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Featured researches published by Oguz Karahan.


Surgical Neurology International | 2013

Reasons, procedures, and outcomes in ventriculoatrial shunts: A single-center experience.

Celal Yavuz; Sinan Demirtas; Ahmet Caliskan; Kaan Kamasak; Oguz Karahan; Orkut Guclu; Suleyman Yazici; Binali Mavitas

Background: Ventricular shunts are used to drain cerebrospinal fluid into extra-cranial spaces. Ventriculoatrial (VA) shunts are provided to transfer cerebrospinal fluid from the cerebral ventricle into the right atrium of the heart. A single center experience of indications, procedure, and clinical outcomes in VA shunt was presented in current study. Methods: VA shunts were applied in 10 patients who had repeated previous shunt dysfunction or infection. The reasons, clinical findings, replacement methods, and postoperative clinical follow-ups and outcomes were recorded retrospectively. Results: There were seven female (70%) and three (30%) male patients; their ages ranged from 5 to 13 years (mean ± SD; 8.5 ± 2.6 years). Shunt re-placement reasons were as follows: Shunt occlusion in five patients, intraperitoneal infection in four patients and a distal catheter was kinked and knotted in one patient. Postoperative early complications were seen in one patient as early catheter thrombosis and catheter revision were applied. Late complications were seen in two patients as follows: Catheter infection and infective endocarditis occurred in one patient and pulmonary thrombus occurred in one other patient. There was not any catheter-related mortality observed at the one year follow-up period. Conclusion: VA shunts may be an option for cerebrospinal fluid drainage at necessary conditions. However, sterilization and general training on asepsy and antisepsy are the most important determinants affecting the clinical outcome due to the cardio systemic relationship.


Vascular | 2014

The relationship between complete blood count parameters and Fontaine’s Stages in patients with peripheral arterial disease

Sinan Demirtas; Oguz Karahan; Suleyman Yazici; Orkut Guclu; Ahmet Caliskan; Celal Yavuz; Aslihan Kucuker; Binali Mavitas

Objective The aim of the present study is to evaluate whether blood count parameters differ according to the stages of Fontaine’s classification and to investigate the relationship between hemogram parameters and the severity of the disease. Method Eighty-two peripheral arterial disease patients were examined prospectively. Patients were classified according to the Fontaine classification system. Fifty newly diagnosed patients were included in the study. The neutrophil-to-lymphocyte ratio, mean platelet volume, and red blood cell distribution width values were recorded. Results Mean neutrophil-to-lymphocyte ratio values were found to be 3.31 ± 1.1% in Stage I, 3.11 ± 1.3% in Stage II, and 3.48 ± 1.1% in Stage III (p > 0.05). Mean platelet volume values were found to be 7.8 ± 0.6 fl (Stage I), 8.2 ± 1.0 fl (Stage II), and 9.0 ± 0.9 fl (Stage III) (p < 0.05). Red blood cell distribution width values were found to be 13.6 ± 1.0% in Stage I, 14.8 ± 1.7% in Stage II, and 15.4 ± 2.3% in Stage III, being significantly different among all three stages (p < 0.05). Conclusion Both red blood cell distribution width and mean platelet volume are found to be associated with the severity of atherosclerotic disease in patients with peripheral arterial disease. This finding hypothesizes that complete blood counting parameters may serve as a beneficial and cost-effective method for monitoring atherosclerotic peripheral disease.


Cns & Neurological Disorders-drug Targets | 2013

Rosuvastatin may have Neuroprotective Effect on Spinal Cord Ischemia Reperfusion Injury

Celal Yavuz; Sinan Demirtas; Orkut Guclu; Oguz Karahan; Ahmet Caliskan; Suleyman Yazici; Binali Mavitas

Ischemia reperfusion injuries can be threatening to end organ viability and can progress, with mortal and morbid outcomes. In particular, neural tissues are highly sensitive to hypoxia and reperfusion stress. This study aimed to determine the neuroprotective effects of rosuvastatin on spinal cord ischemia reperfusion injury. Forty male Sprague- Dawley rats were divided into four equal groups: group I (control), group II (sham with simple laparotomy), group III (ischemia-reperfusion), group IV (ischemia-reperfusion group with continuous rosuvastatin utilization), and group V (ischemia-reperfusion group with rosuvastatin-withdrawal after reperfusion). Spinal cord ischemia was induced by clamping the aorta below the left renal artery and above the aortic bifurcation. Reperfusion was provided after 72(nd) hours of ischemia. After reperfusion, blood samples and spinal cord tissue samples were taken from all the rats. Oxidative and antioxidant markers from both serum and tissue samples were evaluated, and tissues were examined histopathologically. There were no significant differences between the control and sham groups. A notable increase in oxidative markers was observed in group III compared to group I. In addition, a significant decrease in antioxidant markers was detected in group III. However, there was a marked preservation in the tissue and blood samples of groups IV and V compared to group III in terms of oxidative damage. Additionally, definitive prophylaxes were seen in the histopathological examination of the tissue samples in groups IV and V compared with group III. These significant findings show that rosuvastatin has a considerable protective effect on neural tissue against oxidative damage. Likewise, the early withdrawal of rosuvastatin has a clear neuroprotective effect similar to that of continuous therapy. Nevertheless, other systematic effects and beneficial neural effects of statins should be investigated in further clinical trials.


Perfusion | 2014

Iloprost reduces myocardial edema in a rat model of myocardial ischemia reperfusion

Ahmet Caliskan; Celal Yavuz; Oguz Karahan; Suleyman Yazici; Orkut Guclu; Sinan Demirtas; Binali Mavitas

Objective: Myocardial ischemia severely reduces myocyte longevity and function. Extensive interstitial edema and cell damage occur as a result of myocardial reperfusion injury. Current therapies are directed at prevention of ischemia-induced damage to cardiac tissue. Iloprost is a novel pharmaceutical agent for the treatment of ischemia. Methods: Twenty rats were segregated into four experimental groups. The procedure control group consisted of four rats undergoing a sham operation. The remaining 16 rats were divided into two equal groups. The first group (control group) received a continuous intravenous infusion of physiological serum immediately prior to the procedure. Iloprost was administered by a continuous intravenous infusion into the right jugular vein at an infusion rate of 100 ng/kg/min for 30 minutes prior to reperfusion in the experimental group (study group). Following the infusion treatments, ligation of the left coronary artery was conducted for 30 minutes to induce myocardial ischemia. The rats were euthanized 24 hours after reperfusion and cardiac tissue was harvested from all specimens for analysis. Results: Histological examination revealed three myocardial tissue specimens with grade II damage and five myocardial tissue specimens with grade III reperfusion injury in the control group. However, the study group consisted of two grade III myocardial tissue specimens, five grade II myocardial tissue specimens and one grade I myocardial tissue specimen. Moreover, a statistically significant reduction in myocardial edema was observed in the study group (p=0.022). Conclusion: Our results support the hypothesis that iloprost enhances protection against cardiac ischemia reperfusion injury. This protective effect may be associated with vasodilation, antioxidant or anti-edema mechanisms.


Perfusion | 2014

Using oxidant and antioxidant levels to predict the duration of both acute peripheral and mesenteric ischemia

Suleyman Yazici; Sinan Demirtas; Orkut Guclu; Oguz Karahan; Celal Yavuz; Ahmet Caliskan; Binali Mavitas

Objective: The aim of this study was to determine the relationship between oxidative stress markers and the duration of ischemia in rat mesenteric and peripheral ischemia models. Methods: Forty rats were divided into five equal groups, as follows: rats in Group I (control group) were sacrificed to determine the baseline characteristics of the serum markers; the superior mesenteric artery was clamped via a simple laparotomy to induce mesenteric ischemia in Groups II and III; the right common femoral artery was clamped to induce peripheral ischemia in Groups IV and V. Blood samples were taken at 2 (Groups II and IV) and 6 (Groups III and V) hours after these procedures. The serum total oxidative status (TOS), total antioxidant capacity (TAC), oxidative stress index (OSI) and paraoxonase-1 (PON-1) enzyme activities were evaluated in the samples obtained from each group. Results: The OSI level of the control group was 91.00±5.46 (mean ± SD). The OSI levels taken 2 hours after the induction of mesenteric ischemia and peripheral ischemia were significantly higher (194.50±11.16 and 301.75±19.98, respectively (p<0.05)). However, these levels decreased to 151.88±17.02 (mesenteric ischemia) and 108.88±9.46 (peripheral ischemia) after 6 hours. The PON-1 levels of Group III (mesenteric ischemia at 6 hours) (99.75±7.26), Group IV (peripheral ischemia at 2 hours) (96.88±4.09), and Group V (peripheral ischemia at 6 hours) (111.25±10.33) were slightly elevated over that of the control group (87.38±5.31). However, the PON-1 level of Group II (mesenteric ischemia at 2 hours) (42.88±3.14) was lower than that of the other groups (p<0.05). Conclusion: Despite the increment of oxidative markers in early periods of ischemia (2nd hour), which was a hypoxic response of ischemic cells, they have decreased markedly in prolonged ischemia. This might have been caused by the opening of some collateral circulation or the destruction of the ischemic cells.


Perfusion | 2014

Serum ischaemia–modified albumin level is an irrelevant predictive factor for ischaemic duration in mesenteric ischaemia

Ahmet Caliskan; Celal Yavuz; Oguz Karahan; Sinan Demirtas; Suleyman Yazici; Orkut Guclu; Binali Mavitas

Background: Acute mesenteric ischaemia is an emergency condition that requires urgent and expeditious diagnosis and immediate surgical or medical intervention. The initial hours are critical for the recovery of the affected bowel segment. Thus, its clinic diagnostic biomarkers are important when it comes to reducing mortality and morbidity rates. Methods: Twenty-four male Sprague–Dawley rats were included in the study. The rats were divided into three equal groups. Those in Group I were sacrificed to determine the basal serum values of ischaemia-modified albumin (IMA) after a simple laparotomy. The superior mesenteric artery (SMA) was clamped in a simple laparotomy in Groups II and III; blood samples were taken at 120 minutes in Group II and 360 minutes in Group III. The serum IMA levels were identified from the blood samples and the results obtained were compared statistically. Results: The serum IMA levels were determined to be 22±6 (22) μ/L, 34±7 (34) μ/L and 36±4 (37) μ/L in Groups I, II and III, respectively. The differences between the groups were not statistically significant. Conclusion: Our results showed that the serum IMA level is not an appropriate biomarker for acute mesenteric ischaemia. Additionally, the IMA level is not an appropriate biomarker for the detection of ischaemia duration. However, future studies should be conducted to clarify the efficacy of serum IMA levels under different ischaemic conditions.


Therapeutic Advances in Cardiovascular Disease | 2015

Does the direction of tumescent solution delivery matter in endovenous laser ablation of the great saphenous vein

Baris Kutas; Ferit Ozdemir; Orhan Tezcan; Tevfik Gunes; Kamuran Erkoc; Firat H Altin; Oguz Karahan

Background: The aim of this study was to compare the two different directions of tumescent solution delivery (from distal to proximal knee to the saphenofemoral junction [SFJ] or proximal to distal SFJ to the knee) in terms of differences in tumescent volume, number of punctures, and pain and comfort scores of patients. Methods: A total of 100 patients were treated with endovenous laser ablation (EVLA) under local anesthesia between August 2013 and October 2013. These 100 patients were divided into two groups. In group 1, tumescent solution was delivered in a proximal to distal direction. In group 2, the tumescent solution was delivered in a distal to proximal direction. In each group, the great saphenous vein (GSV) diameter, delivered total energy, treated GSV length, delivered tumescent volume, number of punctures, and pain and comfort scores were recorded for each patient. Results: All patients were treated unilaterally. EVLA was performed with 100% technical success in all patients. There was no difference statistically between group 1 and group 2 according to GSV diameter, delivered total energy, and treated GSV length. Average tumescent volume, number of punctures, and pain scores in group 2 were lower than in group 1 (p = 0.0001; p < 0.05). Also, the average comfort score was higher in group 2 than in group 1 (p = 0.0001; p < 0.05). Conclusions: We believe that delivering the tumescent solution in a distal to proximal direction increases the comfort of both patient and surgeon with lower tumescent volume during the EVLA of the GSV.


Biomarkers | 2013

Serum nitric oxide level could be a predictive biomarker for detection of critical ischaemia duration

Celal Yavuz; Suleyman Yazici; Oguz Karahan; Sinan Demirtas; Ahmet Caliskan; Orkut Guclu; Faruk Ertaş; Binali Mavitas

Abstract Objective: To investigate the predictive value of serum nitrate (nitrogen oxide: NOx) levels in the detection of peripheral and mesenteric ischaemia durations. Methods: Rats were sacrificed for determining the basal serum values of NOx in Group I without any intervention. The superior mesenteric artery was clamped in Groups II and III and blood samples were taken at 120 minutes in Group II and at 360 minutes in Group III. The right common femoral artery was clamped in Groups IV and V and blood samples were taken at 120 minutes in Group IV and at 360 minutes in Group V. Results: The peak values of NOx were obtained in Group II and Group IV. NOx levels were reduced in advanced periods of ischaemia. In the other words, the NOx levels were significantly higher at two hours of ischaemia (p < 0.05), and NOx levels were reduced to normal ranges at the sixth hour of ischaemia. Conclusion: Early diagnosis and rapid treatment are important for acute ischaemic disorders. Serum NOx levels can be a decisive biomarker for prediction of the critical ischaemia period.


American Journal of Emergency Medicine | 2016

The relationship between fibrinogen to albumin ratio and severity of coronary artery disease in patients with STEMI

Oguz Karahan; Halit Acet; Faruk Ertaş; Orhan Tezcan; Ahmet Caliskan; Muhammed Demir; Ahmet Kaya; Sinan Demirtas; Mehmet Uğur Çevik; Celal Yavuz

OBJECTIVE Previous studies show that serum fibrinogen levels are established risk factors for coronary artery disease (CAD) and that serum albumin levels are of a higher specificity and sensitivity in ST-elevation myocardial infarction (STEMI). In this study, we sought to evaluate the association between fibrinogen to albumin ratio (FAR) and the extent and severity of CAD evaluated by TAXUS Drug-Eluting Stent Versus Coronary Artery Bypass Surgery for the Treatment of Narrowed Arteries (SYNTAX) Score (SS) in patients with STEMI. METHODS A total of 278 patients with STEMI were included in the study. FAR was calculated using specified variables. The extent and severity of CAD were evaluated using the SS. The patients were divided into low- (SS <22) and high- (SS ≥22) risk groups. A Spearman rank correlation coefficient analysis was used for the relationship between FAR and SS. The cutoff points for sensitivity and specificity of FAR in predicting SS were estimated by performing a receiver operator characteristic curve analysis. RESULTS There were significant differences in the mean age (P=.016), admission serum albumin (P=.041), serum fibrinogen (P<.001), FAR (P<.001), and SS risk groups. Positive correlation was detected between FAR and SS (r=0.458, P<.001). A cutoff level of >87 FAR predicted SS (sensitivity, 70%; specificity, 70%), and an area under the curve of 0.758 serum fibrinogen and albumin level was an independent predictor for SS in patients with STEMI (b=0.039; 95% confidence interval, 0.016-0.062; P=.001 and b=-6.906; 95% confidence interval, -12.284 to -1.527; P=.013, respectively). CONCLUSION In the present study, we showed that FAR is significantly related to SS in predicting the severity of CAD in patients with STEMI.


Kaohsiung Journal of Medical Sciences | 2015

Investigation of possible prophylactic, renoprotective, and cardioprotective effects of thromboprophylactic drugs against ischemia–reperfusion injury

Sinan Demirtas; Oguz Karahan; Suleyman Yazıcı; Orkut Guclu; Ahmet Caliskan; Orhan Tezcan; İbrahim Kaplan; Celal Yavuz

The aim of this study was to investigate whether anticoagulant and antiaggregant agents have protective effects against oxidative damage induced by peripheral ischemia–reperfusion (I/R). Groups were created as follows: control group, I/R group (sham group), I/R plus acetylsalicylic acid (Group I), I/R+clopidogrel (Group II), I/R+rivaroxaban (Group III), I/R+bemiparin sodium (Group IV), and I/R+enoxaparin sodium (Group V). In Groups I, II, III, IV, and V, drugs were administered daily for 1 week before I/R creation. Peripheral I/R was induced in the I/R groups by clamping the right femoral artery. The rats were sacrificed 1 hour after reperfusion. Nitrogen oxide levels, malondialdehyde (MDA) levels, paraoxonase‐1 (PON1) activity, and prolidase activity were evaluated in both cardiac and renal tissues. There was no significant difference in nitrogen oxide levels between the groups. However, cardiac and renal MDA were significantly higher and PON1 activity was markedly lower in the I/R groups compared with the control group (p < 0.05). Although elevated prolidase activity was detected in both the cardiac and renal tissue of the I/R groups, only the sham group and Group V had significantly higher renal prolidase activity (p < 0.05). Group V had significantly higher cardiac MDA, PON1, prolidase levels, and renal prolidase activity compared with the sham group (p < 0.05). Significant improvement in renal MDA levels was only observed in Group III, and marked improvement was observed in the cardiac MDA levels of Group II when compared with the sham group (p < 0.05). Thromboprophylactic agents appear to provide partial or prominent protection against I/R injury.

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Mustafa Karabacak

Süleyman Demirel University

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