Structural and Radiological Parameters for the Nondestructive Characterization of Trabecular Bone

Trabecular bone is characterized by compositional and organizational factors. The former include porosity at microlevel and mineralization. The latter refer to the trabecular architecture. Both determine the mechanical properties of the trabecular bone. The aim of this study is to investigate the relationship between the mechanical properties and the local HU value, the bone mineral density, the in vitro histomorphometric properties assessed by means of microcomputed tomography, and the Young's modulus determined by ultrasound measurement. Also the correlation between local HU values based on CT data of the full bone and HU values based on CT data of excised trabecular bone cylinders is investigated. Therefore density and strength related parameters of 22 trabecular bone cylinders retrieved from a fresh cadaver femur were measured by using different techniques. The mean HU value of the excised bone samples is very highly correlated with the pQCT density (R²=0.95) and the CT-based morphometric parameter BV/TV (R²=0.95). The mean HU values, determined from the CT images of the planned and excised bone samples, are less highly correlated (R²=0.75). The Young's modulus E_US determined from the ultrasound measurement is highly correlated with the maximal stress _max (R²=0.88) but not with the mechanically determined Young's modulus E_mech (R²=0.67). The maximal stress _max correlates well with the density parameters (R² varies between 0.76 and 0.86). On the contrary the mechanically determined Young's modulus E_mech does not correlate well with the density parameters (R² varies between 0.52 and 0.56). The absorbed energy E_abs during the deformation is only highly correlated with the maximal stress _max (R²=0.83). The inclusion of structural parameters besides a density related parameter did improve the prediction of the Young's modulus and the maximal stress. In conclusion, it seems that the HU value from clinical CT scanning is a good predictor of the local bone density and volume fraction. A combination of local density and a measure of the structural anisotropy is clearly needed to achieve good predictions of bone mechanics. © 2001 Biomedical Engineering Society. PAC01: 8719Rr, 8759Ls, 4380Ev, 8759Fm, 4335Zc, 8170Cv     

Detection of Helicobacter pylori in nasal and maxillary sinus specimens from patients with chronic sinusitis

OBJECTIVES: In patients with chronic sinusitis, the colonization of nasal and maxillary sinus tissues by Helicobacter pylori (HP) was investigated using polymerase chain reaction, urease test (CLO test), culture, and immunohistochemical analysis. STUDY DESIGN: A prospective clinical study. METHODS: The subjects were 11 patients aged 20 to 72 years with chronic sinusitis who had undergone sinus surgery under local anesthesia. In 7 of 11 patients, the HP status of the stomach was also studied. Nasal and maxillary sinus tissues were studied using polymerase chain reaction, urease test, culture, and immunohistochemical analysis. Helicobacter pylori infection of nasal and maxillary sinus tissues was defined by at least two positive results of different tests. RESULTS: Three (16%) of 19 nasal and maxillary sinus specimens from two patients were shown to be HP-positive (positive by polymerase chain reaction and immunohistochemical analysis and weakly positive by the CLO test). In one of these two patients, HP infection of the stomach was confirmed. In the other, a positive findings on immunohistochemical analysis suggested HP infection of the stomach. Immunoreactive structures were seen by immunohistochemical analysis in the nasal, maxillary sinus, and gastric specimens of these two patients but were partially degraded. CONCLUSION: Helicobacter pylori may exist in the nasal and maxillary sinus tissue specimens of some patients with chronic sinusitis with gastric HP infection.     

Spatial-temporal display of colour-flow ultrasound for the assessment of the effects of intermittent pneumatic compression in limbs

Colour-flow M-mode ultrasonography in three dimensions (two spatial, one temporal) was used to assess the effects of intermittent pneumatic compression on the blood flow velocities in the common femoral vein and artery. The linear array of a standard 3-D system was held in place over the vessels, to record while a calf and thigh cuff compressed to 60 mmHg. The data was reconstructed in 3-D and, subsequently, sliced in different planes. The technique effectively demonstrated the emptying of distal veins during compression, and hyperaemia in the artery on deflation, in the coronal and sagittal planes. Reconstructions of this type may be of use in visualising the distribution of flow changes within blood vessels. (E-mail: morrisrj@cf.ac.uk)     

保存异体睑板修复睑板缺损的临床观察

目的观察眼睑肿瘤术后保存异体睑板Ⅰ期修复睑板缺损的疗效。方法采用纯甘油保存的异体睑板,对58例眼睑肿瘤切除术后的患者行Ⅰ期睑板缺损修补术,用转位或滑行肌皮瓣和结膜瓣铺衬于异体睑板两侧。分析异体睑板的血运环境、异体睑板大小、保存时间与手术疗效的关系。术后随访3个月至10.5年,平均1.8年。结果58例中,43例异体睑板结膜瓣遮盖完全,术后1周异体睑板内可见新生血管,1个月后新生血管布满整个植片;15例异体睑板结膜瓣遮盖不全,术后2～3个月新生血管长满植片,而裸露部位的植片表层可见不同程度的融解。不同大小结膜瓣间的植片愈合效果比较,差异有显著性（χ     

Stathmin levels in growth plate chondrocytes are modulated by vitamin D3 metabolites and transforming growth factor-beta1 and are associated with proliferation

Stathmin is a highly conserved, phosphorylated cytosolic protein that is found at decreased levels in all cells as they become more terminally differentiated, or when they decrease in their rate of proliferation. This study examined the hypothesis that stathmin levels in growth plate chondrocytes decreases as endochondral maturation increases. To test this hypothesis, we used a costochondral growth plate chondrocyte cell culture model. Cells derived from the resting zone (RC) express twice as much stathmin mRNA in culture and have twice as much stathmin protein as cells derived from the post proliferative growth zone ([GC];prehypertrophic and upper hypertrophic cell zones). Stathmin levels in vivo were assessed by immunohistochemistry. To assess the effects of agents that modulate proliferation and differentiation, RC and GC chondrocytes were cultured in the presence of 10⁻¹⁰ to 10⁻⁸ M 1α,25-(OH)₂D₃, which regulates proliferation in both cell types but affects differentiation of only GC cells, or 10⁻⁹ to 10⁻⁷ M 24R,25-(OH)₂D₃, which regulates differentiation and maturation of RC cells, but decreases proliferation of GC cells. In addition, RC cells were treated with 0.44 or 0.88 ng/mL of recombinant human transforming growth factor β1 (rhTGF-β1), which stimulates proliferation of RC cells and regulates proteoglycan production, but not alkaline phosphatase activity. Stathmin protein levels were determined using quantitative immunoblots, with recombinant human stathmin as a standard. The results show that stathmin levels are associated with proliferation. Proliferating chondrocytes in vivo exhibited higher levels of immunoreactive stathmin than either RC or GC cells in the growth plate. In culture, 1α,25-(OH)₂D₃ caused a dose-dependent de-crease in stathmin in RC and GC cells within 24 h. 24 R, 25-(OH)₂D₃ also reduced stathmin levels in GC cells within 24 h but only affected RC cells after prolonged exposures (96 h), at which time RC cells express a GC-like phenotype. rhTGF-β1 caused an increase in stathmin levels in RC cells. Stathmin levels are sensitive to protein kinase C (PKC) in other cells. Inhibition of PKC with chelerythrine had no effect on the response of RC cells to 1α,25-(OH)₂D₃ but it blocked the effect of rhTGF-β1, indicating that decreases in stathmin by vitamin D₃ metabolites may not be modulated by PKC, whereas increases in stathmin via rhTGF-β1 may be regulated via a PKC-dependent mechanism. These results support the hypothesis that constitutively expressed levels of stathmin are related to cell maturation state and that they are modulated by factors that regulate proliferation.     

Percutaneous Excision of a Facet Joint Cyst Under CT Guidance

We report a patient with a cyst of the posterior inter-articular joint that was decompressed using a bone biopsy Temno needle.     

颈椎单开门扩大成形术后脊髓信号强度变化作用的临床观察

目的探讨颈脊髓压迫性病变中MRI髓内信号强度的改变与临床症状及疾病预后的关系。方法对选取的46例颈脊髓压迫性病变的病人进行多因素分析。结果术前正常信号/正常信号(N/N)组有13例,正常信号/高信号(N/Hi)组有26例,纯信号/高信号(Lo/Hi)组有7例。随访时Lo/Hi组恢复率明显低于其他两组,术前脊髓最大受压处的横截面积在N/N组、N/Hi与Lo/Hi组之间差异显著,术后JOA评分3组之间也有差异。结论脊髓受压后出现的髓内信号强度的改变,多表现为T2加权序列高信号,单独出现预示脊髓有一定的修复功能,但如同时出现T1加权序列改变则预后不良。     

粘弹性条件下槽道板结构的准静态弯曲变形

引入小挠度薄板理论,将槽道板结构简化作支承于地基上的薄板,基于对应性原理和数值逆变换方法,以微槽道换热器为例,解析计算了槽道板结构的粘弹性弯曲变形和粘弹性弯曲应力,并与有限元模拟结果进行对比,由此验证用该解析计算方法分析承压槽道板结构粘弹性能的可行性与准确性。结果表明:解析计算结果与有限元模拟结果基本一致,该方法可作为承压槽道板结构设备力学设计的有效方法。     

微创经皮干骺端锁定加压钢板固定治疗胫骨远端骨折

目的:探讨微创经皮干骺端锁定加压钢板(LCP)治疗胫骨远端骨折的方法和疗效.方法:应用间接复位技术,采用AO新型干骺端锁定加压接骨板内固定治疗本院11例胫骨远端骨折,并随访观察疗效.结果:所有病例得到随访,时间为6～12个月,伤口均一期愈合,未出现皮肤坏死及感染;骨痂出现于术后4～8周,骨折骨性愈合为术后4～6.5个月,未出现骨折延迟愈合、畸形愈合与短缩.1例术后再次跌倒致钢板变形和骨折移位,手术取出钢板后重新行微创干骺端锁定加压钢板内固定;余未出现钢板断裂、松动及断钉现象.结论:微创经皮干骺端锁定加压钢板治疗胫骨远端骨折手术创伤少,对骨折处生物学完整性影响小,疗效满意.     

空心加压钛螺钉治疗股骨颈骨折

目的 观察空心加压钛螺钉治疗股骨颈骨折的治疗效果。方法 行股外侧切口，骨折复位满意后在导向器引导下沿股骨颈方向平行拧入双枚空心加压钛钉，术后患肢皮牵引或丁字鞋维持外展中立约4-6wk。结果 本组37例患者平均随访2．6a，1例术后第7wk出现退钉，3例出现股骨头坏死，1例出现骨折不愈合，余32例骨折均愈合。结论 空心钛钉治疗股骨颈骨折具有手术创伤小、操作简单、固定可靠及骨折愈合率较高等优点，适合于中青年股骨颈骨折患者和不能耐受较大手术的老年患者。