Peter Der

University of Debrecen, Debreczyn, Hajdú-Bihar, Hungary

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Publications (11)34.56 Total impact

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    ABSTRACT: The aim of our study was to investigate the contribution of the adrenocorticotropic hormone fragment, ACTH (4-10), on the recovery of postischemic cardiac function. Effects of ACTH (4-10) on caspase-3 activity, cardiomyocyte and endothelial apoptosis, and HO-1 protein expression were studied. Rats were treated with various doses of ACTH (4-10), and then 12 h later, anesthetized, hearts were isolated, perfused, and subjected to 30-min ischemia followed by 120-min reperfusion. Cardiac function including heart rate, coronary flow, aortic flow, and left ventricular developed pressure were recorded. After 120-min reperfusion, 200 mug/kg of ACTH (4-10) significantly improved the recovery of aortic flow, coronary flow, and left ventricular developed pressure from their untreated control values of 15.3 +/- 0.9 ml/min, 6.5 +/- 0.9 ml/min, and 10 +/- 0.6 kPa to 20.7 +/- 1.3 ml/min, 24.8 +/- 1.8 ml/min and 13.7 +/- 0.7 kPa, respectively. Heart rate did not show significant changes during reperfusion. ACTH (4-10) treatment resulted in a reduction in infarct size, caspase 3 activity, apoptosis, and an increase in HO-1 expression. When ACTH (4-10) was given at the moment of reperfusion, the drug failed to improve the postischemic recovery of the myocardium. Thus, ACTH (4-10) can be a useful tool for the prevention of the development of ischemia/reperfusion-induced injury.
    Antioxidants and Redox Signaling 12/2007; 9(11):1851-61. · 7.19 Impact Factor
  • Journal of Molecular and Cellular Cardiology - J MOL CELL CARDIOL. 01/2007; 42(6).
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    ABSTRACT: Fox nut or gorgon nut (Euryale ferox--Family Nymphaeaceae), popularly known as Makhana, has been widely used in traditional oriental medicine to cure a variety of diseases including kidney problems, chronic diarrhea, excessive leucorrhea and hypofunction of the spleen. Based on the recent studies revealing antioxidant activities of Euryale ferox and its glucosides composition, we sought to determine if Euryale ferox seeds (Makhana) could reduce myocardial ischemic reperfusion injury. Two different models were used: acute model, where isolated rat hearts were preperfused for 15 min with Krebs Henseleit bicarbonate (KHB) buffer containing three different doses of makhana (25, 125 or 250 microg/ml) followed by 30 min of ischemia and 2 h of reperfusion; and chronic model, where rats were given two different doses of makhana (250 and 500 mg/kg/day) for 21 days, after which isolated hearts were subjected to 30 min of ischemia followed by 2 h of reperfusion. In both cases, the hearts of the Makhana treated rats were resistant to ischemic reperfusion injury as evidenced by their improved post-ischemic ventricular function and reduced myocardial infarct size. Antibody array technique was used to identify the cardioprotective proteins. The Makhana-treated hearts had increased amounts of thioredoxin-1 (Trx-1) and thioredoxin-related protein-32 (TRP32) compared to the control hearts. Western blot analysis confirmed increased expression of TRP32 and thioredoxin proteins. In vitro studies revealed that Makhana extracts had potent reactive oxygen species scavenging activities. Taken together, the results of this study demonstrate cardioprotective properties of Makhana and suggest that such cardioprotective properties may be linked with the ability of makhana to induce TRP32 and Trx-1 proteins and to scavenge ROS.
    Molecular and Cellular Biochemistry 10/2006; 289(1-2):55-63. · 2.33 Impact Factor
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    Peter Der, Jianhua Cui, Dipak K Das
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    ABSTRACT: Nitric oxide plays a crucial role in myocardial ischemia reperfusion injury as well as in myocardial adaptation to ischemic stress. To understand the dichotomy of nitric oxide behavior in the ischemic myocardium, isolated rat hearts were subjected to ischemia/reperfusion protocol. The tissue contents of sphingomyelin (SM), ceramide and sphingosine were determined by high performance thin layer chromatography (HPTLC). The myocardial plasma proteins were immunoprecipitated with caveolin-1 specific antibody. Ischemia/reperfusion resulted in the breakdown of SM with corresponding accumulation of ceramide and sphingosine. Immunoprecipitation with eNOS-specific antibody revealed the association of eNOS with caveolin-1 fraction of the heart. Ischemia/reperfusion caused a depression of contractile function and an increased apoptotic cell death and myocardial infarct size, which were reversed by pre-perfusing the hearts with desipramine, an sphingomyelinase inhibitor that also prevented ceramide accumulation and eNOS association with caveolin-1. The similar results were obtained when the hearts were adapted to ischemic stress by subjecting them to repeated reversible ischemia and reperfusion. The results indicate that ischemia/reperfusion causes an increase in eNOS, which is unavailable to the ischemic heart because of its binding with caveolin-1. Ceramide plays a crucial role in this process, because prevention of ceramide formation either by myocardial adaptation to ischemia or with desipramine results in the inhibition of eNOS association with caveolin-1 thereby reducing myocardial ischemic reperfusion injury.
    Journal of Molecular and Cellular Cardiology 03/2006; 40(2):313-20. · 5.15 Impact Factor
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    ABSTRACT: Several accepted methods are available to estimate the adenosine (Ado) concentration of interstitial fluid ([Ado]ISF) in functioning heart, providing results spanning over nano- to micromolar concentrations. This extremely large range points to the necessity of novel approaches for estimating [Ado]ISF or at least the alteration from basal [Ado]ISF. In the present study, the change in [Ado]ISF was characterized following nucleoside transport (NT) blockade elicited by 10 micromol/L dipyridamole or 10 micromol/L nitrobenzylthioinosine in isolated guinea pig atria, by means of our novel procedure referred to as receptorial responsiveness method (RRM). The RRM provided an index of the change in [Ado]ISF under NT blockade, namely the concentration of N-cyclopentyladenosine (CPA; a relatively stable A1 Ado receptor agonist), which is equieffective with the change in [Ado]ISF regarding the contractility. Our results show that dipyridamole or nitrobenzylthioinosine produced an elevation in [Ado]ISF at the cardiomyocyte A1 Ado receptors equivalent to about 16 or 20 nmol/l CPA, respectively. In addition, nitrobenzylthioinosine was found more appropriate for selective NT blockade than dipyridamole.
    Journal of Cardiovascular Pharmacology 02/2006; 47(1):103-9. · 2.38 Impact Factor
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    ABSTRACT: We created a simple method based on curve fitting in order to assess the concentration of pharmacological agonists or antagonists in the microenvironment of the receptors. We tested our method in electrically driven guinea pig left atria by estimating the concentration of N6-cyclopentyladenosine (CPA; A1 adenosine receptor agonist), acetyl-beta-methylcholine (muscarinic receptor agonist) and verapamil (L-type Ca2+ channel inhibitor) added previously to the atria in known amounts. Our results validated the fitness of the model under specified conditions. In addition, our data suggest a relatively slow elimination of CPA in isolated, practically bloodless guinea pig atrial myocardium.
    Bulletin of Mathematical Biology 10/2004; 66(5):1439-53. · 2.02 Impact Factor
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    ABSTRACT: We studied the effects of various cycles of preconditioning (PC) (one cycle, 1 x PC; two cycles, 2 x PC; three cycles, 3 x PC; and four cycles, 4 x PC) on cardiac function, infarct size, and the incidence of reperfusion-induced arrhythmias in isolated hearts obtained from rabbits with hypercholesterolemia. After 8 weeks of hypercholesterolemia, hearts were subjected to 30 min of ischemia followed by 120 min of reperfusion. Various cycles of PC resulted in a "cycle-dependent" reduction in infarct size in the age-matched nonhypercholesterolemic group. In the 8-week hypercholesterolemic group, increasing cycles of PC resulted in a significant increase in infarct size from their nonpreconditioned ischemic/reperfused control value of 44 +/- 5% to 45 +/- 6%, 49 +/- 5%, 59 +/- 6% (p < 0.05), and 58 +/- 5% (p < 0.05), respectively. PC increased the vulnerability of the myocardium to reperfusion-induced arrhythmias in hypercholesterolemics indicating that PC may be an "intact heart" phenomenon. The effects of PC appear currently to be a dilemma in laboratories and clinics. The solution to the problem of PC in intact and diseased myocardium requires further data from two different sources: (a) previously "diseased" animals, and (b) diseased human myocardium from clinics. Once these data are available, then the effects under which PC will be beneficial rather than harmful could be established and the dilemma solved.
    Antioxidants and Redox Signaling 04/2004; 6(2):325-33. · 7.19 Impact Factor
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    ABSTRACT: Heme oxygenase-1 (HO-1)-dependent carbon monoxide (CO) production related to reperfusion-induced ventricular fibrillation (VF) was studied in HO-1 wild-type (+/+), heterozygous (+/-), and homozygous (-/-) isolated ischemic/reperfused mouse heart. In HO-1 homozygous myocardium, under aerobic conditions, HO-1 enzyme activity, HO-1 mRNA, and protein expression were not detected in comparison with aerobically perfused wild-type and heterozygous myocardium. In wild-type, HO-1 hetero- and homozygous hearts subjected to 20 min ischemia followed by 2 h of reperfusion, the expression of HO-1 mRNA, protein, and HO-1 enzyme activity was detected in various degrees. A reduction in the expression of HO-1 mRNA, protein, and enzyme activity in fibrillated wild-type and heterozygous myocardium was observed. In reperfused/nonfibrillated wild-type and heterozygous hearts, a reduction in HO-1 mRNA, protein expression, and HO-1 enzyme activity was not observed, indicating that changes in HO-1 mRNA, protein, and enzyme activity could be related to the development of VF. These changes were reflected in the HO-1-related endogenous CO production measured by gas chromatography. In HO-1 knockout ischemic/reperfused myocardium, all hearts showed VF, and no detection in HO-1 mRNA, protein, and enzyme activity was observed. Thus, interventions that are able to increase endogenous CO may prevent the development of VF.
    The FASEB Journal 12/2003; 17(14):2133-5. · 5.70 Impact Factor
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    ABSTRACT: The contribution of alpha-melanocyte-stimulating hormone (alpha-MSH) treatment, an active fragment of adrenocorticotropic hormone (ACTH), to the recovery of postischemic cardiac function, infarct size, the incidence of reperfusion-induced ventricular fibrillation and apoptotic cell death was studied in ischemic/reperfused isolated rat hearts. Rats were subcutaneously injected with 40, 200 and 400 microg/kg of alpha-MSH, and 12 h later, hearts were isolated, perfused and subjected to 30 min of ischemia followed by 120 min of reperfusion. Thus, after 120 min of reperfusion, with the concentration of 200 microg/kg alpha-MSH, coronary flow, aortic flow and left ventricular developed pressure were significantly improved from their control values of 14.6+/-0.6 ml/min, 7.5+/-0.5 ml/min and 9.1+/-0.4 kPa to 20.2+/-0.4 ml/min (p<0.05), 31.5+/-0.9 ml/min (p<0.05) and 15.9+/-0.6 (p<0.05) kPa, respectively. With the doses of 40, 200 and 400 microg/kg of alpha-MSH, infarct size was reduced from its control value of 38+/-5% to 33+/-6% (NS), 17+/-3% (p<0.05) and 19+/-4% (p<0.05), respectively. The reduction in the incidence of reperfusion-induced ventricular fibrillation followed the same pattern. It is reasonable to assume that a reduction in infarct size, in the alpha-MSH-treated myocardium, resulted in a reduction as well in apoptotic cell death. Although we did not specifically study the exact mechanism(s) of alpha-MSH-afforded postischemic protection, we assume that this protection may be related to alpha-MSH-induced corticosterone release and corticosterone-induced de novo protein synthesis, which reflected in the recovery of postischemic cardiac function in isolated hearts. Thus, interventions that are able to increase plasma corticosterone or glucocorticoid release may prevent the development of ischemia/reperfusion-induced damage.
    European Journal of Pharmacology 06/2003; 470(3):177-83. · 2.59 Impact Factor
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    ABSTRACT: A halálozási statisztikákat évek óta a szív- és érrendszeri megbetegedések vezetik. A minőségi élet megteremtéséhez szükséges a korai halálozás okainak visszaszorítása, a megelőzés szerepének növelése. A betegségcsoport népegészségügyi jelentőségére való tekintettel minden új diagnosztikai és terápiás eljárás komoly tudományos és jelentős piaci érdeklődésre is számot tarthat. A szívizom iszkémiás megbetegedéseiben és a szívsebészeti beavatkozások során az iszkémia/reperfúzió jelenségének központi szerepe van. A hosszabb ideig tartó myocardiális iszkémia szívelégtelenséghez és sejthalálhoz vezethet. A korai terápia (reperfúzió) célja az iszkémiás terület oxigénnel és tápanyaggal történő ellátása, a keringés újraindítása. Bár a reperfúzió nélkülözhetetlen az iszkémia által károsodott szervek felépülésében, mégsem kockázatmentes, mivel maga a reperfúzió súlyosbíthatja az iszkémia utáni állapotban lévő szövetek funkcióját. Az iszkémiás szívbetegség leggyakoribb következményei az angina pectoris, szívinfarktus, szívelégtelenség és az aritmiák következtébenfellépő hirtelen szívhalál. Kísérleteinkben az iszkémia/reperfúzió-indukálta károsodások molekuláris mechanizmusait és farmakológiai befolyásolási lehetőségeit vizsgáltuk. Eredményeinket több hazai és nemzetközi konferencián mutattuk be, valamint számos nemzetközi folyóiratban publikáltuk, mely közlemények 2 db Ph.D. dolgozat alapját képezték. Kutatási eredményeinkből két hazai és két nemzetközi szabadalmi bejelentést tettünk. | Cardiovascular disorders are the leading cause of death worldwide. It is very important to increase the role of prevention in order to decrease the early death. Because of the epidemiological significance of the cardiovascular disorders every new diagnostic and therapeutic approach will have high interest both in science and in the pharmaceutical industry. Ischemia/reperfusion has a crucial role in ischemic heart diseases and cardiac surgery. Decreased oxygen supply and perfusion can cause serious injuries. The aim of the early therapy is the restoration of blood flow into the myocardium. However, reperfusion is necessary for the recovery it is not without hazard, because it can cause cell death. The most frequent consequences of ischemic heart disease are angina pectoris, infarction, heart failure and sudden cardiac death caused by arrhythmias. The overall aims of our studies were to investigate the molecular mechanisms of ischemia/reperfusion-induced cardiovascular damages and to develop new pharmacological approaches capable of reducing ischemia/reperfusion-induced damage. Our results allow us the more precise cognition of the mechanisms of ischemia/reperfusion and arrhythmias, making the possibility the development of new drugs. The results of our experiments were introduced on national and international conferences and published in international journals. Two Ph.D. dissertations were made from our results and we have 2 Hungarian and 2 international patents also.
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    Péter Dér