Elena Ondriasova

Stabilization of calcium release channel (ryanodine receptor) function by FK506-binding protein

FK506-binding protein (FKBP12) was originally identified as the cytosolic receptor for the immunosuppressant drugs FK506 and rapamycin. The cellular function of FKBP12, a ubiquitously expressed 12,000-dalton proline isomerase, has been unknown. FKBP12 copurifies with the 565,000-dalton ryanodine receptor (RyR), four of which form intracellular Ca2+ release channels of the sarcoplasmic and endoplasmic reticula. By coexpressing the RyR and FKBP12 in insect cells, we have demonstrated that FKBP12 modulates channel gating by increasing channels with full conductance levels (by > 400%), decreasing open probability after caffeine activation (from 0.63 +/- 0.09 to 0.04 +/- 0.02), and increasing mean open time (from 4.4 +/- 0.6 ms to 75 +/- 41 ms). FK506 or rapamycin, inhibitors of FKBP12 isomerase activity, reverse these stabilizing effects. These results provide the first natural cellular function for FKBP12, and establish that the functional Ca2+ release channel complex includes FKBP12.

The reaction products of sulfide and S-nitrosoglutathione are potent vasorelaxants.

The chemical interaction of sodium sulfide (Na2S) with the NO-donor S-nitrosoglutathione (GSNO) has been described to generate new reaction products, including polysulfides and nitrosopersulfide (SSNO(-)) via intermediacy of thionitrous acid (HSNO). The aim of the present work was to investigate the vascular effects of the longer-lived products of the Sulfide/GSNO interaction. Here we show that the products of this reaction relax precontracted isolated rings of rat thoracic aorta and mesenteric artery (but to a lesser degree rat uterus) with a >2-fold potency compared with the starting material, GSNO (50 nM), whereas Na2S and polysulfides have little effect at 1-5 µM. The onset of vasorelaxation of the reaction products was 7-10 times faster in aorta and mesenteric arteries compared with GSNO. Relaxation to GSNO (100-500 nM) was blocked by an inhibitor of soluble guanylyl cyclase, ODQ (0.1 and 10 µM), and by the NO scavenger cPTIO (100 µM), but less affected by prior acidification (pH 2-4), and unaffected by N-acetylcysteine (1 mM) or methemoglobin (20 µM heme). By contrast, relaxation to the Sulfide/GSNO reaction products (100-500 nM based on the starting material) was inhibited to a lesser extent by ODQ, only slightly decreased by cPTIO, more markedly inhibited by methemoglobin and N-acetylcysteine, and abolished by acidification before addition to the organ bath. The reaction mixture was found to generate NO as detected by EPR spectroscopy using N-(dithiocarboxy)-N-methyl-D-glucamine (MGD2)-Fe(2+) as spin trap. In conclusion, the Sufide/GSNO reaction products are faster and more pronounced vasorelaxants than GSNO itself. We conclude that in addition to NO formation from SSNO(-), reaction products other than polysulfides may give rise to nitroxyl (HNO) and be involved in the pronounced relaxation induced by the Sulfide/GSNO cross-talk.

Alcohol intoxication requiring hospital admission in children and adolescents: retrospective analysis at the University Children's Hospital in the Slovak Republic

Background. Few epidemiological studies have investigated the problem of children and adolescents taken to hospital with acute alcohol intoxication. Methods. We reviewed the medical records of children and adolescents aged ≤ 18 years hospitalized with alcohol intoxication alone in the University Childrens Hospital in Bratislava, Slovak Republic, during the years 1996–2005 and compared their characteristics between the first and the second 5-year time periods. Results. 537 patients (273 boys and 264 girls) were admitted to the hospital with intentional acute alcohol intoxication (1.5% of all admissions and 34.2% of all intoxications) between 1996 and 2005. The average age of the patients with alcohol intoxication presenting to hospital was 15.1 ± 1.7 and the youngest were 9-year-old children. The proportion of children admitted with alcohol intoxication increased every year (R2 = 0.935) (p < 0.001). The average blood alcohol concentration was 1.98 ± 0.57 g/L, and it increased in 2001–2005 in relation to the previous 5 years (p < 0.001). The highest estimated alcohol concentration (4.39 g/L) was found in the blood of a 17-year-old boy. The mean poisoning severity score was 1.53 ± 0.61 and had increased in line with blood alcohol concentration for the years 2001–2005 (p < 0.001). Conclusions. The results of this analysis emphasize the severity of underage alcohol consumption by young people in the Slovak Republic. Measures are needed to decrease alcohol abuse in children and adolescents.

Perturbation effect of eight calcium channel blockers on liposomal membranes prepared from rat brain total lipids

EPR spectroscopy of phosphatidylcholine or stearic acid labeled at the doxyl group at the 16-carbon position was used to compare the perturbation effect of eight calcium channel blockers (CB) on overall dynamics/disorder of the hydrophobic part of liposome membranes prepared from rat brain total lipids at the drug/lipid molar ratio of 1/2. Nifedipine (NIF), nimodipine, niludipine and nitrendipine had a minor effect on the dynamics/disorder of the liposome membranes, whereas the disordering effect of verapamil (VER), mepamil, gallopamil and diltiazem was more pronounced. Concentration dependence of the overall disordering effect of VER on liposomal membranes was found at the VER/lipid ratio greater than 0.02 and for the tranquilizer thioridazine greater than 0.005. VER exerted a disordering effect at the hydrophobic part of synaptosomal membranes at concentrations greater than or equal to 0.32 mmol/l, whereas NIF did not exhibit a disordering effect even at concentrations of 10-20 mmol/l.

Off-label and unlicensed use of medicinal products in the neonatal setting in the Slovak Republic.

Frequent prescription of medication in an unapproved manner (off‐label or unlicensed) in the neonatal setting is a result of the limited availability of adequately studied drugs in the pediatric population. Given that little information is available on this issue from eastern European countries, the purpose of this study was to describe for the first time the extent and pattern of off‐label or unlicensed use of medicines in newborns in the Slovak Republic.

Retracted: Mathematical relationships and their consequences between rat pulse waveform parameters and blood pressure during decreasing NO bioavailability: Mathematical relationships between rat pulse waveform parameters

What is the central question of this study? We wanted to find out whether the relationship between rat arterial pulse waveform (APW) parameters and blood pressure could be described by known mathematical functions and find mathematical parameters for conditions of hypertension resulting from decreased NO bioavailability. What is the main finding and its importance? We found mathematical functions and their parameters that approximate the relationships of 12 APW parameters to systolic and diastolic blood pressure in conditions of decreased NO bioavailability. The results may assign APW parameters to decreased NO bioavailability, which may have predictive or diagnostic value.

Caustic Ingestion in the Elderly: Influence of Age on Clinical Outcome

Caustic poisonings are still associated with many fatalities. Studies focusing on the elderly are rare. The purpose of the present study was to compare the clinical outcomes of caustic ingestion injury in elderly and non-elderly adults with regard to gender, intent of exposure, substance ingested, severity of mucosal injury, complications, and mortality. Caustic substance exposures reported to the National Toxicological Information Centre in Slovakia during 1998–2015 were reviewed retrospectively. The patients were divided into two groups: the non-elderly (<60 years) and elderly adults (≥60 years). The mortality rate in the elderly was significantly higher (elderly 23.0% vs. non-elderly 11.3%; p = 0.041). The risk of fatal outcome in the elderly was increased by acid ingestion (OR = 7.822; p = 0.002), particularly hydrochloric acid (OR = 5.714, p = 0.006). The incidence of respiratory complications was almost two times higher in the elderly was 31.1% vs. 17.4% for the non-elderly (p = 0.037). Respiratory complications significantly correlated with an increased mortality rate (p = 0.001) in the elderly whereas there was no association between GI complications and mortality in the elderly (p = 0.480). Elderly patients with respiratory complications had the poorest clinical outcomes. The highest risk of complications and fatalities was observed in patients after hydrochloric acid ingestion.

Retraction: ‘Mathematical relationships and their consequences between rat pulse waveform parameters and blood pressure during decreasing NO bioavailability’

The above article from Experimental Physiology, published online on 29 December 2016 in Wiley OnlineLibrary (wileyonlinelibrary.com) and in Volume 102:2, pp. 164–179, has been retracted by agreement between the authors, the journal Editor in Chief, Mike Tipton, and John Wiley & Sons Ltd. The retraction has been agreed because a dosage of anaesthetic was stated incorrectly on page 166, column 2, line 1. The published article reads: ‘Rats were anaesthetized with Zoletil 100 (tiletamine + zolazepam, 40 mg kg−1, I.P.) and Rometar (xylazine, 5 mg kg−1, I.P.)’. In fact, the dosage of the anaesthetic used in the experiment was Zoletil 100 (tiletamine + zolazepam, 120 mg kg−1, I.P.) and Rometar (xylazine, 5 mg kg−1, I.P.). The higher dose of anaesthetic used may have led to cardiovascular depression, compromising the objectives of the experiment. All authors have approved the retraction.

Decomposition of S-nitrosoglutathione by interaction with organic polysulfides and reduced thiols

research in this field is impaired by the lack of pharmacological tools such as selective enzymatic inhibitors [2–4]. The goal of our study is the development of compounds that selectively regulate enzymatic activity. Here we present the synthesis and the activity of a selective CSE inhibitor. We preliminarily selected and tested commercially available cysteine surrogates because of the unavailability of a pharmacophoric model as a lead for rational design of targeted enzyme inhibitors. The catalytic profiles of recombinant CBS and CSE were assessed in the presence of the selected compounds. On the basis of the results obtained were designed new compounds aiming to obtain novel molecular entities embodying the structural features of both cysteine and the well known CSE inhibitor, DL-propargylglycine. The synthetically modified compounds, obtained in our laboratory, were tested in vitro by using rat aortic rings. The compound showing maximal inhibitory effects in this test was an oxothiazolidine derivative, dubbed ‘compound VII’. The effects of this compound on the enzyme kinetics were further tested on the purified enzymes using a metabolomic approach based on nuclear magnetic resonance techniques. These studies clearly showed that ‘compound VII’ is a potent enzyme inhibitor of CSE, without affecting the CBS kinetics. The identification of this highly selective CSE inhibitor may help to better define the role of CSE vs CBS in the pathophysiology of the diseases where a role for the H2S pathway has been proposed.