Browsing by Author "Tseng, Chi Feng"

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Analysis of antioxidant as a therapeutic agent for atherosclerosis
(2006-11-01)
Tseng, Chi Feng
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Mao, Simon J. T.
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生醫工程研究所
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Institute of Biomedical Engineering
Research into the oxidation of lipoprotein has yielded many insights into the underlying process of the development of atherosclerosis. Oxidative modification of low density lipoprotein (LDL) has been suggested as an initial step in the pathogenesis of atherosclerosis. However, up until now, investigations of antioxidants have mostly focused on three main dietary antioxidant vitamins (beta-carotene, vitamin C, and vitamin E) and some synthetic compounds. Among those antioxidants, probucol, a synthetic compound, has been shown to be an extremely potent and effective antioxidant in preventing the formation of atherosclerosis in both in vitro and in vivo studies. The present review focuses on commonly used analytical methods for measuring the antioxidant potency and outlines the, critical steps on how to evaluate and design a potent antioxidant agent that can be used for the intervention of atherosclerosis. We concluded that an antioxidant should first be targeted and incorporated into human LDL. Second, the candidate compound should possess high bioavailability. The rationale and strategy for the analytical procedures are discussed in this report.
Evidence of tandem repeat and extra thiol-groups resulted in the polymeric formation of bovine haptoglobin: A unique structure of Hp 2-2 phenotype
(2007-11-30)
Lai, Yi An
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Lai, I. Hsiang
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Tseng, Chi Feng
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Lee, James
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Mao, Simon J. T.
Human plasma Hp is classified as 1-1, 2-1, and 2-2. They are inherited from two alleles Hp 1 and Hp 2, but there is only Hp 1 in almost all the animal species. Hp 2-2 molecule is extremely large and heterogeneous associated with the development of inflammatory-related diseases. In this study, we expressed entire bovine Hp in E. coli as a alpha beta linear form. Interestingly, the antibodies prepared against this form could recognize the subunit of native Hp. In stead of a complicated column method, the antibody was able to isolate bovine Hp via immunoaffinity and gel-filtration columns. The isolated Hp is polymeric containing two major molecular forms (660 and 730 kDa). Their size and hemoglobin binding complex are significantly larger than that of human Hp 2-2. The amino-acid sequence deducted from the nucleotide sequence is similar to human Hp 2 containing a tandem repeat over the cc chain. Thus, the Hp 2 allele is not unique in human. We also found that there is one additional -SH group (Cys-97) in bovine alpha chain with a total of 8 -SH groups, which may be responsible for the overall polymeric structure that is markedly different from human Hp 2-2. The significance of the finding and its relationship to structural evolution are also discussed.
Low levels of haptoglobin and putative amino acid sequence in Taiwanese Lanyu miniature pigs
(2008-04-01)
Yueh, Sunny C. H.
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Wang, Yao Horng
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Lin, Kuan Yu
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Tseng, Chi Feng
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Chu, Hsien Pin
Porcine haptoglobin (Hp) is an acute phase protein. Its plasma level increases significantly during inflammation and infection. One of the main functions of Hp is to bind free hemoglobin (Hb) and inhibit its oxidative activity. In the present report, we studied the Hp phenotype of Taiwanese Lanyu miniature pigs (TLY minipigs; n=43) and found their Hp structure to be a homodimer (beta-alpha-alpha-beta) similar to human Hp 1-1. Interestingly, Western blot and high performance liquid chromatographic (HPLC) analysis showed that 25% of the TLY minipigs possessed low or no plasma Hp level (<0.05 mg/ml). The Hp cDNA of these TLY minipigs was then cloned, and the translated amino acid sequence was analyzed. No sequences were found to be deficient; they showed a 99.7% identity with domestic pigs (NP_999165). The mean overall Hp level of the TLY minipigs (0.21 +/- 0.25 mg/ml; n=43) determined by enzyme-linked immunosorbent assay (ELISA) was markedly lower than that of domestic pigs (0.78 +/- 0.45 mg/ml; p<0.001), while 25% of the TLY minipigs had an Hp level that was extremely low (<0.05 mg/ml). In addition, the initial recovery rate (first 40 min) in the circulation of infused fluorescein isothiocyanate (FITC)-Hb was significantly higher in the TLY minipigs with extremely low Hp levels than those with high levels. This data suggests that the low concentration of Hp-Hb complex is responsible for the higher recovery rate of Hb in the circulation. TLY minipigs have been used as an experimental model for cardiovascular diseases; whether they can be used as a model for inflammatory diseases, with Hp as a marker, remains a topic of interest. However, since the Hp level varies significantly among individual TLY minipigs, it is necessary to prescreen the Hp levels of the animals to minimize variation in the experimental baseline. The present study may provide a reference value for future use of the TLY minipig as an animal model for inflammation-associated diseases.