different sensitivity of pseudomonas aeruginosa exotoxin a and diphtheria toxin to enzymes from polymorphonuclear leukocytes.we demonstrate that exotoxin a (exoa) of pseudomonas aeruginosa is one to two orders of magnitude more sensitive than diphtheria toxin (dt) of corynebacterium diphtheriae to lysosomal enzymes from polymorphonuclear leukocytes (pmn). it is especially sensitive to pmn elastase which inactivates its cell free enzymatic activity and its cytotoxicity as measured with the chinese hamster ovary cell assay and the rabbit skin test. sodium dodecyl sulphate polyacrylamide gel electrophoresis (sds-page) sh ...19892502701
carbohydrate structures of human tissue plasminogen activator expressed in chinese hamster ovary cells.recombinant human tissue plasminogen activator (rt-pa), produced by expression in chinese hamster ovary cells, is a fibrin-specific plasminogen activator which has been approved for clinical use in the treatment of myocardial infarction. in this study, the structures of the asn-linked oligosaccharides of chinese hamster ovary-expressed rt-pa have been elucidated. high mannose and hybrid oligosaccharides were released from the protein by endoglycosidase h digestion, whereas n-acetyllactosamine-ty ...19892503511
suppressing effect of tannic acid on the frequencies of mutagen-induced sister-chromatid exchanges in mammalian cells.the effects of tannic acid (m-galloyl gallic acid) and 7 of its analogues on the frequencies of sister-chromatid exchanges (sces) were investigated in cultured chinese hamster cells. sces induced by uv-light or mitomycin c (mmc) were suppressed by post-treatment with tannic acid and 5 of its analogues. these effects were independent of the extension of the cell cycle. the compounds which showed an sce-suppressing effect have a common structure of 3 neighboring hydroxy or methoxy groups substitut ...19892503717
adenylate cyclase toxins from bacillus anthracis and bordetella pertussis. different processes for interaction with and entry into target cells.adenylate cyclase (ac) toxins produced by bacillus anthracis and bordetella pertussis were compared for their ability to interact with and intoxicate chinese hamster ovary cells. at 30 degrees c, anthrax ac toxin exhibited a lag of 10 min for measurable camp accumulation that was not seen with pertussis ac toxin. this finding is consistent with previous data showing inhibition of anthrax ac toxin but not pertussis ac toxin entry by inhibitors of receptor-mediated endocytosis (gordon, v. m., lepp ...19892504710
purification and characterization of recombinant human interleukin 5 expressed in chinese hamster ovary cells.recombinant human interleukin 5 (rhil-5) expressed in chinese hamster ovary cells was purified and characterized. molecular heterogeneity was observed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. two major components of mr around 40,000 were detected under non-reducing conditions. however, under reducing conditions, the mr of rhil-5 was determined to be 22,000 and 20,000. after treatment with endoglycosidase f, a band with an apparent mr of 18,000 was observed. treatment of rhil ...19892506168
preferential modification of gc boxes by benzo[a]pyrene-7,8-diol-9,10-epoxide.the distribution of binding sites for the ultimate carcinogen anti-benzo[a]pyrene-7,8-diol-9,10-epoxide (bpde-l) in the 5' region of the chinese hamster ovary aprt gene has been determined. a plasmid (pgal) containing the entire hamster aprt gene including the 3' and 5' flanking regions was inserted into the bamhi site of the multiple cloning site of pgem so that the t7 promoter was 5' to the aprt gene. in vitro transcription of bpde-i-modified pgal, using the t7 rna polymerase, revealed two pro ...19892506885
effect of extracellular calcium concentration on the metabolism of polycyclic aromatic hydrocarbons by cultured mouse keratinocytes.cultures of adult mouse epidermal keratinocytes (meks) were utilized to determine whether the metabolism and metabolic activation of polycyclic aromatic hydrocarbons varied as a function of extracellular calcium (ca2+) concentration. meks grown in low ca2+-containing medium (0.05-0.10 mm) maintain basal cell morphology and proliferate while increasing the ca2+ concentration in the medium to 1.2-1.4 mm signals the cells to undergo terminal differentiation. relative to cultures of undifferentiated ...19892507130
intermolecular disulfide bonds are not required for the expression of the dimeric state and functional activity of the transferrin receptor.the human transferrin receptor is expressed as a disulfide-linked dimer at the cell surface. the sites of intermolecular disulfide bonds are cys-89 and cys-98. we have examined the functional significance of the covalent dimeric structure of the transferrin receptor by substitution of cys-89 and cys-98 with serine residues. wild-type and mutated transferrin receptors were expressed in chinese hamster ovary cells (clone tf-) that lack detectable endogenous transferrin receptors. the rates of rece ...19892507316
clostridium difficile toxin a. interactions with mucus and early sequential histopathologic effects in rabbit small intestine.clostridium difficile produces two toxins, a (enterotoxic) and b (cytopathic), that are implicated in the pathogenesis of pseudomembranous colitis. however, the relationship of the secretory effect and the early histopathologic events is still unclear. we examined the early histopathologic effect of purified c. difficile toxin a in rabbit ileal loops and correlated the mucosal damage with the secretory response. as early as 2 hours after inoculation, toxin a at 1.0 micrograms caused cytolysis of ...19892507823
cytogenetic response to 1,2-dicarbonyls and hydrogen peroxide in chinese hamster ovary auxb1 cells and human peripheral lymphocytes.mutagenic 1,2-dicarbonyls have been reported to occur in coffee and other beverages and in various foods. we have measured the induction of sister-chromatid exchanges (sces) and endoreduplicated cells (ercs) to determine the genotoxicity of various 1,2-dicarbonyl compounds in chinese hamster ovary (cho) auxb1 cells and human peripheral lymphocytes. the 1,2-dicarbonyls glyoxal, methylglyoxal and kethoxal each induced highly significant increases in both sces and ercs in auxb1 cells. glyoxal and k ...19892507914
expression of a human gene for polyamine transport in chinese-hamster ovary cells.a molecular-genetic approach towards isolating mammalian polyamine-transport genes and their encoded proteins was devised involving the production of chinese-hamster ovary (cho) cells expressing a human polyamine-transport protein. cho cells and a polyamine-transport-deficient cho mutant cell line (chomg) were equally sensitive to the antiproliferative effects of alpha-difluoromethylornithine (dfmo), which blocked endogenous polyamine synthesis. exposure to exogenous polyamines increased intrace ...19892512913
purification of active human plasminogen activator inhibitor 1 from escherichia coli. comparison with natural and recombinant forms purified from eucaryotic cells.plasminogen activator inhibitor 1 (pai-1) inhibits both tissue-type plasminogen activator (tpa) and urokinase-type plasminogen activator (upa) and, therefore, is an important regulator of plasminogen activation. we have developed eucaryotic and procaryotic expression systems for pai-1 and characterized the recombinant glycosylated and non-glycosylated products, together with a non-recombinant natural control, produced in the histosarcoma cell line ht 1080. for eucaryotic expression, the pai-1 cd ...19892514093
n-glycosylation and in vitro enzymatic activity of human recombinant tissue plasminogen activator expressed in chinese hamster ovary cells and a murine cell probe the effects of n-glycosylation on the fibrin-dependent plasminogenolytic activity of tissue-type plasminogen activator (t-pa), we have expressed a human recombinant t-pa (rt-pa) gene in chinese hamster ovary (cho) cells and in a murine c127 cell line. the resulting rt-pa glycoproteins were isolated and their associated n-linked oligosaccharide structures determined by using a combination of high-resolution bio-gel p-4 gel filtration chromatography, sequential exoglycosidase digestion, a ...19892514793
non-clastogenicity in mouse bone marrow of fructose/lysine and other sugar/amino acid browning products with in vitro genotoxicity.heated sugar/amino acid reaction mixtures, known to contain products that are clastogenic and/or mutagenic to cells in vitro, were evaluated for clastogenic activity in mouse bone marrow using the erythrocyte micronucleus assay. heated (i.e. browned) fructose/lysine reaction mixtures were also evaluated in the salmonella his-reversion assay and the chinese hamster ovary (cho) cell chromosomal aberration assay to confirm and extend previous in vitro observations. significant mutagenicity of fruct ...19892515134
cross-resistance to the lipid-soluble antifolate trimetrexate in human carcinoma cells with the multidrug-resistant phenotype.we are studying mechanisms of resistance to hydrophilic and lipophilic antifolates in cultured mammalian cells. we determined the cytotoxicity of methotrexate and the lipid-soluble antifolate trimetrexate to various human carcinoma cells and their doxorubicin-resistant sublines. these multidrug-resistant cells were 17-fold to 26-fold more resistant to trimetrexate but as sensitive to methotrexate as their parental cells. verapamil and quinidine, which are known to modulate the degree of pleiotro ...19892521520
chinese hamster ovary cell adhesion to human platelet thrombospondin is dependent on cell surface heparan sulfate proteoglycan.thrombospondin is a 420-kd platelet alpha-granule glycoprotein that binds specifically to heparin. we examined adhesion to thrombospondin of cho k1 cells and three mutant cho lines with varying deficiencies in glycosaminoglycan (gag) synthesis. in an experiment in which the parent line (k1) had 78% adherence to thrombospondin adsorbed to tissue culture plastic, cho s745 cells, with less than 6% normal gag synthesis had 11% adherence. cho s677 cells, with decreased heparan sulfate proteoglycan bu ...19892522106
dna-mediated transformation of n-acetylglucosaminyltransferase i activity into an enzyme deficient cell line.n-acetylglucosaminyltransferase i (glcnac-ti) catalyzes the first reaction in the conversion of asn-linked cell surface oligosaccharides from a mannose-terminating structure to more complex carbohydrate structures. the mutant chinese hamster ovary (cho) cell line, lec1, is deficient in this enzyme and, therefore, shows increased sensitivity to the lectin, concanavalin a, which binds to the mannose-terminating oligosaccharides that accumulate on lec1 cell surface glycoproteins. spontaneous revert ...19892522770
evaluation of nitroimidazole hypoxic cell radiosensitizers in a human tumor cell line high in intracellular glutathione.five nitroimidazole hypoxic cell radiosensitizers were evaluated in a human lung adenocarcinoma cell line (a549) whose gsh level was 8-fold higher than chinese hamster v79 cells. one millimolar concentrations of misonidazole (miso), sr-2508, rsu-1164, rsu-1172, and ro-03-8799 sensitized hypoxic a549 cells to radiation, with ro-03-8799 giving the highest sensitizer enhancement ration (ser) (2.3). however, miso, sr-2508 and ro-03-8799 were less effective in this cell line than in v79 cells, presum ...19892522917
binding of heparan sulfate to type v collagen. a mechanism of cell-substrate adhesion.the functions and molecular interactions of type v collagen in the pericellular matrix are unclear. our studies show that type v collagen adsorbed on a surface binds heparin/heparan sulfate with apparent higher affinity than do collagen types i, ii, iii, iv, or vi, fibronectin, or laminin. therefore, heparin-like molecules may mediate interactions between cells and type v collagen. hence, type v collagen may act as an anchor for proteoglycans in the extracellular matrix and function as a substra ...19892524477
enhanced o6-methylguanine-dna methyltransferase activity in transgenic mice containing an integrated e. coli ada repair gene.the e. coli ada gene encodes o6-methylguanine dna methyltransferase (o6mtase) which repairs the methylation of guanine at the o6 position in dna. after recombination with a chinese hamster metallothionein i gene promoter, the ada gene was microinjected into c3h/hen mouse zygotes. eventually, transgenic mice containing the ada fusion dna were generated. the integrated ada dna complex was transmitted to the progeny in a mode conforming to tandem integration at a single chromosome site, and homozyg ...19892530449
transfection of a human gene that corrects the lec1 glycosylation defect: evidence for transfer of the structural gene for n-acetylglucosaminyltransferase i.chinese hamster ovary (cho) glycosylation mutants provide an approach to cloning mammalian glycosyltransferases by transfection and gene rescue. in this paper, complementation of the lec1 cho mutation by human dna is described. lec1 transfectants expressed human n-acetylglucosaminyltransferase i (glcnac-ti) activity and possessed common human dna fragments. cloning of glcnac-ti should therefore be possible.19892531285
chinese hamster ovary cells deficient in n-acetylglucosaminyltransferase i activity are resistant to entamoeba histolytica-mediated study the relationship between carbohydrate-specific amebic cytoadherence and ameba-mediated cytotoxicity, we measured entamoeba histolytica trophozoite-mediated cytolysis directed against a panel of four chinese hamster ovary (cho) cell lines that have defined alterations in their glycosylation patterns. we recently measured amebic trophozoite adherence to this panel of cho cells and showed that trophozoites bind variant cells (ricr 15b), which are deficient in asn-linked n-acetyllactosamine ...19892535835
ability of mammalian fibroblasts to grow in synthetic medium containing neither serum nor exogenously added macromolecules.rous sarcoma virus transformed chinese hamster fibroblasts, clone chr1-3, were established at high temperature, then subcloned. six subclones with round and flat morphology harboring undeleted and partially deleted rsv proviruses, respectively, were seeded into serum-free synthetic medium with no macromolecular additives, and maintained for 2 mo. one flat subclone no. 14, fully designated sfchr1-3.14 for its serum-free phenotype, was further propagated in the same medium. the cells grew exponent ...19892536651
a recb recc sbcb recj host prevents reca-independent deletions in recombinant cosmid dna propagated in escherichia coli.segments of dna are deleted from recombinant cosmid dnas with high frequency during propagation in standard reca escherichia coli hosts. an attempt has been made to derive an appropriate strain of e. coli, suitable for cosmid cloning, in which such deletions do not occur. we examined the effects of a series of host recombinational mutations on the deletion process, using six independent recombinant cosmids that carry inserts of mouse, chinese hamster, or human dna. various e. coli host cells car ...19892536671
site specificity of the chorionic gonadotropin n-linked oligosaccharides in signal transduction.the role of the human chorionic gonadotropin (hcg) n-linked oligosaccharides in receptor binding and signal transduction was analyzed using site-directed mutagenesis and transfection studies. hcg derivatives with alterations at individual glycosylation sites were expressed in chinese hamster ovary cells. receptor binding studies showed that absence of any or all of the hcg n-linked oligosaccharides had only a minor effect on the receptor affinity of the derivatives. similarly, absence of the n-l ...19892536708
subunit structure of the galactose and n-acetyl-d-galactosamine-inhibitable adherence lectin of entamoeba histolytica.the galactose and n-acetyl-d-galactosamine-inhibitable adherence lectin of entamoeba histolytica is a cell surface protein which mediates parasite adherence to human colonic mucus, colonic epithelial cells, and other target cells. the amebic lectin was purified in 100-micrograms quantities from detergent-solubilized trophozoites by monoclonal antibody affinity chromatography. the adherence lectin was purified 500-fold as judged by radioimmunoassay. the nonreduced lectin had a molecular mass of 2 ...19892536731
replication of adeno-associated virus in cells irradiated with uv light at 254 nm.irradiation of simian virus 40 (ori mutant)-transformed chinese hamster embryo cells (od4 line) with uv light induced a cellular capacity which supported a full cycle of helper-independent adeno-associated virus replication. monochromatic uv light at 254 nm was about 1,000-fold more effective than uv light at 313 nm, indicating that cellular nucleic acid is the primary chromophore in the uv-induced process leading to permissiveness for adeno-associated virus replication. the uv irradiation and t ...19892536816
reversion to normal phenotype induced by sv40 in a spontaneously transformed malignant chinese hamster cell using a selection procedure that excluded the transforming effect of sv40, reversions to several properties of normal phenotype were for the first time obtained in a transformed chinese hamster cell line after sv40 infection. the value of induction to recovery of contact inhibition was typical for sv40-induced reverse gene mutations. thirteen of 15 isolated revertant clones were t-antigen positive, thus synthesizing the product of viral oncogene. therefore, in the majority of clones reversion ...19892537138
activation of s6 kinase in astroglial cells by fgfa and fgfb.basic (b) and acidic (a) forms of the fibroblast growth factor (fgf) promoted a rapid increase of the cytosolic s6 kinase activity in astroglial cells. s6 kinase activity was maximal 10 min after addition of the factors to cell cultures and remained at this level for at least 30 min. half-activation of the enzyme was obtained with 3 ng/ml fgfa. heparin (100 micrograms/ml) potentiated the response to suboptimal concentrations of fgfa. this growth factor appeared to stimulate an astroglial s6 kina ...19892537162
mutagenicity and induction of sister chromatid exchange by optically active enantiomers of secondary butyl methanesulfonate.this report describes experiments in which a chiral alkyl methanesulfonate was used to investigate possible mechanisms by which alkylating agents cause their mutagenic, cytotoxic, and clastogenic effects. optically active enantiomers and the racemic mixture of 2-butyl methanesulfonate (2-bms) were cytotoxic and mutagenic in chinese hamster v79 cells and in as52 cells and mutagenic in salmonella typhimurium strains ta100 and ta1535 (without the addition of exogenous metabolizing systems). within ...19892537195
isolation of chinese hamster ovary cell lines temperature conditional for the cell-surface expression of integral membrane glycoproteins.a procedure is described to select mutants of chinese hamster ovary cells that are conditionally defective for the cell-surface expression of integral membrane glycoproteins, including the hemagglutinin (ha) of influenza virus. using a combination of cell sorting and biochemical screening, seven cell lines were obtained that express more cell-surface ha at 32 degrees c than at 39 degrees c. the production of infectious vesicular stomatitis virus, whose growth requires insertion of an integral me ...19892537314
ubiquitin mrna is a major stress-induced transcript in mammalian cells.ubiquitin mrna was found to be an abundant transcript which was induced by heat shock (hs), and certain other stresses in mammalian cells. in chinese hamster cells, the 2 major ubiquitin transcripts of 2.6 kb and 1.7 kb were induced coordinately, while a minor ubiquitin transcript of 0.8 kb was not induced; the response was similar in human cells with induction of the 2.5 kb ub c and 1.0 kb ub b transcripts. a representative ubiquitin cdna clone, isolated from a cdna library derived from hs-trea ...19892537950
overproduction of topoisomerase ii in an ataxia telangiectasia fibroblast cell line: comparison with a topoisomerase ii-overproducing hamster cell mutant.ataxia telangiectasia (at) cell lines are characterised by their hypersensitivity to ionizing radiation and bleomycin, and their failure to inhibit dna synthesis after dna damage. a recent report [singh et al. (1988) nucl. acids res. 16, 3919-3929] indicated that a reduction in topoisomerase ii (topo ii) activity was a feature of at lymphoblast cell lines. we have studied the possible role of dna topoisomerases in determining the phenotype of an at fibroblast cell line. at5biva cells are sensiti ...19892537956
mrna from ncb-20 cells encodes the n-methyl-d-aspartate/phencyclidine receptor: a xenopus oocyte expression study.the mouse neuroblastoma--chinese hamster brain hybrid cell line ncb-20 is the only clonal cell line in which binding studies indicate the presence of phencyclidine (pcp) receptors. we report here that xenopus oocytes injected with ncb-20 cell poly(a)+ rna express n-methyl-d-aspartate (nmda)-activated channels and that these channels include the pcp receptor site. in injected oocytes, nmda application evoked a partially desensitizing inward current that was potentiated by glycine, blocked by the ...19892537982
active oxygen contributes to the major part of chromosomal aberrations in v79 chinese hamster cells exposed to n-hydroxy-2-naphthylamine.n-hydroxy-2-naphthylamine (noh-2na), an active metabolite of human occupational bladder carcinogens, induced, in v79 chinese hamster cells, chromosomal aberrations which were suppressed in the presence of catalase and/or superoxide dismutase. the induction of the aberrations was more efficient in a more basic ph in parallel with the generation of hydrogen peroxide from noh-2na. the possible role of the oxidation product of noh-2na in the induction of the aberrations is discussed.19892538382
interactions of recombinant and platelet transforming growth factor-beta 1 precursor with the insulin-like growth factor ii/mannose 6-phosphate receptor.recombinant transforming growth factor (tgf)-beta 1 precursor was recently found to contain mannose 6-phosphate (purchio et al., 1988, j. biol. chem. 263, 14211-14215). in the present study, recombinant tgf-beta 1 precursor was shown to bind to the insulin-like growth factor (igf)-ii/mannose 6-phosphate (man6p) receptor on the plasma membrane of cells since: 1) insulin, which induces an increase in cell surface igf-ii/man6p receptors on adipocytes, caused a 2.7-fold increase in tgf-beta 1 precur ...19892540751
radiofrequency radiation-induced calcium ion efflux enhancement from human and other neuroblastoma cells in test the generality of radiofrequency radiation-induced changes in 45ca2+ efflux from avian and feline brain tissues, human neuroblastoma cells were exposed to electromagnetic radiation at 147 mhz, amplitude-modulated (am) at 16 hz, at specific absorption rates (sar) of 0.1, 0.05, 0.01, 0.005, 0.001, and 0.0005 w/kg. significant 45ca2+ efflux was obtained at sar values of 0.05 and 0.005 w/kg. enhanced efflux at 0.05 w/kg peaked at the 13-16 hz and at the 57.5-60 hz modulation ranges. a chines ...19892540756
inhibition of carcinogen-inducible dna amplification in a simian virus 40-transformed hamster cell line by ethacridine or ethanol.dna amplification as a mechanism to increase gene expression has been established as a cause of cytotoxic drug resistance and appears to play a role in tumor cell progression. in order to investigate factors which control the process of dna amplification we have been using a simian virus 40 (sv40)-transformed chinese hamster cell line (co60) as a model system. this cell line can be induced to amplify integrated viral dna with a variety of agents. in this report the following is shown. (a) additi ...19892540904
uv mutagenesis, cytotoxicity and split-dose recovery in a human-cho cell hybrid having intermediate (6-4) photoproduct repair.somatic cell hybrids constructed between uv-hypersensitive chinese hamster ovary cell line uv20 and human lymphocytes were used to examine the influence of a human dna repair gene, ercc1, on uv photoproduct repair, mutability at several drug-resistance loci, uv cytotoxicity and uv split-dose recovery. in hybrid cell line 20hl21-4, which contains human chromosome 19, uv-induced mutagenesis at the aprt, hprt and na+/k+-atpase loci was comparable to that in repair-proficient cho aa8 cells, whereas ...19892541332
determinants for thermoinducible cell binding and plasmid-encoded cellular penetration detected in the absence of the yersinia pseudotuberculosis invasin protein.yersinia pseudotuberculosis inv mutants were analyzed for their ability to bind and penetrate mammalian cell lines. strains defective for the production of invasin and cured of the yersinia virulence plasmid pib1 were extremely defective for entry into the hep-2 cell line. inv strains harboring the virulence plasmid partially overcame this defect, indicating that the virulence plasmid mediates an invasin-independent pathway for low-level entry into cultured cells. plasmid-cured inv mutants were ...19892543628
characterization of cell surface carbohydrate receptors for entamoeba histolytica adherence lectin.binding and cytolysis of chinese hamster ovary (cho) cells by entamoeba histolytica trophozoites is inhibitable by galactose (gal) or n-acetyl-d-galactosamine (galnac). to better define the carbohydrate receptor for e. histolytica, we compared the binding and cytolytic target properties of 10 cho glycosylation mutants. each mutant expresses a uniquely altered array of n- and/or o-linked cell surface carbohydrates. amebic adherence was reduced when lactosamine-containing n-linked carbohydrates we ...19892543634
mechanism of phosphorylation of the epidermal growth factor receptor at threonine 669.the major site of phosphorylation of the epidermal growth factor (egf) receptor after treatment of cells with egf is threonine 669. phosphorylation of this site is also associated with the transmodulation of the egf receptor caused by platelet-derived growth factor and phorbol ester. a distinctive feature of the primary sequence surrounding threonine 669 is the proximity of 2 proline residues (-pro-leu-thr669-pro-). this site is not a substrate for phosphorylation by protein kinase c. to investi ...19892543683
increased glucose transport by human fibroblasts with a heritable defect in insulin binding.insulin and igf-i binding and their regulation of hexose transport were evaluated in skin fibroblasts cultured from a family (atl) whose proband had leprechaunism, hypoglycemia, and severe insulin resistance. high affinity insulin binding to proband atl cells was absent, and partially, but equally, impaired in fibroblasts from his related parents. igf-i binding to his cultured fibroblasts was within the normal range. cells from proband atl had insulin receptor mrnas similar to control fibroblast ...19892544784
a role for the insulin-like growth factor ii/mannose-6-phosphate receptor in the insulin-induced inhibition of protein catabolism.insulin and insulin-like growth factor (igf)-i inhibit intracellular protein degradation in a variety of different cell types. in the present studies, the igf-i-induced inhibition of protein metabolism in chinese hamster ovary (cho) cells was found to be blocked by polyclonal antibodies to the igf-ii/mannose-6-phosphate phosphate (man-6-p) receptor, but not by control immunoglobulin. in contrast, these antibodies had no effect on the ability of igf-i to stimulate glucose uptake in the same cells ...19892544802
human diabetes associated with a mutation in the tyrosine kinase domain of the insulin receptor.insulin receptor complementary dna has been cloned from an insulin-resistant individual whose receptors have impaired tyrosine protein kinase activity. one of this individual's alleles has a mutation in which valine is substituted for gly996, the third glycine in the conserved gly-x-gly-x-x-gly motif in the putative binding site fo adenosine triphosphate. expression of the mutant receptor by transfection into chinese hamster ovary cells confirmed that the mutation impairs tyrosine kinase activit ...19892544998
[a quantitative change in topoisomerase type i in the cell cycle of chinese hamster fibroblasts]. 19892545429
dna amplification in genetic toxicology.chemical compounds can cause amplification of specific dna sequences. dna amplification may result in an enhanced production of gene products which help cells to cope with the chemicals. this may lead to a resistance of the cells toward the agent. additionally, initiation of transformation or progression of transformed cells to tumorigenicity may also involve dna amplification. therefore, it is of interest to study the potential of chemicals to induce dna amplification. this report focuses on th ...19892546072
highly inducible expression from vectors containing multiple gre's in cho cells overexpressing the glucocorticoid receptor.a conditional glucocorticoid-responsive expression vector system is described for highly inducible expression of heterologous genes in mammalian cells. this host-vector system requires high level expression of the glucocorticoid receptor (gr) protein in the host cell and multiple copies of the receptor binding site within the expression vector. transfection and selection of chinese hamster ovary cells with expression vectors encoding the rat gr yielded cell lines which express functional recepto ...19892546123
a b-type pdgf receptor lacking most of the intracellular domain escapes degradation after ligand binding.the characteristics of the human b-type platelet-derived-growth-factor (pdgf) receptor expressed in chinese hamster ovary (cho) cells, were compared with those of a mutant receptor lacking all but 19 amino acids of the intracellular domain. the transfected wild-type receptor was synthesized as a 160-kda precursor that was processed to 190 kda. each cho cell expressed 30,000-100,000 receptors which bound pdgf-bb with a kd of about 0.5 nm. analysis of pdgf-ab binding yielded non-linear scatchard p ...19892546765
reconstitution of epidermal growth factor receptor transmodulation by platelet-derived growth factor in chinese hamster ovary cells.platelet-derived growth factor (pdgf) causes an acute decrease in the high affinity binding of epidermal growth factor (egf) to cell surface receptors and an increase in the phosphorylation state of the egf receptor at threonine654. the hypothesis that pdgf action to regulate the egf receptor is mediated by the activation of protein kinase c and the subsequent phosphorylation of egf receptor threonine654 was tested. the human receptors for pdgf and egf were expressed in chinese hamster ovary cel ...19892547770
endothelin-induced increases in vascular smooth muscle ca2+ do not depend on dihydropyridine-sensitive ca2+ channels.endothelin is a potent mammalian vasoconstrictive peptide with structural homology to cation channel-binding insect toxins. we tested the proposal that this peptide directly activates dihydropyridine-sensitive ca2+ channels in cultured vascular smooth muscle (vsm) cells. first, we found that cell ca2+ can be altered in vsm by activation of voltage-operated ca2+ channels. kcl-induced depolarization and the dihydropyridine ca2+ channel agonist (-) bay k 8644 (10 microm) both raised cell ca2+ more ...19892547835
induction of chromosomal aberrations in cho cells by restriction endonucleases: effects of blunt- and cohesive-ended double-strand breaks in cells treated by 'pellet' recent reports it has been suggested that restriction endonucleases (re) producing cohesive-ended double-strand breaks (dsb), are of comparable effectiveness to those producing blunt-ended dsb in causing chromosomal aberrations (ca) in mammalian cells. in several of these reports, trypsinized cells or suspension cultures were treated as cell 'pellets' in small volumes containing re and storage buffers. in this study we have examined this by comparing 2 'pellet' methods in which trypsinized ch ...19892548092
mutational specificity studies of endogenous mammalian cell loci: methodological aspects.we report here the details of a modified cloning method first described by seed et al. (1983) for use in an extensive study of mutational specificity at the aprt locus of chinese hamster ovary cells. the technology depends on homologous recombination between a suppressor probe plasmid and the desired insert in a genomic library constructed in a double amber mutant bacteriophage lambda vector. recombinant phage form blue plaques on a non-suppressor, lacz amber host. we have determined the sensiti ...19892548093
effect of combinations of antioxidants on phagocyte-induced sister-chromatid exchanges.combinations of oxygen radical scavengers and antioxidants significantly reduced the number of sister-chromatid exchanges in chinese hamster ovary cells exposed to human phagocytes stimulated to generate oxygen radicals. when vitamin e was combined with these antioxidants, no increase in sister-chromatid exchanges was observed compared to controls.19892549410
h4iiec3 rat hepatoma cells activate n-nitrosodimethylamine but are resistant to the genotoxic products.exposure of the differentiated rat hepatoma cells h4iiec3 (h4) or several of their subclones to 20 mm n-nitrosodimethylamine (ndma) did not significantly increase the number of 6-thioguanine (tg)-resistant cells or of micronuclei. similar results were obtained with h4 cells pretreated with isopropanol, an inducer of the ndma-metabolizing cytochrome p450 form. however, when h4 cells were co-cultured with v79 chinese hamster cells, which are incapable of activating ndma, exposure to the nitrosamin ...19892550724
high-efficiency expression of mammalian beta-adrenergic receptors in baculovirus-infected insect cells.infection of a clonal isolate of spodoptera frugiperda cells (sf9) with a baculovirus expression vector harboring the cdna encoding the beta-adrenergic receptor resulted in a high efficiency expression. at 48 hr post-infection, the level of expression of beta-adrenergic receptors was approximately 12 million/cell. specific activities of crude lysates of infected sf9 cells were approximately 30 pmol/mg of protein, 5-fold greater than those of membranes of high-expressor chinese hamster ovary cell ...19892551283
expression and characterization of calmodulin-dependent protein kinase ii from cloned cdnas in chinese hamster ovary cells.cdnas containing the entire coding regions of the alpha and beta subunits of calmodulin-dependent protein kinase ii (cam kinase ii) were isolated from a rat cerebrum cdna library, ligated into an expression vector under the control of sv40 early promoter and introduced into chinese hamster ovary (cho) cells. to investigate the role of the alpha and beta subunits and their functional domains in cam kinase ii activity, the properties of the kinases expressed in the transfected cells were studied. ...19892553731
beta-galactosidase overexpression in sv40-transformed chinese hamster fibroblasts exposed to mutagens as a result of amplification of transfected bacterial lacz dna sequences.genetic constructions in which the bacterial lacz gene, encoding the enzyme beta-galactosidase, is fused to a viral (sv40) origin of replication have been introduced in an sv40-transformed hamster cell line (c1102). we have studied in detail 3 clones in which beta-galactosidase-specific activity increases after treatment with genotoxic agents. we show that this increase is dependent on the activity of the viral t protein and correlates with an amplification of lac sequences. this system provides ...19892554137
pertussis holotoxoid formed in vitro with a genetically deactivated s1 subunit.the cytotoxicity of pertussis toxin, a multisubunit exotoxin produced by bordetella pertussis, is believed to be due to the adp-ribosyltransferase activity of the s1 subunit. we have previously described the recombinant expression of each of the five individual pertussis toxin subunits in escherichia coli and the production of an enzymatically deficient form of the s1 subunit by site-directed mutagenesis. we now report the in vitro assembly of holotoxin from native pertussis toxin b oligomer and ...19892554311
human ornithine decarboxylase(odc)-encoding gene: cloning and expression in odc-deficient cho cells.we have cloned a full-length human ornithine decarboxylase (odc)-encoding gene from a genomic library of human myeloma cells which overproduce odc due to a selective gene amplification. correct expression of the cloned gene was assessed by transfecting it into a chinese hamster ovary (cho) cell mutant devoid of odc activity. transfection with a 10-kb bamhi dna fragment of the genomic clone, conferred odc activity to the recipient cells and relieved them of dependence on exogenous polyamines for ...19892556329
indirect immunofluorescence localization of beta-adrenergic receptors and g-proteins in human a431 cells.polyclonal antibodies directed against (i) rodent lung beta 2-adrenergic receptor, (ii) a synthetic fragment of an extracellular domain of the receptor, and (iii) human placenta g-protein beta-subunits, were used to localize these antigens in situ in intact and permeabilized human epidermoid carcinoma a431 cells. antibodies directed against beta 2-adrenergic receptors showed a punctate immunofluorescence staining throughout the cell surface of fixed intact cells. punctate staining was also obser ...19892556996
functional expression of the calcium release channel from skeletal muscle ryanodine receptor cdna.combined patch-clamp and fura-2 measurements were performed to study the calcium release properties of chinese hamster ovary (cho) cells transfected with the rabbit skeletal muscle ryanodine receptor cdna carried by an expression vector. both caffeine (1-50 mm) and ryanodine (100 microm) induced release of calcium from intracellular stores of transformed cho cells but not from control (non-transfected) cho cells. the calcium responses to caffeine and ryanodine closely resembled those commonly ob ...19892557244
site-directed mutagenesis of m1 muscarinic acetylcholine receptors: conserved aspartic acids play important roles in receptor function.muscarinic acetylcholine receptors contain a region encompassing the second and third transmembrane domains that is rich in conserved aspartic acid residues. to investigate the role of four conserved aspartic acids at positions 71, 99, 105, and 122 in muscarinic receptor function, point mutations in the rat m1 muscarinic receptor gene were made that converted each asp to asn, and wild type or mutant genes were stably expressed in chinese hamster ovary cells that normally lack muscarinic receptor ...19892557534
free radicals induced by adriamycin-sensitive and adriamycin-resistant cells: a spin-trapping study.the radicals generated by adriamycin-sensitive (cho-ab) and adriamycin-resistant (cho-c5) chinese hamster ovary cells as well as by adriamycin-sensitive and -resistant human breast cancer cells (mcf7-wt and mcf7-adr) have been studied with spin-trapping and esr spectroscopy. during anoxic exposure to adriamycin (adr) both pairs of cell lines produced the broad esr singlet characteristic of adr semiquinone (aq.). by use of tris(oxalato)chromate (crox) as an extracellular line-broadening agent, th ...19892557905
the chromosome 11 region flanking the t(11;14) breakpoint in human t-all is deleted in wilms' tumor hybrids.human chromosomal band 11p13 has been implicated in t cell malignancies carrying t(11;14)(p13;q11) reciprocal translocations and has also been associated with wilms' tumor and aniridia in a mechanism characterized by overlapping hemizygous constitutional deletions spanning this region. using probes derived from the t cell receptor delta gene, we have cloned the chromosomal breakpoint in an acute t cell leukemia (t-all). southern blotting analyses of mouse-human somatic cell hybrids from this hum ...19892558334
molecular cloning, sequence and functional expression of the cdna for the human thyrotropin receptor.we screened a human thyroid cdna library with two synthetic oligonucleotides based on the reported amino acid sequence of the 3rd and 4th transmembrane domains of a putative human tsh receptor and related receptors. the nucleotide sequence of a 4 kb clone revealed an open reading frame of 764 amino acids (86,816 daltons) with a putative signal peptide, seven transmembrane domains, five potential glycosylation sites, and a very short intracytoplasmic region. homology with the extracellular domain ...19892558651
immunochemical localization of amiloride-sensitive sodium channels in sodium-transporting epithelia.the localization of amiloride-sensitive na+ channels in na+-transporting epithelia was examined using antibodies made against amiloride-binding na+ channel protein purified from bovine kidney. the distribution of the channel protein was determined in thick frozen sections at the light-microscopic level using indirect immunofluorescence, and at the electron-microscopic level using immunogold labelling. in the cells of both the intact bovine collecting tubule and a6 confluent monolayers, only the ...19892559094
nucleotide ectoenzyme activities of human and chinese hamster fibroblasts in tissue culture.we have previously assigned human ecto-5'-nucleotidase (nt) to chromosome 6 on the basis of conversion of exogenously supplied [14c]amp to adenosine by whole cells of human and chinese hamster hybrids carrying chromosome 6. in this paper we demonstrate that the activity on human mrc-5 fibroblasts is typical of previously described and purified ecto-5'-nucleotidases. in contrast to mrc-5 cells, chinese hamster v79a2 cells weakly express an ampase activity that is not nt. the cytosolic form of nt ...19892560629
expression of recombinant human choriogonadotropin in chinese hamster ovary glycosylation mutants.human cg, a member of the glycoprotein hormone family that includes lh, fsh, and tsh, is composed of two nonidentical subunits each containing two asparagine linked (n-linked) oligosaccharides. the role of the oligosaccharides in the action of these hormones is unclear. to examine the structure-activity relationships of the glycoprotein hormone oligosaccharides using nonenzymatic and nonchemical methods, we transfected cg subunit genes into mutant cell lines derived from chinese hamster ovary ce ...19892560807
erythropoietin: biology and clinical cell production in vertebrates is controlled by a glycoprotein hormone known as erythropoietin (ep), which is produced by the kidney in response to hypoxia and acts on the marrow to selectively stimulate erythropoiesis. the gene for ep has recently been cloned, and highly pure recombinant human ep (rhuep) is now available in considerable quantity. this has led to a better understanding of many aspects of ep biology and to clinical trials in humans. the amino acid sequence of ep is now comple ...19892561121
fibroblast growth factor potentiates receptor- and nonreceptor-mediated stimulation of adenylate cyclase in hamster fibroblasts.basic fibroblast growth factor (fgf) has no effect alone on the basal camp synthesis in chinese hamster fibroblasts (ccl39) but it potentiates (by up to 50%) the stimulation of adenylate cyclase by prostaglandin e1, cholera toxin or forskolin. this potentiating effect is not abolished by pretreatment of the cells with pertussis toxin, which indicates that it is not due to the withdrawal of a tonic inhibition of adenylate cyclase by the pertussis toxin-sensitive inhibitory gtp-binding protein (gi ...19892561914
[constitutive expression of human fibroblast interferon gene controlled by sv40 early promoter in cho cells].hindii fragment encoding human fibroblast interferon (ifn beta) gene coding sequence was fused at 60 bp downstream from the rna start site of sv40 early gene to be a constitutive expression plasmid psve beta. this recombinant plasmid was transfected into the dihydrofolate reductase (dhfr)-deficient chinese hamster ovary (cho) cells together with a selectable dhfr gene. about half of transformants continuously secreted ifn beta into the supernatant without inducement. one of the subclone transfor ...19892562075
mapping of the gene encoding the multifunctional protein carrying out the first three steps of pyrimidine biosynthesis to human chromosome 2.the cad gene encodes a trifunctional protein that carries the activities of the first three enzymes (carbamyl phosphate synthetase ii, aspartate transcarbamylase, and dihydroorotase) of de novo pyrimidine biosynthesis. genomic fragments of the human cad gene have been obtained by screening a human genomic library in bacteriophage lambda using a syrian hamster cdna clone as a probe. these human genomic clones have been used to assign the cad gene to human chromosome 2 using in situ hybridization ...19892565865
detection of dna damage in cells exposed to ionizing radiation by use of anti-single-stranded dna monoclonal immunochemical method has been developed for quantitative detection of dna damage in mammalian cells. the method is based on the binding of a monoclonal antibody to single-stranded dna. the clone producing this antibody (d1b) was obtained as a by-product from fusion of mouse myeloma cells with spleen cells isolated from a mouse immunized with chemically modified dna. the technique is based upon the determination of the percentage single-strandedness resulting from the time-dependent partial u ...19892565936
dna damage and repair in rodent and human cells after exposure to janus fission spectrum neutrons: a minor fraction of single-strand breaks as revealed by alkaline elution is refractory to repair.we have examined the induction and repair of breaks induced in the dna of chinese hamster v79 and human p3 epithelial teratocarcinoma cells by janus fission-spectrum neutrons (mean energy 0.85 mev) and 60co gamma radiation in the biological dose range, using alkaline filter elution methods. fission-spectrum neutrons induce fewer immediate single-strand breaks (ssb) per gray of absorbed dose than do gamma rays, as measured by alkaline elution methods. previous survival measurements have indicated ...19892565937
characterization of monoclonal antibodies recognizing a mr 180,000 p-glycoprotein: differential expression of the mr 180,000 and mr 170,000 p-glycoproteins in multidrug-resistant human tumor cells.p-glycoprotein is a plasma membrane protein believed to mediate resistance to natural product drugs such as vincristine, adriamycin, and actinomycin d. to facilitate the study of human p-glycoprotein, monoclonal antibodies (designated hyb-612, hyb-241, and hyb-195) were raised against vincristine-resistant human neuroblastoma (sh-sy5y/vcr) cells. the antibodies recognize a mr 180,000 plasma membrane phosphoglycoprotein produced in increased amounts in sh-sy5y/vcr as well as in vincristine-resist ...19892566379
a region in the coding sequence is required for high-level expression of murine histone h3 gene.replication-dependent histone genes are expressed at high rates in s phase to provide the histone proteins required for chromosomal replication. two genes, an h2a and h3 gene, located on chromosome 3 in the mouse and cloned together in a single 3-kilobase (plasmid mm614) restriction fragment are highly expressed. by transfecting mouse histone gene constructs into chinese hamster ovary cells, we have identified a 110-nucleotide region within the coding sequence of the h3.2-614 gene that is requir ...19892567515
cloning, sequence analysis, and permanent expression of a human alpha 2-adrenergic receptor in chinese hamster ovary cells. evidence for independent pathways of receptor coupling to adenylate cyclase attenuation and activation.the gene encoding a human alpha 2-adrenergic receptor was isolated from a human genomic dna library using a 367-base pair fragment of drosophila genomic dna that exhibited 54% identity with the human beta 2-adrenergic receptor and 57% identity with the human alpha 2-adrenergic receptor. the nucleotide sequence of a fragment containing the human alpha 2-receptor gene and 2.076 kilobases of untranslated 5' sequence was determined, and potential upstream regulatory regions were identified. this gen ...19892568356
molecular cloning of a chinese hamster mitochondrial protein related to the "chaperonin" family of bacterial and plant proteins.the complete cdna sequence of a mitochondrial protein from chinese hamster ovary cells, designated p1, which was originally identified as a microtubule-related protein (gupta, r.s., ho, t.k.w., moffat, m.r.k., and gupta, r. (1982) j. biol. chem. 257, 1071-1078), has been determined. the p1 cdna encodes a protein of 60,983 da including a 26-amino acid putative mitochondrial targeting sequence at its n-terminal end. the deduced amino acid sequence of chinese hamster p1 shows 97% identity to the hu ...19892568357
co-localization of glutamate and tubulin in putative excitatory neurons of the hippocampus and amygdala: an immunohistochemical study using monoclonal antibodies.tubulin and glutamate were immunohistochemically localized in the hippocampus and amygdala of rats using monoclonal antibodies to gamma-glu-glu (glu-1) and glutaraldehyde-fixed glutamate (glu-2), respectively. glu-2 was shown to be selectively immunoreactive for glutaraldehyde-fixed glu using enzyme-linked immunoassays and inhibition enzyme-linked immunoassays. glu-1 was immunoreactive with tubulin on immunoblots of brain homogenates. however, only tubulin with a glutamate carboxy-terminal appea ...19892568603
identification of p-glycoprotein in renal brush border membranes.a monoclonal antibody (c219) that recognizes the p-glycoprotein (mr = 170,000) in plasma membranes of multidrug-resistant chinese hamster ovary (cho) cell lines was used to assay renal brush border membrane (bbm) and basolateral membrane (blm) fractions for the presence of a cross-reactive polypeptide. the c219 antibody bound to a 155,000 dalton protein in immunoblots of rat bbm but not blm proteins resolved by sodium dodecyl sulfate gel electrophoresis. the corresponding human kidney bbm and do ...19892568833
the d17tu5 locus in the t complex: implications for the origin of t haplotypes and inbred strains.the mouse x chinese hamster cell line r4 4-1 contains only one mouse chromosome, the bulk of which corresponds to mus musculus chromosomes 17 and 18 (mmu17 and mmu18, respectively). a genomic library was prepared from the r4 4-1 dna, and a mouse clone was isolated from the library, which-with the help of somatic cell hybrids-could be mapped to the mmu17. a locus defined by a 2.7-kb long bam hi probe from this clone was designated d17tu5 (tu for tübingen). the locus proved to be polymorphic among ...19892569442
caffeine toxicity is inversely related to dna repair in simian virus 40-transformed xeroderma pigmentosum cells irradiated with ultraviolet light.human cells transformed by simian virus 40 (sv40) are more sensitive to killing by ultraviolet light when grown in caffeine after irradiation. the degree of sensitization at 2 mm caffeine (expressed as the ratio of the 37% survival dose for control cells divided by the 37% survival dose for cells grown in caffeine, i.e., the dose modification factor) was approximately 1.9 in transformed normal cells and 3.8-5.8 in excision-defective xeroderma pigmentosum (xp) groups a, c, and d cells. a large do ...19892570469
a novel ubiquitous protein 'chaperonin' supports the endosymbiotic origin of mitochondrion and plant chloroplast.the deduced amino acid sequences for a major mitochondrial protein (designated p1, related to the 'chaperonin' family of proteins) from human and chinese hamster cells show extensive similarity (greater than 60% identity observed over the entire length) with a related protein present in evolutionarily as divergent organisms as escherichia coli, coxiella burnetii, mycobacterium species, cyanobacteria as well as in yeast mitochondria and higher plant chloroplasts. of the different groups of bacter ...19892571331
multidrug resistance in a human leukemic cell line selected for resistance to trimetrexate.trimetrexate (tmq) is a lipophilic antifolate shown to have antitumor activity in humans. tmq-resistant sublines of the molt-3 human acute lymphoblastic leukemia cell line were developed and were designated as molt-3/tmq200, molt-3/tmq800, and molt-3/tmq2500 based on degrees of resistance to tmq. the tmq resistance was accompanied by 5- to 7-fold increases in dihydrofolate reductase activity and markedly reduced cellular tmq accumulation. methotrexate accumulation was not impaired in tmq-resista ...19892573416
sequence and chromosomal assignment of a novel cdna identified by immunoscreening of a thyroid expression library: similarity to a family of mitochondrial solute carrier immunoglobulin g (igg) preparation of the serum from a patient with active graves' disease was used to isolate cdna clones from a lambda gt11 cdna library of human thyroid follicular carcinoma tissue by immunoscreening. one of these clones, hml-7, is further characterized herein by sequencing, northern analysis, and chromosomal mapping. the clone reacted with igg preparations from the sera of 14 of 19 patients with active graves' disease but not with igg preparations from 11 normal individual ...19892575220
chromosomal localization to 3q21----qter and two taqi rflps of the human prostate-specific acid phosphatase gene (acpp).the chromosomal location of the gene encoding human prostate-specific acid phosphatase (acpp) was determined by southern blotting analysis of panels of human x rodent (mouse or chinese hamster) somatic cell hybrids, using the pap-1007 and pap-1004ep acpp cdna probes. the acpp gene was assigned to chromosome 3, which was confirmed by screening a chromosome 3-specific genomic library. sublocalization of this gene was carried out using hybrids that had retained only various portions of human chromo ...19892575485
monoclonal antibody against the centrosome.a monoclonal antibody, mpm-13, raised against mitotic hela cell extracts recognized a perinuclear area in interphase cells and spindle poles in mitotic cells of human, mouse, chinese hamster and sea urchin. on immunoblots mpm-13 recognized a major protein band at 43 x 10(3) mr and a variable minor band at 56 x 10(3) mr in both mitotic and interphase hela cells. these antigens were detectable in a variety of mammalian cells as well as in the unicellular ciliate tetrahymena. in cells arrested in m ...19892575618
molecular characterization of human minichromosomes in chinese hamster/human somatic cell hybrids. 19892576309
transforming growth factor type beta 3 maps to human chromosome 14, region q23-q24.type beta transforming growth factors (tgf-betas) are polypeptides that act hormonally to control the proliferation and differentiation of multiple cell types. recently, we reported the isolation of a cdna encoding a new member of this gene family, which we have termed tgf-beta 3. here we show by southern analysis using a human probe specific for tgf-beta 3, the presence of a related single copy gene in a wide range of animal species. chromosomal localization of the tgf-beta 3 gene was performed ...19882577876
a completely synthetic toxoid vaccine containing escherichia coli heat-stable toxin and antigenic determinants of the heat-labile toxin b subunit.the immunodeterminant regions of the escherichia coli heat-labile toxin b subunit were identified by determining the antigenicity, by using enzyme-linked immunosorbent assays, of synthetically produced peptides corresponding to various segments of its 124-amino-acid sequence. the addition of the 18-amino-acid sequence of heat-stable toxin (st) to some of these peptides enhanced their b subunit antigenicity. peptide residues containing the 26 amino acids of b subunit sequence 58 to 83 joined to t ...19852581899
two arylamine n-acetyltransferases from chicken pineal gland as identified by cdna cloning.a cdna library prepared from the poly(a)-rich rna of the chicken pineal gland obtained at night was screened with the 32p-labeled cdna of arylamine n-acetyltransferase from the chicken liver recently isolated in this laboratory. two positive clones (p-nat-3 and p-nat-10) that cross-hybridized with the liver cdna were isolated. the cdnas did not cross-hybridize each other under a high stringency, indicating that they corresponded to different mrnas. when the cdnas were inserted into an expression ...19892583181
[susceptibility of the chinese hamster (cricetulus griseus) to parasitic infection (3). experimental infection with hymenolepis nana or trichuris muris to the cortisone treated chinese hamster].susceptibility of chinese hamster (cricetulus griseus) of asahikawa colony (cha) to hymenolepis nana or trichuris muris infection was compared in the feces-egg examination with that of mice as the control animals. though cha were resistant to the infection of h. nana, they were found to become susceptible to h. nana by the treatment with cortisone. a half number of cha was infected with h. nana and the eggs were detected from each animal only in 4 or 6 days in the periods of examination more tha ...19892583668
the pattern of dihydrofolate reductase expression through the cell cycle in rodent and human cultured cells.we have examined the pattern of dihydrofolate reductase (dhfr) enzyme and mrna levels in cell cycle stage-specific populations obtained by centrifugal elutriation in chinese hamster ovary cells and in a derivative line in which the dihydrofolate reductase gene is amplified approximately 50-fold. on a per cell basis, we observed a 2-fold increase in dhfr activity as cells progressed from g1 to g2/m with a concomitant 2-fold increase in the rate of protein synthesis and steady state level of mrna. ...19892584230
high levels of expression of full length human pro-alpha 2(v) collagen cdna in pro-alpha 2(v)-deficient hamster cells.a full length cdna encoding human pro-alpha 2(v) collagen was constructed. partial sequencing of the cdna and primer extension analysis of mrna from fibroblasts found that pro-alpha 2(v) mrna differs from the mrnas of other fibrillar collagens in the increased length of its 5'-untranslated region. the pro-alpha 2(v) cdna was placed downstream of the human cytomegalovirus immediate early promoter/regulatory sequences for expression studies in cultured chinese hamster lung cells. these cells have ...19892584236
functional analysis of gc element binding and transcription in the hamster dihydrofolate reductase gene promoter.dihydrofolate reductase (dhfr) gene expression is required for cell growth. the dhfr gene promoter contains several gc elements capable of binding the transcription factor sp1. in this report we have characterized the effect of protein(s) binding to these sequence elements in the chinese hamster dhfr promoter on transcription. we have constructed a series of deletions containing from 896 to 103 bp 5' to the start of translation. the protein binding domains have been mapped by dnase i footprint a ...19892587257
new synthetic retinoids: effects on proliferation and differentiation.nine retinoid analogues were synthesized and their effects on cell proliferation and differentiation of tumor cell lines were analysed and compared with those of natural retinoids (retinoic acid, retinol, retinal). our results demonstrate differential inhibitory effects of the synthetic retinoids on cell growth. this inhibitory activity of the synthetic retinoids was, in some cases, higher than that of retinoic acid and retinol. natural and synthetic retinoids were found to be able to induce to ...19892589824
stable high level expression of human thyroid peroxidase in cultured chinese hamster ovary expression plasmid containing both human thyroid peroxidase and mouse dihydrofolate reductase cdnas was transfected into chinese hamster ovary cells. the stably transformed cells constitutively expressed immunoreactive thyroid peroxidase on the cell surface. these cells were further used to establish a subline producing a large amount of thyroid peroxidase by selecting clones resistant to methotrexate. the molecular weight of the expressed thyroid peroxidase was the same as purified human thy ...19892590201
complementation of repair gene mutations on the hemizygous chromosome 9 in cho: a third repair gene on human chromosome 19.a human dna repair gene, ercc2 (excision repair cross complementing 2), was assigned to human chromosome 19 using hybrid clone panels in two different procedures. one set of cell hybrids was constructed by selecting for functional complementation of the dna repair defect in mutant cho uv5 after fusion with human lymphocytes. in the second analysis, dnas from an independent hybrid panel were digested with restriction enzymes and analyzed by southern blot hybridization using dna probes for the thr ...19892591959
characterization of recombinant human antithrombin iii synthesized in chinese hamster ovary cells.biochemical and physiochemical properties of recombinant human antithrombin iii were examined. this protein, produced in chinese hamster ovary cells, showed a conformation apparently identical with the natural product isolated from human plasma when examined by circular dichroism, uv absorbance, and fluorescence spectroscopy. comparison of the nh2-terminal sequences of recombinant and human plasma-derived antithrombin iii showed that on synthesis and secretion of the recombinant protein from chi ...19892592368
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