Neuroimaging in Pineal Tumors

BACKGROUND AND PURPOSE: The authors report radiological findings in 11 tumors in the pineal region, which were histologically diagnosed as germinomas, pineocytomas pineoblastomas, ependymomas, teratomas, and astrocytomas. METHODS: Computed tomography (CT) was performed in seven patients and magnetic resonance imaging (MRI) was performed in all patients. RESULTS: CT showed a solid or solid/cystic mass with variable contrast enhancement. MRI showed a heterogeneous mass, with hypointense signal on T1 and iso/hyperintense signal on T2-weighted images (WI) and gadolinium enhancement. Extension to adjacent structures occurred in five patients and spread through the cerebral spinal fluid (CSF) in two. CONCLUSIONS: Pineal region tumors have no pathognomonic imaging pattern. MRI and CT are complementary in diagnosis and are important to determine localization, extension, and meningeal spread.     

Expression and characterization of Gag protein of HIV-1（CN） in Pichia pastoris

To express the core protein of HIV-1 of Chinese prevalent strain （HIV-1 （CN）） in Pichia pastoris, the fulllength gag gene was inserted into the secretory expression vector pHILS1. Linearized recombinant plasmid pHILGAG by Sail was electrotransformed into the yeast strain GS115, and the yeast transformants were identified by PCR. To induce the interest protein to be expressed, the PCR positive transformants were inoculated in the medium of BMGY and BMMY, mRNA of the strain was detected by RT-PCR, and the expressed protein was analyzed by SDS-PAGE, Western blotting and thin layer scanning. mRNA （1.3 kb） was amplified by RT-PCR. SDS-PAGE and Western blotting analysis showed that the molecular mass of the expressed protein was 55 kD, which was similar to the expected value, and the expressed protein could react with McAb to HIV-1 p24. Thin layer scanning analysis demonstrated that the whole amount of the expressed protein was approximately 13 % of the soluble protein in the supernatant. The recombinant yeast had good genetic stability. The optimal expression conditions of the engineering yeast were as follows： BMMY medium, 80-90% of dissolved oxygen, 1% methanol, and 3-day-cultivation course. Gag proteins were expressed under the optimal expression condition and purified via gel filtration chromatography. The purity of the interest protein was up to 85 %. After the purified proteins were inoculated into BALB/c mice, the anti-HIV-1 antibodies in the immunized mice could be detected by Western blotting.     

The hemodynamic consequences of cardiac arrhythmias: Evaluation of the relative roles of abnormal atrioventricular sequencing,irregularity of ventricular rhythm and atrial fibrillation in a canine model

To evaluate the hemodynamic consequences of various cardiac arrhythmias, hemodynamic and angiographic studies were performed on 20 open-chest, atrioventricular (AV) heart-blocked dogs during various programmed pacing protocols. Protocols included AV pacing at intervals of 100 msec and ?100 msec, ventricular (V) pacing during AV dissocation, and V pacing during atrial fibrillation (AF). In addition, the effects of regular versus irregular V pacing were also evaluated. During regular V pacing, cardiac output was optimal at an AV interval of 100 msec, but decreased by 25% at AV ?100 msec and by 18% during both AV dissociation and AF. During irregular V cycles, cardiac output decreased further (e.g., by an additional 7% during AF). Pulmonary venous regurgitation was observed only during AV dissociation and during regular pacing at AV ?100 msec. Notably, mitral valvular regurgitation was observed only during irregular V cycles, but not during regular V pacing, even in the presence of AV dissociation or AF. Using these methods it was possible to resolve some previously reported controversies regarding the relative importance of AV sequencing, atrial systole versus AF, regular versus irregular rhythms, as well as the possible contribution of mitral and/or pulmonary venous regurgitation to the adverse hemodynamics of various cardiac arrhythmias.     

Increased R-wave amplitude induced by acute myocardial ischemia in the dog: A predictor of malignant ventricular arrhythmias

The ability of an increase of 25 % or greater in the sum of R-wave amplitudes in leads X, Y, Z, L₂, and V₅ to predict the occurrence of malignant ventricular arrhythmias (10 or more ventricular premature beats/min, ventricular tachycardia [5 or more consecutive premature beats], and/or fibrillation) was evaluated in 17 dogs during experimental acute myocardial ischemia. Each dog underwent a 15 minute ligation of the left anterior descending coronary artery followed by reperfusion and after recovery, 2 hours later, a 15 minute ligation of the circumflex coronary artery. During ligation of the left anterior descending coronary artery, 12 of 17 dogs (71%) showed no R-wave increase and no arrhythmias (true-negative response). In 5 (29%) of 17 dogs malignant ventricular arrhythmias developed: 2 of 5 (40%) dogs with arrhythmias had a concomitant R-wave increase (true-positive response), and 3 of 5 (60%) with arrhythmias had a less than 25% increase in R-wave amplitude (false-negative results). During circumflex coronary artery ligation, 13 of 17 (76%) dogs showed both R-wave increases and arrhythmias (true-positive response). Four (24%) of 17 dogs had no arrhythmias: 3 of 4 (75%) with no arrhythmias also had a less than 25% increase in R-wave amplitude (true-negative response), whereas 1 of 4 (25%) dogs with no arrhythmias had an increase in R-wave amplitude (false-positive response). In dogs with both arrhythmias and R-wave increases, R-wave changes preceded the onset of arrhythmias by a mean (± standard deviation) of 1 minute 27 seconds (± 43 seconds). Overall, R-wave increases were highly sensitive (83%), specific (94%), and predictive (94%) for the occurrence of malignant ventricular arrhythmias during experimental acute myocardial ischemia.