Phorbol Myristate Acetate Downregulates the Binding Sites for Colony-Stimulating Factor-1 on Osteoclasts Isolated from Rats

Colony-stimulating factor-1 (CSF-1) is the growth factor for the cells of the mononuclear phagocytic system and for osteoclasts. We tested whether phorbol myristate acetate (PMA), a phorbol ester activating protein kinase C, modulates the number of binding sites for CSF-1 on isolated rat osteoclasts. PMA decreased binding of CSF-1 to osteoclasts within 60 minutes. The effect of PMA was dose dependent at concentrations between 10⁻⁹ M and 10⁻⁶ M. The inactive phorbol ester, 4α-phorbol 12,13-didecanoate, had only a slight effect. Since the osteoclast preparation was contaminated with other cells, the action of PMA on the osteoclasts might have been either direct or indirect. In pure osteoclasts harvested by a micropipette, the downregulation of CSF-1 binding by PMA reached only about three-quarters of that in nonpurified preparations. Addition of osteoblastic osteosarcoma UMR106 cells increased the effect of PMA. Antiserum against CSF-1, which was added to osteoclasts contaminated with other cells, mainly osteoblasts, partially inhibited the effect of PMA, but the antiserum had no effect in pure osteoclasts. These data suggest that the effect mediated by osteoblasts or other contaminating cells is due to the release of CSF-1, which is known to downregulate its binding sites on osteoclasts. The direct action of PMA on osteoclasts decreased the binding only to about 40%, in contrast to CSF-1 which completely downregulated the binding. The data also differ from the published results about macrophages. In these cells, PMA downregulates the binding of CSF-1 completely. The CSF-1 binding sites on osteoclasts recovered within 4 hours after removal of PMA, and cycloheximide, an inhibitor of protein synthesis, inhibited the recovery. Received: 16 January 1997 / Accepted: 21 May 1997     

骨巨细胞瘤中的多核巨细胞体外骨吸收研究

目的：比较破骨细胞与骨巨细胞瘤中多核巨细胞的特点，明确后者的性质和来源。方法：用倒置相差显微镜观察体外培养的多核巨细胞的一般形态及降钙素对它的影响；用骨片与多核巨细胞共同培养法观察多核巨细胞的体外骨吸收功能，用扫描电镜观察骨吸收陷窝，Ｇｏｍｏｒｉ染色观察多核巨细胞的酸性磷酸酶活性。结果：倒置相差显微镜下可见多核巨细胞胞核较多（２０个以上），胞浆周边不规则，有伪足样突起；胞浆内可见较多大小不等的空泡；降钙素（１００μｇ·Ｌ－１）可抑制多核巨细胞的伪足样运动；多核巨细胞与灭活的骨片共同培养时可见骨吸收陷窝形成，扫描电镜下可见吸收陷窝底面有原纤维；Ｇｏｍｏｒｉ染色时可见多核巨细胞的酸性磷酸酶呈阳性。结论：证实了多核巨细胞具有破骨细胞的形态特征与骨吸收功能，可能来源于骨髓的破骨细胞前体细胞     

Comparison of the effects of 1,25-dihydroxycholecalciferol,prostaglandin E2, and osteoclast-activating factor with parathyroid hormone on the ultrastructure of osteoclasts in cultured long bones of fetal rats

Summary The effects of 1,25-dihydroxy vitamin D₃ [1,25(OH)₂D₃], prostaglandin (PGE₂), and osteoclast-activating factor (OAF) on the size of osteoclasts, nuclei, ruffled borders, and clear zones in cultured long bones of fetal rats were quantitated. In addition, the number of osteoclasts in the bones was counted and the release of calcium from the bone into the culture medium was determined. These data were compared with the corresponding effects of parathyroid hormone (PTH). All agents tested increased the size of the ruffled borders significantly after 3 h, the size of the clear zones after 12 h, and the size of the cells after 12–24 h. No important differences in sizes were noticed between the agents tested or between the agents and PTH. The number of osteoclasts was increased after 24 h of treatment with PTH, but not after the other agents. Calcium release was significantly increased for all agents between 12 and 24 h. It is concluded that bone resorption by 1,25(OH)₂D₃, OAF, and PGE₂ is mediated primarily by increased activity of existing osteoclasts similar to PTH activation.     

Skeletal alterations in ovariectomized rats

Summary Female Sprague Dawley rats were subjected to either bilateral ovariectomy or sham surgery. Tetracycline derivatives were administered to each rat on two separate occasions to label sites of bone formation. All rats were sacrificed at 5 weeks postovariectomy and their proximal tibiae were processed undecalcified for quantitative bone histomorphometry. A twofold decrease in trabecular bone volume was noted in the proximal tibial metaphysis of ovariectomized rats. This bone loss was associated with elevated histomorphometric indices of bone resorption and formation. Ovariectomy increased osteoclast surface and numbers as well as osteoblast surface and numbers. Elevations in calcification rate and fractional trabecular bone surface with double tetracycline labels also suggest that bone formation was stimulated in ovariectomized rats. In addition, ovariectomized rats exhibited a greater rate of longitudinal bone growth relative to sham-operated control rats. These histomorphometric data indicate that ovariectomy induces marked bone loss and accelerated skeletal metabolism in rats.     

Serum vitamin D metabolites and nuclear uptake of (H)-1,25-dihydroxyvitamin D3 in monocytes from patients with autosomal dominant osteopetrosis: A study of two radiological types

The nuclear uptake of (³H)-1,25 dihydroxyvitamin D₃ in freshly isolated human monocytes and the serum levels of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D were investigated in 13 patients with autosomal dominant osteopetrosis and in sex- and age-matched controls. Seven patients had type I osteopetrosis characterized by diffuse, symmetrical osteosclerosis with pronounced sclerosis of the skull and increased thickness of the cranial vault. The other six patients had type II with “Rugger Jersey Spine” and “endobones” as characteristic findings. In type I osteopetrosis the serum 1,25-dihydroxy vitamin D was significantly reduced (p < 0.05), whereas serum 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D receptor binding were normal. In type II osteopetrosis the serum vitamin D metabolites were normal, as was the maximal binding capacity (Bmax) of 1,25-dihydroxyvitamin D to the nuclear receptor. The dissociation constant (Kd), however, was significantly increased (p < 0.01) indicating a modest resistance to 1,25-dihydroxyvitamin D. It is concluded that a general end-organ resistance to 1,25-dihydroxyvitamin D at the receptor level does not exist in type I osteopetrosis, but may contribute to some of the radiological and biochemical findings in type II.     

Bone morphology in epileptics

Summary In 31 epileptics, most of whom had been on anticonvulsive drugs for decades, the amount of osteoid—active and inactive—and the osteoclast activity were measured in iliac crest biopsies and compared with the same variables from a control group. Although falling within normal limits, the amount of osteoid, in particular the inactive osteoid, was significantly increased in the epileptics. The osteoclast activity was also significantly increased in the epileptics.     

The resorption of biological and non-biological substrates by cultured avian and mammalian osteoclasts

Summary Mammalian and avian osteoclasts were isolated mechanically from long bones, seeded on to either untreated, unmineralized, anorganic or surface-demineralized mammalian dental tissues, and cultured for 1–6 h or up to 9 days in medium with added serum (10% heat-inactivated FCS). All substrates showed Howship's resorption lacunae which varied in detail with the composition and structural organization of the tissue. There was no species or substrate specificity. Osteoclasts also adhered, spread, migrated and resorbed in the absence of serum. In addition, osteoclasts resorbed avian egg shell and mollusc shell containing calcite and aragonite. When given the opportunity, osteoclasts are thus biochemically competent to resorb a much wider range of substrates than they usually do in vivo. Access to the substrate and attraction or deliverance of osteoclast precursors to it must be curtailing factors in in vivo resorption.     

Monocyte-enriched cells on calcified tissues

Summary Monocyte-enriched human blood cells seeded on to sperm whale dentine and cultured for up to 20 days failed to produce any morphological signs of resorbtive activity, although multinucleate giant cells were formed. In contrast, preparations containing known osteoclasts derived from bone resorbed the same substrate within hours.     

PDGF-BB与IGF-I联合应用对大鼠正畸牙移动的影响

目的:观察血小板衍生生长因子-BB(PDGF-BB)与胰岛素样生长因子-I(IGF-I)联合应用对大鼠正畸牙移动的影响,为正畸临床治疗加快正畸牙移动.缩短正畸治疗时间进行探索.方法:在32只SD雄性大鼠上颌安装施加50 g力正畸装置牵引上颌第一磨牙近中移动,隔日在正畸牙颊侧牙龈黏膜下分别或联合注射200 ng rIfl...     

An atypical subtrochanteric femoral fracture from pycnodysostosis: A lesson from nature

This case describes a man with an unusual cause of an atypical subtrochanteric fracture, pycnodysostosis. This condition results from mutations involving the cathepsin K gene. New antiresorptive treatments for osteoporosis inhibit the cathepsin K enzyme in osteoclasts. Therefore, there should be vigilant monitoring for the development of long‐term complications noted to occur in diseases of reduced osteoclast function, including pycnodysostosis, in patients receiving these novel antiresorptive agents. © 2011 American Society for Bone and Mineral Research.