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Seongjin Jeon,Ji-Yun Park,Jong-min Lee,Seulgi Hong 대한평형의학회 2022 Research in Vestibular Science Vol.21 No.2
We report a unique case of vertebrobasilar transient ischemic attacks manifesting as isolated, recurrent, orthostatic dizziness with posterior inferior cerebellar artery (PICA) stenosis. A 57-year-old male patient without past medical history, pre-sented with brief orthostatic dizziness for 2 weeks. There was no associated nausea, vomiting, diplopia, or weakness. On neuro-otologic examination, the pa-tient did not show spontaneous, positional, or gaze-evoked nystagmus. Vestibular function tests such as caloric test, head impulse test, video-oculography, and tilt table test were normal. Brain diffusion-weighted images showed multiple small high signal intensities in the bilateral cerebellar hemispheres. Brain magnetic re-sonance angiography revealed hypoplasia of the right vertebral artery without fo-cal intracranial focal stenosis. Four-vessel cerebral angiogram showed severe stenosis at the right PICA artery. Our patient’s clinical scenario appears unique hemo-dynamic spells without symptoms or signs of posterior circulation ischemia. Phy-sicians should also consider cerebrovascular ischemic when the patient suffers repeated orthostatic dizziness that is not explained clinically.
Jeon, Seungyeon,Hong, Seongjin,Kwon, Bong-Oh,Park, Jinsoon,Song, Sung Joon,Giesy, John P.,Khim, Jong Seong Pergamon Press 2017 Chemosphere Vol.168 No.-
<P><B>Abstract</B></P> <P>The west coast of Korea has experienced environmental deterioration for more than half a century. In the present study, we specifically aimed to: i) evaluate potential toxicities of contaminants in sediments that cause effects mediated through the aryl hydrocarbon receptor (AhR) and estrogen receptor (ER); ii) determine spatio-temporal distributions of polycyclic aromatic hydrocarbons (PAHs) and alkylphenols (APs); and iii) identify causes of greater potencies of samples. From 2010 to 2014, sediments were collected from 12 major estuarine and coastal regions along the west coast of South Korea. <I>In vitro</I> cell bioassays were performed to determine AhR- and ER-mediated potencies using H4IIE-<I>luc</I> and MVLN cells, respectively. Fifteen PAHs and six APs in sediments were identified by GC/MSD. Results of bioassays generally showed a low-to-moderate degree of contamination, however, greater AhR- and ER-mediated potencies were measured at some locations. Concentrations of PAHs and APs varied among locations, which indicated that sources were independently affected by the surrounding environment (e.g., industrial complex and cities). Results of bioassays were generally well correlated with concentrations of putative causative chemicals. Benzo[<I>k</I>]fluoranthene, dibenz[<I>a</I>,<I>h</I>]anthracene, and benzo[<I>b</I>]fluoranthene were the major AhR agonists, explaining approximately 30% of the bioassay-derived benzo[<I>a</I>]pyrene equivalent concentration (BaP-EQ). Unknown AhR and ER agonists and potential mixture effects remain in question. Overall, the present study provides baseline information on chemical contaminations and potential toxicity of sediments in a fairly wide geographical region of the west coast of South Korea.</P> <P><B>Highlights</B></P> <P> <UL> <LI> AhR and ER potencies in sediments from the west coast of Korea were characterized. </LI> <LI> Bioassay results generally showed a low-to-moderate contamination of sediments. </LI> <LI> Distributions of PAHs and APs were generally affected by human activities. </LI> <LI> Five- and six-ring PAHs were the major AhR-active compounds in sediments. </LI> <LI> Known and unknown aromatics with log K<SUB>ow</SUB> 5–8 are likely major AhR agonists. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Influence of Refractive Indices of Glass Matrix on the Reflectance of Glass Composites
Jaeseung Jeon,Jungki Lee,Seongjin Hwang,Jihwan Ahn,Hyungsun Kim 대한금속·재료학회 2011 METALS AND MATERIALS International Vol.17 No.4
To understand the optical behavior of glass matrix composites, the species of glass matrix and ceramic filler,the mixing ratio, the refractive index of the components and the interaction between the matrix and the filler should be considered simultaneously. Two kinds of glass matrix with different refractive index (n = 1.50 and 1.69) and absorption coefficient were mixed with calcite (n = 1.59) in various volume percentages and their optical behavior, such as reflectance and scattering coefficient was studied after firing. The reflectance and the scattering coefficient increased with increasing calcite content regardless of the optical characteristics of the glass matrix. The reflectance of the composite was strongly correlated with the absorption coefficient of the glass matrix while the scattering coefficient of the composite was highly dependent on the refractive index of the glass matrix. We suggest that using the matrix with a higher refractive index than that of the filler may improve the reflectance of the glass composite.