Bionic Mineralized 3D-Printed Scaffolds with Enhanced In Situ Mineralization for Cranial Bone Regeneration

In situ mineralization is a promising strategy to mimic the physicochemical properties of biominerals and is widely applied in the field of bone repair. Given the high requirement for substance exchange in cranial bone regeneration, in situ mineralized organic–inorganic hybrid materials exhibit advantages. However, the integration of remarkable mineral content, mechanical properties, and osteogenic properties also remains a major challenge. Herein, enhanced in situ mineralization through combining the enzymatic and anion-boosted mineralization is applied to promote the mineralization efficiency, mineral content, and mechanical properties. Based on the results of computational calculations and in vitro mineralization experiments, the mechanism of mineralization enhancement is investigated from the perspectives of nucleation sites and the saturation of in situ mineralization. Anionic polyaspartic acid (pAsp) can increase the saturation of in situ mineralization; enzymatic mineralization shows high efficiency, with minerals of low crystallinity. The changes in the properties of the minerals effectively enhance the biological properties of 3D-printed scaffolds, as confirmed by cell proliferation/differentiation experiments in vitro and in cranial bone regeneration in vivo. This strategy provides a new thinking for the preparation of bionic mineralized scaffolds for cranial bone repair, and can greatly promote the efficiency of bone regeneration.     

人工神经网络发展的基础和研究方法

本文阐述了人工神经网络的概括定义、研究方法、发展的基础以及这些基础与信息处理的关系,试图从思想或概念上使信息处理系统的设计者懂得在使用人工神经网络技术设计信息处理系统时,究竟那些特性总是实质性的和必不可少的;并了解人工神经网络与信息处理在数学本质上的联系,进而让人们知道究竟那些问题更适于用人工神经网络技术来解决。     

Caecilian jaw-closing mechanics: integrating two muscle systems

Caecilians (Lissamphibia: Gymnophiona) are unique among vertebrates in having two sets of jaw-closing muscles, one on either side of the jaw joint. Using data from high-resolution X-ray radiation computed tomography scans, we modelled the effect of these two muscle groups (mm. levatores mandibulae and m. interhyoideus posterior) on bite force over a range of gape angles, employing a simplified lever arm mechanism that takes into account muscle cross-sectional area and fibre angle. Measurements of lever arm lengths, muscle fibre orientations and physiological cross-sectional area of cranial muscles were available from three caecilian species: Ichthyophis cf. kohtaoensis; Siphonops annulatus; and Typhlonectes natans. The maximal gape of caecilians is restricted by a critical gape angle above which the mm. levatores mandibulae will open the jaw and destabilize the mandibular joint. The presence of destabilizing forces in the caecilian jaw mechanism may be compensated for by a mandibular joint in that the fossa is wrapped around the condyle to resist dislocation. The caecilian skull is streptostylic; the quadrate–squamosal complex moves with respect to the rest of the skull. This increases the leverage of the jaw-closing muscles. We also demonstrate that the unusual jaw joint requires streptostyly because there is a dorsolateral movement of the quadrate–squamosal complex when the jaw closes. The combination of the two jaw-closing systems results in high bite forces over a wide range of gape angles, an important advantage for generalist feeders such as caecilians. The relative sizes and leverage mechanics of the two closing systems allow one to exert more force when the other has a poor mechanical advantage. This effect is seen in all three species we examined. In the aquatic T. natans, with its less well-roofed skull, there is a larger contribution of the mm. levatores mandibulae to total bite force than in the terrestrial I. cf. kohtaoensis and S. annulatus.     

Anterior and middle cranial fossa in traumatic brain injury: Relevant neuroanatomy and neuropathology in the study of neuropsychological outcome.

The frontal and temporal lobe regions of the brain have a high vulnerability to injury as a consequence of cerebral trauma. One reason for this selective vulnerability is how the frontal and temporal regions are situated in the anterior and cranial fossa of the skull. These concavities of the skull base cup the frontal and temporal lobes which create surface areas of contact between the dura, brain, and skull where mechanical deformation injures the brain. In particular, the sphenoid ridge and the free-edge of the tentorium cerebelli are uniquely situated to facilitate injury to the posterior base of the frontal lobe and the anterior pole and medial surface area of the temporal lobe. Three-dimensional image reconstruction with computerized tomography and magnetic resonance imaging are used to demonstrate the vulnerability of these regions. How neuropsychological deficits result from damage to these areas is reviewed and discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

46例坐位开颅手术的围手术期护理体会

目的坐位手术是神经外科用于后颅窝,高颈段脊髓和部分松果本肿瘤切除的主要体位之一。方法优点为暴露好,术中出血少,术者操作方便。结果由于术式特点,术中易引起体位性和失血性低血压,手术野高于心脏水平,静脉压相对较低,空气易进入静脉内引起空气栓塞。结论术后易发生颅内血肿,故切实做好围手术期护理至关重要。     

IV and IP administration of rhodamine in visualization of WBC‐BBB interactions in cerebral vessels

Epi‐illuminescence intravital fluorescence microscopy has been employed to study leukocyte‐endothelial interactions in a number of brain pathologies. Historically, dyes such as Rhodamine 6G have been injected intravenously. However, intravenous injections can predispose experimental animals to a multitude of complications and requires a high degree of technical skill. Here, we study the efficacy of injecting Rhodamine 6G into the peritoneum (IP) for the purpose of analyzing leukocyte‐endothelial interactions through a cranial window during real time intravital microscopy. After examining the number of rolling and adherent leukocytes through a cranial window, we found no advantage to the intravenous injection (IV). Additionally, we tested blood from both routes of injection by flow cytometry to gain a very precise picture of the two methods. The two routes of administration failed to show any difference in the ability to detect cells. The study supports the notion that IP Rhodamine 6G works as efficaciously as IV and should be considered a viable alternative in experimental design for investigations employing intravital microscopy. Facilitated intravital studies will allow for more exploration into cerebral pathologies and allow for more rapid translation from the laboratory to the patient with less chance of experimental error from failed IV access. Microsc. Res. Tech. 78:894–899, 2015. © 2015 Wiley Periodicals, Inc.     

Regional metabolite levels of the normal posterior fossa studied by proton chemical shift imaging

MR spectroscopy of the posterior fossa is pitted with numerous technical difficulties. It is, however, of great clinical interest in the study of the degenerative diseases and tumors of this area. We have developed a method to perform 2D CSI of this area, by using a sagittal slice and a careful positioning of outer volume saturation. We performed this acquisition in 30 healthy volunteers to determine the normal metabolic ratios in five voxels of this area (mesencephalon. pons. medulla oblongata, vermis, cerebellar white matter). The main technical difficulty was magnetic field inhomogeneity in the lower brainstem generated by dental alloys. However, 88% of the voxels were of sufficient quality to be analyzed. The statistically significant regional variations were a higher NAA/Cr ratio in the pons than in the medulla oblongata, higher Cho/Cr in the pons than in the mesencephalon and higher Cho/ Cr in the cerebellar white matter than in the vermis. We conclude that 2D CSI of the brainstem, although technically delicate can be performed in most patients.     

钛合金颅骨修复体的多点成形数值模拟

采用动态显式有限元软件,针对钛合金网板与压力机基本体直接接触、在基本体和钛合金网板之间放置聚氨酯弹性垫、在基本体和钛合金网板之间放置聚氨酯弹性垫和钢质垫板并使用压边圈3种不同的成形工艺进行数值模拟研究。模拟结果表明:采用前两种成形工艺得到的钛合金颅骨修复体表面出现压痕或起皱缺陷,采用在基本体和钛合金网板之间放置聚氨酯弹性垫和钢质垫板并使用压边圈这种成形工艺时,可以抑制压痕和起皱的产生,获得良好的成形效果。实验验证结果表明,应用多点成形技术,运用合理的成形工艺可以成形合格形状的钛合金颅骨修复体。