Transendothelial transport and metabolism of adenosine and inosine in the intact rat aorta

This study was aimed at defining the role of vascular endothelium in the transport and metabolism of adenosine. For this purpose, endothelium-intact and endothelium-denuded isolated rat aortas, perfused at constant flow (2 ml/min), were prelabeled with 3H-adenosine or 3H-inosine for 10 minutes at concentrations of 0.012-100 microM. Sequestration of adenosine by endothelium was determined from radioactivity recovered during selective endothelial cell removal with deoxycholic acid (0.75% for 15 seconds). In the physiological concentration range of adenosine (0.012-1 microM), fractional sequestration by endothelium was 90-92% of the total adenosine incorporation by the aorta. Endothelial sequestration of inosine at 0.1 microM was 85%. At 100 microM adenosine or inosine, fractional sequestration by aortic endothelium was 33% and 39%, respectively. Analysis of the specific radioactivity of adenine nucleotides extracted from prelabeled aortas indicated that most of the adenosine was incorporated into endothelial adenine nucleotides. Incorporation of inosine into endothelial ATP was approximately 15% that of adenosine. Inhibition of aortic adenosine deaminase with erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA) did not influence sequestration of 0.1 microM adenosine, but resulted in a 49% reduction of total endothelial incorporation at 100 microM adenosine. Transfer of radioactive purines from the endothelium to underlying smooth muscle after prelabeling was equivalent to only 1%/hr of total endothelial radioactivity. Our findings suggested that 1) macrovascular endothelium of the aorta constitutes a highly effective metabolic barrier for circulating adenosine and inosine; 2) transfer of labeled adenine nucleotides from endothelium to underlying smooth muscle is rather small and most likely proceeds via dephosphorylated purine compounds; and 3) measurement of adenosine trapping in endothelial and smooth muscle compartments overestimates the transendothelial adenosine concentration gradient.     

Akuter Myokardinfarkt – primäre Angioplastie oder Thrombolyse?

Zum Thema In den letzten 4 Jahrzehnten konnte die Sterblichkeit nach akutem Myokardinfarkt deutlich gesenkt werden. Insbesondere die Einführung der Thrombolyse und der interventionellen Therapie mittels Katheterdilatation verbesserten die Ergebnisse bedeutsam. Angesichts zus?tzlicher Verbesserungen beider Therapieoptionen und der Einführung weiterer antithrombotischer Substanzen muss eine Neubewertung der Therapie des akuten Koronarsyndroms erfolgen. Hierzu soll die vorliegende übersicht einen Beitrag leisten.     

A prospective study on incidence and risk factors of arteriovenous fistulae following transfemoral cardiac catheterization

BACKGROUND: A potentially harmful complication of cardiac catheterization is the arteriovenous fistula. Precise knowledge of possible factors predisposing for acquisition of iatrogenic AV-fistulae could enable cardiologists to perform a risk stratification for cardiac patients prior to catheterization. METHODS: Over a period of 2 years, 10,271 consecutive patients who underwent cardiac catheterization were included in this study. Auscultation of a new femoral bruit was followed by a duplex scan to confirm the suspected diagnosis of an AVF. Every patient was investigated on the day after catheterization. RESULTS: The incidence of iatrogenic AVF was 0.86%. A multivariate regression analysis revealed five significant and independent risk factors: (1) procedural heparin dosage >or=12,500 IU (Odds Ratio (OR)=2.88), (2) coumadin therapy (OR=2.34), (3) puncture of the left groin (OR=2.21), (4) arterial hypertension (OR=1.86) and (5) female gender (OR=1.84). Coronary angioplasty (instead of diagnostic procedure), size and number of sheaths, age and body mass index did not significantly affect the incidence of AVF. CONCLUSIONS: The overall incidence of AV-fistulae following cardiac catheterization approximates 1%. Determination of significant risk factors will facilitate identification of patients at risk for iatrogenic arteriovenous fistulae prior to cardiac catheterization and thus help to develop strategies to reduce the incidence of AV-fistulae.     

Human and Animal Isolates of Yersinia enterocolitica Show Significant Serotype-Specific Colonization and Host-Specific Immune Defense Properties

Yersinia enterocolitica is a human pathogen that is ubiquitous in livestock, especially pigs. The bacteria are able to colonize the intestinal tract of a variety of mammalian hosts, but the severity of induced gut-associated diseases (yersiniosis) differs significantly between hosts. To gain more information about the individual virulence determinants that contribute to colonization and induction of immune responses in different hosts, we analyzed and compared the interactions of different human- and animal-derived isolates of serotypes O:3, O:5,27, O:8, and O:9 with murine, porcine, and human intestinal cells and macrophages. The examined strains exhibited significant serotype-specific cell binding and entry characteristics, but adhesion and uptake into different host cells were not host specific and were independent of the source of the isolate. In contrast, survival and replication within macrophages and the induced proinflammatory response differed between murine, porcine, and human macrophages, suggesting a host-specific immune response. In fact, similar levels of the proinflammatory cytokine macrophage inflammatory protein 2 (MIP-2) were secreted by murine bone marrow-derived macrophages with all tested isolates, but the equivalent interleukin-8 (IL-8) response of porcine bone marrow-derived macrophages was strongly serotype specific and considerably lower in O:3 than in O:8 strains. In addition, all tested Y. enterocolitica strains caused a considerably higher level of secretion of the anti-inflammatory cytokine IL-10 by porcine than by murine macrophages. This could contribute to limiting the severity of the infection (in particular of serotype O:3 strains) in pigs, which are the primary reservoir of Y. enterocolitica strains pathogenic to humans.     

Recurrent deletion of 3p13 targets multiple tumour suppressor genes and defines a distinct subgroup of aggressive ERG fusion‐positive prostate cancers

Deletion of 3p13 has been reported from about 20% of prostate cancers. The clinical significance of this alteration and the tumour suppressor gene(s) driving the deletion remain to be identified. We have mapped the 3p13 deletion locus using SNP array analysis and performed fluorescence in situ hybridization (FISH) analysis to search for associations between 3p13 deletion, prostate cancer phenotype and patient prognosis in a tissue microarray containing more than 3200 prostate cancers. SNP array analysis of 72 prostate cancers revealed a small deletion at 3p13 in 14 (19%) of the tumours, including the putative tumour suppressors FOXP1, RYBP and SHQ1. FISH analysis using FOXP1‐specific probes revealed deletions in 16.5% and translocations in 1.2% of 1828 interpretable cancers. 3p13 deletions were linked to adverse features of prostate cancer, including advanced stage (p < 0.0001), high Gleason grade (p = 0.0125), and early PSA recurrence (p = 0.0015). In addition, 3p13 deletions were linked to ERG⁺ cancers and to PTEN deletions (p < 0.0001 each). A subset analysis of ERG⁺ tumours revealed that 3p13 deletions occurred independently from PTEN deletions (p = 0.3126), identifying tumours with 3p13 deletion as a distinct molecular subset of ERG⁺ cancers. mRNA expression analysis confirmed that all 3p13 genes were down regulated by the deletion. Ectopic over‐expression of FOXP1, RYBP and SHQ1 resulted in decreased colony‐formation capabilities, corroborating a tumour suppressor function for all three genes. In summary, our data show that deletion of 3p13 defines a distinct and aggressive molecular subset of ERG⁺ prostate cancers, which is possibly driven by inactivation of multiple tumour suppressors. Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

No relevant effect of ursodeoxycholic acid on cytochrome P450 3A metabolism in primary biliary cirrhosis

Induction of cytochrome P450 3A (CYP3A) has been suggested as a mechanism of action of ursodeoxycholic acid (UDCA) in cholestasis. CYP3A is of key importance in human drug metabolism, being involved in presystemic extraction of more than 50% of all drugs currently available and of various endogenous compounds. Therefore, we compared the induction potential of UDCA with that of the prototypical inducer rifampicin in a human model study with the CYP3A substrates budesonide and cortisol. Twelve patients with early-stage primary biliary cirrhosis and eight healthy volunteers were treated with UDCA (15 mg/kg daily) for 3 weeks and subsequently with rifampicin (600 mg/d) for 1 week. Extensive pharmacokinetic profiling of oral budesonide (3 mg) was performed by determination of budesonide and phase I metabolites (6beta-hydroxybudesonide, 16alpha-hydroxyprednisolone) in plasma and urine at baseline and at the end of each treatment. In parallel, urinary 6beta-hydroxycortisol, a validated marker of CYP3A induction, was determined. UDCA did not affect biotransformation of budesonide and urinary excretion of 6beta-hydroxycortisol either in patients or in healthy volunteers. Ratios of areas under plasma concentration-time curves (AUC(0-12 h) during UDCA/AUC(0-12 h) before UDCA) of both metabolites were not higher than those of budesonide itself. In contrast, administration of rifampicin markedly induced CYP3A metabolism, resulting in abolished budesonide plasma levels and high urinary excretion of 6beta-hydroxycortisol. Metabolite formation was enhanced by rifampicin, but not by UDCA (e.g., AUC(16alpha-hydroxyprednisolone)/AUC(budesonide) in patients: baseline, 8.6 +/- 3.9; UDCA, 10.7 +/- 7.1; rifampicin, 527.0 +/- 248.7). In conclusion, UDCA is not a relevant inducer of CYP3A enzymes in humans.     

Mutation of POC1B in a Severe Syndromic Retinal Ciliopathy

We describe a consanguineous Iraqi family with Leber congenital amaurosis (LCA), Joubert syndrome (JBTS), and polycystic kidney disease (PKD). Targeted next‐generation sequencing for excluding mutations in known LCA and JBTS genes, homozygosity mapping, and whole‐exome sequencing identified a homozygous missense variant, c.317G>C (p.Arg106Pro), in POC1B, a gene essential for ciliogenesis, basal body, and centrosome integrity. In silico modeling suggested a requirement of p.Arg106 for the formation of the third WD40 repeat and a protein interaction interface. In human and mouse retina, POC1B localized to the basal body and centriole adjacent to the connecting cilium of photoreceptors and in synapses of the outer plexiform layer. Knockdown of Poc1b in zebrafish caused cystic kidneys and retinal degeneration with shortened and reduced photoreceptor connecting cilia, compatible with the human syndromic ciliopathy. A recent study describes homozygosity for p.Arg106Pro_POC1B in a family with nonsyndromic cone‐rod dystrophy. The phenotype associated with homozygous p.Arg106Pro_POC1B may thus be highly variable, analogous to homozygous p.Leu710Ser in WDR19 causing either isolated retinitis pigmentosa or Jeune syndrome. Our study indicates that POC1B is required for retinal integrity, and we propose POC1B mutations as a probable cause for JBTS with severe PKD.