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Publication Metadata only A multinational cohort study examining sex differences in excess risk of death with graft function after kidney transplant(Lippincott Williams and Wilkins, 2024) Vinson, A.J,; Zhang, X.; Dahhou, M.; Döhler, B.; Sapir-Pichhadze, R.; Cardinal, H.; Melk, A.; Wong, G.; Francis, A.; Pilmore, H.; Foster, B.J.; Süsal, Caner; Koç University Transplant Immunology Research Centre of Excellence (TIREX); School of Medicine; Koç University HospitalBackground: Kidney transplant recipients show sex differences in excess overall mortality risk that vary by donor sex and recipient age. However, whether the excess risk of death with graft function (DWGF) differs by recipient sex is unknown. Methods: In this study, we combined data from 3 of the largest transplant registries worldwide (Scientific Registry of Transplant Recipient, Australia and New Zealand Dialysis and Transplant Registry, and Collaborative Transplant Study) using individual patient data meta-analysis to compare the excess risk of DWGF between male and female recipients of a first deceased donor kidney transplant (1988-2019), conditional on donor sex and recipient age. Results: Among 463 895 individuals examined, when the donor was male, female recipients aged 0 to 12 y experienced a higher excess risk of DWGF than male recipients (relative excess risk 1.68; 95% confidence interval, 1.24-2.29); there were no significant differences in other age intervals or at any age when the donor was female. There was no statistically significant between-cohort heterogeneity. Conclusions: Given the lack of sex differences in the excess risk of DWGF (other than in prepubertal recipients of a male donor kidney) and the known greater excess overall mortality risk for female recipients compared with male recipients in the setting of a male donor, future study is required to characterize potential sex-specific causes of death after graft loss.Item Metadata only A new checklist surgical hand scrub to replace time-based methods – a pixel intensity analysis(Elsevier Ltd, 2023) 0000-0003-1358-3236; 000-0002-8383-6000; N/A; 0000-0002-2137-1164; 0000-0001-7444-8906; N/A; 0000-0001-9034-9350; 0000-0002-8316-9623; 0000-0002-1968-7127; N/A; N/A; N/A; N/A; N/A; N/A; N/A; Department of Mechanical Engineering; N/A; Aslan, Lercan; Subaşı, Ömer; Mızıkoğlu, Duygu; Birsel, Olgar; Tanrıkulu, Seval, Baş, Ada; Arshad, Munam; Lazoğlu, İsmail; Seyahi, Aksel; Faculty Member; Researcher; Nurse; Faculty Member; Doctor; Other; Researcher; Faculty Member; Faculty Member; Manufacturing and Automation Research Center (MARC); School of Medicine; Graduate School of Sciences and Engineering; N/A; School of Medicine; N/A; N/A; Graduate School of Sciences and Engineering; College of Engineering; School of Medicine; Koç University Hospital; N/A; Koç University Hospital; N/A; Koç University Hospital; Koç University Hospital; N/A; N/A; N/A; N/A; 145301; N/A; N/A; 202021; N/A; N/A; N/A; 179391; 52082Background: Hand scrubbing is an absolute precaution to avoid surgical site infections. World Health Organization (WHO) recommends 4-min overall scrubbing (4MS) for surgical hand hygiene. However, we hypothesize that the more methodical 10-stroke counting technique (10SS) via locational partitioning of the arm is superior to WHO's superficial guideline dictating only the duration. Purpose: The mechanical efficiency of 4MS and 10SS techniques are compared. Methods: 24 healthcare professionals were recruited for the study. A novel methodology was devised to quantify the average brightness change of skin-applied UV ink before and after scrubbing via pixel intensity analysis. A black-box setup is constructed with an integrated high-resolution camera to photograph the UV-stained dorsal arm. Each stain was then digitally isolated for brightness comparison. Results: It was observed that the 10SS technique was overall more successful in removing the UV ink in comparison to the 4MS method (p = 0.014). In addition, a bias was observed in removing more percentage of the proximal stains when compared to middle and distal stains with the 4MS technique (p = 0.0027), while location-based brightness change averages were statistically equal with the 10SS technique (p = 0.423). Conclusions and Clinical Relevance: 10SS provided not only a more mechanically efficient scrubbing but also a more homogenous cleaning than 4MS. We recommend the use of the 10SS technique to achieve more effective pre-surgical hand hygiene.Publication Metadata only A new option for the reconstruction of orbital floor defects with heterologous cortical bone(Churchill Livingstone, 2015) Ozel, Bora; Findikcioglu, Kemal; Guney, Kirdar; Barut, Ismail; Ozmen, Selahattin; N/A; Sezgin, Billur; Faculty Member; School of Medicine; 133762Background: The orbital floor is one of the most frequently injured areas of the maxillofacial skeleton during facial trauma. A retrospective analysis of patients who have undergone treatment of orbital floor fractures with heterologous cortical bone is presented. Methods: This retrospective study was carried out with 21 patients over a period of 4 years between 2010 and 2014. All patients with a traumatic orbital floor defect who underwent reconstruction with heterologous cortical bone were included. The operations were carried out under general anesthesia for all patients. A subciliary incision was used in 20 patients and an infraorbital approach was used in one patient. All patients underwent follow-up examinations clinically as well as radiologically, at 1, 3, 6 and 12 months postoperatively. Computed tomographic scans were taken at the postoperative 6th month, and at the first postoperative year if needed. Results: Preoperatively, the physical examination revealed diplopia in 17 patients (80.9%), gaze restriction in 14 patients (66.6%), enophthalmos in six patients (28.5%), and infraorbital nerve paresthesia in two patients (9.5%). None of the patients showed impaired visual acuity preoperatively or postoperatively. Diplopia and gaze restriction resolved postoperatively in all of the patients. All patients had a negative intraoperative forced duction test demonstrating free globe movement. Enophthalmos showed complete resolution in the postoperative period. In one of the two patients with preoperative infraorbital nerve paresthesia, this resolved at the postoperative fifth month. Scleral show appeared in six patients but resolved completely within 3-8 weeks with massage. There was no graft extrusion, resorption or displacement during the follow-up period. Conclusions: Tecnoss Semi Soft Lamina is a good alternative for the reconstruction of blowout fractures due to its plasticity and biocompatible structure. Without donor site morbidity, it is a safe and appropriate heterologous bone graft material for maxillofacial applications such as orbital floor reconstruction. We cannot recommend its use for near-total, wide orbital floor defects as it may not provide enough support in such circumstances.Publication Metadata only A new technique for the surgical treatment of atlantoaxial instability: C1 lateral mass and C2-3 transfacet screwing(Turkish Neurosurgical Soc, 2018) N/A; N/A; N/A; N/A; Şentürk, Salim; Akyoldaş, Göktuğ; Yaman, Onur; Özer, Ali Fahir; Doctor; Faculty Member; Doctor; Faculty Member; N/A; School of Medicine; N/A; School of Medicine; Koç University Hospital; N/A; Koç University Hospital; N/A; 203677; 219524; 1022Atlantoaxial instability is a special entity that may be caused by many disorders such as trauma, tumor, arthritis, congenital malformation and infection. Atlantoaxial fixation is needed to provide stability, prevent neurological deficits and correct deformity. The aim of this report is to introduce an alternative technique for the treatment of atlantoaxial instability in patients who have vertebral artery anomaly, anomalous C2 or osteoporosis. C1-2-3 fixation was performed in a 50-year-old male patient with atlantoaxial instability due to os odontoideum. C1 lateral masses were identified and screw placement was performed. C2 facet joints were identified bilaterally. The superior margin of the junction of pedicle and the lamina was used as the entry point and 3.5x22 mm screws were inserted from C2 facet joint to the C3 facet joint in the mediolateral and craniocaudal direction under fluoroscopic guidance with caution. The posterior fixation screws were interconnected with two rods. Finally, autologous grafts were placed posterolaterally to encourage the fusion. The patient"s complaints were relieved after the surgery. C1-C2 instability was not seen in the postoperative radiological examinations. In the surgical treatment of C1-2 instability, our technique could help reduce the possibility of vertebral artery injury in patients who have a vertebral artery course anomaly or when it is difficult to place C2 pedicle screws due to anomalous C2 pedicles and osteoporosis. High fusion rate could be achieved with this technique due to passing through the four cortical surfaces. No wire or allograft was required. Thus, the instrumentation cost could be reduced.Publication Metadata only A new technique of doppler dearterialization for hemorrhoidal disease: arterial detection ligation (ADL)(Springer, 2021) Zenger, Serkan; Gürbüz, Bülent; Can, Uğur; Yaltı, Mehmet Tunç; Faculty Member; School of Medicine; 221690Purpose: We describe the arterial detection ligation (ADL) technique, designed to find arteries at time-appropriate depth for ligating, and report our preliminary results of using this technique to treat patients with the hemorrhoidal disease (HD). Methods: The subjects of this retrospective analysis were patients with symptomatic grades 2 or 3 HD. We analyzed the clinical characteristics, postoperative complications, recurrence, and patient satisfaction of the patients treated with ADL. Results: A total of 75 patients were included in the study (male/female ratio 1.88; mean age 48 ± 19 years; mean BMI 24 ± 3 kg/m2). Thirty-nine patients (52%) did not require hospitalization and were discharged from the day clinic approximately 4 h postoperatively. Four patients (5.3%) suffered tenesmus for about 1 week postoperatively and two (2.7%) suffered temporary rectal bleeding. The mean VAS scores 1 day postoperatively, then at 1 week, 1 month and 1 year were 2.9, 1.5, 0.4, and 0, respectively. At the 1-month follow-up, there was no sign of recurrence and the satisfaction rate was 78.6% (n = 59). At the 1-year follow-up, three patients (4%) had a recurrence and the satisfaction rate was 86.7% (n = 65). Conclusion: Based on our preliminary findings, ADL is an effective technique for treating HD, generally as an outpatient procedure, without serious morbidity. We anticipate that the incidence of tenesmus, which is encountered frequently after other dearterialization methods, will be lower after the ADL technique, which avoids both mass ligation of hemorrhoidal arteries deeper than 12 mm and running a long mucopexy suture line.Publication Metadata only A novel adjustable locking plate (ALP) for segmental bone fracture treatment(Elsevier Sci Ltd, 2019) N/A; N/A; Department of Mechanical Engineering; Department of Mechanical Engineering; Subaşı, Ömer; Oral, Atacan; Lazoğlu, İsmail; PhD Student; PhD Student; Faculty Member; Manufacturing and Automation Research Center (MARC); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 179391A novel Ti6Al4V adjustable locking plate (ALP) is designed to provide enhanced bone stability for segmental bone fractures and to allow precise positioning of disconnected segments. The design incorporates an adjustable rack and pinion mechanism to perform compression, distraction and segment transfer during plate fixation surgery. The aim of this study is to introduce the advantages of the added feature and computationally characterize the biomechanical performance of the proposed design. Structural strength of the novel plate is analyzed using numerical methods for 4-point bending and fatigue properties, following ASTM standards. An additional mechanical failure finite element test is also conducted on the rack and pinion to reveal how much torque can be safely applied to the mechanism by the surgeon. Simulation results predict that the new design is sufficiently strong to not fail under regular anatomical loading scenarios with close bending strength and fatigue life properties to clinically used locking compression plates. The novel ALP design is expected to be a good candidate for addressing problems regarding fixation of multi-fragmentary bone fractures.Publication Open Access A novel and simple machine learning algorithm for preoperative diagnosis of acute appendicitis in children(Springer, 2020) Türkmen, İnan Utku; Namlı, Gözde; Özturk, Çiğdem; Esen, Ayşe B.; Eray, Y. Nur; Akova, Fatih; Aydın, Emrah; Eroğlu, Egemen; Faculty Member; faculty Member; School of Medicine; 32059; N/AIntroduction: there is a tendency toward nonoperative management of appendicitis resulting in an increasing need for preoperative diagnosis and classification. For medical purposes, simple conceptual decision-making models that can learn are widely used. Decision trees are reliable and effective techniques which provide high classification accuracy. We tested if we could detect appendicitis and differentiate uncomplicated from complicated cases using machine learning algorithms. Materials and methods: we analyzed all cases admitted between 2010 and 2016 that fell into the following categories: healthy controls (Group 1); sham controls (Group 2); sham disease (Group 3), and acute abdomen (Group 4). The latter group was further divided into four groups: false laparotomy; uncomplicated appendicitis; complicated appendicitis without abscess, and complicated appendicitis with abscess. Patients with comorbidities and whose complete blood count and/or pathology results were lacking were excluded. Data were collected for demographics, preoperative blood analysis, and postoperative diagnosis. Various machine learning algorithms were applied to detect appendicitis patients. Results: there were 7244 patients with a mean age of 6.84 +/- 5.31 years, of whom 82.3% (5960/7244) were male. Most algorithms tested, especially linear methods, provided similar performance measures. We preferred the decision tree model due to its easier interpretability. With this algorithm, we detected appendicitis patients with 93.97% area under the curve (AUC), 94.69% accuracy, 93.55% sensitivity, and 96.55% specificity, and uncomplicated appendicitis with 79.47% AUC, 70.83% accuracy, 66.81% sensitivity, and 81.88% specificity. Conclusions: machine learning is a novel approach to prevent unnecessary operations and decrease the burden of appendicitis both for patients and health systems.Publication Open Access A novel Fontan Y-graft for interrupted inferior vena cava and azygos continuation(Oxford University Press (OUP), 2022) Çicek, Murat; Köse, Banu; Yılmaz, Emine Hekim; Aydemir, Numan Ali; Özkök, Serçin; Yurtseven, Nurgül; Erdem, Hasan; Sasmazel, Ahmet; Department of Mechanical Engineering; Department of Mechanical Engineering; Lashkarinia, Seyedeh Samaneh; Pekkan, Kerem; Rezaeimoghaddam, Mohammad; Rasooli, Reza; Faculty Member; Researcher; Graduate School of Sciences and Engineering; College of Engineering; N/A; 161845; N/A; N/AObjectives: to evaluate the hemodynamicdynamic advantage of a new Fontan surgical template that is intended for complex single-ventricle patients with interrupted inferior vena cava-azygos and hemi-azygos continuation. The new technique has emerged from a comprehensive pre-surgical simulation campaign conducted to facilitate a balanced hepatic flow and somatic Fontan pathway growth after Kawashima procedure. Methods: for 9 patients, aged 2 to 18 years, majority having poor preoperative oxygen saturation, a pre-surgical computational fluid dynamics customization is conducted. Both the traditional Fontan pathways and the proposed novel Y-graft templates are considered. Numerical model was validated against in vivo phase-contrast magnetic resonance imaging data and in vitro experiments. Results: the proposed template is selected and executed for 6 out of the 9 patients based on its predicted superior hemodynamic performance. Pre-surgical simulations performed for this cohort indicated that flow from the hepatic veins (HEP) do not reach to the desired lung. The novel Y-graft template, customized via a right- or left-sided displacement of the total cavopulmonary connection anastomosis location resulted a drastic increase in HEP flow to the desired lung. Orientation of HEP to azygos direct shunt is found to be important as it can alter the flow pattern from 38% in the caudally located direct shunt to 3% in the cranial configuration with significantly reversed flow. The postoperative measurements prove that oxygen saturation increased significantly (P-value = 0.00009) to normal levels in 1 year follow-up. Conclusions: the new Y-graft template, if customized for the individual patient, is a viable alternative to the traditional surgical pathways. This template addresses the competing hemodynamic design factors of low physiological venous pressure, high postoperative oxygen saturation, low energy loss and balanced hepatic growth factor distribution possibly assuring adequate lung development.Publication Open Access A novel modular dynamic stabilization system for the treatment of degenerative spinal pathologies(Turkish Neurosurgical Society, 2019) Çevik, Orhun Mete; Erbulut, Deniz Ufuk; Goel, Vijay; N/A; Özer, Ali Fahir; Yaman, Onur; Şentürk, Salim; Öktenoğlu, Bekir Tunç; Sasani, Mehdi; Süzer, Süleyman Tuncer; Faculty Member; Doctor; Doctor; Faculty Member; School of Medicine; 1022; N/A; N/A; N/A; N/A; 221691Aim: to show the preliminary clinical results of the Orthrus modular dynamic stabilization system that is a new instrumentation system intended for degenerative diseases of the lumbar spine. Material and methods: the system utilizes two different types of screws that can be used in conjunction with different types of rods such as titanium, carbon fiber or PEEK. The first type of screw is a double headed screw to interconnect to the upper and lower level with independent rods. The second type of screw is a sliding screw to be used on a immovable vertebrae that allows movement in two planes on the tip. Results: the system has been used on 36 patients with pathology varying from degenerative disc disease to degenerative lumbar scoliosis. Satisfactory results have been obtained in a all 36 patients in the 12-month follow-up period. Conclusion: the Orthrus dynamic system shows better clinical results than the available dynamic systems on the market. It also proves to provide similar fusion with considerably less postoperative morbidity which makes it a better method to treat adult degenerative spine diseases for carefully chosen patients.Publication Metadata only A potential therapeutic pitfall in the treatment of venous reflux due to variant planar anatomy of varicose segments(Sage, 2018) N/A; N/A; N/A; N/A; Deniz, Sinan; Türeli, Derya; Erkan, Burcu; Oğuzkurt, Levent; Doctor; Doctor; Faculty Member; Faculty Member; N/A; N/A; School of Medicine; School of Medicine; Koç University Hospital; N/A; N/A; N/A; 13559Purpose To elaborate on a planar anatomic variant of great saphenous vein as a potential therapeutic pitfall in the treatment of venous reflux. Materials and methods Lower extremity veins in 568 limbs with great saphenous vein insufficiency were sonographically mapped. A rather overlooked variation, the saphenous bow, was studied with emphasis on anatomic clarification and its involvement in venous insufficiency. Results This variation, observed in 5.1% (n=29) of limbs, comprised two segments; one uninterrupted great saphenous vein proper coursing throughout saphenous compartment and one extra-compartmental segment originating distally from and proximally fusing with it. Venous arch remains within compartment only briefly during take-off and re-entry. Extra-compartmental venous arch had reflux either alone (10.3%) or together with intra-compartmental segment (75.9%). Conclusion This variation, part of saphenous segmental aplasia/hypoplasia complex, is associated with venous insufficiency. Meticulous mapping of great saphenous vein territory and identification of such variants during planning stage is indispensable for optimal clinical outcomes of treatment.