Hale Tufan

Comparison of the protective effects of melatonin and amifostine on radiation-induced epiphyseal injury.

Purpose: We compared the effects of amifostine and melatonin in preventing radiation-induced epiphyseal growth plate injury in rats. Materials and methods: Four-week-old (65–85 g), growing male Sprague-Dawley rats were randomly assigned to receive radiation alone, at 25 Gy in three fractions (group R), or this dose of fractionated radiation proceeded by prophylactic amifostine 200 mg/kg i.p. (group A), melatonin 15 mg/kg i.p. (group M), or amifostine + melatonin (group AM). The right rear extremity of each animal was irradiated while the contralateral leg was shielded from radiation, as a control. Bone growth based on the length of the tibia, femur, and overall limb was calculated 6 weeks after the treatment. Results: In groups R, A, M, and AM, the mean growth loss (GL) for the overall limb was 56.9 ± 8.1%, 46.8 ± 7.7%, 36.6 ± 4.3%, and 38.5 ± 5.1%, respectively. The limb length discrepancies (LLD) in groups R, A, M, and AM were 13.8 ± 1.4%, 10.5 ± 0.3%, 7.4 ± 0.7%, and 8.8 ± 1.1%, respectively. Differences in LLD were significant between each treatment group and group R (range: p = 0.0001–0.001). Differences in either of mean GL and LLD were not significant between groups M and AM; however both of these groups had significantly less GL and LLD than group A. Conclusions: We observed a superior radioprotective function of melatonin over amifostine in preventing radiation-induced epiphyseal growth plate injury, without any increase in radioprotective effect by adding amifostine to melatonin.

The Bactericidal and Morphological Effects of Peroxynitrite on Helicobacter pylori

Peroxynitrite (ONOO−) is correlated with the pathogenesis of Helicobacter pylori‐induced peptic ulcer diseases. We aimed to investigate the time‐ and concentration‐dependent bactericidal and morphological effects of ONOO− on H. pylori. Authentic ONOO− was synthesized as quenched‐flow method. A stock culture of H. pylori NCTC 11637 was exposed to different concentrations of ONOO− (0.1–40 µmol/L) or decomposed ONOO− or fresh medium. Samples were taken at 0, 15, 30, 60, and 120 minutes, for the evaluation of viable bacteria and bacterial morphology with gram strain and transmission electron microscopy. Decomposed ONOO− showed no bactericidal activity against H. pylori. ONOO− application caused a decrease in the number of viable bacteria within the first 15 minutes. The significant conversion of H. pylori from spiral form to coccoid form was determined with 10 µmol/L of ONOO−, and higher concentrations caused lysis of the cells. Separation of cell wall, bleb formation, vacuolization, decrease of secretory granules, and lysis of bacteria were the morphological effects of ONOO− on H. pylori. Because the morphology of the bacteria is one of the important factors in virulence; peroxynitrite‐related morphological effects might have an impact in the progress of the H. pylori‐induced peptic ulcer diseases.

The effects of systemic alpha-1 adrenergic antagonists on pupil diameter in rats.

Purpose: To investigate the effects of alpha-1 adrenergic blockers on pupil diameter (PD) in rats. Methods: Four groups, with 10 rats each, were designed to receive terazosin, tamsulosin, doxazosin, and no medication. Dilated pupil diameter (PD) measurements were performed 24 hr before, 24 hr after, and 30 days after the initiation of medication, and after 30 days of washout. The intergroup and intragroup differences in PD were evaluated using one-way ANOVA and Wilcoxon signed rank test, respectively. Results: In day 1, PD decreased in both eyes significantly only in tamsulosin and doxazosin groups, but these effects became insignificant at 30 days of treatment (p > 0.05). The control group showed no significant difference in PD (p > 0.05). PD values returned to baseline after the washout period in all groups. Conclusions: A significant reduction in PD occurred in two of the three groups with alpha-1 adrenergic blockers (tamsulosin and doxazosin), but this effect was not sustained at 30 days. Further functional and structural studies of the iris are needed to determine the clinical significance of these findings.

Evaluation of neointimal hyperplasia on tranilast-coated synthetic vascular grafts: an experimental study.

Tranilast is an antiallergic drug that interferes with proliferation and migration of vascular smooth muscle cell induced by platelet-derived growth factor (PDGF) and transforming growth factor-β1 (TGF-β1). We investigated the local effect of tranilast on neointimal hyperplasia using tranilast-coated prosthetic grafts. The inner sides of the thin-walled polytetrafluoroethylene (PTFE) grafts were coated with chitosan and tranilast containing chitosan solution. Wistar albino rats (32) were used in the study. Patches (1 × 2 mm) for vascular grafts were prepared. Three groups were tested: group 1 (n = 12; tranilast coated), group 2 (n = 10; adhesive-only film-layer–coated), and group 3 (n = 10; normal ePTFE patch grafts sutured to the carotid arteries of the rats). Recipient sites of the carotid arteries were excised 4 weeks after surgery. All sections were examined histologically for graft patency, thrombus formation, and neointimal thickness. Expression of PDGF, fibroblast growth factor, and TGF-β1 on cross-sections of the neointima were evaluated by immunohistochemistry. No significant differences were found regarding mean neointimal thicknesses. PDGF and TGF-β-1 expressions were significantly lower in group 1. Although a decrease in local effect of tranilast was observed for growth factor expressions at a drug concentration of 0.05 mg/cm2, a significant reduction in neointimal hyperplasia was not achieved. The coating concentration of 0.05 mg/cm2 may have been too low to produce an antiproliferative effect. Given our promising results, further studies are recommended and planned using different drug concentrations and time intervals.

Effect of manual bowel decompression (milking) in the obstructed small bowel

BACKGROUND Mechanical intestinal obstruction is a frequently encountered problem in general surgery. One of the frequently used techniques for surgical decompression, so-called milking, is to caress the intestinal contents cephalad into the stomach or caudally into the colon. The aim of our study was to examine the functional, morphologic, and microbiologic effects of manual bowel decompression (milking) in the obstructed small bowel. METHODS Six rats in the milking (M) group (obstructed and decompressed manually), 6 in the control (C) group (obstructed only), and 5 rats in the sham (S) group (laparotomy and evisceration) underwent surgery. Muscle contractility, gastrointestinal dye transmission, histopathologic changes of ileum, and bacterial translocation were analyzed. RESULTS The contractile response of intestinal segments to acetylcholine was significantly less in group M compared with those of groups C and S (P < .05). The maximal contractile response to acetylcholine also was significantly lower in group M (P < .05). There was no statistically significant difference between the groups regarding the sensitivity of cholinergic receptors. Frequency of peristaltic movements, progression of Evans blue dye, histopathologic variables, and the quantitative evaluation (colony-forming units/gram of tissue) of isolated bacteria were not different among the groups. However, Escherichia coli in group M and Klebsiella spp in group S were the main isolated bacteria. CONCLUSIONS Although it reduces muscle contractility, a milking procedure in an intestinal obstruction model does not cause peristaltic deterioration, histopathologic or inflammatory changes, or alterations in the degree of bacterial translocation.

An alternative method of using an interpositional silicone sheet in tissue expansion.

To reduce the rate of complications in tissue expansion, we placed a silicone sheet between the expander and the tissue above it in a rat model. In the rats in group 1 (n = 10), the expanders were placed under the dorsal skin. The expanders were inflated with up to 45 mL of saline solution. In group 2 (n = 10), a silicone sheet was inserted between the tissue expander and the skin, after which the procedure used in group 1 was performed. The blood flow was reduced at the dome (center [C]) of the expanders in groups 1C and 2C to a degree greater than that in the expanded skin in groups 1 and 2 far periphery. However, the flow was significantly better in group 2C than in group 1C. Histologic analysis showed that the dermal and capsular tissues were significantly thicker in group 2C than in group 1C. In our opinion, placing a silicone sheet between the expander and the tissue above it seems to be beneficial. This may reduce the incidence of complications, especially the expander extrusion in this model.