Effect of dihydroxyphenylalanine on Cu²+ -induced inactivation of HDL-associated paraoxonase1 and oxidation of HDL; inactivation of paraoxonasel activity independent of HDL lipid oxidation

Sok Dai-Eun,Park cheon Ho,Kim Ju Ryoung,Nguyen Duy Su 대한약학회 2004 大韓藥學會 總會 및 學術大會 Vol.2004 No.1

Protective Action of N-terminal Sequence (DAHK)of Human Serum Albumin Against Lipoprotein Oxidation

Nguyen, Duy Su,Kim, Ju Ryoung,Wei, Chun Hua,Jeong, Tae-Sook,Sok, Dai-Eun 충남대학교 약학대학 의약품개발연구소 2005 藥學論文集 Vol.20 No.-

N-terminal four amino acid peptide of human serum albumin (DANK) is observed to exhibit antioxidant activity against various oxygen reactive species and to inhibit LDL oxidation. This antioxidant action was largely ascribed to its Cu^(2+)-binding property. However, relatively little is known of its effect on lipoprotein oxidation. In the present study, we investigated whether DAHK exerts protective effect on both LDL and HDL oxidation and attempted to elucidate the mechanism underlying antioxidant activity of DHAK. Our results show that DAHK exhibits a remarkable protection against LDL oxidation induced by Cu^(2+). The concentration required to effectively prevent LDL oxidation is equivalent to that of Cu^(2+), further emphasizing Cu^(2+)chelation of DHAK. It was also observed that DAHK protected AAPH-induced LDL oxidation, suggesting that the protective action of DARK is likely related to scavenging activity in addition to Cu^(2+) sequestration. Consistent with results observed with LDL oxidation, DARK demonstrated a significant prevention against Cu^(2+)-induced HDL oxidation, although to lower extent. It is noteworthy that DAHK was found to exhibit a remarkable protection against PON1 inactivation by various reactive oxygen species-generating systems, underscoring the importance of its antioxidant activity. In support of its antioxidant potential, DARK was also observed to effectively prevent the HOCI-induced modification of Apolipoprotein A-I as evidenced by restoration of fluorescence. Taken together, our data indicate that DARK is highly effective in protecting lipoprotein oxidation and this protective effect results from both its Cu^(2+) chelation and scavenging activity.

Broad-spectrum antioxidant peptides derived from His residue-containing sequences present in human paraoxonase 1

Nguyen, Su Duy,Jeong, Tae-Sook,Kim, Mee Ree,Sok, Dai-Eun Taylor Francis 2006 Free radical research Vol.40 No.4

<P>Hydroxyl or peroxyl radicals and hypochlorous acid (HOCl) are known to cause the oxidation of lipoproteins. Here, we examined Cu 2+ -binding property of paraoxonase 1 (PON1), and antioxidant actions of peptides, resembling His residue-containing sequences in PON1, against oxidations by Cu 2+ , peroxyl radicals or HOCl. When Cu 2+ -binding property of PON1 was examined spectrophotometrically, the maximal Cu 2+ binding was achieved at 1:1 molar ratio of PON1: Cu 2+ . Additionally, Cu 2+ -catalyzed oxidative inactivation of PON1 was prevented by Ca 2+ -depleted PON1 at 1:1 ratio, but not diethylpyrocarbonate (DEPC)-modified PON1, suggesting the participation of His residue in Cu 2+ -binding. When His-containing peptides were examined for antioxidant actions, those with either His residue at N-terminal position 2 or 3, or His–Pro sequence at C-terminal remarkably prevented Cu 2+ -mediated low density lipoprotein (LDL) oxidation and PON1 inactivation. Especially, FHKALY, FHKY or NHP efficiently prevented Cu 2+ -induced LDL oxidation (24 h), indicating a tight binding of Cu 2+ by peptides. In support of this, the peptide/Cu 2+ complexes exhibited a superoxide-scavenging activity. Separately, in oxidations by 2,2'-azobis-2-amidinopropane hydrochloride or HOCl, the presence of Tyrosine (Tyr) or Cysteine (Cys) residue markedly enhanced antioxidant action of His-containing peptides. These results indicate that His-containing peptides with Tys or Cys residues correspond to broad spectrum antioxidants in oxidation models employing Cu 2+ , 2,2'-azobis-2-amidinopropane hydrochloride (AAPH) or HOCl.</P>

Existence of the Cysteine Residue in a Region Close to Active Center of Human Paraoxonase1

Su, Nguyen Duy,Sok, Dai-Eun 충남대학교 약학대학 의약품개발연구소 2004 藥學論文集 Vol.19 No.-

Paraoxonase1 (PON1), one of antioxidant proteins, is known to protect low density lipoprotein (LDL) from the oxidation. Despite no participation of cysteine residue in the catalysis of PON1, some part of its antioxidant action is accounted for by the sulhydryl group of the cysteine residue. Here, we attempted to elucidate the location of cystein residue in the active site. For this purpose, PON1 was exposed to various mercury compounds, which can mod& the cysteine residue, and the remaining activity was determined based on the hydrolysis of phenyl acetate. Of various mercury compounds, the inactivating potency was dependent on the size of mercury compounds; mercuric chloride>mercurochrome>mercury orange>p-hydroxymercuribenzoate. In order to confirm the modification of cysteine residue, each mercury compound-modified PON1 was exposed to excess DTT, and the restored activity was determined. Noteworthy, the the DTT reduction successfully restored the loss of PON1 activity, which was caused by the mercury compounds except p-hydroxymercuribenzoate, negatively-charged. This suggests that there may be a difference in the microenviroment of the active site among the mercury compound-modified PON1 molecules, consistent with the notion that the active site of PON1 molecule may contain the non-polar background. Probably in support of this, oleic acid, a protective fatty acid, effectively prevented against the inactivation of PON1 by p-hydroxymercuribenzoate, but not the other mercury compounds. Thus, the orientation of mercury compound-modified cysteine residue in the active site of PON1 could differ remarkably according to the type of mercury compound. Based on these results, it is suggested that the cysteines residue in the active site of PON1 may be oriented to be affected by extraneous factors.

Key Determinants for Users Intention to Use Smarthome Devices in Vietnam

Nguyen, Thi-Hong-Linh,Duong, Minh-Hung,Nguyen, Hai-Dang,Vo, Dang-HongNgan,Vu, Duy-Phuong-Trinh,Le, Hoanh-Su Korea Multimedia Society 2018 The journal of multimedia information system Vol.5 No.4

Smarthome is one of the remarkable fields of the industrial revolution 4.0, which are popular in many countries such USA, EURO, Japan and Korea. However, how Vietnamese people are considering and having intension to use smarthome devices is still a question for marketers and researchers. This study develops a comprehensive research model that can explain potential customers' behavioral intentions to adopt and use Smarthome services in Viet Nam and figure which key factors affect the intention. This study proposes and validates a new theoretical model that extends the Unified Theory of Acceptance and Use of Technology 2 (UTAUT2). The model consists of eight factors that affect one element (Behavioral Intention), specifically: Habits, Perceived usefulness, Perceived ease of use, Trust, Innovativeness Personal, Perceived value, Hedonic motivations and Social influences. Data were collected from 304 Vietnamese citizens by sending the email to survey questionnaire, direct contact with the experienced smarthome users. Through regression analysis, data from samples were analysed with SPSS 20 software and verification of hypotheses, the results show the key determinants affecting the intention to use smarthome appliances in Vietnam: Perceived Value, Social Influence, Perceived Usefulness, Perceived Ease of Use and Trust. From this result, several recommendations have been suggested to to smarthome devices vendors and marketer to improve products as well as marketing approaches to meet customer needs.

The Factors Affecting Intention to Use Smarthome Devices in Vietnam

Nguyen Thi-Hong-Linh,Duong Minh-Hung,Nguyen Hai-Dang,Vo Dang-HongNgan,Vu Duy-Phuong-Trinh,Le Hoanh-Su 한국경영정보학회 2018 한국경영정보학회 학술대회논문집 Vol.2018 No.5

인체 혈장 Paraoxonase의 산화적 불활성화

위엥쥐스,김주령,정태숙,류희문,석대은 충남대학교 약학대학 의약품개발연구소 2002 藥學論文集 Vol.17 No.-

Paraoxonase (PON), an enzyme associated with high density lipoprotein (HDL), is known to protect low density lipoprotein (LDL) from lipid peroxidation involving copper ion. However, PON activity was observed to decrease during LDL oxidation. Here, we attempted to elucidate the possible mechanism for the inactivation of PON. PON was partially purified from human plasma, and subjected to various oxidant systems. PON activity, based on the hydrolysis of phenyl acetate, decreased slightly after the exposure to H_2O_2 or ascorbate, while oxidants such as peroxynitrite or HOCl had no remarkable effect. Inclusion of Cu^2+ in the incubation with ascorbate (0.3∼1 mM) led to a rapid decrease of activity in a time-and concentration-dependent manner. In comparison, ascorbate/Cu^2+ system was much more effective than ascorbate/Fe^2+ system in inactivating PON. A further study indicates that general hydroxyl radical scavengers such as mannitol, ethanol or benzoate failed to prevent the PON inactivation. Based on these results, it is proposed that the PON inactivation during LDL oxidation may be ascribed mainly to the Cu^2+-catalyzed oxidation.

Cumene hydroperoxide에 의한 paraoxonase 1의 산화적 불활성화에 대한 보호 방안

스, 위엥쥐,류희문,김주령,석대은 충남대학교 약학대학 의약품개발연구소 2003 藥學論文集 Vol.18 No.-

Paraoxonase 1 (PON1), an enzyme associated with high density lipoprotein (HDL), is known to protect low density lipoprotein (LDL) from lipid peroxidation involving copper ion. However, Paraoxonase 1 activity was observed to decrease during LDL oxidation. Here, the inactivation of PON1 by various peroxides was examined. Paraoxonase 1, purified from human plasma, was subjected to cumene hydroperoxide, hydrogen peroxide or tert-butyl hydroperoxide. PON activity, based on the hydrolysis of phenyl acetate, decreased by approximately 40 and 38 %, respectively, after the exposure to 2mM cumene hydroperoxide and hydrogen peroxide, while tert-butyl hydroperoxide had no remarkable inhibitory effect. Next, the compounds capable of preventing against cumene hydroperoxide-induced inactivation of PONl were screened. While quercetin or phenyl acetate failed to protect PON1, lauric acid or calcium chloride was found to protect PONl from cumene hydroperoxide-induced inactivation. Especially, lauric acid appeared to show the greater protection than the other fatty acids tested. In further study, lauric acid showed a dose-dependent protection with an E& value of around 35 μM. Based on these results, It is proposed that the alky hydroperoxide-induced inactivation of Paraoxonase 1 can be prevented by a proper fatty acid recipe.

An implementation of CSG modeling technique on Machining Simulation using C++ and Open GL

Duy Le,Su-Jin Kim(김수진),Jong-Min Lee(이종민),Anh-Thi Nguyen,Vy-Thoai Ha 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11

An application of CSG (Constructive Solid Geometry) modeling technique in Machining Simulation is introduced in this paper. The current CSG model is based on z-buffer CSG Rendering Algorithm. In order to build a CSG model, frame buffers of VGA (Video Graphic Accelerator) should be used in term of color buffer, depth buffer, and stencil buffer. In addition to using CSG model in machine simulation Stock and Cutter Swept Surface (CSS) should be solid. Method to create a solid Cuboid stock and Ball-end mill CSS are included in the present paper. Boolean operations are used to produce the after-cut part, especially the Difference operation between Stock and CSS as the cutter remove materials form stock. Finally, a small program called MaSim which simulates one simple cut using this method was created.

Fiscal Decentralisation and Spatial Externalities in Vietnam Provincial Economic Growth

Bui Duy Tung,Canh Phuc Nguyen,DINH THANH SU 중앙대학교 경제연구소 2021 Journal of Economic Development Vol.46 No.4

This paper aims to investigate the impacts of fiscal decentralisation on the provincial economic development in 62 Vietnamese provinces from 2011-2018. We estimate a Spatial Durbin Model (SDM) based on a growth model with spatial externalities. The focus of the paper is on the spatial spillover effects of fiscal decentralisation on the provincial income levels. The results confirm the existence of spatial interdependency among Vietnamese provinces. The findings indicate that fiscal decentralisation and physical capital not only affects the income level within one province, but also contribute positively to the outputs of nearby provinces. The study does not find significant effects of human capital on provincial income. We also show that these effects vary across five main economic regions of Vietnam. There is also evidence that the total effects are stronger in high institutional quality levels, which points out to the “sand the wheels” effect. Policy implications are also discussed.