Horseradish peroxidase (HRP) is generally used as a label enzyme in enzyme immunoassay (EIA).The procedure used for HRP detection in EIA is critical for sensitivity and precision.This paper describes a novel fluorimetric assay for horseradish peroxidase (HRP) using sesamol as substrate.The principle of the assay is as follow:sesamol (3,4-methylenedioxy phenol) is reacted enzymatically in the presence of hydrogen peroxide to produce dimeric sesamol.The dimer is fluorescent and can be detected sensitively at ex.347 nm,em.427 nm.The measurable range of HRP was 1.0 × 10-18 to 1.0 × 10-15 mol/assay,with a detection limit of 1.0 × 10-18 tmol/assay.The coefficient of variation (CV,n=8) was examined at each point on the standard curve,with a mean CV percentage of 3.8％.This assay system was applied to thyroid stimulating hormone (TSH) EIA using HRP as the label enzyme.

Herein, we present a case of aortic root replacement 42 years after aortic valve replacement (AVR) with the Björk-Shiley Spherical (BSS) valve in a patient with an aortic root aneurysm. The patient was a 67-year-old man who had undergone AVR with BSS and aortic root enlargement for the treatment of infective endocarditis and aortic insufficiency at 25 years of age. He underwent aortic root replacement for an enlarged aortic root (73 mm). Under general anesthesia, median re-sternotomy was performed, and the BSS valve was removed. The valve functioned well with no pannus or thrombus. We performed an aortic root replacement using a composite graft consisting of a 24-mm mechanical valve and 30-mm artificial graft. We experienced a rare case of long-term durability of the BSS valve, which functioned well for 42 years.