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Ahmet Colak

Publications and source records attributed to Ahmet Colak.

13 recordsLinked to original sources
PubMed2006

Distal-end aneurysm of the frontopolar artery with an atypical postoperative complication: case report.

OBJECTIVE: We present a unique case of a saccular aneurysm originating from the distal end of the right frontopolar artery (FPA). METHODS: This previously healthy, 54-year-old man had sustained a mild head trauma. On admission, he was lethargic, but his neurological examination results were otherwise normal. Neuroradiological studies (including brain computed tomography, magnetic resonance imaging, and cerebral angiography) demonstrated a distal-end aneurysm of the right FPA. The aneurysm was clipped and resected via a right frontal craniotomy. RESULTS: The postoperative course was uneventful. Pathological examination of the resected specimen confirmed rupture of the wall of a true aneurysm. The patient's medical history was also negative for trauma in the past, previous neurological disease, and vascular collagen disorders. Routine angiography performed 30 days postoperatively demonstrated complete occlusion of the right FPA. The patient was free of focal neurological deficits. CONCLUSION: This case demonstrates that not all distally located aneurysms are necessarily mycotic or traumatic.

Aneurysm, Ruptured↗
PubMed2005

Characterization of a thermoalkalophilic esterase from a novel thermophilic bacterium, Anoxybacillus gonensis G2.

Poly-3-hydroxybutyrate (P3HB) degradation capabilities of a novel bacterium, Anoxybacillus gonensis G2, were investigated. Both changes on film surfaces of the solution-cast films monitored by scanning electron microscopy (SEM) and weight loss up to 24% after 72 h exposure to A. gonensis G2 cultures indicated secretion of an active esterase responsible for the degradation of P3HB films. Kinetic parameters, Vmax and Km for the esterase activity of crude enzyme from A. gonensis G2 in the presence of p-nitrophenylbutyrate as substrate were observed as 50 U/L and 0.125 mM, respectively, in 50 mM phosphate buffer, pH 7.5 at 60 degrees C. The stimulation of the activity by Ca2+ is an evidence for the requirement of Ca2+ as a cofactor for the enzyme activity which is a characteristic for lipases/esterases. Inhibition of the esterase activity by metal chelating agents such as ethylenediamine tetraacetate, azide and cyanide has also supported the requirement of a metal ion for the activity. The thermal and pH stability profiles for the enzyme showed that the thermophilic bacterium A. gonensis G2 secretes an extracellular thermoalkalophilic PHB depolymerase active at 60 degrees C, and stable at this temperature for 120 min at pH 7.5 and for 24 h at pH 7.5-9.5 range at 4 degrees C by retaining over 75% of its initial activities.

Analysis of Variance↗
PubMed2005

A modified technique for syringo-subarachnoid shunt for treatment of syringomyelia.

Syringo-subarachnoid shunting is a well-established procedure for the treatment of syringomyelia. However, the standard surgical procedure requires a laminectomy and posterior midline myelotomy, which have potential complications. In this study, we describe our clinical experience with a modified technique for syringo-subarachnoid shunt insertion in eight patients between 1998 and 2002. The technique comprises a limited hemilaminectomy, a 2 mm myelotomy at the site of dorsal root entry zone, introduction of a 1.5 mm thick catheter into the syrinx and placement of the distal tip of the catheter in the anterolateral subarachnoid space. Using this technique there was no operative morbidity or mortality. Collapse of the syrinx, in the first post-operative month, was demonstrated by MRI in all cases. There were no relapses in the follow-up period. Although our experience is limited and the results preliminary, this technique is less invasive than commonly used techniques and the results are favorable.

Adult↗
PubMed2005

The neuroprotective effects of z-DEVD.fmk, a caspase-3 inhibitor, on traumatic spinal cord injury in rats.

BACKGROUND: Apoptosis is one of the most important forms of cell death seen in a variety of physiological and pathological conditions, including traumatic injuries. This type of cell death occurs via mediators known as caspases. Previous studies have investigated the roles that apoptosis and different caspases play in the pathogenesis of secondary damage after spinal cord injury (SCI). The aim of this research was to assess the neuroprotective effect of z-DEVD.fmk, a caspase-3 inhibitor, in a rat model of SCI. METHODS: Forty-five Wistar albino rats were studied in 3 groups of 15 animals: sham-operated control animals (group 1); trauma-only control animals (group 2); and rats subjected to trauma + z-DEVD.fmk treatment (group 3). Spinal cord injury was produced at the thoracic level using the weight-drop technique. Responses to injury and the efficacy of z-DEVD.fmk were assessed by light microscopy and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling staining in cord tissues collected at 4 and 24 hours posttrauma. Five rats from each group were used to assess functional recovery at 7 days after SCI. The functional evaluations were done using the inclined-plane technique and a modified Tarlov motor grading scale. RESULTS: At 4 hours postinjury, the mean apoptotic index in groups 1, 2, and 3 was 0, 33.01+/-6.62, and 16.40+/-4.91, respectively. The group 3 count was significantly lower than the group 2 count (P<.01). At 24 hours postinjury, light microscopic examination of group 2 tissues showed widespread hemorrhage, necrosis, polymorphonuclear leukocyte infiltration, and vascular thrombi. The group 3 tissues showed similar features. The prominent findings in group 2 were hemorrhage and necrosis, whereas the prominent findings in group 3 were focal hemorrhage and leukocyte infiltration. The mean inclined-plane angles in groups 1, 2, and 3 were 64.5 degrees+/-1.0 degrees, 41.5 degrees+/-1.3 degrees, and 47 degrees+/-2.0 degrees, respectively. Motor scale results in all groups showed a similar trend. CONCLUSION: Local application of z-DEVD.fmk after SCI in rats reduces secondary tissue injury and helps preserve motor function. These effects can be explained by inhibition of apoptotic death in all cell types in the spinal cord.

Animals↗
PubMed2005

Neuroprotection and functional recovery after application of the caspase-9 inhibitor z-LEHD-fmk in a rat model of traumatic spinal cord injury.

OBJECT: Apoptosis is considered one of the most significant mechanisms in the pathogenesis of neuronal damage after spinal cord injury (SCI). This form of cell death occurs via mediators known as caspases. The aim of this study was to evaluate the neuroprotective effect of the caspase-9 inhibitor, z-LEHD-fmk, in a rat model of spinal cord trauma. METHODS: Fifty-four Wistar albino rats were studied in the following three groups of 18 animals each: sham-operated controls (Group 1); trauma-only controls (Group 2); and trauma combined with z-LEHD-fmk-treated animals (0.8 microM/kg; Group 3). Spinal cord injury was produced at the thoracic level by using the weight-drop technique. Responses to SCI and the efficacy of z-LEHD-fmk treatment were determined on the basis of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling staining and light and electron microscopy findings in cord tissue at 24 hours and 7 days posttrauma. Six rats from each group were also assessed for functional recovery at 3 and 7 days after SCI. This was conducted using the inclined-plane technique and a modified version of the Tarlov motor grading scale. At 24 hours postinjury, light microscopic examination of Group 2 tissue samples showed hemorrhage, edema, necrosis, polymorphonuclear leukocyte infiltration, and vascular thrombi. Those obtained in Group 3 rats at this stage showed similar features. At 24 hours postinjury, the mean apoptotic cell count in Group 2 was significantly higher than that in Group 3 (90.25 +/- 2.6 and 50.5 +/- 1.9, respectively; p < 0.05). At 7 days postinjury, the corresponding mean apoptotic cell counts were 49 +/- 2.1 and 17.7 +/- 2.6, also a significant difference (p < 0.05). Electron microscopy findings confirmed the occurrence of programmed cell death in different cell types in the spinal cord and showed that z-LEHD-fmk treatment protected neurons, glia, myelin, axons, and intracellular organelles. CONCLUSIONS: Examination of the findings in this rat model of SCI revealed that apoptosis occurs not only in neurons and astrocytes but also in oligodendrocytes and microglia. Furthermore, immediate treatment with the caspase-9 inhibitor z-LEHD-fmk blocked apoptosis effectively and was associated with better functional outcome. More in-depth research of the role of programmed cell death in spinal cord trauma and further study of the ways in which caspases are involved in this process may lead to new strategies for treating SCI.

Analysis of Variance↗
PubMed2005

Stereotactic aspiration and antibiotic treatment combined with hyperbaric oxygen therapy in the management of bacterial brain abscesses.

OBJECTIVE: Despite advances in surgical techniques in the management of the brain abscess, long-term antibiotics are as crucial to cure as the initial surgical procedure itself. This study was designed to evaluate the effect of adjuvant hyperbaric oxygen (HBO) therapy on the duration of antibiotic treatment. METHODS: Between 1999 and 2004, 13 patients with bacterial brain abscesses treated with stereotactic aspiration combined with HBO and systemic antibiotic therapy. Patients younger than 18 years of age were excluded from this study. Postoperatively, all patients were given a 4-week course of intravenous antibiotics. Additionally, patients received hyperbaric oxygen (HBO, 100% O2 at 2.5 ATA for 60 min) twice daily for five consecutive days, and an additional treatment (100% O2 at 2.5 ATA for 60 min daily) was given for 25 days. RESULTS: There were eight male and five female patients. Their ages ranged between 18 and 71 years, with a mean of 43.9 years. The average duration of follow-up was 9.5 months (range, 8-13 mo). This treatment modality allowed infection control and healing for all 13 patients with 0% recurrence rate. HBO treatment was tolerated well, and there were no adverse effects of pressurization. At the end of the follow-up period, 12 patients had a good outcome: nine are without sequelae, and three have a mild hemiparesis but are capable of self-care. One patient has a moderate hemiparesis. CONCLUSION: Although the number of patients is small, this series represents the largest reported group of brain abscess patients treated with stereotactic aspiration combined with antibiotic and HBO therapy. Our preliminary results indicate that the length of time on antibiotics can be shortened with the use of HBO as an adjunctive treatment.

Adult↗
PubMed2005

Erythropoietin enhances neurological recovery after experimental spinal cord injury.

PURPOSE: Erythropoietin is a hematopoietic growth factor. It is also involved in neurodevelopment and neuroprotection. The purpose of this study was to evaluate the effectiveness of erythropoietin in enhancing the neurological recovery following experimental spinal cord injury. METHODS: Rats were randomly divided into 4 groups. Group 1 received only laminectomy. Group 2, 3, and 4 have undergone a spinal contusion injury of 50 gr/cm. Group 2 received no medication. Group 3 received 30 mg/kg methylprednisolone. Group 4 received 5000 IU/kg recombinant human erythropoietin. Following injury, neurological recovery was evaluated for 14 days, using a swimming test. RESULTS: At day 1, there was no difference between mean motor scores of group 2, 3, and 4. Following day 1, rats in group 4 exhibited a marked improvement in motor score, and this was maintained throughout the study. When compared to group 2, mean motor score of group 4 was significantly higher at day 4, 7, 10, and 14. When compared to group 3, mean motor score of group 4 was significantly higher at day 7, 10, and 14. CONCLUSION: These findings suggest that erythropoietin enhances neurological recovery following spinal cord injury and it seems to be more effective than methylprednisolone at the given doses.

Animals↗
PubMed2004

Evaluation of styloid process by three-dimensional computed tomography.

The purpose of this paper was to investigate the length, medial angulations and other structural variants of the styloid process (SP) by three-dimensional computed tomography (3D CT) in patients without any complaints related to elongated SP. We performed temporal computed tomography (CT) scans in 138 cases (87 males, 51 females) with a mean age of 34.5 (17-86). The structure, length and medial angulation of SPs were evaluated on 3D reconstructed images. SP lengths varied between 1.58 and 5.48 cm (average length 2.83 cm), and the angles varied between 60.6 and 84.1 degrees (average angle 69.4 degrees). Other morphological findings were absence of SP (3 unilateral and 1 bilateral), ossification of stylohyoid ligament (9 unilateral and 27 bilateral), irregular SP (5 unilateral and 5 bilateral), fragmentation of SP (12 unilateral and 9 bilateral), absence of the proximal part (5 unilateral and 9 bilateral) and double proximal part (1 unilateral). According to our results, we propose a new classification. Absence of SP, absence of the proximal part of SP, duplication of the proximal part of SP and angle values of SP have never been reported before according to the available medical literature. 3D CT is an effective method in the evaluation of the SP length, angulations and other morphological characteristics.

Adolescent↗
PubMed2003

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

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.

Aged↗
PubMed2003

Neuroprotective effects of GYKI 52466 on experimental spinal cord injury in rats.

OBJECT: The toxic effects of glutamate in the central nervous system are well known. This neurotoxicity occurs through metabotropic and ionotropic receptors, the latter group composed of N-methyl-D-aspartate, alpha-amino-3-hydroxy-5-methylisoxazole-4-proprionic acid (AMPA), and kainate receptors. The authors investigated the neuroprotective effects of GYKI 52466, a 2,3-benzodiazepine that is a selective and potent AMPA receptor antagonist, in a rat spinal cord trauma model. METHODS: Sixty Wistar albino rats were studied in three groups of 20 animals each: sham-operated controls (Group 1); spinal cord-injured rats (Group 2); and spinal cord-injured plus GYKI 52466-treated rats (Group 3). In Groups 2 and 3, spinal cord injury (SCI) was induced at the thoracic level by applying an aneurysm clip to the cord for 1 minute. One minute after the clip was removed, the rats in Group 3 received an intraperitoneal injection of 15 mg/kg GYKI 52466. Responses to injury and treatment were evaluated based on biochemical parameters (lipid peroxidation and adenosine 5'-triphosphate [ATP] levels in tissue), and on light and transmission electron microscopy findings in cord tissue collected at different times post-SCI. Five rats from each group underwent assessment of functional recovery at 1, 3, and 5 days after SCI; evaluation was performed using the inclined-plane technique and Tarlov motor grading scale. The mean lipid peroxidation levels in Groups 1 and 2 were 21.73 +/- 4.35 and 35.53 +/- 2.99 nmol/g of wet tissue, respectively. The level in Group 3 was 27.98 +/- 3.93 nmol/g of wet tissue, which was significantly lower than that in Group 2 (p < 0.01). The mean ATP levels in Groups 1 and 2 were 166.21 +/- 25.57 and 41.72 +/- 12.28 nmol/g of wet tissue, respectively. The ATP level in Group 3 was 85.82 +/- 13.92 nmol/g of wet tissue, which was significantly higher than that in Group 2 (p < 0.01). Light microscopic examination of Group 2 tissues showed hemorrhage, necrosis, polymorphonuclear leukocyte infiltration, and vascular thrombi. In contrast, the examination of Group 3 tissues showed limited hemorrhage and no necrosis or vascular thrombi. The most prominent findings in Group 2 were hemorrhage and necrosis, whereas the most prominent findings in Group 3 were focal hemorrhage and leukocyte infiltration. Electron microscopy demonstrated that GYKI 52466 protected the neurons, myelin, axons, and intracellular organelles. The mean inclined-plane angles in Groups 1, 2, and 3 were 65 degrees, 40 to 45 degrees, and 55 degrees, respectively. Motor scale results in all groups showed a similar trend. CONCLUSIONS: The findings in this rat model suggest that GYKI 52466 may provide significant therapeutic protection from secondary damage after acute SCI. This agent may be a viable alternative treatment for SCI.

Adenosine Triphosphate↗
PubMed2002

Cramp finding: can it be used as a new diagnostic and prognostic factor in lumbar disc surgery?

In this prospective study, the validity and the importance of a new finding (cramp finding) in the diagnosis and outcome after lumbar disc surgery were tested. The test is performed with the person in prone position. Against a forceful knee flexion, the examiner holds the leg with one hand and applies a force to overcome the knee flexion. The finding is positive if the examined person feels a disturbing cramp in the leg or thigh. The study was performed between October 1997 and December 1999. Besides the cramp finding, the classical disc herniation examination, including mechanical and neurological findings, magnetic resonance (MR) imaging tests, and laboratory findings were checked pre- and postoperatively. The positive cramp finding in the operated group was 72% (n=133) preoperatively and straight leg raising (SLR) test was positive in all of them. Cramp finding was positive in 70%, 52%, 34%, and 8% of patients postoperatively in the first, 3rd, 12th and 24th months, respectively. The presented finding appears to be as valuable as the SLR, and especially contralateral SLR, tests in lumbar disc surgery. Cramp finding is also important in outcome evaluation.

Adult↗
PubMed2002

Oxidative cleavage of DNA by homo- and heteronuclear Cu(II)-Mn(II) complexes of an oxime-type ligand.

Novel homodinuclear Cu(II) (K1), heterodinuclear Cu(II)-Mn(II) (K2) and homotrinuclear Cu(II) (K3) complexes with a novel oxime-type ligand have been prepared and their nucleolytic activities on pCYTEXP were established by neutral agarose gel electrophoresis. The analyses of the cleavage products obtained electrophoretically indicate that although the examined complexes induces very similar conformational changes on supercoiled DNA by converting supercoiled form to nicked form than linear form in a sequential manner as the complex concentration or reaction period is increased, K3 is less effective than the two others. The oxime complexes were nucleolytically active at physiological pH values but the activities of Kl or K2 were diminished by increasing the pH of the reaction mixture. In contrast, K3 makes dominantly single strand nicking by producing nicked circles on DNA at almost all the applied pH values. Metal complex induced DNA cleavage was also tested for inhibition by various radical scavengers as superoxide dismutase (SOD), azide, thiourea and potassium iodide. The antioxidants inhibited the nucleolytic acitivities of the oxime complexes but SOD afforded no protection indicating that the nucleolytic mechanism involves of copper and/or manganese complex-mediated reactive oxygen species such as hydroxyl radicals being responsible for the oxidative DNA cleavage.

Copper↗