Publications

TitleAbstractYear
Filter
PMID(sorted ascending)
Filter
isolation and characterization of an unsaturated fatty acid-requiring mutant of cultured mammalian cells.an unsaturated fatty acid-requiring mutant derived from chinese hamster ovary (cho) cells has been isolated and characterized. this mutant grows normally when oleate or other unsaturated fatty acids are supplemented in the growth medium. unlike the wild-type cho cells, growth stops when medium is deprived of unsaturated fatty acid. whole cell pulse experiments with [14c]acetate or [14c]stearate indicate that the mutant is defective in unsaturated fatty acid synthesis. enzyme assays in vitro show ...19761750
induction of stable protein-deoxyribonucleic acid adducts in chinese hamster cell chromatin by ultraviolet light.ultraviolet (uv)-light-mediated formation of protein-dna adducts in chinese hamster cell chromatin was investigated in an attempt to compare chromatin alterations induced in vitro with those observed in vivo. three independent methods of analysis indicated stable protein-dna associations: (1) a membrane filter assay which retained dna on the filter in the presence of high salt-detergent; (2) a sepharose 4b column assay in which protein eluted cincident with dna; and (3) a cscl density gradient e ...19765110
modified 5'-nucleotides resistant to 5'-nucleotidase: isolation of 3-(3-amino-3-carboxypropyl) uridine 5'-phosphate and n2, n2-dimethylguanosine 5'-phosphate from snake venom hydrolysates of transfer rna.a procedure for the quantitative measurement of the o2'-methylnucleoside constitutents of rna has recently been developed in this laboratory (gray, m.w. can. j. biochem. 53, 735-746 (1975)). this assay method is based on the resistance of o2'-methylnucleoside 5'-phosphates (pnm) (generated by phosphodiesterase hydrolysis of rna) to subsequent dephosphorylation by venom 5'-nucleotidase (ec 3.1.3.5). in the present investigation, two base-modified 5'-nucleotides, each displaying an unusual resista ...19766133
energy metabolism in respiration-deficient and wild type chinese hamster fibroblasts in culture.this paper presents a comparison of energy metabolism in wild type and respiration-deficient chinese hamster cells. from previous work (defrancesco et. al., '75) it was concluded that the mutant satisfies essentially all of its energy requirements from glycolysis and in this study we measure precisely the amount of glucose consumed and lactate produced per milligram increment of protein in exponentially growing cultures. from these measurements we calculate the amount of atp derived from glycoly ...19768468
the production of chinese hamster interferon. 197611678
altered leucyl-transfer rna synthetase from a mammalian cell culture mutant.altered leucyl-trna synthetase from a mammalian cell culture temperature-sensitive mutant, tshl, was compared with enzyme from normal wild type chinese hamster ovary cells. the mutant enzyme had a km for leucine four times larger than that of wild type and enzyme levels 3-10% that of wild type. the presence of trna was necessary during in vitro heating of the mutant enzyme to allow expression of thermolability while the presence of trna protected wild type enzyme against thermal inactivation. th ...197611833
the electrophoretic properties and aggregation of mouse lymphoma cells, chinese-hamster fibroblasts and a somatic-cell hybrid.1. the electrophoretic mobilities of a mouse lymphoma cell, a chinese-hamster fibroblast and a somatic-cell hybrid (also fibroblastic), produced by fusion of the hamster cell and a mouse lymphoma cell, were measured at 25 degrees c over a range of ph, concentration of ca2+ ions and concentration of la3+ ions. 2. all the cells have pi at ph3.5. 3. ca2+ ions decrease the mobilities and zeta potentials of the cells to zero in the range 1-100mm. 4. la3+ ions lower the mobilities and zeta potentials ...197612752
the isolation and characterization of asparagine-requiring mutants of chinese hamster cells. 197714014
purification and properties of dihydrofolate reductase from methotrexate-sensitive and methotrexate-resistant chinese hamster ovary cells.we have previously described methotrexate-resistant chinese hamster ovary cells which appear to contain normal levls of a structurally altered dihydrofolate reductase (ec 1.5.1.3) (flintoff, w.f., davidson, s.v., and siminovitch, l. (1976) somatic cell genet.2,245-261). by selecting for increased resistance form these class i cells, class iii resistant cells were isolated which appeared to possess an increased activity of the altered enzyme. in the report, we describe the purification and severa ...197715711
effect of ph on hyperthermic cell survival.chinese hamster ovary cells incubated with various concentrations of co2, to obtain extracellular ph values in the range of 6.40-7.85, were heated at 45.5c for 5, 10, or 20 minutes. thermal sensitivity increased sharply from ph 7.35 to 6.65 (i.e., survival decreased from 1 x 10(-2) to 3 x 10(-5) for 20 minutes of heating), but remained constant from ph 7.35 to 7.85. the enhanced thermal sensitivity at ph values below pth 7.35 suggested that tumors should be preferentially destroyed by heat relat ...197717014
expression of differentiated functions in hepatoma cell hybrids: ix extinction and reexpression of liver-specific enzymes in rat hepatoma-chinese hamster fibroblast hybrids.most of the hybrid clones derived from a cross of chinese hamster fibroblasts (don) with rat hepatoma cells (faza 967) showed preferential loss of rat chromosomes. two of the hybrid clones retained the rat chromosomes, and both showed extinction of 4 liver-specific enzymes: aldolase b, liver alcohol dehydrogenase, and the inducible enzymes tyrosine aminotransferase and alanine aminotransferase. subcloning of 1 of these hybrids, which contained 2 sets of hepatoma chromosomes and 1 set of hamster ...197517164
folate-dependent enzymes in cultured chinese hamster cells: folypolyglutamate synthetase and its absence in mutants auxotrophic for glycine + adenosine + thymidine. 197718110
regional assignment of seven genes on chromosome 1 of man by use of man-chinese hamster somatic cell hybrids. i. results obtained after hybridization of human cells carrying reciprocal translocations involving chromosome 1.regional localization studies of genes coding for human pgd, pph1, pgm1, ugpp, guk1, pep-c, and fh, which have been assigned to chromosome 1, were performed with man-chinese hamster somatic cell hybrids, informative hybrids that retained fragments of the human chromosome 1 were produced by fusion of hamster cells with human cells carrying reciprocal translocations involving chromosome 1. analysis of the hybrids that retained one of the translocation chromosomes or de novo rearrangements involvin ...197718324
a role for asparaginyl-trna in the regulation of asparagine synthetase in a mammalian cell line.the expression of asparagine synthetase activity [l-aspartate:ammonia ligase (amp-forming), ec 6.3.1.1] in cultured chinese hamster ovary (cho) cells is regulated by asparagine. after transfer of cho cells from an asparagine-supplemented medium to a medium lacking asparagine, activity increases 1.5- to 2-fold. if asparagine is added back to the medium, activity returns to control levels. to test the possible involvement of asn-trnaasn in regulating the levels of asparagine synthetase, we have ex ...197718735
mutagenesis by simian virus 40. ii. changes in substrate affinities in mutant hypoxanthine-guanine phosphoribosyl transferase enzymes at different ph values.a number of 8-azaguanine-resistant clones selected from chinese hamster cells infected with sv 40, and supposed to originate by virus infection was investigated to demonstrate and analyze genetic alterations occurring in the cells after infection. all resistant clones tested showed reduced but detectable activity levels of the enzyme hypoxanthine-guanine phosphoribosyltransferase. the extent of reduction in the activity was not identical for different substrates. in all the clones tested, sponta ...197721348
biochemical genetic analysis of pyrimidine biosynthesis in mammalian cells: i. isolation of a mutant defective in the early steps of de novo pyrimidine synthesis.the isolation and characterization of a new mutant of chinese hamster ovary cells is described. this mutant, urd-a, shows an absolute requirement for exogenously added pyrimidines for growth. complementation analysis indicates that the lesion in this mutant is recessive. revertants can be isolated at frequencies suggesting that it is a single gene alteration. biochemical analysis of cell-free extracts of cho-k1 (urd+) and urd-a revealed that urd-a possesses no more than 10% of wild-type levels o ...197721463
toxicity, radiation sensitivity modification, and metabolic effects of dehydroascorbate and ascorbate in mammalian cells.dehydroascorbate, an electron affinic metabolite of vitamin c, sensitized ehrlich ascites tumor cells, in vivo, to radiation and was selectively toxic to v79 chinese hamster lung cells under hypoxic conditions (without radiation). the radiosensitization may involve both the electron affinic nature of dehydroascorbate as well as its ability to oxidize the intracellular nad(p)h and non-protein sulfhydryl. dehydroascorbate's oxidation of nad(p)h required higher concentrations than other sulfhydryl ...197823385
acid glycohydrolase in chinese hamster with spontaneous diabetes. i. depressed levels of renal alpha-galactosidase and beta-galactosidase.the activites of alpha-and beta-galactosidases (alpha-d-galactoside galactohydrolase, ec 3.2.1.22; beta-d-galactoside galactohydrolase, ec 3.2.1.23) were significantly lower in the kidneys of diabetic xa line than those in the nondiabetic m line chinese hamsters. the depression of these enzymes was found only in the kidney but not in liver, spleen, hind leg muscle, cheek pouch or spinal cord. in young xa animals before onset of glycosuria, renal alpha-galactosidase level was similar to that in a ...199723847
gamma-glutamyltransferase in human diploid fibroblasts and other mammalian cells.gamma-glutamyltransferase was determined in wi-38 human diploid fibroblasts and compared to enzyme levels determined in several other mammalian cell lines including: fibroblast-like cells from human skin, tibia and foreskin; epithelial-like cells from human, bovine and monkey kidney; and transformed cells (chinese hamster ovary, hela s3 and sv-40 transformed wi-38). transformed cells had the lowest activity found followed in increasing order by fibroblasts, human and bovine epithelial cells and ...197827446
interspecies interactions of arboviruses. iii. competition for virus envelope antigens in mixed getah and sindbis virus populations.interactions of getah and sindbis virus populations in mixed infections of 5 tissue systems were competitive or neutral. the type of interaction is regulated by the host cell and virus population density. on reproduction in mouse brains and spev cell cultures the mixed population exhibited antigenic markers of getah virus; in syrian hamster kidney and chick embryo cell cultures those of sindbis virus; and in chinese hamster kidney cell cultures the antigenic markers of both viruses. mixed popula ...197829465
sexually differentiated activity and isozymes of renal beta-galactosidase in the chinese hamster. 197830661
growth of infective forms of trypanosoma (t.) brucei on buffalo lung and chinese hamster lung tissue culture cells.infective cultures of trypanosoma (t.) brucei (strain 427) have been initiated and maintained on chinese hamster lung tissue culture cells and buffalo lung tissue culture cells. by changing daily one-third of the rpmi-1640 plus 20% fetal bovine serum medium, the cell numbers can be maintained at 2--4 x 10(6) cells/ml. the cultured trypanosomes on these two tissue culture cell types were infective to mice and morphologically similar to bloodstream slender trypomastigotes in having a subterminal k ...197831773
response of cells to hyperthermia under acute and chronic hypoxic conditions.the lethal response of chinese hamster cells heated to 42 degrees was determined following 0 to 30 hr culturing under hypoxic conditions. oxygenated and acutely hypoxic cells were equally sensitive to hyperthermia; however, sensitivity increased with the time of culturing under hypoxic conditions prior to treatment. three hr at 42 degrees resulted in a surviving fraction of approximately or equal to 0.1 under acute hypoxic conditions and less than 0.001 for cells cultured for 30 hr under oxygen- ...197934477
naphthol as-bi (7-bromo-3-hydroxy-2-naphtho-o-anisidine) phosphatase and naphthol as-bi beta-d-glucuronidase in chinese hamster ovary cells: biochemical and flow cytometric studies.conditions for the biochemical and flow cytometric assay of 7-bromo-3-hydroxy-2-naphtho-o-anisidine phosphatase and beta-d-glucuronidase activities in chinese hamster ovary cells were studied. in the biochemical assay, the ph optimum for the phosphatase activity was ph 4.6 with a km of 10(-5) m; the ph optimum for beta-d-glucuronidase activity was ph 5.0 with a km of 2 x 10(-5) m. for intact cells the derived constants were 3 to 10 times higher. the rate of hydrolysis of both substrates was also ...197935565
alteration in structure of multifunctional protein from chinese hamster ovary cells defective in pyrimidine biosynthesis.a combined genetic, biochemical, and immunological approach has clarified structural relationships involving the first three enzymes of de novo pyrimidine biosynthesis. a procedure involving antibody and protein a-sepharose was used to isolate the enzymes carbamoyl-phosphate synthase [atp:carbamate phosphotransferase (dephosphorylating, amido-transferring), ec 2.7.2.9], aspartate transcarbamoyltransferase (carbamoylphosphate:l-aspartate carbamoyltransferase, ec 2.1.3.2), and dihydro-orotase (l-5 ...197936610
lysosomal arylsulfatase deficiencies in humans: chromosome assignments for arylsulfatase a and b.genetics of human lysosomal arylsulfatases a and b (aryl-sulfate sulfohydrolase, ec 3.1.6.1), associated with childhood disease, has been studied with human-rodent somatic cell hybrids. deficiency of arylsulfatase a (ars(a)) in humans results in a progressive neurodegenerative disease, metachromatic leukodystrophy. deficiency of arylsulfatase b (ars(b)) is associated with skeletal and growth malformations, termed the maroteaux-lamy syndrome. simultaneous deficiency of both enzymes is associated ...197936611
rapid isolation of metaphase chromosomes containing high molecular weight dna.metaphase chromosomes with high molecular weight dna were isolated from chinese hamster ovary (cho) cells in a neutral buffer containing polyamines and chelators. the individual, unfixed chromosomes retained their centromeric and secondary constrictions, distinct sister chromatids, and complex banding patterns. the dna from these chromosomes was 100-fold larger (2 x 10(8) daltons) than dna from chromosomes isolated by other procedures. these characteristics indicate preservation during isolation ...197939081
biochemical genetic analysis of pyrimidine biosynthesis in mammalian cells: iii. association of carbamyl phosphate synthetase, aspartate transcarbamylase, and dihydroorotase in mutants of cultured chinese hamster cells.carbamyl phosphate synthetase (ec 2.7.2.9), aspartate transcarbamylase (ec 2.1.3.2), and dihydroorotase (ec 3.5.2.3), the first three enzymes in de novo pyrimidine synthesis in chinese hamster ovary cell strain kl (cho-kl), cose diment through a glycerol gradient. when an extract from urd- a, a pyrimidine-requiring auxotroph reduced in all three activities, is run on a glycerol gradient, the enzyme activities appear in two peaks higher in the gradient, a peak of aspartate transcarbamylase separa ...197939353
purification and chemical characterization of the heat-labile enterotoxin produced by enterotoxigenic escherichia coli.heat-labile enterotoxin (lt) produced by a human strain of enterotoxigenic escherichia coli (286c(2)) was purified to homogeneity from ph extracts of fermentor-grown cells by ultrafiltration, (nh(4))(2)so(4) fractionation, hydrophobic chromatography on norleucine-sepharose 4b, hydroxylapatite chromatography, and bio-gel p-150 filtration. purified lt preparations exhibited biological activity comparable to that of cholera toxin in four bioassays specific for the two enterotoxins (y-1 adrenal tumo ...197939893
mechanism of action of yersinia enterocolitica enterotoxin.enterotoxin derived from three clinical isolates of yersinia enterocolitica was compared with the heat-stable enterotoxin of escherichia coli. both toxins were biologically active in infant mice examined at 2 h and in ligated rabbit ileal loops at 6 h. neither substance, however, produced changes in ligated ileal loops at 18 h or in chinese hamster ovary or y1 adrenal tissue cultures. in addition, both y. enterocolitica enterotoxin concentrated approximately 20 times by ammonium sulfate precipit ...197939894
asparaginyl-trna aminoacylation levels and asparagine synthetase expression in cultured chinese hamster ovary cells. 197940971
epidermal growth factor stimulation of dna synthesis is potentiated by compounds that inhibit its clustering in coated pits.we have used inhibitors of receptor-mediated endocytosis to investigate the mechanism and function of epidermal growth factor uptake by cultured cells. when rhodamine-labeled epidermal growth factor is bound to cell surface receptors on confluent monolayers of balb/c 3t3 cells, it rapidly collects in cell surface clusters and is internalized. the clustering of occupied receptors requires ca(2+) and is inhibited by primary alkylamines; both of these properties are shared by the enzyme transglutam ...197942903
isolation and characterization of cho cell mutants with altered asparagine synthetase.two asparagine auxotrophic mutants (n3, n4) were isolated from the gat- strain of chinese hamster ovary cells, using a selection procedure modified from that of goldfarb et al. (1). the defect in these mutants is due to a deficiency in asparagine synthetase activity. n3, in particular, had no measurable enzyme activity. complementation analysis by peg-mediated cell fusion showed that the auxotrophic phenotype behaved as a recessive trait; complementation was obtained between n3 or n4 and the pse ...197943600
comparison of the properties of the alcohol dehydrogenases from wild-type and mutant chinese hamster somatic cells.alcohol dehydrogenases (alcohol: nad oxidoreductase, e.c. 1.1.1.1.) from allyl alcohol-resistant and wild-type chinese hamster cells were purified using gel filtration, ion-exchange, and affinity-column chromatography. both enzymes exhibited the same isozyme band patterns on electrophoresis and isoelectric focusing. physicochemical properties of the two enzymes such as ph and temperature optima, km values, and temperature stability were found to be the same within the experimental errors. the ge ...197944189
studies on recovery from chemically induced damage in mammalian cells.the survival of plateau-phase or nondividing chinese hamster ovary cells (in vitro) is reduced to a greater extent by treatments with nitrosourea compounds than are cells treated in the exponential phase of growth. the greatest decrease in the survival fraction occurred following treatments with 1-trans-(2-chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea where approximately 128 times more cells were killed in plateau phase than in the dividing state (at the 10 mug/ml-for-1-hr dose). only 5 time ...197547265
premature chromosme condensation in the bone marrow of chinese hamster after application of bleomycin in vivo.the chinese hamster bone marrow was used as a test system in vivo to analyse the chromosome-danaging effect of bleomycin. both chromosome and chromatid aberrations were found. mitoses with aberrations (ma) show a linear dose-effect relationship after a recovery time of 24 h, the same hold true for cells with micronuclei (cm) and for mitoses with premature chromosome condensation (pcc). the dose-effect relationships for ma, cm and pcc run parallel to each other with ma at the highest and pcc at t ...197548189
histones in fixed cytological preparations of chinese hamster chromosomes demonstrated by immunofluorescence. 199248202
[dependence of heterochromatin differential staining on the time of its reduplication and the degree of condensation].a comparison of the chromosomes banding pattern after g-and c-staining with the time of dna reduplication and the degree of chromosome condensation, was carried out using chinese hamster metaphase chromosomes. chromosome condensation was studied under 5-bromodeoxyuridine and 5-bromodeoxycytidine treatment. all the chromosomal segments stained with c-technique are also stainable with g-technique, while only some g-positive segments are capable to be c-bands. c-bands are heterochromatic segments c ...197549115
the induction of chromatid deletions in accord with the breakage-and-reunion hypothesis.in the present experiments it has been possible to study large numbers of x-ray induced chromatid deletions, or breads, in chinese hamster chromosomes and to discern whether or not a sister chromatid exchange also occurs at the point of breadage. chromatid deletions are only infrequently associated with a sister chromatid exchange. this is contrary to the expectations derived from the exchange hypothesis of revell. pn the basis of this hypothesis, in which chromatid deletions are considered to b ...197550557
identification of interspecific translocation chromosomes in human-chinese hamster hybrid cells.chromosome material of human and chinese hamster origin can be stained differentially in human-chinese hamster translocation chromosomes by use of the giemsa-11 staining technique.197551825
enhanced cell killing by bleomycin and 43 degrees hyperthermia and the inhibition of recovery from potentially lethal damage.the effect of hyperthermia on bleomycin (bleo) toxicity and repair was studied in "unfed" monolayer cultures of chinese hamster cells. synergy of toxicities was observed with simultaneous exposure to bleo and 43 degrees. for example, when cells were exposed for 1 hr to bleo (40 mug/ml) at 43 degrees, survival was reduced to 4 x 10(-5); separately, hyperthermia and 37 degrees bleo exposure each resulted in a survival of 20%. heating at 43 degrees prior to drug exposure at 37 degrees also produced ...197552401
sister chromatid exchange in human chromosomes from normal individuals and patients with ataxia telangiectasia.a new fluorescence plus giemsa staining technique now makes the detection of sister-chromatid exchange (sce) a relatively easy matter in cells containing 5-brdu-substituted dna. the technique has been applied to human cells to examine the distribution of sce between different people and within different chromosomes. the results show: (1) that there were no large differences in the incidence of sce between blood leukocyte chromosomes from male and female adults and newborn, and that similar frequ ...197552431
cytological detection of mutagen-carcinogen exposure by sister chromatid exchange.a staining technique that detects sister chromatid exchanges (sces) has been used to examine the response of chromosomes in cultured chinese hamster cells to a wide variety of mutagens-carcinogens. the test gives a very sensitive and rapid method for detecting chromosome mutagenicity of chemical agents and provides a powerful new method for detecting environmental mutagens.197552847
repair (or recovery) effects in quiescent chinese hamster cells: an attempt at classification.increased survival of density-inhibited chinese hamster cells after a variety of treatments is analyzed in terms of half-time of "repair," magnitude of repair, and dependence upon nutrient medium during the repair interval. at least three different systems are identified: x-ray-like, uv-like, and an entirely different system after heat shock. repair after methyl methanesulfonate and after visible light (in bromodeoxyuridine-substituted cells) may be interpreted as a superposition of the x-ray an ...197553050
[2-colored fluorescence of differentially condensed chromosomes stained with acridine orange].metaphase chromosomes of the chinese hamster differentially-condensed under the influence of a) 5-bromdeoxyuridine, b) colcemide, and c) cold, were stained with acridine-orange (ao) in concentrations of 1.5 x 10(-7) to 3 x 10(-5) g/ml at ph 4.1 to 8.5. it was found that stretched chromosomal segments fluoresced in the orange/red part of the spectrum, whereas normally condensed ones--were green. the colour distribution along the chromosome depended mainly on the ao concentration and the exposure ...197553076
a high resolution study of the dna replication patterns of chinese hamster chromosomes using sister chromatid differential staining technique.chinese hamster cells were grown for 1+ and 2+ cell cycles in the presence of brdu and then treated by the sister chromatid differential staining technique (scd). those regions of a chromosome which had replicated twice in the presence of brdu were pale staining and by selecting appropriate metaphase cells an accurate reconstruction of the dna synthetic patterns was possible. a direct correlation between the staining intensity of the g bands and the order in which they replicate was found. dark ...197553130
visualization of nucleolar organizer regions im mammalian chromosomes using silver staining.a simple ammoniacal silver staining procedure, designated ag-as, differentially stains the chromosomal locations of ribosomal dna in certain mammalian species. this was critically demonstrated by ag-as staining of the nucleolus organizer regions in karyotypes of the same species and cell lines used for locating the ribosomal cistrons by dna/rna in situ hybridization. with ag-as, silver stained nors (ag-nors) are visualized as black spherical bodies on yellow-brown chromosome arms. ag-nors were v ...197553131
analysis of the replication pattern of chinese hamster chromosomes using 5-bromodeoxyuridine suppression of 33258 hoechst fluorescence.chinese hamster fibroblasts were synchronized and given 5-bromodeoxyuridine for dna synthesis except during one hour of the s phase when thymidine was present in the medium. in the next mitosis, chromosomes stained with 33258 hoechst were banded in appearance when photographed by fluorescence microscopy. the bright regions corresponded to the chromosome segments replicated during the thymidine exposure in the s phase. the segments replicated together during any one hour produced three distinct p ...197553132
enterotoxigenic escherichia coli and idiopathic diarrhoea in bangladesh.faecal escherichia coli from bangalee patients with idiopathic diarrhoea were tested in the chinese hamster ovary cell (c.h.o.) assay to detect production of thermolabile enterotoxin (l.t.). c.h.o-positive e. coli produce both l.t. and a thermostable toxin (s.t.). c.h.o.-positive strains were found in 19.2% of all cases and in 70% of the most severely ill patients with non-vibrio cholera. e. coli which produce s.t. alone were identified in a third of the c.h.o.-negative cases. enterotoxigenic e. ...197553601
uneven extraction of protein in chinese hamster chromosomes during g-staining procedures. 200155363
enterotoxin testing of escherichia coli causing epidemic infantile enteritis in the u.k.three test systems were used to study enterotoxin production by epidemic strains of escherichia coli from cases of infantile enteritis in well-documented outbreaks in the u.k. the tests used were the y1-mouse-adrenal-cell test and the chinese-hamster-ovary-cell (c.h.o.) test for the detection of heat-labile enterotoxin and the infant-mouse test for the detection of heat-stable enterotoxin. all 6 outbreaks had been studied using full serotyping techniques and the results had been published. in ea ...197655904
antisera against electrophoretically purified tubulin stimulate colchicine-binding activity.several rabbit antisera have been prepared against reduced and alkylated, electrophoretically purified tubulin isolated from chick brain. these antisera give a single precipitin line in ouchterlony double diffusion plates when tested against partially purified tubulin, and label specifically microtubule- and tubulin-containing structures, such as mitotic spindles, cilia, and vinblastine-induced crystals, in a variety of cells. the same antisera also display the unique ability to stimulate the co ...197657619
mitochondrial and nuclear glutamate dehydrogenases in chinese hamster ovary cells in culture.nuclear glutamate dehydrogenase (ec 1.4.1.3) activity has been demonstrated in chinese hamster ovary cells. some characteristics of this enzyme have been examined and compared with those of the mitochondrial glutamate dehydrogenase from the same source. differences were detected in the extent of the activation by inorganic phosphate, in the ph versus activity curves, in the affinity of the two enzymes for the cofactor nad+ and in the electrophosretic mobility. a different rate of decay of the tw ...200157807
the significance of dna damage in the cell cycle sensitivity of chinese hamster ovary cells to bleomycin.chinese hamster ovary cells have been treated with bleomycin at various stages in the cell cycle. mitotic cells, which exhibit least survival, show the greatest amount of dna strand breakage and a marked inhibition of dna replication in the subsequent s phase. strand-rejoining experiments suggest that this is primarily due to differences in the amount of damage produced in the dna but does not exclude the possibility that cells at the various cell stages also differ in their ability to repair th ...197658718
cell volume growth after cell cycle block with chemotherapeutic agents.the effects of various chemotherapeutic agents on the volume of chinese hamster v79 fibroblasts and murine lymphoma l5178y cells were studied by electronic volume spectroscopy. cells arrested in the division cycle by a chemotherapeutic block continued to grow in volume resulting in abnormally large cells unable to reduce their volume by cell division. this was observed in cells treated with colcemid, vinblastine, excess thymidine, hydroxyurea, ara-c, 5-fluorouracil, actinomycin-d and bleomycin, ...197658726
streptozotocin and renal amyloidosis in the syrian hamster.in the syrian hamster, administration of the drug streptozotocin was associated with an increased incidence and severity of renal amyloidosis. some of the more severely affected animals showed a frankly nephrotic picture. although some of the diseased animals showed decreased levels of serum albumin, no other definite changes in serum proteins were noted, nor was there any evidence of glomerular immunoglobulin or immune complex deposition. none of the lesions previously found after administratio ...197659551
isolation of mammalian cell mutants deficient in glucose 6-phosphate dehydrogenase by means of a replica-plating technique.a replica-plating technique is described which was used for the isolation of g-6-pd-deficient mutants in cultures of mutagen-treated chinese hamster cells. mutants were recognized by their failure to stain in a histochemical g-6-pd-specific staining reaction. four mutants were isolated and characterized by growth properties, stability of their variant phenotypes, and reduced g-6-pd activity. one of these mutants on electrophoresis exhibited a variant g-6-pd and thus is very likely the result of ...197659685
cell surface antigens. iv. immunological coorespondence between glycophorin and the a1 human cell surface antigen.a stable human-chinese hamster ovary cell hybrid has been produced which, in addition to the complement of chinese hamster ovary (cho-k1) chromosomes, contains only one human chromosome, no. 11. the human cell-surface antigens whose expression is controlled by human chromosome 11, and are expressed by this hybrid, have been defined as the al immunogenetic complex. although one component of this immunogenetic complex (a1) is also expressed by human red blood cells, a second component (a2) is not. ...197661843
effect of hoechst 33258 on chinese hamster chromosomes.cells of the chinese hamster strain c-125 were treated for different time intervals with h 33258, a bibenzimidazole derivative. the same compound was used to stain fixed cells of the same strain. h 33258 induced in cells in culture specific areas of reduced spiralization on the metaphase chromosomes of some cells. these probably correspond to dna segments rich in a-t bases interspersed along the chromosomes. probably h 33258 acts during s period of cell cycle. the banding obtained by staining wi ...197661845
a novel chromosome abnormality in human neuroblastoma and antifolate-resistant chinese hamster cell lives in culture.four cell lines, sk-n-sh, sk-n-mc, sk-n-be(2), and imr-32, established in vitro from tumor tissue of patients with neuroblastoma were analyzed by trypsin-giemsa banding methods. in two of the lines a large, abnormally staining chromosome region was observed. this "homogeneously staining region" (hsr) was considerably longer than any of the bands present in normal human cells and, as revealed by both g- and q-banding, stained with an intermediate intensity. it was located on chromosomes no 6, 10, ...197662055
dotted chromosomes produced in sodium phosphate solution supersaturated with nahco3.dotted chromosomes were consistently produced in both brdu and non-brdu substituted chinese hamster cells after treatment with 1.0 m na-phosphate solution, adjusted to ph 9.0 with a supersaturating amount of nahco3, and at a temperature of 80--95 degrees c. -- a series of changes in chromosome morphology was produced as the temperature of the solution was progressively increased. in brdu-treated cells, g-banding and differentially stained sister chromatids were sequentially produced prior to the ...197663362
ten model mutagens evaluated by the micronucleus test.the following ten mutagenic compounds were subjected to the micronucleus bone marrow test (mnt) in the mouse: cyclophosphamide (ctx), thiotepa (tt), vincristin (vcr), colcemid (colc), adriamycin (am), bleomycin (bm), cytosin arabinoside (ara c), 6-mercaptopurine (6-mp), methotrexate (mtx) and 5-fluorouracil (5-fu). dose-effect curves were established for all compounds. with the exception of ctx, colc and am, the drugs also were subjected to chromosome analyses on chinese hamster fibroblasts in v ...197664925
the expression and relation of hla, beta2-microglobulin and receptor for marmoset red blood cells on man/mouse and man/chinese hamster hybrid cells.the expression of hla, human and mouse beta2-microglobulin (beta2m), p red blood cell antigen and a receptor for marmoset red blood cells (marbc) were studied on 18 man/mouse and man/chinese hamster hybrids. a positive correlation was found between the expression of hla, p, and the receptor for marbc, which we interpret as a possible synteny between these different loci. we studied 3 hybrid clones where hla antigens are still expressed despite the absence of human beta2m and where redistribution ...197766148
studies on sex chromosomes of four hamster species: cricetus cricetus, cricetulus griseus, mesocricetus auratus, and phodopus sungorus.in this paper, we present an analysis of the sex chromosomes of four hamster species after application of different staining techniques. the mitotic x chromosomes show a striking similarity in g-banding pattern but rather great differences in their c-banding patterns. a presumably homologous euchromatic segment that exhibits two distinct g-bands appears in the x chromosome of each species. the y chromosome of cricetus cricetus is in contrast to those of the other species, because it reveals a re ...197767011
neutralization of salmonella toxin-induced elongation of chinese hamster ovary cells by cholera antitoxin.a partially purified preparation of the delayed skin permeability factor from salmonella typhimurium caused chinese hamster ovary cells to elongate. the elongation effect and the skin test activity were blocked by monospecific rabbit antisera against cholera toxin and against the b fragment of cholera toxin,197767084
pretreatment of hamster cells with phenethyl alcohol alters cell surface glycoproteins and inhibits vesicular stomatitis virus growth.chinese hamster ovary cells cultured in the presence of phenethyl alcohol exhibit obvious changes in cell surface galactose and galactosamine glycoproteins as determined by the galactose-oxidase[3h]borohydride technique and sds gel electrophoresis. cells pretreated with phenethyl alcohol (drug was removed before infection) were not as effective as hosts for vesicular stomatitis virus as untreated cultures. a minimum pretreatment time with 0.1% phenethyl alcohol of about 8 h was required before a ...197768807
flow cytometric analysis of bromodeoxyuridine-substituted cells stained with 33258 hoechst.this paper describes a flow-cytometric application of the quenching of fluorescence from 33258 hoechst stained chinese hamster ovary-line cells due to the incorporation of 5-bromo-deoxyuridine (brdu) into the cellular deoxyribonucleic acid. cells were grown for 24 hr in medium containing brdu in concentrations ranging from 1 x 10(-8) to 1 x 10(-4) m. for each concentration we measured the average fluorescence as determined by flow cytometry, the extent of brdu substitution and the effect of the ...197770460
strategies for choosing a deoxyribonucleic acid stain for flow cytometry of metaphase chromosomes.requirements for flow cytometry of metaphase chromosomes stained with three deoxyribonucleic acid (dna)-specific fluorescent dyes--hoechst 33258, chromomycin a3, and ethidium bromide--are reviewed. fluorescence properties of these three stains when bound to mitotic cells or to chromosomes in suspension are measured and compared with fluorescence properties when bound to dna in solution. conditions are given for high resolution flow cytometry of chinese hamster chromosomes stained with each of th ...197770463
the interaction of hoechst 33258 and brdu substituted dna in the formation of sister chromatid exchanges.sister chromatid exchanges (sces) are induced in cultured chinese hamster cells by treatment with 5-bromodeoxyuridine (brdu) or with hoechst 33258 (h33258) plus brdu. the sce frequencies depend upon the number of h33258 molecules available per cell (or per base pair) and the number of brdu molecules available per cell, and not solely upon molarity. in addition, h33258 and brdu act synergistically to induce sces. at low brdu concentrations h 33258 induces very few sces. at high brdu concentration ...197771978
effect of distamycin a on chinese hamster chromosomes. 197771997
[occurrence of pseudoisocyanine-positive endocrine cells in the midgut of the hamster (cricelulus griseus) (author's transl)].pseudoisocyanine-reacting cells could be identified in the intestinal glands of the upper duodenum of the hamster (cricetulus griseus). these cells contain numerous granules as carrier substances of the colouring pigments. presumable these cells are insulin-producing cells.197772477
differential giemsa staining of sister chromatids after extraction with acids.chromosomes of chinese hamster strain cells were air-dried on slides after brdu substitution for two or three rounds of replication. the preparations were treated with 20% pca at 55 degrees c for 20-30 min, or 5n hcl at 55 degrees c for 15-20 min. after staining with giemsa, unifilarly brdu-substituted chromatids stained faintly and bifilarly substituted chromatids stained darkly. such a pattern of sister chromatid differential staining was confirmed by the examination of metaphase cells grown w ...197772637
identification of a chromosome that controls malignancy in chinese hamster cells.a chromosome that controls malignancy in chinese hamster cells has been identified by analysis of the giemsa banding pattern of a malignant cell line transformed by simian virus 40 (sv40), non-malignant revertants from this line, segregants from the revertants that were again malignant and a cell line transformed by methylcholanthrene. the malignant cell line transformed by sv40 was near diploid and had gained additional material of chromosome 3. revertants with a suppression of malignancy and m ...197773545
further studies on hybrid cell-surface antigens associated with human chromosome 11.a new human immunogenetic cell-surface activity associated with human chromosome 11 in the al human-chinese hamster ovary cell hybrid is described. like a1, but not a2, it is present on the human erythrocyte. by mutagenesis and selection, specific, stable, variants of the al hybrid have been prepared exhibiting various combinations of a1, a2, a3, and lactic dehydrogenase a activities. the antigens of the al system can be demonstrated by the horseradish peroxidase system which offers a promising ...197774861
purine mutants of mammalian cell lines: iii. control of purine biosynthesis in adenine phosphoribosyl transferase mutants of cho cells.spontaneous and mutagen-induced 2,6-diaminopurine-resistant mutants of chinese hamster ovary (cho-k1) cells were isolated. such mutants fell into two classes: spontaneous and ethylmethane-sulfonate-induced mutants had approximately 5% wild-type adenine phosphoribosyl transferase (aprt) activity, whereas icr-170g-induced mutants had barely detectable aprt activity. since it has been reported that human hypoxanthine-guanine phosphoribosyl transferase (hgprt) (lesch-nyhan syndrome) and aprt mutants ...197775575
mutations affecting the antigenic properties of hypoxanthine-guanine phosphoribosyl transferase in cultured chinese hamster cells.cells of the mutant chinese hamster strain rjk10 do not contain either hypoxanthine-guanine phosphoribosyl transferase activity (hgprt) or protein that cross-reacts immunologically with hgprt. hgprt+ revertants have been isolated from rjk10 and those strains produce hgprt with altered antigenic properties. hgprt from the revertant cells is less reactive with anti-hgprt serum than enzyme from the wild-type cells, and enzymes from the two sources are immunoprecipitated independently from mixtures ...197775576
studies with bleomycin and misonidazole on aerated and hypoxic cells.bleomycin is a chemotherapuetic drug used primarily in the treatment of squamous-cell carcinoma, while misonidazole is an effective radiosensitizer and potent cytotoxic agent selectively affecting hypoxic cells. v79 chinese hamster cells were used to investigate the cytotoxicity of bleomycin (blm) under aerated and hypoxic conditions as a function of drug concentration. at a lowered temperature of 17.5 degrees c, or at an elevated temperature of 42.5 degrees c, hypoxic cells are more sensitive t ...197875740
[modified method of differential staining of sister chromatids].a modified method of obtaining differential staining of sister chromatids is described. it is simple, rapid, and effective, and at the same time inexpensive and accessible, since it allows one to use available reagents. when 5-bromdeoxyuridine was administered 24 hours before fixation into the chinese hamster cell culture the percentage of metaphases with a differential chromatid staining constituted 95--98, and when this substance was administered 28 hours before fixation into the human lymphoc ...197875748
the effect of bleomycin and its combined effect with radiation on cultured chinese hamster cells v-79. 197875797
potential genetic risks from stationary magnetic field.cytogenetic analysis of dede cell lines (chinese hamster) was used to study the mutagenic effect of stationary magnetic field (smf) and the combined effect of smf and tepa. cytogenetic analysis showed a moderate mutagenic effect after exposure to smf. in combination with tepa, only the additive effect of the two mutagens was observed.197776658
characterization of virus-like particles released from the hamster cell line cho-k1 after treatment with 5-bromodeoxyuridine.simple biochemical measurements have been shown to seriously overestimate the production of c-type particles by chinese hamster ovary (cho) cells treated with 5-bromodeoxyuridine. first, most particle-bound dna polymerase activity released by induced cells was associated with particles which had a different density from c-type particles. second, when labelled with radioactive uridine, induced cho cells released small amounts of particle-bound radioactivity. most of the radioactivity, however, wa ...197877893
differential control of synergistic effect with polyene macrolide antibiotics upon chinese hamster cells in vitro.an amphotericin b-resistant cell (ambr-1), which was isolated from aneuploid chinese hamster cells (v79), was found to show much higher resistance than the parent v79 cells to other polyene antibiotics, such as pentamycin and filipin. to obtain the 50 to 60% inhibition of the control protein synthesis activity by a synergistic combination of fusidic acid and amphotericin b, 50 microgram fusidic acid per ml were combined with 10 microgram amphotericin b in v79 cells, whereas in ambr cells 50 micr ...197882481
a new immunochemical method for the quantitative measurement of specific gene products in man-rodent somatic cell hybrids.an immunochemical method has been developed for the quantitative determination of species-specific gene products, for instance alpha-galactosidase and n-acetyl-alpha-galactosaminidase, in man-rodent hybrid cells and in the parental cell lines. antisera raised against the purified enzymes are covalently coupled to sepharose 4b. the gene products are specifically removed from a cell lysate by incubating with the appropriate sepharose-coupled antiserum. after centrifugation followed by washing of t ...197883282
molecular mechanisms involved in the production of chromosomal aberrations. i. utilization of neurospora endonuclease for the study of aberration production in g2 stage of the cell cycle.chinese hamster ovary cells (cho) were x-irradiated in g2 stage of the cell cycle and immediately treated, in the presence of inactivated sendai virus, with neurospora endonuclease (e.c. 3.1.4.), an enzyme which is specific for cleaving single-stranded dna. with this treatment, the frequencies of all types of chromosome aberrations increased when compared to x-irradiated controls. these results are interpreted as due to the conversion of some of the x-ray induced single-stranded dna breaks into ...197883535
calcium, asparagine and camp are required for ornithine decarboxylase activation in intact chinese hamster ovary cells. 197883867
informosomal and polysomal messenger rna. differential kinetics of polyadenylation and nucleocytoplasmic transport in chinese hamster ovary cells.the relative kinetics of cytoplasmic appearance and polyadenylation were determined for informosomal (ribosome-free) and polysomal (ribosome-associated) mrnas of cultured chinese hamster cells. label appeared in polysomal mrna 17--20 min and into informosomal mrna 2--5 min after addition of radio-labelled uridine. adenosine appeared in polysomal mrna 4--5 min before uridine. in contrast, adenosine label preceded uridine into informosomal mrna by less than 1 min. about one-third of newly formed i ...199983877
induction of high frequencies of endoreduplication in mammalian cell cultures with 33258 hoechst and rubidazone.cells of the mouse l strain and the chinese hamster cho line were treated with 33258 hoechst, rubidazone, and a combination of these. recovering cell populations following the drug removal exhibited a high frequency (20--50%) of metaphases with diplochromosomes (endoreduplication), especially in the combination treatment series (up to more than 70% in the l strain). such a procedure should be useful in probing the mechanisms of the endoreduplication process.197983930
fibroblast interferon in man is coded by two loci on separate chromosomes.we have examined viral and poly(rl):poly(rc) induction of interferon synthesis in several human, mouse and chinese hamster cell lines, and in hybrids derived from the fusion of such cells. we observed species and cell-type differences in inducer effectiveness and in the kinetics of interferon production. in some cases, parental characteristics are preserved in somatic cell hybrids, and in other cases, the expression of the donor phenotype is modulated by the epigenetic state of the recipient cel ...197984714
fluorescence polarization and pulse width analysis of chromosomes by a flow system.isolated chinese hamster chromosomes have been analyzed using a multiparameter computer-controlled cell sorter to obtain information about unique properties of individual chromosomes. parameters other than dna content were sought that would further aid in distinguishing among chromosomes. the polarized emission of the dna-specific bis-benzimidazole dye hoechst 33342 was measured for each class of chromosomes identified by a distinct peak, i.e., differeing in dna content. the emission anisotropy ...200086570
interactions between pairs of dna-specific fluorescent stains bound to mammalian cells.the interactions between dna-specific fluorescence stains complexed with mitotic chinese hamster cells were studied by spectrofluorometric and flow fluorometric techniques. the degree of binding interactions and of energy transfer between stains was determined from the intensities and shapes of fluorescence emission spectra of cells complexed with pairs of stains. the stain pairs hoechst 33258-chromomycin a3, hoechst 33258-ethidium bromide, and chromomycin a3-ethidium bromide exhibited efficient ...200086583
structure, function, and antigenicity of cholera toxin.chemical modification of intact cholera toxin or its b subunit by either partial nitration or reduction and alkylation did not result in significant loss of biological activity as determined by measurement of cyclic amp in chinese hamster ovary cells. complete nitration or succinylation in the presence of guanidine hydrochloride resulted in complete loss of biological activity and significantly affected the immunoreactivity of the toxin and b subunit. compositional analyses of both the isolated ...200188548
pattern of condensation of mouse and chinese hamster chromosomes in g2 and mitosis of 33258-hoechst-treated cells. 197989960
the relation between chemically induced sister-chromatid exchanges and chromatid breakage.studies of classical chromosome aberrations and sister-chromatid exchanges (sces) suggest independent mechanisms for the two events despite some common features. examination of chromosome breakage caused by x-rays, visible light, and viruses has shown that few chromatid breaks are accompanied by sces at the sites of breaks. no similar observations were available for chemically induced breaks, but it has been reported that rat chromosomes exposed to dimethylbenzanthracene (dmba) contained a prepo ...197990339
hyperthermic enhancement of chromosome damage and lack of effect on sister-chromatid exchanges induced by bleomycin in chinese hamster cells in vitro.chinese hamster cells, m-3, were treated with blm (1--4 micrograms/ml) for 30 min to 1 h at 37 degrees or 43 degrees c. after treatment, the cells were reincubated at 37 degrees until recovery. the material treated at 43 degrees showed increased damage expressed as chromosome and chromatid-type breaks and exchanges. since the amount of blm entering the cell at 37 degrees is supposedly similar to that which enters the cell at 43 degrees, the enhanced damage is the result of true synergism, and no ...200190340
[use of 5-bromodeoxyuridine for determining the duration of cell cycle phases].the method of differential staining of sister chromatids by means of 5-bromdesoxyuridine (bdu) was used to determine duration of the cellular cycle and its phases in a cell culture of chinese hamster. the mitotic cycle lasted for 16 hrs, g1 for 5 hrs, s for 8 hrs and g2 for 3 hrs. these values do not differ from those obtained by the autoradiography. the given method permits quicker determination of the cellular cycle phases duration as compared with the autoradiography method.200190414
regulation of endogenous virus production by bromodeoxyuridine and dibutyryl cyclic amp in chinese hamster ovary cells.either dibutyryl cyclic amp or bromodeoxyuridine can enhance rna type-c virus production in chinese hamster ovary cells. the resultant effect of simultaneous treatment of cells with 1 mm cyclic amp and 65 mum bromodeoxyuridine is greater than their additive effects when used separately. the increase in virus production does not seem to involve viral gene amplification, but correlates with an increase in viral rna transcription. the virus is also shown immunologically to be unique to the chinese ...197990523
mutagenicity and cytotoxicity of nineteen heterocyclic mustards (icr compounds) in cultured mammalian cells.the mutagenicity and cytotoxicity of 19 icr compounds, including 6 reported previously, have been determined in the chinese hamster ovary/hypoxanthine-guanine phosphoribosyltransferase system. as with other physical and chemical agents, icr 170 and 191 exhibit a phenotypic expression time of 7 to 9 days, independent of concentrations tested. thirteen of these compounds are mutagenic. at equimolar concentrations, the compounds with the tertiary amine-type side chain (icr 217, 340, 355, 368, 170, ...199991429
control of permeation of bleomycin a2 by polyene antibiotics in cultured chinese hamster cells.control of permeation of bleomycin a2, a well-known antitumor antibiotic, in combination with various polyene macrolide antibiotics was analyzed in cultured chinese hamster cells in vitro. three polyene antibiotics, filipin, pentamycin, and pimaricin, were found to enhance the action of bleomycin a2 remarkably, while amphotericin b or nystatin could not. although dna synthesis and colony-forming activity of polyene-sensitive chinese hamster v79 cells were synergistically inhibited by the combina ...199991431
in vivo method for sister chromatid exchanges in chinese hamster foetal and bone marrow cells. 197991592
sister chromatid differential staining by direct staining in na2hpo4-giemsa solution and the mechanism involved.the direct staining of brdu-substituted chinese hamster chromosomes in a na2hpo4-giemsa solution without any pretreatments resulted in a b-dark type scd istituted (tb) chromatids stained light. detailed examinations of the staining process suggested that the na2hpo4 solution acts to collapse chromosomes whereas the giemsa dye works to reconstruct the collapsed chromosomes, and that during the reconstruction process preferential binding of the giemsa dye to the bb-chromatids occurs to produce the ...200193041
Displaying items 1 - 100 of 26566