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81.
Five new neoclerodane diterpenoids have been isolated from Scutellaria caerulea: (11S*)-6 alpha-acetoxy-7 beta,11-diisobutiryloxy-1 beta,8 beta-dihydroxy-4(18),13-neoclerodadien-15,16-olide (scuterulein A) (1); (13R*)-1 beta-6 alpha-7 beta-triacetoxy-11 beta-benzoyloxy-8 beta,13-epoxy-4(18)-neocleroden-15,16-olide (scuterulein B) (2); (11S*)-1 beta,6 alpha,11-triacetoxy-7 beta-isobutiryloxy-8 beta-hydroxy-4(18),13-neoclerodadien-15,16-olide (scuterulein C) (3); (11S*)-6 alpha,11-diacetoxy-7 beta-isobutiryloxy-1 beta,8 beta-dihydroxy-4(18),13-neoclerodadien-15,16-olide (deacetyl scuterulein C) (4), and (11E)-6 alpha-acetoxy-7 beta-isobutiryloxy-1 beta,8 beta-dihydroxy-4(18),11,13-neoclerodatrien-15,16-olide (scuterulein D) (5). Structures were established by spectroscopic and chemical methods. An X-ray analysis was carried out on scuterulein B (2). 相似文献
82.
The results using polytetrafluoroethylene (PTFE) and tanned human umbilical cord vein (HUV) grafts are discussed. These two grafts perform well for reconstructions above the knee and the results are similar to the autogenous saphenous vein (ASV) grafts in several series; however, in more distal reconstructions the PTFE and HUV are far inferior to ASV grafts. The factors responsible for graft failure including the events which take place at the blood interface are reviewed. New material surfaces under investigation such as degradable grafts, heparin-bonded surfaces, and endothelial-seeded fabrics are also addressed. 相似文献
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Cerebral blood flow relationships associated with a difficult tone recognition task in trained normal volunteers 总被引:2,自引:2,他引:0
Holcomb HH; Medoff DR; Caudill PJ; Zhao Z; Lahti AC; Dannals RF; Tamminga CA 《Cerebral cortex (New York, N.Y. : 1991)》1998,8(6):534-542
Tone recognition is partially subserved by neural activity in the right
frontal and primary auditory cortices. First we determined the brain areas
associated with tone perception and recognition. This study then examined
how regional cerebral blood flow (rCBF) in these and other brain regions
correlates with the behavioral characteristics of a difficult tone
recognition task. rCBF changes were assessed using H2(15)O positron
emission tomography. Subtraction procedures were used to localize
significant change regions and correlational analyses were applied to
determine how response times (RT) predicted rCBF patterns. Twelve trained
normal volunteers were studied in three conditions: REST, sensory motor
control (SMC) and decision (DEC). The SMC-REST contrast revealed bilateral
activation of primary auditory cortices, cerebellum and bilateral inferior
frontal gyri. DEC-SMC produced significant clusters in the right middle and
inferior frontal gyri, insula and claustrum; the anterior cingulate gyrus
and supplementary motor area; the left insula/claustrum; and the left
cerebellum. Correlational analyses, RT versus rCBF from DEC scans, showed a
positive correlation in right inferior and middle frontal cortex; rCBF in
bilateral auditory cortices and cerebellum exhibited significant negative
correlations with RT These changes suggest that neural activity in the
right frontal, superior temporal and cerebellar regions shifts back and
forth in magnitude depending on whether tone recognition RT is relatively
fast or slow, during a difficult, accurate assessment.
相似文献
85.
The clearance of vancomycin is significantly reduced in patients with acute, as well as, chronic renal failure. Although multiple-dosage regimen adjustment techniques have been proposed for these patients, there is little quantitative data to guide the individualization of vancomycin therapy in acute renal failure patients who are receiving continuous renal replacement therapy (CRRT). To determine appropriate vancomycin dosing strategies for patients receiving continuous venovenous hemofiltration (CVVH) and continuous venovenous hemodialysis (CVVHD), we performed controlled clearance studies in five stable hemodialysis patients with three hemofilters: an acrylonitrile copolymer 0.6 m2 (AN69), polymethylmethacrylate 2.1 m2 (PMMA), and polysulfone 0.65 m2 (PS). Patients received 500 mg of vancomycin intravenously at least 12 hours before the start of the clearance study. The concentration of vancomycin in multiple plasma and dialysate/ultrafiltrate samples was determined by EMIT (Syva, Palo Alto, CA). The diffusional clearance and sieving coefficient (SC) of vancomycin were compared by a mixed-model repeated-measures analysis of variance (ANOVA) with filter and blood (Q(B)), dialysate inflow (Q(DI)), or ultrafiltration rate (Q(UF)) as the main effects and patient as a random effect. Vancomycin was moderately protein bound in these patients; free fraction ranged from 49% to 83%. The SCs of the three filters were similar and significantly correlated with the free fraction of vancomycin (P = 0.01; r2 = 0.465). Significant linear relationships were observed between the diffusional clearance of vancomycin and Q(DI) for all three filters: AN69 (slope = 0.482; r2 = 0.880); PMMA (slope = 0.853; r2 = 0.966); and PS (slope = 0.658; r2 = 0.887). The slope of this relationship for the PMMA filter was significantly greater than that of the AN69 and PS filters. The clearance of vancomycin, urea, and creatinine, however, was essentially constant at all Q(B)s for all three filters. Thus, the clearance of vancomycin was not membrane dependent during CVVH. However, during CVVHD, membrane dependence of vancomycin clearance was noted at a Q(DI) greater than 16.7 mL/min; vancomycin clearance with PMMA at a Q(DI) of 25 mL/min was 66% and 43% greater than that with the AN69 and PS filters, respectively. CVVH (62% to 262%) and CVVHD (90% to 540%) can significantly augment the clearance of vancomycin in acute renal failure patients. Dosing strategies for individualization of vancomycin therapy in patients receiving CVVH and CVVHD are proposed. 相似文献
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88.
Masatoshi Kudo MD David R. Vera PhD Robert C. Stadalnik MD Carlos O. Esquivel MD PhD Walter L. Trudeau MD Katsuji Ikekubo MD Akio Todo MD 《Digestive diseases and sciences》1993,38(12):2183-2188
Technetium-99m-galactosyl-neoglycoalbumin (TcNGA) is a synthetic radiolabeled ligand specific for hepatic binding protein (HBP), a receptor that resides exclusively on hepatocytes.In vivo measurement of receptor concentration was obtained via kinetic analysis of liver and blood time-activity data obtained during the hepatic clearance of intravenously administered TcNGA. The purpose of this study was to assess receptor concentration as a measure of the functioning hepatocyte mass. Therefore, TcNGA and dualinjection indocyanine green maximal removal rate (ICG Rmax) studies were performed on nine patients with hepatic cirrhosis associated or not with hepatocellular carcinoma. Receptor concentration was compared with ICG Rmax, which is a validated method for the estimation of the functioning hepatocyte mass. The correlation coefficient was 0.76 (P=0.017). It is concluded that HBP concentration ([HPB]o) as measured by functional imaging is a measure of functioning hepatocyte mass. This implies that measurement of an individual's receptor concentration by using nuclear medicine techniques provides an objective index of hepatic functional mass and supports attempts to rigorously evaluate [HBP]o for its clinical efficacy. 相似文献
89.
Small pulmonary lesions detected at CT: clinical importance 总被引:27,自引:0,他引:27
90.