The apparent critical isotherm for cryoinsult-induced osteonecrotic lesions in emu femoral heads

Cryoinsult-induced osteonecrosis (ON) in the emu femoral head provides a unique opportunity to systematically explore the pathogenesis of ON in an animal model that progresses to human-like femoral head collapse. Among the various characteristics of cryoinsult, the maximally cold temperature attained is one plausible determinant of tissue necrosis. To identify the critical isotherm required to induce development of ON in the cancellous bone of the emu femoral head, a thermal finite element (FE) model of intraoperative cryoinsults was developed. Thermal material property values of emu cancellous bone were estimated from FE simulations of cryoinsult to emu cadaver femora, by varying model properties until the FE-generated temperatures matched corresponding thermocouple measurements. The resulting FE model, with emu bone-specific thermal properties augmented to include blood flow effects, was then used to study intraoperatively performed in vivo cryoinsults. Comparisons of minimum temperatures attained at FE nodes corresponding to the three-dimensional histologically apparent boundary of the region of ON were made for six experimental cryoinsults. Series-wide, a critical isotherm of 3.5 degrees C best corresponded to the boundary of the osteonecrotic lesions.     

Osteocyte-based image analysis for quantitation of histologically apparent femoral head osteonecrosis: application to an emu model

Femoral head osteonecrosis is often characterized histologically by the presence of empty lacunae in the affected bony regions. The shape, size and location of a necrotic lesion influences prognosis, and can, in principle, be quantified by mapping the distribution of empty lacunae within a femoral head. An algorithm is here described that automatically identifies the locations of osteocyte-filled vs. empty lacunae. The algorithm is applied to necrotic lesions surgically induced in the emu, a large bipedal animal model in which osteonecrosis progresses to collapse, as occurs in humans. The animals' femoral heads were harvested at sacrifice, and hematoxylin and eosin-stained histological preparations of the coronal midsections were digitized and image-analyzed. The algorithm's performance in detecting empty lacunae was validated by comparing its results to corresponding assessments by six trained histologists. The percentage of osteocyte-filled lacunae identified by the algorithm vs. by the human readers was statistically indistinguishable.     

A new animal model of femoral head necrosis induced by intraosseous injection of ethanol

There is no reliable animal model of the early stages of osteonecrosis of the femoral head (ONFH) for the evaluation of new therapeutic approaches. In this study, we propose a new animal model of femoral head osteonecrosis. Pure ethanol was injected into the centre of the femoral head in adult Merino sheep under fluoroscopic control. After 3, 6 and 12 weeks the animals were killed and the femoral heads were harvested. Microradiographic and histological changes were analysed and recorded. Partial necrosis was documented over a period of 12 weeks in all animals. The appearance of necrosis in combination with intact macrotexture, macrocirculation and joint cartilage is similar to the features described in early ONFH in humans. Due to its efficacy and its similarity to the early stages of ONFH in humans, this model may be suitable to evaluate new therapeutic techniques in the treatment of ONFH.     

Contact stress distributions on the femoral head of the emu (Dromaius novaehollandiae)

Osteonecrosis of the femoral head remains a challenging orthopaedic problem. The disease frequently progresses to femoral head collapse, leading to debilitating osteoarthritis in the affected hip(s). Since a major goal of pre-collapse interventions is to forestall the need for hip arthroplasty, it is important that any animal models used to develop or study such interventions also have a natural history of progression to femoral head collapse. The emu (Dromaius novaehollandiae), a large flightless bird native to Australia, consistently progresses to femoral head collapse when osteonecrosis is experimentally induced cryogenically. Full biomechanical characterization of the demands this animal places on its hip is an important consideration in future usage of this model. This study reports in vitro measurement of the contact stress distributions on the emu femoral head during stance phase of the gait cycle, using Fuji pressure-sensitive film. Applied hip loadings were based upon ground reaction forces and hip flexion angles recorded in vivo. The contact stress data showed reasonable homology with the human hip, both in terms of stress magnitude and sites of habitual loading on the femoral head.     

Prediction of femoral head collapse in osteonecrosis

The femoral head deteriorates in osteonecrosis. As a consequence of that, the cortical shell of the femoral head can buckle into the cancellous bone supporting it. In order to examine the buckling scenario we performed numerical analysis of a realistic femoral head model. The analysis included a solution of the hip contact problem, which provided the contact pressure distribution, and subsequent buckling simulation based on the given contact pressure. The contact problem was solved iteratively by approximating the cartilage by a discrete set of unilateral linear springs. The buckling calculations were based on a finite element mesh with brick elements for the cancellous bone and shell elements for the cortical shell. Results of 144 simulations for a variety of geometrical, material, and loading parameters strengthen the buckling scenario. They, particularly, show that the normal cancellous bone serves as a strong supporting foundation for the cortical shell and prevents it from buckling. However, under the development of osteonecrosis the deteriorating cancellous bone is unable to prevent the cortical shell from buckling and the critical pressure decreases with the decreasing Young modulus of the cancellous bone. The local buckling of the cortical shell seems to be the driving force of the progressive fracturing of the femoral head leading to its entire collapse. The buckling analysis provides an additional criterion of the femoral head collapse, the critical contact pressure. The buckling scenario also suggests a new argument in speculating on the femoral head reinforcement. If the entire collapse of the femoral head starts with the buckling of the cortical shell then it is reasonable to place the reinforcement as close to the cortical shell as possible.     

Steroid-Associated Hip Joint Collapse in Bipedal Emus

In this study we established a bipedal animal model of steroid-associated hip joint collapse in emus for testing potential treatment protocols to be developed for prevention of steroid-associated joint collapse in preclinical settings. Five adult male emus were treated with a steroid-associated osteonecrosis (SAON) induction protocol using combination of pulsed lipopolysaccharide (LPS) and methylprednisolone (MPS). Additional three emus were used as normal control. Post-induction, emu gait was observed, magnetic resonance imaging (MRI) was performed, and blood was collected for routine examination, including testing blood coagulation and lipid metabolism. Emus were sacrificed at week 24 post-induction, bilateral femora were collected for micro-computed tomography (micro-CT) and histological analysis. Asymmetric limping gait and abnormal MRI signals were found in steroid-treated emus. SAON was found in all emus with a joint collapse incidence of 70%. The percentage of neutrophils (Neut %) and parameters on lipid metabolism significantly increased after induction. Micro-CT revealed structure deterioration of subchondral trabecular bone. Histomorphometry showed larger fat cell fraction and size, thinning of subchondral plate and cartilage layer, smaller osteoblast perimeter percentage and less blood vessels distributed at collapsed region in SAON group as compared with the normal controls. Scanning electron microscope (SEM) showed poor mineral matrix and more osteo-lacunae outline in the collapsed region in SAON group. The combination of pulsed LPS and MPS developed in the current study was safe and effective to induce SAON and deterioration of subchondral bone in bipedal emus with subsequent femoral head collapse, a typical clinical feature observed in patients under pulsed steroid treatment. In conclusion, bipedal emus could be used as an effective preclinical experimental model to evaluate potential treatment protocols to be developed for prevention of ON-induced hip joint collapse in patients.     

早期激素性股骨头坏死模型的建立

目的:建立早期股骨头坏死模型,为研究其发病机制及合理治疗方法的提供可靠的模型基础。方法:用单一剂量脂多糖LPS(10μg/kg)联合三次甲强龙MPS(10 mg/kg)注射,每次间隔24h,诱导建立兔早期股骨头坏死模型,通过影像学及组织病理性学方法评估模型建立情况。结果:4周后,模型组死亡1例,模型组16例X线检查未见异常表现,2例X线提示股骨头密度不均,未出现股骨头塌陷,18例HE染色示骨细胞空骨陷窝增多,脂肪细胞体积变大,数量增多。结论:用脂多糖(LPS)联合甲强龙可成功诱导建立兔早期股骨头坏死模型,模型成功率高、死亡率低。     

建立犬肺渐次萎陷动物模型的实验研究

目的:术中定位是微小肺癌手术面临的主要难题,而原因则是肺在术中萎陷造成的巨大形变。我们从研究肺的术中萎陷着手,建立肺渐次萎陷动物模型,模拟肺在术中发生的萎陷,用以研究肺萎陷的过程、规律及影响因素,为微小肺癌的术中定位提供理论基础。本文用渐进的人工气胸模拟肺在术中的渐次萎陷过程,探讨简便、有效的肺渐次萎陷动物模型的制作方法。方法:健康成年犬12只机等分入左、右侧手术组麻醉后移至CT扫描床采用切小口置管和胸腔穿刺两种方式制作人工气胸。向胸膜腔内分次、定量地注射气体,使肺逐渐萎陷直至完全萎陷。通过夹闭气管插管协助稳定肺的萎陷状态。将各萎陷状态分别进行CT扫描。结果:所有实验犬均顺利完成实验麻醉良好,无意外情况发生。9只犬给予气管插管,3只未给予气管插管;4只犬采用切小口置管方式制作气胸,8只采用胸腔穿刺方式。气管插管增加了模型制作难度,但有利于稳定肺的萎陷状态;胸腔穿刺方式相对操作更为简便。随着向胸膜腔内注射气体,肺缓慢而均匀地向肺门方向集中,萎陷进程满意。CT扫描记录了肺从膨胀到萎陷的各阶段,经过后期重建再现了肺的萎陷过程。5只犬出现并发症,均通过改变操作得以纠正,未影响实验进程。结论:本研究建立的肺渐次萎陷动物模型,能够很好地模拟肺在术中的萎陷过程,是研究术中肺萎陷的理想动物模型。     

Biomaterial-loaded allograft threaded cage for the treatment of femoral head osteonecrosis in a goat model

The purpose of this study was to evaluate the efficacy of core decompression with a biomaterial-loaded allograft threaded cage (ATC) for the treatment of femoral head osteonecrosis in an established goat model. First, bilateral early-stage osteonecrosis was induced. After core decompression, the remaining goats were randomly divided into three groups: Group A, the goats were left without any treatment; Group B, the goats were treated with implanting a composite of autologous bone and decalcified bone matrix (DBM); Group C, the goats were treated using insertion of ATC loaded with DBM and autogenous bone graft. Then radiographic, histological and biomechanical analysis were taken in each group at 5, 10, and 20 weeks postoperation. In Group A, the classical signs of osteonecrosis of the femoral head were identified 10 weeks after the induction. Twenty weeks later, the density, surface and biomechanical stability of the femoral head were normal in Group C, while an irregular surface and an inhomogeneous microstructure or variation of density/hardness were identified in Group B. The specimens revealed a continuous trabaecular bone structure throughout the cage and extensive bone ingrowth and remodeling in Group C, while fibrous tissue was evident in Group B. Core decompression with a biomaterial loaded ATC almost uniformly delays or arrests the progression of the disease before articular collapse, and it could help to get the balance between bone resorption and new bone formation, strengthen structural mechanics of the femoral head, provide structure support of articular cartilage.     

Nouvelle stratégie dans le diagnostic,la prévention et le suivi de l’ostéonécrose drépanocytaire en Côte d’Ivoire à partir de la scintigraphie osseuse

Osteonecrosis is the most frequent complications of sickle-cell disease (SCD) whose prevalence in Côte d’Ivoire is 21%. The main of this study was to compare scintigraphy, clinical and radiological observations to assess earlier diagnosis in SCD osteonecrosis. It was a prospective study about 45 SCD patients who presented coxopathy and had radio-labelled diphosphonates bone scintigraphy. The results revealed 49% of lesions whose 48% appeared wiyh homogeneous hyperfixation, 11% homogeneous hypofixation, 5% of hypofixation contourned by hyperfixation. Eighty-one percent of lesions concerned femoral head, 6% femoral condyle and 3% humoral head. Fifty percent of osteonecrosis was not visible in radiology and corresponded to the earlier stade. These invisible radiology aspects were observed in 100% hips without lameness, and in 43% permanent lameness. Scintigraphy (sensitive in 100%) isolated 38% more than conventional radiography. In main to improve SCD osteonecrosis prognostic in Côte d’Ivoire, this preliminary study outline that scintigraphy is fundamental in management.     

激素诱导血清病动物骨坏死模型中的脂类代谢异常

目的初步探讨血清病动物激素性骨坏死的发病机制。方法将新西兰大白兔分为三组,A组联合应用马血清和地塞米松磷酸钠诱导骨坏死模型,B组单纯应用地塞米松磷酸钠,C组应用生理盐水作为对照组,对三组实验兔股骨头进行HE、MRI观察,并对各组兔的血脂、AST和ALT进行检测,分析比较。结果A组出现了典型的股骨头缺血坏死改变,血脂、AST和ALT与另外两组相比差异有显著性。单纯应用激素组和对照组未出现股骨头缺血坏死。结论运用马血清和地塞米松磷酸钠可成功诱导出兔骨坏死模型,血管炎、血脂代谢异常和肝功能损害共同导致股骨头缺血坏死发生,短期应用大剂量激素难以诱导出骨坏死模型。     

Probing the alpha-sarcin region of Escherichia coli 23S rRNA with a cDNA oligomer.

The cause of 50S ribosomal subunit collapse reportedly triggered by hybridization of a 14-base cDNA probe to the alpha-sarcin region of 23S rRNA was investigated by physical measurement of probe-subunit complexes in varying buffer conditions. The results reported here show that this probe was unable to hybridize to its target site in the intact 50S subunit and the physical characteristics of 50S subunits remained unchanged in its presence. Subunit collapse was induced in buffer containing 20mM Tris-HCl (pH 7.5), 600 mM NH4Cl, 1 mM MgCl2, 1 mM DTT, and 0.1 mM EDTA in the absence of probe. The probe bound specifically to its target site in the collapsed particle, but did not promote further unfolding. The results demonstrate that a DNA probe bound to the alpha-sarcin region cannot cause the 50S subunit to unfold or cause 23S rRNA to degrade. We suggest that the previously reported collapse was most probably the result of the ionic conditions used.     

A stochastic two-stage carcinogenesis model: a new approach to computing the probability of observing tumor in animal bioassays.

A new definition of probability of observing tumor in animal bioassay is developed. It is derived from a two-stage stochastic model for carcinogenesis with time-dependent birth and death rates for cell proliferation. The model takes into account the method of collecting data on preneoplastic and neoplastic lesions. The new definition is appropriate for analyzing the presence or absence of tumors in animal bioassays.     

Investigation of temperature-dependent viscoelastic properties of thermal lesions in ex vivo animal liver tissue

The viscoelastic characteristics of thermal lesions in ex vivo animal liver are investigated in this paper. Characterization of the moduli of thermal lesions prepared at several temperatures will provide additional information for the elastographic monitoring of radio frequency ablation of hepatic tumors. In this study, the frequency-dependent complex modulus of thermal lesions prepared at temperatures ranging from 60 to 90 °C over a frequency range from 0.1 to 50 Hz are presented. Lesions were prepared using either radio frequency ablation or double immersion boiling. It was found that both the magnitude and phase of the modulus increase with frequency, a behavior that has been noted in the literature. A new result reported shows that the modulus dependence on temperature reveals a local maximum around 70–75 °C corresponding to the temperature at which tissue has released most of its water content. The modulus values at temperatures higher than 70 °C continued to increase, but the extent of increase depend on animal species and other factors.     

Spontaneous Osteonecrosis of the Knee in <Emphasis Type="Italic">Macaca mulatta</Emphasis>

Spontaneous osteonecrosis of the knee (SONK) is a common disease in elderly humans. Clinically, SONK presents with the sudden onset of severe knee joint pain, usually in the load-bearing area of the medial compartment of the knee. Articular cartilage lesions are secondary to subchondral trabecular bone necrosis. These biochemical and structural changes in the bone and cartilage alter the biomechanics of the joint, which may then lead to secondary osteoarthritis and ultimately joint destruction. We observed 3 cases of osteonecrosis affecting the knee joint of free-ranging Macaca mulatta (rhesus macaques). The histopathology of these cases consists of defects in the subchondral bone with articular cartilage necrosis and repair. The defects were associated histologically with secondary osteoarthritis in 2 cases. The osteonecrotic lesions in the macaques resemble closely spontaneous osteonecrosis of the knee as seen in humans. This is the first report of spontaneous osteonecrosis of the knee in nonhuman primates.     

Transcutaneous blood gas monitoring in the rat

Transcutaneous blood gas (TCBG) analysis is a noninvasive alternative method of estimation of blood gas tensions. The objective of the study reported here was to validate this method against standard blood gas (STBG) analysis in adult and juvenile Sprague-Dawley rats. We sought to establish the optimal TCBG probe site and temperature, to establish probe temperatures that would not cause thermal burns, to evaluate correlations between blood gas values (PaCO2 and PaO2) determined by use of TCBG and STBG, and to evaluate the sensitivity of the TCBG unit to changes in arterial blood gas partial pressures. Our results indicated that: in general, the xyphoid area was the optimal site for probe placement, with 44.5 degrees C being the optimal probe temperature for the highest correlation, but thermal burns may be a problem; probe temperatures of 42.5 degrees C (adults) and 42.0 degrees C (juveniles) do not cause thermal burns when left in place for three hours; probe temperatures of 44 degrees C (adults) and 42 degrees C (juveniles) resulted in moderate correlation between PaCO2 and PtcCO2; and the TCBG unit adequately responded to changes in arterial blood gas partial pressures. Neither PtcCO2 or PtcO2 reflect actual values of PaCO2 or PaO2, respectively. We concluded that TCBG analysis may be used as an indicator of change in PaCO2 with sufficient animal numbers under tightly controlled conditions, but not as an indicator of change in PaO2 in adult and juvenile rats.     

Use of Bifidobacterium dentium as an indicator of the origin of fecal water pollution

A new, simple, and specific protocol to discriminate between human and animal fecal pollution is described. The procedure is based on the detection of certain Bifidobacterium species in the samples. Two 16S rRNA gene-targeted probes are described. One of these probes (BDE) has as its target a region of the 16S rRNA gene of Bifidobacterium dentium, a Bifidobacterium species of exclusively human origin. The other probe (BAN) is based on the sequence of a region of 16S rRNA gene for several Bifidobacterium species related with animal origins. The specificity of both probes was evaluated by using 24 Bifidobacterium species, and their threshold detection limit was established by DNA-DNA hybridization. DNA-DNA hybridization with the BDE probe showed it to be specific for B. dentium, whereas that with the BAN probe showed it to be specific for B. animalis, B. asteroides, B. coryneforme, B. cuniculi, B. globosum, B. magnum, B. minimum, and B. subtile. A simple and specific protocol was also developed for the detection of their target species in environmental samples (sewage and feces). DNA-DNA hybridization with the BAN probe was only positive for samples from cattle and goats. Thus, this probe is not suitable for the identification of any animal fecal pollution. Whereas all samples with human fecal pollution showed a positive DNA-DNA hybridization result with the BDE probe, none of those with animal fecal pollution did. Therefore, this finding supports the potential use of this probe in detecting fecal pollution of human origin.     

骨源性细胞因子在激素性股骨头坏死发生发展中的研究进展

股骨头坏死是骨外科常见的难治性疾病,其机制仍有待研究.目前为止,医源性糖皮质激素是非创伤性股骨头坏死的主要原因.激素的长期使用可导致股骨头骨细胞凋亡、血液循环障碍所致缺血缺氧,最终导致股骨头塌陷.激素性股骨头坏死的发生发展与骨组织中细胞直接接触和其间接分泌的细胞因子调控相关.本文综述了骨组织中成骨细胞分泌的核因子κB受...     

Human Endogenous Retrovirus Protein Activates Innate Immunity and Promotes Experimental Allergic Encephalomyelitis in Mice

Multiple sclerosis (MS) is a complex multifactorial disease of the central nervous system (CNS) for which animal models have mainly addressed downstream immunopathology but not potential inducers of autoimmunity. In the absence of a pathogen known to cause neuroinflammation in MS, Mycobacterial lysate is commonly used in the form of complete Freund''s adjuvant to induce autoimmunity to myelin proteins in Experimental Allergic Encephalomyelitis (EAE), an animal model for MS. The present study demonstrates that a protein from the human endogenous retrovirus HERV-W family (MSRV-Env) can be used instead of mycobacterial lysate to induce autoimmunity and EAE in mice injected with MOG, with typical anti-myelin response and CNS lesions normally seen in this model. MSRV-Env was shown to induce proinflammatory response in human macrophage cells through TLR4 activation pathway. The present results demonstrate a similar activation of murine dendritic cells and show the ability of MSRV-Env to trigger EAE in mice. In previous studies, MSRV-Env protein was reproducibly detected in MS brain lesions within microglia and perivascular macrophages. The present results are therefore likely to provide a model for MS, in which the upstream adjuvant triggering neuroinflammation is the one detected in MS active lesions. This model now allows pre-clinical studies with therapeutic agents targeting this endogenous retroviral protein in MS.