低强度脉冲超声对去势大鼠种植体早期骨整合的影响

目的探讨不同强度的低强度脉冲超声对去势大鼠股骨种植早期骨整合的影响。方法40只经双侧卵巢切除术后12周的雌性SD大鼠,于双侧股骨干骺端植入柱状钛合金种植体,分为两组,每组各20只。术后2天开始对右侧股骨种植体周围分别进行30mW／cm2和80mW／cm2强度的低强度脉冲超声照射,作为试验侧,每天1次,每次20分钟,左侧股骨进行空照射,作为自身对照侧。术后第4、8周分批处死动物,每批20只,每组10只,获取双侧股骨标本,进行Micro-CT扫描及三维重建和生物力学性能检测。结果与对照侧相比,试验侧股骨种植体的骨整合相关参数均有所增加。4周时不同照射强度的试验侧之间,骨整合相关参数的增加率差异无统计学意义（P〉0．05）。8周时80mW／cm2的照射强度显示出更好的生物学效应（P〈0．05）。结论低强度脉冲超声可加快去势大鼠股骨种植体骨整合的形成,有利于种植体初期稳定性的改善。较高强度的低强度脉冲超声更有利于种植体的长期维护。     

低强度脉冲超声对兔关节软骨损伤修复的影响

目的探讨低强度脉冲超声对兔受损关节软骨修复的影响。 方法于10只兔双侧股骨髁间窝软骨面处全层钻孔,作为动物模型。术后左后肢膝关节缺损处予以低强度脉冲超声辐射作为治疗组,右后肢膝关节予以假辐射作为对照组。于术后8周全部处死,行大体评分、组织学评分及修复组织中蛋白多糖含量测定。 结果治疗组大体评分、组织学评分及甲苯胺蓝染色光密度值均比对照组高,差异有统计学意义(P<0.05)。 结论低强度脉冲超声能促进受损关节软骨修复,且修复组织类似透明软骨。     

重组人骨形态发生蛋白2局部注射促进兔胫骨延长区的骨愈合

目的:骨形态发生蛋白与骨延长关系的报道很少。为观察其对于牵拉骨再生延长区骨愈合的作用,将重组人骨形态发生蛋白2经皮注射到兔胫骨延长区,行组织学验证。方法:实验于2004-06/2005-03在吉林大学基础医学院实验动物中心完成。①实验材料:雄性日本大耳白兔30只;重组人骨形态发生蛋白2(由美国哈佛医学院分子骨科中心Oliver博士馈赠)。②实验干预及分组:制作日本大耳白兔延长区骨再生不良动物模型24只,行快速延长,2次/d,1mm/次,2mm/d,共延长10d,共2cm。将兔子随机分为2组,每组12只。对照组,延长结束后延长区注射醋酸盐缓冲液;重组人骨形态发生蛋白2组,延长结束后延长区注射醋酸盐缓冲液溶解的重组人骨形态发生蛋白2。③实验评估:延长结束后2周、4周时2组各取4只兔,麻醉后处死,进行延长区拍摄X射线片及延长区骨标本组织学光镜检查。结果:术中兔死亡及针道处骨折6只,24只进入结果分析。①延长区X射线片评价:延长结束后2周和4周时,显示重组人骨形态发生蛋白2组新生骨痂明显多于对照组,延长结束后4周时重组人骨形态发生蛋白2组髓腔开始形成。②延长区组织学观察结果:延长结束后4周时,对照组延长区周新生软骨、骨增多,融合成片,出现编织骨。重组人骨形态发生蛋白2延长区软骨细胞吸收矿化,转化为编织骨,并逐渐向皮质骨改建塑形。结论:牵拉骨再生延长结束后,延长区经皮注射重组人骨形态发生蛋白2,经间接X射线及组织学直接验证,对延长区骨愈合有促进作用。     

低强度脉冲超声靶向纳米粒控释SDF-1及BMP-2调节hPDLCs迁移和成骨分化

目的该文主要研究低强度脉冲超声(LIPUS)靶向PEG-PLGA纳米粒控释SDF-1α、BMP-2对人牙周膜干细胞(hPDLCs)迁移和成骨分化的调节作用。方法以双乳化法制备SDF-1α/BMP-2/PEG-PLGA,检测其基本表征,BCA蛋白定量法检测蛋白释放情况。实验分为对照组、SDF-1α+BMP-2组、SDF-1α/BMP-2/PEG-PLGA组和LIPUS+SDF-1α/BMP-2/PEG-PLGA组。Transwell细胞迁移实验检测各组迁移能力,碱性磷酸酶(ALP)、茜素红染色实验和实时定量PCR评估各组细胞成骨分化能力。结果 LIPUS辐照成功调节了纳米粒内蛋白的释放速率。与其他组相比,LIPUS+SDF-1α/BMP-2/PEG-PLGA组迁移能力和成骨分化能力显著增强。结论 LIPUS靶向作用PEG-PLGA纳米粒成功调节了SDF-1α、BMP-2的释放,该体系能有效促进人牙周膜干细胞迁移和成骨分化。     

低强度脉冲超声治疗关节软骨缺损的超微结构研究

目的：观察低强度脉冲超声治疗兔关节软骨缺损的效果。方法：在21只兔股骨内侧髁软骨面处钻孔，作为动物模型。术后左后肢膝关节缺损处以低强度脉冲超声辐射作为治疗侧，右后肢予以假辐射作为对照侧。分别于术后2周、4周和8周全部处死取材，作透射电镜检查。结果：治疗侧软骨缺损修复速度及修复组织质量均比对照侧高。结论：低强度脉冲超声能有效地治疗关节软骨缺损。     

低强度脉冲超声用于治疗骨腱连接点损伤及提高骨血管重建相关因子的研究

目的:观察低强度脉冲超声(LIPUS)治疗骨-腱连接点(bone-tendon junction,BTJ)损伤的效果,及对骨血管重建相关因子的促进作用。方法:选取BTJ损伤患者41例,采用LIPUS治疗2周。采用放射免疫法和酶联吸附免疫法(ELISA)检测碱性成纤维细胞生长因子(bFGF)、血小板衍生因子(PDGF)、血管内皮生长因子(VEGF)、转化生长因子-β(TGF-β)及基质金属蛋白酶-3(MMP-3)。采用疼痛视觉模拟评分(VAS)及功能指标变化,评价LIPUS的治疗效果。结果:经LIPUS治疗2周后,血清中bFGF、PDGF、VEGF、TGF-β及MMP-3水平较治疗前均明显升高(P0.05或P0.01);VAS评分较治疗前明显下降([7.42±1.89)vs(4.00±1.05)分,t=8.492,P=0.000],Lysholm膝关节功能评分[(65.74±4.05)vs(83.69±8.25)分,t=5.114,P=0.000]、每分钟上下台阶次数([24.81±5.19)vs(40.32±6.33)次/min,t=15.333,P=0.000]及每日平均运动时间([20.25±2.74)vs(72.30±8.52)min/d,t=14.305,P=0.000]均较治疗前明显升高(P=0.000)。每日平均运动时间随时间呈逐渐增高趋势,由72h开始,与治疗前比较,差异有显著性意义(P0.01)。结论:LIPUS治疗可提高骨血管重建相关因子水平,促进BTJ损伤恢复,效果显著。     

低强度脉冲超声治疗骨关节炎的应用进展

近年来低强度脉冲超声治疗骨关节炎在临床研究中取得了一定的疗效。研究内容涉及软骨细胞、Ⅱ型蛋白胶原、胶原酶、转化生长因子β、滑膜炎及病理改变等方面。系列临床研究结果说明低强度脉冲超声是一种无创伤、操作方便、费用低廉、疗效确切、并发症少的治疗方法。本文就低强度脉冲超声治疗骨关节炎的应用进展作一综述。     

牵伸联合低强度脉冲超声对兔膝关节挛缩影响的研究

摘要目的：观察牵伸联合低强度脉冲超声（low intensity pulsed ultrasound,LIPUS）对固定诱导的兔膝关节囊纤维化的影响,并明确牵伸联合LIPUS对兔膝关节源性挛缩的影响。方法：选取新西兰白兔30只,随机分为以下5组,每组6只：对照组（C）、自然恢复组（NR）、LIPUS组（LT）、牵伸组（ST）、牵伸联合LIPUS组（CT）。C组不进行任何处理,其余4组将兔左膝关节伸直位固定6周后,再解除固定分为：NR组进行自然恢复,LT组进行LIPUS干预,ST组进行牵伸干预,CT组进行牵伸联合LIPUS干预。各组干预时间为4周,通过关节活动测量仪检测各组膝关节源性挛缩角度、马松（Masson）染色分析膝关节前囊胶原沉积百分比、蛋白质免疫印迹分析（Western blot）膝关节前囊内转化生长因子（TGF）-β1、α-平滑肌肌动蛋白（SMA）、Ⅰ型胶原（Collagen Ⅰ）、Ⅲ型胶原（Collagen Ⅲ）的蛋白表达水平。结果：在干预4周后,与NR组比较,LT组、ST组、CT组均能有效减小膝关节源性挛缩角度（P＜0.05）;LT组、ST组、CT组均能减轻关节囊纤维化（P＜0.05）,表现为胶原沉积百分比降低（P＜0.05）以及TGF-β1、α-SMA、Collagen Ⅰ、Collagen Ⅲ的蛋白表达水平降低（P＜0.05）。值得注意的是,CT组取得最好的干预效果（与其他干预组相比均P＜0.05）。结论：牵伸联合低强度脉冲超声通过降低膝关节囊内胶原沉积和TGF-β1、α-SMA、Collagen Ⅰ、Collagen Ⅲ的蛋白水平表达来减轻关节囊的纤维化,继而改善膝关节源性挛缩角度。     

低强度的脉冲超声对钛种植体骨结合的影响

目的观察低频脉冲超声对种植体骨结合的影响。方法实验组侧对种植体植入部位进行低频脉冲超声照射。对照侧未进行低频超声照射。低频脉冲超声照射结束后0、2、4、6、8周分别处死2只动物取材,然后进行显微CT扫描、组织学染色以及种植体生物力学检测,评估种植体与周围骨结合的效果。结果显微CT扫描与组织学染色分析发现,经过低频脉冲超声照射后的种植体骨结合形成更早且效果更佳。生物力学检测发现,低频脉冲超声照射后种植钛金属具有更大的拔出力。结论低频脉冲超声可以提升种植体的骨结合效果。     

低强度脉冲超声对兔膝骨性关节炎骨软骨连接血管形成与侵袭的影响

目的观察低强度脉冲超声(LIPUS)对早期兔膝骨性关节炎骨软骨连接血管形成与侵袭的影响。 方法18只新西兰大白兔按随机数字表法分为对照组、模型组和治疗组,每组6只,模型组和治疗组接受前交叉韧带切断法手术,4周后建立早期骨性关节炎疾病模型,而对照组仅接受假手术处理。治疗组接受LIPUS辐射治疗4周,模型组和对照组仅接受LIPUS假辐射。采用番红O 固绿染色比较各组膝关节骨软骨连接血管形成与侵袭情况;采用免疫印迹(Western blot)技术检测各组的整合素β1、磷酸化黏着斑激酶(p FAK)、磷酸化p38、磷酸化c Jun氨基末端激酶(p JNK)、血管内皮生长因子(VEGF)及软骨调节素(CHM) 1蛋白表达水平。 结果模型组和治疗组与对照组比较,骨软骨连接血管形成明显增多,潮线出现漂移、重复,结构紊乱,甚至消失,部分血管突破潮线,侵入非钙化软骨层,而治疗组较模型组病理改变明显减轻。模型组的整合素β1、p FAK和VEGF表达水平［（0.92±0.07）、（0.83±0.09）和（1.02±0.10）］较对照组［（0.45±0.04）、（0.18±0.03）和（0.35±0.02）］明显增高,且组间差异有统计学意义(P<0.05);模型组的p38和JNK磷酸化水平［（0.99±0.11）和（1.86±0.06）］亦较对照组［（0.31±0.04）和（0.38±0.03）］明显增高(P<0.05);而模型组的ChM 1表达（0.61±0.04）较对照组（1.91±0.08）下降,且差异有统计学意义(P<0.05)。治疗组与模型组比较,治疗组的整合素β1和p FAK表达［（1.10±0.09）和（1.09±0.08）］亦较模型组明显增高,组间差异有统计学意义(P<0.05);但治疗组的VEGF表达（0.58±0.06）较模型组明显降低(P<0.05),治疗组的p38和JNK磷酸化水平［（0.54±0.09）和（1.29±0.08）］亦较模型组降低,且差异有统计学意义(P<0.05);但治疗组的ChM 1表达（1.09±0.12）较模型组明显升高,差异有统计学意义(P<0.05)。 结论LIPUS可以抑制骨性关节炎骨软骨连接血管形成与侵袭,其作用机制可能与LIPUS通过整合素β1 FAK p38/JNK VEGF/ChM 1通路调控血管形成相关因子VEGF和ChM 1的表达有关。     

Congenital pseudoarthrosis of the tibia treated with low-intensity pulsed ultrasound stimulation (LIPUS)

A 16-year-old Japanese boy was admitted to our institution in September 2000 because no apparent callus had appeared around a fracture after 6 weeks of cast fixation. Physical examination revealed a tenderness of the right lower leg, and multiple small subcutaneous tumors and café-au-lait spots in extremities and trunk. Radiographs showed the fracture of the right lower tibia with bony sclerosis and a localized fusiform osteolytic lesion at the fracture site. The affected tibia bowed anteriorly and the medullary space in the lower tibia was narrow. A diagnosis of Boyd type IV congenital pseudoarthrosis of the tibia was made. Treatment with low-intensity pulsed ultrasound (US) stimulation (LIPUS) was administered for 20 min/day, and a nonweight-bearing gait was continued with a cast or brace fixation. At 6 months after the treatment, a small amount of bridging callus was seen. We continued the treatment for 1 year until the solid fusion was observed on radiographs and the patient started full-weight-bearing.     

弯曲应力作用下兔胫骨骨干皮质骨的骨重建方式

背景：骨所承受的应力变化是骨重建的重要刺激源。目前应力与骨重建关系的研究集中在轴向应力对骨重建的影响，而对弯曲应力环境下的骨重建模式缺乏研究。目的；观察在长期弯曲应力作用下生长期兔胫骨骨干皮质骨骨重建的方式。方法：在兔左胫骨近端内侧骨骺线远侧O．5cm处开一直径2．5mm骨窗，用冰盐水将兔胫骨及记忆合金片降温，降温后将记忆合金片拉直后经骨窗置入胫骨髓腔。记忆合金置入方向：使其复温后两端抵在外侧骨皮质上，弧形顶点抵向内侧骨皮质，缝合伤口。通过胫骨髓腔内置入的形状记忆合金片，给予兔胫骨骨干内部施加持续弯曲应力，观察胫骨骨干皮质骨在长期弯曲应力环境下骨重建的模式。结果与结论；在6个月持续弯曲应力作用下，兔胫骨骨干张应力侧骨皮质变薄，压应力侧骨皮质增厚，胫骨未观察到明显弯曲形变，压力侧骨皮质增厚程度与胫骨上的应力分布有关。结构完整的胫骨对弯曲应力表现出一种内在的“抗性”，说明无骨折长骨骨干部分基本上不具备力线矫正潜力。实验结果提示，弯曲应力下兔胫骨骨干皮质骨骨重建模型创伤小，应力可控，不影响骨的生长和代谢，不限制实验动物活动，更符合生理状态，是一个理想的骨重建动物模型。     

Acceleration of increase in bone mineral content by low-intensity ultrasound energy in leg lengthening.

The effect of ultrasound energy on bone has been studied for a long time. In particular, multiple effects of low-intensity ultrasound energy have recently been demonstrated experimentally, such as increases in bending strength of fracture callus, acceleration of soft callus formation and endochondral ossification of the callus at the fracture site, stimulation of aggrecan gene expression, or modulation of TGF-beta synthesis and increase of calcium uptake. Clinically, prospective, randomized, and double-blind trials showed the efficacy of low-intensity ultrasound beam stimulation in the acceleration of fracture healing, with a significant decrease in the time to healing. On the other hand, callotasis, a popular method for bone lengthening, requires much time for new bone formation, and an external fixator must be remain on the patient for a long period. This is one of the major problems of the callotasis technique. If ultrasound energy stimulation could accelerate the rate of callus formation in callotasis, the external fixator could be removed earlier, the treatment period could be shortened, and the patient could return to daily activities more quickly. We report on the use low-intensity ultrasound beam stimulation during leg lengthening with the callotasis method in which callus formation was poor.     

Distraction-resisting force during tibial diaphyseal lengthening and consolidation--a study on a rabbit model

BACKGROUND: Distraction-resisting force is generated in the soft tissues and callus during limb lengthening. Monitoring this force may offer a method of studying the behaviour of soft tissue and detecting the distraction osteogenesis related problems, and help to prevent complications. Changes in the post distraction period have not been previously investigated and there are no reports on the contribution of gastrocnemius to the distraction-resisting force. METHODS: Sixteen immature New Zealand White rabbits underwent 30% (left) tibial diaphyseal lengthening at a rate of two 0.4 mm increments per day. Using an instrumented bilateral fixator, the passive distraction-resisting force and the contribution made by gastrocnemius were measured at the end of lengthening and 5 weeks after lengthening. FINDINGS: The distraction-resisting force at the end of lengthening (mean 44 N (SD 10)) was statistically higher (p < 0.01) than that five weeks after lengthening (mean 20 N (SD 8)), so was the contribution of the gastrocnemius to the force (mean 11 N (SD 5 N) or 25% (SD 7) at the end of lengthening and 3 N (SD 1) or 13% (SD 5.2) five weeks later). INTERPRETATION: The callus rather than the surrounding muscles generates most of the passive DRF and its share of the force increased during consolidation period.     

低强度脉冲超声波对早中期兔膝骨性关节炎软骨细胞外基质及MAPKs信号通路的影响

目的:研究低强度脉冲超声波(LIPUS)对早中期兔膝骨性关节炎(OA)软骨细胞外基质(ECM)、丝裂原活化蛋白激酶(MAPKs)信号通路的影响,探讨LIPUS对关节软骨损伤修复和延缓退变的作用机制。方法:36只健康新西兰兔随机分成6组,早期对照组(EC组)、早期OA组(EO组)、早期治疗组(ET组)、中期对照组(MC组)、中期OA组(MO组)和中期治疗组(MT组),6只/组。EO、ET、MO及MT组均接受左后肢前交叉韧带切断术(ACLT),对照组仅接受左侧膝关节囊切开术。ET组和MT组分别于术后第3天和第5周起接受LIPUS治疗。超声频率3MHz,强度40mW/cm2,作用时间20min,1次/d,6d/周,持续6周。EO与MO组的LIPUS方案与治疗组相同,但无超声输出。LIDUS6周后,采用甲苯胺蓝染色进行关节软骨的组织学观察,并进行Mankin评分。采用免疫印迹法检测蛋白多糖、Ⅱ型胶原、磷酸化的细胞外信号调节激酶1/2(p-ERK1/2)及p38(p-p38)的变化。结果:③组织学观察及Mankin评分:EO组关节软骨表面不规则、甲苯胺蓝染色变浅、软骨细胞减少,与EC组相比,Mankin评分显著升高(P<0.01);MO组关节软骨损伤明显,Mankin评分较MC组显著升高(P<0.01)。与EO组相比,ET组病理学改变程度轻,Mankin评分显著降低(P<0.01);但MT组Mankin评分较MO组无显著降低(P>0.05)。③Ⅱ型胶原、蛋白多糖检测:与EC组比较,EO组和ET组均下降,但EO组较ET组明显下降(P<0.05);与MC组相比,MO和MT组均显著降低(P<0.05),MO组与MT组间无显著差异(P>0.05)。③p-ERK1/2、p-p38检测:与EC组相比,EO组表达量显著升高(P<0.05),但与EO组相比,ET组显著降低(P<0.05);与MC组相比,MO组和MT组表达显著升高(P<0.05),MT组与MO组间无明显差异(P>0.05)。结论:LIPUS可以减轻关节软骨ECM的损伤程度,其作用与LIPUS治疗后关节软骨中p38、ERK1/2表达下调有关,这种作用与OA的病变阶段密切相关,即在OA早期进行LIPUS作用更明显。     

Microencapsulated rabbit adipose stem cells initiate tissue regeneration in a rabbit ear defect model

Cell‐based tissue engineering can promote cartilage tissue regeneration, but cell retention in the implant site post‐delivery is problematic. Alginate microbeads containing adipose stem cells (ASCs) pretreated with chondrogenic media have been used successfully to regenerate hyaline cartilage in critical size defects in rat xiphoid suggesting that they may be used to treat defects in elastic cartilages such as the ear. To test this, we used microbeads made with low viscosity, high mannuronate medical grade alginate using a high electrostatic potential, and a calcium cross linking solution containing glucose. Microbeads containing rabbit ASCs (rbASCs) were implanted bilaterally in 3 mm critical size midcartilage ear defects of six skeletally mature male New Zealand White rabbits (empty defect; microbeads without cells; microbeads with cells; degradable microbeads with cells; and autograft). Twelve weeks post‐implantation, regeneration was assessed by microCT and histology. Microencapsulated rbASCs cultured in chondrogenic media expressed mRNAs for aggrecan, Type II collagen, and Type X collagen. Histologically, empty defects contained fibrous tissue; microbeads without cells were still present in defects and were surrounded by fibrous tissue; nondegradable beads with rbASCs initiated cartilage regeneration; degradable microbeads with cells produced immature bone‐like tissue, also demonstrated by microCT; and autografts appeared as normal auricular cartilage but were not fully integrated with the tissue surrounding the defect. Elastin, the hallmark of auricular cartilage, was not evident in the neocartilage. This delivery system offers the potential for regeneration of auricular cartilage, but vascularity of the treatment site and use of factors that induce elastin must be considered.     

低强度脉冲超声波对兔膝骨性关节炎软骨整合素-FAK-MAPKs信号通路蛋白表达的影响

目的:观察低强度脉冲超声波(low-intensity pulsed ultrasound,LIPUS)对兔膝骨性关节炎(osteoarthritis,OA)软骨中整合素-FAK-MAPKs力化学细胞信号转导通路相关蛋白表达的影响。方法:18只成年新西兰大白兔随机平均分成3组,分为正常对照组(normal control,NC),OA模型组(OA group,OA),OA模型照射组(O+L)。OA组接受右侧后肢前交叉韧带切断(ACLT)处理术后4周接受LIPUS假辐射,O+L组同样手术处理,术后4周接受LIPUS辐射,NC组仅切开关节囊。LIPUS作用6周后,处死实验动物,取右后肢,采用HE染色行改良Mankin评分比较各组胫骨平台关节表面病理学改变。同时,采用Western blot技术检测Ⅱ型胶原,MMP-13,整合素β1的蛋白表达水平以及FAK、MAPKs家族蛋白(p38、ERK1/2、JNK)磷酸化水平。结果:1组织学观察及Mankin评分:LIPUS干预后,OA软骨表层轻微不平整,染色轻度缺失,可见软骨细胞增殖;Mankin评分,NC组:4.67±0.57;OA组:10.57±2.55;O+L组:7.66±1.74。与NC组相比,OA组、O+L组Mankin评分明显增高,但OA组增高更为明显(P0.05);与OA组相比,O+L组Mankin评分明显降低(P0.05)。2Ⅱ型胶原、MMP-13含量:LIPUS干预后,II型胶原含量较NC组升高,MMP-13含量有明显下降。3整合素β1-FAK-MAPKs信号通路相关蛋白表达:LIPUS干预使整合素β1、磷酸化FAK表达增高;同时MAPKs信号通路相关蛋白ERK1/2、p38磷酸化水平明显下降,而JNK磷酸化水平无明显变化。结论:LIPUS可以减轻骨性关节炎软骨ECM损伤程度,与LIPUS产生机械应力使关节软骨中细胞表面应力受体之一整合素β1及其下游分子黏着斑激酶FAK磷酸化表达增高,进一步下游的磷酸化p38,ERK1/2表达下调有关。LIPUS的机械效应可经力化学转导途径作用于OA关节软骨,为治疗骨性关节炎提供一种新的思路。     

Effects of ultrasound on osteotomy healing in a rabbit fracture model

This study investigated the effects of ultrasound (US) at different frequencies on fracture healing over a three-week period in a rabbit fibular fracture model. Forty-five adult New Zealand White rabbits were divided into five groups: a control group and four groups treated with US frequencies of 0.5, 1.0, 1.5 and 2.0 MHz (0.5 W/cm², 200-μs burst, pulsed 1:4). After anesthesia, transverse osteotomy was performed on the fibula bone. This was followed by intravital staining and fluorescence microscopic examination of new bone formation and biomechanical tests of torsional stiffness at the osteotomy site. Results showed that total new bone formation and torsional stiffness of the fibula were greater in all US-treated groups than in the control group. No significant difference was found between any of the four US-treated groups. The US treatment also enhanced bone growth of the sham-treated contralateral fracture site. These results suggest that US treatment at 0.5, 1.0, 1.5 or 2.0 MHz can enhance fracture healing in a rabbit model. Furthermore, the effects of US on fracture healing at present parameters might not be confined locally.     

Delayed fetal pulmonary maturation in a rabbit model of the diabetic pregnancy.

A rabbit model for the diabetic pregnancy was used to investigate the etiology of delayed pulmonary maturation observed in infants of diabetic mothers. Pregnant rabbit does were made glucose intolerant and insulinopenic by injection of alloxan, a pancreatic beta-cell cytotoxin. At 28 d (term approximately 31 d) fetuses of these animals were hyperglycemic, but were not hyperinsulinemic and did not demonstrate tissue overgrowth. Fetal pulmonary maturity was assessed by measurement of pressure-volume relationships on the fetal lungs. Fetuses of glucose-intolerant does demonstrated less retention of air on deflation. Phospholipid components of pulmonary surfactant were assayed on fluid obtained from lavage of the fetal lungs. Levels of disaturated phosphatidylcholine (per-cent total-lavage phospholipids) were diminished in fetuses of glucose-intolerant does compared to control fetuses (20.5 +/- 4.2 vs. 38.0 +/ 4.3%; P less than 0.01). Lecithin/sphingomyelin ratios were similar in both groups and phosphatidylglycerol was not detected in either group. There was a direct correlation between the percentage of alveolar disaturated phosphatidylcholine and retention of air on lung deflation. These findings suggest that in this model pulmonary instability was a result of diminished alveolar disaturated phosphatidylcholine, and this diminution did not result from fetal hyperinsulinemia.     

Tendon regeneration induced by umbilical cord graft in a rabbit tendon defect model

Whether tendon regeneration can be induced using the umbilical cord as a whole‐graft structure is unknown. In this study, we explored the potential for tendon regeneration induction using an umbilical cord graft in a rabbit model of patella tendon defects. In 52 of 54 New Zealand White rabbits, the central third of the patella tendons of both hind legs was removed to create tendon defects. The rabbits were randomly divided into four groups, nonfilling (empty defect), refilling (defect refilled with resected tendon portion), Wharton's jelly (WJ) outside (WJO; defect filled with umbilical cord graft, WJ side facing outward), and WJ inside (WJI; same as WJO with WJ side facing inward) groups. Four rabbits from WJO and WJI groups were sacrificed for human CD 105 evaluation 1 month after surgery. Further histological, biomechanical, and gene expression analyses were performed at 3 and 6 months after surgery. The untreated patella tendons in the remaining two rabbits were harvested as normal biomechanical controls. Histological evaluation showed that the formed tissue structure fibers in the tendon defect area were much denser and more mature in the WJI group than in all other groups. Biomechanical testing showed that the failure load of the final tissue structure was the highest in the WJI group. Real‐time polymerase chain reaction indicated that the expression of most tendon‐related genes was upregulated in the WJI group at 6 months after surgery. We concluded that umbilical cord grafting induces effective tendon regeneration, particularly when the WJ side faces inward.