A repolarizációs rezerv csökkenésére és a kamrai repolarizáció adaptációs zavaraira visszavezethető proarrhytmiás mechanizmusok elemzése klinikai körülmények között és emlős szívizomban = Analysis of proarrhythmic mechanisms based on decreased repolarization reserve and disturbed adaptation of cardiac ventricular repolarization under clinical circumstances and in mammalian hearts

Munkánk célja a kamrai repolarizáció - csökkent repolarizációs rezerv okozta - adaptációs zavarainak vizsgálata volt kísérletes és klinikai körülmények között. Diabeteses kutyákban a repolarizációs rezerv az IKs és az Ito áram csökkenése következtében beszűkült. Az elektrofiziológiai eltéréseket az érintett csatornaproteinek elemzése is alátámasztotta. Diabeteses nyulakban az IKs áram hasonló mértékű csökkenését tapasztaltuk. Acut torsade-modellünkben az IKs áram farmakológiai gátlása fogékonnyá tette a kamrai szívizomzatot az IKr-blokkoló gyógyszerek okozta Torsade de Pointes tachycardia kialakulására. Ezekben az esetekben a QT-szakasz megnövekedett időbeli, beat-to-beat variabilitása (QTV) - a csökkent repolarizációs rezerv indikátoraként - a proarrhythmiás események jó előrejelzőjének bizonyult. A QTV cukorbetegekben és szívelégtelenségben egyaránt megemelkedett. Szívelégtelenségben igazoltuk, hogy a QTV a kamrai tachycardiák fellépésének erős prediktora. Munkánk eredményei hozzájárulhatnak a diabetes mellitusban fellépő proarrhythmiás mechanismusok elektrofiziológiai hátterének feltárásához. Acut torsade-modellünk lehetőséget nyújt azoknak a gyógyszereknek a kiszűrésére, amelyek csökkent repolarizációs rezerv mellett potenciálisan veszélyes proarrhythmiás hatással rendelkeznek. Munkánk során igazolódott, hogy a QT-szakasz időbeli variabilitásának megnövekedése különböző kórállapotokban már korai időszakban jelezheti a kamrai repolarizáció instabilitásának fokozódását. | The aim of the project was to characterize the adaptive disturbances of ventricular repolarization caused by decreased repolarization reserve in experimental and clinical circumstances. Repolarization reserve was attenuated by reduction in the density of IKs and Ito currents in diabetic dogs. The analysis of the affected channel proteins supported the observed electrophysiological changes. The IKs current was decreased by similar extent in diabetic rabbits. In our acute experimental torsade model, the pharmacological blockade of the IKs current made vulnerable the ventricular myocardium for the IKr-blocking agents induced Torsades de Pointes tachycardia. In these cases the increased temporal beat-to-beat QT variability (QTV) as an indicator of the decreased repolarization reserve was proven as a good predictor of the subsequent proarrhythmia. In patients with diabetes mellitus or congestive heart failure enhanced QTV was observed. QTV was confirmed as a strong predictor of ventricular tachycardias in heart failure. This project may help us to explain the electrophysiologic background of proarrhythmic mechanisms in diabetes mellitus. Our acut torsade model can provide an appropriate tool to screen the potentially dangerous drugs with high proarrhythmic activity in case of attenuated repolarization reserve. Furthermore, the enhanced temporal QTV may be an early indicator of the increased instability of cardiac repolarization in different pathophysiological conditions

Catalytic Co-Processing of delayed coker light naphtha with other refinery gasoline streams

Upgrading of delayed coker light naphtha is very difficult due to its high diolefin and silicon content. Mixtures of light straight run naphtha and delayed coker light naphtha fractions were hydrotreated in two stages over NiMo/Al2O and CoMo/Al2O catalysts (diolefin saturation followed by hydrodesulphurization ). The results showed that naphtha fractions free of diolefins, olefins, sulphur and silicon can be produced with the two stage hydrogenation. These are excellent feeds for naphtha isomerization. One-stage selective hydrodesulphurization tests were also conducted with blends of coker naphtha (up to 5 vol%) and fluid catalytic crackers gasoline over CoMo/Al2O. Diolefin-free products of < 10 mg/kg sulphur could be produced with a research octane number loss of max. 3

Complex Relationship of Left Ventricular Rotational Mechanics and Deformation Represented by Strain Parameters in Healthy Adults—Detailed Analysis from the Three-Dimensional Speckle-Tracking Echocardiographic MAGYAR-Healthy Study

Introduction: Left ventricular (LV) strains are measures of deformation that reflect LV function quantifying the rate of LV contraction, providing information in three directions in space: radial (RS), longitudinal (LS) and circumferential directions (CS). The LV moves around its longitudinal axis in a special movement called LV rotational mechanics. The present study aimed to assess associations between three-dimensional speckle-tracking echocardiography (3DSTE)-derived LV rotational mechanics and LV strains in healthy adult subjects. Methods: The present study consisted of 174 healthy adults (mean age: 32.8 ± 12.2 years, 79 males). Complete two-dimensional Doppler echocardiography and 3DSTE were performed in all subjects. Results: While LV-gRS and LV-gLS did not show associations with increased basal LV rotation, the lowest LV-gCS was seen in the presence of the highest LV basal rotation. An increase in basal LV rotation and consequential LV twist were not associated with apical LV rotation. While LV-gLS was not associated with the increase in apical LV rotation, LV-gRS and LV-gCS showed a trend towards increasing values. An increase in LV-gRS was associated with an increasing trend towards apical LV rotation, LV twist and LV-gCS and the preservation of basal LV rotation. LV-gLS also increased but only up to a certain value. An increase in LV-gCS was associated with a tendency towards a decrease in basal LV rotation and a tendency towards an increase in LV-gRS and LV-gLS. The highest LV-gCS was associated with the highest apical LV rotation and LV twist. The highest apical LV rotation, LV twist and LV-gCS were seen in the presence of the highest LV-gLS, while basal LV rotation and LV-gRS were not associated with increasing LV-gLS. Conclusions: Basal LV rotation has been shown to have an inverse relationship with LV-gCS, but without being related to LV-gRS and LV-gLS, while apical LV rotation is associated with LV strains in all directions, but to a different extent, suggesting a complex relationship between LV rotational mechanics and LV strains in healthy adults

Similarities and Differences between Three-Dimensional Speckle-Tracking Echocardiography-Derived Left and Right Atrial Volumes and Volume-Based Functional Properties in the Same Healthy Adults—A Detailed Analysis from the MAGYAR-Healthy Study

Background and Objectives: It would be important to know what happens to the volume and volume-based functional properties of one atrium if the size of the other atrium is larger or smaller than the average. Therefore, the present study aimed to perform three-dimensional speckle-tracking echocardiography (3DSTE)-derived quantification of left atrial (LA) and right atrial (RA) volumes and volume-based functional properties to examine these associations in healthy adults with mean and lower or higher than mean atrial volumes. Materials and Methods: The present study consisted of 179 healthy volunteers with a mean age of 32.3 ± 12.3 years (92 males). Three-dimensional speckle-tracking echocardiography-derived LA and RA volumes and volume-based functional properties were determined in all cases. Results: When different LA or RA volume groups were evaluated, both LA and RA showed the same pattern of volume changes in all phases of atrial function with higher LA or RA volumes. In case of low and mean LA volumes, RA volumes were higher compared to their LA counterpart. In case of mean and high RA volumes, RA volumes proved to be higher as well. In case of mean LA or RA volumes, differences between LA and RA stroke volumes (SVs) could not be detected, but all atrial emptying fractions (EFs) were lower for RA than for LA. Some differences were detected in counterpart LA/RA total, passive, and active atrial SVs and EFs values in the presence of lower/higher than mean LA/RA volume. Conclusions: In case of mean LA or RA volumes, RA volumes are higher compared to their LA counterpart, LA-SVs and RA-SVs are similar, but atrial EFs are lower for RA than for LA. If lower/higher than mean LA or RA volumes are present, some differences in patterns of changes in counterpart atrial volumes—SVs and EFs—could be detected