Parametric Studies of the Mechanical Behaviour of Porous Titanium

Seah, Khw,Thampuran, R .,Teoh, Sh . 대한금속재료학회(대한금속학회) 1998 METALS AND MATERIALS International Vol.4 No.4

This paper investigates the prediction of some common mechanical properties of sintered pure titanium. Tensile strength was determined using the radial crush strength method and the fracture toughness tests were performed using disk-shaped compact tension specimens. Empirical models that predict the mechanical behaviour of sintered titanium are reported in this paper and compared with other models like those of Hashin-Strikman, Fleck and Smith, Griffiths et al. and Nielson.

Low-power and low-drug-dose photodynamic chemotherapy <i>via</i> the breakdown of tumor-targeted micelles by reactive oxygen species

Seah, Geok Leng,Yu, Jeong Heon,Yang, Moon Young,Kim, Woo Jin,Kim, Jin-Ho,Park, Keunchil,Cho, Jae-Woo,Kim, Jee Seon,Nam, Yoon Sung Elsevier 2018 Journal of controlled release Vol.286 No.-

<P><B>Abstract</B></P> <P>Tumor-targeted delivery of anticancer agents using nanocarriers has been explored to increase the therapeutic index of cancer chemotherapy. However, only a few nanocarriers are clinically available because the physiological complexity often compromises their ability to target, penetrate, and control the release of drugs. Here, we report a method which dramatically increases <I>in vivo</I> therapeutic drug efficacy levels through the photodynamic degradation of tumor-targeted nanocarriers. Folate-decorated poly(ethylene glycol)-polythioketal micelles are prepared to encapsulate paclitaxel and porphyrins. Photo-excitation generates reactive oxygen species within the micelles to cleave the polythioketal backbone efficiently and facilitate drug release only at the illuminated tumor site. Intravenous injection of a murine xenograft model with a low dose of paclitaxel within the micelles, one-milligram drug per kg (mouse), corresponding to an amount less than that of Taxol by one order of magnitude, induces dramatic tumor regression without any acute systemic inflammation responses or organ toxicity under low-power irradiation (55 mW cm<SUP>−2</SUP>) at 650 nm.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Photodynamically-induced drug delivery under low light intensity and low drug dose </LI> <LI> ROS-scavenging micelles releasing paclitaxel under 650 nm light irradiation </LI> <LI> Dramatic reduction of IC<SUB>50</SUB> of paclitaxel to 4.27% of the reported value </LI> <LI> Efficient ROS consumption by PPADT micelles </LI> <LI> Only 5% of maximum tolerated dose of paclitaxel for tumor suppression </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

The Future of Mathematics Education in a Multipolar World

( Seah Wee Tiong ) 한국수학교육학회 2017 수학교육 학술지 Vol.2017 No.2

In the last 200 years or so, developments in the world`s business and economics, fashion, media, science and technology, and even (mathematics) educational approaches had been led by Western thinkers and scientists. As the world becomes multipolar, it is timely to consider how the nature of research academic work and students` mathematics learning experience might evolve. This paper considers how the mathematics education research communities inside and outside the highperforming East Asian economies might go about sharing and adapting/adopting respectively teaching practices which appear to contribute to student performance in mathematics. The meaningful sharing of teaching practices in the new, multipolar world would also highlight the need to acknowledge the sociocultural aspect of mathematics education. Another aspect of mathematics education research which has become more significant is the valuing of particular teaching and learning activity. Indeed, there is a greater need now than ever before for the research community to make sense of - and benefit from - mathematics learning/teaching contexts from the sociocultural perspective, at the same time complementing traditionally popular cognitive and affective perspectives of mathematics pedagogy with the conative.

Giving Flesh and Emotions to Cold, Hard Quantitative Data

( Seah Wee Tiong ) 한국수학교육학회 2017 수학교육 학술지 Vol.2017 No.2

The collection, analysis and interpretation of quantitative data are often thought of as being objective and impartial. The same process and consideration are expected to apply to different research situations. As wrote, “by remaining several steps removed from the people from whom the data has been obtained, … quantitative researchers argue that they are upholding research standards that are at once empirically rigorous, impartial, and objective” (Rao& Woolcock, 2003, p. 166). More recently, however, both these claims to validity and reliability are being challenged. For example, how are the results valid when they do not take into account cultural idiosyncrasies and relativity? Also, isn`t a study still replicable if adjustments for cultural factors are explicitly and openly listed? In this workshop, participants will examine a few examples of quantitative studies where the strength in the findings would have been boosted further if cultural factors were taken into account. Participants will also discuss and explore ways in which quantitative data can be collected, analysed and interpreted in ways which are culturally sensitive, thus optimising research strength.

Cancer-targeted reactive oxygen species-degradable polymer nanoparticles for near infrared light-induced drug release

Seah, Geok Leng,Yu, Jeong Heon,Koo, Bon Il,Lee, Dong Jae,Nam, Yoon Sung The Royal Society of Chemistry 2018 Journal of materials chemistry. B, Materials for b Vol.6 No.46

<P>Nanocarriers can be translocated to the peripheral region of tumor tissues through the well-known enhanced permeability and retention effects. However, a high dose of nanocarriers need to be injected due to the low delivery efficiency of nanocarriers, which can also increase the side effects of off-targeted nanocarriers in normal tissues. It was demonstrated that on-demand drug release from tumor-targeted nanocarriers can reduce the effective dosage of anti-cancer drugs by rapidly increasing the local drug concentration in the tumor tissue. Here we report a near-infrared (NIR) photodynamic method to trigger drug release from tumor-targeted polymer nanoparticles <I>via</I> reactive oxygen species (ROS)-mediated polymer degradation. Paclitaxel and silicon 2,3-naphthalocyanine bis(trihexylsilyloxide) were co-encapsulated as an anti-cancer drug and photosensitizer, respectively, within biotin-decorated poly(ethylene glycol)-polythioketal micelles. Upon NIR light illumination under the maximum permissible exposure level, the photoexcited naphthalocyanine generated ROS cleaved the thioketal groups in the micelles to release the encapsulated paclitaxel. The photodynamically-induced release of paclitaxel dramatically reduced the half maximal inhibitory concentration of paclitaxel by 39.9-fold and eliminated lung adenocarcinoma at a concentration an order of magnitude smaller than its maximum tolerated dosage. Even under a simulated deep tissue condition with a tissue-like phantom, the NIR light-illuminated micelles exhibited a high level of cytotoxicity against the tumor cells and efficiently suppressed tumor growth. Our study demonstrates that photodynamic polymer degradation is an effective means to improve the anticancer drug efficacy of tumor-targeted micelles.</P>

Cryopreservation of human adipose-derived stem cells for the clinical use

Seah Park,Jiyoung Kim,Hyun Mi Kang,Sujin Yun,Yeonhwa Song,Hye Jin Yang,A young Yoon,Sun Young Baek,Si Hyung Yoo,Sun Hee Kim,Haekwon Kim 한국발생생물학회 2011 한국발생생물학회 학술발표대회 Vol.30 No.-

Mesenchymal stem cells (MSC) are of great interest for cell-based therapies and tissue engineering approaches, as these cells are capable for extensive self-renewal and display a multilineage differentiation potential. Clinical application of these cells for degenerative and age-related diseases has been accumulating. However, preparation of MSC before the onset of the diseases, it needs to develop the cryopreservation method. Most cryopreservation methods include fetal bovine serum (FBS) which is essential for effective cryopreservation. Yet it should not be used clinically because of the potential risk of infection. In the present study, we investigated whether human serum albumin (HSA), human serum (HS), and knockout serum replacement (KSR) can be used as an alternative of FBS for cryopreservation of human adipose derived stem cells (hADSC). Cells cryopreserved with 9% HSA showed much higher viability after thawing compared with cells frozen with 5% or 1% HSA. Cells cryopreserved with 90% HS or KSR exhibited greater viability than cells frozen with 25% and 5% HS or KSR, respectively. Viability of cells frozen with 9% HSA, 90% HS or 90% KSR was comparable to that with 90% FBS. Morphology and proliferation ability of these cells were not affected by cryopreservation when compared the freshly obtained cells. Cryopreserved hADSC expressed transcription factor genes including Oct3/4, Nanog, Nestin and Sox2, which are related to the self-renewal of stem cells. Flow cytometric analyses showed that both fresh and cryopreserved hADSC were positive for the antigens of HLA-ABC, CD44, CD73, CD90, and CD105, CD166, and negative for HLA-DR, CD31, and CD34. Similar to fresh cells, cryopreserved hADSC could differentiate into mesodermal lineages, adipogenic, osteogenic, or chondrogenic cells. These results suggest that 9% HSA, 90% HS or 90% KSR can be used to replace FBS during successful cryopreservation of hADSC.

International Medicine in Canada

Seah, S.K.K INSTITUTE OF TROPICAL MEDICINE YONSEI UNIVERSITY 1979 YONSEI REPORTS ON TROPICAL MEDICINE Vol.10 No.1

케나다처럼 環境衛生 水準이 높고 특히 겨울이면 왜만한 昆? 媒介性 疾患이 자취를 감추는 溫帶地域에 屬하는 여러나라의 醫師들이 熱帶醫學에 非常한 關心을 가지는 理由는 熱帶地域과 溫帶地域에 있어 疾病의 樣相에 相當한 差異가 있기때문이라 하겠다. 卽 熱帶地域에 있어서의 醫學은 感染性 疾患에 큰 比重을 두고 있는 반면 溫帶地域에 있어서는 大?로 退行性 疾患, 心血性疾患 및 惡性 腫瘍等이 主要 問題로 되어 있다. 특히 過食, 알코올中毒, 吸煙, 運動不足, 精神病的, 情緖問題等이 主要 健康問題로 取扱되고 있다. 캐나다 亦是 韓國과 마찬가지로 溫帶地域에 屬하여 여러 가지 類似한 事項, 健康管理를 위한 國際的 事業 및 앞으로의 展望等에 關하여 要約 考察하는 바이다.

ASIAN VULNERABILITIES TO SOVIET INFLUENCE AND MANIPULATION: A VIEW FROM SINGAPORE

Seah, Chee-Meow The Institute for Far Eastern Studies Kyungnam Uni 1985 ASIAN PERSPECTIVE Vol.9 No.1

ASEAN AND ITS PERCEPTIONS ON WESTERN PACIFIC SECURITY

Seah,Chee-Meow The Institute for Far Eastern Studies Kyungnam Uni 1981 ASIAN PERSPECTIVE Vol.5 No.2

ASEAN is likely to be a spectator to any form of military-security arrangement emerging or has already been established in the Western Pacific region. While possessing economic resources and having faster economic growth rates than the indochinese states, the ASEAN countries are still beseiged by problems of development, over-population and of political integration.

Comparison of Split versus Subunit Seasonal Influenza Vaccine in Korean Children over 3 to under 18 Years of Age

( Seah Kang ),( Dong Ho Kim ),( Byung Wook Eun ),( Nam Hee Kim ),( Eun Kyeong Kang ),( Byong Sop Lee ),( Yun-kyung Kim ) 대한소아감염학회 2019 Pediatric Infection and Vaccine Vol.26 No.3

목적: 본 연구는 국내 소아청소년에서 인플루엔자 분할백신 접종군과 인플루엔자 아단위백신 접종군 간 면역원성 및 안전성을 파악하기 위해 시행하였다. 방법: 2008년 10월부터 12월까지 서울과 경기도 지역의 여섯 개의 병원에 방문한 202명의 건강한 만 36개월에서 18세 미만의 소아청소년을 대상으로 하였으며 이들은 인플루엔자 분할백신 또는 아단위백신을 접종받았다. H1N1, H3N2, 그리고 B형의 인플루엔자 바이러스 항원의 면역원성을 평가하기 위해 접종 후 혈구응집억제 항체가가 1:40 이상인 피험자의 비율, 항체 양전률, 그리고 geometric mean titer를 계산하였다. 모든 접종자들에서 국소 그리고 전신 이상반응을 관찰하였다. 결과: 분할백신 접종군과 아단위백신 접종군에서 H1N1, H3N2, B형 항원에 대하여 항체가가 1:40 이상으로 나타난 피험자의 비율은 유사하였다(95.9%, 94.9%, 96.9% vs. 96.0%, 90.9%, 87.9%). 36개월 이상 72개월 미만의 소아에서 두 접종군 간 항체가가 1:40 이상으로 나타난 피험자의 비율은 유사하게 나타났다. 72개월 이상 18세 미만의 소아에서는 H1N1, H3N2, 그리고 B에 대해 항체가가 1:40 이상으로 나타난 피험자의 비율은 모두 높게 나타났으나 (98.4%, 98.4%, 98.4% vs. 97.0%, 95.5%, 91.0%), 항체 양전율은 상대적으로 낮았다 (39.1%, 73.4%, 35.9% vs. 34.3%, 55.2%, 38.8%). 또한 분할백신 접종군에서 아단위백신 접종군에서보다 국소 및 전신 이상반응의 비율이 더 높았으나 두 접종군 모두에서 중대한 이상반응은 나타나지 않았다. 결론: 인플루엔자 분할백신 접종군과 아단위백신 접종군 모두에서 3세 이상 18세 미만의 연령군에서 적절한 면역원성을 보였다. 또한 두 접종군에서 모두 중대한 이상반응은 발생하지 않았다. Purpose: This study was conducted to compare immunogenicities and reactogenicities of the trivalent inactivated subunit influenza vaccine and split influenza vaccine in Korean children and adolescents. Methods: In total, 202 healthy children aged 36 months to <18 years were enrolled at six hospitals in Korea from October to December 2008. The subjects were vaccinated with either the split or subunit influenza vaccine. The hemagglutinin inhibition antibody titers against the H1N1, H3N2, and B virus strains were measured, and the seroconversion rates, seroprotection rates, and geometric mean titers were calculated. All subjects were observed for local and systemic reactions. Results: Both the split and subunit vaccine groups had similar seroprotection rates against all strains (95.9%, 94.9%, 96.9% vs. 96.0%, 90.9%, and 87.9%). In children aged 36 to <72 months, the seroprotection rates were similar between the two vaccine groups. In children aged 72 months to <18 years, both vaccines showed high seroprotection rates against the H1N1, H3N2, and B strain (98.4%, 98.4%, 98.4% vs. 97.0%, 95.5%, and 91.0%), but showed relatively low seroconversion rates (39.1%, 73.4%, 35.9% vs. 34.3%, 55.2%, and 38.8%). There were more local and systemic reactions in the split vaccine group than in the subunit vaccine group; however, no serious adverse reactions were observed in both groups. Conclusions: Both the split and subunit vaccines showed acceptable immunogenicity in all age groups. There were no serious adverse events with both vaccines.