PMID(sorted ascending)
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
transferrin-receptor-independent but iron-dependent proliferation of variant chinese hamster ovary cells.the purpose of this study is to clarify the role of iron, transferrin, an iron-binding protein in vertebrate plasma, and transferrin receptors in cell proliferation. transferrin, which is indispensable for most cells growing in tissue culture, is frequently referred to as a "growth factor". proliferating cells express high numbers of transferrin receptors, and the binding of transferrin to their receptors that is needed for cells to initiate and maintain their dna synthesis is sometimes regarded ...19921397086
the relationship between hsp 70 localization and heat resistance.using indirect immunofluorescence we have investigated the kinetics of nuclear accumulation and removal of hsp 70 in ha-1 chinese hamster fibroblasts exposed to elevated temperatures. the kinetics of accumulation of hsp 70 in the nuclei were found to be time/temperature dependent at all temperatures tested (42-45 degrees c). at a given temperature, the fraction of cells manifesting nuclear localization of hsp 70 increased with exposure time. for a given duration of heating, the fraction of cells ...19921397103
native and recombinant soluble cd23 fragments with ige suppressive activity.cd23-bearing cells are known to release 37,000 33,000 and 25,000 mw soluble cd23 (scd23) fragments that were reported to display multiple biological activities, including the potentiation of ige synthesis. we previously reported that tunicamycin treatment of rpmi-8866 cells switched the biological activity of the scd23 released by these cells from ige potentiation to ige suppression. in this study we show that tunicamycin-treated cells release small cd23 fragments with a mw of 16,000. these frag ...19921398755
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
biphasic activation of two mitogen-activated protein kinases during the cell cycle in mammalian cells.we studied mitogen-activated protein kinase (mapk) activities during the cell cycle of chinese hamster ovary (cho) cells using site-specific antibodies against extracellular signal-regulated kinase-1, a 44-kda mapk (boulton, t.g., yancopoulos, g.d., gregory, j.s., slauer, c., moomaw, c., hsu, j., and cobb, m.h. (1990) science 249, 64-67). these antibodies detected two distinct mapks (44- and 42-kda mapks) in cho cells. cho cells were arrested at metaphase in the m phase by treatment with nocodaz ...19921400347
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
the plant amino acid mimosine may inhibit initiation at origins of replication in chinese hamster understanding of replication initiation in mammalian cells has been hampered by the lack of mutations and/or inhibitors that arrest cells just prior to entry into the s period. the plant amino acid mimosine has recently been suggested to inhibit cells at a regulatory step in late g1. we have examined the effects of mimosine on cell cycle traverse in the mimosine [corrected]-resistant cho cell line choc 400. when administered to cultures for 14 h after reversal of a g0 block, the drug appears ...19921406627
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
the effect of monosaturated and polyunsaturated fatty acids on oxygen toxicity in cultured cells.the influence of oleic, linoleic (lin), and eicosapentaenoic (epa) acids incorporated into cellular lipids on susceptibility to o2-induced toxicity was evaluated in chinese hamster fibroblasts (ha1) using a clonogenic cell survival assay. fatty acid incorporation was achieved by incubating ha1 cells in 21% o2 for 72 h in the presence or absence of media supplemented with 25 microm oleic acid, 25 microm lin, or 2, 4, and 25 microm epa. this fatty acid incorporation period increased the percentage ...19921408477
end extension repair of introduced targeting vectors mediated by homologous recombination in mammalian cells.we have studied the mechanism of targeted recombination in mammalian cells using a hemizygous adenine phosphoribosyltransferase-deficient (aprt-) chinese hamster ovary (cho) cell mutant as a recipient. three structurally different targeting vectors with a 5' or a 3', or both, end-deleted aprt sequence, in either a closed-circular or linear form, were transfected to the cells with a mutated aprt gene by electroporation. aprt-positive (aprt+) recombinant clones were selected and analyzed to study ...19921408793
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
translocation of apolipoprotein b across the endoplasmic reticulum is blocked in a nonhepatic cell explore the process of lipoprotein assembly, plasmids encoding truncated forms of apolipoprotein b (apob) were transfected into chinese hamster ovary (cho) fibroblasts. (one, encoding apob53, the n-terminal 53% of apob100, can direct the assembly and secretion of lipoproteins when expressed in hepatoma cells, while the other, encoding the shorter apob15, does not direct lipoprotein assembly.) expression of apob15 in cho cells resulted in the accumulation of apob15 protein in both medium and c ...19921409618
imaging of luciferase secretion from transformed chinese hamster ovary cells.the blue luminescence characteristic of the marine ostracod crustacean vargula hilgendorfii is from a simple, but highly specific, enzyme-substrate reaction. light is emitted by the oxidation of vargula luciferin (substrate) by molecular oxygen, a reaction catalyzed by luciferase. stable transformants of chinese hamster ovary cells carrying the vargula luciferase gene secreted luciferase from discrete sites on the cell surface, and this secretion could be monitored in real time by the biolumines ...19921409669
interaction between radiation and drug damage in mammalian cells. vi. radiation and doxorubicin age-response function of doxorubicin-sensitive and -resistant chinese hamster cells.a comparative study of the radiation and/or doxorubicin (dox) survival response for synchronous populations of chinese hamster v79 cells and two dox-resistant variants (77a and lz-8) was performed. the greatest cellular radiation sensitivity was observed in mitosis, while the greatest resistance was observed during late s phase for the three cell lines. the variation in radiation response throughout the cell cycle was expressed as a change in the width of the shoulder of the survival curves (dq) ...19921410265
identification of nitroxide radioprotectors.the nitroxide tempol, a stable free radical, has recently been shown to protect mammalian cells against several forms of oxidative stress including radiation-induced cytotoxicity. to extend this observation, six additional water-soluble nitroxides with different structural features were evaluated for potential radioprotective properties using chinese hamster v79 cells and clonogenic assays. nitroxides (10 mm) were added 10 min prior to radiation exposure and full radiation dose-response curves w ...19921410280
radioprotection of dna in isolated nuclei by naturally occurring thiols at intermediate oxygen tension.incubation of isolated chinese hamster ovary cell nuclei, equilibrated in an atmosphere containing 2% o2, with glutathione, cysteine, or cysteamine resulted in a decrease in the number of x-ray-induced dna double-strand breaks (dsbs), determined by ph 9.0 filter elution. in the absence of exogenous thiol, no sensitization was observed with the addition of n-ethylmaleimide, indicating that endogenous thiols were not present at significant levels. protection by 0.3 mm glutathione was not enhanced ...19921410281
radiosensitizing and repair-inhibiting properties of dipyridamole.radioresistance and postirradiation repair of potentially lethal damage (pld repair) are important factors underlying failure to control local disease in cancer. dipyridamole (dp) is known as a modifier of the action of cytotoxic drugs. we therefore investigated dp as a potential radiosensitizer and inhibitor of pld repair in x-irradiated chinese hamster ovary (cho) cells in vitro. exposure to the drug alone resulted in a slight reduction of the clonogenic capacity of the cells. preincubation fo ...19921410580
[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
the study of the cultivation of chinese hamster ovary and bowes cell lines with poly(organophosphazene) membranes.sixteen poly(organophosphazenes) were prepared by reaction between polydichlorophosphazene (npcl2)n and nucleophilic reagents such as phenoxides and amino compounds. adhesive and colony formation percent were investigated using v-79 chinese hamster cells on poly(organophosphazene) films. it was found that [np(oc6h5)2-x(nhbu-n)x]n (x = 0.2, 1.8) gave the best percent adhesiveness. this value was similar to that of falcon. on the other hand, [np(oc6h5)-(nhbu-n)]n film showed best colony percent fo ...19921416954
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
decreased affinity of recombinant antithrombin for heparin due to increased glycosylation.recombinant antithrombin produced by baby hamster kidney (bhk) or chinese hamster ovary (cho) cells was separated into two fractions, containing comparable amounts of protein, by affinity chromatography on matrix-linked heparin. fluorescence titrations showed that the more tightly binding fraction had a heparin affinity similar to that of plasma antithrombin (kd approximately 20 nm), whereas the affinity of the more weakly binding fraction was nearly 10-fold lower (kd approximately 175 nm). anal ...19921417738
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
calmodulin-specific monoclonal antibodies inhibit dna replication in mammalian cells.the involvement of calmodulin in the proliferation of chinese hamster embryo fibroblast cells has been studied with a specific monoclonal antibody to calmodulin. we observed that calmodulin levels increase 2-fold in the late g1 period in these cells, and this coincides with the increase in dna polymerase alpha activity as the cells progress synchronously from a quiescent state in the g1 to the s phase. however, there is a concurrent 10-fold enhancement of thymidine kinase activity, which is tigh ...19921420160
[toxic effects of heavy metal salts on intact and irradiated cultured mammalian cells].the toxicity of solutions of k2cr2o7 and niso4.8h2o for cultivated chinese hamster fibroblasts and murine lymphoma sp-2 cells was determined using three criteria of damage: cell death (dyeing with trypan blue), inhibition of cell proliferation and their colony-forming activity. it was shown that both salts have equal toxicity in (10(-3)-10(-2)) m interval for both culture investigated relative to inhibition of cell proliferation. the threshold of toxicity of k2cr2o7 relative to reproductive cell ...19921421226
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
induction of sister chromatid exchanges by extremely low doses of alpha-particles.the induction of sister chromatid exchanges (sce) was examined in chinese hamster ovary cells irradiated in the g1 phase of the cell cycle with alpha-particles from a plutonium-238 source. a significant increase in the frequency of sce occurred with doses as low as 0.31 mgy (31 millirads). although 30% of the cells showed an increased frequency of sce at this dose, less than 1% of cell nuclei were actually traversed by an alpha-particle. a dose of approximately 2.0 gy was necessary to produce a ...19921423287
expression of the endogenous o6-methylguanine-dna-methyltransferase protects chinese hamster ovary cells from spontaneous g:c to a:t transitions.we have investigated whether the presence of a dna repair enzyme, o6-methylguanine-dna-methyltransferase (mgmt), affects the nature of spontaneous mutations in a mammalian cell line. we compared spontaneous mutations in the adenine phosphoribosyl transferase gene of a chinese hamster ovary (cho) cell line that expressed 14,000 mgmt molecules/cell with those in the parental cho cells lacking this dna repair activity. the mutation rate/cell/generation of the two cho cell lines did not differ signi ...19921423294
identification of the eleventh complementation group of uv-sensitive excision repair-defective rodent mutants.the drug-sensitive mutant uvs1, isolated from the chinese hamster cell line cho9, was previously found to complement the uv sensitivity of the excision repair-defective rodent mutants representative of groups 1 to 8 (hata et al., cancer res., 51: 195-198, 1991; m. numata et al., personal communication). recently two new complementation groups of uv-sensitive cho mutants, e.g., groups 9 and 10, have been identified (stefanini et al., cancer res., 51: 3965-3971, 1991). in this paper we demonstrate ...19921423315
the ts41 mutation in chinese hamster cells leads to successive s phases in the absence of intervening g2, m, and g1.the ts41 mutation of chinese hamster cells was first isolated and characterized by hirschberg and marcus (1982) who showed that at nonpermissive temperature, cells accumulate up to 16c equivalents of dna. here we show that the mutation is recessive and at nonpermissive temperature, cells replicate their genome normally, but instead of going on into g2, m, and g1, they pass directly into a second s phase. entry into a second s phase does not require serum nor is it inhibited by g2 checkpoints or ...19921423617
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
analysis of residual amino acid--dna crosslinks induced in intact cells by nickel and chromium compounds.chinese hamster ovary cells were incubated with radioactive amino acids, the dna was isolated by standard proteinase k/phenol/chloroform extraction and residual amino acids complexed to the dna were examined as an index of metal induced dna-protein crosslinks. using this method, both chromate and nickel caused residual histidine and cysteine to be complexed with the dna isolated from metal-treated cells. in the case of chromate, a number of amino acids were studied and tyr, thr and cys were foun ...19921423835
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
repair of mitochondrial dna after various types of dna damage in chinese hamster ovary cells.using methodology recently developed to assess gene-specific dna repair, we have demonstrated that it is possible not only to study mitochondrial dna repair, but also directly to compare mitochondrial and nuclear dna repair in the same biological sample. complex enzymatic mechanisms recognize and repair nuclear dna damage, but it has long been thought that there was no dna repair in mitochondria. therefore, in an attempt to delineate more clearly which dna repair mechanisms, if any, are function ...19921423864
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
mutational specificity of chromium(vi) compounds in the hprt locus of chinese hamster ovary-k1 cells.chromium(vi) compounds exert their genotoxicity and mutagenicity by complex metabolic reducing pathways that generate a variety of reactive forms of chromium and free radicals. to investigate the molecular nature of chromium-induced mutations, we characterized the entire coding region of the hypoxanthine (guanine) phosphoribosyltransferase (hprt) gene of 27 independent mutants derived from chromium(vi) oxide (cro3)-treated chinese hamster ovary-k1 cells, by direct sequencing of pcr-amplified cdn ...19921423875
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
2,4-dichlorophenoxyacetic acid action on in vitro protein synthesis and its relation to polyamines.the effect of 2,4-dichlorophenoxyacetic acid (2,4-d) on the in vitro synthesis of proteins was studied in chinese hamster ovary cells. a remarkable inhibition of the synthesis of proteins was observed when cells grew for 24 h in presence of 1 mm 2,4-d. this effect was reversed by adding 0.1 mm of the three polyamines (putrescine, spermidine and spermine) to the cultured cells. the mrna is not altered, indicating that the 2,4-d action is located at a different locus, which may be the ribosomes. f ...19921425363
selective removal of glycosylation sites from sex hormone-binding globulin by site-directed 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 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
characterization of a gain of function mutation of integrin alpha iib beta 3 (platelet glycoprotein iib-iiia).integrin alpha iib beta 3 (platelet glycoprotein iib-iiia) is a prototype of integrins involved in cellular adhesive functions. as part of a structure-function analysis of this molecule, we constructed a mutant, designated alpha iib beta 3 (beta 1-2), by replacing 6 amino acids within a putative ligand binding domain of the beta 3 subunit with sequences derived from beta 1. the alteration did not affect the capacity of beta 3(beta 1-2) to combine with transfected alpha iib, nor did it cause it t ...19921429573
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
sphingolipids are essential for the growth of chinese hamster ovary cells. restoration of the growth of a mutant defective in sphingoid base biosynthesis by exogenous sphingolipids.we previously isolated a temperature-sensitive chinese hamster ovary cell mutant (strain spb-1) with thermolabile serine palmitoyltransferase, which is involved in the first step of sphingolipid synthesis (hanada, k., nishijima, m., and akamatsu, y. (1990) j. biol. chem. 265, 22137-22142). in this study, sphingolipid-deficient culture medium was used to examine the effect of exogenous sphingolipids on the cell growth of spb-1. when cultivated in the sphingolipid-deficient medium, spb-1 cells cea ...19921429697
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
photodynamic properties of naphthosulfobenzoporphyrazines, novel asymmetric, amphiphilic phthalocyanine derivatives.metallo naphthosulfobenzoporphyrazines sulfonated to different degrees (m-nsbp) were prepared, and their potential as photosensitizers for the photodynamic therapy (pdt) of cancer was evaluated. m-nsbp can be viewed as hybrid molecules between sulfophthalocyanines and naphthalocyanines resulting in distinct differences in the absorption spectra between the mono-through tetrasulfonated derivatives. this feature greatly facilited their purification. using v-79 chinese hamster cells in vitro, the d ...19921432390
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
the effect of partial hepatectomy on the genotoxicity of aflatoxin b1. ii.the influence of partial hepatectomy (ph) on the genotoxic effect of aflatoxin b1 (afb1) mycotoxin in male chinese hamsters (cricetulus griseus) in vivo was studied after a repeated i.p. application of small doses of afb1 during 8 weeks. the frequency of aberrant cells did not increase after repeated application and persisted throughout the whole period on a relatively stable level. no cumulative genotoxic effect of repeated doses of afb1 was observed. ph decreased the genotoxic effect of afb1 o ...19921436236
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
a fourth complementation group among ionizing radiation-sensitive chinese hamster cell mutants defective in dna double-strand break repair.the xr-v9b mutant of chinese hamster v79 cells which exhibits hypersensitivity to ionizing radiation was isolated by the replica plating technique. the increased sensitivity of xr-v9b cells to x rays (approximately 4-fold, as judged by the d10) was accompanied by increased sensitivity to other dna-damaging agents such as bleomycin (approximately 17-fold), vp16 (approximately 6-fold), and adriamycin (approximately 5-fold). only a slightly increased sensitivity was observed after exposure to uv ra ...19921438689
molecular cloning of a gene involved in methotrexate uptake 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 a wild-type chinese hamster ovary genomic cosmid library. primary and secondary transfectants, which contain a limited number of cosmid sequences, have been shown to regain methotrexate sensitivity and to take up methotrexate. furthermore, the dna from three cosmid clones, isolated from a primary methotrexate-sensitive ...19921440056
[the effect of 3-aminobenzamide on the mitotic cycle of chinese hamster cells cultured on a medium with 5-bromodeoxyuridine following ionizing radiation action].a specific inhibitor of poly(adp-ribose)polymerase-3-aminobenzamide (6 mm) has been shown to: 1) reduce survival of non-irradiated cho-k1 cells, cultivated in medium containing 5-bromodeoxyuridine (10 mkm, bdu cells), and increase their radiosensitivity; 2) induce g2 delay in bdu cells while progressing through the cell cycle as analysed by the dna flow cytometry; 3) increase to a great degree g2 delay in x-irradiated bdu cells. 3-aminobenzamide is primarily effective when it is present during t ...19921440933
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 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 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
quantitative mapping of the n-linked sialyloligosaccharides of recombinant erythropoietin: combination of direct high-performance anion-exchange chromatography and 2-aminopyridine derivatization.a rapid quantitative analysis of the sialylated n-linked oligosaccharides of recombinant erythropoietin (epo) expressed in chinese hamster ovary (cho) cells has been developed. the procedure utilizes a glycoamidase (glycopeptidase f) to release all of the n-linked oligosaccharides from the native glycoprotein, followed by direct chromatographic analysis using high-performance anion-exchange chromatography (hpaec) with pulsed amperometric detection. the eight sialyloligosaccharides isolated from ...19921443598
comparative study of sexual dimorphism of the innominate bone in rodents and amphibians.sexual dimorphism in the shape of the innominate bone was demonstrated in the rat, mouse, chinese hamster (cricetulus griseus), frog (ranna nigromaculata), and newt (cynops pyrrhogaster) with a computer-assisted morphometric technique. in the rat, mouse, and hamster, ratios of ischium and pubis widths to the innominate bone length (inl) were larger in the males than in the females; however, the ratio of pubis length to inl was larger in the females than in the males. in the frog, the ratio of di ...19921443668
lec15 cells transfer glucosylated oligosaccharides to protein.b4-2-1 cells (lec15 cells) are chinese hamster ovary cells deficient in mannosylphosphoryldolichol synthase activity. they synthesize the truncated lipid intermediate man5glcnac2-p-p-dolichol rather than the glc3man9glcnac2-p-p-dolichol synthesized by wild-type cells. in this report we present evidence that these cells did synthesize glucosylated man5glcnac2-p-p-dolichol, but this species represented only a minor fraction of the labeled oligosaccharide-lipid. on the other hand, glucosylated olig ...19921444460
characterization of glut3 protein expressed in chinese hamster ovary cells.we have expressed glut3 protein, an isoform of a facilitative glucose transporter, in chinese hamster ovary cells by transfection of its cdna using an expression vector. the expressed glut3 protein was detected by western-blot analysis as a broad band of 45-65 kda, indicating intensive glycosylation of the protein. the expressed glut3 protein was observed, by immunofluorescence staining, to be located mainly at the plasma membrane, and its expression was associated with a marked increase in gluc ...19921445263
production and ligand-binding characteristics of the soluble form of murine erythropoietin receptor.a recombinant soluble form (sepo-r) of erythropoietin (epo) receptor (epo-r) was produced by chinese hamster ovary cells and isolated in high yield with the epo-fixed gel. ligand binding assays were done using three methods; precipitation of sepo-r radiolabeled epo complex and competition of sepo-r for the binding of radiolabeled epo with the cellular epo-r. the results showed a kd of 17 nm which was much lower than those for cellular epo-r. one n-glycosylation site exists in sepo-r but the glyc ...19921445329
pi-specific phospholipase c "alpha" from sheep seminal vesicles is a proteolytic fragment of pi-plc delta.phosphatidylinositide-specific phospholipase c enzymes (plcs) catalyze the conversion of the phosphoinositides to biologically important signal transducing molecules. these enzymes may be grouped into "families" which share similar structures and modes of regulation. the existence of a structurally distinct family of plc termed "alpha" has been recently called into question. in the current paper we show by immunoblotting experiments that plc "alpha" from sheep seminal vesicles is recognized by m ...19921445352
cholera toxin diminishes tyrosine kinase activity of the insulin receptor.we have examined the effect of cholera toxin (ct) on the insulin receptor tyrosine kinase. incubation of intact rat hepatoma cells fao with ct (1 microgram/ml/2h) inhibited insulin-induced receptor autophosphorylation by 30% in vivo. this effect persisted after receptor purification in vitro. ct did not alter hormone binding of the insulin receptor, indicating that the toxin affects signal transduction of insulin at the level of the receptor kinase. experiments using chinese hamster ovary (cho) ...19921445389
identification and fate of a marker chromosome in methotrexate-resistant v79,b7 cells by flow karyotyping and sorting, metaphase analysis and in situ hybridization.the chromosomes from a methotrexate (mtx)-resistant and its parental v79,b7 chinese hamster cell line were analysed by the combined use of flow karyotyping and sorting, metaphase analysis and in situ hybridization with a probe for the dihydrofolate reductase (dhfr) gene responsible for methotrexate resistance. a marker chromosome with an elongated arm carrying the amplified dhfr gene was identified by in situ hybridization of metaphase cells of the methotrexate-resistant line. in the flow karyot ...19921445793
enhanced stimulation of follicle maturation and ovulatory potential by long acting follicle-stimulating hormone agonists with extended carboxyl-terminal peptides.the induction of granulosa cell differentiation and follicle maturation is dependent upon the stimulatory actions of fsh. our recent studies used recombinant dna technology to fuse the carboxyl-terminal peptide (ctp) of hcg beta-subunit to the carboxyl-terminus of the fsh beta-subunit. the resulting fsh analog has identical in vitro receptor-binding and biological activities as wild-type fsh (wt-fsh), but an increased circulating half-life. the present studies examined further the ability of fsh ...19921446593
improvement in the heterogeneous n-termini and the defective n-glycosylation of human interleukin-6 by genetic engineering.recombinant human interleukin-6 (il-6), expressed in chinese hamster ovary cells, has heterogeneous n-termini of ala1 and val3, as does naturally occurring il-6. this heterogeneity is thought to be caused by difficulty in cleavage of the signal sequence. to obtain homogeneous il-6, pro at -1 was exchanged for ala by site-directed mutagenesis. alternatively, the signal sequence was replaced with that of human granulocyte-colony-stimulating factor. in both cases, the il-6 designed to start with al ...19921446688
genetically engineered v79 chinese hamster cells for stable expression of human cytochrome p450ia2.v79 chinese hamster cells were genetically engineered for stable expression of human p450ia2. full length cdna, encoding human p450ia2, was inserted into an sv40 early promoter containing eukaryotic expression vector and cointroduced with the selection marker neomycin phosphotransferase (conferring resistance to the neomycin derivative g418) into v79 chinese hamster cells. the recombinant expression vector was introduced into two different v79 sublines, one expressing an endogenous acetyltransfe ...19921446722
[a line of chinese hamster cells containing human chromosome 18]. 19921446812
[role of activated cellular c-ha-ras-1 oncogene in the mutagenic effect of the plasmid pej6.6].the role of the activated oncogene c-ha-ras-1 from human bladder carcinoma integrated into the pej6.6 plasmid in the mutagenic effect of the plasmid was studied in chinese hamster cells. the frequency of hypoxanthine-phosphoribosyltransferase defective (hprt-) mutants after treatment with pej6.6 containing an active c-ha-ras-1 exceeded that in control dishes treated with a derivative of pej6.6 plasmid with an inactivated oncogene. the inactivation was achieved by introducing a deletion into the ...19921446813
cell surface expression of the c3b/c4b receptor (cr1) protects chinese hamster ovary cells from lysis by human complement.the c3b/c4b receptor, also known as complement receptor type 1 (cr1, cd35), is a single chain glycoprotein consisting of 30 repeating homologous protein domains known as short consensus repeats (scr) followed by transmembrane and cytoplasmic domains. a series of recombinant proteins derived from cr1 has been prepared and assessed for the capacity to inhibit complement lysis of the host chinese hamster ovary (cho) cells. the full-length recombinant cr1 inhibited human complement-mediated cho cell ...19921447213
[flow cytometric analysis of chromosome aberration on tumor cells].chromosomal changes plays an important role in malignant transformation. generally, the process of karyotype instability with grows aneuploidy occurs in tumor. but it is very difficult to obtained flow karyotype from tumor cells. there are many technical problem in the analysis of chromosomes aberration in tumor cells. problem is technical procedure of isolation from metaphase chromosomes. it is important to choice of swelling buffer and treatment times. such technic affect for flow karyotype pa ...19921447821
identification of a cysteine-rich receptor for fibroblast growth factors.the fibroblast growth factor (fgf) family consists of seven members whose activities are thought to be mediated by multiple receptors. here we describe the cdna cloning, expression, and characterization of a cysteine-rich fgf receptor (cfr) that is distinct from previously identified fgf receptors. the deduced amino acid sequence for cfr suggests that it is an integral membrane protein containing a large extracellular domain comprising 16 cysteine-rich repeated units and an intracellular domain ...20041448090
structural and functional analysis of the insulin-like growth factor i receptor gene promoter.the insulin-like growth factor i receptor (igf-i-r) gene is expressed in most body tissues. the levels of igf-i-r mrna, however, are regulated by a number of physiological conditions (development, differentiation, and hormonal milieu) as well as in certain pathological states (diabetes and tumors). to understand the molecular mechanisms which control the transcription of the igf-i-r gene, we have cloned the promoter of the rat receptor gene and have characterized its activity by transient expres ...19921448110
application of plasma desorption mass spectrometry to molecular weight determination of human interleukin-4 secreted by a chinese hamster ovary line. 19921449214
dolichol metabolism in chinese hamster ovary cells.the addition of oligosaccharide to asparagine residues of soluble and membrane-associated proteins in eukaryotic cells involves a polyisoprenoid lipid carrier, dolichol. in chinese hamster ovary cells, the major isomer of this polyisoprenol has 19 isoprenyl units, the terminal one being saturated. our laboratory has developed a procedure to analyze the levels and nature of the cell's dolichyl derivatives. chinese hamster ovary cells contain predominately activated, anionic dolichol derivatives, ...20051449705
quantification by laser scan microscopy of intracellular doxorubicin distribution.changes in intracellular drug localization accompany doxorubicin resistance in multidrug resistant tumor cells. the purpose of this study was to develop a method to quantify these changes and so detect different levels of resistance. tumor cells were incubated with the fluorescent anthracycline doxorubicin (excitation at 480 nm; emission maximum at 560-590 nm) and were quantified using laser scanning microscopy. the fluorescent mode was used to record the intracellular drug distribution, whereas ...19921451589
flow cytometric measurement of lipid peroxidation in vital cells using parinaric acid.a method for measuring lipid peroxidation using time resolved flow cytometry is described. because of its chemical nature, the naturally fluorescent fatty acid cis-parinaric acid is readily consumed in lipid peroxidation reactions. it could be loaded into chinese hamster ovary cells in a time and concentration dependent manner at 37 degrees c, with 5 microm for 60' giving consistent, bright fluorescence without evidence of cytotoxicity. examination of cells by fluorescence microscopy showed diff ...19921451599
molecular determinants of human prorenin humans, active renin is generated by the removal of a 43-amino acid prosegment from the zymogen prorenin. this cleavage event is highly specific, occurring at only one of the seven pairs of basic amino acids in the body of preprorenin. this cleavage site selectivity is also displayed by a number of other proteases in vitro and in mouse pituitary att-20 cells transfected with a human preprorenin expression vector, suggesting that specificity of cleavage is directed in part by the primary seque ...19921452293
construction of a diphtheria toxin a fragment-c180 peptide fusion protein which elicits a neutralizing antibody response against diphtheria toxin and pertussis toxin.a genetically engineered gene fusion was constructed which encoded a nontoxic derivative of the a fragment of diphtheria toxin joined to the c180 peptide of the s1 subunit of pertussis toxin. the product of this gene fusion, termed the dta-c180 protein, was purified from the periplasm of escherichia coli to approximately 80% purity. the dta-c180 protein possessed an apparent molecular weight of 43,000 by reduced sodium dodecyl sulfate-polyacrylamide gel electrophoresis. the dta-c180 protein was ...19921452339
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