Abnormal coronary perfusion in experimental scorpion envenomation

Perfusion defects and left ventricular dilation after experimental scorpion envenomation were evaluated in five dogs. Left ventricular dilation was observed in three dogs and right ventricular dilation in one other, in scans immediately after envenomation. Perfusion defects were inferred from scans in four dogs. The data are strongly suggestive of coronary hypoperfusion, and the mechanics of abnormal coronary flow after scorpion envenomation are discussed.     

Distribution of vesicular stomatitis virus proteins in the brain of BALB/c mice following intranasal inoculation: an immunohistochemical analysis

Earlier studies have shown that intranasal instillation of vesicular stomatitis virus (VSV), a negative-sense RNA virus, in mice and rats can result in infection of the brain, hind-limb paralysis and death. Using an antiserum directed against VSV proteins, we sought to determine the potential neuronal and non-neuronal pathways VSV utilize, for central nervous system dissemination in BALB/c mice. Within 12 h following intranasal inoculation of VSV, VSV antigen could be detected in the olfactory nerve layer of the ipsilateral olfactory bulb. Within 3–4 days post-inoculation (p.i.), VSV had disseminated into the glomeruli of the olfactory bulb as well as the anterior olfactory nuclei that were ipsilateral to the VSV instillation. Within the glomeruli, VSV antigen was more prevalent in the granule cells than in the mitral cells. Correspondingly, the lateral olfactory tract, where axons of mitral cells course, remained VSV negative throughout 7 days p.i. By 7 days p.i., viral proteins were detected in several additional regions extending to the brainstem. These included regions involved in -rhythm generation during exploration and REM sleep, i.e. the septal nuclei, the suprammamilary body, and the hippocampal formation, as well as the amygdaloid complex and brainstem neuromodulatory centers, such as the dorsal raphe´and locus coerullus. Structures abutting the ventricular surfaces, such as the dorsal cochlear nucleus, were also labeled. Tracts immunoreactive to VSV included the dorsal tegmental tract, fascia retroflexus, Probst tract, and mesencephalic tract of the trigeminal motor nerve. Besides the lateral olfactory tract, tracts that remained VSV negative included the anterior commissure, the corpus callosum and the mammilary peduncle. The pattern of VSV immunoreactivity supports the idea that following infection of the olfactory bulb glomeruli, VSV spreads via both ventricular surfaces and retrograde transport within axons of neuromodulatory transmitter systems innervating the olfactory bulb. Conversely, regions exhibiting low levels of VSV antigen are not likely to be involved in VSV dissemination. In particular, the paucity of VSV antigen in some of the terminal fields of neuromodulatory systems indicate that anterograde transport is more selective than retrograde transport. Surprisingly, the principal neurons of the olfactory glomeruli, thalamus, cerebral cortex and the hippocampus, all of which usel-glutamate as the excitatory neurotransmitter, are much less involved in viral dissemination.     

Quantitative Evaluation of 2-Deoxy-2[F-18]fluoro-<Emphasis Type="SmallCaps">d</Emphasis>-glucose-Positron Emission Tomography Imaging on the Woodchuck Model of Hepatocellular Carcinoma with Histological Correlation

Purpose The Eastern woodchuck (Marmota monax) is considered as a naturally occurring animal model of hepatocellular carcinoma (HCC). The performance of 2-deoxy-2-[F-18]fluoro-d-glucose (FDG) for imaging HCC on the woodchuck using Positron emission tomography (PET) was investigated in this study. Procedures Dynamic FDG-PET scans were performed on five woodchucks with HCC and one healthy woodchuck before removal and processing of the liver tissues for histology. The parameters of a two-tissue compartment model with dual input were estimated using weighted least squares (WLS). Results Ten HCCs were confirmed histologically. Six HCCs had a tumor-to-liver standardized uptake value (SUV) ratio ≤1.15, a k ₄ / k ₃ ratio similar to that in hepatic tissues and were well-differentiated. Four HCCs had a tumor-to-liver SUV ratio >1.15, a lower k ₄ / k ₃ ratio than the hepatic tissues and were moderately differentiated. Conclusions Increased FDG uptake was observed in HCCs that were the least differentiated and correlated with a lower k ₄ / k ₃ ratio.     

Do the recently modified pacemaker guidelines for neurocardiogenic syncope also apply to young patients? Analysis based on five-year follow-up of israeli soldiers with syncope and a positive tilt test

To assess the classification of neurocardiogenic syncope (NCS) as a IIA indication for pacemaker implantation in the recent American College of Cardiology/American Heart Association Task Force on Practice Guidelines/North American Society for Pacing and Electrophysiology guidelines, we performed chart reviews and follow-up interviews in a cohort of 45 consecutive young Israeli soldiers (age 18-24 years) with a history of syncope (mean of 9 prior syncopal episodes) and a positive tilt test treated with drug therapy. Asystole longer than 5 s during tilt testing occurred in 11 patients. Five years later, we found that only 2 patients were still taking medications, only 1 patient (2%) still reported frequent syncopal or near-syncopal episodes and 3 patients (7%) had rare symptoms (no more than one syncopal episode during the past 2 years), while the remaining 40 (89%) were symptom free off medications. Thus, NCS in young patients, even with prolonged asystole during tilt testing, a history of frequent syncopal episodes and other high- risk factors described in the guidelines, is often a self-limiting disorder, perhaps stress related or situational in nature; an overwhelming number of patients become asymptomatic and stop taking medications within 1-2 years. These patients do not require long-term therapy; thus, our data would suggest that the IIA pacing indication for NCS should be restricted to older patients.     

Integration of woodchuck hepatitis and N-myc rearrangement determine size and histologic grade of hepatic tumors

Integrations of woodchuck hepatitis virus (WHV) DNA and rearrangements of the N-myc 2 gene have been detected frequently in hepatocellular carcinoma (HCC) of Eastern woodchucks (Marmota monax) chronically infected with WHV. Fifty-five hepatocellular neoplasms and matched nontumor hepatic tissue specimens obtained postmortem from 13 chronic WHV carriers were analyzed and the frequency of WHV DNA integrations and of N-myc rearrangements compared in tumors of different size and histologic grade. Four small tumor nodules were classified histologically as adenomas and integrated sequences of WHV DNA were detected in two of the four tumor nodules. In one of the two nodules, there was evidence of N-myc rearrangement. Fifty-one neoplasms were classified as HCC. Seven were grade 1 HCCs. WHV DNA integrations were demonstrated in 43% but none had N-myc rearrangements. Twenty grade 2 HCCs had WHV DNA integrations in 80% and in 38% N-myc rearrangements were present. Twenty-four grade 3 HCCs had integrations of WHV DNA in 79% and N-myc rearrangements in 74%. In two other grade 3 HCCs, rearrangements of N-myc were detected in the absence of WHV DNA integrations. The 12 largest tumors in the series all were grade 2 or 3 HCCs, and in 83%, both WHV DNA integrations and N-myc rearrangements were demonstrated. In conclusion, molecular changes observed in this study suggest a progression of genetic alterations providing either a significant proliferative stimulation and/or a growth advantage in hepatocarcinogenesis of woodchucks with chronic WHV infection.