Abstract The human pathogen Mycobacterium tuberculosis is the causative agent of tuberculosis resulting in over 1 million fatalities every year, despite decades of research into the development of new anti-TB compounds. Unlike most other organisms M. tuberculosis has six putative genes for epoxide hydrolases (EH) of the α/β-hydrolase family with little known about their individual substrates, suggesting functional significance for these genes to the organism. Due to their role in detoxification, M. tuberculosis EH’s have been identified as potential drug targets. Here, we demonstrate epoxide hydrolase activity of M. thermoresistibile epoxide hydrolase A (Mth-EphA) and report its crystal structure in complex with the inhibitor 1,3-diphenylurea at 2.0 Å resolution. Mth-EphA displays high sequence similarity to its orthologue from M. tuberculosis and generally high structural similarity to α/β-hydrolase EHs. The structure of the inhibitor bound complex reveals the geometry of the catalytic residues and the conformation of the inhibitor. Comparison to other EHs from mycobacteria allows insight into the active site plasticity with respect to substrate specificity. We speculate that mycobacterial EHs may have a narrow substrate specificity providing a potential explanation for the genetic repertoire of epoxide hydrolase genes in M. tuberculosis.
Ausgangslage: Das Universitats-Spital Zurich bietet seit 1999 eine E-mail-basierte Onlineberatung fur medizinische Laien an. Die Nutzer konnen Telearzten anonym Fragen aus allen Bereichen der Medizin stellen. Der Fokus dieser Studie liegt auf der Evaluation der Anfragen zu arterieller Hypertonie, der Charakterisierung der Nutzer, der bereitgestellten Antworten und der Beratungsqualitat der Dienstleistung. Methode: Die retrospektive Studie schloss 39.091 Anfragen im Zeitraum von August 1999 bis Oktober 2013 ein, wovon mit Hilfe von ICD-10-Codes 197 Anfragen (0,5 %) zum Thema arterielle Hypertonie identifiziert wurden. Ein qualitativer Methodenansatz, beschrieben nach Mayring, wurde mit Hilfe des Textanalysesystems MAXQDA (VERBI Software, Berlin, Germany) durchgefuhrt. Der inhaltsanalytischen Textauswertung mit induktiver Kategorienbildung folgte eine quantitative Auswertung mit Erfassung von Haufigkeiten. Ergebnisse: Zu Medikamenten, Therapien und deren Nebenwirkungen wurde in 17 %, sowie nach Empfehlungen zum weiteren Vorgehen in 26 % gefragt. Ein oder mehrere Medikamente nahmen 72 % der Fragesteller ein, wovon 58 % der eingenommenen Medikamente aus dem Bereich der kardiovaskularen Medikation stammten. Die Telearzte gaben in 49 % Auskunft zu den genannten Medikamenten bzw. den pharmakologischen Therapien. Informationen zu Blutdruck- oder Pulswerten sowie zu deren Grenzwerten waren in 13 % die Intention der Anfrage und in 9 % wurde nach Informationen zu Lebensstilanderungen gefragt. Die Fragesteller erhielten in 50 % eine individuelle Beratung zu konkreten Blutdruckwerten und in 46 % Empfehlungen zu Lebensstilanderungen mit Fokus auf die kardiovaskularen Risikofaktoren. In 18 % wurden Fragen zur Schwangerschaftshypertonie gestellt. Die Verstandlichkeit, Hilfestellung und Erwartungen wurden in mehr als 82 % mit gut bis sehr gut bewertet. Schlussfolgerung: Die Teleberatung zur arteriellen Hypertonie erfordert von den beratenden Telearzten ein breites Fachwissen insbesondere zu Fragestellungen uber kardiovaskulare Erkrankungen, der Mehrfachmedikation als auch zu speziellen Fragestellungen wie der Schwangerschaftshypertonie.
The University Hospital Zurich offers an e-mail-based online consultation service for medical laymen since 1999. Questions in all fields of medicine are asked anonymously to a teledoctor. This study focuses on the evaluation of arterial hypertension-related requests, the characterization of users, the answers provided and the quality of advice given. Method: This retrospective study includes 39`091 requests in the period from August 1999 to October 2013. Of these, 197 requests (0.5%) were identified on the basis of hypertension-related health issues, as coded by ICD-10. A qualitative approach, described by Mayring, was supported by a professional text analysis program MAXQDA (VERBI Software, Berlin, Germany). The content analysis of the requests with inductive category development was followed by a quantitative analysis Results: Requests about medication, treatment or side effects were asked in 17% and about recommendations on how to proceed in 26%. Most enquirers (72%) took one or more drugs, whereof 58% were cardiovascular medication. The teledoctors gave in 49% information about medication or treatment. Information on specific blood pressure values (13%) and lifestyle modification (9%) were asked. The enquirer received in 50% individual information on specific blood pressure values and in 46% recommendations for lifestyle changes with a focus on cardiovascular risk factors. In 79% arterial hypertension was previously diagnosed. In 18% questions were asked about gestational hypertension. The quality of advice in terms of clarity, support and fulfilled expectations were rated from good to very good in more than 82% of all enquiries. Conclusion: Teleconsultation in arterial hypertension requires a broad expertise from teledoctors, in particular on issues of multiple medications, cardiovascular risk factors as well as on specific issues such as pregnancy-induced hypertension. An email-based teleconsultation is a non-verbal form of communication with high demands in often complex medical contexts.
The major virulence factor of the neuroinvasive pathogen Escherichia coli K1 is the K1 capsule composed of α2,8-linked polysialic acid (polySia). K1 strains harboring the CUS-3 prophage modify their capsular polysaccharide by phase-variable O-acetlyation, a step that is associated with increased virulence. Here we present the crystal structure of the prophage-encoded polysialate O-acetyltransferase NeuO. The homotrimeric enzyme belongs to the left-handed β-helix (LβH) family of acyltransferases and is characterized by an unusual funnel-shaped outline. Comparison with other members of the LβH family allowed the identification of active site residues and proposal of a catalytic mechanism and highlighted structural characteristics of polySia specific O-acetyltransferases. As a unique feature of NeuO, the enzymatic activity linearly increases with the length of the N-terminal poly-ψ-domain which is composed of a variable number of tandem copies of an RLKTQDS heptad. Since the poly-ψ-domain was not resolved in the crystal structure it is assumed to be unfolded in the apo-enyzme.
Entamoeba histolytica enolase (EhENO) reversibly interconverts 2-phosphoglyceric acid (2-PGA) and phosphoenolpyruvic acid (PEP). The crystal structure of the homodimeric EhENO is presented at a resolution of 1.9 Å. In the crystal structure EhENO presents as an asymmetric dimer with one active site in the open conformation and the other active site in the closed conformation. Interestingly, both active sites contain a copurified 2-PGA molecule. While the 2-PGA molecule in the closed active site closely resembles the conformation known from other enolase–2-PGA complexes, the conformation in the open active site is different. Here, 2-PGA is shifted approximately 1.6 Å away from metal ion I, most likely representing a precatalytic situation.
The EMPA-KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population.
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