Murat Dikmengil

The protective effect of N-acetylcysteine on apoptotic lung injury in cecal ligation and puncture-induced sepsis model.

Apoptotic loss of parenchymal cells may lead to organ dysfunctions in critically ill patients with septic states. As an antioxidant, the protective effects of N-acetylcysteine (NAC) are documented in many experimental and clinical studies. In this experimental study, we investigated the role of chronically used NAC in septic lung injury on a cecal ligation and puncture (CLP) model. To evaluate this, 30 male Wistar rats were randomly divided into four groups as sham (n = 7), CLP (n = 8), sham + NAC (n = 7) and CLP + NAC (n = 8) groups. NAC was administered 150 mg kg−1 day through intramuscular route beginning 6 h after the operations and lasting for a period of 1 week. One week later, histopathology and epithelial apoptosis were assessed by hematoxylin-eosin and immunohistochemically by M30 and caspase 3 staining to demonstrate septic lung injury. Additionally, lung tissue myeloperoxidase (MPO) activity, malondialdehyde (MDA), and nitrite/nitrate levels were measured. The MPO activity and MDA levels in lung homogenates were found to be increased in CLP group and the administration of NAC prevented their increase significantly (P < 0.05). However, there were no significant differences among the groups regarding nitrite/nitrate levels. The number of apoptotic cells was significantly lower in CLP+NAC group than CLP group, and this finding was supported by M30 and caspase 3 expression in lung (P < 0.05). Lung histopathology was also protected by NAC in CLP-induced sepsis. In conclusion, the chronic use of NAC inhibited MPO activity and lipid peroxidation, which resulted in reduction of apoptosis in lung in this CLP model. Because lung tissue nitrite/nitrate levels did not change significantly, organs other than the lungs may be responsible for producing the increased nitric oxide during sepsis. The chronic use of NAC needs further investigation for its possible antiapoptotic potential in septic states besides its documented antioxidant and antiinflammatory effects.

N-Acetylcysteine for Preventing Pump-Induced Oxidoinflammatory Response During Cardiopulmonary Bypass

PurposeTo investigate the effect of N-acetylcysteine on preventing pump-induced oxidoinflammatory response during cardiopulmonary bypass (CPB).MethodsForty patients undergoing coronary artery bypass grafting (CABG) were randomly divided into a study group (n = 20), given 50 mg kg−1N-acetylcysteine intravenously for 3 days, and a control group (n = 20) given saline. Serum samples were collected for measurement of myeloperoxidase (MPO), malondialdehyde (MDA), interleukin-6, Α1-acid glycoprotein (AAGP), and C-reactive protein (CRP) during surgery and postoperatively.ResultsThe MPO and MDA values showed a similar pattern during and after CPB in the study group, with significantly less variance than in the control group. Interleukin-6 showed similar patterns in the two groups, but the data from 30 min after the start of CPB and from 6 h post-CPB were significantly different. The AAGP and CRP values were both elevated during CPB in the two groups without a significant difference, but 6 and 24 h post-CPB, the values were significantly higher in the control group than in the study group.ConclusionsN-Acetylcysteine decreased pump-induced oxidoinflammatory response during CPB, suggesting that it could be a novel therapy for assisting in the prevention of CBP-induced oxidoinflammatory damage.

Decreased Serum Total Antioxidant Status and Erythrocyte-Reduced Glutathione Levels Are Associated with Increased Serum Malondialdehyde in Atherosclerotic Patients

BACKGROUND Coronary artery disease is the significant cause of morbidity and mortality today. The treatment of coronary artery disease is improving, but its prevalence is increasing. Both primary and secondary prevention measures are of vital importance. METHODS In this study, vitamin C, total antioxidant status, malondialdehyde in serum and erythrocyte-reduced glutathione levels were investigated in patients with atherosclerosis and compared with those of controls. Levels of serum MDA, vitamin C, total antioxidant status, and erythrocyte-reduced glutathione were determined according to the methods of Yagi, Bauer et al., Miller et al., and Beutler, respectively. RESULTS Erythrocyte-reduced glutathione, serum vitamin C, total antioxidant status, and malondialdehyde values of both patients with atherosclerosis and controls were as follows: 2.80 +/- 0.76, 5.82 +/- 0.67 micromol GSH/g Hb; 1.00 +/- 0.19, 1.62 +/- 0.30 mg/dL; 0.86 +/- 0.14, 1.43 +/- 0.16 mmol/L, and 4.26 +/- 0.9, 1.02 +/- 0.80 nmol/mL, respectively. There was a decrease in the levels of serum vitamin C, erythrocyte-reduced glutathione, and total antioxidant status (p <0.001), and increase in the levels of serum malondialdehyde (p <0.001) in patients with atherosclerosis when compared with those of controls. CONCLUSIONS Because treatment of atherosclerosis is improving, our results suggest that antioxidant agents may have preventive roles in the formation of atherosclerosis.

3-Nitrotyrosine in atherosclerotic blood vessels

Abstract The effect of peroxynitrite on the development of atherosclerosis is one of the major foci of recent studies. Here, the cytotoxic effect of peroxynitrite was investigated by quantitatively measuring nitrated tyrosine, 3-nitrotyrosine (3-NT) levels in atherosclerotic blood vessels. Atherosclerotic vessels were obtained from the patients who underwent either coronary artery or peripheric artery bypass surgery. Internal thoracic arteries of the patients were treated as non-atherosclerotic control vessels. 3-NT was measured by reverse-phase HPLC and plasma nitrite-nitrate levels were measured by spectrophotometry. 3-NT levels were significantly elevated in atherosclerotic vessels (46.6±23.3 nmol/mg protein, n = 15; p < 0.001) in comparison to control vessels (15.8±2.5 nmol/mg protein, n = 10). Vessel 3-NT correlated weakly with plasma nitrate levels (r = 0.38). Thus, atherosclerotic arteries have higher 3-NT levels than non-atherosclerotic blood vessels.

Alcohol-induced lung damage and increased oxidative stress.

Background: Alcohol-induced lung damage may be associated with increased oxidative stress. Objective: Our aim was to investigate alcohol-induced changes in the biochemistry and histopathology of the lung. Methods: Rats were divided into two groups, a control group and an ethanol group. The ethanol group received 2 g/kg ethanol (total: 3 ml) intraperitoneally. The controls were given the same amount of saline via the same route. Three hours later, the rats were sacrificed, and blood and lung tissue samples were obtained. Oxidative stress was assessed by measuring the levels of erythrocyte reduced glutathione (GSH), tissue malondialdehyde (MDA), myeloperoxidase (MPO) and Na+-K+ ATPase. Histopathologic evaluation of the lung tissues was also performed. Results: In the ethanol group, serum and tissue MDA levels and MPO activities were increased (p = 0.007, p = 0.001 and p = 0.000), and lung tissue Na+-K+ ATPase activities and erythrocyte GSH were decreased (p = 0.001 and p = 0.000) compared to the controls. Histopathologic examination demonstrated alveolocapillary thickening, alveolar degeneration, leukocyte infiltration and erythrocyte extravasation in the lungs of the ethanol group (p < 0.05). Conclusion: These results suggest that high-doseacute alcohol administration aggravates systemic and local oxidative stress leading to acute lung injury, ranging from mild pulmonary dysfunction to severe lung injury. It should be borne in mind that rapid onset of the acute respiratory distress syndrome (ARDS) may also be due to increased oxidative stress following alcohol abuse, especially when ischemic disturbances, e.g. coronary heart disease, acute ischemia of the extremities and traumatic accidents, are concomitantly present. Therefore, precautions against ARDS may prevent morbidity and mortality in alcohol-induced lung damage in at-risk patients.

Effects of trimetazidine on tissue damage in kidney after hindlimb ischemia-reperfusion.

The objective of this study was to investigate the effects of trimetazidine (TMZ) on tissue damage in kidney after hindlimb ischemia-reperfusion (I/R), by assessing blood biochemical assay and histopathological analysis. Adult male Wistar rats were divided into two groups. TMZ 10 mg kg(-1)day(-1) was administrated twice a day for 10 days to the treatment group (group T, n=10). Sham group was given only 5% gum arabic (group S, n=10). On 11th day of treatment, 8h I/R period was performed on right hindlimb of the rats. At the end of reperfusion period, a 5 ml blood withdrawn from ascending aorta for biochemical assays and their right kidneys were harvested for histopathological examination. Superoxide dismutase, Na(+)-K(+) ATPase, and reduced glutathione levels were significantly increased in group T (P<0.001). On the other hand, myeloperoxidase and malondialdehyde levels were significantly less in group T than group S (P<0.001). Kidneys from the sham-operated group displayed intense leukocytic infiltration in histopathological examination. These overall results strongly suggested that TMZ contributes renal protection from hindlimb I/R injury by decreasing systemic oxidative stress.

Effects of Daflon on oxidative stress induced by hindlimb ischemia/reperfusion.

The objective of this study was to investigate the effects of Daflon 500 mg on tissue damage in kidney after ischemia/reperfusion hindlimb, by assessing blood biochemical assay and histopathological analysis. Rats were given Daflon 80 mg x kg(-1) x day(-1) for 10 days. On 11th day of treatment, 4h ischemia followed by 4 h reperfusion period was performed on right hind limb of the rats. Control groups were given only arabic gum and were subjected to same ischemia/reperfusion period. At the end of reperfusion period, erythrocyte superoxide dismutase, Na(+)-K(+) ATPase and reduced glutathione levels were increased in the rats erythrocytes in Daflon group (P<0.01, for all). On the other hand, serum myeloperoxidase and malondialdehyde levels were significantly lower in the Daflon-received rats (P<0.01, for all). Histopathological studies demonstrated that, there was a prominent tubulointerstitial injury with loss of brush border and this degeneration was accompanied by segmental glomerular degeneration also for both control and Daflon group. Daflon-received group animals displayed significantly less periglomerular and perivascular leukocytic infiltration (P=0.015). These overall results suggest that Daflon contributes renal protection from hind limb ischemia/reperfusion injury in some degree, by decreasing systemic oxidative stress.

Comparison and evaluation of experimental mediastinitis models: precolonized foreign body implants and bacterial suspension inoculation seems promising

BackgroundPost-sternotomy mediastinitis (PSM) is a devastating surgical complication affecting 1–3% of patients that undergo cardiac surgery. Staphylococcus aureus is one of the most commonly encountered bacterial pathogen cultured from mediastinal samples obtained from patients with PSM. A component of the membrane of the gram positive bacteria, lipoteichoic acid, stimulates the blood monocytes and macrophages to secrete cytokines, radicals and nitrogen species leading to oxido-inflammatory damage. This seems to be responsible for the high mortality rate in PSM. For the evaluation of the pathogenesis of infection or for the investigation of alternative treatment models in infection, no standard model of mediastinitis seems to be available. In this study, we evaluated four mediastinitis models in rats.MethodsThe rats were divided into four groups to form different infection models. Group A: A suspension of 1 × 107 colony-forming units Staphylococcus aureus in 0,5 mL was inoculated from the right second intercostal space into the mediastinum. Group B: A hole was created in the right second intercostal space and a piece of stainless-steel implant with a length of 0.5 cm was inserted into the mediastinum and a suspension of 1 × 107 cfu bacteria in 0,5 mL was administered via the tail vein. Group C: Precolonized stainless-steel implant was inserted into the mediastinum. Group D: Precolonized stainless-steel implant was inserted into the mediastinum and the bacteria suspension was also injected into the mediastinum. On the 10th day, rats were sacrificed and the extension of infection in the mediastenae was evaluated by quantitative cultures. Myeloperoxidase activity (MPO) and malondialdehyde (MDA) levels were determined in the sera to evaluate the neutrophil activation and assess the inflammatory oxidation.ResultsThe degree of infection in group C and D were 83.3% and 100% respectively (P < 0.001). MDA levels were significantly higher in these two groups than the others (P < 0.001).ConclusionInfected implants and high bacterial concentration administration were the two important components that played a significant role in the outcome of a successful infection in mediastinum in a rat model.

The effect of ethylenediaminetetraacetic acid on calcific degeneration in bovine pericardium

Calcification is the most frequent cause of the clinical failure of bovine pericardium bioprosthetic valves, preventing their widespread application for surgical treatment. The aim of this study was to minimize calcific degeneration in bovine pericardium by using a chelating agent, ethylenediaminetetraacetic acid (EDTA). Freshly excised bovine pericardium was dissected free from adhering fat tissue and cut into 1-cm2 pieces that were rinsed in phosphate-buffered saline solution (PBS) and transferred into 4°C PBS containing 1% glutaraldehyde (GA) for initial fixation, then allocated into two groups. Group I received the same treatment in a fresh solution for 5 more days. Group II underwent an additional fixation step in PBS solution (pH 7.4, 37°C) containing 11% EDTA for a period of 48 h (30 ml/g tissue) and was then transferred into freshly prepared PBS + 1% GA solution at 37°C for another 3 days. To investigate the calcification rate, pericardial patches were inserted into the dorsal pouches of 25 male Wistar rats for 21 days. Calcium levels were measured with an atomic absorption spectrophotometer and examined histo-pathologically. The calcium content of EDTA-treated pericardium (Group II), 21 ± 3.8 µg/mg, was significantly lower than that of Group I, 43.3 ± 9.2 µg/mg. Assessment of the degree of calcification in the histological sections generally agreed well with the results of the chemical analyses. Calcium deposition in Group I samples were found to be solid mineral depositions, whereas in the Group II pericardial samples, only smaller traces of calcium were found. Calcific degeneration in bovine pericardium can be reduced by using chelates such as EDTA.

Combined Therapy of Teicoplanin and Caffeic Acid Phenethyl Ester (CAPE) in the Treatment of Experimental Mediastinitis in the Rat

Abstract Post-sternotomy mediastinitis affects 1-3% of patients undergoing cardiac surgery and is lethal in 10-47% of these patients. We investigated the effect of an antioxidant/anti-inflammatory agent, caffeic acid phenethyl ester (CAPE), in the attenuation of inflammatory response induced by methicillin-resistant Staphylococcus aureus (MRSA) infection in a rat experimental mediastinitis model. Rats, divided into six equal groups, received MRSA precolonized stainless steel wire pieces implanted into their mediastinal spaces. Control group and CAPE control group received saline and CAPE 10 μmol/kg.day−1 respectively, where Group A received a single dose of teicoplanin 24 mg/kg i.m. for the first day and then 12 mg/kg.day−1. Group B received teicoplanin as in Group A plus CAPE 10 μmol/kg. day−1 intra-peritoneally. Group C received teicoplanin 60 mg/kg i.m. for the first day and then 30 mg/kg.day−1 and Group D received teicoplanin as in Group C plus CAPE 10 μmol/kg.day−1. By the end of 14 days rats were sacrificed and serum malondialdehyde (MDA), myeloperoxidase (MPO), nitric oxide (NO), urea and creatinine levels were evaluated. Mediastinal organ tissues were collected for histopathological analysis. Infection rates in all the drug-treated groups were lower than the control groups (P = 0.002) but statistical significance was attained only between the groups A and D (P = 0.018). In connective tissues and the peribronchial area polymorphonuclear leukocytic (PNL) infiltration in the treatment groups, although becoming very close, did not reach statistical significance (P = 0.053, P = 0.075, respectively). PNL infiltration especially in the peribronchial tissues of the Group B animals was found to be significantly less than the Control and CAPE Control groups with P values of 0.013 and 0.010, respectively. MDA and MPO levels were significantly lower in the treatment groups (P < 0.001 and P < 0.001 respectively). Levels of the degradation products of NO were lower in treatment groups compared to two control groups (P = 0.003, P = 0.005). NO levels in Group D were lowest among all treatment groups (P = 0.001). It has been demonstrated that although bacterial colonization can be controlled in mediastinitis, the inflammatory response persists. The combination of an antioxidant / anti-inflammatory agent, CAPE, added to standard antibiotic therapy might be effective in the treatment of post-sternotomy mediastinitis due to MRSA.