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Biomedical subjects

Kazushi Shinozaki

Publications and source records attributed to Kazushi Shinozaki.

3 recordsLinked to original sources

Changes in carotid atherosclerosis patterns detected by ultrasonography in Japanese elderly patients with aortic aneurysm.

To clarify current changes in the patterns of carotid atherosclerosis in Japan, carotid ultrasonographic findings in Japanese male patients with aortic aneurysm were compared between two groups examined in different periods. The first group was recruited from 42 consecutively examined patients in 1997, while the second group consisted of 40 consecutive patients from September, 2001 to January, 2002. Carotid lesions were analyzed by computer, and classified into three types based on the texture: echolucent, hyperechoic, and heterogeneous types. The mean age of the first group was 72 years, similar to that of the second group. In the first group, cigarette smoking was frequently noted, while the mean BMI was greater and IHD and CVD were frequent in the second group. Fifty carotid lesions were seen in each group. Severe stenosis and hypoechoic type lesions were more frequent in the second group than in the first group. These findings indicated that hypoechoic-type lesions, which are considered to be lipid deposition, hemorrhage, or loose fibrous tissue, and severe stenosis, were increased in the more recent group. This predicted that circulatory disturbance due to unstable atherosclerotic lesions may increase in the future among the elderly because carotid lesions reflect vascular change in other organs.

Age Factors↗

Abnormal incorporation and utilization of alpha-tocopherol in erythrocyte membranes of streptozotocin-induced diabetic rats.

Alpha-tocopherol is a well-known lipophilic-free radical scavenger that is mainly localized in biomembranes. In this study, we investigated the changes in the incorporation and utilization of alpha-tocopherol in erythrocyte membranes of streptozotocin-induced diabetic rats and the effects of insulin to control hyperglycemia on these changes. Diabetes was experimentally induced by the injection of streptozotocin (60 mg/kg, i.v.). Blood was collected to determine the concentrations of alpha-tocopherol and its oxidative metabolite (alpha-tocopherolquinone) in plasma or erythrocyte membranes after streptozotocin injection. In streptozotocin-induced diabetic rats, alpha-tocopherol concentrations were decreased in erythrocyte membranes and increased in plasma. The ratio of alpha-tocopherol in erythrocyte membranes to that in plasma, which reflects the incorporation of alpha-tocopherol into erythrocyte membranes, was dramatically decreased in streptozotocin-induced diabetic rats. Moreover, the ratio of alpha-tocopherolquinone to alpha-tocopherol in erythrocyte membranes, which reflects the utilization of alpha-tocopherol, was increased in streptozotocin-induced diabetic rats. These changes were prevented by insulin to control hyperglycemia. These findings suggest that the abnormalities in the incorporation and utilization of alpha-tocopherol in erythrocyte membranes of streptozotocin-induced diabetes can be restored to normal by insulin therapy to control hyperglycemia.

Animals↗

[Relationship between aging and vitamin E].

We investigated the pathophysiological significance in biomembranes of the redox dynamics of Vitamin E (alpha-tocopherol) which is lipophilic radical scavenger related to aging or pathologic status such as non-insulin-dependent diabetes mellitus or primary hyperlipidemia. Vitamin E eliminates lipid peroxyl radicals by the peroxidation chain reaction of the membrane lipid, and it becomes Vitamin E radical. Furthermore, the Vitamin E radical becomes Vitamin E quinone which is an oxidic metabolite of Vitamin E. Therefore, it was needed to determine the alpha-tocopherol and alpha-tocopherolquinone simultaneously to evaluate the antioxidative status of alpha-tocopherol in biomembranes exactly. For this purpose, we developed the assay method for the simultaneous determination of the two substances using HPLC system. Then we applied this method to basic and clinical research. 1) For the simultaneous determination of alpha-tocopherol and alpha-tocopherolquinone, highly-sensitive measurement system by HPLC-multiple coulometric ECD was developed. This system is useful to estimate the redox dynamics of alpha-tocopherol in biomembranes. 2) The utilization rate of alpha-tocopherol in the erythrocyte membrane of 10- to 120-week-old rats was significantly increased, whereas alpha-tocopherol uptake in the erythrocyte membrane decreased age-dependently. Furthermore, a significant increase in lipid hydroperoxide content and a marked decrease in the fluidity of the erythrocyte membrane were seen with age. 3) There was a strongly significant positive correlation between age and the utilization rate of alpha-tocopherol in the erythrocyte membrane of healthy volunteers aged between 23 and 103. 4) The alpha-tocopherol uptake in erythrocyte membrane was significantly lower in elderly non-insulin-dependent diabetes mellitus patients (average 68.1 years old) than in healthy subjects (average 71.8 years old). 5) The utilization rate of alpha-tocopherol in erythrocyte membrane and the alpha-tocopherol uptake in erythrocyte membrane were significant lower in elderly patients with primary hyperlipidemia (average 74.1 years old) compared to healthy subjects (average 71.2 years old). These findings suggest that the redox dynamics of alpha-tocopherol in biomembranes should be investigated with special regard to the onset, aggravation and complications of several diseases or aging as a result of oxidative stress. In addition redox dynamics were suggested to be useful to evaluate the grade of aging.

Aged↗