Restricting excessive cardiac action potential and QT prolongation: a vital role for IKs in human ventricular muscle

Background - Although pharmacological block of the slow, delayed rectifier potassium current (I-Ks) by chromanol 293B, L-735,821, or HMR-1556 produces little effect on action potential duration (APD) in isolated rabbit and dog ventricular myocytes, the effect of IKs block on normal human ventricular muscle APD is not known. Therefore, studies were conducted to elucidate the role of IKs in normal human ventricular muscle and in preparations in which both repolarization reserve was attenuated and sympathetic activation was increased by exogenous dofetilide and adrenaline. Methods and Results - Preparations were obtained from undiseased organ donors. Action potentials were measured in ventricular trabeculae and papillary muscles using conventional microelectrode techniques; membrane currents were measured in ventricular myocytes using voltage-clamp techniques. Chromanol 293B (10 mu mol/L), L-735,821 (100 nmol/L), and HMR-1556 (100 nmol/L and 1 mu mol/L) produced a < 12-ms change in APD while pacing at cycle lengths ranging from 300 to 5000 ms, whereas the I-Kr blockers sotalol and E-4031 markedly lengthened APD. In voltage-clamp experiments, L- 735,821 and chromanol 293B each blocked IKs in the presence of E-4031 to block IKr. The E-4031-sensitive current (I-Kr) at the end of a 150-ms-long test pulse to 30 mV was 32.9 +/- 6.7 pA (n = 8); the L-735,821-sensitive current (I-Ks) magnitude was 17.8 +/- 2.94 pA (n = 10). During a longer 500-ms test pulse, IKr was not substantially changed (33.6 +/- 6.1 pA; n = 8), and I-Ks was significantly increased (49.6 +/- 7.24 pA; n = 10). On application of an "action potential-like" test pulse, I-Kr increased as voltage became more negative, whereas I-Ks remained small throughout all phases of the action potential - like test pulse. In experiments in which APD was first lengthened by 50 nmol/L dofetilide and sympathetic activation was increased by 1 mu mol/L adrenaline, 1 mu mol/L HMR-1556 significantly increased APD by 14.7 +/- 3.2% (P < 0.05; n = 3). Conclusions - Pharmacological IKs block in the absence of sympathetic stimulation plays little role in increasing normal human ventricular muscle APD. However, when human ventricular muscle repolarization reserve is attenuated, IKs plays an increasingly important role in limiting action potential prolongation

Diclofenac Prolongs Repolarization in Ventricular Muscle with Impaired Repolarization Reserve

Background: The aim of the present work was to characterize the electrophysiological effects of the non-steroidal anti- inflammatory drug diclofenac and to study the possible proarrhythmic potency of the drug in ventricular muscle. Methods: Ion currents were recorded using voltage clamp technique in canine single ventricular cells and action potentials were obtained from canine ventricular preparations using microelectrodes. The proarrhythmic potency of the drug was investigated in an anaesthetized rabbit proarrhythmia model. Results: Action potentials were slightly lengthened in ventricular muscle but were shortened in Purkinje fibers by diclofenac (20 mM). The maximum upstroke velocity was decreased in both preparations. Larger repolarization prolongation was observed when repolarization reserve was impaired by previous BaCl 2 application. Diclofenac (3 mg/kg) did not prolong while dofetilide (25 mg/kg) significantly lengthened the QT c interval in anaesthetized rabbits. The addition of diclofenac following reduction of repolarization reserve by dofetilide further prolonged QT c . Diclofenac alone did not induce Torsades de Pointes ventricular tachycardia (TdP) while TdP incidence following dofetilide was 20%. However, the combination of diclofenac and dofetilide significantly increased TdP incidence (62%). In single ventricular cells diclofenac (30 mM) decreased the amplitude of rapid (I Kr ) and slow (I Ks ) delayed rectifier currents thereby attenuating repolarization reserve. L-type calcium current (I Ca ) was slightly diminished, but the transient outward (I to ) and inward rectifier (I K1 ) potassium currents were not influenced. Conclusions: Diclofenac at therapeutic concentrations and even at high dose does not prolong repolarization markedly and does not increase the risk of arrhythmia in normal heart. However, high dose diclofenac treatment may lengthen repolarization and enhance proarrhythmic risk in hearts with reduced repolarization reserve

Allogén vérképzőőssejt-átültetés Magyarországon

INTRODUCTION AND AIM: The publication summarizes the 2548 stem cell transplantations performed in the period of 1993-2015 in Szent Laszlo Hospital, Budapest and provides a detailed discussion of the 425 allogeneic transplantations during 2007-2013. METHOD: The analysis explains the major steps of the evolution of allogeneic stem cell transplantation and compares the results of the unique Hungarian allogeneic center. RESULTS: The significant shift in the transplantation indications from chronic myeloid leukemia to myelodysplastic syndromes and the rising age of the recipients are in line with world wide tendencies. The latter one is the consequence of the introduction and improvement of the concept of reduced intensity conditioning regimens, originally arising from the idea of Endre Kelemen. The most limiting factor, the donor availability seems to be resolved with the use of a new immunomodulating regimen, the application of posttransplantation cyclophosphamide, which allows the transplantation through HLA barriers with haploidentical family donors with comparable results to the HLA matched volunteer unrelated donors. The above mentioned tendencies result the wider use of allogeneic stem cell transplantation less dependent from recipient age, comorbidities and even donor availability. CONCLUSIONS: The publication highlights the need of expanding the stem cell transplantation budget and the involvement of new centers in Hungary in allogeneic of stem cell transplantation. Orv. Hetil., 2017, 158(8), 291-297

IL28B and IL10R -1087 polymorphisms are protective for chronic genotype 1 HCV infection and predictors of response to interferon-based therapy in an East-Central European cohort.

BACKGROUND: Previous studies have shown that single nucleotide polymorphisms (SNP) in IL28B and IL10R are associated with sustained virological response (SVR) in chronic hepatitis C patients treated with pegilated interferon plus ribavirin (P/R). The present study extends our earlier investigations on a large East-Central European cohort. The allele frequencies of IL28B and IL10R in genotype 1 HCV infection were compared with that of healthy controls for the purpose of examining the relationship between the polymorphisms and the SVR to P/R treatment. METHODS: A total of 748 chronic HCV1 infected patients (365 male, 383 female; 18-82 years) and 105 voluntary blood donors as controls were enrolled. Four hundred and twenty HCV patients were treated with P/R for 24-72 weeks, out of them 195 (46.4%) achieved SVR. The IL28 rs12979860 SNP was determined using Custom Taqman SNP Genotyping Assays. The IL10R -1087 (also known as IL10R -1082 (rs1800896) promoter region SNP was determined by RT-PCR and restriction fragment length polymorphism analysis. RESULTS: The IL28B CC genotype occurred with lower frequency in HCV patients than in controls (26.1% vs 51.4%, p<0.001). P/R treated patients with the IL28B CC genotype achieved higher SVR rate, as compared to patients with CT (58.6% vs 40.8%, p=0.002). The prevalence of IL10R -1087 GG genotype was lower in patients than in controls (31.8 % vs 52.2%, p<0.001). Among patients achieving SVR, the IL10R -1087 GG genotype occurred with higher frequency than the AA (32.0% vs 17.4%, p=0.013). The IL28B T allele plus IL10R A allele combination was found with higher prevalence in patients than in controls (52% vs 20.7%, p<0.001). The IL28B CC plus IL10R A allele combination occurred with higher frequency among patients with SVR than in non-responders (21.3% vs 12.8%, p=0.026). Both the IL28B CC plus IL10R GG and the IL28B CC plus IL10R A allele combinations occurred with lower frequency in patients than in controls. CONCLUSIONS: In our HCV1 patients, both the IL28B CC and IL10R GG genotypes are associated with clearance of HCV. Moreover, distinct IL28B and IL10R allele combinations appear to be protective against chronic HCV1 infection and predictors of response to P/R therapy

A késői egyenirányító kálium áram lassú komponensének (Iks) blokkolása, a gyors komponens (Ikr) gátlásával ellentétben, nem nyújtja meg a kamrai repolarizációt nyúlszív preparátumokon

A szerzők két újonnan kifejlesztett antiarrhythmiás vegyület, a késői egyenirányító kálium csatorna lassú komponensét (IKs) blokkoló chromanol 293B és L-735,821 kamrai repolarizációra kifejtett hatását vizsgálták a QT-szakasz, az akciós potenciál időtartam (APD) és a transzmembrán ionáramok elemzésével, izolált nyúlszív preparátumokon. A vizsgált szerek hatékonyságát a késői egyenirányító kálium áram gyors komponensét (IKr) szelektíven gátló E-4031 hatásával vetették össze. Sem a chromanol 293B, sem az L-735,821 nem okozott szignifikáns változást a Langendorffpreparátumokon mért QT(c)-szakasz időtartamában, míg az E-4031 jelentős megnyúlást (~36%) idézett elő. A két I(Ks)-blokkoló vegyület változó ciklushosszú ingerlési frekvencia mellett is csupán kis mértékben növelte az APD-t (<7%). Az E-4031 fordított frekvencia-függő módon, 30-60%-os APD megnyúlást váltott ki. Izolált myocytákon a chromanol 293B jelentősen, az L735,821 teljesen blokkolta az I(Ks), az E-4031 pedig az I(Kr) csatornát. Az I(Ks) áram lassan aktiválódott és gyorsan deaktiválódott, az I(Kr) áram pedig gyorsan aktiválódott és lassan deaktiválódott. Normál körülmények között a nyúl kamrai akciós potenciálja alatt létrejövő áramok számított sűrűsége jelentősen nagyobb volt I(Kr), mint I(Ks) áram esetében. Eredményeink szerint az I(Ks) csatorna szelektív gátlásától nem várható a normál kamraizomzat repolarizációjának számottevő megnyúlására visszavezethető antiarrhythmiás hatás

Osmotic Stress Changes the Expression and Subcellular Localization of the Batten Disease Protein CLN3

<div><p>Juvenile CLN3 disease (formerly known as juvenile neuronal ceroid lipofuscinosis) is a fatal childhood neurodegenerative disorder caused by mutations in the <i>CLN3</i> gene. <i>CLN3</i> encodes a putative lysosomal transmembrane protein with unknown function. Previous cell culture studies using CLN3-overexpressing vectors and/or anti-CLN3 antibodies with questionable specificity have also localized CLN3 in cellular structures other than lysosomes. Osmoregulation of the mouse <i>Cln3</i> mRNA level in kidney cells was recently reported. To clarify the subcellular localization of the CLN3 protein and to investigate if human CLN3 expression and localization is affected by osmotic changes we generated a stably transfected BHK (baby hamster kidney) cell line that expresses a moderate level of myc-tagged human CLN3 under the control of the human ubiquitin C promoter. Hyperosmolarity (800 mOsm), achieved by either NaCl/urea or sucrose, dramatically increased the mRNA and protein levels of CLN3 as determined by quantitative real-time PCR and Western blotting. Under isotonic conditions (300 mOsm), human CLN3 was found in a punctate vesicular pattern surrounding the nucleus with prominent Golgi and lysosomal localizations. CLN3-positive early endosomes, late endosomes and cholesterol/sphingolipid-enriched plasma membrane microdomain caveolae were also observed. Increasing the osmolarity of the culture medium to 800 mOsm extended CLN3 distribution away from the perinuclear region and enhanced the lysosomal localization of CLN3. Our results reveal that CLN3 has multiple subcellular localizations within the cell, which, together with its expression, prominently change following osmotic stress. These data suggest that CLN3 is involved in the response and adaptation to cellular stress.</p></div

Sex-specific survival difference in association with HLA-DRB1 *04 following allogeneic haematopoietic stem cell transplantation for lymphoid malignancies

The role of HLA system in allogeneic haematopoietic stem cell transplantation (allo-HSCT) outcome is unarguable. In this study we investigated association of HLA-A,-B and-DRB1 alleles with overall survival (OS) in 186 patients undergoing allo-HSCT for lymphoid malignancies. Analyses confirmed significantly better OS for HLA-DRB1 *04 carriers compared with non-carriers (p=0.01). Survival benefit was confined to male patients (in multivariate analyses p=0.034, hazard ratio 0.35, 95% confidence interval 0.13-0.92), whereas in females no difference was noted (p=0.82). Furthermore, donor gender also affected outcome and transplantation from female HLA-DRB1 *04 carrier donors resulted in superior survival compared with female non-carrier donors (p=0.01). Combined analyses including recipient/donor gender and HLA-DRB1 *04 showed that survival of male patients varied significantly according to donor gender and HLA-DRB1 *04 carriership (p=0.04) with best survival among HLA-DRB1 *04 carriers transplanted from female donors. Of relevance to our results, HLA-DRB1 *04 has been documented as risk allele group for lymphoid malignancies, and studies described a male-specific risk. We believe that our findings provide further supporting evidence for sex-specific alterations secondary to HLA-DRB1 *04 or related genes. Further studies are warranted to evaluate whether in contrast to general favour of male donors HLA-DRB1 *04 carrier patients with lymphoid malignancies could benefit from transplantation from female donors