Browsing by Author "Lai, Shiau-Ting"

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Haemoglobin-induced oxidative stress is associated with both endogenous peroxidase activity and H(2)O(2) generation from polyunsaturated fatty acids
(2011-03-01)
Cheng, Tsai-Mu
;
Mao, Simon J. T.
;
Lai, Shiau-Ting
;
Chang, Chia-Ching
;
Yang, Ming-Chi
Patients with increased haemolytic haemoglobin (Hb) have 10-20-times greater incidence of cardiovascular mortality. The objective of this study was to evaluate the role of Hb peroxidase activity in LDL oxidation. The role of Hb in lipid peroxidation, H(2)O(2) generation and intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) was assessed using NaN(3), a peroxidase inhibitor, catalase, a H(2)O(2) decomposing enzyme and human umbilical vein endothelial cells (HUVECs), respectively. Hb induced H(2)O(2) production by reacting with LDL, linoleate and cell membrane lipid extracts. Hb-induced LDL oxidation was inhibited by NaN(3) and catalase. Furthermore, Hb stimulated ICAM-1 and VCAM-1 expression, which was inhibited by the antioxidant, probucol. Thus, the present study suggests that the peroxidase activity of Hb produces atherogenic, oxidized LDL and oxidized polyunsaturated fatty acids (PUFAs) in the cell membrane and reactive oxygen species (ROS) formation mediated Hb-induced ICAM-1 and VCAM-1 expression.
Haemoglobin-induced oxidative stress is associated with both endogenous peroxidase activity and H2O2 generation from polyunsaturated fatty acids
(2011-03-01)
Cheng, Tsai-Mu
;
Mao, Simon J. T.
;
Lai, Shiau-Ting
;
Chang, Chia-Ching
;
Yang, Ming-Chi
Patients with increased haemolytic haemoglobin (Hb) have 10-20-times greater incidence of cardiovascular mortality. The objective of this study was to evaluate the role of Hb peroxidase activity in LDL oxidation. The role of Hb in lipid peroxidation, H2O2 generation and intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) was assessed using NaN3, a peroxidase inhibitor, catalase, a H2O2 decomposing enzyme and human umbilical vein endothelial cells (HUVECs), respectively. Hb induced H2O2 production by reacting with LDL, linoleate and cell membrane lipid extracts. Hb-induced LDL oxidation was inhibited by NaN3 and catalase. Furthermore, Hb stimulated ICAM-1 and VCAM-1 expression, which was inhibited by the antioxidant, probucol. Thus, the present study suggests that the peroxidase activity of Hb produces atherogenic, oxidized LDL and oxidized polyunsaturated fatty acids (PUFAs) in the cell membrane and reactive oxygen species (ROS) formation mediated Hb-induced ICAM-1 and VCAM-1 expression.
Haptoglobin phenotypes and plasma haptoglobin levels in patients with abdominal aortic aneurysm
(2011-05-01)
Pan, Ju-Pin
;
Cheng, Tsai-Mu
;
Shih, Chun-Che
;
Chiang, Shu-Chiung
;
Chou, Shiu-Chin
Objective: Inflammation is associated with the disruption of the aortic media and appears to play a fundamental role in the progression and development of abdominal aortic aneurysm (AAA). Haptoglobin (Hp) is a genetically determined acute phase protein, the synthesis of which is increased during inflammation. This study was designed to investigate both phenotype and plasma levels of Hp in patients with AAA. Methods: Patients with documented AAA who were admitted for elective open repair operation or endograft stem implantation, and non-AAA subjects admitted for coronary arteriography, but found to have normal or insignificant coronary artery disease, were included in the study. Plasma Hp levels were determined using a standard specific enzyme-linked immunosorbent assay, while Hp phenotype was determined by native polyacrylamide gel electrophoresis. Total cholesterol, high density lipoprotein, low density lipoprotein, and triglyceride levels were analyzed enzymatically, and C-reactive protein was analyzed by immunochemistry. Results: Forty-five patients with AAA and 49 non-AAA subjects were included. The Hp 2-2 phenotype was more predominant in AAA patients compared with non-AAA subjects, but this difference was not significant (67% vs 47%; P = .141), while plasma Hp concentrations were significantly higher in AAA patients (237 +/- 144 vs 163 +/- 86 ng/mL; P = .024). Further analysis revealed that plasma Hp concentrations were significantly higher in AAA patients with the 2-2 phenotype compared with corresponding non-AAA subjects (238 +/- 144 vs 163 +/- 86 ng/mL;P = .024). Conclusions: Our findings suggest that plasma Hp concentrations are elevated in patients with AAA, particularly those with the Hp 2-2 phenotype. (J Vasc Surg 2011;53:1189-94.)
Immunochemical property of human haptoglobin phenotypes: Determination of plasma haptoglobin using type-matched standards
(2007-09-01)
Cheng, Tsai-Mu
;
Pan, Ju-Pin
;
Lai, Shiau-Ting
;
Kao, Li-Pin
;
Lin, Hong-Huel
Objectives: Haptoglobin (Hp) phenotypes 1-1, 2-1, and 2-2 are associated with inflammatory diseases. Since their biochemical structures are rather heterogeneous, it is necessary to accurately determine the plasma Hp levels. Design and methods: Immunodiffusion, immunoturbidimetric, and noncompetitive ELISA were conducted to determine the differences in immunoreactivity among Hp phenotypes and to verify that such difference may significantly affect the outcome of Hp determinations. A novel ELISA using phenotype-matched calibrators was performed to compared with a commercial GenWay ELISA kit using a single calibrator in normal healthy males. Results: In immunodiffusion and immunoturbidimetric assays, the immumoreactivity of Hp 1-1 was markedly higher than 2-1 and 2-2, while an opposite result was observed using an ELISA. The latter was primarily due to the repeated antigenic epitopes in polymeric 2-1 and 2-2. Thus, Hp levels could be significantly over- or underestimated depending on the method. An accurate ELISA could be achieved when using each type-specific Hp calibrator matched to each type subject. We show the mean levels of Hp 1-1 subjects (n= 16; 184 +/- 42 mg/dL) to be significantly and differentially greater than 2-1 (n=28; 153 +/- 55 mg/dL) (p < 0.05) and 2-2 (n=24; 93 +/- 54 mg/dL) (p < 0.01) subjects. Conclusions: Due to the diverse immunochemical structure among the Hp types, phenotyping should be performed in all the patients and a type-matched Hp calibrator should be used in clinical Hp determination. (c) 2007 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.