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species-specific restriction of complement by hrf20 (cd59) generated by cdna transfection.the 20-kda homologous restriction factor (hrf20, cd59) is a phosphatidyl inositol-anchored membrane glycoprotein that inhibits the formation of human complement membrane attack complexes. the cdna of hrf20 was transfected into chinese hamster ovary (cho) cells resulting in expression of human hrf20 protein on the cell surface anchored via glycosylphosphatidyl inositol. the transfected cho cells were resistant to human complement-mediated cell killing. however, the cells remained sensitive to rat ...19921378024
highly sensitive enzyme-linked immunosorbent assay for marograstim (kw-2228), a mutant of human granulocyte colony-stimulating factor.an enzyme-linked immunosorbent assay (elisa) for marograstim (kw-2228) was established. this elisa proved to be highly sensitive with the detection limit of 0.01 ng/ml (about 0.5 fmol/ml) of kw-2228 and the assay range between 0.01 and 2 ng/ml. when 0.02 to 2 ng/ml of kw-2228 added to human plasma was determined, the variation coefficiencies of intra-day and inter-day assays were 0.4 to 7.6% and 5.2 to 15.8%, respectively, with good recoveries. these results indicate that this elisa will be appl ...19921378090
inhibition of transcription and strand-specific dna repair by alpha-amanitin in chinese hamster ovary cells.recent studies have shown preferential repair of uv-induced cyclobutane pyrimidine dimers (cpd) in the transcribed strand of the expressed dihydrofolate reductase (dhfr) gene in human and rodent cells. we have tested the hypothesis that the strand-specific repair of such transcription-blocking lesions is dependent upon concurrent transcription. chinese hamster ovary (cho) b11 cells with an amplified dhfr gene were treated with alpha-amanitin before irradiation with uv (254 nm) and during post-ir ...19921378211
expression of soluble isoforms of rat cd45. analysis by electron microscopy and use in epitope mapping of anti-cd45r monoclonal antibodies.the cd45 or leucocyte-common antigens are encoded by a single gene but can be found in various forms due to alternative splicing of three exons near the 5' end of the gene. the cd45 antigens are major glycoproteins of all types of leucocytes. monoclonal antibodies recognizing restricted epitopes of cd45 have been used to distinguish phenotypic and functional subsets of lymphocytes. to facilitate epitope mapping and biochemical studies, we have expressed the extracellular portions for four differ ...19921378817
in vitro and in vivo mutagenicity studies on sporidesmin, the toxin associated with facial eczema in ruminants.sporidesmin, a fungal toxin with widespread distribution within new zealand, is thought to exert toxic effects through oxidative damage. the purified chemical was tested for its ability to cause point mutations in four strains of salmonella typhimurium (ta98, ta100, ta102 and ta1537), in the presence and absence of exogenous metabolic activation. although toxic effects were seen at concentrations exceeding 400 mu gl/plate, there were no significant increases in revertant colonies. in strain ta10 ...19921379325
comparative investigation of cyclophosphamide action on bone marrow cells of the armenian hamster and 4 other species of rodents.we studied the clastogenic action of cyclophosphamide (cp) on bone marrow cells of the armenian hamster (ah), cricetulus migratorius. cp induced a dose-dependent linear increase in aberrant cells. the maximal cytogenetic action was observed 12 h after cp treatment. male and female ahs were similarly sensitive to the clastogenic action of cp. we compared cp clastogenicity at a dose of 25 mg/kg on bone marrow cells of ahs, mice, rats, guinea pigs and chinese hamsters 24 h after treatment. we obser ...19921379326
clastogenicity of low ph to various cultured mammalian cells.it has been reported that low ph itself can be clastogenic to chinese hamster ovary cells or mouse lymphoma l5178y cells. on the other hand, there was no indication that low ph is clastogenic to rat or human lymphocytes. therefore, in order to evaluate the generality of clastogenicity of low ph conditions, chromosomal aberration tests were carried out on chinese hamster cell line cells (cho-k1, chl, don and v79 379a) and human cells (hela and peripheral lymphocytes used as whole-blood cultures). ...19921379335
monoclonal antibodies against defined epitopes of the human transferrin receptor cytoplasmic tail.three murine monoclonal antibodies (mabs) against the 61-residue amino-terminal cytoplasmic tail of the human transferrin receptor (tr) have been produced by immunization of mice with recombinant human tr produced in a baculovirus expression system. mutant human trs expressed in chick embryo fibroblasts (cefs) with point mutations or deletions in their cytoplasmic tails have been used to map the epitopes defined by each of the mabs. one mab, h68.4, previously shown to block receptor internalizat ...19921379471
a naturally occurring secreted form of fibroblast growth factor (fgf) receptor 1 binds basic fgf in preference over acidic fgf.alternatively spliced variants of fibroblast growth factor receptor 1 mrna are predicted to encode secreted forms and membrane-bound forms of receptors. the predicted amino acid sequences of these receptor variants differ in a portion of the extracellular region. in this study, we characterized the function of one of these splice variants which was predicted by its cdna to be a secreted fgf receptor. we expressed this secreted form of the human fgfr1 (sfgfr1) in chinese hamster ovary cells. the ...19921379591
the rat angiotensin ii at1a receptor couples with three different signal transduction pathways.to examine whether the subpopulation of the rat type 1 angiotensin ii (aii) receptor (at1a) couples with a single or multiple signal transduction pathways, we constructed chinese hamster ovary (cho) cell lines producing the recombinant receptor. the expressed at1a receptor exhibits typical pharmacological characteristics of the at1 receptor, known to mediate the main physiological function of aii. addition of aii to the cho cells induced a rapid, transient increase in intracellular free ca2+ con ...19921379799
human recombinant soluble decay accelerating factor inhibits complement activation in vitro and in vivo.complement plays a role in activating the inflammatory response and has been implicated in the pathogenesis of some inflammatory diseases. with a view toward controlling unwanted c activation, we evaluated the c regulator, human decay accelerating factor (daf). three forms of recombinant daf were purified from transfected chinese hamster ovary cells: glycophosphatidylinositol (gpi)-linked membrane daf (mdaf) extracted from cell membranes; spontaneously shed soluble daf (sdaf) derived from mdaf; ...19921380537
increased sensitivity of a chinese hamster ovary cell line to alkylating agents after overexpression of the human metallothionein ii-a gene.the elevation of intracellular levels of metallothionein has been associated with the development of resistance to the cytotoxic effects of some alkylating agents. in order to study the mechanisms underlying metallothionein associated drug resistance we transfected the alkylating agent sensitive cho cell line mmc-1 (robson et al., 1985) with an episomally replicating plasmid coding for the human metallothionein ii-a gene. two transfectants were isolated which carried about 10 copies of the plasm ...19921380651
homologous recombination of adenovirus dna in mammalian cells: enhanced recombination following uv-irradiation of the virus.we have used adenovirus as a molecular probe to examine the recombination of viral dna following infection of mammalian cells. the technique gives a quantitative measure of homologous recombination between adenovirus type 2 (ad2) and ad5pymtr3. ad5pymtr3 is an insertion mutant of ad5 containing polyoma virus (py) dna inserted into a deleted e1 region of the ad5 genome. cells were coinfected with ad2 and ad5pymtr3 and at an appropriate time after infection, viral dna was extracted from the infect ...19921380653
differential gene expression in wild-type and x-ray-sensitive mutants of chinese hamster ovary cell lines.complementary dna cloning, differential screening and northern hybridization techniques were used to study differential gene expression in the wild-type chinese hamster ovary (cho) k1 cell line and its two x-ray sensitive mutants, xrs-5 and xrs-6. 11 species of mrnas were found underexpressed in the two independently isolated mutants. the steady-state levels of those mrnas are 3-26-fold less in the two mutants, depending on the particular species. 6 of the underexpressed mrnas have been identifi ...19921380656
induction of chromosomal damage in mammalian cells in vitro and in vivo by sulfapyridine or 5-aminosalicylic acid.sulfapyridine (sp) and 5-aminosalicylic acid (5-asa) are the two primary metabolites of the anti-inflammatory drug salicylazosulfapyridine (sasp). these two metabolites were studied for induction of chromosomal damage in mammalian cells, in vitro and in vivo, in an attempt to understand better the genetic effects produced by sasp in humans and laboratory mice. to this end, sp and 5-asa were tested for induction of sister-chromatid exchanges (sce) and chromosomal aberrations (abs) in chinese hams ...19921380664
review of the genotoxicity of ozone.ozone is a powerful oxidant, reactive to biomolecules. in aqueous solution it decomposes to give hydrogen peroxide, superoxide and hydroxy radicals which can take part in secondary reactions. ozone is a disinfectant that inactivates both viruses and bacteria. although other reactions are primarily responsible for the inactivation, cellular dna is also damaged. ozone is genotoxic to microorganisms, plants and cell cultures in vitro. the results from in vivo cytogenetic studies with laboratory ani ...19921381051
right-angle light scattering to assay basal and regulated plasma membrane cl- conductances.we describe a simple and rapid technique for assaying both constitutive and regulated plasma membrane cl- conductances. the method uses right-angle light scattering to measure the rate of swelling of cells in suspension, in which the anion conductance is rate limiting for swelling, due to introduction of high plasma membrane cation conductance using gramicidin. the technique was verified using chinese hamster ovary cells and mouse l cells, both stably transfected with the cystic fibrosis transme ...19921381149
sequences and expression of alleles of polymorphic arylamine n-acetyltransferase of human liver.fifty human livers obtained at autopsy were analyzed for n-acetyltransferase and classified into six genotypes. determination of n-acetyltransferase activity and proteins from supernatants of liver homogenates indicate that genotype i corresponds to rapid acetylator, genotypes ii and iii to intermediate acetylator, and genotypes iv, v, and vi to slow acetylator phenotypes. northern blot analysis shows that levels of mrna for n-acetyltransferase in the livers do not markedly differ among the six ...19921381364
forward mutations and dna-protein crosslinks induced by ammonium metavanadate in cultured mammalian cells.ammonium metavanadate yielded a dose-dependent increase in mutation frequency at the v79 hprt locus following a 24-h exposure period in serum-free f12 medium. vanadate also increased the mutation frequency of v79 cells by exposure of cells in salts-glucose medium, but these effects were not as striking, or as dose-dependent as they were in serum-free f12 medium. ammonium metavanadate enhanced the mutation frequency in a v79 variant containing a transfected bacterial gpt gene. these cells are kno ...19921381466
enhancing effects of heterocyclic amines and beta-carbolines on the induction of chromosome aberrations in cultured mammalian cells.the effects of post-treatment with heterocyclic amines and beta-carbolines on the induction of chromosome aberrations were studied in chinese hamster cho k-1 cells and sv40-transformed excision repair-deficient human xp2ossv cells. the number of chromosome aberrations induced by uv and mmc were increased by post-treatment with trp-p-1 and trp-p-2, in both the presence and the absence of s9 mix. a alpha c, mea alpha c, glu-p-1, glu-p-2, iq, meiq, harman and harmine increased chromosome aberration ...19921381474
the effect of gamma-irradiation on the toxicity of malathion in v79 chinese hamster cells and molt-4 human lymphocytes.there is growing interest in the irradiation of food and agricultural products for insect disinfestation, sprout inhibition, delayed ripening and the reduction of microbiological loads. extensive research has been done on this process, and irradiation to a maximum dose of 10 kgy is recognized as safe by national and international regulatory agencies. the question has been raised, however, whether irradiation of pesticide residues might produce radiation products that were more toxic or less toxi ...19921381482
genotoxicity assessment of pirmenol, a new antiarrhythmic drug.the genotoxicity of pirmenol was tested in the e. coli and s. typhimurium mutagenesis assay, an in vitro mammalian cell chromosome-aberration assay and an in vivo mouse micronucleus assay. the e. coli tester strain wp2s was exposed to concentrations of pirmenol as high as 10,000 micrograms/plate both in the absence (s9-) and presence (s9+) of metabolic activation. five strains of s. typhimurium (ta98, ta100, ta1535, ta1537, ta1538) were exposed to concentrations of pirmenol as high as 5000 micro ...19921381484
molecular weights of glycosylated and nonglycosylated forms of recombinant human stem cell factor determined by low-angle laser light scattering.the molecular weight of recombinant human stem cell factor (scf) was determined using a low-angle laser light scattering combined with a differential refractometer and a uv detector. the protein samples were applied to these detectors through a gel filtration column by a high-performance liquid chromatographic pump. the chinese hamster ovary (cho) cell-derived scf gave a molecular weight of 53,000 for the entire molecule and 35,000 for the protein moiety only at ph 7.0, indicating that the cho c ...19921381876
post-translational processing of membrane-associated recombinant human stem cell factor expressed in chinese hamster ovary cells.this report describes the structure of soluble human stem cell factor isolated from the conditioned medium of chinese hamster ovary (cho) cells transfected with stem cell factor (scf) cdna, which encodes a leader sequence plus 248 additional amino acids. the 248 amino acids include a hydrophobic transmembrane region at positions 190-212. the isolated material is glycosylated and three bands (apparent m(r) 28,000, m(r) 35,000, and m(r) 40,000) are evident by sodium dodecyl sulfate (sds)-polyacryl ...19921381905
high level expression on a chimeric anti-ganglioside gd2 antibody: genomic kappa sequences improve expression in cos and cho cells.we report a flexible strategy for the high level expression of a recombinant human monoclonal antibody (mab) in chinese hamster ovary (cho) cells, initially using cos monkey kidney cell transfections to evaluate rapidly modifications to immunoglobulin (ig) dna constructs. using sequential transfections with two amplifiable markers, we generated cho cell lines and clones that secrete 80-110 micrograms/10(6) cells/24 hours of a mouse-human chimeric igg1 kappa mab. this cellular productivity is con ...19921382457
novel sulfated ligands for the cell adhesion molecule e-selectin revealed by the neoglycolipid technology among o-linked oligosaccharides on an ovarian cystadenoma glycoprotein.e-selectin is the inducible adhesion protein on the surface of endothelial cells which has a crucial role in the initial stages of recruitment of leucocytes to sites of inflammation. in addition, it is almost certainly involved in tumor cell adhesion and metastasis. this report is concerned with identification of a new class of oligosaccharide ligand--sulfate-containing--for the human e-selectin molecule from among oligosaccharides on an ovarian cystadenoma glycoprotein. this has been achieved b ...19921382586
normal human erythrocytes express cd36, an adhesion molecule of monocytes, platelets, and endothelial cells.we have recently shown that rosetting of plasmodium falciparum (mc r+ line)-infected erythrocytes (parasitized red blood cells [prbcs]) with uninfected erythrocytes (rbcs) is blocked by coating of the rbcs with anti-cd36 monoclonal antibodies (moabs; handunnetti et al, blood 80:2097, 1992). adult rbcs have previously been considered negative for cd36. however, using fluorescence-activated cell sorter analysis with the anti-cd36 moabs 8a6, okm5, and okm8, which reverse rosetting, we consistently ...19921382721
production and secretion in cho cells of the extracellular domain of amog/beta 2, a type-ii membrane protein.a hybrid gene consisting of the sequences coding for the signal peptide and n terminus of a type-i membrane protein, the neural cell adhesion molecule (n-cam), and the extracellular domain of the adhesion molecule on glia (amog/beta 2), a type-ii membrane protein, was constructed. the sequence was inserted into a eukaryotic expression vector containing the human cytomegalovirus promoter and the glutamine synthetase selection marker, and used to transfect chinese hamster ovary cells. the resultin ...19921383096
biochemical characterization of 25 distinct carcinoembryonic antigen (cea) epitopes recognized by 57 monoclonal antibodies and categorized into seven groups in terms of domain structure of the cea molecule.the chemical nature of 25 distinct carcinoembryonic antigen (cea) epitopes, which were recognized by 57 different monoclonal antibodies and categorized into 7 groups (groups a to g) in terms of domain structure of the cea molecule, was analyzed and the findings obtained were compared with the results of our previous studies using recombinant cea proteins. all 21 epitopes of groups a to f defined by 48 mabs were resistant to periodate oxidation and were to a greater or lesser extent retained afte ...19921383122
a potent enhancer made of clustered liver-specific elements in the transcription control sequences of human alpha 1-microglobulin/bikunin gene.alpha 1-microglobulin (a1m) and bikunin are plasma proteins which are present both as free molecules and as complexes with either iga heavy chains for a1m or the h1, h2, and h3 heavy chains of the inter-alpha-inhibitor family for bikunin. mature a1m and bikunin originate from the cleavage of an a1m/bikunin precursor (abp) synthesized from a single gene with liver-specific expression. five kilobases of the 5'-flanking region of the human abp gene were sequenced. deletion mutants of this region su ...19921383209
mapping of epitopes, glycosylation sites, and complement regulatory domains in human decay accelerating factor.decay accelerating factor (daf, cd55) is a glycophospholipid-anchored membrane protein that protects cells from complement-mediated damage by inhibiting the formation and accelerating the decay of c3/c5 convertases. daf deletion mutants lacking each of the four short consensus repeats (scr) or the serine/threonine-rich region (s/t) were created by site-directed mutagenesis. these deletion mutants were expressed by stable transfection in chinese hamster ovary cells for the purpose of mapping impo ...19921383332
characterization of the binding of a potent, selective, radioiodinated antagonist to the human neurokinin-1 receptor.we have synthesized a potent, selective, radioiodinated antagonist of the human neurokinin-1 (nk1) receptor and have characterized its binding to the cloned receptor expressed in chinese hamster ovary cells. (cis)-2-(diphenylmethyl)-n-[(2-iodophenyl)-methyl]-1- azabicyclo[2.2.2]octan-3-amine (l-703606) inhibits binding of 125i-tyr8-substance p to the human nk1 receptor with an ic50 of 2 nm. this compound is a competitive antagonist of substance p-induced inositol phosphate generation, with a kb ...19921383685
dna base sequence changes in spontaneous and ethyl methanesulfonate-induced mutations of a chromosomally-integrated gene in chinese hamster ovary cells.a series of spontaneous and ethyl methanesulfonate-induced 6-thioguanine-resistant mutants were isolated in the cho-10t5 cell line. this cell line was constructed by the introduction of a shuttle vector containing the escherichia coli gpt gene into a hypoxanthine-guanine phosphoribosyltransferase deficient derivative of the chinese hamster cell line cho-k1. shuttle vector sequences were recovered from many of the mutant cell lines by the cos cell fusion technique and the dna base sequence of the ...19921383728
genotoxicities of nitropyrenes and their modulation by apigenin, tannic acid, ellagic acid and indole-3-carbinol in the salmonella and cho systems.four naturally occurring compounds, indole-3-carbinol (i3c), apigenin (api), ellagic acid (ea) and tannic acid (ta), were tested for their inhibitory effects against 1-nitropyrene- (1-np) or 1,6-dinitropyrene (1,6-dnp)-induced genotoxicity in salmonella tester strains and chinese hamster ovary (cho) cells. api and ta strongly inhibited the bacterial mutagenesis induced by nitropyrenes, while i3c and ea had little or no effect. for example, in ta98, 0.2 mumole api resulted in 48% and 56% inhibiti ...19921383740
rabbit very low density lipoprotein receptor: a low density lipoprotein receptor-like protein with distinct ligand specificity.a cdna that expresses a receptor for very low density lipoprotein (vldl) was isolated from a rabbit heart cdna library and characterized. the deduced amino acid sequence of the cdna revealed that the cdna encodes a protein with striking homology to the low density lipoprotein (ldl) receptor. like the ldl receptor, the mature protein consists of the following five domains spanning 846 amino acids: 328 n-terminal amino acids including an 8-fold repeat of 40 amino acids homologous to the ligand bin ...19921384047
transfection of the escherichia coli nth gene into radiosensitive chinese hamster cells: effects on sensitivity to radiation, hydrogen peroxide, and bleomycin sulfate.the escherichia coli nth gene encodes endonuclease iii, which catalyses the glycolytic removal of various oxidized thymine residues from dna. a truncated version of nth, with the prokaryotic regulatory sequences removed, was ligated into the retrovirus-based vector pzipneosv(x)1 and transfected into the radiosensitive chinese hamster ovary cell line, xrs7. following selection with g418, two clones (x7nth1 and x7nth6) were shown by southern analysis to contain the nth gene. no substantial differe ...19921384080
characterization of a bifunctional peptidylglycine alpha-amidating enzyme expressed in chinese hamster ovary cells.peptidylglycine alpha-amidating enzyme (alpha-ae) catalyzes the conversion of glycine-extended prohormones to their biologically active alpha-amidated forms. we have derived a clonal chinese hamster ovary cell line that secretes significant quantities of active alpha-ae. enzyme production was increased by selection for methotrexate-resistant cells expressing a dicistronic message. amplification of the alpha-ae gene was monitored by southern blot analysis, enzyme activity, and immunoreactive prot ...19921384431
rat cystathionine beta-synthase: expression of four alternatively spliced isoforms in transfected cultured cells.the gene for rat cystathionine beta-synthase consists of 17 exons. its transcripts are alternatively spliced, forming four distinct mrna species. type iii consists of exons 1 through 12, 14, 15, and 17; type i also contains exon 16. the open reading frame of type iv spans exons 1-->13; type ii, 3-->13. we cloned the corresponding cdnas into appropriate expression vectors and inserted the constructs into escherichia coli (i, iii, and iv) and chinese hamster (ch) cells (i through iv); all sequence ...19921384433
excessive production of transforming growth-factor beta 1 can play an important role in the development of tumorigenesis by its action for angiogenesis: validity of neutralizing antibodies to block tumor growth.angiogenesis is an important part of tumor growth in vivo. we used the transfected chinese hamster ovary (cho) cells that overproduced recombinant transforming growth-factor beta 1 (tgf-beta 1) to examine the possible role of this factor in tumor growth and angiogenesis in a nude mouse model. the in-vitro proliferation of tgf-beta 1-transfected cho cells was unaffected by the treatment of either recombinant tgf-beta 1 or an anti-tgf-beta 1 antibody. the tgf-beta 1-transfected cells grew more rap ...19921384712
cd59 molecule: a second ligand for cd2 in t cell adhesion.the t cell surface molecule cd2 forms, with its counter-receptor cd58 (lfa-3), a powerful adhesion/activation pathway. there is some evidence that cd2 might bind more than a single ligand. chinese hamster ovary cells (cho) expressing human cd59 after cdna transfection (cd59+cho) form rosettes with human t cells; these rosettes are inhibited in a dose-dependent fashion by the cd59 monoclonal antibody (mab) h19 and by the cd2 mab o275 known to block natural rosettes, but not by the cd2r mab d66, a ...19921385156
genotoxicity studies in vitro and in vivo on carminic acid (natural red 4).the potential genotoxic activity of carminic acid (cas no. 1260-17-9; einecs no. 215-023-3; c.i. no. 75410), a component of natural red colouring products (cochineal: cas no. 1343-78-8; einecs no. 215-680-6; c.i. no. 75470), used in food, cosmetics and drugs, has been evaluated by means of a series of short-term tests in vitro and in vivo, namely salmonella reverse mutation, chromosome aberrations and sister chromatid exchanges in vitro on chinese hamster ovary cells, and the mouse micronucleus ...19921385283
n-glycosylation is required for human cd2 immunoadhesion functions.the t-lymphocyte glycoprotein receptor, cd2, mediates cell-cell adhesion by binding to the surface molecule cd58 (lfa-3) on many cell types including antigen presenting cells. two domains comprise the cd2 extracellular segment, with all adhesion functions localized to the amino-terminal domain that contains a single n-glycosylation site at asn65. we have defined an important role for the n-linked glycans attached to asn65 of this domain in mediating cd2-cd58 interactions and also characterize it ...19921385399
expression and function of irs-1 in insulin signal transmission.irs-1 is a major insulin receptor substrate which may play an important role in insulin signal transmission. the mrna for irs-1 in rat cells and tissues is about 9.5 kilobases (kb). rat liver irs-1 was stably expressed in chinese hamster ovary (cho) cells (cho/irs-1). although its calculated molecular mass is 131 kda, irs-1 from quiescent cells migrated between 165 and 170 kda during sodium dodecyl sulfate-polyacrylamide gel electrophoresis. irs-1 was phosphorylated strongly on serine residues a ...19921385403
growth hormone (gh) induction of tyrosine phosphorylation and activation of mitogen-activated protein kinases in cells transfected with rat gh receptor cdna.the mechanism of growth hormone (gh) action was studied in chinese hamster ovary (cho) cells transfected with gh receptor cdna. cytosolic extracts from gh- or phorbol ester (12-o-tetradecanoyl 4 beta-phorbol 13-acetate)-treated cells, transfected with full-length gh receptor cdna, had an enhanced ability to phosphorylate myelin basic protein. myelin basic protein, a substrate for mitogen-activated protein (map) kinase, was maximally phosphorylated using extracts from cells treated with 50 nm bov ...19921385420
b7 costimulates proliferation of cd4-8+ t lymphocytes but is not required for the deletion of immature cd4+8+ thymocytes.in addition to tcr-derived signals, costimulatory signals derived from stimulation of the cd28 molecule by its natural ligand, b7, have been shown to be required for cd4+8- t cell activation. we investigate the ability of b7 to provide costimulatory signals necessary to drive proliferation and differentiation of virgin cd4-8+ t-cells that express a transgenic tcr specific for the male (h-y) ag presented by h-2db class i mhc molecules. virgin male-specific cd4-8+ t cells can be activated either w ...19921385518
superantigen and hla-dr ligation induce phospholipase-c gamma 1 activation in class ii+ t cells.bacterial enterotoxin superantigens bind directly to hla class ii molecules (hla-dr) expressed on both apc and activated human t cells, and simultaneously bind to certain v beta chains of the tcr. in this report, we compared early t cell signaling events in human alloantigen-stimulated t cells when activated by hla-dr ligation through antibody cross-linking or by direct enterotoxin superantigen binding. both types of stimuli induced tyrosine phosphorylation of phosphatidylinositol-specific phosp ...19921385526
coupled expression of ca2+ transport atpase and a dihydrofolate reductase selectable marker in a mammalian cell system.stable expression of a full-length cdna encoding chicken fast muscle ca2+ transport atpase was obtained in a chinese hamster lung cell line (dc-3f), using a dual-promoter expression vector (ph beta fcaa3) in which the atpase was cloned downstream of a human beta-actin gene promoter, and a mutant dihydrofolate reductase cdna (a3/dhfr) was cloned downstream of an sv40 promoter-enhancer. owing to its essentially normal catalytic activity and modest (20-fold) resistance to the antifolate methotrexat ...19921385939
human cyclin b1 gene (ccnb1) assigned to chromosome 5 (q13-qter).cyclins play an important role in cell cycle regulation. at least five classes of cyclins have been identified--a, b, c, d, and e. b cyclins are generally of two types in most organisms--b1 and b2. we have mapped the gene for human cyclin b1 (ccnb1) to human chromosome 5 (region q13-qter) by southern blot analysis of human x chinese hamster somatic cell hybrid panels. many more cyclin b-related sequences have been identified in the mouse (cycb-1 to cycb-10) and have been mapped to chromosomes 4, ...19921386686
high-level stable expression of recombinant 5-ht1a 5-hydroxytryptamine receptors in chinese hamster ovary cells.the human 5-hydroxytryptamine 5-ht1a receptor gene was transfected into chinese hamster ovary cells. a series of recombinant monoclonal cell lines expressing the receptor were isolated and the properties of one cell line that expressed receptors at a high level (2.8 pmol/mg) were studied in detail. in ligand binding assays with the selective 5-ht1a receptor agonist 2-(nn-di[3h]propylamino)-8-hydroxy-1,2,3,4-tetrahydronaphthalene ([3h]8-oh-dpat) only a single class of saturable high-affinity bind ...19921386736
the asparagine-linked oligosaccharides on tissue factor pathway inhibitor terminate with so4-4galnac beta 1, 4glcnac beta 1,2 mana alpha.tissue factor pathway inhibitor (tfpi) produced by endothelial cells contains sulfated asn-linked oligosaccharides. we have determined that greater than 70% of the oligosaccharides on recombinant tfpi expressed in 293 cells terminate with the sequence so4-4galnac beta 1, 4glcnac beta 1, 2man alpha. oligosaccharides terminating with this sequence have previously been described on lutropin, thyrotropin, and pro-opiomelanocortin: glycoproteins synthesized in the anterior pituitary. a galnac-transfe ...19921388166
evidence that the scavenger receptor is not involved in the uptake of negatively charged liposomes by cells.scavenger receptors have a broad ligand specificity, ranging from modified low-density lipoproteins to a variety of high-molecular-weight poly-anions. a recent report by nishikawa et al. (j. biol. chem. (1990) 265, 5226-5231) suggested that this receptor is also involved in the binding and endocytosis of liposomes containing negatively charged phospholipids. the mechanism by which liposomes are taken up by cells is of interest because liposomes are promising versatile carriers for macromolecules ...19921390854
experimental evidence for the involvement of the cytoskeleton in mammalian cell electropermeabilization.chinese hamster ovary (cho) cells and human erythrocytes were pulsed by using square-wave electric-field pulses. this treatment induced their permeabilization. this phenomenon appears to be a three-step process of creation, expansion and annihilation of permeated structures. altering the cell cytoskeleton, either with drugs, such as colchicine, known to depolymerise the microtubules in cho cells, or by high temperature shock to affect the spectrin-actin network in erythrocytes, induced no modifi ...19921390863
biochemical properties of recombinant mutants of nonglycosylated single chain urokinase-type plasminogen activator.the role of glycosylation on the enzymatic properties of single chain urokinase-type plasminogen activator (scu-pa) was investigated by site-specific mutagenesis of the glycosylated asn-302 residu to gln. in addition, the role of the nh2-terminal polypeptide chain and of the cys-148 to cys-279 interchain disulphide bond on the activity of non-glycosylated scu-pa was investigated. therefore, variants of recombinant scu-pa (rscu-pa) were produced by transfecting chinese hamster ovary cells with cd ...19921390910
lethality, dna alkylation, and cell cycle effects of adozelesin (u-73975) on rodent and human cells.adozelesin (u-73975) is an extremely potent cytotoxic agent which causes 90% lethality, after 2 h exposure in vitro, of chinese hamster ovary and lung (cho and v79), mouse melanoma (b16), and human ovarian carcinoma (a2780) cells at 0.33, 0.19, 0.2, and 0.025 ng/ml, respectively. under similar conditions, adriamycin and cisplatin had 90% lethality values in cho cells of 150 ng/ml (= 249 nm) and 6800 ng/ml (= 2266 nm), respectively. the relative drug sensitivity of the cell lines (a2780 > v79, b1 ...19921394193
chromosomal breakage following treatment of cho-k1 cells in vitro with u-68,553b is due to induction of undercondensation of heterochromatin.preferential breakage of chromosomes at specific sites (so-called "fragile sites") has been observed to occur spontaneously, and has been induced by some metal salts and chemicals. furthermore, a heterochromatic region of the long arm of the chinese hamster ovary (cho) x-chromosome is known to be susceptible to a disproportionately high frequency of spontaneous breakage; unless there is physical displacement of chromatin the resulting achromatic lesions are not scored as structural aberrations. ...19921396608
the effect of intravenous recombinant human renin on blood pressure in pithed spontaneously hypertensive rats.the effect of highly purified recombinant human renin (rh-renin), expressed in chinese hamster ovary cells, on mean blood pressure (mbp) was evaluated in pithed spontaneously hypertensive rats (shr) and wistar-kyoto rats (wky). intravenous bolus injection of rh-renin produced dose-dependent increases in mbp in pithed shr and wky. the pressor response to rh-renin in pithed shr was about 3 times as potent as that in pithed wky. intravenous infusion of rh-renin produced dose-dependent progressive i ...19921396991
laminin on toxoplasma gondii mediates parasite binding to the beta 1 integrin receptor alpha 6 beta 1 on human foreskin fibroblasts and chinese hamster ovary cells.we investigated the role of parasite-bound laminin and the host cell beta 1 integrin receptors for this extracellular matrix protein in toxoplasma gondii binding to fibroblasts. laminin but not fibronectin was detected on extracellular tachyzoites by immunofluorescence and immunoblotting. binding of parasites to cho cells was inhibited by polyclonal antibodies to laminin and by a monoclonal antibody directed against the globular carboxyl-terminal portion of the long arm of laminin (at or near th ...19921399003
heterogeneity of 5-fluorouracil radiosensitivity modulation in cultured mammalian cell lines.there is ample evidence that 5-fluorouracil (5-fu) improves both local control and survival of a variety of gastrointestinal tumors when added to radiotherapy. however, the modulation of radiosensitivity by 5-fu is incompletely understood and some reports are apparently contradictory. therefore, we have reevaluated the modulation of radiosensitivity by 5-fu in a variety of mammalian cells. ht-29 and widr (human colon adenocarcinoma), du-145 (human prostate adenocarcinoma), v-79 (chinese hamster ...19921399739
incidence of toxigenic vibrios in foods available in taiwan.a total of 1088 vibrios and related species were isolated from seafood and aquacultured foods available in taiwan. they were identified as vibrio alginolyticus, v. cholerae, v. fluvialis i, v. fluvialis ii, v. parahaemolyticus, v. mimicus, aeromonas caviae, a. hydrophila, a. sobria and other species. incidence of these vibrio and aeromonas species in these foods was high. vibrio parahaemolyticus was frequently found in seawater and in foods of freshwater origin. the vibrio isolates were examined ...19921399913
human plasma lipoproteins regulate apolipoprotein e secretion from a post-golgi compartment.the molecular regulation of apolipoprotein e (apoe) synthesis and secretion is incompletely understood. in this study, we have examined the effect of human low density lipoprotein (ldl) on apoe mrna and protein levels in hepg2 and other eukaryotic cells. exposing hepg2 cells to ldl for times up to 4 h resulted in an increase in 35s-labeled apoe accumulation in the medium by 2.2-fold, relative to serum free controls (n = 10, p < 0.001), with no changes in apoe mrna levels. similar observations ha ...19921400506
molecular analyses of a human sex hormone-binding globulin variant: evidence for an additional carbohydrate chain.genomic dna was isolated from an individual who is homozygous for a sex hormone-binding globulin (shbg) variant that resolves into three molecular weight forms of 56k, 52k, and 48k during electrophoresis under denaturing conditions (sodium dodecyl sulfate-polyacrylamide gel electrophoresis). this material was amplified using intron-specific oligonucleotide primers in a polymerase chain reaction to obtain the eight exons encoding shbg. sequence analysis of these exons revealed a point mutation en ...19921400872
biochemical characterization of recombinant human nerve growth factor.recombinant human nerve growth factor (rhngf) was expressed and secreted by chinese hamster ovary cells and purified to homogeneity using ion-exchange and reversed-phase (rp) chromatography. the isolated product was shown to be consistent with a 120-amino-acid residue polypeptide chain by amino acid composition, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (sds-page), rp-hplc, and mass spectrometry and with an n-terminal sequence consistent with that expected from the cdna for human ...19921402913
a retroviral sequence of the chinese hamster ovary cell line.a partial cdna (b52) molecule with the characteristics of retroviral sequences was isolated from the chinese hamster ovary (cho) k1 cell line. the b52 cdna contains 1184 nucleotides. the first 452 nucleotides (nt) are 71% homologous to the env gene of moloney murine leukemia virus (mmlv) and murine endogenous retroviruses. the 139 amino acids predicted from the 452 nt have 82% homology with the carboxy-terminal amino acids of the env protein of mmlv. the remaining 732 nt have several features of ...19921408151
gene transfer of a reserpine-sensitive mechanism of resistance to n-methyl-4-phenylpyridinium.the toxin n-methyl-1,2,3,6-tetrahydropyridine produces a model of neural degeneration very similar to idiopathic parkinson disease. to understand the cellular mechanisms that modulate susceptibility to its active metabolite n-methyl-4-phenylpyridinium (mpp+), we have transfected a cdna expression library from the relatively mpp(+)-resistant rat pheochromocytoma pc12 cells into mpp(+)-sensitive chinese hamster ovary (cho) fibroblasts. selection of the stable transformants in high concentrations o ...19921409604
[the reproductive characteristics of the tick-borne encephalitis virus in interspecific somatic hybrids].the study dealt with features of tick-borne encephalitis virus reproduction in two series of interspecies somatic hybrids generated by fusion of transformed cells of chinese hamster (ag17) with human diploid fibroblasts (km/3) and with pseudonormal cells of indian deer (muntiacus munjak) (kom). the viral infection in hybrid ag17 cells ran an acute course with cell damage, but in km/3 and kom cells virus multiplication was not accompanied by the development of cytopathic effect. two other paramet ...19921413714
studies on virulence determinants of plesiomonas shigelloides.virulence determinants of nineteen strains of plesiomonas shigelloides isolated from stool samples of diarrhoeal children were studied. heat-labile toxin was detected in seven strains using rat ileal loop model and in none of the strains using chinese hamster ovary cell assay system and by enzyme-linked immunosorbent assay. rat ileal loop model was used for the first time to assay toxin in p. shigelloides and is suggested to be a cheap and effective method of detecting labile toxin in the organi ...19921417662
a recombinant rat vascular at1 receptor confers growth properties to angiotensin ii in chinese hamster ovary cells.a rat vascular at1 receptor cdna has been stably expressed into chinese hamster ovary cells and the resulting recombinant at1a receptor has been functionally characterized. this receptor binds 125i sar1-angiotensin ii with an affinity of 0.9 nm and the displacement of this ligand by a series of peptidic and nonpeptidic analogs is shown. binding of angiotensin ii to this receptor causes a rapid increase in inositol phosphate production, whereas this effect is not observed in nontransfected cells. ...19921417814
expression and characterization of bone morphogenetic protein-2 in chinese hamster ovary cells.bone is a dynamic tissue that responds to many factors including vitamin d, parathyroid hormone, estrogen, calcitonin, and bone morphogenetic proteins (bmps). the ability to stimulate new bone growth would permit novel therapies for situations where bone mass has been lost due to accident or disease. purified bmp-2, in conjunction with a suitable matrix, is sufficient to stimulate the synthesis of new bone (wang et al., 1990). we have expressed recombinant human bmp-2 at high levels in chinese h ...19921419071
cloning and expression of the murine gene and chromosomal location of the human gene encoding n-acetylglucosaminyltransferase i.a mouse cdna clone previously isolated from an f9 teratocarcinoma cell library and shown to confer n-acetylglucosaminyltransferase i (glcnac-ti) activity on lec1 chinese hamster ovary (cho) cell transfectants [kumar, r., yang,j., larsen,r.d. and stanley,p. (1990) proc. natl. acad sci. usa, 87, 9948-9952] has been sequenced. the nucleotide and deduced amino acid sequences are highly homologous to previously described human and rabbit glcnac-ti cdnas. a 1250 bp portion of the mouse cdna encoding a ...19921421759
comparison of the carbohydrate moieties of recombinant soluble fc epsilon receptor (sfc epsilon rii/scd23) expressed in saccharomyces cerevisiae and chinese hamster ovary cells. different o-glycosylation sites are used by yeast and mammalian cells.recombinant human soluble low affinity receptor for the fc portion of ige (sfc epsilon rii/scd23) was produced in saccharomyces cerevisiae or chinese hamster ovary cells and subjected to carbohydrate analysis. applied methods included analytical sds-page, reversed phase hplc, methylation analysis and sequential degradation with exoglycosidases. the results revealed that sfc epsilon rii derived from chinese hamster ovary cells is glycosylated exclusively at ser-147, containing mainly the trisacch ...19921422142
purification of recombinant human secretory phospholipase a2 (group ii) produced in long-term immobilized cell culture.recombinant human secretory phospholipase a2 (group ii) was expressed in long-term culture of immobilized chinese hamster ovary cells utilizing a continuous-perfusion airlift bioreactor. the bioreactor was continuously perfused with cell-culture medium supplemented with 5% fetal calf serum at an average flow rate of 5 liters/day for 30 days. recombinant phospholipase a2, at concentrations ranging from 100 to 500 micrograms/liter, was purified to apparent homogeneity by an efficient two-step proc ...19921422206
effects of 3,3'-dihydroxy-alpha,beta-diethylstilbene and 3,3',4,5'-tetrahydroxystilbene on microtubule assembly in vitro, aneuploidy induction, and cellular microtubule and actin networks.we examined the inhibitory activities of 3,3'-dihydroxy-alpha,beta-diethylstilbene (dds) and 3,3',4,5'-tetrahydroxystilbene (ths) on microtubule assembly in vitro and their effects on chromosome number and cellular microtubule networks in chinese hamster v79 cells. dds showed half the inhibitory activity of diethylstilbestrol (des) on microtubule assembly in vitro, while ths had none of the inhibitory activity. dds induced tetraploid at 30 microm, whereas ths was found to be inactive. furthermor ...19921423765
identification and quantitative detection of isomeric benzo[a]pyrene diolepoxide--dna adducts by low-temperature conventional fluorescence methods.the pyrene-like fluorescence of adducts derived from the covalent binding of (+/-)-trans-7,8-dihydroxy-anti-9,10-epoxy-7,8,9, 10-tetrahydrobenzo[a]pyrene [+/-]-anti-bpde] to dna increases in intensity by factors of 20 or more as the temperature is lowered from ambient to approximately 100 k. this effect is primarily associated with the strong quenching of the pyrene-like fluorescence of bpde-deoxyguanosyl adducts at room temperature, and the suppression of the electron-transfer quenching mechani ...19921423840
overexpression of human dna repair protein n-methylpurine-dna glycosylase results in the increased removal of n-methylpurines in dna without a concomitant increase in resistance to alkylating agents in chinese hamster ovary cells.n-alkylpurines induced in dna by simple monofunctional alkylating agents are known to be cytotoxic and possibly indirectly mutagenic. these adducts are removed by the ubiquitous n-methylpurine-dna glycosylase (mpg) in a multistep repair pathway. chinese hamster ovary (cho) cell clones expressing 2- to 16-fold enhanced levels of mpg activity were isolated from cells stably transfected with human mpg cdna expression plasmids. the in vivo removal of 3-methyladenine and 7-methylguanine from some of ...19921423866
a cytotonic, cholera toxin-like protein produced by campylobacter jejuni.1. campylobacter jejuni is a major cause of gastroenteric infection. 2. this organism appears to produce both cytotonic and cytotoxic virulence factors. 3. we report here that culture filtrates of some clinical isolates of c. jejuni induce elongation of chinese hamster ovary (cho) cells in vitro but do not cause inhibition of fluid absorption in the rat ileum. 4. these culture filtrates contain low levels of a protein which cross-reacts immunologically with the cholera toxin. 5. the cholera toxi ...19921424561
selective removal of glycosylation sites from sex hormone-binding globulin by site-directed mutagenesis.sex hormone-binding globulin (shbg) is a homodimeric plasma glycoprotein with high affinity for sex steroid hormones. it contains two n-linked carbohydrate chains and one o-linked oligosaccharide per subunit, but their functional significance is not known. site-directed mutagenesis of a human shbg cdna has enabled us to selectively disrupt the known glycosylation sites individually and in various combinations. the mutant cdnas were expressed in chinese hamster ovary (cho) cells, and it was found ...19921425432
expression of the e.coli 3-methyladenine dna glycosylase i gene in mammalian cells reduces the toxic and mutagenic effects of methylating agents.in order to investigate the importance of 3-methyladenine in cellular sensitivity to chemical methylating agents we have constructed retroviral vectors for the integration and expression of the escherichia coli tag gene in mammalian cells. the tag gene encodes 3-methyladenine dna glycosylase-1 which specifically removes 3-alkyladenines from dna. the constructs were introduced into chinese hamster v79 cells by liposome mediated transfection or into murine haemopoietic stem cells by cocultivation ...19921425578
the potential genotoxicity of sorbates: effects on cell cycle in vitro in v79 cells and somatic mutations in drosophila.sodium sorbate, potassium sorbate and an oxidation product of sodium sorbate, 4,5-epoxy-2-hexenoic acid, were tested for their genotoxic potential in cultured v79 chinese hamster cells and in somatic cells of drosophila melanogaster (wing spot test, smart). in drosophila only the epoxide showed a weak genotoxic effect. in v79 cells, freshly prepared sodium sorbate solutions at the highest concentrations only (2.5 mg/ml, 24 hr exposure) arrested mitosis at the g2/m cell cycle phase and potassium ...19921427506
the ccaat/enhancer binding protein (c/ebp alpha) gene (cebpa) maps to human chromosome 19q13.1 and the related nuclear factor nf-il6 (c/ebp beta) gene (cebpb) maps to human chromosome 20q13.1.the cebpa gene encoding ccaat/enhancer binding protein (c/ebp alpha) has been mapped to human chromosome 19 and the cebpb (formerly tcf5) gene encoding nf-il6 (c/ebp beta) to human chromosome 20 by southern blot analysis of chinese hamster x human and mouse x human somatic cell hybrids. cebpa has been further mapped to 19q13.1 between the loci gpi and tgfb using human x hamster somatic cell hybrids containing restricted fragments of human chromosome 19. this position was confirmed by fluorescenc ...19921427819
a radiation hybrid map of the proximal short arm of the human x chromosome spanning incontinentia pigmenti 1 (ip1) translocation breakpoints.radiation hybrid mapping was used in combination with physical mapping techniques to order and estimate distances between 14 loci in the proximal region of the short arm of the human x chromosome. a panel of radiation hybrids containing human x-chromosomal fragments was generated from a chinese hamster-human cell hybrid containing an x chromosome as its only human dna. sixty-seven radiation hybrids were screened by southern hybridization with sets of probes that mapped to the region xp11.4-xcen ...19921427892
basic fibroblast growth factor is internalized through both receptor-mediated and heparan sulfate-mediated mechanisms.basic fibroblast growth factor (bfgf) was internalized at a rapid rate by chinese hamster ovary (cho) cells that do not express significant numbers of high affinity receptors for bfgf as well as cho cells that have been transfected with cdna encoding fgf receptor-1 or fgf receptor-2. internalization of bfgf was completely blocked by the addition of 10 micrograms/ml heparin in the parental cho cells but only partially inhibited in cells expressing transfected fgf receptors. bovine aortic endothel ...19921429568
replacement of intracellular c-terminal domain of glut1 glucose transporter with that of glut2 increases vmax and km of transport activity.the intracellular c-terminal domain is diverse in size and amino acid sequence among facilitative glucose transporter isoforms. the characteristics of glucose transport are also divergent, and glut2 has far higher km and vmax values compared with glut1. to investigate the role of the intracellular c-terminal domain in glucose transport, we expressed in chinese hamster ovary cells the mutated glut1 protein whose intracellular c-terminal domain was replaced with that of glut2 by means of engineeri ...19921429604
expression of 7 alpha-hydroxylase in non-hepatic cells results in liver phenotypic resistance of the low density lipoprotein receptor to cholesterol repression.the goal of this study was to understand why the expression of low density lipoprotein (ldl) receptors by the liver is poorly down-regulated by cholesterol. we examined the hypothesis that 7 alpha-hydroxylase may indirectly induce the expression of the ldl receptor by metabolizing, i.e. inactivating oxysterol repressors. non-hepatic chinese hamster ovary cells, transfected with a plasmid encoding 7 alpha-hydroxylase, expressed both the mrna and functional activity of this liver-specific enzyme. ...19921429619
cdna cloning of mev, a mutant protein that facilitates cellular uptake of mevalonate, and identification of the point mutation responsible for its gain of function.we report the expression cloning of pmev, a cdna that facilitates cellular uptake of mevalonate. pmev was isolated from the met-18b-2 clone of chinese hamster ovary (cho) cells, which were selected for growth in low concentrations of mevalonate when synthesis is blocked by compactin (faust, j. r., and krieger, m. (1987) j. biol. chem. 262, 1996-2004). pmev encodes a 494-residue protein, mev, that is predicted to have 12 membrane-spanning regions, consistent with a membrane transporter. surprisin ...19921429658
deletion of the pro-alpha 1(i) n-propeptide affects secretion of type i collagen in chinese hamster lung cells but not in mov-13 mouse cells.we have introduced two mutations into a full-length human pro-alpha 1(i) cdna that delete 114 amino acids or the entire 139 amino acids of the n-propeptide domain. wild-type and mutated versions of the cdna were introduced into cultured chinese hamster lung (chl) cells, which do not produce endogenous type i collagen, and into mov-13 mouse cells, which produce endogenous pro-alpha 2(i) chains but not pro-alpha 1(i) chains. as judged by resistance to proteases, neither mutation impaired intracell ...19921429742
homeotic protein binding sites, origins of replication, and nuclear matrix anchorage sites share the atta and attta motifs.nuclear matrix organizes the mammalian chromatin into loops. this is achieved by binding of nuclear matrix proteins to characteristic dna landmarks in introns as well as proximal and distal sites flanking the 5' and 3' ends of genes. matrix anchorage sites (mars), origins of replication (oris), and homeotic protein binding sites share common dna sequence motifs. in particular, the atta and attta motifs, which constitute the core elements recognized by the homeobox domain from species as divergen ...19921429878
animal cell mutants represent two complementation groups of peroxisome-defective zellweger syndrome.generalized peroxisome-deficient disorders including cerebro-hepato-renal zellweger syndrome, neonatal adrenoleukodystrophy, and infantile refsum disease are autosomal recessive diseases, where catalase-containing particles (peroxisomes) are morphologically absent. we previously isolated two chinese hamster ovary (cho) cell mutants (z24 and z65) that resemble the fibroblasts from patients with such diseases, in their defective peroxisome assembly (tsukamoto, t., s. yokota, and y. fujiki. 1990. j ...19921430210
lipoprotein lipase enhances binding of lipoproteins to heparan sulfate on cell surfaces and extracellular matrix.lipoprotein lipase enhances binding at 4 degrees c of human plasma lipoproteins (chylomicrons, vldl, intermediate density lipoprotein, ldl, and hdl3) to cultured fibroblasts and hepg-2 cells and to extracellular matrix. heparinase treatment of cells and matrix reduces the lipoprotein lipase enhanced binding by 90-95%. lipoprotein lipase causes only a minimal effect on the binding of lipoproteins to heparan sulfate deficient mutant chinese hamster ovary cells while it promotes binding to wild typ ...19921430223
double-blind randomized phase i study on the clinical tolerance and biological effects of natural and recombinant interferon-beta.the clinical tolerance of and the effects recombinant human interferon-beta (rhuifn-beta) obtained from mammalian cells (chinese hamster ovary cells) exerts on 2',5'-oligoadenyl (2-5a) synthetase activity, human-mx protein, neopterin, beta 2-microglobulin, interleukin-1 (il-1) alpha and beta synthesis were compared to those of natural ifn-beta in 12 healthy volunteers. each subject received a single i.m. injection of 6 x 10(6) iu rhuifn-beta and natural ifn-beta according to a randomized double- ...19921431312
inhibitors of sterol synthesis. chemical synthesis and spectral properties of 3 beta-hydroxy-5 alpha-cholesta-8(14),24-dien-15-one, 3 beta,25-dihydroxy-5 alpha-cholest-8(14)-en-15-one, and 3 beta,24-dihydroxy-5 alpha-cholest-8(14)-en-15-one and their effects on 3-hydroxy-3-methylglutaryl coenzyme a reductase activity in cho-k1 cells.side-chain functionalized delta 8(14)-15-ketosterols have been synthesized from 3 beta-acetoxy-24-hydroxy-5 alpha-chol-8(14)-en-15-one (vi) as part of a program to prepare potential metabolites and analogs of 3 beta-hydroxy-5 alpha-cholest-8(14)-en-15-one (i), a potent regulator of cholesterol metabolism. oxidation of vi to the 24-aldehyde vii, followed by wittig olefination with isopropyltriphenylphosphonium iodide gave 3 beta-acetoxy-5 alpha-cholesta-8(14),24-dien-15-one (viii), which was hydr ...19921431575
effect of hydrogen peroxide on mammalian chromatin: electron microscopic studies.chromatins purified from rat liver as well as from cultured chinese hamster v79 cells were treated with hydrogen peroxide in presence of iron in vitro. when examined in a transmission electron microscope, chromatins from both the sources were found to lose the native morphology. there were evidences of aggregation of the chromatin fibers. this could be due to dna-protein and dna interstrand crosslinking induced by fenton reaction.19921431672
differentiated caco-2 cells as a model for enteric invasion by campylobacter jejuni and c. coli.a collection of 44 campylobacter isolates (37 c. jejuni and seven c. coli) from children with colitis (21 strains) or watery diarrhoea (23 strains) was analysed for toxin production, association with hela cells, and invasion of differentiated caco-2 cell cultures. there was no obvious association of clinical symptoms with species, biotype or enterotoxin production. all colitis strains and most of the isolates from watery diarrhoea were cytotoxic for chinese hamster ovary cells. measurements of b ...19921433253
ercc1 and ercc2 expression in malignant tissues from ovarian cancer patients.ercc1 and ercc2 are human dna repair genes that are associated with in vitro resistance to selected dna-damaging agents.19921433335
chinese hamster ovarian cells transfected with human parathyroid hormone-related protein cdna cause hypercalcemia in nude mice.parathyroid hormone-related protein (pth-rp) has been implicated as a causative factor in the humoral hypercalcemia of malignancy. animal models of hypercalcemia of malignancy that have traditionally utilized human or animal tumors or injections or infusions of hypercalcemic factors have limitations that may prevent exact delineation of the biologic effects of tumor-produced pth-rp.19921434529
mono- and diglucuronide formation from chrysene and benzo(a)pyrene phenols by 3-methylcholanthrene-inducible phenol udp-glucuronosyltransferase (ugt1a1).mono- and diphenols of chrysene and benzo(a)pyrene are suspected substrates of a 3-methylcholanthrene (mc)-inducible phenol udp-glucuronosyltransferase (ugt1a1). mono- and diglucuronide formation from these compounds was studied in two systems, (a) livers of mc-treated rats (homologous expression) and (b) a chinese hamster lung fibroblast cell line (v79) containing rat ugt1a1 cdna and stably expressing this isozyme (heterologous expression). in liver microsomes of mc-treated rats, glucuronidatio ...19921435739
high resistance of cultured mongolian gerbil cells to x-ray-induced killing and chromosome aberrations.the mongolian gerbil (meriones unguiculatus) is known to be one of the most radioresistant animals. we have examined the x-ray sensitivity of normal diploid fibroblasts from mongolian gerbil embryos compared with those of cultured embryo cells obtained from various laboratory animals and a normal human. there was a wide difference in x-ray sensitivity for cell killing among different mammalian species. the d0 values for mongolian gerbil cells ranged from 2.08 to 2.28 gy, values which are twice a ...19921438686
applications of stable v79-derived cell lines expressing rat cytochromes p4501a1, 1a2, and 2b1.1. chinese hamster v79-derived cell lines, stably expressing cytochromes p4501a1, 1a2, and 2b1 activities, were constructed by genetic engineering in continuation of our work to establish a battery of v79 derived cell lines designed to study the metabolism of xenobiotics. 2. cell lines xem1 and xem2, expressing cytochrome p4501a1, were capable of the o-dealkylation of 7-ethoxycoumarin and the hydroxylation of benzo[a]pyrene. 3. cell lines xemd.mz and xemd.nh, expressing p4501a2, were shown to hy ...19921441600
metabolic activation of 1-nitropyrene to a mammalian cell mutagen and a carcinogen.1. the mutagenicity of 1-nitropyrene metabolites in chinese hamster ovary (cho) cells, in the absence of rat liver s9, decreased in the order 6-hydroxy-1-nitropyrene > 1-nitropyrene 9,10-oxide > 1-nitropyrene 4,5-oxide approximately 3-hydroxy-1-nitropyrene approximately 8-hydroxy-1-nitropyrene > 1-nitropyrene. the order of mutagenicity with rat liver s9 was 1-nitropyrene 4,5-oxide approximately 6-hydroxy-1-nitropyrene approximately 1-nitropyrene 9,10-oxide > 3-hydroxy-1-nitropyrene approximately ...19921441603
cytotoxic activity of trewiasine in 4 human cancer cell lines and 5 murine tumors.trewiasine (tws) is a mytansinoid compound. it possessed a significant cytotoxic activity against various human cancer cell lines in vitro. u937 cells, which were more sensitive to the tws, required tws 1 microgram.ml-1 to inhibit cell growth over 90% (p less than 0.01). tws also showed activities against murine tumors in vivo, such as the ascitic tumors s180, hepatoma, u14, and solid tumor lewis lung carcinoma. depression of leukocytes was not seen when mice were given ip tws 10 or 50 microgram ...19921442109
electroporation-mediated gene transfer efficiency is reduced by linear plasmid carrier dnas.carrier dna has generally been found to stimulate dna-mediated gene transfer of chinese hamster ovary (cho) cells by calcium phosphate coprecipitation. in studies employing electroporation, however, we observed that linear plasmid dna was inhibitory to the transfection of cho cells. this unexpected result prompted us to explore the effects of various types and forms of plasmid, cosmid, and chromosomal dnas on transfection efficiencies. both carrier dna form and type were found to influence trans ...19921443569
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