Publications by authors named "Tuna Karahan"

9 Publications

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Aponeurotic release of semimembranosus: A technical note to increase correction gained with hamstring lengthening surgery in cerebral palsy.

Acta Orthop Traumatol Turc 2021 Mar;55(2):177-180

Department of Orthopaedics and Traumatology, Hacettepe University, School of Medicine, Ankara, Turkey.

Objective: The aim of this study was to determine the intraoperative corrective effect of the aponeurotic release of semimembranosus (SM) as a single procedure or an adjunct procedure to distal myotendinous release of semitendinosus (ST) and myofascial release of SM lengthening in the correction of knee flexion deformity in cerebral palsy (CP).

Methods: In this prospective study, 46 knees of 23 consecutive ambulatory patients (15 boys and 8 girls; mean age=8.33 years; age range=5-12 years) with spastic diplegic CP with a gross motor function classification system level (GMFCS) II or III were included. The patients were then divided into 2 groups. In group I, there were 10 patients (4 boys, 6 girls; mean age=8.6±2), and combined release of ST in the myotendinous junction and SM in the myofascial junction, followed by aponeurotic release of SM were carried out. In group II, there were 13 patients (2 girls, 11 boys; mean age=8±2.35), and aponeurotic release of SM was done first and followed by the combined release of ST in the distal myotendinous junction and the myofascial release of SM. Intraoperative popliteal angle (PA) measurements were recorded in each group.

Results: PA was reduced from 58.1°±7.6° (range=46°-75°) to 41.2°±8.8° (range=20°-54°) in group 1 and from 59.1°±11.3° (range=40°-87°) to 42.7°±10.8° (range=24°-64°) in group 2. No significant difference was observed between the groups in terms of reduction in PA (p=0.867). In group 1, adding the aponeurotic release of SM further reduced the PA to 31.7°± 8.5° (range=14°-47°) (p=0.002). In group 2, adding the myotendinous release of ST and myofascial release of SM further reduced the PA to 32.9°±7.2° (range=16°-44°) (p=0.004). There was no significant difference between the final PA values in the 2 groups (p=0.662). There was no difference in terms of early complications.

Conclusion: Aponeurotic release of SM is equally effective to reduce the intraoperative PA with combined myotendinous release of ST and myofascial release of SM. Combining all the 3 procedures provides a better correction without forceful manipulation or lengthening of the lateral hamstrings during the correction of knee flexion deformity in CP.
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http://dx.doi.org/10.5152/j.aott.2021.20184DOI Listing
March 2021

Intracavernous Injection of Human Umbilical Cord Blood Mononuclear Cells Improves Erectile Dysfunction in Streptozotocin-Induced Diabetic Rats.

J Sex Med 2017 01;14(1):50-58

Department of Pharmacology Faculty of Pharmacy, Ankara University, Ankara, Turkey. Electronic address:

Introduction: Erectile dysfunction (ED) worsens in men with diabetes. Human umbilical cord blood (HUCB), because of its widespread availability and low immunogenicity, is a valuable source for stem cell-based therapies.

Aim: To determine the effect of intracavernous injection of HUCB mononuclear cells (MNCs) on ED in rats with diabetes induced by streptozotocin.

Methods: Thirty adult male Sprague-Dawley rats were equally divided into three groups: (i) control, (ii) diabetes induced by streptozotocin (35 mg/kg intravenously for 8 weeks), and (iii) diabetic rats treated with MNCs (1 × 10 cells by intracavernosal injection). The HUCB-MNCs isolated by the Ficoll-Hypaque technique were obtained from eight healthy donors and administered to diabetic rats after 4 weeks.

Main Outcome Measures: The ratio of intracavernosal pressure to mean arterial pressure ratio; the protein expression of endothelial and neuronal markers, such as von Willebrand factor, neuronal nitric oxide synthase, hypoxia-inducible factor-1α, and vascular endothelium growth factor; and the relative area of smooth muscle to collagen using western blotting and Masson trichrome staining were determined.

Results: Diabetic rats demonstrated a significantly decreased ratio of intracavernosal pressure to mean arterial pressure (0.26 ± 0.04; P < .01) and treatment with MNCs restored erectile function in diabetic rats (0.67 ± 0.05) compared with control rats (0.56 ± 0.02). In bath studies, neurogenic relaxant and contractile responses were significantly decreased in diabetic cavernosal tissues, which were restored by treatment. The ratio of smooth muscle to collagen was partly recovered by treatment, whereas von Willebrand factor levels were not altered in any group. Neuronal nitric oxide synthase and vascular endothelium growth factor levels were decreased, which were not restored by treatment. Increased hypoxia-inducible factor-1α protein expression in the diabetic group was completely normalized in MNC-treated diabetic samples.

Conclusion: These results suggest that HUCB-MNC treatment can enhance the recovery of erectile function and promote numerous activities such the contribution of the hypoxia-inducible factor-1α and von Willebrand factor pathway to the neurogenic erectile response of diabetic rats. HUCB-MNCs in the healing process could involve an adaptive regenerative response and appear to be a potential candidate for cell-based therapy in ED of men with diabetes. It is evident that HUCB could provide a realistic therapeutic modality for the treatment of diabetic ED.
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http://dx.doi.org/10.1016/j.jsxm.2016.11.314DOI Listing
January 2017

The importance of vertebral artery proximity to the odontoid process during anterior odontoid approaches.

J Clin Neurosci 2009 Oct 1;16(10):1325-7. Epub 2009 Jul 1.

Department of Neurosurgery, Ankara Numune Education and Research Hospital, Samanpazari, Ankara 06100, Turkey.

The proximity of the vertebral artery (VA) to the odontoid process makes it vulnerable to injury during surgery. Knowledge of the quantitative anatomy of the VA groove is therefore necessary. In this study we assessed the spatial relationship between the VA and the odontoid process on cadavers by direct measurement and in patients by CT angiography. Our goal was to measure the distances from the VA and vertebrobasilar junction to the odontoid tip. The VA and odontoid process of 10 craniocervical cadavers ("cadavers") and of 20 patients were evaluated and average measurements obtained. The measured parameters were: (i) distance from the right VA to the odontoid tip (right VA-odontoid tip); (ii) distance from the left VA to the odontoid tip (left VA-odontoid tip), and (iii) distance from the vertebrobasilar junction to the odontoid tip (vertebrobasilar-odontoid tip). On the cadavers, the right VA-odontoid tip distance was 11.55mm, the left VA-odontoid tip was 11.02mm, and the vertebrobasilar junction-odontoid tip distance was 24.55mm. In patients, using CT angiography, the right VA-odontoid tip distance was 11.47mm and the left VA-odontoid tip distance was 11.50mm. The VA-odontoid tip distance is important in anterior odontoid approaches. Since the odontoid process may be in close contact with the VA, the relationship between them should be evaluated preoperatively in all candidates for odontoid surgery using three-dimensional CT angiography.
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http://dx.doi.org/10.1016/j.jocn.2009.01.008DOI Listing
October 2009

Anatomical study of axis for odontoid screw thickness, length, and angle.

Eur Spine J 2009 Feb 13;18(2):271-5. Epub 2008 Nov 13.

Department of Neurosurgery, Ankara Numune Education and Research Hospital, Samanpazari, 06550 Ankara, Turkey.

Anterior odontoid screw fixation is a safe and effective method for treatment of odontoid fractures. The screw treads should fit into the odontoid medulla, should pass the fracture line, and should pull fractured odontoid tip against body of axis in order to achieve optimum screw placement and treatment. This study has demonstrated optimal anterior odontoid screw thickness, length, and optimal angle for safe and strong anterior odontoid screw placement. Dry bone axis vertebrae were evaluated by direct measurements, X-ray measurements, and computerized tomography (CT) measurements. The screw thickness (inner diameter of the odontoid) was measured as well as screw length (distance between anterior-inferior point body of axis and tip of odontoid), and screw angle (the angle between basis of axis and tip of odontoid). The inner diameter of odontoid bone was measured as 6.5+/-1.9 mm, the screw length was 37.6+/-3.3 mm, and the screw angle was 62.4+/-4.7 on CT. There was no statistical difference between X-ray and CT in the measurements of screw thickness and angle. X-ray and CT measurements are both safe methods to determine the inner odontoid diameter and angle preoperatively. Screw length should be measured on CT only. To provide safe and strong anterior odontoid screw fixation, screw thickness, length, and angle should be known preoperatively, and these can be measured on X-ray and CT.
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http://dx.doi.org/10.1007/s00586-008-0814-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2899344PMC
February 2009

A neurosurgical view of anatomical evaluation of anterior C1-C2 for safer transoral odontoidectomy.

Eur Spine J 2008 Jun 20;17(6):853-6. Epub 2008 Mar 20.

Department of Neurosurgery, Ankara Numune Education and Research Hospital, Ankara, Turkey.

An anatomical study for evaluation of anterior C1-C2. To provide essential anatomic data for safer transoral odontoidectomy. The surface dimensions of the atlas vertebra and the transoral approach for odontoidectomy have been described in detail. Anterior arcus of C1 must be drilled out to reach odontoid process for transoral odontoidectomy. The thickness of anterior ring of C1 has not been studied before. Sixty, dried adult atlas and 60 axis vertebrae and ten cadaveric craniocervical specimens were measured for the following: (1) bony drilling depth (BDD), the distance from the anterior wall of anterior ring of C1 to anterior wall of odontoid; (2) minimum drilling diameter (MDD), distance of minimum C1 anterior ring removal for odontoid resection on horizontal plane; (3) maximum bony drilling diameter (MBDD), distance of maximum C1 anterior ring removal for odontoid resection on horizontal plane. Lateral border of this diameter is limited by medial borders of the lateral mass; (4) the widest odontoid diameters (WOD) on coronal sections were measured. On 60 atlas and axis vertebrae, the BDD was 7.0 +/- 1.2 mm on dry bones, the distance between the medial borders of the lateral mass (MBDD) was 16.1 +/- 1.5 mm, and the WOD on coronal sections (WOD) was 9.8 +/- 0.8 mm. On cadavers, the distance between the two edges of C1 anterior ring removal for odontoid resection (MDD) was 10.8 +/- 1.1 mm and the WOD on coronal sections (WOD) was 10.1 +/- 1.4 mm. An odontoid surgery through transoral approach is safe and feasible. A quantitative understanding of the anterior anatomy of C-1 and C-2 is necessary when considering transoral odontoid resection. In this study the authors define safe zones for anterior atlas and axis.
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http://dx.doi.org/10.1007/s00586-008-0647-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2518993PMC
June 2008

Effect of ascorbic acid treatment on endothelium-dependent and neurogenic relaxation of corpus cavernosum from middle-aged non-insulin dependent diabetic rats.

Int J Urol 2005 Sep;12(9):821-8

Department of Pharmacology, Faculty of Pharmacy, Ankara University, Ankara, Turkey.

Aims: The purpose of the present study was to investigate functional responses and nitric oxide synthase activity in the corpus cavernosum of young control, middle-aged control and middle-aged non-insulin dependent diabetic rats.

Methods: The animal groups were treated with ascorbic acid.

Results: Acetylcholine-mediated endothelium-dependent relaxation of cavernosal tissue was significantly attenuated from a maximum of 58.0 +/- 4.1% (1 mmol, n = 10) in young rats to 44.3 +/- 1.6% in aged-matched controls (P < 0.05) and to 23.3 +/- 2.8% in non-insulin-dependent diabetes mellitus rats (P < 0.01). These deficits in acetylcholine responsiveness were completely prevented by ascorbic acid treatment. Non-adrenergic non-cholinergic relaxations evoked by electrical field stimulation (0.5-64.0 Hz) in the corpus cavernosum of middle-aged control and non-insulin dependent (NID) diabetic rats are blunted and were not restored by ascorbic acid. The histochemical findings demonstrated a decrease of nicotinamide adenine dinucleotide phosphate-diaphorase staining in the cavernosal tissue obtained from middle-aged control rats and middle-aged diabetic rats.

Conclusion: Partial correction by ascorbic acid may suggest the importance of reactive oxygen species and a therapeutic approach in impotent NID diabetic men.
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http://dx.doi.org/10.1111/j.1442-2042.2005.01125.xDOI Listing
September 2005

Short-term effects of arsenic sulfur in deficits of contractile and relaxant responses on urinary bladder: pharmacological and structural changes.

Urol Int 2005 ;74(3):272-5

Department of Pharmacology, College of Pharmacy, Ankara University, Ankara, Turkey.

Introduction: Our goal was to investigate the effects of arsenic sulfur (AsS) on the detrusor smooth muscle reactivity.

Material And Methods: AsS (100 ppm microg/g) in drinking water was administered for 2 weeks to two groups of female Wistar rats. The contractile responses of urinary bladders to electrical field stimulation, carbachol, ATP and KCl, and the relaxant responses to ATP, adenosine and isoproterenol were examined. Urinary bladder strips were collected for light microscopic examination.

Results: Our results demonstrate that oral inorganic AsS exposure induced enhanced contractile and reduced relaxant responses in rats. We hypothesize that AsS is involved in deficiencies of isolated urinary bladder in rats.

Conclusion: These functional and morphological changes may be important as an intermediate link in urinary bladder oncogenesis induced by AsS.
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http://dx.doi.org/10.1159/000083562DOI Listing
July 2005

How we derived a core curriculum: from institutional to national--Ankara University experience.

Med Teach 2004 Jun;26(4):295-8

Department of Medical Education and Informatics, Faculty of Medicine, Ankara University, Ankara, Turkey.

As the first phase of a major curricular change in a large medical school the core curriculum had to be determined. The criteria for the inclusion of topics in the core curriculum were defined for both clinical and basic sciences. A large group of faculty members have worked in 11 sub-groups to determine the core knowledge, skills and attitudes for undergraduate medical students. During this work 608 clinical topics have been reviewed. Four-hundred and eighty five of them (79%) have been included in the core curriculum. Clinical and basic science knowledge, skills and attitudes relevant to these topics have been defined and classified. A total of 1610 cognitive, 428 psychomotor skills and 247 attitudes have been named. Thus the core curriculum defined is not just a set of diseases, conditions and symptoms but also includes the details of each and every topic. Starting from this point the medical school has participated actively in defining the national core curriculum, which has also been determined according to the same criteria.
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http://dx.doi.org/10.1080/01421590410001679433DOI Listing
June 2004