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Dive into the research topics where Ahmet Çolak is active.

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Featured researches published by Ahmet Çolak.


Journal of Clinical Neuroscience | 2007

Multilevel cervical fusion without plates, screws or autogenous iliac crest bone graft.

Mehmet Nusret Demircan; Ahmet Murat Kutlay; Ahmet Çolak; Serdar Kaya; Tamer Tekin; Kenan Kıbıcı; Kaan Ungoren

OBJECTIVE This prospective study was performed to evaluate the safety and efficacy of polyetheretherketone (PEEK) cages packed with demineralized bone matrix (DBM) mixed with autologous blood and curettage microchip material for treatment of multilevel cervical disc disease and spondylosis without the use of plates, screws or autogenous iliac crest bone graft. MATERIAL AND METHODS Sixteen patients underwent multilevel anterior cervical discectomy and fusion (ACDF) for a total of 42 levels. Minimum follow-up was 18 months. Neurological outcomes were evaluated using the Japanese Orthopaedic Association (JOA) scoring system; cervical lordosis and cervical fusion status was assessed on X-ray. Statistical analysis was performed to compare preoperative and postoperative scores using a dependent t-test (P<0.05). RESULTS Eight patients underwent two-level, six underwent three-level and two underwent four-level operations. The fusion rate was 90.5% and non-fusion rate was 9.5%, but reoperation was not required for these patients in the follow-up period. Cervical lordosis was preserved and neurological status was improved. No cage migration or cage failure occured. CONCLUSION ACDF using PEEK cages packed with DBM is a safe and efficient method for treatment of multilevel cervical disc disease and spondylosis. It preserves cervical lordosis and obviates the complications related to iliac crest graft harvest and screw-plate fixation.


Journal of Clinical Ultrasound | 2008

Sonographic appearances of the normal ulnar nerve in the cubital tunnel

Ersin Ozturk; Guner Sonmez; Ahmet Çolak; H. Onur Sildiroglu; Hakan Mutlu; Mehmet Guney Senol; C. Cinar Basekim; Esref Kizilkaya

To investigate the sonographic characteristics of the normal ulnar nerve in the cubital tunnel, as well as any differences related to age, sex, and dominant arm.


Journal of Clinical Neuroscience | 2008

Tauroursodeoxycholic acid and secondary damage after spinal cord injury in rats

Ahmet Çolak; Bilal Kelten; Ayhan Sağmanligil; Osman Akdemir; Alper Karaoğlan; Elife Şahan; Özge Çelik; Şeref Barut

Greater clinical understanding of the pivotal role of apoptosis in spinal cord injury (SCI) has led to new and innovative apoptosis-based therapies for patients with an SCI. Tauroursodeoxycholic acid (TUDCA) is a biliary acid with antiapoptotic properties. To our knowledge, this is the first study in the English language to evaluate the therapeutic efficacy of TUDCA in an experimental model of SCI. Thirty rats were randomized into three groups (sham-operated, trauma only, and trauma plus TUDCA treatment) of 10 each. In groups 2 and 3, spinal cord trauma was produced at the T8-T10 level via the Allen weight drop technique. Rats in group 3 were treated with TUDCA (200 mg/kg intraperitoneal) 1 min after trauma. The rats were killed either 24 h or 5 days after injury. The neuroprotective effect of TUDCA on injured spinal cord tissue and the effects of that agent on the recovery of hind-limb function were assessed. The efficacy of treatment was evaluated with histopathologic examination and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) analysis. Histopathologic characteristics were analyzed by comparison of hematoxylin-and-eosin stained specimens. Neurologic evaluations were performed 24 h, 3 days, and 5 days after trauma. Hind-limb function was assessed with the inclined plane technique of Rivlin and Tator and the modified version of Tarlovs grading scale. Twenty-four hours after injury, there was a significantly higher number of apoptotic cells in the lesioned spinal cord group than in the sham-operated control group. Treatment of the rats with TUDCA significantly reduced the number of apoptotic cells (4.52+/-0.30 vs. 2.31+/-0.24 in group 2) and the degree of tissue injury. Histopathologic examination showed that group 3 rats had better spinal cord architecture compared with group 2 rats. Five days after injury, the mean inclined plane angles in groups 1, 2, and 3 were 65.50 degrees +/- 2.09, 42.00 degrees +/- 2.74, and 53.50 degrees +/- 1.36. Motor grading of the rats revealed a similar trend. These differences were statistically significant (p<0.05). The mechanism of neuroprotection in the treated rats, although not yet elucidated, may be related to the marked antiapoptotic properties of TUDCA. A therapeutic strategy using TUDCA may eventually lead to effective treatment of SCI without toxic effects in humans.


Neurosurgical Review | 1991

Primary multiple cerebral hydatid cysts.

Oguz Cataltepe; Kadir Tahta; Ahmet Çolak; Aykut Erbengi

Primary multiple cerebral hydatid cysts are extremely rare: In this paper, an 8-year-old male patient who has one primary cerebral hydatid cyst in each cerebral hemisphere is presented. CT findings and operation are discussed. The literature is reviewed and the incidence of multiple cerebral hydatid cyst is compared with the published reports.


Neurosurgical Review | 1992

Meningiomas of the lateral ventricle. Report on six cases.

Hakan Caner; Bektaş Açikgöz; Tunçalp Özgen; Ahmet Çolak; Onol B

In this study 6 patients who had meningioma of the lateral ventricle are reviewed. The incidence is 1.8% of cases of meningiomas in our series. Microsurgical techniques were employed in all patients. There was no death and the follow-up period was between 5 months and 10 years. No recurrence was seen. Although the origin of these tumors is still not known, Dunn and Kernohan note that the choroid plexus has the potential for the production of menigothelial, fibrous, or mixed patterns. Our pathological results confirmed this suggestion.


Neurosurgical Review | 2004

Two-staged operation on C2 neoplastic lesions: anterior excision and posterior stabilization

Ahmet Çolak; Murat Kutlay; Kenan Kıbıcı; M. Nusret Demircan; Osman Niyazi Akin

This retrospective study included eight consecutive cases with C2 vertebral body neoplastic lesions. The anterior retropharyngeal approach was used to remove the lesions and decompress the spinal cord. Spinal stabilization with occipitocervical plating in a second-stage operation makes the treatment more tolerable for patients. The object of this study was to determine the effectiveness of a two-stage operation strategy for these lesions. Eight patients were operated on via anterior retropharyngeal approach and then stabilized with occipitocervical plates posteriorly in a second sitting. All neck pain and all dysphagia problems resolved. Partial neurologic improvement was achieved in three out of four patients. No postoperative infection was seen. The retropharyngeal approach to the upper cervical spine and anterior foramen magnum lesions is an effective alternative to transoral surgery because of low complication rates. Neoplastic lesions in the upper cervical spine can safely and effectively be operated with this technique. The general medical status of patients with malignancies does not permit too long, time-consuming operations. Stabilization of the spine in a separate operation increases patient tolerability without any morbidity.


Spine | 2008

Lumbar epidural capillary hemangioma presenting as lumbar disc herniation disease: case report.

Tamer Tekin; Fatih Bayrakli; Hakan Simsek; Ahmet Çolak; Murat Kutlay; Mehmet Nusret Demircan

Study Design. A case of lumbar spinal epidural hemangioma is presented. Objective. To present the first reported lumbar spinal epidural hemangioma patient clinically mimicking the lumbar disc herniation disease. Summary of Background Data. Capillary hemangiomas are benign endothelial cell neoplasms that are believed to be hamartomatous proliferations of vascular endothelial cells. The occurrence of spinal epidural capillary hemangiomas is exceedingly rare. There are only 3 reported epidurally located cases of capillary hemangiomas in the spinal channel in literature. Lumbar spinal epidural capillary hemangioma in a patient has not been previously reported. Methods. Radiologic features, pathology, and clinical course were documented. Results. L4 hypoesthesia and back pain of the patient was caused by an epidurally located capillary hemangioma. The neurologic symptoms of the patient were markedly improved after surgery. Conclusion. We have reported for the first lumbar epidural capillary hemangioma patient in literature. These lesions are benign and surgical treatment is curative.


Journal of Clinical Neuroscience | 2008

Therapeutic efficacy of Ac-DMQD-CHO, a caspase 3 inhibitor, for rat spinal cord injury

Osman Akdemir; Ismail Berksoy; Alper Karaoğlan; Şeref Barut; Kaya Bilguvar; Beyazit Cirakoglu; Elife Şahan; Ahmet Çolak

We investigated the therapeutic efficacy of Ac-DMQD-CHO, a caspase-3 inhibitor, and functional recovery in spinal cord injury in a rat model. Thirty rats were randomized into three groups of 10 each. In groups 2 and 3, spinal cord trauma was produced in the thoracic region. Group 3 rats were treated with Ac-DMQD-CHO. Treatment responses were evaluated based on histopathological and TUNEL staining findings at 24 h and 5 days post-injury. Neurologic performance was assessed during and following treatment. Twenty-four hours after injury, light microscopy examination revealed diffuse hemorrhagic necrosis, edema, vascular thrombi, and polymorphonuclear leukocyte infiltration in group 2 and 3 rats, but cavitation and demyelinization were less prominent in group 3. At this time point, treatment of the rats with Ac-DMQD-CHO significantly reduced the number of apoptotic cells. Traumatic injury to the spinal cord causes apoptosis and administration of Ac-DMQD-CHO decreases apoptosis and improves functional outcome.


European Spine Journal | 2007

Is there any relationship between proinflammatory mediator levels in disc material and myelopathy with cervical disc herniation and spondylosis? A non-randomized, prospective clinical study

Mehmet Nusret Demircan; Alparslan Asir; Ahmet Cetinkal; Nursal Gedik; Ahmet Murat Kutlay; Ahmet Çolak; Sedat Kurtar; Hakan Simsek

The proinflammatory mediator (PIM) levels were assessed in surgically removed samples of herniated cervical intervertebral discs. The objective of this study was to investigate if there is a correlation between the levels of PIMs in disc material and myelopathy associated with cervical intervertebral disc herniation and spondylosis. The role of proinflammatory mediators in the degeneration of intervertebral disc and the inflammatory effects of disc herniations on radicular pain has been previously published. However, the possible relationship between PIMs and myelopathy related to cervical disc herniation and spondylosis has not been investigated before. Thirty-two patients undergoing surgery for cervical disc herniation and spondylosis were investigated. Surgically obtained disc materials, stored at 70°C, were classified into two groups: cervical disc herniation alone or with myelopathy. Biochemical preparation and solid phase enzyme amplified sensitivity immunoassay (ELISIA) analysis of the samples were performed to assess the concentration of mediators in the samples. Very similar values of interleukin-6 were found in both groups whereas the concentrations of mediators were significantly higher in myelopathy group. This study has demonstrated that PIMs are involved in cervical intervertebral disc degeneration with higher concentrations in the samples associated with myelopathy.


Turkish Neurosurgery | 2009

The effects of meloxicam on neural tube development in the early stage of chick embryos.

Ahmet Cetinkal; Ahmet Çolak; Kivanc Topuz; Mehmet Nusret Demircan; Hakan Simsek; Berber U; Ahmet Sukru Umur; Mehmet Selçuki; Vatansever Hs

AIM The aim of this study is to demonstrate the effect of meloxicam in early stage chick embryos on neural tube development. MATERIAL AND METHODS One hundred specific pathogen-free (SPF) chicken eggs were used to investigate the neurulation. SPF eggs were invastigated in four groups (n:25). All of the groups were incubated at 37.2 +/- 0.1 degrees C and 60 +/- 5 % relative humidity for 30 hours, and an embryological development in the ninth stage as classified by Hamburger and Hamilton was obtained. In the end of the 30th hour, group A(control group) was administered 0.1 ml of saline (0.9% NaCl) in ovo and the other groups were administered meloxicam in increasing doses. At the end of 72 hours, all of the embryos were extracted from eggs and they underwent pathological examination with hematoxylin eosine and immunohistopathological examinations with CD138 and tubulin beta II. RESULTS While the groups Aand B showed no neural tube defects, totally eight defective embryos were detected in the groups C and D (three in group C and five in group D. CONCLUSION Our results suggested that meloxicam, a nonselective COX inhibitor, caused neural tube closure defects when injected at supratherapeutic doses. However, further studies with larger numbers of subjects are needed for its use in lower doses.

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Murat Kutlay

Military Medical Academy

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Ahmet Cetinkal

Military Medical Academy

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Serdar Kaya

University of Minnesota

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Hakan Simsek

Military Medical Academy

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Kivanc Topuz

Military Medical Academy

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Cem Atabey

Military Medical Academy

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Hakan Şimşek

Military Medical Academy

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