Yuichiro Maeda

Glycation of cataractous lens in non-diabetic senile subjects and in diabetic patients.

Early- and advanced-stage products in the Maillard reaction, glycation, were measured in patients with diabetic or senile cataracts. Early-stage products were measured by means of furosine, which is an acid-hydrolysis product derived from fructose-lysine. Advanced-stage products were measured by fluorometry using high-performance liquid chromatography. Furosine levels were high (listed in descending order) in capsule, cortex and nucleus in both diabetic and senile cataracts. The advanced-stage products were also high (listed in descending order) in nucleus, cortex and capsule in both diabetic and senile cataracts. These results suggest that advanced-stage products might accumulate in larger amounts in the nucleus and cortex than in the capsule, resulting in the formation of cataracts. The study also revealed that the Maillard reaction plays an important role in causing not only diabetic cataracts but also senile cataracts.

Autonomic nervous function determined by changes of periflux blood flow in the aged

The periflux blood flow (PBF) in fingers was determined by a periflux laser Doppler flowmeter (PLDF). The patterns of PBF responses to standing and Valsalvas maneuver were analyzed. The PBF responses in both loading tests were well correlated with the results of the conventional autonomic function test. It was, therefore, considered that our method would be useful for assessment of autonomic function. We practically investigated PBF responses in the two loading tests in three groups: young age group (10-39 years), middle age group (40-69 years) and old age group (70-89 years). The old age group showed significant decreases in both sympathetic and parasympathetic functions. It was indicated that this non-surgical and simple autonomic function test will be useful particularly in the elderly.

Hair protein glycation as a long-term index of blood glucose in diabetics

We used furosine, which is derived from fructose-lysine and is a glycation product, to measure the extent of hair protein glycation in diabetic patients. We took hair samples that were 12 cm long, corresponding roughly to 1 years growth. While the furosine levels in these samples correlated poorly with fasting plasma glucose (FPG) and with hemoglobin A1c (HbA1c) levels at the time of sampling, better correlations were observed between glycation and the year-long average values of FPG, HbA1c, and the conduction velocities in two peripheral nerves. The glycation levels in these samples may thus reflect the year-long average of the patients blood glucose. Hair glycation may serve as a valuable indicator both of long-term blood glucose trends and of the relationship between diabetic complications and blood glucose.

Accelerated glycation of the aorta in diabetic rats.

Glycation of the aorta in rats with streptozotocin-induced diabetes was estimated by determining the early-stage product and the advanced product of the Maillard reaction. The early-stage product of the Maillard reaction was determined using furosine, which is derived from glycated lysine residues by acid hydrolysis. The advanced product was determined by fluorescence high-performance liquid chromatography. The levels of both early-stage and advanced products in diabetic rats were significantly higher than those in non-diabetic rats at the age of both 20 and 50 weeks. The levels of both early-stage and advanced products at 50 weeks in rats tended to be higher than those at 20 weeks. However, the level of glycated hemoglobin in both non-diabetic and diabetic rats showed no significant change between 20 and 50 weeks of age. These results suggest that tissue glycation may be involved in the development of diabetic complications and may be related to the aging mechanism.