Melatonin Protects Human Adipose-Derived Stem Cells from Oxidative Stress and Cell Death

Shaun S. Tan,Xiaolian Han,Priyadharshini Sivakumaran,,Shiang Y. Lim,Wayne A. Morrison 대한성형외과학회 2016 Archives of Plastic Surgery Vol.43 No.3

Background Adipose-derived stem cells (ASCs) have applications in regenerative medicine based on their therapeutic potential to repair and regenerate diseased and damaged tissue. They are commonly subject to oxidative stress during harvest and transplantation, which has detrimental effects on their subsequent viability. By functioning as an antioxidant against free radicals, melatonin may exert cytoprotective effects on ASCs. Methods We cultured human ASCs in the presence of varying dosages of hydrogen peroxide and/or melatonin for a period of 3 hours. Cell viability and apoptosis were determined with propidium iodide and Hoechst 33342 staining under fluorescence microscopy. Results Hydrogen peroxide (1–2.5 mM) treatment resulted in an incremental increase in cell death. 2 mM hydrogen peroxide was thereafter selected as the dose for co-treatment with melatonin. Melatonin alone had no adverse effects on ASCs. Co-treatment of ASCs with melatonin in the presence of hydrogen peroxide protected ASCs from cell death in a dose-dependent manner, and afforded maximal protection at 100 μM (n=4, one-way analysis of variance P<0.001). Melatonin co-treated ASCs displayed significantly fewer apoptotic cells, as demonstrated by condensed and fragmented nuclei under fluorescence microscopy. Conclusions Melatonin possesses cytoprotective properties against oxidative stress in human ASCs and might be a useful adjunct in fat grafting and cell-assisted lipotransfer.

Professional Associations and Barriers to Intrapreneurship and Entrepreneurship

Joseph S. Merrill,Terry M. Chambers,Wayne A. Roberts KINFORMS 2008 Management Review Vol.3 No.1

This paper focuses on an entrepreneur in the Alaskan marine piloting industry who wanted to make changes to meet changing needs in the market, but faced obstacles from entrenched industry participants with established relationships with a powerful state-sanctioned board. This paper illustrates how professional associations working with and through the government can inhibit individual members from being innovative. This paper also reviews the literature pertinent to entrepreneurship and intrapreneurship. This should be of interest to those interested in the impact of organizational and other barriers to entrepreneurial activity, as well as those interested in the marine piloting industry.

Melatonin Protects Human Adipose-Derived Stem Cells from Oxidative Stress and Cell Death

Tan, Shaun S.,Han, Xiaolian,Sivakumaran, Priyadharshini,Lim, Shiang Y.,Morrison, Wayne A. Korean Society of Plastic and Reconstructive Surge 2016 Archives of Plastic Surgery Vol.43 No.3

Background Adipose-derived stem cells (ASCs) have applications in regenerative medicine based on their therapeutic potential to repair and regenerate diseased and damaged tissue. They are commonly subject to oxidative stress during harvest and transplantation, which has detrimental effects on their subsequent viability. By functioning as an antioxidant against free radicals, melatonin may exert cytoprotective effects on ASCs. Methods We cultured human ASCs in the presence of varying dosages of hydrogen peroxide and/or melatonin for a period of 3 hours. Cell viability and apoptosis were determined with propidium iodide and Hoechst 33342 staining under fluorescence microscopy. Results Hydrogen peroxide (1-2.5 mM) treatment resulted in an incremental increase in cell death. 2 mM hydrogen peroxide was thereafter selected as the dose for co-treatment with melatonin. Melatonin alone had no adverse effects on ASCs. Co-treatment of ASCs with melatonin in the presence of hydrogen peroxide protected ASCs from cell death in a dose-dependent manner, and afforded maximal protection at $100{\mu}M$ (n=4, one-way analysis of variance P<0.001). Melatonin co-treated ASCs displayed significantly fewer apoptotic cells, as demonstrated by condensed and fragmented nuclei under fluorescence microscopy. Conclusions Melatonin possesses cytoprotective properties against oxidative stress in human ASCs and might be a useful adjunct in fat grafting and cell-assisted lipotransfer.

A Generic Time-resolved Fluorescence Assay for Serine/threonine Kinase Activity: Application to Cdc7/Dbf4

Xu, Kui,Stern, Alvin S.,Levin, Wayne,Chua, Anne,Vassilev, Lyubomir T. Korean Society for Biochemistry and Molecular Biol 2003 Journal of biochemistry and molecular biology Vol.36 No.4

The serine/threonine protein kinase family is a large and diverse group of enzymes that are involved in the regulation of multiple cellular pathways. Elevated kinase activity has been implicated in many diseases and frequently targeted for the development of pharmacological inhibitors. Therefore, non-radioactive antibody-based kinase assays that allow high throughput screening of compound libraries have been developed. However, they require a generation of antibodies against the phosphorylated form of a specific substrate. We report here a time-resolved fluorescence assay platform that utilizes a commercially-available generic anti-phosphothreonine antibody and permits assaying kinases that are able to phosporylate threonin residues on protein substrates. Using this approach, we developed an assay for Cdc7/Dbf4 kinase activity, determined the $K_m$ for ATP, and identified rottlerin as a non-ATP competitive inhibitor of this enzyme.

판금 구조물의 열좌굴 예측을 위한 유한요소해석 및 실험적 검증

이주원(J. W. Lee),Wayne Cai,Thomas B. Stoughton,남성우(S. W. Nam),정철영(C. Y. Jung),윤정환(J. W. Yoon) 한국소성가공학회 2022 한국소성가공학회 학술대회 논문집 Vol.2022 No.5

Metal-induced growth of crystal Si for low-cost Al:ZnO/Si heterojunction thin film photodetectors

Tong, Chong,Kozarsky, Eric S.,Kim, Joondong,Yun, Juhyung,Anderson, Wayne A. Elsevier 2018 Materials science in semiconductor processing Vol.82 No.-

<P><B>Abstract</B></P> <P>Quality crystal silicon (Si) thin films were grown via the metal-induced growth (MIG) method, which is a low-cost and metal-silicide assisted technique. The metal catalysts of Ni, Pd and Co were first deposited onto substrates for silicide template layer formation. Then, crystal Si thin films with a thickness of ~ 5 µm were epitaxially deposited on the silicide seeds via DC magnetron sputtering. The crystallinity of the Si films was confirmed and investigated by X-ray diffraction (XRD). These Si thin films were then used to fabricate Al doped ZnO (AZO)/MIG Si heterojunction photodetectors. The device achieved a saturation photocurrent of 23.2 mA/cm<SUP>2</SUP> at − 5 V. This photocurrent level is comparable with that of previous reported AZO/bulk-Si devices. Current transport mechanisms and defect distributions were also studied. By analyzing the dark current-voltage (I – V) characteristics, the space charge limited (SCL) current dominated junction behaviors with an exponential defect level distribution were determined. In the bias range of 0.25 V < V < 1.0 V, SCL current transported in the mobility regime based on I ∝ V<SUP>β</SUP>, where β > 3. For 0 <SUP><</SUP> V < 0.25 V, tunneling and SCL current in ballistic regime were implied due to I ∝ V<SUP>1.5</SUP>. In the reverse bias, the device exhibited SCL current in saturation regime or tunneling, suggested by the unity I-V relation. The fabricated devices with the theoretical understanding of the defect and carrier transport mechanisms provided new design insights for low-cost ZnO/MIG-Si thin film optoelectronics.</P>

A Generic Time-resolved Fluorescence Assay for Serine/threonine Kinase Activity : Application to Cdc7/Dbf4

Xu, Kui,Stern, Alvin S.,Levin, Wayne,Chua, Anne,Vassilev, Lyubomir T. 한국생화학분자생물학회 2003 BMB Reports Vol.36 No.4

The serine/threonine protein kinase family is a large and diverse group of enzymes that are involved in the regulation of multiple cellular pathways. Elevated kinase activity has been implicated in many diseases and frequently targeted for the development of pharmacological inhibitors. Therefore, non-radioactive antibody-based kinase assays that allow high throughput screening of compound libraries have been developed. However, they require a generation of antibodies against the phosphorylated form of a specific substrate. We report here a time-resolved fluorescence assay platform that utilizes a commercially-available generic anti-phospho-threonine antibody and permits assaying kinases that are able to phosporylate threonin residues on protein substrates. Using this approach, we developed an assay for Cdc7/Dbf4 kinase activity, determined the K_(m) for ATP, and identified rottlerin as a non-ATP competitive inhibitor of this enzyme.

Comparison of Cytoplasmic Inclusions Induced by Maize Dwarf Mosaic Virus Strain A and B

최창원,Choi, Chang-Won,Gardner, Wayne S. Korean Society of Electron Microscopy 1994 Applied microscopy Vol.24 No.2

Maize dwarf mosaic virus (MDMV) strain A에 감염된 수수 (Sorghum bicolor L. Moench) 품종 HOK와 strain B에 감염된 Pioneer 8680의 엽세포를 미세구조적으로 비교연구한 결과 종단면과 횡단면으로 초박절편된 표본에서 다양한 원통형 봉입체의 형성이 관찰되었다. MDMV strain A와 B는 세포질 내에 존재하는 특별한 봉입체의 유무에 따라 뚜렷이 구별되었다. MDMV-B에 감염된 Pioneer 8680 수수 엽세포는 pinwheels, bundles, scrolls, 그리고 laminated aggregates 형태의 원통형 봉입체가 관찰된 반면, MDMV-A에 감염된 HOK 수수 엽세포에서는 laminated aggregates가 결여되어 있다. 특히 laminated aggregates의 유무와 관련하여 MDMV 두 strain간에 원통형 봉입체의 미세구조적 차이점은 potyvirus군을 아군으로 분류하는 형태학적 지표가 되어왔다. laminated aggregates가 존재하면 아군 III으로, 존재하지 않을 경우 아군 I로 분류될 수 있다. 이런 원통형 봉입체의 이형화는 바이러스 특이적 유도체로서, 아마도 감염의 발전에 따른 형태 발생을 발현하는 것으로 사료된다. Comparative ultrastructural studies of sorghum (Sorghum bicolor L. Moench) cultivar (cv.) HOK and cv Pioneer 8680 leaf cells separately infected with maize dwarf mosaic virus (MDMV) strain A and B, respectively, revealed the formation of numerous cylindrical inclusions in both cross and longitudinal sections. The MDMV-A and -B were distinguished by the presence or absence of specific inclusion bodies in the cytoplasm. Electron microscope revealed the presence of pinwheels, bundles, scrolls, and laminated aggregates in Pioneer 8680 sorghum leaf cells infected with MDMV-B while no laminated aggregates were found in cells of HOK sorghum leaf cells infected with MDMV-A. Differences in the ultrastructure of cylindrical inclusions between two strains of MDMV, especially with respect to laminated aggregates, have been morphologically indexed to classify potyviruses into subdivision. The presence of laminated aggregates may be assigned to subdivision III while the absence of laminated aggregates is assigned to subdivision I. These variations of structures associated with cylindrical inclusions appeared virus-specific inductions and may be represented the morphogenesis of inclusion bodies following development of infections.

Wind tunnel study of wind loading on rectangular louvered panels

D. Zuo,C.W. Letchford,S. Wayne 한국풍공학회 2011 Wind and Structures, An International Journal (WAS Vol.14 No.5

Drag forces on a rectangular louvered panel, both as a free-standing structure and as a component in a generic low-rise building model, were obtained in a wind tunnel study. When tested in a building model, the porosity ratio of the wall opposite the louvered panel was varied to investigate its effect on the loading of the louvered panel. Both mean and pseudo-steady drag coefficients were obtained. Comparisons with the provisions for porous walls in contemporary loading standards indicate that for some opposite wall porosity ratios, the standards specify significantly different wind loads (larger and smaller) than obtained from this wind tunnel study.

Wind tunnel study of wind loading on rectangular louvered panels

Zuo, D.,Letchford, C.W.,Wayne, S. Techno-Press 2011 Wind and Structures, An International Journal (WAS Vol.14 No.5

Drag forces on a rectangular louvered panel, both as a free-standing structure and as a component in a generic low-rise building model, were obtained in a wind tunnel study. When tested in a building model, the porosity ratio of the wall opposite the louvered panel was varied to investigate its effect on the loading of the louvered panel. Both mean and pseudo-steady drag coefficients were obtained. Comparisons with the provisions for porous walls in contemporary loading standards indicate that for some opposite wall porosity ratios, the standards specify significantly different wind loads (larger and smaller) than obtained from this wind tunnel study.