[Utilization of an enzyme-sensor in clinical medicine]

The utilization and merit of an enzyme-sensor for measuring serum- or urine-components were reported. The enzyme sensor (enzyme-electrode) is an H2O2-electrode, O2-electrode or ion selective electrode connected with an enzyme-immobilized nylon tube. First, the principle of measurements with an enzyme sensor was reported. Secondly, and H2O2 electrode which had been planned and developed in our laboratory was introduced. The outline of our apparatus and the procedure of enzyme-immobilization onto a nylon tube wall were explained. Then the results obtained from quantitative analysis of serum- and urine-components were shown. For the analysis by our apparatus, 3-60 microliters of serum or urine was used and incubation time was approximately 5 min. The results obtained by our apparatus coincided with those obtained by other methods (r = 0.981-0.997). Thirdly, the usefulness of commercial instruments with an enzyme-sensor for determining glucose- or lactic acid-content was described. The results (glucose and lactic acid-contents) measured by desktop-size instruments showed a high lineality and good reproducibility (CV = 0.6-1.5% in glucose and 0-0.7% in lactic acid). A good correlation was observed among each instrument (r = 0.999). The results by card-size instruments, GLUTEST E or ExacTech, showed a lower reproducibility (CV = 4.1-6.5%) and correlation (r = 0.95-0.98) than those by desktop-size instruments.