• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.1
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• pp.24-30
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• 2011

We have developed a hand-held probe for an ophthalmic OCT system. The hand-held probe for imaging was designed to be compact and portable. The cornea and retinal images were acquired by replacing the objective lens at the front of the probe. To verify the performance of the hand-held OCT probe, we acquired two dimensional OCT image of the rat eye in vivo and reconstructed three dimensional rat eye rendering images. In vivo 3D OCT images were showed distinct structural information in the posterior and anterior chamber with minimal motion artifacts. Thereby, OCT imaging speed is suitable for an dynamic in vivo experiment.

• Progress in Medical Physics
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• v.9 no.2
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• pp.95-104
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• 1998

The dynamic properties of the 3rd-order neuron of the retina was investigated by using conventional intracellular recording techniques. Experiments were performed in the superfused retina-eyecup preparation of the channel catfish, Ictalurus punctatus. The cornea, iris, lens, and vitreous were removed by absorption with Kimwipe tissue under the dissection microscope thereby exposing the retina in a hemi -eyecup. The electrical signal was amplified by electrometer, viewed on oscilloscope. Regular signals from the cells were recorded on a penwriter and stored by data recorder and computer. Full-field, spot or annular light stimuli were generated on a computer monitor and focused onto the retina. Baclofen hyperpolarized the dark membrane potential, suppressed sustained component and enhanced transient component of the ON-sustained cell with a large transient component, but did not affect the surround antagonism of the cell. Baclofen selectively suppressed responses evoked by moving bar light stimuli on the ON-OFF transient cell. The results suggest that transient cells have directional selectivity in the inner retina. These dynamic properties of amacrine and ganglion cells were modulated by baclofen. Therefore, it is presumed that there is baclofen-induced directional selectivity in ON-OFF transient cells in the catfish retina.

• Animal cells and systems
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• v.9 no.3
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• pp.139-144
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• 2005

The attractant (orange light) or repellent (white light) signal is transmitted from SRI (Sensory Rhodopsin I) via protein-protein interaction with its transducer Htrl (Halobacterial Transducer for Sensory Rhodopsin I) which in turn controls a cytoplasmic phospho-transfer pathway that modulates flagella motor switching in Halobacterium salinarum. Some mutations in both SRI and Htrl showed an unusual mutant phenotype called inverted signaling, in which the cell produces a repellent response to normally attractant light. Twelve mutations at the Glutamate 56 (E56) position in the second transmembrane helix of Htrl were introduced by site-specific random mutagenesis. Almost all E56 mutants showed orange-light inverted responses in pH and temperature-dependent manners except E56D and E56Y. Except for these two mutants, all mutants accelerated the $S_{373}$ decay compared to wild-type at $18^{\circ}C$. This supported that there is an interaction between SRI and the second transmembrane of Htrl. Also a structural model of Htrl based on the Tar crystal structure and the secondary structure prediction program proposed the E56 residue to be in the middle of the proton channel. The most important observation is that the E56 mutant provides the evidence that this residue is very sensitive for signal relay, which can be explained by the open and closed conformations of the channel (A and R conformations) in SRI, as was postulated by the unified conformational shuttling model for transport and signaling.

• Molecules and Cells
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• v.38 no.2
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• pp.105-111
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• 2015

The beta2-adrenergic receptor (${\beta}2AR$) belongs to the G protein coupled receptor (GPCR) family, which is the largest family of cell surface receptors in humans. Extra attention has been focused on the human GPCRs because they have been studied as important protein targets for pharmaceutical drug development. In fact, approximately 40% of marketed drugs directly work on GPCRs. GPCRs respond to various extracellular stimuli, such as sensory signals, neurotransmitters, chemokines, and hormones, to induce structural changes at the cytoplasmic surface, activating downstream signaling pathways, primarily through interactions with heterotrimeric G proteins or through G-protein independent pathways, such as arrestin. Most GPCRs, except for rhodhopsin, which contains covalently linked 11 cis-retinal, bind to diffusible ligands, having various conformational states between inactive and active structures. The first human GPCR structure was determined using an inverse agonist bound ${\beta}2AR$ in 2007 and since then, more than 20 distinct GPCR structures have been solved. However, most GPCR structures were solved as inactive forms, and an agonist bound fully active structure is still hard to obtain. In a structural point of view, ${\beta}2AR$ is relatively well studied since its fully active structure as a complex with G protein as well as several inactive structures are available. The structural comparison of inactive and active states gives an important clue in understanding the activation mechanism of ${\beta}2AR$. In this review, structural features of inactive and active states of ${\beta}2AR$, the interaction of ${\beta}2AR$ with heterotrimeric G protein, and the comparison with ${\beta}1AR$ will be discussed.

• Journal of Genetic Medicine
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• v.8 no.2
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• pp.125-129
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• 2011

Stickler syndrome is a very rare connective tissue disorder. The authors of the present study describe an 11-month-old girl with high myopia, retinal abnormalities, flat nose, cleft palate, retrognathia, micrognathia, short stature and arthrogryposis. Radiological evaluation also showed irregularity of the epiphysis of the femur and tibia and spondyloepiphyseal dysplasia. Genetic analysis using a peripheral blood sample revealed a novel variant c.787G>A (p.Gly246Asp) mutation of the COL2A1 gene. This is the first Korean case with Stickler syndrome confirmed by genetic testing.

• The Korean Journal of Physiology and Pharmacology
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• v.13 no.2
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• pp.91-97
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• 2009

The tubby mouse is characterized by progressive retinal and cochlear degeneration and late-onset obesity. These phenotypes are caused by a loss-of-function mutation in the tub gene and are shared with several human syndromes, suggesting the importance of tubby protein in central nervous system (CNS) functioning. Although evidence suggests that tubby may act as a transcription factor mediating G-protein coupled receptor (GPCR) signaling, any downstream gene regulated by tubby has yet to be identified. To explore potential target genes of tubby with region-specific transcription patterns in the brain, we performed a microarray analysis using the cerebral cortex and hypothalamus of tubby mice. We also validated the changes of gene expression level observed with the microarray analysis using real-time RT-PCR. We found that expression of erythroid differentiation factor 1 (Erdrl) and caspase 1 (Casp1) increased, while p21-activated kinase 1 (Pak1) and cholecystokinin 2 receptor (Cck2r) expression decreased in the cerebral cortex of tubby mice. In the hypothalamic region, Casp 1 was up-regulated and $\mu$-crystallin (CRYM) was down-regulated. Based on the reported functions of the differentially expressed genes, these individual or grouped genes may account for the phenotype of tubby mice. We discussed how altered expression of genes in tubby mice might be understood as the underlying mechanism behind tubby phenotypes.

• Childhood Kidney Diseases
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• v.23 no.2
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• pp.59-66
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• 2019

Background: Primary hyperoxaluria (PH), a rare inborn error of glyoxylate meta bolism causing overproduction of oxalate, is classified into three genetic subgroups: type 1-3 (PH1-PH3) caused by AGXT, GRHPR, and HOGA1 gene mutations, respectively. We performed a retrospective case series study of Korean pediatric patients with PH. Methods: In total, 11 unrelated pediatric patients were recruited and their phenotypes and genotypes were analyzed by a retrospective review of their medical records. Results: Mutational analyses revealed biallelic AGXT mutations (PH1) in nine patients and a single heterozygous GRHPR and HOGA1 mutation in one patient each. The c.33dupC was the most common AGXT mutation with an allelic frequency of 44%. The median age of onset was 3 months (range, 2 months-3 years), and eight patients with PH1 presented with end stage renal disease (ESRD). Patients with two truncating mutations showed an earlier age of onset and more frequent retinal involvement than patients with one truncating mutation. Among eight PH1 patients presenting with ESRD, five patients were treated with intensive dialysis followed by liver transplantation (n=5) with/without subsequent kidney transplantation (n=3). Conclusion: Most patients presented with severe infantile forms of PH. Patients with two truncating mutations displayed more severe phenotypes than those of patients with one truncating mutation. Sequential liver and kidney transplantation was adopted for PH1 patients presenting with ESRD. A larger nation-wide multicenter study is needed to confirm the genotype-phenotype correlations and outcomes of organ transplantation.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.28 no.1
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• pp.58-70
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• 2002

In an attempt to compare the antioxidation effects of constrain the oxidation and improve the structural stability, retinol and various antioxidants were together encapsulated by liposome. Four water soluble and four oil soluble antioxidants were tested for performance. The influence of tertiary butylhydroquinone(TBHQ), ${\alpha}$-glycosyl rutin(${\alpha}$-G rutin), licorece, pycnogenol as water soluble antioxidants and butylated hydroxytoluene(BHT), ${\alpha}$-lipoic acid, ferulic acid, natural concentrated tooopherol(no-tocopherol) as oil soluble antioxidants on the constraint of oxidation of retinol were investigated. Additional study was conducted to compare the synergic effect of antioxidation for retinol with licorice, pycnogenol, ${\alpha}$-lipoic acid and BHT. All the antioxidant used at the study constrained oxidation of retinol. The effect of antioxidation for retinol increased in order of licorice, pycnogenol, TBHQ, ${\alpha}$-G rutin as water soluble antioxidants and ${\alpha}$-lipoic acid, BHT, no-tocopherol, ferulic acid as oil soluble antioxidants. In conclusion, ${\alpha}$-lipoic acid is more effective retinol antioxidants than BHT. And the combination of ${\alpha}$-lipoic acid and BHT gave best synergic among six combinations.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.18 no.3
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• pp.95-98
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• 2018

A striking feature of mitochondrial disorders is the vast heterogeneity in their clinical symptoms that ranges from a single organ to severe multisystem involvement. Though a variety of ocular symptoms such as ptosis, pigmentary retinal degeneration, external ophthalmoplegia, and optic nerve atrophy can occur in association with mitochondrial cytopathies, progressive bilateral cataracts are rare among their ocular findings. A 5-year-old girl with no previous medical history came to our hospital presenting symptoms of seizure. She started showing progressive developmental regression, increased seizure frequency, hypotonia, general weakness, dysphagia and decreased vision. Lactic acidosis was noted in metabolic screening test and we confirmed mitochondrial respiratory chain complex I defect in spectrophotometric enzyme assay using the muscle tissue. Progressive bilateral cataracts then developed and were fully evident at the age of 7. She underwent cataract extraction with posterior chamber lens implantation. We are reporting a case of mitochondrial respiratory chain defect with multiorgan involvements including bilateral progressive cataract, an uncommon ocular manifestation. Ophthalmologic evaluation is highly recommended not to overlook the possible ocular manifestations in mitochondrial disorders.

• Parasites, Hosts and Diseases
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• v.57 no.2
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• pp.83-92
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• 2019

Based on the reactive oxygen species (ROS) regulatory properties of diphenyleneiodonium (DPI), we investigated the effects of DPI on host-infected T. gondii proliferation and determined specific concentration that inhibit the intracellular parasite growth but without severe toxic effect on human retinal pigment epithelial (ARPE-19) cells. As a result, it is observed that host superoxide, mitochondria superoxide and $H_2O_2$ levels can be increased by DPI, significantly, followed by suppression of T. gondii infection and proliferation. The involvement of ROS in anti-parasitic effect of DPI was confirmed by finding that DPI effect on T. gondii can be reversed by ROS scavengers, N-acetyl-L-cysteine and ascorbic acid. These results suggest that, in ARPE-19 cell, DPI can enhance host ROS generation to prevent T. gondii growth. Our study showed DPI is capable of suppressing T. gondii growth in host cells while minimizing the un-favorite side-effect to host cell. These results imply that DPI as a promising candidate material for novel drug development that can ameliorate toxoplasmosis based on ROS regulation.