The effect of ball milling grinding pathways on the bulk and reactivity properties of calcium phosphate cements

Calcium phosphate cements (CPCs) are significant alternatives to autologous bone grafting. CPCs can be composed of biphasic or multiphase calcium phosphate (CaP) compounds. A common way to process CPCs is by ball milling. Ball milling can be used for grinding or mechanosynthesis. The aim of this study was to determine the effect of well-defined ball milling grinding parameters, applied via different milling pathways, on the properties of CPCs. Starting CaP compounds used included α-tricalcium phosphate, dicalcium phosphate anhydrous and precipitated hydroxyapatite. Scanning electron microscopy showed changes in the powder morphology, which were related to the behavior of the starting CaP materials. Specific surface area (SSA) and particle size (PS) measurements exposed the effect of ball milling on the CaP compounds and CPC powders. X-ray diffraction revealed no effect of ball milling pathways or milling time on the composition of CPCs or the starting materials, but affected their crystallographic properties. No contamination of the milling media or transformation into an amorphous calcium phosphate compound was found. The milling pathways affected setting and cohesion. Fourier transform infrared spectroscopy (FTIR) revealed differences on the CPC v?-PO?3? bands according to the interaction, created between the CaP compounds by the milling pathways. FTIR confirmed that the milling pathways changed the crystallographic properties. This study demonstrates that the pathways used for milling grinding modify the PS, SSA, and crystallographic properties of the powders, without affecting their composition. These modifications affected the bulk and reactivity properties of the CPCs by creating different setting and cohesion behaviors.     

A New Method to Prepare Maleic Anhydride Grafted Poly(propylene)

Summary: A new method to prepare maleic anhydride grafted poly(propylene) (MAPP) was developed successfully. The grafting reaction of maleic anhydride (MA) onto poly(propylene) (PP) was performed with the aid of ball‐milling, and the grafting mechanism was proposed based on the experimental results. MAPP was prepared by ball‐milling of PP powder, MA, and peroxide initiator in balls‐containing jars with a planetary ball mill for a certain time. Factors were considered on reaction time, rotational speed of the mill, cyclic milling mode, kind and concentration of peroxide, and concentration of MA. Results show that MAPP obtained contains the main structures of end‐grafting type (both single and oligomeric) and bridge‐grafting type. Compared with the conventional melt‐mixing method, MAPP obtained through the ball‐milling method reveals alleviated degradation of PP or even increased molecular weight of resultant MAPP. This novel method has also the advantages of lower process temperature and solventless, energy efficient, low cost and simple running process. Furthermore, it is very easy to get purified products.

Key steps for preparing MAPP through ball‐milling.     

The effect of immobilization on myotendinous junction: an ultrastructural,histochemical and immunohistochemical study

Kannus , P., Jozsa , L., Kvist , M., Lehto , M. & Järvinen , M. 1992. The effect of immobilization on myotendinous junction: an ultrastructural, histochemical and immunohistochemical study. Acta Physiol Scand 144 , 387–394. Received 28 April 1 991 , accepted 13 October 1991. ISSN 0001–6772. Tampere Research Station of Sports Medicine, UKK-Institute, and Department of Surgery, Tampere University Central Hospital, Tampere, Finland; Department of Morphology, National Institute of Traumatology, Budapest, Hungary; and Sports Medical Research Unit, Paavo Nurmi Center, University of Turku, Turku, Finland. The effect of immobilization on the myotendinous junction of the calf muscles in the rat was studied histochemically, immunohistochemically and morphometrically with a transmission electron microscope. After 3 weeks of immobilization, the contact area between the muscle cells and tendineal collagen fibres was reduced by almost 50% in both type I (slow-twitch) and type II (fast-twitch) muscle fibres. The terminal finger-like processes of the muscle cells became shallow and cylindrical or were completely atrophied. Their basal membranes were slightly thickened. Histochemically, the most remarkable alteration in the myotendinous junction was the marked decrease in the sulphate containing glyco-saminoglycans. In the basal lamina of the muscle fibres, the glycosaminoglycan and proteoglycan content was also reduced. Immunohistochemical analyses revealed that the amount of type III collagen was markedly increased on the myotendinous interface, but the amount and distribution of type I collagen was not affected by immobilization. These findings suggest that immobilization causes degenerative changes at the myotendinous junction, which, in turn, most likely decrease its tensile strength and may predispose it to rupture during activity.     

人皮肤经络线上P物质和VIP免疫反应神经纤维与肥大细胞关系的光镜和电镜研究

本研究在已发现神经与肥大细胞之间有突触样联接关系的的基础上,检查了与肥大细胞形成联接的神经纤维终末内是否含有P物质和血管活性肠肽(VIP)。证明:光镜下P物质免疫反应阳性神经纤维与肥大细胞直接接触;将光镜看到的目的物用原位包埋法转到电镜下,可见P物质免疫反应轴索与肥大细胞紧密并靠,两者之间距离不超过20nm。含P物质免疫反应囊泡的轴突末梢在近肥大细胞处形成膨大,有的膨大部直接与肥大细胞接触,形成突触样联接。证实了前人关于与肥大细胞形成联接的轴突末梢内含有P物质的推断。此外,在光镜下证明的P物质和VIP免疫反应神经纤维在皮肤的分布与前人的报道一致,本实验并观察了它们在电镜下的结构特点。     

不同分散介质研磨所得纳米珍珠粉的比较

文题释义：纳米材料：物质结构在三维空间中至少有一维处于纳米尺度，或由纳米结构单元构成的且具有特殊性质的材料。在最新的一项纳米碳酸钙标准中，要求颗粒平均粒径≤100 nm。 纳米珍珠粉：以无水乙醇或水作为分散介质球磨细化珍珠粉，研磨介质为0.1 mm氧化锆球，通过扫描电镜、透射电镜、X射线衍射仪检测分析珍珠粉粒径，珍珠粉平均晶粒、平均粒径<100 nm，属于纳米材料。 背景：为了保留更多的有机质及材料生物学活性，需通过物理方法研磨细化珍珠粉。球磨法可以最大限度地保留珍珠粉中的有机质及其活性，而不同分散介质球磨制备的纳米材料效果不同。 目的：对以蒸馏水和无水乙醇两种分散介质研磨所得的纳米珍珠粉进行对比。 方法：分别以无水乙醇与水作为分散介质研磨制备纳米珍珠粉，采用扫描电镜、透射电镜、X射线衍射仪、凯氏定氮法及食品中氨基酸测定等方法比较分析研磨前后的珍珠粉。 结果与结论：①以无水乙醇为分散介质制备的纳米珍珠粉主要为类圆形颗粒，大小不等，主要分布在30-50 nm，平均晶粒20 nm，方解石碳酸钙相对百分比增至7%，蛋白质和氨基酸含量未发生明显变化；②以蒸馏水为分散介质制备的纳米珍珠粉主要为类圆形颗粒，存在较大的条状或块状不规则颗粒，大小不均，平均晶粒30 nm，方解石碳酸钙相对百分比增至10%，蛋白质和氨基酸含量有所减少；③结果表明两种分散介质研磨后珍珠粉粒度有明显差异，以无水乙醇为分散介质研磨的珍珠粉粒度更细更均匀。 ORCID: 0000-0002-9436-3464(毛秋华) 中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程     

Detection of cortical malformations using enhanced synthetic contrast images derived from quantitative T1 maps

The detection of cortical malformations in conventional MR images can be challenging. Prominent examples are focal cortical dysplasias (FCD), the most common cause of drug‐resistant focal epilepsy. The two main MRI hallmarks of cortical malformations are increased cortical thickness and blurring of the gray (GM) and white matter (WM) junction. The purpose of this study was to derive synthetic anatomies from quantitative T1 maps for the improved display of the above imaging characteristics in individual patients. On the basis of a T1 map, a mask comprising pixels with T1 values characteristic for GM is created from which the local cortical extent (CE) is determined. The local smoothness (SM) of the GM‐WM junctions is derived from the T1 gradient. For display of cortical malformations, the resulting CE and SM maps serve to enhance local intensities in synthetic double inversion recovery (DIR) images calculated from the T1 map. The resulting CE‐ and/or SM‐enhanced DIR images appear hyperintense at the site of cortical malformations, thus facilitating FCD detection in epilepsy patients. However, false positives may arise in areas with naturally elevated CE and/or SM, such as large GM structures and perivascular spaces. In summary, the proposed method facilitates the detection of cortical abnormalities such as cortical thickening and blurring of the GM‐WM junction which are typical FCD markers. Still, subject motion artifacts, perivascular spaces, and large normal GM structures may also yield signal hyperintensity in the enhanced synthetic DIR images, requiring careful comparison with clinical MR images by an experienced neuroradiologist to exclude false positives.     

连接蛋白基因一个新致聋突变体p.Y155X及功能分析

目的 观察连接蛋白(connexin 26,CX26)基因的一个新致聋突变c.465T→A,P.Y155X,在体外表达细胞功能的改变,以探讨其致聋的可能机理.方法 常染色体隐性遗传耳聋家系的先证者外周血抽提DNA,DNA直接测序法分析CX26基因突变.将在该家系发现的突变c.465T→A,P.Y155X和野生型CX26(wtCX26)定向克隆到pEGFP-N1质粒,构建CX26 p.Y155X-EGFP及wtCX26-EGFP融合蛋白表达载体,转染HeLa细胞,Western印迹分析蛋白的表达,共聚焦显微镜观察突变蛋白和野生型CX26在HeLa细胞的定位及有无间隙连接斑形成,染料转移实验分析间隙连接的功能.结果 在该耳聋家系发现CX26基因一个新的致聋突变:c.465T→A,P.Y155X.CX26 P.Y155X突变体在HeLa细胞表达的突变蛋白的分子量小于野生型蛋白分子量;突变蛋白在细胞质表达,不能分布到细胞膜和形成间隙连接,无染料转移.野生型表达于细胞膜并形成间隙连接斑,能转移染料.结论 CX26 P.Y155X突变体在翻译后不能从细胞内转运到细胞膜,不能形成间隙连接通道.CX26基因c.465T→A,P.Y155X导致常染色体隐性遗传性聋.     

Junction between the great cerebral vein and the straight sinus: an anatomical, immunohistochemical, and ultrastructural study on 25 human brain cadaveric dissections

The cerebral venous system is poorly understood, and best appreciated under macroscopic anatomical considerations. We present an anatomical and immunohistochemical studies to better define the morphological characteristics of the junction between the great cerebral vein and the straight sinus. Twenty-five cadaveric specimens from the anatomy laboratory of the University Victor Segalen of Bordeaux were studied. The observation of the venous junctions with the straight sinus was performed under an operating microscope. The smooth muscular actin immunohistochemical staining was performed for 18 veno-sinosal junctions. Five venous junctions were observed using an electron microscope. We observed 3 different anatomic aspects: type 1 was a junction with a small elevation in its floor and a posterior thickening (14 cases); type 2 was a junction with an outgrowth on the floor like a cornice (7 cases); and type 3 was a junction presenting a nodule. Microscopic study of type 1 and 2 junctions showed a positive coloration to orceine attesting the presence of elastic fibers. Immunohistochemistry revealed the presence of smooth muscular actin and S 100 protein attesting the presence of smooth muscular fibers and nervous fibers. We observed in the ultrastructural study, a morphological progression of the endothelium. The venous orifice of the great cerebral vein into the straight sinus could be anatomically assimilated as a true "sphincter." Its function in the regulation of the cerebral blood flow needs further exploration.     

Influence of touching an object on corticospinal excitability during motor imagery

We investigated whether corticospinal excitability during the imagery of an action involving an external object was influenced by actually touching the object. Corticospinal excitability was assessed by monitoring motor evoked potentials (MEPs) in the first dorsal interosseous muscle following transcranial magnetic stimulation over the motor cortex during imagery of squeezing a ball—with or without passively holding the ball. The MEPs amplitude during imagery when the ball was held was larger than that when the ball was not held. The MEPs amplitude was not modulated just by holding the ball. In the same experimental condition, the somatosensory evoked potentials (SEPs) in response to the stimulation of median nerve were not modulated by motor imagery or by holding the ball. These results suggest that the corticospinal excitability during imagery of squeezing a ball is enhanced with the real touch of the ball, and the enhancement would be caused by some changes along the corticospinal pathway itself and not by the change in responsiveness along the afferent pathway to the primary somatosensory cortex.     

血管壁切应力变化对动脉内皮细胞间连接的影响

目的：探讨动脉血流受阻后管壁切应力变化对动脉内皮细胞连接的影响。方法：60只实验兔建立颈总动脉血流减少模型,在术后0至30天8个不同时相点,制作血流减小后的颈总动态超薄切片,透射电镜下观察内皮细胞间连接和细胞形态学变化。结果：动脉内皮细胞间连接结构及稳定性随血管壁切应力的变化而发生相应改变。3天后,在部分细胞间近腔面出现间隙;细胞间紧密连接不象正常对照那样完好而致密,胞质内未见微丝附着;可见部分动脉壁内皮细胞脱离基底膜或完全脱落人管腔。在血管壁切应力递增阶段,近腔面内皮细胞间隙消失,可见窄而短的闭锁带。结论：血管壁切应力的降低可导致动脉内皮细胞间连接结构发生改变,细胞稳定发生减小。提示低血流的切应力变化可能破坏动态内皮细胞屏蔽的完整性。     

缓激肽对脑胶质瘤大鼠紧密连接影响的形态学观察

目的研究缓激肽(BK)对脑胶质瘤大鼠血肿瘤屏障紧密连接的影响。方法采用伊文氏兰(EB)法检测缓激肽作用后血肿瘤屏障(BTB)通透性的变化;应用透射电镜(TEM)观察BK作用后内皮细胞间紧密连接的变化,同时应用硝酸镧[La(NO3)3]和辣根过氧化物酶(HRP)作示踪剂,检测缓激肽作用后,小分子和大分子示踪剂通过紧密连接的情况。结果缓激肽可使血肿瘤屏障对伊文氏兰的通透性增加,在15min时达到高峰,以后逐渐下降。透射电镜显示缓激肽作用15min时,肿瘤组织毛细血管内皮细胞间紧密连接的完整性明显破坏,缝隙指数显著增加,同时可见硝酸镧和辣根过氧化物酶在紧密连接处沉积。结论缓激肽能够通过开放紧密连接选择性增加血肿瘤屏障的通透性。     

Junctional complexes of the blood-testis barrier in the Japanese quail (Coturnix Coturnix japonica)

This study investigated the developmental changes in the adherens junctions, gap junctions, as well as tight junctions forming the blood-testis barrier (BTB) in Japanese quail (Coturnix Coturnix japonica) testis. Testicular tissue from pre-pubertal, pubertal, adult, and aged Japanese quail were examined by immunohistochemistry and transmission electron microscopy (TEM). The tight junction proteins claudin-3, claudin-11, occludin and zonula occludens-1 (ZO-1), were generally localised in the cytoplasm of Sertoli cells, spermatogonia, and spermatocytes of pre-pubertal, pubertal, some adult birds. The adherens junction protein E-cadherin had a similar distribution pattern. During pre-pubertal development, the gap junction protein connexin-43 (Cx43) was only localised between Leydig cells in the testicular interstitium. However, TEM revealed the presence of gap junctions between cells of the seminiferous epithelium as early as the pre-pubertal stage. Furthermore, TEM confirmed the presence of tight and adherens junctions in the seminiferous epithelia of all age groups. The findings of this study document age-related differences in the immunolocalisation and intensity of the junctional proteins and the ultrastructure of the junctional complexes forming the BTB in quail testes. Additionally, the junctional complexes forming the BTB in the Japanese quail are well established prior to puberty. This study provides baseline information for the future evaluation of pathological changes in the BTB of avian species at different developmental stages.     

采用MRF二次混合多阶先验的PET图像的贝叶斯重建

在正电子发射成像（肿）中，很多方法被用来抑制重建图像中的噪声效果，其中。在所有方法中，贝叶斯重建或者最大化后验估计的方法被证明具有在重建图像质量方面相对于其他方法的优越性。基于贝叶斯重建，本研究提出了一种应用于贝叶斯重建中新的综合了二次一阶先验和二次二阶先验的马尔可夫随机场混合多阶先验。基于不同阶数的二次平滑先验的自身的不同性质，该新先验的设计的目的是实现自适应的发挥这些算子的作用。该混合先验能够保持其先验能量函数凸性，从而保证整体目标贝叶斯后验能量函数的凹性。模拟实验和实验结果的比较证明了对于PET重建，该先验在抑制背景噪声和保持边缘方面均具有很好的表现。     

Morphogenesis of the myoneural junctions after immobilization of the muscle in the rat

Summary Immobilization of the tibialis anterior muscle of the newborn rat was caused by amputation of the hind limb at the talocrural joint. Subsequent muscular atrophy was measured by weighing the muscle and the myoneural morphogenesis in the disused muscle was studied in light and electron microscope. The acetylcholinesterase (AChE; E.C.3.1.1.7) and nonspecific cholinesterase (Ns. ChE; E.C.3.1.1.8) activity at the myoneural junction was followed histochemically.It was observed that the myoneural morphogenesis proceeded normally in the immobilized and atrophied muscle. Cholinesterase activities at the developing myoneural junction were identical on both the immobilized and the contralateral control side.The myoneural morphogenesis may be solely controlled by the nerve since, at the light of the present observations, the abnormally diminished function of the muscle seems to have no effect on the myoneural development.     

导航联合内镜辅助远外侧入路的解剖学研究

目的　探讨导航联合内镜辅助远外侧入路的可行性及对颅颈交界区腹侧解剖学特点的观察。 方法　对6例（12侧）尸头标本模拟远外侧入路，分别用显微镜、0度和30度内镜观察，随后磨除后内侧1/3枕髁和颈静脉结节，再次用显微镜观察（其中内镜下观察和磨除颅底骨性结构均在导航引导下完成），比较这四种方式对颅颈交界区腹侧显露的差异。 结果　导航联合内镜能够通过面听神经、后组颅神经组成的上、中、下3个间隙近距离观察颅底结构，还能观察被颈静脉结节和枕髁遮挡的神经血管，与远外侧经髁入路显露范围相似。 结论　在内镜和神经导航辅助下，远外侧入路能够良好的观察颅颈交界区腹侧的神经血管结构，避免磨除颈静脉结节和枕髁，减少手术创伤。     

Effect of process control agent on the porous structure and mechanical properties of a biomedical Ti–Sn–Nb alloy produced by powder metallurgy

The influence of different amounts and types of process control agent (PCA), i.e., stearic acid and ethylene bis-stearamide, on the porous structure and mechanical properties of a biomedical Ti–16Sn–4Nb (wt.%) alloy was investigated. Alloy synthesis was performed on elemental metal powders using high-energy ball milling for 5 h. Results indicated that varying the PCA content during ball milling led to a drastic change in morphology and particle-size distribution of the ball-milled powders. Porous titanium alloy samples sintered from the powders ball milled with the addition of various amounts of PCA also revealed different pore morphology and porosity. The Vickers hardness of the sintered titanium alloy samples exhibited a considerable increase with increasing PCA content. Moreover, the addition of larger amounts of PCA in the powder mixture resulted in a significant increase in the elastic modulus and peak stress for the sintered porous titanium alloy samples under compression. It should also be mentioned that the addition of PCA introduced contamination (mainly carbon and oxygen) into the sintered porous product.     

Effect of ball milling on the processing of bone substitutes with calcium phosphate powders

Decreasing the microscale morphology of synthetic bone substitutes is of primary importance in order to enhance the morphology of the surface of the material, which is directly in contact with osteoconductive cells when it is implanted in bone. The aim of this study was to investigate the influence of ball milling of slurries on the microscale morphology of hydroxyapatite and tricalcium phosphate bone substitutes and the influence on their processing. Ball milling appeared to be a successful method in order to raise the sintering reactivity of the powders, that is, to decrease the sintering temperature and microstructural morphology of the material. However, it was demonstrated that ball milling had a great influence on dispersion, which became very difficult under long milling times because of dissolution of the calcium phosphate powders. Due to dissolution, ionic species were generated in the slurry and interfered with the dispersing agent. Moreover a reprecipitation process occurred simultaneously, and large particles of the most stable phase (HAP) formed. The presence of such large particles generated stress gradients and cracks in the material during the sintering stage.     

内镜下经口咽入路至颅颈交界应用解剖学研究

目的研究内镜下经口咽入路至颅颈交界区域局部解剖学并测量相关解剖数据,为临床手术提供形态学数据。方法交替使用手术显微镜和0°、30°硬质内镜研究10例成人尸头,探讨经口咽至颅颈交界手术入路;测量与入路相关的60具成人颅骨标本数据。结果该入路的定位标志,即“路标”主要为寰椎前结节、齿突、咽结节、枕骨大孔前缘、IX～Ⅻ对脑神经、椎动脉及其分支、延髓等;沿途“路标”构成该入路的操作路线图。结论(1)解剖数据对于临床手术具有参考价值;(2)应用不同角度的内镜,仅切开软腭足以达斜坡下部至第2颈推的范围,应用特殊手术器械可完成上述区域病变的治疗。     

脑震荡大鼠脑干神经纤维组织病理与超微结构损伤后64天动态改变观察

本研究运用光镜和透射电镜方法,对脑震荡(brain concussion,BC)大鼠的脑干锥体束神经纤维的组织病理与超微结构的动态变化进行了观察。27只BC大鼠随机分为致伤后3、12、24h和2、4、8、16、32、64d九个实验组,另设正常对照组,每组3只动物。光镜轴索银染结果显示:BC后轴索结构变化表现为直径增粗,或呈串珠状、畸形状或收缩球样改变,或染色不均;间质水肿等。透射电镜显示:轴索超微结构在BC后3h髓鞘开始水肿并出现不同程度的分离,纤维周围及胶质细胞水肿,毛细血管扩张淤血或闭塞、血小板血栓形成等。BC后12h开始出现部分轴索的溶解,BC后4~32d髓鞘水肿腔隙明显、增厚显著,直到伤后64d脑干神经轴索仍未恢复正常。以上结果表明脑震荡大鼠存在较长时程的脑干不同程度的神经轴索损伤。     

Discerning alumina ball wear from confounding metal transfer artifact

On dismounting a ceramic femoral ball from its metal trunnion, there is usually a range of gray metallic bands transferred to the trunnion bore inside the ball. This creates an artifact that may compromise detection by weight of the exceedingly low wear rates of ceramic balls. The objective of this study was to compare the weight trending of the metal trunnions and their ceramic balls during conditioning studies. Our hypothesis was that a pretest conditioning protocol would eliminate or greatly reduce the metal transfer artifact. The balls and tapers were placed on a hip simulator under 300-600 load cycles but with no articulation. The balls were then dismounted from the trunnions, and both were cleaned and weighed. This was repeated 6-23 times. We developed a novel hydraulic method for dismounting balls from trunnions that proved to be safe and efficient. There was significant weight loss in the trunnions after the ball removal, but there was no corresponding weight gain in the alumina balls. The weight effect of the metal transfer appeared to have been removed from the balls with our standard cleaning procedures. Therefore, wear rates for alumina balls may be gravimetrically determined without compensating for the metal transfer from trunnion to ball.