制备PDLLA组织工程支架的致孔剂研究

为了制备孔隙呈球形、孔隙间相互连通的高孔隙率三维细胞支架,研究了一种新型水溶性球形致孔剂及性质。探讨了间歇离心湿度粘技术与水溶性球形致孔剂相结合,制备聚乳酸(PDLLA)三维多孔细胞支架,获得了高度为5·0mm±0·5mm,直径为8·3±0·4mm的三维多孔支架。实验结果表明,致孔剂颗粒呈球形、水溶性良好,在三维支架中无残留;并且支架的孔隙结构均匀、孔隙率高(94·68%±0·52%)、孔隙呈球形、孔隙间相互完全连通,孔隙的大小可以人为控制。由此表明,在组织工程细胞支架制备中,这类水溶性球形致孔剂具有广泛的潜在应用价值。     

A synthetic bone implant macroscopically identical to cancellous bone

Macroporous hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) are widely used as synthetic bone replacement materials due to their high biocompatibility and osteoconductive properties. The level of porosity, pore size distribution, pore morphology, and the degree of pore interconnectivity in such grafts significantly influences the extent of bone ingrowth. It has been hypothesised that an ideal implant macrostructure may be similar in morphological characteristics to the inorganic matrix of the bone it is replacing. However, to date, clinically available synthetic materials differ structurally from cancellous bone.

A method is described for the macrostructural replication of cancellous bone. Reproduction involves a multistage process requiring the manipulation of positive and negative forms of the inorganic matrix. By infiltration of a wax negative mould of cancellous bone with a ceramic slip, followed by removal of the wax, and firing, it is possible to produce a positive replica of the original cancellous macrostructure.

Optimisation of slip preparation conditions (pH and percentage deflocculant addition) and sintering conditions have allowed successful replication of cancellous bone using several bioceramic compositions including HA, β-TCP, and HA/β-TCP.     

Microvasculature of the rabbit urinary bladder

Background: The urinary bladder requires a rich blood supply to maintain its functions, the storage and release of urine. Specialized properties of the bladder vasculature might be anticipated to ensure the integrity of this blood supply, because it is known that blood flow is reduced by distension during bladder filling. However, the bladder vasculature has been described in detail only at the gross level. A comprehensive, threedimensional view of the blood supply to the bladder wall is presented here. Methods: The microvasculature of the bladder of male New Zealand white rabbits was described using the combination of vascular corrosion casting, alkali digestion, light microscopy, and scanning and transmission electron microscopy. Following administration of an anticoagulant and an overdose of anesthetic, the abdominal aorta was cannulated just above the inferior mesenteric artery to permit flushing of the distal vasculature. The bladder vasculature was cleared of blood with buffered saline and then either perfuse-fixed with buffered 2% glutaraldehyde and sectioned, or filled with “Mercox” resin to prepare vascular corrosion casts. Casts were cleaned with NaOH, formic acid, and water. In some cases fixed bladders were partially digested with NaOH to expose the mucosal capillary plexus. Results: The bladder is supplied with blood by single, left and right vesicular branches of the internal or external iliac arteries. The serpentine vesicular arteries extend along the lateral borders of the bladder from base to apex just deep to the serosal surface and send dorsal and ventral branches to supply the dorsal and ventral bladder walls. Veins accompany the arteries and exhibit numerous valves. A very dense complex of vessels at the apex of the bladder apparently serves to accommodate bladder distension. The muscularis and submucosa contains few vessels, but the mucosa is well vascularized. An especially dense capillary plexus is present in the lamina propria at its junction with the transitional epithelium. In the relaxed bladder these capillaries lie in grooves formed by the basal layers of the epithelium. The endothelial cells of these capillaries display few cytoplasmic vesicles and are continuous or fenestrated. These capillaries are often invested with pericytes. The mucosal capillary plexus may be associated with an epithelial transport function or may be necessary for urothelial metabolism or maintenance of the barrier function of the urothelium. Unusual capillary tufts, possibly associated with vascular lymphatic tissue, are found associated with the main vessels on the lateral walls in the basal half of the bladder. Conclusions: These methods present a clear, comprehensive, three-dimensional view of the microvasculature of the bladder wall. They also identify several unique features of this vasculature and provide a basis for studies of the response of this vasculature to pathologic states and experimental manipulation. © 1995 Wiley-Liss, Inc.     

后牙分体插入式铸造桩核冠修复的临床研究

目的：探讨后牙残根残冠的分体插入式铸造桩核冠修复的方法及临床意义。方法：对68颗后牙残根残冠应用分体插入式铸造桩核修复，观察患自我感觉、临床使用效果等。结果：68颗后牙修复后随访2年半至3年，所有患均使用良好。其中2颗根管预备中发生意外侧穿，早期有轻度胀痛：2颗根管超填，偶有不适感。结论：后牙残根残冠插入式铸造桩核冠修复，既方便、简洁，又解决了共同就位道的问题。     

两种口腔镍铬合金离子析出的体外实验研究

目的 研究Heraenium S与TILITE P两种口腔镍铬合金在唾液pH值和成分变化时离子析出行为。方法 将两种合金试件在pH6墙正常唾液环境中浸泡一周，再用pH4的酸性及酸性加0．1％F^-的人工唾液处理两小时，之后回到正常唾液环境中浸泡一周，观察其在处理前、后镍离子的析出和表面理化状态的改变。结果 ①在正常唾液环境中HeraeniumS合金镍离子的析出量大于TILITEP合金；②pH降低和氟化物的加入增大了两种合金镍离子的析出量，其中TILITEP合金大于HeraeniumS合金；③在短暂的pH降低和加入氟化物后再回到正常唾液环境中，TILITEP合金的镍离子析出量大于HeraeniumS合金；并且在合金表面可以观察到形态学上的腐蚀破坏。结论 口腔镍铬合金的镍离子析出受到口腔环境动态变化的影响，TILITEP合金对环境改变的敏感性曼大。     

自制透明工作通道辅助神经内镜手术治疗脑室铸型血肿

目的 探讨自制透明工作通道辅助神经内镜手术治疗脑室铸型血肿的疗效。方法 回顾性分析百色市人民医院2017年9月～2019年12月收治的脑室铸型血肿患者的临床资料,根据其手术方式分为观察组和对照组。结果 两组患者的性别、平均年龄、入院时GCS评分、术前血肿量比较,差异无统计学意义(P>0.05),观察组手术时间、术中出血量、引流管留置时间、术后24 h内血肿清除率、术后并发颅内感染、需分流型脑积水、30天内的死亡率、术后第1 d、14 d、28 d、6 M的GCS评分及术后6 M的NIHSS评分等观察指标比较,差异有统计学意义(P<0.05)。结论 相较于侧脑室穿刺外引流术而言,虽然自制透明工作通道辅助神经内镜手术治疗脑室铸型血肿时术中出血量较多,手术时间较长,但该手术方式可有效缩短引流管留置时间、减少术后并发症、降低患者致死率及致残率,提高患者术后生存质量。     

Anelastic Behaviour of Commercial Die-Cast Magnesium Alloys: Effect of Temperature and Alloy Composition

The anelastic deformation, resulting from partial reversal of {101¯2} twinning, is studied at room temperature to 150 °C on several commercial die-cast magnesium alloys for the first time. The magnitude of anelastic strain decreases with increasing temperature. For inter-alloy comparison, AZ91 shows the largest maximum anelastic strain, while AM40 and AM60 show similar maximum anelastic strain. The phenomenon is discussed in terms of solid solution softening and hardening of slip planes and how they influence twinning. T5-aged AE44 consistently shows smaller magnitude of anelasticity compared to as-cast AE44, suggesting that the precipitates formed during ageing may decrease the twin-boundary mobility and further suppress untwinning. Presence of anelasticity poses a challenge to yield strength measurement using the conventional 0.2% offset method, and a more accurate and consistent method of using a higher offset strain or a lower modulus is proposed in this study.     

ZTA Pipes with a Gradient Structure-Effect of the Rheological the Behavior of Ceramic Suspensions on the Gradient Structure and Characterized of the Obtained Products

This paper focuses on the verifying the possibility of producing Al₂O₃-ZrO₂ composite pipes with a gradient structure using centrifugal slip casting method. The aim of the research is to define the correlation between the rheological properties of aqueous suspensions of ceramic powders with different solid loading and obtaining the ZrO₂ phase gradient in the Al₂O₃ matrix. Such products, due to their unique properties, can be utilized in the transport of aggressive substances, even in extreme temperature or corrosive conditions. The suspensions and the sintered samples were characterized by: broad rheological analysis, scanning electron microscopy, X-ray diffraction, stereological analysis and Vickers hardness tests. The study reports on a series of samples produced of ceramic suspensions (70 vol.% Al₂O₃–30 vol.% ZrO₂) differing in the total solid loading in the range of 30–55 vol.%. The results clearly indicate that obtaining the gradient structure of ceramic-ceramic composite pipes is closely related to the rheological properties of the suspensions from which the samples are cast. The phase gradient is obtainable from suspensions 30–40 vol.%, in which the possibility of moving ZrO₂ particles relative to the Al₂O₃ is quite high—these suspensions are characterized by low viscosity and the dominance of viscous over elastic properties (G′ > G″).     

牙科铸造合金诱发慢性毒副作用细胞机制的研究进展

牙科铸造合金在口腔临床中被广泛应用,而合金修复后在长期使用过程中,由于口腔内复杂微环境的影响,合金在口腔中的腐蚀会引起金属离子析出。大量的研究发现：这些析出的金属离子会对邻近的组织和细胞带来不同程度的慢性毒副作用,主要包括局部不良反应和全身不良反应。由于全身不良反应的发生率较低,相关的数据报道也比较有限,所以对合金中析出的金属离子引起的口腔局部不良反应成为国内外学者研究的热点。本文就铸造合金析出的金属离子对组织和细胞的毒副作用的研究现状及相应的细胞调控机制作一综述。