A V0-ATPase-dependent apical trafficking pathway maintains the polarity of the intestinal absorptive membrane.

Intestine function relies on the strong polarity of intestinal epithelial cells and the array of microvilli forming a brush border at their luminal pole. Combining a genetic RNA interference (RNAi) screen with in vivo super-resolution imaging in the Caenorhabditiselegans intestine, we found that the V0 sector of the vacuolar ATPase (V0-ATPase) controls a late apical trafficking step, involving Ras-related protein 11 (RAB-11)+ endosomes and the N-ethylmaleimide-sensitive factor-attachment protein receptor (SNARE) synaptosome-associated protein 29 (SNAP-29), and is necessary to maintain the polarized localization of both apical polarity modules and brush border proteins. We show that the V0-ATPase pathway also genetically interacts with glycosphingolipids and clathrin in enterocyte polarity maintenance. Finally, we demonstrate that silencing of the V0-ATPase fully recapitulates the severe structural, polarity and trafficking defects observed in enterocytes from individuals with microvillus inclusion disease (MVID) and use this new in vivo MVID model to follow the dynamics of microvillus inclusions. Thus, we describe a new function for V0-ATPase in apical trafficking and epithelial polarity maintenance and the promising use of the C. elegans intestine as an in vivo model to better understand the molecular mechanisms of rare genetic enteropathies.

[Single-center retrospective analysis of extracorporal photopheresis in clinical practice : Peripheral venous compared to central venous access]. / Unizentrische, retrospektive Analyse der praktischen Durchführung der extrakorporalen Photopherese : Periphervenöser und zentralvenöser Zugang im Vergleich.

BACKGROUND: Extracorporal photopheresis (ECP) was shown to be effective without severe side effects in the treatment of cutaneous T cell lymphoma (CTCL) and graft versus host disease (GvHD). However, only few studies investigated the practical aspects of ECP. METHODS: Treatment protocols of 2038 ECP procedures in 52 patients (CTCL, n = 29; GvHD, n = 15; other, n = 8) were evaluated. The patients were treated with the UVAR® XTS™ ECP system (Therakos, Inc. Johnson & Johnson, Raritan, NJ, USA) between 2001 and 2010. All patients started with a peripheral venous access. During the course of treatment 7 patients were treated via a port and 4 via a central venous catheter. RESULTS: In all, 1765 (86.6%) treatments were performed with a peripheral venous access; 239 (11.7%) ECPs were done via a port and 34 (1.7%) via a central venous catheter. The peripheral venous access showed a higher flow rate and longer photoactivation time. ECPs via port lead to higher UV-irradiated volumes, longer treatment times and higher differences in systolic blood pressure. The following side effects were observed: being unwell (n = 13), hypo- (n = 13) and hypertension (n = 7), vertigo (n = 4), headache (n = 4), shortness of breath (n = 4), fever (n = 3) and metallic taste (n = 3). Technical complications such as problems with venous access (9.6%) occurred in 385 (18.9%) treatments. CONCLUSIONS: Peripheral venous access should be preferred for ECP treatments.

Impact of an in-Hospital Patient Education Program on Choice of Renal Replacement Modality in Unplanned Dialysis Initiation.

BACKGROUND/AIMS: Up to 50% patients requiring dialysis receive an urgent, unplanned start (UPS) to renal replacement therapy (RRT). Most of these are initiated with an intravenous catheter and commenced and maintained on hemodialysis (HD). Although peritoneal dialysis (PD) could be an equipotent initial modality for RRT, it is used less frequently as long-term RRT in UPS patients. This multicenter-study aimed to evaluate the impact of a structured, in-hospital education program and factors influencing PD rates, especially in UPS patients. METHODS: Three German nephrology departments collaborated to implement an in-hospital education program. Retrospective analysis included 336 subjects and compared the rates of HD and PD in consecutive patients who started RRT 12 months prior (two centers) and for 12 months after (three centers) implementing the education program. RESULTS: PD rates increased significantly (p < 0.05) by 66% in all planned and unplanned dialysis starts after implementation of a structured, patient-centered education program. A highly significant (p < 0.0001) rise in utilization of PD was found, especially in UPS patients. In logistic regression analysis, PD modality choice was significantly influenced by age (p < 0.0001) and gender (p = 0.006). CONCLUSIONS: A structured, patient-centered in-hospital education program increases the frequency of PD in patients needing unplanned RRT. PD modality choice is significantly higher in young (p < 0.0001) and male (p = 0.006) patients.

Infarct-remodelled hearts with limited oxidative capacity boost fatty acid oxidation after conditioning against ischaemia/reperfusion injury.

AIMS: Infarct-remodelled hearts are less amenable to protection against ischaemia/reperfusion. Understanding preservation of energy metabolism in diseased vs. healthy hearts may help to develop anti-ischaemic strategies effective also in jeopardized myocardium. METHODS AND RESULTS: Isolated infarct-remodelled/sham Sprague-Dawley rat hearts were perfused in the working mode and subjected to 15 min of ischaemia and 30 min of reperfusion. Protection of post-ischaemic ventricular work was achieved by pharmacological conditioning with sevoflurane. Oxidative metabolism was measured by substrate flux in fatty acid and glucose oxidation using [(3)H]palmitate and [(14)C]glucose. Mitochondrial oxygen consumption was measured in saponin-permeabilized left ventricular muscle fibres. Activity assays of citric acid synthase, hydroxyacyl-CoA dehydrogenase, and pyruvate dehydrogenase and mass spectrometry for acylcarnitine profiling were also performed. Six weeks after coronary artery ligation, the hearts exhibited macroscopic and molecular signs of hypertrophy consistent with remodelling and limited respiratory chain and citric acid cycle capacity. Unprotected remodelled hearts showed a marked decline in palmitate oxidation and acetyl-CoA energy production after ischaemia/reperfusion, which normalized in sevoflurane-protected remodelled hearts. Protected remodelled hearts also showed higher ß-oxidation flux as determined by increased oxygen consumption with palmitoylcarnitine/malate in isolated fibres and a lower ratio of C16:1+C16OH/C14 carnitine species, indicative of a higher long-chain hydroxyacyl-CoA dehydrogenase activity. Remodelled hearts exhibited higher PPARα-PGC-1α but defective HIF-1α signalling, and conditioning enabled them to mobilize fatty acids from endogenous triglyceride stores, which closely correlated with improved recovery. CONCLUSIONS: Protected infarct-remodelled hearts secure post-ischaemic energy production by activation of ß-oxidation and mobilization of fatty acids from endogenous triglyceride stores.

Oxidative phenol coupling reactions catalyzed by OxyB: a cytochrome P450 from the vancomycin producing organism. implications for vancomycin biosynthesis.

OxyB is a cytochrome P450 enzyme that catalyzes the first phenol coupling reaction during the biosynthesis of vancomycin-like glycopeptide antibiotics. The phenol coupling reaction occurs on a linear peptide intermediate linked as a C-terminal thioester to a peptide carrier protein (PCP) domain within the multidomain glycopeptide nonribosomal peptide synthetase (NRPS). Using model peptides with the sequence (R)(NMe)Leu-(R)Tyr-(S)Asn-(R)Hpg-(R)Hpg-(S)Tyr-S-PCP and (R)(NMe)Leu-(R)Tyr-(S)Asn-(R)Hpg-(R)Hpg-(S)Tyr-(S)Dpg-S-PCP (where Hpg = 4-hydroxyphenylglycine, and Dpg = 3,5-dihydroxyphenylglycine), or containing (R)Leu instead of (R)(NMe)Leu, attached to recombinant PCPs derived from modules-6 and -7 in the vancomycin NRPS, we show that cross-linking of Hpg4 and Tyr6 by OxyB can occur in both hexapeptide- and heptapeptide-PCP conjugates. Thus, whereas OxyB may act preferentially on a hexapeptide still linked to the PCP-6 in NRPS subunit-2, it is possible that a linear heptapeptide intermediate linked to PCP-7 in NRPS subunit-3 may also be transformed into monocyclic product. For turnover, OxyB requires electrons, which in vitro can be supplied by spinach ferredoxin and E. coli flavodoxin reductase. Turnover is also dependent upon the presence of molecular oxygen. The model substrate (R)(NMe)Leu-(R)Tyr-(S)Asn-(R)Hpg-(R)Hpg-(S)Tyr-S-PCP is transformed into cross-linked product by OxyB with a kcat of 0.1 s-1 and Km in the range 4-13 muM. Equilibrium binding of this substrate to OxyB, monitored by UV-vis, is accompanied by a typical low-to-high spin state change in the heme, characterized with a Kd of 17 +/- 5 muM.

Crystal structure of OxyB, a cytochrome P450 implicated in an oxidative phenol coupling reaction during vancomycin biosynthesis.

Gene-inactivation studies point to the involvement of OxyB in catalyzing the first oxidative phenol coupling reaction during glycopeptide antibiotic biosynthesis. The oxyB gene has been cloned and sequenced from the vancomycin producer Amycolatopsis orientalis, and the hemoprotein has been produced in Escherichia coli, crystallized, and its structure determined to 1.7-A resolution. OxyB gave UV-visible spectra characteristic of a P450-like hemoprotein in the low spin ferric state. After reduction to the ferrous state by dithionite or by spinach ferredoxin and ferredoxin reductase, the CO-ligated form gave a 450-nm peak in a UV-difference spectrum. Addition of putative heptapeptide substrates to resting OxyB produced type I changes to the UV spectrum, but no turnover was observed in the presence of ferredoxin and ferredoxin reductase, showing that either the peptides or the reduction system, or both, are insufficient to support a full catalytic cycle. OxyB exhibits the typical P450-fold, with helix L containing the signature sequence FGHGXHXCLG and Cys(347) being the proximal axial thiolate ligand of the heme iron. The structural similarity of OxyB is highest to P450nor, P450terp, CYP119, and P450eryF. In OxyB, the F and G helices are rotated out of the active site compared with P450nor, resulting in a much more open active site, consistent with the larger size of the presumed heptapeptide substrate.