Transjugular intrahepatic portosystemic shunts (TIPS) in children

The transjugular intrahepatic portosystemic shunt procedure is an accepted treatment for adults with complications of portal hypertension. We performed a retrospective review of all pediatric TIPS placements performed at the University of California, San Francisco between 1990 and 1996. Twelve procedures were attempted in nine children, with a mean age (+/- SD) of 9.4 +/- 3.9 years (range, 5 to 15 years) and a mean weight of 31 +/- 18 kg (range, 16 to 70 kg). The indications for TIPS placement were portal hypertension complicated by chronic variceal hemorrhage not controlled with sclerotherapy (n = 7) and hypersplenism with thrombocytopenia (n = 2). TIPS placement was successfully completed initially in seven of nine (78%) patients. Unfavorable vascular anatomy was the cause of failure in two cases. The seven patients who underwent successful TIPS placement were followed up for an average of 136 days (range, 1 to 800 days); two still have patent shunts, three underwent liver transplantation, one had a splenorenal shunt after stenosis, and one died of underlying liver disease. Variceal bleeding was controlled in four of five patients who successfully underwent TIPS placement. Shunt occlusion occurred in four patients; patency was restored by transjugular shunt revision in three, and a splenorenal shunt was performed in one.     

Serum amyloid P component scintigraphy and turnover studies for diagnosis and quantitative monitoring of AA amyloidosis in juvenile rheumatoid arthritis

OBJECTIVE: To evaluate aspects of the natural history of AA amyloidosis complicating juvenile rheumatoid arthritis (JRA), and its response to therapy with chlorambucil. METHODS: Scintigraphy and 7-day turnover studies were performed in JRA patients with histologically proven (n = 35) or clinically suspected (n = 30) AA amyloidosis, following intravenous injection of 123I and 125I-labeled serum amyloid P component (SAP). Prospective monitoring studies were performed over 2-3 years in 20 patients with amyloidosis. All but 2 amyloidosis patients were treated with chlorambucil. RESULTS: Positive scanning results were obtained in all patients in whom imaging was performed within 12 years of positive biopsy findings of amyloid and in 5 patients with clinically suspected amyloidosis. Negative scanning results with normal SAP metabolism, indicating regression of amyloid, were obtained in 4 patients whose amyloidosis had been in full clinical remission for more than 12 years. Prospective monitoring studies in patients whose JRA-associated inflammatory activity was in remission demonstrated regression of amyloid in 8 patients and no substantial changes in 8 others; however, in 4 further patients with active inflammation, there was accumulation of amyloid. There was a very poor correlation between the amount of amyloid present at a particular site and the resultant organ dysfunction. CONCLUSION: Radiolabeled SAP scintigraphy and turnover studies are useful complementary tools in the diagnosis, screening, and quantitative monitoring of type AA amyloidosis in JRA. The amyloid deposits may progress and/or regress at different rates in different anatomic sites over short periods.     

Internal mammary vein to coronary artery anastomotic fistula

Two patients are presented where internal mammary artery grafting was performed for the relief of symptomatic coronary artery disease. At follow-up the internal mammary artery was occluded and a communication between the internal mammary vein and the native coronary artery was demonstrated. These patients were characterised by the early recurrence of angina or the appearance of a continuous murmur. Both patients were treated by re-operation with ligation of the arterio-venous fistula and saphenous vein grafting.     

Laser therapy of Barrett''s mucosa

Midden and Dahl, in a recent paper, have presented important data on the inactivation of bacteria by singlet oxygen. In analyzing the data, use was made of a theory published earlier by the present author. The purpose of this paper is to point out that theory and experiment can be brought into better agreement by assuming that the interaction of singlet oxygen with the bacteria takes place in an essentially lipid environment rather than aqueous.     

Structure-function relationships in membrane segment 5 of the yeast Pma1 H+-ATPase

Membrane segment 5 (M5) is thought to play a direct role in cation transport by the sarcoplasmic reticulum Ca2+-ATPase and the Na+, K+-ATPase of animal cells. In this study, we have examined M5 of the yeast plasma membrane H+-ATPase by alanine-scanning mutagenesis. Mutant enzymes were expressed behind an inducible heat-shock promoter in yeast secretory vesicles as described previously (Nakamoto, R. K., Rao, R., and Slayman, C. W. (1991) J. Biol. Chem. 266, 7940-7949). Three substitutions (R695A, H701A, and L706A) led to misfolding of the H+-ATPase as evidenced by extreme sensitivity to trypsin; the altered proteins were arrested in biogenesis, and the mutations behaved genetically as dominant lethals. The remaining mutants reached the secretory vesicles in sufficient amounts to be characterized in detail. One of them (Y691A) had no detectable ATPase activity and appeared, based on trypsinolysis in the presence and absence of ligands, to be blocked in the E1-to-E2 step of the reaction cycle. Alanine substitution at an adjacent position (V692A) had substantial ATPase activity (54%), but was likewise affected in the E1-to-E2 step, as evidenced by shifts in its apparent affinity for ATP, H+, and orthovanadate. Among the mutants that were sufficiently active to be assayed for ATP-dependent H+ transport by acridine orange fluorescence quenching, none showed an appreciable defect in the coupling of transport to ATP hydrolysis. The only residue for which the data pointed to a possible role in cation liganding was Ser-699, where removal of the hydroxyl group (S699A and S699C) led to a modest acid shift in the pH dependence of the ATPase. This change was substantially smaller than the 13-30-fold decrease in K+ affinity seen in corresponding mutants of the Na+, K+-ATPase (Arguello, J. M., and Lingrel, J. B (1995) J. Biol. Chem. 270, 22764-22771). Taken together, the results do not give firm evidence for a transport site in M5 of the yeast H+-ATPase, but indicate a critical role for this membrane segment in protein folding and in the conformational changes that accompany the reaction cycle. It is therefore worth noting that the mutationally sensitive residues lie along one face of a putative alpha-helix.     

Calcium stimulates intramitochondrial cholesterol transfer in bovine adrenal glomerulosa cells

In adrenal glomerulosa cells, angiotensin II (Ang II) stimulates aldosterone synthesis through rises of cytosolic calcium ([Ca2+]c). The rate-limiting step in this process is the transfer of cholesterol to the inner mitochondrial membrane, where it is converted to pregnenolone by the P450 side chain cleavage enzyme. The aim of the present study was to examine the effect of changes in [Ca2+]c and of Ang II on intramitochondrial cholesterol distribution. Freshly prepared bovine zona glomerulosa cells were submitted to a cytosolic Ca2+ clamp (600 nM) or stimulated with Ang II (10 nM). Mitochondria were isolated and subfractionated into outer membranes (OM), inner membranes (IM), and contact sites (CS). Cholesterol content was determined by the cholesterol oxidase assay. Stimulation of intact cells with Ca2+ led to a marked decrease in cholesterol content of OM (to 54 +/- 24% of controls, n = 5) and to a concomitant increase of cholesterol in CS and IM (to 145 +/- 14%, n = 5). When glomerulosa cells were exposed to Ang II, a marked increase of cholesterol in CS occurred (to 172 +/- 16% of controls, n = 5). No significant changes were detected in OM cholesterol, suggesting a stimulation of cholesterol supply to the mitochondria in response to Ang II. Cycloheximide specifically and significantly reduced Ca2+-activated cholesterol transfer to CS and IM. In conclusion, our data indicate that one of the main functions of the Ca2+ messenger is to increase cholesterol supply to the P450 side chain cleavage enzyme by enhancing endogenous intermembrane cholesterol transfer to a mitochondrial site containing the enzymes responsible for the initial steps of the steroidogenic cascade.