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991.
AD Anichkov AV Vodianov SV Mozhaev TN Trofimova VB Nizkovolos AV Obliapin IuZ Polonski? AL Spirin 《Canadian Metallurgical Quarterly》1998,(3):6-9; discussion 9-10
The paper summarizes experience with stereotactic operations by magnetic resonance imaging data by using a Russian OREOL stereotactic manipulator. It describes methods of preoperative preparation of patients by employing diagnostic magnetic resonance tomographs. A number of points of the procedure for identification and localization of deep target structures from magnetic resonance images in parkinsonism, temporal epilepsy and some mental disorders. 相似文献
992.
R Dhand VK Sharma AL Teng S Krishnasamy NJ Gross 《Canadian Metallurgical Quarterly》1998,244(3):712-719
Surfactant convertase is required for conversion of heavy density (H) natural surfactant to light density (L) subtype during cycling in vitro, a technique that reproduces surfactant metabolism. To study mechanisms of H to L conversion, we prepared liposomes of dipalmitoylphosphatidylcholine (DPPC) and phosphatidylglycerol (PG), or the phospholipids (PL) in combination with either surfactant protein A (SP-A), surfactant protein B (SP-B), or both SP-A and SP-B. Phospholipids alone showed time-dependent conversion from heavy to light subtype on cycling in the absence of convertase, which was decreased by adding SP-B, but not SP-A, to phospholipids (p < 0.01 for PL+SP-B, or PL+SP-A+SP-B vs. PL, or PL+SP-A). The ultrastructure, surface activity, buoyant density, and L subtype generation on cycling PL+SP-A+SP-B with partially purified convertase or with phospholipase D were similar to those of natural TM. In conclusion, a reconstituted surfactant mimics the behavior of natural surfactant on cycling, and reveals that interaction of SP-B with phospholipids decreases L subtype generation. In addition, esterase/ phospholipase D activity is required for conversion of heavy to light subtype on cycling. 相似文献
993.
The CRY1 blue light photoreceptor of Arabidopsis interacts with phytochrome A in vitro 总被引:1,自引:0,他引:1
Plants have at least two major photosensory receptors: phytochrome (absorbing primarily red/far-red light) and cryptochrome (absorbing blue/UV-A light); considerable physiological and genetic evidence suggests some form of communication or functional dependence between the receptors. Here, we demonstrate in vitro, using purified recombinant photoreceptors, that Arabidopsis CRY1 and CRY2 (cryptochrome) are substrates for phosphorylation by a phytochrome A-associated kinase activity. Several mutations within the CRY1 C terminus lead to reduced phosphorylation by phytochrome preparations in vitro. Yeast two-hybrid interaction studies using expressed C-terminal fragments of CRY1 and phytochrome A from Arabidopsis confirm a direct physical interaction between both photoreceptors. In vivo labeling studies and specific mutant alleles of CRY1, which interfere with the function of phytochrome, suggest the possible relevance of these findings in vivo. 相似文献
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995.
Agha Z. Khan Ali Sher Bhatti M. Zahid Raza Nisar Ahmad 《Petroleum Science and Technology》1995,13(8):973-990
The Makerwal coal of Pakistan gives higher extractibi1ity with Tetrahydrofuran ( THF ) as compared to Sharigh, Sor-Range and Lakhra coals. The structural characterization of Pakistan coal extracts by FT-IR spectroscopy indicates that all the extracts contained less condensed aromatic rings in comparision to their original coal. 相似文献
996.
AM Elbahnasy AL Shalhav DM Hoenig OM Elashry DS Smith EM McDougall RV Clayman 《Canadian Metallurgical Quarterly》1998,159(3):676-682
PURPOSE: We determine whether there is a significant relationship between the spatial anatomy of the lower pole, as seen on preoperative excretory urography (IVP), and the outcome after shock wave lithotripsy or ureteroscopy for a solitary lower pole caliceal stone 15 mm. or less. MATERIALS AND METHODS: Between January 1992 and June 1996, 34 patients with 15 mm. or less solitary lower pole stone underwent ureteroscopy with intracorporeal lithotripsy (13) or extracorporeal shock wave lithotripsy (ESWL) with a Dornier HM3 lithotriptor (21). On pretreatment IVP lower pole infundibular length and width, infundibulopelvic angle of the stone bearing calix were measured. Stone size and area were determined from an abdominal plain x-ray. A plain x-ray of the kidneys, ureters and bladder was obtained in all patients at a median followup of 12.3 and 8 months in the ureteroscopy and ESWL groups, respectively. RESULTS: After initial therapy the overall stone-free rate was 62 and 52% in the ureteroscopy and ESWL groups, respectively. Stone-free status after ESWL was significantly related to each anatomical measurement. Infundibulopelvic angle 90 degrees or greater, and infundibular length less than 3 cm. and width greater than 5 mm. were each noted to correlate with an improved stone-free rate after ESWL. In contrast, the stone-free rate after ureteroscopy was not statistically significantly impacted by these anatomical features, although a clinical stone-free trend was identified relating to a favorable infundibular length and infundibulopelvic angle. The infundibulopelvic angle was 90 degrees or greater in 4 stone-free patients (12% overall), including 2 who underwent ureteroscopy and 2 who underwent ESWL. On the other hand, in 2 and 4 stone-free patients (18% overall) who underwent ureteroscopy and ESWL, respectively, favorable radiographic features consisted of a short, wide but acutely angulated infundibulum with the infundibulopelvic angle less than 90 degrees, and infundibular length less than 3 cm. and width 5 mm. or greater. In contrast, in 4 and 6 patients (29% overall) who underwent ureteroscopy and ESWL, respectively, all 3 radiographic features were unfavorable with the infundibulopelvic angle less than 90 degrees, and infundibular length greater than 3 cm. and width less than 5 mm. In these cases the stone-free rate was 50 and 17% after ureteroscopy and ESWL, respectively. CONCLUSIONS: The 3 major radiographic features of the lower pole calix (infundibulopelvic angle, and infundibular length and width) can be easily measured on standard IVP using a ruler and protractor. Each factor individually has a statistically significant influence on stone clearance after ESWL. A wide infundibulopelvic angle or short infundibular length and broad infundibular width regardless of infundibulopelvic angle are significant favorable factors for stone clearance following ESWL. Conversely, these factors have a cumulatively negative effect on the stone clearance rate after ESWL when they are all unfavorable. In ureteroscopy spatial anatomy has less of a role in regard to stone clearance but it may have a negative impact when there is uniformly unfavorable anatomy. 相似文献
997.
Heart rate (HR) and heart rate variability (HRV) are risk markers in cardiac disease. HRV is also an index of the sympathovagal modulation of heart rate. Their relations have been rarely analyzed. We aimed to study such relations in normal adult conscious rats by using a novel bradycardic agent, a sinus node inhibitor, S-16257. Placebo-drug crossover designs were used while monitoring HR with telemetry and analyzing HRV in both time and frequency domains. S-16257 (2 mg/kg; n = 10) decreased HR by 29% and markedly increased HRV in parallel. By using various combinations of S-16257, atropine (2 mg/kg), and propranolol (4 mg/kg), a positive relation was shown between RR interval and various indexes of HRV: the slower the HR, the greater the HRV. Nevertheless, there is one exception to this correlation. When S-16257 was associated with both atropine and propranolol, the deep bradycardia was accompanied by a reduction of HRV, which indicates that the physiologic negative correlation between HR and HRV is not an intrinsic property of the pacemaker but is highly dependent on the two components of the autonomic system. 相似文献
998.
999.
1000.