Electronic and Structural Properties of a 4d-Perovskite: Cubic Phase of SrZrO3_3

First-principles density functional calculations are performed within the local density approximation to study the electronic properties of SrZrO$_3$, an insulating 4d-perovskite, in its high-temperature cubic phase, above 1400 K, as well as the generic 3d-perovskite SrTiO$_3$, which is also a d^0-insulator and cubic above 105 K, for comparison reasons. The energy bands, density of states and charge density distributions are obtained and a detailed comparison between their band structures is presented. The results are discussed also in terms of the existing data in the literature for both oxides.Comment: 5 pages, 2 figure

Circulating KCNH2 Current-Activating Factor in Patients with Heart Failure and Ventricular Tachyarrhythmia

It is estimated that approximately half of the deaths in patients with HF are sudden and that the most likely causes of sudden death are lethal ventricular tachyarrhythmias such as ventricular tachycardia (VT) or fibrillation (VF). However, the precise mechanism of ventricular tachyarrhythmias remains unknown. The KCNH2 channel conducting the delayed rectifier K(+) current (I(Kr)) is recognized as the most susceptible channel in acquired long QT syndrome. Recent findings have revealed that not only suppression but also enhancement of I(Kr) increase vulnerability to major arrhythmic events, as seen in short QT syndrome. Therefore, we investigated the existence of a circulating KCNH2 current-modifying factor in patients with HF.We examined the effects of serum of HF patients on recombinant I(Kr) recorded from HEK 293 cells stably expressing KCNH2 by using the whole-cell patch-clamp technique. Study subjects were 14 patients with non-ischemic HF and 6 normal controls. Seven patients had a history of documented ventricular tachyarrhythmias (VT: 7 and VF: 1). Overnight treatment with 2% serum obtained from HF patients with ventricular arrhythmia resulted in a significant enhancement in the peaks of I(Kr) tail currents compared to the serum from normal controls and HF patients without ventricular arrhythmia.Here we provide the first evidence for the presence of a circulating KCNH2 channel activator in patients with HF and ventricular tachyarrhythmias. This factor may be responsible for arhythmogenesis in patients with HF

Acute Effects of Sex Steroid Hormones on Susceptibility to Cardiac Arrhythmias: A Simulation Study

Acute effects of sex steroid hormones likely contribute to the observation that post-pubescent males have shorter QT intervals than females. However, the specific role for hormones in modulating cardiac electrophysiological parameters and arrhythmia vulnerability is unclear. Here we use a computational modeling approach to incorporate experimentally measured effects of physiological concentrations of testosterone, estrogen and progesterone on cardiac ion channel targets. We then study the hormone effects on ventricular cell and tissue dynamics comprised of Faber-Rudy computational models. The “female” model predicts changes in action potential duration (APD) at different stages of the menstrual cycle that are consistent with clinically observed QT interval fluctuations. The “male” model predicts shortening of APD and QT interval at physiological testosterone concentrations. The model suggests increased susceptibility to drug-induced arrhythmia when estradiol levels are high, while testosterone and progesterone are apparently protective. Simulations predict the effects of sex steroid hormones on clinically observed QT intervals and reveal mechanisms of estrogen-mediated susceptibility to prolongation of QT interval. The simulations also indicate that acute effects of estrogen are not alone sufficient to cause arrhythmia triggers and explain the increased risk of females to Torsades de Pointes. Our results suggest that acute effects of sex steroid hormones on cardiac ion channels are sufficient to account for some aspects of gender specific susceptibility to long-QT linked arrhythmias

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Περιέχει την περίληψηΜέσα στα πλαίσια της Κοινωνίας της Πληροφορίας οι βιβλιοθηκονόμοι διεκδικούν, άλλοτε πετυχημένα, άλλοτε όχι και τόσο, ένα πιο ενεργό και απαιτητικό ρόλο, προβάλλοντας το επιχείρημα πώς όσο μεγαλύτερη είναι η παραγωγή πληροφορίας και γνώσης και η παροχή πληροφόρησης τόσο mo απαιτητική είναι και η διαδικασία που αναγκάζεται να ακολουθήσει ο χρήστης ώστε να ικανοποιήσει τις ανάγκες του. Αλλά, η αναγκαιότητα του βιβλιοθηκονόμου (ως επιστήμονα της πληροφόρησης πλέον), του διαμεσολαβητή, δηλαδή, ανάμεσα στην πληροφορία και στον χρήστη, δικαιολογεί απαραιτήτως και την αναγκαιότητα για την ίδια τη Βιβλιοθήκη; Τεκμηριώνεται, δηλαδή, η ύπαρξη αυτού του οργανισμού ως μη κερδοσκοπικού, πολιτιστικού ιδρύματος που εξυπηρετεί όχι μόνο πληροφοριακές αλλά και ψυχαγωγικές, εκπαιδευτικές, κοινωνικοοικονομικές ανάγκες των επισκεπτών του; Και τότε, το έργο του βιβλιοθηκονόμου πώς προδιαγράφεται; Ποιο το περιεχόμενο και ο τρόπος της διαμεσολάβησης; Πρόκειται για σύνθεση ή μηχανιστική διάδοση της πληροφορίας; Αν η Πληροφορία διακινείται, στις μέρες μας κυρίως και πρωτίστως, με ηλεκτρονικά μέσα, τότε το αυτονόητο της ύπαρξης ενός απτού οικοδομήματος που στεγάζει την πληροφορία παύει να ισχύει και είτε πρέπει να καταλυθεί, είτε να εφευρεθεί από την αρχή, προσδίδοντας νέα επίκαιρα χαρακτηριστικά σε ένα αρχαιότατο κατασκεύασμα

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead