Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| depletion of glutathione after gamma irradiation modifies survival. | the relationship between the intracellular glutathione (gsh) concentration and the aerobic radiation response was studied in chinese hamster ovary cells. various degrees of gsh depletion were produced by exposure to buthionine sulfoximine (bso) and/or diethyl maleate (dem). diethyl maleate did not act as a classical radiosensitizer under the experimental conditions employed, nor did exposure to dem/bso nonspecifically affect protein thiols as measured by thiol blotting. dose-response curves were ... | 1991 | 2000450 |
| characterization of binding proteins from ovarian carcinoma and kidney tubule cells that are specific for cisplatin modified dna. | we have detected proteins in nuclear extracts from ovarian carcinoma cells and kidney tubule cells that bind specifically to platinated dna. a 123-bp restriction fragment was platinated with cisplatin (ddp) to a formal molar platinum to nucleotide ratio of 0.05 and end-labeled with [32p]-dctp. incubation with nuclear extracts from 2008 human ovarian carcinoma cells caused shifts in the mobility of this probe in non-denaturing polyacrylamide gels. proteinase k, but not ribonuclease a, destroyed t ... | 1991 | 2001331 |
| carbohydrate structures of recombinant soluble human cd4 expressed in chinese hamster ovary cells. | infection of t-lymphocytes and macrophages by human immunodeficiency virus (hiv) is mediated by the binding of the hiv envelope glycoprotein to the cell-surface receptor glycoprotein cd4. a soluble, recombinant cd4 molecule (rcd4), produced by expression of a truncated cd4 gene in chinese hamster ovary (cho) cells [smith et al. (1987) science 238, 1704-1707], is in clinical trials as a potential therapeutic agent in the treatment of acquired immunodeficiency syndrome (aids). in the present study ... | 1991 | 2001369 |
| isolation and characterization of a human cdna encoding uracil-dna glycosylase. | dna repair of genetic information is an essential defense mechanism, which protects cells against mutation and transformation. the biochemistry of human dna repair is in its beginning stages. our research has concentrated on the enzymes involved in the removal of atypical bases from dna. we present information on the identification and characterization of a cdna isolate encoding uracil-dna glycosylase. uracil-dna glycosylase was purified to homogeneity from hela s3 cells and used to generate pol ... | 1991 | 2001396 |
| effect of thiols on micronucleus frequency in gamma-irradiated mammalian cells. | the effects of the thiols cysteamine, wr-1065, and wr-255591 on radiation-induced micronucleus (mn) frequency and cell killing were compared in cultured chinese hamster ovary cells. mn were measured using the cytochalasin b assay of fenech and morley (1985), which minimizes the effect of cytokinetic perturbations on mn expression. the dose-response curves for mn induction were curvilinear both for control cells at doses between 1.5 and 4.5 gy and for thiol-treated cells at doses between 3 and 9 ... | 1991 | 2002801 |
| investigation of soy sauce treated with nitrite in the chromosomal aberration test in vitro and the micronucleus test in vivo. | soy sauce pretreated with 2300 ppm nitrite caused no more aberrations than did untreated soy sauce in the chromosomal aberration test in vitro using a chinese hamster fibroblast cell line with or without s9 mixture. the aberration induction by soy sauce is likely to be caused by the 17% sodium chloride it contains. soy sauce with or without pretreatment with 2300 ppm nitrite was orally given to icr mice at a dose of 14 ml/kg body weight once or 6 ml/kg body weight/day for 5 consecutive days. thi ... | 1991 | 2002815 |
| no induction of interchromosomal effect in male meiosis of chinese hamsters with reciprocal translocations. | chinese hamsters from five strains with reciprocal translocations, t(1;3)7idr, t(1;3)8idr, t(1;2)9idr, t(7;9)16idr, and t(1;5)17idr, and a karyotypically normal strain, chs/idr, were used to look for an interchromosomal effect by chromosomal analysis of meiotic cells and one-cell embryos. the frequencies of nondisjunction at first meiosis in five normal (+/+) males, calculated by doubling the number of hyperhaploid cells, ranged from 0.43% to 1.33%, and there was no significant difference in fre ... | 1991 | 2004562 |
| posttranslational modifications of rat proenkephalin overexpressed in chinese hamster ovary cells. | rat proenkephalin was overexpressed in chinese hamster ovary cells using the dihydrofolate reductase-coupled genetic amplification method. about 2 mg purified protein could be obtained from 250 ml conditioned medium; multiple successive harvests could be obtained from the same roller bottle. degradation of proenkephalin released into the conditioned medium was reduced significantly in the presence of 2% fetal bovine serum. forty-eight percent of recombinant proenkephalin was glycosylated; glycos ... | 1991 | 2004604 |
| resistance to dna denaturation in irradiated chinese hamster v79 fibroblasts is linked to cell shape. | exponentially growing chinese hamster v79-171b lung fibroblasts seeded at high density on plastic (approximately 7 x 10(3) cells/cm2) flatten, elongate, and produce significant amounts of extracellular fibronectin. when lysed in weak alkali/high salt, the rate of dna denaturation following exposure to ionizing radiation is exponential. conversely, cells plated at low density (approximately 7 x 10(2) cells/cm2) on plastic are more rounded 24 h later, produce little extracellular fibronectin, and ... | 1991 | 2004650 |
| the chinese hamster hprt gene: restriction map, sequence analysis, and multiplex pcr deletion screen. | the fine structure of the chinese hamster hypoxanthine guanine phosphoribosyltransferase (hprt) gene has been determined; the gene has nine exons and is dispersed over 36 kb dna. exons 2-9 are contained within overlapping lambda bacteriophage clones and exon 1 was obtained by an inverse polymerase chain reaction (pcr). all the exons have been sequenced, together with their immediate flanking regions, and these sequences compared to those of the mouse and human hprt genes. sequences immediately f ... | 1991 | 2004774 |
| mapping of a locus correcting lack of phosphoribosylaminoimidazole carboxylase activity in chinese hamster ovary cell ade-d mutants to human chromosome 4. | the human phosphoribosylaminoimidazole (air) carboxylase locus has been until this report one of the genes encoding purine biosynthetic enzymes that had not been assigned to an individual human chromosome. characterization of chinese hamster ovary (cho) cell mutant ade-d showed that the cell line was unable to produce imp and accumulated air. cho ade-d cells were fused with normal human lymphocytes utilizing inactivated sendai virus and the resulting hybrid cell lines were selected for purine pr ... | 1991 | 2004782 |
| a gene correcting the defect in the cho mutant ade -h, deficient in a branch point enzyme (adenylosuccinate synthetase) of de novo purine biosynthesis, is located on the long arm of chromosome 1. | somatic hybrids between human cells and the chinese hamster ovary (cho) k1 mutant, ade -h cells, were selected for purine prototrophy by growth in adenine-free medium. the ade -h mutant is defective in the enzyme adenylosuccinate (amps) synthetase (adss; ec 6.3.4.4), which carries out the first of a two-step sequence in the biosynthesis of amp from imp, and therefore requires exogenous adenine for growth. the presence of the long arm of human chromosome 1 in the hybrids is 100% concordant for th ... | 1991 | 2004783 |
| isolation of 37 single-copy dna probes from human chromosome 6 and physical mapping of 11 probes by in situ hybridization. | fifty-five single-copy dna probes were isolated from the library ll06ns01, which was constructed from a complete hindiii digest of a flow-sorted human chromosome 6. because chromosomes from a human x chinese hamster somatic cell hybrid were used as the starting material for the flow-sorting, the library could be expected to contain some contaminating chinese hamster dna as well as dna from human chromosomes other than 6. thirty-seven of the 55 probes, however, were shown to map to human chromoso ... | 1991 | 2004785 |
| the peripherin gene maps to mouse chromosome 15. | we have mapped the mouse peripherin gene, prph, to chromosome 15 by means of southern analysis of a panel of chinese hamster/mouse somatic cell hybrids using a rat peripherin cdna probe. peripherin is a recently characterized type iii intermediate filament expressed in the peripheral and the central nervous system. although its exact function is not known, peripherin is likely to be involved in the neuronal cytoskeleton, a role it shares with other intermediate filaments, such as the neurofilame ... | 1991 | 2004788 |
| structural analysis of the transmembrane domain of the epidermal growth factor receptor. | the ligand-binding domain of the epidermal growth factor (egf) receptor is separated from the cytoplasmic protein tyrosine kinase domain by a predicted single transmembrane segment. antipeptide antibodies prepared against the outer portion of the predicted transmembrane segment confirmed this area was exposed only when cells were treated with permeabilizing agents. to investigate structural requirements for signal transduction by the transmembrane domain, three types of mutant egf receptor were ... | 1991 | 2005111 |
| multiple signals activate cleavage of the membrane transforming growth factor-alpha precursor. | cleavage of the membrane-anchored precursor for transforming growth factor-alpha (tgf-alpha), a rate-limiting step in the generation of soluble tgf-alpha, can be stimulated by phorbol esters acting via protein kinase c. in the present study, activators of other intracellular signaling pathways were tested for their ability to stimulate pro-tgf-alpha cleavage in chinese hamster ovary cells transfected with a pro-tgf-alpha cdna. treatment with the ca2+ ionophore, a23187, rapidly increased the rate ... | 1991 | 2005114 |
| a novel suicide inhibitor strategy for antiparasitic drug development. | dl-alpha-difluoromethylornithine (dfmo), a suicide inhibitor of eukaryotic ornithine decarboxylase (odc), has therapeutic activities against african trypanosomiasis. the ki value of dfmo for odc of trypanosoma brucei is somewhat higher than that for mouse odc. the therapeutic efficacy of dfmo cannot therefore be attributed to a preferential inhibition of the parasite enzyme. the t. brucei gene encoding odc was cloned and sequenced, and the derived amino acid sequence has 61.5% homology with that ... | 1991 | 2005184 |
| differential introduction of dna damage and repair in mammalian genes transcribed by rna polymerases i and ii. | we have developed a general quantitative method for comparing the levels of drug-induced dna crosslinking in specific mammalian genes. we observed a dramatic difference between the efficiency of the removal of both psoralen monoadducts and interstrand crosslinks from the rrna genes and the efficiency of their removal from the dihydrofolate reductase (dhfr) gene in cultured human and hamster cells. while 90% of the interstand crosslinks were removed from the human dhfr gene in 48 h, less than 25% ... | 1991 | 2005908 |
| a cloned gene encoding phosphatidylserine decarboxylase complements the phosphatidylserine biosynthetic defect of a chinese hamster ovary cell mutant. | a phosphatidylserine-auxotrophic mutant of cultured chinese hamster ovary cells, psa-3, manifests a defect in phosphatidylserine synthase i activity (kuge, o., nishijima, m., and akamatsu, y. (1986) j. biol. chem. 261, 5790-5794). we cloned a chinese hamster gene, designated pssc, which was able to transform the psa-3 cell line to a phosphatidylserine prototroph. the resultant transformant contained phosphatidylserine in normal amounts but remained defective in phosphatidylserine synthase i acti ... | 1991 | 2007589 |
| studies on the immunogenicity of chinese hamster ovary cell-derived recombinant gp120 (hiv-1iiib). | recombinant dna-derived gp120 (hiv-1iiib) expressed in chinese hamster ovary cells elicited specific humoral and cell-mediated immune responses in a variety of mammals. antisera from immunized rabbits, sheep and goats recognized virus-derived gp120 and its precursor (gp160). neutralizing antibodies were also elicited, but only in a few animals, and this may be related to the protein's susceptibility to cleavage through the neutralizing domain. however, in rabbits the degree of cleavage of gp120 ... | 1991 | 2008801 |
| comparative chemical and biological studies of four prototype phosphoraziridine antineoplastic agents. | the chemical alkylating activities of four prototype phosphoraziridine antineoplastic agents were compared with their biological effects on v-79 chinese hamster lung fibroblasts. it was found that the chemical reactivity patterns correlate well with all of the biological parameters examined in this study, i.e. cytotoxicity, dna synthesis, and production of alkali labile strand breaks. specifically, the 2,2-dimethylaziridine derivatives (ab-132 and ab-163) showed higher initial activities reachin ... | 2007 | 2009083 |
| temperature dependence of melphalan efflux kinetics in chinese hamster ovary cells. | the temperature dependence of the kinetics of efflux of melphalan from chinese hamster ovary (cho) cells was studied from 4 degrees to 47 degrees. time courses for melphalan efflux showed an initial rapid phase of efflux followed by a plateau. the data for melphalan concentration (c) versus efflux time (t) were described by the equation c(t) = a + b exp(-kt), where a is the final steady-state melphalan concentration, b is the total change in melphalan concentration from time zero until steady-st ... | 1991 | 2009093 |
| a method for determination of iododeoxyuridine substitution of thymidine using reversed-phase high-performance liquid chromatography. | an assay for thymidine substitution by iododeoxyuridine (idurd) using reversed-phase high-performance liquid chromatography (hplc) has been developed. three principal steps in this procedure are: extraction of dna from cell or tissues, hydrolysis of dna into deoxynucleosides and separation using hplc. approximately 1 microgram of dna was recovered from 10(5) cells by phenol extraction, and subjected to hydrolysis into deoxynucleosides which required a three-stage dna digestion using enzymes dnas ... | 1991 | 2009316 |
| ethanol potentiates doxorubicin-induced inhibition of cell survival in cultured chinese hamster ovary cells. | doxorubicin is an antineoplastic drug which undergoes oxidation-reduction cycling and produces toxicity to some cancer cell lines. since oxidation-reduction cycling requires reducing equivalents and because ethanol metabolism via alcohol dehydrogenase (adh) increases nadh, the effect of ethanol on doxorubicin toxicity was examined in cultured cells. since some cells exhibit resistance to anthracyclines such as doxorubicin, two different chinese hamster ovary cell lines were used, one sensitive ( ... | 1991 | 2009522 |
| human müllerian inhibiting substance inhibits tumor growth in vitro and in vivo. | müllerian inhibiting substance (mis) causes regression of the müllerian duct in the male fetus. bovine mis has been reported to inhibit the growth of some gynecological tumors. recombinant human mis (rhmis) produced in transfected chinese hamster ovary cells has been highly purified by immunoaffinity chromatography. the introduction of a salt wash prior to elution of mis from the affinity column removes a growth-stimulating factor(s) derived from chinese hamster ovary cells. this immunopurified ... | 1991 | 2009529 |
| inhibition of tumor invasion of smooth muscle cell layers by recombinant human metalloproteinase inhibitor. | matrix metalloproteinases secreted by tumor cells play an important role in the proteolytic degradation of the extracellular matrix during invasion. in a previous study, we showed that the degradation of extra-cellular matrices by human ht 1080 fibrosarcoma cells is suppressed by endothelial cells. the identification of inhibitors of metalloproteinases secreted by endothelial cells led us to postulate that these inhibitors were responsible for the suppressive effect (cancer res., 46: 3580-3586, ... | 1991 | 2009533 |
| notes to application of the v79 metabolic cooperation assay for detection of potential tumor promoters. | many chemicals which promote tumorigenesis in vivo have been observed to inhibit metabolic cooperation between 6-thioguanine-resistant (6tgr) and sensitive (6tgs) chinese hamster lung v79 cells. the apparent correlation between inhibition of metabolic cooperation in v79 cells in vitro and promotion of oncogenesis in vivo has led to the suggested utilization of the assay as a screen for tumor promoters. several parameters concerning the v79 metabolic cooperation assay were investigated for an imp ... | 1991 | 2011213 |
| polyoma and hamster papovavirus large t antigen-mediated replication of expression shuttle vectors in chinese hamster ovary cells. | eukaryotic expression vectors have been used successfully in viral lt-expressing cell lines (ie. cos) to clone cdnas encoding proteins that can be detected through their bio-activity or reactivity with specific antibodies. since chinese hamster ovary cells (cho) have been used extensively for the isolation and characterization of somatic cell mutants, we felt it would be an advantage to develop an expression cloning system in cho cells. we have modified the eukaryotic expression vector cdm8 by r ... | 1991 | 2011514 |
| correlation between cell survival and dna single-strand break repair proficiency in the chinese hamster ovary cell lines aa8 and em9 irradiated with 365-nm ultraviolet-a radiation. | cell survival parameters and the induction and repair of dna single-strand breaks were measured in two chinese hamster ovary cell lines after irradiation with monochromatic uva radiation of wavelength 365 nm. the radiosensitive mutant cell line em9 is known to repair ionizing-radiation-induced single-strand breaks (ssb) more slowly than the parent line aa8. em9 was determined to be 1.7-fold more sensitive to killing by 365-nm radiation than aa8 at the 10% survival level, and em9 had a smaller sh ... | 1991 | 2011627 |
| detection of direct mutagenicity of cigarette smoke condensate in mammalian cells. | mutagenicity of cigarette smoke condensate (csc) and the acidic, basic and neutral fractions of csc was examined in the al hybrid cell, a chinese hamster ovary cell containing one human chromosome 11. since the human chromosome 11 is not necessary for survival of the al cells, mutations involving large deletions and chromosomal loss by non-dysjunction are non-lethal events that are detectable by loss of human cell surface antigens (a1, a2 and a3) encoded by genes on chromosome 11p (a1 and a3) an ... | 1991 | 2013132 |
| genetic mapping of the gene for androgen-binding protein/sex hormone-binding globulin to mouse chromosome 11. | southern blot analysis of dnas from chinese hamster x mouse and rat x mouse somatic cell hybrids showed that the mouse gene encoding androgen-binding protein/sex hormone-binding globulin (abp-shbg) is on chromosome 11. progeny from an intersubspecies backcross were analyzed to position this locus, termed shbg, between il-3 and int-4 in the middle of this chromosome. shbg is thus closely linked to several neurological mutations, one of which, tr, is also associated with male sterility. the recent ... | 1991 | 2013230 |
| mapping of the silver fox genes: assignments of the genes for me1, adk, pp, pepa, gsr, mpi, and got1. | evidence is presented for the assignment of seven fox genes on the basis of the segregation data for chromosomes and enzymes of fox x chinese hamster somatic cell hybrids. the chromosomal loci of the following enzyme genes were determined: me1, vfu1; adk and pp, vfu4; pepa, vfu5; gsr, vfu7; and mpi and got1, vfu15. the localization of these genes now extends the fox genetic map to 22 mapped genes. based on comparative analysis of mammalian genetic maps, karyotype evolution in carnivora is discus ... | 1991 | 2013231 |
| differential effect of cysteine-to-serine substitutions in metallothionein on cadmium resistance. | a set of mutant coding sequences for chinese hamster metallothionein (mt) 2 in which codons for individual cysteines were replaced by serine codons was cloned into a yeast expression system. mt gene expression was placed under control of a constitutive promoter on a multicopy escherichia coli-yeast shuttle vector. mts were expressed in a metal-sensitive host that lacks the endogenous mt gene. the expressed mts conferred increased metal resistance to the yeast host. a sensitive assay for cadmium ... | 1991 | 2014225 |
| factors influencing survival of mammalian cells exposed to hypothermia. v. effects of hepes, free radicals, and h2o2 under light and dark conditions. | cytotoxicity resulting from the interaction of fluorescent light from a flow hood with hepes-buffered cell culture medium at room temperature was demonstrated. toxicity was prevented by keeping both cells (v79 chinese hamster) and medium shielded from direct fluorescent light ("dark conditions") or by supplementing the medium with 10 micrograms/ml catalase; this suggests that extracellular hydrogen peroxide is a major cause of the lethal effect under "lighted conditions." no sensitization result ... | 1991 | 2015762 |
| characterization of oxygen-resistant chinese hamster ovary cells. iii. relative resistance of succinate and alpha-ketoglutarate dehydrogenases to hyperoxic inactivation. | we have recently shown that exposure of chinese hamster ovary (cho) cells to a toxic dose of normobaric hyperoxia (98% o2 for 3 days) caused a disturbance of cellular energy metabolism, that is, respiratory failure followed by stimulation of glycolytic activity and a net depletion of atp. respiratory failure was correlated with a selective inactivation of three mitochondrial enzymes, that is, partial inactivation of nadh dehydrogenase and virtually complete inactivation of succinate and alpha-ke ... | 1991 | 2016073 |
| isolation and characterization of recombinant human prorenin in chinese hamster ovary cells. | recombinant human prorenin (rh-prorenin) was purified from supernatants of chinese hamster ovary (cho) cell line transfected with the cdna for rh-prorenin by employing a simple two-step procedure which consisted of ammonium sulfate precipitation and immunoaffinity chromatography using a monoclonal antibody specific for the profragment of human prorenin. about 100-fold purification with 35% recovery was achieved after the two steps. purified rh-prorenin migrated as a single protein band with appa ... | 1991 | 2016271 |
| estradiol beta-d-xyloside, an efficient primer for heparan sulfate biosynthesis. | animal cells utilize beta-d-xylosides as primers for glycosaminoglycan synthesis. however, most xylosides preferentially stimulate chondroitin sulfate synthesis and only weakly prime heparan sulfate synthesis. to test if the structure of the aglycone determines the type of glycosaminoglycan made, the priming activity of methyl, n-octyl, p-nitrophenyl, 4-methylumbelliferyl, trans,trans-farnesyl, cholesteryl, and estradiol beta-d-xylosides was compared. their potency was tested in pgsa-745 cells, ... | 1991 | 2016281 |
| gene-specific formation and repair of cisplatin intrastrand adducts and interstrand cross-links in chinese hamster ovary cells. | we have used three methods to study the formation and repair of intrastrand adducts and interstrand cross-links in the dna of chinese hamster ovary cells induced by the anticancer drug cis-diamminedichloroplatinum ii (cisplatin). using atomic absorption spectroscopy, we found that 21% of the total genomic cisplatin adducts were removed at 8 h and 42% at 24 h. we used abc excinuclease digestion, coupled with out previously reported methodology to quantify dna in specific genomic regions. these ad ... | 1991 | 2016318 |
| synthesis of potential dual-acting radiation sensitizer antineoplastic agents: 2,2-dimethylphosphoraziridines containing 2-nitroimidazoles or other electron-affinic moieties. | in view of the in vivo demonstrated radiation-potentiating activities of several previously studied 2,2-dimethylphosphoraziridines, six new compounds incorporating the bis(2,2-dimethyl-1-aziridinyl)phosphinyl moiety, together with an electron-affinic group such as 2-nitroimidazole or nitrobenzyl, have been synthesized and tested (1) in vitro for ability to increase the effect of x-irradiation under hypoxic conditions on v-79 chinese hamster lung fibroblast cells, (2) in vivo for antitumor activi ... | 1991 | 2016716 |
| site-directed mutagenesis of the human thyrotropin receptor: role of asparagine-linked oligosaccharides in the expression of a functional receptor. | we studied the role of glycosylation in the expression of a functional human tsh receptor. oligonucleotide-directed mutagenesis was used to replace, separately or together, the asn codons with gln in each of the six potential glycosylation sites in the receptor. recombinant wild-type and mutated tsh receptors were stably expressed in chinese hamster ovary cells. high affinity tsh binding and the camp response to tsh stimulation were abolished in the receptor mutated at asn77 as well as in the re ... | 1991 | 2017190 |
| effects of 2,4-dichlorophenoxyacetic acid on polyamine synthesis in chinese hamster ovary cells. | it was found that 1 mm 2,4-dichlorophenoxyacetate (2,4-d) inhibited dna and protein synthesis in chinese hamster ovary (cho) cells. when the possible relationship of this phenomenon to the presence of polyamines in the culture medium was investigated, it was found that: (a) the pesticide inhibited ornithine decarboxylase activity; (b) when the concentration of polyamines present in cells treated with the pesticide was determined, the putrescine concentration did not change, and the spermine and ... | 1991 | 2017772 |
| induction of chromosome changes by metal compounds in cultured cho cells. | the effect of 4 metal salts on the induction of chromosome aberrations and sister chromatid exchange (sce) in cultured chinese hamster ovary (cho) cells was investigated. it was observed that cdcl2, nicl2, cro3 and hgcl2 were effective in causing various types of chromosome aberrations. the percentages of abnormalities increased with increasing doses of the metals used. these metal compounds also raised the sce rates compared to 5-bromo-2'-deoxyuridine controls. the importance of rapid screening ... | 1991 | 2017776 |
| genotoxicity studies of the reaction of chlorine or chlorine dioxide with l-tryptophan. | non-volatile reaction products generated from the reactions of 70 mm aqueous chlorine or chlorine dioxide with 10 mm l-tryptophan were shown to be direct-acting mutagens to salmonella typhimurium ta100 and ta98. several of the fluorescent bands obtained after thin-layer chromatographic fractionation of the xad-2/8 resin concentrates of the reaction mixtures were shown to be more mutagenic than the reaction mixtures using the ames salmonella/microsome assay. in addition, these fractions were show ... | 1991 | 2017781 |
| chinese hamster ovarian cells transfected with the murine interleukin-6 gene cause hypercalcemia as well as cachexia, leukocytosis and thrombocytosis in tumor-bearing nude mice. | the effects of interleukin-6 (il-6) in vivo were assessed by inoculating chinese hamster ovarian (cho) cells which were transfected with the murine il-6 gene in nude mice. nude mice bearing cho cells expressing il-6 developed hypercalcemia. tumor-bearing mice also showed increases in white cell count, platelet count, and decreases in body weight. in nude mice carrying cho tumors which had not been transfected with the il-6 gene, there were no changes in these parameters. these results suggest th ... | 1991 | 2019273 |
| the protective activity of tea against infection by vibrio cholerae o1. | extracts of black tea exhibited bactericidal activity against vibrio cholerae o1. the tea extract inhibited the haemolysin activity of v. cholerae o1, el tor and the morphological changes of chinese hamster ovary cells induced by cholera toxin. tea extract also reduced fluid accumulation induced by cholera toxin in sealed adult mice and by v. cholerae o1 in ligated intestinal loops of rabbits. these findings suggest that tea has protective activity against v. cholerae o1. | 1991 | 2019547 |
| identification of phosphorylated sites in the mouse glucocorticoid receptor. | glucocorticoid receptors in vivo are phosphorylated in the absence of hormone and become hyperphosphorylated in the presence of glucocorticoid agonist but not antagonists (ortí, e., mendel, d.b., smith, l.i., and munck, a. (1989) j. biol. chem. 264, 9728-9731). as a preliminary step to elucidating the functional significance of receptor phosphorylation, we have identified seven phosphorylated sites on the mouse receptor. tryptic phosphopeptides from 32p-labeled receptors were purified from gluco ... | 1991 | 2019585 |
| substitution of leucine for tryptophan 412 does not abolish cytochalasin b labeling but markedly decreases the intrinsic activity of glut1 glucose transporter. | glut1 glucose transporter cdna was modified to introduce a single amino acid substitution of leucine for tryptophan 412, a putative cytochalasin b photo-affinity labeling site. although the mutated transporter was expressed into plasma membranes of chinese hamster ovary cells, glucose transport activity of the mutated transporter was observed to be only 15-30% of that of the wild-type glut1 when glucose transport activity was assessed by 2-deoxyglucose uptake at 0.1-10 mm concentrations. analysi ... | 1991 | 2019601 |
| characterization of tissue-specific enhancer elements in the second intron of the human apolipoprotein b gene. | we report the identification and characterization of tissue-specific transcriptional enhancer elements that influence the expression of the human apolipoprotein b gene. a 704-base pair psti fragment comprising sequences from the first and second introns of the human apolipoprotein b gene (positions +360 to +1064) possesses tissue-specific transcriptional enhancer elements when assayed in transient transfection experiments using either the apolipoprotein b or thymidine kinase promoter. the majori ... | 1991 | 2019605 |
| six chains of the human t cell antigen receptor.cd3 complex are necessary and sufficient for processing the receptor heterodimer to the cell surface. | the t cell antigen receptor (tcr) plays a key role in the process of antigen recognition. it is a complex of at least seven peptide chains (alpha beta gamma delta epsilon zeta-zeta). it is found on the surface of mature t cells and functions in antigen binding in the presence of the major histocompatibility complex. it has been known for some time that physical associations between the cd3 proteins and the tcr chains are essential for efficient transport of either component to the surface of t c ... | 1991 | 2019606 |
| structural changes in plasma membranes prepared from irradiated chinese hamster v79 cells as revealed by raman spectroscopy. | the effect of gamma irradiation on the integrity of plasma membranes isolated from chinese hamster v79 cells was investigated by raman spectroscopy. plasma membranes of control v79 cells show transitions between (-) 10 and 5 degrees c (low-temperature transition), 10 and 22 degrees c (middle-temperature transition), and 32 and 40 degrees c (high-temperature transition). irradiation (5 gy) alters these transitions markedly. first, the low-temperature transition shifts to higher temperature (onset ... | 1991 | 2020736 |
| the effect of hyperthermia on transmembrane potential in chinese hamster ovary cells in vitro. | the effect of elevated temperature on transmembrane potential was studied in chinese hamster ovary cells in vitro using tetraphenylphosphonium cation (tpp+) and 3,3'-dipentyloxacarbocyanine [di-o-c5(3)], two unrelated lipophilic cation probes that equilibrate across the plasma membrane according to the transmembrane potential. uptake of tpp+ was measured using a tritium-labeled probe and the uptake of the fluorescent probe di-o-c5(3) was measured by flow cytometry. the nernst equation was used t ... | 1991 | 2020742 |
| loss of the intrinsic heat resistance of human cells and changes in mr 70,000 heat shock protein expression in human x hamster hybrids. | since mammalian cells vary widely in their intrinsic thermoresistance, we have investigated the genetic basis underlying this phenomenon in human and rodent cell lines. typically, human cells are considerably more resistant to killing by heat than rodent cell lines. to determine whether the heat-resistant phenotype is dominant or recessive and to locate the chromosome(s) bearing determinants for heat resistance, we have prepared hybrids of heat-resistant human ht1080 cells and heat-sensitive chi ... | 1991 | 2021941 |
| effects of tamoxifen and protein kinase c inhibitors on hyperthermic cell killing. | the effects of the anti-estrogen, tamoxifen, and the protein kinase c inhibitor, 1-(5-isoquinolinylsulfonyl)2-methylpiperazine (h7), on hyperthermic cytotoxicity were studied. three cell lines were used, a human colon cancer cell line (ht-29), a human mammary carcinoma cell line (mcf-7), and chinese hamster v79 lung fibroblasts. with all three cell lines, tamoxifen at concentrations greater than 7.5 microm during heating or with a 3-hr exposure prior to heating significantly sensitized cells to ... | 1991 | 2022504 |
| a specific heterotypic cell adhesion activity between members of carcinoembryonic antigen family, w272 and nca, is mediated by n-domains. | the ca(2+)-independent homotypic and heterotypic cell adhesion activities of a carcinoembryonic antigen (cea) family member, w272 (cgm6), whose cdna has recently been isolated from libraries of human peripheral leukocytes of apparently normal subjects (arakawa, f., kuroki, mo., misumi, y., oikawa, s., nakazato, h., and matsuoka, y. (1990) biochem. biophys. res. commun. 166, 1063-1071) and spleen of chronic myelogenous leukemia patients (berling, b., kolbinger, f., grunert, f., thompson, j. a., b ... | 1991 | 2022629 |
| choriocarcinoma cells increase the number of differentiating human cytotrophoblasts through an in vitro interaction. | the human placenta arises from the zygote through single cell intermediates called cytotrophoblasts that in turn give rise to a syncytium. in culture, mononucleated cytotrophoblasts exhibit little, if any, cell division but are converted to multinucleated cells. choriocarcinoma, the malignant tumor of placenta trophoblast, comprises a mixed population of dividing cellular intermediates that resemble cytotrophoblasts but are less differentiated. because the choriocarcinoma intermediates arise fro ... | 1991 | 2022665 |
| membrane potential and amino acid transport in a mutant chinese hamster ovary cell line. | the bioenergetics of amino acid transport system a was studied in two chinese hamster ovary (cho) cell lines, the parent line cho-peot/1 and chy-1, a mutant of the former exhibiting a low activity of the same transport system. the steady-state transmembrane distribution ratio of the cationic amino acid l-arginine (rarg) was employed as an indicator of membrane potential (delta psi). evidence for the reliability of rarg to measure delta psi can be summarized as follows: (1) l-arginine transmembra ... | 1991 | 2022695 |
| recombinant human thyrotropin (tsh) receptor in a radioreceptor assay for the measurement of tsh receptor autoantibodies. | we studied the suitability of using the recombinant human tsh receptor expressed in chinese hamster ovary cells in a tsh binding inhibition (tbi) assay for autoantibodies against the tsh receptor. purified immunoglobulin g (igg) containing potent thyroid-stimulating immunoglobulin bioactivity competed for radiolabeled tsh binding to recombinant tsh receptor in parallel to inhibition by unlabeled tsh. using polyethylene glycol-prepared igg, this assay discriminated very well between sera from nor ... | 1991 | 2022709 |
| ionizing radiation and genetic risks. iii. nature of spontaneous and radiation-induced mutations in mammalian in vitro systems and mechanisms of induction of mutations by radiation. | this paper (1) presents an analysis of published data on the molecular nature of spontaneously arising and radiation-induced mutations in mammalian somatic cell systems and (2) examines whether the molecular nature and mechanisms of origin of radiation-induced mutations, in mammalian in vivo and in vitro systems, as currently understood, are consistent with expectations based on the biophysical and microdosimetric properties of ionizing radiation. depending on the test system (cho cells, human t ... | 1991 | 2023601 |
| sindbis virus infection of a chinese hamster ovary cell mutant defective in the acidification of endosomes. | sindbis virus infection of a chinese hamster ovary temperature-sensitive mutant cell line defective in its ability to acidify endosomes was examined to evaluate the importance of this step in the process of alphavirus penetration of host cells by measuring the time at which viral rna synthesis was initiated. we found that rna synthesis was initiated in these mutant cells at the same time after addition of virus at either permissive or nonpermissive temperature. we conclude that exposure to the a ... | 1991 | 2024467 |
| the glucose transport activity of glut1 is markedly decreased by substitution of a single amino acid with a different charge at residue 415. | glut1 glucose transporter cdna was modified to introduce a single amino acid substitution of aspartic acid for asparagine 415, which is conserved among all facilitative glucose transporter isoforms. although a significant amount of the mutated transporter was expressed into plasma membranes of chinese hamster ovary cells by transfection with expression vector, almost no increase in glucose transport activity was observed. analysis of glucose uptake with lineweaver-burk plot depicts that the muta ... | 1991 | 2025301 |
| background and peak evaluation of one parameter flow karyotypes on a pc/at computer. | flow cytometry has become a fast, quantitative method for the classification of metaphase chromosomes in suspension (flow karyotyping) stained with fluorescent dyes. such a flow karyotype (frequency distribution of the fluorescence signals) consists of several peaks. the peak pattern characterizes the analyzed chromosome complement. in many cases flow karyotypes contain a continuum of an unspecific background deriving from chromosome fragments or chromosome aggregates. for the quantitative evalu ... | 1991 | 2025602 |
| the pathway mediating insulin's effects on pyruvate dehydrogenase bypasses the insulin receptor tyrosine kinase. | the effect of insulin on pyruvate dehydrogenase activity was examined in two different cell types that over expressed either normal or defective human insulin receptors, rat 1 embryonic fibroblasts and chinese hamster ovary (cho) cells. insulin stimulated pyruvate dehydrogenase activity in cells that expressed normal insulin receptors (rat 1 hirc, and cho-wt and cho-t cells), or receptors in which lysine 1018 in the atp-binding site of the tyrosine kinase domain was exchanged for alanine (rat 1 ... | 1991 | 2026596 |
| protective effect of vitamin e against chromosomal aberrations and mutation induced by sodium chromate in chinese hamster v79 cells. | the effect of vitamin e on chromosomal aberrations and mutation caused by na2cro4 was investigated in chinese hamster v79 cells. pretreatment with 25 microm alpha-tocopherol succinate (vitamin e) for 24 h prior to chromate exposure (2.5-5 microm) resulted in a decrease of metal-induced chromosomal aberrations. na2cro4 (2.5-7.5 microm) induced mutations at the hgprt locus, but only within a very limited concentration range. this mutagenic response could also be suppressed by pretreatment with vit ... | 1991 | 2027337 |
| induction of mutation in v79 chinese hamster cells by tetrachlorohydroquinone, a metabolite of pentachlorophenol. | tetrachlorohydroquinone (tchq) and tetrachlorocatechol (tcc), two metabolites of the environmental mutagen and carcinogen pentachlorophenol, were tested without exogenous activation in v79 chinese hamster cells for the induction of mutation at the hypoxanthine phosphoribosyl transferase (hprt) locus to 6-thioguanine resistance (tgr) and at the na/k-atpase locus to ouabain resistance (ouar). treatment was for 24 h at 37 degrees c. tchq produced statistically significant increases in the frequency ... | 1991 | 2027344 |
| thiol-enhanced decomposition of mnng, enng, and nitrosocimetidine: relationship to mutagenicity in v79 chinese hamster cells. | the nitrosated form of cimetidine (tagamet), nitrosocimetidine (nc), belongs to a group of nitrosoamidines in which the mutagenic and carcinogenic properties of n-methyl-n'-nitro-n-nitrosoguanidine (mnng) and n-ethyl-n'-nitro-n-nitrosoguanidine (enng) have been studied in detail. the common mechanism of action of these compounds is that nucleophilic atoms can attack their iminocarbon, thereby leading to the formation of alkyldiazohydroxide and, subsequently of an alkylating and mutagenic diazoni ... | 1991 | 2029748 |
| assembly and disulfide rearrangement of recombinant surfactant protein a in vitro. | the surfactant-associated protein, protein a, produced by transgenic chinese hamster ovary cells exhibits a heterogeneous population of structures. electron microscopy reveals lollipop-shaped monomers consisting of a collagenous triple helix and a globular domain as well as oligomers in which two, three or more protomers are connected by their collagenous stalks. each protomer consists of three alpha-chains (36 kda) but under non-reducing conditions few free alpha-chains are observed by sds/page ... | 1991 | 2029908 |
| induction of chromosomal aberrations and sce by chloramphenicol. | the induction of chromosomal aberrations and sister-chromatid exchanges (sce) was studied in human lymphocyte cultures treated with chloramphenicol (cap), an antimicrobial agent acting by inhibiting protein synthesis. moreover chromosomal aberrations and sister-chromatid exchanges were studied in bone marrow cells of treated mice and in chinese hamster cell cultures (v79) respectively. while no aberrations were induced by short treatments in human lymphocytes exposed in g1 and g2 phases, high fr ... | 1991 | 2030703 |
| the effects of radon daughter alpha-particle irradiation in k1 and xrs-5 cho cell lines. | we investigated the radiobiological effects of the radon daughter bismuth-212 (212bi) in chinese hamster ovary (cho) k1 cells and in xrs-5 cells, which are x-ray sensitive and deficient in the ability to rejoin dna double-strand breaks. the cells were exposed to 250 kvp x-rays or to 212bi chelated to diethylene triamine pentaacetic acid (dtpa); chelation of 212bi to dtpa prevented its attachment to or entry into the cells. cytotoxic, clastogenic, and mutagenic responses of the cells were measure ... | 1991 | 2030713 |
| verapamil and cyclosporin a modulate doxorubicin toxicity by distinct mechanisms. | cyclosporin a has been reported to enhance the sensitivity of cells displaying multiple drug resistance to anthracyclines. however, the mechanism of action of cyclosporin a in modulating drug resistance is still controversial. this study compares the effects of cyclosporin a and verapamil on doxorubicin resistance in chinese hamster ovary cells (chrc5) using several criteria including in vitro cytotoxicity, drug accumulation, intracellular distribution by video microscopy, and nuclear dna damage ... | 1991 | 2032209 |
| activation of 5-[125i]iodonaphthyl-1-azide via excitation of fluorescent (n-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)) lipid analogs in living cells. a potential tool for identification of compartment-specific proteins and proteins involved in intracellular transport and metabolism of lipids. | we describe a new technique for analysis of proteins located near fluorescent lipid analogs in intact living cells using the membrane-permeant, photoactivatable probe, 5-[125i]iodonaphthyl-1-azide ([125i]ina). [125i] ina can be activated directly with uv light or indirectly through excitation of adjacent fluorophores (photosensitizers) with visible light to modify nearby proteins covalently with 125i. in this report we demonstrate that fluorescent phospholipids and sphingolipids containing n-(7- ... | 1991 | 2033068 |
| evidence supporting a passive role for the insulin receptor transmembrane domain in insulin-dependent signal transduction. | we previously have demonstrated that intramolecular interactions between alpha beta-alpha beta subunits are necessary for insulin-dependent activation of the protein kinase domain within a single alpha 2 beta 2 heterotetrameric insulin-receptor complex (wilden, p. a., morrison, b. d., and pessin, j. e. (1989) biochemistry 28, 785-792). to evaluate the role of the beta subunit transmembrane domain in the insulin-dependent signalling mechanism, mutant human insulin receptors containing a series of ... | 1991 | 2033070 |
| evidence for isopentenyladenine modification on a cell cycle-regulated protein. | we have prepared antibodies that recognize isopentenyladenosine (i6a), a modified nucleoside derived from mevalonic acid (mva). in immunoblot assays, affinity-purified anti-i6 a antibodies specifically bound to a 26-kda protein (i6a26) in chinese hamster ovary cells. anti-i6a recognition of i6a26 was blocked with i6a but not adenosine or isopentenol. employing immunoblot analysis we have quantitated the level of i6a26 in cells expressing various rates of dna synthesis. the cellular content of i6 ... | 1991 | 2033083 |
| production of antisera selective for m1 muscarinic receptors using fusion proteins: distribution of m1 receptors in rat brain. | a fragment of the cdna encoding the third intracellular loop of the rat m1 muscarinic receptor was cloned, and the dna was expressed in escherichia coli as a fusion protein. the fusion protein was purified and utilized as an antigen to raise a polyclonal antiserum in rabbits. chinese hamster ovary cells stably transfected with the cdna encoding each of the five known subtypes of muscarinic receptor were used as tissue sources to test the antiserum. the antiserum was found to quantitatively immun ... | 1991 | 2034236 |
| [the effect of prolonged gamma irradiation at a decreasing dose rate on survivability and gene mutation induction in cultured chinese hamster cells]. | continuous gamma irradiation at decreasing dose rate was shown to be less effective than acute exposure with regard to the lethal effect and frequency of mutations of resistance to 6-thioguanine in cultured chinese hamster cells. the cell population subjected to continuous irradiation was more radioresistant than the intact one. lethal and genetic effects of continuous irradiation at decreasing dose rate were mainly determined by the contribution of the radiation dose received during the first 2 ... | 2013 | 2034801 |
| mapping of human chromosome 22 with a panel of somatic cell hybrids. | the adenylosuccinate lyase (adsl) which is essential for generating adenylate, maps to the long arm of chromosome 22. by using a chinese hamster ovary cell line deficient in adsl activity, we have constructed a set of 17 somatic cell hybrids containing defined regions of human chromosome 22. this panel was extended with six additional hybrids, obtained in other laboratories using various methods of selection. southern analysis of the hybrids with 38 chromosome 22 probes defined 14 different subr ... | 1991 | 2037296 |
| high level expression of functional full length and truncated glucocorticoid receptor in chinese hamster ovary cells. demonstration of ligand-induced down-regulation of expressed receptor mrna and protein. | full length human glucocorticoid receptor and truncated receptor derivatives lacking the major amino-terminal trans-activating domain were expressed in stably transfected chinese hamster ovary (cho) cells. the receptors were co-expressed together with human metallothionein iia, and the expression levels were amplified in the presence of increasing concentrations of metal. in amplified cells, both synthesized receptor forms showed the expected molecular weights, as assayed by affinity labeling an ... | 1991 | 2037566 |
| biosynthesis of heparan sulfate. coordination of polymer-modification reactions in a chinese hamster ovary cell mutant defective in n-sulfotransferase. | a previous study identified a chinese hamster ovary cell mutant, pgse-606, which is defective in the n-sulfotransferase that catalyzes one of the initial polymer-modification reactions in the biosynthesis of heparan sulfate (bame, k. j., and esko, j. d. (1989) j. biol. chem. 264, 8059-8065). the structure of heparan sulfate generated by these cells reflects a 3-5-fold reduction in enzyme activity. the mutant produces heparan sulfate with half the content of n-sulfated glucosamine residues of tha ... | 1991 | 2037581 |
| cdna cloning and expression of platelet p24/cd9. evidence for a new family of multiple membrane-spanning proteins. | this study was designed to clone, sequence, and express the full-length cdna for the human platelet p24/cd9 antigen. a 1.3-kilobase cdna clone was identified that has an open reading frame encoding a mature protein of 228 amino acids (approximately 25,400 da) containing 10 cysteine residues and four putative transmembrane domains. the identity of the clone was confirmed by: (i) its predicted size, (ii) identity to four peptide sequences from the isolated protein including the nh2 terminus, and ( ... | 1991 | 2037603 |
| phosphorylation of hsp27 during development and decay of thermotolerance in chinese hamster cells. | the small molecular weight heat shock protein hsp27 was recently shown to confer a stable thermoresistant phenotype when expressed constitutively in mammalian cells after structural gene transfection. these results suggested that hsp27 may also play an important role in the development of thermotolerance, the transient ability to survive otherwise lethal heat exposure after a mild heat shock. in chinese hamster o23 cells increased thermoresistance is first detected at 2 h after a triggering trea ... | 1991 | 2037626 |
| co-culture systems for assessing the stability and genotoxicity of reactive 1,2-dibromo-3-chloropropane (dbcp) metabolites. | 1,2-dibromo-3-chloropropane (dbcp) induced dna damage, measured by alkaline elution, at low concentrations (5-10 microm) in suspensions of hepatocytes and testicular cells isolated from rats. at higher concentrations (greater than or equal to 100 microm) dbcp caused dna damage and increased the frequency of sister chromatid exchanges in chinese hamster v79 cells. when dbcp (2.5-10 microm) was tested for its ability to cause unscheduled dna synthesis (uds) in monolayers of liver cells isolated fr ... | 1991 | 2038269 |
| nitroreduction is not involved in the genotoxicity of 2-nitropropane in cultured mammalian cells. | we have investigated the importance of nitroreduction for the genotoxicity of the carcinogen 2-nitropropane (2-np) in primary cultures of rat hepatocytes and in v79 chinese hamster cells. induction of dna repair synthesis was used as an indicator of genotoxic effects in hepatocytes. genotoxicity in v79 cells was determined as induction of dna repair, micronuclei and mutations to 6-thioguanine (tg) resistance. both hepatocytes and v79 cells were found capable of reducing and oxidizing 2-np. reduc ... | 1991 | 2038276 |
| suppression of tumor formation in vivo by expression of the je gene in malignant cells. | the early growth response gene je encodes a monocyte chemoattractant, mcp-1. the je/mcp-1 protein attracts and stimulates human monocytes and induces monocyte-mediated inhibition of tumor cell growth in vitro. expression of human or murine je/mcp-1 in chinese hamster ovary (cho) cells completely suppressed their ability to form tumors in nude mice. coinjection of je/mcp-1-expressing cells with nonexpressing cho cells or with hela cells also prevented tumor formation. since je/mcp-1 expression ha ... | 1991 | 2038321 |
| demonstration by confocal microscopy that unliganded overexpressed glucocorticoid receptors are distributed in a nonrandom manner throughout all planes of the nucleus. | mouse glucocorticoid receptors (gr) that are over-expressed in chinese hamster ovary (cho) cells behave like progesterone receptors, in that the unliganded receptor localizes to the nucleus where it resides in a loosely bound docking complex, probably in association with the 90-kda heat shock protein (hsp90) and hsp70. in this paper we examine the localization of the overexpressed gr within the cho cell nucleus by confocal microscopy. in hormone-free cells the receptor distributes in a mottled p ... | 1991 | 2038343 |
| similarity between physicochemical properties of recombinant rat prorenin and native inactive renin. | rat prorenin was synthesized by chinese-hamster ovary cells transfected with an expression vector containing rat preprorenin cdna sequences, then purified by concanavalin a-sepharose chromatography and h.p.l.c. on g3000sw. the molecular mass of purified prorenin was 46,000 da, as determined by h.p.l.c. on g3000sw. immunoblot analysis indicated that recombinant prorenin cross-reacted with anti-(mature renin) antibody and two kinds of antibodies recognizing the n-terminus and c-terminus of the pro ... | 1991 | 2039449 |
| measuring cell proliferation by relative movement. i. introduction and in vitro studies. | this paper presents two new ways of analysing data which may be obtained from pulse labelling a population of cells with bromodeoxyuridine and analysing that population as a function of time with bivariate flow cytometry. the progression of cells is measured by the change in position in the cell cycle, as shown by a change in the mean dna content of the labelled and unlabelled cells. the particular measures of the mean dna content used are extensions of the relative movement of the labelled undi ... | 1991 | 2039802 |
| the effect of chemical radiation protectors on cell cycle progression after gamma or neutron irradiation. | the effects of two chemical radiation protectors, wr-1065 and wr-151326, were characterized in v79 chinese hamster cells after either cobalt-60 (60co) gamma or fission spectrum neutron irradiation. each protector was administered at a concentration of 4 mm to exponentially growing cultures for 30 min prior to and during irradiation with either 60co gamma or janus fission spectrum neutrons. after irradiation the cells were either plated immediately for survival or returned to the incubator and as ... | 1991 | 2039803 |
| cadmium-resistant chinese hamster v79 cells with decreased accumulation of cadmium. | cells resistant to 3 x 10(-5) m cdcl2 (cdr cells) were isolated from cultures of chinese hamster v79 cells by a procedure that involved stepwise increase in the concentration of cd2+ and subsequent mass selection. cdr cells grew as fast as wild-type cells (cds) in medium without cadmium. cdr cells were not cross-resistant to other divalent metal ions, such as hg2+, ni2+, pb2+, and zn2+. both cds and cdr cells induced similar levels of metallothioneins (mt) in response to zinc. depletion of gluta ... | 1991 | 2040025 |
| mutagenesis of cysteines in the hormone binding domain of the human estrogen receptor. alterations in binding and transcriptional activation by covalently and reversibly attaching ligands. | we have carried out experiments to determine the role of the cysteines in the hormone-binding domain (hbd) of the human estrogen receptor (er) in receptor function. in each mutant receptor, 1 of the 4 cysteines in the hbd (cysteines 381, 417, 447, and 530) was changed by in vitro mutagenesis of the er cdna (containing gly400) from cysteine to alanine; cys530 was also mutated to a serine. the mutant and wild-type receptor cdnas were expressed in chinese hamster ovary cells using an expression vec ... | 1991 | 2040605 |
| cycloheximide increases the thermostability of proteins in chinese hamster ovary cells. | protein denaturation resulting from temperatures between 42.0 degrees c and 50 degrees c has been observed and implicated as the lethal lesion for hyperthermic cell killing. a logical corollary is that protection against hyperthermic killing requires stabilization of cellular proteins against thermal denaturation. to test this, chinese hamster ovary cells were treated with the heat protector cycloheximide and then subjected to differential scanning calorimetry to measure protein denaturation. cy ... | 1991 | 2043141 |
| the importance of n- and o-linked oligosaccharides for the biosynthesis and in vitro and in vivo biologic activities of erythropoietin. | erythropoietin (epo) plays a critical role in stimulating the proliferation and differentiation of erythroid precursor cells. epo is heavily glycosylated with three asparagine (n)-linked tetraantennary oligosaccharides that may contain n-acetyl-lactosamine repeats and a single serine (o)-linked oligosaccharide. epo expressed in chinese hamster ovary cells exhibits biologic properties and amino acid and carbohydrate composition similar to natural urinary epo. the importance of the complex n-linke ... | 1991 | 2043765 |
| a new system for high-resolution dna sequence mapping interphase pronuclei. | cosmid clones containing human or hamster inserts have been hybridized in situ and localized with fluorescent reporter molecules in interphase nuclei (pronuclei) obtained after fusion of hamster eggs with either human or hamster sperm. hamster egg cytoplasm processes the tightly packaged sperm dna into large diffuse networks of chromatin fiber bundles, providing hybridization targets more extended than those available in somatic interphase cell nuclei. pronuclear physical distances between hybri ... | 1991 | 2045112 |
| chromosomal mapping of glutamate dehydrogenase gene sequences to mouse chromosomes 7 and 14. | glutamate dehydrogenase (glud) plays an important role in mammalian neuronal transmission. in human, glud is encoded by a small gene family. to determine whether defects in glud genes are associated with known neurological mutations in the mouse and to contribute to the comparative mapping of homologous genes in man and mouse, the chromosomal location of genes reactive with a mouse brain glud cdna were determined. genomic southern analysis of a well-characterized panel of chinese hamster x mouse ... | 1991 | 2045113 |
| the lethal effects of fermilab fast neutrons vary with the depth of cells in a water phantom. | using v79 chinese hamster lung fibroblast cells grown in culture we have examined the lethal effects of fast neutrons from the fermilab therapy facility as a function of depth in a water phantom. exposures and dosimetry were performed from 3 to 24 cm deep in the phantom along the central axis of the neutron beam, using various collimator configurations. the results indicate that the relative biological effect (rbe), using 60co gamma rays as the standard radiation, varies with depth in the neutro ... | 1991 | 2045307 |
| competitive inhibition of a set of endoplasmic reticulum protein genes (grp78, grp94, and erp72) retards cell growth and lowers viability after ionophore treatment. | grp78, a 78-kda protein localized in the endoplasmic reticulum (er), has been implicated in protein processing and stress protection. its promoter contains a 36-bp region which is conserved among grp genes across species and has the ability to compete for trans-acting factors mediating grp gene expression. integration of about 800 tandem copies of this sequence into the genome of a chinese hamster ovary cell line (dg44) results in transfectants with the following phenotypes: (i) the induction le ... | 1991 | 2046663 |
| influence of airborne suspended matter on mitotic cell division. | the effect of organic extracts of airborne suspended matter collected in the highly polluted industrial region of silesia (poland) on mitotic cell division was evaluated in the chinese hamster v79 cell line. crude benzene extracts as well as sequential elution solvent chromatography (sesc) fractions were investigated for their ability to affect the mitotic index, the proportion of anaphases-telophases to metaphases (at/m ratio), the cloning efficiency and to produce aneuploid cells. the incidenc ... | 1991 | 2046700 |
| 2,4-dichlorophenoxyacetic acid causes chromatin and chromosome abnormalities in plant cells and mutation in cultured mammalian cells. | the cytotoxic and mutagenic effects of the synthetic auxin 2,4-dichlorophenoxyacetic acid (2,4-d) on shallot root tip cells and on v79 chinese hamster fibroblast cells were examined and compared. in shallot root tips 2,4-d caused changes in mitotic activity, as well as changes in chromosome and chromatin structure, and also changes during the cell cycle. 2,4-d also showed mutagenic and cytotoxic effects on v79 cells in culture in concentrations higher than 10 micrograms/ml. the results in both s ... | 1991 | 2046706 |
| isolation of a human cdna encoding amidophosphoribosyltransferase and functional complementation of a cho ade-a mutant deficient in this activity. | we report here the isolation of a human cdna encoding the first step in de novo purine biosynthesis, amidophosphoribosyltransferase (prat). the human prat cdna was isolated by complementation of a saccharomyces cerevisiae ade4 mutant deficient in prat enzymatic activity. the identity of the isolated cdna, designated padea-3, was confirmed by several independent methods. genomic dna sequences homologous to padea-3 show coordinate segregation with the hypoxanthine nutritional requirement in chines ... | 1991 | 2047942 |
| an approach to imaging of living cell surface topography by scanning tunneling microscopy. | since a scanning tunneling microscope (stm) was developed, an observation of living cell surface has been one of the final aims in the biological application of stm. by developing a new style of stm which was combined with an optical microscope and with a novel system for the centering of both images, we successfully got the stm images of living cell surface of t24 cells (human bladder cancer cell line) and cho cells (chinese hamster ovary fibroblast) cultured on highly oriented pyrolytic graphi ... | 1991 | 2049086 |
| a sensitive method for measuring neutralizing antibodies to bordetella pertussis toxin: optimized adp-ribosylation of transducin. | pertussis toxin (pt), preactivated with 20 mm dithiothreitol (dtt), was incubated with different serum dilutions (1/10-1/200) before addition to the reaction mixture. final concentrations of the reagents were: pt (50 ng/ml), dithiothreitol (dtt)(less than or equal to 0.3 mm), bovine transducin (2 micrograms/ml), atp (1 mm). gtp (1 mm), lysophosphatidylcholine (ltc) (0.1 mg/ml), sodium acetate (naac) (0.1 m), tris-hcl, ph 7.1 (0.06 m) and 32p-nad+ (10 microci 28 ci/mm). the reaction was stopped b ... | 1991 | 2049177 |
| cloning and in vivo expression of the human gart gene using yeast artificial chromosomes. | two yeast artificial chromosomes (yacs) were isolated each with a full-length copy of the human gene that encodes the trifunctional protein containing phosphoribosylglycinamide synthetase (gars), phosphoribosylglycinamide formyltransferase (gart) and phosphoribosylaminoimidazole synthetase (airs). the yacs were characterized by restriction mapping and by in situ hybridization of cosmid subclones containing the yac ends to human metaphase chromosomes. one of the yacs contains co-cloned non-contig ... | 1991 | 2050105 |