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[a double-blind, cross-over clinical trial of recombinant human g-csf on neutropenia induced by chemotherapy for non-hodgkin's lymphoma].a double-blind, placebo-controlled, cross-over clinical trial of recombinant human granulocyte colony-stimulating factor (rg-csf), produced by chinese hamster ovary cells, was conducted in 46 patients receiving intensive chemotherapy for non-hodgkin's lymphoma. each patient received 2 cycles of chop therapy. rg-csf (2 micrograms/kg/day) or its placebo was given subcutaneously to each patient for 14 days from 2 days after initiation of the chemotherapy, in a cross-over fashion. rg-csf significant ...19901702132
cloning and expression of n-acetylglucosaminyltransferase i, the medial golgi transferase that initiates complex n-linked carbohydrate formation.this laboratory has previously identified a human gene encoding n-acetylglucosaminyltransferase i (glcnac-ti; ec 2.4.1.101) by complementation of the glycosylation defect in the lec1 chinese hamster ovary (cho) cell mutant. a phage lambda library prepared from genomic dna of a tertiary lec1 transfectant (3 degrees t) has now been used to obtain clones encoding an active glcnac-ti enzyme. a small genomic dna fragment [approximately 4.6 kilobases (kb)], isolated from an alupositive lambda clone, c ...19901702225
abnormal sister-chromatid exchange induction by 3-aminobenzamide in an sv40-transformed indian muntjac cell line: relationships with dna maturation and dna-strand breakage.in svm cells, an sv40-transformed line of indian muntjac fibroblasts, levels of sister-chromatid exchanges are known to be abnormally high after uv-irradiation or alkylation. the svm line is also known to have a defect in the processing of dna-strand breaks. sister-chromatid exchange in other cells is known to be stimulated by the poly(adp-ribose) transferase inhibitor, 3-aminobenzamide, which also retards dna-break sealing. sister-chromatid exchanges in svm cells are found to be hypersensitive ...19911702517
sex-dependent and independent expression of the p-glycoprotein isoforms in chinese hamster.p-glycoprotein (pgp) is a small family of membrane proteins which belongs to a superfamily of energy-dependent membrane transport proteins identified in phylogenetically distant species, from bacteria to man. among mammalian species, some of the pgp isoforms can mediate multidrug resistance by acting as an energy-dependent drug efflux pump. however, the physiologic functions of the pgp isoforms have not been defined. in this study we examined the expression of the three hamster pgp isoforms in n ...19901703163
localization of dna adducts induced by n-acetoxy-n-2-acetylaminofluorene in chinese hamster ovary cells using electron microscopy and colloidal gold.dna adduct induction by n-acetoxy-n-2-acetylaminofluorene (n-ac-aaf) has been investigated in chinese hamster ovary (cho) cells using immunoelectron microscopy. the major rna and dna adducts, n-(guanosin-8-yl)-2-aminofluorene (g-c8-af) and n-(deoxyguanosin-8-yl)-2-aminofluorene (dg-c8-af), were localized with a rabbit anti-g-c8-af antiserum and colloidal gold cytochemistry. appropriate controls, including incubation of untreated cells with normal rabbit serum and immunogen-absorbed serum, demons ...19901703779
generation of camp-activated chloride currents by expression of cftr.mutations in the cystic fibrosis transmembrane conductance regulator (cftr) cause cystic fibrosis. in order to evaluate its function, cftr was expressed in hela, chinese hamster ovary (cho), and nih 3t3 fibroblast cells, and anion permeability was assessed with a fluorescence microscopic assay and the whole-cell patch-clamp technique. adenosine 3',5'-monophosphate (camp) increased anion permeability and chloride currents in cells expressing cftr, but not in cells expressing a mutant cftr (delta ...19911704151
evidence for allelic exclusion in chinese hamster ovary cells.earlier results suggested that the functional hemizygosity of genes in pseudodiploid chinese hamster ovary (cho) cells is due to the silencing of one allele by dna methylation. from this one could make a strong prediction that we have now been able to confirm by genetic experiments, using thymidine kinase (tk) alleles. tk- mutants induced by ethylmethane sulphonate (ems) were all revertible to tk+ at high frequency by the demethylating agent 5-azacytidine (5-aza-cr). this revertibility was due t ...19901704254
novel antipeptide antibodies to the human glucocorticoid receptor: recognition of multiple receptor forms in vitro and distinct localization of cytoplasmic and nuclear receptors.we have synthesized two peptides that correspond to unique regions of the amino-terminus of the human glucocorticoid receptor (gr). peptides representing amino acids 245-259 and 346-367 (designated 59 and 57, respectively) were chosen on the basis of hydrophobicity/hydrophilicity ratios as well as overall proline content. these peptides were then used as antigens to produce epitope-specific antibodies that recognize and interact with human gr in a variety of physical states. antiserum directed a ...19901704480
endogenous origin of defective retroviruslike particles from a recombinant chinese hamster ovary cell line.the presence of budding c-type and intracytoplasmic a-type particles in chinese hamster ovary (cho) cells is well documented. however, extensive screening has failed to detect any evidence of infectivity. continuous-flow ultracentrifugation has been used to concentrate extracellular particles from culture fluid of a recombinant cho cell subclone for molecular characterization. particles exhibiting reverse transcriptase activity and associated with mammalian c-type retrovirus structural proteins ...19911704658
chromosomal localization of cd1d genes in the mouse.southern blot hybridization of dna from chinese hamster x mouse somatic cell hybrids was used to assign the mouse cd1d genes to chromosome 3. analysis of the progeny of an intersubspecies backcross was used to position these genes near the gene for glucocerebrosidase, gba.19911705364
delineation via site-directed mutagenesis of the carboxyl-terminal region of human choriogonadotropin beta required for subunit assembly and biological activity.the choriogonadotropin beta subunit is unique in the human glycoprotein hormone family in containing a carboxyl-terminal extension, with four sites of o-glycosylation, that is not present in the other beta subunits. we have used site-directed mutagenesis to define boundaries on the extent to which truncations can be made at the cooh terminus without abolishing subunit assembly and biological activity. two cooh-terminal deletion mutant chains of human choriogonadotropin beta, des(93-145) and des( ...19911707877
the possible role of probiotics as dietary antimutagen.possible antimutagenic actions of probiotics--mainly lactic acid bacteria--were examined using in vitro and in vivo test systems. in the ames test with salmonella typhimurium ta1538 beef extract and nitrosated beef extract were used as mutagens. l. casei showed high antimutagenic activity on mutagenicity induced by nitrosated beef extract only without s9 mix, whereas omniflora (a lyophilized preparation of lactobacilli and e. coli) and its cell-free culture broth exhibited antimutagenic action o ...19911708108
constitutive and trophoblast-specific expression of a class of bovine interferon genes.the early conceptus in sheep and cattle secretes a low molecular weight protein called ovine and bovine trophoblast protein 1 (tp-1) that is critical for establishment of pregnancy. tp-1 is a type i interferon (ifn) and is most related to ifn-omega. here we have determined if tp-1 genes are regulated similarly to other type i ifns. single day 18 bovine conceptuses secrete approximately 10(5) units of ifn antiviral activity per hour in culture, amounts approximately 300 times higher than those pr ...19911708888
human monocytes bind to two cytokine-induced adhesive ligands on cultured human endothelial cells: endothelial-leukocyte adhesion molecule-1 and vascular cell adhesion molecule-1.vascular cell adhesion molecule-1 (vcam-1) and endothelial-leukocyte adhesion molecule-1 (elam-1) are adhesive proteins induced on endothelium by cytokines. we examined the contribution of these adhesive proteins to human peripheral blood monocyte adherence to endothelium using transfected chinese hamster ovary (cho) cells stably expressing these proteins and monoclonal antibodies (moabs) to elam-1, vcam-1, or cd49d/cd29 (vla-4), the leukocyte receptor for vcam-1. monocytes bound to cho cells tr ...19911709380
dna sequence, genomic organization, and chromosomal localization of the mouse peripheral myelin protein zero gene: identification of polymorphic alleles.we have cloned and characterized the mouse gene, p0, that encodes the predominant protein of peripheral myelin. similar to the rat gene, the mouse p0 gene is encoded by six exons that span about 7 kb of dna. the dna sequence of the mouse gene is highly homologous with the rat gene, including the regions believed to be important in transcriptional control. furthermore, the p0 protein appears well conserved throughout evolution. the gene was mapped to mouse chromosome 1 by southern analysis of a c ...19911709914
comparison of mutagenicity results for nine compounds evaluated at the hgprt locus in the standard and suspension cho assays.the chinese hamster ovary (cho) assay, which measures newly induced mutations at the hypoxanthine-guanine phosphoribosyltransferase (hgprt) locus, has been widely used for mutagenesis testing. the insensitivity of the standard assay to some genotoxic agents has been speculated to be due to the relatively small number of cells used in the assay. in the present study, we have compared the standard monolayer assay with a suspension adapted cho assay that uses cell numbers comparable to that of the ...19911710014
high affinity human ige receptor (fc epsilon ri). analysis of functional domains of the alpha-subunit with monoclonal antibodies.the binding of ige to the high affinity fc epsilon receptor (fc epsilon ri) on mast cells and basophils is mediated by the alpha-subunit of the tetrameric receptor complex. based on sequence homologies, the 50-kda alpha-subunit is a member of the immunoglobulin superfamily of proteins and has two predicted disulfide-bonded loops. monoclonal antibodies specific for the human alpha-subunit have been identified and separated into two major classes: inhibitory and noninhibitory antibodies. inhibitor ...19911710221
[the effect of recombinant human granulocyte colony-stimulating factor (rg-csf) on childhood neutropenias].the clinical effect of recombinant human granulocyte colony-stimulating factor (rg-csf), produced by chinese hamster ovary cells, was studied in 27 patients with childhood neutropenias. the sample consisted of 8 patients with congenital neutropenia (kostmann type), 9 with neutropenia with miscellaneous causes (5 chronic benign, 2 associated with hypogammaglobulinemia, 1 drug-induced, and 1 hypoplastic type), 3 with cyclic neutropenia, and 7 with severe aplastic anemia. the rg-csf was given subcu ...19911710294
transfected na1 and na2 forms of human neutrophil fc receptor iii exhibit antigenic and structural heterogeneity.human neutrophils express two polymorphic forms (na1 and na2) of fc receptor iii (fcriii), which differ structurally and antigenically. we recently isolated fcriii cdnas from na1na1 and na2na2 homozygotes and determined that they differ only at five nucleotides, predicting four amino acid substitutions. to determine whether the cdnas that we isolated actually encode proteins that differ structurally and that react appropriately with anti-na1 and anti-na2 antibodies, we transfected chinese hamste ...19911710518
molecular biology of type a endogenous retrovirus.intracisternal a particles (iaps) are retrovirus-like structures consistently observable in a variety of mouse tumor cells such as myeloma and hybridoma and in early embryonic cells derived from rodents but nothing is known of their infectivity. mouse iaps contain a gag-like protein, a reverse transcriptase and a polyadenylated rna molecule (iap rna). dna sequences complementary to iap rna (iap genome) are interspersedly present in rodent such as mice, rats, chinese hamsters and syrian hamsters ...19901710682
expression and functional characterization of a soluble form of endothelial-leukocyte adhesion molecule 1.endothelial leukocyte adhesion molecule 1 (elam1) is a leukocyte adhesion molecule induced on human venular endothelium in vitro and in vivo by inflammatory stimuli. a truncated cdna for elam1 has been constructed, stably expressed in chinese hamster ovary cells, and the secreted recombinant soluble form of elam1 (rselam1) purified to homogeneity by immunoaffinity chromatography. rselam1, when immobilized on plastic, is fully functional as an adhesion protein, and selectively binds only cells kn ...19911711067
phospholipid-anchored and transmembrane versions of either decay-accelerating factor or membrane cofactor protein show equal efficiency in protection from complement-mediated cell damage.decay-accelerating factor (daf) is a glycosyl-phosphatidylinositol (gpi)-anchored membrane protein that protects cells from complement-mediated damage by regulation of the c3 convertase. to investigate the role of the gpi anchor in the function of daf, the cdna encoding human daf was expressed by transfection in chinese hamster ovary (cho) cells. testing of these daf transfectants in an antibody plus human complement-mediated cytotoxicity assay demonstrated that daf protects these cells from cyt ...19911711565
amplified gene expression in cd59-transfected chinese hamster ovary cells confers protection against the membrane attack complex of human complement.protection against the pore-forming activity of the human c5b-9 proteins was conferred on a nonprimate cell by transfection with cdna encoding the human complement regulatory protein cd59. cd59 was stably expressed in chinese hamster ovary cells using the pfrsv mammalian expression vector. after cloning and selection, the transfected cells were maintained in media containing various concentrations of methotrexate, which induced surface expression of up to 4.2 x 10(6) molecules of cd59/cell. phos ...19911712784
purification and characterization of human recombinant insulin-like growth factor binding protein 3 expressed in chinese hamster ovary cells.recombinant human insulin-like growth factor binding protein 3 (higfbp-3) stably expressed in chinese hamster ovary cells (cho cells) has been purified to homogeneity from serum-free culture media. the purified protein migrates as a doublet (45/43 kda) upon sds-page. the purified recombinant higfbp-3 is fully active and binds one mole of igf-i per mole of recombinant binding protein. when the transfected cho cells are treated with tunicamycin a single 29 kda higfbp-3 protein is observed. this ex ...19911713450
phosphorylation-regulated cl- channel in cho cells stably expressing the cystic fibrosis gene.a cyclic amp-stimulated chloride conductance appears when the cystic fibrosis gene is expressed in non-epithelial cells by infection with recombinant viruses. cyclic amp-stimulated conductance in this system is mediated by the same ohmic, low-conductance cl- channel as in human secretory epithelia, but control of this channel by phosphorylation has not been directly demonstrated. here we report the appearance of the low-conductance cl- channel in chinese hamster ovary cells after stable transfec ...19911714039
the hypersensitivity of the chinese hamster ovary variant bl-10 to bleomycin killing is due to a lack of glutathione s-transferase-alpha activity.as a means to understand the fundamental mechanisms of bleomycin cell killing, we previously isolated 19 bleomycin-sensitive mutants which represent at least six genetically distinct complementation groups (t.d. stamato, b. peters, p. patil, n. denko, r. weinstein, and a. giaccia. cancer res., 47: 1588-1592, 1987). one class of mutants represented by the cell line bl-10 displays only hypersensitivity to killing by bleomycin in both acute (16 h) and chronic treatments but no sensitivity to killin ...19911714344
electron microscopic identification of the intracellular secretion pathway of human g-csf in a human tumor cell line: a comparative study with a chinese hamster ovary cell line (ia1-7) transfected with human g-csf cdna.using monoclonal antibodies specific for human granulocyte colony-stimulating factor (g-csf), intracellular localization of g-csf in a g-csf-producing human tumor cell line (chu-2) and its ultrastructural characters were described and compared with those of a chinese hamster ovary cell line (ia1-7) transfected with human g-csf cdna. the chu-2 line, which was derived from a poorly differentiated squamous cell carcinoma of the oral cavity, preserved the character of a poorly differentiated squamou ...19911714402
expression and functional characterization of a soluble form of vascular cell adhesion molecule 1.vascular cell adhesion molecule 1 (vcam1) is a leukocyte adhesion molecule induced on human endothelium in vitro and in vivo by inflammatory stimuli. a truncated cdna for vcam1 was constructed, stably expressed in chinese hamster ovary (cho) cells, and the secreted recombinant soluble form of vcam1 (rsvcam1) purified to homogeneity by immunoaffinity chromatography. immobilized rsvcam1 is a functional adhesion protein, and selectively binds only vla4-expressing cells, including human b and t lymp ...19911714725
the new potent immunosuppressant fk-506 reverses multidrug resistance in chinese hamster ovary cells.the macrolide fk-506, produced by streptomyces tsukubaensis, is effective in sensitizing a multidrug resistant strain of chinese hamster ovary cells to the cytotoxic action of vinblastine. fk-506 also promotes adriamycin accumulation into both wild type and resistant cell lines. fk-506 may be a useful drug to enhance the effectiveness of anti-tumour cytotoxic drugs.19911714737
endogenous xenobiotic enzyme levels in mammalian cells.the response of mammalian cell lines to chemicals depends, in part, on the exogenous activation system used for the induction of a biological response. this could be attributed to differences in the expression of enzymes involved in xenobiotic metabolism. we have measured the activities of benzo[a]pyrene hydroxylase, dimethylaminoazobenzene n-demethylase, catalase, superoxide dismutase, peroxidase and glutathione-s-transferase in human lymphoblast tk6, mouse lymphoma l5178y, chinese hamster ovar ...19911715512
phosphorylation of insulin-like growth factor (igf)-binding protein 1 in cell culture and in vivo: effects on affinity for igf-i.the insulin-like growth factors (igf-i and igf-ii) are present in extracellular fluids bound to specific igf-binding proteins (igfbps). we and others have reported varying biologic activity of different preparations of igfbp-1 that appeared to have identical amino acid sequences and molecular sizes. this observation prompted us to determine whether igfbp-1 undergoes posttranslational modifications. immunoprecipitation was used to show that chinese hamster ovary cells (transfected with a human ig ...19911715565
molecular cloning of a human fucosyltransferase gene that determines expression of the lewis x and vim-2 epitopes but not elam-1-dependent cell adhesion.we have used the human lewis blood group fucosyltransferase cdna and cross-hybridization procedures to isolate a human gene that encodes a distinct fucosyltransferase. its dna sequence predicts a type ii transmembrane protein whose sequence is identical to 133 of 231 amino acids at corresponding positions within the catalytic domain of the lewis fucosyltransferase. when expressed by transfection in cultured cell lines, this gene determines expression of a fucosyltransferase capable of efficientl ...19911716630
glycosylated and unglycosylated recombinant-derived human stem cell factors are dimeric and have extensive regular secondary structure.we have recently described the identification, isolation, and characterization of a factor, termed stem cell factor (scf), which acts on primitive hematopoietic progenitors of the marrow. a soluble form of the factor was isolated from the conditioned medium of a rat cell line (zsebo, k. m., wypych, j., mcniece, i. k., lu, h. s., smith, k. a., karkare, s. b., sachdev, r. k., yuschenkoff, v. n., birkett, n. c., williams, l. r., satyagal, v. n., tung, w., bosselman, r. a., mendiaz, e. a., and langl ...19911717457
recombinant human [cys281]insulin-like growth factor-binding protein 2 inhibits both basal and insulin-like growth factor i-stimulated proliferation and collagen synthesis in fetal rat calvariae.it is recognized that insulin-like growth factors (igfs) are bound to specific high-affinity insulin-like growth factor-binding proteins (igfbps). the role of igfbps in bone metabolism is not well established. the effect of recombinant human [cys281]igfbp-2 ([cys281]rhigfbp-2) on bone formation in 21-day-old fetal rat calvariae was investigated. [cys281]rhigfbp-2 was expressed in and purified from conditioned medium of a clonal chinese hamster ovary cell line. igf-i-stimulated cell proliferation ...19911717466
immunological and biological characteristics of recombinant human thyrotropin.analyses of epitopes and biological activity were made on two preparations of recombinant human thyrotropin produced in chinese hamster ovary cells. seven monoclonal antibodies recognizing four epitopes on alpha subunit of htsh (htsh alpha) and three on beta subunit (htsh beta) were used for the analysis. binding activities of the two rhtsh with each antibody were almost identical with that of a pituitary-derived reference htsh, except at one epitope on htsh alpha. their immunoreactivity measure ...19911717604
mutational analysis of the structure and function of the adenine phosphoribosyltransferase enzyme of chinese hamster.we have analyzed the adenine phosphoribosyltransferase (aprt) enzyme from chinese hamster ovary cells through the study of mutants that are able to grow in the presence of the toxic adenine analogue 8-azaadenine. the distribution of the amino acid alterations was analyzed in terms of the binding regions for the purine and phosphoribosylpyrophosphate substrates and a comparison was made with mutants known in human aprt and human, mouse and hamster hypoxanthine-guanine phosphoribosyltransferase. a ...19911717694
gene-specific dna repair in terminally differentiating rat myoblasts.preferential dna repair in expressed genes has been well documented in proliferating mammalian cells following ultraviolet irradiation. it was of interest to learn whether excision repair is similarly selective in terminally differentiating cells. we have measured the removal of ultraviolet-induced cyclobutane pyrimidine dimers (detected as t4 endonuclease v-sensitive sites) from various genes in cultured l8 rat skeletal myoblasts. in these cells, the transcription of muscle-specific genes such ...19911717842
cell kinetic analysis of mixed populations using three-color fluorescence flow cytometry.the development of antibodies to dna-incorporated thymidine analogs has in turn led to the development of flow cytometric techniques for rapidly measuring cell kinetics parameters. more recently, these techniques have been applied to clinical tumor material. one problem with such measurements has been the difficulty of distinguishing malignant cells from coexistent normal cells in the biopsy material. in the present study, the feasibility of selecting out the desired malignant cell population fo ...19911718673
characterization of murine monoclonal antibodies that recognize defined epitopes of pertussis toxin and neutralize its toxic effect on chinese hamster ovary cells.three murine monoclonal antibodies (mab), e19, e205, and e251, raised against pertussis toxin reacted in western blots (immunoblots) with the s1, s4, and s2-s3 subunits, respectively, and neutralized the chinese hamster ovary cell-clustering activity of pertussis toxin. mab e251 recognized a linear synthetic peptide corresponding to amino acids 107 to 120 of the s2 subunit, suggesting a role for this region in receptor binding.19911718872
cloning of a human alpha(1,3)-fucosyltransferase gene that encodes elft but does not confer elam-1 recognition on chinese hamster ovary cell transfectants.in previous studies, chinese hamster ovary (cho) cell genomic dna transfectants that expressed a human alpha(1,3)-fucosyltransferase (alpha(1,3)fuc-t) gene were isolated and shown to possess a common approximately 7.5-kilobase (kb) ecori fragment that hybridized to an alu probe (potvin, b., kumar, r., howard, d. r., and stanley, p. (1990) j. biol. chem. 265, 1615-1622). one of these transfectants was used to make a genomic dna library in lambda zap-ii from ecori-digested, size-selected (6-8 kb) ...19911718983
glycosylation of insulin-like growth factor binding protein-3 (igfbp-3) is not required for potentiation of igf-i action: evidence for processing of cell-bound igfbp-3.insulin-like growth factor binding protein-3 (igfbp-3) is unique among the igf binding proteins in its extensive glycosylation in the native state. to determine the functional significance of carbohydrate moieties on igfbp-3, we examined the effects of nonglycosylated escherichia coli-derived recombinant human igfbp-3 (higfbp-3e. coli) and glycosylated chinese hamster ovary cell-derived higfbp-3 (higfbp-3cho) on igf-i action in cultured bovine fibroblasts. both higfbp-3 preparations bound igf-i ...19911720092
glial fibrillary acidic protein immunoreactivity in adrenocortical and leydig cells of the syrian golden hamster (mesocricetus auratus).in an immunocytochemical investigation of the expression of glial fibrillary acidic protein (gfap) in non-nervous system tissues ten anti-gfap antibodies were used on a range of normal adult organs from different species. all four polyclonal and six monoclonal antibodies revealed the expression of gfap in cells of the zona fasciculata and reticularis of the adrenal cortex and leydig cells of the syrian hamster. the chinese hamster, mole, rat, mouse, guinea pig, rabbit, pig, duck and man were neg ...19911720132
radioimmunoassay of metallothionein in rabbit, rat, mouse, chinese hamster, and human cells.we describe a competitive, solid-phase radioimmunoassay for metallothionein, which employs a rabbit antiserum directed against rat mt-2 to detect metallothionein (mt) from several different species (rabbit, mouse, rat, chinese hamster, and human). the lower limit of detection of the assay for rat mt-2 was 0.7 ng; for rabbit mt-2 it was 2 ng. the method is capable of measuring both isoforms of mt (mt-1 and mt-2). when mt levels in rat and mouse tissues were estimated with this ria and the silver- ...19911720645
human chromosome 19 confers the cd2/e rosette receptor phenotype in interspecific cell hybrids.interspecific cell hybrids between chinese hamster ovary (cho) and phytohaemagglutinin (pha) stimulated human t lymphocytes were purified by preparative rosetting with sheep red blood cells (srbc). the hybrid cell clone used in the present study consisted of cells containing a complete set of the 20 cho chromosomes and one extra human chromosome, no 19. hybrid cells constitutively expressed high levels of human cd2 surface receptor and formed multilayer rosettes with srbc and human erythrocytes. ...19911720937
an adipose tissue-specific beta-adrenergic receptor. molecular cloning and down-regulation in obesity.clones encoding an atypical beta-adrenergic receptor were isolated from a rat brown adipose tissue cdna library. this receptor expressed in chinese hamster ovary (cho) cells displays a low affinity for beta-adrenergic antagonists and a high affinity for brl 37344, an agonist that selectively stimulates lipolysis in adipose tissue. the rank order of potency for agonist-mediated increases in intracellular camp in transfected cells correlates with that for agonist-mediated stimulation of lipolysis ...19911721063
de novo chromosome formation in rodent cells.a hybrid cell line was produced by the fusion of an ec3/7 mouse cell with a chinese hamster ovary cell. the ec3/7 cell carries a dicentric chromosome with a functional marker centromere. this marker centromere contains human, lambda, and bacterial vector dna sequences and a dominant selectable gene (aminoglycoside 3'-phosphotransferase type ii; neo). in the hybrid, the marker centromere separated from the dicentric chromosome and formed a full-sized chromosome (lambda neo). the newly formed chro ...19911722315
expression and differential glycosylation of human sex hormone-binding globulin by mammalian cell lines.the human sex hormone-binding globulin (shbg) gene is responsible for the production of plasma shbg by the liver and androgen-binding protein in the testis. cell-specific glycosylation events during synthesis may account for minor differences in the biochemical properties of shbg and androgen-binding protein, and we have, therefore, expressed a human shbg cdna in chinese hamster ovary (cho) cells and a mouse hepatoma cell line (bw-1), and compared the products to shbg in serum. the shbg produced ...19911723489
growth of chinese hamster ovary (cho) cells in the presence of mmc in low-serum medium.chinese hamster ovary (cho-wblt) cells growing in mccoy's 5a with 10% fetal bovine serum (fbs) were adapted to 0.5% fbs in cho-1 complete media system, a serum-free medium from ventrex. cells in these two media were exposed to 10(-7) m and 10(-8) m mitomycin c (mmc) for 24 h. comparison of cell growth over 10 days showed that cells in 0.5% serum proliferate, though at a slower rate than cells in 10% serum. treatment with mmc revealed that at 10(-7) m, mmc is cytotoxic to cells to both the media; ...19911723496
clinical effect of recombinant human granulocyte colony-stimulating factor (rhg-csf) on various types of neutropenia including cyclic neutropenia.recombinant human granulocyte colony-stimulating factor (rhg-csf) was investigated for its clinical efficacy in the treatment of various types of neutropenia (3 cases with idiopathic neutropenia of suspected drug induction, 5 cases with idiopathic neutropenia of other origin, and 2 cases with cyclic neutropenia). treatment with glycosylated rhg-csf produced in the chinese hamster ovary cells at dose levels of 2-5 micrograms/kg/day caused rapid increases of neutrophil counts associated with an im ...19911723891
characterization of monoclonal antibodies directed against domains of pertussis toxin involved in receptor recognition.the exotoxin pertussis toxin (pt) produced by virulent bordetella pertussis bacteria is regarded as the main virulence factor of the organism and held responsible for most of its pathological effects. identification of functional sites on pt would greatly facilitate site-specific detoxification and thus also the development of a new vaccine. for the investigation of structure-function aspects of pt we have prepared and characterized eleven monoclonal antibodies (mabs) (ub-a1, ub-a2, ub-a10, ub-b ...19911724605
mutation screening of bleomycin-induced v79 chinese hamster hprt mutants using multiplex polymerase chain reaction.we have shown by the filter hybridization technique that bleomycin (blm) induces different types of mutations at the hprt gene locus of v79 chinese hamster cells. dna of mutants identified by southern blots as partial deletions was subjected to further analysis using multiplex polymerase chain reaction (pcr) to localize the endpoints of the deletions over the hprt gene. the pcr analysis revealed that deletions occur in all parts of the hprt gene but are distributed non-randomly. deletions occurr ...19911724791
[the use of a cho cell culture in studying vibrio cholerae grown under different conditions].studies of biological activity of cholera vibrios in cultures of chinese hamster ovary cells (cho) have revealed their strong dependence on culture conditions. elongation of cho cells is caused only by choleragenic strains. under stationary conditions of culture the vibrios were found to release haemolisin into the medium and had a cytotoxic effect. most of cytotoxic supernatants exhibited a neuraminidase activity. proteolytic activity was less dependent on the vibrio culture conditions. strains ...19911726445
thyroid cell lines in research on goitrogenesis.thyroid cell lines have contributed a lot to the understanding of goitrogenesis. the cell lines mostly used in thyroid research are briefly discussed, namely the rat thyroid cell lines frtl and frtl-5, the porcine thyroid cell lines porthos and arthos, the sheep thyroid cell lines ovnis 5h and 6h, the cat thyroid cell lines petcat 1 to 4 and romcat, and the human thyroid cell lines ftc-133 and hth 74. chinese hamster ovary (cho) cells and cos-7 cells, stably transfected with tsh receptor cdna an ...19911726925
escherichia coli reca protein modified with a nuclear location signal binds to chromosomes in living mammalian cells.we tried to make a well-characterized bacterial protein function in mammalian cell nuclei. for this purpose we chose escherichia coli reca protein and fused its carboxy terminus to the nuclear location signal of sv40 large t-antigen by oligonucleotide-dependent modification of the gene. when injected into the cytoplasm, the modified reca protein (t-reca for the t-antigen signal) accumulated efficiently in the nuclei, whereas the wild-type reca protein remained in the cytoplasm. the t-reca protei ...19921727044
interaction of photodynamic treatment and either hyperthermia or ionizing radiation and of ionizing radiation and hyperthermia with respect to cell killing of l929 fibroblasts, chinese hamster ovary cells, and t24 human bladder carcinoma cells.both hyperthermia and photodynamic therapy of cancer are frequently used in combination with other treatment modalities in order to improve tumor control with minimal damage to normal tissues. the present results indicate that the most effective combination of treatment modalities is different in different cell types. for instance, ionizing irradiation and hyperthermia exhibited additivity when applied to l929 fibroblasts, in contrast to the synergistic interaction described before in many other ...19921727371
expression of human o6-methylguanine-dna methyltransferase in a dna excision repair-deficient chinese hamster ovary cell line and its response to certain alkylating agents.a plasmid has been constructed in which the expression of human o6-methylguanine-dna methyltransferase (mgmt) complementary dna is driven by the rous sarcoma virus promoter sequence. we had previously shown that transfection of this plasmid into chinese hamster ovary (cho) cells results in the expression of mgmt and in increased cellular resistance to n-methyl-n'-nitro-n-nitrosoguanidine and 1-(2-chloroethyl)-1-nitrosourea (cnu) but not n-nitroso-n-ethylurea (enu). in the present study, the rous ...19921727384
isolation and characterization of a 1-beta-d-arabinofuranosylcytosine-resistant chinese hamster ovary cell mutant that is also x-ray sensitive and is noncomplementary with ataxia telangiectasia cells.in order to study the mechanism of induction of mutations and chromosome aberrations by ionizing radiations, it is particularly useful to have available radiation-sensitive mutants. while several x-ray-sensitive rodent cell lines are available, they have been selected rather nonspecifically. it was determined that selection for resistance to the dna replication/repair inhibitor, 1-beta-d-arabinofuranosylcytosine (ara-c), would permit production of a set of x-ray-sensitive mutant cell lines that ...19921728406
circulatory half-life but not interaction with the lutropin/chorionic gonadotropin receptor is modulated by sulfation of bovine lutropin oligosaccharides.certain of the glycoprotein hormones, including bovine lutropin (blh), bear asparagine-linked oligosaccharides terminating with the sequence so4-4galnac beta 1-4glcnac beta 1-2man alpha. to establish the biologic significance of these sulfate-bearing oligosaccharides we have compared properties of native blh, desulfated blh, recombinant blh produced in chinese hamster ovary cells that bears asparagine-linked oligosaccharides terminating with sialic acid alpha 2- 3gal beta 1-4glcnac beta 1-2man a ...19921729704
biochemical and biologic properties of rt-pa del (k296-g302), a recombinant human tissue-type plasminogen activator deletion mutant resistant to plasminogen activator inhibitor-1.a mutant of recombinant tissue-type plasminogen activator (rt-pa), obtained by deletion of residues lys296 to gly302 [rt-pa del(k296-g302)], was previously shown to be resistant to inhibition by plasminogen activator inhibitor-1 (pai-1) (madison et al, nature 339:721, 1989). this mutant was obtained by expression of its cdna in chinese hamster ovary cells and purification to homogeneity from conditioned cell culture medium. it was obtained as a single chain molecule with amidolytic activity, spe ...19921730087
max: functional domains and interaction with c-myc.the product of the c-myc proto-oncogene is a dna-binding protein, the deregulated expression of which is associated with a variety of malignant neoplasms. the cdna for the max gene was recently cloned as a result of the ability of its protein product to interact with the c-myc protein. we studied bacterially produced max, c-myc, and a series of truncated c-myc proteins. full-length c-myc alone cannot bind dna. however, a truncated c-myc protein comprising the basic, helix-loop-helix, and leucine ...19921730412
susceptibility of corneas from various animal species to in vitro binding and invasion by acanthamoeba castellanii [corrected].a crucial requirement for establishing corneal infection by the extracellular protozoal parasite, acanthamoeba, is the ability of the parasite to bind to the corneal surface. in a series of in vitro studies, we examined the ability of acanthamoeba castellanii [corrected] to adhere, invade, and damage normal, intact corneas of 11 mammalian and one avian species. a. castellanii [corrected] (80-90% trophozoites and 10-20% cysts) were incubated with corneas for 24 hours in vitro and examined by scan ...19921730531
heat shock induces translocation to the nucleus of the unliganded glucocorticoid receptor.there have been many reports demonstrating the specific association of several heat shock proteins with unliganded steroid hormone receptors. however, little evidence to date has been proposed to link steroid receptor action with the heat shock response in cells. in this paper, we demonstrate the effect of heat and chemical stress on glucocorticoid receptor subcellular localization in mouse l929 cells and in a stably transfected chinese hamster ovary cell line (wcl2) which over-expresses the mou ...19921730584
differential phosphorylation and localization of the transcription factor ubf in vivo in response to serum deprivation. in vitro dephosphorylation of ubf reduces its transactivation properties.we have analyzed the expression, phosphorylation, and localization of the ribosomal dna transcription factors ubf1 and ubf2 in chinese hamster ovary cells in response to serum deprivation. in vivo labeling experiments demonstrate that ubf1 and ubf2 are phosphoproteins. phosphoamino acid analysis of the in vivo labeled proteins demonstrate that ubf is phosphorylated on serine residues. following serum deprivation there is no alteration in the cellular levels of ubf1 and ubf2 as determined by west ...19921730600
a site-directed mutagenesis study of human placental aromatase.aromatase, a cytochrome p-450, catalyzes the formation of aromatic c18 estrogenic steroids from c19 androgens. using the x-ray structure of cytochrome p-450cam as the model, seven mutants of human aromatase were designed and expressed in chinese hamster ovary cells by a stable expression method. they are his-128----gln, his-128----ala, cys-299----ala, glu-302----leu, asp-309----asn, asp-309----ala, and ser-312----cys. the presence of the aromatase mutants in the transfected chinese hamster ovary ...19921730667
human hsp27 is phosphorylated at serines 78 and 82 by heat shock and mitogen-activated kinases that recognize the same amino acid motif as s6 kinase ii.the intracellular concentration of the 27-kda mammalian heat shock protein, hsp27, increases several-fold after heat and other metabolic stresses and is closely associated with the acquisition of thermotolerance. posttranslational modifications may also affect the function of hsp27. heat shock of hela cell cultures, or treatment with arsenite, phorbol ester, or tumor necrosis factor, caused a rapid phosphorylation of preexisting hsp27 and the appearance of three phosphorylated isoforms, hsp27 b, ...19921730670
regulation of globin gene expression in human k562 cells by recombinant activin a.recent studies indicate that a purified protein, activin a, belongs to the transforming growth factor beta (tgf-beta) superfamily. similar to tgf-beta, activin a can have different biologic activities, depending on the target tissues. we used recombinant activin a to demonstrate a possible regulatory role of this protein in modulating human erythroid differentiation in the human erythroid cell line, k562. using genomic probes containing the second exon of alpha, beta, gamma, and epsilon globins, ...19921732015
characterization of monoclonal antibodies to the human thyrotropin receptor.we have produced four monoclonal antibodies (mabs), 34a, 49g, 11e7, and 12e3, which bind the human tsh receptor (htsh-r) when expressed on a human thyroid cell line (gej), freshly dissociated human and murine thyroid cells, or chinese hamster ovary cells stably transfected with the htsh-r gene. these mabs were obtained after immunization of dba/1 mice with affinity-purified tsh-binding sites from gej cells. biochemical studies, including sodium dodecyl sulfate-polyacrylamide-gel electrophoresis, ...19921733738
the human blood fluke schistosoma mansoni synthesizes a novel type of glycosphingolipid.previous studies have shown that the glycoprotein oligosaccharides synthesized by adult schistosoma mansoni, the organism responsible for human schistosomiasis, are unusual in that they contain terminal beta-galnac residues and lack sialic acid. these observations and other studies indicating that schistosome glycoproteins and glycolipids are antigenic in infected animals led us to investigate the structures of the glycosphingolipids synthesized by these organisms and to determine whether they a ...19921733932
the effect of oxidation/reduction on the charge heterogeneity of the human glucocorticoid receptor.in order to investigate the molecular basis for the charge heterogeneity which has been reported for the glucocorticoid receptor, we have analyzed the [3h]dexamethasone mesylate ([3h]dm)1 affinity labeled receptor from hela s3 cells by high resolution two-dimensional gel analysis. the [3h]dm labeled glucocorticoid receptor from hela cells exists as a population of 5-6 isoforms which range over approx. 0.6 pi units but have similar molecular weights. this heterogeneity is apparently the result of ...19921734932
engineering mammalian aspartyl-trna synthetase to probe structural features mediating its association with the multisynthetase complex.aspartyl-trna synthetase from higher eukaryotes is a component of a multienzyme complex comprising nine aminoacyl-trna synthetases. the cdna encoding cytoplasmic rat liver aspartyl-trna synthetase was previously cloned and sequenced. this work reports the identification of structural features responsible for its association within the multisynthetase complex. mutant and chimeric proteins have been expressed in mammalian cells and their structural behavior analyzed. a wild-type rat liver aspartyl ...19921735430
expression, purification and characterization of a mouse-human chimeric antibody and chimeric fab' fragment.b72.3 is a mouse monoclonal antibody against a tumour-associated antigen, tag72, which recognizes breast, ovarian and colorectal tumour tissue. a mouse-human chimeric version of b72.3 has been expressed in chinese-hamster ovary cells. this molecule has the binding specificity of b72.3 and constant regions from human igg4. the chimeric b72.3 assembles to intact igg and recognizes tag72 as well as b72.3 in competitive binding assays. a proportion of the chimeric b72.3 (approx. 10%) does not form i ...19921736881
high and low affinity receptors for human interleukin for da cells/leukemia inhibitory factor on human cells. molecular characterization and cellular distribution.radioiodinated recombinant human interleukin da (hilda)/leukemia inhibitory factor (lif) purified from conditioned medium of chinese hamster ovary transfected cells enabled the identification of specific receptor sites on a variety of human cell types. using low concentrations (up to 500 pm) of the ligand iodinated at a high specific radioactivity, high affinity receptors (equilibrium dissociation constant kd in the range of 30-100 pm) were first demonstrated. they were expressed at low levels b ...19921737777
ornithine delta-aminotransferase mutations in gyrate atrophy. allelic heterogeneity and functional consequences.ornithine delta-aminotransferase is a nuclear-encoded mitochondrial matrix enzyme which catalyzes the reversible interconversion of ornithine and alpha-ketoglutarate to glutamate semialdehyde and glutamate. inherited deficiency of ornithine delta-aminotransferase results in ornithine accumulation and a characteristic chorioretinal degeneration, gyrate atrophy of the choroid and retina. we have surveyed the ornithine delta-aminotransferase genes of gyrate atrophy patients for mutations. using a v ...19921737786
selective inactivation of the arg-gly-asp-ser (rgds) binding site in von willebrand factor by site-directed mutagenesis.in order to assess the requirement for the arg-gly-asp-ser (rgds) consensus adhesion sequence in von willebrand factor (vwf) for vwf binding to platelets and endothelial cells, point mutations were introduced into this sequence by site-directed mutagenesis. a glycine to alanine substitution yielded rads-vwf, while an aspartate to glutamate substitution resulted in rges-vwf. recombinant rads-vwf and rges-vwf, purified from transformed chinese hamster ovary cells, were compared with recombinant wi ...19921737795
human estrogen receptor mutants with altered estrogen and antiestrogen ligand discrimination.a structural characteristic of many antiestrogens (aes) is a bulky side chain with basic or polar functional groups that may interact with charged and polar amino acids near the hormone-binding site in the estrogen receptor. recently, we have identified cys530 as the residue of the human estrogen receptor that is the site of covalent labeling by aziridine analogs of estrogens (es) and aes (harlow, k. w., smith, d. n., katzenellenbogen, j. a., greene, g. l., and katzenellenbogen, b. s. (1989) j. ...19921737796
biotransformation of caffeine and theophylline in mammalian cell lines genetically engineered for expression of single cytochrome p450 isoforms.primary steps in the metabolism of caffeine and theophylline are cleavage of methyl groups and/or hydroxylation at position 8, mediated by cytochromes p450. v79 chinese hamster cells genetically engineered for stable expression of single forms of rat cytochromes p450ia1, p450ia2 and p450iibi and human p450ia2 and rat liver epithelial cells expressing murine p450ia2 were used to overcome problems arising in the proper allocation of metabolic pathways to specific isoforms by conventional technique ...19921739411
primary structure and characterization of the precursor to human pituitary adenylate cyclase activating polypeptide.human cdnas encoding the precursor to pituitary adenylate cyclase activating polypeptide (pacap) were cloned from human testis and cerebral cortex cdna libraries. nucleotide sequencing revealed that cdna from the testis library encoded the entire precursor for pacap, while cdna from the brain library represented only the carboxy-terminal half of the precursor. the predicted human pacap precursor consisted of 176 amino acid residues and was very similar to the ovine one (82%). both human and ovin ...19921739432
point mutational analysis of the hamster dihydrofolate reductase minimum promoter.we have shown previously that 48 base pairs (bp) of 5'-flanking sequence are necessary for correct initiation at the major transcriptional start site of the chinese hamster dihydrofolate reductase (dhfr) gene (ciudad et al., 1988). as an upstream element, this sequence alone confers 25% of maximum promoter activity. the 5' half of this sequence is particularly well conserved among mammalian species; it contains one sp1 binding site (gc box) and one caa element. in the present work, we have analy ...19921740417
the role of the membrane domain in the regulated degradation of 3-hydroxy-3-methylglutaryl coenzyme a reductase.we have constructed a series of mutations in the membrane and linker domains of syrian hamster 3-hydroxy-3-methylglutaryl-(hmg) coa reductase in order to determine the regions critical for the regulated degradation of the enzyme. in transfected chinese hamster ovary cells, we have expressed a fusion protein, hmgal, which consists of the membrane and linker domains of the syrian hamster hmg-coa reductase fused to beta-galactosidase. using this fusion protein, we have determined that a deletion of ...19921740463
soluble cd4-pe40 is cytotoxic for a transfected mammalian cell line stably expressing the envelope protein of human immunodeficiency virus (hiv-1), and cytotoxicity is variably inhibited by the sera of hiv-1-infected patients.sera were obtained from 50 individuals infected with human immunodeficiency virus type 1 or from hiv-1-uninfected individuals before or after vaccination with recombinant gp160. these sera were evaluated for activity antagonistic to the cell-killing activity of the chimeric pseudomonas exotoxin hybrid protein, scd4-pe40. for these studies, chinese hamster ovary (cho) cells were transfected with a chimeric plasmid encoding the tat, rev, and envelope genes of hiv-1 and a cell line was selected for ...19911742081
the effect of apo e secretion on lipoprotein uptake in transfected cells.to investigate the role of apolipoprotein e (apo e) secreted by peripheral tissues in local lipoprotein metabolism, we developed a cell strain that constitutively produced and secreted apo e. a fusion plasmid containing rat apo e genomic dna under control of mouse metallothionein promotor was constructed and transfected into chinese hamster ovary cells. a stable transformant designated cho-maeii constitutively secreted rat apo e mainly in the form of sialylated free protein. the secretion was fu ...19911742315
s9-mediated metabolism of 1-nitropyrene to a mutagen in chinese hamster ovary cells by ring-oxidation under aerobic conditions and by nitroreduction under anaerobic conditions.both nitroreduction and ring-oxidation appear to be important pathways for the in vivo metabolic activation of 1-nitropyrene (1-np), a tumorigenic environmental contaminant. previous studies, however, suggest that ring-oxidation is primarily responsible for the s9-mediated mutagenicity of 1-np in chinese hamster ovary (cho) cells. in this study, an anaerobic rat liver s9 metabolizing system was used to facilitate the nitroreduction of 1-np to a mutagen in repair-proficient cho-k1-bh4 cells and e ...19911747934
cloning and characterization of the gene encoding bovine mitochondrial adenylate kinase isozyme 3.the structure of the gene (ak3) encoding bovine mitochondrial (mt) adenylate kinase isozyme 3 (ak3) has been determined. the gene spans about 46 kb and splits into five exons. the 5'-flanking region of the gene lacks typical transcriptional regulatory elements such as tata and caat boxes. the g + c content of this region is high (71%), and seven gc boxes are recognized. possible sequences responsive to transcription factors, ap-1, ap-2, myf-6 and myod1, are present in this region. in the 5'-flan ...19911748300
the type i and type ii bovine scavenger receptors expressed in chinese hamster ovary cells are trimeric proteins with collagenous triple helical domains comprising noncovalently associated monomers and cys83-disulfide-linked dimers.scavenger receptors have been implicated in the development of atherosclerosis and other macrophage-associated functions. the structures and processing of type i and type ii bovine macrophage scavenger receptors were examined using polyclonal anti-receptor antibodies. pulse/chase metabolic labeling experiments showed that both types of scavenger receptors expressed in chinese hamster ovary (cho) cells behaved as typical cell surface membrane glycoproteins. they were synthesized as endoglycosidas ...19911748671
expression of human glycophorin a in wild type and glycosylation-deficient chinese hamster ovary cells. role of n- and o-linked glycosylation in cell surface expression.glycophorin a, the most abundant sialoglycoprotein on human red blood cells, carries several medically important blood group antigens. to study the role of glycosylation in surface expression and antigenicity of this highly glycosylated protein (1 n-linked and 15 o-linked oligosaccharides), glycophorin a cdna (m-allele) was expressed in chinese hamster ovary (cho) cells. both wild type cho cells and mutant cho cells with well defined glycosylation defects were used. glycophorin a was well expres ...19911748686
restoration by a 35k membrane protein of peroxisome assembly in a peroxisome-deficient mammalian cell mutant.peroxisomes are among the intracellular organelles of eukaryotic cells that contain specialized sets of enzymes with specific functions. little is known of membranous components involved in assembly of the intracellular compartments. we isolated two peroxisome-deficient and mutually complementary, chinese hamster ovary cell mutants, z65 and z24, which closely resembled fibroblasts from patients with autosomal recessive, peroxisome-defective disorders such as zellweger syndrome. these patients sh ...19911750930
mutagenicity studies of kojic acid.kojic acid, a fungal metabolite produced by some species of aspergillus and penicillium, was found to induce sister chromatid exchanges and chromosomal aberrations in chinese hamster ovary cells in the presence or absence of the rat liver s9 mix. furthermore, this compound was demonstrated to induce mutations in salmonella typhimurium strains ta98 and ta100 using both plate-incorporation and preincubation methods.19911755028
inhibition and enhancement of eukaryotic gene expression by potential non-b dna sequences.in a transient or constitutive expression assay we have examined the effect of non-b dna sequences d(ca)40 and d(caaaaatgcc)n on gene expression in eukaryotic cells. these sequences were cloned adjacent to the weak eukaryotic promoter (cgtatttatttg) and located upstream from the coding sequence of galactokinase enzyme. recombinants were micro-injected in cultured cells (chinese hamster fibroblasts r1610, mutant gal-k-) and expression levels have been determined. the alternating purine-pyrimidine ...19911755861
human chromosome-dependent and -independent pathways for hiv-2 trans-activation.human immunodeficiency virus (hiv types 1 and 2) replication is controlled by the interaction of viral-encoded regulatory proteins and host cellular proteins with the viral long terminal repeat (ltr). the presence of hiv-1 and hiv-2 trans-activator proteins, tat1 and tat2, respectively, greatly increases viral gene expression from their homologous ltrs. it is unclear if the cellular factors that support tat1-directed trans-activation of the hiv-1 ltr are the same for tat2 trans-activation of the ...19911760228
mutation of invariant cysteines of mammalian metallothionein alters metal binding capacity, cadmium resistance, and 113cd nmr spectrum.using a yeast expression vector system, we have expressed both wild type and six mutated chinese hamster metallothionein coding sequences in a metal-sensitive yeast strain in which the endogenous metallothionein gene has been deleted. the mutant proteins have single or double cysteine to tyrosine replacements (c13y, c50y, and c13,50y), single cysteine to serine replacements (c13s and c50s), or a single cysteine to alanine replacement (c50a). these proteins function in their yeast host in cadmium ...19911761540
the role of n-glycosylation of glut1 for glucose transport activity.to elucidate a functional role of n-glycosylation in glucose transporters, we introduced oligonucleotide-directed mutagenesis in glut1 cdna to remove the possible site for n-linked glycosylation. the wild-type and the mutated glut1 cdnas which induced a mutation of asn at residue 45 to asp, tyr, or gln were transfected and stably expressed into chinese hamster ovary cells. the expressed wild-type and the mutated glut1 was demonstrated to be a broad band of a 45-60-kda form and a sharp band of a ...19911761560
high-efficiency stable gene transfection using chloroquine-treated chinese hamster ovary cells.we describe a highly efficient stable gene transfection procedure for chinese hamster ovary (cho) cells using a modification of the calcium phosphate-dna coprecipitation method. we have found that treatment of cho cells with chloroquine increases the efficiency of gene transfer by up to 20-fold (from approx. 0.01% to approx. 0.2%) when transfection is done using the psv2-neo plasmid. the optimized transfection procedure requires that cho cells to be incubated with calcium phosphate-dna coprecipi ...19911763389
human parvovirus b19 specific igg, iga, and igm antibodies and dna in serum specimens from persons with erythema infectiosum.to determine the diagnostic use of different markers of acute parvovirus b19 infection, serum specimens obtained from 128 persons with erythema infectiosum were tested for specific immunoglobulin g (igg), iga, and igm antibodies by capture enzyme immunoassay (eia) using chinese hamster ovary (cho) cell-expressed b19 antigen, and tested for circulating b19 dna by polymerase chain reaction (pcr). a significant rise in specific igg and iga antibodies was detected in 87% and 77%, respectively, of pe ...19911765775
evidence for human dna-mediated transfer of the suppressed phenotype into malignant chinese hamster cells.genetic suppression of the neoplastic phenotype has been demonstrated in somatic cell hybrids between tumor and normal cells. suppression in whole-cell and microcell hybrids cannot, as yet, be attributed to specific elements defined at the molecular level. to identify a gene capable of suppressing the neoplastic phenotype, we have introduced dna of normal human cells into tumorigenic chinese hamster wg3-h-o cells. primary and secondary transfectants which exhibit the suppressed phenotype similar ...19911766670
genetic analysis of resistance to total bromodeoxyuridine substitution in mammalian cell hybrids.somatic cell hybrids derived from the fusion of chinese hamster ovary cells (cho) and mutant syrian hamster melanoma cells (2e) were tested for their ability to grow with all of the thymidine (dthd) in their dna replaced with 5-bromo-2'-deoxyuridine (brdu), a phenotypic capability of the 2e cells but not of the cho cells. under these conditions, the 2e cells survived and grew, all of the hybrid clones survived and grew to varying degrees, and the cho cells did not survive at all. when 2e cells w ...19911767335
the gonadotropin-releasing hormone (gnrh) gene maps to mouse chromosome 14 and identifies a homologous region on human chromosome 8.the murine gonadotropin-releasing hormone (gnrh) locus has been mapped to mouse chromosome 14 using a mouse x chinese hamster somatic cell hybrid panel. the equivalent human locus, known as luteinizing hormone-releasing hormone (lhrh), has been previously mapped to 8p21-8p11.2. four other loci mapping to the human chromosome 8 short arm have been mapped to mouse chromosome 8; two of these (plat, gsr) lie proximal to lhrh, and two (lpl, def1) lie distal to lhrh. the localization of gnrh, the muri ...19911767338
indefinite growth of mammalian cell autotrophs on amino acids, vitamins, and glucose.established mammalian cells segregate variants, named autotrophs, able to proliferate in the absence of hormones and proteins of any kind. we provided complete formulas for autotrophic media composed of amino acids, vitamins, glucose, and inorganic salts only and showed that such media are sufficient to sustain continuous propagation of chinese hamster fibroblasts and human keratinocytes. the cells grew on bare polystyrene and divided every 32 to 44 hours reaching approximately 8 x 10(5) cells/c ...19911773442
mouse chromosome-specific markers generated by pcr and their mapping through interspecific backcrosses.we have utilized an oligonucleotide primer from the 3' end of the mouse l1 repeat element for amplification of mouse-specific inter-repeat pcr products from chinese hamster/mouse somatic cell hybrids. pcr of a chinese hamster/mouse somatic cell hybrid (96az2), containing only mouse chromosome 16, produced a range of mouse-specific bands. two of the mouse-specific pcr products, of 250 and 580 bp, have been confirmed as originating from mouse chromosome 16 by somatic cell hybrid analysis. both the ...19911774069
bile salt/acid induction of dna damage in bacterial and mammalian cells: implications for colon cancer.two bile salts, sodium chenodeoxycholate and sodium deoxycholate, induced a dna repair response in the bacterium escherichia coli. similarly, a bile acid and a bile salt, chenodeoxycholic acid and sodium deoxycholate, induced dna repair (indicated by unscheduled dna synthesis) in human foreskin fibroblasts. also, dna repair-deficient chinese hamster ovary (cho) cells were found to be more sensitive than normal cells to killing by bile salts. in particular, mutant uv4 cho cells, defective in dna ...19911775385
role of ring oxidation in the metabolic activation of 1-nitropyrene.nitrated polycyclic aromatic hydrocarbons are wide-spread environmental pollutants that have been detected in photocopier toners, airborne particulates, coal fly ash, and diesel engine exhaust emissions. 1-nitropyrene, a representative nitropolycyclic aromatic hydrocarbon present in diesel particulates, is a mutagen in salmonella typhimurium and a tumorigen in laboratory animals. the activation of 1-nitropyrene to a bacterial mutagen has been attributed to nitroreduction; however, the metabolic ...19911777157
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