Ulker Sonmez

Dokuz Eylul University, İzmir, Izmir, Turkey

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Publications (10)16.25 Total impact

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    ABSTRACT: Gray platelet syndrome (GPS) is a rare inherited disorder characterized by the absence of α-granules and their constituents. It may be present with thrombocytopenia and bleeding tendency. Platelets have a large and gray appearance under light and electron microscope. A 19-year old female patient with her second relapse acute lymphoblastic leukemia had to be consolidated with allo-hematopoietic stem cell transplantation (HSCT) after achieving remission with induction chemotherapy. The only available and one mismatch compatible donor was her brother, who was previously diagnosed as GPS. Allogeneic HSCT was performed from her brother in spite of GPS, and successful neutrophil and platelet engraftment achieved at the 12th and 42nd day of reinfusion, consecutively. The engrafted and circulating thrombocytes were large and gray and had little or no α-granules under electron microscope. The patient was well with no major bleeding event and increased need for thrombocyte replacement until developing bronchiolitis obliterans organizing pneumonia and respiratory distress syndrome. Thereafter death occurred. This is the first case of successful thrombocyte engraftment with documented gray thrombocyte megakaryopoiesis after allogeneic HSCT from a GPS donor. The only noteworthy issue was the slight prolongation of engraftment.
    Blood coagulation & fibrinolysis: an international journal in haemostasis and thrombosis 03/2013; 24(2):208-10. · 1.25 Impact Factor
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    ABSTRACT: In this study, experimental diabetes and nephrectomy have been applied separately and together in order to investigate the possible therapeutic effects of lipoic acid (LA) on hypertensive and diabetic rat kidneys. Wistar rats were divided into eight groups: control, diabetes mellitus (DM), 5/6 nephrectomy, DM + 5/6 nephrectomy, LA administration, DM + LA treated, 5/6 nephrectomy + LA treated, and DM + 5/6 nephrectomy + LA-treated groups, respectively. Renal damage was evaluated histomorphometrically, ultrastructurally, and biochemically. Our findings supported that diabetes and hypertension together increased the rate of renal injury, and LA had therapeutic effects on hypertensive and diabetic rat kidneys.
    Clinical and Experimental Hypertension 10/2012; · 1.28 Impact Factor
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    ABSTRACT: Consumption of alcohol leads to oxidative stress in liver by inducing lipid peroxidation. The aim of this study was to investigate the effects of carnosine (CAR) in alcohol-induced liver injury by biochemical and histomorphological evaluations. The rats were divided into four groups, namely, control group, alcohol (AL) group, CAR group and AL + CAR group. Three doses of ethanol (5 g/kg, 25% (v/v) in distilled water) were given by nasogastric catheter for twice-a-day. CAR (100 mg/kg) was given 1 h before the administration of ethanol using the same method. Levels of alanine aminotransferase, aspartate aminotransferase, myeloperoxidase and malondialdehyde were significantly increased in the AL group compared with control, CAR and AL + CAR groups. Glutathione level was significantly decreased in the AL group, while it was increased in the AL + CAR group. Immunoreactivity of caspase-3 and bax increased in the hepatocytes of AL group when compared with control and AL + CAR groups. Expression of bcl-2 was decreased in AL group than AL + CAR group. Under electron microscopy, dense mitochondria, accumulation of lipid, sinusoidal dilatation, vacuolization and decrease in the number of microvilli were observed in AL group, while these findings were markedly less in the AL + CAR group. In conclusion, pretreatment of CAR is effective for recovering biochemical alterations and morphologic damage in the liver of rats treated with ethanol.
    Toxicology and Industrial Health 06/2012; · 1.56 Impact Factor
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    ABSTRACT: To determine the neuroprotective effects of Ginkgo biloba extract (EGb761) and Selenium (Se), and the combination of these agents on ischemia/reperfusion (I/R) injury in a rat model of transient global cerebral I/R. This experimental study took place in the Animal Research Laboratory at Dokuz Eylul University, Izmir, Turkey in the year 2006. Fifty rats were subjected to cerebral I/R induced by right carotid artery occlusion technique for a duration of 45 minutes, and then were treated with EGb761 (50 mg/kg/day, ip) and Se (0.625 mg/kg, ip), alone or in combination for 14 days after surgery. Superoxide dismutase, and glutathione peroxidase activities were measured in the hippocampal tissues from 25 animals. Histopathological examinations were also carried out under light and electron microscopy from the rest of animals. The results suggest that EGb761 has a potent neuroprotective effect against cerebral I/R induced injury in rat brain that is comparable with that of Se. However, the combined use of EGb761 and Se does not further protect from neuronal injury when compared with the use of both agents alone. Our results suggest that administration of EGb761, Se and its combination with EGb761 have significant neuroprotective effects on I/R injury in rats via suppression of oxidative stress.
    Neurosciences 07/2008; 13(3):233-8. · 0.32 Impact Factor
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    ABSTRACT: Perinatal asphyxia is an important cause of neonatal mortality and subsequent serious sequelae such as motor and cognitive deficits and seizures. Recent studies have demonstrated that short peptides derived from activity-dependent neurotrophic factor (ADNF) and activity-dependent neuroprotective protein (ADNP) are neuroprotective at femtomolar concentrations. However, the effect of these peptides on the hypoxic-ischemic brain injury model is unknown. The aim of this study is to investigate the effects of the peptides ADNF-9 and NAP on neurodegeneration and cerebral nitric oxide (NO) production in a neonatal rat model of hypoxic-ischemic brain injury. Seven-day-old Wistar Albino rat pups have been used in the study (n=42). Experimental groups in the study were: sham-operated group, ADNF-9-treated hypoxia-ischemia group, NAP-treated hypoxia-ischemia group, ADNF-9+NAP-treated hypoxia-ischemia group, and vehicle-treated group. In hypoxia-ischemia groups, left common carotid artery was ligated permanently on the seventh postnatal day. Two hours after the procedure, hypoxia (92% nitrogen and 8% oxygen) was applied for 2.5 h. ADNF-9, NAP, and ADNF-9+NAP were injected (intraperitoneally; i.p.) as a single dose immediately after the hypoxia period. Brain nitrite levels, neuronal cell death, and apoptosis were evaluated in both hemispheres (carotid ligated or nonligated) 72 h after the hypoxic-ischemic insult. Histopathological evaluation demonstrated that ADNF-9 and NAP significantly diminished number of "apoptotic cells" in the hippocampal CA1, CA2, CA3, and gyrus dentatus regions in both hemispheres (ligated and nonligated). When compared with vehicle-treated group, combination treatment with ADNF-9+NAP did not significantly reduce "apoptotic cell death" in any of the hemispheres. ADNF-9 and NAP, when administered separately, significantly preserved the number of neurons CA1, CA2, CA3, and dentate gyrus regions of the hippocampus, when compared with vehicle-treated group. The density of the CA1, CA2, and dentate gyrus neurons was significantly higher when combination therapy with ADNF-9+NAP was used in the carotid ligated hemispheres. In the nonligated hemispheres, combination therapy preserved the number of neurons only in the CA1 and dentate gyrus regions. Brain nitrite levels were evaluated by Griess reagent and showed that hypoxic-ischemic injury caused a significant increase in NO production. Brain nitrite levels in ADNF-9+NAP-treated animals were not different in carotid ligated or nonligated hemispheres. The peptides ADNF-9 and NAP significantly decreased NO overproduction in the hypoxic-ischemic hemisphere, whereas no significant change appeared in hypoxia alone and also in the sham-operated group. These results suggest the beneficial neuroprotective effect of ADNF-9 and NAP in this model of neonatal hypoxic-ischemic brain injury. To our knowledge, this is the first study that demonstrates a protective effect of these peptides against hypoxia-ischemia in the developing brain.
    Brain Research 11/2006; 1115(1):169-78. · 2.88 Impact Factor
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    ABSTRACT: It is known that maternal deprivation induces hippocampal damage in the developing brains. In the present study, we examined the effects of melatonin on maternal deprivation-induced hippocampal damage both during and after stress-hyporesponsive period (SHRP). Hippocampal damage was examined by cresyl violet staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. The results showed that a single episode of maternal deprivation for 24 h at post-SHRP induced neuronal loss in hippocampus regions of the brain in the infant rats, while it did not influence hippocampal neurons in SHRP. Melatonin prevented maternal deprivation-induced hippocampal damage in the infant rats at post-SHRP. These results suggest that melatonin is a potentially beneficial agent to improve the neurobehavioral outcomes of maternal deprivation in later developmental period.
    Neuroscience Letters 06/2006; 398(1-2):145-50. · 2.03 Impact Factor
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    ABSTRACT: The developing central nervous system is extremely sensitive to ethanol, with well-defined temporal periods of vulnerability. Recent studies have shown that administration of ethanol to infant rats during the synaptogenesis period triggers extensive apoptotic neurodegeneration throughout many regions of the developing brain. Furthermore, acute ethanol administration produces lipid peroxidation in the brain as an indicator of oxidative stress. In recent years, it has been shown that erythropoietin (EPO) has a critical role in the development, maintenance, protection, and repair of the nervous system. In the present study, we investigated the effect of EPO against ethanol-induced neurodegeneration and oxidative stress in the developing C57BL/6 mouse brain. Seven-day-old C57BL/6 mice were divided into three groups: control group, saline-treated group, EPO-treated group. Ethanol was administered to mice at a dosage of 2.5 g/kg for two times with a 2-h interval. Recombinant human EPO (rhEPO) was given 1000 U/kg. Twenty-four hours after the first dose of ethanol, all the animals were killed. Neuronal cell death, apoptosis, thiobarbituric acid substance (TBARS) levels, superoxide dismutase (SOD), and glutathione peroxidase (Gpx) enzymes activities were evaluated. Histopathological evaluation demonstrated that EPO significantly diminished apoptosis in the cerebellum, prefrontal cortex, and hippocampus and also spared hippocampal CA1, CA2, and CA3 neurons. Simultaneous administration of EPO along with ethanol attenuated the lipid peroxidation process and restored the levels of antioxidants. Regarding the wide use of erythropoietin in premature newborns, this agent may be potentially beneficial in treating ethanol-induced brain injury in the perinatal period.
    Developmental Brain Research 01/2006; 160(2):146-56. · 1.78 Impact Factor
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    ABSTRACT: It is well known that head trauma induces the cognitive dysfunction resulted from hippocampal damage. In the present study, we aimed to demonstrate the effect of melatonin on hippocampal damage and spatial memory deficits in 7-day-old rat pups subjected to contusion injury. Melatonin was injected intraperitoneally at the doses of 5 or 20 mg/kg of body weight immediately after induction of traumatic injury. Hippocampal damage was examined by cresyl violet staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. Spatial memory performance was assessed in the Morris water maze. Melatonin significantly attenuated trauma-induced neuronal death in hippocampal CA1, CA3 regions and dentate gyrus, and improved spatial memory deficits, which was equally effective at doses of 5-20 mg/kg. The present results suggest that melatonin is a highly promising agent for preventing the unfavorable outcomes of traumatic brain injury in young children.
    Neuroscience Letters 10/2005; 385(3):234-9. · 2.03 Impact Factor
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    ABSTRACT: We investigated whether the psychostimulant methamphetamine (METH) has a cytotoxic effect on oligodendrocytes and which cell-death pathways are involved in the cytotoxic process. METH caused concentration- and time-dependent cytotoxicity in rat oligodendrocyte cultures. METH induced apoptotic cell death and mRNA expression of pro-apoptotic proteins (bax and DP5), but not anti-apoptotic proteins (bcl-2 and bcl-XL). These results suggest that METH induces cytotoxicity in rat oligodendrocytes via the differential regulation of the expression of genes involved in the apoptotic process.
    Brain Research 09/2003; 982(1):125-30. · 2.88 Impact Factor
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    ABSTRACT: To analyze the retinal toxicity of bevacizumab at various doses both in vitrectomized and non-vitrectomized rabbit models. Twenty- eight rabbits were included in the study. Twenty- four rabbits were assigned to six groups, with 4 of the rabbits in the control group. The animals in Groups 1, 2 and 3 received bevacizumab at a dose of 0.3 mg, 0.5 mg and 1.5 mg /eye, respectively. The rabbits in Groups 4, 5 and 6 received intravitreal bevacizumab of 0.3 mg, 0.5 mg and 1.5mg/eye, respectively, after gas compression vitrectomy. Two weeks after the procedure, the rabbits were euthanized. Retina tissue samples were then obtained and examined with both light and electron microscopes. In Groups 1, 2 and 3 after bevacizumab injection, toxic degeneration in the photoreceptor and retinal pigment epithelium cells was observed via electron microscopic examination. The findings in Groups 4 and 5 were normal as compared to the control group. In Group 6, toxicity in the bipolar neurons and photoreceptor cells was noticed. Increased toxicity and retinal penetration were noticed in all administered doses of bevacizumab in the presence of vitreous. In addition, ocular toxicity occurred through the injection of the highest dose of bevacizumab after vitrectomy. It is possible that the bevacizumab dose and the, vitreous are as important as the drug half-life in the vitreous. KeywordsAnti-VEGF-Bevacizumab-Electron microscopy
    Central European Journal of Medicine 5(6):745-751. · 0.26 Impact Factor