Person: ÖZEN, AHMET OĞUZHAN
Loading...
Email Address
Birth Date
Research Projects
Organizational Units
Job Title
Last Name
ÖZEN
First Name
AHMET OĞUZHAN
Name
122 results
Search Results
Now showing 1 - 10 of 122
Publication Metadata only Outcome of hypogammaglobulinemia in children: Immunoglobulin levels as predictors(ACADEMIC PRESS INC ELSEVIER SCIENCE, 2010) ÖZEN, AHMET OĞUZHAN; Ozen, Ahmet; Baris, Safa; Karakoc-Aydiner, Elif; Ozdemir, Cevdet; Bahceciler, Nerin Nadir; Barlan, Isil BeratWe evaluated 131 children (M=88, F=43) with hypogammaglobulinemia Data was analyzed mainly for delineating predictor factors for outcome The distance from the lower limit of normal (-2SD) for any single measurement of immunoglobulins (Ig) was calculated and transformed into Ig scores Mean age and duration of follow up were 5 06 +/- 4 05 and 3 7 +/- 3 03 years, respectively The diagnoses were 22 CVID, 16 IgA deficiency, 33 transient hypogammaglobulinemia of childhood (THC), 3 selective IgM deficiency and 57 unclassified hypogammaglobulinemia (UCH) Low IgA scores (<-0 124) at presentation were indicative of subsequent development of IgA deficiency or CVID, whereas low IgM score (<-0 038) pointed towards more severe and persistent phenotypes Combination of low IgM score between 2 and 5 years, impaired antibody response and low B cell counts enabled us to predict persistence of hypogammaglobulinemia beyond 5 years (specificity = 90 5% and PPV = 94 9%) and chronic lung disease (sensitivity =90 4% and specificity = 68 3%) The set of criteria including low IgM scores, impaired antibody response and low B cell counts provided a high predictive value in detecting those with persistent hypogammaglobulinemia (C) 2010 Elsevier Inc All rights reservedPublication Open Access Outcome of Hematopoietic Stem Cell Gene Therapy for Wiskott-Aldrich Syndrome(AMER SOC HEMATOLOGY, 2019-11-13) ÖZEN, AHMET OĞUZHAN; Labrosse, Roxane; Chu, Julia; Armant, Myriam; van der Spek, Jet; Miggelbrink, Alexandra; Fong, Johnson; Everett, John K.; Raymond, Hayley; Kessler, Lyanna; Dansereau, Colleen; Mackinnon, Brenda; Koo, Stephanie; Morris, Emily; London, Wendy B.; Ozen, Ahmet; Baris, Safa; Despotovic, Jenny M.; Forbes, Lisa; Saitoh, Akihiko; Takachi, Takayuki; King, Alejandra; Thi Mai Anh Thi Nguyen; Vy Do Uyen Vu; Bushman, Frederic D.; Galy, Anne; Notarangelo, Luigi; Williams, David A.; Pai, Sung-YunPublication Open Access Immediate adverse reactions to intravenous immunoglobulin in primary immune deficiencies: a single center experience(2020) ÖZEN, AHMET OĞUZHAN; Nain, Ercan; Kıykım, Ayça; Kasap, Nurhan Aruci; Barış, Safa; Özen, Ahmet; Aydıner, Elif KarakoçPublication Open Access Protein Expression in the Diagnosis of LRBA Deficiency by Flow Cytometer(BILIMSEL TIP YAYINEVI, 2017-11-17) ÖZEN, AHMET OĞUZHAN; Ogulur, Ismail; Kiykim, Ayca; Nain, Ercan; Somer, Ayper; Guven, Ayla; Baris, Safa; Ozen, Ahmet; Karakoc Aydiner, ElifObjective: Lipopolysaccharide-responsive beige-like anchor (LRBA) plays a role in cell surface expression of inhibitory cytotoxic T lymphocyte-associated protein-4 (CTLA-4) protein. Recently identified LRBA deficiency leads to immune deficiency and autoimmunity and is diagnosed by mutation analyses and protein expression. Herein, we quantified stimulated and unstimulated intracellular LRBA protein expression by flow cytometry in LRBA deficiency patients. Materials and Methods: Five LRBA deficient patients and seven healthy controls were evaluated. The LRBA expressions were assessed in peripheral-blood-mononuclear-cells in the presence or absence of phorbol-miristat-acetate and ionomycin stimulation. The difference in mean-fluorescence-intensity (Delta MFI) was calculated. Results: The differences in mean-fluorescence-intensity values of LRBA by flow cytometry were 24 +/- 9 for the healthy controls and 4.8 +/- 2.8 for the patients..MFIs were 20.8 for P3, 19 for P4 and 49.6 for healthy controls with stimulants and 4.8, 4.6 and 20.1 respectively without stimulants. Conclusion: As a rapid and widely available assay, flow cytometric assessment of intracellular LRBA expression has been found to be an effective and reliable method in the identification of LRBA deficiency.Publication Open Access Management of inborn errors of immunity in the genomic era(2022-03-01) ÖZEN, AHMET OĞUZHAN; Demir D. D., Asnaashari K., Rezaei N., Ozen A.Inborn errors of immunity are a group of rare diseases characterized by a wide variety of manifestations, including unusually severe infections, cancer susceptibility, and exaggerated inflammation that disrupts organ function. As of 2022, over 450 gene deficiencies have been classified under ten categories, where numbers are constantly increasing. The range of inborn errors of immunity varies considerably, from mild infections to serious multisystemic disease. Whereas patients with T cell defects are liable to a broad range of pathogens, selected inborn errors of immunity may predispose hosts merely to a narrow range of microorganisms. Dysregulated immune responses often cause autoimmune manifestations that may target any organ or lead to severe allergies. Therefore, presentation to any medical discipline is possible. Historically, inborn errors of immunity have been associated with short life expectancy and poor life quality, but intensive research into the field has revolutionized this assumption. Especially with the aid of translational investigations, our clinical practice has transformed from a predominantly phenotype-driven management into one that is reinforced by an etiology-driven therapy. This review summarizes the recent advances in molecularly targeted treatment approaches in various inborn errors of immunity conditions, with many success stories corroborating the power of genomic medicine. The principles of applications learned from these rare monogenic traits, in which the functional impact of the molecular pathways is clear-cut, may be instructive for developing basic concepts toward precision therapy of the common immune-mediated disorders, including autoimmunity, infectious diseases, and allergy, which affect mass populations.Publication Metadata only Osteoporosis: An ignored complication of CVID(WILEY, 2011) ÖZEN, AHMET OĞUZHAN; Baris, Safa; Ozen, Ahmet; Ercan, Hulya; Karakoc-Aydiner, Elif; Cagan, Hasret; Ozdemir, Cevdet; Barlan, Metin; Bahceciler, Nerin N.; Barlan, Isil B.Background: Multiple factors in common variable immunodeficiency (CVID) might interfere with optimal growth and maturation and potentially compromise bone health. Methods: We aimed to evaluate bone mineral density (BMD) of patients with CVID using dual energy X-ray absorptiometry (DEXA) and investigate risk factors associated with decreased bone density. Results: Twenty-two patients were included (M: 16, F: 6) with a mean age of 15.6 +/- 9.0 yr. DEXA revealed osteopenia in 6/22 (27.3%) and osteoporosis in 9/22 (40.9%) at lumbar spine and osteopenia in 7/19 (37%) and osteoporosis in 3/19 (16%) at femoral neck sites. The age of subjects with osteoporosis was significantly higher than those without (21.6 +/- 8.0 vs. 9.0 +/- 5.7 yr; p < 0.0001). BMD z-scores were significantly lower in patients with bronchiectasis compared with those without (p = 0.03). Patients with osteoporosis at femoral neck site had lower forced expiratory volume in 1 s (FEV1) (p = 0.024), FEV1/forced vital capacity (FVC) (p < 0.0001), PEF (p = 0.008), and FEF 25-75 (p = 0.013) values compared with the patients with normal BMD z-scores. Low serum 25(OH) vitamin D levels were detected in 13/22 patients and low dietary calcium intake in 17/22 patients. BMD z-scores at femoral neck were lower in patients with low B-cell percentage (p = 0.03). BMD z-score at lumbar spine was correlated with folate (r = +0.63, p = 0.004) and serum immunoglobulin G levels (r = +0.430, p = 0.04). Conclusion: Osteoporosis appeared as an emerging health problem of patients with CVID, the risk increasing with older age and poorer lung function. Nutritional, biochemical, and immunologic factors appeared to take part in decreased BMD. Insight into the mechanisms of osteoporosis in CVID is crucial to develop preventive strategies.Publication Metadata only CHAPLE disease and non-CHAPLE protein losing enteropathies: natural history and immune characteristics(2021-08-01) SELÇUK, MERVE; BARIŞ, SAFA; ÖZEN, AHMET OĞUZHAN; ÖĞÜLÜR, İSMAİL; AYDINER, ELİF; Selcuk M., Sefer A. P., Baser D., Ogulur I., Eltan S. B., Dursun E., Kocamis B., Kasap N., BARIŞ S., AYDINER E., et al.Publication Open Access Severe Early-Onset Combined Immunodeficiency due to Heterozygous Gain-of-Function Mutations in STAT1(SPRINGER/PLENUM PUBLISHERS, 2016-10) ÖZEN, AHMET OĞUZHAN; Baris, Safa; Alroqi, Fayhan; Kiykim, Ayca; Karakoc-Aydiner, Elif; Ogulur, Ismail; Ozen, Ahmet; Charbonnier, Louis-Marie; Bakir, Mustafa; Boztug, Kaan; Chatila, Talal A.; Barlan, Isil B.Loss and gain-of-function (GOF) mutations in human signal transducer and activator of transcription 1 (STAT1) lead to distinct phenotypes. Although recurrent infections are common to both types of STAT1 mutations, GOF mutations are distinguished by chronic mucocutaneous candidiasis and autoimmunity. However, the clinical spectra of STAT1 GOF mutations continue to expand. We here describe two patients with STAT1 GOF mutations presenting early in life with combined immunodeficiency (CID). Clinical data and laboratory findings including immunophenotyping, level of interferon (IFN)-gamma/IL-17(+) T cells, interferon-induced STAT1 phosphorylation, and JAK inhibitor assays were evaluated. Sequencing of STAT1 gene was performed by Sanger sequencer. Patient 1 (P1) had persistent oral candidiasis and cytomegalovirus (CMV) infection since 2 months of age and later developed cavitary lung lesions due to Mycobacterium tuberculosis. Patient 2 (P2) presented with oral candidiasis and recurrent pneumonia at 4 months of age and subsequently developed CMV pneumonitis. Both patients suffered heterozygous missense mutations in STAT1, leading to deleterious amino acid substitutions in the DNA binding domain (P1: c.1154C > T; p.T385M; P2. c.971G > T; p.C324F). Circulating CD4(+) T cells of both patients exhibited increased interferon-gamma and decreased IL-17 expression as compared to controls. They also exhibited increased IFN-beta and -gamma-induced STAT1 phosphorylation that was reversed upon treatment with the JAK kinase inhibitor ruxolitinib. STAT1 GOF mutations may present early in life with CID, consistent with the clinical heterogeneity of the disease. JAK kinase inhibitors may potentially be useful in some patients as adjunct therapy pending definitive treatment with bone marrow transplantation.Publication Metadata only Evaluation of a Standardized Bakery Product (SUTMEK) as a Potential Tool for Baked-Milk Tolerance and Immunotherapy Research Studies(KARGER, 2019) ÖZEN, AHMET OĞUZHAN; Kiykim, Ayca; Karakoc-Aydiner, Elif; Gunes, Esra; Nain, Ercan; Ogulur, Ismail; Yazici, Duygu; Aktac, Sule; Bicer, Ayse Humeyra; Sackesen, Cansin; Baris, Safa; Ozen, AhmetBackground and Objectives: About 65-80% of children with IgE-mediated cow's milk allergy (CMA) can tolerate extensively heated milk. We have invested in the mass fabrication of a test product containing milk protein baked at 180 degrees C for 30 min (SUTMEK-milk) and a milk-free placebo (SUTMEK-placebo) to carry out a standardised double-blind placebo-controlled food challenge (DBPCFC) test in patients with CMA. Methods: We studied children with IgE-mediated CMA between 13 and 48 months of age. Specific IgEs (spIgE) to milk proteins were quantified. A DBPCFC with our bakery products was performed, and factors determining reactivity to extensively heated milk were evaluated. We also tested the applicability of SUTMEK products in baked-milk oral immunotherapy in a pilot assessment. Results: We studied 15 children (8 girls, 7 boys) with a median age of 26 months (range: 13-48 months). Nine (60%) patients tolerated a challenge with extensively heated milk, while 6 (40%) were found reactive (anaphylaxis: 2, wheezing: 2, urticaria: 2). spIgE to milk, alpha-lactalbumin, and casein, and the wheal diameter on skin prick testing were higher in the reactive group than the tolerant groups (p = 0.001, p = 0.001, p = 0.002, and p = 0.048, respectively). Receiver-operating characteristic curve analyses yielded the following cut-off values for spIgEs that would predict a reactivity to extensively heated milk; milk: 25 kU/L (area under curve, AUC: 0.981), casein: 32 kU/L (AUC: 0.983), and alpha-lactalbumin: 17 kU/L (AUC: 0.981). Nine patients have tolerated well a continued daily consumption of SUTMEK-milk or -placebo for 6 months at the desired doses. Conclusions: Our bakery products were successfully used in DBPCFC studies and qualified as an acceptable tool for use in the research of interventional tolerance induction. Although spIgE appears useful in determining children at high risk of reacting to extensively heated milk, the predictive cut-off values are still far from being perfect. (c) 2018 S. Karger AG, BaselPublication Metadata only Autosomal recessive agammaglobulinemic patient with a novel large deletion in IGHM presenting with mild clinical phenotype(2020) ÖZEN, AHMET OĞUZHAN; Nain, Ercan; Ulgen, Ozge; Kiykim, Ayca; Aydiner, Elif Karakoc; Ozen, Ahmet; Baris, Safa