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    PublicationOpen Access
    A class of Banach algebras whose duals have the Schur property
    (TÜBİTAK, 1999) Mustafayev, H.; Department of Mathematics; Department of Mathematics; Ülger, Ali; Faculty Member; College of Sciences
    Call a commutative Banach algebra A a γ-algebra if it contains a bounded group Λ such that aco(Λ) contains a multiple of the unit ball of A. In this paper, first by exhibiting several concrete examples, we show that the class of γ-algebras is quite rich. Then, for a γ-algebra A, we prove that A* has the Schur property iff the Gelfand spectrum Σ of A is scattered iff A* = ap(A) iff A* = Span(Σ).
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    A class of banach algebras whose duals have the schur property
    (Scientific and Technical research Council of Turkey - TUBITAK/Türkiye Bilimsel ve Teknik Araştırma Kurumu, 1999) Mustafayev, Heybetkulu; Department of Mathematics; Department of Mathematics; Ülger, Ali; Faculty Member; College of Sciences; N/A
    Call a commutative Banach algebra A a γ-algebra if it contains a bounded group Λ such that aco(Λ) contains a multiple of the unit ball of A. In this paper, first by exhibiting several concrete examples, we show that the class of γ-algebras is quite rich. Then, for a γ-algebra A, we prove that A* has the Schur property iff the Gelfand spectrum Σ of A is scattered iff A* = ap(A) iff A* = Span(Σ).
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    A potentially fatal outcome of oral contraceptive therapy: estrogen-triggered hereditary angioedema in an adolescent
    (Galenos Publishing House, 2023) 0000-0003-1377-8332; 0000-0001-9578-9267; 0000-0003-3919-7763; 0000-0003-2971-283X; 0000-0002-1115-9805; Balkanci, Ugur Berkay; Birben, Esra; Soyer, Ozge; N/A; Balkancı, Uğur Berkay; Demirkol, Demet; Mutlu, Rahime Gül Yeşiltepe; Yılmaz, Özlem; Saçkesen, Cansın; Undergraduate Student; Faculty Member; Faculty Member; Doctor; Faculty Member; School of Medicine; School of Medicine; School of Medicine; N/A; School of Medicine; N/A; N/A; N/A; Koç University Hospital; N/A; N/A; 108964; 153511; 140706; 182537
    Hereditary angioedema (HAE) is characterized by recurrent angioedema attacks with no urticaria. This disease has a high mortality due to asphyxia. Level of complement component 4 (C4), C1 esterase inhibitor (C1-INH) level and function, and genetic mutations determine different endotypes of HAE. Clinical presentation and the triggers of vasogenic edema may change according to the endotypes. An adolescent girl with oligomenorrhea, obesity, hirsutism, and acanthosis nigricans was diagnosed with polycystic ovary syndrome and prescribed ethinyl estradiol and cyproterone acetate containing oral contraceptive (OC). On the sixteenth day of treatment, she developed angioedema of the face, neck, and chest leading to dyspnea. Adrenaline, antihistamine, and corticosteroid treatments were ineffective. In the family history, the patient's mother and two cousins had a history of angioedema. C1-INH concentrate was administered with a diagnosis of HAE. C4 and C1-INH level and activity were normal. Genetic analysis identified a mutation in the factor 12 (F12) gene, and the diagnosis of F12-related HAE was made. OC treatment was discontinued. She has had no additional angioedema attacks in the follow-up period of two years. OC containing estrogen may induce the life-threatening first attack of F12-related HAE even in children. Recurring angioedema attacks in the family should be asked before prescribing estrogen-containing OC pills.
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    A prospective, multicentered study to assess social adjustment in patients with an intestinal stoma in Turkey
    (H M P Communications, 2015) Karabulut, Hatice; Baykara, Zehra G.; Harputlu, Deniz; Toyluk, Eylem; Ulusoy, Birgul; Karadag, Sercan; Kahraman, Aysel; Hin, Aysel Oren; Altinsoy, Meral; Akil, Yasemin; Leventoglu, Sezai; N/A; Karadağ, Ayişe; Faculty Member; School of Nursing; 3549
    Patients with a stoma undergo physiological, psychological, and social adjustment to their new life situation. A descriptive, prospective study was conducted to assess adaptation among patients > 18 years of age with a new temporary or permanent colostomy or ileostomy living in Turkey and receiving care at a participating stomatherapy unit. The study took place between September 1, 2011, and September 1, 2012. During hospitalization and following discharge, patients with a stoma received training and counseling according to their individual characteristics and their physiological, psychological, and social needs. Each participant completed the 19-item "Identification Form for Patients with a Stoma" at the beginning of the study to document sociodemographic and stoma characteristics. To assess adjustment to the stoma, The Ostomy Assessment Inventory (OAI-23) was administered 2 times - he first within 1 month and the second within 6 months after surgery or when a temporary stoma was closed (whichever came first). This instrument comprised 23 items regarding adaptation to the stoma using Likert-type response options (0-4 range). Total scores ranged from 10 to 92, with higher scores indicating better adjustment. The instruments were completed by stoma and wound care nurses during face-to-face interviews. Data were analyzed using the Kruskal-Wallis, Mann-Whitney, and Wilcoxon tests. of the 135 participants, the majority (77, 57.0%) were male; 73 (54.1%) had a colostomy, and 106 (78.5%) had a temporary stoma. The primary reason for stoma creation was cancer (89, 65.9%). Mean total OAI-23 scores were 48.63 +/- 13.75 at the first administration and 50.59 +/- 13.89 for the second. In terms of sociodemographic factors, significant increases in mean scores from the first to the second survey time were noted among patients in the 50-69 age group, women, married persons, and unemployed persons (P < 0.05). With regard to stoma characteristics, the OAI-23 scores of patients with planned stoma operations and persons with permanent stomas increased significantly (P < 0.05) between assessments. Significant increases in OAI-23 scores also were noted among persons who did not receive information before the operation, patients whose stoma site was not marked, and patients who had experienced a complication (P < 0.05). Postoperatively, it is important to consider sociodemographic and stoma characteristics as well as preoperative variables that may influence adaptation to stoma. Additional larger, multicentered studies with extended patient follow-up are warranted.
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    A Turkish 3-center study evaluation of serum folic acid and vitamin B12 levels in Alzheimer disease
    (Scientific and Technical Research Council Turkey (TUBITAK), 2015) Yılmaz, Gökhan; Erbayraktar, Zübeyde; Evlice, Ahmet Turan; Aras, Sevgi; Yener, Görsev; Avcı, Aslıhan; Ulusu, Nuriye Nuray; Faculty Member; School of Medicine; 6807
    Background/Aim: Alzheimer disease, a common proteopathy of advanced age, is characterized by cortical atrophy, neuron degeneration, neuronal loss, and accumulation of extracellular amyloid beta plaques. We aimed to investigate serum vitamin B12 and folic acid levels in Alzheimer disease and other dementia patients, as a potential screening test to detect presymptomatic Alzheimer disease in Turkish patients. Materials and Methods: We evaluated folic acid and vitamin B12 levels in Alzheimer disease patients as well as in other dementia and geriatric patients from Ankara, Dokuz Eylul, and Cukurova university hospitals; 290 female and male geriatric subjects were enrolled. Vitamin B12 and folic acid levels were measured using Roche E170 and Beckman Coulter DXI 800 immunoassays (chemiluminescence) according to the manufacturers' guideline in all centers. Results: We evaluated the results of folic acid and vitamin B12 in Alzheimer disease, other dementias and geriatric patients. No significant difference between the groups regarding the routine control of biochemical parameters was observed. Conclusion: Currently, serum folic and vitamin B12 levels are not diagnostically reliable tests for screening presymptomatic Alzheimer disease. However, the results may statistically be significant if we increase the sample size.
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    An alarming emergence of measles in Europe: gaps and future directions
    (Galenos Publ House, 2024) Ozsurekci, Yasemin; Ergönül, Önder; Koç Üniversitesi İş Bankası Enfeksiyon Hastalıkları Uygulama ve Araştırma Merkezi (EHAM) / Koç University İşbank Center for Infectious Diseases (KU-IS CID); School of Medicine
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    Approaches of pediatric nephrologists to hypertensive patients in Turkey (Turkish pediatric hypertension working group study)
    (Springer, 2018) Demir, Belde Kasap; Hacıhamdioğlu, Duygu Övüç; Girişgen, İlknur; Dursun, Hasan; Çivilibal, Mahmut; Benzer, Meryem; Bıyıklı, Neşe Karaaslan; Özkayın, Neşe; Sönmez, Ferah; Taşdemir, Mehmet; Faculty Member; School of Medicine; 175867
    Objective: We aimed to evaluate the approaches of pediatric nephrologists in our country to the management of childhood hypertension. Methods: The pediatric nephrologists in our country were invited to fill out an online questionnaire including 24 questions. The answers were compared between those working in the field for <= 10 years (Group 1, n =74) and >10 years (Group 2, n = 62). Results: of 136 participants (M/F = 101/35), 52% were following a single guideline [31% Fourth Report of 2004, 17% European Society of Hypertension in 2016, and 52% American Academy of Pediatrics in 2017], which is more common in Group 1 (P =.035). The most commonly used guideline was American Academy of Pediatrics of 2017 and Group 2 used Fourth Report of 2004 more commonly (P =.042). The most common choice to diagnose hypertension was office + home + ambulatory blood pressure monitoring (59%). The frequency of screening for end-organ damage at first evaluation was 96%. The time to wait for the effect of lifestyle modifications was 3 months in 52%. The first choice medication was angiotensin-converting enzyme inhibitors (49%) or calcium-channel blockers (48%) in non-obese and angiotensin-converting enzyme inhibitors (74%) in obese children. Calcium-channel blockers were more commonly prescribed as the first choice in non-obese children in Group 1 (P =.035). The most accessible emergency drug was esmolol. Conclusion: Despite following recent guidelines, the time spent in the proficiency would change the practices.
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    Bronchiectasis in Türkiye: data from a multicenter registry (Turkish adult bronchiectasis adtabase)
    (Galenos Publ House, 2024) Edis, Ebru Cakir; Cilli, Aykut; Kizilirmak, Deniz; Coskun, Ayson Sakar; Guler, Nurcan; Cicek, Sedat; Sevinc, Can; Agca, Meltem Coban; Gulmez, Inci; Kabak, Mehmet; Niksarlioglu, Elif Yelda Ozgun; Kokturk, Nurdan; Sayiner, Abdullah; Çağlayan, Benan Niku; School of Medicine
    Background: Bronchiectasis is a chronic lung disease characterized by permanent bronchial wall dilatation. Although it has been known as an orphan disease, it has recently gained attention because of registry -based studies and drug research. Aims: We aimed to use a multicenter database to analyze and compare data regarding the etiology, associated comorbidities, microbiological characteristics, and preventive strategies of bronchiectasis in T & uuml;rkiye to those of other countries. Study Design: A multicenter prospective cohort study. Methods: The multicenter, prospective cohort study was conducted between March 2019 and January 2022 using the Turkish Adult Bronchiectasis Database, in which 25 centers in T & uuml;rkiye participated. Patients aged > 18 years who presented with respiratory symptoms such as cough, sputum, and dyspnea and were diagnosed with non -cystic fibrosis bronchiectasis using computed tomography were included in the study. Demographic information, etiologies, comorbidities, pulmonary functions, and microbiological, radiological, and clinical data were collected from the patients. Results: Of the 1,035 study participants, 518 (50%) were females. The mean age of the patients was 56.1 +/- 16.1 years. The underlying etiology was detected in 565 (54.6%) patients. While postinfectious origin was the most common cause of bronchiectasis (39.5%), tuberculosis was identified in 11.3% of the patients. An additional comorbidity was detected in 688 (66.5%) patients. The most common comorbidity was cardiovascular disease, and chronic obstructive pulmonary disease (COPD) and bronchiectasis was identified in 19.5% of the patients. The most commonly detected microbiological agent was Pseudomonas aeruginosa (29.4%). Inhaled corticosteroids (ICS) were used in 70.1% of the patients, and the frequency of exacerbations in the last year was significantly higher in patients using ICS than in nonusers (p < 0.0001). Age [odds ratio (OR): 1.028; 95% confidence interval (CI): 1.005-1.051], cachexia (OR: 4.774; 95% CI: 2,054-11,097), high modified medical research council dyspnea scale score (OR: 1,952; 95% CI: 1,459-2,611), presence of chronic renal failure (OR: 4,172; 95% CI: 1,249-13,938) and use of inhaled steroids (OR: 2,587; 95% CI: 1,098-6,098) were significant risk factors for mortality. Mortality rates were higher in patients with COPD than in those with no COPD (21.7-9.1%, p = 0.016). Patients with bronchiectasis and COPD exhibited more frequent exacerbations, exacerbation -related hospitalizations, and hospitalization in the intensive care unit in the previous year than patients without COPD. Conclusion: This is the first multicenter study of bronchiectasis in T & uuml;rkiye. The study results will provide important data that can guide the development of health policies in T & uuml;rkiye on issues such as infection control, vaccination, and the unnecessary use of antibiotics and steroids.
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    Clinical parameters of laminoplasty and laminectomy with fusion in the treatment of cervical spondylosis and analysis of postoperative sagittal balance
    (Turkiye Klinikleri, 2023) 0000-0003-1342-7663; 0000-0002-3132-4839; 0000-0002-2198-565X; 0000-0001-7285-381X; N/A; N/A; Akgün, Mehmet Yiğit; Ateş, Özkan; Günerbüyük, Caner; Özer, Ali Fahir; Tepebaşılı, Mehmet Ali; Doctor; Faculty Member; Teaching Faculty; Faculty Member; Researcher; N/A; School of Medicine; School of Medicine; School of Medicine; School of Medicine; Koç University Hospital; N/A; N/A; N/A; N/A; 118533; 380939; 1022; N/A
    Background/aim: Cervical spondylosis is a progressive disease that causes degenerative changes affecting the spine, intervertebral discs, facets, and ligaments. With anterior and posterior surgical interventions, effective treatments can be applied in cervical spondylotic myelopathy (CSM). The relationship between regional and global spinal alignment and functional and pain outcomes was examined and it was revealed that these parameters play a significant role in obtaining good results. The aim of this study was to compare the perioperative and follow-up results of patients with CSM who underwent laminoplasty or laminectomy with fusion. Materials and method: CSM patients who were operated on between 2015 and 2020 and had at least 2 years of clinical and radiological follow-up were analyzed retrospectively. The patients were divided into 2 groups as the laminoplasty group and the laminectomy with fusion group, according to a simple random method. Demographic, clinical, radiological, and perioperative parameters were examined. Measurements were made by an independent observer using Surgimap and 2 years was considered to be sufficient time for the spine to take its final shape. Result: A total of 112 patients, including 68 males and 44 females, were included. Of these patients, 69 were in the laminectomy with fusion group, and 43 were in the laminoplasty group. Patient ages ranged from 39 to 85 years. The mean follow-up period was 36.28 months. In both groups, at the 3-month follow-up, a statistically significant improvement in the clinical parameters (neck disability index, visual analogue scale, modified Japanese Orthopaedic Association scores) was observed. When the preoperative cervical radiological parameters were evaluated, no statistically significant difference was found between the groups. The C2–C7 lordotic angles and the cervical SVA values were increased in the postoperative period, for both groups (p < 0.001). Although it is noteworthy that the increases were higher in the laminectomy with fusion group, no statistically significant difference was found between the groups. Conclusion: Deformity in a spinal segment may indirectly affect another segment. Being aware of the compensatory mechanisms and radiological parameters will help in determining the effective treatment plan.
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    Clinical, radiological, and surgical outcomes of 431 patients with adrenal incidentalomas: retrospective study of a 10-year single-center experience
    (Tubitak Scientific & Technological Research Council Turkey, 2024) Imga, Narin Nasiroglu; Aslan, Yilmaz; Catak, Merve; Tuncel, Altug; Berker, Dilek; N/A; Aykanat, İbrahim Can; N/A; Koç University Hospital
    Background/aim: The incidence of adrenal tumors is increasing due to the widespread utilization of radiographic imaging techniques. Factors such as tumor size, radiological characteristics, and functionality of adrenal adenomas play crucial roles in diagnosis and subsequent management. In this retrospective study, we investigated the clinical, radiological, and surgical features of patients with adrenal incidentalomas (AIs) and evaluated their follow-up results. Materials and methods: We analyzed data from 431 patients diagnosed with AIs (130 males, 301 females) who underwent adrenal hormone evaluation at our center. We compared nonfunctioning and functioning AIs in terms of radiological features. We also compared baseline and follow-up characteristics in nonfunctioning AIs. Results: The mean age of the patients was 55.4 +/- 11.5 years, with a mean tumor size of 25.9 +/- 14.3 mm. Mean follow-up duration was 3.17 +/- 2.07 years. Adenoma localization revealed 165 (38.3%) right-sided, 185 (42.9%) left-sided, and 81 (18.8%) bilateral cases. Most patients (76.6%) had nonfunctioning AIs. During follow-up, nonfunctioning AIs exhibited increased fasting blood glucose, fasting insulin and HOMA-IR values (p = 0.002, <0.001 and 0.004, respectively). Among the functioning AIs cases (23.4%), autonomous cortisol secretion, Cushing's syndrome, pheochromocytoma, and primary aldosteronism were observed in 10.4%, 5.1%, 3.9%, and 3.9% of cases, respectively. Receiver operating characteristic curve analysis determined an adrenal adenoma size of 26.5 mm as the optimal cut-off for distinguishing between functioning and nonfunctioning AIs, with a sensitivity and specificity of 61.4% and 70.0%, respectively. Conclusion: Although the majority of AIs are nonfunctioning, the prevalence of functioning adrenal adenomas is not rare. Our findings suggest that adenoma size emerges as a valuable predictor for early detection of functioning adenomas. In addition, smaller masses appear to carry a lower risk of malignancy.