Permanent atrial fibrillation ablation surgery in patients with advanced age

Background: Even if permanent atrial fibrillation (pAF) is a frequent concomitant problem in patients undergoing open heart surgery and particularly in those with advanced age, data of pAF ablation surgery in older aged patients are scarce. This study was performed to assess early and late results of combined open heart surgery and pAF ablation procedures in patients with advanced aged, compared to young patients. Material and Methods: A selective group of 126 patients (Group A: age ≥70 [76.4±4.8] years, n=70; Group B: age <70 [62.0±6.2] years: n=56) with pAF (≥6 months) underwent either monopolar (Group A, B: n=51 vs. n=44) or bipolar (Group A, B: n=19 vs. n=12) radiofrequency (RF) ablation procedures concomitant to open heart surgery. Regular follow-up was performed 3 to 36 months after surgery to assess survival, New York Heart Association (NYHA) class and conversion rate to stable sinus rhythm (SR). Results: Early mortality (<30 days) was 2.9% in Group A (Group B: 0%), cumulative survival at long-term follow up was 0.78 vs. 0.98 (p=0.03) and NYHA-class improved significantly in both groups, particularly in cases with stable SR. At 12-months follow-up 73% of Group A patients were in stable SR (Group B 78%). Conclusions: Concomitant mono- and bipolar RF ablation surgery represents a safe option to cure pAF during open heart surgery with a very low risk, even in patients with advanced age

A Massively Parallel Algorithm for the Approximate Calculation of Inverse p-th Roots of Large Sparse Matrices

We present the submatrix method, a highly parallelizable method for the approximate calculation of inverse p-th roots of large sparse symmetric matrices which are required in different scientific applications. We follow the idea of Approximate Computing, allowing imprecision in the final result in order to be able to utilize the sparsity of the input matrix and to allow massively parallel execution. For an n x n matrix, the proposed algorithm allows to distribute the calculations over n nodes with only little communication overhead. The approximate result matrix exhibits the same sparsity pattern as the input matrix, allowing for efficient reuse of allocated data structures. We evaluate the algorithm with respect to the error that it introduces into calculated results, as well as its performance and scalability. We demonstrate that the error is relatively limited for well-conditioned matrices and that results are still valuable for error-resilient applications like preconditioning even for ill-conditioned matrices. We discuss the execution time and scaling of the algorithm on a theoretical level and present a distributed implementation of the algorithm using MPI and OpenMP. We demonstrate the scalability of this implementation by running it on a high-performance compute cluster comprised of 1024 CPU cores, showing a speedup of 665x compared to single-threaded execution

Biological Functions of RBP4 and Its Relevance for Human Diseases

Retinol binding protein 4 (RBP4) is a member of the lipocalin family and the major transport protein of the hydrophobic molecule retinol, also known as vitamin A, in the circulation. Expression of RBP4 is highest in the liver, where most of the body's vitamin A reserves are stored as retinyl esters. For the mobilization of vitamin A from the liver, retinyl esters are hydrolyzed to retinol, which then binds to RBP4 in the hepatocyte. After associating with transthyretin (TTR), the retinol/RBP4/TTR complex is released into the bloodstream and delivers retinol to tissues via binding to specific membrane receptors. So far, two distinct RBP4 receptors have been identified that mediate the uptake of retinol across the cell membrane and, under specific conditions, bi-directional retinol transport. Although most of RBP4's actions depend on its role in retinoid homeostasis, functions independent of retinol transport have been described. In this review, we summarize and discuss the recent findings on the structure, regulation, and functions of RBP4 and lay out the biological relevance of this lipocalin for human diseases

Memory control ability modulates intrusive memories after analogue trauma

AbstractBackgroundMost people suffer from intrusive memories in the aftermath of trauma. For survivors' well-being, it is key that these intrusions are controlled. Memory control can be exerted through retrieval suppression. Poor retrieval suppression, however, should be associated with persistent distressing intrusions and posttraumatic stress disorder (PTSD). This study tested the hypothesis that individual differences in retrieval suppression predict intrusive memories after trauma. Retrieval suppression was examined with the think/no-think task (TNT) using behavioral and event related potential (ERP) measures.MethodsTwenty-four healthy participants watched a “traumatic” film after performing the TNT task. The frequency and distress of intrusions from the “traumatic” film was measured with an electronic diary. Additionally the Impact of Event Scale (IES) was assessed.ResultsIn line with our hypothesis, behavioral measures of retrieval suppression ability predicted reduced distress ratings for intrusions (r=−.53, p<.01). Further ERP markers of retrieval suppression (a fronto-centrally distributed N2) predicted reduced distress ratings for intrusions (r=−.45, p<.05) and reduced IES Intrusion scores (r=−.56, p<.01).LimitationsThe presented film is a relatively mild stressor as compared to a real-life trauma. Further studies are needed to explore the role of memory control processes for real-life trauma.ConclusionsParticipants with lower retrieval suppression ability exhibited less distressing intrusive memories after analogue trauma. The ERP correlate of retrieval suppression was associated with less distressing intrusive memories and reduced IES Intrusion scores, suggesting that deficient memory control is a potential risk factor for developing PTSD

Research vessel Meteor, cruise no. 48 : 6 July - 3 November 2000

Die fünf Abschnitte der Meteor-Reise 48 führen in die Zone der Ostrandzirkulation des Südost-Atlantiks und verknüpfen ozeanografische, biologische, geologische und chemische Arbeiten im Bereich des Auftriebsgebietes vor der südwest-afrikanischen Küste sowie im Pelagial des Angolabeckens und des Kapbeckens. Die Arbeiten konzentrieren sich auf · die Biodiversität von Benthosgemeinschaften in Tiefseebecken, · biogeochemische Stoffkreisläufe und kurzskalige holozäne Klimavariationen im Auftriebsgebiet vor Namibia, · die Dynamik des Angola Domes und des Benguelastromes und die Entstehung des Südäquatorialen Gegenstroms im Atlantik, · die Verteilungen von Spurenelementen und natürlichen Radionukliden im Auftriebsgebiet vor Namibia, · den Einfluss mesoskaliger physikalischer Strukturen und Prozesse auf die Produktion des Zooplanktons im nördlichen Benguela-Auftriebssystem.The five legs of Meteor cruise 48 lead into the eastern boundary circulation of the south-eastern Atlantic, combining oceanographical, biological, geological, and chemical work in the upwelling area off the coast of Namibia and the pelagic region of the Angola and the Cape basin. Studies focus on · biodiversity of the benthos community in deep sea basins, · biogeochemical cycles and short-scale holocene climate variations in the Namibia upwelling region, · dynamics of the Angola dome and the Benguela current, and the formation of the southequatorial contercurrent in the Atlantic, · distributions of (essential) trace elements and natural radionuclides in the Namibia upwelling region · the influence of mesoscale physical structures/processes on the production of zooplankton in the northern Benguela upwelling system