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다량의 골양물질을 형성한 중심성 거대세포육아종의 영상진단
이설미,허민석,이삼선,최순철,박태원 대한구강악안면방사선학회 2000 Imaging Science in Dentistry Vol.30 No.2
A 19-year-old man was referred to Seoul National University Dental Hospital for evaluation of a large painless swelling of the left mandibular angle area in August, 1999. The growth had been first noted 6 years ago. He had visited other hospital in 1997. In spite of the treatment given at the hospital, the mass continued to grow rapidly. Conventional radiographs in 1999 showed an expansile, lobulated, and destructive lesion of the left mandibular body. CT scan demonstrated an expansile mass with a corticated margin. Bony septa were seen within the lesion. Internal calcification noted on the bone-setting CT image, and corresponded to the hypointense area in T1-weighted MRI image. MRI clearly delineated the extent of the lesion which had heterogenous intermediate signal intensity in T1-weighted images and heterogenous hyperintense signal intensity in T2-weighted images. The lesion was well-enhanced. Histopathologically, the lesion was well demarcated. Multinucleated giant cells were presented in a fibrous background, demonstrating a storiform pattern. Areas of osteoid rimmed by a few osteoblasts were scattered throughout the lesion. Inflammatory cells, blood vessels, and hemosiderin deposition were also shown. CGCG may show lots of internal calcification foci on the CT, and varied signal intensity in MRI. More cases will be needed to understand the features of the CT & MR fonding of CGCG. (Korean J Oral Maxillofac Radiol 2000 ; 30 : 127-131)
Sol-lim Choi,Hyun-Sung Kim,Jae-Hwan Choi,Eun Hye Oh 대한평형의학회 2022 Research in Vestibular Science Vol.21 No.4
Objectives: This study aimed to investigate clinical significance of a head-bending test in benign paroxysmal positional vertigo (BPPV) involving the posterior semi-circular canal (PC-BPPV). Methods: We retrospectively recruited 256 patients with unilateral PC-BPPV between January 2016 and December 2021, and assessed the clinical characteri-stics of patients showing head-bending nystagmus (HBN). Results: Of 256 patients, 138 (53.9%) showed HBN. Most patients (n=136, 98.6%) had downbeat nystagmus with (n=38) or without (n=98) torsional component. The remaining two patients had pure upbeat and torsional nystagmus, respectively. The torsional component was directed to the contralesional side in all. Between patients with and without HBN, there were no significant differences in clinical characteristics such as age, lateralization, types of BPPV (canalolithiasis or cupulo-lithiasis), and success rate of repositioning maneuver. Conclusions: Head-bending test may be useful in predicting the diagnosis and lateralization of PC-BPPV.
Neural stem cells differentiated from iPS cells spontaneously regain pluripotency.
Choi, Hyun Woo,Kim, Jong Soo,Choi, Sol,Hong, Yean Ju,Kim, Min Jung,Seo, Han Geuk,Do, Jeong Tae AlphaMed Press 2014 Stem Cells Vol.32 No.10
<P>Differentiated somatic cells can be reprogrammed into pluripotent stem cells by transduction of exogenous reprogramming factors. After induced pluripotent stem (iPS) cells are established, exogenous genes are silenced. In the pluripotent state, retroviral genes integrated in the host genome are kept inactive through epigenetic transcriptional regulation. In this study, we tried to determine whether exogenous genes remain silenced or are reactivated upon loss of pluripotency or on differentiation using an in vitro system. We induced differentiation of iPS cells into neural stem cells (NSCs) in vitro; the NSCs appeared morphologically indistinguishable from brain-derived NSCs and stained positive for the NSC markers Nestin and Sox2. These iPS cell-derived NSCs (iPS-NSCs) were also capable of differentiating into all three neural subtypes. Interestingly, iPS-NSCs spontaneously formed aggregates on long-term culture and showed reactivation of the Oct4-GFP marker, which was followed by the formation of embryonic stem cell-like colonies. The spontaneously reverted green fluorescent protein (GFP)-positive (iPS-NSC-GFP(+) ) cells expressed high levels of pluripotency markers (Oct4 and Nanog) and formed germline chimeras, indicating that iPS-NSC-GFP(+) cells had the same pluripotency as the original iPS cells. The reactivation of silenced exogenous genes was tightly correlated with the downregulation of DNA methyltransferases (Dnmts) during differentiation of iPS cells. This phenomenon was not observed in doxycycline-inducible iPS cells, where the reactivation of exogenous genes could be induced only by doxycycline treatment. These results indicate that pluripotency can be regained through reactivation of exogenous genes, which is associated with dynamic change of Dnmt levels during differentiation of iPS cells.</P>