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Bilateral Retinal Dysplasia and Secondary Glaucoma Associated with Homozygous Protein C Deficiency
( Un Chul Park ),( Ho Kyung Choung ),( Seong Joon Kim ),( Young Suk Yu ) 대한안과학회 2005 Korean Journal of Ophthalmology Vol.19 No.2
Purpose: Protein C deficiency is an autosomal recessive disorder, which predisposes the patient to potentially blinding and widespread lethal thromboembolic complications, especially in the homozygous type. We here report the first Korean case of ophthalmic involvement and its surgical treatment in homozygous protein C deficiency. Methods: A 3.4kg, full term girl was born by normal delivery but showed bilateral leukocoria on day 2. Laboratory results disclosed a very low protein C activity level (10%) in the patient and moderately decreased levels in the other family members. Ophthalmic examination showed bilateral corneal opacity and shallow anterior chamber. B-scan ultrasonography which showed intravitreal mass lesions without microphthalmos and a funnel-shaped retinal detachment suggested bilateral retinal dysplasia. Results: As the eyes were under progression of secondary glaucoma, bilateral lensectomies were performed at 2 months old and corneal opacity was regressed to some degree. However, at 14 months old, the left eye showed moderate corneal opacity with a band keratopathy. Conclusions: Although visual outcome was very poor after surgery, we could impede or slow down the progression of secondary glaucoma and save the eyeballs in the infant with homozygous protein C deficiency.
Adaptive logic circuits with doping-free ambipolar carbon nanotube transistors.
Yu, Woo Jong,Kim, Un Jeong,Kang, Bo Ram,Lee, Il Ha,Lee, Eun-Hong,Lee, Young Hee American Chemical Society 2009 Nano letters Vol.9 No.4
<P>A CMOS-like inverter was integrated by using ambipolar carbon nanotube (CNT) transistors without doping. The ambipolar CNT transistors automatically configure themselves to play a role as an n-type or p-type transistor in a logic circuit depending on the supply voltage (V(DD)) and ground. A NOR (NAND) gate is adaptively converted to a NAND (NOR) gate. This adaptiveness of logic gates exhibiting two logic gate functions in a single logic circuit offers a new opportunity for designing logic circuits with high integration density for next generation applications.</P>
Yu, Changho,Kang, Seung Rok,Yang, Giltae,Hong, Chul Un,Lee, Hyung Jong,Oh, Do Young,Kwon, Tae Kyu Pergamon Press 2015 Bio-medical materials and engineering Vol.26 No.1
<P>This study investigated the feasibility of the Infrared (IR) sensor-based walking aids for detecting the gait intention. To compensate for the defects of Force Sensing Resistors (FSRs) or force sensors, such as the velocity control problem on gait slopes, we used IR sensors to investigate knee joint anterior displacement in order to recognize the gait intention. We also measure leg muscle activities and foot pressure, in order to verify our investigation. We placed two IR sensors on the rollator center to sense left and right leg walking intentions. We took EMG signals of four leg muscles, and analyzed them. Foot pressure analysis parameters were the measured force and mean pressure. We conducted experiments on twenty young healthy adults. The results show that knee joint anterior displacement increases according to gait slope and velocity. We confirm similar results of knee joint anterior displacement through the IR sensors.</P>
Yu, Ji Hoon,Kang, Sin-Gun,Jung, Un-Young,Jun, Chul-Ho,Kim, Hyeyoung Wiley (Blackwell Publishing) 2009 Annals of the New York Academy of Sciences Vol.1171 No.1
<P>Oxidative stress plays a critical role in apoptosis of gastric epithelial cells. Omega-3 fatty acids show anti-inflammatory and/or anticancer effects and regulate apoptosis in various cells. In this study, we aimed to investigate whether omega-3 fatty acids inhibit oxidative stress-induced apoptosis of gastric epithelial cells. The cells received oxidative stress caused by silica-immobilized glucose oxidase acting on beta-D-glucose and cultured in the absence or presence of alpha-linolenic acid or docosahexanoic acid. Viable cell numbers, levels of H(2)O(2) in the medium, DNA fragmentation, and protein levels of p53 and Bax were determined. As a result, silica-immobilized glucose oxidase acting on beta-D-glucose consistently and reproducibly produced H(2)O(2), which decreased cell viability and increased DNA fragmentation of the cells. Omega-3 fatty acids inhibited oxidative stress-induced cell death, DNA fragmentation, and induction of p53 and Bax of the cells. The silica-immobilized glucose oxidase could be a useful tool for studies on oxidative stress-induced cellular events because it is reusable and forms a stable enzyme system acting on glucose. Omega-3 fatty acids may be beneficial for preventing oxidative stress-induced apoptosis by inhibiting apoptotic gene expression and DNA fragmentation of gastric epithelial cells.</P>
Yu, Un Young,Yoo, Byong Chul,Ahn, Jung-Hyuck The Korean Society of Pharmacology 2014 The Korean Journal of Physiology & Pharmacology Vol.18 No.2
Overexpression of amyloid precursor protein with the Swedish mutation causes abnormal hyperphosphorylation of the microtubule-associated protein tau. Hyperphosphorylated isoforms of tau are major components of neurofibrillary tangles, which are histopathological hallmarks of Alzheimer's disease. Protein phosphatase 2A (PP2A), a major tau protein phosphatase, consists of a structural A subunit, catalytic C subunit, and a variety of regulatory B subunits. The B subunits have been reported to modulate function of the PP2A holoenzyme by regulating substrate binding, enzyme activity, and subcellular localization. In the current study, we characterized regulatory B subunit-specific regulation of tau protein phosphorylation. We showed that the PP2A B subunit PPP2R2A mediated dephosphorylation of tau protein at Ser-199, Ser-202/Thr-205, Thr-231, Ser-262, and Ser-422. Down-regulation of PPP2R5D expression decreased tau phosphorylation at Ser-202/Thr-205, Thr-231, and Ser-422, which indicates activation of the tau kinase glycogen synthase kinase 3 beta ($GSK3{\beta}$) by PP2A with PPP2R5D subunit. The level of activating phosphorylation of the $GSK3{\beta}$ kinase Akt at Thr-308 and Ser-473 were both increased by PPP2R5D knockdown. We also characterized B subunit-specific phosphorylation sites in tau using mass spectrometric analysis. Liquid chromatography-mass spectrometry revealed that the phosphorylation status of the tau protein may be affected by PP2A, depending on the specific B subunits. These studies further our understanding of the function of various B subunits in mediating site-specific regulation of tau protein phosphorylation.
( Un Young Yu ),( Jung Hyuck Ahn ) 생화학분자생물학회 2010 BMB Reports Vol.43 No.4
To characterize the biochemical properties of the PP2A regulatory B subunit, PPP2R5D, we analyzed its phosphorylation sites, stoichiometry and effect on holoenzyme activity. PPP2R5D was phosphorylated on Ser-53, Ser-68, Ser-81, and Ser-566 by protein kinase A, and mutations at all four of these sites abolished any significant phosphorylation in vitro. In HEK293 cells, however, the Ser-566 was the major phosphorylation site after PKA activation by forskolin, with marginal phosphorylation on Ser-81. Inhibitory tyrosine phosphorylation on Tyr-307 of the PP2A catalytic C subunit was decreased after forskolin treatment. Kinetic analysis showed that overall PP2A activity was increased with phosphorylation by PPP2R5D phosphorylation. The apparent Km was reduced from 11.25 μM to 1.175 μM with PPP2R5D phosphorylation, resulting in an increase in catalytic activity. These data suggest that PKA-mediated activation of PP2A is enabled by PPP2R5D phosphorylation, which modulates the affinity of the PP2A holoenzyme to its physiological substrates. [BMB reports 2010; 43(4): 263-267]
Un Young Yu,Byong Chul Yoo,Jung-Hyuck Ahn 대한생리학회-대한약리학회 2014 The Korean Journal of Physiology & Pharmacology Vol.18 No.2
Overexpression of amyloid precursor protein with the Swedish mutation causes abnormal hyperphos-phorylation of the microtubule-associated protein tau. Hyperphosphorylated isoforms of tau are major components of neurofibrillary tangles, which are histopathological hallmarks of Alzheimer’s disease. Protein phosphatase 2A (PP2A), a major tau protein phosphatase, consists of a structural A subunit, catalytic C subunit, and a variety of regulatory B subunits. The B subunits have been reported to modulate function of the PP2A holoenzyme by regulating substrate binding, enzyme activity, and subcellular localization. In the current study, we characterized regulatory B subunit-specific regulation of tau protein phosphorylation. We showed that the PP2A B subunit PPP2R2A mediated dephosphory-lation of tau protein at Ser-199, Ser-202/Thr-205, Thr-231, Ser-262, and Ser-422. Down-regulation of PPP2R5D expression decreased tau phosphorylation at Ser-202/Thr-205, Thr-231, and Ser-422, which indicates activation of the tau kinase glycogen synthase kinase 3 beta (GSK3<em>β</em>) by PP2A with PPP2R5D subunit. The level of activating phosphorylation of the GSK3<em>β</em> kinase Akt at Thr-308 and Ser-473 were both increased by PPP2R5D knockdown. We also characterized B subunit-specific phos-phorylation sites in tau using mass spectrometric analysis. Liquid chromatography-mass spectrometry revealed that the phosphorylation status of the tau protein may be affected by PP2A, depending on the specific B subunits. These studies further our understanding of the function of various B subunits in mediating site-specific regulation of tau protein phosphorylation.