Browsing by Author "Wu, TZ"

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A synthetic complement C1q-like peptide selectively interacts with immune complexes
(1998-12-01)
Chan, EC
;
Pan, MZ
;
Chang, CA
;
Wu, TZ
;
Kuo, YB
A water-soluble peptide possessing an immune complex selective affinity was synthesized and its primary structure established as: Leu-Glu-Gln-Gly-Glu-Asn-Val-Phe-Leu-Gln-Ala-Thr-Ser-Asp-Asp-Cys. This peptide, designated as C1q-like peptide (CLP), represents a possible immune complex binding epitope of complement C1q. CLP has a hydrophilicity value of 0.21. At 0.5 mu M, it inhibited by 50% natural human C1q from binding to horseradish peroxidase-rabbit anti-peroxidase immune complex. CLP failed to inhibit Staphylococcus aureus protein A from binding monomeric IgG. When coated to a microplate, CLP showed selective binding to the immune complex, and could be used for application in immunochemical detection of immune complex.
Effects of recombinant lysostaphin on cytotoxicity and interleukin-8 level in normal human epidermal keratinocytes cell line
(1998-11-01)
Chan, EC
;
Chang, CA
;
Wu, TZ
;
Lin, YL
;
生物科技學系
The normal human epidermal keratinocyte (NHEK) was used to evaluate the cytotoxicity of recombinant lysostaphin. As determined with the Neutral Red (NR) cytotoxicity assay, the midpoint toxicity value (NR50) after 48 h exposure was 16 +/- 0.4 g lysostaphin/l. Lysostaphin cytotoxicity effect is much less than the surface active agent, sodium laurate. However, the NR,, value after 48-h exposure was 1.9 +/- 0.02 g/l for S. aureus lysate derived from the bacterial lytic action of lysostaphin. A linear increase in interleukin-8 (IL-8) level in NHEK cells from resting levels of 65 +/- 3 pg/ml to peak of 760 +/- 15 pg/ml during the first 9 hours was noted for the cells treated with 800 mg lysostaphin/l. S. aureus lysate has the same effect on the induction of IL-8 levels. The induced rises in IL-8 were lysostaphin and S. aureus lysate concentration dependence.
Effects of recombinant lysostaphin on cytotoxicity and interleukin-8 level in normal human epidermal keratinocytes cell line
(1998-11-01)
Chan, EC
;
Chang, CA
;
Wu, TZ
;
Lin, YL
;
生物科技學系
The normal human epidermal keratinocyte (NHEK) was used to evaluate the cytotoxicity of recombinant lysostaphin. As determined with the Neutral Red (NR) cytotoxicity assay, the midpoint toxicity value (NR50) after 48 h exposure was 16 +/- 0.4 g lysostaphin/l. Lysostaphin cytotoxicity effect is much less than the surface active agent, sodium laurate. However, the NR,, value after 48-h exposure was 1.9 +/- 0.02 g/l for S. aureus lysate derived from the bacterial lytic action of lysostaphin. A linear increase in interleukin-8 (IL-8) level in NHEK cells from resting levels of 65 +/- 3 pg/ml to peak of 760 +/- 15 pg/ml during the first 9 hours was noted for the cells treated with 800 mg lysostaphin/l. S. aureus lysate has the same effect on the induction of IL-8 levels. The induced rises in IL-8 were lysostaphin and S. aureus lysate concentration dependence.
Purification and characterization of neutral sphingomyelinase from Helicobacter pylori
(2000-04-25)
Chan, EC
;
Chang, CC
;
Li, YS
;
Chang, CA
;
Chiou, CC
Phospholipase activities of human gastric bacterium, Helicobacter pylori , are regarded as the pathogenic factors owing to their actions on epithelial eel membranes. In this study, we purified and characterized neutral sphingomyelinase (N-SMase) from the superficial components of H. pylori strains for the first time. N-SMase was purified 2083-fold with an overall recovery of 37%. The purification steps included acid glycine extraction, ammonium sulfate precipitation, CM-Sepharose, Mono-Q, and Sephadex G-75 column chromatography. Approximate molecular mass for the native N-SMase was around 32 kDa. When N-omega-trinitrophenylaminol auryl sphingomyelin (TNPAL-SM) was used as a substrate, the purified enzyme exhibited a K-m of 6.7 mu M and a V-max of 15.6 nmol of TNPAL-sphingosine/h/mg of protein at 37 degrees C in 50 mM phosphate-buffered saline, pH 7.4. N-SMase I-caches optimal activity at pH 7.4 and has a pi of 7.5. The enzyme activity is magnesium dependent and specifically hydrolyzed sphingomyelin and phosphatidylethanolamine. The enzyme also exhibits hemolytic activity on human erythrocytes. According to Western blot analysis, a rabbit antiserum against purified N-SMase from H. pylori cross-reacted with SMase from Bacillus cereus. Sera from individuals with H, pylori infection but not uninfected ones recognizing the purified N-SMase indicated that it was produced in vivo. In enzyme linked immunosorbent assays, the purified N-SMase used as an antigen was as effective as crude protein antigens in detecting human antibodies to H. pylori.