MR‐based measurements and simulations of the magnetic field created by a realistic transcranial magnetic stimulation (TMS) coil and stimulator

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 (B_TMS) produced by standard TMS stimulators are still lacking. Such a validation can be performed by mapping B_TMS 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 B_TMS were performed. MR‐based measurements allow the mapping and quantification of B_TMS starting 2.5 cm from the TMS coil. For closer regions, the intra‐voxel dephasing induced by B_TMS 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.     

Influence of Imaging on the Negative Appendectomy Rate in Pregnancy

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.     

Effect of MG132 on proteasome activity and prooxidant/antioxidant status of rat liver subjected to ischemia/reperfusion injury.

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.     

Immunohistochemical study of cells of invasive cancer of the vaginal part of the cervix uteri]

Immunohistochemical study of cervical carcinoma used EE21-06d monoclonal antibodies which identify five cytokeratin polypeptides inherent in the squamous epithelium. PAP-method and reaction of immunofluorescence were employed. Initial stages of squamous cell carcinoma invasion were characterized by bleaching or complete cell discoloring of most tumor cells. However, in deeply invading tumors, the share of intensively stained cells was markedly increased. The results point to expression of different cytokeratins or cell clones replacement with tumor progression. The peculiarities of cytokeratin distribution may serve to determine the degree of invasion and differentiation of tumor cells.     

The characteristics of the hemagglutinin from persistent variants of the influenza virus A/Victoria/35/72 (H3N2)

Electrophoresis in polyacrylamide gel of the reference influenza A/Victoria/35/72 (H3N2) virus and its persisting variants (PV) showed that the PV isolated on the 158th day from the moment of persistence modelling (PV158) had mutation in the gene of hemagglutinin (HA). This mutation is manifested by incomplete HA synthesis at 40 degrees C and increase of mobility of the light HA subunit (HA2). Analysis of nucleotide sequence of the greater part of HA gene of PV158 virus revealed 5 nucleotide substitutions four of which were significant. Three substitutions were found in Hal: 219 (Ser----Phe), 220 (Arg----Gly), 226 (Leu----Gln) and one in HA2: 156 (Thr----Asn). The importance of these mutations in the determination of the PV phenotype is discussed.