperature. at higher temperatures (e.g., 50 degrees, 60 degrees c etc.) it gets inactivated. enolase requires mg++ for its activity and is resistant to urea. the optimum ph for the enzyme is ... | 1986 | 3801033 |
| chromosome segregation from cell hybrids. ii. do differences in parental cell growth rates and phase times determine direction of loss? | the hypothesis that the direction of chromosome segregation in cell hybrids is determined by the interaction of parent cell cycles, or s-phase times, predicts that the segregant parent will always be the one with the longer cycle, or the longer s phase, and that late replicating chromosomes will be more frequently lost. we have tested this hypothesis by studying cell cycle parameters of mouse, chinese hamster, and platypus parent cells and by observing chromosome loss and replication patterns in ... | 1986 | 3801969 |
| evaluation of a tetrazolium-based semiautomated colorimetric assay: assessment of radiosensitivity. | radiation survival curves were generated for v79 chinese hamster and two human lung cancer cell lines (nci-h460 and nci-h249) with doubling times of 10, 20, and 85 h, respectively, using a standard clonogenic assay, a dye exclusion assay, and a semiautomated colorimetric assay utilizing a tetrazolium salt, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenylformazan bromide. comparable results for d0 and extrapolation number (n) were observed for all assays in the lines with doubling times of 10 and 20 h. ... | 1987 | 3802101 |
| metabolism and activation of n-nitrosodimethylamine by hamster and rat microsomes: comparative study with weanling and adult animals. | it has been reported that hamster liver preparations are more effective for the metabolic activation of n-nitrosodimethylamine (ndma) to a mutagen than rat liver preparations. the enzymatic basis for this phenomenon, however, has not been clearly elucidated. the present study was undertaken to examine the enzymology of ndma metabolism by different hepatic subcellular fractions prepared from hamsters and rats of two different ages, and to investigate the correlation between the metabolism and the ... | 1987 | 3802105 |
| physicochemical characteristics and biological effects of nickel oxides. | ten nickel oxides and nickel-copper oxides, which all contained nio (bunsenite) as the predominant crystalline phase, were assayed as follows: in vitro dissolution tests in water and body fluids; in vitro phagocytosis tests in chinese hamster ovary and c3h-10t1/2 cells; morphological transformation and cytotoxicity tests in cultured syrian hamster embryo (she) cells; erythropoiesis stimulation assay by intrarenal administration to fischer-344 rats; and scoring the renal histopathologic responses ... | 1987 | 3802416 |
| characterization of the region around the start point of transcription of ribosomal rna in the chinese hamster. | the initiation site for ribosomal rna transcription in the chinese hamster was identified and the sequence around and upstream determined. the start point region shows considerable homology with comparable regions in the mouse and rat. in the chinese hamster, the region between bp -700 and -200 consists of imperfect repeats approximately 120-130 bp in length which are flanked by t-rich regions. the region within each repeat which is homologous with an adjacent repeat decreases in length as the s ... | 1986 | 3803927 |
| regulation of secretion of the hepatitis b virus major surface antigen by the pres-1 protein. | p24, p30, and p39, the three major surface antigens of the envelope of hepatitis b virus, are co-carboxy-terminal proteins with different amino-terminal extensions. we prompted expression of these proteins in chinese hamster ovary (cho) cells by placing the appropriate coding sequence(s) under the control of the simian virus 40 early promoter. p24 and p30 formed 22-nm particles which were efficiently secreted. in contrast, p39 accumulated in a perinuclear structure, presumably the golgi complex, ... | 1987 | 3806798 |
| a comparison of the radiation-induced mutation at the hgprt locus in v79 and bhk cells. | mutation response at the hgprt locus has been compared in two differing cell lines: v79/4, an aneuploid chinese-hamster fibroblast line with a complement of 20 chromosomes, and bhk21-c13, a diploid syrian-hamster fibroblast line with a complement of 44 chromosomes. the data presented show that bhk is slightly more radiosensitive than v79/4; however, the toxicity curves and expression times are similar for both cell lines. if radiosensitivity is taken into account, a common line can be drawn for ... | 1987 | 3807932 |
| in situ autoradiographic detection of folylpolyglutamate synthetase activity. | the enzyme folylpolyglutamate synthetase (fpgs) catalyzes the conversion of folate (pteroylmonoglutamate) to the polyglutamate forms (pteroylpolyglutamates) that are required for folate retention by mammalian cells. a rapid in situ autoradiographic assay for fpgs was developed which is based on the folate cofactor requirement of thymidylate synthase. chinese hamster aux b1 mutant cells lack fpgs activity and are unable to accumulate folate. as a result, the conversion of [6-3h]deoxyuridine to th ... | 1986 | 3812977 |
| cytotoxicity of compounds that interfere with the regulation of intracellular ph: a potential new class of anticancer drugs. | the extracellular ph (phe) in many solid tumors is often lower than in normal tissues. cells may survive conditions of acid phe because antiports in their membrane exchange na+ for h+, or hco3- for cl-, and thus regulate the intracellular ph (phi). we have therefore assessed the effects of drugs which interfere with regulation of phi on survival of chinese hamster ovary and human bladder cancer mgh-u1 cells in tissue culture. nigericin, an ionophore which acidifies the cytoplasm when cells are p ... | 1987 | 3815351 |