Research Outputs

Permanent URI for this communityhttps://hdl.handle.net/20.500.14288/2

Browse

Filters

2011 - 201932020 - 20221

Advanced Search

Filter by

Settings

Department: search.filters.department.Department of MathematicsSubject: search.filters.subject.Clinical neurology

Search Results

Now showing 1 - 4 of 4
  • Thumbnail Image
    PublicationOpen Access
    Censoring distances based on labeled cortical distance maps in cortical morphometry
    (Frontiers, 2013) Nishino, Tomoyuki; Alexopolous, Dimitrios; Todd, Richard D.; Botteron, Kelly N.; Miller, Michael I.; Ratnanather, J. Tilak; Department of Mathematics; Department of Mathematics; Ceyhan, Elvan; Undergraduate Student; Faculty Member; College of Sciences
    It has been demonstrated that shape differences in cortical structures may be manifested in neuropsychiatric disorders. Such morphometric differences can be measured by labeled cortical distance mapping (LCDM) which characterizes the morphometry of the laminar cortical mantle of cortical structures. LCDM data consist of signed/labeled distances of gray matter (GM) voxels with respect to GM/white matter (VW) surface. Volumes and other summary measures for each subject and the pooled distances can help determine the morphometric differences between diagnostic groups, however they do not reveal all the morphometric information contained in LCDM distances. To extract more information from LCDM data, censoring of the pooled distances is introduced for each diagnostic group where the range of LCDM distances is partitioned at a fixed increment size; and at each censoring step, the distances not exceeding the censoring distance are kept. Censored LCDM distances inherit the advantages of the pooled distances but also provide information about the location of morphometric differences which cannot be obtained from the pooled distances. However, at each step, the censored distances aggregate, which might confound the results. The influence of data aggregation is investigated with an extensive Monte Carlo simulation analysis and it is demonstrated that this influence is negligible. As an illustrative example, GM of ventral medial prefrontal cortices (VMPFCs) of subjects with major depressive disorder (MDD), subjects at high risk (HR) of MDD, and healthy control (Ctrl) subjects are used. A significant reduction in laminar thickness of the VMPFC in MDD and HR subjects is observed compared to Ctrl subjects. Moreover, the GM LCDM distances (i.e., locations with respect to the GM/WM surface) for which these differences start to occur are determined. The methodology is also applicable to LCDM-based morphometric measures of other cortical structures affected by disease.
  • Placeholder
    PublicationMetadata only
    Cerebral microhemorrhages detected by susceptibility-weighted imaging in amateur boxers
    (Amer Soc Neuroradiology, 2011) Hasiloğlu, Z. I.; Albayram, S.; Selçuk, H.; Delil, S.; Arkan, B.; Başköy, L.; Department of Mathematics; Department of Mathematics; Ceyhan, Elvan; Faculty Member; College of Sciences; N/A
    Background and Purpose: SWI is a new technique for evaluating diffuse axonal injury associated with punctate hemorrhages. The aim of our study was to determine the prevalence of cerebral microhemorrhages in amateur boxers compared with nonboxers by using SWI and to evaluate the sensitivity of SWI compared with T2 FSE and T2*GE sequences. MATERIALS and METHODS: We performed cranial MR imaging with a 1.5T scanner in 21 amateur boxers and 21 control subjects. The study protocol included conventional MR images, T2 FSE, T2*GE, and SWI sequences. The proportions of boxers and controls having CSP, DPVS, cerebral atrophy, cerebellar atrophy, ventricular dilation. PSWMD, and microhemorrhages were computed and were compared by using the chi(2) test of proportions. The relationship between microhemorrhages and boxing-related covariates was assessed by using the Wilcoxon rank sum test. The association between the categories was tested by using the Fisher exact test. RESULTS: Using SWI, microhemorrhages were found in 2 (9.52%) of 21 boxers. The microhemorrhages were not visible on T2 FSE or T2*GE images. The proportion of subjects with microhemorrhages did not differ significantly between the boxers and control subjects (chi(2) = 0.525, df = 1, P = .4688). The prevalence of CSP and DPVS was significantly higher in the boxers than in the control subjects. CONCLUSIONS: More microhemorrhages were detected in amateur boxers than in controls, but this difference was not statistically significant.
  • Thumbnail Image
    PublicationOpen Access
    Metric distances between hippocampal shapes indicate different rates of change over time in nondemented and demented subjects
    (Bentham Science, 2013) Beg, M. F.; Ceritoglu, C.; Wang, L.; Morris, J. C.; Csernansky, J. G.; Miller, M. I.; Ratnanather, J. T.; Department of Mathematics; Department of Mathematics; Ceyhan, Elvan; Undergraduate Student; Faculty Member; College of Sciences
    In this article, we use longitudinal morphometry (shape and size) measures of hippocampus in subjects with mild dementia of Alzheimer type (DAT) and nondemented controls in logistic discrimination. The morphometric measures we use are volume and metric distance measures at baseline and follow-up (two years apart from baseline). Morphometric differences with respect to a template hippocampus were measured by the metric distance obtained from the large deformation diffeomorphic metric mapping (LDDMM) algorithm. LDDMM assigns metric distances on the space of anatomical images, thereby allowing for the direct comparison and quantization of morphometric changes. We also apply principal component analysis (PCA) on volume and metric distance measures to obtain principal components that capture some salient aspect of morphometry. We construct classifiers based on logistic regression to distinguish diseased and healthy hippocampi (hence potentially diagnose the mild form of DAT). We consider logistic classifiers based on volume and metric distance change over time (from baseline to follow-up), on the raw volumes and metric distances, and on principal components from various types of PCA analysis. We provide a detailed comparison of the performance of these classifiers and guidelines for their practical use. Moreover, combining the information conveyed by volume and metric distance measures by PCA can provide a better biomarker for detection of dementia compared to volume, metric distance, or both.
  • Placeholder
    PublicationMetadata only
    The role of base excision repair in major depressive disorder and bipolar disorder
    (Elsevier, 2022) Küçüker, Mehmet Utku; Özerdem, Ayşegül; Cabello Arreola, Alejandra; Ho, Ada M. C.; Joseph, Boney; Webb, Lauren M.; Croarkin, Paul E.; Frye, Mark A.; Veldic, Marin; Department of Mathematics; Department of Mathematics; Ceylan, Deniz; Faculty Member; College of Sciences; 137755
    Background: In vivo and in vitro studies suggest that inflammation and oxidative damage may contribute to the pathogenesis of major depressive disorder (MDD) and bipolar disorder (BD). Imbalance between DNA damage and repair is an emerging research area examining pathophysiological mechanisms of these major mood disorders. This systematic review sought to review DNA repair enzymes, with emphasis on the base excision repair (BER), in mood disorders.Methods: We conducted a comprehensive literature search of Ovid MEDLINE (R) Epub Ahead of Print, Ovid MEDLINE (R) In-Process & Other Non-Indexed Citations, Ovid MEDLINE (R) Daily, EMBASE (1947), and PsycINFO for studies investigating the alterations in base excision repair in patients with MDD or BD.Results: A total of 1364 records were identified. 1352 records remained after duplicates were removed. 24 records were selected for full-text screening and a remaining 12 articles were included in the qualitative synthesis. SNPs (single nucleotide polymorphisms) of several BER genes have been shown to be associated with MDD and BD. However, it was difficult to draw conclusions from BER gene expression studies due to conflicting findings and the small number of studies. Limitations: All studies were correlational so it was not possible to draw conclusions regarding causality.Conclusion: Future studies comparing DNA repair during the manic or depressive episode to remission will give us a better insight regarding the role of DNA repair in mood disorders. These alterations might be utilized as diagnostic and prognostic biomarkers as well as measuring treatment response.