Apostolos Papalois

University of Ioannina, Yannina, Epirus, Greece

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Publications (201)484.32 Total impact

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    ABSTRACT: The effects of changes in left ventricular (LV) afterload on diastolic function of acutely ischemic and reperfused myocardium have not been studied in depth. We examined 1) the consequences of increasing the LV afterload on LV diastolic function during acute ischemia and reperfusion, 2) whether the myocardial response to afterload elevation is stable throughout a 2-h reperfusion period, and 3) the role of LV wall synchrony on the development of afterload-induced diastolic dysfunction. We instrumented 12 anesthetized, open chest pigs with Millar pressure catheters and piezoelectric crystals before ligating the mid left anterior descending coronary artery for 1 h, followed by reperfusion for 2 h. Six of the animals survived throughout the 2 hours of reperfusion and their data were used for comparisons across the different experimental phases. LV afterload was increased by inflating an intraaortic balloon. Data were recorded at baseline and after 20 min of coronary occlusion, and 30 and 90 min of myocardial reperfusion. The increased afterload for 2 minutes lengthened the isovolumic relaxation during ischemia, and during early and late reperfusion but had no significant effect on isovolumic relaxation before coronary artery occlusion. Increasing the afterload aggravated LV diastolic dyssynchrony during coronary artery occlusion, but not during reperfusion. The afterload-induced prolongation of isovolumic relaxation was positively correlated with afterload-induced diastolic dyssynchrony. These observations indicate that, during myocardial ischemia and throughout reperfusion, LV diastolic function is afterload-dependent. Afterload-induced diastolic dyssynchrony might be an underlying mechanism of diastolic dysfunction during acute ischemia.This article is protected by copyright. All rights reserved
    Experimental physiology 12/2014; · 2.87 Impact Factor
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    ABSTRACT: Background: The readmission of molecular oxygen into an ischemic tissue promotes the oxidation of resuscitated tissue with certain pathophysiologic mechanisms. Materials and methods: Twenty four pigs (male or female) were randomized in this study. The animals were allocated to four groups with an equal number (n = 6) in each group: 1) control group-ischemia for 30 min and reperfusion for 60 min. 2) control group-ischemia for 30 min and reperfusion for 120 min. 3) ischemia for 30 min and immediate iv injection of lazaroid U-74389G and reperfusion for 60 min. 4) ischemia for 30 min and immediate iv injection of lazaroid U-74389G and reperfusion for 120 min. Results: We investigated further the role of an antioxidant molecule such as U-74389G and we concluded that there is statistically significant relation in MDA (malondialdeyde), TNF -α (tumor necrosis factor-α) measurement in tissue, while the histological score in the groups that the lazaroid was administered was improved. Conclusions: In many emergency clinical situations, such as reperfusion of the intestine, the role of U-74389G can be protective. Copyright © 2014 Surgical Associates Ltd. Published by Elsevier Ltd. All rights reserved.
    International Journal of Surgery (London, England) 11/2014; · 1.44 Impact Factor
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    ABSTRACT: Cardiopulmonary resuscitation (CPR) in patients with severe sepsis and septic shock is challenging and usually unsuccessful. The aim of the present study is to describe our swine model of cardiac arrest and resuscitation in severe sepsis and septic shock.
    Shock (Augusta, Ga.) 11/2014; · 2.87 Impact Factor
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    ABSTRACT: We investigated the effects of intra-aortic balloon pump (IABP) counterpulsation on left ventricular (LV) contractility, relaxation, and energy consumption and probed the underlying physiologic mechanisms in 12 farm pigs, using an ischemia-reperfusion model of acute heart failure. During both ischemia and reperfusion, IABP support unloaded the LV, decreased LV energy consumption (pressure-volume area, stroke work), and concurrently improved LV mechanical performance (ejection fraction, stroke volume, cardiac output). During reperfusion exclusively, IABP also improved LV relaxation (tau) and contractility (Emax, PRSW). The beneficial effects of IABP support on LV relaxation and contractility correlated with IABP-induced augmentation of coronary blood flow. In conclusion, we find that during both ischemia and reperfusion, IABP support optimizes LV energetic performance (decreases energy consumption and concurrently improves mechanical performance) by LV unloading. During reperfusion exclusively, IABP support also improves LV contractility and active relaxation, possibly due to a synergistic effect of unloading and augmentation of coronary blood flow.
    Journal of Cardiovascular Translational Research 11/2014; · 3.06 Impact Factor
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    ABSTRACT: Background Crohn's disease is still incurable. Compounds with anti-inflammatory and/or antioxidative effects are tested in various preclinical models of the disease. Our aim was to investigate the effects of sildenafil and lazaroid U74389G in an experimental rat model of trinitrobenzene sulfonic acid (TNBS)-induced colitis. Materials and Methods TNBS was instilled into the colon of male Wistar rats except for the first group. For 6 days the animals in group 3 were administered daily sildenafil per os, the rats in group 4 were administered daily U-74389G IV and the rats in group 5 were codministered daily sildenafil per os and IV U-74389G The rats in groups 1 and 2 were not administered any treatment. During the study the rat weights were recorded as a marker of clinical condition. The colon damage was evaluated using macroscopic (CMDI), microscopic (Geboes score) and biochemical analysis (tissue TNF-a and MDA). Results Sildenafil reduced TNF-a tissue levels and increased body weight. U-74389G reduced TNF-a, the macroscopic index of mucosal damage score (CMDI) and increased the weight. The combined treatment with sildenafil and U-74389G reduced tissue levels of TNF-a and MDA, lowered CMDI and microscopic Geboes score and increased the weight. Conclusions U-74389G demonstrated a significant anti-inflammatory activity related to its ability to reduce colonic TNF-a, CMDI score and improve weight change. We confirmed that sildenafil has anti-inflammatory capacity by reducing colonic TNF-a and by improving weight change. Finally, the combined treatment showed superior effects by reducing colonic TNF-a, colonic MDA, CMDI score, Geboes score, and by improving weight change.
    Journal of Surgical Research 09/2014; · 2.12 Impact Factor
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    ABSTRACT: The aim of this experiment was to study the effects of the antioxidant drug "U-74389G" on rat model, particularly in ischemia reperfusion protocol. The beneficial or other effects of that molecule were studied estimating the mean oophoritis (OI) lesions. Materials and methods: 40 rats were used of mean weight 231.875 g. OI was evaluated 60 min after reperfusion for groups A and C and 120 min after reperfusion for groups B and D. Groups A and B without the drug but C and D with U-74389G administration. Results were that U-74389G administration kept non-significantly increased the OI scores by 0.05+0.051 without lesions (p=0.3204). Reperfusion time kept non-significantly increased the OI scores by 0.05+0.051 also without lesions (p=0.3204). Nevertheless, U-74389G administration and reperfusion time together kept non-significantly increased the OI scores by 0.045+0.030 (p=0.1334). Conclusions: Results of this study indicate that U-74389G administration, reperfusion time and their interaction got on declining the increased OI scores from significant to non-significant level.
    Anti-Inflammatory & Anti-Allergy Agents in Medicinal Chemistry (Formerly Cu rrent Medicinal Chemistry - Anti-Inflammatory and Anti-Allergy Agents) 08/2014;
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    ABSTRACT: Βackground And Aim: Infliximab is effective in the induction and maintenance of remission in Crohn's disease. Whether, the perioperative administration of anti-TNF-a compromises intestinal healing leading to anastomotic failure and increased risk of postoperative complications, remains controversial. The aim of the study was to evaluate the effect of Infliximab on intestinal anastomosis healing. Methods: Fifty six wistar rats were divided into 4 groups: (a) 20 rats were subjected to excision of part of the terminal ileum followed by anastomosis which was evaluated on the 3rd or 7th postoperative day; (b) 20 rats received Infliximab and thereafter, the same surgical protocol as group (a) was followed; (c) 8 rats received Infliximab and served as relative control group; and (d) 8 served as absolute control group. Bursting pressure was used for testing intestinal healing. Additionally, the anastomoses were examined macroscopically, histologicaly and immunohistochemicaly for TGFb1, MMP1, MMP2 and Collagen V. The results were confirmed by Western blot analysis. Results: There were no significant differences in bursting pressures and septic intra-abdominal events among non-Infliximab (a) and Infliximab-treated (b) groups. Infliximab-treated (b) group showed mild to moderate inflammation, whereas the non-Infliximab (a) group exhibited severe inflammation. Expression of TGFb1, MMP2 and collagen V was significantly higher in the Infliximab-treated (b) group. Conclusion: Infliximab seems to influence intestinal healing in terms of less inflammatory activity and higher tissue remodeling activity.
    International Journal of Surgery (London, England) 08/2014; · 1.44 Impact Factor
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    14th International Congress of the European Association for Endoscopic Surgery (EAES), Palais des Congrès de Paris, Place de la Porte Maillot, Paris, France; 06/2014
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    ABSTRACT: Export Date: 18 October 2014
    Turk Uroloji Dergisi 06/2014; 40(2):110-114.
  • Resuscitation 05/2014; 85:S4. · 3.96 Impact Factor
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    ABSTRACT: In addition to its role in the endogenous control of erythropoiesis, recombinant human erythropoietin (rh-EPO) has been shown to exert tissue protective properties in various experimental models. However, its role in the cardiac arrest (CA) setting has not yet been adequately investigated.
    American Journal of Emergency Medicine 04/2014; · 1.15 Impact Factor
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    ABSTRACT: The aim of the present study was to evaluate the effectiveness of two isoenergetic elemental formulae with different fat content in the rat model of trinitrobenzene sulphonic acid (TNBS) colitis that mimics human inflammatory bowel disease. A total of forty-five male Wistar rats were assigned to five groups: (1) control group; (2) TNBS-induced colitis group; (3) TNBS-induced colitis group fed a long-chain TAG (LCT)-rich diet; (4) TNBS-induced colitis group fed a medium-chain TAG (MCT)-rich diet; (5) TNBS-induced colitis group fed a baseline diet and administered infliximab. Nutritional management lasted 12 d before and 4 d after rectal administration of TNBS. Subsequently, the rats were killed, and colonic tissue samples were collected for the assessment of histology, inflammation and oxidative stress. The MCT-rich diet decreased IL-6, IL-8 and intercellular adhesion molecule-1 (ICAM-1) levels and glutathione S-transferase (GST) activity, while the LCT-rich diet reduced only ICAM-1 levels and GST activity (P<0.05). Neither elemental formula affected IL-10 levels. Infliximab reduced IL-8 and ICAM-1 levels and GST activity and increased IL-10 levels (P<0.05). No significant differences were detected in oxidative stress. Histological damage scores differed significantly only between the control and the TNBS-induced colitis group. A MCT-rich formula seems to exert stronger anti-inflammatory effects than a LCT-rich formula in TNBS colitis.
    British Journal of Nutrition. 04/2014; 111(7):1213-20.
  • Neurological Sciences 04/2014; · 1.50 Impact Factor
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    ABSTRACT: Despite advances in surgical treatment options, large rotator cuff (r-c) tears still represent a challenge for orthopedic surgeons. The purpose of this study was to evaluate the temporary and spatial histological incorporation of fascia lata allografts, used for bridging artificially created defects of the r-c.
    International Journal of Shoulder Surgery 04/2014; 8(2):39-46. · 0.51 Impact Factor
  • BioMed Research International 03/2014; · 2.71 Impact Factor
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    ABSTRACT: Tumor necrosis factor (TNF)α is a cytokine exerting pleiotropic effects on critical cell functions and, most importantly, is the main regulator of pro-inflammatory cytokine production and a key player in the pathophysiology of numerous autoimmune diseases, including Crohn's disease. TNFα became a therapeutic target and TNFα blocking agents are currently used in the treatment of inflammatory diseases. Beyond the therapeutic benefits deriving from TNFα neutralization, amendments in the cellular functions of the immune system may as well induce potent immunosuppressive effects. An attenuated immune response may compromise the intestinal healing ability, thus leading to weaker anastomosis and increased risk of anastomotic leak and septic complications. This hypothesis raises great concerns about the safety of perioperative administration of anti-TNF and has been the endpoint of numerous studies. The aim of this review is to critically evaluate the evidence regarding the role of TNFα in anastomosis related complications after abdominal surgery in Crohn's disease patients.
    Journal of Gastrointestinal Surgery 03/2014; · 2.36 Impact Factor
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    ABSTRACT: ABSTRACT Introduction: Hepatocyte transplantation is proposed as a solution for liver failure. The allotransplantation of hepatocytes has been studied extensively, however, graft rejection remains a major problem. The aim of the present study was to evaluate the immunosuppressive activity of mycophenolate mofetil (MMF), sirolimus, and their combination in an experimental model of hepatocyte allotransplantation in rats with acute liver failure. Materials and methods: Five male Wistar rats were used as hepatocyte donors and 60 male Lewis rats as recipients. The recipients were divided into five groups of 12 animals each. Group 1: no treatment. Group 2: cyclosporine. Group 3: sirolimus. Group 4: MMF. Group 5: MMF and sirolimus. All surviving animals were preserved for 15 days. For the induction of acute liver failure the recipients were injected with N-dimethyl-nitrosamine 24 hr before transplantation. The isolated hepatocytes were transplanted intrasplenically. Results: Analysis of the results showed a statistically significant prolongation of animal survival for groups 3, 4, and 5. More animals in group 5 survived than those in groups 3 and 4, although the difference was not statistically significant. Transplant hepatocyte survival was significantly better in groups 3, 4, and 5. Hepatocytes transplanted in the spleen of animals of group 5 showed better survival compared with those of groups 3 and 4. Conclusion: Use of MMF and sirolimus, as monotherapy or in combination, is both effective and safe as immunosuppressive treatment in hepatocyte transplantation, as was proven in this experimental protocol.
    Journal of Investigative Surgery 02/2014; · 1.32 Impact Factor
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    ABSTRACT: The aim of this study was to demonstrate a percutaneous transauricular method of balloon angioplasty in high-cholesterol fed rabbits, as an innovative atherosclerosis model. Twenty male New Zealand rabbits were randomly divided into two groups of ten animals, as follows: atherogenic diet plus balloon angioplasty (group A) and atherogenic diet alone (group B). Betaalloon angioplasty was performed in the descending thoracic aorta through percutaneous catheterization of the auricular artery. Eight additional animals fed regular diet were served as long term control. At the end of 9 week period, rabbits were euthanized and thoracic aortas were isolated for histological, immunohistochemical and biochemical analysis. Atherogenic diet induced severe hypercholesterolemia in both group A and B (2802 +/- 188.59 and 4423 +/- 493.39 mg/dl respectively) compared to the control animals (55.5 +/- 11.82 mg/dl; P < 0.001). Group A atherosclerotic lesions appeared to be more advanced histologically (20% type IV and 80% type V) compared to group B lesions (50% type III and 50% type IV). Group A compared to group B atherosclerotic lesions demonstrated similar percentage of macrophages (79.5 +/- 9.56% versus 84 +/- 12.2%; P = 0.869), more smooth muscle cells (61 +/- 14.10% versus 40.5 +/- 17.07; P = 0.027), increased intima/media ratio (1.20 +/- 0.50 versus 0.62 +/- 0.13; P = 0.015) despite the similar degree of intimal hyperplasia (9768 +/- 1826.79 mum2 versus 12205 +/- 8789.23 mum2; P = 0.796), and further significant lumen deterioration (23722 +/- 4508.11 versus 41967 +/- 20344.61 mum2; P = 0.05) and total vessel area reduction (42350 +/- 5819.70 versus 73190 +/- 38902.79 mum2; P = 0.022). Group A and B animals revealed similar nitrated protein percentage (P = NS), but significantly higher protein nitration compared to control group (P < 0.01; P < 0.01, respectively). No deaths or systemic complications were reported. Transauricular balloon angioplasty constitutes a safe, minimally invasive and highly successful model of induced atherosclerosis in hyperlipidaemic rabbits.
    Lipids in Health and Disease 02/2014; 13(1):33. · 2.31 Impact Factor
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    ABSTRACT: Aims We investigated the role of endothelin-B receptors on sympathetic activation originating from the adrenal gland or from the myocardium and its impact on arrhythmogenesis during acute myocardial infarction. Main methods We studied two groups of rats (n = 120, 284 ± 2 g), namely wild-type and ETB-deficient. Myocardial infarction was induced by permanent ligation of the left coronary artery and ventricular tachyarrhythmias were evaluated from continuous electrocardiographic recordings. Sympathetic activation, measured by indices of heart rate variability, was evaluated after adrenalectomy or catecholamine depletion induced by reserpine. Acute left ventricular failure was assessed by total animal activity. Key findings Adrenalectomy decreased the total duration of tachyarrhythmias in ETB-deficient rats, but their incidence remained higher, compared to wild-type rats. After reserpine, heart rate variability indices and tachyarrhythmias were similar in the two groups during the initial, ischaemic phase. During evolving infarction, tachyarrhythmia duration was longer in ETB-deficient rats, despite lower sympathetic activation. Heart rate was lower in ETB-deficient rats throughout the 24-hour observation period, whereas activity was comparable in the two groups. Significance Endothelin-B receptors modulate sympathetic activation during acute myocardial infarction in the ventricular myocardium, but also in the adrenal gland. Sympathetic activation markedly increases early-phase ventricular tachyarrhythmias, but other mechanisms involving the endothelin system underlie delayed arrhythmogenesis.
    Life sciences 02/2014; · 2.56 Impact Factor
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    ABSTRACT: ABSTRACT Introduction: The aim of this study was to develop a model of fibrous cholangitis in the offspring of gravid domestic pigs through the administration of 1,4-phenylene diisothiocyanate (DITC). Material and Methods: Six young domestic pigs and two gravid pigs with their offspring (21 pigs) were used as experimental models and six wild-type animals were used as controls. All pigs were divided into five main groups and five subgroups, according to their developmental stage and time of exposure to DITC. The following histopathological characteristics were quantitatively evaluated on a scale of 0-5: ductal proliferation, periportal fibrosis, inflammatory infiltration, periductal fibrosis and edema, intraluminal fibrosis, duct wall thickening, epithelial apoptosis, and arterial hyperplasia/hypertrophy. Results: Statistically significant differences were observed for most of the histopathological markers between the group of pigs' offspring that received DITC at early gestation and their control group. Moreover, the group of animals that were exposed to the agent at early gestation exhibited significant differences for all histopathological characteristics compared to the animals that were exposed at late gestation. On the other hand, no statistically significant differences were observed between the group of animals that received the agent at late gestation and their healthy controls. Conclusions: Administration of DITC to domestic pigs in early pregnancy may induce histopathological patterns of fibrous cholangitis to their offspring imitating biliary atresia. This model may provide insight to the pathogenesis of the obstructive cholangitis in pigs.
    Journal of Investigative Surgery 01/2014; · 1.32 Impact Factor

Publication Stats

915 Citations
484.32 Total Impact Points


  • 2013
    • University of Ioannina
      Yannina, Epirus, Greece
    • Università degli studi di Cagliari
      Cagliari, Sardinia, Italy
    • Γενικό Νοσοκομείο Σάμου Αγίου Παντελεήμονα
      Vathy, North Aegean, Greece
  • 1994–2013
    • Athens State University
      Athens, Alabama, United States
  • 2012
    • 401 GSNA
      Athínai, Attica, Greece
  • 2008–2012
    • Attikon University Hospital
      • Department of Cardiology
      Athínai, Attica, Greece
  • 2003–2012
    • National and Kapodistrian University of Athens
      • • Department of Pharmaceutical Chemistry
      • • Faculty of Medicine
      • • Division of Intensive Care I
      Athens, Attiki, Greece
  • 2011
    • General Hospital of Attica KAT
      Kēfissia, Attica, Greece
  • 2007–2011
    • Red Cross Hospital, Athens
      Athínai, Attica, Greece
    • Democritus University of Thrace
      • Department of Internal Medicine I
      Komotiní, Anatoliki Makedonia kai Thraki, Greece
  • 2000–2010
      Athínai, Attica, Greece
  • 2006
    • Elpen Pharmaceuticals Co. Inc.
      Athínai, Attica, Greece
    • Forest Research Institute of Athens
      Athínai, Attica, Greece
  • 2005
    • Laiko Hospital
      • First Department of Surgery
      Athínai, Attica, Greece
  • 2000–2005
    • Onassis Cardiac Surgery Center
      • Department of Cardiology
      Kallithéa, Attiki, Greece
  • 2004
    • Alexandra Regional General Hospital
      Athínai, Attica, Greece