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V. A. Sazhin A. A. Shcherbakov A. G. Breslaukhov A. A. Ozerov V. I. Petrov 《Pharmaceutical Chemistry Journal》1991,25(8):569-573
Translated from Khimiko-farmatsevticheskii Zhurnal, Vol. 25, No. 8, pp. 50–53, August, 1991. 相似文献
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MR‐based measurements and simulations of the magnetic field created by a realistic transcranial magnetic stimulation (TMS) coil and stimulator
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Stefano Mandija Petar I. Petrov Sebastian F.W. Neggers Peter R. Luijten Cornelis A.T. van den Berg 《NMR in biomedicine》2016,29(11):1590-1600
Transcranial magnetic stimulation (TMS) is an emerging technique that allows non‐invasive neurostimulation. However, the correct validation of electromagnetic models of typical TMS coils and the correct assessment of the incident TMS field (BTMS) produced by standard TMS stimulators are still lacking. Such a validation can be performed by mapping BTMS produced by a realistic TMS setup. In this study, we show that MRI can provide precise quantification of the magnetic field produced by a realistic TMS coil and a clinically used TMS stimulator in the region in which neurostimulation occurs. Measurements of the phase accumulation created by TMS pulses applied during a tailored MR sequence were performed in a phantom. Dedicated hardware was developed to synchronize a typical, clinically used, TMS setup with a 3‐T MR scanner. For comparison purposes, electromagnetic simulations of BTMS were performed. MR‐based measurements allow the mapping and quantification of BTMS starting 2.5 cm from the TMS coil. For closer regions, the intra‐voxel dephasing induced by BTMS prohibits TMS field measurements. For 1% TMS output, the maximum measured value was ~0.1 mT. Simulations reflect quantitatively the experimental data. These measurements can be used to validate electromagnetic models of TMS coils, to guide TMS coil positioning, and for dosimetry and quality assessment of concurrent TMS‐MRI studies without the need for crude methods, such as motor threshold, for stimulation dose determination. 相似文献
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Carmelita A. Wallace Maxim S. Petrov David I. Soybel Stephen J. Ferzoco Stanley W. Ashley Ali Tavakkolizadeh 《Journal of gastrointestinal surgery》2008,12(1):46-50
Appendectomy is the most common non-gynecologic surgery performed during pregnancy. Little data exist on the accuracy of imaging
studies in the diagnosis of appendicitis in pregnancy. The objective of this study was to evaluate the probability of ultrasound
and computed tomography (CT) scan in diagnosing appendicitis in pregnancy, as reflected in the negative appendectomy rate.
We retrospectively reviewed the charts of 86 pregnant women who underwent an appendectomy between January 1, 1997 and January
1, 2006. Patients were divided into three groups: clinical evaluation, ultrasound, and ultrasound followed by a CT scan. The
clinical evaluation group had 13 patients, with a negative appendectomy rate of 54% (7/13). Fifty-five patients underwent
an ultrasound alone, with a negative appendectomy rate 36% (20/55). In the ultrasound/CT group (n = 13), the negative appendectomy rate was 8% (1/13). There was a significant reduction in the negative appendectomy rate
in the ultrasound/CT scan group compared to clinical evaluation group (54 vs 8%, p < 0.05). This reduction was not achieved in the ultrasound group when compared to the clinical evaluation group or the ultrasound/CT
group (p = 0.05). A significant reduction was achieved when the ultrasound/CT group was compared to the patients in the ultrasound
only group who had a normal or inconclusive ultrasound (p < 0.05). Our data documents a very high negative appendectomy rate in the pregnant patient. We recommend an ultrasound followed
by a CT scan in patients with a normal or inconclusive ultrasound. 相似文献
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Albena Alexandrova Lubomir Petrov Almira Georgieva Mila Kessiova Elina Tzvetanova Margarita Kirkova Marian Kukan 《Hepatology research》2008,38(4):393-401
Aim: Previous studies have shown that proteasome inhibitors exerted protective effects against ischemia/reperfusion injury (IRI) of brain, heart, kidney and intestine. The aim of the present study was to investigate: (i) whether the proteasome inhibitor MG132 protects rat liver against IRI; and (ii) whether MG132 modulates prooxidant/antioxidant status of rat liver subjected to warm IRI. Methods: The left lateral and medial lobes (approximately 70% of the total liver volume) of livers of male Wistar rats were subjected to 30-min ischemia followed by 60-min reperfusion. Lactate dehydrogenase (LDH), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) levels were measured in the plasma. Proteasome chymotryptic-like (ChT-L) activity, levels of thiobarbituric acid-reactive substances (TBARS), protein carbonyls (PC) and glutathione (GSH), as well as superoxidase dismutase (SOD), catalase (CAT), glutathionine peroxidase and glutathionine reductase activities were measured in liver fractions. Results: Thirty-min ischemia followed by 60-min reperfusion increased liver TBARS and PC, CAT and SOD activities, but decreased GSH level. Ischemia/reperfusion-induced oxidative stress was exacerbated in mitochondria, indicating that these organelles are the preferential target of IRI. Plasma LDH and AST levels were decreased by MG132 during both ischemia and reperfusion, while ALT values were decreased only after 30 min of reperfusion. MG132 did not significantly affect liver TBARS and GSH levels, but it increased PC and decreased ChT-L activity; the activities of CAT and SOD were also decreased. Conclusions: MG132 exerts a protective effect during the early phase of reperfusion and it modulates prooxidant/antioxidant status of rat liver subjected to warm IRI. 相似文献
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