Cobi Lidor

Decrease in bone levels of 1,25-dihydroxyvitamin D in women with subcapital fracture of the femur

SummaryIn a previous study we were able to show that in women over the age of 45 the level of 1,25-dihydroxyvitamin D (1,25(OH)2D) in bone, but not in serum, is significantly reduced when compared with younger women. In the present study we measured the concentration of 1,25(OH)2D in sera and bones of 19 female patients with subcapital fractures of the femur, mean age 78±2 years. We were able to show that serum levels of 1,25(OH)2D were within the normal range, while bone levels were markedly reduced compared to levels in femoral bone obtained from young female cadavers or to the previously reported levels in non-osteoporotic elderly women. Thus, reduced levels of 1,25(OH)2D in bones of elderly women may lead, together with other factors, to subcapital fractures.

Parosteal lipoma of the proximal radius: A report of five cases

Parosteal lipoma of the proximal radius is a benign, slow-growing tumor. It may cause compression of either the posterior interosseous or the superficial branch of the radial nerve. Surgical excision usually leads to complete recovery. Five cases of parosteal lipoma of the proximal radius are presented. X-ray films demonstrated a radiolucent mass in contact with the radius. Two patients had signs of posterior interosseous nerve compression, and two showed signs of superficial radial nerve compression. In one case the lipoma surrounded an exostosis arising from the proximal radius. The tumors were excised in four patients. The three patients with neurologic involvement recovered fully. One patient refused surgery, and posterior interosseous nerve paralysis developed.

Levels of active metabolites of vitamin D3 in the callus of fracture repair in chicks.

The levels of the active metabolites of vitamin D were measured in the callus and in the epiphyseal growth plate of chicks given radioactive cholecalciferol during fracture healing. Those levels were correlated with the histological findings. Three groups of chicks were studied: a control group with no fracture, chicks with fractures fixed by Kirschner wire, and chicks with unfixed fractures. A significant increase in the levels of the active metabolites was found in the callus during the first few days after fracture. The levels of 25-hydroxycholecalciferol [25(OH)D3] and of 24,25-dihydroxycholecalciferol [24,25(OH)2D3] were higher when there was no fixation, while those of 1,25-dihydroxycholecalciferol [1,25(OH)2D3] were higher after fixation. The concentrations of these metabolites in the proximal epiphysis of the tibia were similar to those found in the callus. Based on these findings it is suggested that the active metabolites of vitamin D are directly involved in the process of fracture repair.

Biochemical and biomechanical properties of avian callus after local administration of dihydroxylated vitamin D metabolites

In vitamin D-fed chicks 1,25-dihydroxyvitamin D3 and 24,25-dihydroxyvitamin D3 were implanted into experimentally-produced fractures of the mid-tibia. The mechanical and biochemical properties of the tibia were evaluated for two weeks, including torsion tests, measurement of alkaline phosphatase activity, 45Ca incorporation, and Ca2+ content. Both dihydroxylated metabolites of vitamin D3 had a direct effect on endochondral bone formation. 24,25(OH)2D3 strengthened the callus, and raised alkaline phosphate activity in the first seven days after fracture. 1,25(OH)2D3 decreased the strength of the callus concomitant with a reduction in 45Ca incorporation. It is suggested that local application of 24,25(OH)2D3 into fractures may accelerate healing and prevent non-union.

Influence of 1,25-hydroxyvitamin D3 on cytosolic free calcium concentrations

Using isolated cartilage cells from the epiphyseal growth plate of rachitic chicks and utilizing the fluorescence indicator quin2 for measurements of cytosolic free calcium, it has been possible to demonstrate that 1,25-dihydroxyvitamin D3 regulates the concentrations of cytosolic free calcium. The reduction in cytosolic free calcium is associated with inhibition of the activity of alkaline phosphatase. As several hours are required before an effect on cytosolic free calcium can be observed in the cells, it is suggested that the action is dependent on genomic interactions.

Successful High-Dose Calcium Treatment of Aluminum-Induced Metabolic Bone Disease in Long-Term Home Parenteral Nutrition

A patient who developed severe metabolic bone disease is presented. He had received long-term home parenteral nutrition (HPN) following extensive small bowel resection after mesenteric vein thrombosis. Bone disease caused by aluminum intoxication had components of osteomalacia and low-turnover osteoporosis. Aluminum was detected at the surface of mineralized bone and was elevated in the serum, resulting in a positive deferoxamine infusion test. One year of treatment with high doses of calcium (up to 24 mEq per day) significantly diminished the patients bone pain, increased the serum levels of calcium, abolished aluminum deposits in the mineralized trabecula, improved bone formation, and increased trabecular bone volume as assessed by repeated histomorphometric analysis.

Decrease in bone level of 1,25-dihydroxyvitamin D in women over 45 years old

SummaryThe most active metabolite of vitamin D is 1,25-dihydroxyvitamin D [1,25(OH)2D]. Its level in the bone may play a role in the pathogenesis of metabolic bone diseases such as osteoporosis. To assess this, and to see whether there is correlation between serum and bone levels, we studed serum and bone samples taken from 43 patients (18 men and 25 women) undergoing different orthopedic procedures. Patients were studied according to sex and age groups (<45 years, 46–60 years, >61 years). Serum level of 1,25(OH)2D was found to be 29.7±2.61 pg/ml (mean±SEM) for women, 32.2±3.86 pg/ml for men, and 30.7±2.18 pg/ml for the group as a whole. No significant statistical differences were found among age subgroups in either sex or between sexes. Bone level of 1,25(OH)2D was found to be 31.5±4.46 pg/g for women, 26.5±3.06 pg/g for men, and 29.4±2.81 pg/g for the entire group. No significant statistical difference was found between the age subgroups for men. However, the level of 1,25(OH)2D was found to be higher in the group of younger women (<45 years) compared with the older women (46–60 years and >61 years) (P<0.005).

Proteoglycan synthesis in vitamin D-deficient cartilage: recovery from vitamin D deficiency.

Vitamin D appears to be required for mineralization of skeletal elements. There is also evidence that cartilage proteoglycans may be involved in the regulation of mineralization. Previous studies have shown an alteration in the structure of the proteoglycans of the epiphyseal growth cartilage as a result of the decrease in serum calcium related to deficiency of dietary vitamin D. Vitamin D deficiency also induces a thickening of the epiphyseal growth plate presumably because of the inhibition of maturation of the growth plate chondrocytes. In order to compare the effect on proteoglycan structure with that on growth plate morphology, the proteoglycans of healing epiphyseal cartilage were characterized. The results indicate that, consistent with previous data, in vitamin D-deficient hatching chicks, the proteoglycans of the growth cartilage, but not of the articular cartilage, are smaller in monomer size with slightly smaller chondroitin sulfate chains whose sulfation pattern is unaltered. Sternal cartilage proteoglycans are unaffected. During recovery from vitamin D deficiency, the proteoglycans isolated from the growth cartilage are still not completely normal one day after supplementation with vitamin D, but are indistinguishable from normal by four days. In addition, the results conflict with those of a previous study in which only growth cartilage of hatchling chicks, not sternal or articular cartilage, was reported to synthesize large proteoglycans. Instead, all of these cartilages in the normal chicken have been found in this study to produce large proteoglycans of a size typical for mammalian cartilage and embryonic chick cartilage.

Calcitriol increases Ca2+-ATPase activity

Treatment with calcitriol of isolated cartilage cells derived from epiphyseal growth plates of rachitic chicks results in reduced intracellular calcium concentrations. The reduction in calcium was found to correlate with increased activity of Ca2+-ATPase. The activities of Na+-K+-ATPase and of Mg2+-ATPase did not change in response to the treatment with calcitriol. It is suggested that calcitriol regulates intracellular calcium by modulating the activity of the Ca2+-pumping ATPase.

Migratory multiple bone involvement in a patient with systemic mastocytosis.

A young patient with severe generalized osteopenia and multiple compressed vertebral fractures caused by systemic mastocytosis is presented. Extensive clinical, laboratory, and pathologic examination showed the involvement of the skeleton alone. Follow-up bone scintigraphy with Tc-99m MDP during a period of 6 years demonstrated migratory multiple axial lesions. These results suggest that Tc-99m MDP imaging is an accurate detection of the activity of the disease.