Ultrasonic assessment of calcaneus in inhabitants in a cadmium-polluted area.

We used ultrasound (US) transmission to evaluate the speed of sound (SOS) and broadband ultrasonic attenuation (BUA) in the calcaneus in 17 male and 18 female inhabitants of a Cd-polluted area and 23 men and 45 women living in a nonpolluted area. Significant decreases in SOS and stiffness (Stiff), which was an index empirically derived from SOS and BUA, were found in Cd-exposed women. To evaluate the usefulness of the US measurements for detecting bone abnormality in Cd-exposed people, we examined the associations with the bone measurements of metacarpus by the previously used microdensitometry (MD) method and the grade of renal tubular damage due to Cd exposure. Bone density estimated by MD, sigmaGS/D, was significantly correlated with BUA, SOS, and Stiff in the Cd-exposed men and with BUA and Stiff in the Cd-exposed women. Further, in the Cd-exposed women, the decreases in BUA and Stiff correlated significantly with the increases in urinary beta 2-microglobulin, while sigmaGS/D by the MD method did not. These results suggest that the measurement of the calcaneus using US is not only radiation free but also can be used as a tool for population surveys aiming to evaluate bone damage in people, especially women, showing renal tubular damage due to environmental Cd exposure.

Histomorphometric study of ribs with looser zones in Itai-itai disease.

Twelve Looser zones and 17 healing bands of the ribs obtained from autopsy cases of Itai-itai disease were analyzed by bone histomorphometry. Furthermore, proper cancellous tissue of the ribs from 24 autopsy cases of Itai-itai disease with Looser zones or with the healing bands, 27 autopsy cases of Itai-itai disease without such lesions, and 29 control cases were studied by the same method to pursue the histogenesis of Looser zones. In translucent zones of Looser zones, 94% of the cancellous bone was occupied by thick woven bone in which 72% was woven osteoid and 22% was woven mineralized bone. In adjacent scleroses, 71% of the cancellous bone was occupied by woven bone in which 37% was woven mineralized bone, and 34% was woven osteoid; 53% of the cancellous bone consisted of mineralized bone. As compared with those in translucent zones, woven osteoid was decreased, and mineralized bone was increased significantly in the cancellous bone of adjacent scleroses. A significant increase of lamellar mineralized bone and a decrease of woven bone in healing bands were observed as compared with those in Looser zones. These findings suggest that the healing starts from the edge of the Looser zone, and slowly proceeds toward the center. In the cancellous bone of the ribs, the volume, thickness, and surface of osteoid and woven bone were significantly increased in patients with Itai-itai disease, with Looser zones as compared with those without Looser zones. It was concluded that Looser zones seem to occur in severe osteomalacic bones that contain abundant woven bone in the patients of Itai-itai disease.

Effect of cadmium in the zinc deficient rat.

Three-w-old male Sprague-Dawley rats were given a zinc (Zn)-deficient (0 ppm Zn) or a Zn-adequate diet (30 ppm Zn) supplemented with 0, 0.5 or 100 ppm cadmium (Cd) for up to 5 mo. The proximal convoluted tubules of the kidneys had degenerative changes in the rats fed the Zn-deficient diet containing 100 ppm Cd [Zn 0, Cd 100], but there were no lesions in other groups. Electron microscopy showed cytoplasmic vacuolation of the proximal tubules, mitochondrial swelling and coagulative necrosis in Zn 0:Cd 100 rats. The present study revealed diminished bone growth and cortical thinning of the femur, but there was no osteomalacia seen in Itai-Itai disease patients. The results indicate that Zn deficiency may enhance the renal toxicity of Cd, but that dietary Cd did not cause osteomalacia even under severe Zn-deficient conditions.