Browsing by Author "Tunca, Zeliha"

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Citation - WoS: 9
Citation - Scopus: 12
Brain-Derived Neurotrophic Factor in Bipolar Disorder: Associations With Age at Onset and Illness Duration
(Pergamon-Elsevier Science Ltd, 2021) Baykara, Burak; Koc, Dogukan; Resmi, Halil; Akan, Pinar; Tunca, Zeliha; Ozerdem, Aysegul; Ceylan, Deniz
Bipolar disorder (BD) is a heterogeneous disorder that contains neurodevelopmental differences. Defining homogeneous subgroups of BD patients by using age at onset (AAO) as a specifier may promote the classification of biomarkers. This study compares peripheral BDNF levels between pediatric and adult BD patients to investigate the associations between BDNF levels, AAO, and illness duration. We enrolled two groups of euthymic patients, those with pediatric BD (n = 39) and those with adult BD (n = 31), as well as a group of healthy controls (HCs) (n = 90). Participants were assessed using clinical measures and BDNF serum levels were obtained using ELISA. We observed that BDNF levels were comparable between adult BD and HCs, but were clearly lower in pediatric BD than in HCs. In adult BD with AAO ?30 years, BDNF levels were significantly higher than in adult BD with AAO <30 years. In pediatric BD, patients with prepubertal-onset had higher BDNF levels than those with pubertalonset. BDNF levels demonstrated the accuracy of being able to distinguish pediatric BD from healthy controls in a receiver operating characteristic (ROC) curve analysis (area under the curve [AUC] = 0.792). In adult BD, higher BDNF levels were associated with later disease onset, but this was not the case in pediatric BD. Finally, reduced BDNF levels were associated with illness duration in adult BD. The findings indicate that BDNF levels in BD patients are associated with AAO. BDNF may, therefore, potentially serve as a developmental marker in BD, when AAO is taken into account.
Citation - WoS: 27
Citation - Scopus: 31
Dna Redox Modulations and Global Dna Methylation in Bipolar Disorder: Effects of Sex, Smoking and Illness State
(Elsevier Ireland Ltd, 2018) Ceylan, Deniz; Scola, Gustavo; Tunca, Zeliha; Isaacs-Trepanier, Cameron; Can, Gunes; Andreazza, Ana C.; Young, L. Trevor
DNA redox modulations and methylation have been associated with bipolar disorder (BD) pathophysiology. We aimed to investigate DNA redox modulation and global DNA methylation and demethylation levels in patients with BD during euthymia, mania or depression in comparison to non-psychiatric controls. The roles of sex and smoking as susceptibility factors for DNA redox modulations and global DNA methylation and demethylation were also explored. Levels of 5-methylcytosine (5-mC), 5-hydroxymethylcytosine (5-hmC) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) were assessed in DNA samples of 75 patients with DSM-IV BD type I (37 euthymic, 18 manic, 20 depressive) in comparison to 60 non-psychiatric controls. Levels of 5-mC and 5-hmC were assessed using Dot Blot as a screening process, and verified using ELISA. Levels of 8-OHdG were assessed using ELISA. The levels of 8-OHdG significantly differed among non-psychiatric control, euthymia, mania and depression groups [F (3,110) = 2.771, p = 0.046], whereas there were no alterations in the levels of 5-hmC and 5-mC. Linear regression analyses revealed the significant effects of smoking (p = 0.031) and sex (p = 0.012) as well as state of illness on the levels of 8-OHdG (p = 0.025) in patients with BD. Our results suggest that levels of 8-OHdG may be affected by sex, illness states and smoking in BD.
Citation - WoS: 18
Citation - Scopus: 20
Neurocognitive Functioning During Symptomatic States and Remission in Bipolar Disorder and Schizophrenia: a Comparative Study
(Elsevier Ireland Ltd, 2020) Ceylan, Deniz; Akdede, Berna Binnur; Bora, Emre; Aktener, Ahmet Yigit; Ongun, Ceren Hidiroglu; Tunca, Zeliha; Alptekin, Koksal
Aims Patients with bipolar disorder present milder cognitive impairment in comparison to patients with schizophrenia. Psychotic symptoms are associated with poorer cognitive functioning in both disorders. We aim to compare cognitive dysfunction between bipolar disorder and schizophrenia across symptomatic and remitted states. Methods An extensive cognitive battery was used to assess bipolar disorder patients (32 in manic episodes with psychotic features, 44 in euthymia), patients with schizophrenia (41 symptomatic, 39 remitted), and 55 healthy controls. A global cognitive factor and six neurocognitive domain factors were identified using principal component analyses. Results Global cognition components differed according to both illness and remission status; working memory differed according to remission status regardless of diagnosis; verbal fluency differed according to diagnosis regardless of remission status. An omnibus F test revealed that the remission state had a significant impact on processing speed in schizophrenia. Conclusion Our data suggest that both disorders are associated with state dependent (i.e., global cognition and working memory) and diagnosis dependent (i.e., global cognition and verbal fluency) neurocognitive dysfunctions. Processing speed was exclusively influenced by symptomatic states of schizophrenia.
Neurocognitive Functioning in Schizophrenia and Bipolar Disorder During the Remission and the Psychotic States
(Oxford Univ Press, 2018) Ceylan, Deniz; Akdede, Berna Binnur; Bora, Emre; Hidiroglu, Ceren; Tunca, Zeliha; Alptekin, Koksal; Ozerdem, Aysegul
[Abstract Not Available]
Citation - WoS: 26
Citation - Scopus: 31
Oxidatively-Induced Dna Damage and Base Excision Repair in Euthymic Patients With Bipolar Disorder
(Elsevier Science Bv, 2018) Ceylan, Deniz; Tuna, Gamze; Kirkali, Guldal; Tunca, Zeliha; Can, Gunes; Arat, Hidayet Ece; Kant, Melis
Oxidatively-induced DNA damage has previously been associated with bipolar disorder. More recently, impairments in DNA repair mechanisms have also been reported. We aimed to investigate oxidatively-induced DNA lesions and expression of DNA glycosylases involved in base excision repair in euthymic patients with bipolar disorder compared to healthy individuals. DNA base lesions including both base and nucleoside modifications were measured using gas chromatography-tandem mass spectrometry and liquid chromatography-tandem mass spectrometry with isotope-dilution in DNA samples isolated from leukocytes of euthymic patients with bipolar disorder (n = 32) and healthy individuals (n = 51). The expression of DNA repair enzymes OGG1 and NEIL1 were measured using quantitative real-time polymerase chain reaction. The levels of malondialdehyde were measured using high performance liquid chromatography. Seven DNA base lesions in DNA of leukocytes of patients and healthy individuals were identified and quantified. Three of them had significantly elevated levels in bipolar patients when compared to healthy individuals. No elevation of lipid peroxidation marker malondialdehyde was observed. The level of OGG1 expression was significantly reduced in bipolar patients compared to healthy individuals, whereas the two groups exhibited similar levels of NEIL1 expression. Our results suggest that oxidatively-induced DNA damage occurs and base excision repair capacity may be decreased in bipolar patients when compared to healthy individuals. Measurement of oxidatively-induced DNA base lesions and the expression of DNA repair enzymes may be of great importance for large scale basic research and clinical studies of bipolar disorder.
Peripheral Levels of Brain-Derived Neurotrophic Factor in Bipolar Disorder: Associations With Age at Onset and Illness Duration
(Wiley, 2020) Koc, Dogukan; Baykara, Burak; Tunca, Zeliha; Resmi, Halil; Ozerdem, Aysegul; Yalcin, Neslihan G.; Ceylan, Deniz
[Abstract Not Available]