Narushi Ito

Development of urine glucose meter based on micro-planer amperometric biosensor and its clinical application for self-monitoring of urine glucose

The highly sensitive urine glucose meter based on amperometric glucose sensor was developed and commercialized. It shows remarkable performances of wide measurement range in 0-2000 mgdl(-1), rapid response time as 6s and robustness against influence by interferents like ascorbic acid or acetaminophen. Correlation between the developed urine glucose meter and commercialized clinical-use urine glucose analyzer showed excellent linear relationship. The monitoring of postmeal blood glucose levels by assess of urine glucose of actual subjects was performed with the developed urine glucose meter. The experimental results suggest the urine glucose level 120 min following the meal should be the appropriate index for diabetes or impaired glucose tolerance to control blood glucose level. The new portable meter was developed, and is expected for flexible use at places other than home or office.

Determination of human serum 8-hydroxy-2'-deoxyguanosine (8-OHdG) by HPLC-ECD combined with solid phase extraction (SPE)

Human serum 8-hydroxy-2-deoxyguanosine (8-OHdG) was measured by HPLC-ECD method combined with solid phase extraction (SPE) developed by our group: (our proprietary kit, named 8-OHdG Pre-treatment Kit (TANITA Corporation)). The major interfering substances and proteins in serum were removed by 8-OHdG Pre-treatment Kit. This measurement method was highly reproducible (CV=2.2-7.1%) and demonstrated the lower detection limit for control serum sample of less than 10 pg/ml without the sample evaporation. The other hand 8-OHdG concentration in serum for healthy people was in the range of 0-70 pg/ml (25.5+/-13.8 pg/ml, n=37). Secondary a relationship between the HPLC-ECD and ELISA methods was investigated. ELISA method could not detect 8-OHdG concentration in serum for healthy people, because the detection limit of 130 pg/ml was higher than the normal range for healthy people. These results show our SPE method has high sensitivity and quantitative accuracy for 8-OHdG analysis.

New noninvasive transcutaneous approach to blood glucose monitoring: successful glucose monitoring on human 75 g OGTT with novel sampling chamber

A novel noninvasive and quasi-continuous method of transcutaneous blood glucose monitoring for use with the human 75-g oral glucose tolerance test (OGTT) was developed. Effused fluid was obtained by applying suction to the skin surface and was labeled suction effusion fluid (SEF). The system consists of a suction apparatus and the glucose sensor system. A vacuum is applied to the patients skin at 400 mmHg absolute pressure to collect the SEF. The miniature ion sensitive field effect transistor (IS-FET)-based glucose sensor can measure glucose in small SEF quantities. The monitoring system is based on the association between the glucose concentration in the SEF and in the serum. During the 75 g OGTT, the glucose change in the SEF was measured every 10 min. Although a response delay of up to 20 min was observed in the SEF glucose change, it was possible to perform the 75 g OGTT by this noninvasive monitoring method.<<ETX>>

Transcutaneous biochemical substance monitoring based on biosensors-blood glucose and lactate

New transcutaneous monitoring methods for biochemical substances such as blood glucose and lactate have been developed by using a suction effusion fluid (SEF) collecting technique with an ion-sensitive field-effect transistor for blood glucose, and with a micro-planar amperometric biosensor for lactate respectively. Firstly, blood glucose change during the 75-g oral glucose tolerance test (OGTT) was monitored by suction effusion fluid (SEF) sampling in 5 patients with type II diabetes. Secondly, the authors have also developed a micro planar biosensor for determining lactate concentration in very small sample. The biosensor utilizes a lactate oxidase immobilized membrane on a micro planar platinum electrode to yield a lactate sensor. Both glucose and lactate concentrations measured with SEF showed good correlation with those obtained directly from whole blood.

Transcutaneous Measurement Of Bio-substances By Suction Effusion Fluid From Skin TT

Successful transcutaneous blood glucose monitoring on human subjects has been achieved. Effusion fluid is collected from the skin using a recently developed suction apparatus, and glucose concentration in the fluid is measured. During a 75-g oral glucose tolerance test on normal subjects, frequent transcutaneous monitoring of blood glucose change was achieved with an improved ion-sensitive field effect transistor glucose sensor which can measure glucose concentration in only 5- mu l samples. >