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The cytotoxic effect of chlorpyrifos ( CP) on human HepG2 cell lines and the protective role of melatonin were investigated. TD50 of CP for HepG2 cells was also determined. The viability of HepG2 cells decreased with CP treatment in a dose-dependent manner ( P < 0.05). Preincubation with melatonin prior to CP application caused an increase in cell viability ( P < 0.05). TD50 of CP for HepG2 was determined as 84.5 mu g/mL. A 1-hour melatonin treatment caused a decrease in TD50 from 84.5 to 34.1 mg/mL. The level of thiobarbituric acid reactive substance ( TBARS) and the activities of superoxide dismutase ( SOD), glutathione peroxidase ( GSH-Px) and catalase ( CAT) were determined in cell lines with or without melatonin administration to find out the possible mechanism of melatonin. CP caused a significant decrease in SOD, GSH-Px and CAT activities and an increase in TBARS level ( P < 0.05). Pre-incubation of cells with melatonin prevented an increase in TBARS. Melatonin also reduced the CP-caused inhibition of the activities of GSH-Px and CAT ( P < 0.05). It was suggested that CP shows a cytotoxic effect on HepG2 cell lines and melatonin can suppress cytotoxicity caused by CP with its antioxidant properties. Melatonin also reduces TD50 of CP for HepG2 cell lines. C1 Suleyman Demirel Univ, Tip Fak, Biyokimya AD, Sch Med,Dept Biochem, TR-32260 Isparta, Turkey. Pamukkale Univ, Fac Arts & Sci, Dept Biol, Denizli, Turkey.

A variety of experimental studies have demonstrated the neuroprotective effects of melatonin, based on its antioxidant activity. In a prospective randomized study, the effects of melatonin were investigated in experimental head trauma-induced oxidative stress in rabbits. The experimental study was performed on 30 rabbits. The animals were divided into three groups. Group I (sham procedure): a right parietal craniotomy was performed on each animal, and the dura mater was left intact. Group II: experimental brain trauma (EBT) was performed on each animal using a 1 cm inner diameter x 10 cm long glass tube, through which a 20 g weight (0.5 cm diameter) was dropped onto the brain at the craniotomy site, causing a contusional head trauma. Group III: the same EBT model was performed, but 2.5 mg/kg melatonin was injected intraperitoneally four times (total dose 10 mg/kg); these injections were performed 20 min before the operation, during the trauma, 1 h later and 2 h later. The rabbits were sacrificed after the EBT at 24 h after the brain trauma. The activities of the three principal antioxidant enzymes-catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px)-were determined, and the levels of malondialdehyde (MDA), a product of lipid peroxidation, and glutathione (GSH) were measured in brain homogenates. MDA levels were found to be higher in the EBT group than in the EBT+melatonin group or the sham procedure group. The SOD activity was found to be higher in the EBT group than in the sham procedure group. Enzymatic parameters (except for SOD) were significantly higher in melatonin-treated animals than in EBT animals. GSH levels in melatonin-treated animals were decreased compared with EBT animals. In conclusion, the data indicate that melatonin protects against free radical-mediated oxidative changes in brain tissue by boosting antioxidant enzymes, and in particular lowering lipid peroxidation in rabbits with EBT. C1 S Demirel Univ, Sch Med, Dept Neurosurg, Isparta, Turkey. Pamukkale Univ, Dept Neurosurg, Denizli, Turkey. S Demirel Univ, Sch Med, Dept Physiol, Isparta, Turkey. S Demirel Univ, Sch Med, Dept Clin Biochem, Isparta, Turkey.

Polypropylene mesh is an effective and widely used material in repairing abdominal wall defects, but it causes dense adhesions when in contact with abdominal viscera directly. As a consequence of this process intestinal obstruction and enterocutaneous fistula may develop. The purpose of the present study was to determine whether Seprafilm((R)), a bioresorbable translucent membrane, reduces abdominal visceral adhesions to polypropylene mesh and whether Seprafilm((R)) has any effects on peritoneal tissue hydroxyproline levels. Twenty-six adult Wistar rats were used. A full-thickness abdominal wall defect was created and cecal abrasions were created to induce adhesion formation in each animal. All of the abdominal defects were repaired with polypropylene mesh. In addition a Seprafilm((R)) membrane was laid over the abdominal viscera in the Seprafilm((R)) group (n = 13). The abdominal cavity was evaluated for adhesion formation, and peritoneal biopsies were taken for the measurement of tissue hydroxyproline levels at the 14th day. The use of Seprafilm((R)) resulted in significant reduction in the adhesion formation (P = 0.002) and a significant increase in peritoneal hydroxyproline level (P < 0.0001). These findings demonstrate that the increase of peritoneal hydroxyproline levels caused by Seprafilmg might play a role on the antiadhesive effects of Seprafilmg.

OBJECTIVES: To investigate the effects of pinealectomy on lipid peroxidation, antioxidant status and NMDA receptor subunits 2A and 2B concentrations in hippocampus.

Adapalene is a new naphthoic acid derivative with strong retinoid agonistic pharmacological properties. We propose that adapalene might contribute to the wound repairing process as is detected with retinoids. In this controlled study, the effects of topical adapalene, tretinoin and collagenase on full-thickness wound healing were compared in an animal model. Thirty-two adult male Wistar-Albino rats were used in the study. Two circular, full-thickness wounds were made for each animal with a standard 8-mm punch biopsy, on both sides of the midline on the back. No treatment was given to Group I rats (n:8) which comprised the control group. Tretinoin cream (0.1%) was applied topically in Group II (n:8), adapalene gel (0.1%) in Group III (n:8), and collagenase ointment in Group IV (n:8) once daily. On day 7, the wounds were photographed to measure the wound surface area. The wounds on the left side of each animal were excised on day 7, for histopathologic and biochemical examination. The treatments were continued for the right side wounds up to 14 days when the same procedure was repeated. In Group II, a significant decrease in hydroxylproline (HP) levels was detected at day 7 (p = 0.018), and an increase at day 14 (p = 0.002) compared to the control group. HP results revealed no difference either in Group III nor in Group IV versus control at day 7 or 14.

In an experimental model of sublethal hemorrhagic shock the effect of colloidal solutions on wound healing was studied. 20 ml/kg blood was drawn to achieve sublethal hemorrhagic shock. Resuscitation was performed with four different solutions; 0.9% NaCl, 10% dextran 40, 6% hydroxyethyl starch and 4% modified fluid gelatin. After anesthesia a full thickness skin incision of 2 cm in length was done on abdominal wall and sutured primarily with 4/0 polypropylene. After 5 days the incision on abdominal wall was excised. Tensile strength of the incision and hydroxyproline content of dry tissue were evaluated. It was observed that there were no differences in tensile strength values between groups (p>0.05). But hydroxyproline values were significantly lower in Group IV (58.47 mu g/ml) and Group LI (69.17 mu g/ml) (p

Aim To determine the age of development of bladder and bowel control and the frequency of enuresis, encopresis, and urinary infections in children with cerebral palsy.

This study investigated the levels of iron, zinc, and copper and their demolishing effects against lipid peroxidation in chronic giardiasis. Serum iron, zinc and copper levels, erythrocyte cytosolic superoxide dismutase activity, and malondialdehyde levels were measured in 34 children with chronic giardiasis and were compared with controls. The serum iron and zinc levels and erythrocyte superoxide dismutase activity were significantly lower, and malondialdehyde levels were significantly higher among the children with chronic giardiasis compared to the control group (p0.05). Consequently, the oxidant-antioxidant balance may tilt towards the oxidative side due to weakness of the antioxidant system in giardiasis. If early and proper treatment is not performed, free radical-mediated damage might occur in children with chronic giardiasis.

WOS: 000428138400013, In this study, we showed theoretically enhanced reflectance characteristics of nitride based blue Light Emitting Diode (LED) by adding GaN/AlxGa1-xN Distributed Bragg Reflector (DBR) between n-contact layer and GaN buffer layer. Calculation of reflectance and phase of electromagnetic waves are done by using Transfer Matrix Method (TMM). Light output of the LED structure is enhanced with 15 pair DBR, silver coating and optimizing GaN buffer, undoped GaN and n-contact GaN layer thicknesses. As a result of these, reflectance of the LED is increased from 92% to 98,6%. Finally, similar to 5% enhancement is showed in reflectance of the blue LED which results in increase in output power of LED., Scientific and Technological Research Council of Turkey (TUBITAK) [1007-113G103], This work was supported by the Scientific and Technological Research Council of Turkey (TUBITAK), Grant No: 1007-113G103.

WOS: 000401364700031, We studied the effect of the substrate temperature, in the range from 450 degrees C to 500 degrees C, on the required Zn to (Be + Mg) flux ratio for plasma-assisted molecular beam epitaxy growth of O-polar BexMgyZn1-x-yO on (0001)-GaN/sapphire templates. Achievement of single-crystalline BexMgyZn1-x-yO with improved optical and structural qualities required relatively high substrate temperatures, which necessitated the Zn to (Be + Mg) flux ratio to be increased from 3.9 at 450 degrees C to 8.3 at 500 degrees C. This resulted in a reduction of Mg incorporation from 25% to 15% for a fixed Be content of similar to 3%. With increasing Zn to (Be + Mg) ratio, 15K photoluminescence energy for the dominant emission remained unchanged at around 3.75 eV and 3.55 eV for the samples grown at 475 degrees C and 500 degrees C, respectively. These findings readily suggest a kinetic limitation of Mg and Be incorporation into wurtzite BexMgyZn1-x-yO lattice, resulting in the formation of second phase due mainly to the enhanced surface mobility of Mg adatoms and, therefore, an increase in the probability of the formation of Mg-rich clusters. An increase in the in-plane lattice parameter, deduced from the Reflection High Energy Electron Diffraction, at the onset of the phase segregation suggests the formation of the wurtzite phase MgO rich alloy(s). Published by AIP Publishing., Air Force Office of Scientific Research (AFOSR) [FA9550-12-1-0094]; Scientific and Technological Research Council of Turkey (TUBITAK), This work was supported by Air Force Office of Scientific Research (AFOSR) under Grant No. FA9550-12-1-0094. Ismail Altuntas, acknowledges the Ph.D. Grant support from the Scientific and Technological Research Council of Turkey (TUBITAK). The authors are thankful to Dr. Monavarian for his help while providing (0001) GaN/sapphire template.

WOS: 000463693300002, This paper presents high performance, GaN/InGaN-based light emitting diodes (LEDs) in three different device configurations, namely Top Emitting (TE) LED, conventional Flip Chip (FC) and Distributed Contact (DC) FC. Series resistances as low as 1.1 Omega have been obtained from FC device configurations with a back reflecting ohmic contact of Ni/Au/RTA/Ni/Ag metal stack. A small shift has been observed between electroluminescence (EL) emissions of TE LED and the FC LEDs. In addition, FWHM value of the EL emission of DCFC LED has shown the minimum value of 160 meV (26.9 nm). Furthermore, DCFC LED configuration has shown the highest quantum efficiency and power output, with 330 mW at 500 mA current injection, compared to that of traditional wire bonded TE LEDs and the conventional FC LEDs., Scientific and Technical Research Council of Turkey, (TUBITAK) [113G042, 115E109], We are grateful to H. Morkoc, U Ozgur, V. Avrutin of Virginia Commonwealth University for many fruitful discussions. This work is supported by Scientific and Technical Research Council of Turkey, (TUBITAK Grant no: 113G042 and 115E109).

WOS: 000373869300021, We have calculated the ground state binding energy using variational methods and the effective mass approximation for the hydrogenic impurity in square quantum well structure made up of GaAs/InGaAs/GaAs epilayers under the action of hydrostatic pressure and temperature for different well widths and barrier heights. The effects of the variation of hydrostatic pressure and temperature can be summarized as follows; impurity binding energy is a negligibly decreasing function of temperature for fixed pressure and is an increasing function of pressure for fixed temperature. (C) 2015 Elsevier Ltd. All rights reserved.

WOS: 000459827000007, We report the effect of total carrier gas flow of GaN during both GaN nucleation layer and high temperature GaN growth steps on structural, optical, electrical and morphological properties. The formation of dislocations in GaN layer and their effects were investigated in detail as a function of carrier gas flow. It has been found that the more carrier gas requires longer recovery time for transition from 3D (3 dimensional) to 2D growth and results in smaller edge-type dislocation density. The images obtained from the AFM measurements have shown terraces widths varying between 60-150 nm depending on the hydrogen flow rate., TUBITAK [113G103, 115E109]; Cumhuriyet University [M-699], The authors acknowledge the usage of Nanophotonics Research and Application Center at Cumhuriyet University (CUNAM) facilities. This work is supported by the TUBITAK under project nos. 113G103 and 115E109 and by Scientific Research Project Fund of Cumhuriyet University under the project number M-699. The authors thank Ms. A. Alev Kizilbulut from ERMAKSAN Optoelectronics for room temperature PL measurements.

WOS: 000430037600030, We investigate the effect of InGaN stress compensation layer on the properties of light emitting diodes based on InGaN/GaN multiple quantum well (MQW) structures with step graded electron injectors. Insertion of an InGaN stress compensation layer between n-GaN and the step graded electron injector provides, among others, strain reduction in the MQW region and as a result improves epitaxial quality that can be observed by 15-fold decrease of V-pit density. We observed more uniform distribution of In between quantum wells in MQW region from results of electro- and photoluminescence measurement. These structural improvements lead to increasing of radiant intensity by a factor of 1.7-2.0 and enhancement of LED efficiency by 40%. (C) 2018 Elsevier Ltd. All rights reserved., Scientific and Technological Research Council of Turkey [113G042]; TUBITAK, Financial support for this work is provided by the Scientific and Technological Research Council of Turkey (Grant No: 113G042). Ismail Altuntas acknowledges the Ph.D. Grant support from TUBITAK. We thank UNAM-National Nanotechnology Research Center at Bilkent University for access to fabrication and characterization equipment.

WOS: 000425566100069, Enhancement of InGaN/GaN based light emitting diode performance with step graded electron injectors through a two-step passivation is reported. Perimeter passivation of LED dies with SiO2 immediately following ICP mesa etch in addition to conventional Si3N4 dielectric surface passivation leads to decrease in the reverse bias leakage current by a factor of two as well as a decrease in the shunt current under forward bias by an order of magnitude. Mitigation of the leakage currents owing to the two-step passivation leads to significant increase in the radiant intensity of LEDs by more than a factor of two compared to the conventional single step surface passivation. Further, micro-dome patterned surface of Si3N4 passivation layer allow enhanced light extraction from LEDs. (C) 2017 Elsevier Ltd. All rights reserved., Scientific and Technological Research Council of Turkey (TUBITAK) [113G042]; TUBITAK, Financial support for this project was provided by the Scientific and Technological Research Council of Turkey (TUBITAK) [Grant No: 113G042]. Ismail Altuntas, acknowledges the Ph.D. Grant support from TUBITAK. We thank to UNAM-National Nanotechnology Research Center at Bilkent University for the use of fabrication and characterization equipment.

WOS: 000415768800128, The effect of a transparent ITO current spreading layer on electrical and light output properties of blue InGaN/GaN light emitting diodes (LEDs) is discussed. When finite conductivity of ITO is taken into account, unlike in previous models, the topology of LED die and contacts are shown to significantly affect current spreading and light output characteristics in top emitting devices. We propose an approach for calculating the current transfer length describing current spreading. We show that an inter-digitated electrode configuration with distance between the contact pad and the edge of p-n junction equal to transfer length in the current spreading ITO layer allows one to increase the optical area of LED chip, as compared to the physical area of the die, light output power, and therefore, the LED efficiency for a given current density. A detailed study of unpassivated LEDs also shows that current transfer lengths longer than the distance between the contact pad and the edge of p-n junction leads to increasing surface leakage that can only be remedied with proper passivation. (C) 2017 Elsevier Ltd. All rights reserved., TUBITAK [113G042]; Scientific and Technological Research Council of Turkey (TUBITAK), This work has been performed with the support of TUBITAK (Grant no: 113G042). Ismail Altuntas, acknowledges the Ph.D. Grant support from the Scientific and Technological Research Council of Turkey (TUBITAK).