高橋 香代

The tubular basement membrane (TBM) (i.e. tubular basal lamina) of rat kidney was shown to be a fine meshwork by electron microscopy after negative staining. Strands of the meshwork formed a regular three dimensional lattice work. The pores of the meshwork were polygonal. There were two main pore sizes: one approximately 30 A in diameter, the other 42--60 A. In view of our previous observation that glomerular and alveolar basement membranes were made up fine meshwork, it is quite possible that the basement membranes of other organs are also made up such fine meshwork.

A 26-year-old female with Bartter's syndrome associated with Graves' disease is reported. This patient had a history of Graves' disease from the age of 22 and anti-thyroid drug (Methimazole) had been administered for 2 years. Thyroid function returned to normal but general fatigue and polyuria continued. Hypokalemia was diagnosed at 25 years of age and she was referred to our hospital for evaluation. Blood pressure was normal and laboratory data revealed normal thyroid function, hypokalemic alkalosis, high plasma renin activity and high plasma aldosterone concentration. She showed normal pressor sensitivity to norepinephrine infusion, grossly diminished pressor sensitivity to exogenous angiotensin II infusion compared with the normal. A renal biopsy specimen showed juxtaglomerular cell hyperplasia. Electron microscopy confirmed lacis cell (agranular cell) proliferation.

Rat kidney glomerular basement membrane (GBM) was isolated and digested with alpha-amylase and elastase. Electron microscopy revealed a meshwork structure composed of fibrils 3 nm in width. They appeared to be type IV collagen fibrils. We succeeded in clarifying a significant ultrastructural aspect of the GBM which had been unclear until now. The findings are consistent with our previously proposed GBM molecular sieve theory.

The morbidity of diabetes mellitus is increasing gradually in Japanese populations. It is important to clarify the risk factors of diabetes in Japanese populations in order to take adequate measures against the increasing morbidity of diabetes. In order to evaluate the link between past and concurrent obesity and diabetes in middle-aged Japanese men, we conducted a worksite-based historical cohort study in Okayama, Japan in 1999. Annual health examination data of middle-aged male workers in a worksite were collected. The relative risks of past and concurrent obesity for developing diabetes were calculated. Subjects with a past history of obesity at between 40 and 50 years of age had a significantly higher risk of developing diabetes by age 55 than did subjects in the normal weight group. These results suggest that, in order to prevent diabetes in middle-aged Japanese men, health guidance for normal weight maintenance should be provided not only for middle-aged men, but also for men under age 40.

With the electron microscopic and the negative staining method, the glomerular basement membrane of human and bovine kidneys was shown to have a definite fine meshwork structure. The pores of the meshwork of bovine glomerular basement membrane appeared to be pentagonal or hexagonal in shape. Strands of the meshwork branched three-dimensionally and made up the whole basement membrane. The portion of the sgrand between two neighboring branches was presumed to be a structural unit of the basement membrane. Glomerular basement membrane in man showed a structure similar to that seen in cattle, although the pore size of the meshwork was smaller in man than in cattle.

This study assessed total and segmental distribution of fat mass (FM) in athletes with spinal cord injury (SCI) and examined the relationships between segmental distribution of fat mass and age, injury level, athletic history, and training load in order to provide useful information for improvements in their physical strength and training. Twenty-five male athletes with SCI participated in the study. The whole bone composition was measured by a dual-energy X-ray absorptiometry (DXA) method for the calculation of bone minerals, FM, and fat-free mass. The percent fat of the trunk, arms, and legs was also calculated. The percent fat in the legs was highest in comparison with that in the trunk and arms (p < 0.001), and the percent fat in the trunk was higher than that in the arms (p < 0.001). The body fat (p < 0.01), waist circumference (p < 0.01), and waist-to-hip ratio (p < 0.0001) were higher in the group aged 40 or older in comparison with that aged 39 or younger. Path analysis revealed that training load was a factor decreasing the percent fat on the arms and trunk (p < 0.01), and athletic history was a factor reducing the percent fat on the arms (p < 0.05). Our study suggests that exercise is effective in reducing the waist circumference, waist-to-hip ratio, and percent body fat of SCI individuals, and that such effects can help to enhance athletic performance and likely to protect against development of metabolic syndromes resulting from a sedentary lifestyle.