Hideki Koh

A radioimmunoassay of thromboxane B2 with thromboxane B2-125I-tyramide and its application to the study on the thromboxane B2 formation during platelet aggregation

Abstract A radioimmunoassay for measuring thromboxane B2 with thromboxane B2-125I-tyramide was developed. Antibody to thromboxane B2 that was produced in rabbits immunized with conjugates of thromboxane B2 coupled to bovine serum albumin had a high specificity to thromboxane B2 Thromboxane B2-125I-tyramide had a high affinity to antiplasma of thromboxane B2. This method was utilized to study thromboxane B2 formation during platelet aggregation induced by collagen, ADP and adrenalin. Formations of thromboxane B2 were observed in accordance with platelet secondary aggregation, namely, release reaction.

Exercise-Induced Increase in Glandular Kallikrein Activity in Human Plasma and its Significance in Peripheral Glucose Metabolism

Glucose uptake into skeletal muscle of human forearm at rest and during exercise is reported to be diminished by the administration of a kallikrein (kallidinogenase) inhibitor. The present study was conducted to clarify the changes of glandular kallikrein (GK) activity in human plasma during acute exercise and its significance in peripheral glucose metabolism. 10 non-diabetic inpatients, aged 49.5 years, and 8 diabetic inpatients, aged 53.8 years, were studied. After an overnight fast, bicycle ergometer exercise test was performed for 15 min (25 W (5 min)----50 W (5 min)----75 W (5 min]. Before (basal), during (at 15 min) and after exercise (at 25 min), venous blood samples were drawn to determine plasma GK activity and glucose, serum immunoreactive insulin (IRI), C-peptide immunoreactivity (CPR), nonesterified fatty acids, pyruvate, lactate, noradrenaline and adrenaline levels. In the 1st trial, in both non-diabetics (n = 10) and diabetics (n = 8), plasma GK activity increased significantly during exercise. After the 1st trial, in 6 patients (5 non-diabetics; 1 diabetic), exercise test was repeated once after 2-4 weeks and in a diabetic patient, exercise test was repeated twice at 4-week intervals, accordingly exercise test was performed 26 times in 18 patients in total. Natural logarithmic correlation between sigma glucose level and sigma GK activity (r = 0.52, n = 26), and hyperbolic correlation between sigma glucose level and sigma IRI level (r = -0.66, n = 26) but no correlation between sigma glucose level and sigma CPR level (r = 0.17, n = 26) were found.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of Atenolol on Serum β2-Microglobulin Level in Hypertensive Diabetic Patients

The effects of atenolol (50 mg once daily) on serum beta 2-microglobulin levels in 11 hypertensive diabetic patients uncomplicated by renal dysfunction were studied. Atenolol significantly decreased serum beta 2-microglobulin levels (micrograms/mL) at four weeks (1.5 +/- 0.13) and at eight weeks (1.4 +/- 0.09) from pretreatment level (1.8 +/- 0.17) (P less than 0.05, respectively), along with statistically significant antihypertensive effects. Blood urea nitrogen, serum creatinine, fasting plasma glucose, HbA1C levels, and body weight remained unchanged. The results suggest that atenolol provides a favorable effect on renal function in hypertensive diabetic patients uncomplicated by renal dysfunction.

Acute effect of low-calorie and low-carbohydrate diet on serum triiodothyronine-response to glucose ingestion and its relation to glucose tolerance.

This study was conducted to elucidate the mechanism of glucose intolerance due to carbohydrate restriction. 15 non-diabetic patients, aged 51 +/- 3 yr, were placed under dietary condition-I (2,012 kcal/day; carbohydrate 299 g) for more than 3 days after admission and then condition-I was substituted by condition-II (1,156 kcal/day; carbohydrate 139 g) for 2 weeks. At the end of condition-I and -II, 75 g OGTT was performed. After the comparison between condition-I and -II, patients were subdivided into two groups, namely, glucose tolerance-improved (n = 8) and -impaired (n = 7) groups. In the former, sigma glucose (mg/dl) during OGTT decreased from 898.1 +/- 28.0 to 738.5 +/- 36.0 (p < 0.05) and sigma IRI (microU/ml) decreased from 418.8 +/- 60.1 to 300.7 +/- 33.5 (p < 0.05) but sigma dT3 (ng/dl) increased from 11.3 +/- 14.7 to 70.3 +/- 15.1 (p < 0.05). In the latter, sigma glucose (mg/dl) increased from 774.6 +/- 46.6 to 867.1 +/- 50.1 (p < 0.05) and sigma IRI (microU/ml) increased from 323.4 +/- 47.8 to 400.8 +/- 47.8 (p < 0.05) but sigma dT3 (ng/dl) decreased from 45.3 +/- 7.1 to 20.0 +/- 14.7 although it did not reach a level of statistical significance. These results suggest that blunted serum T3-response to glucose ingestion is linked to the mechanism of glucose intolerance due to carbohydrate restriction.