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human glioblastoma cell derived transforming growth factor-beta 2: evidence for secretion of both high and low molecular weight biologically active forms.transforming growth factors beta (tgf-beta) form a family of multifunctional polypeptides which in the active dimeric forms have a molecular weight of 25 kda. human glioblastoma cells secrete immunosuppressive tgf-beta consisting mostly of tgf-beta 2 rather than tgf-beta 1. the results shown here demonstrate that in addition to the mature 25 kda form of tgf-beta 2, glioblastoma cells release a biologically active high molecular weight form of tgf-beta 2 which suppresses the interleukin-2-depende ...19911894732
an experimental approach to identifying the genotoxic risk by cooked meat mutagens.in order to define the toxicological risk for the human population derived from the chemical compounds formed during the process of cooking animal meat, which have been described to possess a mutagenic, genotoxic, and carcinogenic activity, an extensive study has been developed on cooked meat extract and two cooked meat mutagens, iq and meiqx. the study has been based on toxicokinetics and mouse tissue distribution of the two chemicals, on in vitro and in vivo mutagenicity/genotoxicity analyses ...19911897387
enhancement of heme oxygenase-1 synthesis by glutathione depletion in chinese hamster ovary cells.chinese hamster ovary cells cultured in vitro were used to assess the role of glutathione metabolism in the induction of the 32-kda stress protein. enhanced synthesis of the 32-kda protein was observed after cells were incubated with cdcl2 or diethylmaleate and protein was subjected to sds-page followed by fluorography. concomitantly, in both cell preparations an increase in heme oxygenase activity was observed. proteins from cdcl2- and diethylmaleate-treated cells were subjected to western blot ...19911898036
oligosaccharide structures present on asparagine-289 of recombinant human plasminogen expressed in a chinese hamster ovary cell line.the oligosaccharide structures linked to asn289 of a recombinant (r) variant (r561s) human plasminogen (hpg) expressed in chinese hamster ovary (cho) cells, after transfection of these cells with a plasmid containing the cdna coding for the variant hpg, have been determined. employing high-performance anion-exchange liquid chromatography mapping of the oligosaccharide units cleaved from the protein by glycopeptidase f, compared with elution positions of standard oligosaccharides, coupled with mo ...19911899031
disruption of the golgi apparatus by brefeldin a inhibits the cytotoxicity of ricin, modeccin, and pseudomonas toxin.we have studied the cytotoxicity of ricin in cells treated with brefeldin a (bfa), which dramatically disrupts the structure of the golgi apparatus causing golgi content and membrane to redistribute to the er. bfa inhibits the cytotoxicity of ricin in chinese hamster ovary, normal rat kidney, and vero cells and abolishes the enhancement of ricin cytotoxicity by nh4cl, nigericin, swainsonine, and tunicamycin or by a mutation in endosomal acidification. bfa protects cells from the cytotoxicities o ...19911899070
tea tannin components modify the induction of sister-chromatid exchanges and chromosome aberrations in mutagen-treated cultured mammalian cells and mice.the modifying effects of tannin components extracted from green tea and black tea on mutagen-induced sces and chromosome aberrations were studied. these tannin components did not affect spontaneous sces and chromosome aberrations in cultured chinese hamster cells. the frequency of sces and chromosome aberrations induced by mitomycin c (mmc) or uv was enhanced by the posttreatment with tea tannin components. when cells were post-treated with tea tannin components in the presence of metabolic enzy ...19911899132
the dysfunctional ldl receptor in a monensin-resistant mutant of chinese hamster ovary cells lacks selected o-linked oligosaccharides.the chinese hamster ovary (cho) cell line monr31, which is resistant to the cytotoxic ionophore monensin, produces a receptor for the low density lipoprotein (ldl) that has a lowered binding affinity for ldl and is approximately 5 kda smaller in size than the receptor from parental cho cells. it has been proposed that the reduced size and affinity for ldl are associated with a reduced level of o-glycosylation of ser/thr residues in the receptor. to examine this possibility in more detail, both p ...19911899178
construction and characterization of a functional chimeric murine-human antibody directed against human fibrin fragment-d dimer.fibrin-directed monoclonal antibodies may be clinically useful for in vitro thrombus imaging and for the targeting of fibrinolytic agents to blood clots. one such murine monoclonal antibody, (mab-15c5), raised against the fragment-d dimer epitope of cross-linked human fibrin, was previously characterized [holvoet, p., stassen, j. m., hashimoto, y., spriggs, d., devos, p. & collen, d. (1989) thromb. haemostasis 61, 307-313] has recently been cloned and expressed [vandamme, a.-m., bulens, f., bern ...19911899382
heterogeneity in the tyrosine sulfation of chinese hamster ovary cell produced recombinant fviii.by the use of recombinant technology, several stable chinese hamster ovary (cho) cell lines expressing human fviii were established. thrombin treatment and sds-page analysis of the purified recombinant fviii (rfviii) revealed a striking difference from plasma-derived fviii (pfviii). a 43-kda fragment of the fviii heavy chain appears as a double band from rfviii, while a single band from pfviii is observed. all other fragments from the two samples appeared similar by sds-page. the heterogeneity i ...19911899619
assignment of human preprothyrotropin-releasing hormone (trh) gene to chromosome 3.the human gene encoding preprotrh (thyrotropin-releasing hormone) was assigned to chromosome 3, using human-chinese hamster ovary somatic cell hybrids, analyzed by southern hybridizations. hybridization was carried out with a 32p-labeled human preprotrh cdna labeled by the method of random priming. hybridization of the cdna probe to a human specific 4.8-kb dna fragment of ecori-digested wbc dna was used to localize the human preprotrh gene. no hybridization, by contrast, was seen with human prep ...19911900134
fjord- and bay-region diol-epoxides investigated for stability, sos induction in escherichia coli, and mutagenicity in salmonella typhimurium and mammalian cells.the fjord-region diol-epoxides of benzo(c)phenanthrene combine high mutagenic and carcinogenic activity with low chemical reactivity. to study whether this is a unique property of these compounds or a more general characteristic of fjord-region diol-epoxides, we have synthesized the anti- and syn-diastereomers of r-9,t-10-dihydroxy-11,12-oxy-9,10,11,12-tetrahydrobenzo(c)chrysene and r-11-t-12-dihydroxy-13,14-oxy-11,12,13,14-tetrahydrobenzo(g)chrysene. these compounds as well as the anti- and syn ...19911900215
tissue plasminogen activator has an o-linked fucose attached to threonine-61 in the epidermal growth factor domain.an unusual type of glycosylation has been observed for tissue plasminogen activator (t-pa). the monosaccharide fucose is glycosidically linked to threonine-61 in the epidermal growth factor region of t-pa. the presence of o-linked fucose was demonstrated by carbohydrate analysis and mass spectrometry of tryptic and chymotryptic peptides that contain this site. the susceptibility of the fucose residue to alpha-fucosidase indicated that it was in the alpha-anomeric configuration. fucosylation of t ...19911900431
the chinese hamster cell mutant v-h4 is homologous to fanconi anemia (complementation group a).v-h4, a mitomycin c (mmc)-sensitive chinese hamster cell mutant, is phenotypically very similar to fanconi anemia (fa) cells. genetic complementation analysis shows that v-h4 belongs to the same complementation group as fa group a cells. proliferating hybrid cell lines obtained after fusion of v-h4 with normal or fa group b cells show an increased resistance to mmc. absence of complementation was noted in v-h4 x fa group a hybrid cell lines. this was shown not to be due to the absence of a speci ...19911900747
gene for murine alpha 1----3-galactosyltransferase is located in the centromeric region of chromosome 2.the gene for alpha 1----3-galactosyltransferase, termed ggta-1, was mapped to mouse chromosome 2 by southern blot analysis of chinese hamster x mouse somatic cell hybrids. using an intersubspecies back-cross, this locus was positioned to the centromeric region on this chromosome, near the hc locus.19911901427
analysis of protein transport through the golgi in a reconstituted cell-free system.the processes which transport membrane proteins between compartments of the golgi apparatus have been reconstituted in vitro using isolated golgi fractions. this cell-free system allows a detailed analysis of protein transport not possible in intact cells. transport of the membrane glycoprotein (g protein) of vesicular stomatitis virus (vsv) is measured from a "donor" to an "acceptor" golgi fraction. the donor golgi fraction is prepared from vsv-infected chinese hamster ovary (cho) mutant cells ...19911901603
genotoxic effects of the drinking water mutagen 3-chloro-4-(dichloromethyl)-5-hydroxy-2[5h]-furanone (mx) in mammalian cells in vitro and in rats in vivo.the potent bacterial mutagen 3-chloro-4-(dichloromethyl)-5-hydroxy-2[5h]- furanone) (mx), which is formed during chlorination of drinking water and accounts for about one third of the ames mutagenicity of tap water, has been studied with respect to its genotoxicity in vitro and in vivo. treatment with 30-300 microm mx (1 h) induced dna damage in a concentration-dependent manner in suspensions of rat hepatocytes, as measured by an automated alkaline elution system. the effect was similar in hepat ...19911902909
evaluation of the probability of spontaneous transfer of drug resistance between cells in culture.coculture of two different cell lines in monolayer or spheroids was used to investigate the spontaneous transfer of dominant genes determining drug resistance. mgh-u1 human bladder cancer cells (ouabain-sensitive, mitomycin c-resistant) were cocultured with uv-20 cells (a subline of chinese hamster ovary cells which is ouabain-resistant and mitomycin c-sensitive). we investigated the possible transfer of mitomycin-c resistance from human to rodent cells by selection in both ouabain and mitomycin ...19911903383
expression, isolation, and characterization of an active site (serine 528----alanine) mutant of recombinant bovine prothrombin.an active site mutant bovine prothrombin cdna (ser528----ala) has been constructed, subcloned, and expressed in chinese hamster ovary cells. the recombinant mutant prothrombin, expressed at the level of 1.5-2.0 micrograms/ml of cell medium, was fully carboxylated (9.9 +/- 0.4 mol of gamma-carboxyglutamic acid/mol of prothrombin). the mutant prothrombin could be activated to thrombin by taipan snake venom and activated to meizothrombin by ecarin in a manner comparable to native bovine prothrombin ...19911903392
metabolic formation, synthesis and genotoxicity of the n-hydroxy derivative of the food mutagen 2-amino-1-methyl-6-phenylimidazo (4,5-b) pyridine (phip).hepatic microsomes from rats pretreated with pcb were found to metabolize the food mutagen 2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine (phip) to two major metabolites, one of which was identified as the n-hydroxy derivative, 2-hydroxy-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine (n-oh-phip). this identification was based on mass spectral (ms), uv and hplc data by comparison with n-oh-phip prepared by chemical synthesis, as well as the specific activity of the compound in the ames salmonella ...19911903830
cultured human fibroblasts contain a large pool of precursor beta 1-integrin but lack an intracellular pool of mature subunit.previous work has shown the presence of an important intracellular pool of beta 1-integrin subunit in human skin fibroblasts as detected with monoclonal antibody dh12 [de strooper, b., van der schueren, b., jaspers, m., saison, m., spaepen, m., van leuven, f., van den berghe, h. & cassiman, j. j. (1989) j. histochem. cytochem. 37,299-307]. to analyze this more quantitatively, a radioimmunoassay with radioiodinated monoclonal antibody was developed. the total amount of specific binding sites for ...19911906002
inhibition of degradation of 3-hydroxy-3-methylglutaryl-coenzyme a reductase in vivo by cysteine protease inhibitors.3-hydroxy-3-methylglutaryl-coenzyme a (hmg-coa) reductase is a key regulatory enzyme of cholesterol biosynthesis and is located in the endoplasmic reticulum (er). a fusion protein, hmgal, consisting of the membrane domain of hmg-coa reductase fused to escherichia coli beta-galactosidase and expressed in chinese hamster ovary (cho) cells from the sv40 promoter, was previously constructed and was found to respond to regulatory signals for degradation in a similar fashion to the intact hmg-coa redu ...19911906466
recombinant expression of human follistatin with 315 and 288 amino acids: chemical and biological comparison with native porcine follistatin.follistatin is a glycosylated monomeric protein originally isolated from ovarian follicular fluid based on its ability to specifically inhibit pituitary fsh release. to further explore the physiological role of follistatin, we have expressed recombinant human follistatins with 315 (rhfs-315) and 288 (rhfs-288) amino acids in chinese hamster ovary cells under the control of the simian virus-40 promoter. the two types of fs originated from alternatively spliced mrnas and rhfs-315 differed from rhf ...19911906804
molecular cloning and characterization of a complete chinese hamster provirus related to intracisternal a particle genomes.we report here the nucleotide sequence of a full-length chinese hamster genomic proviral element, chiap34. chiap34 is 6,403 bp long with long terminal repeats of 311 bp at each end. the genetic organization of chiap34 was determined by comparison with intracisternal a particle (iap) genetic elements from the mouse and syrian hamster. extensive homology at the nucleotide and deduced amino acid sequence levels was observed between chiap34 and the mouse and syrian hamster iap elements. chiap34 may ...19911908027
secretion of the beta/a4 amyloid precursor protein. identification of a cleavage site in cultured mammalian cells.alzheimer's disease, a progressive neurodegenerative disorder, affects greater than 10% of the population of individuals greater than 65 years of age. a principal neuropathological feature of this disease is the senile plaque, a fibrillar extracellular deposit primarily composed of a approximately 4-kda peptide, beta/a4, derived from the amyloid precursor protein (app). studies in cultured cells have documented that app matures through a constitutive secretory pathway and is cleaved at or near t ...19911909332
dopamine activation of the arachidonic acid cascade as a basis for d1/d2 receptor synergism.understanding the actions of the neurotransmitter dopamine in the brain is important in view of its roles in neuropsychiatric illnesses. dopamine d1 receptors, which stimulate both adenylyl cyclase and phospholipase c, and d2 receptors, which inhibit them, can nevertheless act synergistically to produce many electrophysiological and behavioral responses. because this functional synergism can occur at the level of single neurons, another, as yet unidentified, signalling pathway activated by dopam ...19911909771
quantitative immunocytochemical staining for recombinant tissue-type plasminogen activator in transfected chinese hamster ovary cells.tissue-type plasminogen activator (tpa) is a serine protease which cleaves plasminogen to its active form, plasmin. tpa plays a physiologic role in hemostasis, wound healing, and embryogenesis. therapeutically, recombinant human tpa is used as a thrombolytic in myocardial infarction. although production of therapeutic quantities of tpa in chinese hamster ovary (cho) cells transfected with the human gene for tpa is practical, production costs remain high. one important factor which determines the ...19911909792
inhibition by 2,6-dithiopurine and thiopurinol of binding of a benzo(a)pyrene diol epoxide to dna in mouse epidermis and of the initiation phase of two-stage tumorigenesis.the chemotherapeutic agent 6-mercaptopurine was previously shown to inhibit the binding of 7r,8t-dihydroxy-9,10t-oxy-7,8,9,10-tetrahydro-benzo(a) pyrene (bpde-i) to dna in chinese hamster ovary cells. two compounds related to 6-mercaptopurine, 2,6-dithiopurine (dtp) and thiopurinol (tp), have been tested for inhibition of the binding of bpde-i to epidermal dna in mouse skin. doses of test compound (0.2-20 mumol) or solvent control were applied to the shaved backs of female sencar mice. fifteen m ...19911909930
anthrax protective antigen interacts with a specific receptor on the surface of cho-k1 cells.the interaction of protective antigen (pa), a component of the anthrax toxin, with receptors on the chinese hamster ovary cell line cho-k1 was characterized. protective antigen binding at 4 degrees c is highly specific, concentration dependent, saturable (kd = 0.9 nm), and reversible. scatchard analysis indicates the presence of a single class of pa binding sites at a concentration of 10,000 +/- 2,000 per cell. pretreatment of cells with a number of different proteases strongly inhibits pa bindi ...19911909998
slit scan flow cytometry of isolated chromosomes following fluorescence hybridization: an approach of online screening for specific chromosomes and chromosome translocations.the recently developed methods of non radioactive in situ hybridization of chromosomes offer new aspects for chromosome analysis. fluorescent labelling of hybridized chromosomes or chromosomal subregions allows to facilitate considerably the detection of specific chromosomal abnormalities. for many biomedical applications (e.g. biological dosimetry in the low dose range), a fast scoring for aberrations (e.g. dicentrics or translocations) in required. here, we present an approach depending on flu ...19911910388
overexpression of low density lipoprotein receptor on chinese hamster ovary cells generates foam cells.the atherosclerotic lesion is characterized by the presence of cholesterol-loaded foam cells. chinese hamster ovary (cho) cells do not normally store cholesteryl esters because low density lipoprotein (ldl) receptors are suppressed by exposure of these cells to ldl cholesterol. we transfected ldl receptor cdna linked to the simian virus 40 early promoter into cho cells (cho 29) and found that ldl receptor binding in these cells was not suppressed by an excess amount of ldl cholesterol, indicatin ...19911911717
increased survival after treatments with anticancer agents of chinese hamster cells expressing the human mr 27,000 heat shock protein.a family of 10 thermoresistant cell lines cloned from chinese hamster cells transfected with a plasmid containing the structural gene for the small human mr 27,000 heat shock protein (hsp27) was used to assess the putative role of this heat shock protein in chemoresistance. these cells express varying amounts of human hsp27 in addition to the normal level of endogenous hamster hsp27. as previously observed in the case of thermoresistance, a significant positive linear correlation (p less than 0. ...19911913647
cell-cycle specific cytotoxicity mediated by stizophyllin (2 alpha,3 beta,12 beta-trihydroxypregna-4,7,16-trien-20-one), a novel electrophilic pregnane isolated from stizophyllum riparium.a structurally-novel pregnane derivative, 2 alpha,3 beta,12 beta-trihydroxypregna-4,7,16-trien-20-one (stizophyllin), was isolated from an extract of stizophyllum riparium (h.b.k.) sandw. on the basis of bioactivity-guided fractionation and confirmed to mediate a potent cytotoxic response with cultured p-388 cells. we presently report a detailed isolation procedure and the results of studies designed to examine its mechanism of action. by means of a michael-type addition, stizophyllin formed add ...19911913978
identification of the cdna clone which encodes the 58-kda protein containing the amino acid sequence of rat liver non-specific lipid-transfer protein (sterol-carrier protein 2). homology with rat peroxisomal and mitochondrial 3-oxoacyl-coa thiolases.the relationship between the rat liver non-specific lipid-transfer protein (nsltp) and the 58-kda protein cross-reactive with anti-nsltp antibodies, was investigated by cdna analysis. a 1945-bp cdna clone was isolated which encodes a 58.7-kda protein. this protein is identical to the 58-kda immunoreactive protein determined by n-terminal sequence analysis of the purified 58-kda protein. it consists of 546 amino acid residues, of which the 123 c-terminal residues are identical to the sequence of ...19911915369
cloning and expression of human ciliary neurotrophic factor.ciliary neurotrophic factor (cntf) is a survival factor for avian ciliary ganglion neurons and a variety of other neuronal cell types in vitro. we report here the cloning of the entire genomic sequence encoding human cntf and its primary structure. biologically active cntf has been expressed in chinese hamster ovary cells from a human genomic dna clone. human cntf has no significant sequence similarity to any previously reported protein, although approximately 84% similarity exists compared with ...19911915374
interferon-gamma inhibits serotonin release from mouse peritoneal mast cells.conditioned medium (cm) from concanavalin a-activated mouse spleen cells inhibits antigen-induced 5-hydroxytryptamine (5-ht) release from mouse peritoneal mast cells when added for 24 or 48 h to cell cultures containing monoclonal ige sensitizing antibody. we present the following evidence that the spleen cell-derived inhibitory factor is interferon-gamma (ifn-gamma): (a) cm from con a-activated spleen cells and from chinese hamster ovary (cho) cells transfected with the murine (mu)ifn-gamma gen ...19911915558
localization of the xeroderma pigmentosum group b-correcting gene ercc3 to human chromosome 2q21.the human excision-repair gene ercc3 was cloned after dna-mediated gene transfer to the uv-sensitive chinese hamster ovary mutant cell line 27-1, a member of complementation group 3 of the excision-defective rodent cell lines. the ercc3 gene specifically corrects the dna repair defect of xeroderma pigmentosum (xp) complementation group b, which displays the clinical symptoms of xp as well as of another rare excision-repair disorder, cockayne syndrome. the gene encodes a presumed dna and chromati ...19911916809
an amino acid substitution in biobreeding rat corticosteroid binding globulin results in reduced steroid binding affinity.biobreeding (bb) rats are derived from an outbred colony of wistar rats and are used as a model of autoimmune diabetes mellitus. a corticosteroid binding globulin (cbg) variant with reduced affinity for glucocorticoids has now been found in the blood of these animals. the dissociation rate constants of bb cbg for cortisol (4.42 nm) and corticosterone (1.43 nm) are both about 50% higher than those associated with wistar cbg, but no obvious difference in the steroid binding specificity of bb and w ...19911917978
mouse submandibular gland prorenin-converting enzyme is a member of glandular kallikrein family.mouse submandibular gland prorenin-converting enzyme (prece) consists of the two polypeptide chains of 17 and 10 kda and cleaves mouse ren-2 prorenin at a dibasic site to yield mature renin. western blot analysis using an antiserum against this enzyme gave rise to multiple bands in mouse submandibular glands, suggesting that prece is a member of a protease family. partial amino acid sequence analysis of purified prece and cloning and sequence analyses of its cdna indicated that it is identical t ...19911918045
role of the invariant aspartic acid 99 of human choriogonadotropin beta in receptor binding and biological activity.the four human glycoprotein hormones are heterodimers that contain a common alpha subunit and a hormone-specific beta subunit. within this hormone family, 23 amino acid sequences from 11 mammalian species are available. there are 19 invariant amino acid residues in the beta subunits, 12 of which are cys that form six disulfide bonds. of the remaining seven conserved amino acid residues, we have investigated the role of an asp which occurs at position 99 in human choriogonadotropin beta (hcg beta ...19911918051
evidence that erythroid-type glucose transporter intrinsic activity is modulated by cadmium treatment of mouse 3t3-l1 cells.previous studies suggest that regulation of hexose uptake in chinese hamster ovary fibroblasts can occur by alterations in glucose transporter intrinsic activity without changes in cell surface transporter number (harrison, s. a., buxton, j. m., helgerson, a. l., macdonald, r. g., chlapowski, f. j., carruthers, a., and czech, m. p. (1990) j. biol. chem. 265, 5793-5801). we tested this hypothesis using 3t3-l1 fibroblasts and adipocytes which exhibit 5-6-fold increases in 2-deoxyglucose or 3-o-met ...19911918056
dna-mediated transfer of a human gene that confers resistance to mitomycin c.attempts to complement the defect in the mitomycin c (mmc)-sensitive chinese hamster ovary (cho) mutant mmc3 led to the isolation of hybrids with high resistance to the cytotoxic action of the drug. hybrid cells selected with mmc after fusion of mmc3 cells to human diploid fibroblasts were approximately five times more resistant to mmc than wild-type cho cells but retained the original mmc3 sensitivity to another dna cross-linking agent, diepoxybutane. to confirm that the mmc resistance was gene ...19911918174
chinese hamster ovary cell assays for mutation and chromosome damage: data from non-carcinogens.in vitro genotoxicity tests are employed to screen chemicals for their capability to cause various dna and chromosomal alterations, and the results are often used to predict their potential for carcinogenicity. however, there is controversy regarding the apparent low specificity of some in vitro genotoxicity assays, which result in a high false positive rate. since we use and rely upon in vitro assays for risk assessment and prediction of carcinogenicity, this specificity issue is of serious con ...19911918790
the hiv-1 gp120 envelope protein has the intrinsic capacity to stimulate monokine secretion.results and conclusions concerning the ability of hiv glycoprotein (gp) 120 to stimulate monokine secretion have been equivocal, based on observations using natural gp120 derived from infected human cells and a chinese hamster ovary (cho) cell-derived recombinant fusion protein. current studies were designed to determine whether differences in recombinant gp120 proteins could result in failure to trigger monokine production. we found that natural gp120 could stimulate monocytes to release tnf-al ...19911918997
molecular evolution of the mammalian ribosomal protein gene, rps14.ribosomal protein s14 genes (rps14) in eukaryotic species from protozoa to primates exhibit dramatically different intron-exon structures yet share homologous polypeptide-coding sequences. to recognize common features of rps14 gene architectures in closely related mammalian species and to evaluate similarities in their noncoding dna sequences, we isolated the intron-containing s14 locus from chinese hamster ovary (cho) cell dna by using a pcr strategy and compared it with human rps14. we found t ...19911921707
the origin of o6-methylguanine-dna methyltransferase in chinese hamster ovary cells transfected with human dna.transfection of chinese hamster ovary (cho) cells with human dna has been shown in several laboratories to produce clones which stably express the dna-repair protein, o6-methylguanine-dna methyltransferase (mgmt), that is lacking in the parent cell lines (mex- phenotype). we have investigated the genetic origin of the mgmt in a number of such mgmt-positive (mex+) clones by using human mgmt cdna and anti-human mgmt antibodies as probes. none of the five independently isolated mex+ lines has human ...19911922149
genotoxicity testing of extracts of a swedish moist oral snuff.the present study was designed to investigate the potential genotoxicity of aqueous and methylene chloride extracts of swedish moist oral snuff. the test systems were selected to provide optimal data for the prediction of carcinogenicity in rodents and included assays for the induction of mutation in bacteria, sister-chromatid exchanges (sce) in human lymphocytes, of chromosome aberrations and gene mutations in v79 chinese hamster cells and of micronuclei in mouse bone marrow cells. in addition, ...19911922153
the effects of ventilation and the dilution of smoke upon the clastogenic and aneugenic activity of tobacco particulate matter in cultured mammalian cells.we demonstrate here that tobacco particulate matter (tpm) produced from both non-ventilated and ventilated cigarettes of varying tar contents induced structural and numerical aberrations in cultured chinese hamster cells. our data indicate that tpm from ventilated cigarettes is of lower potency in inducing both clastogenic and aneugenic effects compared with tpm from non-ventilated cigarettes. these observations provide support for the concept that the genotoxic activity (to cultured chinese ham ...19911922161
functional analysis of the tobacco mosaic virus trna-like structure in cytoplasmic gene regulation.the 3'-untranslated region (utr) of tobacco mosaic virus (tmv), which terminates in a trna-like structure, functionally substitutes for a poly(a) tail in both plant and animal cells. the addition of the tmv 3'-utr to chimeric mrna constructs increases their expression up to 100-fold, increasing both translational efficiency and mrna stability. the domain largely responsible for the regulation maps to a 72 base region immediately upstream of the trna-like structure, however, the 3'-terminal, trna ...19911923770
characterization of chinese hamster ovary cells stably transformed by a plasmid with an inducible aprt gene.a plasmid was constructed by fusion of a selectable mammalian gene, hamster adenine phosphoribosyltransferase (aprt), to the zn(2+)-inducible sheep metallothionein i (mt i) promoter. this plasmid was used to produce stable chinese hamster ovary (cho) cell transformants by electroporation to study the effects of induced gene expression on dna-mediated transformation. the sheep mt ia promoter was chosen for these experiments because it regulates gene expression differently than murine mt promoters ...19911924558
synthesis and characterization of a pertussis toxin-biotin conjugate.we prepared a pertussis toxin-biotin conjugate and found its biological properties to be similar to those of native pertussis toxin with respect to the hemagglutination, chinese hamster ovary cell, and lymphocyte proliferation assays. direct binding to chinese hamster ovary and jurkat cells was observed using fluorescence microscopy. pertussis toxin-biotin was also found to possess similar glycoconjugate binding specificities as those of 125i-labeled pertussis toxin.19911930187
purification and characterization of natural human interleukin-3.the human interleukin-3 gene was cloned in 1986 and the biochemical and biological properties of recombinant human interleukin-3 (rhuil-3) protein were described. in this report we compare rhuil-3 with nonrecombinant, natural huil-3, purified from the supernatant of the human t cell leukemia line jurkat. the main purification step, affinity chromatography, using a selected monoclonal anti-huil-3 antibody, resulted in an approximately 40,000-fold enrichment of huil-3. combination of this step wit ...19911932378
site specificity of n-methyl-n-nitrosourea-induced transition mutations in the hprt gene.the reaction product of n-methyl-n-nitrosourea (mnu) with dna, o6-methylguanine (o6-meg), is responsible for the mutagenic and carcinogenic effects of this carcinogen. these involve activation of the h-ras proto-oncogene in rat mammary tumors by mnu, with a high frequency of gc to at transitions in codon 12 of this gene. the present study aimed to investigate the types and position specificities of mutations induced by mnu in another gene, the hprt gene of v79 chinese hamster cells. furthermore, ...19911934271
comparative in vitro and in vivo studies on the biological characteristics of recombinant human follicle-stimulating hormone.the in vitro and in vivo activities of recombinant human fsh (recfsh) produced by a chinese hamster ovary cell line were studied and compared with those of natural fsh preparations. the specific fsh activities of recfsh established by immunoassay and in vivo bioassay were greater than 10,000 iu/mg protein and considerably higher than the activities of tested urinary fsh references, while the in vivo bio/immuno ratios of these preparations were not significantly different. compared to a highly pu ...19911935792
overexpression of an immunologically-intact, secreted form of human thyroid peroxidase in eukaryotic cells.recombinant human thyroid peroxidase (htpo) has been expressed in eukaryotic cells as both the membrane-associated enzyme and as a secreted protein. we now report overexpression of the secreted form of recombinant htpo in eukaryotic cells. for htpo gene amplification we used a vector containing the mouse dihydrofolate reductase (dhfr) gene. stably transfected chinese hamster ovary (cho) cells were grown in the presence of increasing concentrations of methotrexate (mtx) and htpo expression was me ...19911936519
evidence that functional erythrocyte-type glucose transporters are oligomers.in this study we tested the hypothesis that functional erythrocyte-type glucose transporters (glut1) exist as oligomeric complexes by expressing chimeric transporter proteins in chinese hamster ovary cells harboring endogenous glut1 transporters. the chimeric transporters were glut1-4c, in which the 29 c-terminal residues of human glut1 were replaced by the 30 c-terminal residues of rat skeletal muscle glucose transporter (glut4), and glut1n-4, containing the n-terminal 199 residues of glut1 and ...19911939082
protease specificity and heparin binding and activation of recombinant protease nexin i.structural and functional properties of alpha-protease nexin i (alpha-pni) expressed in chinese hamster ovary cells were studied. all three cysteines were in the reduced form, showing that the potential disulfide bridge between residues cys117 and cys131 was not formed. heparin association rate enhancements were from ka = 8.3 x 10(5) to 0.7-1.6 x 10(9) m-1 s-1 for the interaction of pni with thrombin, from ka = 5.1 x 10(3) to 3.5 x 10(5) m-1 s-1 for interaction with factor xa, and from ka = 2.2 ...19911939253
lipoproteins in pinnipeds: analysis of a high molecular weight form of apolipoprotein e.we have examined the apolipoprotein content of the lipoproteins of several marine mammals by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. their apolipoprotein (apo) b-100, apob-48, and apoa-i migrated to virtually the same position as the comparable human apolipoproteins. in cetaceans (bottlenose dolphins and killer whales), the molecular mass of the apoe was identical to that of human apoe (35 kda). in contrast, in the lipoproteins of pinnipeds (harbor seals, sea lions, and walrus ...19911940617
binding of [3h]af-dx 384 to cloned and native muscarinic receptors.the binding selectivity of [3h]af-dx 384 [(+-)-5,11-dihydro-11- ([(2-(2-[(dipropylamino)methyl]-1- piperidinyl)ethyl)amino]carbonyl)-h-pyrido(2,3-b)(1,4)benzodiazepine-6-o ne] was evaluated with cloned human muscarinic receptors (m1-m4) in chinese hamster ovary (cho-k1) cell lines as well as in rat heart and brain. there were uniform classes of sites for the radioligand in the m2-rich tissues, heart (kd = 2.3 nm) and brainstem (kd = 2.4 nm). however, [3h]af-dx 384 bound to all four cloned recept ...19911941609
metabolic activation and cytogenetic effects of 2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine (phip) in chinese hamster ovary cells expressing murine cytochrome p450 ia2.we have utilized chinese hamster ovary cell lines which stably express a murine cytochrome p450ia2 (p(3)450) cdna to characterize more fully the mechanisms of genotoxicity of heterocyclic amines derived from cooked meats. to verify that these cell lines were capable of converting promutagens into active metabolites, we studied the microsomal metabolism and cytogenetic effects of 2-amino-1-methyl-6-phenylimidazo-[4,5-b]pridine (phip). microsomal preparations derived from excision repair-deficient ...19911943715
investigations into the induction of aneuploidy and polyploidy in mammalian cells by the anti-tussive agent noscapine hydrochloride.noscapine, a non-narcotic, centrally-acting anti-tussive drug induces polyploidy in chinese hamster chl cells; further studies were carried out to investigate whether similar effects could be induced in other rodent cells (chinese hamster v79) and in human lymphocytes. in both cases, large increases in the frequency of polyploid cells were induced at test concentrations ranging from 15 to 120 micrograms/ml after 24 and 48 h continuous treatment in the absence of s9 mix. in addition, spindle dama ...19911943718
müllerian inhibiting substance blocks epidermal growth factor receptor phosphorylation in fetal rat lung membranes.neonatal males develop respiratory distress syndrome more frequently than females for unknown reasons. the fetal testis secretes testosterone and müllerian inhibiting substance (mis); mis has been shown to inhibit fetal lung maturation in vitro and in vivo and to block phosphorylation of epidermal growth factor (egf) receptors in a431 cells. we hypothesized that mis would also inhibit membrane phosphorylation of egf receptors in fetal lung, and that ultrastructural study of mis-exposed lung migh ...19911943746
human alpha-l-iduronidase: cdna isolation and expression.alpha-l-iduronidase (idua; ec 3.2.1.76) is a lysosomal hydrolase in the metabolic pathway responsible for the degradation of the glycosaminoglycans heparan sulfate and dermatan sulfate. a deficiency of idua in humans leads to the accumulation of these glycosaminoglycans and results in the lysosomal storage disorder mucopolysaccharidosis type i. we have isolated and sequenced cdna clones containing part of the human idua coding region and used pcr from reverse-transcribed rna to obtain the full i ...19911946389
characteristics of nonpathogenic strains of listeria monocytogenes.five strains of nonpathogenic listeria monocytogenes were characterized for (i) hemolysin production, (ii) cytolysis of chinese hamster ovary (cho) cells, and (iii) ability to attach and enter intestine 407 cells. four of the five strains produced variable hemolysis and were weakly cytolytic for chinese hamster ovary cells, whereas the other isolate was consistently hemolytic and strongly cytolytic for cho cells. none of the strains was able to penetrate intestine 407 cells. in addition, two of ...19911954578
an attempt at transmission of hormonal imprinting between foreign cell lines.hormonal imprinting is transmitted from imprinted to virgin cells of the same cell line. no transmission of imprinting occurred between chinese hamster ovary (cho) and human chang liver cells, and the presence of the latter reduced rather than enhanced the thyrotropic hormone (tsh) binding capacity of the cho cells. while hormone binding capacity was relatively homogeneous in the control and the mixed cell cultures, it was not homogeneous in the homologous imprinted plus virgin cell population, ...19911954786
synthesis, molecular modeling studies, and muscarinic receptor activity of azaprophen analogues.synthesis, radioligand binding, and pharmacologic activities of a series of muscarinic receptor ligands including and related to azaprophen (6-methyl-6-azabicyclo[3.2.1]octan-3 alpha-ol 2,2-diphenylpropionate, 1) have been measured to determine activity and selectivity for muscarinic receptor subtypes. pharmacologic affinities of antagonists were determined as pa2 values for antagonism of methacholine-induced tension responses in guinea pig ileum. binding affinities were measured by competition ...19911956033
measuring gene mutation in vivo.both chromosomal aberrations and intragenic mutations are important in the activation of oncogenes and inactivation of antioncogenes. it is now possible to measure both types of mutational events in vivo in a single cell type. the results obtained in both chinese hamsters and rats are surprising: mutations can be induced in the absence of detectable chromosomal aberrations by some agents and vice versa by others. preliminary results from a validation study are presented.19911956925
effect of 1-methyl-2-nitrosoimidazole on intracellular thiols and calcium levels in chinese hamster ovary cells.the cellular reduction of 2-nitroimidazoles under hypoxic conditions can lead to cell killing. one of the postulated toxic intermediates is the two-electron reduction product, the nitrosoimidazole. 1-methyl-2-nitrosoimidazole (ino) was used as a model to study the reactivity of 2-nitrosoimidazoles with sulfhydryls. ino reacted within minutes with bovine serum albumin (bsa) in a stoichiometric fashion as measured by the loss of its characteristic absorption at 360 nm. it appeared to react specifi ...19911958233
comparative evaluation of some bioassay models & serological tests for the detection of salmonella enterotoxin.two bioassay models viz., rabbit ligated ileal loop (rlil) and the chinese hamster ovary (cho) cell culture and three serological methods viz., enzyme-linked immunosorbent assay (elisa), biken and staphylococcal coagglutination (coa) tests were standardized and used for the detection of salmonella enterotoxin. a total of 37 strains belonging to 14 different serotypes of salmonella were tested simultaneously by all the five assay models. serological tests were standardized with antiserum against ...19911959949
the lymphocytosis promoting action of pertussis toxin can be mimicked in vitro. holotoxin but not the b subunit inhibits invasion of human t lymphoma cells through fibroblast monolayers.pertussis toxin is known to elicit lymphocytosis in whooping cough patients and experimental animals, by blocking the extravasation of lymphocytes and stimulating their release from lymphoid organs such as the thymus. the mechanisms responsible for these unique effects of pt are not fully understood. the effect of pertussis toxin (pt) on the invasive behavior of human ccrf-cem t lymphoma cells has been investigated with the use of a monolayer invasion assay (mia). we had previously found that in ...19911960420
functional analysis of an oxygen-regulated transcriptional enhancer lying 3' to the mouse erythropoietin gene.erythropoietin, the major hormone controlling red-cell production, is regulated in part through oxygen-dependent changes in the rate of transcription of its gene. using transient transfection in hepg2 cells, we have defined a dna sequence, located 120 base pairs 3' to the poly(a)-addition site of the mouse erythropoietin gene, that confers oxygen-regulated expression on a variety of heterologous promoters. the sequence has the typical features of a eukaryotic enhancer. approximately 70 base pair ...19911961720
myogenin is in an evolutionarily conserved linkage group on human chromosome 1q31-q41 and unlinked to other mapped muscle regulatory factor genes.myogenin is a member of a family of muscle-specific regulatory factors which includes myod1, myf-5, and myf-6 (also called mrf4 and herculin). extensive regions of sequence homology in genes for these three factors suggest duplication events associated with their evolution. in the present study, the chromosomal location of the myogenin gene in humans (myog), mice (myog), and chinese hamsters (myog) was determined using in situ hybridization to human metaphase chromosomes as well as segregation a ...19901962752
recombinant human prorenin from cho cells: expression and purification.the gene for human preprorenin was obtained from total rna prepared from primary human chorion cells. an expression vector was constructed containing an sv40 early promoter, a human preprorenin cdna, bovine growth hormone poly-a addition signal, and a dihydrofolate reductase (dhfr) expression cassette. this vector was inserted into the dxb-11 chinese hamster ovary (cho) cell line. the recombinant protein was exported by cho cells into the tissue culture media. at harvest the prorenin levels rang ...19901963533
inhibition by nitric oxide and nitric oxide-producing vasodilators of dna synthesis in vascular smooth muscle cells.effects of nitric oxide (no) and no-producing vasodilators such as glyceryl trinitrate and sodium nitroprusside were tested on dna synthesis in the clonal rat aortic smooth muscle cells, racs-1. dna synthesis was estimated by [3h]thymidine incorporation to dna. no and no-producing vasodilators inhibited the dna synthesis that was induced by 10% fetal calf serum. no and no-producing vasodilators also inhibited the basal level of dna synthesis that occurred possibly as a result of autocrine mechan ...19901963600
radiation-induced gene amplification in rodent and human cells.ionizing and uv radiations induce amplification of sv40 dna sequences integrated in the genome of chinese hamster cells and increase amplification of the dihydrofolate reductase (dhfr) gene during methotrexate selection in human skin fibroblasts of a patient with ataxia telangiectasia. by cell fusion experiments it could be shown that sv40 gene amplification is mediated by one or several diffusible trans-acting factors induced or activated in a dose dependent manner by all types of radiation. on ...19901965560
identification of dna topoisomerase-ii activity in terminally differentiated mammalian organs and in non-growing cultured cells.dna topoisomerase-ii activity was measured in a variety of rat organs and in two types of cultured mammalian cells at different stages of growth. the assay for enzyme activity is based on the ability of dna topoisomerase ii to catenate relaxed, circular double-stranded [3h]dna into huge networks of interlocked circles which can be selectively trapped on a nitrocellulose filter. this catenation requires atp and provides a sensitive, specific, and quantitative way to measure topoisomerase-ii activ ...19901966287
expression and amplification of cloned rat liver tyrosine aminotransferase in nonhepatic cells.a full-length cdna for the rat liver enzyme tyrosine aminotransferase has been used to construct mammalian expression vectors by recombinant dna techniques. these vectors, which have employed either a simian virus 40 or a rous sarcoma virus promoter, were transfected into a variety of nonhepatic mammalian cell lines in culture. transient expression of tyrosine aminotransferase was readily observed after transfection into monkey cos cells and mouse l cells. stable clones that express cloned tyros ...19901967611
isolation of anonymous, polymorphic dna fragments from human chromosome 22q12-qter.a series of 195 random chromosome 22-specific probes, equivalent to approximately 1% of the size of this chromosome, have been isolated from a chromosome 22-specific bacteriophage lambda genomic library. these probes were mapped to four different regions of chromosome 22 on a panel of five somatic cell hybrids. restriction fragment length polymorphisms were detected by 28 of the probes mapping to 22q12-qter. evolutionarily conserved sequences in human, mouse, and chinese hamster dna were detecte ...19901968030
cloning and expression of cdnas for polymorphic and monomorphic arylamine n-acetyltransferases from human liver.to elucidate the molecular basis of human n-acetylation polymorphism, cdna clones encoding human liver n-acetyltransferases (ec 2.3.1.5) were isolated from lambda gt10 cdna libraries using the 32p-labeled cdna of rabbit liver n-acetyltransferase recently cloned in this laboratory. three types of cdnas (d-14, o-7, and d-24) were isolated and their nucleotide sequences were determined, from which the amino acid sequences of human n-acetyltransferases were deduced. all the cdnas coded for 290 amino ...19901968463
radiosensitization by misonidazole, pimonidazole and azomycin and intracellular uptake in human tumour cell lines.the radiosensitization of two human tumour in vitro cell lines, ht-1080 and lovo, has been compared with that of the chinese hamster cell line v79-379a. although the two human tumour cell lines were more radiosensitive than the v79 cell line sensitizer, enhancement ratios for misonidazole, pimonidazole and azomycin were similar (relative to extracellular concentration) for all three cell lines. average intracellular concentrations of radiosensitizer were measured by high-performance liquid chrom ...19901968500
changes in the pancreatic a-, b- and d-cell populations during development of diabetes in spontaneously diabetic chinese hamsters of the asahikawa colony (chad).we investigated the pathological changes in pancreatic islets during the development of diabetes in spontaneously diabetic chinese hamsters of the asahikawa colony (chad), using morphometric analysis and specific immunocytochemical methods. we also investigated the relationships between changes in islet cell composition and the hormonal changes in the plasma and pancreas. plasma and pancreatic insulin levels were significantly lower in diabetic hamsters than in pre-diabetic hamsters. however, pl ...19901971211
transfection of a mutant regulatory subunit gene of camp-dependent protein kinase causes increased drug sensitivity and decreased expression of p-glycoprotein.wild-type chinese hamster ovary (cho) cells were transfected with a dna clone (mt-rev, site a) carrying a mouse gene for a dominant mutant regulatory subunit (ri) gene of camp-dependent protein kinase (pka) from s49 cells along with a marker for g418 resistance. g418-resistant transfectant clone r-2d1 was resistant to 8-br-camp-induced growth inhibition and morphological changes. the cells also did not phosphorylate a 50-kda protein after camp stimulation and had decreased pka activity, both cha ...19901971796
p-glycoprotein-independent mechanism of resistance to vp-16 in multidrug-resistant tumor cell lines: pharmacokinetic and photoaffinity labeling studies.the interaction of etoposide (vp-16), vinca alkaloids, and verapamil with the p-glycoprotein (p-gp) was studied in human breast (mcf-7) and chinese hamster lung (dc3f) cell lines and the corresponding multidrug-resistant mcf-7/adr and dc3f/adx tumor cell lines, selected for resistance to adriamycin and actinomycin d, respectively, and overexpressing p-gp. verapamil (10 microm) markedly reversed resistance to vincristine (11-fold in dc3f/adx and 125-fold in mcf-7/adr; 1-hr exposure), but it had a ...19901972771
gene for parathyroid hormone-like peptide is on mouse chromosome 6.the single-copy parathyroid hormone-like peptide gene (pthlh) was assigned to mouse chromosome 6 using a rat pthlh cdna as hybridization probe in the southern blot analysis of dnas isolated from a panel of mouse x chinese hamster cell hybrids. the mouse parathyroid hormone gene (pth) has previously been assigned to mouse chromosome 7 and the pthlh and pth genes have also been shown to be on different chromosomes in human and rat. therefore, despite significant amino-terminal sequence homology be ...19901973379
calibration of pulsed field gel electrophoresis for measurement of dna double-strand breaks.the pulsed field gel electrophoresis (pfge) assay was calibrated for the measurement of x-ray-induced dna double-strand breaks in chinese hamster ovary (cho) cells. calibration was conducted by incorporating [125i]deoxyuridine into dna, which induces one double-strand break for every disintegration that occurs in frozen cells. based on the percentage of the dna migrating into the gel, the number of breaks/dalton/gy was estimated to be (9.3 +/- 1.0) x 10(-12). this value is close to (10 to 12) x ...19901974573
identification of a protein altered in mutants resistant to microtubule inhibitors as a member of the major heat shock protein (hsp70) family.a major cellular protein (p2; approximately 70 kilodaltons) which is altered in chinese hamster ovary (cho) cell mutants resistant to the microtubule inhibitors colchicine and podophyllotoxin has been shown to correspond to the constitutive form of the 70-kilodalton heat shock protein (hsc70). the inference that p2 and hsc70 are the same protein is based on the following observations: (i) migration of p2 in two-dimensional polyacrylamide gels in the same position as that reported for hsc70; (ii) ...19901975944
rna pseudoknot domain of tobacco mosaic virus can functionally substitute for a poly(a) tail in plant and animal cells.the genomes of many rna viruses terminate in a tertiary structure similar to the l-conformation of trnas and this structure is recognized by many trna-specific enzymes such as aminoacyl-trna synthetase. virtually the entire 3'-untranslated region (utr) of tobacco mosaic virus (tmv) rna is involved in an extended tertiary structure containing, in addition to a trna-like structure, a pseudoknot domain that lies immediately upstream. although the functions of these structures are not well understoo ...19901976569
enhancement of radiosensitivity of cultured mammalian cells by neocarzinostatin. i. inhibition of the repair of sublethal damage.the enhancement of radiosensitivity by neocarzinostatin (ncs), an antitumour drug, was studied using three strains of cultured mammalian cells with different repair capabilities for sublethal damage. ncs enhanced the radiosensitivity of the cells when applied both during and after x-irradiation under aerobic conditions. the enhancement ratios of ncs during x-irradiation were 1.25, 1.27 and 1.38 for mouse lymphoma l5178y, chinese hamster v79 and mouse mammary tumour fm 3a cells, respectively. the ...19901976722
enhancement of radiosensitivity of cultured mammalian cells by neocarzinostatin. ii. fixation of potentially lethal damage.the effects of neocarzinostatin (ncs), an anti-tumour drug, on the repair of potentially lethal damage (pld) were studied using cultured chinese hamster v79, malignant human melanoma and mouse lymphoma l5178y cells in the stationary phase. the repair of pld was observed in the melanoma and l5178y cells but no such repair was observed in the v79 cells, when studied by delayed plating. ncs added to the culture medium immediately after x-irradiation evoked fixation of pld within 10 min of the addit ...19901976723
cloning of a chinese hamster protein homologous to the mouse t-complex protein tcp-1: structural similarity to the ubiquitous 'chaperonin' family of heat-shock proteins.the complete cdna sequence of a chinese hamster ovary cell protein, homologous to a mouse t-complex protein, tcp-1, has been determined. the deduced amino acid sequences of the mouse/chinese hamster tcp-1 proteins exhibit significant identity to the 60-65 kda heat shock 'chaperonin' family of proteins present in prokaryotes and in the eukaryotic cell organelles.19901977474
nucleotide sequence of mouse hsp60 (chaperonin, groel homolog) cdna.the cdna sequence of the 60 kda heat-shock protein from mouse 3t3 cells has been determined. the deduced amino acid sequence of mouse hsp60 protein differs from the corresponding proteins from chinese hamster and human cells in 7 and 13 residues, respectively, most of which are conservative replacements.19901979012
characterization of three distinct size classes of human 3-hydroxy-3-methylglutaryl coenzyme a reductase mrna: expression of the transcripts in hepatic and nonhepatic cells.3-hydroxy-3-methylglutaryl-coenzyme a (hmg-coa) reductase mrna is expressed in two highly differentiated human hepatoma cell lines, hepg2 and hep3b, at exceptionally high levels relative to human fetal liver and fibroblasts. blotting experiments revealed that the mrna consists of three major size classes of approximately 4.7, 4.5, and 4.2 kb that responded coordinately to agents that alter hmg-coa reductase activity. in view of the markedly elevated levels of reductase mrna in the hepatoma cell ...19901979742
evaluation of the mutagenicity of the anti-inflammatory drug salicylazosulfapyridine (sasp).salicylazosulfapyridine, commonly known as sulfasalazine or sasp, is an anti-inflammatory drug that is widely used in the treatment of diseases such as ulcerative colitis and crohn's disease. increases in sister chromatid exchanges (sce) and micronuclei (mn) frequencies have been reported in lymphocytes of patients maintained on sasp therapy for up to 21 months. we have tested sasp for its ability to induce chromosome aberrations (abs) and sce in cultured chinese hamster ovary (cho) cells, abs i ...19901979833
nucleotide sequences and novel structural features of human and chinese hamster hsp60 (chaperonin) gene families.a number of clones that specifically hybridize to the human hsp60 cdna (chaperonin protein; groel homolog) were isolated from human and chinese hamster ovary cell genomic libraries. dna sequence analysis shows that one of these clones, pgem-10, is completely homologous to the human hsp60 cdna (in both coding and noncoding regions) with no intervening sequences. the other human clones analyzed were all nonfunctional pseudogenes containing numerous small additions, deletions, and base substitution ...19901980192
genetic mapping of the gene for ca2+/calmodulin-dependent protein kinase iv (camk-4) to mouse chromosome 18.southern blot analysis of chinese hamster x mouse somatic cell hybrids was used to map the gene for a serine/threonine protein kinase expressed in brain and testis. this locus, termed camk-4, encodes ca2+/calmodulin-dependent protein kinase iv. progeny of an interspecific backcross were analyzed to position camk-4 in the centromeric region of chromosome 18 near two mutations known to affect neurological function and fertility. this raises the possibility that a defect in camk-4 may be responsibl ...19901981056
alpha 2-adrenergic agonists stimulate dna synthesis in chinese hamster lung fibroblasts transfected with a human alpha 2-adrenergic receptor gene.to test the hypothesis that agents activating receptors negatively coupled to adenylyl cyclase (ac) can stimulate cell proliferation, we have expressed a human alpha 2-adrenergic receptor (alpha 2-c10) in ccl39 cells and studied the effects of alpha 2-agonists on reinitiation of dna synthesis in quiescent cells. we report that the alpha 2-agonists epinephrine and clonidine stimulate [3h]-thymidine incorporation in synergy with fibroblast growth factor and that the alpha 2-antagonist yohimbine ef ...19901981685
microtubules, mitochondria, and molecular chaperones: a new hypothesis for in vivo assembly of microtubules.in chinese hamster ovary cells, a number of independent mutants selected for resistance to antimitotic drugs have been found to be specifically altered in two major cellular proteins, designated p1 (relative mass (mr) approximately 60-63 kilodaltons (kda] and p2 (mr approximately 69-70 kda), which appeared microtubule related by a number of genetic and biochemical criteria. antibodies to p1 have been found to bind specifically to mitochondria that showed specific association with microtubules in ...19901982213
evaluation of the genotoxicity of gentian violet in bacterial and mammalian cell systems.previous studies indicate that gentian violet (gv), a triphenylmethane dye used in agriculture and human medicine, is a clastogen in vitro and a carcinogen in chronically exposed mice and rats. data on its genotoxic activity, however, have been incomplete and partly contradictory. mutagenesis and dna damage experiments were conducted to re-evaluate the genotoxic potential of gv in both bacterial and mammalian cell systems. gv was mutagenic in salmonella typhimurium tester strains ta97 and ta104, ...19901982909
structural comparison of recombinant pulmonary surfactant protein sp-a derived from two human coding sequences: implications for the chain composition of natural human sp-a.the pulmonary surfactant-associated protein sp-a is encoded by presumably two different genes, resulting in slightly different amino acid sequences. both gene products were expressed in chinese hamster ovary cells. their macromolecular structure differed significantly. sp-a alpha 3 exhibited a much higher amount of tetrameric to hexameric structures than sp-a alpha 2, for which dimeric structures predominate. these differences may be caused by the higher expression rates of sp-a alpha 3 presumab ...19911986781
legionella pneumophila inhibits protein synthesis in chinese hamster ovary cells.legionella pneumophila is a gram-negative facultative intracellular parasite that causes legionnaires disease. to explore the interactions between l. pneumophila and host cells, we have developed a continuous cell line model of infection. we show that about 80% of chinese hamster ovary (cho) cells were associated with l. pneumophila after incubation for 3 h at a multiplicity of infection of 20 bacteria per cell. within 3 to 4 h of incubation with l. pneumophila, protein synthesis of cho cells wa ...19911987039
dna damage induced by 193-nm radiation in mammalian cells.the contribution of dna damage to the effects of 193-nm excimer laser radiation on mammalian cells in culture was studied in order to evaluate the mutagenic potential of this uv wavelength in vivo. two approaches were taken: measurement of pyrimidine dimer-specific endonuclease-sensitive sites/megabase and comparison of the 193-nm radiation-induced cytotoxicity in normal versus dna repair-deficient cells. the formation of pyrimidine dimer-specific endonuclease-sensitive sites/megabase was invers ...19911988091
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