Bone and mineral最新文献

The changes of bone mineral density (BMD) and skeletal muscles were evaluated in the rat model at either sham or ovariectomized stages to attempt to make clear the effect of voluntary running exercise on bone metabolism. In comparison with the control groups within the ovariectomized (OVX) and the sham groups, in the running groups, (1) the urinary phosphorus (P) and creatinine (Cr) excretions showed an increase concurrently with the increase in the running distance; (2) the weight of the quadriceps femoris was significantly higher; and (3) the BMD of appendicular and axial bones was significantly greater. These results suggest that voluntary running exercise could effect the BMD, the weight of the skeletal muscles, and the acceleration of energy metabolism.

Growth plate cartilage calcification has been examined in a recently described mouse mutant, tich, which is co-isogenic with the A.TL strain. Long bones were studied from 1-day-old and 1-month-old mice which carried a homozygous recessive gene mutation making them short limbed and dumpy. Specimens were studied by routine histology, scanning electron microscopy and radiography. In 1-day-old tich mice the front of calcified cartilage was recessed behind the advancing periosteum and bone. No similar recess was seen in control mice. At 1 month of age, a number of the long bone growth plates were irregularly thickened, particularly in the central area. This produced a central tongue of non-calcified cartilage (particularly prominent in the proximal tibia) which gave rise to a corresponding pit in the calcified cartilage layer, in macerated specimens. This was accompanied by poor resorption of calcified cartilage. At both ages the presence of the respective defects was radiographically confirmed. At present it is not known whether this is primarily a defect of calcification or resorption but its presence, apparently from a single mutation in a genetically defined mouse strain, makes it a potentially valuable model.

Studies of hypocalcemia and osteoporosis frequently encountered in heavy users of alcohol have previously been performed on alcoholic people who have already recovered from alcohol intoxication. Bone and mineral metabolism during and after the intoxication may be different. We measured serum parameters of bone and mineral metabolism in 26 alcohol-intoxicated men and in 19 healthy control men. Although serum ionized calcium was 12% (P < 0.0001) lower in the patients than in the controls, serum intact parathyroid hormone was similar in the study groups. As reflected by decreased serum levels of osteocalcin (−43%; P < 0.001), bone formation was depressed in the patients. Serum cross-linked carboxyterminal telopeptide of human type I collagen (ICTP), a novel parameter of bone matrix degradation, was 9% higher in the patients (P = 0.03) than controls. The positive correlation between serum osteocalcin and ICTP in the controls (r = 0.59, P < 0.01) was absent in the patients (r = 0.05, P = 0.8). We conclude that in alcohol-intoxicated alcohol users, the parathyroid glands do not respond normally to a hypocalcemic stimulus, and that depressed bone formation is uncoupled from accelerated bone resorption.

The present study was performed to measure appendicular bone mass of Japanese infants and children, and to assess the influence of age, sex and body size on bone mass during the period of bone growth. The bone mineral content (BMC) and bone width (BW) at the distal third of the radius were measured by single photon absorptiometry (SPA) in 229 healthy Japanese infants and children aged 0–12 years, and the BMC/BW ratio was calculated to give the bone mineral density (BMD). BMC and BW increased with age until 2 years, while BMD did not obviously change until 2 years. After 2 years of age, the overall effect of aging appeared more prominent in BMC and BMD than in BW. There were no significant differences in BMC, BW and BMD between males and females aged 0–12 years. Age, body height, and body weight were strongly correlated with three parameters of bone mass (BMC, BW, and BMD). Among the three parameters of bone mass, BMC showed the highest Pearson coefficient of correlation with age (r = 0.955), body height (r = 0.957) and body weight (r = 0.966), as compared with BW and BMD. The present cross-sectional study provides normative data of the appendicular bone mass in healthy Japanese children, which may serve as a standard for assessment of bone mineralization in Japanese infants and children with medical problems.

SAMP6 is a recently developed strain of osteoporotic mice, and SAMP2 is a control for SAMP6 and has a higher peak bone mass. The bone mass of SAMP6 was increased until 2 months of age when a lysate of cells derived from the bone marrow of SAMP2 was injected at 1 or 4 days of age, but it was not increased when the lysate was injected at 21 days of age. No effect on bone mass was observed when lysates of other cells, bovine serum albumin or heat-inactivated lysate of bone marrow-derived cells of SAMP2, were injected. The ability to increase bone mass was not in the supernatant but in the pellet obtained by ultracentrifugation (105 000 g) of the lysate of bone marrow-derived cells of SAMP2. The lysate did not change the osteoclast surface but changed the appositional bone formation. In conclusion, the lysate of cells derived from the bone marrow of SAMP2 contains factors which can increase the bone mass of SAMP6, and these factors are present in the pellet obtained by ultracentrifugation.

The effects of 3,9-bis(N,N-dimethylcarbamoyloxy)-5H-benzofuro[3,2-c]quinoline-6-one (KCA-098), a derivative of coumestrol, on bone resorption was studied in organ cultures of 20-day fetal rat femora. KCA-098 increased the length, dry weight, and calcium and phosphorus contents of parathyroid hormone (PTH)-treated fetal rat femur. As PTH significantly reduced the calcium and phosphorus contents of the femora, probably by stimulating bone resorption, KCA-098 seems to inhibit bone resorption. In fact, KCA-098 inhibited the PTH-induced release of ⁴⁵Ca from pre-labeled fetal rat femora into the medium in organ culture. Coumestrol also inhibited the release of ⁴⁵Ca from bone into the medium. However, KCA-098 did not increase the uterine weight of ovariectomized rats, whereas coumestrol did so. Thus KCA-098 is a unique, new inhibitor of bone resorption that has no estrogenic activity.

To evaluate the effect of 17β-estradiol replacement (10 μg, twice a week) (E₂) and treadmill exercise (18 m/min, 45 min/day) (EX) on long bone and vertebral bone mass and density, 10-month-old rats were ovariectomized (OV) and divided into four groups: OV, OV + E₂, OV + EX, OV + EX + E₂ 2 months after surgery. After 7 weeks intervention, the calcium content and the density of lumbar-5 were higher in both OV + E₂ and OV + EX + E₂ groups than in the OV group, but, only the OV + EX + E₂ group had a significantly higher femoral bone weight and density than the OV group. After 16 weeks intervention, the bone-conserving effects of E₂ and EX were significant on lumbar-5 and femoral dry weight and density. The effect of E₂ on both two sides of bones was due to the suppression of the bone turnover rate, while EX suppressed bone turnover rate primarily on the femur. We conclude that the effect of the two interventions on lumbar-5 and femoral bone mass were additive and independent.