Ozlen Bagdatoglu

THE EFFECTS OF DEXAMETHASONE ON LIPID PEROXIDATION AND NITRIC OXIDE LEVELS ON THE HEALING OF TRACHEAL ANASTOMOSES: AN EXPERIMENTAL STUDY IN RATS

Corticosteroids are shown to have deleterious effects on wound healing for various tissues. Arginine metabolism and nitric oxide (NO) synthesis play an important role in many aspects of inflammation and wound healing. The study was designed to evaluate the relationship of dexamethasone impaired healing of tracheal anastomoses to NO metabolism and lipid peroxidation. Forty-two adult Wistar rats were randomly divided into five groups. The animals underwent tracheal transection and primary anastomoses. The groups were assigned as follows: Group I (GI) (sham, N = 6); Group II (GII) (control, N = 6); Group III (GIII), dexamethasone, 0.1 mg kg(-1) per day, intramuscularly for a week (N = 10); Group IV (GIV), dexamethasone, 1 mg kg(-1) per day, intramuscularly for a week (N = 10); Group V (GV), dexamethasone, 6 mg kg(-1) intramuscularly as a single dose (N = 10). After 7 days, bursting pressure was used to evaluate anastomotic healing. Serum nitrite/nitrate and malondialdehyde (MDA) levels were measured as an index of NO synthesis and lipid peroxidation, respectively. The bursting pressure significantly decreased in GIII and GIV when compared to the control group. The difference between GIII and GIV was also statistically significant. Nitrite/nitrate and MDA levels of GIII were found to be significantly higher than the control group. Also, the difference was found to be statistically significant between GIII and GIV in regard to nitrite/nitrate levels. The present study demonstrates that daily administration of dexamethasone for a week inhibits NO synthesis in a dose-dependent manner on tracheal anastomotic healing. Besides the generally accepted evaluation parameters including bursting pressure and hydoxyproline content; NO and MDA levels may be helpful in the assessment of wound healing especially for the investigation of impairment mechanism.

The effects of carnitine on distally-burned dorsal skin flap: an experimental study in rats

OBJECTIVE In ischemia and burn injuries, there are major alterations threatening tissue survival. Increased energy flow requirements are among the major problems in these disorders. Carnitine is an endogenous cofactor, which has a regulatory action on the energy flow from different oxidative sources. The purpose of this study was to determine the effects of carnitine in an experimental flap model. Biochemically, nitric oxide (NO), malondialdehyde (MDA), and acetylcholinesterase levels, and histopathologically tissue examination under light microscope were studied. METHODS In the rat dorsal skin, a 10 cm x 3 cm flap was marked. The most distal 3 cm x 3 cm of the flap was burned to full-thickness. The dorsal flap was elevated, and sutured back to its original site. Sixteen rats were divided into two groups (a control (1) and a study group (2)), consisting of eight rats in each. While the animals in the control group were just followed, the animals in the study group were administrated carnitine with a dose of 100 mg/kg per day for 7 days. RESULTS At the end of the experiment: the mean surviving areas of the flaps were 15.22 cm(2) (50.73%) in group 1, 20.53 cm(2) (68.43%) in group 2, and the difference was statistically significant (P=0.008). In the analysis of blood samples; the mean levels of NO were 22.63 and 40.78 micromol/l; of MDA were 6.74 and 3.79 ng/ml; and of acetylcholinesterase were 136.14 and 222.85 U/l in groups 1 and 2, respectively. The differences in the levels of NO (P=0.001), MDA (0.027) and acetylcholinesterase (P=0.006) were statistically significant. Histopathological examination revealed a full-thickness muscle necrosis in addition to skin tissue in the control group, while healing tissue was present with marked cellularity including mixed inflammatory cells and fibroblast proliferation with an increased vascularity in the form of capillary budding in the study group. CONCLUSION Carnitine has a positive effect in such a model, particularly in preventing the progressive effect of burn, and limiting the necrosis in the full-thickness burned part.

Genetic Polymorphism of VEGF-1154 (A/G) in Laryngeal Squamous Cell Carcinoma

BACKGROUND Angiogenesis has been shown to be increased in various human tumors including head and neck squamous cell carcinoma (SCC). Vascular endothelial growth factor (VEGF) is thought to be one of the most important angiogenic factors in tumorigenesis. In this study, we aimed to investigate whether polymorphism of VEGF-1154 (A/G) genotypes are associated with the risk of laryngeal SCC. METHODS A prospective, randomized, case-control study in a tertiary university hospital was done. The study group consisted of 57 Caucasian patients with laryngeal SCC and 89 control subjects. Blood samples were obtained before surgery or from the patients under follow-up to 5 years after surgery. VEGF-1154 (A/G) genotypes were detected by real-time polymerase chain reaction with thermal cycler system. RESULTS According to the high-risk (GG) genotype, the difference between the patient and control groups was statistically significant (OR 0.43, 95% CI=0.19-0.95, p=0.037). CONCLUSIONS GG genotype of the VEGF gene may increase the risk of laryngeal SCC in this population. VEGF gene polymorphism may be an important potential genetic and therapeutic marker of laryngeal SCC.

N-acetylcysteine protects the rats against phrenic nerve dysfunction in sepsis.

This study investigates the association of oxidative stress with the function of the phrenic nerve and inquires whether N-acetylcysteine (NAC) may counteract the possible detrimental effects. Thirty rats were divided into three groups: sham, cecal ligation and puncture (CLP), and CLP plus NAC treatment. Sepsis was produced by the CLP procedure. NAC was administered at 70 mg/day for 7 days. Electrophysiology was evaluated by the needle electromyography of the diaphragm and phrenic nerve conduction study. Oxidative stress was evaluated by malondialdehyde (MDA), nitrite/nitrate (NN), and reduced-glutathione (ReGSH) levels and myeloperoxidase (MPO) and catalase (CAT) activities in the phrenic nerve. In the CLP group, ReGSH and CAT were decreased (P = 0.0001, P = 0.07, respectively); and MDA, MPO, and NN were increased (P = 0.02, P = 0.0001, P = 0.043, respectively), compared with the sham group. NAC administration increased the ReGSH (P = 0.036) and decreased the MDA, MPO, and NN (P = 0.008, P = 0.01, P = 0.032, respectively), compared with the CLP group. In the CLP group, electrophysiology revealed reductions in the number of motor unit action potentials (P = 0.0001) and prolongations in the latency of the compound nerve action potential (P = 0.0001), indicating phrenic nerve neuropathy. NAC administration significantly ameliorated these electrophysiological alterations (P = 0.011, P = 0.0001, respectively), compared with the CLP group. The present results showed that intraabdominal sepsis is closely associated with phrenic nerve neuropathy. In addition, NAC administration protects the rats against the detrimental events of sepsis.

The urinary 5-hydroxyindole acetic acid and plasma nitric oxide levels in irritable bowel syndrome: a preliminary study.

Background and Aims: Postprandial increase of 3-hydroxytryptamine (5-HT) has been implicated in irritable bowel syndrome (IBS). There is evidence that nitric oxide (NO) may act as a mediator of 5-HT-evoked secretions in the colon. Our aim is to investigate the role of urinary 5-hydroxyindole acetic acid (5-HIAA) and plasma NO levels (with diarrhoea) in IBS patients. Methods: Nineteen (with constipation) IBS patients (group 1), 22 IBS patients (group 2) and 18 healthy controls (group 3) were included in the study. The diagnosis of IBS was made according to the Rome I Criteria. The urine was collected for determination of 5-HIAA and venous blood was collected from each subject for the measurement of plasma NO levels. Results: The levels of urinary 5-HIAA mmol/day and plasma NO mmol/l of group 1 (22,4±2,2 and 29,4±2 respectively) were significantly higher than group 3(14,2 ± 2,3 and 21,3 ± 2,1 respectively) (p =0,036 and p =0,019 respectively). The NO level of group 1 was also significantly higher than group 2(21,8 ± 1,9) (p = 0,021). The 5-HIAA level of group 1 was higher than group 2 (15,2, ± 2,1) and the difference was marginally significant (p = 0,055). There was no difference between group 2 and group 3 with respect to 5-HIAA and NO levels. Conclusions: The results of this preliminary study lend support to the involvement of 5-HT in some symptomatology of diarrhoea predominant IBS. Furthermore, NO may be one of the effector mediators of the 5-HT-induced symptoms in these patients.

Effect of Trapidil in Ischemia/Reperfusion Injury on Rat Small Intestine

To investigate the effect of trapidil on the intestinal ischemia-reperfusion injury, we determined malondialdehyde levels as a indicator of lipid peroxidation, nitrite and nitrate levels as reflections of nitric oxide metabolism, and histopathological findings in rats subjected to 40 min of ischemia and 2 h of reperfusion. Histopathological evaluation demonstrated that trapidil treatment has a protective effect on intestinal mucosa and reduces inflammatory cell infiltration in lamina propria, which is consistently noted in the untreated ischemic and reperfused intestines. Possible mechanism of this effect may be explained by the reduced lipid peroxidation (mean malondialdehyde level 3.72 - 0.27 vs. 6.13 - 0.44, p < .0001) and improved nitric oxide metabolism (mean nitrite plus nitrate 38.21 - 2.33 vs. 30.14 - 1.47, p = .022).

Bronchoscopy induces intestinal mucosal barrier dysfunction: a possible role for nitric oxide.

OBJECTIVE This study investigates the effect of bronchoscopy on intestinal mucosal barrier function and its association with intestinal nitric oxide production. METHODS 30 rats were used. The study group (n=15) underwent rigid bronchoscopy. At 24 h following bronchoscopy, ileal nitrite/nitrate levels were evaluated. The ileum was also examined for mucosal damage, and graded according Chius histologic injury scale. RESULTS In the bronchoscopy group, the ileal nitrite/nitrate levels were significantly higher than those of controls (398.5 +/- 85.1 and 44.5 +/- 6.6 nmol/g tissue, respectively, P=0.001). In the bronchoscopy group, the mucosal damage was significant, compared with those of controls (mean ranks, 22.8 and 8.2, P<0.0001). The changes varied from denuded villi and dilated capillaries to significant architectural distortion, lamina propria disintegration, ulceration and hemorrhage. Significant correlation was found between ileal nitrite/nitrate levels and mucosal damage in the bronchoscopy group (rs=0.56, P=0.03). CONCLUSION This study suggests that bronchoscopy induces intestinal mucosal barrier dysfunction in association with excess intestinal nitric oxide production. These events may be involved in mechanisms responsible for bacterial translocation after bronchoscopy.

Association of the platelet glycoprotein Ia C807T/G873A gene polymorphism and thrombosis in Behçet patients.

Thrombosis is a common complication of Behçet disease and the pathogenic mechanism of thrombotic tendency in Behçet disease is not well known. Several platelet membrane glycoprotein gene polymorphisms have been identified as risk factors for thrombosis. This study aimed to evaluate the possible role of the GP Ia C807T/G873A polymorphism as a risk factor for thrombosis in Behçet disease. We determined the prevalence of platelet glycoprotein Ia C807T/G873A gene polymorphism in Behçet patients. Genomic DNA was obtained from 20 patients with Behçet disease and 61 controls. All individuals were of Turkish ancestry and were genotyped for the GP Ia C807T/G873A polymorphism with real-time PCR method by LightCycler system. The 807 CC, CT and TT genotypes corresponded with 873 GG, GA and AA genotypes, respectively. Complete linkage between the 807 and 873 sites was found in all samples. The 807CC(873 GG), 807CT(873GA), 807TT(873AA) genotypes found to be 45.9%, 45.9% and 8.1% in controls and 30.0%, 55.0% and 15.0% in patients with Behçet disease, respectively. The Odds Ratio for BD (OR = 1.97; 95% confidence interval (CI): 0.42-9.13) is high for the 807 TT genotype compared with controls. Thrombosis was found in 7 cases of Behçet disease group: five cases have 807CT, one case has 807TT genotype and one case has 807CC genotype. Our data indicate hat patients with BD are affected by the glycoprotein Ia gene 807TT genotypes and carrying 807T allele. The risk of thrombosis is significantly higher in patients who have 807TT and 807CT genotypes than in patients who have 807CC genotype.

Effects of trapidil on intestinal mucosal barrier function and bacterial translocation after intestinal ischemia and reperfusion in an experimental rat model

BACKGROUND Intestinal ischemia and reperfusion may be the primary triggers of mucosal barrier impairment, cytokine expression, and bacterial translocation (BT). Trapidil is a phosphodiesterase and platelet-derived growth factor inhibitor that reduces lipid peroxidation and inhibits the production of cytokines. OBJECTIVE The goal of this study was to assess whether trapidil might protect the intestinal epithelial barrier by inhibiting lipid peroxidation and proinflammatory cytokines by testing the effect of trapidil on intestinal barrier function in an experimental ischemia/reperfusion (I/R) rat model. METHODS Trapidil was used in a rat model of intestinal barrier dysfunction caused by intestinal ischemia for 40 minutes followed by reperfusion for 12 hours. To do this, the rats were randomized to 1 of 4 treatment groups, as follows: (1) sham surgery and saline administration (1 mL IV) (Sham group); (2) sham surgery and trapidil administration (8 mg/kg IV) (Sham+T group); (3) I/R and saline administration (1 mL IV) (I/R group); and (4) I/R and trapidil administration (8 mg/kg IV) (I/R+T group). Intestinal barrier function was assessed by histopathologic examination, blood malondialdehyde (MDA) level, and BT. RESULTS The I/R+T group showed significantly less incidence of BT compared with the I/R group in the liver and reduced median colony count of translocated bacteria in mesenteric lymph nodes, liver, spleen, and peritoneum compared with the I/R group. Furthermore, the mean blood MDA level demonstrated that lipid peroxidation was significantly decreased in the I/R+T group compared with the I/R group. Histopathologic findings revealed that trapidil administration before reperfusion preserved intestinal mucosal integrity and inhibited the infiltration of inflammatory cells into the intestines. CONCLUSIONS In this experimental study, a correlation seemed to exist between intestinal barrier dysfunction and BT. Intestinal barrier dysfunction may allow a large amount of bacteria to pass from the gut to distant organs. Trapidil treatment may inhibit BT by preserving intestinal barrier by inhibiting thromboxane A2, lipid peroxidation, proinflammatory cytokines, and stimulated prostacyclin. Future dose- and time-dependent studies will be helpful in revealing the effects of trapidil on BT.

Effects of α-MSH on ischemia/reperfusion injury in the rat sciatic nerve.

Background: Ischemia/reperfusion (I/R) causes the production of toxic free radicals and leads to pathological changes in nerve tissue. We investigated the effect of alpha-melanocyte stimulating hormone (α-MSH) in a rat model for sciatic nerve I/R and discuss the possible cytoprotective and antioxidant mechanism of α-MSH against ischemic fiber degeneration. Methods: Experiments were performed using 42 adult male Wistar rats. Rats were divided into six experimental groups: control group, ischemia group, I/R groups, and α-MSH treated groups. Ischemia was produced by clamping of the femoral vessels. Immediately after ischemia that lasted 3 h, 75 μg/kg of α-MSH was administered subcutaneously before reperfusion and the tissue malondialdehyde (MDA) level was evaluated as an indicator of lipid peroxidation in groups with different reperfusion periods. Results: The reperfusion injury did not begin in the first hour of reperfusion after 3 h of ischemia, and MDA levels increased on the first day of reperfusion. During the first day, blood MDA levels were decreased in the α-MSH group compared to the control group. The tissue from animals pre-treated with α-MSH showed fewer morphological alterations. Myelin breakdown was significantly diminished after treatment with α-MSH, and the ultrastructural features of axons showed remarkable improvement. Two-way analysis of variance was used for comparing three or more groups. When a significant difference existed, the post-hoc multiple-comparison test was applied to demonstrate the differences. Conclusions: The results confirm that pre-treatment with α-MSH after ischemia protected the peripheral nerves against I/R injury.