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961.
962.
D D Miller D L Johnston D Dragotakes J B Newell T Aretz H L Kantor T J Brady R D Okada 《Magnetic resonance imaging》1989,7(1):79-88
To determine how administration of a hyperosmotic agent alters regional nuclear magnetic resonance (NMR) relaxation parameters and imaging characteristics in ischemic-reperfused myocardium, 7 dogs were infused with mannitol for 15 minutes before and after the release of a 3 hour left anterior descending coronary artery (LAD) occlusion. Nine control animals received normal saline during the 3 hour occlusion and 1 hour reperfusion periods. Normal posterior left ventricular (LV) wall and the ischemic anterior LV wall (risk area) myocardium was sampled for calculation of segmental microsphere myocardial blood flow, % tissue water content, NMR relaxation times (T1, T2) and myocyte ultrastructure using electron microscopy. Mean infarct T1 values were 14% greater than normal segments in saline-treated controls, but only 5% greater after mannitol. The difference in tissue water content between infarcted and normal segments was 4% in saline-treated (83 vs. 79%) compared to 2% in mannitol-treated dogs (79 vs. 77%). T1, T2 and % water content of control infarct segments were greater than treated infarcts (p less than 0.01). T1 and T2 rose as occlusion flow fell below 0.5 ml/min/g in control hearts but did not rise until flows were reduced to 0.1 ml/min/g in mannitol-treated hearts. Areas of increased signal in T1 and T2 NMR images correlated well with histochemical infarct volume (r = 0.98, SEE = 1.1 cc) in mannitol-treated dogs, but infarct borders were qualitatively less well-defined than in controls. We concluded that mannitol (1) diminishes tissue edema and reduces NMR relaxation parameters (T1, T2) in infarcted myocardium; and (2) attenuates the rise in T1 and T2 and ultrastructural myocyte injury in ischemic-reperfused myocardium. 相似文献
963.
964.
965.
966.
Reduction of alkylmercury(II) acetates with N-benzyl-1,4-dihydronicotinamide (BNAH) proceeds through electron-transfer chain-substitution mechanism. The rate constant of hydrogen transfer from BNAH to alkyl radical was estimated as in the order of 105 1/mol·sec. 相似文献
967.
968.
Michiharu Wada Hong-jie Xu Jin'ichi Tanaka Hirokane Kawakami Ichiro Katayma Kunihiko Okada Shunsuke Ohtani 《Hyperfine Interactions》1993,81(1-4):161-170
An on-line ion trap system is under construction at INS in order to study properties of the trapped unstable nuclei produced by a cyclotron beam. Among several subjects on the system, development of a direct trapping method for unstable nuclear ions from a recoil separator is taken to be of first priority. We have successfully developed a new ion cooling device for this purpose using an ion-guide followed by an RF multipole ion beam guide.On leave from the Institute of Atomic Energy, Academia Cinica, Shanghai, P.R. China 相似文献
969.
We study the phase structure in the minimal SU(5)-Coleman-Weinberg theory. We consider the implication of the results for cosmology and point out that the Higgs coupling constant must be fine-tuned in order to realize the new inflationary universe scenario. The effects of heavy fermions are also discussed. 相似文献
970.
A method for measuring three simensional position by using a multiplex hologram is proposed with some examples of measurements. 相似文献