Effects of sodium fluoride and alendronate on the bone mineral in minipigs: a small-angle X-ray scattering and backscattered electron imaging study.

Sodium fluoride (NaF), which stimulates bone formation, and bisphosphonates, which reduce bone resorption, are both used in the treatment of osteoporosis, and are binding to bone mineral. In this study, using small-angle X-ray scattering and backscattered electron imaging, we analyzed the bone mineral in the vertebrae of minipigs treated with fluoride, with the bisphosphonate alendronate (ALN), or with vehicle. All specimens were investigated blindly. A slight increase in the average thickness of the mineral crystals as well as changes in the structure of the mineral/collagen composite were found in the case of fluoride-treated animals. No differences were found between ALN-treated animals and controls. The changes produced by fluoride are in the same direction as seen in bones from patients treated with NaF, albeit much smaller. They also correlate quantitatively with the reduction in biomechanical properties of bone in fluoride-treated minipigs found in an earlier study with the same animals. These findings suggest that small changes in the structure of the mineral/collagen composite in bone may considerably affect its biomechanical properties. It also emphasizes the delicate balance between the increase of bone mass and deterioration of bone material properties for the effect of fluoride on the biomechanical properties of bone.

Architectural modifications and cellular response during disuse-related bone loss in calcaneus of the sheep.

The results of simple biomechanical unloading in models of acute-disuse osteoporosis are influenced by systemic and regional effects of the method used to generate the bone loss. A model in which strain-gauge measurements confirmed that the os calcis was unloaded in healthy ewes during ambulation was assessed by histomorphometry. Twelve nonovariectomized adult female Welsh mountain sheep were submitted to hock joint immobilization by an external fixation procedure from the tibia to the metatarsus for a period of 12 wk. Histomorphometric analysis showed that this model was able to produce pure local bone loss, as transiliac bone biopsies failed to reveal any difference between the initial and final results. Immobilized and nonimmobilized calcanei were both removed postmortem. After the 12 wk of the study, osteoclastic activity was increased in accordance with the usual disuse process. An unexpected increase of osteoblastic activity was also observed, possibly related to recovery after the initial dramatic bone loss, but an artifact of the surgical procedure such as a regional acceleration phenomenon cannot be definitively excluded. However, the increased osteoblastic activity was not sufficient to prevent accentuation of the negative bone balance, resulting in a 29% decrease of trabecular bone volume in immobilized calcanei compared with nonimmobilized calcanei. This reduction was due to thinning of trabeculae (72.4 +/- 12.1 vs. 98.9 +/- 15.9 microns; P < 0.05) without any change in trabecular number (2.74 +/- 0.72 vs. 2.79 +/- 0.40/mm2; not significant). In conclusion, this model only locally increased both osteoclastic and osteoblastic activities leading to bone loss and architectural modifications. The decreased bone formation usually observed in other models of disuse osteoporosis may therefore not constitute a local phenomenon generated by unloading.

[Role of phosphorus in hyperparathyroidism secondary to non-dialysed adult chronic renal insufficiency]. / Le rôle du phosphore dans l'hyperparathyroïdie secondaire de l'insuffisant rénal chronique adulte non dialysé.

Secondary hyperparathyroidism (HPT II) occurs early in the course of chronic renal failure (CRF), mainly because of decreased calcitriol levels, low levels of serum calcium, retention of phosphorus, abnormal parathyroid gland function and hyperplasia, and peripheral resistance to the action of parathormone (PTH). Amongst these factors, phosphorus retention plays a crucial role in moderate and advanced CRF, by inhibiting renal calcitriol synthesis, lowering serum calcium levels and stimulating PTH secretion. In patients with mild CRF, phosphorus restriction prevents the development of HPT II by increasing renal calcitriol secretion. In patients with advanced CRF, the suppressive effect of phosphorus restriction may be obtained independent of any changes in plasma calcitriol levels, suggesting a direct effect of phosphorus on parathyroid function. Phosphorus restriction should be used in the early stages of CRF, together with a sufficient intake of calcium in the form of phosphorus chelating salts. When phosphorus and calcium serum concentrations are normalised but PTH levels are not in the target range, 1 alpha hydroxy vitamin D3 derivatives may be used, with a careful monitoring to avoid high serum levels of phosphorus or calcium.

Atypical osteomalacia after 2 year etidronate intermittent cyclic administration in osteoporosis.

A 68-year-old postmenopausal woman with osteoporosis received intermittent cyclic etidronate therapy (400 mg/day). No concomitant diseases were noted. A baseline transiliac bone biopsy showed a high bone turnover without impairment due to mineralization. After 2 years of treatment, she had increased osteoid volume, and mineralization lag time corresponded to a variant form of osteomalacia called atypical osteomalacia. No clinical consequence was observed. This is the first case report of such a mineralization defect due to 2 year intermittent cyclic etidronate therapy.

Comparison of alendronate and sodium fluoride effects on cancellous and cortical bone in minipigs. A one-year study.

Fluoride stimulates trabecular bone formation, whereas bisphosphonates reduce bone resorption and turnover. Fracture prevention has not been convincingly demonstrated for either treatment so far. We compared the effects of 1-yr treatment of 9-mo-old minipigs with sodium fluoride (NaF, 2 mg/kg/d p.o.) or alendronate (ALN, 4 amino-1-hydroxybutylidene bisphosphonate monosodium, 1 mg/kg/d p.o.) on the biomechanical and histomorphometric properties of pig bones. As expected, NaF increased and ALN decreased bone turnover, but in these normal animals neither changed mean bone volume. NaF reduced the strength of cancellous bone from the L4 vertebra, relative to control animals, and the stiffness (resistance to deformation) of the femora, relative to the ALN group. In the ALN-treated animals, there was a strong positive correlation between bone strength and L5 cancellous bone volume, but no such correlation was observed in the NaF group. Furthermore, the modulus (resistance to deformation of the tissue) was inversely related to NaF content and there was a relative decrease in bone strength above 0.25 mg NaF/g bone. Moreover, within the range of changes measured in this study, there was an inverse correlation between bone turnover, estimated as the percentage of osteoid surface, and modulus. These findings have relevant implications regarding the use of these agents for osteoporosis therapy.

Ketodiet, physiological calcium intake and native vitamin D improve renal osteodystrophy.

The effects of a very low-protein diet (VLPD) supplemented with amino acids and ketoanalogues (KA) and with 1 g of calcium carbonate and 1000 IU of vitamin D2, were studied in 17 patients with advanced renal failure (GFR < or = 20 ml/min) over a period of one year. The protein intake was 0.3 g protein/kg body wt/day. Daily phosphorus and calcium intake were respectively 1,500 mg and 300 mg. Sequential bone densitometry was performed and bone histomorphometry after double tetracycline labeling was evaluated, before and after one year of diet. Calcium and phosphate metabolism parameters were monitored every two months. In spite of a significant decrease of GFR, phosphorus, parathyroid hormone (1-84) and osteocalcin plasma levels decreased significantly, while low plasma bicarbonate normalized, and calcitriol and calcium levels remained respectively low and normal. Before the diet, histological study disclosed four cases of mixed osteopathy: osteomalacia associated with osteitis fibrosa (OM/OF), nine pure osteitis fibrosa (OF) and four with normal bone remodeling (NB). After one year of diet, the OM component of OM/OF disappeared, as evidenced by a normalization of the mineral apposition rate and osteoid thickness. In the patients presenting pure OF, a significant decrease in osteoblastic and osteoclastic surfaces, in the number of osteoclasts, and in the bone formation rate (BFR) were found. Vertebral mineral density measured by quantitative computerized tomodensitometry did not change significantly. In conclusion, this study not only confirms the beneficial effects of VLPD + KA + calcium on uremic hyperparathyroid bone disease in advanced renal failure assessed using static bone histomorphometry, but also shows a correction of histodynamic bone parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

[Deforming arthropathy associated with the presence of anti Jo-1 antibody in polymyositis. A new case]. / Arthropathie déformante associée à la présence de l'anticorps anti Jo-1 au cours de la polymyosite. Une nouvelle observation.

A deforming arthropathy confined to the hands developed in a woman with polymyositis of three year's duration. Roentgenograms showed distal subluxations of several fingers, especially the thumb, asymmetrical marginal erosions of the phalanges and periarticular calcifications. These roentgenographic findings are considered to be specific of polymyositis associated with anti-Jo-1 antibody.

[Condensing myeloma. Apropos of 2 cases with bone histomorphometric study]. / Myélome condensant. A propos de deux cas avec étude histomorphométrique osseuse.

Two cases of myeloma with roentgenographic evidence of bone sclerosis confirmed by iliac histomorphometric measurements are reported. In one patient, increased resorption, major depression of osteoblast activity, initial intense myelofibrosis, and myeloid deposits were found. The other patient had both increased resorption and increased osteoblast activity with clinical manifestations suggestive of POEMS syndrome. These two cases are compared with 116 cases previously published in the occidental medical literature and with five histomorphometric studies demonstrating increased bone trabecula volume (BTV). Conventional histologic studies suggest several mechanisms as possible explanations for the occurrence of bone sclerosis, including increased modeling unit activity, isolated osteoblast activation, metamorphic neoosteogenesis in myelofibrosis foci, and, in exceptional cases, inhibition of resorption due to increased production of calcitonin. The diversity of bone modeling patterns evidenced by the seven histomorphometric studies reviewed in this article is striking. Bone modeling patterns provide only a snapshot of bone modeling units and may vary over time in a given patient. Reported cases are too few to allow conclusions but emphasize the need for performing further histomorphometric investigations.

[Bone involvement in primary oxalosis. Study of 20 cases]. / Atteinte osseuse de l'oxalose primitive. Etude de 20 cas.

The authors report 20 cases of primary oxalosis with bone involvement, late revealed in adults in 19 cases. They have studied the clinical, radiological and histological manifestations of this bone oxalosis. 19 cases had an end stage chronic renal failure, either treated by maintenance hemodialysis, or by renal (or liver-renal) graft. 17 patients complained of bone pain after starting hemodialysis; 3 had vertebral crush fractures, and 1 multiple spontaneous fractures. Diffuse bone sclerosis (with a homogeneous pattern on axial skeleton and a patchy appearance on the peripherical skeleton), bone translucency, subperiosteal phalangeal resorption were the main radiological symptoms. Oxalate crystals surrounded by a giant cells granuloma were always observed on bone biopsy (16 cases). Bone resorption was observed in 9 cases, hyperparathyroidism in 14 cases and osteomalacia in 7 cases. Hyperparathyroidism does'nt explain all the clinical and radiological manifestations (especially bone resorption). Bone resorption as other radiological and clinical manifestations can be found without hyperparathyroidism and can increase despite parathyroidectomy; so, bone resorption seems to be partly due to the granulomatous reaction around oxalate crystals rather than hyperparathyroidism.

[Isolated osteoporosis in a case with Cushing's disease: development after treatment]. / Ostéoporose isolée dans un cas de maladie de Cushing: évolution après traitement.

The unusual case of a 37 year old woman with Cushing's disease in whom the only feature of hypercortisolism was a clinically asymptomatic osteoporosis is presented. After successful treatment of the disease, serial bone biopsy examinations and bone mineral density measurements (BMD) were performed up to 31 months. 27 months after cessation of hypercortisolism, BMD remained unchanged and histomorphometric examination showed no improvement of the osteopenia in addition to focal osteomalacia. Despite 5 months of calcium and vitamin D therapy, BMD did not improve. This case report emphasizes the importance of routine evaluation of adrenal function in unexplained isolated osteoporosis. Long-term follow-up studies, leaded in a large number of patients are necessary to elucidate the course of osteoporosis in Cushing's syndrome and the usefulness of a specific treatment.