Fikriye Yasemin Özatik

The Notch Signaling System Is Involved in the Regulation of Reparative Angiogenesis in the Zone of Stasis.

The Notch pathway ligand Delta-like 4 (Dll4) functions as an antiangiogenic factor, inhibiting vascular endothelial growth factor (VEGF)–induced angiogenesis. This function is documented in tumor and embryonic vasculature. However, its implication in burn wounds remains unexplored. Our objective was to explore the involvement of the Notch in the healing of zone of stasis burns. We hypothesized that anti-Dll4 therapy would prevent progressive necrosis in the stasis zone by promoting angiogenesis. Burns were created in 21 rats using the comb burn model. The Notch inhibitor N-[N-(3,5-difluorophenacetyl)-1-alanyl]-S-phenylglycine-t-butyl-ester was administered in the treatment group. Controls were given the same amount of solvent. Seven days after the burn, skin samples were evaluated for VEGF and Dll4 gene expressions. Immunohistochemical analysis was used for the assessment of vascular density, endothelial Dll4 expression, and apoptosis count. Histologic grading of tissue damage was performed. Circulating levels of VEGF and Dll4 were determined. VEGF and Dll4 mRNA levels were found to be simultaneously induced after the burn. In the treatment group, a significant increase in the number of vessels was observed. However, gross evaluation documented an expansion of necrosis to the zone of stasis with marked activation of apoptosis. Histologic assessment showed that the resultant vascular overgrowth was accompanied by extensive edema and abundant infiltration of leukocytes. We provide evidence for the involvement of Notch in the regulation of angiogenesis in zone of stasis burns.

Effects of tadalafil on hemorrhagic cystitis and testicular dysfunction induced by cyclophosphamide in rats.

Introduction: The protective and/or therapeutic potential of tadalafil (TDL) on cyclophosphamide (CP)-induced hemorrhagic cystitis (HC) and testicular dysfunction in rats was evaluated. Materials and Methods: The animals except from the control group were divided into four groups and treated with saline, or 1, 5 or 10 mg/kg TDL orally (CP, TDL1, TDL5 and TDL10 groups, respectively) before and after CP injection. Body and organ weights, sperm count, cGMP, nitric oxide (NO), IL-6 and IL-10 levels in serum and bladder tissue, and serum testosterone (T), LH and FSH levels were determined. The histological analysis of bladder and testis was performed and the number of apoptotic cells was determined. Results and Conclusion: The CP group had decreased cGMP and NO levels in the bladder, serum T level (p < 0.05) and sperm count (p < 0.001) and higher IL-6 levels in serum and bladder (p < 0.01). Treatment with TDL resulted in increased cGMP (p < 0.001), NO (p < 0.05) and serum T (p < 0.05) levels. Histological analysis of the CP group showed severe HC in bladder and testicular damage. TDL-treated animals showed a dose-dependent improvement in all of these histological impairments. In conclusion, a selective inhibitor of phosphodiesterase-5 enzyme, TDL, showed a protective and/or therapeutic effect on CP-induced HC and testicular dysfunction in rats.

Protective role of resveratrol on testicular germ cells in mice with testicular toxicity

Objective The aim of the present study was to investigate the possible beneficial effects of resveratrol in mice subjected to vinyl cyclohexene dieposide (VCD) -induced testicular toxicity. Material and methods A total of thirty- six Swiss albino male mice aged 28-days were used in the present study. The study was composed of two stages where mice which received or did not receive VCD (320 mg/kg/day) were administered resveratrol. The animals were assigned into control and resveratrol-treated groups in the first stage and into groups of VCD- and VCD+resveratrol-treated groups in the second stage. At the end of the experiments, relative testicular weight (TW/BW) and dry/wet weight of testis (TDW/TWW) were calculated. Histological analysis by hematoxylin and eosin (H&E) staining and immunohistochemical staining by BAX and Bcl-2 were performed. Serum testosterone, LH and FSH levels were measured by a commercially available ELISA kit. Results Resveratrol caused a dose-dependent increase in TW/BW and decrease in TDW/TWW (p<0.05). Resveratrol at a dose of 20 mg/kg resulted in an improvement in testosterone, LH and FSH levels in mice with VCD-induced testicular toxicity (p<0.001). Resveratrol also improved apoptotic index and epithelial cell height of testicular seminipherous tubuli significantly after VCD exposure (p<0.001). Conclusion Results of the present study suggest that resveratrol can be used as a protective and/or therapeutic agent particularly for cases with male infertility caused by testicular toxicity.

The Role of Cyclooxygenase Enzymes in the Effects of Losartan and Lisinopril on the Contractions of Rat Thoracic Aorta

OBJECTIVE It was suggested that prostaglandins which are synthesized by cyclooxygenase (COX) enzymes contribute to the actions of angiotensin-converting enzyme (ACE) inhibition and angiotensin AT1 receptor antagonism and there is an interaction between ACE signaling pathway and COX enzymes. We aim to investigate the role of COX enzymes in the effects of losartan, an angiotensin II (Ang II) receptor antagonist or lisinopril, an ACE inhibitor, on the contractions of rat thoracic aorta in isolated tissue bath. MATERIALS AND METHODS Responses of losartan (10-6, 10-5, 10-4 M), lisinopril (10-6, 10-5, 10-4 M), and non-selective COX inhibitor dipyrone (10-4, 7 × 10-4, 2 × 10-3 M) alone to the contractions induced by phenylephrine (Phe) (10-7 M), potassium chloride (KCl) (6 × 10-2 M), Ang II (10-8 M) and responses of losartan or lisinopril in combination with dipyrone to the contractions induced by Phe or KCl were recorded. RESULTS When used alone, dipyrone and losartan inhibited Phe, KCl, and Ang II-induced contractions, whereas lisinopril inhibited only Phe and Ang II-induced contractions. Inhibition of COX enzymes (COX-3, COX-3 + COX-1, COX-1+ COX-2 + COX-3 by dipyrone 10-4, 7 × 10-4, 2 × 10-3 M, respectively) augmented the relaxant effects of losartan or lisinopril. Also, dipyrone potentiated the effect of lisinopril on KCl-induced contractions. CONCLUSION We suggest that dipyrone increases the smooth-muscle relaxing effects of losartan or lisinopril and that COX enzyme inhibition may have a role in the enhancement of this relaxation.

Enhancement of vascular endothelial growth factor’s angiogenic capacity by the therapeutic modulation of notch signalling improves tram flap survival in rats submitted to nicotine

Abstract Background: Smoke of cigarettes, and specifically nicotine, has been shown to diminish pedicled transverse rectus abdominis musculocutaneous (TRAM) flap survival. Considering that Notch signalling through its ligand Delta-like 4 (Dll4) functions as anti-angiogenic factor by inhibiting the pro-angiogenic effects of vascular endothelial growth factor (VEGF), it is hypothesised that inhibition of the Notch would promote angiogenesis and increase TRAM flap survival in rats submitted to nicotine. Methods: Twenty rats were treated with nicotine for 28 days preoperatively. Thereafter, a pedicled TRAM flap was created in all animals. The Notch inhibitor N-[N-(3,5-difluorophenacetyl)-1-alanyl]-S-phenylglycine-t-butyl-ester was administered in animals of the treatment group. Animals in the control group were given the same amount of solvent. Five days after the surgery, viable flap areas were determined. Skin samples were evaluated for VEGF and Dll4 mRNA levels. Immunohistochemical analysis was used for the assessment of endothelial Dll4 expression. Vascular density was determined histologically. Plasma levels of VEGF and Dll4 were measured. Results: A significant improvement in TRAM flap surviving area was observed in the treatment group (53.50 ± 14.25%) compared with the controls (32.20 ± 9.15%). Immunohistochemical analysis revealed a significant increase in the number of Dll4 stained vessels in animals of the treatment group (9.2 ± 1.6) in comparison with the controls (5.7 ± 1.9). VEGF mRNA levels (0.22 ± 0.08) in the treatment group were significantly lower than those in the control group (0.36 ± 0.09). Conclusion: Notch inhibition significantly improved TRAM flap survival in animals exposed to nicotine by promoting VEGF-induced angiogenesis.