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Georgios Nikolaou,Aristeidis H. Zibis,Apostolos H. Fyllos,Antonios Katsioulis,Sotirios Sotiriou,Anastasios Kotrotsios,Markos Sgantzos,Aikaterini Vassiou,Dimitrios L. Arvanitis 대한척추외과학회 2017 Asian Spine Journal Vol.11 No.6
Study Design: Human herniated discs were obtained from discectomy specimens for the immunohistochemical detection of OGlcNAc and O-GlcNAcase (OGA)/O-GlcNAc transferase (OGT). Purpose: This study aimed to quantify the extent of O-GlcNAcylation and its associated enzymes (OGT/OGA) in human degenerated intervertebral discs. Overview of Literature: The O-GlcNAcylation of nuclear, cytoplasmic, and mitochondrial proteins as well as the effects of such post-translational modifications are currently the focus of extensive research. O-GlcNAcylation is believed to contribute to the etiology of chronic illnesses by acting as a nutrient and stress sensor in the cellular environment. Mature intervertebral disc cells are chondrocyte-like cells, and O-GlcNAc has been shown to promote chondrocyte apoptosis in vitro . We believe that O-GlcNAcylation is a key regulator of disc degeneration. Methods: Fifty-six specimens were fixed for 24 hours in a 10% solution of neutral-buffered formaldehyde, dehydrated, and embedded in paraffin. Tissue slices (4-μm-thick) were used for hematoxylin-eosin staining and immunohistochemistry. Results: We found that O-GlcNAcylation of cytoplasmic proteins was less than that of nuclear proteins in both single cells and cell clusters. Cytoplasmic O-GlcNAcylation occurs subsequent to nuclear O-GlcNAcylation and is directly proportional to disc degeneration. OGT and O-GlcNAc expression levels were identical in all specimens examined. Conclusions: O-GlcNAc and OGA/OGT expression is shown to correlate for the first time with intervertebral disc cell degeneration. Increasing disc degeneration is associated with increasing O-GlcNAcylation in both nuclear and cytoplasmic proteins in human disc cells.
The Unclear Legal Framework as a Deterring Parameter Of Developing Cave Tourism in Greece
( Dimitrios Mylonopoulos ),( Polyxeni Moira ),( Nikolaou Eleni ) 한국문화관광학회 2016 문화관광연구 Vol.18 No.2
Cave tourism is a special form of tourism, part of the broader category of geotourism. In Greece, despite the vast speleological wealth, the special and alternative form of cave tourism has not been exploited properly.This essay has been based on thorough research of the legal framework and case law that refer directly or indirectly to the protection of caves and the development of cave tourism. In addition, using websites of both state and private institutions as well as of speleological institutions, operating caves and their management bodies have been recorded. It appears that the complicated and unclear legal framework regulating ownership and supervision of caves in Greece contributes to their non-exploitation. The essay proposes the conduction of a new research to complete recording in a single database the existing exploited caves of the country, the setup of a "registry of exploited tourist caves" and the creation of a clear legislative framework that shall promote and exploit them. Furthermore, the inclusion of caves in regional tourism policy plans in order to achieve rational development of cave tourism in Greece.
77‐GHz mmWave antenna array on liquid crystal polymer for automotive radar and RF front‐end module
김상길,Amin Rida,Vasileios Lakafosis,Symeon Nikolaou,Manos M. Tentzeris 한국전자통신연구원 2019 ETRI Journal Vol.41 No.2
This paper introduces a low‐cost, high‐performance mmWave antenna array module at 77 GHz. Conventional waveguide transitions have been replaced by 3D CPW‐microstrip transitions which are much simpler to realize. They are compatible with low‐cost substrate fabrication processes, allowing easy integration of ICs in 3D multi‐chip modules. An antenna array is designed and implemented using multilayer coupled‐fed patch antenna technology. The proposed 16 × 16 array antenna has a fractional bandwidth of 8.4% (6.5 GHz) and a 23.6‐dBi realized gain at 77 GHz.
Storz, Corinna,Kolb, Manuel,Kim, Jong Hyo,Weiss, Jakob,Kunz, Wolfgang G.,Nikolaou, Konstantin,Bamberg, Fabian,Othman, Ahmed E. Elsevier 2018 Academic radiology Vol.25 No.3
<P><B>Rationale and Objectives</B></P> <P>To determine the intraindividual impact of radiation dose reduction in abdominal computed tomography (CT) on diagnostic performance in patients with suspected appendicitis.</P> <P><B>Materials and Methods</B></P> <P>This study was approved by the institutional review board. Seventy-five patients who underwent standard contrast-enhanced abdominal CT for suspected appendicitis between 2004 and 2009 were retrospectively included. Low-dose CT reconstructions with 75%, 50%, and 25% of the original radiation dose level were generated by applying realistic reduced-dose simulation. Two blinded, independent readers assessed image quality, signal-to-noise ratio, and diagnostic confidence on each dataset. Diagnostic accuracy for detection of appendicitis and complications were calculated for each reader. Paired univariate tests were used to determine intraindividual differences.</P> <P><B>Results</B></P> <P>Among 75 subjects included in the analysis (57% female, mean age: 41 ± 18 years), the prevalence of histopathologically confirmed appendicitis was 59%. Signal-to-noise ratio and subjective image quality of 50% and 25% reduced-dose CTs were significantly lower than the reference datasets (all <I>P</I> < .005). Appendicitis was correctly identified in all reference and low-dose datasets (sensitivity: 100%, negative predictive value: 100%). Presence of complications was correctly detected in all reference, 75%, and 50% datasets, but was decreased in 25% datasets (sensitivity: 77.8% and negative predictive value: 97.4%). Diagnostic confidence was high for original and 75% datasets, but significantly lower for 50% and 25% datasets (<I>P</I> < .001).</P> <P><B>Conclusions</B></P> <P>Our results indicate that diagnostic accuracy in abdominal CT acquisitions acquired at 75% and 50% of radiation dose is maintained in patients with suspected appendicitis, whereas further reduction of radiation exposition is associated with decreased diagnostic performance.</P>
Afat, Saif,Brockmann, Carolin,Nikoubashman, Omid,Mü,ller, Marguerite,Thierfelder, Kolja M.,Brockmann, Marc A.,Nikolaou, Konstantin,Wiesmann, Martin,Kim, Jong Hyo,Othman, Ahmed E. Radiological Society of North America 2018 Radiology Vol.287 No.2
<P>Conclusion: The results suggest that radiation dose reduction to 40% of original dose levels (tube current-time product, 72 mAs) may be performed in VP CT imaging of patients with aneurysmal subarachnoid hemorrhage without compromising the diagnostic accuracy regarding detection of cerebral perfusion impairment indicating vasospasm. (C)RSNA, 2018</P>
Othman, A. E.,Brockmann, C.,Yang, Z.,Kim, C.,Afat, S.,Pjontek, R.,Nikoubashman, O.,Brockmann, M. A.,Nikolaou, K.,Wiesmann, M. SPRINGER INTERNATIONAL 2016 EUROPEAN RADIOLOGY Vol.26 No.1
<P>To examine the impact of denoising on ultra-low-dose volume perfusion CT (ULD-VPCT) imaging in acute stroke. Simulated ULD-VPCT data sets at 20 % dose rate were generated from perfusion data sets of 20 patients with suspected ischemic stroke acquired at 80 kVp/180 mAs. Four data sets were generated from each ULD-VPCT data set: not-denoised (ND); denoised using spatiotemporal filter (D1); denoised using quanta-stream diffusion technique (D2); combination of both methods (D1 + D2). Signal-to-noise ratio (SNR) was measured in the resulting 100 data sets. Image quality, presence/absence of ischemic lesions, CBV and CBF scores according to a modified ASPECTS score were assessed by two blinded readers. SNR and qualitative scores were highest for D1 + D2 and lowest for ND (all p a parts per thousand currency signaEuro parts per thousand 0.001). In 25 % of the patients, ND maps were not assessable and therefore excluded from further analyses. Compared to original data sets, in D2 and D1 + D2, readers correctly identified all patients with ischemic lesions (sensitivity 1.0, kappa 1.0). Lesion size was most accurately estimated for D1 + D2 with a sensitivity of 1.0 (CBV) and 0.94 (CBF) and an inter-rater agreement of 1.0 and 0.92, respectively. An appropriate combination of denoising techniques applied in ULD-VPCT produces diagnostically sufficient perfusion maps at substantially reduced dose rates as low as 20 % of the normal scan. aEuro cent Perfusion-CT is an accurate tool for the detection of brain ischemias. aEuro cent The high associated radiation doses are a major drawback of brain perfusion CT. aEuro cent Decreasing tube current in perfusion CT increases image noise and deteriorates image quality. aEuro cent Combination of different image-denoising techniques produces sufficient image quality from ultra-low-dose perfusion CT.</P>
Nina F. Schwenzer,Ferdinand Seith,Sergios Gatidis,Cornelia Brendle,Holger Schmidt,Christina A. Pfannenberg,Christian laFougère,Konstantin Nikolaou,Christina Schraml 대한영상의학회 2016 Korean Journal of Radiology Vol.17 No.5
Objective: First, to investigate the diagnostic performance of fast T1-weighted sequences for lung nodule evaluation in oncologic magnetic resonance (MR)/positron emission tomography (PET). Second, to evaluate the influence of image acquisition in inspiration and expiration breath-hold on diagnostic performance. Materials and Methods: The study was approved by the local Institutional Review Board. PET/CT and MR/PET of 44 cancer patients were evaluated by 2 readers. PET/CT included lung computed tomography (CT) scans in inspiration and expiration (CTin, CTex). MR/PET included Dixon sequence for attenuation correction and fast T1-weighted volumetric interpolated breath-hold examination (VIBE) sequences (volume interpolated breath-hold examination acquired in inspiration [VIBEin], volume interpolated breath-hold examination acquired in expiration [VIBEex]). Diagnostic performance was analyzed for lesion-, lobe-, and size-dependence. Diagnostic confidence was evaluated (4-point Likert-scale; 1 = high). Jackknife alternative free-response receiver-operating characteristic (JAFROC) analysis was performed. Results: Seventy-six pulmonary lesions were evaluated. Lesion-based detection rates were: CTex, 77.6%; VIBEin, 53.3%; VIBEex, 51.3%; and Dixon, 22.4%. Lobe-based detection rates were: CTex, 89.6%; VIBEin, 58.3%; VIBEex, 60.4%; and Dixon, 31.3%. In contrast to CT, inspiration versus expiration did not alter diagnostic performance in VIBE sequences. Diagnostic confidence was best for VIBEin and CTex and decreased in VIBEex and Dixon (1.2 ± 0.6; 1.2 ± 0.7; 1.5 ± 0.9; 1.7 ± 1.1, respectively). The JAFROC figure-of-merit of Dixon was significantly lower. All patients with malignant lesions were identified by CTex, VIBEin, and VIBEex, while 3 patients were false-negative in Dixon. Conclusion: Fast T1-weighted VIBE sequences allow for identification of patients with malignant pulmonary lesions. The Dixon sequence is not recommended for lung nodule evaluation in oncologic MR/PET patients. In contrast to CT, inspiration versus expiratory breath-hold in VIBE sequences was less crucial for lung nodule evaluation but was important for diagnostic confidence.