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protein and carbohydrate structural analysis of a recombinant soluble cd4 receptor by mass spectrometry.the primary structure of a soluble form of the cd4 receptor (scd4) expressed in chinese hamster ovary cells has been confirmed by mass spectrometric peptide mapping and and tandem mass spectrometry. these studies corroborated 95% of the 369-amino acid-long sequence and established the fidelity of translation of the nh2 and cooh terminal including the absence of "ragged ends." the arrangement of the three disulfide bonds in recombinant scd4 was also established by mass spectrometry and comparativ ...19892592374
calcium-independent growth of human ovarian carcinoma cells.evidence in the literature suggests that cancer cell growth in vitro is generally not sensitive to external calcium. a human ovarian carcinoma cell line (skov3) retained 60% of its normal growth in dulbecco modified eagle's medium (dme) when the calcium concentration was reduced from 3 mm to 10 microm. chinese hamster ovary cells (cho) were growth-arrested in media containing less than 500 microm calcium. in low-calcium (10 microm) dme, 10 microm of a calmodulin antagonist w7 inhibited the growt ...19892592423
characterization of cytotoxicity and r-plasmid in salmonella krefeld.from 1981 to 1984, 254 isolates of salmonella krefeld were isolated from newborns and infants with acute gastroenteritis in southern taiwan. all the crude enterotoxin preparations of s. krefeld caused the cytotoxic elongation reaction in chinese hamster ovary k1 (cho-k1) cells. cytotoxic enterotoxin was also produced by s. krefeld inducing vero cells to round up and appear partially detached from the culture plate. it was noted that s. krefeld showed internalization and multiplication in cho-k1 ...19892593211
characterization of the anaemia of chronic renal failure and the mode of its correction by a preparation of human erythropoietin (r-huepo). an investigation of the pharmacokinetics of intravenous erythropoietin and its effects on erythrokinetics.studies were directed to characterization of the anaemia of renal failure of 11 patients on haemodialysis and determination of the way in which it is corrected by human erythropoietin derived from recombinant dna expressed in chinese hamster ovary cells (r-huepo) administered intravenously. erythrokinetics before treatment showed that total red cell mass was below normal and that both erythron transferrin uptake and red cell survival were modestly reduced; treatment increased both total red cell ...19892594953
surfactant peptides stimulate uptake of phosphatidylcholine by isolated cells.to determine whether small hydrophobic surfactant peptides (sp-b and sp-c) participate in recycling of pulmonary surfactant phospholipid, we determined the effect of these peptides on transfer of 3h- or 14c-labelled phosphatidylcholine from liposomes to isolated rat alveolar type ii cells and chinese hamster lung fibroblasts. both natural and synthetic sp-b and sp-c markedly stimulated phosphatidylcholine transfer to alveolar type ii cells and chinese hamster lung fibroblasts in a dose- and time ...19892597670
i/lyn mouse phosphorylase kinase deficiency: mutation disrupts expression of the alpha/alpha'-subunit mrnas.a cdna encoding the alpha subunit of mouse skeletal muscle phosphorylase kinase was used to compare the expression of alpha mrnas in normal and phosphorylase kinase-deficient tissues of the i/lyn mouse. the results demonstrate that two different molecular weight species of poly(a)+ rna in normal mouse heart and skeletal muscle hybridize to the alpha cdna. these two mrnas direct the synthesis of alpha protein and its isoform alpha' in a cell-free translation system. thus, alpha and alpha' are enc ...19892602386
expression of enzymatically active rat dipeptidyl peptidase iv in chinese hamster ovary cells after transfection.dipeptidyl peptidase iv (dppiv) is a cell surface membrane glycoprotein expressed in many tissues. we have subcloned the coding region of a full-length cdna for dppiv into the inducible eukaryotic expression vector pmsg. the resulting construct was used to transfect chinese hamster ovary (cho) cells. stable transformants were found to express dppiv, and the expression is enhanced by dexamethasone. metabolic labeling of the transfected cells with [35s]met followed by immunoprecipitation revealed ...19892605197
rapid methods for purification of human recombinant interleukin-5 (il-5) using the anti-murine il-5 antibody-coupled immunoaffinity column.a large scale production of human recombinant il-5 (hil-5) was performed by way of recombinant dna technology. in this study, we transfected chinese hamster ovary cells with pdkcr-hil-5gene-dhfr plasmid and selected a cell line, with the use of methotrexate, producing large amounts of hil-5. the recombinant hil-5 thus obtained induced igm production of murine b cell leukemia bcl1, and its activity was inhibited by tb13 anti-mouse il-5 monoclonal antibody. hil-5 could be purified from the cell-fr ...19892607155
stable overproduction of intact glucocorticoid receptors in mammalian cells using a selectable glucocorticoid responsive dihydrofolate reductase gene.we have generated several mammalian cell lines that stably express high levels of intact glucocorticoid receptor. these cells were created by cotransfecting a glucocorticoid-dependent dihydrofolate reductase (dhfr) gene into dhfr-deficient chinese hamster ovary (cho) cells together with a plasmid directing the expression of human glucocorticoid receptor. using this approach, transfection frequencies indicate that the inclusion of glucocorticoid receptor cdna increased the efficiency of dhfr tran ...19892608055
disruption of n-linked glycosylation of bovine luteinizing hormone beta-subunit by site-directed mutagenesis dramatically increases its intracellular stability but does not affect biological activity of the secreted heterodimer.the single site for n-linked glycosylation of the beta-subunit of bovine lh (lh beta) was disrupted by oligonucleotide-directed mutagenesis to assess its potential roles in the biosynthesis, transport, and hormonal activity of the lh alpha/beta heterodimer. pulsechase studies performed with stably transfected chinese hamster ovary cells that expressed both alpha-subunit (fully glycosylated) and nonglycosylated lh beta revealed that turnover, transport, and secretion of newly synthesized, nonglyc ...19892608056
determination of the electrophoretic mobility of chromosomes by free flow electrophoresis. i. morphology and stability.isolated metaphase chromosomes of several fibroblastoid cell lines (chinese hamster, chinese hamster x human hybrid) were subjected to free flow electrophoresis (ffe) to study their electrophoretic mobility (em). the morphology and stability of the chromosomes were unaffected by ffe as examined by cytogenetic methods and flow cytometry. the chromosomes of the complement all showed similar em under most of the conditions applied. at neutral ph the em of the chromosomes had the same sign as free d ...19892612466
chromosomal localization of murine interleukin-1 alpha and beta genes.dna analyses of mouse x chinese hamster somatic cell hybrids and of recombinant inbred mouse strains have previously shown that the interleukin-1 alpha and beta genes are tightly linked on murine chromosome 2, approximately 4.7 cm distal to beta-2-microglobulin. in this study, using in situ chromosome hybridization, we show that the two interleukin-1 genes are located in the f region of murine chromosome 2 and discuss this physical map position in relation to conserved genetic linkage groups.19892613234
immunofluorescent visualization of dna replication sites within nuclei of chinese hamster ovary cells.the spatial distribution of replication sites was studied by a sensitive method in cells cultured in vitro. exponentially growing chinese hamster ovary cells were permeabilized and pulse labeled in the presence of deoxyribonucleoside triphosphates, dttp being replaced by biotin-11-dutp as a substrate for dna replication. the distribution of replication sites was visualized in isolated nuclei by fluorescent microscopy of samples taken periodically after short-term (2 min) in vitro labeling and pu ...19892613551
infection of the chinese hamster with trichinella pseudospiralis.a mean of 2,862 muscle larvae was recovered on day 45 postinfection (pi) from the total body musculature of chinese hamsters infected with 498 trichinella pseudospiralis. infection of the chinese hamster with 494 trichinella spiralis resulted in recovery of a mean of 225 muscle larvae on day 45 pi. the reproductive capacity index for t. pseudospiralis was 5.74, whereas that for t. spiralis was 0.46 in this host species.19892614596
genotoxic investigations of tobacco protein using microbial and mammalian test systems.tobacco protein was assayed for mutagenicity using the ames test and three in vivo tests. in the salmonella strains ta 98 and ta 100 methanolic extracts of the tobacco protein and urine of rats fed tobacco protein exhibited increased revertant numbers, but extracts of feces did not. using the micronucleus test throughout, weak mutagenic effects after feeding the tobacco protein were detected in chinese hamsters and two inbred strains of mice, and again in chinese hamsters when the chromosome abe ...19892618105
effect of butyrate on the expression of the human preprourokinase gene introduced into chinese hamster ovary cells.a plasmid containing the human preprourokinase gene cdna under the control of the simian virus 40 early region promoter was introduced into cho-k1 cells and recombinant cell lines secreting a relatively high level of urokinase were obtained. in the course of studying the effects of various agents on the recombinant cell lines, we found that exposure of recombinant cells to 5 mm butyrate for 24 hours resulted in a 2-3 fold increase in urokinase production. the induction by butyrate was dose-depen ...19892620348
agarose gel electrophoresis in isozyme separation and visualization.isozyme analysis of rodent-human somatic cell hybrids has been used frequently to detect specific human chromosomes. the majority of these isozyme systems employs starch gels, the use of which can be laborious when screening large numbers of cell lines. we describe the development of two procedures to detect the long arms of human chromosomes 1 and 2 in chinese hamster-human cell hybrids by a rapid and reproducible method using 1-mm-thick agarose gels. detection of human chromosome 1q was accomp ...19892627195
transient production and secretion of human transforming growth factor tgf-beta 2.transient transfection of simian cos cells with a recombinant plasmid encoding the human transforming growth factor tgf-beta 2 precursor protein results in the production of a latent, biologically inactive protein. upon acidification, recombinant tgf-beta 2 exhibits full biological activity, including inhibition of mink lung epithelial cell growth, stimulation of anchorage-independent growth of murine embryonic fibroblasts, and competition for tgf-beta receptor binding. further analysis of condi ...19892628179
inhalation hazards from airborne particulates evaluated by in vitro cyto- and genotoxicity testing: a long-term study over a period of 14 years (1975-1988) from a highly industrialized area.26 samples of airborne particulates collected between 1975 and 1988 in the highly industrialized rhine-ruhr region were analyzed for cytotoxic and genotoxic activity. samples were extracted by organic solvents and quantitatively transferred to dimethyl sulfoxide for tissue culture experiments. cytotoxicity testing of samples revealed a dose related loss of cell viability of mouse and human macrophages as well as an impairment of phagocytosis. we observed a reduction of "plating efficiency" of ro ...19892637158
inhibition of 'in vitro' tumor cell growth by aromatic polyamidines exhibiting antiproteinase activity.aromatic polyamidines containing two, three or four benzamidine residues inhibit proteinase activity and proliferation of different human tumor cell lines, including leukemic (k562, hel), melanoma (colo 38) and b-lymphoid (wi-l2) cell lines. in addition, the benzamidine derivatives analysed in the present study inhibit cell growth of the chinese hamster fho6t1-1 cell line, obtained after transfection of primary lung cells with the activated human t24-ha-ras-1 oncogene. after treatment of fho6t1- ...19892642270
flow cytometric analysis of doxorubicin accumulation in cells from human and rodent cell lines.the correlation between intracellular accumulation of doxorubicin (dox) and drug cytotoxicity was studied in cells from seven cell lines of rodent and human origin. we used three chinese hamster ovary cell lines (auxb1, chrc5, and uv20), two murine tumor cell lines (kht-lp1 and emt6/ro), and two human tumor cell lines (mgh-u1 and dld-1). intracellular dox was measured by its fluorescence intensity with flow cytometry, and drug cytotoxicity was quantified with clonogenic assays. when data for all ...19892642304
chromosome aberration and sister chromatid exchange tests in chinese hamster ovary cells in vitro: ii. results with 20 chemicals.twenty chemicals were tested for their ability to induce sister chromatid exchanges (sces) and chromosomal aberrations (abs) in cultured chinese hamster ovary cells (cho). these chemicals were tested with and without an added metabolic activation system (rat liver s9 fraction). four chemicals were negative in both assays, 1 induced abs only, and 15 were positive for sces; 6 of these 15 also induced abs. the effect of cell harvest time on the ability to detect the induction of chromosomal aberrat ...19892642806
mutagenicity studies on fenitrothion in bacteria and mammalian cells.the mutagenicity of fenitrothion was determined in strains of salmonella typhimurium and escherichia coli. fenitrothion was found to be non-mutagenic in salmonella typhimurium strains of ta98, ta1535 and ta1537 and in escherichia coli wp2uvra both with and without s9 mix, while weak mutagenicity was observed only in salmonella typhimurium ta100 and enhanced by the addition of s9 mix. the mutagenicity observed in the ta100 strain was not expressed in a nitroreductase-deficient strain, ta100 nr, a ...19892643032
rabbit brain glucose transporter responds to insulin when expressed in insulin-sensitive chinese hamster ovary cells.transfection of chinese hamster ovary cells with the expression vector containing rabbit brain hepg2-type glucose transporter cdna resulted in a dramatic over-expression (approximately 10-fold) of glucose transporter as assessed by either immunoblotting with antipeptide antibody against rabbit brain glucose transporter or photoaffinity labeling with [3h]cytochalasin b. 2-deoxyglucose uptake was also increased 4-fold in the transfected cells, while no increase in transport activity or transporter ...19892644284
[from natural to recombinant human erythropoietin. biotechnological production of recombinant human erythropoietin].human erythropoietin (epo), which occurs only in minute quantities in human plasma, has been isolated from urine of patients and purified to homogeneity. a partial amino acid sequence from tryptic digests of the purified protein was selected for oligodeoxynucleotide probe synthesis. these probes were used to isolate the epo gene from a human gene bank. the isolated gene was engineered into a eukaryotic expression vector and introduced into chinese hamster ovary cells commonly used for recombinan ...19892644578
addition of truncated oligosaccharides to influenza virus hemagglutinin results in its temperature-conditional cell-surface expression.in the preceding paper (hearing, j., e. hunter, l. rodgers, m.-j. gething, and j. sambrook. 1989. j. cell biol. 108:339-353) we described the isolation and initial characterization of seven chinese hamster ovary cell lines that are temperature conditional for the cell-surface expression of influenza virus hemagglutinin (ha) and other integral membrane glycoproteins. two of these cell lines appeared to be defective for the synthesis and/or addition of mannose-rich oligosaccharide chains to nascen ...19892645296
internalization and degradation of insulin by a human insulin receptor-v-ros hybrid in chinese hamster ovary cells.chinese hamster ovary cell lines expressing either the wild-type human insulin receptor or a hybrid molecule in which the tyrosine kinase domain of the insulin receptor is replaced with that of the oncogene, v-ros were examined for their ability to internalize and degrade insulin. cells expressing the hybrid receptor were found to internalize and degrade insulin at approximately half the rate of cells expressing the native insulin receptor. moreover, insulin was incapable of inducing the interna ...19892645866
influence of the alkyl substituent on mutagenicity and covalent dna binding of bay region diol-epoxides of 7-methyl- and 7-ethylbenz(a)anthracene in salmonella and v79 chinese hamster cells.the anti-isomers of the bay region diol-epoxides of the strong carcinogen 7-methylbenz(a)anthracene and of the weak carcinogen 7-ethylbenz(a)anthracene were investigated for mutagenicity in salmonella typhimurium (reversion of the his - strains ta98 and ta100 to prototrophy) and v79 chinese hamster cells (acquisition of resistance to 6-thioguanine and ouabain; formation of micronuclei). in addition, in the v79 cells, the levels of the dna adducts formed were determined by 32p-postlabeling analys ...19892647293
mutagenicity of 1-, 3- and 6-nitrosobenzo[a]pyrene in salmonella typhimurium and chinese hamster ovary cells. 19892648140
induction of sister chromatid exchanges by tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone in human and hamster cells.4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (nnk), a nicotine derived n-nitrosamine, is a carcinogen that induces tumors in mice, rats and hamsters. to assess the ability of nnk to interact with the cellular dna as an essential step in carcinogenesis, the induction of sister chromatid exchange (sce) was examined in cultured normal human lymphocytes (hl) and chinese hamster v79 cells. sce formation is a sensitive indicator of carcinogen-dna interaction that correlates with the induction of mut ...19892649269
mutagenicity profiles of newer amsacrine analogues with activity against solid tumours: comparison of microbial and mammalian systems.amsacrine, an acridine derivative used clinically in the treatment of acute leukaemia, has formed the basis for the development of further compounds with high activity against experimental solid tumours, one of which is currently in clinical trial. we have compared the ability of these drugs to cause point mutations in bacteria, 'petite' mutations in yeast and mutations in mammalian cells. several of the compounds are frameshift mutagens in salmonella typhimurium ta1537 while some cause 'petite' ...19892649376
glycosylation and processing of the human immunodeficiency virus type 1 envelope protein.the human immunodeficiency virus type 1 (hiv-1) envelope protein is synthesized as a gp160 precursor that is cleaved to a 120 kda exterior glycoprotein (gp120) and a 41 kda transmembrane glycoprotein (gp41). the hiv-1 envelope protein was stably expressed under the control of the transactivator proteins tat and rev, in wild-type and mutant chinese hamster ovary (cho) cells. the mutant, ldld, is conditionally defective for the addition of galactose and n-acetylgalactosamine to oligosaccharide cha ...19892649653
genotoxicity of azidoalanine in mammalian cells.sodium azide mutagenesis is mediated through a metabolic intermediate in bacteria and plant species. however, very little is known about the interaction of this intermediate with nucleic acids, its genotoxic potential, or its mechanism of action, especially in mammalian cells. chinese hamster cells and normal human skin fibroblasts were treated with extracts from salmonella typhimurium or hordeum vulgare (barley) containing a crude mutagenic metabolite, as well as with synthetically produced azi ...19892651118
photobiology of low-power laser effects.quantitative studies have been performed to determine the action of low-intensity visible monochromatic light on various cells (e. coli, yeasts, hela, chinese hamster fibroblasts and human lymphocytes); also irradiation conditions (wavelength, dose and intensity) conducive to vital activity stimulation have been examined. respiratory chain components are discussed as primary photoacceptors. the possible ways for photosignal transduction and amplification are discussed. it is proposed that enhanc ...19892651364
acetylation and deacetylation of histone h4 continue through metaphase with depletion of more-acetylated isoforms and altered site usage.antibodies specific for acetylated isoforms of histone h4 have been used to compare acetylation of this histone in interphase and metaphase cells. two rabbit antisera (r5 and r6) were used, each specific for h4 molecules acetylated at one of the four possible acetylation sites, namely lys-5 (r6) and lys-12 (r5). both antisera bound preferentially to the more-acetylated h4 isoforms (h4ac2-4). to test for continued h4 acetylation in metaphase chromosomes. chinese hamster ovary cells were blocked i ...19892653852
toxicity of dibutyltin, tributyltin and other organotin compounds to humans and to experimental animals.alkyltin compounds are used as stabilizers and antifouling agents. food chain accumulation and bioconcentration have been demonstrated in crabs, oysters and salmon exposed to tributyltin oxide. in mammalian species, tributyltin compounds may be metabolized to dibutyltin derivatives and related metabolites. di- and tributyltins appear to be less potent neurotoxicants than trimethyltins and triethyltins. dibutyltins and tributyltins produced bile duct damage in rats, mice and hamsters. tributyltin ...19892655175
a structural model to explain the partial catalytic activity of human prorenin.human prorenin, secreted from a chinese hamster ovary cell line transfected with the cdna for preprorenin, has been purified in mg quantities by a novel single-step procedure. the method takes advantage of reversible acid activation as a means of generating active prorenin that may be bound and eluted from an affinity column for renin. analysis of the prorenin so purified revealed that it contained about 80% intact zymogen; the remaining 20% comprised a mixture of various prorenin derivatives tr ...19892655662
the mutagenicity of dibenz[a,j]acridine, some metabolites and other derivatives in bacteria and mammalian cells.dibenz[a,j]acridine (dbajac) was studied because of its close structural relationship with a number of important carcinogenic polycyclic and azaaromatic hydrocarbons. it was of particular relevance to examine the mutagenicity of known or proposed 'bay-region' metabolites, which may be proximate or ultimate carcinogenic derivatives of dbajac. trans-1,2-, 3,4- and 5,6-dihydrodiols, the 4- and 6-phenols, the 5,6-oxide and n-oxide derivatives, and anti- and syn-3,4-diol 1,2-epoxides of dbajac were e ...19892655962
a fusion protein required for vesicle-mediated transport in both mammalian cells and yeast.a protein sensitive to n-ethylmaleimide catalyses the fusion of transport vesicles with golgi cisternae in a mammalian cell-free system. by cloning and sequencing its gene from chinese hamster ovary cells and by use of in vitro assays, we show that this fusion protein is equivalent to the sec18 gene product of the yeast saccharomyces cerevisiae, known to be essential for vesicle-mediated transport from the endoplasmic reticulum to the golgi apparatus. the mechanism of vesicular fusion is thus hi ...19892657434
utilization of rat lymphocytes for the in vitro chromosomal aberration assay.in vitro cytogenetic assays are widely conducted to assess the mutagenic potential of chemicals. chinese hamster ovary (cho) cells or human lymphocytes are often used for these assays; however, these cell types have certain limitations. in order to evaluate an alternate cell system, cultured rat lymphocytes were treated for 4 h at 48 h of incubation with a variety of direct- and indirect-acting clastogens in the presence or absence of an exogenous mammalian activation system. cytogenetic effects ...19892659926
in vitro genotoxicity of dyes present in colored smoke munitions.genetic toxicology studies were conducted on organic dyes and mixtures used in colored smoke munitions. the dyes studied included solvent red 1; two different batches (lot 1 and lot 2) of disperse red 11; terephthalic acid; and a mixture of 25 parts solvent red 1, 5 parts disperse red 11, and 16 parts terephthalic acid. the dyes were evaluated for their ability to produce mutations in salmonella bacterial strains and in chinese hamster ovary (cho) cells. the dyes were also tested in cho cells to ...19892661223
studies on the antimutagenic activities of garlic extract.experiments with salmonella tester strains indicated that aqueous garlic extract possesses antimutagenic properties toward ionizing radiation, peroxides, adriamycin, and n-methyl-n'-nitro-nitrosoguanidine. the assumption that radical scavenging garlic constituents, i.e., molecules with sulfur moieties, might be responsible for the inhibitory effect of aqueous extract toward mutagenesis induced by radiation and radiomimetic compounds was confirmed by the results of subsequent experiments; 1) garl ...19892661224
genotoxicity of zinc in 4 short-term mutagenicity assays.the genotoxicity of zinc was examined in 4 short-term mutagenicity assays. zinc acetate produced dose-related positive responses in the l5178y mouse lymphoma assay and an in vitro cytogenetic assay with chinese hamster ovary cells, but was negative in the salmonella mutation assay and did not induce unscheduled dna synthesis in primary cultures of rat hepatocytes. zinc-2,4-pentanedione produced frameshift mutations in salmonella tester strains ta1538 and ta98, but did not induce unscheduled dna ...19892662005
chromosome segregation from cell hybrids. vi. centromeres of both parental chromosome sets stain with antikinetochore antibody.antikinetochore antibodies obtained from serum of patients with the crest syndrome of scleroderma were used to test the hypothesis that there are differences in protein binding to retained- and segregant-set centromeres in chinese hamster--human hybrids. this hypothesis is not supported since identical staining of the two types of kinetochores was observed with crest antibody.19892663641
characterization of transforming growth factors produced by the insulin-independent teratoma-derived cell line 1246-3a.the 1246-3a cell line is an insulin-independent variant derived from the adipogenic cell line 1246. data presented in this paper indicate that the 1246-3a cell line releases in its culture medium two types of transforming growth factors, tgf-alpha- and tgf-beta-like polypeptides, and a growth inhibitor. tgf-alpha like polypeptide eluted from biogel p60 column into two fractions with an apparent molecular weight of 50 kda and 13 kda. these high-molecular-weight tgf-alpha-like factors competed wit ...19892663884
repair of cytotoxic lesions introduced into dna by methylating agents.we have investigated the biological role of o6-methylguanine and methylphosphotriesters in the dna of mammalian cells. our approach has been to express escherichia coli (e. coli) dna repair activities of well-defined specificity in chinese hamster cells. expression of o6-methylguanine-dna methyltransferase is necessary and sufficient to confer resistance to the cytotoxic action of n-methyl-n'-nitro-n-nitrosoguanidine (mnng) indicating the potential involvement of o6-methylguanine in cell killing ...19892665601
genotoxicity of the food mutagen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (phip): formation of 2-hydroxamino-phip, a directly acting genotoxic metabolite.hepatocytes isolated from aroclor 1254 (pcb) pretreated rats metabolized 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (phip) to a reactive metabolite that induced dna damage measured by alkaline elution or as increased unscheduled dna synthesis. phip induced mutations in salmonella typhimurium ta98 and dna strand breaks and sister chromatid exchange(s) in chinese hamster v79 cells co-incubated with pcb-hepatocytes. no, or only minor genotoxic, effects were observed when hepatocytes from non-i ...19892665964
immunological characterization of a human homolog of the 65-kilodalton mycobacterial antigen.a human mitochondrial protein, designated p1 (63 kilodaltons [kda], shows extensive sequence homology (47% identical residues and an additional approximately 20% conserved changes) to the 65-kda mycobacterial antigen. to understand the relationship of these proteins, the cross-reactivity of several monoclonal antibodies directed against the 65-kda mycobacterium leprae antigen towards human, chinese hamster, chicken, and bacterial cells has been examined. a number of antibodies (y1-2, ml 30-a2, a ...19892668187
a self-inducing runaway-replication plasmid expression system utilizing the rop protein.a highly efficient prokaryotic expression system has been developed that produces proteins at levels exceeding 150 micrograms/ml of culture medium. the system consists of a temperature-sensitive-copy-number plasmid that carries the rop gene and promoter downstream from the trp promoter. any sequence cloned into the pvuii site of the rop gene alters rop protein activity and causes lethal runaway plasmid dna replication. this plasmid replication can be suppressed in trans by complementation with a ...19892670683
sodium azide mutagenesis in mammals: inability of mammalian cells to convert azide to a mutagenic intermediate.sodium azide is unique among mutagens. it is highly mutagenic in many plant and bacterial species but marginally mutagenic in mammalian cells. a possible explanation for this difference in mutagenic efficiency may lie in the inability of mammalian cells to convert azide to the putative ultimate mutagen. normal human fibroblasts and chinese hamster cells or cell-free extracts from these cell lines were treated with azide and the sonicates tested for mutagenicity in salmonella strain ta1530. the d ...19892671718
regulation of spermatogonial proliferation.in nonprimates the spermatogonial compartment can be subdivided into (morphologically) undifferentiated spermatogonia and differentiating spermatogonia. each cycle of the seminiferous epithelium the proliferative activity of the undifferentiated spermatogonia is stimulated, probably by factors secreted by sertoli cells. subsequently, during a period of active proliferation many aal spermatogonia are formed. in the normal situation around epithelial stage iii, proliferation is inhibited by the di ...19892672954
introduction of cytochrome p-450 genes into v79 chinese hamster cells to generate new mutagenicity test systems. 19892673143
kinetochore size variation in mammalian chromosomes: an image analysis study with evolutionary implications.the kinetochore, a proteinaceous plate that is the site for attachment of spindle microtubules to the metaphase chromosome, can be visualized using anti-kinetochore indirect immunofluorescence. we have used computer-assisted image analysis to measure the variation of kinetochore surface areas, as reflected by immunofluorescence areas, in cell lines derived from rat kangaroo, chinese hamster and common rat, to determine if our size estimates correlate well with those obtained using measurements f ...19892674167
isolation and characterization of glucose-6-phosphate dehydrogenase-deficient chinese hamster cells derived from pure mutant colonies.ten pure glucose-6-phosphate dehydrogenase (g6pd)-deficient mutants were isolated from colonies composed entirely of cells which lacked g6pd staining activity. these mutants were analyzed for g6pd enzyme activity and the presence of immunologically cross-reactive proteins using immunoblotting techniques and antiserum directed against bovine g6pd. four mutants had no detectable enzyme activity and did not contain protein which produces a detectable cross-reaction with g6pd antibody. one mutant ha ...19892674604
potential role of the human ha-ras oncogene in the inhibition of gap junctional intercellular communication.the modulation of gap junctional intercellular communication (gjic) plays an important role during tumor promotion. several tumor-promoting agents are known to inhibit this form of cellular coupling. in addition, tumor cells and cells expressing certain oncogenic products have been shown to exhibit inhibited or reduced gjic. the ha-ras oncogene is expressed in a wide variety of human tumors from different tissues. its p21 product is a membrane-bound polypeptide, the function of which is not full ...19892675903
estrogen-induced expression of mouse lactate dehydrogenase-a gene.the synthesis of lactate dehydrogenase-a isoenzyme was shown to increase significantly in the uterus of immature mice treated by diethylstilbestrol. the expression of the mouse ldh-a promoter and cat fusion gene in chinese hamster ovary cells was also induced by 17 beta-estradiol and diethylstilbestrol.19892676196
multiple activation pathways of benzene leading to products with varying genotoxic characteristics.benzene and 13 potential metabolites were investigated for genotoxicity in salmonella typhimurium and v79 chinese hamster cells. in the presence of nadph-fortified hepatic postmitochondrial fraction (s9 mix), benzene reverted his- s. typhimurium strains. the effect was strongest in strain ta1535. among the potential metabolites, only the trans-1,2-dihydrodiol, in the presence of s9 mix, and the diol epoxides, in the presence and absence of s9 mix, proved mutagenic in this strain. the anti-diol e ...19892676505
structure and cell surface maturation of the attachment glycoprotein of human respiratory syncytial virus in a cell line deficient in o glycosylation.the synthesis of the extensively o-glycosylated attachment protein, g, of human respiratory syncytial virus and its expression on the cell surface were examined in a mutant chinese hamster ovary (cho) cell line, ldld, which has a defect in protein o glycosylation. these cells, used in conjunction with an inhibitor of n-linked oligosaccharide synthesis, can be used to establish conditions in which no carbohydrate addition occurs or in which either n-linked or o-linked carbohydrate addition occurs ...19892677404
the mutagenic activity of sodium perborate.sodium perborate (cas no. 1333-73-9, 10486-00-7, or 13517-20-9, depending on the structural formula given) is produced in huge amounts mainly for its use as a bleaching agent in laundry detergents. its action involves the liberation of active oxygen species at elevated temperatures. in view of the widespread use of this compound it is surprising to note that no mutagenicity test data yet exist. the investigations reported in this paper have shown that sodium perborate is indeed capable of produc ...19892677709
a genetically engineered cell line that produces empty capsids of b19 (human) parvovirus.b19 parvovirus is pathogenic in humans, causing the common childhood exanthem fifth disease and bone-marrow failure, both acute (transient aplastic crisis of hemolysis) and chronic (pure erythrocyte aplasia in immunodeficiency). the virus is tropic for a human red cell progenitor cell, and failure to culture b19 in a cell line has limited its clinical study. we cotransfected the right half of the cloned b19 genome and a minigene derived from the human dihydrofolate reductase gene (dhfr) into dhf ...19892678109
monoclonal antibodies for affinity purification of il-6/ifn- beta 2 and for neutralization of hgf activity.two types of recombinant human il-6 (ril-6) were used for the development of specific monoclonal antibodies. the first was produced in e. coli and used for immunization, the second was produced in chinese hamster ovary cells (cho) and used for screening. the complete translated sequence of the cdna coding for human il-6 was fused, in phase, to protein-a and the hybrid gene was fused to the strong lambda pr promoter. this protein was purified from bacterial extracts by chromatography on rabbit ig ...19892680901
effects of neonatal ovarian x-irradiation in the chinese hamster. ii. absence of chromosomal and developmental damages in surviving oocytes irradiated at the pachytene and resting dictyate stages.ovaries of chinese hamsters were irradiated with 1 gy of x-rays on day 0, 4, 8 and 14 after birth, and the late effects on pachytene and resting dictyate oocytes, which had been proven to be radioresistant and to survive acute oocyte-killing, were studied in the progeny of the irradiated females. thirty hours after mating, fertilized ova were collected and female pronuclear chromosomes were karyotyped. on day 18.5 of gestation, the number of corpora lutea and implantation sites were counted and ...19892681722
potentiality of protamine sulfate as mutagen.the mutagenicity of protamine sulfate has been clarified based on chromosomal aberration of cultured chinese hamster lung cells (cell line) in direct and metabolic activation methods and microbial mutagenesis (ames test). in chromosomal aberration test, protamine sulfate caused cytotoxicity in the high doses (2500 and 5000 micrograms/ml) in the presence of rat liver homogenates (s-9). but very negligible or no cytotoxicity occurred in direct method at high dose (5000 micrograms/ml). structural a ...19892681804
human chromosome 12 is required for elevated hiv-1 expression in human-hamster hybrid cells.host cell factors act together with regulatory genes of the human immunodeficiency virus (hiv) to control virus production. human-chinese hamster ovary hybrid cell clones were used to probe for human chromosomes involved in regulating hiv gene expression. dna transfection experiments showed that 4 of 18 clones had high levels of hiv gene expression measured by both extracellular virus production and transactivation of the hiv long terminal repeat in the presence of the trans-activator (tat) gene ...19892683071
immortalization by truncated myc or ras genes and synergism between myc and ras genes in cell transformation.human c-myc and normal or mutant t24 h-ras1 genes either linked to the regulatory sequences of the human metallothionein iia gene or unlinked have been employed individually or in combination to transfect early passage chinese hamster lung cells. since the c-myc and h-ras1 genes are present in recombinant plasmids carrying the aminoglycoside phosphotransferase (aph), gene transfectants were selected in the presence of geneticin. a synergistic effect has been observed between myc and h-ras1 genes ...19892683993
mutagenicity of dihydrodiols and diol epoxides of dibenz[a, h]acridine in bacterial and mammalian cells.bay-region diol epoxides are ultimate carcinogenic metabolites of a number of polycyclic aromatic compounds. dibenz[a, h]acridine can form two diastereomeric pairs of these diol epoxides which are not positionally equivalent as a result of the nitrogen atom at position 7. we have assessed the structure-activity relationships resulting from heterocyclic nitrogen substitution by examining the mutagenic activity of these four bay-region diol epoxides of dibenz[a,h]acridine in both bacterial and mam ...19892684405
biotesting of wastewater: a comparative study using the salmonella and cho assay systems.means to assess the toxicity of wastewaters are essential to implementing the federal clean water act. health risk assessment based on single chemicals is limited by the number of chemicals that can be identified and to those chemicals for which toxicity data are available. long-term whole animal tests on large numbers of wastewater samples are not practical. in this study, two short-term tests, the salmonella mutagenicity assay and the chinese hamster ovary (cho) cell assay for mutagenicity and ...19892684657
dna base sequence changes induced by ultraviolet light mutagenesis of a gene on a chromosome in chinese hamster ovary cells.the dna base sequence changes induced by mutagenesis with ultraviolet light have been determined in a gene on a chromosome of cultured chinese hamster ovary (cho) cells. the gene was the escherichia coli gpt gene, of which a single copy was stably incorporated and expressed in the cho cell genome. the cells were irradiated with ultraviolet light and gpt- colonies were selected by resistance to 6-thioguanine. the gpt gene was amplified from chromosomal dna by use of the polymerase chain reaction ...19892685319
characterization and cloning of enterotoxin genes of salmonella typhimurium.five of fifty five strains of salmonella typhimurium of human origin was hybridized with both the lt-a and lt-b gene of escherichia coli. the remarkably erythromatous and indurated response on rabbit skin and significant elongation of chinese hamster ovary (cho) cells indicated the production of enterotoxin of these isolates. the salmonella enterotoxin is heat-labile and is not a secretory product. the lt gene of e. coli was used to analyze the chromosome and plasmid dna from salmonella typhimur ...19892685851
cytogenetic response to coffee in chinese hamster ovary auxb1 cells and human peripheral lymphocytes.we have investigated the genotoxic effects of three different brands and three types of coffee (freshly brewed regular, instant regular and freshly brewed decaffeinated) in two mammalian systems: the chinese hamster ovary (cho) auxb1 cell line and human peripheral lymphocytes. sister-chromatid exchanges (sces) and endoreduplicated cells (ercs) were used as the endpoints. coffee was prepared according to the manufacturer's suggestions, and after cooling, administered to cultured cells at dilution ...19892687627
relevance of plasmid pkm101-mediated mutagenicity in bacteria to genotoxicity in mammalian cells.three structurally related compounds, 4-acetoxy-3-acetoxy-methyl-acetophenone (aamap), 1-[4'-hydroxy-3'-hydroxy-methylphenyl]-2-[benzyl-t-butylamino] ethanone hydrochloride (hhbeh) and 1-[4'-hydroxy-3'-hydroxymethyl-phenyl]-2-[benzyl-t-butylamino] ethanol (hhbe), gave positive dose-related mutagenic responses in the ames test when salmonella typhimurium strain ta100 was used as the test organism. strain ta100 carries the hisg46 allele, which is revertable by base changes, together with plasmid p ...19892687632
differential mutant quantitation at the mouse lymphoma tk and cho hgprt loci.recent reports by several laboratories indicate that not all non-essential target loci are equally capable of detecting chromosomal mutations. the present study was undertaken to determine if both the tk locus in mouse lymphoma cells and the hgprt locus in chinese hamster ovary (cho) cells can be used to quantitate chromosomal mutations. seven known mutagens for the tk locus were selected. these compounds were evaluated in the mouse lymphoma assay and in a suspension adapted cho assay for their ...19892687635
overexpression and biosynthesis of cd4 in chinese hamster ovary cells: coamplification using the multiple drug resistance gene.cd4 is a t-cell surface glycoprotein and serves as the receptor for the human immunodeficiency virus. glycosylation of cd4 has been shown to be necessary for proper surface expression. to study the biosynthesis and assembly of cd4, wild-type and glycosylation-deficient mutant chinese hamster ovary (cho) cells were cotransfected with a cdna encoding cd4 and a cdna for the human multiple drug resistance gene, which allowed the amplification of the transfected cd4 cdna sequences. clones were isolat ...19892687874
expression of a deletion mutant of the prosegment of human prorenin in chinese hamster ovary cells.expression plasmids encoding native human preporenin and a mutant deleted in its entire prosegment were transfected into chinese hamster ovary cells. the cells transfected with the expression plasmid of native preporenin secreted exclusively inactive prorenin, while the cells transfected with the mutant secreted the active enzyme. the secreted amount of renin from the latter cells was much lower than that of prorenin from the former ones, although these two enzymes had little difference in speci ...19892689230
chinese hamster ovary cell mutants defective in peroxisome biogenesis. comparison to zellweger syndrome.we have previously reported the isolation of chinese hamster ovary (cho) cell mutants that are defective in the biosynthesis of plasmalogens, deficient in at least two peroxisomal enzymes (dihydroxyacetonephosphate (dhap) acyltransferase and alkyl-dhap synthase), and in which catalase is not found within peroxisomes (zoeller, r. a., and raetz, c. r. h. (1986) proc. natl. acad. sci. u.s.a. 83, 5170). we now provide further evidence that three such strains are more generally defective in peroxisom ...19892689450
the molecular biology of human renin and its gene.the molecular biology of renin, prorenin, and the renin gene have been studied. a tissue-specific pattern of expression was found in rat and human tissues. in the human placenta, the transfected and endogenous renin promoters are active, and renin mrna levels and transfected promoter activity are increased by a calcium ionophore plus camp. cultured pituitary att-20 cells transfected with a preprorenin expression vector mimick renal renin release by converting prorenin to renin and releasing reni ...19892697983
preferential repair of damage in actively transcribed dna sequences in vivo.my colleagues and i have discovered intragenomic heterogeneity in dna repair in mammalian cells. consequences of unrepaired dna damage depend upon the precise location of the damage with respect to relevant genes. it is therefore important to understand rules governing accessibility of specific dna sequences in chromatin to damage and repair. the efficiency of removal of pyrimidine dimers has been determined in the active dihydrofolate reductase (dhfr) gene in chinese hamster ovary (cho) cells. ...19892698835
mutational analysis of the mouse glucocorticoid receptor.we have cloned the mouse glucocorticoid receptor (gr) from both wild-type and glucocorticoid-resistant variants of the mouse lymphoma cell lines wehi-7 and s49. mapping of the mutations present in the variant receptors, together with deletion analysis of wild-type receptor, reveals that the receptor has three clearly defined domains. the cooh-terminal domain contains the hormone-binding site. within this domain is a small region which is important for the suppression of receptor activity in the ...19892702668
a comparison of colorimetric and clonogenic assays for hypoxic-specific toxins with hamster and human cells.the hypoxic cytotoxicities of misonidazole and pimonidazole (ro 03-8799) towards the human tumor cell lines ht-1080 and lovo have been compared with those seen with chinese hamster v79-379a cells. survival was assayed using two colorimetric assays, either a tetrazolium salt (mtt) or methylene blue, and by conventional colony scoring. the drugs were more cytotoxic towards ht-1080 and lovo cells than v79 cells. the times taken for 10 mmol dm-3 misonidazole to reduce survival to 0.1 surviving fract ...19892703401
antagonist binding properties of five cloned muscarinic receptors expressed in cho-k1 cells.a family of five cholinergic muscarinic receptor genes (m1, m2, m3, m4, and m5) has recently been identified and cloned. in order to investigate the pharmacological properties of the individual muscarinic receptors, we have transfected each of these genes into chinese hamster ovary cells (cho-k1) and have established stable cell lines expressing each receptor. in the present study we have examined the antagonist binding properties of each muscarinic receptor. antagonists were chosen that had pre ...19892704370
role of respiratory-burst products from polymorphonuclear leukocytes in the antitumor activity of propionibacterium acnes vaccine.tumor cells injected into balb/c mice together with heat-killed 48-h p. acnes cells were rendered nontumorigenic as early as 12 h after injection, as determined by the inability of the tumor cells to give rise to tumors when transferred to a new host. determination of tumor cell antigen levels by elisa indicated that the tumour antigens had virtually disappeared by 24 h after injection of tumor cells and p. acnes. in contrast, in control animals injected with tumor cells only, there was an initi ...19892706641
expression of pertussis toxin in bordetella bronchiseptica and bordetella parapertussis carrying recombinant plasmids.pertussis toxin is produced only by strains of bordetella pertussis. cloned genes encoding pertussis toxin from b. pertussis were transferred into bordetella bronchiseptica and bordetella parapertussis by conjugation. these transconjugants expressed pertussis toxin at levels comparable to those expressed by b. pertussis. the toxin made by these strains was biologically active in the chinese hamster cell clumping assay, contained all five subunits, and was mostly periplasmic. toxin expression app ...19892707851
unexpected synergy between n-phosphonacetyl-l-aspartate and cytidine against human tumor cells.cytidine, a non-toxic endogenous nucleoside, was found unexpectedly to augment the cytotoxicity of a pyrimidine antimetabolite n-phosphonacetyl-l-aspartate (pala) in human ovarian carcinoma cells. the pala/cytidine synergy is confirmed here in other human tumor cells (t242 melanoma, hl60 promyelocytic leukemia and skov3 ovarian carcinoma) in the cytidine concentration range of 1-10 micromolar. the synergy was not observed in chinese hamster ovary (cho) cells. exogenous uridine (5-50 microm) comp ...19892714348
insulin receptor and altered glucose transport in a monensin-resistant mutant of chinese hamster ovary cell.a monensin-resistant mutant monr-31, derived from chinese hamster ovary (cho) cell line, has been shown to have a reduced number of insulin receptors and a reduction in glucose uptake in response to insulin. we have further investigated the possibility that altered glucose uptake in monr-31 cells is related to an alteration in the activity of the insulin receptor. uptake of glucosamine, 2-deoxy-d-glucose, and 3-o-methyl-d-glucose in monr-31 cells was one-half to one-third that of cho cells. the ...19892715185
proteolytic generation of constitutive tyrosine kinase activity of the human insulin receptor.structural modification induced by partial digestion with trypsin has been shown to stimulate the tyrosine kinase activity of the insulin receptor both in solution and in intact cells [tamura, fujita-yamaguchi & larner (1983) j. biol. chem. 258, 14749-14752; goren, white & kahn (1987) biochemistry 26, 2374-2382; leef & larner (1987) j. biol. chem. 262, 14837-14842]. furthermore, experiments involving deletion of sequences encoding the extracellular domain of the insulin receptor suggest that it ...19892719663
expression and characterization of recombinant tgf-beta 2 proteins produced in mammalian cells.recombinant dna plasmids coding for transforming growth factor beta 2 (tgf-beta 2) precursor and a hybrid tgf-beta 1(nh2)/beta 2(cooh) molecule consisting of the amino-terminal precursor portion of transforming growth factor-beta 1 (tgf-beta 1) linked in phase to the carboxyl terminus of mature tgf-beta 2 were constructed and transfected into cos cells. both plasmids directed the synthesis of active tgf-beta 2 which was secreted into the supernatants of transfected cells. the tgf-beta 2 was secr ...19892721369
immune response to dimeric subunits of the pertussis toxin b oligomer.immunization of mice with the dimeric subunits of pertussis toxin (s2-s4 and s3-s4) induced an antibody response detectable by enzyme-linked immunosorbent assay and immunoblot techniques. these antibodies were able to neutralize the ability of pertussis toxin to alter the morphology of chinese hamster ovary cells. mice immunized with the dimers were also protected against the leukocytosis-promoting effects of toxin. based on these data, the dimers of pertussis toxin may be considered for further ...19892722238
modulation of mitogenic activity and cellular binding of basic fibroblast growth factor by basic proteins.polycationic molecules were studied either for their ability to displace the binding of basic fibroblast growth factor (bfgf) to high- and low-affinity membrane interaction sites and/or to modulate bfgf-induced proliferation of fibroblasts. heparin-binding polypeptides, such as polylysine, protamine, histones, and thrombin-displaced [125i]bfgf bound to bovine brain membrane receptors. the most displacing polypeptides were those with the strongest affinity to heparin. two of these polypeptides, p ...19892722969
cascade of autophosphorylation in the beta-subunit of the insulin receptor.insulin stimulated autophosphorylation of the beta-subunit of the insulin receptor purified from fao hepatoma cells or purified from chinese hamster ovary (cho/hirc) or swiss 3t3 (3t3/hirc) cells transfected with the wild-type human insulin receptor cdna. autophosphorylation of the purified receptor occurred in at least two regions of the beta-subunit: the regulatory region containing tyr-1146, tyr-1150, and tyr-1151, and the c-terminus containing tyr-1316 and tyr-1322. in the presence of antiph ...19892722971
control of carbohydrate processing: increased beta-1,6 branching in n-linked carbohydrates of lec9 cho mutants appears to arise from a defect in oligosaccharide-dolichol biosynthesis.a correlation between increased beta-1,6 branching of n-linked carbohydrates and the ability of a cell to metastasize or to form a tumor has been observed in several experimental models. lec9 chinese hamster ovary (cho) mutants exhibit a drastic reduction in tumorigenicity in nude mice, and this phenotype directly correlates with their ability to attach an increased proportion of beta-1,6-branched carbohydrates to the g glycoprotein of vesicular stomatitis virus (j. ripka, s. shin, and p. stanle ...19892725506
an rna polymerase i promoter located in the cho and mouse ribosomal dna spacers: functional analysis and factor and sequence requirements.we report results of experiments in which we demonstrated the existence of a polymerase i promoter within the ribosomal dna spacer upstream from the rrna initiation site in chinese hamsters and mice. transcription of the cho spacer promoter was achieved by the same protein factors, c and d, that catalyzed transcription of the gene promoter, and these factors bound stably to the cho spacer promoter in a preinitiation complex, just as they did to the gene promoter. in contrast to the cho spacer pr ...19892725513
demethylation enhances removal of pyrimidine dimers from the overall genome and from specific dna sequences in chinese hamster ovary cells.we have examined the effects of changes in cytosine methylation on dna repair in uv-irradiated chinese hamster ovary (cho) cells. a hypomethylated derivative of the cho k1b11 line, b11aza, was established by passaging b11 cells over several months in increasing concentrations of 5-azacytidine; greater than 60% demethylation was consistently demonstrated in these conditioned cells. following a uv dose of 10 j/m2, the amount of repair replication performed within 24 h was approximately twofold hig ...19892725518
complementation of a methotrexate uptake defect in chinese hamster ovary cells by dna-mediated gene transfer.a methotrexate-resistant chinese hamster ovary cell line deficient in methotrexate uptake has been complemented to methotrexate sensitivity by transfection with dna isolated from either wild-type chinese hamster ovary or human g2 cells. primary and secondary transfectants regained the ability to take up methotrexate in a manner similar to that of wild-type cells, and in the case of those transfected with human dna, to contain human-specific dna sequences. the complementation by dna-mediated gene ...19892725523
skin photosensitivity and photodestruction of several potential photodynamic sensitizers.the major side effect associated with porphyrins (photofrin ii) in clinical photodynamic therapy is skin photosensitivity. in order to avoid this deleterious reaction, patients must remain out of the sunlight for approximately 1 month. a possible procedure to reduce the amount of skin photosensitivity is to photodegrade (photobleach) the compound in the skin. in this study, we report a series of experiments describing the photodegradation rates of two photosensitizers currently receiving attenti ...19892727082
characterization of four different mammalian-cell-derived recombinant human interferon-beta 1s. identical polypeptides and non-identical carbohydrate moieties compared to natural ones.in order to evaluate the structural identification of various recombinant human interferon-beta 1s, the recombinant proteins were produced in four different mammalian cells (human pc12 and pc8 lung adenocarcinoma cells, chinese hamster ovary cells and mouse c127 cells) and characterized. each mammalian-cell-derived recombinant human interferon-beta 1 represented a single band of 23 kda on sodium dodecyl sulphate/polyacrylamide gel electrophoresis, the same molecular mass as fibroblast-derived na ...19892731537
localization of adriamycin in model and natural membranes. influence of lipid molecular packing.the interaction of adriamycin with lipids was studied in model (monolayers, small unilamellar vesicles, large multilamellar vesicles) and natural (chinese hamster ovary cell) membranes by measurement of fluorescence energy transfer and fluorescence quenching. 2-apam, 7-aste, 12-aste and anthracene-phosphatidylcholine were used as fluorescent probes in which the anthracene group is well located at graded depths in the membrane. egg-yolk phosphatidylcholine and a 1/1 mixture of it with bovine brai ...19892731543
gene transfer and expression of human ornithine aminotransferase.a generalized deficiency in the mitochondrial enzyme, ornithine aminotransferase (oat), is present in the hereditary blinding disease, gyrate atrophy (ga). because the oat gene is a multi-gene family, and the native oat enzyme is an oligomer, it would be important to identify the gene locus actually responsible for the oat activity and affected in ga. a mammalian expression clone containing a previously characterized human oat cdna (phoat), corresponding to the oat gene on chromosome 10, was pre ...19892732018
the relationship between dna damage and mutation frequency in mammalian cell lines treated with n-nitroso-n-2-fluorenylacetamide.the induction of dna single-strand breaks in c3h10t1/2 mouse fibroblasts and chinese hamster ovary (cho) cells by n-nitroso-n-2-fluorenylacetamide (n-no-2-faa) was demonstrated by the alkaline elution technique. without metabolic activating system (i.e., rat liver s9 fraction), n-no-2-faa exhibits more direct and strong damaging effects on dna than its parent compound, 2-faa, at equal concentration in both cell lines. to compare the dna-damaging potency of n-no-2-faa with other well-known carcin ...19892733714
differential cytotoxicity of sodium arsenite in human fibroblasts and chinese hamster ovary cells.human skin fibroblast (hf) cells were approximately 10-fold more sensitive to sodium arsenite toxicity than chinese hamster ovary (cho) cells using the clonogenic assay. g1-phase cho cells showed a 2-fold increase in the susceptibility to the toxic effects of sodium arsenite as compared to asynchronous cho cells. the concentrations of sodium arsenite required to kill 50% of the cell population were correlated with the intracellular glutathione levels in asynchronous, g1-phase cho, and asynchrono ...19892734807
kinetic analysis of cell killing effect induced by cytosine arabinoside and cisplatin in relation to cell cycle phase specificity in human colon cancer and chinese hamster cells.we presented a cell kill pharmacodynamic model for cell cycle phase-specific antitumor agents as well as that for cell cycle phase-nonspecific agents. the former was based upon assumptions that a cell population could be divided into a drug-sensitive population having sensitive (or specific) cell cycle phase(s) and a drug-resistant population in resistant cell cycle phases. this model revealed that cell killing action of antitumor agents with sufficient cell cycle phase specificity was time depe ...19892736524
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