• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.6
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• pp.581-589
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• 2004

In this study, the capacitive micromachined ultrasonic transducer(cMUT) was developed based on the previous research results. The cross sectional image of the developed cMUT was characterized. To measure the membrane displacement of the cMUT, the Michelson phase modulation fiber interferometer was constructed. The measured membrane displacement was in good agreement with the result of the finite element analysis. To estimate the ultrasonic wave generated by the cMUT, an ultrasonic system including a pulser, receiver and charge amplifier was used. The cMUT developed in this study shows a good performance and hence will be widely used in the non-contact ultrasonic applications.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.14 no.2
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• pp.174-177
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• 2014

Isolated methylmalonic acidemia (MMA) is a group of autosomal recessive inborn errors of metabolism caused by impaired activity of methylmalonyl-coenzyme A mutase (MCM). Mutations in the gene encoding MCM (MUT ) is the most common cause of isolated MMA. In this report, we identify an asymptomatic 15 days old female who had elevated C3-acylcarnitine (C3) in the newborn screening. Her serum homocysteine was normal and urine methylmalonic acid was increased that suggested isolated MMA. She was maintained on a low-protein diet and carnitine supplementation. At 3 months of age, she was still asymptomatic and had normal growth. We analyzed MUT gene mutations. Two heterozygote mutations in the MUT gene were identified including c.323G>A and c.1672+2T>C (IVS8(+2)T>C. Among these, c.1672+2T>C (IVS8(+2)T>C) have not been described previously.

• 한국전산유체공학회:학술대회논문집
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• 2008.08a
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• pp.32.2-32.2
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• 2008

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.5
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• pp.487-493
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• 2004

This study was conducted to develope a capacitive micromachined ultrasonic transducer (cMUT) which enable to high efficient non-contact transmit and receive the ultrasonic wave in air. Theoretical analysis and finite element analysis of the behavior of membrane (such as resonance frequency, membrane deflection, collapse deflection and collapse voltage) of the cMUT were performed. The design parameters of the cMUT such as the dimension and thickness of membrane, thickness of sacrificial layer, thickness and size of electrode were estimated. The resonance frequency of the membrane increased as the thickness of the membrane increased but decreased as the diameter of the membrane increased. The deflection of the membrane increased as d-c bias voltage increased. The collapse voltage of the membrane was analyzed.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.6
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• pp.573-580
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• 2004

The main goal of this study was to develop a micro-fabrication process for the capacitive micromachined ultrasonic transducer (cMUT). In order to achieve this goal, the former research results of the micro-electro-mechanical system (MEMS) process for the cMUT were analyzed. The membrane deposition, sacrificial layer deposition and etching were found to be a main process of fabricating the cMUT. The optimal conditions for those microfabrication were determined by the experiment. The thickness, uniformity, and residual stress of the $Si_3N_3$ deposition which forms the membrane of the cMUT were characterized after growing the $Si_3N_3$ on Si-wafer under various process conditions. As a sacrificial layer, the growth rate of the $SiO_2$ deposition was analyzed under several process conditions. The optimal etching conditions of the sacrificial layer were analyzed. The microfabrication process developed in this study will be used to fabricate the cMUT.

• BMB Reports
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• v.40 no.6
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• pp.1021-1027
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• 2007

We demonstrated the genetic polymorphism of aldehyde oxidase (AO) in Donryu strain rats: the ultrarapid metabolizer (UM) with nucleotide mutation of (377G, 2604C) coding for amino acid substitution of (110Gly, 852Val), extensive metabolizer (EM) with (377G/A, 2604C/T) coding for (110Gly/Ser, 852Val/Ala), and poor metabolizer (PM) with (377A, 2604T) coding for (110Ser, 852Ala), respectively. The results suggested that 377G > A and/or 2604C > T should be responsible for the genetic polymorphism. In this study, we constructed an E. coli expression system of four types of AO cDNA including Mut-1 with (377G, 2604T) and Mut-2 with (377A, 2604C) as well as naturally existing nucleotide sequences of UM and PM in order to clarify which one is responsible for the polymorphism. Mut-1 and Mut-2 showed almost the same high and low activity as that of the UM and PM groups, respectively. Thus, the expression study of mutant AO cDNA directly revealed that the nucleotide substitution of 377G > A, but not that of 2604C > T, will play a critical role in the genetic polymorphism of AO in Donryu strain rats. The reason amino acid substitution will cause genetic polymorphism in AO activity was discussed.

• The Korean Journal of Food And Nutrition
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• v.7 no.1
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• pp.51-57
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• 1994

A nuluk, a Korean traditional koji for brewing, was made with wheat flour and Aspergillus usamii mot. shirousamii S1 which had strong abilities in producing amylase and protease. The cultural conditions for the production of saccharogenic and proteolytic enzymes were tested. The productivities of saccharogenic and dextrogenic enzymes were improved when nuluk was made with unsteamed wheat flour as compared with steamed one, but those of proteolytic enzyme and organic acid were reduced. The addition of water containing 0.5% of hydrochloric acid was unfavorable for the production of saccharogenic, dextrogenic and proteolytic enzymes. The optimum ratios of water added to wheat flour for the production of saccharogenic enzyme and proteolytic enzyme were 32% and 28%, respectively on the basis of wheat flour. The optimum temperatures for the production of saccharogenic enzyme and proteolytic enzyme were 36$^{\circ}C$ and 28$^{\circ}C$, respectively. The activity of saccharogenic enzyme reached its maximum after 120 hours of cultivation at 36$^{\circ}C$, but that of proteolytic enzyme 96 hours. The productivity of saccharogenic enzyme was enhanced when the nuluk was molded after 24 hours of precultivation but that of proteolytic enzyme was reduced as compared with no molding.

• Animal cells and systems
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• v.1 no.3
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• pp.451-455
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• 1997

The effects of nalidixic acid, mitomycin C, and cadmium chloride $(CdCI_2)$ on the activity of 8-hydroxyguanine $(oh^8Gua)$ endonuclease, a DNA repair enzyme for oxidatively modified guanine, $(oh^8Gua$ were studied. Nalidixic acid and mitomycin C, typical inducers of the S0S DNA repair response in E. coli, showed different effects. Nalidixic acid raised the activity of this enzyme, but mitomycin C did not show such an effect. Cadmium chloride also induced the enzyme activity, These results show that the expression of $oh^8$ Gua endonuclease is regulated by multiple factors and can be induced under stressful conditions. In an attempt to demonstrate the importance of this enzyme in defense against DNA damage and mutagenesis, we also characterized mutM mutant for its oh8 Gua endonuclease activity. The mutM mutant showed no detectable $oh^8$ Gua endonuclease activity, unlike its wild type showing high activity. In addition, paraquat, a superoxide producing compound, failed to elevate $oh^8Gua$ endonuclease activity in this mutant. These results suggest that the mutM gene is identical to the $oh^8Gua$ endonuclease gene of E. coli. Taken together with previous reports, these results suggest that $oh^8Gua$ endonuclease plays a crucial role in the protection of aerobically growing organisms from threats of oxidative DNA damage and mutation.

• Journal of Genetic Medicine
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• v.14 no.2
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• pp.80-85
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• 2017

Methylmalonic acidemia (MMA) is an autosomal recessive metabolic disorder characterized by an abnormal accumulation of methylmalonyl-CoA and methylmalonate in body fluids without hyperhomocysteinemia. Cardiac disease is a rarely known lethal complication of MMA, herein, we report a Korean neonate diagnosed with MMA on the basis of biochemical and genetic findings, who developed cardiomyopathy, resulting in sudden death. The patient presented vomiting and lethargy at 3 days of age. Initially, the patient had an increased plasma propionylcarnitine/acetylcarnitine concentration ratio of 0.49 in a tandem mass spectrometry analysis and an elevated ammonia level of $537{\mu}mol/L$. Urine organic acid analysis showed increased excretion of methylmalonate. Subsequent sequence analysis of the methylmalonyl-CoA mutase (MUT) gene revealed compound heterozygous mutations c.323G>A (p.Arg108His) in exon 1 and c.1033_1034del (p. Leu345Serfs*15) in exon 4, the latter being a novel mutation. In summary, this is the first case of MMA and cardiomyopathy in Korea that was confirmed by genetic analysis to involve a novel MUT mutation.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.19 no.1
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• pp.12-19
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• 2019

Purpose: Isolated methylmalonic acidemia (MMA) is an autosomal recessive inherited disorder of propionate metabolism. There are two subtypes of MMUT gene defects. $Mut^0$ represents complete loss of methylmalonyl-CoA mutase (MCM) activity while mut- is associated with residual MCM activity, which can be stimulated by hydroxocobalamin (OHCbl) supplementation. The objective of this study is to investigate cobalamin responsiveness and mutations present in Korean MMA population. Methods: We evaluated 10 MMA patients using somatic cell complementation analysis on their fibroblasts to measure MCM activity and vitamin B12 responsiveness for the optimal treatment. MMUT gene was sequenced to identify the MMA mutations. Results: For all patients, the incorporation of $[^{14}C]-propionate$ was low, and there was no response to OHCbl. The incorporation of $[^{14}C]-methyltetrahydrofolate$ and $[^{57}Co]-CNCbl$ fell within the normal range. There was adequate synthesis of methylcobalamin while the synthesis of adenosylcobalamin was low. The complementation analysis showed all patients were $mut^0$. The sequence analysis identified 12 different MMUT mutations, including 2 novel mutations, p.Gln267Ter and p.Ile697Phe, were identified. All the patients in this study had neonatal onset of symptoms, belonged to $mut^0$ complementation class, and as a result, showed no cobalamin responsiveness. Conclusion: No Korean MMA patient showed cobalamin responsiveness.