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Sample records for chromatid exchange induced

  1. SISTER CHROMATID EXCHANGES IN MAMMALIAN MEIOTIC CHROMOSOMES

    EPA Science Inventory

    Very little is known about sister chromatid exchanges (SCEs) in meiotic cells--only that they occur (1) and reveal frequency and distribution patterns apparently unaffected by cross-over (CO) exchange conditions in those cells; (2) unfortunately, the number of studies from which ...

  2. How-to-Do-It: Demonstrating Sister Chromatid Exchanges.

    ERIC Educational Resources Information Center

    Dye, Frank J.

    1988-01-01

    Outlines procedures for demonstrating and preparing a permanent slide of sister chromatid exchanges and recombination events between the two chromatids of a single chromosome. Provides the name of an additional resource for making preparations of exchanges. (RT)

  3. Influence of retinol on carcinogen-induced sister chromatid exchangers and chromosome aberrations in V79 cells

    SciTech Connect

    Qin, S.; Batt, T.; Huang, C.C.

    1985-01-01

    The influence of retinol (Rol) on sister chromatid exchangers (SCE) in V79 cells induced by six indirect and two direct carcinogens, and on chromosome aberration (CA) in V79 cells induced by four indirect carcinogens were studied. The indirect carcinogens used were aflatoxin B/sub 1/ (AFB), cyclophosphamide (CPP), benzo(a)anthracene (BA), benzo(a)pyrene (BP), 9,10-dimethyl-1,2-benz(a)anthracene (DMBA), and 3-methylcholanthrene (MCA). The two direct carcinogens were ethyl methane sulfonate (EMS) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Rol effectively inhibited SCE and CA induced by AFB and CPP in a dose-dependent manner, but it had no effect on SCE induced by BA, BP, DMBA, MCA, EMS, and MNNG. To the contrary, Rol had an enhancing effect on CA induced by BP and DMBA. The possibility that Rol exerts its anticarcinogenic effects by inhibiting certain forms of the cytochrome P-450 isoenzymes required for activation of precarcinogens, such as AFB and CPP but not those enzymes required by BA, BP, DMBA, and MCA, is discussed.

  4. Low doses of alpha particles do not induce sister chromatid exchanges in bystander Chinese hamster cells defective in homologous recombination

    SciTech Connect

    Nagasawa, H; Wilson, P F; Chen, D J; Thompson, L H; Bedford, J S; Little, J B

    2007-10-26

    We reported previously that the homologous recombinational repair (HRR)-deficient Chinese hamster mutant cell line irs3 (deficient in the Rad51 paralog Rad51C) showed only a 50% spontaneous frequency of sister chromatid exchange (SCE) as compared to parental wild-type V79 cells. Furthermore, when irradiated with very low doses of alpha particles, SCEs were not induced in irs3 cells, as compared to a prominent bystander effect observed in V79 cells (Nagasawa et al., Radiat. Res. 164, 141-147, 2005). In the present study, we examined additional Chinese hamster cell lines deficient in the Rad51 paralogs Rad51C, Rad51D, Xrcc2, and Xrcc3 as well as another essential HRR protein, Brca2. Spontaneous SCE frequencies in non-irradiated wild-type cell lines CHO, AA8 and V79 were 0.33 SCE/chromosome, whereas two Rad51C-deficient cell lines showed only 0.16 SCE/chromosome. Spontaneous SCE frequencies in cell lines defective in Rad51D, Xrcc2, Xrcc3, and Brca2 ranged from 0.23-0.33 SCE/chromosome, 0-30% lower than wild-type cells. SCEs were induced significantly 20-50% above spontaneous levels in wild-type cells exposed to a mean dose of 1.3 mGy of alpha particles (<1% of nuclei traversed by an alpha particle). However, induction of SCEs above spontaneous levels was minimal or absent after {alpha}-particle irradiation in all of the HRR-deficient cell lines. These data suggest that Brca2 and the Rad51 paralogs contribute to DNA damage repair processes induced in bystander cells (presumably oxidative damage repair in S-phase cells) following irradiation with very low doses of alpha particles.

  5. TISSUE-SPECIFIC SISTER CHROMATID EXCHANGE ANALYSES IN MUTAGEN-CARCINOGEN EXPOSED ANIMALS

    EPA Science Inventory

    The phenomenon of sister chromatid exchange (SCE) has been extensively reviewed. Sister chromatid exchanges are intrachromosomal events, wherein segments of DNA are reciprocally swapped between the chromatids. They are most easily studied with 5-bromodeoxyuridine (BrdU) dye metho...

  6. Evidence for an indirect effect of radiation on mammalian chromosomes. III. UV- and x-ray-induced sister chromatid exchanges in heterokaryons

    SciTech Connect

    Graves, J.A.; Kellow, G.N.

    1983-04-01

    The hypothesis that chromosomes may be damaged indirectly by radiation was examined by assaying sister chromatid exchange, (SCE) frequency in heterokaryons between irradiated and unirradiated mouse and Chinese hamster cells. One cell line was UV or x irradiated, then fused to unirradiated BrdU-labeled cells of the other line; SCEs in the unirradiated set were scored in heterokaryons. A dose-dependent increase was consistently observed; the magnitude of which suggested that 25% of UV-induced and up to 60% of x-ray-induced SCEs are indirectly induced. Medium transfer experiments, cell mixing, and fusion with irradiated chick erythrocyte ghosts suggested that unirradiated chromosomes in heterokaryons are damaged by a stable, nondiffusible cytoplasmic component contributed by the irradiated cell.

  7. Histone H3 K79 methylation states play distinct roles in UV-induced sister chromatid exchange and cell cycle checkpoint arrest in Saccharomyces cerevisiae

    PubMed Central

    Rossodivita, Alyssa A.; Boudoures, Anna L.; Mecoli, Jonathan P.; Steenkiste, Elizabeth M.; Karl, Andrea L.; Vines, Eudora M.; Cole, Arron M.; Ansbro, Megan R.; Thompson, Jeffrey S.

    2014-01-01

    Histone post-translational modifications have been shown to contribute to DNA damage repair. Prior studies have suggested that specific H3K79 methylation states play distinct roles in the response to UV-induced DNA damage. To evaluate these observations, we examined the effect of altered H3K79 methylation patterns on UV-induced G1/S checkpoint response and sister chromatid exchange (SCE). We found that the di- and trimethylated states both contribute to activation of the G1/S checkpoint to varying degrees, depending on the synchronization method, although methylation is not required for checkpoint in response to high levels of UV damage. In contrast, UV-induced SCE is largely a product of the trimethylated state, which influences the usage of gene conversion versus popout mechanisms. Regulation of H3K79 methylation by H2BK123 ubiquitylation is important for both checkpoint function and SCE. H3K79 methylation is not required for the repair of double-stranded breaks caused by transient HO endonuclease expression, but does play a modest role in survival from continuous exposure. The overall results provide evidence for the participation of H3K79 methylation in UV-induced recombination repair and checkpoint activation, and further indicate that the di- and trimethylation states play distinct roles in these DNA damage response pathways. PMID:24748660

  8. Sister chromatid exchange (SCE) induced by laser-UV-microirradiation: correlation between the distribution of photolesions and the distribution of SCEs.

    PubMed

    Raith, M; Cremer, T; Cremer, C; Speit, G

    1984-01-01

    Small, medium, and large nuclear areas comprising approximately 5, 30, or 80% of the total area of the interphase nuclei of Chinese hamster cells (M3-1) cultivated in vitro were irradiated with a laser-UV-microbeam of wavelength 257 nm. The DNA of the cells was substituted with 5-bromodeoxyuridine (BrdUrd) for 1 cell cycle in one set of experiments. After microirradiation the cells were grown for a second cycle in medium without BrdUrd (protocol A). In a second set, cells with nonsubstituted DNA were microirradiated and grown for 2 additional cycles, the first in the presence, the second in the absence of BrdUrd (protocol B). In situ chromosome preparation and differential chromatid staining was subsequently performed. The induction of sister chromatid exchanges (SCEs) was found to be dependent on both the ultraviolet (UV) dose and the spatial distribution of the UV energy within the cell nucleus. Following both protocols the average number of chromosomes with SCEs was significantly higher after microirradiation of a large nuclear area as compared to microirradiation of a small nuclear area. In the latter case, multiple SCEs were noted on individual chromosome arms at the first postirradiation mitosis (protocol A). In other cells, especially at higher doses, protocol A resulted in shattering of a few closely neighbored chromosomes which were surrounded by intact ones with normal SCE levels. Microirradiation of medium-sized nuclear areas produced high levels of SCEs over a number of chromosomes which still appeared spatially related in a part of the metaphase spread. Finally, high SCE levels could be observed over most or all chromosomes when a large nuclear area (up to 100%) was exposed to the microbeam. Following protocol B the increase of SCEs was much less pronounced. Microirradiation of a small part of the cytoplasm in addition to the nuclei did not induce SCEs. Our results support the concept (i) that interphase chromosomes occupy distinct nuclear domains and

  9. Solution Radioactivated by Hadron Radiation Can Increase Sister Chromatid Exchanges

    PubMed Central

    Maeda, Junko; Yurkon, Charles R.; Fujii, Yoshihiro; Fujisawa, Hiroshi; Kato, Sayaka; Brents, Colleen A.; Uesaka, Mitsuru; Fujimori, Akira; Kitamura, Hisashi; Kato, Takamitsu A.

    2015-01-01

    When energetic particles irradiate matter, it becomes activated by nuclear reactions. Radioactivation induced cellular effects are not clearly understood, but it could be a part of bystander effects. This investigation is aimed at understanding the biological effects from radioactivation in solution induced by hadron radiation. Water or phosphate buffered saline was activated by being exposed to hadron radiation including protons, carbon- and iron-ions. 1 mL of radioactivated solution was transferred to flasks with Chinese hamster ovary (CHO) cells cultured in 5 mL of complete media. The induction of sister chromatid exchanges (SCE) was used to observe any increase in DNA damage responses. The energy spectrum and the half-lives of the radioactivation were analyzed by NaI scintillation detector in order to identify generated radionuclides. In the radioactivated solution, 511 keV gamma-rays were observed, and their half-lives were approximately 2 min, 10 min, and 20 min. They respectively correspond to the beta+ decay of 15O, 13N, and 11C. The SCE frequencies in CHO cells increased depending on the amount of radioactivation in the solution. These were suppressed with a 2-hour delayed solution transfer or pretreatment with dimethyl sulfoxide (DMSO). Our results suggest that the SCE induction by radioactivated solution was mediated by free radicals produced by the annihilated gamma-rays. Since the SCE induction and DMSO modulation are also reported in radiation-induced bystander effects, our results imply that radioactivation of the solution may have some contribution to the bystander effects from hadron radiation. Further investigations are required to assess if radioactivation effects would attribute an additional level of cancer risk of the hadron radiation therapy itself. PMID:26657140

  10. Solution Radioactivated by Hadron Radiation Can Increase Sister Chromatid Exchanges.

    PubMed

    Maeda, Junko; Yurkon, Charles R; Fujii, Yoshihiro; Fujisawa, Hiroshi; Kato, Sayaka; Brents, Colleen A; Uesaka, Mitsuru; Fujimori, Akira; Kitamura, Hisashi; Kato, Takamitsu A

    2015-01-01

    When energetic particles irradiate matter, it becomes activated by nuclear reactions. Radioactivation induced cellular effects are not clearly understood, but it could be a part of bystander effects. This investigation is aimed at understanding the biological effects from radioactivation in solution induced by hadron radiation. Water or phosphate buffered saline was activated by being exposed to hadron radiation including protons, carbon- and iron-ions. 1 mL of radioactivated solution was transferred to flasks with Chinese hamster ovary (CHO) cells cultured in 5 mL of complete media. The induction of sister chromatid exchanges (SCE) was used to observe any increase in DNA damage responses. The energy spectrum and the half-lives of the radioactivation were analyzed by NaI scintillation detector in order to identify generated radionuclides. In the radioactivated solution, 511 keV gamma-rays were observed, and their half-lives were approximately 2 min, 10 min, and 20 min. They respectively correspond to the beta+ decay of 15O, 13N, and 11C. The SCE frequencies in CHO cells increased depending on the amount of radioactivation in the solution. These were suppressed with a 2-hour delayed solution transfer or pretreatment with dimethyl sulfoxide (DMSO). Our results suggest that the SCE induction by radioactivated solution was mediated by free radicals produced by the annihilated gamma-rays. Since the SCE induction and DMSO modulation are also reported in radiation-induced bystander effects, our results imply that radioactivation of the solution may have some contribution to the bystander effects from hadron radiation. Further investigations are required to assess if radioactivation effects would attribute an additional level of cancer risk of the hadron radiation therapy itself. PMID:26657140

  11. 40 CFR 79.65 - In vivo sister chromatid exchange assay.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... references should be consulted. (1) 40 CFR 798.5915, In vivo Sister Chromatid Exchange Assay. (2) Kato, H...) assay detects the ability of a chemical to enhance the exchange of DNA between two sister chromatids of... ligation of at least two DNA helices. (c) Test method—(1) Principle of the test method. (i) Groups...

  12. 40 CFR 79.65 - In vivo sister chromatid exchange assay.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... references should be consulted. (1) 40 CFR 798.5915, In vivo Sister Chromatid Exchange Assay. (2) Kato, H...) assay detects the ability of a chemical to enhance the exchange of DNA between two sister chromatids of... ligation of at least two DNA helices. (c) Test method—(1) Principle of the test method. (i) Groups...

  13. 40 CFR 79.65 - In vivo sister chromatid exchange assay.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... references should be consulted. (1) 40 CFR 798.5915, In vivo Sister Chromatid Exchange Assay. (2) Kato, H...) assay detects the ability of a chemical to enhance the exchange of DNA between two sister chromatids of... ligation of at least two DNA helices. (c) Test method—(1) Principle of the test method. (i) Groups...

  14. 40 CFR 79.65 - In vivo sister chromatid exchange assay.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... references should be consulted. (1) 40 CFR 798.5915, In vivo Sister Chromatid Exchange Assay. (2) Kato, H...) assay detects the ability of a chemical to enhance the exchange of DNA between two sister chromatids of... ligation of at least two DNA helices. (c) Test method—(1) Principle of the test method. (i) Groups...

  15. Nonhomologous chromatid exchange in hereditary and sporadic renal cell carcinomas.

    PubMed Central

    Kovacs, G; Kung, H F

    1991-01-01

    For the development of renal cell carcinomas, it has been suggested that a germ-line or somatic mutation occurs on one of the homologous chromosomes 3p, and subsequently the other 3p segment is lost. We have examined the karyotype and/or the allelic combination on chromosomes 3 and 5 by restriction fragment length polymorphism analysis in normal kidney and tumor samples from 28 renal cell carcinomas that developed in two patients with von Hippel-Lindau disease; we then compared the results to those of sporadic tumors. An unbalanced translocation between chromosome 3p and 5q or other chromosomes was found to be the most common aberration. We developed a model of nonhomologous chromatid exchange involving breakpoint clusters at chromosomes 3p13, 3p11.2, 5q22, and 8q11.2. Subsequent chromatid segregation may result in net loss of the 3p segment either (i) in one step or (ii) after a nondisjunctional loss of the derivative chromosome carrying the 3p segment. This general mechanism could also be implicated to explain genetic changes occurring in other types of solid tumors. Images PMID:1986366

  16. Increased sister chromatid exchange associated with smoking and coffee consumption.

    PubMed

    Reidy, J A; Annest, J L; Chen, A T; Welty, T K

    1988-01-01

    Sister chromatid exchange (SCE) is a very sensitive cytogenetic assay for detecting exposure to chemical mutagens and carcinogens. One application of SCE is the monitoring of populations believed to be exposed to such agents. We have, however, relatively little knowledge about common lifestyle factors that may influence SCE and therefore complicate any study designed to examine the effects of exposure to genotoxins. In this study, we assessed the effect of cigarette smoking and coffee consumption on SCE. Smoking was associated with an increase of approximately 2 SCEs per cell and a decrease in cell proliferation. A positive linear relationship between SCE and coffee consumption was also observed. This effect was similar for smokers and nonsmokers. Additionally, the folic acid content of cell culture medium seemed to affect neither SCE nor cell proliferation. PMID:3169009

  17. Sister chromatid exchanges in peripheral lymphocytes after preoperative mammography

    SciTech Connect

    Husum, B.; Wulf, H.C.; Niebuhr, E.

    1981-09-01

    Examination of sister chromatid exchanges (SCE) in peripheral lymphocytes may be useful for evaluating in vivo exposure to chemical mutagens. In vitro exposure of human lymphocytes to low levels of ionizing radiation has failed to produce increased SCE rates. Scarcity of information about the SCE test system and in vivo exposure to radiation prompted the present study of SCE rates in peripheral lymphocytes in women investigated with mammography prior to operation because of a tumor of the breast. In 64 of a total of 131 women a mammography was performed before the operation. The two groups of patients were identical with respect to age, smoking habits, and incidence of malignancy of the mammary tumors. SCE rates were examined in 30 metaphases from each patient following cultivation of peripheral blood lymphocytes using the BrdU/Giemsa technique.

  18. Telomere sister chromatid exchange in telomerase deficient murine cells

    SciTech Connect

    Wang, Yisong; Giannone, Richard J; Liu, Yie

    2005-01-01

    We have recently demonstrated that several types of genomic rearrangements (i.e., telomere sister chromatid exchange (T-SCE), genomic-SCE, or end-to-end fusions) were more often detected in long-term cultured murine telomerase deficient embryonic stem (ES) cells than in freshly prepared murine splenocytes, even through they possessed similar frequencies of critically short telomeres. The high rate of genomic rearrangements in telomerase deficient ES cells, when compared to murine splenocytes, may reflect the cultured cells' gained ability to protect chromosome ends with eroded telomeres allowing them to escape 'end crisis'. However, the possibility that ES cells were more permissive to genomic rearrangements than other cell types or that differences in the microenvironment or genetic background of the animals might consequentially determine the rate of T-SCEs or other genomic rearrangements at critically short telomeres could not be ruled out.

  19. Cultured mouse embryos metabolize benzo[a]pyrene during early gestation: genetic differences detectable by sister chromatid exchange.

    PubMed Central

    Galloway, S M; Perry, P E; Meneses, J; Nebert, D W; Pedersen, R A

    1980-01-01

    Mouse embryos explanted at 7 1/2 or 8 1/2 days of gestation were cultured in medium containing benzo[a]pyrene and supplemented with 5-bromodeoxyuridine to allow detection of sister chromatid exchanges. The murine Ah locus regulates the inducible metabolism of polycyclic hydrocarbons such as benzo[a]pyrene. A high frequency of sister chromatid exchange was induced by benzo[a]pyrene in embryos from three Ah-"responsive" inbred strains (BALB/cDub, C3H/AnfCum, and C57BL/6N); there was little or no increase in two Ah-"nonresponsive" inbred strains (AKR/J and DBA/2J). Benzo[a]pyrene also induced sister chromatid exchanges in the Ah-responsive recombinant inbred line B6NXAKN-12 but not in the Ah-nonresponsive recombinant inbred line B6NXAKN-3. Sister chromatid exchange in cultured Ah-responsive mouse embryos was thus shown to be a sensitive assay. These data provide direct evidence that genetically responsive mouse embryos (early postimplantation stage) possess the subcellular processes necessary for induction of enzymes that metabolize benzo[a]pyrene to its chemically active forms(s). Both the Ah regulatory gene product (a cytoslic receptor) and the structural gene product (inducible cytochrome P1-450) therefore appear to be functional at an early embryonic age. Furthermore, this metabolic capacity may play an important role in the damage to embryonic cells by polycyclic hydracarbons. PMID:6932035

  20. Sister chromatid exchange assay as a predictor of tumor chemoresponse.

    PubMed

    Mourelatos, D

    2016-06-01

    Sister Chromatid Exchanges (SCEs) are known to enhance as a consequence of exposure to various mutagenic agents and appear to indicate DNA damaging effects and/or subsequent repair by homologous recombination (HR). DNA damage plays an interesting role in the majority of mechanisms underlying the effects of antitumor drugs, since the genetic activity of the plethora of these agents is due to their ability to damage the DNA. The DNA-effects of antitumor agents towards normal cells (genotoxicity) are great drawbacks of antitumor therapy and are connected to important adverse health effects in cancer patients undergoing chemotherapy. On the other hand, failure of chemotherapy in many cases is due to the DNA repair ability which cancer, like normal cells, also possess. As both DNA repair and genotoxic exposure are expected to vary among patients, correlating SCEs frequencies with only individual repair capacity may be feasible to predict. Cancer risk has not been observed to be associated with high SCEs levels. Since the administration of effective antitumor drugs with limited adverse effects is of great importance in the success of anticancer therapy, a lot of interest has been directed toward the development of methods and approaches that would enable the correct selection of appropriate drugs prior to the initiation of therapy on an individual basis. To this effect, more than 30 years ago, an investigation of the ability of the in vitro and the in vivo SCEs-assay to predict the in vitro and in vivo sensitivity of tumor cells to newly synthesized drugs or to those already in use began. In this short review a critical appraisal of the SCEs-assay as an important biomarker used for predicting cancer chemo-response as well as a summary of the key findings from several studies published within the last 20 years in this field is performed. PMID:27265374

  1. Bromodeoxyuridine does not contribute to sister chromatid exchange events in normal or Bloom syndrome cells.

    PubMed

    van Wietmarschen, Niek; Lansdorp, Peter M

    2016-08-19

    Sister chromatid exchanges (SCEs) are considered sensitive indicators of genome instability. Detection of SCEs typically requires cells to incorporate bromodeoxyuridine (BrdU) during two rounds of DNA synthesis. Previous studies have suggested that SCEs are induced by DNA replication over BrdU-substituted DNA and that BrdU incorporation alone could be responsible for the high number of SCE events observed in cells from patients with Bloom syndrome (BS), a rare genetic disorder characterized by marked genome instability and high SCE frequency. Here we show using Strand-seq, a single cell DNA template strand sequencing technique, that the presence of variable BrdU concentrations in the cell culture medium and in DNA template strands has no effect on SCE frequency in either normal or BS cells. We conclude that BrdU does not induce SCEs and that SCEs detected in either normal or BS cells reflect DNA repair events that occur spontaneously. PMID:27185886

  2. Effect of lead chromate on chromosome aberration, sister-chromatid exchange and DNA damage in mammalian cells in vitro.

    PubMed

    Douglas, G R; Bell, R D; Grant, C E; Wytsma, J M; Bora, K C

    1980-02-01

    Possible mutagenic activity of lead chromate in mammalian cells was studied using assays for chromosome aberrations and sister-chromatid exchanges in cultured human lymphocytes, and DNA fragmentation as detected by alkaline-sucrose gradient sedimentation in cultured Chinese hamster ovary (CHO) cells. Lead chromate caused dose-related increases in chromosome aberration and sister-chromatid exchange in human lymphocytes. No increase in DNA damage was observed in CHO cells, possibly due to the relative insensitivity of the CHO cells and the limited solubility of lead chromate in tissue culture medium. The mutagenicity of lead chromate in human lymphocytes appears to be entirely due to the chromate ion since chromosome aberrations were induced by potassium chromate but not lead chloride. PMID:7374664

  3. 40 CFR 79.65 - In vivo sister chromatid exchange assay.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... references should be consulted. (1) 40 CFR 798.5915, In vivo Sister Chromatid Exchange Assay. (2) Kato, H... peripheral blood lymphocytes, often from rodent species. (b) Definitions. For the purposes of this section... the end of the exposure period and blood lymphocyte cell cultures are prepared from study...

  4. EVIDENCE FOR THE CHROMOSOMAL REPLICONS AS UNITS OF SISTER CHROMATID EXCHANGES

    EPA Science Inventory

    Current hypotheses of sister chromatid exchange (SCE) formation postulate that sites of SCE induction are associated with active replicons or replicon clusters. We have applied the FCC-SCD technique to in vivo studies of mouse bone marrow cells that have been treated with cycloph...

  5. Chromosome aberration and sister chromatid exchange test results with 42 chemicals.

    PubMed

    Anderson, B E; Zeiger, E; Shelby, M D; Resnick, M A; Gulati, D K; Ivett, J L; Loveday, K S

    1990-01-01

    Forty-two chemicals were tested for their ability to induce cytogenetic change in Chinese hamster ovary cells using assays for chromosome aberrations (ABS) and sister chromatid exchanges (SCE). These chemicals were included in the National Toxicology Program's evaluation of the ability of four in vitro short-term genetic toxicity assays to distinguish between rodent carcinogens and noncarcinogens. The conclusions of this comparison are presented in Zeiger et al. [Zeiger E, Haseman JK, Shelby MD, Margolin BH, Tennant RW (1990): [Environ Molec Mutagen 16(Suppl 18): 1-14]. The in vitro cytogenetic testing was conducted at four laboratories, each using a standard protocol to evaluate coded chemicals with and without exogenous metabolic activation. Most chemicals were tested in a single laboratory; however, two chemicals, tribromomethane and p-chloroaniline, were tested at two laboratories as part of an interlaboratory comparison. Four chemicals (C.I. basic red 9 HCl, 2-mercaptobenzothiazole, oxytetracycline HCl, and rotenone) were tested for SCE in one laboratory and in a different laboratory for ABS. Tetrakis(hydroxymethyl)phosphonium sulfate was tested at one laboratory and the chloride form was tested at a different laboratory. Twenty-five of the 42 chemicals tested induced SCE. Sixteen of these also induced ABS; all chemicals that induced ABS also induced SCE. There was approximately 79% reproducibility of results in repeat tests, thus, we conclude that this protocol is effective and reproducible in detecting ABS and SCE. PMID:2091924

  6. Induction of sister chromatid exchanges by coal dust and tobacco snuff extracts in human peripheral lymphocytes

    SciTech Connect

    Tucker, J.D.; Ong, T.

    1985-01-01

    The organic solvent extracts of sub-bituminous coal dust and tobacco snuff, both together and separately, were tested for the induction of sister chromatid exchanges (SCEs) in human peripheral lymphocytes. The results indicate that these extracts induced SCEs, and that when tested together synergistically induced SCEs in two of three donors. Studies with the organic solvent extracts of all five ranks of coal indicate that the extracts of bituminous, lignite, and peat, but not anthracite, induced SCEs. Similar experiments conducted with water extracts, induced SCEs, and that anthracite was equivocal. To determine whether individuals differed in their SCE responses to coal dust extracts, lymphocytes from five donors were tested with organic solvent extracts of bituminous and sub-bituminous coal. An analysis of variance indicates that the SCE response was significantly influenced by the donor and each of the two coal extracts. The findings presented here suggest that coal dust, with or without tobacco snuff, may play a role in the elevated incidence of gastric cancer in coal miners. Because water extracts of some ranks of coal induced SCEs, there exists the possibility of adverse environmental effects due to coal leachates.

  7. DNA crosslinking, sister-chromatid exchange and specific-locus mutations.

    PubMed

    Carrano, A V; Thompson, L H; Stetka, D G; Minkler, J L; Mazrimas, J A; Fong, S

    1979-11-01

    Chinese hamster ovary cells were treated with the DNA-crosslinking chemicals, mitomycin C (MMC) and porfiromycin (POR), and their monofunctional derivative decarbamoyl mitomycin C (DCMMC). After exposure, the cells were studied for the induction of sister-chromatid exchanges (SCEs) and mutations at the hypoxanthine phosphoribosyltransferase and adenine phosphoribosyltransferase loci. The frequency of SCEs varied significantly in successive sampling intervals, requiring the weighting of each interval by the percentage of second-division mitosis in that interval to obtain the mean SCE frequency for each dose. All 3 compounds were potent inducers of SCEs but weakly mutagenic. All 3 chemicals by concentration were approximately equally effective in inducing SCEs or mutations. When the induced SCEs and mutations were compared at equal levels of survival, DCMMC was slightly more effective than MMC or POR in inducing SCEs and somewhat less mutagenic. These results indicate that the DNA interstrand crosslink is not the major lesion responsible for the induction of SCE or mutation by these compounds. PMID:522865

  8. Induction of sister chromatid exchanges and bacterial revertants by organic extracts of airborne particles. [Humans

    SciTech Connect

    Lockard, J.M.; Viau, C.J.; Lee-Stephens, C.; Caldwell, J.C.; Wojciechowski, J.P.; Enoch, H.G.; Sabharwal, P.S.

    1981-01-01

    The genotoxicities of organic extracts of airborne particles have been studied extensively in the Salmonella/mammalian microsome (Ames) test, but in few other bioassays. In these studies, we tested benzene-acetone extracts of particulate pollutants collected in Lexington, Kentucky, for capacity to induce increases in sister chromatid exchanges (SCE) in human lumphocytes and V79 cells, as well as in the Ames assay. Extracts induced linear dose-related increases in SCE in human lumphocytes and in bacterial revertants.However, variable responses were observed in SCE assays in V79 cells with and without activation by rat liver S9 or feeder layers of irradiated Syrian hamster fetal cells. We conclude that the SCE assay in human lumphocytes may be a useful indicator of the potential risks to humans of airborne particulate pollutants, as it utilizes human cells recently taken from the host, is rapid and economical, and requires small quantities of test materials. However, thorough studies of the quantitative relationships between SCE induction and mutagenicity in human cells are needed.

  9. INDUCTION, ACCUMULATION, AND PERSISTENCE OF SISTER CHROMATID EXCHANGES IN WOMEN WITH BREAST CANCER RECEIVING CYCLOPHOSPHAMIDE, ANDRIAMYCIN, AND 5-FLUOROACIL CHEMOTHERAPY

    EPA Science Inventory

    The induction, stimulation, and persistence of sister chromatid exchanges (SCE's) and high SCE frequency cells (HFC's) was measured in peripheral lymphocytes of women with breast cancer before chemotherapy and on multiple occasions during and after therapy. Chemotherapy consisted...

  10. Evaluation of genotoxic effects of Apitol (cymiazole hydrochloride) in vitro by measurement of sister chromatid exchange.

    PubMed

    Stanimirovic, Zoran; Stevanovic, Jevrosima; Jovanovic, Slobodan; Andjelkovic, Marko

    2005-12-30

    Apitol, with cymiazole hydrochloride as the active ingredient, is used in bee-keeping against the ectoparasitic mite Varroa destructor. The preparation was evaluated for genotoxicity in cultured human peripheral blood lymphocytes. Sister chromatid exchange, the mitotic index and the cell proliferation index were determined for three experimental concentrations of Apitol (0.001, 0.01 and 0.1 mg/ml). All concentrations significantly (p < 0.001) increased the mitotic index (MI = 7.35+/-0.18%, 8.31+/-0.20% and 12.33+/-0.25%, respectively), the proliferative index (PI = 1.83+/-0.01, 1.84+/-0.01 and 1.88+/-0.02, respectively) and the frequency of sister chromatid exchange (SCE = 8.19+/-1.81, 8.78+/-1.80 and 13.46+/-1.88, respectively), suggesting that cymiazole hydrochloride has genotoxic potential. PMID:16309949

  11. Sister chromatid exchange analysis to monitor genotoxic chemicals. (Latest citations from Pollution Abstracts). Published Search

    SciTech Connect

    Not Available

    1993-03-01

    The bibliography contains citations concerning the use of the sister chromatid exchange (SCE) analysis for toxicological studies. SCE analysis are very sensitive measures of genotoxic damage to chromosomes. SCE toxicological studies analyzing ionizing radiation, chromium compounds, styrene, paint thinner, mercury, cigarette smoke, coal dust, fuel oil, insecticides, ethylene oxide, diesel exhaust, and polychlorinated biphenyls are discussed. SCE studies using both human and animal tissue cultures are described. (Contains a minimum of 191 citations and includes a subject term index and title list.)

  12. Health assessment of gasoline and fuel oxygenate vapors: micronucleus and sister chromatid exchange evaluations.

    PubMed

    Schreiner, Ceinwen A; Hoffman, Gary M; Gudi, Ramadevi; Clark, Charles R

    2014-11-01

    Micronucleus and sister chromatid exchange (SCE) tests were performed for vapor condensate of baseline gasoline (BGVC), or gasoline with oxygenates, methyl tert-butyl ether (G/MTBE), ethyl tert butyl ether (G/ETBE), t-amyl methyl ether (G/TAME), diisopropyl ether (G/DIPE), t-butyl alcohol (TBA), or ethanol (G/EtOH). Sprague Dawley rats (the same 5/sex/group for both endpoints) were exposed to 0, 2000, 10,000, or 20,000mg/m(3) of each condensate, 6h/day, 5days/week over 4weeks. Positive controls (5/sex/test) were given cyclophosphamide IP, 24h prior to sacrifice at 5mg/kg (SCE test) and 40mg/kg (micronucleus test). Blood was collected from the abdominal aorta for the SCE test and femurs removed for the micronucleus test. Blood cell cultures were treated with 5μg/ml bromodeoxyuridine (BrdU) for SCE evaluation. No significant increases in micronucleated immature erythrocytes were observed for any test material. Statistically significant increases in SCE were observed in rats given BGVC alone or in female rats given G/MTBE. G/TAME induced increased SCE in both sexes at the highest dose only. Although DNA perturbation was observed for several samples, DNA damage was not expressed as increased micronuclei in bone marrow cells. Inclusion of oxygenates in gasoline did not increase the effects of gasoline alone or produce a cytogenetic hazard. PMID:24852491

  13. The effects of boric acid on sister chromatid exchanges and chromosome aberrations in cultured human lymphocytes

    PubMed Central

    Arslan, Mehmet; Topaktas, Mehmet

    2007-01-01

    The aim of this study was to determine the possible genotoxic effects of boric acid (BA) (E284), which is used as an antimicrobial agent in food, by using sister chromatid exchange (SCEs) and chromosome aberration (CAs) tests in human peripheral lymphocytes. The human lymphocytes were treated with 400, 600, 800, and 1000 μg/mL concentrations of BA dissolved in dimethyl sulfoxide (DMSO), for 24 h and 48 h treatment periods. BA did not increase the SCEs for all the concentrations and treatment periods when compared to control and solvent control (DMSO). BA induced structural and total CAs at all the tested concentrations for 24 and 48 h treatment periods. The induction of the total CAs was dose dependent for the 24 h treatment period. However, BA did not cause numerical CAs. BA showed a cytotoxic effect by decreasing the replication index (RI) and mitotic index (MI). BA decreased the MI in a dose-dependent manner for the 24 h treatment period. PMID:19002846

  14. Frequency of sister chromatid exchange and chromosomal aberrations in asbestos cement workers.

    PubMed Central

    Fatma, N; Jain, A K; Rahman, Q

    1991-01-01

    Exposure to asbestos minerals has been associated with a wide variety of adverse health effects including lung cancer, pleural mesothelioma, and cancer of other organs. It was shown previously that asbestos samples collected from a local asbestos factory enhanced sister chromatid exchanges (SCEs) and chromosomal aberrations in vitro using human lymphocytes. In the present study, 22 workers from the same factory and 12 controls were further investigated. Controls were matched for age, sex, and socioeconomic state. The peripheral blood lymphocytes were cultured and harvested at 48 hours for studies of chromosomal aberrations and at 72 hours for SCE frequency determinations. Asbestos workers had a raised mean SCE rate and increased numbers of chromosomal aberrations compared with a control population. Most of the chromosomal aberrations were chromatid gap and break types. PMID:1998603

  15. Frequency of sister chromatid exchange and chromosomal aberrations in asbestos cement workers.

    PubMed

    Fatma, N; Jain, A K; Rahman, Q

    1991-02-01

    Exposure to asbestos minerals has been associated with a wide variety of adverse health effects including lung cancer, pleural mesothelioma, and cancer of other organs. It was shown previously that asbestos samples collected from a local asbestos factory enhanced sister chromatid exchanges (SCEs) and chromosomal aberrations in vitro using human lymphocytes. In the present study, 22 workers from the same factory and 12 controls were further investigated. Controls were matched for age, sex, and socioeconomic state. The peripheral blood lymphocytes were cultured and harvested at 48 hours for studies of chromosomal aberrations and at 72 hours for SCE frequency determinations. Asbestos workers had a raised mean SCE rate and increased numbers of chromosomal aberrations compared with a control population. Most of the chromosomal aberrations were chromatid gap and break types. PMID:1998603

  16. Genotoxicity evaluation in patients on phenobarbital monotherapy by sister chromatid exchange.

    PubMed

    Schaumann, B A; Winge, V B; Pederson, M

    1989-01-01

    The potential of phenobarbital to interact with DNA has been studied using the sister chromatid exchange (SCE) assay in peripheral lymphocytes of nine adult male patients with epilepsy and of their matched controls. All patients were otherwise healthy individuals, treated chronically with phenobarbital in monotherapy. No statistically significant differences in SCE levels were found between the patient and control groups. Smoking was associated with increased SCE frequencies. The experiment was repeated with five available patients, using a slightly modified methodology. Although different SCE scores were obtained, the results of both tests were comparable. PMID:2585535

  17. Sister chromatid exchange analysis to monitor genotoxic chemicals. (Latest citations from Pollution abstracts). Published Search

    SciTech Connect

    1996-04-01

    The bibliography contains citations concerning the use of the sister chromatid exchange (SCE) analysis for toxicological studies. SCE analysis are very sensitive measures of genotoxic damage to chromosomes. SCE toxicological studies analyzing ionizing radiation, chromium compounds, styrene, paint thinner, mercury, cigarette smoke, coal dust, fuel oil, insecticides, ethylene oxide, diesel exhaust, and polychlorinated biphenyls are discussed. SCE studies using both human and animal tissue cultures are described. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  18. Sister chromatid exchange analysis in lymphocytes of workers exposed to hexavalent chromium.

    PubMed Central

    Nagaya, T; Ishikawa, N; Hata, H

    1989-01-01

    To investigate the usefulness of sister chromatid exchange (SCE) analysis in lymphocytes as an indicator for mutagenic effects after in vivo exposure to hexavalent chromium (Cr), SCE frequency was analysed in lymphocytes of 44 Cr platers occupationally exposed to hexavalent Cr and 47 controls. Although urinary Cr analysis confirmed that the Cr platers were exposed to Cr, no effects of the exposure on SCE frequency were found. Smokers, both Cr platers and controls, had a significantly higher SCE frequency than non-smokers. These results suggest that SCE analysis in human lymphocytes is not a good indicator of possible mutagenic effects of exposure to hexavalent Cr. PMID:2920143

  19. Comparison of sister chromatid exchange induction in murine germinal and somatic cells by gamma radiation exposure in vivo

    SciTech Connect

    Morales-Ramirez, P.; Mendiola-Cruz, M.T.; Vallarino-Kelly, T.; Rodriguez-Reyes, R.

    1994-12-31

    Sister chromatid exchange (SCE) induction by gamma rays was determined in speratogonia irradiated before or after BrdU incorporation. Furthermore, the comparison of responses obtained in spermatogonia, bone marrow and salivary gland cells was carried out in the cells irradiated after BrdU incorporation, a condition which permits a higher SCE induction. Results indicate that gamma ray exposure of spermatogonia could induce a significant increase in SCE frequency with doses as low as 0.27 Gy, either before or after BrdU incorporation. However, the increase caused by radiation exposure after BrdU incorporation in spermatogonia was nearly three times lower than that obtained in both bone marrow and salivary gland cells. These data suggest that spermatogonia are either more efficient in repairing the gamma ray-induced lesions involved in SCE production or that these cells are less prone to the induction of such lesions. 53 refs., 2 figs., 3 tabs.

  20. The induction of sister chromatid exchanges by environmental pollutants: relationship of SCE to other measures of genetic damage

    SciTech Connect

    Brooks, A.L.; Shimizu, R.W.; Li, A.P.; Benson, J.M.; Dutcher, J.S.

    1984-01-01

    Sister chromatid exchanges (SCEs), induced by environmental pollutants from fossil fuel use, were measured in 2 cell systems, Chinese hamster ovary (CHO) cells and Chinese hamster primary lung cell cultures. The frequency of SCEs induced in these cell systems was related to other measures of genetic damage, namely mutations in CHO cells at the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) gene locus and in bacteria (Salmonella mutagenicity test TA-98), produced by the same pollutants. The pollutants were divided into 2 classes: those produced in oxidizing combustion environments--extracts of particles from light-duty diesel cars, spark-ignition cars, and an automotive tunnel; and those produced in reducing environments--extracts from coke oven mains and condensates from a low BTU coal gasifier obtained either before or after cleanup of the process stream. Sister chromatid exchanges were induced by all pollutants without the addition of a rat liver microsomal fraction (S-9 mix), whereas S-9 mix was required to induce a positive response in the CHO/HGPRT assay for all pollutants. The pollutants produced in a reducing environment required metabolic activation by S-9 mix to be mutagenic in the Salmonella mutation assay. The addition of S-9 mix to pollutants produced in an oxidizing environment reduced the response in the Salmonella test. The relative genotoxic potency for each pollutant was determined for all 3 endpoints. The slopes of dose-response curves for each pollutant were plotted for each assay to compare relative potency. When the bacterial mutagenicity test was compared to either mammalian cell assay, SCE or CHO/HGPRT, there was little correlation between relative potencies. However, the data indicated that the responses in the 2 mammalian cell assays, SCE and CHO/HGPRT, showed similar relative responses to the pollutants.

  1. Sister chromatid exchanges in Chinese hamster ovary cells exposed to high intensity pulsed ultrasound: inability to confirm previous positive results.

    PubMed

    Miller, M W; Azadniv, M; Pettit, S E; Church, C C; Carstensen, E L; Hoffman, D

    1989-01-01

    This study was undertaken in an attempt to determine a physical mechanism of action for a recently published report of a small but statistically significant increase in sister chromatid exchanges (SCEs) in Chinese hamster ovary cells exposed to high-intensity pulsed ultrasound. The "positive" report's protocol involved a sizeable chance of ultrasound beam impingement on the side wall of the cell exposure chamber. Ten experiments per regimen were conducted; the regimens included exposures of (a) chamber center, (b) chamber wall, (c) nine grid sites, 0.5 mm between sites, and (d) nine grid sites, 1.5 mm between sites. The last was an exact replication of the conditions previously reported to induce the small SCE effect. The results did not support the postulate of an increase in SCEs with the ultrasound exposures. PMID:2741252

  2. KINETICS OF IN VIVO SISTER CHROMATID EXCHANGE INDUCTION IN MOUSE BONE MARROW CELLS BY ALKYLATING AGENTS: CYCLOPHOSPHAMIDE

    EPA Science Inventory

    Administration of cyclophosphamide (5, 10, 20 and 25 mg/kg body weight) to male CD-1 mice 2 hours after subcutaneous implantation of a 5-bromo-2'-deoxyuridine (BrdU) pellet (55 mg) resulted in a dose-dependent increase in sister chromatid exchanges (SCE) in bone marrow cells. Tre...

  3. Effects of infliximab on sister chromatid exchanges and chromosomal aberration in patients with rheumatoid arthritis.

    PubMed

    Atteritano, M; Mazzaferro, S; Mantuano, S; Bagnato, G L; Bagnato, G F

    2016-03-01

    The aim of this study was to evaluate in a 24-weeks the effect of anti-TNF-alpha, infliximab, on cytogenetic biomarkers in peripheral lymphocytes of patients with rheumatoid arthritis (RA). A total of 40 patients with RA met the criteria to be treated with methotrexate (15 mg/week) were evaluated. Twenty patients, randomly selected, were treated with infliximab in addition to methotrexate (group I), whereas the other 20 patients continued with only methotrexate treatment (group M). Twenty healthy volunteers matched for age, gender and smoking habits served as control group (group C). At baseline, sister chromatid exchange rate was 7.20 ± 2.21 in group I, 7.40 ± 1.60 in group M and 4.97 ± 1.32 in group C (P < 0.01 vs group I and M). After 24-weeks, sister chromatid exchange rate was 7.87 ± 2.54 in group I and 7.81 ± 1.95 in group M (P = ns). High frequency cells count was 4.9 % and 4.7 % in the groups I and M, respectively, at the end of the study (P = ns). The basal chromosomal aberration frequency was 4.90 % in group I and 5.20 % in groups M; after 24-weeks, this was 5.10 % in group I and 5.10 % in groups M (P = ns). Infliximab treatment, for 24 weeks, did not increase the cytogenetic biomarkers in patients with RA. Our data show that the use of infliximab has not a genotoxic effect in patients with RA. PMID:26012953

  4. An increase in telomere sister chromatid exchange in murine embryonic stem cells possessing critically shortened telomeres

    SciTech Connect

    Wang, Yisong; Giannone, Richard J; Wu, Jun; Gomez, Marla V; Liu, Yie

    2005-01-01

    Telomerase deficiency leads to a progressive loss of telomeric DNA that eventually triggers cell apoptosis in human primary cells during prolonged growth in culture. Rare survivors can maintain telomere length through either activation of telomerase or recombination-based telomere lengthening, and thus proliferate indefinitely. We have explored the possibility that telomeres may be maintained through telomere sister chromatid exchange (T-SCE) in murine telomere reverse transcriptase-deficient (mTert -/-) splenocytes and ES cells. Because telomerase deficiency leads to gradual loss of telomeric DNA in mTert -/- splenocytes and ES cells and eventually to chromosomes with telomere signal-free ends (SFEs), we examined these cell types for evidence of sister chromatid exchange at telomeres, and observed an increase in T-SCEs only in a subset of mTert -/- splenocytes or ES cells that possessed multiple SFEs. Furthermore, T-SCEs were more often detected in ES cells than in splenocytes that harbored a similar frequency of SFEs. In mTert heterozygous (mTert +/-) ES cells or splenocytes, which are known to exhibit a decrease in average telomere length but no SFEs, no increase in T-SCE was observed. In addition to T-SCE, other genomic rearrangements (i.e., SCE) were also significantly increased in mTert -/- ES cells possessing critically short telomeres, but not in splenocytes. Our results suggest that animals and cell culture differ in their ability to carry out genomic rearrangements as a means of maintaining telomere integrity when telomeres become critically shortened.

  5. Retinoid protection against x-ray-induced chromatid damage in human peripheral blood lymphocytes.

    PubMed Central

    Sanford, K K; Parshad, R; Price, F M; Tarone, R E; Kraemer, K H

    1992-01-01

    Oral administration of isotretinoin (13-cis retinoic acid) was shown previously (Kraemer, K. H., J. J. DiGiovanna, A. N. Moshell, R. E. Tarone, and G. L. Peck. 1988. N. Engl. J. Med. 318:1633-1637) to reduce the frequency of skin cancers in xeroderma pigmentosum (XP) patients. The mechanism of protection was unclear. In the present study, x-ray-induced chromatid damage in PHA-stimulated blood lymphocytes from five XP patients receiving isotretinoin was approximately half that in blood samples from the same patients before or subsequent to treatment. The x-ray-induced chromatid damage in blood lymphocytes from a normal control was reduced significantly by cocultivation with blood or plasma from an XP patient receiving isotretinoin or by addition of 10(-6) M isotretinoin to cultures 1 h before x-irradiation. A similar reduction in x-ray-induced chromatid damage was reported previously by adding to the culture medium, mannitol, a scavenger of the free hydroxyl radical, or catalase, which decomposes hydrogen peroxide; both of these products are generated during ionizing radiation. The present observations suggest that isotretinoin acts as a scavenger of such radiation products, thereby providing protection against x-ray-induced chromatid damage. PMID:1430230

  6. Frequencies of chromosomal aberrations and sister chromatid exchanges in the benthic worm Neanthes arenaceodentata exposed to ionizing radiation

    SciTech Connect

    Harrison, F.L.; Rice, D.W. Jr., Moore, D.H.

    1984-07-01

    Traditional bioassays are unsuitable for assessing sublethal effects from ocean disposal of low-level radioactive waste because mortality and phenotypic responses are not anticipated. We compared the usefulness of chromosomal aberration and sister chromatid exchange (SCE) induction as measures of low-level radiation effects in a sediment-dwelling marine worm, Neanthes arenaceodentata. The SCEs, in contrast to chromosomal aberrations, do not alter the overall chromosome morphology and in mammalian cells appear to be a more sensitive indicator of DNA alterations caused by environmental mutagens. Newly hatched larvae were exposed to two radiation-exposure regimes of either x rays at a high dose rate of 0.7 Gy (70 rad)/min for as long as 5.5 min or to /sup 60/Co gamma rays at a low dose rate of from 4.8 x 10/sup -5/ to 1.2 x 10/sup -1/ Gy (0.0048 to 12 rad)/h for 24 h. After irradiation, the larvae were exposed to 3 x 10/sup -5/M bromodeoxyuridine (BrdUrd) for 28 h (x-ray-irradiated larvae) or for 54 h (/sup 60/Co-irradiated larvae). Larval cells were examined for the proportion of cells in first, second, and third or greater division. Frequencies of chromosomal aberrations and SCEs were determined in first and second division cells, respectively. Results from x-ray irradiation indicated that dose-related increases occur in chromosome and chromatid deletions, but a dose of equal or greater 2 Gy (equal to or greater than 200 rad) was required to observe a significant increase. Worm larvae receiving /sup 60/Co irradiation showed elevated SCE frequencies with a significant increase of 0.6 Gy (60 rad). We suggest that both SCEs and chromosomal aberrations may be useful for measuring effects on genetic material induced by radiation. 56 references, 7 figures, 9 tables.

  7. The induction of sister chromatid exchanges by environmental pollutants: relationship of SCE to other measures of genetic damage.

    PubMed

    Brooks, A L; Shimizu, R W; Li, A P; Benson, J M; Dutcher, J S

    1984-01-01

    Sister chromatid exchanges (SCEs), induced by environmental pollutants from fossil fuel use, were measured in 2 cell systems, Chinese hamster ovary (CHO) cells and Chinese hamster primary lung cell cultures. The frequency of SCEs induced in these cell systems was related to other measures of genetic damage, namely mutations in CHO cells at the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) gene locus and in bacteria (Salmonella mutagenicity test TA-98), produced by the same pollutants. The pollutants were divided into 2 classes: those produced in oxidizing combustion environments--extracts of particles from light-duty diesel cars, spark-ignition cars, and an automotive tunnel; and those produced in reducing environments--extracts from coke oven mains and condensates from a low BTU coal gasifier obtained either before or after cleanup of the process stream. Sister chromatid exchanges were induced by all pollutants without the addition of a rat liver microsomal fraction (S-9 mix), whereas S-9 mix was required to induce a positive response in the CHO/HGPRT assay for all pollutants. The pollutants produced in a reducing environment required metabolic activation by S-9 mix to be mutagenic in the Salmonella mutation assay. The addition of S-9 mix to pollutants produced in an oxidizing environment reduced the response in the Salmonella test. The relative genotoxic potency for each pollutant was determined for all 3 endpoints. The slopes of dose-response curves for each pollutant were plotted for each assay to compare relative potency. When the bacterial mutagenicity test was compared to either mammalian cell assay, SCE or CHO/HGPRT, there was little correlation between relative potencies. However, the data indicated that the responses in the 2 mammalian cell assays, SCE and CHO/HGPRT, showed similar relative responses to the pollutants. Differences in the requirement for S-9 mix seem to be related to both the chemical nature of the mixture and the endpoint

  8. Analysis of chromosome aberrations and sister chromatid exchanges in peripheral blood lymphocytes of newborns after vitamin K prophylaxis at birth.

    PubMed

    Cornelissen, M; Smeets, D; Merkx, G; De Abreu, R; Kollee, L; Monnens, L

    1991-12-01

    In many countries vitamin K prophylaxis at birth is recommended to prevent bleeding in infants due to vitamin K deficiency. Because the incidence of clinical vitamin K deficiency is very low, such a vitamin K administration should be completely safe. However, an increase in sister chromatid exchanges in lymphocytes of fetal sheep 24 h after injection of vitamin K1 has been reported. Therefore, a study concerning genotoxicity of vitamin K1 in man was conducted. Sister chromatid exchanges and chromosome aberrations were analyzed in peripheral blood lymphocytes of six newborns 24 h after intramuscular administration of 1 mg vitamin K1 and in six control neonates. The mean number of sister chromatid exchanges per metaphase in the vitamin K group was 8.88 +/- 1.22 as compared with 9.05 +/- 1.14 in the control group (NS). The mean number of chromosome aberrations per 100 mitoses was 3.00 +/- 2.61 in the vitamin K group and 2.50 +/- 1.87 in the control group (NS). Vitamin K1 plasma concentrations ranged from 115 to 1150 ng/mL (255 to 2555 x 10(-9) M) in the supplemented group, a 5000-fold rise as compared with the control group (p less than 0.01). We did not find any evidence for genetic toxicity due to the administration of 1 mg vitamin K1 intramuscularly to the newborn child. PMID:1805152

  9. The correlation between the frequency of sister-chromatid exchange and human reproductive hormones.

    PubMed

    Joseph-Lerner, N; Fejgin, M; Ben-Nun, I; Legum, C; Amiel, A

    1993-08-01

    Different frequencies of sister-chromatid exchanges (SCEs) during various stages of the menstrual cycle have previously been observed. We tested the hypothesis that sex hormones, particularly steroids, influence the frequency of SCEs in women undergoing ovulation induction for in vitro fertilization treatment. These women undergo extreme hormonal changes and therefore serve as a good model for testing the rate of genetic damage due to these changes. As controls, we tested fertile women with regular menstrual cycles who received no hormonal treatment. Peripheral lymphocytes were obtained during different stages of the normal and treated cycles. We examined SCE frequency as related to the different hormones of the reproductive cycle at each of the stages. In general, an increased SCE frequency was observed around ovulation time in the controls, and around the time of human chorionic gonadotropin administration in the group undergoing ovulation induction. However, in the latter group, SCE frequency was significantly higher. SCE frequency was positively correlated with the level of testosterone and FSH in the ovulation induction group, and positively correlated with the estradiol level in both groups. PMID:7687025

  10. Effects of cigarette smoking and solvent exposure on sister chromatid exchange frequency in painters

    SciTech Connect

    Kelsey, K.T.; Wiencke, J.K.; Little, F.F.; Baker, E.L. Jr.; Little, J.B.

    1988-01-01

    A cross-sectional study of sister chromatid exchange frequency (SCE) in peripheral blood lymphocytes from 117 members of the International Brotherhood of Painters and Allied Tradesman was conducted in union locals in two major US cities. Chronic solvent exposure intensity and duration were estimated from interviewer-administered-questionnaire data. SCE for all of the workers in the study were scored by one reader. A second reader determined the SCE frequency from a random sample of 30 workers. Age, coffee and alcohol intake and chronic solvent exposure (both intensity and duration, estimated over the working lifetime and over the year prior to study for each worker) did not significantly elevate SCE. The effect of smoking on SCE frequency, assessed by analysis of variance controlling for other possible confounding factors, showed that smoking increased SCE frequency. The SCE frequency in the smoking, solvent-exposed (estimated as lifetime exposure) painters were 6.75 SCE/cell; in the non-smoking, solvent-exposed workers the SCE frequency was 5.73 SCE/cell. These observations are consistent with other work suggesting that chronic solvent exposure in the paint trade is not associated with an elevation in SCE in peripheral blood lymphocytes. However, further work is necessary to address adequately the question of the genotoxicity of acute solvent exposure in these workers.

  11. Elevated sister chromatid exchange frequencies in New Zealand Vietnam War veterans.

    PubMed

    Rowland, R E; Edwards, L A; Podd, J V

    2007-01-01

    From July 1965 until November 1971, New Zealand Defence Force Personnel fought in the Vietnam War. During this time more than 76,500,000 litres of phenoxylic herbicides were sprayed over parts of Southern Vietnam and Laos, the most common being known as 'Agent Orange'. The current study aimed to ascertain whether or not New Zealand Vietnam War veterans show evidence of genetic disturbance arising as a consequence of their now confirmed exposure to these defoliants. A sample group of 24 New Zealand Vietnam War veterans and 23 control volunteers were compared using an SCE (sister chromatid exchange) analysis. The results from the SCE study show a highly significant difference (P < 0.001) between the mean of the experimental group (11.05) and the mean of a matched control group (8.18). The experimental group also has an exceptionally high proportion of HFCs (cells with high SCE frequencies) above the 95th percentile compared to the controls (11.0 and 0.07%, respectively). We conclude that the New Zealand Vietnam War veterans studied here were exposed to a clastogenic substance(s) which continues to exert an observable genetic effect today, and suggest that this is attributable to their service in Vietnam. PMID:17431321

  12. Role of oxygen free radicals in the induction of sister chromatid exchanges by cigarette smoke

    SciTech Connect

    Lee, C.K.; Brown, B.G.; Rice, W.Y. Jr.; Doolittle, D.J. )

    1989-01-01

    Cigarette smoke has been reported to contain free radicals and free radical generators in both the gas and particulate phases. Studies in our laboratory have shown that both cigarette smoke condensate (CSC) and smoke bubbled through phosphate buffered saline solution (smoke-PBS) increased sister chromatid exchanges (SCE) in Chinese hamster ovary cells in a dose-dependent manner. Since oxygen free radicals have been shown to cause SCEs and other chromosomal damage, we investigated the role of these radicals in the induction of SCEs by CSC and smoke-PBS. Addition of the antioxidant enzymes catalase and superoxide dismutase or the oxygen-radical scavenger ascorbic acid failed to reduce the SCE frequency in the presence of either CSC or smoke-PBS. Additional studies indicated that the quantity of hydrogen peroxide produced in CSC or smoke-PBS is too small to account for the observed SCE induction. It appears, therefore, that SCE induction by CSC or smoke-PBS does not involve the participation of oxygen free radicals.

  13. Enhanced response to the induction of sister chromatid exchange by gamma radiation in neurofibromatosis

    SciTech Connect

    Hafez, M.; Abd el-Nabi, S.M.; el-Wehedi, G.; Al-Tonbary, Y.

    1986-05-15

    The study included 8 unrelated patients with neurofibromatosis, and 10 unrelated normal and healthy persons as controls. Whole blood samples were divided into plastic T flasks and exposed at room temperature to gamma rays. The radiation dose was 36 rad/minute, and the doses delivered were 0, 75, 150 and 300 rad. The lymphocytes were cultured in (RPMI) 1640 tissue culture medium and autologous serum (20%). Phytohemagglutinin and bromodeoxyuridine (Brdu) (10 microM) were added at initiation of culture and harvesting was done 64 to 68 hours after culture initiation. Slides were coded, differential staining was done, and sister chromatid exchanges (SCEs) and aberrations (gaps, breaks, dicentrics, fragments and minutes) were counted. In the controls no significant increase in frequency of SCE has been found (P greater than 0.5). In the patients, the frequencies significantly increased with the increase of dose of irradiation (P less than 0.001). Furthermore, after irradiation, the incidence of gaps, breaks, and dicentrics were significantly increased in patients compared with controls. Moreover, the incidence increased with the increase in the dose of radiation. The results are discussed with a conclusion that the results add to the indication of a genetic predisposition to develop cancer in neurofibromatosis patients.

  14. A high rate of telomeric sister chromatid exchange occurs in chronic lymphocytic leukaemia B-cells.

    PubMed

    Medves, Sandrine; Auchter, Morgan; Chambeau, Laetitia; Gazzo, Sophie; Poncet, Delphine; Grangier, Blandine; Verney, Aurélie; Moussay, Etienne; Ammerlaan, Wim; Brisou, Gabriel; Morjani, Hamid; Géli, Vincent; Palissot, Valérie; Berchem, Guy; Salles, Gilles; Wenner, Thomas

    2016-07-01

    Cancer cells protect their telomere ends from erosion through reactivation of telomerase or by using the Alternative Lengthening of Telomere (ALT) mechanism that depends on homologous recombination. Chronic lymphocytic leukaemia (CLL) B cells are characterized by almost no telomerase activity, shelterin deregulation and telomere fusions. To characterize telomeric maintenance mechanisms in B-CLL patients, we measured their telomere length, telomerase expression and the main hallmarks of the ALT activity i.e. C-circle concentration, an extra-chromosomal telomere repeat (ECTR), and the level of telomeric sister chromatid exchange (T-SCE) rate. Patients showed relative homogenous telomere length although almost no TERT transcript and nearly no C-circle were evidenced. Nevertheless, compared with normal B cells, B-CLL cells showed an increase in T-SCE rate that was correlated with a strong down-regulation of the topoisomerase III alpha (TOP3A) expression, involved in the dissolution of Holliday Junctions (HJ), together with an increased expression of SLX1A, SLX4, MUS81 and GEN1, involved in the resolution of HJ. Altogether, our results suggest that the telomere maintenance mechanism of B-CLL cells do not preferentially use telomerase or ALT. Rather, the rupture of the dissolvasome/resolvasome balance may increase telomere shuffling that could homogenize telomere length, slowing telomere erosion in this disease. PMID:26970083

  15. Induction of sister chromatid exchanges by direct and indirect chemical agents in a human teratoma cell line

    SciTech Connect

    Murison, G. . Dept. of Biological Sciences)

    1989-01-01

    In the present work, we have extended the characterization of the P3 cell line, derived from a human epithelial teratocarcinoma, by studying the induction of sister chromatid exchanges (SCEs) by direct and indirect carcinogens. Several direct-acting carcinogens produce a dose-dependent increase in SCEs. Most notably, N-methyl-N{prime}-nitro-N-nitrosoguanidine and 7{beta}, 8{alpha}-dihydroxy-9 {alpha},10{alpha}-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene produce increases in SCEs at dosages comparable to those used to induce mutations at the hypoxanthine-guanine phosphoribosyl transferase locus. The indirect carcinogens elicit SCEs only when the P3 cells are cocultured with cells capable of metabolizing the indirect carcinogens to the active form. Human breast carcinoma (BJ-015) and rat hepatoma (RL12) cells are equally efficient in activating polycyclic aromatic hydrocarbons to the active form. This cell-mediated induction of SCEs is obtained when P3 cells are incubated with live, x-irradiated, or UV-irradiated BJ or RL cells. This P3 cell line is thus equally suitable to study the induction of mutations or the induction of SCEs with direct and indirect carcinogens. 35 refs., 3 tabs.

  16. Sister chromatid exchange: A possible approach to characterize familial breast cancer patients.

    PubMed

    De Pascalis, Ivana; Pilato, Brunella; Mazzotta, Annalisa; Dell'Endice, Teresa Stefania; Rubini, Vincenza; Simone, Giovanni; Paradiso, Angelo; Aiello, Vincenzo; Mangia, Anita

    2015-02-01

    Sister chromatid exchange (SCE) frequency is widely used as an indicator of spontaneous chromosome instability. We investigated SCE frequency in the peripheral blood lymphocytes of familial and sporadic breast cancer (BC) patients from the Apulian Caucasian Population. Eighty-one patients were enrolled: 22 with familial history and 59 sporadic patients. Eleven familial patients had an 'increased risk' of BRCA gene mutation (BRCAPro ≥ 10%) and were candidates for BRCA1 and BRCA2 mutation analysis. For these reasons, we stratified the 22 familial BC patients in two group: 'low-risk' (n=11) and 'high-risk' (n=11) patients for BRCA gene mutations. Two of these 11 'high-risk' patients (18%) had pathogenic mutations in the BRCA2 gene. The subjects were not cigarette smokers or alcohol or drug users, and had no genetic disorders or chronic diseases affecting the family. Our results showed a significant increase in SCE frequency in the familial (5.305 ± 1.088/metaphase) (P<0.0001) and the sporadic patients (3.943 ± 0.552) (P<0.0001) compared to the controls (3.197 ± 0.649). We found that the SCE frequency was always significantly higher in familial than in sporadic patients, regardless of their clinicopathological characteristics. Moreover, we observed that the frequency of SCE in BRCA2 mutation carrier patients was higher compared to patients without mutations in BRCA1/2 genes. These findings highlight an intrinsic genomic instability in familial patients, and we suggest that SCE frequency may be used as a biomarker to better characterize familial BC. PMID:25434423

  17. Incorporation of deoxyuridine monophosphate into DNA increases the sister-chromatid exchange yield

    SciTech Connect

    Pardo, E.G.; Hernandez, P.; Gutierrez, C.

    1987-02-01

    The effect of a treatment with 5-fluoro-2'-deoxyuridine (FdUrd) in combination with 2'-deoxyuridine (dUrd) on cell proliferation, incorporation of DNA precursors into DNA and sister-chromatid exchanges (SCEs) has been analyzed in Allium cepa meristem cells. FdUrd in the range 10/sup -9/-5 x 10/sup -7/ M produced a dose- and time-dependent decrease in the amount of cells in mitosis. This inhibitory effect could be reversed by 70-80% in short-term (6 h) experiments, by exogenously supplied dUrd at a concentration of 10/sup -1/ M. However, at the highest FdUrd dose tested (10/sup -7/ M), 10/sup -4/ M dUrd could not reverse the FdUrd effect in long-term experiments as shown by analyzing the kinetics of synchronous cell populations. DNA extracted from cells pulsed with (6-/sup 3/H)dUrd in the presence of FdUrd and 6-amino-uracil (6-AU), an inhibitor of uracil-DNA glycosylase, contained a small amount of label in the form of (6-/sup 3/H)dUMP. Thus the authors conclude that under the experimental conditions, exogenously supplied dUrd may be metabolized intracellularly to 2'-deoxyuridine triphosphate (dUTP) and that this deoxynucleotide may eventually be mis-incorporated into DNA. By analyzing SCE levels in third division chromosomes of cells treated with FdUrd and dUrd during their second cycle, they has scored a 6-fold increase in the reciprocal SCE level which demonstrates that the replication of a dUMP-containing DNA template leads to a higher SCE yield.

  18. Effects of cigarette smoking and solvent exposure on sister chromatid exchange frequency in painters.

    PubMed

    Kelsey, K T; Wiencke, J K; Little, F F; Baker, E L; Little, J B

    1988-01-01

    A cross-sectional study of sister chromatid exchange frequency (SCE) in peripheral blood lymphocytes from 117 members of the International Brotherhood of Painters and Allied Tradesman was conducted in union locals in two major U.S. cities. Chronic solvent exposure intensity and duration were estimated from interviewer-administered-questionnaire data. SCE for all of the workers in the study were scored by one reader. A second reader determined the SCE frequency from a random sample of 30 workers. No significant difference in SCE frequency was associated with reader or time of reading. Age, coffee and alcohol intake and chronic solvent exposure (both intensity and duration, estimated over the working lifetime and over the year prior to study for each worker) did not significantly elevate SCE. The effect of smoking on SCE frequency, assessed by analysis of variance controlling for other possible confounding factors, showed that smoking increased SCE frequency (P less than .0001). The SCE frequency in the smoking, solvent-exposed (estimated as lifetime exposure) painters was 6.75 SCE/cell; in the non-smoking, solvent-exposed workers the SCE frequency was 5.73 SCE/cell; the controls had SCE levels of 6.84 SCE/cell (smokers) and 5.90 SCE/cell (non-smokers), respectively. These observations are consistent with other work suggesting that chronic solvent exposure in the paint trade is not associated with an elevation in SCE in peripheral blood lymphocytes. However, further work is necessary to address adequately the question of the genotoxicity of acute solvent exposure in these workers. PMID:3356184

  19. The Relationship between Dioxin Congeners in the Breast Milk of Vietnamese Women and Sister Chromatid Exchange

    PubMed Central

    Suzuki, Hiroyuki; Kido, Teruhiko; Okamoto, Rie; Nhu, Dang Duc; Nishijo, Muneko; Nakagawa, Hideaki; Tawara, Kenji; Horikawa, Hiroaki; Sato, Yuko; Dung, Phung Tri; Thom, Le Hong; Hung, Nguyen Ngoc

    2014-01-01

    The aim of this study was to clarify the relationship between dioxin concentrations in breast milk and the sister chromatid exchange (SCE) frequency in women from herbicide-sprayed and non sprayed areas. Blood samples were taken from 21 women with high TCDD (tetrachlorodibenzo-p-dioxin) levels from sprayed areas, 23 women with moderate TCDD levels from sprayed areas, and 19 women from non sprayed areas to determine their SCE frequency. The SCE frequencies for the high and moderate TCDD groups from the sprayed area and for the non sprayed area group were 2.40, 2.19, and 1.48 per cell, respectively. Multiple regression analysis showed that the standardized β values for 1,2,3,6,7,8-hexaCDD (β = 0.60), 1,2,3,4,6,7,8-heptaCDD (β = 0.64), and octaCDD (β = 0.65) were higher than those for TCDD (β = 0.34) and 1,2,3,7,8-pentaCDD (β = 0.42). The adjusted R2 value for polyCDDs (R2 = 0.38) was higher than that for polyCDD toxic equivalents (TEQ (toxic equivalents); R2 = 0.23). This study therefore shows that levels of hexa-, hepta-, and octaCDD, which were previously regarded as being less toxic than TCDD, are closely related to SCE frequency and that the level of dioxin (pg/g lipid) is potentially more useful as an indicator than TEQ value for explaining SCE frequency. PMID:24786289

  20. Molecular cloning of the human XRCC1 gene, which corrects defective DNA strand break repair and sister chromatid exchange.

    PubMed Central

    Thompson, L H; Brookman, K W; Jones, N J; Allen, S A; Carrano, A V

    1990-01-01

    We describe the cloning and function of the human XRCC1 gene, which is the first mammalian gene isolated that affects cellular sensitivity to ionizing radiation. The CHO mutant EM9 has 10-fold-higher sensitivity to ethyl methanesulfonate, 1.8-fold-higher sensitivity to ionizing radiation, a reduced capacity to rejoin single-strand DNA breaks, and a 10-fold-elevated level of sister chromatid exchange compared with the CHO parental cells. The complementing human gene was cloned from a cosmid library of a tertiary transformant. Two cosmid clones produced transformants that showed approximately 100% correction of the repair defect in EM9 cells, as determined by the kinetics of strand break repair, cell survival, and the level of sister chromatid exchange. A nearly full-length clone obtained from the pcD2 human cDNA expression library gave approximately 80% correction of EM9, as determined by the level of sister chromatid exchange. Based on an analysis of the nucleotide sequence of the cDNA insert compared with that of the 5' end of the gene from a cosmid clone, the cDNA clone appeared to be missing approximately 100 bp of transcribed sequence, including 26 nucleotides of coding sequence. The cDNA probe detected a single transcript of approximately 2.2 kb in HeLa polyadenylated RNA by Northern (RNA) blot hybridization. From the open reading frame and the positions of likely start sites for transcription and translation, the size of the putative XRCC1 protein is 633 amino acids (69.5 kDa). The size of the XRCC1 gene is 33 kb, as determined by localizing the endpoints on a restriction endonuclease site map of one cosmid clone. The deduced amino acid sequence did not show significant homology with any protein in the protein sequence data bases examined. Images PMID:2247054

  1. In vitro and occupational induction of sister-chromatid exchanges in human lymphocytes with furfuryl alcohol and furfural.

    PubMed

    Gomez-Arroyo, S; Souza, V

    1985-06-01

    Sister-chromatid exchanges (SCEs) in human lymphocytes were studied using the FPG technique in order to determine the cytogenetic effect of furfural and furfuryl alcohol. The induction of SCEs was also investigated in workers occupationally exposed to these solvents that are commonly used in the manufacture of furoic resins. The results obtained from the in vitro treatments show that furfural increased the number of SCEs, while furfuryl alcohol did not. In exposed workers, neither of these solvents increased the spontaneous frequency of SCEs per metaphase. PMID:4000179

  2. Sister-chromatid exchanges and cell-cycle delay in Chinese hamster V79 cells treated with 9 organophosphorus compounds (8 pesticides and 1 defoliant).

    PubMed

    Chen, H H; Sirianni, S R; Huang, C C

    1982-03-01

    Significant increase of sister-chromatid exchanges (SCE) in V79 cells treated with 2 organophosphorus pesticides (OPP), fenthion and oxydemeton-methyl, was observed. The other 7 compounds (6 OPP and 1 defoliant) namely, amaze, azinphos-methyl, bolstar, DEF-defoliant, fensulfothion, monitor and nemacur caused no increase of SCE frequencies at the doses tested. All the compounds except fensulfothion and oxydemeton-methyl induced cell-cycle delay in varying degrees. Cell-cycle delay caused by an OPP was found to be dose-dependent. Based on these data as well as others reported, it would appear that OPP which induce no SCE increase and no or slight cell-cycle delay could be considered as good candidates to substitute the pesticides that have been found to be harmful to the environment. PMID:6211614

  3. Sister chromatid exchange test in river buffalo lymphocytes treated in vitro with furocoumarin extracts.

    PubMed

    Iannuzzi, Alessandra; Perucatti, Angela; Genualdo, Viviana; Pauciullo, Alfredo; Melis, Rita; Porqueddu, Claudio; Marchetti, Mauro; Usai, Marianna; Iannuzzi, Leopoldo

    2016-09-01

    Furocoumarin extracts from Psoralea morisiana, the endemic Sardinian legume species, were tested for their mutagenic potential on river buffalo blood cells. The results obtained performing the sister chromatid exchange (SCE) test in blood cultures of five river buffalo calves (exposure to furocoumarins for 72h) and five cows (exposure to furocoumarins for 3h, in the absence and presence of S9 metabolic activator) are reported. Significant differences in mean values of SCEs were observed in cells of calves compared to control cells (unexposed), but no differences in SCE mean values were found between treated and untreated cells of cows in the presence or absence of S9. SCE mean values were much higher in cells of cows (exposed and control) than in cells of calves. Indeed, in calf cells, SCE mean values/cell (±SD) were 6.66±2.45 in the control and 7.63±3.01, 9.03±3.90, 9.53±3.60 and 9.99±3.41 in treated cells at 50, 100, 200 and 400 µg/ml of furocoumarin extracts, respectively. In cow cells, grown in presence of S9, SCE mean values/cell were 11.49±4.78 and 11.65±5.19 in treated cells at 100 and 200 µg/ml of furocoumarins and 11.66±5.45 in the control. In cow cells grown in absence of S9, SCE mean values were 11.81±6.14 in the control and 12.35±7.09 and 12.01±5.43, respectively, in the presence of 100 and 200 µg/ml of furocoumarins. Despite their higher SCE values in the absence of S9, no statistically significant differences were found when these values were compared with those shown in presence of S9, suggesting no mutagenic action of furocoumarins in cows, at the doses used in this study. PMID:27180332

  4. Unequal mitotic sister chromatid exchange: A rare mechanism for chromosomal abnormality resulting in duplication/deletion of chromosome 7q

    SciTech Connect

    Eydoux, P.; Ortenberg, J.; Chalifoux, N.

    1994-09-01

    We report a case of unequal mitotic chromatid exchange, which has rarely been reported as a mechanism for microscopic chromosomal anomalies. The proposita was born at 40 weeks, after an uneventful pregnancy, of parents with a negative family history. The baby was small for gestational age and had dysmorphic features, including scaphocephaly, bilateral epicanthal folds and palpebral ptosis, mild hypertelorism, hypoplasia of orbital contours, right coloboma, bulbous prominent nose, retrognathism, downturned mouth, low set posteriorly rotated ears, tapering of the limbs. bilateral Sydney creases. At 5 months, she was under the 5th percentile for height, weight and head circumference, and had a mild developmental delay. The karyotype showed an abnormality of chromosome 7 in all cells, half with a duplication and half with a deletion of the same region; 46,XX,del(7)(q33{yields}q34)/46,XX,dup(7)(q33{yields}q34). This chromosomal abnormality could be explained by an unequal chromatid exchange occuring in the first mitosis of the embryo. To our knowledge, only one such human microscopic abnormality, involving chromosome Y, has been reported to date. This type of genetic unbalance could be missed by molecular techniques.

  5. Elevated frequency of sister chromatid exchanges in lymphocytes of victims of the Tokyo sarin disaster and in experiments exposing lymphocytes to by-products of sarin synthesis.

    PubMed

    Li, Q; Minami, M; Clement, J G; Boulet, C A

    1998-09-01

    More than 5000 passengers of Tokyo subway trains were injured with toxic chemicals including the nerve gas sarin. Most of the victims examined had marked miosis and decreased serum cholinesterase activity. To monitor the genetic aftereffects of sarin exposure, we measured sister chromatid exchanges (SCEs) of the victims using peripheral blood lymphocytes. The frequency of SCEs was significantly higher in the victims than in the control group. Analyzing results using samples of urine from the victims suggested that the victims were exposed to not only sarin per se, but by-products of sarin synthesis, i.e. diisopropyl methylphosphonate (DIMP), diethyl methylphosphonate (DEMP) and ethyl isopropyl methylphosphonate (EIMP). Thus, the in vitro SCE-inducing effect of DIMP, DEMP and EIMP was examined using human lymphocytes and we obtained positive results. PMID:9776566

  6. Effects of radiation on frequency of chromosomal aberrations and sister chromatid exchange in the benthic worm Neanthes arenaceodentata

    SciTech Connect

    Harrison, F.L.; Rice, D.W. Jr.; Moore, D.H.; Varela, M.

    1983-04-01

    Traditional bioassays are unsuitable for assessing sublethal effects of low levels of radioactivity because mortality and phenotypic responses are not anticipated. We compared the usefulness of chromosomal aberration (CA) and sister chromatid exchange (SCE) induction as measures of low-level radiation effects in a sediment-dwelling marine worm, Neanthes arenaceodentata. Newly hatched larvae were exposed to two radiation exposure regimes. Groups of 100 larvae were exposed to either x rays delivered at high dose rates (0.7 Gy min/sup -1/) or to /sup 60/Co gamma rays delivered at low dose rates (4.8 X 10/sup -5/ to 1.2 X 10/sup -1/ Gy h/sup -1/). After irradiation, the larvae were exposed to 3 X 10/sup -5/M bromodeoxyuridine (BrdUrd) for 28 h (x-ray-irradiated larvae) or for 54 h (/sup 60/Co-irradiated larvae). Slides of larval cells were prepared for observation of CAs and SCEs. Frequencies of CAs were determined in first division cells; frequencies of SCEs were determined in second division cells. Results from x-ray irradiation indicated that dose-related increases occur in chromosome and chromatid deletions, but an x-ray dose greater than or equal to 2 Gy was required to observe a significant increase. Worm larvae receiving /sup 60/Co irradiation showed elevated SCE frequencies; a significant increase in SCE frequency was observed at 0.6 Gy. 49 references, 2 figures.

  7. Mutagenicity of inhalation anaesthetics studied by the sister chromatid exchange test in lymphocytes of patients and operating room personnel.

    PubMed

    Husum, B

    1987-06-01

    Retrospective studies have indicated that operating room personnel may have increased risks of spontaneous abortion, congenital malformations in offspring, and cancer (Cohen et al 1980, Buring et al 1985). Occupational exposure to waste anaesthetic gases may be responsible for these possible adverse health effects, but a cause-effect relationship has never been proved. Induction of changes in the DNA in the chromosomes leading to mutations may play a role in teratogenicity and carcinogenicity. Along with an increasing concern in society regarding occupational diseases and working and living environment in general, cytogenetic methods have been developed for rapid detection of potential mutagenicity in vitro of chemical agents. One such method is the SCE test, which is based on examination of sister chromatid exchanges (SCEs), i.e. exchanges of chromatid-segments between the two chromatids in a chromosome, during cell replication. SCEs are not mutations, but an increased frequency of SCE is a sensitive indicator of exposure to agents that are capable of producing damage to the DNA and thus possibly mutations. In vitro tests like the SCE test are very useful for evaluation of specific chemical agents, which may be added to the culture in known concentrations. In studies of possible hazards from chemical agents in the working or living environment, the exposure is often poorly defined. Also, biotransformation may be different in different species, and the duration and the level of the exposure may play a role. Examination of SCEs is, therefore, increasingly performed directly on human lymphocytes from peripheral blood. Thus, although the examination of SCEs is still performed in vitro, the exposure has taken place in vivo. Increased SCE levels are then regarded as a non-specific indicator that the donor has been exposed to potentially mutagenic agents in the environment. The author and his associates used the SCE test to investigate the possible mutagenicity of

  8. Induction of sister chromatid exchange in preimplantation mouse embryos in vitro by /sup 3/H-thymidine or ultraviolet light in combination with caffeine

    SciTech Connect

    Mueller, W.U.S.; Spindle, A.

    1986-01-01

    Preimplantation mouse embryos were exposed in vitro to /sup 3/H-thymidine (25, 100, or 250 Bq/ml) or ultraviolet (UV) light (1.35 or 4.05 J/m2), either alone or in combination with caffeine (1 mM with /sup 3/H-thymidine and 0.5 mM with UV light). Exposure to /sup 3/H-thymidine lasted for 2 days, from the two-cell stage to the late morula/early blastocyst stage, and UV radiation was applied acutely at the late morula/early blastocyst stage. The effects were quantified by the sister chromatid exchange (SCE) assay. All three agents induced SCEs when used singly. /sup 3/H-thymidine was effective in inducing SCEs only at 250 Bq/ml, whereas UV light was effective at both fluences. Although caffeine did not induce SCEs when it was added before exposure to bromodeoxyuridine (BrdUrd), which is used to visualize SCEs, it did induce SCEs when present during the entire culture period (/sup 3/H-thymidine experiments) or during incubation in BrdUrd (UV experiments). Caffeine markedly enhanced the SCE-inducing effect of UV light but did not influence the effect of /sup 3/H-thymidine.

  9. Dose--response of initial G2-chromatid breaks induced in normal human fibroblasts by heavy ions

    NASA Technical Reports Server (NTRS)

    Kawata, T.; Durante, M.; Furusawa, Y.; George, K.; Takai, N.; Wu, H.; Cucinotta, F. A.; Dicello, J. F. (Principal Investigator)

    2001-01-01

    PURPOSE: To investigate initial chromatid breaks in prematurely condensed G2 chromosomes following exposure to heavy ions of different LET. MATERIAL AND METHODS: Exponentially growing human fibroblast cells AG1522 were irradiated with gamma-rays, energetic carbon (13 keV/ microm, 80 keV/microm), silicon (55 keV/microm) and iron (140 keV/microm, 185keV/microm, 440keV/microm) ions. Chromosomes were prematurely condensed using calyculin-A. Initial chromatid-type and isochromatid breaks in G2 cells were scored. RESULTS: The dose response curves for total chromatid breaks were linear regardless of radiation type. The relative biological effectiveness (RBE) showed a LET-dependent increase, peaking around 2.7 at 55-80keV/microm and decreasing at higher LET. The dose response curves for isochromatid-type breaks were linear for high-LET radiations, but linear-quadratic for gamma-rays and 13 keV/microm carbon ions. The RBE for the induction of isochromatid breaks obtained from linear components increased rapidly between 13keV/microm (about 7) and 80keV/microm carbon (about 71), and decreased gradually until 440 keV/microm iron ions (about 66). CONCLUSIONS: High-LET radiations are more effective at inducing isochromatid breaks, while low-LET radiations are more effective at inducing chromatid-type breaks. The densely ionizing track structures of heavy ions and the proximity of sister chromatids in G2 cells result in an increase in isochromatid breaks.

  10. Effect of oral administration of mutagens found in food on the frequency of sister chromatid exchanges in the colonic epithelium of mice

    SciTech Connect

    Couch, D.B.; Stuart, E.; Heddle, J.A.

    1987-01-01

    Epidemiological studies indicate there is a link between dietary factors and the incidence of colon cancer, and it has been suggested mutagens in foods might be responsible for initiating the carcinogenic process. Some food mutagens are formed during the cooking process. For example, certain heterocyclic amines, including Trp-P-2 (3-amino-1-methyl-5H-pyrido(4,3-n) indole) and MeIQ (2-amino-3,4-dimethylimidazo(4,5-f)quinoline), which have been isolated from broiled meat and fish at low (ng/g) levels, are extremely potent mutagens in the Ames Salmonella/microsome test and can induce mutation in cultured mammalian cells as well. Other mutagens in foods are natural products; quercetin, a flavanoid widely distributed in plant products, is mutagenic to Salmonella and cultured mammalian cells. As most of the evidence implicating substance in food as mutagenic carcinogens comes from in vitro studies, it is of interest to determine whether these compounds can also exert genotoxic effects in vivo, particularly in colonic tissue. The ability to induce nuclear aberrations in vivo in murine colonic epithelial tissue has been suggested to be a property of colon carcinogens specifically, and several mutagens found in cooked food, including MeIQ and Trp-P-2, have been found to produce such nucleotoxicity. The authors report here tests of the ability of MeIQ, Trp-P-2, and quercetin to induce sister chromatid exchanges (SCEs) in the colonic epithelium of mice.

  11. Effects of coal combustion products and metal compounds on sister chromatid exchange (SCE) in a macrophagelike cell line.

    PubMed

    Andersen, O

    1983-01-01

    Investigations of genotoxic effects of particles have almost exclusively been performed by organic extraction, while direct investigations in cells capable of engulfing particles have only been performed in few cases. Thus, in most studies, the eventual effects of particle-associated metal compounds have remained undiscovered. The present study attempted direct measurement of genotoxic effects of particulate coal combustion products by using the P388D(1) macrophage cell line. The capability of these cells for phagocytosis was demonstrated with insoluble particles. The sister chromatid exchange (SCE) test was used for measuring genotoxic effects of test compounds. Dimethylnitrosamine and benzo(a)pyrene did not increase SCE, indicating that the P388D(1) cell line has lost the capacity for metabolism of latent organic carcinogens, reducing the value of these cells for evaluating genotoxic effects of complex particles. Indirect evidence has been obtained that the cell line may be infected with a virus. Thus, interactions between virus and test compound may lead to erroneous results. This should be kept in mind during evaluation of the results. The effects of metals with reported carcinogenic or mutagenic effects on SCE were compared in P388D(1) cells and human lymphocytes: NaAsO(2), CdCl(2), K(2)Cr(2)O(7), CoCl(2), CH(3)HgCl and MnSO(4) increased SCE in both cell systems. Pb(CH(3)COO)(2), BeSO(4) and NiSO(4) had a weak effect on SCE in P388D(1). Pb(CH(3)COO)(2) and NiSO(4), but not BeSO(4), increased SCE in human lymphocytes. Cr(CH(3)COO)(3) increased SCE in human lymphocytes at high concentration, but was a strong inducer of increased SCE in P388D(1) cells, which take up Cr(III) by phagocytosis. This suggests that the Cr(III) ion is an ultimate carcinogenic form of chromium. Generally P388D(1) cells and human lymphocytes respond to in vitro exposure to metals in agreement with reported mutagenic/carcinogenic effects of the metals. Of four precipitated coal fly ash

  12. In utero analysis of sister chromatid exchange: alterations in suscptibility to mutagenic damage as a function of fetal cell type and gestational age.

    PubMed Central

    Kram, D; Bynum, G D; Senula, G C; Bickings, C K; Schneider, E L

    1980-01-01

    Frequencies of baseline and cyclophosphamide-induced sister chromatid exchanges (SCE) were measured in mouse maternal and fetal cells between days 11 and 19 of gestation. Baseline levels of SCE did not vary as a function of gestational age in either the mother or fetus. Cyclophosphamide-induced SCE frequencies remained constant in maternal cells but declined dramatically in the fetus throughout the latter half of development. Because cyclophosphamide is a metabolically activated mutagen, a direct-acting drug, mitomycin C, was given on days 11 and 15 to determine if the decline in induced SCE levels seen with gestational results from alterations in activating enzymes. A similar decline in mitomycin C-induced SCE levels was noted in fetal tissues as a function of gestational age. Dose-response curves to cyclophosphamide performed on day 13 of gestation showed increases in SCE as a function of cyclophosphamide concentration in both the mother and the fetus. When mutagen-induced SCE levels were compared in different fetal organs, the direct-acting drugs (mitomycin C and daunomycin) were found to induce similar levels in all tissues. Cyclophosphamide, which is metabolically activated, induced higher SCE levels in fetal liver than in lung or gut. Whereas cyclophosphamide induced similar SCE levels in fetal and maternal cells on day 13 of gestation, daunomycin produced fetal SCE levels that were approximately 50% of maternal levels. Simultaneous measurement of the distribution of [14C]cyclophosphamide and [3H]daunomycin in maternal and fetal cells revealed that the lower SCE induction by daunomycin was probably due to decreased ability to cross the placental barrier. PMID:6933526

  13. G2-phase chromatid break kinetics in irradiated DNA repair mutant hamster cell lines using calyculin-induced PCC and colcemid-block.

    PubMed

    Bryant, Peter E; Mozdarani, Hossein; Marr, Christie

    2008-11-17

    We have investigated the role of the major pathways of DNA double-strand break (DSB) rejoining in the formation and kinetics of disappearance of chromatid breaks following irradiation in the G2 phase of the cell-cycle. We studied the responses of Chinese hamster cell lines xrs5, UV41 and irs1 with mutations in DNA repair genes XRCC5, ERCC4/XPF and XRCC2, involved in the non-homologous end-joining (NHEJ), single-strand annealing (SSA) and homologous recombination (HR) pathways of DSB rejoining respectively. We have used calyculin-induced PCC to study the kinetics of chromatid breaks in xrs5 and UV41 and wild-type CHOK1 cell line. xrs5 showed an elevated frequency of both spontaneous and radiation-induced chromatid breaks. However, the rate of disappearance of chromatid breaks with time was similar in xrs5 to that in its parental CHO cell line. The results with xrs5 firstly confirm our previous findings using the traditional colcemid-block technique, and secondly they demonstrate the independence of chromatid break kinetics of the radiation-induced cell-cycle checkpoint delay. The lack of correspondence between chromatid break kinetics and the deficiency in DSB rejoining in xrs5 argues strongly for an indirect involvement of DSB in the formation of chromatid breaks. The UV41 strain also showed similar chromatid break frequencies and kinetics to CHOK1 suggesting that the SSA pathway is not involved in the rejoining of DSB in the G2 phase of the cell-cycle. We found it not possible to use calyculin-induced PCC in V79-4 and irs1 cell lines. However, using colcemid block we show an elevation in both spontaneous and radiation-induced chromatid break frequency, and a similar rate of disappearance of G2 chromatid breaks with time after irradiation to its wild-type parental V79 line. Thus, deficiencies in two of the major pathways of DSB rejoining (NHEJ and HR) lead to elevated frequencies of chromatid breaks, but do not significantly influence the kinetics of their

  14. Absence of a synergistic effect between moderate-power radio-frequency electromagnetic radiation and adriamycin on cell-cycle progression and sister-chromatid exchange.

    PubMed

    Ciaravino, V; Meltz, M L; Erwin, D N

    1991-01-01

    In our laboratories we are conducting investigations of potential interactions between radio-frequency electromagnetic radiation (RFR) and chemicals that are toxic by different mechanisms to mammalian cells. The RFR is being tested at frequencies in the microwave range and at different power levels. We report here on the 1) ability of simultaneous RFR exposures to alter the distribution of cells in first and second mitoses from that after treatment by adriamycin alone, and 2) on the ability of simultaneous RFR exposure to alter the extent of sister chromatid exchanges (SCEs) induced by adriamycin alone. This chemical was selected because of its reported mechanism of action and because it is of interest in the treatment of cancer. In our studies, Chinese hamster ovary (CHO) cells were exposed for 2 h simultaneously to adriamycin and pulsed RFR at a frequency of 2,450 MHz and a specific absorption rate of 33.8 W/Kg. The maximal temperature (in the tissue-culture medium) was 39.7 +/- 0.2 degrees C. The experiments were controlled for chemical and RFR exposures, as well as for temperature. Verified statistically, the data indicate that the RFR did not affect changes in cell progression caused by adriamycin, and the RFR did not change the number of SCEs that were induced by the adriamycin, which adriamycin is known to affect cells by damaging their membranes and DNA. PMID:1759979

  15. Comparison of 6-thioguanine-resistant mutation and sister chromatid exchanges in Chinese hamster V79 cells with forty chemical and physical agents

    SciTech Connect

    Nishi, Y.; Hasegawa, M.M.; Taketomi, M.; Ohkawa, Y.; Inui, N.

    1984-08-01

    The induction of sister chromatid exchanges (SCE) and mutation at the hypoxanthine-guanine phosphoribosyl transferase locus and toxicities of 40 different chemical and physical agents were examined on Chinese hamster V79 cells. These agents included mono-, di-, tri-, and polyfunctional alkylating agents, intercalators, gamma-rays, and UV light irradiation. Mutation was measured as resistance to 6-thioguanine and toxicity as loss of cell-plating efficiency. SCE were examined 29 hr after treatment. With the agents examined, a highly positive correlation existed between SCE-inducing and mutagenic potencies, when expressed as increase in the number per a unit dose over the control values. But the great difference of the ratios of mutagenic potencies versus SCE-inducing potencies among agents was observed, the maximal difference in the ratios being about 200-fold. The agents that showed the higher values of the ratio (agents producing more mutations than SCE) were bleomycin, cobalt-60 gamma-rays, all ethylating agents (N-ethyl-N-nitrosourea, N-ethyl-N'-nitro-N-nitrosoguanidine, ethyl methanesulfonate, and diethylsulfate), N-propyl-N-nitrosourea, N-butyl-N-nitrosourea, isopropyl methanesulfonate, intercalating acridine compounds (2-methoxy-6-chloro-9-(3-(ethyl-2-chloroethyl)aminopropylamino)-acridine X 2HCl and 2-methoxy-6-chloro-9-(3-(chloroethyl)-aminopropylamino)acridine 2HCl) and UV light at 254 nm.

  16. Effects of chronic exposure to 2, 3, 7, 8,-tetrachlorodibenzo-p-dioxin on sister chromatid exchange levels in peripheral lymphocytes of the rhesus monkey

    SciTech Connect

    Lim, M.; Jacobson-Kram, D.; Bowman, R.E.; Williams, J.R.

    1987-01-01

    Frequencies of sister chromatid exchanges and chromosomal aberrations were examined in peripheral lymphocytes of Rhesus monkeys that had been fed a diet containing 25 parts per trillion 2,3,7,8-tetrachlorodibenzo-p-dioxin for a period of 4 years. When compared to non-exposed control animals, no significant differences were noted for either of these cytogenetic end points. In addition, there was not a significant difference in sister chromatid exchange response to a challenge dose of mitomycin C in cells from 2,3,7,8-tetrachlorodibenzo-p-dioxin exposed animals compared to controls. The results confirm the lack of genotoxic effects associated with 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure.

  17. Sister chromatid exchange analysis to monitor genotoxic chemicals. March 1978-July 1989 (A Bibliography from Pollution Abstracts). Report for March 1978-July 1989

    SciTech Connect

    Not Available

    1990-04-01

    This bibliography contains citations concerning the use of the sister chromatid exchange (SCE) analysis for toxicological studies. SCE analysis are very sensitive measures of genotoxic damage to chromosomes. SCE toxicological studies analyzing ionizing radiation, chromium compounds, styrene, paint thinner, mercury, cigarette smoke, coal dust, fuel oil, insecticides, ethylene oxide, diesel exhaust, and polychlorinated biphenyls are discussed. SCE studies using both human and animal tissue cultures are described. (Contains 150 citations fully indexed and including a title list.)

  18. DNA single strand breakage, DNA adducts, and sister chromatid exchange in lymphocytes and phenanthrene and pyrene metabolites in urine of coke oven workers.

    PubMed Central

    Popp, W; Vahrenholz, C; Schell, C; Grimmer, G; Dettbarn, G; Kraus, R; Brauksiepe, A; Schmeling, B; Gutzeit, T; von Bülow, J; Norpoth, K

    1997-01-01

    OBJECTIVES: To investigate the specificity of biological monitoring variables (excretion of phenanthrene and pyrene metabolites in urine) and the usefulness of some biomarkers of effect (alkaline filter elution, 32P postlabelling assay, measurement of sister chromatid exchange) in workers exposed to polycyclic aromatic hydrocarbons (PAHs). METHODS: 29 coke oven workers and a standardised control group were investigated for frequencies of DNA single strand breakage, DNA protein cross links (alkaline filter elution assay), sister chromatid exchange, and DNA adducts (32P postlabelling assay) in lymphocytes. Phenanthrene and pyrene metabolites were measured in 24 hour urine samples. 19 different PAHs (including benzo(a)pyrene, pyrene, and phenanthrene) were measured at the workplace by personal air monitoring. The GSTT1 activity in erythrocytes and lymphocyte subpopulations in blood was also measured. RESULTS: Concentrations of phenanthrene, pyrene, and benzo(a)pyrene in air correlated well with the concentration of total PAHs in air; they could be used for comparisons of different workplaces if the emission compositions were known. The measurement of phenanthrene metabolites in urine proved to be a better biological monitoring variable than the measurement of 1-hydroxypyrene. Significantly more DNA strand breaks in lymphocytes of coke oven workers were found (alkaline filter elution assay); the DNA adduct rate was not significantly increased in workers, but correlated with exposure to PAHs in a semiquantitative manner. The number of sister chromatid exchanges was lower in coke oven workers but this was not significant; thus counting sister chromatid exchanges was not a good variable for biomonitoring of coke oven workers. Also, indications for immunotoxic influences (changes in lymphocyte subpopulations) were found. CONCLUSIONS: The measurement of phenanthrene metabolites in urine seems to be a better biological monitoring variable for exposure to PAHs than

  19. Increased sister chromatid exchange frequency in young women with breast cancer and in their first-degree relatives.

    PubMed

    Cefle, Kivanc; Ucur, Ali; Guney, Nese; Ozturk, Sukru; Palanduz, Sukru; Tas, Faruk; Asoglu, Oktar; Bayrak, Aysegul; Muslumanoglu, Mahmut; Aydiner, Adnan

    2006-11-01

    The well-known increased risk of breast cancer (BC) in first-degree relatives of patients with BC has been related to shared genetic factors including defective DNA repair, with loss of genomic integrity. On the other hand, it can be hypothesized that early-onset breast cancer is also associated with overburden of heritable factors leading to increased DNA injury. In this respect, we analyzed sister chromatid exchange frequency (SCE) in 20 women with breast cancer (all < or =40 years old), in their first-degree female relatives, and in 20 age-matched healthy females without a personal or family history of cancer. SCE was significantly increased (P < 0.05) in patients (7.17 +/- 1.81 per metaphase) and in their first-degree relatives (6.44 +/- 0.98), compared with controls (5.85 +/- 0.72). There was no difference in SCE frequency between patients and their first-degree relatives. We suggest that the increased SCE in patients reflects a genomic instability that may be operative in carcinogenesis. Further, genomic instability is shared also by first-degree relatives, although none of them had a history of breast cancer at the time of the study. PMID:17074593

  20. Sister chromatid exchanges and micronuclei in lymphocytes of operating room personnel occupationally exposed to enfluorane and nitrous oxide.

    PubMed

    Pasquini, R; Scassellati-Sforzolini, G; Fatigoni, C; Marcarelli, M; Monarca, S; Donato, F; Cencetti, S; Cerami, F M

    2001-01-01

    The objective of this article is to assess whether occupational exposure to anesthetics increases genotoxic risk. We investigated two cytogenetic biomarkers, sister chromatid exchanges (SCE) and micronuclei (MN), in the peripheral blood lymphocytes of 46 anesthesiologists (24 men), working in operating rooms and mostly exposed to enfluorane and nitrous oxide, and 66 controls (35 men), not exposed to chemicals and living in the same area. Contrary to what was expected, a lower frequency of SCE was found in male anesthesiologists than in controls. Smoking status was found to be positively associated with SCE frequency in each group, while no relation to age was evident. On the contrary, MN frequency was significantly higher in female, but not male, anesthesiologists than in controls. Age and smoking status did not modify the association. No relationship between MN frequency and duration of employment was found in anesthesiologists. Smoking status and mean number of cigarettes smoked per day in smokers were not associated with MN frequency in either anesthesiologists or in controls. MN analysis seems to be a sensitive index of possible genotoxic effects of occupational exposure to anesthesiologists, and women appear to be more susceptible to these effects than men. PMID:11394710

  1. Effect of low /sup 60/Co dose rates on sister chromatid exchange incidence in the benthic worm. Neanthes arenaceodentata

    SciTech Connect

    Harrison, F.L.; Rice, D.W. Jr.

    1981-10-13

    The usefulness of sister chromatid exchange (SCE) induction as a measure of low-level radiation effect was examined in a benthic marine worm, Neanthes arenaceodentata. Larvae were exposed to /sup 60/Co radiation for 12 to 24 h at total doses ranging from 0.5 to 309 R and at dose rates from 0.04 to 13 R/h. Animals exposed at intermediate dose rates (0.5, 0.6, 1.25, 2.0, and 2.5 R/h) had SCE frequencies per chromosome about twice that of those receiving no radiation (controls), whereas those exposed at the higher dose rates (7.0 and 13 R/h) had SCE frequencies lower than the controls. Animals exposed at the lower dose rates (0.04 and 0.1 R/h) had lower SCE frequencies than those exposed at intermediate dose rates (and higher SCE frequencies than controls). The length of chromosome pair number one differed among metaphase spreads and was used as an index of chromosome condensation in a given metaphase. Because there is a possibility that chromosome morphology may affect the ability to resolve SCEs, morphology will be monitored in future studies. A preliminary experiment was performed to assess the effects of 2.2 and 11.5 R/h for 24 h on growth and development. Larvae observed at 6 and 17 d after irradiation did not have significantly different numbers of abnormal larvae or survival rates.

  2. Chromosome aberration and sister chromatid exchange tests in Chinese hamster ovary cells in vitro III: Results with 27 chemicals

    SciTech Connect

    Gulati, D.K. ); Witt, K.; Anderson, B.; Zeiger, E.; Shelby, M.D. )

    1989-01-01

    Twenty-seven chemicals previously tested in rodent carcinogenicity assays were tested for induction of chromosomal aberrations (ABS) and sister chromatid exchanges (SCE) in Chinese hamster ovary (CHO) cells as part of a larger analysis of the correlation between results of in vitro genetic toxicity assays and carcinogenicity bioassays. Chemicals were tested up to toxic doses with and without exogenous metabolic activation. Seventeen of the chemicals tested were carcinogens; only two of these were negative for both ABS and SCE. Of the eight noncarcinogens tested, four were negative for both endpoints and four gave a positive response for at least one endpoint. Of the remaining two chemicals, one, diallylphthalate, gave an equivocal response in the bioassay and a positive response in these CHO cell cytogenetics tests. The other chemical, 2,4-toluene diisocyanate, was tested for carcinogenicity as a mixture with the 2,6-isomer; the mixture was carinogenic, but the cytogenetic test results for the 2,4-isomer were negative. Experiments with unsynchronized CHO cells demonstrated that mean SCE frequency increased with increasing culture time, and this may have been a factor in the positive results obtained for five chemicals in the SCE test under conditions of delayed harvest.

  3. Elevated frequency of sister chromatid exchanges of lymphocytes in sarin-exposed victims of the Tokyo sarin disaster 3 years after the event.

    PubMed

    Li, Qing; Hirata, Yukiyo; Kawada, Tomoyuki; Minami, Masayasu

    2004-09-01

    We previously reported that the frequency of sister chromatid exchanges (SCEs) among victims of the Tokyo subway sarin disaster was significantly higher than that of controls 2-3 months after the disaster. It has been reported that the victims were also exposed to the by-products generated during sarin synthesis, i.e., diisopropyl methylphosphonate (DIMP), diethyl methylphosphonate (DEMP) and N,N-diethylaniline (DEA) during the disaster and we previously found that DIMP, DEMP and DEA induced a significant SCE increase in human lymphocytes in vitro. To monitor the genetic aftereffects of the sarin exposure, SCEs of peripheral blood lymphocytes were measured in fire fighters and police officers involved in the disaster 3 years after the event. We found that the frequency of SCEs was still significantly higher in the exposed subjects than the controls, suggesting a risk of the genetic aftereffects of the sarin exposure. We further found a significant positive correlation between the frequency of SCEs and the inhibition of serum cholinesterase activity in the exposed subjects, suggesting that the elevated frequency of SCEs is related to the sarin exposure. On the other hand, there was no significant difference in natural killer activity between the exposed and the controls. PMID:15297034

  4. Chaetophractus villosus as a sentinel organism: Baseline values of mitotic index, chromosome aberrations and sister chromatid exchanges.

    PubMed

    Rossi, Luis Francisco; Luaces, Juan Pablo; Browne, Melanie; Chirino, Mónica Gabriela; Merani, María Susana; Mudry, Marta Dolores

    2016-01-15

    Sentinel species are useful tools for studying the deleterious effects of xenobiotics on wildlife. The large hairy armadillo (Chaetophractus villosus) is the most abundant and widely distributed mammal in Argentina. It is a long-lived, omnivorous, burrowing species, with fairly restricted home ranges. To evaluate the level of spontaneous genetic damage in this mammal, we determined the baseline values of several genotoxicity biomarkers. The study included 20 C. villosus adults of both sexes from eight pristine localities within its geographic distribution range. Genotoxicity analysis was performed on 72-h lymphocyte cultures, using mitomycin C as positive control. We obtained the baseline values of mitotic index (MI=10.52±0.30 metaphases/total cells, n=20), chromosome aberrations (CA=0.13±0.22, n=20), sister chromatid exchanges (SCE)=6.55±0.26, n=6) and replication index (RI=1.66, n=6). MI and CA did not show significant differences (P>0.05) among localities or between sexes. No significant differences in MI, CA, SCE, and RI (P>0.05) were found between values from the pristine localities and historical data. There were significant differences in CA, SCE, and RI (P<0.05) between lymphocyte cultures from pristine localities and those exposed to mitomycin C. We propose the large hairy armadillo as a sentinel organism for environmental biomonitoring of genotoxic chemicals due to its abundance, easy manipulation, well-known biology, the fact that it is usually exposed to different mixtures and concentrations of environmental contaminants, and the baseline values of genetic damage characterized by MI, CA, SCE and RI as biomarkers. PMID:26778508

  5. Effects on sister chromatid exchange frequency of aldehyde dehydrogenase 2 genotype and smoking in vinyl chloride workers.

    PubMed

    Wong, R H; Wang, J D; Hsieh, L L; Du, C L; Cheng, T J

    1998-12-01

    Vinyl chloride monomer (VCM) is a human carcinogen. However, the exact mechanism of carcinogenesis remains unclear. VCM may be metabolized by cytochrome P450 2E1 (CYP2E1), aldehyde dehydrogenase 2 (ALDH2) and glutathione S-transferases (GSTs). Thus workers with inherited variant metabolic enzyme activities may have an altered risk of genotoxicity. This study was designed to investigate which risk factors might affect sister chromatid exchange (SCE) frequency in polyvinyl chloride (PVC) workers. Study subjects were 44 male workers from three PVC factories. Questionnaires were administered to obtain detailed histories of cigarette smoking, alcohol consumption, occupations, and medications. SCE frequency in peripheral lymphocytes was determined using a standardized method, and CYP2E1, GSTM1, GSTT1 and ALDH2 genotypes were identified by the polymerase chain reaction (PCR). Analysis revealed that smoking status and exposure to VCM were significantly associated with increased SCE frequency. The presence of ALDH2 1-2/2-2 genotypes was also significantly associated with an elevation of SCE frequency (9. 5 vs. 8.1, p<0.01). However, CYP2E1, GSTM1 or GSTT1 genotypes were not significantly associated with SCE frequency. When various genotypes were considered together, combination of CYP2E1 c1c2/c2c2 with ALDH2 1-2/2-2 showed an additive effect on SCE frequency. Similar results were also found for the combination of smoking with CYP2E1, or smoking with ALDH2. These results suggest that VCM workers with ALDH2 1-2/2-2 genotypes, who also smoke, may have increased risk of DNA damage. PMID:9838066

  6. Correlations of blood lead with DNA-protein cross-links and sister chromatid exchanges in lead workers.

    PubMed

    Wu, Fang-Yang; Chang, Pao-Wen; Wu, Chin-Ching; Kuo, Hsien-Wen

    2002-03-01

    Levels of sister chromatid exchanges (SCEs), high-SCE frequency cells (HFCs), DNA-protein cross-links (DPCs), blood lead (BLL), and zinc protoporphyrin (ZPP) were measured in peripheral blood from three groups. The lead workers were divided into two groups: a high BLL group (> or =15 microg/dl) and a low BLL group (<15 microg/dl). The control subjects were selected from an area that had not been contaminated with lead and had normal BLL and ZPP levels. In addition, exposure to airborne lead was measured for 11 lead workers, and the time-weighted average was shown to range from 0.19 to 10.32 mg/m(3). The BLL levels of 9 of 11 workers were >15 microg/dl, of which, 3 exceeded current exposure limits (> or =40 microg/dl). The BLL levels of all 11 controls were < 15 microg/dl. The average SCE and DPC values for the workers were 6.1 SCEs/cell and 1.9%, which were significantly higher (P < 0.01, Wilcoxon's test) than the value of 5.2 SCEs/cell and 1.1% for the control subjects. Lead workers had significantly higher BLL and ZPP levels than did the controls. Statistically significant increases in DPCs, SCEs, and HFCs were observed for the high-BLL group compared with the control group. The results of this study suggest that DPCs, SCEs, and HFCs are reliable biomarkers for monitoring workers exposed to lead and clearly indicate health effects from occupational exposure to lead. PMID:11895879

  7. Induction of sister chromatid exchanges and inhibition of cellular proliferation in vitro. I. Caffeine

    SciTech Connect

    Guglielmi, G.E.; Vogt, T.F.; Tice, R.R.

    1982-01-01

    While many agents have been examined for their ability to induce SCE's, complete dose-response information has often been lacking. We have reexamined the ability of one such compound - caffeine - to induce SCEs and also to inhibit cellular proliferation in human peripheral lymphocytes in vitro. An acute exposure to caffeine prior to the DNA synthetic period did not affect either SCE frequency or the rate of cellular proliferation. Chronic exposure to caffeine throughout the culture period lead to both a dose-dependent increase in SCEs (SCE/sub d/ or doubling dose = 2.4 mM; SCE/sub 10/ or the dose capable of inducing 10 SCE = 1.4 mM) and a dose-dependent inhibition of cellular proliferation (IC/sub 50/ or the 50% inhibition concentration = 2.6 mM). The relative proportion of first generation metaphase cells, an assessment of proliferative inhibiton, increased linearly with increasing caffeine concentrations. However, SCE frequency increased nonlinearly over the same range of caffeine concentrations. Examination of the ratio of nonsymmetrical to symmetrical SCEs in third generation metaphase cells indicated that caffeine induced SCEs in equal frequency in each of three successive generations. The dependency of SCE induction and cellular proliferative inhibition on caffeine's presence during the DNA synthetic period suggests that caffeine may act as an antimetabolite in normal human cells.

  8. Stimulation of Sister Chromatid Exchanges and Mutation by Aflatoxin B1-DNA Adducts in Saccharomyces cerevisiae Requires MEC1 (ATR), RAD53, and DUN1

    PubMed Central

    Fasullo, Michael; Sun, Mingzeng; Egner, Patricia

    2008-01-01

    The hepatocarcinogen aflatoxin B1 (AFB1) is a potent recombinagen but weak mutagen in the yeast Saccharomyces cerevisiae. AFB1 exposure induces DNA damage-inducible genes, such as RAD51 and those encoding ribonucleotide reductase (RNR), through a MEC1 (ATR homolog)-dependent pathway. Previous studies have indicated that MEC1 is required for both AFB1-associated recombination and mutation, and suggested that AFB1-DNA adducts are common substrates for recombination and mutagenesis. However, little is known about the downstream effectors of MEC1 required for genotoxic events associated with AFB1 exposure. Here we show that AFB1 exposure increases frequencies of RAD51-dependent unequal sister chromatid exchange (SCE) and activates Rad53 (CHK2). We found that MEC1, RAD53, and DUN1 are required for both AFB1-associated mutation and SCE. Deletion of SML1, which encodes an inhibitor of RNR, did not suppress the DUN1-dependent requirement for AFB1-associated genetic events, indicating that higher dNTP levels could not suppress the dun1 phenotype. We identified AFB1-DNA adducts and show that approximately the same number of adducts are obtained in both wild type and rad53 mutants. Since DUN1 is not required for UV-associated mutation and recombination, these studies define a distinct role for DUN1 in AFB1-associated mutagenesis and recombination. We speculate that AFB1-associated DNA adducts stall DNA replication, a consequence of which can either be mutation or recombination. PMID:18228255

  9. Possible synergistic effect of mercury and smoking on sister-chromatid-exchange (SCE) rates in humans

    SciTech Connect

    Mottironi, V.D.; Harrison, B.; Pollara, B.; Gooding, R.; Banks, S.

    1986-03-01

    The authors previously reported that exposure to mercury did not appear to cause DNA damage as measured by SCE. They have expanded these studies and have further defined smokers and nonsmokers in the mercury exposed population. Cytogenetic analyses were performed in 29 mercury exposed workers and in 26 controls. The SCE technique was applied to monitor the possible mutagenic effects of elemental and inorganic mercury in somatic cells of exposed workers from two plants that use a mercury electrolytic process to generate caustic soda and copper foil. The mercury levels in blood samples from the exposed workers showed a range of 6.69 to 103.90 ng/ml, with a mean of 26.90 ng/ml. The mercury levels for the controls ranged from 1.52 to 6.08 ng/ml, with a mean of 3.87 ng/ml. Mean duration of exposure was 8 years, with a range of 0.90 to 34.80 years. Results showed a significant increase in the number of SCE in exposed workers with high mercury levels as compared to controls. When exposed workers and controls were subdivided into smokers and nonsmokers, a significant increase in the number of SCE in smoking workers with either low or high mercury levels in their blood were also shown. The data suggest a mutagenic effect induced by mercury, which is further enhanced by smoking. Thus, mercury and smoking may exert a synergistic effect in the induction of SCE.

  10. Sister chromatid exchange assay. January 1978-April 1990 (A Bibliography from the NTIS data base). Report for January 1978-April 1990

    SciTech Connect

    Not Available

    1990-04-01

    This bibliography contains citations concerning use of the sister chromatid exchange (SCE) assay for toxicological studies. SCE assays are very sensitive measures of genotoxic damage to chromosomes. SCE toxicological studies analyzing vinyl carbamate, nerve gas, tritium, chlorofluorocarbons, sewage sludge, arsenic, ionizing radiation, ethylene oxide, microwave radiation, coal and oil fly ash, heavy metals, and sodium azide are discussed. SCE studies using both human and animal tissue cultures are described. SCE studies in the developing fetus, and improved SCE techniques are also described. (Contains 146 citations fully indexed and including a title list.)

  11. Analysis of chromosome damage by sister chromatid exchange (SCE) and redox homeostasis characterization on sheep flocks from Sardinian pasturelands.

    PubMed

    Genualdo, Viviana; Perucatti, Angela; Pauciullo, Alfredo; Iannuzzi, Alessandra; Incarnato, Domenico; Spagnuolo, Maria Stefania; Solinas, Nicolina; Bullitta, Simonetta; Iannuzzi, Leopoldo

    2015-09-15

    Over the last decades, an increase of pollutants of diverse origin (industrial, military, mining, etc.) was recorded in several areas of Sardinia Island. We report the results of a multidisciplinary and complementary study based on cytogenetic and physiological analyses. The data obtained show the effects of the environmental impact on six sheep flocks (Sardinian breed) grazing on natural pasturelands next to possible polluted areas and compared to three herds grazing in different areas far from those potentially contaminated and used as control. Sister chromatid exchange (SCE) test was used as cytogenetic test to analyze chromosomal damages and it was performed on peripheral blood samples collected from 129 adult sheep (age > 4 years) randomly selected from polluted (92 animals) and control (37 animals) areas. Two types of cell cultures were performed: without (normal cultures) and with the addition of 5-BrdU. SCE-mean values estimated over 35 cells counted for each animal were 8.65 ± 3.40, 8.10 ± 3.50, 8.05 ± 3.08, 7.42 ± 3.34, 9.28 ± 3.56 and 8.38 ± 3.29 in the exposed areas, whereas the average values were 7.86 ± 3.31 in the control group. Significant increases (P < 0.01) of SCEs were found in three investigated areas of Southern Sardinia. Furthermore, sheep of the same flocks were characterized for blood redox homeostasis in order to define the potential targets of oxidative damage and to identify biomarkers of the extent of animal exposure to environmental contaminants. The plasma levels of Asc, Toc and Ret were found to be significantly lower (P < 0.001) in exposed sheep (I, II, IV and V) than in the control group. TAC as well as GPx and SOD activities were higher in control than in the exposed groups (P < 0.001). Finally, plasma levels of N-Tyr, PC, and LPO were significantly lower (P < 0.001) in the control group than in the exposed groups. PMID:25984702

  12. Genotoxicity of the anticonvulsant drug phenytoin (PHT): a follow-up study of PHT-untreated epileptic patients. I. Sister chromatid exchange (SCE) analysis.

    PubMed

    Kaul, A; Goyle, S

    1999-01-01

    Phenytoin (PHT) is a widely prescribed antiepileptic drug. Its potential to interact with genetic material was investigated in a set of 30 epileptic patients (age 10-30 years) prior to and following the administration of PHT over a period of 9 months (grouped in a multiple of 3 months) and 40 control subjects in relation to age, sex, duration of drug therapy, and plasma concentration of PHT, using the sister chromatid exchange (SCE) frequency assay. Plasma levels of the phenytoin were measured by biochemical assay in epileptic patients before and after the PHT therapy. The peripheral blood lymphocytes were cultured and harvested at 72 h. The frequency of SCE was significantly higher (P < 0.001) in both age groups (10-20 and 21-30 years) for PHT-treated epileptics compared to PHT-untreated and control subjects. However, there were no considerable variations in SCE finding between the control and PHT-untreated patients. Between the two age groups, a significantly higher SCE frequency was observed in PHT-treated patients (P < 0.01) in the older age group (21-30 years). Mean SCE frequency did not differ between the male and female in the controls, PHT-untreated, or treated epileptics. Correlation between the plasma concentration of PHT and the incidence of SCE among 30 patients was insignificant. PHT monotherapy appears to have genotoxic effect as expressed by the induction of increased SCE rates in treated epileptics, while disease does not play any role in inducing genetic damage as shown by no difference in SCE frequencies between control subjects and PHT-untreated epileptic patients. PMID:10321411

  13. Use of a Ring Chromosome and Pulsed-Field Gels to Study Interhomolog Recombination, Double-Strand DNA Breaks and Sister-Chromatid Exchange in Yeast

    PubMed Central

    Game, J. C.; Sitney, K. C.; Cook, V. E.; Mortimer, R. K.

    1989-01-01

    We describe a system that uses pulsed-field gels for the physical detection of recombinant DNA molecules, double-strand DNA breaks (DSB) and sister-chromatid exchange in the yeast Saccharomyces cerevisiae. The system makes use of a circular variant of chromosome III (Chr. III). Meiotic recombination between this ring chromosome and a linear homolog produces new molecules of sizes distinguishable on gels from either parental molecule. We demonstrate that these recombinant molecules are not present either in strains with two linear Chr. III molecules or in rad50 mutants, which are defective in meiotic recombination. In conjunction with the molecular endpoints, we present data on the timing of commitment to meiotic recombination scored genetically. We have used x-rays to linearize circular Chr. III, both to develop a sensitive method for measuring frequency of DSB and as a means of detecting double-sized circles originating in part from sister-chromatid exchange, which we find to be frequent during meiosis. PMID:2693206

  14. Use of a ring chromosome and pulsed-field gels to study interhomolog recombination, double-strand DNA breaks and sister-chromatid exchange in yeast

    SciTech Connect

    Game, J.C. ); Sitney, K.C.; Cook, V.E.; Mortimer, R.K. )

    1989-12-01

    The authors describe a system that uses pulsed-field gels for the physical detection of recombinant DNA molecules, double-strand DNA breaks (DSB) and sister-chromatid exchange in the yeast Saccharomyces cerevisiae. The system makes use of a circular variant of chromosome II (Chr. III). Meiotic recombination between this ring chromosome and a linear homolog produces new molecules of sizes distinguishable on gels from either parental molecule. They demonstrate that these recombinant molecules are not present either in strains with two linear Chr. III molecules or in rad50 mutants, which are defective in meiotic recombination. In conjunction with the molecular endpoints. They present data on the timing of commitment to meiotic recombination scored genetically. They have used x-rays to linearize circular Chr. III, both to develop a sensitive method for measuring frequency of DSB and as a means of detecting double-size circles originating in part from sister-chromatid exchange, which they find to be frequent during meiosis.

  15. Sister chromatid exchanges, hyperdiploidy and chromosomal rearrangements studied in cells from melanoma-prone individuals belonging to families with the dysplastic nevus syndrome.

    PubMed

    Jaspers, N G; Roza-de Jongh, E J; Donselaar, I G; Van Velzen-Tillemans, J T; van Hemel, J O; Rümke, P; van der Kamp, A W

    1987-01-01

    Cytogenetic investigations were performed on 25 individuals belonging to six melanoma-prone families with multiple melanocytic lesions (the dysplastic nevus syndrome, DNS). Patients having DNS with or without a history of melanoma were compared with clinically normal relatives and unrelated normal controls. The results indicate normal frequencies of hyperdiploidy and spontaneous sister chromatid exchanges in the fibroblasts of all individuals studied. Karyotypic analyses were carried out on the members of one family. The patients with DNS had a normal constitutional karyotype. In lymphocytes or fibroblasts from five patients, however, increased frequencies of cells with random chromosomal rearrangements were observed. These abnormalities, mainly translocations and inversions, were not found in two of the patients' spouses and in six clinically normal relatives. In the fibroblast cultures considerable clonal selection of cytogenetically abnormal cells occurred. PMID:3791172

  16. Mutagenicity studies on herring gulls from different locations on the Great Lakes. I. Sister chromatid exchange rates in herring-gull embryos.

    PubMed

    Ellenton, J A; McPherson, M F

    1983-01-01

    Unincubated herring-gull (Larus argentatus) eggs were collected from five colonies on the Great Lakes Basin and from one relatively pollutant-clean colony on the Atlantic coast. Eggs were incubated at 38 degrees C with 55% relative humidity, and sister chromatid exchange (SCE) levels were measured in 7-d embryos. For all of the colonies, the average SCE/chromosome frequency ranged from 0.069 to 0.101; however, no significant differences were found. Organochlorine analysis was carried out on egg homogenates for each colony, to determine the levels of several contaminants. There were no relationships found between any of the contaminant levels and the SCE frequencies. The study indicates that either the contaminants present in the herring-gull eggs are not having any genetic effects on the embryos or, alternatively, that there may be genetic damage that measurement of SCEs in the 7-d embryo is unable to detect. PMID:6655738

  17. Effects of radiofrequency radiation and simultaneous exposure with mitomycin C on the frequency of sister chromatid exchanges in Chinese hamster ovary cells

    SciTech Connect

    Ciaravino, V.; Meltz, M.L.; Erwin, D.N.

    1987-01-01

    Chinese hamster ovary (CHO) cells were exposed for 2 hr with and without mitomycin C (MMC) (1 X 10(-8)M) to pulsed wave radiofrequency radiation (RFR) at 2450 MHz. The repetition rate of 25,000 pulses per sec (pps), pulse width of 10 microseconds, and exposure geometry used, resulted in a specific absorption rate (SAR) of 33.8 W/kg. The following exposure regimens were used: a 37 degrees C water bath control; a water bath temperature control (TC) in which the continuously monitored medium temperature closely followed the temperature rise in the RFR-exposed flasks; and the RFR-exposed cells in a water bath set at 37 degrees C prior to exposure. RFR exposure resulted in a maximum cell culture medium temperature of 39.2 degrees C. In the absence of MMC, there was no significant increase in sister chromatid exchange (SCE) in the RFR-exposed or TC groups over that of the 37 degrees C control. When a simultaneous treatment of RFR and MMC occurred there was no statistical difference in SCE frequency from that caused by chemical treatment alone.

  18. Effects of radiofrequency radiation and simultaneous exposure with mitomycin C on the frequency of sister chromatid exchanges in Chinese hamster ovary cells

    SciTech Connect

    Ciaravino, V.; Meltz, M.L.; Erwin, D.N.

    1987-01-01

    Chinese hamster ovary (CHO) cells were exposed for 2 hr with and without mitomycin C (MMC) to pulsed wave radiofrequency radiation (RFR) at 2450 MHz. The repetition rate of 25,000 pulses per sec (pps), and exposure geometry used, resulted in a specific absorption rate (SAR) of 33.8 W/kg. The following exposure regimens were used: 1) a 37 C water bath control; 2) a water bath temperature control (TC) in which the continuously monitored medium temperature closely followed teh temperature rise in the RFR-exposed flasks; and 3) the RFR-exposed cells in a water bath set at 37 C prior to exposure. RFR exposure resulted in a maximum cell culture medium temperature of 39.2 C. In the absence of MMC, there was no significant increase in sister chromatid exchange (SCE) in the RFR-exposed or TC groups over that of teh 37 C control. When a simultaneous treatment of RFR and MMC occurred there was no statistical difference in SCE frequency from that caused by chemical treatment alone.

  19. Association of Polymorphisms of Phase I Metabolizing Genes with Sister Chromatid Exchanges in Occupational Workers Exposed to Toluene Used in Paint Thinners

    PubMed Central

    Priya, Kanu; Yadav, Anita; Kumar, Neeraj; Gulati, Sachin; Aggarwal, Neeraj; Gupta, Ranjan

    2015-01-01

    This study investigated genetic damage in paint workers mainly exposed to toluene as it is a major solvent used in paint thinners. Sister chromatid exchange (SCE) assay was used as biomarker of genotoxicity. Blood samples were collected from 30 paint workers and 30 control subjects matched with respect to age and other confounding factors except for exposure to toluene. SCE frequency was found to be significantly higher in paint workers (4.81 ± 0.92) as compared to control individuals (1.73 ± 0.54) (p < 0.05). We also investigated influence of polymorphisms of CYP2E1 and CYP1A1m2 genes on SCE frequency. Our results showed that there was significant increase in frequencies of SCE among the mutant genotypes of CYP2E1 and CYP1A1m2 as compared to wild genotypes. Our study indicated that long term exposure of toluene can increase genotoxic risk in paint workers. PMID:26688756

  20. Variation in the human lymphocyte sister chromatid exchange frequency as a function of time: results of daily and twice-weekly sampling

    SciTech Connect

    Tucker, J.D.; Christensen, M.L.; Strout, C.L.; McGee, K.A.; Carrano, A.V.

    1987-01-01

    The variation in lymphocyte sister chromatid exchange (SCE) frequency was investigated in healthy nonsmokers who were not taking any medication. Two separate studies were undertaken. In the first, blood was drawn from four women twice a week for 8 weeks. These donors recorded the onset and termination of menstruation and times of illness. In the second study, blood was obtained from two women and two men for 5 consecutive days on two separate occasions initiated 14 days apart. Analysis of the mean SCE frequencies in each study indicated that significant temporal variation occurred in each donor, and that more variation occurred in the longer study. Some of the variation was found to be associated with the menstrual cycle. In the daily study, most of the variation appeared to be random, but occasional day-to-day changes occurred that were greater than those expected by chance. To determine how well a single SCE sample estimated the pooled mean for each donor in each study, the authors calculated the number of samples that encompassed that donor's pooled mean within 1 or more standard errors. For both studies, about 75% of the samples encompassed the pooled mean within 2 standard errors. An analysis of high-frequency cells (HFCs) was also undertaken. The results for each study indicate that the proportion of HFCs, compared with the use of Fisher's Exact test, is significantly more constant than the means, which were compared by using the t-test. These results coupled with our previous work suggest that HFC analysis may be the method of choice when analyzing data from human population studies.

  1. Induction of micronuclei and sister chromatid exchanges by polycyclic and N-heterocyclic aromatic hydrocarbons in cultured human lymphocytes

    SciTech Connect

    Warshawsky, D.; Livingston, G.K.; LaDow, K.

    1995-12-31

    Many natural environments are contaminated with carcinogenic polycyclic aromatic hydrocarbons (PAHs) and N-heterocyclic aromatic hydrocarbons (NHAs) as complex mixtures of coal tar, petroleum, and shale oil. These potentially hazardous substances are prevalent at many former tar production and coal gasification sites. Three polycyclic [benzo(a)pyrene (BaP), benz(a)anthracene (BAA), and 7, 12-dimethylbenz(a)anthracene (DMBA)] and two N-heterocyclic [7H-dibenzo(c,g)carbazole (DBC), and dibenz(a,j)acridine (DBA)] aromatic hydrocarbons were analyzed for cytotoxic and genotoxic effects on human lymphocytes. All of these polyaromatic compounds are normally present in the environment, except for DMBA. Lymphocytes from healthy donors were isolated from whole blood. The 5-ring polycyclic aromatic BaP consistently induced micronuclei in a linear dose-dependent manner with doses from 0.1-10.0 {mu}g/ml, whereas the 4-ring compounds (BAA and DMBA) had no effect on the induction of micronuclei above controls except at 5 and 10 {mu}g/ml. Of the two N-heterocyclic compounds DBC produced a significant increase in micronuclei in lymphocytes, but the dose response tended to plateau above 0.1 {mu}g/ml. DBA showed an effect on the frequency of micronuclei above controls only at high doses of 5 and 10 {mu}g/ml. The average background frequency of micronuclei for 7 lymphocyte donors averaged 3.1 per 1,000 stimulated cells, whereas the average frequency of micronuclei at 10 {mu}g/ml BaP was 36.8 per 1,000 stimulated cells. The lowest effective dose in 2 donors for BaP occurred at 0.1 {mu}g/ml. 61 refs., 2 figs., 6 tabs.

  2. Cell elongation is an adaptive response for clearing long chromatid arms from the cleavage plane

    PubMed Central

    Kotadia, Shaila; Montembault, Emilie; Sullivan, William

    2012-01-01

    Chromosome segregation must be coordinated with cell cleavage to ensure correct transmission of the genome to daughter cells. Here we identify a novel mechanism by which Drosophila melanogaster neuronal stem cells coordinate sister chromatid segregation with cleavage furrow ingression. Cells adapted to a dramatic increase in chromatid arm length by transiently elongating during anaphase/telophase. The degree of cell elongation correlated with the length of the trailing chromatid arms and was concomitant with a slight increase in spindle length and an enlargement of the zone of cortical myosin distribution. Rho guanine-nucleotide exchange factor (Pebble)–depleted cells failed to elongate during segregation of long chromatids. As a result, Pebble-depleted adult flies exhibited morphological defects likely caused by cell death during development. These studies reveal a novel pathway linking trailing chromatid arms and cortical myosin that ensures the clearance of chromatids from the cleavage plane at the appropriate time during cytokinesis, thus preserving genome integrity. PMID:23185030

  3. Enhanced G2 chromatid radiosensitivity in dyskeratosis congenita fibroblasts.

    PubMed Central

    DeBauche, D M; Pai, G S; Stanley, W S

    1990-01-01

    Dyskeratosis congenita (DC) is an inherited disorder characterized by reticular pigmentation of the skin, dystrophic nails, mucosal leukoplakia, and a predisposition to cancer in early adult life. In the majority of cases, DC is an X-linked recessive trait. However, one or more autosomal form(s) of DC may exist. Although excessive spontaneous chromatid breakage has been reported in DC, it is not a consistent cytological marker for this disorder. We examined the frequency and specificity of X-irradiation-induced G2 chromatid breakage in fibroblasts from three unrelated DC patients (two males and one female). Metaphase cells from DC patients had significantly more chromatid breaks (16-18-fold and 17-26-fold at 50 and 100 rad X-irradiation, respectively) and chromatid gaps (10-12-fold and 6-7-fold at 50 and 100 rad, respectively) than those from two different controls. Analysis of banded chromosomes revealed a nonrandom distribution of chromatid aberrations in DC but not in controls, a distribution corresponding to some of the known breakpoints for cancer-specific rearrangements, constitutive fragile sites, and/or loci for cellular proto-oncogenes. The significance of this finding for cancer predisposition in DC patients is uncertain, but the increased susceptibility of X-irradiation-induced chromatid breakage may serve as a cellular marker of diagnostic value. PMID:2301400

  4. Analysis of chromosomal aberrations, sister-chromatid exchanges and micronuclei in peripheral lymphocytes of pharmacists before and after working with cytostatic drugs.

    PubMed

    Roth, S; Norppa, H; Järventaus, H; Kyyrönen, P; Ahonen, M; Lehtomäki, J; Sainio, H; Sorsa, M

    1994-12-01

    The frequencies of chromosome aberrations, SCEs and micronuclei (cytokinesis-block method) in blood lymphocytes were compared among six nonsmoking female pharmacists before and after 1 year of working with cytostatic drugs. All possible precautions were taken to avoid exposure to cytostatics, including proper protective clothing and a monitored, negative-pressured working environment with vertical laminar flow cabinet. As referents, an age-matched group of six nonsmoking female hospital workers not dealing with cytostatics was simultaneously sampled twice with the same time interval. The pharmacists showed a marginally higher mean frequency of SCEs/cell (6.3; P = 0.049) after the working period than 1 year earlier (5.8). On the other hand, the referents, with no obvious exposure, had a higher mean number of cells with chromatid-type aberrations, gaps excluded, in the second sampling (2.0%; P = 0.048) than in the first one (0.5%). In addition, a slight (P = 0.055) trend towards a higher frequency of micronucleated binucleate cells was observed in the second sampling for both the exposed and control subjects. As such findings suggest technical variation in the cytogenetic parameters, the small difference observed in SCEs for the pharmacists between the two samplings was probably not related to the cytostatics exposure. No statistically significant differences were observed for any of the cytogenetic parameters in comparisons between the pharmacists and the referents. The findings suggest that caution should be exercised in comparing results obtained from two different samplings in prospective cytogenetic studies. PMID:7527908

  5. Cell killing and chromatid damage in primary human bronchial epithelial cells irradiated with accelerated 56Fe ions

    NASA Technical Reports Server (NTRS)

    Suzuki, M.; Piao, C.; Hall, E. J.; Hei, T. K.

    2001-01-01

    We examined cell killing and chromatid damage in primary human bronchial epithelial cells irradiated with high-energy 56Fe ions. Cells were irradiated with graded doses of 56Fe ions (1 GeV/nucleon) accelerated with the Alternating Gradient Synchrotron at Brookhaven National Laboratory. The survival curves for cells plated 1 h after irradiation (immediate plating) showed little or no shoulder. However, the survival curves for cells plated 24 h after irradiation (delayed plating) had a small initial shoulder. The RBE for 56Fe ions compared to 137Cs gamma rays was 1.99 for immediate plating and 2.73 for delayed plating at the D10. The repair ratio (delayed plating/immediate plating) was 1.67 for 137Cs gamma rays and 1.22 for 56Fe ions. The dose-response curves for initially measured and residual chromatid fragments detected by the Calyculin A-mediated premature chromosome condensation technique showed a linear response. The results indicated that the induction frequency for initially measured fragments was the same for 137Cs gamma rays and 56Fe ions. On the other hand, approximately 85% of the fragments induced by 137Cs gamma rays had rejoined after 24 h of postirradiation incubation; the corresponding amount for 56Fe ions was 37%. Furthermore, the frequency of chromatid exchanges induced by gamma rays measured 24 h after irradiation was higher than that induced by 56Fe ions. No difference in the amount of chromatid damage induced by the two types of radiations was detected when assayed 1 h after irradiation. The results suggest that high-energy 56Fe ions induce a higher frequency of complex, unrepairable damage at both the cellular and chromosomal levels than 137Cs gamma rays in the target cells for radiation-induced lung cancers.

  6. In vitro induction of polyploidy and chromatid exchanges by culture medium extracts of natural rubbers compounded with 2-mercaptobenzothiazole as a positive control candidate for genotoxicity tests.

    PubMed

    Matsuoka, Atsuko; Isama, Kazuo; Tsuchiya, Toshie

    2005-11-01

    We tested extracts of custom-made natural rubber samples for cytotoxicity using V79 cells and for chromosome aberration (CA) induction using CHL cells in compliance with the Japanese guidelines for basic biological tests of medical materials and devices. The samples were formulated with a high level of 2-mercaptobenzothiazole (MBT) (A); a low level of MBT (B); or zinc dibutyldithiocarbamate (ZDBC) (C). In the CA test, MBT induced mainly polyploidy, including endoreduplication, and ZDBC induced structural CAs. In the cytotoxicity test, culture medium extracts of A, B, and C suppressed colony formation to 50% of the control value at 53.1%, 94.3%, and >100%, respectively. Culture medium extracts of sample A induced polyploidy and structural CAs in the absence of an exogenous metabolic activation system (S9 mix), but at lower concentrations in its presence, indicating the existence of other leachable promutagens. The extracts of sample B induced structural CAs at the highest concentration and only with S9 mix. Sample C was negative. The facts suggest that sample A may be a candidate for a positive control for genotoxicity tests. The high frequency of polyploidy induced by sample A was not predicted by MBT, suggesting the usefulness of the test for safety evaluation of medical devices. Numerical CAs induced by MBT and sample A are discussed. PMID:16088893

  7. COMPARISON OF SISTER-CHROMATID EXCHANGE IN MOUSE PERIPHERAL BLOOD LYMPHOCYTES EXPOSED IN VITRO AND IN VIVO TO PHOSPHORAMIDE MUSTARD AND 4-HYDROXYCLOPHOSPHAMIDE

    EPA Science Inventory

    The present study was designed to investigate the genotoxicity of 4-hydroxycyclophosphamide (4-OHCP) and phosphoramide mustard (PAM), both reactive metabolites of cyclophosphamide (CP), for possible differences in SCE-inducing activity in mouse T- and B-lymphocytes. ouse peripher...

  8. Genetic control of recombination partner preference in yeast meiosis. Isolation and characterization of mutants elevated for meiotic unequal sister-chromatid recombination.

    PubMed Central

    Thompson, D A; Stahl, F W

    1999-01-01

    Meiotic exchange occurs preferentially between homologous chromatids, in contrast to mitotic recombination, which occurs primarily between sister chromatids. To identify functions that direct meiotic recombination events to homologues, we screened for mutants exhibiting an increase in meiotic unequal sister-chromatid recombination (SCR). The msc (meiotic sister-chromatid recombination) mutants were quantified in spo13 meiosis with respect to meiotic unequal SCR frequency, disome segregation pattern, sporulation frequency, and spore viability. Analysis of the msc mutants according to these criteria defines three classes. Mutants with a class I phenotype identified new alleles of the meiosis-specific genes RED1 and MEK1, the DNA damage checkpoint genes RAD24 and MEC3, and a previously unknown gene, MSC6. The genes RED1, MEK1, RAD24, RAD17, and MEC1 are required for meiotic prophase arrest induced by a dmc1 mutation, which defines a meiotic recombination checkpoint. Meiotic unequal SCR was also elevated in a rad17 mutant. Our observation that meiotic unequal SCR is elevated in meiotic recombination checkpoint mutants suggests that, in addition to their proposed monitoring function, these checkpoint genes function to direct meiotic recombination events to homologues. The mutants in class II, including a dmc1 mutant, confer a dominant meiotic lethal phenotype in diploid SPO13 meiosis in our strain background, and they identify alleles of UBR1, INP52, BUD3, PET122, ELA1, and MSC1-MSC3. These results suggest that DMC1 functions to bias the repair of meiosis-specific double-strand breaks to homologues. We hypothesize that the genes identified by the class II mutants function in or are regulators of the DMC1-promoted interhomologue recombination pathway. Class III mutants may be elevated for rates of both SCR and homologue exchange. PMID:10511544

  9. Kinetics of chromatid break repair in G2-human fibroblasts exposed to low- and high-LET radiations

    NASA Technical Reports Server (NTRS)

    Kawata, T.; Durante, M.; George, K.; Furusawa, Y.; Gotoh, E.; Takai, N.; Wu, H.; Cucinotta, F. A.

    2001-01-01

    The purpose of this study is to determine the kinetics of chromatid break rejoining following exposure to radiations of different quality. Exponentially growing human fibroblast cells AG1522 were irradiated with gamma-rays, energetic carbon (290 MeV/u), silicon (490 MeV/u) and iron (200 MeV/u, 600 MeV/u). Chromosomes were prematurely condensed using calyculin A. Prematurely condensed chromosomes were collected after several post-irradiation incubation times, ranging from 5 to 600 minutes, and the number of chromatid breaks and exchanges in G2 cells were scored. The relative biological effectiveness (RBE) for initial chromatid breaks per unit dose showed LET dependency having a peak at 55 keV/micrometers silicon (2.4) or 80 keV/micrometers carbon particles (2.4) and then decreased with increasing LET. The kinetics of chromatid break rejoining following low- or high-LET irradiation consisted of two exponential components. Chromatid breaks decreased rapidly after exposure, and then continued to decrease at a slower rate. The rejoining kinetics was similar for exposure to each type of radiation, although the rate of unrejoined breaks was higher for high-LET radiation. Chromatid exchanges were also formed quickly.

  10. High-LET radiation-induced aberrations in prematurely condensed G2 chromosomes of human fibroblasts

    NASA Technical Reports Server (NTRS)

    Kawata, T.; Gotoh, E.; Durante, M.; Wu, H.; George, K.; Furusawa, Y.; Cucinotta, F. A.; Dicello, J. F. (Principal Investigator)

    2000-01-01

    PURPOSE: To determine the number of initial chromatid breaks induced by low- or high-LET irradiations, and to compare the kinetics of chromatid break rejoining for radiations of different quality. MATERIAL AND METHODS: Exponentially growing human fibroblast cells AG1522 were irradiated with gamma-rays, energetic carbon (290MeV/u), silicon (490MeV/u) and iron (200 and 600 MeV/u). Chromosomes were prematurely condensed using calyculin A. Chromatid breaks and exchanges in G2 cells were scored. PCC were collected after several post-irradiation incubation times, ranging from 5 to 600 min. RESULTS: The kinetics of chromatid break rejoining following low- or high-LET irradiation consisted of two exponential components representing a rapid and a slow time constant. Chromatid breaks decreased rapidly during the first 10min after exposure, then continued to decrease at a slower rate. The rejoining kinetics were similar for exposure to each type of radiation. Chromatid exchanges were also formed quickly. Compared to low-LET radiation, isochromatid breaks were produced more frequently and the proportion of unrejoined breaks was higher for high-LET radiation. CONCLUSIONS: Compared with gamma-rays, isochromatid breaks were observed more frequently in high-LET irradiated samples, suggesting that an increase in isochromatid breaks is a signature of high-LET radiation exposure.

  11. G2 Chromatid Damage and Repair Kinetics in Normal Human Fibroblast Cells Exposed to Low-or High-LET Radiation

    NASA Technical Reports Server (NTRS)

    Kawata, T.; Ito, H.; Uno, T.; Saito, M.; Yamamoto, S.; Furusawa, Y.; Durante, M.; George, K.; Wu, H.; Cucinotta, F. A.

    2004-01-01

    Radiation-induced chromosome damage can be measured in interphase using the Premature Chromosome Condensation (PCC) technique. With the introduction of a new PCC technique using the potent phosphatase inhibitor calyculin-A, chromosomes can be condensed within five minutes, and it is now possible to examine the early damage induced by radiation. Using this method, it has been shown that high-LET radiation induces a higher frequency of chromatid breaks and a much higher frequency of isochromatid breaks than low-LET radiation. The kinetics of chromatid break rejoining consists of two exponential components representing a rapid and a slow time constant, which appears to be similar for low- and high- LET radiations. However, after high-LET radiation exposures, the rejoining process for isochromatid breaks influences the repair kinetics of chromatid-type breaks, and this plays an important role in the assessment of chromatid break rejoining in the G2 phase of the cell cycle.

  12. Flow-induced vibration of component cooling water heat exchangers

    SciTech Connect

    Yeh, Y.S.; Chen, S.S. . Nuclear Engineering Dept.; Argonne National Lab., IL )

    1990-01-01

    This paper presents an evaluation of flow-induced vibration problems of component cooling water heat exchangers in one of Taipower's nuclear power stations. Specifically, it describes flow-induced vibration phenomena, tests to identify the excitation mechanisms, measurement of response characteristics, analyses to predict tube response and wear, various design alterations, and modifications of the original design. Several unique features associated with the heat exchangers are demonstrated, including energy-trapping modes, existence of tube-support-plate (TSP)-inactive modes, and fluidelastic instability of TSP-active and -inactive modes. On the basis of this evaluation, the difficulties and future research needs for the evaluation of heat exchangers are identified. 11 refs., 19 figs., 3 tabs.

  13. Commitment in Structurally Enabled and Induced Exchange Relations

    ERIC Educational Resources Information Center

    Lawler, Edward J.; Thye, Shane R.; Yoon, Jeongkoo

    2006-01-01

    Network structures both enable and constrain the development of social relations. This research investigates these features by comparing the development of commitments in structurally enabled and structurally induced exchange relations. We integrate ideas from the theory of relational cohesion and the choice process theory of commitment. In an…

  14. CYCLOPENTA[CD]PYRENE-INDUCED TUMORIGENICITY, KI-RAS CODON 12 MUTATIONS AND DNA ADDUCTS IN STRAIN A/J MOUSE LUNG

    EPA Science Inventory

    Cyclopenta[cd]pyrene (CPP) is a ubiquitous cyclopenta-fused polycyclic aromatic hydrocarbon. PP is highly genotoxic in bacterial and mammalian systems inducing gene mutations, sister-chromatid exchanges, and morphological transformation. PP is a mouse skin carcinogen, a mouse ski...

  15. Alternative meiotic chromatid segregation in the holocentric plant Luzula elegans

    PubMed Central

    Heckmann, Stefan; Jankowska, Maja; Schubert, Veit; Kumke, Katrin; Ma, Wei; Houben, Andreas

    2014-01-01

    Holocentric chromosomes occur in a number of independent eukaryotic lineages. They form holokinetic kinetochores along the entire poleward chromatid surfaces, and owing to this alternative chromosome structure, species with holocentric chromosomes cannot use the two-step loss of cohesion during meiosis typical for monocentric chromosomes. Here we show that the plant Luzula elegans maintains a holocentric chromosome architecture and behaviour throughout meiosis, and in contrast to monopolar sister centromere orientation, the unfused holokinetic sister centromeres behave as two distinct functional units during meiosis I, resulting in sister chromatid separation. Homologous non-sister chromatids remain terminally linked after metaphase I, by satellite DNA-enriched chromatin threads, until metaphase II. They then separate at anaphase II. Thus, an inverted sequence of meiotic sister chromatid segregation occurs. This alternative meiotic process is most likely one possible adaptation to handle a holocentric chromosome architecture and behaviour during meiosis. PMID:25296379

  16. Chromatin Structure and Radiation-Induced Intrachromosome Exchange

    NASA Technical Reports Server (NTRS)

    Mangala; Zhang, Ye; Hada, Megumi; Cucinotta, Francis A.; Wu, Honglu

    2011-01-01

    We have recently investigated the location of breaks involved in intrachromosomal type exchange events, using the multicolor banding in situ hybridization (mBAND) technique for human chromosome 3. In human epithelial cells exposed to both low- and high-LET radiations in vitro, intrachromosome exchanges were found to occur preferentially between a break in the 3p21 and one in the 3q11. Exchanges were also observed between a break in 3p21 and one in 3q26, but few exchanges were observed between breaks in 3q11 and 3q26, even though the two regions were on the same arm of the chromosome. To explore the relationships between intrachromosome exchanges and chromatin structure, we used probes that hybridize the three regions of 3p21, 3q11 and 3q26, and measured the distance between two of the three regions in interphase cells. We further analyzed fragile sites on the chromosome that have been identified in various types of cancers. Our results demonstrated that the distribution of breaks involved in radiation-induced intrachromosome aberrations depends upon both the location of fragile sites and the folding of chromatins

  17. Sister chromatid decatenation: bridging the gaps in our knowledge

    PubMed Central

    Broderick, Ronan; Niedzwiedz, Wojciech

    2015-01-01

    Faithful chromosome segregation is critical in preventing genome loss or damage during cell division. Failure to properly disentangle catenated sister chromatids can lead to the formation of bulky or ultrafine anaphase bridges, and ultimately genome instability. In this review we present an overview of the current state of knowledge of how sister chromatid decatenation is carried out, with particular focus on the role of TOP2A and TOPBP1 in this process. PMID:26266709

  18. The nature of high frequency sister chromatid exchange cells (HFCs).

    PubMed

    Ponzanelli, I; Landi, S; Bernacchi, F; Barale, R

    1997-09-01

    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 (S3) S phases. Fifty one of 900 lymphocytes from 37 healthy donors were defined as HFCs by calculating the 95th percentile of the distribution of SCEs in S1 + S2. 'Normal' cells presented almost the same number of SCEs after the first, second and third cell cycles (SCE averages of 2.43, 2.04 and 3.53 respectively). In contrast, HFCs showed a higher SCE count in S1, which decreased rapidly through the cycles and reached baseline level at S3 (SCE averages of 7.18, 4.29 and 3.45 respectively). This would suggest that the lesions responsible for the higher SCE frequency in HFCs were effectively removed after two cell cycles and strongly support the hypothesis that HFCs are lymphocytes which accumulate higher levels of DNA lesions through time. PMID:9379910

  19. SISTER CHROMATID EXCHANGE AND GENOTOXICITY MEASUREMENTS USING POLYCHAETE WORMS

    EPA Science Inventory

    Contaminants entering coastal marine environments may affect the genetic constitution of exposed organisms by causing shifts in gene pool composition through selective pressures or by acting directly on the genetic material to cause damage. he latter problem is referred to as gen...

  20. Proximity induced exchange interaction in graphene-YIG devices

    NASA Astrophysics Data System (ADS)

    Leutenantsmeyer, Johannes Christian; Kaverzin, Alexey; Wojtaszek, Magdalena; van Wees, Bart J.; Physics of Nanodevices Team

    The proximity of two materials with radically different properties can give rise to a new physical phenomenon present only in the direct vicinity to the interface. Graphene is a perfect candidate for observing proximity effects as being ultimately thin and therefore ultimately sensitive for such interactions. Ferromagnetism is one of the desired properties for spintronics applications of graphene. It is absent in the pristine state, however, one can artificially induce magnetic ordering by bringing graphene in the proximity of ferrimagnetic insulating material, such as yttrium iron garnet (YIG). In this work we show that a monolayer of graphene placed on top of YIG adopts the exchange interaction induced by YIG and thus becomes ferromagnetic even at room temperatures. The proximity induced exchange interaction results in an effective magnetic field that influences directly the spin transport in graphene seen in a spin precession measurements. We are able to fit the measured Hanle dependences with extended solutions of Bloch diffusion equations and extract the value of the effective exchange field that is around 200 mT. Our findings open up a new route for creating novel all graphene in plane spin valve devices for spintronics applications. European Union's Seventh Framework Programme n607904-13 Spinograph, n604391 Graphene Flagship, FOM, ZIAM.

  1. The Cohesin Subunit Rad21 Is Required for Synaptonemal Complex Maintenance, but Not Sister Chromatid Cohesion, during Drosophila Female Meiosis

    PubMed Central

    Lehner, Christian F.; Heidmann, Stefan K.

    2014-01-01

    Replicated sister chromatids are held in close association from the time of their synthesis until their separation during the next mitosis. This association is mediated by the ring-shaped cohesin complex that appears to embrace the sister chromatids. Upon proteolytic cleavage of the α-kleisin cohesin subunit at the metaphase-to-anaphase transition by separase, sister chromatids are separated and segregated onto the daughter nuclei. The more complex segregation of chromosomes during meiosis is thought to depend on the replacement of the mitotic α-kleisin cohesin subunit Rad21/Scc1/Mcd1 by the meiotic paralog Rec8. In Drosophila, however, no clear Rec8 homolog has been identified so far. Therefore, we have analyzed the role of the mitotic Drosophila α-kleisin Rad21 during female meiosis. Inactivation of an engineered Rad21 variant by premature, ectopic cleavage during oogenesis results not only in loss of cohesin from meiotic chromatin, but also in precocious disassembly of the synaptonemal complex (SC). We demonstrate that the lateral SC component C(2)M can interact directly with Rad21, potentially explaining why Rad21 is required for SC maintenance. Intriguingly, the experimentally induced premature Rad21 elimination, as well as the expression of a Rad21 variant with destroyed separase consensus cleavage sites, do not interfere with chromosome segregation during meiosis, while successful mitotic divisions are completely prevented. Thus, chromatid cohesion during female meiosis does not depend on Rad21-containing cohesin. PMID:25101996

  2. A Long Noncoding RNA Regulates Sister Chromatid Cohesion.

    PubMed

    Marchese, Francesco P; Grossi, Elena; Marín-Béjar, Oskar; Bharti, Sanjay Kumar; Raimondi, Ivan; González, Jovanna; Martínez-Herrera, Dannys Jorge; Athie, Alejandro; Amadoz, Alicia; Brosh, Robert M; Huarte, Maite

    2016-08-01

    Long noncoding RNAs (lncRNAs) are involved in diverse cellular processes through multiple mechanisms. Here, we describe a previously uncharacterized human lncRNA, CONCR (cohesion regulator noncoding RNA), that is transcriptionally activated by MYC and is upregulated in multiple cancer types. The expression of CONCR is cell cycle regulated, and it is required for cell-cycle progression and DNA replication. Moreover, cells depleted of CONCR show severe defects in sister chromatid cohesion, suggesting an essential role for CONCR in cohesion establishment during cell division. CONCR interacts with and regulates the activity of DDX11, a DNA-dependent ATPase and helicase involved in DNA replication and sister chromatid cohesion. These findings unveil a direct role for an lncRNA in the establishment of sister chromatid cohesion by modulating DDX11 enzymatic activity. PMID:27477908

  3. Anaphase chromatid motion: involvement of type II DNA topoisomerases.

    PubMed Central

    Duplantier, B; Jannink, G; Sikorav, J L

    1995-01-01

    Sister chromatids are topologically intertwined at the onset of anaphase: their segregation during anaphase is known to require strand-passing activity by type II DNA topoisomerase. We propose that the removal of the intertwinings involves at the same time the traction of the mitotic spindle and the activity of topoisomerases. This implies that the velocity of the chromatids is compatible with the kinetic constraints imposed by the enzymatic reaction. We show that the greatest observed velocities (about 0.1 microns s-1) are close to the theoretical upper bound compatible with both the diffusion rate (calculated here within a probabilistic model) and the measured reaction rate of the enzyme. PMID:8534830

  4. Precocious Sister Chromatid Separation (PSCS) in Cornelia de Lange Syndrome

    PubMed Central

    Kaur, Maninder; DeScipio, Cheryl; McCallum, Jennifer; Yaeger, Dinah; Devoto, Marcella; Jackson, Laird G.; Spinner, Nancy B.; Krantz, Ian D.

    2009-01-01

    The Cornelia de Lange syndrome (CdLS) (OMIM# 122470) is a dominantly inherited multisystem developmental disorder. The phenotype consists of characteristic facial features, hirsutism, abnormalities of the upper extremities ranging from subtle changes in the phalanges and metacarpal bones to oligodactyly and phocomelia, gastroesophageal dysfunction, growth retardation, and neurodevelopmental delay. Prevalence is estimated to be as high as 1 in 10,000. Recently, mutations in NIPBL were identified in sporadic and familial CdLS cases. To date, mutations in this gene have been identified in over 45% of individuals with CdLS. NIPBL is the human homolog of the Drosophila Nipped-B gene. Although its function in mammalian systems has not yet been elucidated, sequence homologs of Nipped-B in yeast (Scc2 and Mis4) are required for sister chromatid cohesion during mitosis, and a similar role was recently demonstrated for Nipped-B in Drosophila. In order to evaluate NIPBL role in sister chromatid cohesion in humans, metaphase spreads on 90 probands (40 NIPBL mutation positive and 50 NIPBL mutation negative) with CdLS were evaluated for evidence of precocious sister chromatid separation (PSCS). We screened 50 metaphases from each proband and found evidence of PSCS in 41% (compared to 9% in control samples). These studies indicate that NIPBL may play a role in sister chromatid cohesion in humans as has been reported for its homologs in Drosophila and yeast. PMID:16100726

  5. DNA damage tolerance branches out toward sister chromatid cohesion

    PubMed Central

    Branzei, Dana

    2016-01-01

    ABSTRACT Genome duplication is temporarily coordinated with sister chromatid cohesion and DNA damage tolerance. Recently, we found that replication fork-coupled repriming is important for both optimal cohesion and error-free replication by recombination. The mechanism involved has implications for the etiology of replication-based genetic diseases and cancer. PMID:27308553

  6. Thermal induced flow oscillations in heat exchangers for supercritical fluids

    NASA Technical Reports Server (NTRS)

    Friedly, J. C.; Manganaro, J. L.; Krueger, P. G.

    1972-01-01

    Analytical model has been developed to predict possible unstable behavior in supercritical heat exchangers. From complete model, greatly simplified stability criterion is derived. As result of this criterion, stability of heat exchanger system can be predicted in advance.

  7. Development of Design Criteria for Fluid Induced Structural Vibrations in Steam Generators and Heat Exchangers

    SciTech Connect

    Uvan Catton; Vijay K. Dhir; Deepanjan Mitra; Omar Alquaddoomi; Pierangelo Adinolfi

    2004-04-06

    Flow-induced vibration in heat exchangers has been a major cause of concern in the nuclear industry for several decades. Many incidents of failure of heat exchangers due to apparent flow-induced vibration have been reported through the USNRC incident reporting system. Almost all heat exchangers have to deal with this problem during their operation. The phenomenon has been studied since the 1970s and the database of experimental studies on flow-induced vibration is constantly updated with new findings and improved design criteria for heat exchangers.

  8. Securin and not CDK1/cyclin B1 regulates sister chromatid disjunction during meiosis II in mouse eggs.

    PubMed

    Nabti, Ibtissem; Reis, Alexandra; Levasseur, Mark; Stemmann, Olaf; Jones, Keith T

    2008-09-15

    Mammalian eggs remain arrested at metaphase of the second meiotic division (metII) for an indeterminate time before fertilization. During this period, which can last several hours, the continued attachment of sister chromatids is thought to be achieved by inhibition of the protease separase. Separase is known to be inhibited by binding either securin or Maturation (M-Phase)-Promoting Factor, a heterodimer of CDK1/cyclin B1. However, the relative contribution of securin and CDK/cyclin B1 to sister chromatid attachment during metII arrest has not been assessed. Although there are conditions in which either CDK1/cyclinB1 activity or securin can prevent sister chromatid disjunction, principally by overexpression of non-degradable cyclin B1 or securin, we find here that separase activity is primarily regulated by securin and not CDK1/cyclin B1. Thus the CDK1 inhibitor roscovitine and an antibody we designed to block the interaction of CDK1/cyclin B1 with separase, both failed to induce sister disjunction. In contrast, securin morpholino knockdown specifically induced loss of sister attachment, that could be restored by securin cRNA rescue. During metII arrest separase appears primarily regulated by securin binding, not CDK1/cyclin B1. PMID:18639540

  9. Sister chromatid junctions in the hyperthermophilic archaeon Sulfolobus solfataricus

    PubMed Central

    Robinson, Nicholas P; Blood, Katherine A; McCallum, Simon A; Edwards, Paul A W; Bell, Stephen D

    2007-01-01

    Although the Archaea exhibit an intriguing combination of bacterial- and eukaryotic-like features, it is not known how these prokaryotic cells segregate their chromosomes before the process of cell division. In the course of our analysis of the third replication origin in the archaeon Sulfolobus solfataricus, we identify and characterise sister chromatid junctions in this prokaryote. This pairing appears to be mediated by hemicatenane-like structures, and we provide evidence that these junctions persist in both replicating and postreplicative cells. These data, in conjunction with fluorescent in situ hybridisation analyses, suggest that Sulfolobus chromosomes have a significant period of postreplicative sister chromatid synapsis, a situation that is more reminiscent of eukaryotic than bacterial chromosome segregation mechanisms. PMID:17255945

  10. Compaction and segregation of sister chromatids via active loop extrusion

    PubMed Central

    Goloborodko, Anton; Imakaev, Maxim V; Marko, John F; Mirny, Leonid

    2016-01-01

    The mechanism by which chromatids and chromosomes are segregated during mitosis and meiosis is a major puzzle of biology and biophysics. Using polymer simulations of chromosome dynamics, we show that a single mechanism of loop extrusion by condensins can robustly compact, segregate and disentangle chromosomes, arriving at individualized chromatids with morphology observed in vivo. Our model resolves the paradox of topological simplification concomitant with chromosome 'condensation', and explains how enzymes a few nanometers in size are able to control chromosome geometry and topology at micron length scales. We suggest that loop extrusion is a universal mechanism of genome folding that mediates functional interactions during interphase and compacts chromosomes during mitosis. DOI: http://dx.doi.org/10.7554/eLife.14864.001 PMID:27192037

  11. EXCHANGE

    SciTech Connect

    Boltz, J.C.

    1992-09-01

    EXCHANGE is published monthly by the Idaho National Engineering Laboratory (INEL), a multidisciplinary facility operated for the US Department of Energy (DOE). The purpose of EXCHANGE is to inform computer users about about recent changes and innovations in both the mainframe and personal computer environments and how these changes can affect work being performed at DOE facilities.

  12. Merotelic attachments allow alignment and stabilization of chromatids in meiosis II oocytes.

    PubMed

    Kouznetsova, Anna; Hernández-Hernández, Abrahan; Höög, Christer

    2014-01-01

    The chromosome segregation process in human oocytes is highly error-prone, generating meiosis II (MII) oocytes with unbalanced chromatids that contribute to aneuploidy in offspring. This raises questions regarding the mechanism for transmission of chromatids and how chromatids evade the error correction mechanisms in MII oocytes. Here, we analyse the behaviour of chromatids in mouse MII oocytes. We find that chromatids align at the spindle equator at the metaphase stage of MII and that their presence does not obstruct entry into the anaphase stage. The alignment process is mediated by merotelic (bi-directional) microtubule-kinetochore attachments, revealing a multi-domain organization of the kinetochore of mammalian meiotic chromosomes. Our results suggest that biorientation of chromatids stabilize microtubule attachments at the kinetochores in a tension-dependent manner. Our results also suggest that merotelic attachments contribute to chromosome mis-segregation in wild-type MII oocytes. Thus, merotely is an important promoter of aneuploidy in mammalian oocytes. PMID:25007239

  13. Influence of ion bombardment induced patterning of exchange bias in pinned artificial ferrimagnets on the interlayer exchange coupling

    SciTech Connect

    Hoeink, V.; Schmalhorst, J.; Reiss, G.; Weis, T.; Lengemann, D.; Engel, D.; Ehresmann, A.

    2008-06-15

    Artificial ferrimagnets have many applications as, e.g., pinned reference electrodes in magnetic tunnel junctions. It is known that the application of ion bombardment (IB) induced patterning of the exchange bias coupling of a single layer reference electrode in magnetic tunnel junctions with He ions is possible. For applications as, e.g., special types of magnetic logic, a combination of the IB induced patterning of the exchange bias coupling and the implementation of an artificial ferrimagnet as reference electrode is desirable. Here, investigations for a pinned artificial ferrimagnet with a Ru interlayer, which is frequently used in magnetic tunnel junctions, are presented. It is shown that in this kind of samples the exchange bias can be increased or rotated by IB induced magnetic patterning with 10 keV He ions without a destruction of the antiferromagnetic interlayer exchange coupling. An IrMn/Py/Co/Cu/Co stack turned out to be more sensitive to the influence of IB than the Ru based artificial ferrimagnet.

  14. Investigating the Interplay between Sister Chromatid Cohesion and Homolog Pairing in Drosophila Nuclei.

    PubMed

    Senaratne, T Niroshini; Joyce, Eric F; Nguyen, Son C; Wu, C-Ting

    2016-08-01

    Following DNA replication, sister chromatids must stay connected for the remainder of the cell cycle in order to ensure accurate segregation in the subsequent cell division. This important function involves an evolutionarily conserved protein complex known as cohesin; any loss of cohesin causes premature sister chromatid separation in mitosis. Here, we examined the role of cohesin in sister chromatid cohesion prior to mitosis, using fluorescence in situ hybridization (FISH) to assay the alignment of sister chromatids in interphase Drosophila cells. Surprisingly, we found that sister chromatid cohesion can be maintained in G2 with little to no cohesin. This capacity to maintain cohesion is widespread in Drosophila, unlike in other systems where a reduced dependence on cohesin for sister chromatid segregation has been observed only at specific chromosomal regions, such as the rDNA locus in budding yeast. Additionally, we show that condensin II antagonizes the alignment of sister chromatids in interphase, supporting a model wherein cohesin and condensin II oppose each other's functions in the alignment of sister chromatids. Finally, because the maternal and paternal homologs are paired in the somatic cells of Drosophila, and because condensin II has been shown to antagonize this pairing, we consider the possibility that condensin II-regulated mechanisms for aligning homologous chromosomes may also contribute to sister chromatid cohesion. PMID:27541002

  15. Investigating the Interplay between Sister Chromatid Cohesion and Homolog Pairing in Drosophila Nuclei

    PubMed Central

    Senaratne, T. Niroshini; Joyce, Eric F.; Wu, C.-ting

    2016-01-01

    Following DNA replication, sister chromatids must stay connected for the remainder of the cell cycle in order to ensure accurate segregation in the subsequent cell division. This important function involves an evolutionarily conserved protein complex known as cohesin; any loss of cohesin causes premature sister chromatid separation in mitosis. Here, we examined the role of cohesin in sister chromatid cohesion prior to mitosis, using fluorescence in situ hybridization (FISH) to assay the alignment of sister chromatids in interphase Drosophila cells. Surprisingly, we found that sister chromatid cohesion can be maintained in G2 with little to no cohesin. This capacity to maintain cohesion is widespread in Drosophila, unlike in other systems where a reduced dependence on cohesin for sister chromatid segregation has been observed only at specific chromosomal regions, such as the rDNA locus in budding yeast. Additionally, we show that condensin II antagonizes the alignment of sister chromatids in interphase, supporting a model wherein cohesin and condensin II oppose each other’s functions in the alignment of sister chromatids. Finally, because the maternal and paternal homologs are paired in the somatic cells of Drosophila, and because condensin II has been shown to antagonize this pairing, we consider the possibility that condensin II-regulated mechanisms for aligning homologous chromosomes may also contribute to sister chromatid cohesion. PMID:27541002

  16. Reversible brain inactivation induces discontinuous gas exchange in cockroaches.

    PubMed

    Matthews, Philip G D; White, Craig R

    2013-06-01

    Many insects at rest breathe discontinuously, alternating between brief bouts of gas exchange and extended periods of breath-holding. The association between discontinuous gas exchange cycles (DGCs) and inactivity has long been recognised, leading to speculation that DGCs lie at one end of a continuum of gas exchange patterns, from continuous to discontinuous, linked to metabolic rate (MR). However, the neural hypothesis posits that it is the downregulation of brain activity and a change in the neural control of gas exchange, rather than low MR per se, which is responsible for the emergence of DGCs during inactivity. To test this, Nauphoeta cinerea cockroaches had their brains inactivated by applying a Peltier-chilled cold probe to the head. Once brain temperature fell to 8°C, cockroaches switched from a continuous to a discontinuous breathing pattern. Re-warming the brain abolished the DGC and re-established a continuous breathing pattern. Chilling the brain did not significantly reduce the cockroaches' MR and there was no association between the gas exchange pattern displayed by the insect and its MR. This demonstrates that DGCs can arise due to a decrease in brain activity and a change in the underlying regulation of gas exchange, and are not necessarily a simple consequence of low respiratory demand. PMID:23430991

  17. Mechanics of Sister Chromatids studied with a Polymer Model English</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Yang; Isbaner, Sebastian; Heermann, Dieter</p> <p>2013-10-01</p> <p>Sister <span class="hlt">chromatid</span> cohesion denotes the phenomenon that sister <span class="hlt">chromatids</span> are initially attached to each other in mitosis to guarantee the error-free distribution into the daughter cells. Cohesion is mediated by binding proteins and only resolved after mitotic chromosome condensation is completed. However, the amount of attachement points required to maintain sister <span class="hlt">chromatid</span> cohesion while still allowing proper chromosome condensation is not known yet. Additionally the impact of cohesion on the mechanical properties of chromosomes also poses an interesting problem. In this work we study the conformational and mechanical properties of sister <span class="hlt">chromatids</span> by means of computer simulations. We model both protein-mediated cohesion between sister <span class="hlt">chromatids</span> and chromosome condensation with a dynamic binding mechanisms. We show in a phase diagram that only specific link concentrations lead to connected and fully condensed <span class="hlt">chromatids</span> that do not intermingle with each other nor separate due to entropic forces. Furthermore we show that dynamic bonding between <span class="hlt">chromatids</span> decrease the Young's modulus compared to non-bonded <span class="hlt">chromatids</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19780068435&hterms=solar+hydrogen&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dsolar%2Bhydrogen','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19780068435&hterms=solar+hydrogen&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dsolar%2Bhydrogen"><span id="translatedtitle">The diurnal and solar cycle variation of the charge <span class="hlt">exchange</span> <span class="hlt">induced</span> hydrogen escape flux</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Maher, L. J.; Tinsley, B. A.</p> <p>1978-01-01</p> <p>On the basis of ion temperature and density data at specific points and times in June 1969 provided by the OGO 6 satellite, and altitude profiles of the ion and electron temperature and concentration provided by the Arecibo radar facility over the period February 1972-April 1974, the diurnal and solar cycle variation of the charge-<span class="hlt">exchange-induced</span> hydrogen escape flux was investigated. It was calculated that for low to moderate solar activity at Arecibo, the diurnal ratio of the maximum-to-minimum charge-<span class="hlt">exchange-induced</span> hydrogen escape flux was approximately 6 with a peak around noon and a minimum somewhere between 0100 and 0300 h LT. This study of a limited amount of OGO 6 and Arecibo data seems to indicate that the charge-<span class="hlt">exchange-induced</span> hydrogen escape flux increases as the F(10.7) flux increases for low to moderate solar activity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27084937','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27084937"><span id="translatedtitle">Transcription facilitates sister <span class="hlt">chromatid</span> cohesion on chromosomal arms.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bhardwaj, Shweta; Schlackow, Margarita; Rabajdova, Miroslava; Gullerova, Monika</p> <p>2016-08-19</p> <p>Cohesin is a multi-subunit protein complex essential for sister <span class="hlt">chromatid</span> cohesion, gene expression and DNA damage repair. Although structurally well studied, the underlying determinant of cohesion establishment on chromosomal arms remains enigmatic. Here, we show two populations of functionally distinct cohesin on chromosomal arms using a combination of genomics and single-locus specific DNA-FISH analysis. Chromatin bound cohesin at the loading sites co-localizes with Pds5 and Eso1 resulting in stable cohesion. In contrast, cohesin independent of its loader is unable to maintain cohesion and associates with chromatin in a dynamic manner. Cohesive sites coincide with highly expressed genes and transcription inhibition leads to destabilization of cohesin on chromatin. Furthermore, induction of transcription results in de novo recruitment of cohesive cohesin. Our data suggest that transcription facilitates cohesin loading onto chromosomal arms and is a key determinant of cohesive sites in fission yeast. PMID:27084937</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001RaPC...60..503C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001RaPC...60..503C"><span id="translatedtitle">Desalination by electrodialysis with the ion-<span class="hlt">exchange</span> membrane prepared by radiation-<span class="hlt">induced</span> graft polymerization</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Choi, Seong-Ho; Han Jeong, Young; Jeong Ryoo, Jae; Lee, Kwang-Pill</p> <p>2001-01-01</p> <p>Ion-<span class="hlt">exchange</span> membranes modified with the triethylamine [-N(CH 2CH 3) 3] and phosphoric acid (-PO 3 H) groups were prepared by radiation-<span class="hlt">induced</span> grafting of glycidyl methacrylate (GMA) onto the polyolefin nonwavon fabric (PNF) and subsequent chemical modification of poly(GMA) graft chains. The physical and chemical properties of the GMA-grafted PNF and the PNF modified with ion-<span class="hlt">exchange</span> groups were investigated by SEM, XPS, TGA, and DSC. Furthermore, electrochemical properties such as specific electric resistance, transport number of K +, and desalination were examined. The grafting yield increased with increasing reaction time and reaction temperature. The maximum grafting yield was obtained with 40% (vol.%) monomer concentration in dioxane at 60°C. The content of the cation- and anion-<span class="hlt">exchange</span> group increased with increasing grafting yield. Electrical resistance of the PNF modified with TEA and -PO 3 H group decreased, while the water uptake (%) increased with increasing ion-<span class="hlt">exchange</span> group capacities. Transport number of the PNF modified with ion-<span class="hlt">exchange</span> group were the range of ca. 0.82-0.92. The graft-type ion-<span class="hlt">exchange</span> membranes prepared by radiation-<span class="hlt">induced</span> graft copolymerization were successfully applied as separators for electrodialysis.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JaJAP..55g0304O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JaJAP..55g0304O"><span id="translatedtitle"><span class="hlt">Exchange</span> bias controlled by electric current: Interplay of Joule heating and the <span class="hlt">induced</span> field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Oda, Kent; Moriyama, Takahiro; Kawaguchi, Masashi; Kamiya, Michinari; Tanaka, Kensho; Kim, Kab-Jin; Ono, Teruo</p> <p>2016-07-01</p> <p><span class="hlt">Exchange</span> bias is a unidirectional magnetic anisotropy developed in a bilayer of ferromagnetic and antiferromagnetic layers. Its technical importance as a “fix layer” is seen in various spintronic devices. The <span class="hlt">exchange</span> bias can also be a probe to investigate the antiferromagnetic layer as it partly reflects the magnetic state of the antiferromagnet. In this work, we investigated the modulation of the <span class="hlt">exchange</span> bias by a flow of electric current in Pt/Fe50Mn50/FeNi and Cu/Fe50Mn50/FeNi. We show that the <span class="hlt">exchange</span> bias can be modulated just by applying the current due to interplay among the Joule heating, Ampere field, and current-<span class="hlt">induced</span> effective field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EL....11437001N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EL....11437001N"><span id="translatedtitle"><span class="hlt">Exchange</span> bias-like effect in TbFeAl <span class="hlt">induced</span> by atomic disorder</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nair, Harikrishnan S.; Strydom, André M.</p> <p>2016-05-01</p> <p>The <span class="hlt">exchange</span> bias-like effect observed in the intermetallic compound TbFeAl, which displays a magnetic phase transition at T^hc ≈ 198 \\text{K} and a second one at T^lc ≈ 154 \\text{K} , is reported. Jump-like features are observed in the isothermal magnetization, M (H) , at 2 K which disappear above 8 K. The field-cooled magnetization isotherms below 10 K show loop shifts that are reminiscent of <span class="hlt">exchange</span> bias, also supported by the training effect. A significant coercive field, Hc ≈ 1.5 \\text{T} at 2 K, is observed in TbFeAl which, after an initial increase, shows a subsequent decrease with temperature. The <span class="hlt">exchange</span> bias field, H eb , shows a slight increase and a subsequent leveling off with temperature. It is argued that the inherent crystallographic disorder among Fe and Al and the high magnetocrystalline anisotropy related to Tb3+ lead to the <span class="hlt">exchange</span> bias effect. TbFeAl has been recently reported to show the magnetocaloric effect and the present discovery of <span class="hlt">exchange</span> bias makes this compound a multifunctional one. The result obtained on TbFeAl generalizes the observation of <span class="hlt">exchange</span> bias in crystallographically disordered materials and gives impetus for the search for materials with <span class="hlt">exchange</span> bias <span class="hlt">induced</span> by atomic disorder.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NaPho...9..506B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NaPho...9..506B"><span id="translatedtitle">Probing ultrafast photo-<span class="hlt">induced</span> dynamics of the <span class="hlt">exchange</span> energy in a Heisenberg antiferromagnet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Batignani, G.; Bossini, D.; di Palo, N.; Ferrante, C.; Pontecorvo, E.; Cerullo, G.; Kimel, A.; Scopigno, T.</p> <p>2015-08-01</p> <p>Manipulating the macroscopic phases of solids using ultrashort light pulses has resulted in spectacular phenomena, including metal-insulator transitions, superconductivity and subpicosecond modification of magnetic order. The development of this research area strongly depends on the understanding and optical control of fundamental interactions in condensed matter, in particular the <span class="hlt">exchange</span> interaction. However, disentangling the timescales relevant for the contributions of the <span class="hlt">exchange</span> interaction and spin dynamics to the <span class="hlt">exchange</span> energy, Eex, is a challenge. Here, we introduce femtosecond stimulated Raman scattering to unravel the ultrafast photo-<span class="hlt">induced</span> dynamics of magnetic excitations at the edge of the Brillouin zone. We find that femtosecond laser excitation of the antiferromagnet KNiF3 triggers a spectral shift of the two-magnon line, the energy of which is proportional to Eex. By unravelling the photo-<span class="hlt">induced</span> modification of the two-magnon line frequency from a dominating nonlinear optical effect, we find that Eex is increased by the electromagnetic stimulus.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/822365','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/822365"><span id="translatedtitle">Development of Design Criteria for Fluid <span class="hlt">Induced</span> Structural Vibration in Steam Generators and Heat <span class="hlt">Exchangers</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Catton, Ivan; Dhir, Vijay K.; Alquaddoomi, O.S.; Mitra, Deepanjan; Adinolfi, Pierangelo</p> <p>2004-03-26</p> <p>OAK-B135 Flow-<span class="hlt">induced</span> vibration in heat <span class="hlt">exchangers</span> has been a major cause of concern in the nuclear industry for several decades. Many incidents of failure of heat <span class="hlt">exchangers</span> due to apparent flow-<span class="hlt">induced</span> vibration have been reported through the USNRC incident reporting system. Almost all heat <span class="hlt">exchangers</span> have to deal with this problem during their operation. The phenomenon has been studied since the 1970s and the database of experimental studies on flow-<span class="hlt">induced</span> vibration is constantly updated with new findings and improved design criteria for heat <span class="hlt">exchangers</span>. In the nuclear industry, steam generators are often affected by this problem. However, flow-<span class="hlt">induced</span> vibration is not limited to nuclear power plants, but to any type of heat <span class="hlt">exchanger</span> used in many industrial applications such as chemical processing, refrigeration and air conditioning. Specifically, shell and tube type heat <span class="hlt">exchangers</span> experience flow-<span class="hlt">induced</span> vibration due to the high velocity flow over the tube banks. Flow-<span class="hlt">induced</span> vibration in these heat <span class="hlt">exchangers</span> leads to equipment breakdown and hence expensive repair and process shutdown. The goal of this research is to provide accurate measurements that can help modelers to validate their models using the measured experimental parameters and thereby develop better design criteria for avoiding fluid-elastic instability in heat <span class="hlt">exchangers</span>. The research is divided between two primary experimental efforts, the first conducted using water alone (single phase) and the second using a mixture of air or steam and water as the working fluid (two phase). The outline of this report is as follows: After the introduction to fluid-elastic instability, the experimental apparatus constructed to conduct the experiments is described in Chapter 2 along with the measurement procedures. Chapter 3 presents results obtained on the tube array and the flow loop, as well as techniques used in data processing. The project performance is described and evaluated in Chapter 4 followed by</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=145703','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=145703"><span id="translatedtitle">Acid-<span class="hlt">induced</span> <span class="hlt">exchange</span> of the imino proton in G.C pairs.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Nonin, S; Leroy, J L; Gueron, M</p> <p>1996-01-01</p> <p>Acid-<span class="hlt">induced</span> catalysis of imino proton <span class="hlt">exchange</span> in G.C pairs of DNA duplexes is surprisingly fast, being nearly as fast as for the isolated nucleoside, despite base-pair dissociation constants in the range of 10(-5) at neutral or basic pH. It is also observed in terminal G.C pairs of duplexes and in base pairs of drug-DNA complexes. We have measured imino proton <span class="hlt">exchange</span> in deoxyguanosine and in the duplex (ATATAGATCTATAT) as a function of pH. We show that acid-<span class="hlt">induced</span> <span class="hlt">exchange</span> can be assigned to proton transfer from N7-protonated guanosine to cytidine in the open state of the pair. This is faster than transfer from neutral guanosine (the process of intrinsic catalysis previously characterized at neutral ph) due to the lower imino proton pK of the protonated form, 7.2 instead of 9.4. Other interpretations are excluded by a study of <span class="hlt">exchange</span> catalysis by formiate and cytidine as <span class="hlt">exchange</span> catalysts. The cross-over pH between the regimes of pH-independent and acid-<span class="hlt">induced</span> <span class="hlt">exchange</span> rates is more basic in the case of base pairs than in the mononucleoside, suggestive of an increase by one to two decades in the dissociation constant of the base pair upon N7 protonation of G. Acid-<span class="hlt">induced</span> catalysis is much weaker in A.T base pairs, as expected in view of the low pK for protonation of thymidine. PMID:8604298</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=145417','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=145417"><span id="translatedtitle">Securin degradation is mediated by fzy and fzr, and is required for complete <span class="hlt">chromatid</span> separation but not for cytokinesis</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zur, Amit; Brandeis, Michael</p> <p>2001-01-01</p> <p>We have studied the ubiquitination and degradation patterns of the human securin/PTTG protein. We show that, in contrast to budding yeast pds1, securin degradation is catalyzed by both fzy (fizzy/cdc20) and fzr (fizzy-related/cdh1/hct1). Both fzy and fzr also <span class="hlt">induce</span> the APC/C to ubiquitinate securin in vitro. Securin degradation is mediated by an RXXL destruction box and a KEN box, and is inhibited only when both sequences are mutated. Interestingly, the non-degradable securin mutant is also partially ubiquitinated by fzy and fzr in vitro. Expressing the non-degradable securin mutant in cells frequently resulted in incomplete <span class="hlt">chromatid</span> separation and gave rise to daughter cells connected by a thin chromatin fiber, presumably of chromosomes that failed to split completely. Strikingly, the mutant securin did not prevent the majority of sister <span class="hlt">chromatids</span> from separating completely, nor did it prevent mitotic cyclin degradation and cytokinesis. This phenotype, reminiscent of the fission yeast cut (cells untimely torn) phenotype, is reported here for the first time in mammals. PMID:11179223</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27136266','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27136266"><span id="translatedtitle">Sister <span class="hlt">chromatid</span> resolution is an intrinsic part of chromosome organization in prophase.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nagasaka, Kota; Hossain, M Julius; Roberti, M Julia; Ellenberg, Jan; Hirota, Toru</p> <p>2016-06-01</p> <p>The formation of mitotic chromosomes requires both compaction of chromatin and the resolution of replicated sister <span class="hlt">chromatids</span>. Compaction occurs during mitotic prophase and prometaphase, and in prophase relies on the activity of condensin II complexes. Exactly when and how sister <span class="hlt">chromatid</span> resolution occurs has been largely unknown, as has its molecular requirements. Here, we established a method to visualize sister resolution by sequential replication labelling with two distinct nucleotide derivatives. Quantitative three-dimensional imaging then allowed us to measure the resolution of sister <span class="hlt">chromatids</span> throughout mitosis by calculating their non-overlapping volume within the whole chromosome. Unexpectedly, we found that sister <span class="hlt">chromatid</span> resolution starts already at the beginning of prophase, proceeds concomitantly with chromatin compaction and is largely completed by the end of prophase. Sister <span class="hlt">chromatid</span> resolution was abolished by inhibition of topoisomerase IIα and by depleting or preventing mitotic activation of condensin II, whereas blocking cohesin dissociation from chromosomes had little effect. Mitotic sister <span class="hlt">chromatid</span> resolution is thus an intrinsic part of mitotic chromosome formation in prophase that relies largely on DNA decatenation and shares the molecular requirement for condensin II with prophase compaction. PMID:27136266</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SSCom.230...11C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SSCom.230...11C"><span id="translatedtitle">Tiny Ni-NiO nanocrystals with <span class="hlt">exchange</span> bias <span class="hlt">induced</span> room temperature ferromagnetism</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chaghouri, Hanan Al; Tuna, F.; Santhosh, P. N.; Thomas, P. John</p> <p>2016-03-01</p> <p>Ni nanocrystals coated with a thin layer of NiO with a diameter of 5.0 nm show <span class="hlt">exchange</span> bias <span class="hlt">induced</span> ferromagnetism at room temperature. These particulates are freely dispersible in water and were obtained by annealing Ni nanoparticles coated with a thin amorphous layer of NiO. Particulates with diameters between 5.0 and 16.8 nm are studied. Detailed magnetic measurements reveal signs consistent with strong <span class="hlt">exchange</span> bias including elevated blocking temperatures and tangible loop shifts. The structure of the particulates are characterized by high resolution transmission electron microscopy, energy dispersive x-ray analysis and x-ray diffraction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4933981','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4933981"><span id="translatedtitle">Plasma <span class="hlt">exchange</span> in the treatment of thyroid storm secondary to type II amiodarone-<span class="hlt">induced</span> thyrotoxicosis</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zainudin, Sueziani Binte; Kaushik, Manish; Khor, Li Yan; Chng, Chiaw Ling</p> <p>2016-01-01</p> <p>Summary Type II amiodarone-<span class="hlt">induced</span> thyrotoxicosis (AIT) is an uncommon cause of thyroid storm. Due to the rarity of the condition, little is known about the role of plasma <span class="hlt">exchange</span> in the treatment of severe AIT. A 56-year-old male presented with thyroid storm 2months following cessation of amiodarone. Despite conventional treatment, his condition deteriorated. He underwent two cycles of plasma <span class="hlt">exchange</span>, which successfully controlled the severe hyperthyroidism. The thyroid hormone levels continued to fall up to 10h following plasma <span class="hlt">exchange</span>. He subsequently underwent emergency total thyroidectomy and the histology of thyroid gland confirmed type II AIT. Management of thyroid storm secondary to type II AIT can be challenging as patients may not respond to conventional treatments, and thyroid storm may be more harmful in AIT patients owing to the underlying cardiac disease. If used appropriately, plasma <span class="hlt">exchange</span> can effectively reduce circulating hormones, to allow stabilisation of patients in preparation for emergency thyroidectomy. Learning points Type II AIT is an uncommon cause of thyroid storm and may not respond well to conventional thyroid storm treatment. Prompt diagnosis and therapy are important, as patients may deteriorate rapidly. Plasma <span class="hlt">exchange</span> can be used as an effective bridging therapy to emergency thyroidectomy. This case shows that in type II AIT, each cycle of plasma <span class="hlt">exchange</span> can potentially lower free triiodothyronine levels for 10h. Important factors to consider when planning plasma <span class="hlt">exchange</span> as a treatment for thyroid storm include timing of each session, type of <span class="hlt">exchange</span> fluid to be used and timing of surgery. PMID:27398220</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/153685','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/153685"><span id="translatedtitle">Novel ion-<span class="hlt">exchange</span> membranes for electrodialysis prepared by radiation-<span class="hlt">induced</span> graft polymerization</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tsuneda, Satoshi; Saito, Kyoichi; Misuhara, Hisashi; Sugo, Takanobu</p> <p>1995-11-01</p> <p>Ion-<span class="hlt">exchange</span> membranes have been used to concentrate seawater to produce salt as well as to desalinate brackish water to render it potable. Also, the interest in applications of ion-<span class="hlt">exchange</span> membranes as separators for electrodialytic desalination of bioproducts and separators in hydrogen-oxygen fuel cells has been growing. Novel ion-<span class="hlt">exchange</span> membranes containing sulfonic acid (SO{sub 3}H) and trimethyl ammonium [N(CH{sub 3}){sub 3}] groups were prepared by a simple method of radiation-<span class="hlt">induced</span> cografting of sodium styrene sulfonate (SSS) with acrylic acid (AAc) and vinyl benzyl trimethyl ammonium chloride (VBTAC) with 2-hydroxyethyl methacrylate (HEMA), onto a polyethylene film with a thickness of 50 {micro}m. The high density graft chain was introduced throughout the polyethylene film. The maximum cation- and anion-<span class="hlt">exchange</span> capacities of the resultant membranes were 2.5 and 1.3 mol/kg, receptively. These membranes exhibited an electrical resistance one order lower than commercially available ion-<span class="hlt">exchange</span> membranes; for example, 12 h cografting provided cation- and anion-<span class="hlt">exchange</span> membranes whose electrical resistances in a 0.5 M NaCl solution were 0.25 and 0.85 {Omega} cm{sup 2}, respectively. From the evaluation of electrodialytic desalination in a batch mode, using a pair of the graft-type ion-<span class="hlt">exchange</span> membranes, the time required to achieve 99.5% desalination of the initial 0.5 M NaCl solutions was reduced to 85% comparing with that of the commercial ion-<span class="hlt">exchange</span> membranes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3575537','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3575537"><span id="translatedtitle">Condensin II initiates sister <span class="hlt">chromatid</span> resolution during S phase</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ono, Takao; Yamashita, Daisuke</p> <p>2013-01-01</p> <p>Condensins I and II are multisubunit complexes that play essential yet distinct functions in chromosome condensation and segregation in mitosis. Unlike condensin I, condensin II localizes to the nucleus during interphase, but it remains poorly understood what functions condensin II might have before mitotic entry. Here, we report that condensin II changes its chromatin-binding property during S phase. Remarkably, advanced premature chromosome condensation (PCC) assays enabled us to visualize condensin II forming “sister axes” in replicated regions of chromosomes in S phase cells. Depletion of condensin II compromised PCC-driven sister <span class="hlt">chromatid</span> resolution during S phase. Moreover, fluorescence in situ hybridization assays revealed that condensin II, but not condensin I, promotes disjoining duplicated chromosomal loci during S phase. Application of mild replicative stress partially impaired this process and further exacerbated phenotypes arising from condensin II depletion. Our results suggest that condensin II initiates structural reorganization of duplicated chromosomes during S phase to prepare for their proper condensation and segregation in mitosis. PMID:23401001</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2567865','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2567865"><span id="translatedtitle">Shugoshin1 May Play Important Roles in Separation of Homologous Chromosomes and Sister <span class="hlt">Chromatids</span> during Mouse Oocyte Meiosis</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Yin, Shen; Ai, Jun-Shu; Shi, Li-Hong; Wei, Liang; Yuan, Ju; Ouyang, Ying-Chun; Hou, Yi; Chen, Da-Yuan; Schatten, Heide; Sun, Qing-Yuan</p> <p>2008-01-01</p> <p>Background Homologous chromosomes separate in meiosis I and sister <span class="hlt">chromatids</span> separate in meiosis II, generating haploid gametes. To address the question why sister <span class="hlt">chromatids</span> do not separate in meiosis I, we explored the roles of Shogoshin1 (Sgo1) in chromosome separation during oocyte meiosis. Methodology/Principal Findings Sgo1 function was evaluated by exogenous overexpression to enhance its roles and RNAi to suppress its roles during two meioses of mouse oocytes. Immunocytochemistry and chromosome spread were used to evaluate phenotypes. The exogenous Sgo1 overexpression kept homologous chromosomes and sister <span class="hlt">chromatids</span> not to separate in meiosis I and meiosis II, respectively, while the Sgo1 RNAi promoted premature separation of sister <span class="hlt">chromatids</span>. Conclusions Our results reveal that prevention of premature separation of sister <span class="hlt">chromatids</span> in meiosis I requires the retention of centromeric Sgo1, while normal separation of sister <span class="hlt">chromatids</span> in meiosis II requires loss of centromeric Sgo1. PMID:18949044</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22162960','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22162960"><span id="translatedtitle">Boron- and phosphorus-doped polycrystalline silicon thin films prepared by silver-<span class="hlt">induced</span> layer <span class="hlt">exchange</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Antesberger, T.; Wassner, T. A.; Jaeger, C.; Algasinger, M.; Kashani, M.; Scholz, M.; Matich, S.; Stutzmann, M.</p> <p>2013-05-27</p> <p>Intentional boron and phosphorus doping of polycrystalline silicon thin films on glass prepared by the silver-<span class="hlt">induced</span> layer <span class="hlt">exchange</span> is presented. A silver/(titanium) oxide/amorphous silicon stack is annealed at temperatures below the eutectic temperature of the Ag/Si system, leading to a complete layer <span class="hlt">exchange</span> and simultaneous crystallization of the amorphous silicon. Intentional doping of the amorphous silicon prior to the <span class="hlt">exchange</span> process results in boron- or phosphorus-doped polycrystalline silicon. Hall effect measurements show carrier concentrations between 2 Multiplication-Sign 10{sup 17} cm{sup -3} and 3 Multiplication-Sign 10{sup 20} cm{sup -3} for phosphorus and 4 Multiplication-Sign 10{sup 18} cm{sup -3} to 3 Multiplication-Sign 10{sup 19} cm{sup -3} for boron-doped layers, with carrier mobilities up to 90 cm{sup 2}/V s.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=461013','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=461013"><span id="translatedtitle">Effectiveness of a heat and moisture <span class="hlt">exchanger</span> in preventing hyperpnoea <span class="hlt">induced</span> bronchoconstriction in subjects with asthma.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Gravelyn, T R; Capper, M; Eschenbacher, W L</p> <p>1987-01-01</p> <p>The effect of a heat and moisture <span class="hlt">exchanger</span>, a device with hygroscopic material for conditioning inspired air, on hyperpnoea <span class="hlt">induced</span> bronchoconstriction was studied in nine non-smoking volunteers with asthma, aged 19-32 years. Each had previously shown an increase of at least 100% in specific airways resistance (sRaw) to isocapnic hyperpnoea with dry air. On two separate days the subject performed isocapnic hyperpnoea with dry air at 60-70 l min-1 for five minutes. Before, immediately after, and five minutes after completion of a test sRaw measurements were made. Heat and moisture <span class="hlt">exchangers</span> were placed in the breathing circuit on one of the two days. All subjects had an increase in sRaw of 100% or more without the heat and moisture <span class="hlt">exchangers</span> (average increase 300%) but were protected from bronchoconstriction with the devices in place (average increase 7%) (p less than 0.005). The <span class="hlt">exchanger</span>'s resistance to airflow was less than 1 cm H2O for flow rates of 100 l min-1. A heat and moisture <span class="hlt">exchanger</span> designed as a facemask or mouthpiece may allow a person with asthma to exercise without the need for prophylactic drugs. PMID:3424269</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015Nanot..26D5602T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015Nanot..26D5602T"><span id="translatedtitle">Paramagnetic molecule <span class="hlt">induced</span> strong antiferromagnetic <span class="hlt">exchange</span> coupling on a magnetic tunnel junction based molecular spintronics device</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tyagi, Pawan; Baker, Collin; D'Angelo, Christopher</p> <p>2015-07-01</p> <p>This paper reports our Monte Carlo (MC) studies aiming to explain the experimentally observed paramagnetic molecule <span class="hlt">induced</span> antiferromagnetic coupling between ferromagnetic (FM) electrodes. Recently developed magnetic tunnel junction based molecular spintronics devices (MTJMSDs) were prepared by chemically bonding the paramagnetic molecules between the FM electrodes along the tunnel junction’s perimeter. These MTJMSDs exhibited molecule-<span class="hlt">induced</span> strong antiferromagnetic coupling. We simulated the 3D atomic model analogous to the MTJMSD and studied the effect of molecule’s magnetic couplings with the two FM electrodes. Simulations show that when a molecule established ferromagnetic coupling with one electrode and antiferromagnetic coupling with the other electrode, then theoretical results effectively explained the experimental findings. Our studies suggest that in order to align MTJMSDs’ electrodes antiparallel to each other, the <span class="hlt">exchange</span> coupling strength between a molecule and FM electrodes should be ˜50% of the interatomic <span class="hlt">exchange</span> coupling for the FM electrodes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26159362','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26159362"><span id="translatedtitle">Paramagnetic molecule <span class="hlt">induced</span> strong antiferromagnetic <span class="hlt">exchange</span> coupling on a magnetic tunnel junction based molecular spintronics device.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tyagi, Pawan; Baker, Collin; D'Angelo, Christopher</p> <p>2015-07-31</p> <p>This paper reports our Monte Carlo (MC) studies aiming to explain the experimentally observed paramagnetic molecule <span class="hlt">induced</span> antiferromagnetic coupling between ferromagnetic (FM) electrodes. Recently developed magnetic tunnel junction based molecular spintronics devices (MTJMSDs) were prepared by chemically bonding the paramagnetic molecules between the FM electrodes along the tunnel junction's perimeter. These MTJMSDs exhibited molecule-<span class="hlt">induced</span> strong antiferromagnetic coupling. We simulated the 3D atomic model analogous to the MTJMSD and studied the effect of molecule's magnetic couplings with the two FM electrodes. Simulations show that when a molecule established ferromagnetic coupling with one electrode and antiferromagnetic coupling with the other electrode, then theoretical results effectively explained the experimental findings. Our studies suggest that in order to align MTJMSDs' electrodes antiparallel to each other, the <span class="hlt">exchange</span> coupling strength between a molecule and FM electrodes should be ∼50% of the interatomic <span class="hlt">exchange</span> coupling for the FM electrodes. PMID:26159362</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhRvB..92v0422P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvB..92v0422P"><span id="translatedtitle">Interfacial <span class="hlt">exchange</span>-coupling <span class="hlt">induced</span> chiral symmetry breaking of spin-orbit effects</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Perna, P.; Ajejas, F.; Maccariello, D.; Fernandez Cuñado, J. L.; Guerrero, R.; Niño, M. A.; Bollero, A.; Miranda, R.; Camarero, J.</p> <p>2015-12-01</p> <p>We demonstrate that the interfacial <span class="hlt">exchange</span> coupling in ferromagnetic/antiferromagnetic (FM/AFM) systems <span class="hlt">induces</span> symmetry breaking of the spin-orbit (SO) effects. This has been done by studying the field and angle dependencies of anisotropic magnetoresistance and vectorial-resolved magnetization hysteresis loops, measured simultaneously and reproduced with numerical simulations. We show how the <span class="hlt">induced</span> unidirectional magnetic anisotropy at the FM/AFM interface results in strong asymmetric transport behaviors, which are chiral around the magnetization hard-axis direction. Similar asymmetric features are anticipated in other SO-driven phenomena.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27170622','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27170622"><span id="translatedtitle">High density of REC8 constrains sister <span class="hlt">chromatid</span> axes and prevents illegitimate synaptonemal complex formation.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Agostinho, Ana; Manneberg, Otto; van Schendel, Robin; Hernández-Hernández, Abrahan; Kouznetsova, Anna; Blom, Hans; Brismar, Hjalmar; Höög, Christer</p> <p>2016-06-01</p> <p>During meiosis, cohesin complexes mediate sister <span class="hlt">chromatid</span> cohesion (SCC), synaptonemal complex (SC) assembly and synapsis. Here, using super-resolution microscopy, we imaged sister <span class="hlt">chromatid</span> axes in mouse meiocytes that have normal or reduced levels of cohesin complexes, assessing the relationship between localization of cohesin complexes, SCC and SC formation. We show that REC8 foci are separated from each other by a distance smaller than 15% of the total chromosome axis length in wild-type meiocytes. Reduced levels of cohesin complexes result in a local separation of sister <span class="hlt">chromatid</span> axial elements (LSAEs), as well as illegitimate SC formation at these sites. REC8 but not RAD21 or RAD21L cohesin complexes flank sites of LSAEs, whereas RAD21 and RAD21L appear predominantly along the separated sister-<span class="hlt">chromatid</span> axes. Based on these observations and a quantitative distribution analysis of REC8 along sister <span class="hlt">chromatid</span> axes, we propose that the high density of randomly distributed REC8 cohesin complexes promotes SCC and prevents illegitimate SC formation. PMID:27170622</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22374834','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22374834"><span id="translatedtitle">Accurate quantification of water-macromolecule <span class="hlt">exchange</span> <span class="hlt">induced</span> frequency shift: effects of reference substance.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Leutritz, Tobias; Hilfert, Liane; Smalla, Karl-Heinz; Speck, Oliver; Zhong, Kai</p> <p>2013-01-01</p> <p>Water-macromolecule <span class="hlt">exchange</span> <span class="hlt">induces</span> a bulk water frequency shift contributing to the contrast in phase imaging. For separating the effects of the water-macromolecule <span class="hlt">exchange</span> and the macromolecule susceptibility, appropriate internal or external references are needed. In this study, two internal reference compounds, 2,2,3,3-tetradeuterio-3-trimethylsilyl-propionate (TMSP) and 1,4-dioxane, were used to study the macromolecule-dependent water frequency shift in a bovine serum albumin (BSA)-water system in detail. For TMSP, the water-macromolecule <span class="hlt">exchange</span> shift depended on both the BSA and the reference concentration and stabilized to a value of 0.025 ppm/mM (298 K, TMSP concentrations > 30 mM). For dioxane, the dependency of the water-macromolecule <span class="hlt">exchange</span> shift on the BSA concentration is independent of dioxane at low concentrations. The resulting shift was smaller (0.009 ppm/mM) when compared with using higher TMSP concentrations as reference. This discrepancy might be due to additional dioxane-water interactions. Measurements with an external chloroform reference in a coaxial geometry showed a shift of -0.013 ppm/mM resulting from the opposing effects of macromolecules in water <span class="hlt">exchange-induced</span> shift and diamagnetic susceptibility shift. All these effects should be considered in the interpretation of tissue phase contrast. From the experimental data, the equilibrium binding constant between BSA and TMSP has been quantified to be K(d) = 1.3 ± 0.4, and the estimated number of interaction sites for BSA is 12.7 ± 2.6. PMID:22374834</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=69342&keyword=ocean+AND+currents&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=65307677&CFTOKEN=54495834','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=69342&keyword=ocean+AND+currents&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=65307677&CFTOKEN=54495834"><span id="translatedtitle">ON THE WIND-<span class="hlt">INDUCED</span> <span class="hlt">EXCHANGE</span> BETWEEN INDIAN RIVER BAY, DELAWARE AND THE ADJACENT CONTINENTAL SHELF. (R826945)</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p><p>The structure of the wind-<span class="hlt">induced</span> <span class="hlt">exchange</span> between Indian River Bay, Delaware and the adjacent continental shelf is examined based on current measurements made at the Indian River Inlet which represents the only conduit of <span class="hlt">exchange</span> between the bay and the coastal ocean. Local ...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EPJD...70..120H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EPJD...70..120H"><span id="translatedtitle">The weakening of fermionization of one dimensional spinor Bose gases <span class="hlt">induced</span> by spin-<span class="hlt">exchange</span> interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hao, Yajiang</p> <p>2016-05-01</p> <p>We investigate the ground state density distributions of anti-ferromagnetic spin-1 Bose gases in a one dimensional harmonic potential in the full interacting regimes. The ground state is obtained by diagonalizing the Hamiltonian in the Hilbert space composed of the lowest eigenstates of noninteracting Bose gas and spin components. The study reveals that in the situation of a weak spin-dependent interaction the total density profiles evolve from a Gaussian-like distribution to a Fermi-like shell structure of N peaks with the increasing of spin-independent interaction. The increasing spin-<span class="hlt">exchange</span> interaction always weakens the fermionization of the density distribution such that the total density profiles show the shell structure of less peaks and even show single peak structure in the limit of the strong spin-<span class="hlt">exchange</span> interaction. The weakening of fermionization results from the formation of composite atoms <span class="hlt">induced</span> by the spin-<span class="hlt">exchange</span> interaction. It is also shown that phase separation occurs for the spinor Bose gas with a weak spin-<span class="hlt">exchange</span> interaction, meanwhile the spin-independent interaction is strong.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016RaPC..118...35K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016RaPC..118...35K&link_type=ABSTRACT"><span id="translatedtitle">Polymeric nanocomposite proton <span class="hlt">exchange</span> membranes prepared by radiation-<span class="hlt">induced</span> polymerization for direct methanol fuel cell</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Young-Seok; Seo, Kwang-Seok; Choi, Seong-Ho</p> <p>2016-01-01</p> <p>The vinyl group-modified montmorillonite clay (F-MMT), vinyl group-modified graphene oxide (F-GO), and vinyl group-modified multi-walled carbon nanotube (F-MWNT) were first prepared by ion <span class="hlt">exchange</span> reaction of 1-[(4-ethylphenyl)methyl]-3-butyl-imidazolium chloride in order to use the materials for protection against methanol cross-over in direct methanol fuel cell (DMFC) membrane. Then polymeric nanocomposite membranes with F-MMT, F-GO, and F-MWNT were prepared by the solvent casting method after radiation-<span class="hlt">induced</span> polymerization of vinyl monomers in water-methanol mixture solvents. The proton conductivity, water uptake, ion-<span class="hlt">exchange</span> capacity, methanol permeability, and DMFC performance of the polymeric nanocomposite membranes with F-MMT, F-GO, and F-MWNT were evaluated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JMagR.245...12S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JMagR.245...12S"><span id="translatedtitle"><span class="hlt">Exchange-induced</span> relaxation in the presence of a fictitious field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sorce, Dennis J.; Mangia, Silvia; Liimatainen, Timo; Garwood, Michael; Michaeli, Shalom</p> <p>2014-08-01</p> <p>In the present study we derive a solution for two site fast <span class="hlt">exchange-induced</span> relaxation in the presence of a fictitious magnetic field as generated by amplitude and frequency modulated RF pulses. This solution provides a means to analyze data obtained from relaxation experiments with the method called RAFFn (Relaxation Along a Fictitious Field of rank n), in which a fictitious field is created in a coordinate frame undergoing multi-fold rotation about n axes (rank n). The RAFF2 technique is relevant to MRI relaxation methods that provide good contrast enhancement for tumor detection. The relaxation equations for n = 2 are derived for the fast <span class="hlt">exchange</span> regime using density matrix formalism. The method of derivation can be further extended to obtain solutions for n > 2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24911888','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24911888"><span id="translatedtitle"><span class="hlt">Exchange-induced</span> relaxation in the presence of a fictitious field.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sorce, Dennis J; Mangia, Silvia; Liimatainen, Timo; Garwood, Michael; Michaeli, Shalom</p> <p>2014-08-01</p> <p>In the present study we derive a solution for two site fast <span class="hlt">exchange-induced</span> relaxation in the presence of a fictitious magnetic field as generated by amplitude and frequency modulated RF pulses. This solution provides a means to analyze data obtained from relaxation experiments with the method called RAFFn (Relaxation Along a Fictitious Field of rank n), in which a fictitious field is created in a coordinate frame undergoing multi-fold rotation about n axes (rank n). The RAFF2 technique is relevant to MRI relaxation methods that provide good contrast enhancement for tumor detection. The relaxation equations for n=2 are derived for the fast <span class="hlt">exchange</span> regime using density matrix formalism. The method of derivation can be further extended to obtain solutions for n>2. PMID:24911888</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4308052','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4308052"><span id="translatedtitle"><span class="hlt">Exchange-Induced</span> Relaxation in the Presence of a Fictitious Field</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Sorce, Dennis J.; Mangia, Silvia; Liimatainen, Timo; Garwood, Michael; Michaeli, Shalom</p> <p>2014-01-01</p> <p>In the present study we derive a solution for two site fast <span class="hlt">exchange-induced</span> relaxation in the presence of a fictitious magnetic field as generated by amplitude and frequency modulated RF pulses. This solution provides a means to analyze data obtained from relaxation experiments with the method called RAFFn (Relaxation Along a Fictitious Field of rank n), in which a fictitious field is created in a coordinate frame undergoing multi-fold rotation about n axes (rank n). The RAFF2 technique is relevant to MRI relaxation methods that provide good contrast enhancement for tumor detection. The relaxation equations for n = 2 are derived for the fast <span class="hlt">exchange</span> regime using density matrix formalism. The method of derivation can be further extended to obtain solutions for n > 2. PMID:24911888</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4358958','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4358958"><span id="translatedtitle"><span class="hlt">Inducible</span> and Reversible Lentiviral and Recombination Mediated Cassette <span class="hlt">Exchange</span> (RMCE) Systems for Controlling Gene Expression</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bersten, David C.; Sullivan, Adrienne E.; Li, Dian; Bhakti, Veronica; Bent, Stephen J.; Whitelaw, Murray L.</p> <p>2015-01-01</p> <p>Manipulation of gene expression to invoke loss of function (LoF) or gain of function (GoF) phenotypes is important for interrogating complex biological questions both in vitro and in vivo. Doxycycline (Dox)-<span class="hlt">inducible</span> gene expression systems are commonly used although success is often limited by high background and insufficient sensitivity to Dox. Here we develop broadly applicable platforms for reliable, tightly controlled and reversible Dox-<span class="hlt">inducible</span> systems for lentiviral mediated generation of cell lines or FLP Recombination-Mediated Cassette <span class="hlt">Exchange</span> (RMCE) into the Collagen 1a1 (Col1a1) locus (FLP-In Col1a1) in mouse embryonic stem cells. We significantly improve the flexibility, usefulness and robustness of the Dox-<span class="hlt">inducible</span> system by using Tetracycline (Tet) activator (Tet-On) variants which are more sensitive to Dox, have no background activity and are expressed from single Gateway-compatible constructs. We demonstrate the usefulness of these platforms in ectopic gene expression or gene knockdown in multiple cell lines, primary neurons and in FLP-In Col1a1 mouse embryonic stem cells. We also improve the flexibility of RMCE Dox-<span class="hlt">inducible</span> systems by generating constructs that allow for tissue or cell type-specific Dox-<span class="hlt">inducible</span> expression and generate a shRNA selection algorithm that can effectively predict potent shRNA sequences able to knockdown gene expression from single integrant constructs. These platforms provide flexible, reliable and broadly applicable <span class="hlt">inducible</span> expression systems for studying gene function. PMID:25768837</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25795300','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25795300"><span id="translatedtitle">Rho guanine nucleotide <span class="hlt">exchange</span> factors involved in cyclic-stretch-<span class="hlt">induced</span> reorientation of vascular endothelial cells.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Abiko, Hiyori; Fujiwara, Sachiko; Ohashi, Kazumasa; Hiatari, Ryuichi; Mashiko, Toshiya; Sakamoto, Naoya; Sato, Masaaki; Mizuno, Kensaku</p> <p>2015-05-01</p> <p>Cyclic stretch is an artificial model of mechanical force loading, which <span class="hlt">induces</span> the reorientation of vascular endothelial cells and their stress fibers in a direction perpendicular to the stretch axis. Rho family GTPases are crucial for cyclic-stretch-<span class="hlt">induced</span> endothelial cell reorientation; however, the mechanism underlying stretch-<span class="hlt">induced</span> activation of Rho family GTPases is unknown. A screen of short hairpin RNAs targeting 63 Rho guanine nucleotide <span class="hlt">exchange</span> factors (Rho-GEFs) revealed that at least 11 Rho-GEFs – Abr, alsin, ARHGEF10, Bcr, GEF-H1 (also known as ARHGEF2), LARG (also known as ARHGEF12), p190RhoGEF (also known as ARHGEF28), PLEKHG1, P-REX2, Solo (also known as ARHGEF40) and α-PIX (also known as ARHGEF6) – which specifically or broadly target RhoA, Rac1 and/or Cdc42, are involved in cyclic-stretch-<span class="hlt">induced</span> perpendicular reorientation of endothelial cells. Overexpression of Solo <span class="hlt">induced</span> RhoA activation and F-actin accumulation at cell-cell and cell-substrate adhesion sites. Knockdown of Solo suppressed cyclic-stretch- or tensile-force-<span class="hlt">induced</span> RhoA activation. Moreover, knockdown of Solo significantly reduced cyclic-stretch-<span class="hlt">induced</span> perpendicular reorientation of endothelial cells when cells were cultured at high density, but not when they were cultured at low density or pretreated with EGTA or VE-cadherin-targeting small interfering RNAs. These results suggest that Solo is involved in cell-cell-adhesion-mediated mechanical signal transduction during cyclic-stretch-<span class="hlt">induced</span> endothelial cell reorientation. PMID:25795300</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25962614','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25962614"><span id="translatedtitle">The effects of oxygen <span class="hlt">induced</span> pulmonary vasoconstriction on bedside measurement of pulmonary gas <span class="hlt">exchange</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Weinreich, Ulla M; Thomsen, Lars P; Rees, Stephen E; Rasmussen, Bodil S</p> <p>2016-04-01</p> <p>In patients with respiratory failure measurements of pulmonary gas <span class="hlt">exchange</span> are of importance. The bedside automatic lung parameter estimator (ALPE) of pulmonary gas <span class="hlt">exchange</span> is based on changes in inspired oxygen (FiO2) assuming that these changes do not affect pulmonary circulation. This assumption is investigated in this study. Forty-two out of 65 patients undergoing coronary artery bypass grafting (CABG) had measurements of mean pulmonary arterial pressure (MPAP), cardiac output and pulmonary capillary wedge pressure thus enabling the calculation of pulmonary vascular resistance (PVR) at each FiO2 level. The research version of ALPE was used and FiO2 was step-wise reduced a median of 0.20 and ultimately returned towards baseline values, allowing 6-8 min' steady state period at each of 4-6 levels before recording the oxygen saturation (SpO2). FiO2 reduction led to median decrease in SpO2 from 99 to 92 %, an increase in MPAP of 4 mmHg and an increase in PVR of 36 dyn s cm(-5). Changes were immediately reversed on returning FiO2 towards baseline. In this study changes in MPAP and PVR are small and immediately reversible consistent with small changes in pulmonary gas <span class="hlt">exchange</span>. This indicates that mild deoxygenation <span class="hlt">induced</span> pulmonary vasoconstriction does not have significant influences on the ALPE parameters in patients after CABG. PMID:25962614</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25319531','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25319531"><span id="translatedtitle">Uncoupled surface spin <span class="hlt">induced</span> <span class="hlt">exchange</span> bias in α-MnO2 nanowires.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Wenxian; Zeng, Rong; Sun, Ziqi; Tian, Dongliang; Dou, Shixue</p> <p>2014-01-01</p> <p>We have studied the microstructure, surface states, valence fluctuations, magnetic properties, and <span class="hlt">exchange</span> bias effect in MnO2 nanowires. High purity α-MnO2 rectangular nanowires were synthesized by a facile hydrothermal method with microwave-assisted procedures. The microstructure analysis indicates that the nanowires grow in the [0 0 1] direction with the (2 1 0) plane as the surface. Mn(3+) and Mn(2+) ions are not found in the system by X-ray photoelectron spectroscopy. The effective magnetic moment of the manganese ions fits in with the theoretical and experimental values of Mn(4+) very well. The uncoupled spins in 3d(3) orbitals of the Mn(4+) ions in MnO6 octahedra on the rough surface are responsible for the net magnetic moment. Spin glass behavior is observed through magnetic measurements. Furthermore, the <span class="hlt">exchange</span> bias effect is observed for the first time in pure α-MnO2 phase due to the coupling of the surface spin glass with the antiferromagnetic α-MnO2 matrix. These α-MnO2 nanowires, with a spin-glass-like behavior and with an <span class="hlt">exchange</span> bias effect excited by the uncoupled surface spins, should therefore inspire further study concerning the origin, theory, and applicability of surface structure <span class="hlt">induced</span> magnetism in nanostructures. PMID:25319531</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014NatSR...4E6641L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014NatSR...4E6641L"><span id="translatedtitle">Uncoupled surface spin <span class="hlt">induced</span> <span class="hlt">exchange</span> bias in α-MnO2 nanowires</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Wenxian; Zeng, Rong; Sun, Ziqi; Tian, Dongliang; Dou, Shixue</p> <p>2014-10-01</p> <p>We have studied the microstructure, surface states, valence fluctuations, magnetic properties, and <span class="hlt">exchange</span> bias effect in MnO2 nanowires. High purity α-MnO2 rectangular nanowires were synthesized by a facile hydrothermal method with microwave-assisted procedures. The microstructure analysis indicates that the nanowires grow in the [0 0 1] direction with the (2 1 0) plane as the surface. Mn3+ and Mn2+ ions are not found in the system by X-ray photoelectron spectroscopy. The effective magnetic moment of the manganese ions fits in with the theoretical and experimental values of Mn4+ very well. The uncoupled spins in 3d3 orbitals of the Mn4+ ions in MnO6 octahedra on the rough surface are responsible for the net magnetic moment. Spin glass behavior is observed through magnetic measurements. Furthermore, the <span class="hlt">exchange</span> bias effect is observed for the first time in pure α-MnO2 phase due to the coupling of the surface spin glass with the antiferromagnetic α-MnO2 matrix. These α-MnO2 nanowires, with a spin-glass-like behavior and with an <span class="hlt">exchange</span> bias effect excited by the uncoupled surface spins, should therefore inspire further study concerning the origin, theory, and applicability of surface structure <span class="hlt">induced</span> magnetism in nanostructures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005ApPhB..80..193W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005ApPhB..80..193W"><span id="translatedtitle">Wavelength-tunable polarization converter utilizing the strain <span class="hlt">induced</span> by proton <span class="hlt">exchange</span> in lithium niobate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, T.-J.; Chung, J.-S.</p> <p>2005-02-01</p> <p>A new wavelength-tunable polarization converter utilizing the strain <span class="hlt">induced</span> by proton <span class="hlt">exchange</span> is demonstrated in x-cut LiNbO3. The light polarization is converted by the strain-optic effect through the phase-matched coupling of two orthogonal polarizations. The stress-applying structure is designed to be composed of several proton-<span class="hlt">exchanged</span> strip regions for maximization of the stress distribution. The principle of birefringent chain filters is utilized to design the device structure in order to avoid the requirement of large stress, which results in serious cracks on the substrate surface. The overlap integral between the optical field distribution and the stress distribution can be enhanced simply by prolonging the proton-<span class="hlt">exchange</span> time. Besides, the stress distribution and its strength in the stress-applying structure can be fine tuned without affecting the waveguide characteristics such that the principle of the birefringent chain filters is completely satisfied. Therefore, the polarization-conversion efficiency can be optimized when utilizing this exclusive stress-tuning ability. By the thermal-optic effect, the wavelength of maximum conversion can be tuned at a rate of -0.115 nm/°C with a maximum conversion efficiency of 92.41%. The proposed polarization converter has the advantages of adequate stress distribution and strength, high parameter-tuning feasibility, low propagation loss, easy fabrication, and low fabrication cost.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..MAR.A7005L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..MAR.A7005L"><span id="translatedtitle">Magnetization in Intrinsic Topological Insulators <span class="hlt">Induced</span> by <span class="hlt">Exchange</span> Interaction with Ferromagnetic Insulator</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lauter, Valeria; Katmis, Ferhat; Assaf, Badih; Heiman, Don; Moodera, Jagadeesh</p> <p>2015-03-01</p> <p>We examine the magnetic proximity-<span class="hlt">induced</span> symmetry breaking via the <span class="hlt">exchange</span> interaction in heterostructures of the topological insulator (TI) Bi2Se3 and the ferromagnetic insulator (FMI) EuS. We observed the emergence of a ferromagnetic phase in TI with the excess of magnetic moment at the interface using depth and element sensitive Polarized Neutron Reflectometry (PNR). We find that the magnetization, penetrating into the TI originates through <span class="hlt">exchange</span> interaction, without structural perturbation at the interface. Due to the different interlayer <span class="hlt">exchange</span> coupling as well as the properties of the bulk and surface magnetizations, we investigated several different heterostructures after cooling in zero field (ZFC) and in an external magnetic field (FC). The significantly enhanced magnetic properties of the heterostructures as revealed by the PNR studies, as well as the temperature and external magnetic field dependence will be presented. This work was supported by the Scientific User Facilities Division, BES, DOE, NSF ECCS-1402738, DMR-1207469, ONR N00014-13-1-0301.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4198866','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4198866"><span id="translatedtitle">Uncoupled surface spin <span class="hlt">induced</span> <span class="hlt">exchange</span> bias in α-MnO2 nanowires</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Li, Wenxian; Zeng, Rong; Sun, Ziqi; Tian, Dongliang; Dou, Shixue</p> <p>2014-01-01</p> <p>We have studied the microstructure, surface states, valence fluctuations, magnetic properties, and <span class="hlt">exchange</span> bias effect in MnO2 nanowires. High purity α-MnO2 rectangular nanowires were synthesized by a facile hydrothermal method with microwave-assisted procedures. The microstructure analysis indicates that the nanowires grow in the [0 0 1] direction with the (2 1 0) plane as the surface. Mn3+ and Mn2+ ions are not found in the system by X-ray photoelectron spectroscopy. The effective magnetic moment of the manganese ions fits in with the theoretical and experimental values of Mn4+ very well. The uncoupled spins in 3d3 orbitals of the Mn4+ ions in MnO6 octahedra on the rough surface are responsible for the net magnetic moment. Spin glass behavior is observed through magnetic measurements. Furthermore, the <span class="hlt">exchange</span> bias effect is observed for the first time in pure α-MnO2 phase due to the coupling of the surface spin glass with the antiferromagnetic α-MnO2 matrix. These α-MnO2 nanowires, with a spin-glass-like behavior and with an <span class="hlt">exchange</span> bias effect excited by the uncoupled surface spins, should therefore inspire further study concerning the origin, theory, and applicability of surface structure <span class="hlt">induced</span> magnetism in nanostructures. PMID:25319531</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110023194','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110023194"><span id="translatedtitle">The Correlation of Interphase Chromatin Structure with the Radiation-<span class="hlt">Induced</span> Inter- and Intrachromosome <span class="hlt">Exchange</span> Hotspots</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zhang, Ye; Mangala, Lingegowda S.; Purgason, Ashley M.; Hada, Megumi; Cucinotta, Francis A.; Wu, Honglu</p> <p>2011-01-01</p> <p>To investigate the relationship between chromosome aberrations <span class="hlt">induced</span> by radiation and chromatin folding, we reconstructed three dimensional structure of chromosome 3 and measured the physical distances between different regions of the chromosome. Previously, we have investigated the location of breaks involved in inter- and intrachromosomal type <span class="hlt">exchange</span> events in human chromosome 3, using the multicolor banding in situ hybridization (mBAND) technique. In human epithelial cells exposed to both low- and high-LET radiations in vitro, we reported that intra-chromosome <span class="hlt">exchanges</span> occurred preferentially between a break in the 3p21 and one in the 3q11 regions, and the breaks involving in inter-chromosome <span class="hlt">exchanges</span> occurred in two regions towards the telomeres of the chromosome. <span class="hlt">Exchanges</span> were also observed between a break in 3p21 and one in 3q26, but few <span class="hlt">exchanges</span> were observed between breaks in 3q11 and 3q26, even though the two regions are located on the same arm of the chromosome. In this study, human epithelial cells were fixed at G1 phase and the interphase cells were hybridized using the XCyte3 mBAND kit from MetaSystems. The z-section images of chromosome 3 were captured with a Leica and an LSM 510 Meta laser scanning confocal microscopes. A total of 100 chromosomes were analyzed. The reconstruction of three dimensional structure of interphase chromosome 3 with six different colored regions was achieved using the Imaris software. The relative distance between different regions was measured as well. We further analyzed fragile sites on the chromosome that have been identified in various types of cancers. The data showed that, in majority of the cells, the regions containing 3p21 and 3q11 are colocalized in the center of the chromosome, whereas, the regions towards the telomeres of the chromosome are either physically wrapping outside the chromosome center or with arms sticking out. Our results demonstrated that the distribution of breaks involved in radiation-<span class="hlt">induced</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.9059B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.9059B"><span id="translatedtitle">Modeling dune-<span class="hlt">induced</span> hyporheic <span class="hlt">exchange</span> and nutrient reactions in stream sediments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bardini, L.; Boano, F.; Cardenas, M. B.; Revelli, R.; Ridolfi, L.</p> <p>2012-04-01</p> <p>The <span class="hlt">exchange</span> of water across the streambed plays an important role in the ecology of fluvial environments, since it assures the connections of surface and subsurface waters, which have very different peculiarities. Water-borne chemicals are also involved in the process: they enter the sediments with the water and they are transformed into oxidized or reduced substances by biogeochemical reactions, mediated by the hyporheic microbiota. In particular, organic substances can be used as electron donors in a series of redox reactions, with different electron acceptors, e.g., oxygen and nitrate. Nitrification and other secondary reactions also occur as soon as water enters the streambed. These pore-scale transformations concur to affect subsurface solute concentrations and, consequently, the chemistry of upwelling water and the quality of the stream environment. The <span class="hlt">exchange</span> with the hyporheic zone occurs in response to variations in bed topography, with a very wide range of spatial and temporal scales. For instance, small-scale <span class="hlt">exchanges</span> are mainly <span class="hlt">induced</span> by river bed forms, like ripples and dunes, while large-scale <span class="hlt">exchanges</span> depend on larger geomorphological features. In this work we focus on small-scale <span class="hlt">exchange</span> <span class="hlt">induced</span> by the presence of dunes on the streambed, investigating the interplay of hydrological and biogeochemical processes and their effects on solute spatial distribution in the sediments. We numerically simulate the turbulent water flow and the pressure distribution on the streambed and then we evaluate the coupled flow field and biogeochemical reactions in the hyporheic zone in steady-state conditions. Four representative reactive compounds are taken into account: dissolved organic carbon (DOC), oxygen (O2), nitrate (NO3-) and ammonium (NH4+). Sensitivity analyses are also performed to analyze the influence of hydrological and chemical properties of the system on solute reaction rates. The results demonstrate that the stream water quality can strongly</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMEP43C3583L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMEP43C3583L"><span id="translatedtitle">Hyporheic <span class="hlt">exchange</span> <span class="hlt">induced</span> by channel-spanning obstacles in a coarse, highly-permeable laboratory streambed</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lichtner, D.; Best, J.; Blois, G.; Kim, T.; Christensen, K. T.</p> <p>2014-12-01</p> <p>Knowledge of flow over and through a porous streambed is essential to understanding hyporheic <span class="hlt">exchange</span> in coarse gravel-bed rivers, where turbulence in the stream flow can penetrate significantly into the streambed. To study the turbulent momentum <span class="hlt">exchange</span> between a stream and gravel streambed, laboratory experiments were conducted in a 2.5 m long refractive-index matching (RIM) laboratory flume. A flat gravel bed was simulated using cubically packed acrylic spheres (Ds = 1.27 cm) with a refractive index, RI = 1.495, that matched that of the NaI solution in the flume. Thus, optical access to the pore spaces could be gained, and the flow field from the near-bed and into the pore spaces could be measured with particle image velocimetry (PIV). Dense 2-D velocity vector fields were measured for two bed configurations: (1) a flat, porous, bed composed of three layers of spheres and (2) a flat bed with a cylinder (Dc = 1.27 cm) placed atop it, to <span class="hlt">induce</span> hyporheic <span class="hlt">exchange</span> in the manner of a channel-spanning large woody debris. The flow over and through the bed produced by the cylinder is found to be dramaticallydifferent from that associated with a flat bed. The mean velocity field produced by the cylinder exhibited strong flow downwelling in the pore space immediately upstream of the cylinder and upwelling several pore spaces downstream. In particular, the shear layer separating from the cylinder remained parallel to the bed from the point of flow separation to the edge of the field of view, instead of reattaching several grain diameters downstream. The cylinder also promoted increased vertical momentum <span class="hlt">exchange</span> as suggested by turbulent kinetic energy maps.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25970916','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25970916"><span id="translatedtitle">[Piezoresistivity of ultra-thin poly-silicon layer by aluminum-<span class="hlt">induced</span> layer <span class="hlt">exchange</span>].</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Cheng-long; Ma, Jun; Fan, Duo-wang; Xing, Da; Liu, Song-hao</p> <p>2015-02-01</p> <p>Poly-Si film, due to its favorable piezoresistive properties, has been widely used in piezoresistive sensors. The previous researches have shown that the ultra-thin poly-Si film have better piezoresistive properties than common poly-silicon film, and have promising future of application. A promising method to obtain large grained high quality poly-silicon films by low-temperature crystallization of an amorphous precursor material is the aluminum-<span class="hlt">induced</span> layer <span class="hlt">exchange</span> (ALILE). In this paper, ultra-thin poly-Si films were prepared by aluminum <span class="hlt">induced</span> layer <span class="hlt">exchange</span> (ALILE). Experimental results of Raman spectroscopy show that a narrow and symmetrical Raman peak at the wave number of about 518 cm(-1) was observed for all samples, indicating that the films were fully crystallized. XRD results show that the crystallites of ultra-thin poly-silicon layer were preferably (111) and (220) oriented. Hall affect measurements show that hole concentration of the films (p-type) were between 9 x 10(18) and 6 x 10(19) cm(-3). Restorative properties show that the piezoresistors exhibit gauge factors (GFs) up to 60, with temperature coefficients of GF (TCGF) between -0.17-0% degree C and temperature coefficients of resistance (TCR) between -0.2 and -0.1% degrees C. The study of the ultra-thin poly-Si films by ALILE is completed, and the study results lay a foundation for application of the film PMID:25970916</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014LSSR....2...23Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014LSSR....2...23Z"><span id="translatedtitle">Proximity within interphase chromosome contributes to the breakpoint distribution in radiation-<span class="hlt">induced</span> intrachromosomal <span class="hlt">exchanges</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Ye; Uhlemeyer, Jimmy; Hada, Megumi; Asaithamby, A.; Chen, David J.; Wu, Honglu</p> <p>2014-07-01</p> <p>Previously, we reported that breaks involved in chromosome aberrations were clustered in several regions of chromosome 3 in human mammary epithelial cells after exposures to either low- or high-LET radiation. In particular, breaks in certain regions of the chromosome tended to rejoin with each other to form an intrachromosome <span class="hlt">exchange</span> event. This study tests the hypothesis that proximity within a single chromosome in interphase cell nuclei contributes to the distribution of radiation-<span class="hlt">induced</span> chromosome breaks. Chromosome 3 in G1 human mammary epithelial cells was hybridized with the multicolor banding in situ hybridization (mBAND) probes that distinguish the chromosome in six differently colored regions, and the location of these regions was measured with a laser confocal microscope. Results of the study indicated that, on a multi-mega base pair scale of the DNA, the arrangement of chromatin was non-random. Both telomere regions tended to be located towards the exterior of the chromosome domain, whereas the centromere region towards the interior. In addition, the interior of the chromosome domain was preferentially occupied by the p-arm of the chromatin, which is consistent with our previous finding of intrachromosome <span class="hlt">exchanges</span> involving breaks on the p-arm and in the centromere region of chromosome 3. Other factors, such as the fragile sites in the 3p21 band and gene regulation, may also contribute to the breakpoint distribution in radiation-<span class="hlt">induced</span> chromosome aberrations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040088723&hterms=chromosome&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D%2528Y%2Bchromosome%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040088723&hterms=chromosome&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D%2528Y%2Bchromosome%2529"><span id="translatedtitle">Rejoining of isochromatid breaks <span class="hlt">induced</span> by heavy ions in G2-phase normal human fibroblasts</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kawata, T.; Durante, M.; Furusawa, Y.; George, K.; Ito, H.; Wu, H.; Cucinotta, F. A.</p> <p>2001-01-01</p> <p>We reported previously that exposure of normal human fibroblasts in G2 phase of the cell cycle to high-LET radiation produces a much higher frequency of isochromatid breaks than exposure to gamma rays. We concluded that an increase in the production of isochromatid breaks is a signature of initial high-LET radiation-<span class="hlt">induced</span> G2-phase damage. In this paper, we report the repair kinetics of isochromatid breaks <span class="hlt">induced</span> by high-LET radiation in normal G2-phase human fibroblasts. Exponentially growing human fibroblasts (AG1522) were irradiated with gamma rays or energetic carbon (290 MeV/nucleon), silicon (490 MeV/nucleon), or iron (200 MeV/nucleon) ions. Prematurely condensed chromosomes were <span class="hlt">induced</span> by calyculin A after different postirradiation incubation times ranging from 0 to 600 min. Chromosomes were stained with Giemsa, and aberrations were scored in cells at G2 phase. G2-phase fragments, the result of the induction of isochromatid breaks, decreased quickly with incubation time. The curve for the kinetics of the rejoining of <span class="hlt">chromatid</span>-type breaks showed a slight upward curvature with time after exposure to 440 keV/microm iron particles, probably due to isochromatid-isochromatid break rejoining. The formation of <span class="hlt">chromatid</span> <span class="hlt">exchanges</span> after exposure to high-LET radiation therefore appears to be underestimated, because isochromatid-isochromatid <span class="hlt">exchanges</span> cannot be detected. Increased induction of isochromatid breaks and rejoining of isochromatid breaks affect the overall kinetics of <span class="hlt">chromatid</span>-type break rejoining after exposure to high-LET radiation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6220543','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6220543"><span id="translatedtitle">Review of the international symposium, sister <span class="hlt">chromatid</span> <span class="hlt">exchanges</span>: twenty-five years of experimental research</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tice, R.R.; Lambert, B.; Morimoto, Kanehisa; Hollaender, A.</p> <p>1983-01-01</p> <p>The purpose of this symposium was to honor initial research at Brookhaven by bringing internationally recognized leaders in the fields of genetics, cytogenetics, carcinogenesis, mutagenesis, radiation biology, toxicology, and environmental health together into an open forum to present and discuss: (1) current knowledge of the induction and formation of SCEs and their relationship to other biological endpoints, including carcinogenesis, mutagenesis, transformation, clastogenesis, DNA damage and repair, and cellular toxicity; (2) the optimal strategies for the utilization of SCEs in genetic toxicology testing schemes involving in vitro and in vivo exposure situations; (3) the most valid statistical methods for analyzing SCE data obtained from cells in culture, from cells in intact organisms, and from cells in humans; (4) the relevance of SCEs as an indicator of human disease states, both inherited and acquired, and of progress in disease treatment; and (5) the use of SCEs as an indicator of human exposure to genotoxic agents and their relevance as a prognosticator of future adverse health outcomes. This report summarizes the presentations. 7 references. (ACR)</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24955171','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24955171"><span id="translatedtitle">Tempol protects human lymphocytes from genotoxicity <span class="hlt">induced</span> by cisplatin.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Khabour, Omar F; Alzoubi, Karem H; Mfady, Doa'a S; Alasseiri, Mohammed; Hasheesh, Taghrid F</p> <p>2014-01-01</p> <p>The use of cisplatin in treatments of human malignancies is limited by its side effects that include DNA damage and the subsequent risk of developing secondary cancer. In this study, we examined the possible protective effect of Tempol against DNA damage <span class="hlt">induced</span> by cisplatin in human lymphocytes using chromosomal aberrations (CAs) and sister <span class="hlt">chromatid</span> <span class="hlt">exchanges</span> (SCEs) assays. Cisplatin <span class="hlt">induced</span> significant elevation in the frequencies of CAs and SCEs in cultured human lymphocytes (P < 0.01). Treatment of lymphocytes with Tempol significantly lowered CAs and SCEs <span class="hlt">induced</span> by cisplatin. Tempol alone did not affect spontaneous levels of SCEs and CAs observed in the control group (P > 0.05). In conclusion, Tempol protects human lymphocytes against genotoxicity <span class="hlt">induced</span> by the anticancer drug cisplatin. PMID:24955171</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23756266','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23756266"><span id="translatedtitle">Role of plasma <span class="hlt">exchange</span> in autoimmune hyperthyroidism complicated by severe tiamazol-<span class="hlt">induced</span> cholestatic jaundice.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Miljić, D; Stojanović, M; Ješić, R; Bogadnović, G; Popović, V</p> <p>2013-10-01</p> <p>Therapeutic plasma <span class="hlt">exchange</span> (TPE) is an alternative treatment for hyperthyroidism, resulting in a rapid decline in plasma thyroid hormones and anti-thyroid antibodies. TPE has also been used both in primary liver disease and in drug-<span class="hlt">induced</span> cholestasis. Data on thyrotoxic patients with severe hepatic complications are scarce. Cholestasis <span class="hlt">induced</span> by imidazol-derived anti-thyroid drugs is extremely rare. The use of TPE for treating this complication was not previously reported. We report the experience of one such patient with a favorable response to TPE. A 45-year-old male patient with Graves' disease, presented with severe jaundice and extremely high serum bilirubin levels due to hepatotoxicity <span class="hlt">induced</span> by tiamazol. Through extensive investigation primary liver disease, including viral, metabolic, neoplastic and autoimmune disease, as a cause of cholestasis were all ruled out. The patient underwent total of 6 TPEs which in combination with low dose of glucocorticoids and standard supportive measures, resulted in normalization of thyroid hormones and normal liver function tests. TPE provided a safe, rapid and effective treatment of severe drug-<span class="hlt">induced</span> cholestasis and auto immune hyperthyroidism. From this case we conclude that TPE should be considered as a valuable alternative therapeutic option in thyrotoxic patients with severe complications. Guidelines and indication criteria for TPE treatment in patients with hyperthyroidism are still lacking. PMID:23756266</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15254761','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15254761"><span id="translatedtitle">The Na+/H+ <span class="hlt">exchange</span> inhibitor HOE642 prevents stress-<span class="hlt">induced</span> epithelial barrier dysfunction.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nowak, Peter; Blaheta, Roman; Schuller, Alina; Cinatl, Jindrich; Wimmer-Greinecker, Gerhard; Moritz, Anton; Scholz, Martin</p> <p>2004-08-01</p> <p>Recently, evidence has been obtained that the Na+/H+ <span class="hlt">exchange</span> (NHE) inhibitor HOE642 may stabilize endothelial and epithelial barrier function in vivo. However, the underlying mechanisms are not known. Therefore, we studied the influence of HOE642 on the barrier function of the epithelial cell line CaCo2. The phorbolester phorbol 12-myristate 13-acetate (PMA) was used to <span class="hlt">induce</span> hyperpermeability of the epithelial layer which was indirectly determined by measuring the transepithelial electrical resistance (TER). Confocal laser scan microscopy (LSM) served to analyze the intracellular localization of adherens and tight junction molecules. In five independent experiments we found that HOE642 increased TER in non-treated CaCo2 cells (control: 350 +/- 28 Omega/cm2; HOE642: 444 +/- 53 Omega/cm2) and prevented PMA-<span class="hlt">induced</span> barrier dysfunction (PMA: 33 +/- 12 Omega/cm2; PMA plus HOE642: 496 +/- 47 Omega/cm2). LSM showed that HOE642 prevented the PMA-<span class="hlt">induced</span> disassociation of the zonula adherens molecule beta-catenin from the cell membrane and the decreased expression of the zonula occludens molecule ZO-1. From our data we conclude that HOE642 may prevent stress-<span class="hlt">induced</span> epithelial dysfunction by stabilization of cell membrane-associated junction molecules. PMID:15254761</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/8625980','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/8625980"><span id="translatedtitle">A third interferon-gamma-<span class="hlt">induced</span> subunit <span class="hlt">exchange</span> in the 20S proteasome.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Groettrup, M; Kraft, R; Kostka, S; Standera, S; Stohwasser, R; Kloetzel, P M</p> <p>1996-04-01</p> <p>The 20S proteasome is a protease complex of functional importance for antigen processing. Two of the 14 proteasome subunits, delta and MB1, can be replaced by the major histocompatibility complex (MHC)-encoded and interferon-gamma (IFN-gamma)-<span class="hlt">inducible</span> subunits LMP2 and LMP7, respectively. LMP2 and LMP7 alter the cleavage site specificity of the 20S proteasome and are required for the efficient generation of T cell epitopes from a number of viral proteins and for optimal MHC class I cell surface expression. We compared the 20S proteasome subunit pattern from IFN-gamma-<span class="hlt">induced</span> and non-<span class="hlt">induced</span> mouse fibroblasts on two-dimensional gels and identified a third subunit <span class="hlt">exchange</span> by microsequencing: the non-MHC-encoded subunit MECL-1 is <span class="hlt">induced</span> by IFN-gamma and replaces a sofar barely characterized beta subunit designated 'MC14'. In analogy to LMP2 and LMP7, MECL-1 may be functional in MHC class I-restricted antigen presentation. PMID:8625980</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2941706','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2941706"><span id="translatedtitle">Sodium hydrogen <span class="hlt">exchanger</span> as a mediator of hydrostatic edema <span class="hlt">induced</span> intestinal contractile dysfunction</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Uray, Karen S.; Shah, Shinil K.; Radhakrishnan, Ravi S.; Jimenez, Fernando; Walker, Peter A.; Stewart, Randolph H.; Laine, Glen A.; Cox, Charles S.</p> <p>2010-01-01</p> <p>Background Resuscitation-<span class="hlt">induced</span> intestinal edema is associated with early and profound mechanical changes in intestinal tissue. We hypothesize that the sodium hydrogen <span class="hlt">exchanger</span> (NHE), a mechano-responsive ion channel, is a mediator of edema-<span class="hlt">induced</span> intestinal contractile dysfunction. Methods An animal model of hydrostatic intestinal edema was utilized for all experiments. NHE isoforms 1-3 mRNA and protein were evaluated. Subsequently, the effects of NHE inhibition (with 5-(N-ethyl-N-isopropyl) amiloride (EIPA)) on wet to dry ratios, signal transduction and activator of transcription (STAT)-3, intestinal smooth muscle myosin light chain (MLC) phosphorylation, intestinal contractile activity, and intestinal transit were measured. Results NHE1-3 mRNA and protein levels were significantly increased in the small intestinal mucosa with the induction of intestinal edema. Administration of EIPA, an NHE inhibitor, attenuated validated markers of intestinal contractile dysfunction <span class="hlt">induced</span> by edema as measured by decreased STAT-3 activation, increased MLC phosphorylation, improved intestinal contractile activity, and enhanced intestinal transit. Conclusion The mechano-responsive ion channel NHE may mediate edema-<span class="hlt">induced</span> intestinal contractile dysfunction, possibly via a STAT-3 related mechanism. PMID:20553904</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4401699','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4401699"><span id="translatedtitle">Na+/H+ <span class="hlt">Exchanger</span> Isoform 1-<span class="hlt">Induced</span> Osteopontin Expression Facilitates Cardiomyocyte Hypertrophy</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Mohamed, Iman A.; Gadeau, Alain-Pierre; Fliegel, Larry; Lopaschuk, Gary; Mlih, Mohamed; Abdulrahman, Nabeel; Fillmore, Natasha; Mraiche, Fatima</p> <p>2015-01-01</p> <p>Enhanced expression and activity of the Na+/H+ <span class="hlt">exchanger</span> isoform 1 (NHE1) has been implicated in cardiomyocyte hypertrophy in various experimental models. The upregulation of NHE1 was correlated with an increase in osteopontin (OPN) expression in models of cardiac hypertrophy (CH), and the mechanism for this remains to be delineated. To determine whether the expression of active NHE1-<span class="hlt">induces</span> OPN and contributes to the hypertrophic response in vitro, cardiomyocytes were infected with the active form of the NHE1 adenovirus or transfected with OPN silencing RNA (siRNA-OPN) and characterized for cardiomyocyte hypertrophy. Expression of NHE1 in cardiomyocytes resulted in a significant increase in cardiomyocyte hypertrophy markers: cell surface area, protein content, ANP mRNA and expression of phosphorylated-GATA4. NHE1 activity was also significantly increased in cardiomyocytes expressing active NHE1. Interestingly, transfection of cardiomyocytes with siRNA-OPN significantly abolished the NHE1-<span class="hlt">induced</span> cardiomyocyte hypertrophy. siRNA-OPN also significantly reduced the activity of NHE1 in cardiomyocytes expressing NHE1 (68.5±0.24%; P<0.05), confirming the role of OPN in the NHE1-<span class="hlt">induced</span> hypertrophic response. The hypertrophic response facilitated by NHE1-<span class="hlt">induced</span> OPN occurred independent of the extracellular-signal-regulated kinases and Akt, but required p90-ribosomal S6 kinase (RSK). The ability of OPN to facilitate the NHE1-<span class="hlt">induced</span> hypertrophic response identifies OPN as a potential therapeutic target to reverse the hypertrophic effect <span class="hlt">induced</span> by the expression of active NHE1. PMID:25884410</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JIEx...22...53A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JIEx...22...53A"><span id="translatedtitle">Electrodialysis of Sulfuric Acid with Cation-<span class="hlt">Exchange</span> Membranes Prepared by Electron-Beam-<span class="hlt">Induced</span> Graft Polymerization</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Asari, Yuki; Shoji, Nobuyoshi; Miyoshi, Kazuyoshi; Umeno, Daisuke; Saito, Kyoichi</p> <p></p> <p>Strongly acidic cation-<span class="hlt">exchange</span> membranes were prepared by the electron-beam-<span class="hlt">induced</span> graft polymerization of glycidyl methacrylate onto a high-density polyethylene film with a thickness of 35 μm and the subsequent conversion of the resulting epoxy group into a sulfonic acid group. The resulting cation-<span class="hlt">exchange</span> membranes with various ion-<span class="hlt">exchange</span> capacities or sulfonic acid group densities ranging from 1.9 to 2.7 mmol/g were applied to the enrichment of 0.50 mol/L sulfuric acid by electrodialysis. Concentrated sulfuric acids at concentrations of 1.4 to 2.9 mol/L were obtained in the concentrate chamber during the electrodialysis operated at 30 mA/cm2 and 298 K, using a pair of this cation-<span class="hlt">exchange</span> membrane and a commercially available anion-<span class="hlt">exchange</span> membrane.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25141009','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25141009"><span id="translatedtitle">IL-17A <span class="hlt">induces</span> Pendrin expression and chloride-bicarbonate <span class="hlt">exchange</span> in human bronchial epithelial cells.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Adams, Kelly M; Abraham, Valsamma; Spielman, Daniel; Kolls, Jay K; Rubenstein, Ronald C; Conner, Gregory E; Cohen, Noam A; Kreindler, James L</p> <p>2014-01-01</p> <p>The epithelium plays an active role in the response to inhaled pathogens in part by responding to signals from the immune system. Epithelial responses may include changes in chemokine expression, increased mucin production and antimicrobial peptide secretion, and changes in ion transport. We previously demonstrated that interleukin-17A (IL-17A), which is critical for lung host defense against extracellular bacteria, significantly raised airway surface pH in vitro, a finding that is common to a number of inflammatory diseases. Using microarray analysis of normal human bronchial epithelial (HBE) cells treated with IL-17A, we identified the electroneutral chloride-bicarbonate <span class="hlt">exchanger</span> Pendrin (SLC26A4) as a potential mediator of this effect. These data were verified by real-time, quantitative PCR that demonstrated a time-dependent increase in Pendrin mRNA expression in HBE cells treated with IL-17A up to 48 h. Using immunoblotting and immunofluorescence, we confirmed that Pendrin protein expression is increased in IL-17 treated HBE cells and that it is primarily localized to the mucosal surface of the cells. Functional studies using live-cell fluorescence to measure intracellular pH demonstrated that IL-17A <span class="hlt">induced</span> chloride-bicarbonate <span class="hlt">exchange</span> in HBE cells that was not present in the absence of IL-17A. Furthermore, HBE cells treated with short interfering RNA against Pendrin showed substantially reduced chloride-bicarbonate <span class="hlt">exchange</span>. These data suggest that Pendrin is part of IL-17A-dependent epithelial changes and that Pendrin may therefore be a therapeutic target in IL-17A-dependent lung disease. PMID:25141009</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4290709','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4290709"><span id="translatedtitle">Selective Na+/Ca2+ <span class="hlt">exchanger</span> inhibition prevents Ca2+ overload-<span class="hlt">induced</span> triggered arrhythmias</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Nagy, Norbert; Kormos, Anita; Kohajda, Zsófia; Szebeni, Áron; Szepesi, Judit; Pollesello, Piero; Levijoki, Jouko; Acsai, Károly; Virág, László; Nánási, Péter P; Papp, Julius Gy; Varró, András; Tóth, András</p> <p>2014-01-01</p> <p>Background and Purpose Augmented Na+/Ca2+ <span class="hlt">exchanger</span> (NCX) activity may play a crucial role in cardiac arrhythmogenesis; however, data regarding the anti-arrhythmic efficacy of NCX inhibition are debatable. Feasible explanations could be the unsatisfactory selectivity of NCX inhibitors and/or the dependence of the experimental model on the degree of Ca2+i overload. Hence, we used NCX inhibitors SEA0400 and the more selective ORM10103 to evaluate the efficacy of NCX inhibition against arrhythmogenic Ca2+i rise in conditions when [Ca2+]i was augmented via activation of the late sodium current (INaL) or inhibition of the Na+/K+ pump. Experimental Approach Action potentials (APs) were recorded from canine papillary muscles and Purkinje fibres by microelectrodes. NCX current (INCX) was determined in ventricular cardiomyocytes utilizing the whole-cell patch clamp technique. Ca2+i transients (CaTs) were monitored with a Ca2+-sensitive fluorescent dye, Fluo-4. Key Results Enhanced INaL increased the Ca2+ load and AP duration (APD). SEA0400 and ORM10103 suppressed INCX and prevented/reversed the anemone toxin II (ATX-II)-<span class="hlt">induced</span> [Ca2+]i rise without influencing APD, CaT or cell shortening, or affecting the ATX-II-<span class="hlt">induced</span> increased APD. ORM10103 significantly decreased the number of strophanthidin-<span class="hlt">induced</span> spontaneous diastolic Ca2+ release events; however, SEA0400 failed to restrict the veratridine-<span class="hlt">induced</span> augmentation in Purkinje-ventricle APD dispersion. Conclusions and Implications Selective NCX inhibition – presumably by blocking revINCX (reverse mode NCX current) – is effective against arrhythmogenesis caused by [Na+]i-<span class="hlt">induced</span> [Ca2+]i elevation, without influencing the AP waveform. Therefore, selective INCX inhibition, by significantly reducing the arrhythmogenic trigger activity caused by the perturbed Ca2+i handling, should be considered as a promising anti-arrhythmic therapeutic strategy. PMID:25073832</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/2791669','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/2791669"><span id="translatedtitle">Pulmonary gas <span class="hlt">exchange</span> during histamine-<span class="hlt">induced</span> bronchoconstriction in asthmatic subjects.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Burke, T V; Küng, M; Burki, N K</p> <p>1989-10-01</p> <p>Bronchial provocation for testing airway hyperreactivity is now well-established. However, the effects of histamine-<span class="hlt">induced</span> bronchoconstriction on pulmonary gas <span class="hlt">exchange</span> in man have not been systematically studied. We empirically noted marked decreases in PaO2 in some asthmatic subjects following <span class="hlt">induced</span> bronchoconstriction. Nine subjects with mild, stable asthma were studied, each on two separate days. The first determined the dose of inhaled histamine necessary to decrease FEV1 by 20 percent and the relationship to lung volume and to pulmonary resistance by the interrupter technique (Rint). On the second day arterial blood gases, ventilation, Rint, and the anatomic (VDan) and physiologic (VDphys) dead spaces were measured simultaneously. There was a significant (p less than 0.05), profound fall in PaO2 (mean, -21.8 mm Hg) and in P(A-a)O2 (mean +14.7 mm Hg) within 5 min after bronchoconstriction, associated with a significant (p less than 0.05) increase in respiratory frequency (mean +5.1 min-1); and decrease in tidal volume (mean, -0.3 L). The ratio VDphys/VT increased significantly (p less than 0.05; mean change, +0.08) even though VDan and VDphys did not. Bronchoconstriction <span class="hlt">induced</span> the broadening of ventilation (V)/perfusion (Q) ratios, with, most likely, an increase in areas of high V/Q. Histamine-<span class="hlt">induced</span> bronchoconstriction in mild asthma results in a marked fall in PaO2 due to <span class="hlt">induced</span> V/Q inequality. Therefore, histamine airway challenge should be used with caution in patients with any preexisting hypoxemia. PMID:2791669</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5017209','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5017209"><span id="translatedtitle"><span class="hlt">Exchange</span> factors directly activated by cAMP mediate melanocortin 4 receptor-<span class="hlt">induced</span> gene expression</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Glas, Evi; Mückter, Harald; Gudermann, Thomas; Breit, Andreas</p> <p>2016-01-01</p> <p>Gs protein-coupled receptors regulate many vital body functions by activation of cAMP response elements (CRE) via cAMP-dependent kinase A (PKA)-mediated phosphorylation of the CRE binding protein (CREB). Melanocortin 4 receptors (MC4R) are prototypical Gs-coupled receptors that orchestrate the hypothalamic control of food-intake and metabolism. Remarkably, the significance of PKA for MC4R-<span class="hlt">induced</span> CRE-dependent transcription in hypothalamic cells has not been rigorously interrogated yet. In two hypothalamic cell lines, we observed that blocking PKA activity had only weak or no effects on reporter gene expression. In contrast, inhibitors of <span class="hlt">exchange</span> factors directly activated by cAMP-1/2 (EPAC-1/2) mitigated MC4R-<span class="hlt">induced</span> CRE reporter activation and mRNA induction of the CREB-dependent genes c-fos and thyrotropin-releasing hormone. Furthermore, we provide first evidence that extracellular-regulated kinases-1/2 (ERK-1/2) activated by EPACs and not PKA are the elusive CREB kinases responsible for MC4R-<span class="hlt">induced</span> CREB/CRE activation in hypothalamic cells. Overall, these data emphasize the pivotal role of EPACs rather than PKA in hypothalamic gene expression elicited by a prototypical Gs-coupled receptor. PMID:27612207</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26302862','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26302862"><span id="translatedtitle">Solvent <span class="hlt">exchange-induced</span> in situ forming gel comprising ethyl cellulose-antimicrobial drugs.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Phaechamud, Thawatchai; Mahadlek, Jongjan</p> <p>2015-10-15</p> <p>Solvent-<span class="hlt">exchanged</span> in situ forming gel is a drug delivery system which is in sol form before administration. When it contacts with the body fluid, then the water miscible organic solvent dissipates and water penetrates into the system, leading the polymer precipitation as in situ gel at the site of injection. The aim of this research was to study the parameters affecting the gel properties, drug release and antimicrobial activities of the in situ forming gels prepared from ethyl cellulose (EC) dissolved in N-methyl pyrrolidone (NMP) to deliver the antimicrobial agents (doxycycline hyclate, metronidazole and benzyl peroxide) for periodontitis treatment. The gel appearance, pH, viscosity, rheology, syringeability, gel formation, rate of water diffusion into the gels, in vitro degradation, drug release behavior and antimicrobial activities against Staphylococcus aureus, Escherichia coli, Candida albicans, Streptococcus mutans and Porphyrommonas gingivalis were determined. Increasing the amount of EC increased the viscosity of system while still exhibiting Newtonian flow and increased the work of syringeability whereas decreased the releasing of drug. The system transformed into the rigid gel formation after being injected into the simulated gingival crevicular fluid. The developed systems containing 5% w/w antimicrobial agent showed the antimicrobial activities against all test bacteria. Thus the developed solvent <span class="hlt">exchange-induced</span> in situ forming gels comprising EC-antimicrobial drugs exhibited potential use for periodontitis treatment. PMID:26302862</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ApPhL.105o2402C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ApPhL.105o2402C"><span id="translatedtitle"><span class="hlt">Exchange</span> bias field <span class="hlt">induced</span> symmetry-breaking of magnetization rotation in two-dimension</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cui, B.; Song, C.; Sun, Y.; Wang, Y. Y.; Zhao, Y. L.; Li, F.; Wang, G. Y.; Zeng, F.; Pan, F.</p> <p>2014-10-01</p> <p>We investigate the effect of strain-<span class="hlt">induced</span> intrinsic <span class="hlt">exchange</span> bias field (HEB) on the magnetization rotation process in a nominally "single" layered La2/3Sr1/3MnO3 (LSMO) film. The intrinsic <span class="hlt">exchange</span> bias appears when the LSMO film is grown on LaAlO3 substrate. The HEB is proved to be an effective approach to tuning the in-plane magnetization rotation, producing a 360° instead of 180° periodicity in the anisotropic magnetoresistance curves measured in a low external magnetic field. The planar Hall effect curves are asymmetric when the in-plane magnetization rotate between two orthogonal axes of LSMO, helped or hindered by the HEB. Our study reveals that the HEB in but not limited to LSMO with phase separation exhibits an unprecedentedly two-dimensional effect rather than merely establishing a reference magnetization direction as achieved in ferromagnetic/antiferromagnetic bilayers, thus furthering the cognition of manipulating the magnetization orientation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24777198','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24777198"><span id="translatedtitle">High-temperature electromagnons in the magnetically <span class="hlt">induced</span> multiferroic cupric oxide driven by intersublattice <span class="hlt">exchange</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jones, S P P; Gaw, S M; Doig, K I; Prabhakaran, D; Hétroy Wheeler, E M; Boothroyd, A T; Lloyd-Hughes, J</p> <p>2014-01-01</p> <p>Magnetically <span class="hlt">induced</span> ferroelectric multiferroics present an exciting new paradigm in the design of multifunctional materials, by intimately coupling magnetic and polar order. Magnetoelectricity creates a novel quasiparticle excitation--the electromagnon--at terahertz frequencies, with spectral signatures that unveil important spin interactions. To date, electromagnons have been discovered at low temperature (<70 K) and predominantly in rare-earth compounds such as RMnO3. Here we demonstrate using terahertz time-domain spectroscopy that intersublattice <span class="hlt">exchange</span> in the improper multiferroic cupric oxide (CuO) creates electromagnons at substantially elevated temperatures (213-230 K). Dynamic magnetoelectric coupling can therefore be achieved in materials, such as CuO, that exhibit minimal static cross-coupling. The electromagnon strength and energy track the static polarization, highlighting the importance of the underlying cycloidal spin structure. Polarized neutron scattering and terahertz spectroscopy identify a magnon in the antiferromagnetic ground state, with a temperature dependence that suggests a significant role for biquadratic <span class="hlt">exchange</span>. PMID:24777198</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016JaJAP..55hNB07K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016JaJAP..55hNB07K&link_type=ABSTRACT"><span id="translatedtitle">Surface-segregated Si and Ge ultrathin films formed by Ag-<span class="hlt">induced</span> layer <span class="hlt">exchange</span> process</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kurosawa, Masashi; Ohta, Akio; Araidai, Masaaki; Zaima, Shigeaki</p> <p>2016-08-01</p> <p>We have developed a new method of growing Si or Ge ultrathin films on a Ag(111) surface by using a Ag-<span class="hlt">induced</span> layer <span class="hlt">exchange</span> (ALEX) process toward the creation of 2D honeycomb sheets of Si and Ge, known as silicene and germanene, respectively. In the present paper, we clarify ALEX features, specifically the surface segregation of Si (or Ge) atoms from the underlying substrate, focusing on the annealing temperature and time. Hard X-ray photoelectron spectroscopy analyses demonstrate that surface-segregated Si (or Ge) exists on the Ag surfaces after the epitaxial growth of the Ag layer on Si(111) [or Ge(111)] substrates; the amount of segregated Si (or Ge) can be controlled by a subsequent annealing. Also, we find that the segregation of an ultrathin Si or Ge layer proceeds at an interface between Ag and the AlO x capping layer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AcSpA..95..533V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AcSpA..95..533V"><span id="translatedtitle">Multivariate analysis of Ion Beam <span class="hlt">Induced</span> Luminescence spectra of irradiated silver ion-<span class="hlt">exchanged</span> silicate glasses</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Valotto, Gabrio; Quaranta, Alberto; Cattaruzza, Elti; Gonella, Francesco; Rampazzo, Giancarlo</p> <p></p> <p>A multivariate analysis is used for the identification of the spectral features in Ion Beam <span class="hlt">Induced</span> Luminescence (IBIL) spectra of soda-lime silicate glasses doped with silver by Ag+-Na+ ion <span class="hlt">exchange</span>. Both Principal Component Analysis and multivariate analysis were used to characterize time-evolving IBIL spectra of Ag-doped glasses, by means of the identification of the number and of the wavelength positions of the main luminescent features and the study of their evolution during irradiation. This method helps to identify the spectral features of the samples spectra, even when partially overlapped or less intense. This analysis procedure does not require additional input such as the number of peaks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22571943','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22571943"><span id="translatedtitle">Multivariate analysis of Ion Beam <span class="hlt">Induced</span> Luminescence spectra of irradiated silver ion-<span class="hlt">exchanged</span> silicate glasses.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Valotto, Gabrio; Quaranta, Alberto; Cattaruzza, Elti; Gonella, Francesco; Rampazzo, Giancarlo</p> <p>2012-09-01</p> <p>A multivariate analysis is used for the identification of the spectral features in Ion Beam <span class="hlt">Induced</span> Luminescence (IBIL) spectra of soda-lime silicate glasses doped with silver by Ag(+)-Na(+) ion <span class="hlt">exchange</span>. Both Principal Component Analysis and multivariate analysis were used to characterize time-evolving IBIL spectra of Ag-doped glasses, by means of the identification of the number and of the wavelength positions of the main luminescent features and the study of their evolution during irradiation. This method helps to identify the spectral features of the samples spectra, even when partially overlapped or less intense. This analysis procedure does not require additional input such as the number of peaks. PMID:22571943</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23003184','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23003184"><span id="translatedtitle">Effect of interface-<span class="hlt">induced</span> <span class="hlt">exchange</span> fields on cuprate-manganite spin switches.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Yaohua; Visani, C; Nemes, N M; Fitzsimmons, M R; Zhu, L Y; Tornos, J; Garcia-Hernandez, M; Zhernenkov, M; Hoffmann, A; Leon, C; Santamaria, J; te Velthuis, S G E</p> <p>2012-05-18</p> <p>We examine the anomalous inverse spin switch behavior in La0.7Ca0.3MnO3(LCMO)/YBa2Cu3O7-δ (YBCO)/LCMO trilayers by combined transport studies and polarized neutron reflectometry. Measuring magnetization profiles and magnetoresistance in an in-plane rotating magnetic field, we prove that, contrary to many accepted theoretical scenarios, the relative orientation between the two LCMO's magnetizations is not sufficient to determine the magnetoresistance. Rather the field dependence of magnetoresistance is explained by the interplay between the applied magnetic field and the (exponential tail of the) <span class="hlt">induced</span> <span class="hlt">exchange</span> field in YBCO, the latter originating from the electronic reconstruction at the LCMO/YBCO interfaces. PMID:23003184</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150009494','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150009494"><span id="translatedtitle">Proximity Within Interphase Chromosome Contributes to the Breakpoint Distribution in Radiation-<span class="hlt">Induced</span> Intrachromosomal <span class="hlt">Exchanges</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zhang, Ye; Uhlemeyer, Jimmy; Hada, Megumi; Asaithamby, A.; Chen, David J.; Wu, Honglu</p> <p>2015-01-01</p> <p>Previously, we reported that breaks involved in chromosome aberrations were clustered in several regions of chromosome3 in human mammary epithelial cells after exposures to either low-or high-LET radiation. In particular, breaks in certain regions of the chromosome tended to rejoin with each other to form an intrachromosome <span class="hlt">exchange</span> event. This study tests the hypothesis that proximity within a single chromosome in interphase cell nuclei contributes to the distribution of radiation-<span class="hlt">induced</span> chromosome breaks. Chromosome 3 in G1 human mammary epithelial cells was hybridized with the multicolor banding in situ hybridization (mBAND) probes that distinguish the chromosome in six differently colored regions, and the location of these regions was measured with a laser confocal microscope. Results of the study indicated that, on a multi-mega base pair scale of the DNA, the arrangement of chromatin was non-random. Both telomere regions tended to be located towards the exterior of the chromosome domain, whereas the centromere region towards the interior. In addition, the interior of the chromosome domain was preferentially occupied by the p-arm of the chromatin, which is consistent with our previous finding of intrachromosome <span class="hlt">exchanges</span> involving breaks on the p-arm and in the centromere region of chromosome3. Other factors, such as the fragile sites in the 3p21 band and gene regulation, may also contribute to the breakpoint distribution in radiation-<span class="hlt">induced</span> chromosome aberrations. Further investigations suggest that the 3D chromosome folding is cell type and culture condition dependent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/16334295','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/16334295"><span id="translatedtitle">Antigenotoxic effect of allicin against methyl methanesulphonate <span class="hlt">induced</span> genotoxic damage.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Siddique, Yasir Hasan; Afzal, Mohammad</p> <p>2005-07-01</p> <p>Allicin, one of the sulfur compounds especially thiosulphonates of garlic (Allium sativum), possesses antioxidant and thioldisulphide <span class="hlt">exchange</span> activity and is also shown to cause a variety of actions potentially useful for human health. In this investigation we determined its antigenotoxic potential using chromosomal aberrations (CAs) and sister <span class="hlt">chromatid</span> <span class="hlt">exchanges</span> (SCEs) <span class="hlt">induced</span> by methyl methanesulphonate (MMS) as genotoxic end points both in the presence as well as absence of rat liver microsomal activation system (S9 mix) in cultured human lymphocytes. We tested the effect of 5, 10 and 20 microM of allicin on the damage exerted by 60 microM of MMS. The levels of CAs and SCEs were lowered suggesting an antigenotoxic role of allicin against genotoxic damage both in the presence as well as absence of metabolic activation. PMID:16334295</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1783675','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1783675"><span id="translatedtitle">Roles of the sister <span class="hlt">chromatid</span> cohesion apparatus in gene expression, development, and human syndromes</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dorsett, Dale</p> <p>2006-01-01</p> <p>The sister <span class="hlt">chromatid</span> cohesion apparatus mediates physical pairing of duplicated chromosomes. This pairing is essential for appropriate distribution of chromosomes into the daughter cells upon cell division. Recent evidence shows that the cohesion apparatus, which is a significant structural component of chromosomes during interphase, also affects gene expression and development. The Cornelia de Lange (CdLS) and Roberts/SC phocomelia (RBS/SC) genetic syndromes in humans are caused by mutations affecting components of the cohesion apparatus. Studies in Drosophila suggest that effects on gene expression are most likely responsible for developmental alterations in CdLS. Effects on <span class="hlt">chromatid</span> cohesion are apparent in RBS/SC syndrome, but data from yeast and Drosophila point to the likelihood that changes in expression of genes located in heterochromatin could contribute to the developmental deficits. PMID:16819604</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15454308','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15454308"><span id="translatedtitle">Reduction of chrysotile asbestos-<span class="hlt">induced</span> genotoxicity in human peripheral blood lymphocytes by garlic extract.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bhattacharya, Kunal; Yadava, Santosh; Papp, Thilo; Schiffmann, Dietmar; Rahman, Qamar</p> <p>2004-11-28</p> <p>Asbestos fibers are well known environmental carcinogen, however, the underlying mechanisms of their action have still not clearly been identified. Asbestos is capable of depleting glutathione and generating reactive oxygen species (ROS), which are important mediators of damage in biological system. Asbestos-<span class="hlt">induced</span> mutagenecity, may be mediated by the generation. It is known that a number of scavengers and antioxidants attenuate asbestos-<span class="hlt">induced</span> ROS release. Furthermore, it is known that garlic, contains numerous sulfur compounds and glutathione precursors which act as antioxidants and also demonstrate anticarcinogenic properties. The aim of this study was to investigate whether garlic extract has any influence on asbestos-mediated genotoxicity. As an assay system, we applied the micronucleus assay, sister <span class="hlt">chromatid</span> <span class="hlt">exchanges</span>, and chromosomal aberrations with human peripheral blood lymphocytes, which has already been used to analyze the genotoxicity of asbestos fibers. Our results indicate that garlic extract, when administered to the lymphocytes cell culture simultaneously with chrysotile reduced the rates of micronucleus formation, sister <span class="hlt">chromatid</span> <span class="hlt">exchanges</span>, and chromosomal aberrations significantly. We conclude that garlic extract may be an efficient, physiologically tolerable quencher of asbestos-mediated genotoxicity. PMID:15454308</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1470669','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1470669"><span id="translatedtitle">Chl1p, a DNA helicase-like protein in budding yeast, functions in sister-<span class="hlt">chromatid</span> cohesion.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Skibbens, Robert V</p> <p>2004-01-01</p> <p>From the time of DNA replication until anaphase onset, sister <span class="hlt">chromatids</span> remain tightly paired along their length. Ctf7p/Eco1p is essential to establish sister-<span class="hlt">chromatid</span> pairing during S-phase and associates with DNA replication components. DNA helicases precede the DNA replication fork and thus will first encounter chromatin sites destined for cohesion. In this study, I provide the first evidence that a DNA helicase is required for proper sister-<span class="hlt">chromatid</span> cohesion. Characterizations of chl1 mutant cells reveal that CHL1 interacts genetically with both CTF7/ECO1 and CTF18/CHL12, two genes that function in sister-<span class="hlt">chromatid</span> cohesion. Consistent with genetic interactions, Chl1p physically associates with Ctf7p/Eco1p both in vivo and in vitro. Finally, a functional assay reveals that Chl1p is critical for sister-<span class="hlt">chromatid</span> cohesion. Within the budding yeast genome, Chl1p exhibits the highest degree of sequence similarity to human CHL1 isoforms and BACH1. Previous studies revealed that human CHLR1 exhibits DNA helicase-like activities and that BACH1 is a helicase-like protein that associates with the tumor suppressor BRCA1 to maintain genome integrity. Our findings document a novel role for Chl1p in sister-<span class="hlt">chromatid</span> cohesion and provide new insights into the possible mechanisms through which DNA helicases may contribute to cancer progression when mutated. PMID:15020404</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2670183','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2670183"><span id="translatedtitle">Characterization of the components of the putative mammalian sister <span class="hlt">chromatid</span> cohesion complex</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Darwiche, N.; Freeman, L.A.; Strunnikov, A.</p> <p>2009-01-01</p> <p>Establishing and maintaining proper sister <span class="hlt">chromatid</span> cohesion throughout the cell cycle are essential for maintaining genome integrity. To understand how sister <span class="hlt">chromatid</span> cohesion occurs in mammals, we have cloned and characterized mouse orthologs of proteins known to be involved in sister <span class="hlt">chromatid</span> cohesion in other organisms. The cDNAs for the mouse orthologs of SMC1S.c. and SMC3S.c., mSMCB and mSMCD respectively, were cloned and the corresponding transcripts and proteins were characterized. mSMCB and mSMCD are transcribed at similar levels in adult mouse tissues except in testis, which has an excess of mSMCD transcripts. The mSMCB and mSMCD proteins, as well as the PW29 protein, a mouse homolog of Mcd1pS.c./Rad21S.p., form a complex similar to cohesin in X. laevis. mSMCB, mSMCD and PW29 protein levels show no significant cell-cycle dependence. The bulk of the mSMCB, mSMCD and PW29 proteins undergo redistribution from the chromosome vicinity to the cytoplasm during prometaphase and back to the chromatin in telophase. This pattern of intracellular localization suggests a complex role for this group of SMC proteins in chromosome dynamics. The PW29 protein and PCNA, which have both been implicated in sister <span class="hlt">chromatid</span> cohesion, do not colocalize, indicating that these proteins may not function in the same cohesion pathway. Overexpression of a PW29-GFP fusion protein in mouse fibroblasts leads to inhibition of proliferation, implicating this protein and its complex with SMC proteins in the control of mitotic cycle progression. PMID:10375619</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/20582805','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/20582805"><span id="translatedtitle">Antigenotoxic effect of allicin against estradiol-17beta-<span class="hlt">induced</span> genotoxic damage in cultured mammalian cells.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Siddique, Yasir Hasan; Beg, Tanveer; Ara, Gulshan; Gupta, Jyoti; Afzal, Mohammad</p> <p>2010-07-01</p> <p>Antigenotoxic activity of allicin, one of the sulphur compounds of garlic (Allium sativum) which possesses antioxidant and thiol disulphide <span class="hlt">exchange</span> activity, was studied against estradiol-17beta-<span class="hlt">induced</span> genotoxic damage using chromosomal aberrations (CAs) and sister <span class="hlt">chromatid</span> <span class="hlt">exchanges</span> (SCEs) as parameters. Approximately 10, 20 and 40 microM of estradiol-17beta was tested for its genotoxic effect in the presence of metabolic activation and was found to be genotoxic at 20 and 40 microM. Approximately 20 microM of estradiol-17beta was treated along with 5, 10 and 15 microM of allicin, separately, in the presence of metabolic activation. Similar treatments were given with 40 microM of estradiol-17beta. Treatments along with allicin result in the reduction of CAs and SCEs, suggesting its anti-genotoxic activity in human lymphocytes in vitro against estradiol-17beta-<span class="hlt">induced</span> genotoxic damage. PMID:20582805</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015WRR....51.2923C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015WRR....51.2923C"><span id="translatedtitle">Three-dimensional versus two-dimensional bed form-<span class="hlt">induced</span> hyporheic <span class="hlt">exchange</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Xiaobing; Cardenas, M. Bayani; Chen, Li</p> <p>2015-04-01</p> <p>The hyporheic zone is often a critical component of river systems. Hyporheic <span class="hlt">exchange</span> is generally forced by variation in riverbed topography such as due to bed forms. Most previous research on bed form-driven hyporheic flow has focused on two-dimensional (2-D) dunes and ripples, while little has been done on their three-dimensional (3-D) counterparts. Here we compared hyporheic <span class="hlt">exchange</span> and associated metrics for a previously studied pair of corresponding 2-D and 3-D bed forms. To accomplish this, a series of multiphysics computational fluid dynamics models were conducted both in 2-D and 3-D with similar open channel Reynolds numbers (Re). Results show that the pressure gradient along the sediment-water interface is highly sensitive to the spatial structure of bed forms, which consequently determines hyporheic flow dynamics. Hyporheic flux is a function of Re for both 2-D and 3-D dunes via a power law; however, the equivalent 3-D dunes have a higher flux since the 3-D form <span class="hlt">induces</span> more drag. The hyporheic zone depths and volumes are only slightly different with the 3-D case having a larger volume. The mean fluid residence times for both cases are related to Re by an inverse power law relationship, with the 3-D dune having smaller residence times at moderate to high Re. The effects of increasing flux on residence time in 3-D dunes are partly modulated by a slightly increasing hyporheic volume. Our results suggest that a 2-D idealization is a reasonable approximation for the more complex 3-D situation if local details are unimportant but that development of predictive models for mean fluxes and residence times, which are critical for biogeochemical processes, based on 2-D models may be insufficient.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/18613199','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/18613199"><span id="translatedtitle">Photo-<span class="hlt">induced</span> hydrogen <span class="hlt">exchange</span> reaction between methanol and glyoxal: formation of hydroxyketene.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mielke, Zofia; Mucha, Małgorzata; Bil, Andrzej; Golec, Barbara; Coussan, Stephane; Roubin, Pascale</p> <p>2008-08-25</p> <p>We study the structure and photochemistry of the glyoxal-methanol system (G-MeOH) by means of FTIR matrix isolation spectroscopy and ab initio calculations. The FTIR spectra show that the non-hydrogen-bonded complex, G-MeOH-1, is present in an inert environment of solid argon. MP2/aug-cc-pVDZ calculations indicate that G-MeOH-1 is the most stable complex among the five optimized structures. The interaction energy partitioned according to the symmetry-adapted perturbation theory (SAPT) scheme demonstrates that the dispersion energy gives a larger contribution to the stabilization of a non-hydrogen-bonded G-MeOH-1 complex than compared to the hydrogen-bonded ones. The irradiation of G-MeOH-1 with the filtered output of a mercury lamp (lambda>370 nm) leads to its photo-conversion into the hydroxyketene-methanol complex HK-MeOH-1. The identity of HK-MeOH-1 is confirmed by both FTIR spectroscopy and MP2/aug-cc-pVDZ calculations. An experiment with deuterated methanol (CH(3)OD) evidences that hydroxyketene is formed in a photo-<span class="hlt">induced</span> hydrogen <span class="hlt">exchange</span> reaction between glyoxal and methanol. The pathway for the photo-conversion of G-MeOH-1 to HK-MeOH-1 is studied by a coupled-cluster method [CR-CC(2,3)]. The calculations confirm our experimental findings that the reaction proceeds via hydrogen atom <span class="hlt">exchange</span> between the OH group of methanol and CH group of glyoxal. PMID:18613199</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3730250','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3730250"><span id="translatedtitle">SA1 binds directly to DNA through its unique AT-hook to promote sister <span class="hlt">chromatid</span> cohesion at telomeres</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bisht, Kamlesh K.; Daniloski, Zharko; Smith, Susan</p> <p>2013-01-01</p> <p>Summary Sister <span class="hlt">chromatid</span> cohesion relies on cohesin, a complex comprising a tri-partite ring and a peripheral subunit Scc3, which is found as two related isoforms SA1 and SA2 in vertebrates. There is a division of labor between the vertebrate cohesin complexes; SA1-cohesin is required at telomeres and SA2-cohesin at centromeres. Depletion of SA1 has dramatic consequences for telomere function and genome integrity, but the mechanism by which SA1-cohesin mediates cohesion at telomeres is not well understood. Here we dissect the individual contribution of SA1 and the ring subunits to telomere cohesion and show that telomeres rely heavily on SA1 and to a lesser extent on the ring for cohesion. Using chromatin immunoprecipitation we show that SA1 is highly enriched at telomeres, is decreased at mitosis when cohesion is resolved, and is increased when cohesion persists. Overexpression of SA1 alone was sufficient to <span class="hlt">induce</span> cohesion at telomeres, independent of the cohesin ring and dependent on its unique (not found in SA2) N-terminal domain, which we show binds to telomeric DNA through an AT-hook motif. We suggest that a specialized cohesion mechanism may be required to accommodate the high level of DNA replication-associated repair at telomeres. PMID:23729739</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23134723','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23134723"><span id="translatedtitle">Legacy of human-<span class="hlt">induced</span> C erosion and burial on soil-atmosphere C <span class="hlt">exchange</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Van Oost, Kristof; Verstraeten, Gert; Doetterl, Sebastian; Notebaert, Bastiaan; Wiaux, François; Broothaerts, Nils; Six, Johan</p> <p>2012-11-20</p> <p>Carbon <span class="hlt">exchange</span> associated with accelerated erosion following land cover change is an important component of the global C cycle. In current assessments, however, this component is not accounted for. Here, we integrate the effects of accelerated C erosion across point, hillslope, and catchment scale for the 780-km(2) Dijle River catchment over the period 4000 B.C. to A.D. 2000 to demonstrate that accelerated erosion results in a net C sink. We found this long-term C sink to be equivalent to 43% of the eroded C and to have offset 39% (17-66%) of the C emissions due to anthropogenic land cover change since the advent of agriculture. Nevertheless, the erosion-<span class="hlt">induced</span> C sink strength is limited by a significant loss of buried C in terrestrial depositional stores, which lagged the burial. The time lag between burial and subsequent loss at this study site implies that the C buried in eroded terrestrial deposits during the agricultural expansion of the last 150 y cannot be assumed to be inert to further destabilization, and indeed might become a significant C source. Our analysis exemplifies that accounting for the non-steady-state C dynamics in geomorphic active systems is pertinent to understanding both past and future anthropogenic global change. PMID:23134723</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1637748','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1637748"><span id="translatedtitle">Studies of negative ions by collision-<span class="hlt">induced</span> decomposition and hydrogen-deuterium <span class="hlt">exchange</span> techniques.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hunt, D F; Sethi, S K; Shabanowitz, J</p> <p>1980-01-01</p> <p>Development of two new techniques for studying the gas phase chemistry of negative ions is reported. Collision <span class="hlt">induced</span> dissociation (CID) of (M-1)- ions has been accomplished in a newly constructed triple stage quadrupole mass spectrometer. This instrument was assembled by adding two additional Finnigan quadrupole mass filters to a Finnigan Model 3200 CI mass spectrometer. Generation of (M-1)- ions is accomplished by allowing OH- and sample to react under CI conditions in the ion source. The first quadrupole mass filter, Q1, is then employed to selectively pass the (M-1)- ion into a second quadrupole filter containing argon or neon at 10(-3) torr. On collision with the inert gas the (M-1)- ions dissociate into fragments which are then mass analyzed in the third quadrupole filter, CID spectra of (M-1)- ions from twelve carbonyl compounds are presented in this paper. Ion molecule isotope <span class="hlt">exchange</span> reactions in the CI ion source can be used to count the number of hydrogen atoms in many different chemical environments. Collisions between sample (M-1)- ions and deuterium-labeled reagent gases (ND3, D2O, EtOD) facilitate incorporation of deuterium into the negative ion if the basicities of the sample and reagent anions are similar. Thus it is possible to selectively incorporate deuterium into many organic samples by controlling the exothermicity of the acid base, ion-molecule chemistry. PMID:7428745</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040088798&hterms=deuterium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Ddeuterium','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040088798&hterms=deuterium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Ddeuterium"><span id="translatedtitle">Deuterium enrichment of polycyclic aromatic hydrocarbons by photochemically <span class="hlt">induced</span> <span class="hlt">exchange</span> with deuterium-rich cosmic ices</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sandford, S. A.; Bernstein, M. P.; Allamandola, L. J.; Gillette, J. S.; Zare, R. N.</p> <p>2000-01-01</p> <p>The polycyclic aromatic hydrocarbon (PAH) coronene (C24H12) frozen in D2O ice in a ratio of less than 1 part in 500 rapidly <span class="hlt">exchanges</span> its hydrogen atoms with the deuterium in the ice at interstellar temperatures and pressures when exposed to ultraviolet radiation. <span class="hlt">Exchange</span> occurs via three different chemical processes: D atom addition, D atom <span class="hlt">exchange</span> at oxidized edge sites, and D atom <span class="hlt">exchange</span> at aromatic edge sites. Observed <span class="hlt">exchange</span> rates for coronene (C24H12)-D2O and d12-coronene (C24D12)-H2O isotopic substitution experiments show that PAHs in interstellar ices could easily attain the D/H levels observed in meteorites. These results may have important consequences for the abundance of deuterium observed in aromatic materials in the interstellar medium and in meteorites. These <span class="hlt">exchange</span> mechanisms produce deuteration in characteristic molecular locations on the PAHs that may distinguish them from previously postulated processes for D enrichment of PAHs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMNH13B1151A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMNH13B1151A"><span id="translatedtitle">Climate-<span class="hlt">induced</span> tree mortality: earth system consequences for carbon, energy, and water <span class="hlt">exchanges</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Adams, H. D.; Macalady, A.; Breshears, D. D.; Allen, C. D.; Luce, C.; Royer, P. D.; Huxman, T. E.</p> <p>2010-12-01</p> <p> subsurface flow, runoff, groundwater recharge, and streamflow. Under some circumstances there may also be increased flood risks. We hypothesized thresholds of mean annual precipitation and canopy cover reduction identified from the forest harvesting literature as minima that must be exceeded for die-off to noticeably affect hydrologic processes. We note exceptions to these thresholds when snowmelt dominates the watershed hydrology and when mortality affects a single species with a unique hydrologic role. Management options for mitigating die-off effects on ecosystem and earth system processes and implementing post-die-off restoration will likely be limited and costly, requiring ecological and societal adaptation in many areas. As such, climate-<span class="hlt">induced</span> tree mortality poses a significant risk to the current earth system function through altered <span class="hlt">exchanges</span> of carbon, energy, and water between the land surface and atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/14598338','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/14598338"><span id="translatedtitle">Chromosome instability <span class="hlt">induced</span> in vitro with mitomycin C in five Seckel syndrome patients.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bobabilla-Morales, Lucina; Corona-Rivera, Alfredo; Corona-Rivera, J Román; Buenrostro, C; García-Cobián, Teresa A; Corona-Rivera, Enrique; Cantú-Garza, José María; García-Cruz, Diana</p> <p>2003-12-01</p> <p>Seckel syndrome (SS) is an autosomal recessive entity characterized by proportionate pre- and post-natal growth retardation, microcephaly, typical facial appearance with beak-like protrusion, and severe mental retardation. A heterogeneous basis for SS was proposed since around 25% of SS patients have hematological anomalies, suggesting a subgroup of SS with chromosome instability and hematological disorders. Chromosome instability <span class="hlt">induced</span> by mitomycin C (MMC) has been observed in previous reports. The purpose of this study is to report cytogenetic features in five patients with SS. The patients had low birth weight (mean 1,870 g), short stature (SD = 6.36), microcephaly (OFC, SD = 8.1), typical facial appearance, and multiple articular dislocations. None of them had anemia at the time of examination. In all cases their parents were healthy and non-consanguineous. Lymphocytes of SS patients and a control group (n = 9) matched by age and sex were cultured with and without MMC, and harvested at 72 and 96 hr. Chromosomal aberrations (<span class="hlt">chromatid</span> and chromosomal gaps and breaks, deletions, fragments, and <span class="hlt">exchanges</span>) were scored in 100 metaphases per culture. A statistical increase of chromosomal aberrations was observed in 96 hr MMC cultures in all patients (40.2% vs. 2.8%). Sister <span class="hlt">chromatid</span> <span class="hlt">exchanges</span> were also performed with no differences between groups. Clinical and cytogenetic findings support the idea that SS may correspond to a chromosome instability syndrome. PMID:14598338</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3424243','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3424243"><span id="translatedtitle">LAB-1 Targets PP1 and Restricts Aurora B Kinase upon Entrance into Meiosis to Promote Sister <span class="hlt">Chromatid</span> Cohesion</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Tzur, Yonatan B.; Egydio de Carvalho, Carlos; Nadarajan, Saravanapriah; Van Bostelen, Ivo; Gu, Yanjie; Chu, Diana S.; Cheeseman, Iain M.; Colaiácovo, Monica P.</p> <p>2012-01-01</p> <p>Successful execution of the meiotic program depends on the timely establishment and removal of sister <span class="hlt">chromatid</span> cohesion. LAB-1 has been proposed to act in the latter by preventing the premature removal of the meiosis-specific cohesin REC-8 at metaphase I in C. elegans, yet the mechanism and scope of LAB-1 function remained unknown. Here we identify an unexpected earlier role for LAB-1 in promoting the establishment of sister <span class="hlt">chromatid</span> cohesion in prophase I. LAB-1 and REC-8 are both required for the chromosomal association of the cohesin complex subunit SMC-3. Depletion of lab-1 results in partial loss of sister <span class="hlt">chromatid</span> cohesion in rec-8 and coh-4 coh-3 mutants and further enhanced <span class="hlt">chromatid</span> dissociation in worms where all three kleisins are mutated. Moreover, lab-1 depletion results in increased Aurora B kinase (AIR-2) signals in early prophase I nuclei, coupled with a parallel decrease in signals for the PP1 homolog, GSP-2. Finally, LAB-1 directly interacts with GSP-1 and GSP-2. We propose that LAB-1 targets the PP1 homologs to the chromatin at the onset of meiosis I, thereby antagonizing AIR-2 and cooperating with the cohesin complex to promote sister <span class="hlt">chromatid</span> association and normal progression of the meiotic program. PMID:22927794</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040088722&hterms=dna+metabolism&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Ddna%2Bmetabolism','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040088722&hterms=dna+metabolism&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Ddna%2Bmetabolism"><span id="translatedtitle">Probabilities of radiation-<span class="hlt">induced</span> inter- and intrachromosomal <span class="hlt">exchanges</span> and their dependence on the DNA content of the chromosome</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wu, H.; Yang, T. C. (Principal Investigator)</p> <p>2001-01-01</p> <p>A biophysical model has been developed that is based on the assumptions that an interphase chromosome occupies a spherical territory and that chromosome <span class="hlt">exchanges</span> are formed by the misrejoining of two DNA double-strand breaks <span class="hlt">induced</span> within a defined interaction distance. The model is used to explain the relative frequencies of inter- and intrachromosomal <span class="hlt">exchanges</span> and the relationship between radiation-<span class="hlt">induced</span> aberrations in individual chromosomes and the DNA content of the chromosome. Although this simple model predicts a higher ratio of inter- to intrachromosomal <span class="hlt">exchanges</span> for low-LET radiation than for high-LET radiation, as has been suggested by others, we argue that the comparison of the prediction of the model with experimental results is not straightforward. With the model, we also show that the probability of the formation of interchromosomal <span class="hlt">exchanges</span> is proportional to the "surface area" of the chromosome domain plus a correction term. The correction term is small if the interaction distance is less than 1 microm for both low- and high-LET radiations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1484498','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1484498"><span id="translatedtitle">Metazoan Scc4 Homologs Link Sister <span class="hlt">Chromatid</span> Cohesion to Cell and Axon Migration Guidance</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Seitan, Vlad C; Banks, Peter; Laval, Steve; Majid, Nazia A; Dorsett, Dale; Rana, Amer; Smith, Jim; Bateman, Alex; Krpic, Sanja; Hostert, Arnd; Rollins, Robert A; Erdjument-Bromage, Hediye; Tempst, Paul; Benard, Claire Y; Hekimi, Siegfried; Newbury, Sarah F</p> <p>2006-01-01</p> <p>Saccharomyces cerevisiae Scc2 binds Scc4 to form an essential complex that loads cohesin onto chromosomes. The prevalence of Scc2 orthologs in eukaryotes emphasizes a conserved role in regulating sister <span class="hlt">chromatid</span> cohesion, but homologs of Scc4 have not hitherto been identified outside certain fungi. Some metazoan orthologs of Scc2 were initially identified as developmental gene regulators, such as Drosophila Nipped-B, a regulator of cut and Ultrabithorax, and delangin, a protein mutant in Cornelia de Lange syndrome. We show that delangin and Nipped-B bind previously unstudied human and fly orthologs of Caenorhabditis elegans MAU-2, a non-axis-specific guidance factor for migrating cells and axons. PSI-BLAST shows that Scc4 is evolutionarily related to metazoan MAU-2 sequences, with the greatest homology evident in a short N-terminal domain, and protein–protein interaction studies map the site of interaction between delangin and human MAU-2 to the N-terminal regions of both proteins. Short interfering RNA knockdown of human MAU-2 in HeLa cells resulted in precocious sister <span class="hlt">chromatid</span> separation and in impaired loading of cohesin onto chromatin, indicating that it is functionally related to Scc4, and RNAi analyses show that MAU-2 regulates chromosome segregation in C. elegans embryos. Using antisense morpholino oligonucleotides to knock down Xenopus tropicalis delangin or MAU-2 in early embryos produced similar patterns of retarded growth and developmental defects. Our data show that sister <span class="hlt">chromatid</span> cohesion in metazoans involves the formation of a complex similar to the Scc2-Scc4 interaction in the budding yeast. The very high degree of sequence conservation between Scc4 homologs in complex metazoans is consistent with increased selection pressure to conserve additional essential functions, such as regulation of cell and axon migration during development. PMID:16802858</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/16802858','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/16802858"><span id="translatedtitle">Metazoan Scc4 homologs link sister <span class="hlt">chromatid</span> cohesion to cell and axon migration guidance.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Seitan, Vlad C; Banks, Peter; Laval, Steve; Majid, Nazia A; Dorsett, Dale; Rana, Amer; Smith, Jim; Bateman, Alex; Krpic, Sanja; Hostert, Arnd; Rollins, Robert A; Erdjument-Bromage, Hediye; Tempst, Paul; Benard, Claire Y; Hekimi, Siegfried; Newbury, Sarah F; Strachan, Tom</p> <p>2006-07-01</p> <p>Saccharomyces cerevisiae Scc2 binds Scc4 to form an essential complex that loads cohesin onto chromosomes. The prevalence of Scc2 orthologs in eukaryotes emphasizes a conserved role in regulating sister <span class="hlt">chromatid</span> cohesion, but homologs of Scc4 have not hitherto been identified outside certain fungi. Some metazoan orthologs of Scc2 were initially identified as developmental gene regulators, such as Drosophila Nipped-B, a regulator of cut and Ultrabithorax, and delangin, a protein mutant in Cornelia de Lange syndrome. We show that delangin and Nipped-B bind previously unstudied human and fly orthologs of Caenorhabditis elegans MAU-2, a non-axis-specific guidance factor for migrating cells and axons. PSI-BLAST shows that Scc4 is evolutionarily related to metazoan MAU-2 sequences, with the greatest homology evident in a short N-terminal domain, and protein-protein interaction studies map the site of interaction between delangin and human MAU-2 to the N-terminal regions of both proteins. Short interfering RNA knockdown of human MAU-2 in HeLa cells resulted in precocious sister <span class="hlt">chromatid</span> separation and in impaired loading of cohesin onto chromatin, indicating that it is functionally related to Scc4, and RNAi analyses show that MAU-2 regulates chromosome segregation in C. elegans embryos. Using antisense morpholino oligonucleotides to knock down Xenopus tropicalis delangin or MAU-2 in early embryos produced similar patterns of retarded growth and developmental defects. Our data show that sister <span class="hlt">chromatid</span> cohesion in metazoans involves the formation of a complex similar to the Scc2-Scc4 interaction in the budding yeast. The very high degree of sequence conservation between Scc4 homologs in complex metazoans is consistent with increased selection pressure to conserve additional essential functions, such as regulation of cell and axon migration during development. PMID:16802858</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26697498','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26697498"><span id="translatedtitle">Inhibition of NA(+)/H(+) <span class="hlt">Exchanger</span> 1 Attenuates Renal Dysfunction <span class="hlt">Induced</span> by Advanced Glycation End Products in Rats.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Peng; Chen, Geng-Rong; Wang, Fu; Xu, Ping; Liu, Li-Ying; Yin, Ya-Ling; Wang, Shuang-Xi</p> <p>2016-01-01</p> <p>It has been recognized that sodium hydrogen <span class="hlt">exchanger</span> 1 (NHE1) is involved in the development of diabetic nephropathy. The role of NHE1 in kidney dysfunction <span class="hlt">induced</span> by advanced glycation end products (AGEs) remains unknown. Renal damage was <span class="hlt">induced</span> by AGEs via tail vein injections in rats. Function and morphology of kidney were determined. Compared to vehicle- or BSA-treated rats, AGEs caused abnormalities of kidney structures and functions in rats, accompanied with higher MDA level and lower GSH content. Gene expressions of NHE1 gene and TGF-β1 in the renal cortex and urine were also increased in AGEs-injected rats. Importantly, all these detrimental effects <span class="hlt">induced</span> by AGEs were reversed by inhibition of NHE1 or suppression of oxidative stress. These pieces of data demonstrated that AGEs may activate NHE1 to <span class="hlt">induce</span> renal damage, which is related to TGF-β1. PMID:26697498</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4838874','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4838874"><span id="translatedtitle">New mechanism of kinetic <span class="hlt">exchange</span> interaction <span class="hlt">induced</span> by strong magnetic anisotropy</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Iwahara, Naoya; Chibotaru, Liviu F.</p> <p>2016-01-01</p> <p>It is well known that the kinetic <span class="hlt">exchange</span> interaction between single-occupied magnetic orbitals (s-s) is always antiferromagnetic, while between single- and double-occupied orbitals (s-d) is always ferromagnetic and much weaker. Here we show that the <span class="hlt">exchange</span> interaction between strongly anisotropic doublets of lanthanides, actinides and transition metal ions with unquenched orbital momentum contains a new s-d kinetic contribution equal in strength with the s-s one. In non-collinear magnetic systems, this s-d kinetic mechanism can cause an overall ferromagnetic <span class="hlt">exchange</span> interaction which can become very strong for transition metal ions. These findings are fully confirmed by DFT based analysis of <span class="hlt">exchange</span> interaction in several Ln3+ complexes. PMID:27098292</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27098292','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27098292"><span id="translatedtitle">New mechanism of kinetic <span class="hlt">exchange</span> interaction <span class="hlt">induced</span> by strong magnetic anisotropy.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Iwahara, Naoya; Chibotaru, Liviu F</p> <p>2016-01-01</p> <p>It is well known that the kinetic <span class="hlt">exchange</span> interaction between single-occupied magnetic orbitals (s-s) is always antiferromagnetic, while between single- and double-occupied orbitals (s-d) is always ferromagnetic and much weaker. Here we show that the <span class="hlt">exchange</span> interaction between strongly anisotropic doublets of lanthanides, actinides and transition metal ions with unquenched orbital momentum contains a new s-d kinetic contribution equal in strength with the s-s one. In non-collinear magnetic systems, this s-d kinetic mechanism can cause an overall ferromagnetic <span class="hlt">exchange</span> interaction which can become very strong for transition metal ions. These findings are fully confirmed by DFT based analysis of <span class="hlt">exchange</span> interaction in several Ln(3+) complexes. PMID:27098292</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25337657','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25337657"><span id="translatedtitle">Solid-solid phase transformations <span class="hlt">induced</span> through cation <span class="hlt">exchange</span> and strain in 2D heterostructured copper sulfide nanocrystals.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ha, Don-Hyung; Caldwell, Andrew H; Ward, Matthew J; Honrao, Shreyas; Mathew, Kiran; Hovden, Robert; Koker, Margaret K A; Muller, David A; Hennig, Richard G; Robinson, Richard D</p> <p>2014-12-10</p> <p>We demonstrate dual interface formation in nanocrystals (NCs) through cation <span class="hlt">exchange</span>, creating epitaxial heterostructures within spherical NCs. The thickness of the inner-disk layer can be tuned to form two-dimensional (2D), single atomic layers (<1 nm). During the cation <span class="hlt">exchange</span> reaction from copper sulfide to zinc sulfide (ZnS), we observe a solid-solid phase transformation of the copper sulfide phase in heterostructured NCs. As the cation <span class="hlt">exchange</span> reaction is initiated, Cu ions replaced by Zn ions at the interfaces are accommodated in intrinsic Cu vacancy sites present in the initial roxbyite (Cu1.81S) phase of copper sulfide, <span class="hlt">inducing</span> a full phase transition to djurleite (Cu1.94S)/low chalcocite (Cu2S), a more thermodynamically stable phase than roxbyite. As the reaction proceeds and reduces the size of the copper sulfide layer, the epitaxial strain at the interfaces between copper sulfide and ZnS increases and is maximized for a copper sulfide disk ∼ 5 nm thick. To minimize this strain energy, a second phase transformation occurs back to the roxbyite phase, which shares a similar sulfur sublattice to wurtzite ZnS. The observation of a solid-solid phase transformation in our unique heterostructured NCs provides a new pathway to control desired phases and an insight into the influence of cation <span class="hlt">exchange</span> on nanoscale phase transitions in heterostructured materials. PMID:25337657</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27389420','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27389420"><span id="translatedtitle">Water-<span class="hlt">Induced</span> Decoupling of Tracer and Electrochemical Oxygen <span class="hlt">Exchange</span> Kinetics on Mixed Conducting Electrodes.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nenning, Andreas; Navickas, Edvinas; Hutter, Herbert; Fleig, Jürgen</p> <p>2016-07-21</p> <p>Isotope <span class="hlt">exchange</span> depth profiling and electrochemical impedance spectroscopy are usually regarded as complementary tools for measuring the surface oxygen <span class="hlt">exchange</span> activity of mixed conducting oxides, for example used in solid oxide fuel cell (SOFC) electrodes. Only very few studies compared electrical (k(q)) and tracer (k*) <span class="hlt">exchange</span> coefficients of solid-gas interfaces measured under identical conditions. The 1:1 correlation between k(q) and k* often made is thus more an assumption than experimentally verified. In this study it is shown that the measured rates of electrical and tracer <span class="hlt">exchange</span> of oxygen may strongly differ. Simultaneous acquisition of k(q) and k* on La0.6Sr0.4FeO3-δ and SrTi0.3Fe0.7O3-δ thin film electrodes revealed that k* > 100 k(q) in humid oxidizing ((16)O2 + H2(18)O) and humid reducing (H2 + H2(18)O) atmospheres. These results are explained by fast water adsorption and dissociation on surface oxygen vacancies, forming two surface hydroxyl groups. Hence, interpreting experimentally determined k* values in terms of electrochemically relevant oxygen <span class="hlt">exchange</span> is not straightforward. PMID:27389420</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25946564','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25946564"><span id="translatedtitle">The SUMO deconjugating peptidase Smt4 contributes to the mechanism required for transition from sister <span class="hlt">chromatid</span> arm cohesion to sister <span class="hlt">chromatid</span> pericentromere separation.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Stephens, Andrew D; Snider, Chloe E; Bloom, Kerry</p> <p>2015-01-01</p> <p>The pericentromere chromatin protrudes orthogonally from the sister-sister chromosome arm axis. Pericentric protrusions are organized in a series of loops with the centromere at the apex, maximizing its ability to interact with stochastically growing and shortening kinetochore microtubules. Each pericentromere loop is ∼50 kb in size and is organized further into secondary loops that are displaced from the primary spindle axis. Cohesin and condensin are integral to mechanisms of loop formation and generating resistance to outward forces from kinesin motors and anti-parallel spindle microtubules. A major unanswered question is how the boundary between chromosome arms and the pericentromere is established and maintained. We used sister <span class="hlt">chromatid</span> separation and dynamics of LacO arrays distal to the pericentromere to address this issue. Perturbation of chromatin spring components results in 2 distinct phenotypes. In cohesin and condensin mutants sister pericentric LacO arrays separate a defined distance independent of spindle length. In the absence of Smt4, a peptidase that removes SUMO modifications from proteins, pericentric LacO arrays separate in proportion to spindle length increase. Deletion of Smt4, unlike depletion of cohesin and condensin, causes stretching of both proximal and distal pericentromere LacO arrays. The data suggest that the sumoylation state of chromatin topology adjusters, including cohesin, condensin, and topoisomerase II in the pericentromere, contribute to chromatin spring properties as well as the sister cohesion boundary. PMID:25946564</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PlST...13..604L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PlST...13..604L"><span id="translatedtitle">Plasma-<span class="hlt">induced</span> Styrene Grafting onto the Surface of Polytetrafluoroethylene Powder for Proton <span class="hlt">Exchange</span> Membrane Application</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lan, Yan; Cheng, Cheng; Zhang, Suzhen; Ni, Guohua; Chen, Longwei; Yang, Guangjie; Nagatsu, M.; Meng, Yuedong</p> <p>2011-10-01</p> <p>Low-temperature plasma treatment was adopted to graft styrene onto polytetrafluoroethylene (PTFE) powder, which is widely used in the fabrication of proton <span class="hlt">exchange</span> membrane (PEM). The grafted PTFE powder was sulfonated in chlorosulfonic acid and fabricated into a membrane, which was used as inexpensive PEM material for a proton <span class="hlt">exchange</span> membrane fuel cell (PEMFC). Fourier transform infrared spectroscopy attenuated total reflection spectroscopy (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS) analysis were used to characterize the structure of the sulfonated PTFE powder. The results showed that all the PTFE powders were successfully grafted by nitrogen plasma and then sulfonated under such experimental conditions. A scanning electron microscopy (SEM) image indicated that the fabricated membrane exhibits flat morphology and homogenous structure. The ion <span class="hlt">exchange</span> capacity (IEC) of this kind of PEM was also investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012CP....402..105A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012CP....402..105A"><span id="translatedtitle">Proton <span class="hlt">exchange</span> in acid-base complexes <span class="hlt">induced</span> by reaction coordinates with heavy atom motions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Alavi, Saman; Taghikhani, Mahdi</p> <p>2012-06-01</p> <p>We extend previous work on nitric acid-ammonia and nitric acid-alkylamine complexes to illustrate that proton <span class="hlt">exchange</span> reaction coordinates involve the rocking motion of the base moiety in many double hydrogen-bonded gas phase strong acid-strong base complexes. The complexes studied involve the biologically and atmospherically relevant glycine, formic, acetic, propionic, and sulfuric acids with ammonia/alkylamine bases. In these complexes, the magnitude of the imaginary frequencies associated with the proton <span class="hlt">exchange</span> transition states are <400 cm-1. This contrasts with widely studied proton <span class="hlt">exchange</span> reactions between symmetric carboxylic acid dimers or asymmetric DNA base pair and their analogs where the reaction coordinate is localized in proton motions and the magnitude of the imaginary frequencies for the transition states are >1100 cm-1. Calculations on complexes of these acids with water are performed for comparison. Variations of normal vibration modes along the reaction coordinate in the complexes are described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApPhL.108s2402L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApPhL.108s2402L"><span id="translatedtitle"><span class="hlt">Exchange</span> magnon <span class="hlt">induced</span> resistance asymmetry in permalloy spin-Hall oscillators</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Langenfeld, S.; Tshitoyan, V.; Fang, Z.; Wells, A.; Moore, T. A.; Ferguson, A. J.</p> <p>2016-05-01</p> <p>We investigate magnetization dynamics in a spin-Hall oscillator using a direct current measurement as well as conventional microwave spectrum analysis. When the current applies an anti-damping spin-transfer torque, we observe a change in resistance which we ascribe mainly to the excitation of incoherent <span class="hlt">exchange</span> magnons. A simple model is developed based on the reduction of the effective saturation magnetization, quantitatively explaining the data. The observed phenomena highlight the importance of <span class="hlt">exchange</span> magnons on the operation of spin-Hall oscillators.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApSS..367..418Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApSS..367..418Z"><span id="translatedtitle">Fast laser annealing <span class="hlt">induced</span> <span class="hlt">exchange</span> bias in poly-crystalline BiFeO3/Co bilayers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Y. Q.; Ruan, X. Z.; Liu, B.; Xu, Z. Y.; Xu, Q. Y.; Shen, J. D.; Li, Q.; Wang, J.; You, B.; Tu, H. Q.; Gao, Y.; Zhang, W.; Xu, Y. B.; Du, J.</p> <p>2016-03-01</p> <p>The conventional field cooling process for antiferromagnetic/ferromagnetic bilayer system might strongly damage the interface of BiFeO3 (BFO) with metallic ferromagnetic layer, leading to significant deterioration of <span class="hlt">exchange</span> bias (EB). In this paper, a field cooling process with fast laser annealing has been proposed and applied on polycrystalline-BFO/Co bilayers, which can effectively modify the EB. In those samples with obvious EB, it is found that the <span class="hlt">exchange</span> field (HE) increases abruptly when the laser fluence rises to a critical value, and decreases when the laser fluence is large enough. On the other hand, in those samples with negligible HE, EB could be easily <span class="hlt">induced</span> after field cooling with proper laser fluence. In addition, the sign of HE could also be changed, depending on the direction of the cooling field. In contrast, after field cooling by conventional heat treatment, EB could be neither <span class="hlt">induced</span> nor enhanced. The feasibility of fast laser annealing accompanied with field cooling to enhance or <span class="hlt">induce</span> EB in the BFO/Co bilayer can be understood by much less interfacial diffusion in comparison with conventional field cooling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/16719949','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/16719949"><span id="translatedtitle">Na+ /Ca2+ <span class="hlt">exchanger</span> contributes to asterosap-<span class="hlt">induced</span> elevation of intracellular Ca2+ concentration in starfish spermatozoa.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Islam, M Sadiqul; Kawase, Osamu; Hase, Sumitaka; Minakata, Hiroyuki; Hoshi, Motonori; Matsumoto, Midori</p> <p>2006-05-01</p> <p>Asterosap, a group of equally active isoforms of sperm-activating peptides from the egg jelly of the starfish Asterias amurensis, functions as a chemotactic factor for sperm. It transiently increases the intracellular cGMP level of sperm, which in turn <span class="hlt">induces</span> a transient elevation of intracellular Ca(2+) concentration ([Ca(2+)](i)). Using a fluorescent Ca(2+)-sensitive dye, Fluo-4 AM, we measured the changes in sperm [Ca(2+)](i) in response to asterosap. KB-R7943 (KB), a selective inhibitor of Na(+)/Ca(2+) <span class="hlt">exchanger</span> (NCX), significantly inhibited the asterosap-<span class="hlt">induced</span> transient elevation of [Ca(2+)](i), suggesting that asterosap influences [Ca(2+)](i) through activation of a K+-dependent NCX (NCKX). An NCKX activity of starfish sperm also shows K(+) dependency like other NCKXs. Therefore, we cloned an NCKX from the starfish testes and predicted that it codes for a 616 amino acid protein that is a member of the NCKX family. Pharmacological evidence suggests that this <span class="hlt">exchanger</span> participates in the asterosap-<span class="hlt">induced</span> Ca(2+) entry into sperm. PMID:16719949</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25378216','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25378216"><span id="translatedtitle">Oxygen-<span class="hlt">induced</span> plasticity in tracheal morphology and discontinuous gas <span class="hlt">exchange</span> cycles in cockroaches Nauphoeta cinerea.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bartrim, Hamish; Matthews, Philip G D; Lemon, Sussan; White, Craig R</p> <p>2014-12-01</p> <p>The function and mechanism underlying discontinuous gas <span class="hlt">exchange</span> in terrestrial arthropods continues to be debated. Three adaptive hypotheses have been proposed to explain the evolutionary origin or maintenance of discontinuous gas <span class="hlt">exchange</span> cycles (DGCs), which may have evolved to reduce respiratory water loss, facilitate gas <span class="hlt">exchange</span> in high CO2 and low O2 micro-environments, or to ameliorate potential damage as a result of oversupply of O2. None of these hypotheses have unequivocal support, and several non-adaptive hypotheses have also been proposed. In the present study, we reared cockroaches Nauphoeta cinerea in selected levels of O2 throughout development, and examined how this affected growth rate, tracheal morphology and patterns of gas <span class="hlt">exchange</span>. O2 level in the rearing environment caused significant changes in tracheal morphology and the exhibition of DGCs, but the direction of these effects was inconsistent with all three adaptive hypotheses: water loss was not associated with DGC length, cockroaches grew fastest in hyperoxia, and DGCs exhibited by cockroaches reared in normoxia were shorter than those exhibited by cockroaches reared in hypoxia or hyperoxia. PMID:25378216</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4467855','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4467855"><span id="translatedtitle">Phosphorylation of the <span class="hlt">exchange</span> factor DENND3 by ULK in response to starvation activates Rab12 and <span class="hlt">induces</span> autophagy</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Xu, Jie; Fotouhi, Maryam; McPherson, Peter S</p> <p>2015-01-01</p> <p>Unc-51-like kinases (ULKs) are the most upstream kinases in the initiation of autophagy, yet the molecular mechanisms underlying their function are poorly understood. We report a new role for ULK in the induction of autophagy. ULK-mediated phosphorylation of the guanine nucleotide <span class="hlt">exchange</span> factor DENND3 at serines 554 and 572 upregulates its GEF activity toward the small GTPase Rab12. Through binding to LC3 and associating with LC3-positive autophagosomes, active Rab12 facilitates autophagosome trafficking, thus establishing a crucial role for the ULK/DENND3/Rab12 axis in starvation-<span class="hlt">induced</span> autophagy. PMID:25925668</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21596540','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21596540"><span id="translatedtitle">Synthesis of N=127 isotones through (p,n) charge-<span class="hlt">exchange</span> reactions <span class="hlt">induced</span> by relativistic {sup 208}Pb projectiles</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Morales, A. I.; Benlliure, J.; Alvarez-Pol, H.; Casarejos, E.; Dragosavac, D.; Perez-Loureiro, D.; Verma, S.; Agramunt, J.; Molina, F.; Rubio, B.; Algora, A.; Alkhomashi, N.; Farrelly, G.; Gelletly, W.; Pietri, S.; Podolyak, Z.; Regan, P. H.; Steer, S. J.; Boutachkov, P.; Caceres, L. S.</p> <p>2011-07-15</p> <p>The production cross sections of four N=127 isotones ({sup 207}Hg, {sup 206}Au, {sup 205}Pt, and {sup 204}Ir) have been measured using (p,n) charge-<span class="hlt">exchange</span> reactions, <span class="hlt">induced</span> in collisions of a {sup 208}Pb primary beam at 1 A GeV with a Be target. These data allow one to investigate the use of a reaction mechanism to extend the limits of the chart of nuclides toward the important r-process nuclei in the region of the third peak of elemental abundance distribution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..1510348S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..1510348S"><span id="translatedtitle">Light-<span class="hlt">induced</span> diurnal pattern of methane <span class="hlt">exchange</span> in a boreal forest</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sundqvist, Elin; Crill, Patrick; Mölder, Meelis; Vestin, Patrik; Lindroth, Anders</p> <p>2013-04-01</p> <p>Boreal forests represents one third of the Earth's forested land surface area and is a net sink of methane and an important component of the atmospheric methane budget. Methane is oxidized in well-aerated forest soils whereas ponds and bog soils are sources of methane. Besides the microbial processes in the soil also forest vegetation might contribute to methane <span class="hlt">exchange</span>. Due to a recent finding of methane consumption by boreal plants that correlated with photosynthetic active radiation (PAR), we investigate the impact of PAR on soil methane <span class="hlt">exchange</span> at vegetated plots on the forest floor. The study site, Norunda in central Sweden, is a 120 years old boreal forest stand, dominated by Scots pine and Norway spruce. We used continuous chamber measurements in combination with a high precision laser gas analyzer (Los Gatos Research), to measure the methane <span class="hlt">exchange</span> at four different plots in July-November 2009, and April-June 2010. The ground vegetation consisted almost entirely of mosses and blueberry-shrubs. Two of the plots acted as stable sinks of methane whereas the other two plots shifted from sinks to sources during very wet periods. The preliminary results show a clear diurnal pattern of the methane <span class="hlt">exchange</span> during the growing season, which cannot be explained by temperature. The highest consumption occurs at high PAR levels. The amplitude of the diurnal methane <span class="hlt">exchange</span> during the growing season is in the order of 10 μmol m-2 h-1. This indicates that besides methane oxidation by methanotrophs in the soil there is an additional removal of methane at soil level by a process related to ground vegetation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AnGeo..21.1289F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AnGeo..21.1289F"><span id="translatedtitle">The charge-<span class="hlt">exchange</span> <span class="hlt">induced</span> coupling between plasma-gas counterflows in the heliosheath</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fahr, H. J.</p> <p>2003-06-01</p> <p>Many hydrodynamic models have been presented which give similar views of the interaction of the solar wind plasma bubble with the counterstreaming partially ionized interstellar medium. In the more recent of these models it is taken into account that the solar and interstellar hydrodynamic flows of neutral atoms and protons are coupled by mass-, momentum-, and energy-<span class="hlt">exchange</span> terms due to charge <span class="hlt">exchange</span> processes. We shall reinvestigate the theoretical basis of this coupling here by use of a simplified description of the heliospheric interface and describe the main physics of the H-atom penetration through the more or less standing well-known plasma wall ahead of the heliopause. Thereby we can show that the type of charge <span class="hlt">exchange</span> coupling terms used in up-to-now hydrodynamic treatments unavoidably leads to an O-type critical point at the sonic point of the H-atom flow, thus not allowing for a continuation of the integration of the hydrodynamic set of differential equations. The remedy for this problem is given by a more accurate formulation of the momentum <span class="hlt">exchange</span> term for quasi-and sub-sonic H-atom flows. With a refined momentum <span class="hlt">exchange</span> term derived from basic kinetic Boltzmann principles, we instead arrive at a characteristic equation with an X-type critical point, allowing for a continuous solution from supersonic to subsonic flow conditions. This necessitates that the often treated problem of the propagation of inter-stellar H-atoms through the heliosheath has to be solved using these newly derived, differently effective plasma - gas friction forces. Substantially different results are to be expected from this context for the filtration efficiency of the heliospheric interface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3872193','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3872193"><span id="translatedtitle">Chromosome Segregation in Budding Yeast: Sister <span class="hlt">Chromatid</span> Cohesion and Related Mechanisms</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2014-01-01</p> <p>Studies on budding yeast have exposed the highly conserved mechanisms by which duplicated chromosomes are evenly distributed to daughter cells at the metaphase–anaphase transition. The establishment of proteinaceous bridges between sister <span class="hlt">chromatids</span>, a function provided by a ring-shaped complex known as cohesin, is central to accurate segregation. It is the destruction of this cohesin that triggers the segregation of chromosomes following their proper attachment to microtubules. Since it is irreversible, this process must be tightly controlled and driven to completion. Furthermore, during meiosis, modifications must be put in place to allow the segregation of maternal and paternal chromosomes in the first division for gamete formation. Here, I review the pioneering work from budding yeast that has led to a molecular understanding of the establishment and destruction of cohesion. PMID:24395824</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/20991421','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20991421"><span id="translatedtitle">Elimination of radiation-<span class="hlt">induced</span> {gamma}-H2AX foci in mammalian nucleus can occur by histone <span class="hlt">exchange</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Svetlova, Maria; Solovjeva, Liudmila; Nishi, Kayoko; Nazarov, Igor; Siino, Joseph; Tomilin, Nikolai . E-mail: nvtom@mail.ru</p> <p>2007-06-29</p> <p>Double-strand breaks in mammalian DNA lead to rapid phosphorylation of C-terminal serines in histone H2AX ({gamma}-H2AX) and formation of large nuclear {gamma}-H2AX foci. After DNA repair these foci disappear, but molecular mechanism of elimination of {gamma}-H2AX foci remains unclear. H2AX protein can be phosphorylated and dephosphorylated in vitro in the absence of chromatin. Here, we compared global <span class="hlt">exchange</span> of GFP-H2AX with kinetics of formation and elimination of radiation-<span class="hlt">induced</span> {gamma}-H2AX foci. Maximal number of {gamma}-H2AX foci is observed one hour after irradiation, when {approx}20% of GFP-H2AX is <span class="hlt">exchanged</span> suggesting that formation of the foci mostly occurs by in situ H2AX phosphorylation. However, slow elimination of {gamma}-H2AX foci is weakly affected by an inhibitor of protein phosphatases calyculin A which is known as an agent suppressing dephosphorylation of {gamma}-H2AX. This indicates that elimination of {gamma}-H2AX foci may be independent of dephosphorylation of H2AX which can occur after its removal from the foci by <span class="hlt">exchange</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20100015501&hterms=human+genomics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dhuman%2Bgenomics','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20100015501&hterms=human+genomics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dhuman%2Bgenomics"><span id="translatedtitle">Distributions of Low- and High-LET Radiation-<span class="hlt">Induced</span> Breaks in Chromosomes are Associated with Inter- and Intrachromosome <span class="hlt">Exchanges</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hada, Megumi; Zhang, Ye; Feiveson, Alan; Cucinotta, Francis A.; Wu, Honglu</p> <p>2010-01-01</p> <p>To study the breakpoint along the length of the chromosome <span class="hlt">induced</span> by low- and high-LET radiations, we exposed human epithelial cells in vitro to Cs-137 rays at both low and high dose rates, secondary neutrons at a low dose rate, and 600 MeV/u Fe ions at a high dose rate. The location of the breaks was identified using the multicolor banding in situ hybridization (mBAND) that paints Chromosome 3 in 23 different colored bands. The breakpoint distributions were found to be similar between rays of low and high dose rates and between the two high-LET radiation types. Detailed analysis of the chromosome break ends involved in inter- and intrachromosome <span class="hlt">exchanges</span> revealed that only the break ends participating in interchromosome <span class="hlt">exchanges</span> contributed to the hot spots found for low-LET. For break ends participating in intrachromosome <span class="hlt">exchanges</span>, the distributions for all four radiation scenarios were similar with clusters of breaks found in three regions. Analysis of the locations of the two break ends in Chromosome 3 that joined to form an intrachromosome <span class="hlt">exchange</span> demonstrated that two breaks with a greater genomic separation may be more likely to rejoin than two closer breaks, indicating that chromatin folding can play an important role in the rejoining of chromosome breaks. Our study demonstrated that the gene-rich regions do not necessarily contain more breaks. The breakpoint distribution depends more on the likelihood that a break will join with another break in the same chromosome or in a different chromosome.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012cosp...39.2266Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012cosp...39.2266Z"><span id="translatedtitle">Correlation Between Interphase Chromatin Structure and - and High-Let Radiation-<span class="hlt">Induced</span> - and Intra-Chromosome <span class="hlt">Exchange</span> Hotspots</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Ye; Wu, Honglu; Mangala, Lingegowda; Asaithamby, Aroumougame; Chen, David</p> <p>2012-07-01</p> <p>CORRELATION BETWEEN INTERPHASE CHROMATIN STRUCTURE AND LOW- AND HIGH-LET RADIATION-<span class="hlt">INDUCED</span> INTER- AND INTRA-CHROMOSOME <span class="hlt">EXCHANGE</span> HOTSPOTS Ye Zhang1,2, Lingegowda S. Mangala1,3, Aroumougame Asaithamby4, David J. Chen4, and Honglu Wu1 1 NASA Johnson Space Center, Houston, Texas, USA 2 Wyle Integrated Science and Engineering Group, Houston, Texas, USA 3 University of Houston Clear Lake, Houston, Texas, USA 4 University of Texas, Southwestern Medical Center, Dallas, Texas, USA To investigate the relationship between chromosome aberrations <span class="hlt">induced</span> by low- and high-LET radiation and chromatin folding, we reconstructed the three dimensional structure of chromosome 3 and measured the physical distances between different regions of this chromosome. Previously, we investigated the location of breaks involved in inter- and intrachromosomal type <span class="hlt">exchange</span> events in chromosome 3 of human epithelial cells, using the multicolor banding in situ hybridization (mBAND) technique. After exposure to both low- and high-LET radiations in vitro, intra-chromosome <span class="hlt">exchanges</span> occurred preferentially between a break in the 3p21 and one in the 3q11 regions, and the breaks involved in inter-chromosome <span class="hlt">exchanges</span> occurred in two regions near the telomeres of the chromosome. In this study, human epithelial cells were fixed in G1 phase and interphase chromosomes hybridized with an mBAND probe for chromosome 3 were captured with a laser scanning confocal microscope. The 3-dimensional structure of interphase chromosome 3 with different colored regions was reconstructed, and the distance between different regions was measured. We show that, in most of the G1 cells, the regions containing 3p21 and 3q11 are colocalized in the center of the chromosome domain, whereas, the regions towards the telomeres of the chromosome are located in the peripherals of the chromosome domain. Our results demonstrate that the distribution of breaks involved in radiation-<span class="hlt">induced</span> inter and intra-chromosome aberrations depends</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25633096','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25633096"><span id="translatedtitle">NCX1 <span class="hlt">Exchanger</span> Cooperates with Calretinin to Confer Preconditioning-<span class="hlt">Induced</span> Tolerance Against Cerebral Ischemia in the Striatum.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Boscia, Francesca; Casamassa, Antonella; Secondo, Agnese; Esposito, Alba; Pannaccione, Anna; Sirabella, Rossana; Pignataro, Giuseppe; Cuomo, Ornella; Vinciguerra, Antonio; de Rosa, Valeria; Annunziato, Lucio</p> <p>2016-03-01</p> <p>Recently, the Na(+)/Ca(+2) <span class="hlt">exchanger</span> NCX1 and the calcium binding protein calretinin have emerged as new molecular effectors of delayed preconditioning in the brain. In the present study, we investigated whether NCX1 and calretinin cooperate within the preconditioned striatum to confer neurons greater resistance to degeneration. Confocal microscopy analysis revealed that NCX1 expression was upregulated in calretinin-positive interneurons in the rat striatum after tolerance induction. Consistently, coimmunoprecipitation assays performed on human SHSY-5Y cells, a neuronal cell line which constitutively expresses calretinin, revealed a binding between NCX1 and calretinin. Finally, silencing of calretinin expression, both in vitro and in vivo, significantly prevented preconditioning-<span class="hlt">induced</span> neuroprotection. Interestingly, our biochemical and functional studies showed that the selective silencing of calretinin in brain cells significantly prevented not only the preconditioning-<span class="hlt">induced</span> upregulation of NCX1 expression and activity but also the activation of the prosurvival protein kinase Akt, which is involved in calretinin and NCX1 protective actions. Collectively, our results indicate that the Na(+)/Ca(+2) <span class="hlt">exchanger</span> NCX1 and the calcium binding protein calretinin cooperate within the striatum to confer tolerance against cerebral ischemia. PMID:25633096</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.H31B0595C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.H31B0595C"><span id="translatedtitle">Analysis of three-dimensional versus two-dimensional bedform-<span class="hlt">induced</span> hyporheic <span class="hlt">exchange</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, X.; Cardenas, M. B.; Chen, L.</p> <p>2014-12-01</p> <p>The hyporheic zone is a critical ecotone for maintaining the health of river systems due to the <span class="hlt">exchange</span> of water and nutrients between streams and groundwater. Within riverbeds, hyporheic <span class="hlt">exchange</span> is generally forced by variation in riverbed topography such as due to bedforms. In the past, a vast majority of research on bedform-driven hyporheic flow has focused on two-dimensional (2D) scenarios, while little has been done on more realistic three-dimensional (3D) situations. We investigated hyporheic <span class="hlt">exchanged</span> using a sinuous-crested 3D dune which is superimposed with successive crest lines of 2D dunes, and compared it to a 2D dune with similar wavelength and height. These 2D and 3D dunes are depicted in detail in McLean (1997) and Maddux (2003), respectively. A series of modeling studies are conducted both in 2D and 3D with similar open channel Reynolds numbers (Re). Turbulent flow in the water column is simulated by solving the Reynolds-averaged Navier-Stokes equations with the k-ω turbulence closure model, and a Darcy flow model is applied for the underlying porous media. These two sets of equations are coupled via the pressure distribution on the sediment-water interface (SWI). Results show that the pressure gradient along the SWI is highly controlled by the spatial structure of bedforms, which consequently determines flow dynamics in the porous media. Hyporheic flux is a function of Re for both 2D and 3D via a power-law trend; however, the hyporheic flux in the 3D dunes is generally higher and much more sensitive to Re. The depth and volume of the interfacial <span class="hlt">exchange</span> zone of the 3D-bedform driven flow are only slightly different from the 2D situation, showing that the dimensionality of bedform has less impact on the <span class="hlt">exchanged</span> zone. The mean fluid residence times for both 3D/2D dunes are related to Re by an inverse-power law relationship, they are different at low Re and become similar at higher Re. A 2D idealization seems a reasonable approximation for the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6709721','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6709721"><span id="translatedtitle">Implications of S-phase <span class="hlt">exchanges</span> for the mechanisms of radiosensitivity in trisomy 21</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Athanasiou, K.; Bartsocas, C.S.</p> <p>1982-06-01</p> <p>Human lymphocytes obtained from four patients with Down syndrome and from two normal individuals were irradiated with X-rays during their S phase and examined for <span class="hlt">chromatid</span> type aberrations. It is suggested that the significantly increased frequency of asymmetrical <span class="hlt">chromatid</span> interchanges found in trisomic cells is related to an altered DNA repair system. This altered repair system is probably responsible for the increased frequency of chromosome aberrations that can be <span class="hlt">induced</span> in these cells by x-rays and the increased tendency for leukemia observed in Down syndrome as well.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2001AdSpR..27..383K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2001AdSpR..27..383K&link_type=ABSTRACT"><span id="translatedtitle">G2-chromosome aberrations <span class="hlt">induced</span> by high-LET radiations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kawata, T.; Durante, M.; Furusawa, Y.; George, K.; Ito, H.; Wu, H.; Cucinotta, F. A.</p> <p></p> <p>We report measurements of initial G2-<span class="hlt">chromatid</span> breaks in normal human fibroblasts exposed to various types of high-LET particles. Exponentially growing AG 1522 cells were exposed to γ-rays or heavy ions. Chromosomes were prematurely condensed by calyculin A. <span class="hlt">Chromatid</span>-type breaks and isochromatid-type breaks were scored separately. The dose response curves for the induction of total <span class="hlt">chromatid</span> breaks (<span class="hlt">chromatid</span>-type + isochromatid-type) and <span class="hlt">chromatid</span>-type breaks were linear for each type of radiation. However, dose response curves for the induction of isochromatid-type breaks were linear for high-LET radiations and linear-quadratic for γ-rays. Relative biological effectiveness (RBE), calculated from total breaks, showed a LET dependent tendency with a peak at 55 keV/μm silicon (2.7) or 80 keV/μm carbon (2.7) and then decreased with LET (1.5 at 440 keV/μm). RBE for <span class="hlt">chromatid</span>-type break peaked at 55 keV/μm (2.4) then decreased rapidly with LET. The RBE of 440 keV/μm iron particles was 0.7. The RBE calculated from induction of isochromatid-type breaks was much higher for high-LET radiations. It is concluded that the increased production of isochromatid-type breaks, <span class="hlt">induced</span> by the densely ionizing track structure, is a signature of high-LET radiation exposure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4267994','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4267994"><span id="translatedtitle">Involvement of the Sodium-Calcium <span class="hlt">exchanger</span> 3 (NCX3) in ziram-<span class="hlt">induced</span> calcium dysregulation and toxicity</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Jin, J.; Lao, A.J.; Katsura, M.; Caputo, A.; Schweizer, F. E.; Sokolow, S.</p> <p>2014-01-01</p> <p>Ziram is a dimethyldithiocarbamate fungicide which can cause intraneuronal calcium (Ca2+) dysregulation and subsequently neuronal death. The signaling mechanisms underlying ziram-<span class="hlt">induced</span> Ca2+ dyshomeostasis and neurotoxicity are not fully understood. NCX3 is the third isoform of the sodium-calcium <span class="hlt">exchanger</span> (NCX) family and plays an important role in regulating Ca2+ homeostasis in excitable cells. We previously generated a mouse model deficient for the sodium-calcium <span class="hlt">exchanger</span> 3 and showed that NCX3 is protective against ischemic damage. In the present study, we aim to examine whether NCX3 exerts a similar role against toxicological injury caused by the pesticide ziram. Our data show baby hamster kidney (BHK) cells stably transfected with NCX3 (BHK-NCX3) are more susceptible to ziram toxicity than cells transfected with the empty vector (BHK-WT). Increased toxicity in BHK-NCX3 was associated with a rapid rise in cytosolic Ca2+ concentration [Ca2+i] <span class="hlt">induced</span> by ziram. Profound mitochondrial dysfunction and ATP depletion were also observed in BHK-NCX3 cells following treatment with ziram. Lastly, primary dopaminergic neurons lacking NCX3 (NCX3−/−) were less sensitive to ziram neurotoxicity than wildtype control dopaminergic neurons. These results demonstrate that NCX3 genetic deletion protects against ziram-<span class="hlt">induced</span> neurotoxicity and suggest NCX3 and its downstream molecular pathways as key factors involved in ziram toxicity. Our study identifies new molecular events through which pesticides (e.g. ziram) can lead to pathological features of degenerative diseases such as Parkinson’s disease and indicates new targets to slow down neuronal degeneration. PMID:25284465</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995NIMPB..96..382C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995NIMPB..96..382C&link_type=ABSTRACT"><span id="translatedtitle">Irradiation-<span class="hlt">induced</span> Ag-colloid formation in ion-<span class="hlt">exchanged</span> soda-lime glass</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Caccavale, F.; De Marchi, G.; Gonella, F.; Mazzoldi, P.; Meneghini, C.; Quaranta, A.; Arnold, G. W.; Battaglin, G.; Mattei, G.</p> <p>1995-03-01</p> <p>Ion-<span class="hlt">exchanged</span> glass samples were obtained by immersing soda-lime slides in molten salt baths of molar concentration in the range 1-20% AgNO 3 in NaNO 3, at temperatures varying from 320 to 350°C, and processing times of the order of a few minutes. Irradiations of <span class="hlt">exchanged</span> samples were subsequently performed by using H +m, He +, N + ions at different energies in order to obtain comparable projected ranges. The fluence was varied between 5 × 10 15 and 2 × 10 17 ions/cm 2. Most of the samples were treated at current densities lower than 2 μA/cm 2, in order to avoid heating effects. Some samples were irradiated with 4 keV electrons, corresponding to a range of 250 nm. The formation of nanoclusters of radii in the range 1-10 nm has been observed after irradiation, depending on the treatment conditions. The precipitation process is governed by the electronic energy deposition of incident particles. The most desirable results are obtained for helium implants. The process was characterized by the use of Secondary Ion Mass Spectrometry (SIMS) and nuclear techniques (Rutherford Backscattering (RBS), Nuclear Reactions (NRA)), in order to determine concentration-depth profiles and by optical absorption and Transmission Electron Microscopy (TEM) measurements for the silver nanoclusters detection and size evaluation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26479775','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26479775"><span id="translatedtitle">Light-<span class="hlt">induced</span> cation <span class="hlt">exchange</span> for copper sulfide based CO2 reduction.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Manzi, Aurora; Simon, Thomas; Sonnleitner, Clemens; Döblinger, Markus; Wyrwich, Regina; Stern, Omar; Stolarczyk, Jacek K; Feldmann, Jochen</p> <p>2015-11-11</p> <p>Copper(I)-based catalysts, such as Cu2S, are considered to be very promising materials for photocatalytic CO2 reduction. A common synthesis route for Cu2S via cation <span class="hlt">exchange</span> from CdS nanocrystals requires Cu(I) precursors, organic solvents, and neutral atmosphere, but these conditions are not compatible with in situ applications in photocatalysis. Here we propose a novel cation <span class="hlt">exchange</span> reaction that takes advantage of the reducing potential of photoexcited electrons in the conduction band of CdS and proceeds with Cu(II) precursors in an aqueous environment and under aerobic conditions. We show that the synthesized Cu2S photocatalyst can be efficiently used for the reduction of CO2 to carbon monoxide and methane, achieving formation rates of 3.02 and 0.13 μmol h(-1) g(-1), respectively, and suppressing competing water reduction. The process opens new pathways for the preparation of new efficient photocatalysts from readily available nanostructured templates. PMID:26479775</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24844246','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24844246"><span id="translatedtitle">Pharmacological inhibition of cystine-glutamate <span class="hlt">exchange</span> <span class="hlt">induces</span> endoplasmic reticulum stress and ferroptosis.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dixon, Scott J; Patel, Darpan N; Welsch, Matthew; Skouta, Rachid; Lee, Eric D; Hayano, Miki; Thomas, Ajit G; Gleason, Caroline E; Tatonetti, Nicholas P; Slusher, Barbara S; Stockwell, Brent R</p> <p>2014-01-01</p> <p><span class="hlt">Exchange</span> of extracellular cystine for intracellular glutamate by the antiporter system xc (-) is implicated in numerous pathologies. Pharmacological agents that inhibit system xc (-) activity with high potency have long been sought, but have remained elusive. In this study, we report that the small molecule erastin is a potent, selective inhibitor of system xc (-). RNA sequencing revealed that inhibition of cystine-glutamate <span class="hlt">exchange</span> leads to activation of an ER stress response and upregulation of CHAC1, providing a pharmacodynamic marker for system xc (-) inhibition. We also found that the clinically approved anti-cancer drug sorafenib, but not other kinase inhibitors, inhibits system xc (-) function and can trigger ER stress and ferroptosis. In an analysis of hospital records and adverse event reports, we found that patients treated with sorafenib exhibited unique metabolic and phenotypic alterations compared to patients treated with other kinase-inhibiting drugs. Finally, using a genetic approach, we identified new genes dramatically upregulated in cells resistant to ferroptosis.DOI: http://dx.doi.org/10.7554/eLife.02523.001. PMID:24844246</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4054777','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4054777"><span id="translatedtitle">Pharmacological inhibition of cystine–glutamate <span class="hlt">exchange</span> <span class="hlt">induces</span> endoplasmic reticulum stress and ferroptosis</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dixon, Scott J; Patel, Darpan N; Welsch, Matthew; Skouta, Rachid; Lee, Eric D; Hayano, Miki; Thomas, Ajit G; Gleason, Caroline E; Tatonetti, Nicholas P; Slusher, Barbara S; Stockwell, Brent R</p> <p>2014-01-01</p> <p><span class="hlt">Exchange</span> of extracellular cystine for intracellular glutamate by the antiporter system xc− is implicated in numerous pathologies. Pharmacological agents that inhibit system xc− activity with high potency have long been sought, but have remained elusive. In this study, we report that the small molecule erastin is a potent, selective inhibitor of system xc−. RNA sequencing revealed that inhibition of cystine–glutamate <span class="hlt">exchange</span> leads to activation of an ER stress response and upregulation of CHAC1, providing a pharmacodynamic marker for system xc− inhibition. We also found that the clinically approved anti-cancer drug sorafenib, but not other kinase inhibitors, inhibits system xc− function and can trigger ER stress and ferroptosis. In an analysis of hospital records and adverse event reports, we found that patients treated with sorafenib exhibited unique metabolic and phenotypic alterations compared to patients treated with other kinase-inhibiting drugs. Finally, using a genetic approach, we identified new genes dramatically upregulated in cells resistant to ferroptosis. DOI: http://dx.doi.org/10.7554/eLife.02523.001 PMID:24844246</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2759111','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2759111"><span id="translatedtitle">Size-<span class="hlt">Induced</span> Enhancement of Chemical <span class="hlt">Exchange</span> Saturation Transfer (CEST) Contrast in Liposomes</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zhao, Jason M.; Har-el, Yah-el; McMahon, Michael T.; Zhou, Jinyuan; Sherry, A. Dean; Sgouros, George; Bulte, Jeff W. M.; van Zijl, Peter C. M.</p> <p>2009-01-01</p> <p>Liposome-based chemical <span class="hlt">exchange</span> saturation transfer (lipoCEST) agents have shown great sensitivity and potential for molecular magnetic resonance imaging (MRI). Here we demonstrate that the size of liposomes can be exploited to enhance the lipoCEST contrast. A concise analytical model is developed to describe the contrast dependence on size for an ensemble of liposomes. The model attributes the increased lipoCEST contrast in smaller liposomes to their larger surface-to-volume ratio, causing an increased membrane water <span class="hlt">exchange</span> rate. Experimentally measured rates correlate with size, in agreement with the model. The water permeability of liposomal membrane is found to be 1.11 ± 0.14 μm/s for the specific lipid composition at 22 °C. Availability of the model allows rational design of the size of liposomes and quantification of their properties. These new theoretical and experimental tools are expected to benefit applications of liposomes to sensing the cellular environment, targeting and imaging biological processes, and optimizing drug delivery properties. PMID:18361490</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013Nanos...5.6589M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013Nanos...5.6589M"><span id="translatedtitle">Tunable properties <span class="hlt">induced</span> by ion <span class="hlt">exchange</span> in multilayer intertwined CuS microflowers with hierarchal structures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mi, Liwei; Wei, Wutao; Zheng, Zhi; Gao, Yang; Liu, Yang; Chen, Weihua; Guan, Xinxin</p> <p>2013-06-01</p> <p>Novel hierarchical wool-ball-like copper sulfide (CuS) microflowers with a three-dimensional (3D) porous framework were successfully synthesized by the direct reaction of copper with sulfur powder using a one-pot in situ growth method at low temperature (60 °C). The CuS microflowers covered firmly the surface of the 3D porous framework. The formation mechanism was examined in detail by adjusting the amount of hydrochloric acid and reaction time. Most importantly, the chemical composition of the CuS microflowers was altered by the Se <span class="hlt">exchange</span> without changing their morphology and structure. In this way, pure CuSe and Cu1.8Se crystalline materials were obtained on the surface of the porous microtube at different reaction times and the appropriate amount of Se powder. And interestingly, the core material remained as CuS. This behavior greatly affects the physical and chemical properties of the materials. The catalytic ability of the as-obtained CuSe@CuS and CuSe1.8@CuS composite materials to degrade methylene blue and rhodamine B is several times greater than that of the as-synthesized CuS microflowers.Novel hierarchical wool-ball-like copper sulfide (CuS) microflowers with a three-dimensional (3D) porous framework were successfully synthesized by the direct reaction of copper with sulfur powder using a one-pot in situ growth method at low temperature (60 °C). The CuS microflowers covered firmly the surface of the 3D porous framework. The formation mechanism was examined in detail by adjusting the amount of hydrochloric acid and reaction time. Most importantly, the chemical composition of the CuS microflowers was altered by the Se <span class="hlt">exchange</span> without changing their morphology and structure. In this way, pure CuSe and Cu1.8Se crystalline materials were obtained on the surface of the porous microtube at different reaction times and the appropriate amount of Se powder. And interestingly, the core material remained as CuS. This behavior greatly affects the physical and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26176908','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26176908"><span id="translatedtitle">Excess titanium dioxide nanoparticles on the cell surface <span class="hlt">induce</span> cytotoxicity by hindering ion <span class="hlt">exchange</span> and disrupting exocytosis processes.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Yanli; Yao, Chenjie; Li, Chenchen; Ding, Lin; Liu, Jian; Dong, Peng; Fang, Haiping; Lei, Zhendong; Shi, Guosheng; Wu, Minghong</p> <p>2015-08-14</p> <p>To date, considerable effort has been devoted to determine the potential toxicity of nanoparticles to cells and organisms. However, determining the mechanism of cytotoxicity <span class="hlt">induced</span> by different types of nanoparticles remains challenging. Herein, typically low toxicity nanomaterials were used as a model to investigate the mechanism of cytotoxicity <span class="hlt">induced</span> by low toxicity nanomaterials. We studied the effect of nano-TiO2, nano-Al2O3 and nano-SiO2 deposition films on the ion concentration on a cell-free system simulating the cell membrane. The results showed that the ion concentration of K(+), Ca(2+), Na(+), Mg(2+) and SO4(2-) decreased significantly following filtration of the prepared deposition films. More specifically, at a high nano-TiO2 concentration (200 mg L(-1)) and a long nano-TiO2 deposition time (48 h), the concentration of Na(+) decreased from 2958.01 to 2775.72, 2749.86, 2757.36, and 2719.82 mg L(-1), respectively, for the four types of nano-TiO2 studied. Likewise, the concentration of SO4(2-) decreased from 38.83 to 35.00, 35.80, 35.40, and 35.27 mg L(-1), respectively. The other two kinds of typical low toxicity nanomaterials (nano-Al2O3 and nano-SiO2) have a similar impact on the ion concentration change trend. Adsorption of ions on nanoparticles and the hydrated shell around the ions strongly hindered the ions through the nanoparticle films. The endocytosed nanoparticles could be released from the cells without <span class="hlt">inducing</span> cytotoxicity. Hindering the ion <span class="hlt">exchange</span> and disrupting the exocytosis process are the main factors that <span class="hlt">induce</span> cytotoxicity in the presence of excess nano-TiO2 on the cell surface. The current findings may offer a universal principle for understanding the mechanism of cytotoxicity <span class="hlt">induced</span> by low toxicity nanomaterials. PMID:26176908</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/20863868','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20863868"><span id="translatedtitle">Pion-<span class="hlt">induced</span> double-charge <span class="hlt">exchange</span> reactions in the {delta} resonance region</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Buss, O.; Alvarez-Ruso, L.; Larionov, A. B.; Mosel, U.</p> <p>2006-10-15</p> <p>We have applied the Giessen BUU (GiBUU) transport model to the description of the double-charge <span class="hlt">exchange</span> (DCX) reaction of pions with different nuclear targets at incident kinetic energies of 120-180 MeV. The DCX process is highly sensitive to details of the interactions of pions with the nuclear medium and, therefore, represents a major benchmark for any model of pion scattering off nuclei at low and intermediate energies. The impact of surface effects, such as the neutron skins of heavy nuclei, is investigated. The dependence of the total cross section on the nuclear mass number is also discussed. We achieve a good quantitative agreement with the extensive data set obtained at LAMPF. Furthermore, we compare the solutions of the transport equations obtained in the test-particle ansatz using two different schemes: the full and the parallel ensemble methods.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <center> <div class="footer-extlink text-muted"><small>Some links on this page may take you to non-federal websites. Their policies may differ from this site.</small> </div> </center> <div id="footer-wrapper"> <div class="footer-content"> <div id="footerOSTI" class=""> <div class="row"> <div class="col-md-4 text-center col-md-push-4 footer-content-center"><small><a href="http://www.science.gov/disclaimer.html">Privacy and Security</a></small> <div class="visible-sm visible-xs push_footer"></div> </div> <div class="col-md-4 text-center col-md-pull-4 footer-content-left"> <img src="http://www.osti.gov/images/DOE_SC31.png" alt="U.S. Department of Energy" usemap="#doe" height="31" width="177"><map style="display:none;" name="doe" id="doe"><area shape="rect" coords="1,3,107,30" href="http://www.energy.gov" alt="U.S. Deparment of Energy"><area shape="rect" coords="114,3,165,30" href="http://www.science.energy.gov" alt="Office of Science"></map> <a ref="http://www.osti.gov" style="margin-left: 15px;"><img src="http://www.osti.gov/images/footerimages/ostigov53.png" alt="Office of Scientific and Technical Information" height="31" width="53"></a> <div class="visible-sm visible-xs push_footer"></div> </div> <div class="col-md-4 text-center footer-content-right"> <a href="http://www.osti.gov/nle"><img src="http://www.osti.gov/images/footerimages/NLElogo31.png" alt="National Library of Energy" height="31" width="79"></a> <a href="http://www.science.gov"><img src="http://www.osti.gov/images/footerimages/scigov77.png" alt="science.gov" height="31" width="98"></a> <a href="http://worldwidescience.org"><img src="http://www.osti.gov/images/footerimages/wws82.png" alt="WorldWideScience.org" height="31" width="90"></a> </div> </div> </div> </div> </div> <p><br></p> </div><!-- container --> </body> </html>