Effects of Misoprostol on Bone Resorption and Formation in Organ Culture

Prostaglandins are potent stimulators of bone resorption and formation. Because misoprostol is an analog of prostaglandin E(1) (PGE(1)), we have examined its effects on resorption and formation in organ culture. The results were compared with PGE(2) which can stimulate resorption and both stimulate and inhibit bone formation. Resorption, measured as the release of previously incorporated (45)Ca from 5-day cultures of 19-day fetal-rat long bones, was increased by misoprostol 1.5-fold at 10(minus sign6) M and twofold at 10(minus sign5) M. The effect at 10(minus sign6) M was abolished by addition of indomethacin (10(minus sign6) M). PGE(2) was approximately 100 times more potent and was not affected by indomethacin in this system. In 21-day fetal-rat calvariae, cultured for 24 h in the presence of cortisol (10(minus sign7) M), misoprostol produced a dose-related increase in TdR incorporation between 10(minus sign5) and 10(minus sign7) M. PGE(2) appeared to be only 10-fold more potent in this response. The effects of misoprostol on incorporation of [(3)H]proline into collagenase digestible protein (CDP) and noncollagen protein (NCP) were measured in 72-h cultures, either with continuous treatment or 24-h treatment followed by 48 h in control medium. With continuous treatment at 10(minus sign6) M, misoprostol increased labeling of CDP twofold. A similar effect was observed with 24 h of treatment at 10(minus sign5) M, followed by 48 h in control medium. Again, PGE(2) was approximately 10-fold more potent than misoprostol. When calvariae were treated with insulin-like growth factor I, which increases CDP labeling by 2.5-fold, the effects of misoprostol and PGE(2) were inhibitory. We conclude that misoprostol resembles PGE(2) in its effects on bone but is less potent. Moreover, misoprostol may be relatively less effective in stimulating resorption than in stimulating formation. Therefore, an increase in bone turnover, possibly with a net anabolic effect, might occur in vivo with long-term misoprostol treatment. Misoprostol effects on bone turnover in humans could be evaluated using the sensitive biochemical markers for bone resorption and formation which are currently available.     

Suppressive Effects of 24,25-Dihydroxycholecalciferol on Bone Resorption Induced by Acute Bilateral Nephrectomy in Rats

The possible suppressive effects of 24,25-dihydroxycholecalciferol on secondary hyperparathyroidism and increased bone resorption were investigated in adult rats raised on a diet normal in calcium, phosphorus, and vitamin D, and subjected to acute bilateral nephrectomy. The animals had received subcutaneous radiocalcium 4 wk before the experiment. 5 h after nephrectomy an increase in serum total calcium, ⁴⁵Ca-specific activity, citrate, phosphorus, and magnesium concentrations were observed. Serum immunoreactive parathyroid hormone increased, while serum calcitonin decreased. The osteoclast count in the tibial metaphyses was augmented. The biochemical and histological changes observed were partly parathyroid hormone and calcitonin independent, as they also occurred in parathyroidectomized hypocalcemic rats. Pretreatment with 650 pmol of 24,25-dihydroxycholecalciferol 16 h before nephrectomy prevented bone calcium mobilization and diminished the rise in serum total calcium and citrate both in parathyroid-intact and in parathyroidectomized animals. In parathyroid-intact rats, serum immunoreactive parathyroid hormone and calcitonin remained normal in spite of the fall in serum-ionized calcium, and the number of osteoclasts did not increase. In parathyroidectomized rats, 24,25-dihydroxycholecalciferol did not prevent the postnephrectomy rise in the osteoclast count. This latter observation suggests that this metabolite exerts its effect on bone either by acting on cells other than osteoclasts, i.e., the osteocytes, or by inhibiting cell activity. At equimolar dosage 1,25-dihydroxycholecalciferol had a potent stimulatory effect on bone resorption. This effect of 1,25-dihydroxycholecalciferol was partly blocked by the simultaneous administration of 24,25-dihydroxycholecalciferol.     

Effect of 1,25-Dihydroxyvitamin D3 on the Renal Handling of Pi in Thyroparathyroidectomized Rats

The kidney adapts its tubular capacity to transport inorganic phosphate (P_i) according to the dietary supply of P_i in both intact and thyropara-thyroidectomized (TPTX) rats. However, in TPTX rats the capability of the renal tubule to adapt to a high P_i diet is diminished. In TPTX rats the production of the active vitamin D₃ metabolite, 1,25-dihydroxyvitamin D₃ [1,25-(OH)₂D₃], is also reduced. 1,25-(OH)₂D₃ has been shown to have a marked effect on P_i metabolism. Therefore the question arises whether the deficient production of 1,25-(OH)₂D₃ contributes to the alteration of the tubular transport of P_i observed in chronically TPTX rats. In the present investigation, vitamin D-replete rats were sham operated (SHAM) or thyroparathyroidectomized and then pair fed diets containing either 0.2 or 1.2 g/100 g P for 7 days. During this period, groups of SHAM and TPTX rats received i.p. 2 × 13 pmol/day of 1,25-(OH)₂D₃, a dose which was shown to just normalize the decreased intestinal absorption of Ca and P_i in TPTX rats. The capacity of tubular P_i transport was then assessed by measuring the fractional excretion of P_i (FEP_i) at increasing plasma P_i concentration ([P_i]_Pl) obtained by acute infusion of P_i. The results show that in SHAM rats fed either P diet, 1,25-(OH)₂D₃ has no effect on the renal handling of P_i. In TPTX rats fed 1.2 g/100 g P diet, 1,25-(OH)₂D₃ increases FEP_i over a wide range of [P_i]_Pl. In TPTX rats fed a 0.2 g/100 g P diet, 1,25-(OH)₂D₃ does not alter FEP_i up to a [P_i]_Pl of 3.0-3.5 mM, but does increase it at higher [P_i]_Pl. In fact, on both diets TPTX rats supplemented with 1,25-(OH)₂D₃ appear to have the same renal handling of P_i as SHAM counterparts. The effect of 1,25-(OH)₂D₃ was not associated with a change in urine pH or in urinary excretion of cyclic AMP and was maintained under marked extracellular volume expansion. It was associated with a rise in plasma calcium in the TPTX rats fed the high, but not the low, P diet. In TPTX rats fed 1.2 g/100 g P diet, 25-hydroxyvitamin D₃ in doses of 2 × 130 or 2 × 1,300 pmol/day i.p. did not increase FEP_i.     

上颌中切牙种植体的应力改变及骨吸收变化

目的：观察上颌中切牙种植体植入方向在与牙冠长轴不同夹角情况下,种植体骨界面应力变化值和最大安全角度的临界值,以此来指导种植前设计。方法：应用有限元法分析不同倾斜角度对种植体骨界面应力峰值影响。结合临床病例,使用X线头影测量分析,测算出患者理想牙冠长轴的位置,以此轴线与种植体长轴的夹角作为倾斜角度分析在不同角度下种植体的骨界面应力变化和中切牙种植病例的周围骨吸收情况。倾斜角0°-20°范围内边缘骨吸收值和种植体骨界面应力值均在正常范围内,适合使用角度基台修复;倾斜角大于20°或25°以上时,应力值有明显升高趋势,种植体唇侧颈部应力集中区骨吸收明显。结论：建议做牙槽骨改建手术,改变种植体植入角度。     

Particulate-Induced, Prostaglandin- and Cytokine-Mediated Bone Resorption in an Experimental System and in Failed Joint Replacements

Total hip arthroplasty (THA) has provided dramatic pain relief and improvement in function for millions of patients with end-stage arthritis; however, periprosthetic osteolysis following THA has become increasingly recognized as a major clinical problem in both cemented and cementless reconstructions. An aggressive granulomatous tissue (interfacial membrane) consisting predominantly of fibroblasts, aggregates of macrophages, and foreign body giant cells develops at the interface of bone/prostheses or bone/cement. It is believed that particulate wear debris from prosthetic materials and/or bone cement are phagocytized by histiocytic cells of interfacial membrane and then these cells produce inflammatory mediators and proteolytic enzymes to provoke a cascade of osteolytic events. In this paper, we studied in vitro responsiveness of various cell types to particulate wear debris. Although titanium and titanium alloys demonstrate excellent biocompatibility in bulk from, titanium in particulate form can provoke a variety of cellular responses. We have found that small-sized Ti particles of phagocytosable size, a commonly encountered particle species in the periprosthetic tissues of failed THAs, stimulate macrophages to secrete various mediators of bone resorption (prostaglandin E(2), interleukin-1, interleukin-6, and tumor necrosis factor-alpha from macrophages and cause bone resorption in organ culture. In addition, we have shown that phagocytosable titanium particles stimulate fibroblasts to up-regulate the expression of matrix metalloproteinases (stromelysin and collagenase) without a substantial effect on the tissue inhibitor of these enzymes (TIMP). Titanium particulates also have a suppressive effect on procollagen synthesis by osteoblast-like cell line. Thus, titanium particulates have the capacity to stimulate bone resorption and inhibit bone matrix formation. In this series of experiments, we have also shown in vitro inhibitory effect of certain pharmaceutical components (indomethacin, misoprostol) upon bone resorption in organ culture, which may indicate a potential therapeutic intervention to prevent or treat particulate-induced pathological bone resorption in total joint arthroplasties.     

TRANCE Is Necessary and Sufficient for Osteoblast-mediated Activation of Bone Resorption in Osteoclasts

TRANCE (tumor necrosis factor–related activation-induced cytokine) is a recently described member of the tumor necrosis factor superfamily that stimulates dendritic cell survival and has also been found to induce osteoclastic differentiation from hemopoietic precursors. However, its effects on mature osteoclasts have not been defined. It has long been recognized that stimulation of osteoclasts by agents such as parathyroid hormone (PTH) occurs through a hormonal interaction with osteoblastic cells, which are thereby induced to activate osteoclasts. To determine whether TRANCE accounts for this activity, we tested its effects on mature osteoclasts. TRANCE rapidly induced a dramatic change in osteoclast motility and spreading and inhibited apoptosis. In populations of osteoclasts that were unresponsive to PTH, TRANCE caused activation of bone resorption equivalent to that induced by PTH in the presence of osteoblastic cells. Moreover, osteoblast-mediated stimulation of bone resorption was abrogated by soluble TRANCE receptor and by the soluble decoy receptor osteoprotegerin (OPG), and stimulation of isolated osteoclasts by TRANCE was neutralized by OPG. Thus, TRANCE expression by osteoblasts appears to be both necessary and sufficient for hormone-mediated activation of mature osteoclasts, and TRANCE-R is likely to be a receptor for signal transduction for activation of the osteoclast and its survival.     

同体非血管化游离骨移植中骨形成的实验研究

目的观察非血管化游离骨块在不同离体时间点植入体内后成骨情况。方法拔除狗前磨牙。口腔黏膜完全愈合后,截除狗长度3.0cm的无牙下颌骨段,取不带血管和软组织的全层髂骨,分别在离体40min、120min内植入下颌骨缺损区。术后4、8周取出植骨块,观察移植骨块内细胞活力和新骨形成情况。结果移植骨同期恢复了下颌骨节段性缺损的连续性。离体40min的游离骨块植入体内后4周和8周时仍为活骨块,可见到大量成活的骨细胞,并有数量不等的岛状软骨形成。离体120min的游离骨块植入体内后4周和8周时为死骨块,其中未见骨细胞成活,部分骨块中见到破骨细胞。结论非血管化游离髂骨块在较短的离体时间内同体移植可以修复狗长度3.0cm的下颌骨节段性缺损,在修复过程中可见岛状的软骨形成。新骨形成与游离骨块的离体时间有关。     

Estrogen Inhibits Bone Resorption by Directly Inducing Apoptosis of the Bone-resorbing Osteoclasts

Estrogen deficiency causes bone loss, which can be prevented by estrogen replacement therapy. Using a recently developed technique for isolation of highly purified mammalian osteoclasts, we showed that 17 β-estradiol (E₂) was able to directly inhibit osteoclastic bone resorption. At concentrations effective for inhibiting bone resorption, E₂ also directly induced osteoclast apoptosis in a dose- and time-dependent manner. ICI164,384 and tamoxifen, as pure and partial antagonists, respectively, completely or partially blocked the effect of E₂ on both inhibition of osteoclastic bone resorption and induction of osteoclast apoptosis. These data suggest that the protective effects of estrogen against postmenopausal osteoporosis are mediated in part by the direct induction of apoptosis of the bone-resorbing osteoclasts by an estrogen receptor– mediated mechanism.     

可注射性硫酸钙在免椎体松质骨中成骨性能的研究

目的 观察可注射性硫酸钙在兔椎体松质骨中的成骨降解性能.方法 18只成年新西兰兔随机分为A、B两组,每组9只.其中A组向兔椎体松质骨注入硫酸钙骨水泥（calcium sulfate cement,CSC）;B组作为空白对照组不植入材料.在不同时间点（2,6和12周）采用大体观察、X片影像学、组织学等方法观察和评估CSC植入后在椎体松质骨内的成骨和降解情况.结果 术后兔进食,活动正常,标本周围软组织无炎症反应.CSC在植入2周见少量新生骨,6周植入物部分吸收,见大量新生骨,12周植入物全部吸收,并有编织骨形成,成骨量明显高于对照组（P＜0.05）.结论 可注射性硫酸钙有良好的生物相容性,植入椎体后成骨作用明显,新生骨与植入材料的吸收降解同步,是一种良好的骨移植材料.     

去卵巢大鼠骨密度变化与骨髓造血功能改变的关系

本研究探讨去卵巢大鼠不同时段骨密度的改变与骨髓造血功能改变的关系。探讨骨质疏松的发生与造血功能的关联。50只3月龄SD雌性大鼠随机分为去卵巢（OVX）组和假手术（Sham）组,分别在4周、8周、12周、16周和20周处死。取左侧股骨测量骨密度。右侧远端股骨干骺端松质骨甲醛固定,常规制片观察骨髓组织病理改变,集落形成实验观察造血干细胞集落形成能力,酶联免疫吸附试验（ELISA）检测血清造血生成因子粒-巨噬细胞集落刺激因子（GM—CSF）的浓度。结果表明,大鼠去卵巢4周还未出现明显的骨量丢失时,其骨髓组织即出现明显的脂肪组织容量增加,大鼠去卵巢8周、12周、16周和20周,与同时段假手术组比较股骨骨密度显著减低（P〈0．05）,同时伴有骨髓造血组织容量减少,脂肪组织容量增高,巨核细胞数目减少,破骨细胞数目和肥大细胞数目显著增加,与假手术组比较均有显著性差异（P〈0．05）。大鼠去卵巢16周后,造血干细胞形成粒-巨噬细胞集落能力明显低于假手术组。大鼠去卵巢12周后,GM—CSF水平明显低于假手术各组（P〈0．05）。结论：去卵巢大鼠骨密度减低的同时存在骨髓造血功能的减低,3月龄SD雌性大鼠去卵巢可以作为造血功能减低的动物模型,有助于临床上诸多造血功能减低的研究。     

骨髓基质细胞植入对脑缺血大鼠海马齿状回突触形成及记忆能力的影响

目的探讨骨髓基质细胞(BMSCs)经侧脑室植入脑缺血大鼠后海马齿状回突触形成及大鼠记忆能力的变化。方法大鼠BMSCs培养3 代。60 只新生Sprague-Dawley大鼠分为假手术组、模型组、细胞组各20 只,后两组结扎左侧颈总动脉,细胞组于7 d 后经侧脑室植入BMSCs。8 周后行Morris 水迷宫测试。测试后取脑组织,免疫组织化学染色检测海马齿状回处突触素表达。结果模型组探查训练(T1)和对位探查训练(T2)时间均较假手术组缩短(P<0.05);细胞组T1 和T2 分别较模型组延长(P<0.05)。模型组大鼠海马突触素阳性细胞积分光密度值(IOD)较假手术组减小(P<0.05),细胞组IOD较模型组增加(P<0.05)。结论BMSCs经侧脑室植入可促进脑缺血大鼠海马齿状回突触形成,并改善其记忆功能。     

Mycobacterium tuberculosis Chaperonin 10 Stimulates Bone Resorption: A Potential Contributory Factor in Pott's Disease

Pott's disease (spinal tuberculosis), a condition characterized by massive resorption of the spinal vertebrae, is one of the most striking pathologies resulting from local infection with Mycobacterium tuberculosis (Mt; Boachie-Adjei, O., and R.G. Squillante. 1996. Orthop. Clin. North Am. 27:95–103). The pathogenesis of Pott's disease is not established. Here we report for the first time that a protein, identified by a monoclonal antibody to be the Mt heat shock protein (Baird, P.N., L.M. Hall, and A.R.M. Coates. 1989. J. Gen. Microbiol. 135:931–939) chaperonin (cpn) 10, is responsible for the osteolytic activity of this bacterium. Recombinant Mt cpn10 is a potent stimulator of bone resorption in bone explant cultures and induces osteoclast recruitment, while inhibiting the proliferation of an osteoblast bone–forming cell line. Furthermore, we have found that synthetic peptides corresponding to sequences within the flexible loop and sequence 65–70 of Mt cpn10 may comprise a single conformational unit which encompasses its potent bone-resorbing activity. Our findings suggest that Mt cpn10 may be a valuable pharmacological target for the clinical therapy of vertebral tuberculosis and possibly other bone diseases.     

幼鼠废用性骨质戕主松症骨量与骨质量的相关实验研究

目的：建立并评价幼鼠废用性骨质疏松症实验模型。方法：20只4周龄SD雄性幼年大鼠。随机分为模型组与假手术组。8周后2组比较,采用骨量及骨质量的检测指标对幼鼠废用性骨质疏松症作出评价。结果：与模型组术侧比较,假手术组同侧胫骨骨矿含量。骨密度,骨小梁体积密度,股骨几何参灵敏以及结构力学性均不同程度高于模型组。结论：切断幼鼠坐骨神经可成功建立术侧废用性骨质疏松症,其不仅有骨量的减少而且有骨质量的退化。     

幼鼠废用性骨质疏松症骨量与骨质量的相关实验研究

目的:建立并评价幼鼠废用性骨质疏松症实验模型.方法:20只4周龄SD雄性幼年大鼠,随机分为模型组与假手术组,8周后2组比较,采用骨量及骨质量的检测指标对幼鼠废用性骨质疏松症作出评价.结果:与模型组术侧比较,假手术组同侧胫骨骨矿含量、骨密度、骨小梁体积密度、股骨几何参数以及结构力学性能均不同程度高于模型组.结论:切断幼鼠坐骨神经可成功建立术侧废用性骨质疏松症,其不仅有骨量的减少而且有骨质量的退化.     

细胞因子在去卵巢大鼠骨组织中的检测分析

目的探讨白细胞介素-16(1L-1β)、白细胞介素-6(1L-6)和肿瘤坏死因子-α(TNF-α)对骨质疏松症的影响。方法建立去卵巢大鼠骨质疏松动物模型,采用放射免疫(RIA)法检测血清雌二醇(E2)及骨组织中IL-1β、IL-6、TNF-α水平,光镜下观察HE染色的骨组织形态学变化,X线测定大鼠全身的骨密度。结果与对照组相比,去卵巢组大鼠骨组织中IL-1β、IL-6和TNF-α含量均明显增高,而骨密度和血清E2含量却降低;骨组织形态学也显著改变。结论骨组织微环境中的IL-1β、IL-6和TNF-α可能共同参与介导了去卵巢所致的大鼠骨质疏松。     

绝经后妇女基质金属蛋白酶-2水平及其与骨密度和骨代谢指标的关系

目的:探讨绝经后妇女血清基质金属蛋白酶-2 (MMP-2) 水平及其与骨密度和骨代谢生化指标的关系.方法:用酶联免疫吸附试验(ELISA)测定78例48～65岁绝经后妇女的血清MMP-2, 用双能X线吸收法(DEXA)测定腰椎正位,股骨颈,Ward's三角和大粗隆的骨密度(BMD),用自动生化仪测定血清钙(Ca)、血清骨碱性磷酸酶 (AKP)和血清磷(P).将骨密度检测正常的30例妇女列为正常组,有骨质疏松症(OP)的48例为OP组.结果:①OP组患者血清MMP-2水平(1388±121)μg/L高于正常组(1126±141)μg/L(P<0.01).②OP组血清MMP-2与腰椎、股骨颈和Ward's三角骨密度呈负相关,在校正年龄和体重指数后,与股骨颈骨密度相关性消失.③OP组血清MMP-2与血清Ca负相关(P<0.05),与血清AKP和P无相关性.结论:绝经后妇女血清MMP-2与骨密度和Ca呈相关性,血清MMP-2水平升高可能为绝经后骨质疏松症伴随骨代谢转换过程增快的表现.     

脊髓损伤后对大鼠骨质的影响

选用36只Wistar大鼠，随机分为实验组及假手术组，每组18只。实验组切断脊髓。每组于手术后1、2、3个月各处死6只大鼠，测量血清Ca，P，AKP含量，并测定胫骨上段BMC及BD。结果表明，在脊髓损伤后大鼠血清AKP明显增高（P＜0．05），Ca，P变化不明显，实验组与假手术组比较差异有显著性（P＜0．05），说明脊髓损伤后大鼠体内骨转化增高，骨质明显下降。     

川芎嗪对骨髓移植小鼠骨髓造血的影响

目的 探讨川芎嗪对同基因骨髓移植（Bone Marrow Transplantation,BMT)小鼠骨髓移植后骨髓造血的影响。方法 建立典型同基因BMT小鼠模型,随机分成两组：骨髓移植对照组（BMT组）和骨髓移植＋川芎嗪处理组（川芎嗪组）,另外设正常一组为未做任何处理的小鼠,共3组。BMT组胃饲生理盐水0．2ml／只、次。每天2次,川芎嗪组胃饲磷酸川芎嗪注射液2mg/只、次、每天2次。分别于BMT后第1、7、14天观察外周白细胞,骨髓单个核细胞（CMMNC）,使用免疫组化SABC－AP法测定骨髓组织切片中硫酸肝素（HS）表达水平;基质细胞来源因子－1（stro-maeel derived factor,SDF-1)的表达水平;CXC趋化因子受体4（CXCR4）表达水平。结果 川芎嗪组第7、14天外周白细胞、血小板、CMMMNC、CXCR4表达水平、HS表达水平、SDF－1均显著高于BMT组（P＜0．05）。结论 川芎嗪能在骨髓移植造血重建早期促进骨髓造血。