Angiographic patterns of portal venous system in children with extrahepatic portal hypertension and its etiological and clinical relevance.

PURPOSE: To study the relationship between the angiographic pattern of extrahepatic portal vein obstruction (EHPVO) and its etiology and clinical manifestations. METHODS: Clinical, etiological, and angiographic findings in 155 children with EHPVO were reviewed. Anatomy of extrahepatic portal venous system (EPVS) was categorized into five imaging patterns. Assessment of the severity of esophageal and gastric varices (EV and GV) was performed by upper gastrointestinal endoscopy. RESULTS: Based on multislice CT angiography, most commonly observed pattern of EHPVO was type I (48.4%) and type II (29%). According to anamnesis, 68 (43.8%) children had pathological conditions in neonatal period. Of these, 35 (22.6%) had an umbilical vein catheterization, 11 (7.1%) had a history of omphalitis, and 9 (5.8%) had prolonged jaundice. Thirteen (8.4%) patients had various septic conditions in neonatal period and it was more common associated with widespread thrombosis throughout the EPVS (type 5)-28% of observations. Significantly lower risk of bleeding from EV (p = 0.01) was noted in children with type IV pattern, whereas children with type III and V patterns had higher grades of EV. CONCLUSION: Angiographic pattern of portomesenteric occlusion may provide a clue to its etiology, and clinical manifestation, especially in children with widespread thrombosis throughout the EPVS.

Deep Learning-Based Image Registration in Dynamic Myocardial Perfusion CT Imaging.

Registration of dynamic CT image sequences is a crucial preprocessing step for clinical evaluation of multiple physiological determinants in the heart such as global and regional myocardial perfusion. In this work, we present a deformable deep learning-based image registration method for quantitative myocardial perfusion CT examinations, which in contrast to previous approaches, takes into account some unique challenges such as low image quality with less accurate anatomical landmarks, dynamic changes of contrast agent concentration in the heart chambers and tissue, and misalignment caused by cardiac stress, respiration, and patient motion. The introduced method uses a recursive cascade network with a ventricle segmentation module, and a novel loss function that accounts for local contrast changes over time. It was trained and validated on a dataset of n = 118 patients with known or suspected coronary artery disease and/or aortic valve insufficiency. Our results demonstrate that the proposed method is capable of registering dynamic cardiac perfusion sequences by reducing local tissue displacements of the left ventricle (LV), whereas contrast changes do not affect the registration and image quality, in particular the absolute CT (HU) values of the entire CT sequence. In addition, the deep learning-based approach presented reveals a short processing time of a few seconds compared to conventional image registration methods, demonstrating its application potential for quantitative CT myocardial perfusion measurements in daily clinical routine.

Comparative analysis of the effects of synthetic derivatives of batrachotoxin on sodium currents in frog node of Ranvier.

1. In voltage-clamp experiments on frog myelinated nerve fibers, the effects of nine synthetic derivatives of batrachotoxin (BTX) obtained from 7,8-dihydrobatrachotoxinin A (DBTX-A) on Na+ currents (INa) have been investigated. 2. Both of 20 alpha-esters of DBTX-A with 2,4,5-trimethylpyrrol-3-carboxylic acid (DBTX-P) and benzoic acid (DBTX) at a 10(-5) M concentration caused modification of INa qualitatively similar to that induced by BTX. 3. The quaternary derivative of DBTX (QDBTX) produced such changes in INa only at a 5.10(-4) M concentration, apparently due to its much lower lipid solubility. 4. Replacement of a -CH2- by a -C = O. group in the homomorpholine ring near the tertiary nitrogen atom abolished the DBTX activity, strongly suggesting the necessity of tertiary nitrogen protonation for the toxin interaction with the channel receptor. 5. Transfer of an 11-hydroxygroup from the alpha- to the beta-position in the DBTX molecule did not decrease its activity in spite of the fact that in the beta-position this group is sterically very hindered. The activity of 11 beta-DBTX is at variance with the prediction of Codding's (1983) "oxygen triad" hypothesis. 6. DBTX-A and compounds obtained from DBTX by oxidation of the 11 alpha-hydroxygroup (K-DBTX), acetylation (Ac-DBTX), or reduction of the hemiketal moiety (H2DBTX) even at a concentration as high as 10(-3) M were able to modify only a very small fraction of the Na channels. However, a clear-cut reversible blocking action on both normal and modified Na channels was observed. 7. These results led us to conclude that BTX modifies the Na channels only in the charged form and hemiketal and 20 alpha-ester moieties provide adequate disposition of toxin on the receptor surface. The inability of H2DBTX, DBTX-A, and K-DBTX and Ac-DBTX to modify most of the Na channels can be explained by a low "probability of correct disposition" of these ligands on the receptor surface.