Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| organisation of the genes coding for 5s rna in the chinese hamster. | hybridisation of iodinated mouse 5s rna with chinese hamster dna fractionated on a cscl gradient, identifies two separate dna components that hybridise with the labelled probe. one component is slightly, and one considerably heavier than the main band dna. this suggests that the gene coding for 5s rna in the chinese hamster may constitute two distinct populations differing in g + c content of their adjacent spacer regions. | 1976 | 1250414 |
| selective modification of cell surface proteins and thymidine transport in hamster cells exposed to cholera toxin. | the increased adherence and morphological response which occurs in chinese hamster ovary cells as a result of exposure to cholera toxin is paralleled by modification in the relative exposure of outer proteins. mild proteolysis treatment of the cells prelabeled with [3h] glucosamine reveals a markedly different kinetics of release of external glycopeptides as a result of exposure to cholera toxin. selective alterations in external tyrosyl-rich proteins can also be detected by lactoperoxidase-cata ... | 1976 | 1256059 |
| a comparative analysis of the karyotypes of cricetus cricetus and cricetulus griseus. | this study presents a comparison of the mitotic chromosomes of the two species of hamsters cricetus cricetus (european hamster) and cricetulus griseus (chinese hamster), which have the same chromosome number of 2n=22.--g-banding procedure reveals striking similarities in both karyotypes and gives the possibility to analyse structural changes so that two examples for robertsonian rearrangement can be observed.--a remarkable kind of difference between the two karyotypes becomes obvious after c-ban ... | 1976 | 1269344 |
| isolation and properties of heat-labile enterotoxin(s) from enterotoxigenic escherichia coli. | various techniques have been applied to the detection of skin reactivity associated with heat-labile escherichia coli enterotoxin in fermenter-grown cultures of enterotoxigenic strains in syncase medium and in trypticase soy broth. isolated products that were homogeneous, as determined by disc electrophoresis and sodium dodecyl sulfate gel electrophoresis, differed immunologically and in physicochemical characteristics depending on the strain and medium used, even though the products had similar ... | 1976 | 768386 |
| animal models of diabetes and obesity, including the pbb/ld mouse. | diabetes mellitus occurs in many animals species. however, only a few have been utilized in systematic studies designed to answer unsolved problems associated with the disorder in man such as molecular basis, pathogenesis of the vascular and neural lesions, and the roles of diet, exercise and obesity. among the animal models available, rodents have been studied most thoroughly for a number of reasons: a) short generation time (sexually mature at about 3 mo of age, gestation time 21 days) and lif ... | 1976 | 770197 |
| inhibition of human lymphoma cell-line colony formation by lymphocytes from patients with lymphoma and cancer hospital employees. | inhibition of human lymphoma cell-line colony formation (icf) was induced by peripheral blood lymphocytes (pbl) from patients with lymphoma and apparently healthy cancer hospital personnel. pbl from patients with non-lymphoma neoplasms and from normal blood bank donors did not elicit icf. icf was most marked when pbl were cocultivated for 24 hours in a ratio of 1000:i with target lymphoma cells that had been cultured for 24 hours before exposure. no significant icf was observed when target cells ... | 1976 | 779948 |
| mutagenicity and cytotoxicity of benzo(a)pyrene arene oxides, phenols, quinones, and dihydrodiols in bacterial and mammalian cells. | twenty-nine benzo(a)pyrene derivatives were tested for mutagenic acitivity without metabolic activation in salmonella typhimurium strains ta98, ta100, and ta1538 and in chinese hamster v79 cells. the compounds studied included 4 arene oxides, all 12 isomeric phenols, 5 quinones, and 8 dihydrodiols. benzo(a)pyrene 4,5-oxide was the most mutagenic of the compounds tested in both the bacterial and mammalian systems. the other arene oxides [benzo(a)pyrene 7,8-, 9,10-, and 11,12-oxides] were only wea ... | 1976 | 788898 |
| mutagenicity and cytotoxicity of benzo(a)pyrene benzo-ring epoxides. | four benzo-ring epoxides of the environmental carcinogen benzo(a)pyrene (bp) were tested for mutagenic and cytotoxic activity in 3 strains of salmonella typhimurium (ta1538, ta98, and ta100) and in chinese hamster v79 cells. although very unstable in aqueous solution, 7beta,8alpha-dihydroxy-0beta,10beta-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene (diol epoxide 1), with the 7-hydroxyl group on the same face of the molecule as the epoxide oxygen, was 1.5 to 4 times as mutagenic in the bacterial strain ... | 1976 | 788899 |
| mutagenicity of industrial compounds: styrene and its possible metabolite styrene oxide. | styrene and its presumed metabolite, styrene oxide, were tested for their mutagenic effect on a forward mutation system of yeast and of chinese hamster cells, and on a gene-conversion system of yeast. experiments with liver microsomal preparations and host-mediated assay with yeast were also carried out. styrene oxide was mutagenic in all test systems. styrene was mutagenic only in the host-mediated assay. | 1976 | 796697 |
| the mutagenicity of benzimidazole and benzimidazole derivatives. vi. cytogenetic effects of benzimidazole derivatives in the bone marrow of the mouse and the chinese hamster. | methyl benzimidazole-2-ylcarbamate (mbc) was mutagenic in mice by the micro-nucleus test. other benzimidazole derivatives, with the exception of the parent compound of mbc, benomyl, and the very closely related substance 2-benzimidazolylurea, did not produce micro-nuclei in mouse bone marrow. evidence is presented that mbc acts through inhibition of mitosis and that for this action the carbamoyl group is a necessary but not a sufficient condition. it is also demonstrated that for this particular ... | 1976 | 796698 |
| sister chromatid exchange as an assay for genetic damage induced by mutagen-carcinogens. ii. in vitro test for compounds requiring metabolic activation. | sister chromatid exchanges (sce's) which are easily seen by "harlequin chromosome" techniques can be readily induced in cultured chinese hamster ovary (cho) cells by low concentrations of mutagen-carcinogens that do not require metabolic activation. if the cells are simultaneously treated with cyclophosphamide which does require metabolic activation before it becomes mutagenic, and an activating system consisting of an extract of rat liver containing microsomes (s-9 mix) then numerous sce's are ... | 1976 | 796721 |
| mutagenicity and metabolism of vinyl chloride and related compounds. | the various adverse biological effects of vinyl chloride appear to be dependent upon the metabolic conversion of this compound into chemically reactive metabolites. the metabolism of vinyl chloride in mammals and in man, including the formation of monochloroacetic acid and some identified sulfur conjugates is reviewed. hepatic microsomal mixed function oxidases from rats, mice, and humans were equally effective in transforming vinyl chloride into alkylating agents in vitro. two of the enzyme rea ... | 1976 | 799962 |
| mutagenesis by simian virus 40. i. detection of mutations in chinese hamster cell lines using different resistance markers. | the mutagenic action of sv40 in permanent lines of chinese hamster cells (cho-k1 and v79) was investigated with the aid of different resistance markers. the markers studied had resistance to 8-azaguanine (25 and 30 mug/ml), aminopterin (3.3--5.5x10(-3) mug/ml), colchicine (6.5 and 7.0x10(-2) mug/ml) and 5-bromodeoxyuridine (50--120 mug/ml), respectively. after virus infection the mutation frequencies were increased by one (azaguanine, aminopterin) and two (colchicine) orders of magnitude as comp ... | 1976 | 184380 |
| ultrastructural study of the adenohypophysis of the chinese hamster. | the adenohypophysis of normal chinese hamsters of both sexes was examined ultrastructurally. organs were fixed by intravascular perfusion with s-collidine-buffered glutaraldehyde solution. seven types of cells were differentiated and, according to morphological characteristics, classified as (1) mammotropes, with very large (400-800 nm) polymorphous secretory granules; (2) somatotropes, either in the storage phase with numerous large, dense granules (average 300 nm), or in the hormone synthesis ... | 1976 | 184639 |
| confirmation of the assignment of the locus determining ada to chromosome 20 in man: data on possible synteny of ada and itp in human-chinese hamster somatic cell hybrids. | 1976 | 185012 | |
| chromosomal assignment of the gene for human red cell adenylate kinase (ak1) in man-chinese hamster somatic cell hybrids. | 1976 | 185020 | |
| simian virus 40 mutants carrying two temperature-sensitive mutations. | five temperature-sensitive mutants of simian virus 40 containing two temperature-sensitive mutations were isolated. the double mutant of the a and d complementation groups, like the d mutants, failed to complement by conventional complementation analysis and did not induce host dna synthesis at 40 degrees c. however, under conditions that suppressed the d defect, the a:d double mutant expressed only the a defect. thus, viral dna replication dropped rapidly after this mutant was shifted from perm ... | 1976 | 185417 |
| [transmission and expression of malignancy in somatic hybrid cell lines (hamster/hamster, mouse/mouse, hamster/mouse)]. | various characteristics of transformation were studied in subclones isolated from a hybrid cell line obtained by fusion of two chinese hamster sub-lines having the same origin but presenting different properties, particularly in respect to heterotransplantability. different subclones were obtained by cloning on semisoft agar. transplantability, plating efficiency, agglutinability by concanavalin a and actinomycin d resistance were studied in parallel with the evolution of the karyotype to try to ... | 1976 | 186142 |
| transformation of chinese hamster embryo cells with an avian sarcoma virus ts mutant. | chinese hamster embryo cells were transformed with temperature-sensitive mutant of the schmidt-ruppin strain of rous sarcoma virus-subgroup a (ts ny68s ra-a). the developed cell line elicited the morphological transformation at a permissive temperature of 35 degrees c, whereas after a shift to a non-permissive temperature of 40 degrees c the cells reverted to a normal phenotype. tests for the presence of avian sarcoma group-specific antigen showed that the antigen was not expressed both at permi ... | 1976 | 186335 |
| evolutionary trends in 18s ribosomal rna nucleotide sequences of rat, mouse, hamster and man. | the large t1 ribonuclease fragments of 18s ribosomal rna from four mammalian species, rat, mouse, hamster and man, were compared by two-dimensional homochromatography fingerprinting. the nucleotide sequences of the large t1 ribonuclease fragments, polypyrimidines and polypurines which were different among the four mammalian species were determined and compared. the method used for determining nucleotide sequences utilizes 32p-labeling of oligonucleotides at their 5'-termini by polynucleotide kin ... | 1976 | 188015 |
| laboratory investigation of diarrhea in travelers to mexico: evaluation of methods for detecting enterotoxigenic echerichia coli. | a laboratory investigation was conducted on cultures collected from travelers before, during, and after a trip to mexico to characterize the etiology of traveler's diarrhea. four laboratory methods for detecting enterotoxigenicity of escherichia coli were evaluated: the infant mouse assay, the chinese hamster ovary (cho) cell assay, the y1 adrenal cell assay, and the rabbit ileal loop. although a number of common enteric pathogens were identified as a cause of traveler's diarrhea, including six ... | 1976 | 180047 |
| the selection of virus-resistant chinese hamster ovary cells. | we have selected chinese hamster ovary (cho) cells resistant to infection by encephalomycarditis (emc) virus. thus far, we have obtained five lines resistant to emc, all of which manifest different phenotypes. three of the five are not persistently infected with virus, while two lines produce infectious virus and grow in its presence. the nonpersistently infected lines exhibit different resistance profiles to the other viruses we have tested, and they are stable in nonselective growth conditions ... | 1976 | 182382 |
| 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 ... | 1976 | 6133 |
| the production of chinese hamster interferon. | 1976 | 11678 | |
| 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 ... | 1976 | 12752 |
| resting state in normal and simian virus 40 transformed chinese hamster lung cells. | normal cell deprived of amino acids or serum factors enter a resting state, whereas cells transformed by wild-type simian virus 40 do not. the ability to enter a resting state is temperature-sensitive (ts) in cells transformed by a tsa mutant of simian virus 40. we shown further: (i) that when complete medium is added to resting cells, the length of time until the onset of dna synthesis often exceeds the length of g1 in growing cells; (ii) that the length of this interval depends upon the condit ... | 1976 | 179093 |
| persistent reovirus infection of cho cells resulting in virus resistance. | we obtained a persistently infected line of chinese hamster ovary cells by selection for resistance to reovirus infection. the cells were persistently infected by a population of viruses that were (i) cytopathic for parental chinese hamster ovary cells and (ii) similar to wild-type reovirus in molecular characteristics. the growth rate, plating efficiency, and morphology of the cells were altered. a large majority of the cells in the population were infected. there was no detectable interferon p ... | 1976 | 176428 |
| chromosomally depleted interspecific hybrid cell clones selected with cytotoxic antisera: utilization in the study of control of murine leukemia virus host-range. | a chromosomally stable mouse-chinese hamster hybrid cell line was subjected to five rounds of selection with cytotoxic antisera raised in rabbits against either the parental mouse 3t3 cells or the parental chinese hamster wg-1 cells. routine karyological analysis of clones isolated at each stage of serum selection revealed that treatment with either serum resulted in a limited loss of chromosomes (compared to the untreated hybrid cell cultured in parallel) and that the pattern of chromosome loss ... | 1976 | 176536 |
| assignment of the ak1:np:abo linkage group to human chromosome 9. | in man-chinese hamster somatic cell hybrids the segregation patterns of the loci for 25 human enzyme markers and human chromosomes were studied. the results provide evidence for the localization of the gene for adenylate kinase-1 (ak1) on chromosome 9. since the loci for the abo blood group (abo), nail-patella syndrome (np), and ak1 are known to be linked in man, the abo:np:ak1 linkage group may be assigned to chromosome 9. | 1976 | 176661 |
| simian virus 40-chinese hamster kidney cell interaction. ii. the semipermissivity of the cell system. | throughout in vitro passages, chinese hamster kidney (chk) cells progressively lost susceptibility to sv 40 virus infection while remaining continuously susceptible to viral dna infection. upon infection with sv 40 virus or viral dna, the chk cell line supported viral dna and virus replication at a low level. sv 40 transformed chk cell lines spontaneously produced small amounts of viral dna and virions. the percentage of virus-producing cells was low. various clones derived from each of these li ... | 1976 | 176967 |
| enhanced sv 40-virus replication in chinese hamster kidney cells pretreated with 5-iodo-2'-deoxyuridine. | sv40 virion production was enhanced when semipermissive chinese hamster kidney cells were treated with 5-iodo-2'-deoxyuridine (iudr), prior to infection either with virus or viral-dna. pretreatment did not increase sv40 replication in fully permissive monkey kidney and nonpermissive syrian hamster or mouse embryo cells. | 1976 | 176975 |
| induction by short-chain fatty acids of alkaline phosphatase activity in cultured mammalian cells. | short-chain fatty acids, such as propionic, n-butyric, n-butyric, n-valeric, isovaleric, n-caproic, and n-caprylic acids, induce alkaline phosphatase activity in cultured mammalian cells. long-chain fatty acids have no similar effects. with b-6 cells (mouse x chinese hamster cell hybrids), n-butyrate at 2 to 5 mm exhibits the greatest activity. induction begins exponentially about 24 hours after addition of the fatty acid and continues over 48 hours. studies on the inducing activity-structure r ... | 1976 | 177433 |
| the effects of serum concentration on the level of integration of simian virus (sv40) genome and the transformation frequency in sv40-infected chinese hamster cells. | 1976 | 174291 | |
| 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 ... | 1976 | 55904 |
| 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 ... | 1976 | 57619 |
| 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 ... | 1976 | 59551 |
| 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. ... | 1976 | 61843 |
| 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, ... | 1976 | 62055 |
| 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 ... | 1976 | 64925 |
| chromosomal assignment of the gene for human red cell adenylate kinase (ak1) in man-chinese hamster somatic cell hybrids. | 1976 | 192371 | |
| localization of the structural genes for hexokinase-1 and inorganic pyrophosphatase on region (pter-->q24) of human chromosome 10. | concordant expression of human hexokinase-1 and inorganic pyrophosphatase was established in somatic cell hybrids between thymidine kinase-deficient chinese hamster cells and human fibroblasts carrying a translocation of the distal third of the long arm of chromosome 10 to chromosome 17. neither human hexokinase-1 nor human inorganic pyrophosphatase expression segregated concordantly with human cytoplasmic glutamic-oxaloacetic transaminase expression. | 1976 | 17494625 |
| the effect of cyclophosphamide on the centromere separation sequence in chinese hamster spermatogonia. | the sequence of centromere separation in spermatogonial chromosomes of untreated and cyclophosphamide-treated chinese hamsters is described. centromeres of chromosome 1 and 2 separated much earlier than all other chromosomes, especially 6-8. cyclophosphamide significantly inhibits the centromere separation in all chromosome groups but does not alter the sequence of separation. | 1977 | 598845 |
| tyzzer's disease in the chinese hamster (cricetulus griseus). | 1977 | 599880 | |
| effects of ultraviolet light on synchronized chinese hamster ovary cells; potentiation by hydroxyurea. | we have examined the effects of hydroxyurea on u.v.-irradiated chinese hamster cho-ki cells. ultraviolet irradiation followed by incubation with hydroxyurea causes only slight disruption of dna and chromosome structure in cho-ki cells compared with hela cells. there is, however, a clear potentiation by hydroxyurea of the u.v. killing of cho-ki cells, which is most pronounced at those points in the cycle which are reported to have small dna precursor pools. this potentiation is reduced when dna p ... | 1977 | 599176 |
| pesticide induced ouabain resistant mutants in chinese hamster v79 cells. | the effect of 3 insecticides (chlordane, dieldrin and carbaryl) and one herbicide (2,4-d-fluid) was studied on the induction of ouabain-resistant mutants in chinese hamster v79 cells at concentrations approaching the environmental protection agency (epa) tolerance limits. the kinetics and dose range for cytotoxicity were determined by colony formation assay. results showed that these compounds enhanced the number of ouabain-resistant mutants and acted as weak mutagens. | 1977 | 413633 |
| retention of the glycocalyx after cell detachment by egta. | chinese hamster ovary cells were examined ultrastructurally following several detachment procedures. alterations in the surface glycoproteins were observed by using ruthenium red in the fixation procedure. trypsin removed a major portion of the cells glycocalyx and formed spherical cellular configurations. egta detached cells were also spherical, however, their glycocalyx appeared to remain although redistributed over the cell surface. kinetic studies showed no alterations in subsequent populati ... | 1977 | 411829 |
| a search for allelic recombination in chinese hamster cell hybrids. | mutants resistant to 6-thioguanine were selected from cho cells which were either temperature sensitive or proline requiring. these mutants were stable and had low levels of hypoxanthine guanine phosphoribosyl transferase (hgprt). hybrids were selected which were heteroallelic at the hgprt locus and complementation between the mutants used was not observed. interallelic recombination at this locus would generate hgprt+ cells which could be selected in littlefield's hat medium. selection experime ... | 1977 | 600266 |
| analysis of karyotype variation following carcinogen treatment of chinese hamster primary cell lines. | chinese hamster primary fibroblasts derived from several embryos were treated with the carcinogens benzo(a)pyrene, 7,12-dimethylbenz(a)anthracene or n-methyl-n'-nitro-n-nitrosoguanidine. karyotype analysis, sister chromatid exchange frequency, evidence of transformation by growth in agar, cell morphology and reaction to cytocholasin b were tested at regular intervals over many culture passages. carcinogen treatment was found to shorten the time period before onset of permanent karyotypically cha ... | 1977 | 924693 |
| 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 ... | 1977 | 72637 |
| a role for aminoacyl-trna synthetases in the regulation of amino acid transport in mammalian cell lines. | the regulation of neutral amino acid transport was examined utilizing two temperature-sensitive aminoacyl-trna synthetase mutants, by comparison of their transport activities at permissive and marginally permissive temperatures. when the temperature-sensitive leucyl-trna -synthetase mutant tsh1 was shifted from a normal growth temperature of 34 degrees to a marginally permissive temperature for growth of 38%, a significant enhancement in the initial rate of uptake of leucine and other l system a ... | 1977 | 914817 |
| studies on adenosine 3',5'-phosphate-binding and adenosine 3',5-phosphate-dependent protein kinase activities associated with subcellular fractions of chinese hamster ovary cells. | both cyclic amp-binding and cyclic amp-dependent protein kinase activities exist in chinese hamster ovary cell extract. competition experiments demonstrate that the binding is specific for cyclic amp. all cellular elements including nucleus, mitochondria, plasma membrane, microsome, ribosome and cytosol contain both activities. binding activity is highest in the cytosol and lowest in the nucleus. each fraction contains endogenous protein kinase activity which is insensitive to cyclic amp activat ... | 1977 | 200277 |
| histone composition of nucleosomes isolated from cultured chinese hamster cells. | nuclei isolated from cultured chinese hamster cells were treated with micrococcal nuclease and lysed, and the resulting chromatin subunit classes (nucleosomes) were purified by sedimentation and resedimentation through isokinetic sucrose gradients. nucleosomes isolated from [3h]thymidine-labeled cells were analyzed for dna size using both polyacrylamide gel and electron microscopic techniques. nucleosomes isolated from [14c]lysine-labeled cells were analyzed for protein content using a sodium do ... | 1977 | 911804 |
| properties of carbohydrate utilising variants of chinese hamster cells. | variants of chinese hamster ovary cells (cho-k1) have been isolated which can grow on one of the following carbohydrates: lactose, sucrose, ribose or lactate. the ribose+ clones grow at the same rate on glucose as the parental cells whereas the others grow more slowly. with the exception of one ribose+ clone all excrete lactic acid while growing on glucose; none excrete significant amounts of lactic acid while growing on the alternative energy source. wild-type cells and the variants accumulate ... | 1977 | 610885 |
| a method for the isolation of chinese hamster cell variants with an altered ability to utilise carbohydrates. | chinese hamster ovary cells (cho-k1) are able to utilise only a few carbohydrates for growth such as glucose, mannose, fructose and galactose. they do not grow on ribose, lactose, sucrose, glycerol, lactate, pyruvate, citrate, succinate, fumarate or malate nor on glycogenic or ketogenic amino acids. after mutagenesis and selection in glucose free medium supplemented with various, individual, growth substrates, we have isolated single-cell derived clones which are now able to grow on one of the f ... | 1977 | 610884 |
| induction of sister chromatid exchanges in chinese hamster cells by carcinogenic mutagens requiring metabolic activation. | 1977 | 593288 | |
| biochemical genetics of chinese hamster cell mutants with deviant purine metabolism: characterization of chinese hamster cell mutants defective in phosphoribosylpyrophosphate amidotransferase and phosphoribosylglycinamide synthetase and an examination of alternatives to the first step of purine biosynthesis. | activities of the first three enzymes in the de novo purine biosynthetic pathway have been measured in cell-free extracts of the chinese hamster ovary cell (cho-k1) and two purine-requiring auxotrophs of this cell. ade-a has been found to be defective in phosphoribosylpryophosphate (prpp) amidotransferase while ade-c has been found to be defective in glycinamide ribonucleotide (gar) synthetase. neither enzyme deficiency is due to the presence of an excess of diffusible inhibitor, and mixed extra ... | 1977 | 564086 |
| isolation of a lactic dehydrogenase-a-deficient cho-k1 mutant by nylon cloth replica plating. | a mutant chinese hamster ovary cell deficient in lactate dehydrogenase a activity has been isolated using a nonselective technique. the method uses histochemical staining to examine colonies directly for enzyme activity and nylon cloth replica plating to recover particular clones. the mutant cell has an apparent km (pyruvate to lactate) that is nearly tenfold higher than the parental cell, while its vmax has been reduced more than 80-fold. in mutant cell extracts with added porcine ldh-b enzyme, ... | 1977 | 341374 |
| selective loss of wheat germ agglutinin binding to agglutinin-resistant mutants of chinese hamster ovary cells. | the binding of 125i-labeled wheat germ agglutinin (wga) to parental and three distinct wga-resistant chinese hamster ovary cell lines possessing modified cell surface carbohydrate structures has been examined over a 10(6)-fold range of wga concentrations. the scatchard plot for wga binding to parental cells was complex and exhibited positively cooperative binding at the high affinity sites. one of the wga-resistant mutants (wgariii) was apparently not altered in its wga-binding ability compared ... | 1977 | 270740 |
| cell cycle variation associated with feeder effects in cultures of chinese hamster fibroblasts. | 1977 | 913497 | |
| effect of distamycin a on chinese hamster chromosomes. | 1977 | 71997 | |
| a quantitative assay of mutation induction at the hypoxanthine-guanine phosphoribosyl transferase locus in chinese hamster ovary cells (cho/hgprt system): development and definition of the system. | an assay is described for the measurement of mutation induction at the hypoxanthine-guanine phosphoribosyl transferase (hgprt) locus in chinese hamster ovary (cho) cells utilizing resistance to 6-thioguanine (tg). optimal selection conditions are defined for such parameters as phenotypic expression time prior to selection, and tg concentration and cell density which permits maximum mutant recovery. the nature of the tg-resistant mutants is characterized by several physiological and biochemical m ... | 1977 | 917038 |
| effect of caffeine on sister chromatid exchanges and chromosomal aberrations induced by mutagens in chinese hamster cells. | 1977 | 917034 | |
| effect of tumor promoting agents on mutation frequencies in cultured v79 chinese hamster cells. | 1977 | 917033 | |
| mutagenic and epigenetic influence of caffeine on the frequencies of uv-induced ouabain-resistant chinese hamster cells. | caffeine, given as a post-treatment to uv-irradiated chinese hamster cells in vitro, modified the frequency were increased when caffeine was added only for the dna repair and mutation fixation period. when caffeine was added after the dna repair and mutation fixation period, or immediately after dna damage and for the entire repair and selection period, mutation frequencies were reduced. a hypothesis, given to explain both results, is that caffeine, by blocking a constitutive "error-free" postre ... | 1977 | 917032 |
| forward and reverse mutations affecting the kinetics and apparent molecular weight of mammalian hgprt. | chinese hamster cells selected for resistance to 8-azaguanine following mutagenesis have hypoxanthine-guanine phosphoribosyltransferase (hgprt; e.c. 2.4.2.8) with characteristics compatible with different mutations in the structural gene for that enzyme. using immunopurification and sds-polyacrylamide electrophoresis, mutants producing antigenically active forms of the enzyme can be analyzed for changes in the molecular weight of hgprt. enzyme subunits from mutants rjk3 and rjk39 are reduced in ... | 1977 | 912745 |
| discrete electrophoretic products of mitochondrial protein synthesis in the chinese hamster ovary cell line. | mitochondrial proteins labelled with [35s]methionine for 1 h in whole chinese hamster ovary (cho) cells in the presence of cycloheximide or emetine, known inhibitors of cytosolic protein synthesis, have been enumerated and characterized by their electrophoretic mobility in sodium dodecyl sulfate slab gel electrophoresis. ten distinct electrophoretic bands were observed. the components were relatively stable during a 2 h postlabelling period. the same 10 bands were also seen with the cho cell lin ... | 1977 | 912598 |
| sensitivity of different cell lines and of different phases in the cell cycle to hyperthermia. | the sensitivity of different cell lines (chinese hamster ovary, hela, l1210, and p388) to 43 degrees was compared chinese hamster ovary and hela cells were much less temperature sensitive than were l1210 or p388 cells. this difference persisted even when hela and l1210 cells were grown in the same medium and suggested that this was an inherent difference between the cell lines. of all the cell lines, 7-day l1210 ascites, maintained by transfer in mice, were the most sensitive. the greater sensit ... | 1977 | 561655 |
| nucleolar chromatin in chinese hamster ovary cells. topographical distribution of ribosomal dna sequences and isolation of ribosomal transcription complexes. | 1977 | 913418 | |
| spontaneous lesions in chinese hamsters. | one hundred and fifty-seven chinese hamsters (cricetulus griseus) from the lovelace foundation inhalation toxicology research institute colony had pulmonary granulomas, nodular hyperplasia of the liver, granulocytic bone marrow hyperplasias and myelogenous leukemia, nephrosclerosis and uterine adenocarcinomas. these chinese hamsters had a median life span of 1 075 days. the long life span and information on naturally-occurring diseases suggest that this species might be more widely used for toxi ... | 1977 | 919235 |
| induction of thioguanine- and ouabain-resistant mutants and single-strand breaks in the dna of chinese hamster ovary cells by 3h-thymidine. | cultured chinese hamster cells were labeled with 6-3h-thymidine or 5-methyl-3h-thymidine and allowed to accumulate damage from 3h decays for various periods of time while frozen. the frequencies of cells resistant to 6-thioguanine or ouabain and the amount of dna damage (i.e., number of single-strand breaks) were determined and compared with the mutation frequencies resulting from x and ultraviolet light irradiation. whereas 3h decays and x rays made only 6-thioguanine-resistant mutants, ultravi ... | 1977 | 914028 |
| somatostatin in the pancreas, stomach and hypothalamus of the diabetic chinese hamster. | 1977 | 908469 | |
| abnormalities in pelvic visceral nerves. a basis for neurogenic bladder in the diabetic chinese hamster. | in order to determine whether bladder dysfunction and hydronephrosis in diabetic chinese hamsters are associated with nerve pathology, the pelvic visceral nerves of diabetic and normal hamsters were examined with histochemical and electron microscopic techniques. acetylcholinesterase activity was reduced in the nerves and on smooth muscle fibers in the urinary bladder of diabetic hamsters when compared to controls. depression of enzyme staining was most marked in those hamsters with the most sev ... | 1977 | 903213 |
| repair of potentially lethal damage in chinese hamster cells after x and alpha irradiation. | 1977 | 897087 | |
| distribution of uv-induced unscheduled dna synthesis in metaphase chromosomes of chinese hamster cells. | 1977 | 891651 | |
| repair following combined x-ray and heat at 41 degrees in plateau-phase mammalian cells. | plateau-phase v79 chinese hamster cells maintained at 37 degrees following x-irradiation demonstrated both sublethal damage repair and potentially lethal damage repair. when cells were kept at 41 degrees for 1 hr following irradiation, no sublethal damage repair was seen. in contrast, irradiated cells maintained at 41 degrees for 1 hr and then returned to 37 degrees were capable of repairing both sublethal and potentially lethal radiation damage; hyperthermic (41 degrees) inhibition of radiation ... | 1977 | 884682 |
| repair of the sublethal and mutational damage induced by x-rays in chinese hamster hai cells in vitro. | the ability of chinese hamster hai cells to repair damage related to cell death and mutational change induced by x-rays were examined by using a sensitive forward mutation system from prototrophic ch-hai cl 23 cells to auxotrophs. the results obtained from the split dose experiments seem to suggest that chinese hamster hai cells have the repair mechanisms for the sublethal and mutational damage induced by x-rays and that the repair mechanisms act in common for the repair of both cases of damage. | 1977 | 608187 |
| [replication of chromosomal dna in chinese hamster cells, cultivated at different temperatures]. | dna fiber autoradiography was used to measure the rate of replication and the size of replication units in chinese hamster cells cultured at 34, 37 and 39 degrees c. the average rate of dna replication per single fork is 0.6 mcm/min at 34 degrees and 0.8 mcm/min at 37 and 39 degrees. in contrast to the change in the rate of dna replication, no change was found in the size of replication units, which are more than 200 mcm at 31, 37 and 39 degrees. the change of the length of the s phase at variou ... | 1977 | 563118 |
| clonal growth of chinese hamster cell lines in protein-free media. | a protein-free synthetic medium, mcdb 301, has been developed for clonal growth of chinese hamster ovary cell lines. medium f12 was developed originally for that purpose, but later failed to support good growth without small amounts of serum protein. growth was restored by the addition of nonphysiological amounts of commercially prepared thyroxine or smaller amounts of the trace element selenium. the thyroxine preparation was shown to contain sufficient selenium to account for all of its growth- ... | 1977 | 562838 |
| chromosome loss is responsible for segregation at the hprt locus in chinese hamster cell hybrids. | the phenomenon of segregation of gene expression has been examined in intraspecific somatic cell hybrids. specifically, segregation at the hypoxanthine guanine phosphoribosyltransferase (hprt) locus has been studied in hybrids of chinese hamster cell lines. the role of chromosome segregation, or other chromosomal events has been assessed by detailed comparison of karyotypes in the 6-thioguanine resistant segregants with those of the parental hybrid lines. the results clearly demonstrate that los ... | 1977 | 562539 |
| the control of cell proliferation by preformed purines: a genetic study. i. isolation and preliminary characterization of chinese hamster lines with single or multiple defects in purine "salvage" pathways. | sublines with single or multiple defects in purine "salvage" enzymes were isolated from the chinese hamster fibroblastic line gma32 through single or successive one-step selections for resistance to purine analogs. they were examined for their ability to incorporate purine bases and nucleosides into macromolecules, for their sensitivity to growth inhibitory purines, and for their rescue by exogenous purines from deprivation imposed by metabolic inhibitors of endogenous synthesis. the results sho ... | 1977 | 199954 |
| cytochemical study of glucose-6-phosphatase in chinese hamster testis. | 1977 | 196695 | |
| 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 ... | 1977 | 21463 |
| variations in the length of s-phase related to the time cells are blocked at the g1-s interface. | the inhibition of dna synthesis with hydroxyurea or 5-fluorode-oxyuridine decreases the duration of s-phase of synchronously growing chinese hamster cultures. - the observed drug effects are discussed in relation to an alteration of programmed dna replication. | 1977 | 144048 |
| 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 ... | 1977 | 71978 |
| action of heparin on mammalian nuclei. i. differential extraction of histone h1 and cooperative removal of histones from chromatin. | heparin interacts strongly with the histone component of chromatin, forming heparin-histone complexes which resist dissociation by 0.2 m h2so4. heparin treatment of unfractionated histones isolated from nuclei of chinese hamster cells indicates that the affinities of the histone classes for heparin appear in the order from greatest to least: (h3, h4) greater than (h2a, h2b) greater than h1. however, when isolated nuclei are treated with heparin, h1 is released from the chromatin more readily tha ... | 1977 | 884118 |
| dna replication kinetics in x-irradiated chinese hamster ovary cells. | 1977 | 897075 | |
| a radioprotective effect of vitamin c observed in chinese hamster ovary cells. | vitamin c at high concentrations was found to inhibit the growth of cho clone a cells in culture. it had a radioprotective effect, giving a maximum increase in cell survival of a factor of seven under the experimental conditions used. the protective effect was mainly but not exclusively attributable to an increase in the do, the maximum increase observed being the order of 1.4. | 1977 | 890235 |
| no mutagenic effect of enflurane on cultured cells. | enflurane was tested by the 8-azaguanine system for any evidence of mutagenic effects. no significant increase in the number of mutant colonies compared with controls was found after 24 h of exposure of chinese hamster cells to 1.5-6.5% enflurane and no damaged chromosomes were seen in metaphase cells on slides. studies of inhibition of growth rate by enflurane show that in this respect its effects were similar in magnitude to other commonly used inhalation anaesthetic agents, but with regard to ... | 1977 | 889666 |
| the adhension of chinese hamster cells. i. effects of temperature, metabolic inhibitors and proteolytic dissection of cell surface macromolecules. | 1977 | 881433 | |
| the organization of repeated nucleotide sequences in the replicons of mammalian dna. | chinese hamster ovary cells were irradiated with 100-5,000 rads of x-rays and inhibition of the initiation of replicons after irradiation was demonstrated by analyzing nascent dna sedimented in alkaline sucrose gradients. the renaturation kinetics of dna synthesized during 60 min of incubation after irradiation was compared with that of dna synthesized during the 60 min after sham irradiation and with that of parental dna. nascent dna from cells whose replicon initiation was inhibited renatured ... | 1977 | 880330 |
| quantitative analysis of biological marker synthesis in tumor cell cycle. | a quantitative relationship between tumor cell number and biologic marker concentration has been investigated and characterized by the previously developed discrete-time kinetic model for the study of cell kinetics. here, this model is further expanded to cope with both cell cycle kinetics and biologic marker synthesis. a synchronized tumor-cell population is examined to determine the time course of the synthesis of markers in relation to cell cycle. the dna content distributions, measured by fl ... | 1977 | 872404 |
| effects of mercuric chloride on synchronized chinese hamster ovary cells: survival and dna replication. | chinese hamster ovary (cho) cells in vitro were treated with hgcl2 at various stages in the cell cycle and the effects of this chemical on cell survival, dna replication, and cell division were observed. in terms of survival the early g1 cells were the most sensitive to treatment, followed by late g1 and early s, while mid s and late s-g2 treated cells were the least sensitive. treatment with hgcl2 also resulted in reduced rates of dna replication and delays in cell division. the early g1 treate ... | 1977 | 560920 |
| the response of chinese hamster ovary cells to fast-neutron radiotherapy beams. ii. sublethal and potentially lethal damage recovery capabilities. | 1977 | 408868 | |
| adhesion of phospholipid vesicles to chinese hamster fibroblasts. role of cell surface proteins. | the adhesion of artificially generated lipid membrane vesicles to chinese hamster v79 fibroblasts in suspension was used as a model system for studying membrane interactions. below their gel-liquid crystalline phase transition temperature, vesicles comprised of dipalmitoyl lecithin (dpl) or dimyristoyl lecithin (dml) absorbed to the surfaces of edta- dissociated cells. these adherent vesicles could not be removed by repeated washings of the treated cells but could be released into the medium by ... | 1977 | 407233 |
| transfer of codominant markers by isolated metaphase chromosomes in chinese hamster ovary cells. | codominant mutations to methotrexate and ouabain resistance in chinese hamster ovary cells can be transferred to recipient chinese hamster ovary cells by isolated metaphase chromosomes. for methotrexate, both the structural change and the increased activity of dihydrofolate reductase (5,6,7,8-tetrahydrofolate:nadp+ oxidoreductase ec 1.5.1.3), characteristic of the donor cells, are observed in the transferents (cells that carry and express functions derived by chromosome transfer). the transferen ... | 1977 | 269408 |
| 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 ... | 1977 | 70463 |
| mutants of cho cells resistant to the protein synthesis inhibitors, cryptopleurine and tylocrebrine: genetic and biochemical evidence for common site of action of emetine, cryptopleurine, tylocrebine, and tubulosine. | stable mutants resistant to the protein synthesis inhibitors cryptopleurine and tylocrebine can be isolated in chinese hamster ovary (cho) cells, in a single step. the frequency of occurrence of cryptopleurine (cryr) and tylocrebrine (tylr) resistant mutants in normal and mutagenized cell populations is similar to that observed for emetine resistant (emtr) mutants. the cryr, tylr, and emtr mutants exhibit strikingly similar cross-resistance to the three drugs used for selection, to tubulosine an ... | 1977 | 560858 |
| a reduction in the degree of h4 acetylation during mitosis in chinese hamster cells. | 1977 | 883971 | |
| chinese hamster cell mutant with defective mitochondrial protein synthesis. | 1977 | 196202 | |
| the recovery of normal dna replication kinetics in ultraviolet-irradiated chinese hamster cells. | 1977 | 895752 |