Methods to assess free radicals and oxidative stress in biological systems.     

G Rimbach  D H?hler  A Fischer  S Roy  F Virgili  J Pallauf  L Packer 《Archives of Animal Nutrition》1999,52(3):203-222

Oxidative stress results from a disruption of the prooxidant/antioxidant cellular balance and monitoring free radical status becomes an interesting challenge in animal and human nutrition. In the present work, merits and limitations of different analytical techniques (HPLC, GC-MS, fluorometric and colourometric assays, ELISA, gel electrophoresis) for the measurement of radical mediated alterations in the cellular integrity of lipids (malondialdehyde, hydrocarbon gases, F2-isoprostanes) proteins (protein carbonyls, 3-nitrotyrosine) and DNA (8-hydroxy-2'-deoxyguanosine) are discussed. Besides these indirect methods, owing to the fact that free radicals are paramagnetic, electron paramagnetic resonance spectroscopy combined with spin trapping has become a valuable tool to directly assess and to better understand the mechanisms of free radical reactions. With this approach a radical that is too short-lived to be detected, adds to a spin-trapping agent to form a relatively long-lived radical adduct. Information obtained from the hyperfine splitting of the spin-trapped adduct can provide identification and quantification of the originally generated free radicals.  相似文献   

Mass-independent oxygen isotope fractionation in atmospheric CO as a result of the reaction CO + OH     

T Rockmann  CAM Brenninkmeijer  G Saueressig  P Bergamaschi  JN Crowley  H Fischer  PJ Crutzen 《Science (New York, N.Y.)》1998,281(5376):544-546

Atmospheric carbon monoxide (CO) exhibits mass-independent fractionation in the oxygen isotopes. An 17O excess up to 7.5 per mil was observed in summer at high northern latitudes. The major source of this puzzling fractionation in this important trace gas is its dominant atmospheric removal reaction, CO + OH --> CO2 + H, in which the surviving CO gains excess 17O. The occurrence of mass-independent fractionation in the reaction of CO with OH raises fundamental questions about kinetic processes. At the same time the effect is a useful marker for the degree to which CO in the atmosphere has been reacting with OH.  相似文献   

Increasing ozone over the Atlantic Ocean     

Lelieveld J  van Aardenne J  Fischer H  de Reus M  Williams J  Winkler P 《Science (New York, N.Y.)》2004,304(5676):1483-1487

Ship-borne ozone (O3) measurements over the Atlantic Ocean during the period from 1977 to 2002 show that O3 trends in the northern mid-latitudes are small. In contrast, remarkably large O3 trends occur at low latitudes and in the Southern Hemisphere, where near-surface O3 has increased by up to a factor of 2. The likely cause is the substantial increase of anthropogenic emissions of nitrogen oxides (NOx) associated with energy use in Africa, which has added to NOx from biomass burning and natural sources.  相似文献   

Optic neuritis in dogs     

C A Fischer  G T Jones 《Journal of the American Veterinary Medical Association》1972,160(1):68-79

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Rumen fermentation characteristics, nitrogen balance and growth in lambs fed methane digester effluent     

F K Goedeken  J A Paterson  L L Koeln  J R Fischer  J E Williams 《Journal of animal science》1985,60(6):1472-1478

A laboratory silo trial, two lamb metabolism trials and a lamb growth trial were conducted to compare the nitrogen (N) value of swine methane digester effluent (MDE) to that of urea. Using laboratory silos (four/treatment), fermentation characteristics were measured for silages containing cracked corn, ground wheat straw and MDE added at levels of 0, 4, 8 or 12% of silage dry matter (DM). Lactic acid concentration increased linearly with up to 8% MDE addition, but then decreased (P less than .05; quadratic) with 12% MDE. Butyric acid was highest (P less than .05; linear) with 12% MDE, indicating an undesirable fermentation. In a metabolism study, DM, organic matter and N digestibilities and N balance were similar (P greater than .10) between urea and MDE, but DM digestibility was lower (P less than .05) for ensiled diets (52%) than diets fed fresh daily (59.4%). Mean ruminal volatile fatty acid, ruminal ammonia-N and plasma urea-N concentrations were similar (P greater than .10) between urea- and MDE-fed lambs. Plasma urea-N was higher (P less than .05) and ruminal isovaleric acid lower (P less than .05) in animals fed ensiled than fresh diets. In the second metabolism trial, digestibility of N was lowest (P less than .05) for MDE (51.2%) and highest for soybean meal (SBM; 71.8%), but N balance was similar among all diets.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

Kurzmitteilung Mechanische Reinigung von Pt-Elektroden     

G. Schaller  W. R. Fischer 《植物养料与土壤学杂志》1981,144(2):222-223

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Alkylation of guanine in mice in vivo by organophosphorus insecticides. I. Trichlorphone and butonate     

W. Dedek  Kh. Lohs  G.W. Fischer  R. Schmidt 《Pesticide biochemistry and physiology》1976,6(2):101-110

Following intraperitoneal administration to male mice of trichlorphone, 4 mg/animal = 160 mg/kg and butonate, 5 and 10 mg/animal = 200 and 400 mg/kg, labeled by ¹⁴C in the OCH₃-groups, nucleic acids taken from different organs and urine were analyzed for [7-¹⁴C]methylguanine. The limit of detection was 2 × 10^?8, calculated as ¹⁴C relative to the total dose. The maximum of ¹⁴C in 7-methylguanine was 2 × 10^?7 in lung, kidney, and testicles and 3 × 10^?6 in liver. The excretion rate of 7-MeG from nucleic acids is very rapid, a halflife of 2.0 hr was measured in liver from butonate and of < 24 hr was calculated in the whole body from trichlorphone, contrary to the excretion rate of 3.0–3.5 days following administration of strongly genotoxic agents. The relative amounts of [7-¹⁴C]methylguanine excreted in the urine were determined and compared with data for dichlorvos, dimethyl sulfate, and methyl methanesulfonate from the literature. Following intraperiotoneal administration, the methylating capability towards N-7 of guanine in nucleic acids is given by the ratio of about 100:10:25 for dichlorvos, butonate, and trichlorphone, respectively.  相似文献   

Bericht über das Symposium der EUCARPIA, Sektion Obstzüchtung in Angers/Frankreich vom 1. bis 5. September 2003     

Prof. Dr. M. Fischer 《Erwerbs-Obstbau》2004,46(2):59-62

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Innere und äußere Qualitätsparameter von Himbeerfrüchten     

Erika Krüger  Evelin Schöpplein  Sabine Rasim  Guiseppa Cocca  Heike Fischer 《Erwerbs-Obstbau》2004,46(6):133-140

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Zur Biologie und Bekämpfung des Pflaumenvicklers (Laspeyresia funebrana Tr.) in Norddeutschland     

Hermann Fischer 《Journal of pest science》1948,21(3):40-43

Ohne Zusammenfassung  相似文献