Search Results
Results 351 - 400 of 1497
< 3 4 5 6 7 8 9 10 11 12 13 >
Zhou H - - 1999
The mutagenicity of 4-methylnitrosamine-1-3-pyridyl-1-butanone (NNK), either alone or in combination with low dose alpha particle irradiation, was examined using the human-hamster hybrid (A(L)) cell assay. NNK induced a dose-dependent toxicity in A(L) cells. In combination with a 25 cGy dose of alpha particles, the induced survival fraction fell within the ...
Yoshitatsu M - - 1999
The cell membrane-bound forms of mini-factor H with 1-4 short consensus repeats (fH-PI) and factor I (fI-PI) were constructed. Swine endothelial cell (SEC) lines and Chinese hamster ovary (CHO) cell expressing fH-PI or fI-PI were established and confirmed by flow cytometry. The cell lysate of the SEC line expressing fH-PI ...
Knasmüller S - - 1999
In order to study the mutagenic effects of heterocyclic aromatic amines (HAAs) in cells of human origin, five compounds, namely 2-amino-3-methyl-imidazo[4,5-f]quinoline (IQ), 2-amino-3, 4-dimethyl-imidazo[4,5-f]quinoline (MeIQ), 2-amino-3, 8-dimethyl-imidazo[4,5-f]quinoxaline (MeIQx), the pyridoimidazo derivative 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1), were tested in micronucleus (MN) assays with a human derived hepatoma (HepG2) cell line. ...
Binley K M - - 1999
PRS3 is one of a family of five genes encoding phosphoribosylpyrophosphate synthetase, an enzyme which catalyses the first step in a variety of biosynthetic pathways, including purine and pyrimidine biosynthesis. We report here that prs3Delta mutants have a number of phenotypes that suggest an unexpected role for PRS3 in linking ...
Berntsson P S - - 1999
Cells in mitosis were seeded immediately after being harvested by the mitotic shake off technique from a culture of exponentially growing Chinese hamster ovary cells. At 2, 5, 7, 10, and 12 h after seeding, cycloheximide was added. Cells were sampled at various times after cycloheximide addition and the ornithine ...
Masuda S - - 1999
In the central nervous system, astrocytes produce erythropoietin (Epo) and neurons express its receptor. To examine whether or not the brain Epo protects the in vitro cultured neurons from glutamate-induced cell death, we established rat astrocyte cell lines containing the plasmid for production of recombinant rat Epo. Epo partially purified ...
Heth G - - 1999
In this investigation, the authors used habituation techniques to explore similarities and differences in the qualities of individual odors from hamsters. In Experiment 1, male Turkish hamsters (Mesocricetus brandti) treated flank-gland odors of 2 males from 1 litter as similar compared with the odor of a male from another litter, ...
Kuge O - - 1999
Phosphatidylserine (PtdSer) in Chinese hamster ovary (CHO) cells is synthesized through the action of PtdSer synthase (PSS) I and II, which catalyzes the exchange of L-serine with the base moiety of phosphatidylcholine and phosphatidylethanolamine, respectively. The PtdSer synthesis in a CHO cell mutant, PSA-3, which lacks PSS I but has ...
Butters T D - - 1999
Heterologous gene expression in either (1) the glycosylation-defective, mutant Chinese hamster ovary cell line, Lec3.2.8.1, or (2) the presence of the alpha-glucosidase inhibitor, N-butyldeoxynojirimycin facilitates the trimming of N-linked glycans of glycoproteins to single N-acetylglucosamine (GlcNAc) residues with endoglycosidase H (endo H). Both approaches are somewhat inefficient, however, with as ...
Sato Y - - 1999
Recent results on cell killing by microbeams were analysed using three parameters (k, L, L1), where k is the mean number of lethal particles per cell nucleus, L [keV/microm] is the track-average LET (linear energy transfer) in cells, and L1 [keV/microm] is a critical value for inducing lethal damage by ...
Barbour S E - - 1999
Phosphatidylcholine (PtdCho) is the most abundant phospholipid in mammalian cell membranes and is essential for cell viability. The levels of this lipid must be tightly controlled to maintain homeostasis. Therefore, changes in the rate of PtdCho synthesis are generally balanced by changes in PtdCho catabolism and vice versa. It is ...
Sanfeliu A - - 1999
The effect of glutamine depletion on the death of attached Chinese hamster ovary (CHO) cells was investigated. Experiments were performed using an anchorage dependent CHO cell line expressing gamma-IFN and a second cell line obtained by transfection of that cell line with the human bcl-2 (hbcl-2). Either cell line could ...
Matsuoka A - - 1999
In our previous in vitro micronucleus (MN) study, we showed that aneugens, in addition to inducing micronuclei, induce a higher frequency of polynuclear (PN) and mitotic (M) cells than clastogens. We hypothesized that the frequency of PN and M cells induced can distinguish aneugens from clastogens. To test the hypothesis, ...
Cai Y - - 1999
Cyclophosphamide is used to treat a wide range of human malignancies. However, it is also a known carcinogen associated with induction of therapy-related leukemia and bladder cancer. The DNA repair protein, O6-alkylguanine-DNA alkyltransferase (AGT), protects cells from the toxic and mutagenic effects of O6-alkylating agents. We report here the contribution ...
Heine H - - 1999
Toll-like receptor (TLR) 2 and TLR4 have been implicated in the responses of cells to LPS (endotoxin). CD14-transfected Chinese hamster ovary (CHO)-K1 fibroblasts (CHO/CD14) are exquisitely sensitive to endotoxin. Sequence analysis of CHO-TLR2, compared with human and mouse TLR2, revealed a single base pair deletion. This frameshift mutation resulted in ...
Chang C C - - 1999
Zellweger syndrome and related disorders represent a group of lethal, genetically heterogeneous diseases. These peroxisome biogenesis disorders (PBDs) are characterized by defective peroxisomal matrix protein import and comprise at least 10 complementation groups. The genes defective in seven of these groups and more than 90% of PBD patients are now ...
Ghaedi K - - 1999
We isolated peroxisome biogenesis-defective mutants from rat PEX2-transformed Chinese hamster ovary (CHO) cells, using the 9-(1'-pyrene)nonanol/ultraviolet method. A total of 18 mutant cell clones showing cytosolic localization of catalase were isolated. By complementation group (CG) analysis by means of PEX cDNA transfection and cell fusion, cell mutants, ZP124 and ZP126, ...
Ghaedi K - - 1999
We developed an improved method for isolation of peroxisome biogenesis-defective somatic animal cell mutants, using a combination of green fluorescent protein (GFP) expression and the 9-(1'-pyrene)nonanol/ultraviolet (P9OH/UV) selection method. We used TKaG1 and TKaG2 cells, the wild-type Chinese hamster ovary (CHO) cells, CHO-K1, that had been stably transfected with cDNAs ...
Bol S A - - 1999
The butylating agent N-n-butyl-N-nitrosourea (BNU) was employed to study the role of nucleotide excision repair (NER) in protecting mammalian cells against the genotoxic effects of monofunctional alkylating agents. The direct acting agent BNU was found to be mutagenic in normal and XPA mouse splenocytes after a single i.p. treatment in ...
Silva M J - - 1999
Sister chromatid exchanges (SCEs) were scored in lymphocytes of nine high-performance pilots of alphajet aircrafts and of ten control individuals from the same air base. Statistical analysis of the mean SCE count per cell in the total number of cells analyzed as well as in those having 12 or more ...
Saito M - - 1999
The influence of peroxisomal dysfunction on glycosphingolipid metabolism was investigated using mutant Chinese hamster ovary (CHO) cells (Z65) with defective assembly of the peroxisomal membranes. In accordance with previous observations, the concentration of very long chain fatty acid (C24:0) was shown to be higher in Z65 cells than in control ...
Chidambaram N - - 1999
CD38 is a 46-kDa type II transmembrane glycoprotein that catalyses the synthesis of cyclic ADP-ribose (cADPR) from NAD+. cADPR is a second messenger known to regulate intracellular Ca2+-induced Ca2+-release (CICR). A recent study has revealed that CD38 in Namalwa B cells undergoes internalization upon exposure to external NAD+. In this ...
Marini A - - 1999
The frequency of reversion in a histidine-requiring mutant of Saccharomyces cerevisiae increases about ten-fold in stationary cells during histidine starvation. Histidine starvation enhances a similar frequency of reversion in a tryptophan-requiring mutant. Starvation, therefore, enhances mutation frequencies in a non-adaptive manner. The base analogue 6-N-hydroxylaminopurine (HAP) added prior to plating ...
Okayasu R - - 1999
Cytotoxicity and mutagenicity of tremolite, erionite and the man-made ceramic (RCF-1) fibre were studied using the human-hamster hybrid A(L) cells. Results from these fibres were compared with those of UICC Rhodesian chrysotile fibres. The A(L) cell mutation assay, based on the S1 gene marker located on human chromosome 11, the ...
Fukasawa M - - 1999
LY-A strain is a Chinese hamster ovary cell mutant resistant to sphingomyelin (SM)-directed cytolysin and has a defect in de novo SM synthesis. Metabolic labeling experiments with radioactive serine, sphingosine, and choline showed that LY-A cells were defective in synthesis of SM from these precursors, but not syntheses of ceramide ...
Kalweit S - - 1999
The in vitro micronucleus test (MNT) is a useful assay for the detection of mutagenic events on both the chromosomal and the genomic level. The main disadvantage for introducing the in vitro MNT into official test guidelines seems to be the disparity of existing protocols. To contribute to the aim ...
Yamazaki S - - 1999
Cell bodies staining positively for serotonin (5HT) appear in the suprachiasmatic nuclei (SCN) of hamsters that have been held in constant darkness (DD) for several months but are otherwise untreated. No such cell bodies are found in the SCN of animals that have been bilaterally enucleated for the same amount ...
Tal S - - 1999
Site-directed psbA mutants at the tyrosine Y112 position have been generated in Synechocystis PCC6803 cells. The mutation Y112F does not affect photosystem II (PSII) activity as compared with control 4 delta 1K cells. However, the Y112L mutant exhibits a photosynthetically impaired phenotype. PSII activity is not detectable in this mutant ...
Chang K H - - 1999
Sodium butyrate (NaBu) is known to enhance the rate of biosynthesis of recombinant proteins in Chinese hamster ovary cells (CHO). Here we demonstrate that supplementation with NaBu during rapid growth brings about abrupt death of the cells. The death of the cells is due to apoptosis, as assessed by intranucleosomal ...
O'Rear J L - - 1999
Parental Chinese hamster ovary (CHO) cells were mutagenized and subjected first to a mannose suicide selection technique and second to a screen of individual colonies grown on polyester discs for reduced mannose incorporation into protein. The incorporation of radioactivity for the selection and the screen was conducted at 41.5 degrees ...
Plewa M J - - 1999
Commercial products of agronomic crop plants may become a reliable and inexpensive source of phytonutrients, such as antimutagenic food supplements. We previously demonstrated that PCC, an ethanol extract of a commercial soybean processing by-product, was able to repress induced genomic DNA damage, whole cell clastogenicity, and point mutation in mammalian ...
Erexson G L - - 1999
We have established and characterized primary mouse and rat cell strains for studies designed to complement in vivo gene mutation assays using the Big Blue(R) mouse or rat. Primary fibroblast cell strains, designated BBM1 and BBR1, were derived from a transgenic male Big Blue(R) B6C3F1 mouse and from a male ...
Jones N A - - 1999
Flow cytometry allows rapid multiparameter analyses of individual cells. Cells are illuminated with incident laser light of a specific wavelength. Resultant light scatter signals and fluorescence-emission signals from fluorochromes contained at the surface of the cell or within it are detected by an array of photomultiplier tubes. For example, fluorochrome-conjugated ...
Scarselli M - - 1999
Apomorphine is a potent non selective agonist at the D1 and D2 dopamine receptors acting both pre- and post-synaptically. In this report we describe a novel function of apomorphine, independent from its dopaminergic activity. Apomorphine inhibits Chinese hamster ovary (CHO)-K1 cell proliferation in a dose-dependent manner. The EC50 of apomorphine-induced ...
Stamato T D - - 1998
PURPOSE: To review studies of mutagen-induced colony sectoring which demonstrate that UV light and EMS produce delayed mutational events in Chinese hamster ovary cells. METHODS AND RESULTS: Since the late 1940s, it has been known that the treatment of a single bacterial or yeast cell with mutagenic agents produces complete ...
Sasai K - - 1998
Leukemia inhibitory factor (LIF) is a pluripotent growth factor which acts in various cell systems. LIF is a glycoprotein containing six putative N-glycosylation sites. We established Chinese hamster ovary (CHO) cell lines to evaluate the biological roles of the N-glycosylation in rat LIF (rLIF). The bioactivity of rLIF was evaluated ...
Zanghi J A - - 1998
Ammonia is a major concern in biotechnology because it often limits recombinant protein production by animal cells. Conditions, such as ammonia accumulation, in large-scale production systems can parallel those that develop within fast-growing solid tumors such as small cell lung cancer (SCLC). Ammonia's specific inhibition of the sialylation of secreted ...
Erexson G L - - 1998
The transgenic Big Blue Rat2 and Big Blue mouse embryonic fibroblast cell lines have been used to complement the transgenic Big Blue rat and mouse in vivo mutagenesis assays. However, limited information is available regarding the karyology of these cell lines. Therefore, we have characterized the ploidy, mitotic index, spontaneous ...
Vreeswijk M P - - 1998
Cells from Cockayne's syndrome (CS) patients are hypersensitive to the cytotoxic effects of UV-irradiation and are defective in transcription coupled repair (TCR). We have examined the mutagenic consequences of impaired TCR in the Chinese hamster cell line UV61, the rodent homologue of CS complementation group B. Analysis of the two ...
Kaiden A - - 1998
B211, a glycosylation mutant isolated from Chinese hamster ovary cells, synthesizes 10- to 15-fold less Glc3Man9GlcNAc2-P-P-lipid, the substrate used by the oligosaccharide transferase in the synthesis of asparagine-linked glycoproteins. B211 cells are also 10- to 15-fold deficient in the glucosylation of oligosaccharide-lipid. Despite these properties, protein glycosylation in B211 cells ...
Kojima N - - 1998
To determine the effect of alpha1,6-linked fucose modification of N-glycans on the expression of polysialic acids (PSAs), the expression of PSAs in a fucose-lacking mutant of Chinese hamster ovary (CHO) cells, Lec13, was compared with that in CHO K1 cells. PSA synthase activity in these cells and the antennary structures ...
Hashiguchi K - - 1998
The partial nucleotide sequences of mitochondrial 16S rRNA gene were analyzed in five rodent cell lines, prior to the analysis of mutation spectrum in the gene. Total DNA was isolated from V79 and CHO-K1 cell lines from Chinese hamster and murine cell lines, Balb Y SV and PCC4 AG Cap, ...
Bolzán A D - - 1998
The effects of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and the hydroxyl radical scavenger mannitol (MAN) on the clastogenesis induced by STZ in Chinese hamster ovary (CHO) and mosquito cells were investigated. The addition of liposome-entrapped SOD, CAT and MAN to both cell lines caused a significant decrease ...
Loupart M L - - 1998
A 4 Mb human mini-chromosome, DeltaDelta2, was transferred from Chinese hamster ovary (CHO) cells into a mouse L cell line. The mini-chromosome could be transferred intact into the L cells, with 112/119 clones maintaining a mini-chromosome of the same size as the original. Ten clones were grown for 30 days ...
Tesfai Y - - 1998
The interaction of multiple carcinogens on human cells has not been extensively examined. This study reports the results of experiments in which normal human fibroblasts were exposed to both benzo[a]pyrene diolepoxide (BPDE) and potassium dichromate. The effect of four different treatment protocols on the cloning ability of the cells and ...
Ikushima T - - 1998
Treatments of Chinese hamster V79 cells during one cell cycle with a new type of topoisomerase II inhibitor, ICRF-193, which does not accumulate cleavable topoisomerase-DNA complexes induced both chromosome- and chromatid-type aberrations with high frequencies. Furthermore, ICRF-193 synergistically enhanced the yield of UVB-induced chromatid-type aberrations, chromatid exchanges in particular. Treated ...
Lin S - - 1998
The mechanism by which planktonic marine cyanobacteria of the genus Trichodesmium fix N2 aerobically during photosynthesis without heterocysts is unknown. As an aid in understanding how these species protect nitrogenase, we have developed an immunofluorescence technique coupled to light microscopy (IF-LM) with which intact cyanobacteria can be immunolabeled and the ...
Brezden C B - - 1998
The 2-nitroimidazoles have been used clinically to radiosensitize resistant hypoxic cells, but a dose-limiting peripheral neuropathy has restricted their therapeutic effectiveness. A model compound, 1-methyl-2-nitroimidazole (INO2), was used to investigate the possible role of oxidative stress in this normal tissue toxicity. Chinese hamster ovary (CHO) cells were 10-15 times more ...
Azarani A - - 1998
Endothelin-converting enzyme (ECE) is a phosphoramidon-sensitive membrane-bound metalloprotease responsible for the conversion of big-endothelins into endothelins [Yanagisawa, Kurihara, Kimura, Tomobe, Kobayashi, Mitsui, Yazaki, Goto and Masaki (1988) Nature (London) 332, 411-415]. Several distinct isoforms of ECE have been cloned and identified. ECE-1a, b and c have the same ectodomain and ...
Saito K - - 1998
Phosphatidylserine (PS) in mammalian cells is synthesized through the exchange of free L-serine with the base moiety of phosphatidylcholine or phosphatidylethanolamine (PE). The serine base exchange in Chinese hamster ovary (CHO) cells is catalyzed by at least two enzymes, PS synthase (PSS) I and II. A PSS I-lacking mutant of ...
< 3 4 5 6 7 8 9 10 11 12 13 >