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Biomedical subjects

W C Yu

Publications and source records attributed to W C Yu.

113 records · Page 7Linked to original sources
PubMedDate not supplied

Measurement of plasma concentrations of vasodilators and metabolites by the TEA Analyzer.

The determination of therapeutic levels of glyceryl trinitrate (GTN), isosorbide dinitrate (ISDN), pentaerythritol tetranitrate (PETN), and their metabolites in human plasma was conducted using the TEA Analyzer interfaced to a high-performance liquid chromatograph (HPLC-TEA). Chromatographic separation of these compounds was accomplished under isocratic HPLC conditions. The sensitivity of the instrument was established to be 0.1 ng for each of the three nitrate esters. At the 5 ng ml-1 plasma fortification level, the precision of the method gives mean relative standard deviations (RSD) of +/- 10.2 per cent, +/- 6.5 per cent, and +/- 5.9 per cent for GTN, ISDN, and PETN, respectively. The recoveries for the nitrate esters and their metabolites from human plasma over the range 1-50 ng ml-1 are presented. The specific and sensitive HPLC-TEA method developed in this study provides a reliable and rapid assay for the routine analysis for metabolism or bioavailability studies of nitrate esters and their metabolites in plasma of blood, with a detection limit as low as 1 ng ml-1.

Chromatography, High Pressure Liquid↗
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Clinical and electrophysiological characteristics in children with atrioventricular nodal reentrant tachycardia.

Atrioventricular (AV) nodal reentrant tachycardia is one of the most common supraventricular tachycardias in childhood. However, information about AV nodal reentrant tachycardia in childhood is limited, especially about the variant and multiple forms. The purpose of this retrospective study was to investigate the clinical and electrophysiological characteristics in pediatric patients with AV nodal reentrant tachycardia. Forty-eight pediatric patients with AV nodal reentrant tachycardia were included (ages 11-18 years; 25 males and 23 females). The age of onset and duration of symptoms were significantly younger and shorter in pediatric patients, respectively. A higher incidence of antegrade dual AV nodal pathways was found in adult patients than pediatric patients (72.9 vs 52.1% p = 0.003). Both antegrade and retrograde slow pathway functions were better in pediatric than adult patients. There was no significant difference between children and adults in the occurrence of variant and multiple forms of AV nodal reentrant tachycardia. This study demonstrated that pediatric patients have different electrophysiologic characteristics from those of adult patients.

Abnormalities, Multiple↗
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T lymphocyte function in patients with malignant biliary obstruction.

The T lymphocyte function in 59 patients with malignant biliary obstruction undergoing pre-operative endoscopic drainage (group Ia, n = 24) or surgery (group Ib, n = 35) was evaluated by mitogen stimulation test with phytohaemagglutinin. The T lymphocyte function before endoscopic or surgical intervention was found to be impaired as compared with patients with gastric cancer (group II, n = 27) and with normal persons (group III, n = 19). Regression analysis showed a significant negative correlation between T lymphocyte function and the serum bilirubin level (correlation coefficient -0.3, P = 0.01) and a positive correlation with serum albumin level (correlation coefficient 0.34, P = 0.01) and serum transferrin level (correlation coefficient 0.45, P = 0.001). After 18 +/- 3 days of endoscopic biliary drainage, the T lymphocyte function of group Ia patients did not change substantially. At postoperative day 14, there were more patients in both groups Ia and Ib having deterioration of T lymphocyte function than those with improvement. The incidence of postoperative sepsis was found to be significantly higher in patients with deterioration than those with improvement of T lymphocyte function (18/31 vs 7/26, P = 0.036). It is concluded that endoscopic biliary drainage and surgery could not reverse the T lymphocyte dysfunction in patients with malignant biliary obstruction.

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