Publications
| Title | Abstract | Year(sorted descending) Filter | PMID Filter |
|---|
| autoradiographic detection of animal cell membrane mutants altered in phosphatidylcholine synthesis. | we have screened approximately 20,000 colonies of chinese hamster ovary cells immobilized on filter paper [esko, j.d. & raetz, c.r.h. (1978) proc natl. acad. sci. usa 75, 1190-1193] for strains unable to incorporate [methyl-14c]-choline into trichloroacetic acid-precipitable phospholipid at 40 degrees c. mutant 58, identified in this way, was specifically defective in choline incorporation, and other isolates were also blocked in thymidine and leucine incorporation into dna and protein, respecti ... | 1980 | 6254065 |
| redistribution of myosin during morphological reversion of chinese hamster ovary cells induced by db-camp. | 1980 | 6253306 | |
| studies on temperature-sensitive mutants of chinese hamster ovary cells affected in dna synthesis. | dna synthesis in two mutants of chinese hamster overy cells, ts 13a and ts 15c, which were temperature sensitive for growth, was found to be shut off rapidly at the nonpermissive temperature. the mutants did not complement each other and the ts lesion was not located on the x chromosome. both isolates were found to be considerably more sensitive to the alkylating agents, ethylmethanesulfonate (ems) and methylmethanesulfonate (mms), as compared to the parental cells, but showed normal sensitivity ... | 1980 | 6159689 |
| addition of poly(a) to nuclear rna occurs soon after rna synthesis. | a kinetic analysis of the appearance of [3h]uridine label in rna sequences that neighbor poly(a), as well as the incorporation of [3h]adenosine label into both the rna chain and the poly(a) of poly(a)-containing molecules, shows that poly(a) is added within a minute or so after rna chain synthesis in chinese hamster ovary cells and hela cells. previous conclusions by several groups (5-7) that poly(a) might be added as long as 20-30 min after rna synthesis appear to be in error, and the present c ... | 1980 | 6157696 |
| regulation of cytosolic acetoacetyl coenzyme a thiolase, 3-hydroxy-3-methylglutaryl coenzyme a synthase, 3-hydroxy-3-methylglutaryl coenzyme a reductase, and mevalonate kinase by low density lipoprotein and by 25-hydroxycholesterol in chinese hamster ovary cells. | 1980 | 6105157 | |
| the influence of the wavelength of ultraviolet radiation on survival, mutation induction and dna repair in irradiated chinese hamster cells. | 1980 | 7453709 | |
| x-ray induced activity of n-ethylmaleimide-sensitive dna polymerase in chinese hamster cells. | chinese hamster ddn cells have been exposed to low doses of x-irradiation (< 15 gy). these doses have been shown to induce significant levels of repair replication. levels of activity of dna polymerase were subsequently measured in cells exposed in g1 phase of mitosis to 7.5 gy of x-rays. following exposure, the activity of this enzyme was observed to rise to a peak within 15 min post-irradiation, then decline and then rise again over a long period. the initial rise at least was found to be sens ... | 1980 | 7447787 |
| inhibition and recovery of dna synthesis in uv-irradiated chinese hamster v-79 cells. | 1980 | 7433527 | |
| isobologram analysis of the combined effects of anti-tumour platinum complexes and ionizing radiation on mammalian cells. | chinese hamster ovary cells have been treated in vitro with the platinum coordination complexes cis-pad or chip and with radiation, either alone or in combination with different doses and time intervals. the isobologram method has been used to make a graphic comparison of these combined-modality data in terms of additivity and enhancement. the data showed enhancement of the radiation effect by these platinum complexes in many combinations, and a truly synergistic effect in one case. this method ... | 1980 | 7426336 |
| glycerolization of chinese hamster ovary cells in monolayer culture. | 1980 | 7398361 | |
| mutagenicity and cytotoxicity of various nitrosoureas in v-79 chinese hamster cells. | 1980 | 7388820 | |
| experiments on the effect of the medium in mutation tests with the hgprt system in cultured mammalian cells. | higher mutation frequencies were observed on 8ag than on 6tg medium when hgprt-deficient mutants were being selected in v79 chinese hamster cells. 2 alternative explanations for the effect of the medium were considered, namely (1), that mechanisms are present that cause resistance to 8ag only, in addition to that (or those) causing resistance to both drugs, and (2), that mutants with low hgprt content survive on 8ag but not on 6tg medium, owing to lower affinity of 8ag for the enzyme. the second ... | 1980 | 7192797 |
| mutagenic activity of 3 diazoacetylglycine derivatives on v79 chinese hamster cells. | 3 diazoacetylglycine derivatives, diazoacetylglycine amide (dga), diazoacetylglycine ethyl ester (dge) and diazoacetylglycine hydrazide (dgh), known as antitumour agents, and shown to be mutagenic in bacteria, were studied for their mutagenic activity in the hgprt system of v79 chinese hamster cells in culture (v79/hgprt system). all 3 drugs were highly effective in inducing 6-thioguanine-resistant mutants at concentrations that were not significantly cytotoxic. | 1980 | 6777694 |
| mutation of chinese hamster cells by near-uv activation of promutagens. | a tissue-culture assay for mutagenesis and cytotoxicity incorporating near ultraviolet (nuv) light activation of polyaromatic hydrocarbons (pah) has been developed. cultures of chinese hamster cells (line cho) growing in suspension culture were inoculated with benzo[a]pyrene (b[a]p), 7,12-dimethylbenzanthracene (dmba) of shale-oil retort-water and exposed to light from a high-pressure mercury lamp fitted with a corning nuv bandpass filter. this light source both permitted activation of pah and t ... | 1980 | 6777686 |
| repetitive dna sequences in methotrexate- and methasquin-sensitive and -resistant chinese hamster cell lines. | dna purified from a chinese hamster cell line of lung fibroblast origin (dc83f) was analyzed by density gradient centrifugation and by gel electrophoresis after restriction endonuclease digestion in order to fractionate discrete repetitive fractions within the total dna. no obvious satellite dnas were resolved using the cscl or ag-cs2so4 density gradient conditions described herein. however, analysis of the digestion products of a battery of restriction endonucleases indicated that three of thes ... | 1980 | 6258555 |
| diethyldithiocarbamate, a superoxide dismutase inhibitor, decreases the radioresistance of chinese hamster cells. | 1980 | 6250186 | |
| regulation of ornithine decarboxylase activity by amino acids, cyclic amp and luteinizing hormone in cultured mammalian cells. | any one of five amino acis (alanine, asparagine, glutamine, glycine, and serine) is an essential requirement for the induction of ornithine decarboxylase (ec 4.1.1.17) in cultured chinese hamster ovary (cho) cells maintained with a salts/glucose, medium. each of these amino acids induced a striking activation of ornithine decarboxylase in the presence of dibutyryl cyclic amp and luteinizing hormone. the effect of the other amino acids was considerably less or negligible. the active amino acids a ... | 1980 | 6249374 |
| antifolate-resistant chinese hamster cells. evidence for dihydrofolate reductase gene amplification among independently derived sublines overproducing different dihydrofolate reductases. | purification of a cdna probe specific for dihydrofolate reductase mrna has allowed the relative quantification of dihydrofolate reductase gene numbers and mrna levels between a line of chinese hamster lung fibroblasts sensitive to the antifolate drugs methotrexate and methasquin and sublines which by virtue of their overproduction of the target enzyme dihydrofolate reductase are cross-resistant to these site-specific inhibitors. previous results have shown that resistant sublines could overprodu ... | 1980 | 7391066 |
| isolation of a domain of the plasma membrane in chinese hamster ovary cells which contains iodinatable, acidic glycoproteins of high molecular weight. | a light vesicle fraction, apparently derived from the plasma membrane, was obtained following breakage of chinese hamster ovary (cho) cells by means of a fluid pump disrupting device. the final preparation was enriched approx. 40-fold over the homogenate in k+,na+-stimulated atpase and phosphodiesterase i, but only approx. 10-fold in 125i specific radioactivity after lactoperoxidase-catalyzed iodination. this preparation was compared with another plasma membrane fraction purified as large sheets ... | 1980 | 6156700 |
| regulation of transglutaminase activity in chinese hamster ovary cells. | we have investigated the regulation of transglutaminase activity (epsilon-(gamma-glutamyl)lysine crosslinking enzyme) in chinese hamster ovary cells in culture. we report that transglutaminase activity increases several-fold in cho cells at maximum density in suspension culture. this increase cannot be explained by the presence of soluble regulators of the enzyme activity or the appearance of a new enzyme activity with a different affinity for substrate, but appears to be due to an increase in t ... | 1980 | 6104988 |
| role of aminoacylation of histidyl-trna in the regulation of protein degradation in chinese hamster ovary cells. | 1980 | 7391021 | |
| biochemical and genetic evidence for a new class of emetine-resistant chinese hamster cells with alterations in the protein biosynthetic machinery. | we have isolated a number of emetine-resistant mutants from several different clones of cho and chl cells. protein synthesis in extracts derived from each of the mutants is much more resistant to emetine than in the parental, emetine-sensitive cell lines, indicating the lesions affect the protein synthetic machinery directly. however, hybrid cell lines, derived from fusing either of two different emetine-resistant cho mutants with either one of two different emetine-resistant chl cells, are much ... | 1980 | 7444715 |
| simultaneous detection of chromosomal aberrations and sister-chromatid exchanges: experience with dna intercalating agents. | micronuclei that arise from chromosomal fragments can be used as an index of cytogenetic damage in a number of mammalian cell-culture systems. since sister-chromatid exchanges (sce) can be scored at the second metaphase after treatment, micronuclei that have arisen from acentric fragments at the first mitosis should be present in the same preparations. when a series of 8 mutagens, most of them intercalating agents, was studied in chinese hamster ovary (cho) cells, increased frequencies of micron ... | 1980 | 7432360 |
| the application of particle size analysis to the aggregation of chinese hamster cells by concanavalin a. | 1980 | 7408985 | |
| relationship between dna adduct formation and sister chromatid exchange induction by [3h]8-methoxypsoralen in chinese hamster ovary cells. | 1980 | 7408979 | |
| effects of heat shock on nuclear and nucleolar protein phosphorylation in chinese hamster ovary cells. | distribution and 32p labeling of nuclear and nucleolar phosphoproteins were studied in chinese hamster ovary cells incubated at supranormal temperature (1 h at 43 degrees c). the heat shock induced the phosphorylation of a nucleolar protein with a molecular weight of 95,000. similarly, in the non-nucleolar fraction of the nucleus, phosphorylation of a 54,000-mr protein was induced while a protein with a molecular weight of 35,000 was rapidly dephosphorylated. except for these definite changes, t ... | 1980 | 7408858 |
| the effects of x rays on dna synthesis in synchronized chinese hamster ovary cells. | 1980 | 7406968 | |
| effect of oxygen-radiosensitizer mixtures on the radiation response of chinese hamster cells, line v-79-753b, in vitro. ii. determination of the initial yield of single-strand breaks in the cellular dna using a rapid lysis technique. | 1980 | 7394167 | |
| x-ray induction of 8-azaguanine-resistant mutants in synchronous chinese hamster ovary cells. | 1980 | 7394161 | |
| effects of a tumor promoter and an anti-promoter on spontaneous and uv-induced 6-thioguanine-resistant mutations and sister-chromatid exchanges in v79 chinese hamster cells. | the effects of a tumor promoter 12-o-tetradecanoylphorbol-13-acetate (tpa) and/or an anti-promoter antipain (protease inhibitor) on spontaneous and ultraviolet-induced sister-chromatid exchanges (sces) and 6-thioguanine-resistant (6tgr) recessive mutations were examined in v79 chinese hamster cells in culture. tpa and/or antipain neither significantly altered base-line and uv-induced immediate sce frequencies, nor decreased the level of delayed sces which persisted 6-7 days after irradiation. tp ... | 1980 | 7393240 |
| inability of chinese hamster ovary cells to excise o6-alkylguanine. | the capacity of chinese hamster ovary cells for excising alkylated bases from their dna was investigated. cells were treated with n-methyl-n-nitrosourea or n-ethyl-n-nitrosourea, and the amounts of 3-alkyladenine, 7-alkylguanine, and o6-alkylguanine in dna were compared immediately after the treatment and after a 20-hr incubation. cells were able to excise 3-alkyladenine and 7-alkylguanine, but there was no loss of o6-alkylguanine, after correction for dilution, due to dna synthesis during postt ... | 1980 | 7388815 |
| correlation of the growth of chinese hamster v279-17lb multicellular spheroids with cytokinetic parameters. | the volumes of chinese hamster v279-17lb multicellular spheroids grown in spinner culture were measured and correlated to dna distribution and cell volume distribution information. spheroid growth curves were obtained over a 21-day period using both electronic cell volume measurements and microscope micrometer sizing. the spheroids were collected from the aperture tube after electronic sizing, and single cell suspensions were prepared via trypsinization. saline-washed cells were then stained wit ... | 1980 | 7273964 |
| reversion of a mutation affecting the molecular weight of hgprt: intragenic suppression and localization of x-linked genes. | rjk39 is a clone of chinese hamster cells carrying a mutation which inactivates hypoxanthine-guanine phosphoribosyltransferase (hgprt) and reduces the apparent molecular weight of the enzyme. using mutagens, we have isolated subclones of rjk39 which will grow in the counterselective hat medium. some continue to be hgprt-deficient and survived the selection because they are resistant to aminopterin. in all but one of the hgprt-positive revertants, the molecular weight of the enzyme returned to th ... | 1980 | 7192435 |
| selection of wild-type revertants from methotrexate-resistant cells containing an altered dihydrofolate reductase. | a selection system for wild-type revertants from methotrexate-resistant chinese hamster ovary cells is described. in the absence of exogenous thymidine, cells use the folate metabolic pathway to generate thymidine 5'-monophosphate from deoxyuridine 5'-monophosphate. thus, in the presence of methotrexate, the incorporation of labeled deoxyuridine into phenotypic wild-type cells is inhibited whereas resistant cells that are cycling incorporate sufficient radioactivity to be killed. using several s ... | 1980 | 7003776 |
| production of cyclobutane type pyrimidine dimers in the dna of chinese hamster lung fibroblasts (v-79) exposed to u.v.-b light. | 1980 | 6968304 | |
| isolation of chinese hamster cell mutants deficient in dihydrofolate reductase activity. | mutants of chinese hamster ovary cells lacking dihydrofolate reductase (tetrahydrofolate dehydrogenase, 7,8-dihydrofolate:nadp+ oxidoreductase; ec 1.5.1.3) activity were isolated after mutagenesis and exposure to high-specific-activity [3h]deoxyuridine as a selective agent. fully deficient mutants could not be isolated starting with wild-type cells, but could readily be selected from a putative heterozygote that contains half of the wild-type level of dihydrofolate reductase activity. the hetero ... | 1980 | 6933469 |
| phenotypic evolution of cells resistant to bromodeoxyuridine. | variants resistant to bromodeoxyuridine (brdurd) and deficient in thymidine kinase (atp:thymidine 5'-phosphotransferase; ec 2.7.1.21) have been obtained from v79 chinese hamster cells by a combination of spontaneous and drug-induced change. initial mutations take place in wild-type populations as a facilitating step to give partially resistant clones that can be isolated by one-step selection in brdurd. when these tolerant populations are maintained for extended periods in brdurd-containing medi ... | 1980 | 6933467 |
| changes in surface morphology associated with ageing and carcinogen treatment of chinese hamster lung cells. | the relationship between ageing and transformation has been investigated by a serial study of the changes in cell-surface morphology as normal and carcinogen-treated cells progressed in culture. a progressive increase in the density of cell surface microvilli occurred in association with the adoption of a more rounded profile and concomitant increase in the rate of cell detachment. these changes occurred earlier after carcinogen treatment, which appeared to indicate a carcinogen-induced accelera ... | 1980 | 6775654 |
| inability of styrene to induce nondisjunction in drosophila or a positive micronucleus test in the chinese hamster. | styrene produced no effect on induction of sex-chromosome nondisjunction in drosophila melanogaster fed on 500 ppm styrene for 24 h. no increase in the frequency of micronuclei from chromosome fragments or from nondisjunction of whole chromosomes was seen in the bone marrow of chinese hamsters (cricetulus griseus) injected (i.p.) with a single dose of 1.0 g/kg b.wt. styrene or with 250 mg/kg b.wt. of the primary metabolite, styrene oxide. | 1980 | 6774448 |
| renal glucosyltransferase activity in highly-inbred spontaneously diabetic chinese hamsters. | a modified glucosyltransferase assay using degraded gelatin as acceptors was found to be enzyme concentration- and time-dependent in the chinese hamster kidney extracts. in 54 chinese hamsters selected from 7 highly inbred sublines with or without spontaneous glycosuria, the glucosyltransferase activity (0.78-3.25 unit/g) in the kidney was found to be significantly correlated (p = 0.0002) to blood sugar concentrations (60-475 mg/dl). however, subline-dependent variation in glycosyltransferase ac ... | 1980 | 6446476 |
| trypsin modifies the activity of adenylate cyclase from normal, malignant and hybrid mammalian cells. | adenylate cyclase (atp pyrophosphate-lyase (cylizing), ec 4.6.1.1) activity, measured in homogenates of normal, malignant and hybrid mammalian cell lines, is enhanced and subsequently inhibited by increasing concentrations of trypsin (ec 3.4.21.4). treatment of intact cells with trypsin appears to cause latent activation of adenylate cyclase (i.e. activation which is only expressed after homogenization of the cells). conversely, adenylate cyclase activity of a normal chinese hamster fibroblast c ... | 1980 | 6248130 |
| pressure inhibits thermal killing of chinese hamster ovary fibroblasts. | 1980 | 7402292 | |
| concentration-dependent effects of sodium butyrate in chinese hamster cells: cell-cycle progression, inner-histone acetylation, histone h1 dephosphorylation, and induction of an h1-like protein. | this paper presents the first unified quantitative study of the effects of butyrate concentration upon (1) cell-cycle progression, (2) modification of all inner histones, (3) dephosphorylation of histone h1, and (4) enhancement of an h1-like protein (bep) in cho cells. flow cytometric analysis shows that exposure to butyrate enriches cho cultures in g1 cells and, at sufficient butyrate concentration, leads to g1 arrest. additionally, butyrate alters the rate of cell-cycle progression through g2/ ... | 1980 | 7397096 |
| alanine transport by chinese hamster ovary cells with altered phospholipid acyl chain composition. | the na+-dependent transport of alanine has been examined in chinese hamster ovary (cho) cells as a function of the fatty acid composition of their membrane lipids. significant changes in the fatty acid composition of the cho cell phospholipids were achieved by supplementation of the growth medium with specific saturated (palmitate) or monoenoic (oleate) free fatty acids. arrhenius plots of the temperature-dependent uptake of alanine were constructed for cells of altered fatty acid composition. a ... | 1980 | 6104513 |
| dependence of the cytostatic effect of adriamycin on drug concenration and exposure time in vitro. | the surviving fraction (sf) of chinese hamster cells and hela cells after treatment with a range of adriamycin concentrations and exposure times was determined. the cytostatic effect was proportional to the product of extracellular drug concentration (c) and exposure time (t) according to the equation: sf=e-ktc. by determining the intracellular drug concentration at various exposures, it could be shown that absorbed dose is not proportional to exposure dose. | 1980 | 7426313 |
| protective effect of steroids on cultured cells damaged by high concentrations of oxygen. | chromosomal aberrations resulting from the exposure of chinese hamster lung fibroblast cells to 95% oxygen have been used to investigate the protective effect of three steroids. hydrocortisone had little useful effect. however, dosage of both methylprednisolone and dexamethasone could be increased to a level at which damage by oxygen was reduced to 50% of nuclei compared with 90% damaged in cells unprotected by steroids. there was no appreciable impairment of cell growth. concentrations of stero ... | 1980 | 7426227 |
| growth and g1 arrest of glucosamine requiring mutant cells derived from chinese hamster lung cells. | 1980 | 7410122 | |
| altered cell behavior of glucosamine requiring mutant derived from chinese hamster lung cells. | 1980 | 7410120 | |
| effect of oxygen-radiosensitizer mixtures on the radiation response of chinese hamster cells, line v.79-753b, in vitro. i. survival response. | 1980 | 7406984 | |
| the induction of sister-chromatid exchanges in chinese hamster ovary cells by some epoxides and phenolic derivatives of benzo[a]pyrene. | the induction of sister-chromatid exchanges in chinese hamster ovary cells by in vivo treatment with a number of epoxy and phenolic derivatives of the carcinogenic polycyclic hydrocarbon, benzo[a]pyrene, has been investigated. of the 3 vicinal diol-epoxides tested the anti-isomer of the bay-region 7,8-dihydrodiol-9,10-epoxide was the most active since, when tested at a 10-fold lower concentration, it induced the same number of sister-chromatid exchanges as the corresponding syn-isomer. the anti- ... | 1980 | 7393246 |
| sister-chromatid exchanges and chromosomal aberrations in cultured chinese hamster cells treated with pesticides positive in microbial reversion assays. | the induction of sister-chromatid exchanges (sces), chromosomal aberrations and polyploids was investigated in cultured chinese hamster cells treated with pesticides or a related compound positive in microbial reversion assays. the chemicals tested were captan, captafol, 1,2-dibromoethane (edb), 1,2-dibromo-3-chloropropane (dbcp), 5-nitro-1-naphrhonitrile (nnn), p-dimethylaminobenzenediazo sodium sulfonate (dapa), 2-hydrazinoethanol (heh), vamidothion, dichlorovos (ddvp), n-nitroso-ethylenethiou ... | 1980 | 7393245 |
| inhibition of dna chain elongation in a purine-auxotrophic mutant of chinese hamster. | dna synthesis has been examined in a purine-auxotrophic mutant cell line of chinese hamster (v79 pur 1) under conditions of purine deprivation. at 6 h after the removal of purines from the growth medium, there is a decrease in semiconservative dna replication. alkaline velocity centrifugation of the dna synthesized during a 1-min pulse under conditions of purine deprivation shows that approximately 50% of the newly replicated dna is the size of okazaki pieces. these are not incorporated into bul ... | 1980 | 7391141 |
| cell-cell adhesion molecule: identification of a glycoprotein relevant to the ca2+-independent aggregation of chinese hamster fibroblasts. | 1980 | 7388946 | |
| the incorporation of o4-methylthymidine into v79a cell dna when present in the cell culture medium. | when chinese hamster v79a cells are cultured in the presence of o4-methyl-[6-3h]-thymidine the incorporation of this modified nucleoside into newly synthesised dna is observed. the radioactivity incorporated has been identified as o4-methylthymidine by digesting the dna to 3'-monophosphates with spleen phosphodiesterase followed by treatment with alkaline phosphatase to give o4-methylthymidine as the major radioactive product. the radioactivity associated with the latter co-chromatographs with a ... | 1980 | 7273281 |
| analysis of the cell adhesion mechanism using somatic cell hybrids. i. aggregation of hybrid cells between adhesive v79 and non-adhesive ehrlich's ascites tumour cells. | v79 chinese hamster cells dissociated with 1 nm edta retain 2 kinds of cell adhesion mechanisms, one dependent on ca2+ and the other independent of ca2+. ehrlich's ascites tumour (eat) cells are provided with neither ca2+-dependent nor ca2+-independent mechanisms. studies on the aggregation of cells of 25 different hybrid clones obtained by fusing these 2 lined cells revealed the following points with regard to adhesive properties of hybrid cells. (1) the activity of the ca2+-independent mechani ... | 1980 | 6998992 |
| inhibition of carcinogen-induced chromosomal aberrations by an anticarcinogenic protease inhibitor. | it was hypothesized that chemicals- and radiation-induced carcinogenesis might require at least two specific chromosomal events that must coincide within a single target cell: (i) induction of chromosomal changes, possibly mutations, that are recessive and therefore latent in diploid somatic cells and (ii) aberrant mitotic segregation events that will convert the heterozygous cell, created by the first process, into a homozygous or hemizygous cell through chromosomal rearrangements. hence, we te ... | 1980 | 6932036 |
| stable heat-resistant variants in populations of chinese hamster cells. | sublines with increased survival at elevated temperatures were obtained by repeated exposure of v79 chinese hamster lung cells to 44.5 degrees c followed by regrowth of survivors to mass populations at 37 degrees c. after three cycles, the time at 44.5 degrees c required to reduce cell survival to 37% (d0 value) increased from 4.6 to 26.3 minutes. clonal isolates retained their resistance to thermal stress for at least 3 months in culture at 37 degrees c and showed distinctive differences from p ... | 1980 | 6929387 |
| sensitization to hyperthermia below 43 degrees c induced in chinese hamster ovary cells by step-down heating. | step-down heating (sdh) of chinese hamster ovary cells consisted of an acute heat treatment at an elevated temperature followed immediately by chronic exposure to a lower hyperthermic temperature [step-down temperature (sdt)]. the survival curve at the sdt showed a reduced d0 (dose required to reduce the cell population to 37% on exponential part of the curve) relative to that of control cells only for sdt of 43 degrees c or less. the ratio r of d0's, d0 (control)/d0 (sdh), varied inversely with ... | 1980 | 6929384 |
| incorporation of 3h-leucine, 3h-lysine, and 3h-tryptophan during the cell cycle of chinese hamster ovary cells: a flow cytometric analysis. | exponentially growing chinese hamster ovary cells were pulse labeled with 3h-leucine, 3h-lysine, or 3h-tryptophan, fixed, and stained by either the acriflavine-feulgen procedure or with fluorescein isothiocyanate (fitc). protein content as determined by fitc fluorescence was representative of protein content determined biochemically by the method of lowry. utilizing a fluorescence-activated cell sorter, 3h-labeled cells were sorted according to their dna or protein content and the incorporation ... | 1980 | 6771322 |
| genetics of chinese hamster mixed lymphocyte reactivity. | two-way and one-way mixed lymphocyte cultures (mlc) with chinese hamster peripheral blood lymphocytes were performed. reduction of the culture surface and additon of 2-mercaptoethanol to the culture medium gives a marked enhancement of the reactivity of low numbers of lymphocytes in the mlc. genetic analysis of the mixed lymphocyte reactivity (mlr) in the animals studied so far indicates that three or four different alleles are involved. however, not all phenotypes could be traced. the samples o ... | 1980 | 6447733 |
| multienzyme complex for metabolic channeling in mammalian dna replication. | in the dna-synthesizing phase (s phase) of chef/18 chinese hamster embryo fibroblast cells, six enzymes associated with dna metabolism, including dna polymerase (deoxynucleoside triphosphate:dna deoxynucleotidyl-transferase, ec 2.7.7.7), were largely localized in the nuclear region (karyoplasts). by contrast, in quiescent and g1 phase cells these enzymatic activites were mainly absent from the nucleus and were recovered in the cytoplasmic portion (cytoplasts). these nuclear (but not cytoplasmic) ... | 1980 | 6251456 |
| water permeability of mammalian cells as a function of temperature in the presence of dimethylsulfoxide: correlation with the state of the membrane lipids. | the water permeability of v-79 chinese hamster lung fibroblasts was determined by measuring the rate of cell shrinkage in hypertonic medium using a cell sizer. the water permeability appears to follow arrhenius kinetics as a function of temperature with a sharp discontinuity at 21 degrees c. an activation energy of 7.0 +/- 1.6 kcal/mole was found below 21 degrees c and 22.8 +/- 3.1 kcal/mole above 21 degrees c. the correlation time of rotation of the spin label 2,2-dimethyl-5-dodecyl-5-methyloxa ... | 1980 | 6249829 |
| total cellular rna content: correlation between flow cytometry and ultraviolet spectroscopy. | total rna content in chinese hamster ovary and hela-s3 cells determined by ultraviolet spectroscopy is compared with the red fluorescence distribution of acridine orange-stained cells observed by flow cytometry. a correlation coefficient of 0.93 is obtained when these methods of estimating rna content are compared after various rnase treatments. these data suggest that acridine orange staining effectively quantitates total cellular rna content when analyzed by flow cytometry, although dna is als ... | 1980 | 6156196 |
| mutants of chinese hamster ovary cells with altered membrane phospholipid composition. replacement of phosphatidylinositol by phosphatidylglycerol in a myo-inositol auxotroph. | 1980 | 7372588 | |
| chinese hamster ovary cells resistant to beta-aspartylhydroxamate contain increased levels of asparagine synthetase. | the growth of chinese hamster ovary cells in a complete medium lacking asparagine is inhibited by beta-aspartylhydroxamate. the inhibition is overcome by the presence of asparagine in the growth medium. beta-aspartylhydroxamate inhibits the activity of both asparagine synthetase and asparaginyl-trna synthetase in vitro. beta-aspartylhydroxamate-resistant clones of chinese hamster ovary cells have been isolated and three of these have been characterized. one clone, ah12, is 3-fold more resistant ... | 1980 | 6102991 |
| ornithine decarboxylase induction in cells stimulated to proliferate differs from that in continuously dividing cells. | ornithine decarboxylase activity increases at least 4-5-fold before dna synthesis both in synchronous cycling cells and in quiescent cells stimulated to proliferate. the purpose of our experiments was to test whether the transient peaks of ornithine decarboxylase activity in both growth situations were biochemically regulated in a similar manner. we found that the regulation of this particular enzyme activity is distinct in two ways. firstly, the addition of 2mm-hydroxyurea will block the induct ... | 1980 | 6772164 |
| cell cycle-related variations in uv damage and repair capacity in chinese hamster (cho-k1) cells. | uv damage to cho cell dna, measured by formation of thymine-containing dimers, increases from mitosis to early s phase. computer simulation of uv absorption by the dna of an idealized cho cell at different stages in the cell cycle resembles the cycle dependence of uv damage. incision at uv damage sites, measured by the accumulation of breaks in preexisting dna during 30 minutes' post-irradiation incubation with the dna synthesis inhibitors 1-beta-d arabinofuranosylcytosine and hydroxyurea, incre ... | 1980 | 7440631 |
| diphtheria toxin resistance in chinese hamster cells: genetic and biochemical characteristics of the mutants affected in protein synthesis. | diphtheria toxin (dt) resistant mutants (dipr) have been isolated from a number of different chinese hamster lines. among mutants affected in protein synthesis (diprii class), two distinct phenotypes have been identified. in one class, the entire elongation factor-2 (ef-2) activity becomes resistant to dt-catalyzed adp-ribosylation (dipriia class); these mutants behave recessively upon hybridization with sensitive cells. the second kind of protein synthesis mutants contain nearly normal levels o ... | 1980 | 7404268 |
| rapid, quantitative analysis of cell cycle stages of cold-sensitive derivatives of the chinese hamster cell line cho-k1. | cell cycle parameters of two cold-sensitive chinese hamster cell lines have been determined by flow cytometric analysis of cell populations stained with the dna specific fluorochrome mithramycin. the most striking finding is a depletion of s phase cells, detectable as early as 12 h after a shift to the nonpermissive temperature of 30.0 degrees c and complete by 24 h following the shift. there is a substantial increase in the proportion of cells in the g1 phase of the cell cycle compared to wild ... | 1980 | 7404267 |
| cho mutants resistant to colchicine, colcemid or griseofulvin have an altered beta-tubulin. | single-step mutants of chinese hamster ovary (cho) cells have been isolated which are resistant to killing by the anti-mitotic drugs colchicine, colcemid or griseofulvin. two-dimensional gel analysis showed that two mutants resistant to griseofulvin, one resistant to colcemid and one resistant to colchicine carry an alteration in the beta-tubulin subunit. most of the remaining isolates are believed to be permeability mutants on the basis of their cross resistance to drugs which do not interefere ... | 1980 | 7388944 |
| arrested growth of chinese hamster ovary (cho) cell colonies on agar. | chinese hamster ovary (cho) cells plated on agar form two classes of colonies; those which increase continuously in diameter and those which become arrested in outward growth. all colonies continue to increase in mass and thickness as demonstrated by computer-assisted analysis of time sequence photographs of several thousand colonies and by examination of histological sections. colonies which shift from a monolayer to a mounded morphology at fairly large colony diameter (greater than or approxim ... | 1980 | 7371065 |
| induction of 8-azaguanine or ouabain resistant somatic mutation of chinese hamster lung cells by treatment with tryptophan products. | the basic fraction of tryptophan pyrolysis products (tbf) showed strong mutagenic activity on somatic cells of the lung of chinese hamsters. in this somatic mutation test, tbf was demonstrated to have 5.6 times higher mutagenicity than diethylnitrosamine (den) when mutants were selected with 8-azaguanine, and 13.5-fold higher mutagenicity than den when mutants were selected with ouabain. from these findings, it is suggested that pyrolyzates of amino acids may have mutagenic actions on somatic ce ... | 1980 | 7226150 |
| mutagenicity, cytotoxicity, and dna binding of platinum(ii)-chloroammines in chinese hamster ovary cells. | the cytotoxicity and mutagenicity at the six platinum(ii)chloroammines have been investigated in chinese hamster ovary cells. for these compounds, the observed slopes of the mutation-induction curves (mutants/10(6) cells/microm) were: cis-pt(nh3)2cl2 (31.5), k[pt(nh3)cl3] (2.78), [pt(nh3)3cl]cl (0.11), k2[ptcl4] (0.12), trans-pt(nh3)2cl2 (0.013), and [pt(nh3)4]cl2 (0.0). the relative cytotoxicity of these compounds follows the same order and is of similar magnitude. the observed relative mutagen ... | 1980 | 7189447 |
| mitochondrial protein synthesis in chinese hamster cells (line cho) synchronized by isoleucine deprivation. | mitochondrial protein synthesis was measured in line cho cells after phases of the cell cycle were synchronized by isoleucine deprivation or mitotic selection. maximum incorporation of [3h] leucine into mitochondrial polypeptides occurred within 2 hours after isoleucine was added to initiate g1 traverse. in cells synchronized in g1 by mitotic selection, the rate of mitochondrial protein synthesis was fairly constant throughout the cell cycle. sds-polyacrylamide gel electrophoretic profiles of la ... | 1980 | 7002936 |
| chromosomal aberrations and mutation in cultured mammalian cells induced by pyrrolizidine alkaloids. | 4 pyrrolizidine alkaloids, heliotrine, lasiocarpine, petasitenine, and senkirkine, were tested for their effects of v79 chinese hamster cells. all the alkaloids produced cytoplasmic vacuolization, and caused cellular and nuclear enlargement. chromosomal aberrations were induced in cells treated with the alkaloids. heliotrine and petasitenine induced interchromosomal exchanges, and lasiocarpine and senkirkine caused chromatid gaps. all the alkaloids induced an 8-azaguanine-resistant mutation in v ... | 1980 | 6991930 |
| isolation of a chinese hamster fibroblast mutant defective in hexose transport and aerobic glycolysis: its use to dissect the malignant phenotype. | a procedure is described for the selection of glucose uptake mutants based upon radiation suicide of chinese hamster fibroblasts by 2-deoxy[3h]glucose. in one of these mutants, ds 7, the ability to transport either 2-deoxyglucose or 3-o-methylglucose was decreased to one-fifth to one-fourth. besides this defect, ds7 produces 1/14th the lactic acid produced by the parent when grown on 5 mm glucose. this block in aerobic glycolysis is due to a mutation that affects the expression of the phosphoglu ... | 1980 | 6930659 |
| the chinese hamster gene map. assignment of four genes (dts, pgm2, 6pgd, enoi) to chromosome 2. | 1980 | 6445830 | |
| inactivation of synchronized chinese hamster v79 cells with charged-particle track segments. | 1980 | 6246560 | |
| cycle-dependent anticancer drug cytotoxicity in mammalian cells synchronized by centrifugal elutriation. | the cycle-dependent cytotoxicity of seven chemotherapy agents was compared with the use of subpopulations of chinese hamster ovary cells separated into the various phases of the cell cycle by centrifugal elutriation. the proportion of cells killed by either beta-cytosine arabinoside or hydroxyurea agreed well with the proportion of s-phase cells in the treated subpopulations. cell-cycle survival patterns were also determined for bleomycin (blm), adriamycin (adr), cis-diamminedichloroplatinum (ii ... | 1980 | 6154171 |
| effect of lipid soluble antioxidants on cytotoxicity induced by photochemical products of cholesterol. | lipid soluble antioxidants, butylated hydroxytoluene and vitamin e, were shown to suppress cytotoxicity induced by cholesterol-derived photoproducts in chinese hamster embryo cells. these cholesterol-derived photoproducts were rather toxic. | 1980 | 7379918 |
| action of phalloidin on the mitotic cycle in chinese hamster fibroblasts. | 1980 | 7393336 | |
| regulation of translation. analysis of intermediary reactions in protein synthesis in exponentially growing and stationary phase chinese hamster ovary cells in culture. | 1980 | 7388000 | |
| differential involvement of cell surface sialic acid residues in wheat germ agglutinin binding to parental and wheat germ agglutinin-resistant chinese hamster ovary cells. | two chinese hamster ovary (cho) cell mutants selected for resistance to wheat germ agglutinin (wga) have been shown to exhibit defective sialylation of membrane glycoproteins and a membrane glycolipid, gm3. the mutants (termed wgarii and wgariii) have been previously shown to belong to different genetic complementation groups and to exhibit different wga-binding abilities. these mutants and a wga-resistant cho cell mutant termed wgari (which also possesses a surface sialylation defect arising fr ... | 1980 | 7364875 |
| adaptive alteration in phospholipid composition of plasma membranes from a somatic cell mutant defective in the regulation of cholesterol biosynthesis. | a somatic cell mutant (cr1) of a chinese hamster ovary cell (cho-k1) which has previously been shown to be defective in the regulation of cholesterol biosynthesis accumulates more cholesterol than the parental cell line in plasma membranes. although such an increase in membrane cholesterol should lead to an increase in the order parameter of these membranes, as measured with an electron spin resonance spin probe, the order parameters of mutant and wild-type plasma membranes are identical--appare ... | 1980 | 7364872 |
| comparison of induction of sister chromatid exchange, 8-azaguanine- and ouabain-resistant mutants by cyclophosphamide, ifosfamide and 1-(pyridyl-3)-3,3-dimethyltriazene in chinese hamster cells cultured in diffusion chambers in mice. | data on induction of sister chromatid exchange (sce), 8-azaguanine and ouabain-resistant mutants in v79 cells in diffusion chambers in mice treated with three chemicals were compared to determine the relationship between sce and mutation. for 1-(pyridyl-3)-3,3-dimethyltriazene, a positive, linear correlation was demonstrated between induced sce and mutation at both loci. for cyclophosphamide and ifosfamide, it was observed that sce analysis was a more sensitive biological endpoint than induction ... | 1980 | 7273275 |
| the energy charge in wild-type and respiration-deficient chinese hamster cell mutants. | high pressure liquid chromatography was used to determine the base, nucleoside, and nucleotide levels in wild type and a series of respiration-deficient chinese hamster cell mutants. from this analysis the size of the total adenylate pool and the energy charge could be calculated for each cell line. we find a constant energy charge, as expected, but the adenylate pool seems to be considerably lower in the respiration-deficient mutants. | 1980 | 7191856 |
| time-dependent changes in drug sensitivity expressed by mammalian cells after exposure to trypsin. | immediately after a 5-minute exposure to 0.025% trypsin, chinese hamster ovary cells treated with anticancer drugs exhibited changes in drug sensitivity. depending on the drug, cells immediately became more sensitive, less sensitive, or showed no change in sensitivity at all. the deviation from normally expected survival values ranged from fourfold to fifty-fold and varied with time (of drug treatment) after trypsinization. by the 12th hour post trypsinization, the drug survival responses had re ... | 1980 | 6929002 |
| the metabolism of serine and glycine in mutant lines of chinese hamster ovary cells. | 1980 | 6776895 | |
| the ultrastructure of process formation following treatment with db-camp of a chinese hamster ovary x chinese hamster brain cell hybrid. | 1980 | 6244966 | |
| conjugation of methotrexate to poly (l-lysine) as a potential way to overcome drug resistance. | methotrexate (mtx) was conjugated through a carbodiimide-catalyzed reaction to poly (l-lysines) of various molecular sizes at a ratio of approximately one molecule per 27 lysyl residues. these conjugates were tested on cultured, chinese hamster, ovary cells known to be drug resistant because of a deficient methotrexate transport. the cellular uptake of conjugated drug far exceeded the uptake of free drug in both drug sensitive and resistant lines. the conjugated drug inhibited the growth of the ... | 1980 | 7357512 |
| pactamycin resistance in cho cells: morphological changes induced by the drug in the wild-type and mutant cells. | stable mutants resistant to pactamycin (pacr), a polypeptide chain initiation inhibitor, have been selected in a single step in chinese hamster ovary (cho) cells. the sensitivity of protein synthesis in mutant cell extracts to pactamycin indicates that resistance involves an alteration in the permeability of this drug. the failure of pacr mutants to show cross-resistance to other compounds provides further indication that the lesion is presumably specific for pactamycin. cell hybrids formed betw ... | 1980 | 7391143 |
| effect of heat combined with polyamines on tumor growth in mice. | the combined effect of heat and polyamines on transplanted b16 melanomas was studied in mice. a synergistic interaction between heat and the polyamines spermine and cadaverine was demonstrated, confirming previous observations with cultured chinese hamster cells. the effect, however, was weak, resulting in no more than a 20% increase in the mean survival time. this was due to toxicity limitations on the doses of polyamines delivered to the animals. thus, at least in this system, the combined tre ... | 1980 | 7390757 |
| dna damage, cell survival and dna repair in chinese hamster ovary cells after in vitro metabolic activation of dimethylnitrosamine and benzo[a]pyrene. | both benzo[a]pyrene (bp) and dimethylnitrosamine (dmn) cause a dose-related increase in single-strand dna lesions in cho cells after in vitro metabolic activation, as detected by alkaline sucrose gradients (asg) sedimentation analysis. this type of dna damage and cell survival are inversely related with dmn, whereas there is negligible cell killing with bp even at concentrations producing maximal dna damage. however, high concentrations of bp do result in a reduction in colony size, suggesting a ... | 1980 | 7383044 |
| chlorpropamide inhibition of excision repair and postreplication repair of ultraviolet damage in chinese hamster ovary cells. | chlorpropamide, an oral hypoglycemic agent, was tested for effects on excision repair and postreplication repair of ultraviolet (uv) damage of dna in cho-k1 cells. the technique used to measure excision repair involved isopycnic centrifugation of density- and isotopically-labeled dna. alkaline sucrose gradient sedimentation was used to monitor postreplication repair. administration of chlorpropamide at 250 and 1000 microgram/ml after exposure of cultures to 254-nm uv reduced excision repair to 7 ... | 1980 | 7383043 |
| enhanced killing of chinese hamster cells following combined exposure to 'sunlight' and x-rays. | 1980 | 7367471 | |
| the redistribution of fluoresceinated concanavalin a in chinese hamster ovary cells and in their colcemid-resistant mutants. | 1980 | 7358097 | |
| [use of the effect of impaired complete internal reflection for studying the adhesion of animal cells to glass. iii. measurement of the refractive index of hyaloplasm and determination of the distance between cell membrane surface and glass]. | the kinetics of form change (flattening) of chinese hamster fibroblast cell surface facing the glass has been studied during attachment of fibroblasts to the glass using the effect of frustrated total reflection. two stages of the process were shown to exist. the first one is characterized by a rapid (5 min) partial flattening and requires no serum in the medium. the second stage occurs only in the presence of serum in the medium, it lasts no longer than one hour and ends in a complete flattenin ... | 1980 | 6989063 |
| [use of the effect of impaired complete internal reflection for studying the adhesion of animal cells to glass. ii. kinetics of flattening of the cell surface facing the glass]. | the kinetics of form change (flattening) of chinese hamster fibroblast cell surface facing the glass has been studied during attachment of fibroblasts to the glass using the effect of frustrated total reflection. two stages of the process were shown to exist. the first one is characterized by a rapid (5 min) partial flattening and requires no serum in the medium. the second stage occurs only in the presence of serum in the medium, it lasts no longer than one hour and ends in a complete flattenin ... | 1980 | 6989062 |
| [determination of the effectiveness of chinese hamster cell fusion in monolayers]. | using polyethylene glycol 6000 (peg), cell fusion was obtained for the chinese hamster transplantable culture. a most rational character of cell fusion efficiency was the amount of nuclei found in multinuclear cells (polykaryocytar index) determined within 30-60 minutes after peg treatment of the culture. after a 1-6 hour treatment, a mass death of polykaryocytes was more than 8 hours; in 3 hours and up to the end of a 24 hour's period of observation an intensive cell division is observed. | 1980 | 6989061 |
| linkage of genetic markers emt and chr in chinese hamster cells. | segregation analysis in somatic cell hybrids has been used to demonstrate linkage in the cho cell line between two autosomal loci, emt (defined by mutants resistant to the protein synthesis inhibitor emetine) and chr (defined by mutants resistant to chromate). in both cases drug resistance behaves recessively in hybrids and linkage has been determined by examining the recovery of the mutant phenotypes from hybrids of the type cho emtr chrr x cho emt+ chr+. of 24 independent segregants selected f ... | 1980 | 6930704 |