Successful revascularization of chronic total occlusion of lower extremity arteries: a wire only and bail out use of re-entry device approach.

AIM: The management of progressive peripheral artery disease experienced a vast change in paradigms over the last decades for the benefit of minimal invasive therapy as a first-line strategy. With the constant development of new devices, materials and dedicated access strategies, more complex lesions can be managed but the limitations to successfully treat chronic total occlusions are still the challenge to re-enter the true lumen. The aim of this retrospective study was to investigate, if a "wire only" strategy leads to an acceptable success rate in a mixed cohort of CTO lesions and to what extend re-entry devices are used. METHODS: We retrospectively analyzed patients treated at the Vascular Center Berlin between 2011 and 2013 with chronic total occlusion out of a prospective conducted database (Endovascular MILestones - EMIL) for demographics, risk factors, co-morbidities, technical success rates, lesion characteristics and use of guidewires as well as re-entry systems. A total of 128 patients with 146 lesions, which represent a subgroup of all the cases performed in our center, following a predefined treatment algorithm for chronic total occlusions (CTOs), have been analyzed. RESULTS: We achieved a technical success in 133 (91.1%) of all cases following a "wire only" strategy. Out of 13 (8.9%) CTOs with technical failure in 7 (53.9%) CTOs a re-entry device (Off-Road®) with a 100% technical success has been used. In 91.1% of chronic total occlusion lesions the use of 2 wires only (88.7%) led to a successful recanalization. A "wire only" strategy followed by the use of a re-entry device as a bail out strategy, led to a total of 140 (96%) lesions to be successfully recanalized. CONCLUSION: In more than 90% of all cases with chronic total occlusion of peripheral lower extremity arteries, endovascular intervention has been successful following a "wire only" strategy. When deciding to use a re-entry device, in case of a failure of a proper wire re-entry at the reconstitution point, a technical success rate of 100% was achieved. Therefore following a strict wire algorithm and considering the use of a re-entry system as a bail out strategy will lead to a successful minimal invasive management of chronic total occlusion in nearly 100% of the cases with TASC II A - D lesions.

No increased risk for contrast-induced nephropathy after multiple CT perfusion studies of the brain with a nonionic, dimeric, iso-osmolal contrast medium.

BACKGROUND AND PURPOSE: Contrast-induced nephropathy (CIN) is one of the most common causes of in-hospital acute renal failure. The aim of this study was to assess the risk for CIN after repeated administration of the nonionic, dimeric, iso-osmolal contrast agent iodixanol regardless of pre-existing renal function. Changes in serum creatinine (SCr) levels were compared with those of control subjects who did not receive iodinated contrast media (CM). MATERIALS AND METHODS: Between January 2005 and March 2007, a total of 100 consecutive patients were prospectively included. Patients underwent a CT perfusion (CTP) study of the brain from clinical signs of acute cerebral infarction. CTP was performed with an intravenous bolus of 60 mL of iodixanol-270. Precontrast and postcontrast SCr levels were obtained, and the CTP study was repeated within 32 hours and postcontrast SCR was assessed. The control group consisted of 100 patients scheduled for plain cranial CT examination, who were not exposed to iodinated CM. RESULTS: Mean baseline SCr level was 0.96 +/- 0.35 mg/dL in the contrast group and 1.14 +/- 0.74 mg/dL in the control group. After repeated administration of CM, a total of 7 patients had a relative increase of greater than or equal to 25% compared with baseline. In the control group, a relative increase of 25% or more was seen in 12 patients. The difference in the incidence of the rise in SCr of >25% was not significantly different (P = .094). CONCLUSION: Multiple contrast-enhanced studies with intravenously administered iodixanol are not associated with a higher risk for CIN compared with a control group receiving no CM.

Identification of the ABC protein SapD as the subunit that confers ATP dependence to the K+-uptake systems Trk(H) and Trk(G) from Escherichia coli K-12.

The activity of the two almost identical K+-uptake systems, Trk(H) and Trk(G), from Escherichia coli K-12 depends completely and partially on the presence of the trkE gene, respectively. trkE maps inside the sapABCDF operon, which encodes an ATP-binding cassette (ABC) transporter of unknown function from the subgroup of peptide-uptake systems. This study was carried out to clarify the role of sapABCDF gene products in the ATP dependence of the E. coli Trk systems. For this purpose DeltasapABCDF DeltatrkG and DeltasapABCDF DeltatrkH strains of E. coli containing plasmids with sap genes from either E. coli or Vibrio alginolyticus were used. All five plasmid-encoded E. coli Sap proteins were made in E. coli mini-cells. The presence of the ATP-binding SapD protein from either E. coli or V. alginolyticus alone was sufficient for stimulating the K+ transport activity of the Trk(H) and Trk(G) systems. K+-uptake experiments with Escherichia coli cells containing SapD variants with changes in the Walker A box Lys-46 residue, the Walker B box Asp-183 residue and the signature motif residues Gly-162 or Gln-165 suggested that adenine nucleotide binding to SapD rather than ATP hydrolysis by this subunit is required for the activity of the E. coli Trk(H) system. K+ transport via two plasmid-encoded Trk systems in a DeltasapABCDF E. coli strain remained dependent on both a high membrane potential and a high cytoplasmic ATP concentration, indicating that in E. coli ATP dependence of Trk activity can be independent of Sap proteins. These data are interpreted to mean that Trk systems can interact with an ABC protein other than SapD.

Identification of OmpT as the protease that hydrolyzes the antimicrobial peptide protamine before it enters growing cells of Escherichia coli.

The influence of extracytoplasmic proteases on the resistance of Escherichia coli to the antimicrobial peptide protamine was investigated by testing strains with deletions in the protease genes degP, ptr, and ompT. Only DeltaompT strains were hypersusceptible to protamine. This effect was abolished by plasmids carrying ompT. Both at low and at high Mg2+ concentrations, ompT+ strains cleared protamine from the medium within a few minutes. By contrast, at high Mg2+ concentrations, protamine remained present for at least 1 h in the medium of an ompT strain. These data indicate that OmpT is the protease that degrades protamine and that it exerts this function at the external face of the outer membrane.

Requirement of a large K+-uptake capacity and of extracytoplasmic protease activity for protamine resistance of Escherichia coli.

The effect of protamine on growing cells of Escherichia coli K-12 strains containing different K+-uptake systems was investigated. Immediately after the addition of the toxic peptide, growth ceased and all strains lost most of their K+. In addition, these cells released a significant amount of their ATP into the medium, and the cytoplasmic volume of these cells decreased by 70%. Whereas cells without rapid K+-uptake systems did not recover, cells containing either the Trk systems or the overproduced Kup system slowly reversed the effects of protamine, and growth resumed after the cells had reached their original volume. Experiments with a set of strains carrying mutations in the K+-uptake gene trkA showed a reasonably satisfactory correlation between inhibition of net K+ uptake and the lag time for resumption of growth after addition of protamine. Cells carrying mutations in three extracytoplasmic proteases were hypersusceptible to protamine, suggesting that the toxic peptide is degraded by these proteases. Data on the effect of a second addition of protamine suggest that protamine degradation activity is inducible. These data are interpreted to mean that reaccumulation of K+ by protamine-treated cells triggers recovery of the cells, thereby allowing induction of extracytoplasmic proteases. These, in turn, degrade protamine, leading to complete recovery of the cells and resumption of growth. Cells that cannot take up K+ rapidly remain metabolically compromised to such an extent that extracytoplasmic protease activity is not induced, leading to a prolonged susceptibility of the cells to the toxic peptide.

TrkH and its homolog, TrkG, determine the specificity and kinetics of cation transport by the Trk system of Escherichia coli.

The corrected sequence of the trkH gene of Escherichia coli predicts that the TrkH protein is a hydrophobic membrane protein of 483 amino acid residues, of which 41% are identical to those of the homologous and functionally analogous TrkG protein. These two proteins form the transmembrane component of the Trk system for the uptake of K+. Each protein alone is sufficient for high-level Trk activity. When Trk is assembled with the TrkG protein, Rb+ and K+ are transported with a Km near or below 1 mM; however, the Vmax for Rb+ is only about 7% of that for K+. When Trk is formed with TrkH, the affinities for both for K+ and Rb+ are somewhat lower, and the Vmax for Rb+ is only 1% of that for K+ transport. The kinetics of transport in strains with wild-type alleles at trkG and at trkH suggest that both products participate in transport.