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Results 401 - 450 of 1502
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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 ...
Wang T C - - 1998
N-Methylcarbamate esters are an important group of insecticides. They have lower acute toxicity to vertebrates than organophosphates, although their genotoxicity has not been adequately studied. Here we investigate the cytotoxicity and genotoxicity of N-methylcarbamate insecticides and their N-nitroso derivatives in Chinese hamster V79 cells, using the hprt locus as a ...
Nagan N - - 1998
We have developed a two-step selection protocol to generate a population of Chinese hamster ovary (CHO) cell variants that are plasmalogen-deficient, but contain intact, functional peroxisomes (plasmalogen-/peroxisome+). This involved sequential exposures of a mutagenized cell population to photodynamic damage by using two different pyrene-labelled sensors, 9-(1'-pyrene)nonanol and 12-(1'-pyrene)dodecanoic acid. By ...
Lu P J - - 1998
Titanium dioxide (TiO2) has color properties of extreme whiteness and brightness, is relatively inexpensive, and is extensively used as a white pigment in a variety of materials. TiO2, an effective blocker of ultraviolet light, is frequently added to sunscreens and cosmetic creams. However, the genotoxicity of TiO2 remains to be ...
Varga E V - - 1998
The identification of adenylyl cyclase isoenzymes in mammalian host cells is important for the interpretation of data obtained from cell lines heterologously expressing G-protein coupled receptors. Reverse transcriptase polymerase chain reaction (RT-PCR) was used to amplify adenylyl cyclase cDNAs from Chinese hamster ovary (CHO) and mouse fibroblast (B82) cells. The ...
Priola S A - - 1998
Inherited forms of the human transmissible spongiform encephalopathy Creutzfeldt-Jakob disease (CJD) have been associated with mutations in the normal soluble, protease-sensitive form of the host prion protein (PrP-sen). Normal PrP protein contains five copies of a repeating eight-amino acid region, and PrP molecules with six or more copies of this ...
Walderich B - - 1998
Blastocystis hominis isolates from asymptomatic carriers and symptomatic patients were cultured in vitro, purified from the co-cultivated bacterial flora and tested for cytopathic effects on monolayers of Chinese Hamster Ovary (CHO) cells and Adeno Carcinoma HT29 cells. In the case of the CHO cells, living B. hominis cells and B. ...
Tzung T Y - - 1998
PURPOSE: To characterize further the contribution of the DNA-PK-dependent dsb repair pathway in mammalian cells. MATERIALS AND METHODS: The efficiency and fidelity of the joining of linear plasmids by DNA-PKcs-defective mouse cells (SCID) and Ku80-defective Chinese hamster ovary cells (xrs-6) was measured using either linear or circular replicating shuttle vector ...
Kuge O - - 1998
Phosphatidylserine (PtdSer) synthesis in Chinese hamster ovary (CHO) cells occurs through the exchange of L-serine with the base moiety of phosphatidylcholine or phosphatidylethanolamine. The synthesis is depressed on the addition of PtdSer to the culture medium. A CHO cell mutant named mutant 29, whose PtdSer biosynthesis is highly resistant to ...
Mitaroff A - - 1998
Chinese hamster ovary (CHO) cells and thermoluminescent detectors (TLD-700) were used for physical and biological verification of heavy ion treatment planning. Experiments were performed in a cylindrical water phantom, in some cases with lung and bone equivalent material in front of the target volume. The results confirm the possibility of ...
Taets C - - 1998
Pesticide contamination of drinking water supplies has increased over the past decade. A major concern is how exposure to combinations of low levels of pesticides, especially herbicides, could affect public health. Flow cytometric analysis was performed to determine the clastogenic potential of herbicide interaction on Chinese hamster ovary (CHO) cells. ...
Stone S J - - 1998
In eukaryotic cells, phosphatidylserine (PtdSer) is synthesized by two distinct synthases on the endoplasmic reticulum by a base-exchange reaction in which the polar head-group of an existing phospholipid is replaced with serine. We report the cloning and expression of a cDNA for mouse liver PtdSer synthase-1. The deduced protein sequence ...
Avramoglu R K - - 1998
The low density lipoprotein receptor-related protein (LRP) is responsible for the clearance of several physiological ligands including a complex of proteinase and alpha2-macroglobulin (alpha2M) and for the entrance of Pseudomonas exotoxin A (PEA) into cells. We have prepared expression plasmids for the full-length chicken LRP (designated LRP100) and two intermediates ...
Velasco J A - - 1998
We reported previously that expression of the cph oncogene in Syrian hamster and mouse cells leads to the secretion of a polypeptide factor or factors structurally and functionally related to neu differentiation factor (NDF) and the establishment of an autocrine loop mediated through the simultaneous overexpression of the erbB4 receptor. ...
Sburlati A R - - 1998
Genetic engineering of oligosaccharide biosynthesis pathways in mammalian cells makes possible generation of new recombinant glycoproteins of potential importance in the biopharmaceutical industry. Most prior investigations of glycosylation engineering of secreted heterologous glycoproteins involve terminal steps of oligosaccharide biosynthesis. In particular, increasing the frequency of bisected structures within the glycoform ...
Zhu W - - 1998
We have examined whether cells with replication error-positive (RER+) and -negative phenotype (RER ) respond differently to the mutagen MNNG, employing three RER+ and two RER- human cell lines. Cells were treated with several concentrations of MNNG, and HPRT mutants were selected phenotypically by their growth in the presence of ...
Glatt H - - 1998
Sulfation is a common final step in the biotransformation of xenobiotics and is traditionally associated with inactivation. However, the sulfate group is electron-withdrawing and may be cleaved off heterolytically in some molecules leading to electrophilic cations which may form adducts with DNA and other important cellular structures. Since endogenous sulfotransferases ...
Hong S T - - 1998
In the present study, we examined the effects of hemin on the mutagenicity of 6-sulfooxymethylbenzo[a]pyrene (SMBP) in Salmonella typhimurium TA98 and Chinese hamster lung fibroblast (V79) cells. The compound was tested for the possible chemoprotective activity against mutagenesis induced by SMBP and its precursor, 6-hydroxymethylbenzo[a]pyrene (HMBP), activated by hepatic cytosol ...
Papandreou M J - - 1998
The influence of HIV Env glycosylation on the conformation of the third variable domain (V3) of Env was studied by both deglycosylation of mature Env and the use of Env produced by recombinant systems in which alpha-glucosidase activity was inhibited by either deoxynojirimycin (DNM) or mutation. Selective deglycosylation affected anti-V3 ...
Dillon C T - - 1998
The genotoxicity of Cr(V) complexes in mammalian cells (V79 Chinese hamster lung cells) has been studied for the first time using the in vitro micronucleus assay. Two complexes were investigated, [CrO(ehba)2]-, which undergoes ligand-exchange and disproportionation reactions in the cell growth medium, and [CrO(mampa)]-, which is chemically inert in the ...
Fantini C - - 1998
The correlation between etoposide (VP-16) cytotoxicity and the induction of sister chromatid exchanges (SCEs) suggested that the promotion of DNA recombination events may be crucial for the activity of antitopoisomerase drugs. To further evaluate this hypothesis, we investigated the correlation between VP-16 induction of SCEs, chromosomal aberrations and cell cycle ...
Melia S M - - 1998
Genetic analysis of regulated exocytosis can be accomplished in ciliates, since mutants defective in stimulus-dependent secretion of dense-core vesicles can be identified. In Tetrahymena thermophila, secretion in wild-type cells can result in their encapsulation by the proteins released from vesicle cores. Cells with defects in secretion were isolated from mutagenized ...
Waldren C - - 1998
We measured the number of mutants and the kinds of mutations induced by 137Cs-gamma and by HZE-Fe (56Fe [600 MeV/amu, LET = 190 KeV/micrometer) in standard AL human hamster hybrid cells and in a new variant hybrid, AL-179. We found that HZE-Fe was more mutagenic than 137Cs-gamma per unit dose ...
Abe H - - 1998
The effects of steroid hormones (oestradiol and progesterone) on the appearance of a golden hamster oviduct-specific glycoprotein (GHOGP) in the epithelium of the oviduct of the newborn golden hamster were investigated by immunoblotting and immunohistochemical staining with a GHOGP-specific monoclonal antibody. Newborn golden hamsters (1.5 days old) were injected daily ...
Saranko C J - - 1998
1,3-Butadiene (BD) is a genotoxic carcinogen that is bioactivated to at least two mutagenic metabolites, 1,2-epoxybutene (EB) and 1,2:3,4-diepoxybutane (DEB). We investigated the mutagenicity and induction of micronuclei by DEB in vitro in Rat2 lambda/lacI transgenic fibroblasts (Big Blue Rat2 cells, Stratagene, LaJolla, CA). Assays for mutagenicity and micronuclei induction ...
Forman M S - - 1997
Expression of the Swedish DeltaNL mutation in the beta-amyloid precursor protein (APPDeltaNL) dramatically increases Abeta generation in nonneuronal cell lines, although it is unclear whether intracellular levels of beta-amyloid (Abeta) are also elevated after APPDeltaNL expression. Furthermore, the effects of expressing APPDeltaNL in neurons on the production and secretion of ...
Omata W - - 1997
We have investigated the subcellular distribution of GLUT4 by immunofluorescence microscopy after transfection with wild-type or mutant dynamin cDNA into Chinese hamster ovary cells expressing insulin receptor and GLUT4. In the basal state, GLUT4 was distributed exclusively within the cells in the cells overexpressing wild-type dynamin (CHOIR-GLUT4-WT) but was located ...
Ding S - - 1997
Expression of recombinant cytochrome P450s (P450s) in mammalian cells has been used as a powerful tool to study these enzymes. However, the activity of CYP3A4 expressed in several stable mammalian cell lines was much lower than native enzyme in human liver. The low level of recombinant CYP3A4 may have been ...
Liu C - - 1997
The circadian clock in the suprachiasmatic nuclei is composed of multiple, single-cell circadian oscillators (clock cells). We now test the hypothesis that the circadian period in behavior is determined by the mean period that arises from the coupling of clock cells with diverse circadian periods. For these studies, we monitored ...
Best C J - - 1997
In this study, the effect of thymidine kinase deficiency on the responses of the human lymphoblastoid cell line Raji to methyl methanesulphonate and mitomycin C was investigated. Mutagen sensitivity was measured in terms of cell survival and mutation to hypoxanthine-guanine phosphoribosyltransferase deficiency. Thymidine kinase-deficient Raji cells showed decreased survival and ...
Merz G S - - 1997
To define the cellular processing of human cystatin C as well as to lay the groundwork for investigating its contribution to lcelandic Hereditary Cerebral Hemorrhage with Amyloidosis (HCHWA-I), we have characterized the trafficking, secretion, and extracellular fate of human cystatin C in transfected Chinese hamster ovary (CHO) cells. It is ...
Kaina B - - 1997
O6-Methylguanine (O6-MeG) is induced in DNA by methylating environmental carcinogens and various cytostatic drugs. It is repaired by O6-methylguanine-DNA methyltransferase (MGMT). If not repaired prior to replication, the lesion generates gene mutations and leads to cell death, sister chromatid exchanges (SCEs), chromosomal aberrations and malignant transformation. To address the question ...
Munzert E - - 1997
Chinese hamster ovary (CHO) cells producing the recombinant glycoprotein human antithrombin III (rhAT III) were batch cultivated in a 20-L bioreactor for 13 days. Neuraminidase activity in cell-free supernatant was monitored during cultivation and free sialic acid was determined by HPLC. Neu5Acalpha(2-->3)Gal-specific Maackia amurensis and Galbeta(1-->4)GlcNAc-specific Datura stramonium agglutinin were ...
Johnston P J - - 1997
The micronucleus assay holds promise as a method for determining clastogenic effects of particular agents and for examining relative sensitivities of eukaryotic cells to such clastogens. In the following work, a detailed examination of the induction of micronuclei in radio-resistant Chinese hamster ovary fibroblasts (CHO-K1) and the DNA double-strand break ...
Hadnagy W - - 1997
A complex chemical mixture of heavy oil (Z1003), composed of polycyclic aromatic hydrocarbons (PAHs) and aza-heterocyclic compounds (AHCs), has been analysed for its ability to induce cell division disturbances on Chinese hamster lung cell line V79. In addition to the complex chemical mixture (Z1003), separated fractions of PAHs and AHCs ...
Banfalvi G - - 1997
To strengthen the causal association between repair and replicative DNA synthesis, we have simultaneously measured the two types of DNA synthesis in a cell cycle-dependent manner. Synchrony was obtained by counterflow centrifugal elutriation of logarithmic-phase Chinese hamster ovary (CHO) cells kept in suspension cultures. A comparison of cell cycle profiles ...
James P F - - 1997
Using tritium suicide, we have isolated a variant of the Chinese hamster ovary cell line, CHO-K1, that is deficient in long-chain fatty alcohol:NAD+ oxidoreductase (FAO; EC 1.1.1.192). Specifically, it was the fatty aldehyde dehydrogenase component that was affected. The enzymatic deficiency found in this mutant strain, designated FAA. K1A, was ...
Auer H - - 1997
The genotoxic properties of 2',2'-difluorodeoxycytidine (dFdC) were characterised using diploid, mortal low-passage fibroblasts (LPF cells) and the spontaneously transformed fibroblast cell line V79. In both cell types, incorporation of dFdC into the DNA led to an increase of DNA single-strand breaks evaluated by an in situ nick translation assay and ...
Kuge O - - 1997
Phosphatidylserine (PtdSer) in mammalian cells is synthesized through an exchange of free L-serine for the base moiety of pre-existing phospholipids. Studies on PtdSer biosynthesis in Chinese hamster ovary (CHO) cells have suggested that the serine base-exchange is catalyzed by at least two different enzymes; one, named PtdSer synthase I (PSS ...
Kyossev Z N - - 1997
11Beta-hydroxysteroid dehydrogenase (11beta-HSD) catalyzes the oxidation of cortisol and corticosterone to cortisone and 11-dehydrocorticosterone, respectively. NAD-dependent 11beta-HSD is expressed at high levels in the distal nephron and contributes to mineralocorticoid specificity in that region. The present studies determined whether N-glycosylation is necessary for the activity of NAD-dependent 11beta-HSD (11beta-HSD2). First, ...
Yadollahi-Farsani M - - 1997
Deficiency of the enzyme adenine phosphoribosyltransferase (APRT) has been associated with hypersensitivity to the mutagenic effects of ethyl methanesulphonate (EMS) and 254 nm ultraviolet (UV) radiation in clone 707 of Friend mouse erythroleukaemia (FEL) cells. The molecular nature of spontaneous EMS- and UV-induced mutations in the coding region of hypoxanthine-guanine ...
Brar B - - 1997
The mouse neuroblastoma cell line (Neuro 2 A) has been shown to contain the mRNA of a prohormone converting enzyme, PC2. The Chinese hamster ovary cell line (CHO) does not express PC2 mRNA, but is thought to contain the ubiquitous protease, furin. The enzyme(s) responsible for releasing corticotrophin-releasing hormone (CRH) ...
Steen A M - - 1997
1,3-Butadiene (BD) is an indirect-acting mutagen that is bioactivated in laboratory animals to at least two mutagenic metabolites, 1,2-expoxy-3-butene (EB) and 1,2,3,4-diepoxybutane (DEB). In the present study, the cytotoxicity, mutagenicity and mutational spectrum at hprt were determined after EB-exposure of human TK6 lymphoblastoid cells (TK6 cells). EB was cytotoxic at ...
Ponzanelli I - - 1997
We employed the three-way differential staining technique (TWD), which allows SCEs to be distinguished on a per generation basis by scoring third metaphases (M3), in order to study the spontaneous levels of SCEs in normal and high frequency cells (HFCs) that occurred in the first (S1), second (S2) and third ...
Tateishi S - - 1997
We isolated mutants of Chinese hamster ovary cells that exhibit excessive apoptosis after serum deprivation. In the medium containing 10% serum, the growth rates of the mutants were 1.4 to 1.5-fold faster than those of wild-type cells. Whereas the cell cycle of wild-type cells was arrested at the G1 phase ...
Wu J J Department of Pathophysiology and Laboratory of Medical Molecular Biology, Zhejiang Medical University, Hangzhou - - 1997
With specific designed primers, CYP2B6 and CYP1A1 cDNA were generated by reverse transcription-polymerase chain reaction(RT-PCR) technique performed on total RNAs isolated from human liver and 3-methylcholanthrene(3-MC) induced human amnion FL cells. Cell lines (CHL-2B6 and CHL-1A1) capable of expressing human cytochrome P450(CYP)2B6 and 1A1 were established after transfection of corresponding ...
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