Browsing by Author "Özer, E"
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Item A child with intravascular fasciitis mimicking deep vein thrombosis: a case reportYigit, Y; Erdogan, O; Yildirim, AT; Özer, E; Gülen, HBackground. Intravascular fasciitis (IF) is a benign, reactive, myofibroblastic proliferation that originates from the superficial or deep fascia of small / medium-sized arteries and veins. Case Report. An 8-year-old male patient was admitted to a health center with the complaint of swelling in the inguinal region. Lower extremity venous Doppler ultrasonography showed deep vein thrombosis (DVT) of the femoral vein and anticoagulation with low-molecular weight heparin (LMWH) was initiated. The patient was referred to our center for follow-up. The D-dimer level was detected within normal limits. Doppler ultrasonography was repeated and showed an intraluminal expanding mass lesion with increasing vascularity, without distinct borders and LMWH was discontinued. This lesion at the sapheno-femoral junction was excised surgically and the histopathological examination revealed intravascular fasciitis. Conclusion. Clinicians should be aware that the clinical findings of IF may mimic sarcoma and thrombosis.Item Determination of diffusion kinetics, wear and corrosion behaviour of boro-sintered powder metal AISI 316 stainless steel alloyAyvaz, SI; Zalaoglu, D; Özer, E; Bahçepinar, AI; Aydin, IBThe study aimed to improve the hardness, wear, and corrosion resistance of powder metal AISI 316 stainless steel alloy using boro-sintering to form FeB and Fe2B compounds on the sample surface at different temperatures and durations utilizing Ekabor II boriding powder. The boride layer thickness was measured, and boron diffusion kinetics were determined. The boron diffusion activation energy was computed at 190.29 kJ & sdot;mol-1 during borosintering. The microhardness test revealed 12.5 times increase in the hardness of the AISI 316 stainless steel substrate. Adhesion tests using Daimler-Benz Rockwell C confirmed adequate substrate-coating adhesion of the formed boride layers. The ball-on-disc method results indicated that the wear resistance of boro-sintered samples exceeded that of unboronized AISI 316 stainless steel by a ratio ranging from 8.32 to 14.17. Corrosion tests of boronized powder metal AISI 316 stainless steel alloy samples were conducted in 3.5 % NaCl solution, demonstrating a 50 % reduction in corrosion rate with the boro-sintering process.Item Microstructural, mechanical, wear and corrosion properties of Mg3Zn/ TiB2-CNT nanocompositesÖzer, E; Ayvaz, M; Zalaoglu, D; Übeyli, M; Özdogru, TLight magnesium nanocomposites, offering great weight savings, have a great potential to be utilized in aerospace and automotive industries. They have also been attracted much attention to be evaluated as biomaterial recently owing to their in vitro biodegradability and biocompatibility properties. In the present research, the Mg3Zn/TiB2-CNT nanocomposites were successfully manufactured using mechanical alloying, cold compaction at 600 MPa and finally sintering at 560 degrees C for 1 h. Their microstructural, mechanical, wear and corrosion properties were investigated extensively for comparison with the Mg3Zn alloy. It was found that the microhardness of the Mg3Zn nanocomposites increased directly with the hybrid reinforcement ratio. In parallel to the hardness, an addition of 15 vol % TiB2-CNT reinforcement to the Mg3Zn alloy allowed to the improvement of the compressive strength by of 46.3 % at a reasonable ductility level of similar to 7.8 % compared to the Mg3Zn alloy. The crystallite size, decreasing with an augmentation in the reinforcement content steadily, was obtained to be smaller than 100 nm for the bulk Mg3Zn nanocomposites. Moreover, the wear loss of Mg3Zn alloy reduced by similar to 45 % upon the incorporation of 15 % hybrid reinforcement due to the occurrence of a stable tribolayer between the working couple. An additional benefit of the incorporation of hybrid reinforcement into Mg3Zn alloy was also obtained in the progress of corrosion resistance significantly. The corrosion rate was recorded to be 1462.6 mpy for Mg3Zn but it decreased to 276 mpy upon the incorporation of 10 % hybrid reinforcement into the alloy.Item Effect of Heat Treatment and Reinforcement Content on the Wear Behavior of Al-4Cu/Al2O3-CNT NanocompositesÖzer, E; Ayvaz, M; Übeyli, M; Sarpkaya, IIn the study, the effects of hybrid reinforcement (nano-alumina and MWCNT) and heat treatment on the wear behavior of the Al-4Cu nanocomposites were investigated under dry sliding condition against W-6Co ball by means of a ball-on-disk type tribometer. The load and the sliding speed were kept constant and selected to be 10 N and 0.1 m s(-1), respectively, in the course of the wear tests. Meanwhile, the wear tests were completed after a total sliding distance of 1500 m was reached for each case. During these tests, the wear loss of the nanocomposites was measured at every 250 m. The worn surfaces of the nanocomposites were examined with the help of stereo and scanning electron microscopes. The volumetric wear rates, wear coefficients and wear mechanisms were identified for the nanocomposites to clarify the influence of reinforcement content and heat treatment on their wear resistance. The volume loss at the wear distance of 1500 m was obtained as 24.9 and 8.2 mm(3) for the annealed and aged Al-4Cu alloy, respectively. On the other hand, it decreased to 4.6 and 3.2 mm(3) in the case of the nanocomposites with 15% hybrid reinforcement in the annealed and aged conditions, successively. Moreover, increasing the hybrid reinforcement amount decreased the wear loss of the aged nanocomposites substantially in such a way that it resulted in the mild wear.Item Properties of Aluminum Nano Composites Bearing Alumina Particles and Multiwall Carbon Nanotubes Manufactured by Mechanical Alloying and Microwave SinteringÖzer, E; Ayvaz, M; Übeyli, M; Sarpkaya, IIn this research, the effects of heat treatment and hybrid reinforcement ratio on the microstructural and mechanical properties of Al-4Cu nanocomposites containing MWCNT and nano Al2O3p were investigated. First of all, the hybrid reinforced Al-4Cu nanocomposites were manufactured with the aid of mechanical alloying and microwave sintering. And then, they were subjected to various heat treatments; annealing and artificial aging at 170, 180 and 200 degrees C individually. After that, the microstructural observations were made using X-ray diffraction, optical microscope and scanning electron microscopes (SEMs). The secondary electrons (SE), back scattered electrons (BSE), energy dispersive X-ray (EDX) and elemental mapping analyses of the specimens were carried out with the aid of SEMs. In addition, the nanoindentation tests were done to get the nanohardness and elastic modulus of composites. Finally, the composites were subjected to the compression test to clarify their compressive properties. The Al2Cu and Al4C3 precipitates were detected in the composite samples either annealed or peak-aged at 200 degrees C, while the intermetallic compound, Al7Cu2Fe, precipitated only in the aged samples. A significant increment in the nanohardness of composites was obtained with increasing reinforcement content. Moreover, the elastic modulus of annealed and peak-aged composites, reinforced with 15% hybrid reinforcement in volume, increased by 59% and 57%, respectively compared to the unreinforced alloy. Furthermore, the use of hybrid reinforcement in the alloy matrix allowed an improvement of compressive yield strength at the expense of compressive strain.Item Does ileal reverse segment in rats with short bowel syndrome change intestinal morphology?Sencan, A; Akçora, B; Mir, E; Sencan, A; Günsar, C; Arslan, O; Özer, EBackground: The primary goal of surgical therapy for short bowel syndrome is to increase intestinal absorptive capacity. Many surgical procedures have been described for this purpose. One of these is ileal reverse-segment procedure. This procedure after massive small-bowel resection is an alternative way to treat short bowel syndrome. but how it affects intestinal morphology in short bowel syndrome has not been investigated. The aim of this study is to investigate macroscopic and microscopic effects of reverse-segment procedure on the short bowel. Methods: Twenty rats underwent resection of 80% of the small bowel. The rats were separated into two groups (n = 10). In the first group (reverse group). a reverse segment was formed by twisting a 2-cm ileal segment 180degrees, without damaging its vascularity. In the second group (control group), a 2-cm ileal segment was resected, preserving its mesentery, and end-to-end anastomosis was performed to maintain the intestinal passage. The segment was not twisted 180degrees. The 2-cm proximal (jejunal) and distal (ileal) segments of the resected bowel were reserved for histologic investigation. Two months later, the rats were killed and the jejunal and ileal segments were evaluated morphologically, Results: In the reverse group, body weight and total intestinal length significantly increased (14% more than in the control group). The diameter of both proximal (jejunal) and distal (ileal) segments in the reverse group also increased 53.8% and 22.8%, respectively (P < 0.05). Histologically, crypt depth and villus height of the ileal segment in the reverse group increased 15,2% and 18.2% more than in the control group (P < 0.05). No histologic change was observed at the jejunal level except for intestinal muscle thickness. Conclusions: Ilea] reverse-segment procedure in rats with short bowel syndrome 1) does not cause intestinal obstruction, 2) increases total bowel length and body weight, 3) increases the diameter of both jejunal and ileal segments, and 4) increases villus height and crypt depth only at the ileal level. For this reason, reverse-segment procedure positively affects intestinal adaptation.Item Testis fixation in prepubertal ratsSencan, A; Cenç, A; Günsar, C; Daglar, Z; Yilmaz, Ö; Ulukus, Ç; Özer, E; Taneli, C; Mir, EExperimental studies have shown that different suture materials used in testis fixation cause some degree of inflammation in the testis. This study was planned to compare the histological changes that were caused by fibrin glue which is a tissue sealant and by silk and polypropylene for transparenchymal testis fixation. 28 prepubertal rats were divided into 4 groups. Testis was fixed to the tunica vaginalis by fibrin glue in group 1, by silk in group 2 and by polypropylene in group 3. Group 4 was planned as a control. Testicular inflammation and seminiferous tubular diameter were evaluated for histological changes. The least inflammation was observed in the fibrin glue group, while the most inflammation occurred in the silk group. Seminiferous tubular diameter was 241.55 +/- 45.90 in the fibrin glue group, 151.90 +/- 8.34 in the silk group and 161.36 +/- 9.96 in the polypropylene group. In conclusion, fibrin glue, when used for testis fixation, causes less inflammation and less destruction of seminiferous tubular diameter compared with silk and polypropylene.Item The effect of SiC content on microstructural and tribological properties of sintered B4C and SiC reinforced Al-Cu-Mg-Si matrix hybrid compositesGezici, LU; Özer, E; Sarpkaya, I; Çavdar, UIn this study, B4C and SiC hybrid reinforced Al-Cu-Mg-Si alloy Matrix composites were fabricated using a microwave sintering technique at a sintering temperature of 550 degrees C for 60 min. In the produced hybrid composites, while the B4C ratio was kept constant (3 wt%), SiC was used in four different amounts (3, 6, 9, and 12 wt%). In these produced hybrid composites, as a result of microwave sintering, thanks to the high microwave absorption of SiC, the porosities closed at a rate of 36.65-40.90%. In 3, 6, 9, and 12 wt% SiC reinforced composites, the microhardness of 100.1, 106.8, 114.4, and 117.2 HV0.05 were achieved, respectively. Due to agglomeration increasing with SiC reinforcement rate, delamination wears increased in 12 wt% SiC reinforced hybrid composite. As a result, the lowest specific wear rate was measured as 0.3374 x 10(-3) mm(3)center dot(Nm)(-1) in the 3 wt% B4C+9 wt% SiC reinforced sample.Item Effects of amnio-allantoic fluid exchange on bowel contractility in chick embryos with gastroschisisSencan, A; Gümüstekin, M; Gelal, A; Arslan, O; Özer, E; Mir, EBackground/Purpose: Intestinal damage in patients with gastroschisis is characterized by bowel wall thickening, intestinal dilatation, mesenteric shortening, and a fibrous peel. The prevention of intestinal damage in gastroschisis by amnio-allantoic fluid (AAF) exchange has been reported using histologic and macroscopic evaluation of intestines, but the effects of this treatment on bowel contractility have not been investigated. The current study was performed to determine the effect of AAF exchange on the intestinal contractility in chick embryos with gastroschisis. Methods: Thirteen-day-old fertilized chick eggs were used. Gastroschisis was created through amnio-allantoic cavity. There were 3 study groups: control group, gastroschisis-only group, and gastroschisis-plus-exchange group. The bowels were evaluated by an in vitro muscle strip technique, and the response was expressed as a percentage of the maximum acetylcholine evoked contraction (E-max) in each tissue obtained. Additionally, parasympathetic ganglion cells per 10 plexus at the intestinal wall were counted. Differences between groups were analyzed by analysis of variance (ANOVA) followed by Tukey-Kramer. Probabilities of less than 5% were considered significant. Results: The intestines were thickened and covered by fibrous peel in the gastroschisis-only group when compared with the control group and the gastroschisis exchange group morphologically. There was a statistically significant decrease in contractility in the gastroschisis-only group compared with the control group (P < .05). It exerted 42.03 +/- 46.73% contraction of control group's Em x. This decrease in contractility was significantly reversed in the exchange group (P < .05; E-max value of gastroschisis plus exchange group was 71.45 +/- 23.54% of control group's E-max). Although the number of ganglia per 10 plexus was 76.7 +/- 4.3 in the control group, it was measured 28% less in the gastroschisis-only group (P < .05). There was no significant difference between the ganglion numbers of control and exchange groups. Conclusions: Prenatal AAF exchange treatment prevents decreased bowel contractility in gastroschisis. Gastroschisis does not affect intestinal ganglia morphology, but the number of ganglion cells decreases. AAF exchange prevents these functional and morphologic adverse effects of disease. By these findings the expectancy of a better clinical result in gastroschisis with intrauterine pretreatment by amniotic fluid exchange increases. Copyright 2002, Elsevier Science (USA). All rights reserved.Item Does sucralfate prevent apoptosis occurring in the ischemia/reperfusion-induced intestinal injury?Sencan, A; Yilmaz, Ö; Özer, E; Günsar, C; Genç, K; Ulukus, Ç; Taneli, C; Mir, EBackground/Purpose: We have shown in a previous study that sucralfate is beneficial in the prophylaxis and treatment of hypoxia/reoxygenation-induced intestinal injury. The aim of this study is to investigate whether sucralfate has any effect on the prevention of apoptosis in the ischemia/reperfusion (I/R)-induced intestinal injury. Methods: Rats were randomized into three groups. Group 1 and 2 were subjected to I/R. Group 1 (treatment group) received sucralfate while group 2 (treatment control group) did not. Group 3 served as a normal control group (sham group). The terminal ileum was harvested for histopathologic investigation by light microscopy. The presence of apoptotic enterocytes (DNA fragmentation in cell nuclei) was detected by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end-labeling (TUNEL) reaction. Results: In treatment control group, 3 of 7 rats had severe inflammation. None of the sucralfate-treated rats showed severe inflammation, 6 of them only showed mild inflammatory changes (p < 0.05). The apoptotic percentage was found to be 37.1 +/- 9.4 in the sucralfate-treated group (group 1), whereas it was 45.4 +/- 3.9 in the untreated group (group 2) (p < 0.05). The sham group had a completely normal intestinal architecture. Conclusions: The present study shows that 1) the experimental model of I/R-induced intestinal injury induces enterocyte apoptosis; 2) sucralfate decreases enterocyte apoptosis in the experimental model of I/R-induced intestinal injury which may play a key role in the pathophysiological events leading to failure of the intrinsic gut barrier defense mechanisms.Item Comparative Study of Conventional and Microwave-Assisted Boriding of AISI 1040 and AISI 4140 SteelsAyvaz, SI; Özer, EIn this study, AISI 1040 and AISI 4140 steels were boriding using Ekabor-II commercial boriding powder with powder-pack boriding method using microwave and conventional heating methods. The samples were borided at 950 & DEG;C for 2 and 6 hours in an Ar atmosphere in a microwave oven of Enerzi-Mh2912-V8. Biphasic structure (FeB/Fe2B) was formed in all borided AISI 4140 samples and AISI 1040 samples borided for 6 hours. A single-phase structure was observed in AISI 1040 steel borided for 2 hours. Compared to the conventional method, a 1.5-1.6 times thicker boride layer was obtained in AISI 4140 and AISI 1040 steels with microwave-assisted powder-pack boriding. The highest hardness was measured as 1561.8 HV0.05 for boriding AISI 4140 steel and 1499.7 HV0.05 for boriding AISI 1040 steel. The Vickers indentation fracture toughness of borided steels with microwave energy varied between 2.31 and 3.46 MPa & BULL;m1/2. It was determined that in all samples borided by the microwave-assisted and conventional powder-pack boriding method, the adhesion strength between the boride layers and the substrate obtained was sufficient.Item Does Fetal Malnutrition Affect Ghrelin, Leptin, Adiponectin and Insulin Levels in the Cord Blood of Newborns?Tanriverdi, S; Ersoy, B; Taneli, F; Özer, EAim: Fetal malnutrition is a condition characterized clinically by the inability of subcutaneous adipose tissue and muscle mass to reach the mai amount or by significant intrauterine loss. The major hormones regulating fetal growth, fetal energy metabolism and adipogenesis are insulin, leptin, ghrelin and adiponectin. Cholesterol and triglycerides are very important in fetal growth in the last period of pregnancy. In this study, it was aimed to compare the glucose, insulin, leptin, ghrelin, adiponectin, cholesterol and triglyceride levels in the cord blood of newborn babies with and without fetal malnutrition. Materials and Methods: Term babies born in our hospital were included in this study. Babies with a Clinical Assessment of Nutritional Status of 24 or below were considered as cases with fetal malnutrition, and those over 24 were considered as cases without fetal malnutrition. Glucose, insulin, leptin, ghrelin, adiponectin, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, very-lowdensity lipoprotein cholesterol and triglyceride levels were studied from blood samples taken from the umbilical cord after delivery. Results: A total of 80 term newborn babies (40 babies with fetal malnutrition and 40 babies without fetal malnutrition) were included in this study. Birth weight, glucose and insulin values were found to be significantly lower in the group with fetal malnutrition (p<0.001; p<0.001; p=0.047, respectively), and adiponectin levels were found to be significantly higher (p<0.001). Concluslon: In our study, adiponectin levels in cord blood were found to be high in infants with fetal malnutrition. Considering the anti-inflammatory role of adiponectin, high adiponectin levels in infants with fetal malnutrition may directly or indirectly reflect a protective mechanism.Item Dry tribological behaviour of microwave-assisted sintered AA2024 matrix hybrid composites reinforced by TiC/B4C/nano-graphite particlesÖzer, E; Ayvaz, MThis study aimed to produce hybrid composites with a AA2024 matrix reinforced by TiC/B4C/nano-graphite through a microwave-assisted sintering technique at 560 degrees C for 60 min. The nano-graphite ratio in the produced composite samples was kept constant as 1 wt%. TiC and B4C were used in equal ratios at 2, 6 and 10 % by weight total to determine their effects on tribological properties. Wear tests were conducted under three different loads: 3, 5 and 10 N. In the hybrid composites produced, an inverse correlation was observed between the increase in reinforcement ratio and sinterability, while a direct correlation relationship was found in hardness and wear resistance. Compared to the sample containing 2 % TiC/B4C in total by weight, a similar to 50 % increase in Brinell hardness and a 52-68 % decrease in wear rate was obtained in the sample containing 10 % TiC/B4C. As the reinforcement ratio increased, tribofilm formation increased, and abrasive wear was replaced by mild-oxidative wear type.Item Prevention of posterior capsule opacification by retinoic acid and mitomycinInan, ÜÜ; Öztürk, F; Kaynak, S; Ilker, SS; Özer, E; Güler, CBackground: Our aim was to evaluate the effect of an intraoperative single dose of retinoic acid (RA) or mitomycin C (MMC) in preventing posterior capsule opacification (PCO). Methods: Twenty-seven rabbits were divided randomly into three groups. RA (250 mug/ml) and MMC (0.04 mg/ml) were given 0.1 ml by hydrosection and 0.9 ml into the capsular bag after phacoemulsification. The third group served as a control group. Three months after intervention PCO was graded clinically. Furthermore, proliferation of lens epithelial cells was evaluated histologically. Results: Two eyes developed corneal edema in the MMC group. On clinical assessment, RA and MMC were significantly effective in preventing PCO compared with controls (P <0.005). On histological analysis, there was significantly reduced proliferative activity on posterior capsules in the treatment groups, in contrast to multilayer cells in the control group. Conclusion: Intraoperative single-dose administration of RA and MMC significantly prevented the development of PCO in rabbit eyes. The optimal biocompatible dosage must be carefully determined by further investigation.Item Prevention of posterior capsule opacification by intraoperative single-dose pharmacologic agentsInan, ÜÜ; Özturk, F; Kaynak, S; Kurt, E; Emiroglu, L; Özer, E; Ilker, SS; Güler, CPurpose. To determine whether an intraoperative single dose of dexamethasone, diclofenac, ethylenediaminetetraacetic acid (EDTA), a combination of EDTA and RGD peptide (arginine-glycin-aspartic acid sequence), or mitomycin-C (MMC) is a pharmacological means of preventing or reducing the development of posterior capsule opacification (PCO). Setting. Department of Ophthalmology, Celal Bayar University, School of Medicine, Manisa, and Department of Pathology, Dokur Eylul University, School of Medicine, izmir, Turkey. Methods: Fifty-four rabbits were randomly divided into 6 groups. Dexamethasone (4 mg/cc), diclofenac (2.5 mg/cc), EDTA (8 mg/cc), a combination of EDTA and RGD peptide (2.5 mg/cc), or MMC (0.04 mg/cc) was given, 0.1 cc by hydrodissection and 0.9 cc into the capsular bag after phacoemulsification. The sixth group served as a control group. After 3 months, the PCO was graded clinically and the proliferation of lens epithelial cells (LECs) was evaluated histologically. Results: The drugs were significantly effective in preventing PCO compared with the control (P < .005). Dexamethasone had a weaker effect than the other drugs. In histological analysis, although monolayer LECs in the dexamethasone and diclofenac groups were observed, there was no proliferative activity on the posterior capsules in the EDTA, EDTA+RGD, and MMC groups in contrast to the multilayer cells in the control. Conclusions: Intraoperative single-dose application of EDTA, EDTA+RGD peptide combination, and MMC significantly prevented the development of PCO in rabbit eyes. Diclofenac was less effective but also reduced PCO. Although dexamethasone did not prevent the proliferation of LECs, it decreased PCO clinically. (C) 2001 ASCRS and ESCRS.Item Physicochemical and Sensory Characteristics of Winter Yoghurt Produced from Mixtures of Cow's and Goat's MilkKesenkas, H; Karagözlü, C; Yerlikaya, O; Özer, E; Akpinar, A; Akbulut, NWinter yoghurt is one of the most popular dairy products in Van and Hatay region of Turkey. It is made of different kinds of milk, and known as cooked yoghurt or salted yoghurt due to its high solids content and long shelf life. In this study, two different concentration methods were used to produce traditional winter yoghurt. Some physical (firmness and cohesiveness, L-, a- and b- values), chemical (total solid, fat, protein, pH, lactic acid, salt) and sensory analyses (color, odor, consistent and flavor) were made to determine the effect of production methods and storage on winter yoghurt samples at the 1st, 30th, 60th and 90th days. Significant differences were found between sensory, rheological properties and color values of winter yoghurts however no significant differences were found between physicochemical properties of the samples. Especially, winter yoghurts produced from 100% goat milk were the more appreciated samples.