Norbert Nagy

Wayne State University, Detroit, Michigan, United States

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Publications (16)75.05 Total impact

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    Journal of Molecular and Cellular Cardiology 11/2012; 53(5):743. DOI:10.1016/j.yjmcc.2012.08.017 · 5.22 Impact Factor
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    Journal of Molecular and Cellular Cardiology 11/2012; 53(5):744. DOI:10.1016/j.yjmcc.2012.08.016 · 5.22 Impact Factor
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    Journal of Molecular and Cellular Cardiology 11/2012; 53(5):745. DOI:10.1016/j.yjmcc.2012.08.015 · 5.22 Impact Factor
  • N Nagy · G Malik · A B Fisher · D K Das
    AJP Heart and Circulatory Physiology 06/2012; 302(11):H2448. DOI:10.1152/ajpheart.zh4-0449-retr.2012 · 4.01 Impact Factor
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    ABSTRACT: Consumption of flavonoid-rich foods and beverages is thought to reduce the risk of cardiovascular diseases. Whereas the biological activities of flavonoids have been characterized in vitro, there are no clear experimental data demonstrating that chronic dietary intake and intestinal absorption of flavonoids actually protects the heart against ischemia-reperfusion injury. We tested whether long-term consumption of specific flavonoids (anthocyanins) included in normal food could render the heart of rats more resistant to myocardial infarction. Maize kernels that differed specifically in their accumulation of anthocyanins were used to prepare rodent food in which anthocyanins were either present or absent. Male Wistar rats were fed the anthocyanin-rich (ACN-rich) or the anthocyanin-free (ACN-free) diet for a period of 8 wk. Anthocyanins were significantly absorbed and detected in the blood and urine of only rats fed the ACN-rich diet. In Langendorff preparations, the hearts of rats fed the ACN-rich diet were more resistant to regional ischemia and reperfusion insult. Moreover, on an in vivo model of coronary occlusion and reperfusion, infarct size was reduced in rats that ate the ACN-rich diet than in those that consumed the ACN-free diet (P < 0.01). Cardioprotection was associated with increased myocardial glutathione levels, suggesting that dietary anthocyanins might modulate cardiac antioxidant defenses. Our findings suggest important potential health benefits of foods rich in anthocyanins and emphasize the need to develop anthocyanin-rich functional foods with protective activities for promoting human health.
    Journal of Nutrition 04/2008; 138(4):747-52. · 4.23 Impact Factor
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    ABSTRACT: This study examined if glutaredoxin-1 (Glrx1), a redox-regulator of thioredoxin superfamily, plays any role in the redox signaling of ischemic myocardium. The hearts were subjected to 30 min of coronary occlusion followed by 24 h of reperfusion. Another group of hearts was rendered tolerant to ischemia (preconditioned, PC) by four cyclic episodes of 5 min ischemia each followed by another 10 min of reperfusion, which was then subjected to 30 min ischemia and 24 h of coronary occlusion. While ischemia/reperfusion had no effect on Glrx1 expression, adaptation to ischemia resulted in the up-regulation of Glrx1 expression, which was inhibited by cadmium, a known inhibitor of Glrx1. CdCl(2) also abolished cardioprotection afforded by PC as evidenced by its ability to partially increase myocardial infarct size without affecting cardiomyocyte apoptosis. The amount of ROS was significantly decreased in the PC heart, which was abolished by CdCl(2). The cardioprotective role of Glrx1was further confirmed with Glrx1 transgenic and knockout mice. The mouse hearts overexpressing Glrx1 exhibited significantly improved post-ischemic ventricular recovery and reduced myocardial infarct size while hearts deficient in Glrx1 exhibited depressed functional recovery and increased infarct size as compared to the wild-type hearts. Furthermore, Glrx1-overexpressing hearts exhibited reduced and Glrx1-deficient hearts exhibited increased ROS production during ischemia and reperfusion. Adapted hearts showed increased Akt phosphorylation that was inhibited by CdCl(2). The amount of Bcl-2 protein expression was not affected by the inhibition of Glrx1. Taken together, the results of this study implicate a role of Glrx1 in cardioprotection and redox signaling of the ischemic myocardium.
    Journal of Molecular and Cellular Cardiology 03/2008; 44(2):261-9. DOI:10.1016/j.yjmcc.2007.08.022 · 5.22 Impact Factor
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    ABSTRACT: Mitochondrial glutaredoxin-2 (Glrx2) has been recognized as an important redox regulator in mammalian organs including heart. To date no investigations have addressed the potential role of Glrx2 in cardiac disorders. The present study examined if myocardial overexpression of Glrx2 in the heart could rescue the cardiac cells from apoptosis and necrosis induced by ischemia and reperfusion. The human Glrx2 transgene was created by placing a full-length cDNA fragment encoding human mitochondrial Glrx2 downstream to the 5' flanking sequence and promoter of the mouse alpha-myosin heavy chain gene. The isolated hearts from Glrx2 transgenic mice and non-transgenic (wild type) littermates [on c57BL/6xC3H hybrid background] were subjected to 30 min of global ischemia followed by 2 h of reperfusion via working mode. The hearts from Glrx2 transgenic mice displayed significantly improved contractile performance and reduced myocardial infarct size and cardiomyocyte apoptosis. There was a reduction in cytochrome c release and activation of caspase 3 and caspase 9. Glrx2 overexpression also reduced the ischemia/reperfusion-mediated loss of mitochondrial cardiolipin, decreased the activities of reactive oxygen species (ROS) and preserved GSH/GSSG ratio. Glrx2 mediated survival signal appeared to be stemmed from PI-3-kinase-Akt survival signaling pathway and involved the activation of redox sensitive transcription factor NFkappaB and antiapoptotic protein Bcl-2. The results indicated a crucial role of mitochondrial Glrx2 in cardioprotection.
    Journal of Molecular and Cellular Cardiology 03/2008; 44(2):252-60. DOI:10.1016/j.yjmcc.2007.08.021 · 5.22 Impact Factor
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    ABSTRACT: Previous studies have shown that 1 wk after permanent coronary artery ligation in rats, some cellular mechanisms involving TNF-alpha occur and contribute to the development of cardiac dysfunction and subsequent heart failure. The aim of the present study was to determine whether similar phenomena also occur after ischemia-reperfusion and whether cytokines other than TNF-alpha can also be involved. Anesthetized male Wistar rats were subjected to 1 h coronary occlusion followed by reperfusion. Cardiac geometry and function were assessed by echocardiography at days 5, 7, 8, and 10 postligation. Before death, heart function was assessed in vivo under basal conditions, as well as after volume overload. Finally, hearts were frozen for histoenzymologic assessment of infarct size and remodeling. The profile of cardiac cytokines was determined by ELISA and ChemiArray on heart tissue extracts. As expected, ischemia-reperfusion induced a progressive remodeling of the heart, characterized by left ventricular free-wall thinning and cavity dilation. Heart function was also decreased in ischemic rats during the first week after surgery. Interestingly, a transient and marked increase in TNF-alpha, IL-1beta, IL-6, cytokine-induced neutrophil chemoattractant (CINC) 2, CINC3, and macrophage inflammatory protein-3alpha was also observed in the myocardium of myocardial ischemia (MI) animals at day 8, whereas the expression of anti-inflammatory interleukins IL-4 and IL-10 remained unchanged. These results suggest that overexpression of proinflammatory cytokines occurring during the first week after ischemia-reperfusion may play a role in the adaptative process in the myocardium and contribute to early dysfunction and remodeling.
    AJP Heart and Circulatory Physiology 12/2007; 293(5):H3014-9. DOI:10.1152/ajpheart.00797.2007 · 4.01 Impact Factor
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    ABSTRACT: The existing literature indicates a crucial role of p38 MAP (mitogen-activated protein) kinase (p38MAPK) and its downstream target MAPKAP kinase 2 (MK2) in ischemic preconditioning (IPC). Accordingly, deletion of MK2 gene should abolish the cardioprotective ability of IPC. Interestingly, we were able to partially precondition the hearts from MK2(-/-) knockout mice suggesting the existence of an as yet unknown alternative downstream target of p38MAPK. A recent study from our laboratory also determined a crucial role of CREB (cyclic AMP response element binding protein) in IPC. Since CREB is a downstream target of MSK-1 (mitogen- and stress-activated protein kinase-1) situated at the crossroad of ERK (extracellular receptor kinase) and p38MAPK signaling pathways, we reasoned that MSK-1 could be a downstream molecular target for p38MAPK and ERK signaling in the IPC hearts. To test this hypothesis, the rat hearts were subjected to IPC by four cyclic episodes of 5 min ischemia and 10 min reperfusion. As expected, IPC induced the activation of ERK1/2, p38MAPK, MK2 and HSP (heat shock protein) 27 as evidenced by their increased phosphorylation; and the inhibition of p38MAPK with SB203580 almost completely, and the inhibition of ERK1/2 with PD098059 partially, abolished cardioprotective effects of IPC. Inhibition of MSK-1 with short hairpin RNA (shRNA) also abolished the IPC-induced cardioprotection. SB203580 partially blocked the effects of MSK-1 suggesting that MSK-1 sits downstream of p38MAPK. shRNA-MSK-1 blocked the contribution of both p38MAPK and ERK1/2 as it is uniquely situated at the downstream crossroad of both of these MAP kinases. Although MSK-1 sits downstream of both ERK1/2 and p38MAPK, ERK1/2 activation appears to play less significant role compared to p38MAPK, since its inhibition blocked MSK activation only partially. Consistent with these results, shRNA-MSK-1 blocked the partial PC in MK2(-/-) hearts, and in combination with SB203580, completely abolished the PC effects in the wild-type hearts. The IPC-induced survival signaling was almost completely inhibited with SB203580, and only partially with PD 098059 as evidenced from the inhibition patterns of IPC induced activation of CREB, Akt and Bcl-2. Again SB203580 alone or in combination with shRNA-MSK-1 inhibited IPC induced survival signal comparatively, suggesting that MSK-1 exists downstream of p38MAPK. Taken together, these results indicate for the first time MSK-1 as an alternative (other than MK2) downstream target for p38MAPK, which also transmits survival signal through the activation of CREB.
    Journal of Molecular and Cellular Cardiology 05/2007; 42(5):981-90. DOI:10.1016/j.yjmcc.2007.02.010 · 5.22 Impact Factor
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    ABSTRACT: PR-39, a proline-arginine-rich angiogenic response peptide, has been implicated in myocardial ischemic reperfusion injury. The present study examined the cardioprotective abilities of PR39 gene therapy. Male C57Bl/J6 mice were randomized to intramyocardial injecton of 10(9) p.f.u. adenovirus encoding PR39 (PR39), FGFR1 dominant negative signaling construct (FGFR1-dn), empty vector (EV), or PR39 adenovirus plus 4 microg of plasmid endcoding a HIF1alpha dominant negative construct (PR39 + HIF1alpha-dn). Seven days later, hearts were subjected to 20 min of ischemia (I) and 2 h. reperfusion (R) ex vivo and aortic and coronary flow, left ventricular developed pressure (LVDP), and LVdp/dt were measured. Myocardial infarct (MI) size and cardiomyocyte apoptosis were measured by TTC staining and TUNEL, respectively. PR39 expression was robust up to 14 days after gene transfer and was absent after EV and FGFR1-dn. Hemodynamics showed no differences at baseline, and heart rate remained unchanged in all groups throughout the experiment. After I-R, hemodynamics remained unchanged in PR39 hearts, but deteriorated significantly in the other groups, except for aortic flow, which remained significantly higher in FGFR1-dn than in EV and PR39 + HIF1alpha-dn (p < 0.05), although it was lower than in PR39 (p < 0.05). MI was 8.7 +/- 0.9 % in PR39, 23.8 +/- 1.1% in FGFR1-dn, 29.9 +/- 2.2% in EV, and 30.8 +/- 2.7 % in PR39 + HIF1alpha-dn (PR39 vs. other groups: p < 0.05; FGFR1-dn vs. EV and PR39 + HIF1alpha-dn: p < 0.05). In PR39, HIF-1alpha protein was higher than in FGFR1-dn and EV. Importantly, cotransfection of HIF1alpha-dn with PR39 completely abolished cardioprotection by PR39. Cardioprotection by PR39 is likely conveyed by protective metabolic and survival responses through HIF1-alpha stabilization and not by angiogenesis, because baseline coronary flow was the same in all groups. Abrogation of FGFR1 signaling conveyed an intermediate degree of cardioprotection.
    Antioxidants and Redox Signaling 04/2007; 9(4):437-45. DOI:10.1089/ars.2006.1501 · 7.67 Impact Factor
  • Norbert Nagy · Gautam Malik · Aron B Fisher · Dipak K Das
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    ABSTRACT: Peroxiredoxin 6 (Prdx6) is a novel peroxidase enzyme belonging to the Prdx family, which in mammals contains five more peroxiredoxins (Prdx1-Prdx5). Like glutathione peroxidase (GSHPx) and catalase, Prdx6 possesses H(2)O(2)-scavenging activities, and, like the former, it also removes hydroperoxides. Since significant amounts of catalase and GSHPx are present in the heart contributing toward the attenuation of H(2)O(2) and hydroperoxides formed during ischemia-reperfusion injury and thereby providing cardioprotection, we asked whether Prdx6 also has any role in this process. In the present study we used Prdx6(-/-) mice to assess the role of Prdx6 in ischemic injury. Western blot analysis revealed the absence of any Prdx activity in the Prdx6(-/-) mouse heart, while the GSHPx-1 and catalase levels remained unchanged. Randomly selected hearts from Prdx6(-/-) mice and wild-type mice were subjected to 30 min of global ischemia followed by 120 min of reperfusion at normothermia. The hearts from the Prdx6(-/-) mice were more susceptible to ischemic reperfusion injury as evidenced by reduced recovery of left ventricular function, increased myocardial infarct size, and higher amount of apoptotic cardiomyocytes compared with wild-type mouse hearts. These Prdx6(-/-) hearts were also subjected to a higher amount of oxidative stress as evidenced by the presence of higher amount of malondialdehyde. The present study thus indicates a nonredundant role of Prdx6 in myocardial ischemic reperfusion injury as catalase, and GSHPx could not make up for the deficiency of Prdx6 activities.
    AJP Heart and Circulatory Physiology 01/2007; 291(6):H2636-40. DOI:10.1152/ajpheart.00399.2006 · 4.01 Impact Factor
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    Cell Death and Differentiation 11/2006; 13(10):1827-9. DOI:10.1038/sj.cdd.4401889 · 8.39 Impact Factor
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    ABSTRACT: The effects of kernel extract obtained from sour cherry (Prunus cerasus) seed on the postischemic cardiac recovery were studied in isolated working rat hearts. Rats were treated with various daily doses of the extract for 14 days, and hearts were then isolated and subjected to 30 min of global ischemia followed by 120 min of reperfusion. The incidence of ventricular fibrillation (VF) and tachycardia (VT) fell from their control values of 92% and 100% to 50% (not significant) and 58% (not significant), 17% (P<0.05), and 25% (P<0.05) with the doses of 10 mg/kg and 30 mg/kg of the extract, respectively. Lower concentrations of the extract (1 and 5 mg/kg) failed to significantly reduce the incidence of VF and VT during reperfusion. Sour cherry seed kernel extract (10 and 30 mg/kg) significantly improved the postischemic recovery of cardiac function (coronary flow, aortic flow, and left ventricular developed pressure) during reperfusion. We have also demonstrated that the extract-induced protection in cardiac function significantly reflected in a reduction of infarct size. Immunohistochemistry indicates that a reduction in caspase-3 activity and apoptotic cells by the extract, beside other potential action mechanisms of proanthocyanidin, trans-resveratrol, and flavonoid components of the extract, could be responsible for the cardioprotection in ischemic-reperfused myocardium.
    AJP Heart and Circulatory Physiology 10/2006; 291(3):H1329-36. DOI:10.1152/ajpheart.01243.2005 · 4.01 Impact Factor
  • I Bak · J Varadi · N Nagy · M Vecsernyes · A Tosaki
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    ABSTRACT: Isolated rat hearts were perfused for 10 min with oxygenated buffer and equilibrated with carbon monoxide (CO) of 0.001% and 0.01% before the induction of 30 min global ischemia followed by 120 min of reperfusion. These concentrations of CO significantly improved the post-ischemic recovery of coronary flow (CF), aortic flow (AF), and left ventricular developed pressure (LVDP). The improvement in recovery reflected in the reduction of infarct size and the incidence of reperfusion-induced ventricular fibrillation (VF). Thus, hearts subjected to 0.001% and 0.01% of CO exposure via the perfusion buffer, infarct size was reduced from the CO-free control value of 39% +/- 5% to 21% +/- 3% (*p<0.05) and 18% +/- 4% (*p<0.05), respectively. In the presence of 0.001% and 0.01% CO, the incidence of VF was also reduced from its control value of 92% to 17% (*p<0.05) and 17% (*p<0.05), respectively. Increasing the CO exposure to 0.1% in the buffer, all hearts showed VF combined with ventricular tachycardia or bradycardia and various rhythm disturbances indicating the direct toxic effects of CO on the myocardium. The results show that cardioprotective concentrations (0.01% and 0.001%) of exogenous CO related to an increase in cGMP levels and guanylate cyclase activities.
    Cellular and molecular biology (Noisy-le-Grand, France) 10/2005; 51(5):453-9. DOI:10.1170/T650 · 1.46 Impact Factor
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    ABSTRACT: There is increasing evidence to show cytoprotective effects of various flavonoid-rich extracts and the tissue-protective capacity of flavonoid-rich extract of sour cherry is due to flavonoid components of seeds. Sour cherry seed flavonoids were evaluated for their contribution to postischemic recovery related to endogenous carbon monoxide (CO) production in rat retinas subjected to ischemia/reperfusion. Rats were orally treated with selected doses of flavonoid-rich extract of sour cherry seeds for 2 weeks. Animals were anesthetized, and a suture was placed behind the globe including the central retinal artery. Next, retinas were subjected to 90 minutes of ischemia followed by 24 hours of reperfusion. After this procedure, heme oxygenase-1 (HO-1)-related protein expression and enzyme activity, HO-1-related endogenous CO production, and ionic imbalance including tissue Na(+), K(+), and Ca(2+) in untreated and treated ischemic/reperfused retinas were measured. Retinal ischemia/reperfusion resulted in a significant reduction (to 10%) in HO-1 protein expression, enzyme activity, and HO-1-related endogenous CO production in the retina. These changes were accompanied by increases in retinal Na(+) and Ca(2+) gains and loss of K(+). In rats treated with 10 and 30 mg/kg of sour cherry flavonoid-rich extract, after 24 hours of reperfusion, tissue Na(+) and Ca(2+) accumulation and K(+) loss were prevented in comparison with the drug-free control. Sour cherry seed flavonoid-rich extract showed a protective effect against reperfusion-induced injury through its ability to reduce the changes in concentrations of retinal ions through HO-1-related endogenous CO production in the ischemic/reperfused retina.
    Investigative Ophthalmology &amp Visual Science 11/2004; 45(10):3727-32. DOI:10.1167/iovs.03-1324 · 3.66 Impact Factor
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    ABSTRACT: We investigated the contribution of dexamethasone treatment on the recovery of postischemic cardiac function and the development of reperfusion-induced arrhythmias in ischemic/reperfused isolated rat hearts. Rats were treated with 2 mg/kg of intraperitoneal injection of dexamethasone, and 24 hours later, hearts were isolated according to the 'working' mode, perfused, and subjected to 30 min global ischemia followed by 120 min reperfusion. Cardiac function including heart rate, coronary flow, aortic flow, and left ventricular developed pressure were recorded. After 60 min and 120 min reperfusion, 2 mg/kg of dexamethasone significantly improved the postischemic recovery of aortic flow and left ventricular developed pressure from their control values of 10.7 +/- 0.3 ml/min and 10.5 +/- 0.3 kPa to 22.2 +/- 0.3 ml/min (p < 0.05) and 14.3 +/- 0.5 kPa (p < 0.05), 19.3 +/- 0.3 ml/min (p < 0.05) and 12.3 +/- 0.5 kPa (p < 0.05), respectively. Heart rate and coronary flow did not show a significant change in postischemic recovery after 60 or 120 min reperfusion. In rats treated with 0.5 mg/kg of actinomycin D injected i.v., one hour before the dexamethasone injection, suppressed the dexamethasone-induced cardiac protection. Electrocardiograms were monitored to determine the incidence of reperfusion-induced ventricular fibrillation. Dexamethasone pretreatment significantly reduces the occurrence of ventricular fibrillation. Cytochrome c release was also observed in the cytoplasm. The results suggest that the inhibition of cytochrome c release is involved in the dexamethasone-induced cardiac protection.
    Life Sciences 10/2004; 75(20):2411-23. DOI:10.1016/j.lfs.2004.04.031 · 2.30 Impact Factor

Publication Stats

454 Citations
75.05 Total Impact Points

Institutions

  • 2008–2012
    • Wayne State University
      Detroit, Michigan, United States
    • University of Connecticut
      • Department of Medicine
      Storrs, Connecticut, United States
  • 2004–2012
    • University of Debrecen
      • • Department of Pharmacology and Pharmacotherapy
      • • Department of Pharmaceutical Technology
      Debreczyn, Hajdú-Bihar, Hungary
  • 2007
    • Geisel School of Medicine at Dartmouth
      Hanover, New Hampshire, United States