四种陶瓷材料与牙釉质磨耗性能的研究

【目的】研究临床常用的四种陶瓷材料（松风陶瓷、义获嘉陶瓷、低温水热陶瓷、纳米陶瓷）与天然牙釉质的磨耗性能,比较不同修复材料对天然牙釉质的磨耗,探讨其磨耗机制。【方法】采用针一盘式二体磨耗机,以滑石瓷为对磨物,计算天然牙釉质、陶瓷试件及其对磨滑石瓷的体积损失并电镜观察修复材料磨耗面的微观结构。【结果】被测试件磨耗后体积损失量均小于天然牙（P〈0．01）,天然牙体积损失量与其对磨滑石瓷体积损失量无显著性差异（P〉0．05）,松风陶瓷的滑石瓷损失量大于其它各组陶瓷（P〈O．01）,义获嘉陶瓷的滑石瓷损失量大于纳米陶瓷及低温水热陶瓷（P〈0．01）,纳米陶瓷与低温水热陶瓷的滑石瓷损失量无显著性差异（P〉0．05）。电镜观察不同修复材料磨耗后其磨痕及微观结构明显不同。【结论】修复材料的微观结构是影响其磨耗性能的重要因素,改善材料的微观结构可减少对天然牙的过度磨耗,保护牙齿硬组织。     

Narratives of children with high-functioning autism spectrum disorder: A meta-analysis

BackgroundThe aim of this meta-analysis was to analyze the narrative performance of children and adolescents with high-functioning Autism Spectrum Disorders (ASD) in terms of microstructure, macrostructure and internal state language.MethodA systematic literature search yielded 24 studies that met the predetermined inclusion criteria. Effect sizes for each study were calculated for eight variables and analyzed using a random effects model. Intellectual ability, age and type of narrative were considered as potential moderators.ResultsResults revealed that the children with ASD performed significantly worse than their peers on all the variables considered.ConclusionsFindings are discussed taking into account the main explanatory psychological autism theories. Implications for intervention and orientations for future research are suggested.     

Microstructure of the feather in Japanese Jungle Crows (<Emphasis Type="Italic">Corvus macrorhynchos</Emphasis>) with distinguishing gender differences

Assessing gender difference in Japanese Jungle Crows (Corvus macrorhynchos) is difficult by gross observation because both sexes have black plumage colors. Careful observation of the plumage, however, reveals that it is actually iridescent glossy purple and dark-green in color, and that these colors are more marked in adult males than in females. In birds, such iridescent structural colors are generally produced in the feather barbules, where light is scattered constructively by laminar arrays consisting of alternating layers of materials with different refractive indices, namely keratin, melanin and air. We have investigated differences in the microstructure of the feathers of male and female Jungle Crows by means of scanning and transmission electron microscopy. Male birds had more barbs than females, and the length of the prongs was shorter in males than in females. The density of the melanin granules in the cross-section of barbules was higher in males than in females. Moreover, only in males did the melanin granules show an ordered arrangement beneath a keratin cortex layer at the edges of barbules. These results demonstrate that there are microstructural differences in the feathers of male and female Jungle Crows and suggest that the Jungle Crows’ feathers may have iridescent coloring that differs according to gender.     

Changes in the microstructure of the rat alveolar bone induced by unilateral molar extraction and estrogen deficiency

The present study was designed to assess compensatory changes in the microstructure of alveolar bone induced by occlusal force and estrogen deficiency using micro-computed tomography, which enables us to analyse bone mass and architecture in detail, in combination with a histomorphometric analysis.Fifteen 10-week-old female Wistar rats were used. We created hypofunctional teeth in the right molar region of the mandible after abolishing occlusal force by extracting the right maxillary molars and bilateral ovariectomy was undergone. Analyses of the microstructure and bone resorption of the alveolar bone were carried out by the micro-computed tomography (micro-CT) and histomorphometric analyses.The results of micro-CT and histomorphometric analyses showed that a decrease in occlusal force stimulated bone resorption and accelerated the fragility of the bone structure in the alveolar bone around the teeth, and also shortened the mean intercept length of the trabecular bone in the direction of the tooth axis. However, estrogen deficiency appeared to have few effects, based on the results of micro-CT and histological morphometric analyses.These results suggest that occlusal force is essential for female rats with sexual maturation during short time period to maintain the structure and regulation of alveolar bone in rats.     

建立猪胰腺高强度聚焦超声通道的探讨

目的探索高强度聚焦超声（HIFU）辐照正常猪胰腺超声通道的建立方法，提高HIFU辐照胰腺的有效性和安全性。 方法以猪胰体部为HIFU靶目标进行辐照，实验组在猪胃内放置水囊并注入800～1200ml脱气水，对照组未放置水囊，通过病理和电镜检查比较两组之间胰腺损伤程度，并观察并发症发生情况。 结果实验组胰腺的HIFU超声通道明显改善，HIFU对胰腺组织的损伤程度较对照组重，同时HIFU对超声通道的损伤较对照组轻。 结论胃内放置水囊并注入脱气水是建立猪胰腺HIFU超声通道的可行方法。     

Zoledronate reverses mandibular bone loss in osteoprotegerin-deficient mice

Summary  To characterize the changes in osteoprotegerin-deficient (OPG−/−) mice mandibles and the possible mandibular bone loss prevention by zoledronate. This preventive effect in the mandible differed from that in the proximal tibia and was independent of the OPG pathway. Introduction  The study aimed to characterize both the changes in the mandible in osteoprotegerin-deficient (OPG^−/−) mice and possible mandibular bone loss prevention by zoledronate. Methods  Twenty-eight 6-week-old female mice (C57BL/6J), including OPG^−/− (n = 21) and wild-type (WT) (n = 7) mice, were assigned to four groups after 2 weeks of acclimatization to local vivarium conditions: wild mice with vehicle (WT group); OPG^−/− mice with vehicle (OPG^−/− group); and OPG^−/− mice that were subcutaneously injected with either 50 or 150 μg/kg zoledronate (Zol-50 and Zol-150 groups, respectively). Mice were sacrificed at 4 weeks after these treatments and after fasting for 12 h. Sera were harvested for biochemical analyses. The right mandible and tibia of each mouse were selected for microCT analysis. Student’s t-test was performed for comparisons of bone parameters at different sites in the WT group. Analysis of variance (ANOVA) was used to compare the biomarkers and bone parameters in the different treatment groups. Results  Serum bone-specific alkaline phosphatase (B-ALP) and tartrate-resistant acid phosphatase 5b (TRACP-5b) were significantly decreased in WT mice as compared to the levels in the OPG^−/− mice (P < 0.05). Zoledronate treatment decreased the high serum B-ALP activity observed in OPG^−/− mice to the levels seen in WT mice, while serum TRACP-5b concentrations were decreased to levels even lower than those in WT mice. There were substantial variations in BMD and microstructure of the mandibular and proximal tibial trabeculae. Mandibular bone loss was less affected by OPG gene deprivation than the proximal tibia was. Both zoledronate groups showed greater BMD, trabecular BV/TV, Tb.Th, Tb.N, and Conn.D and a significant decrease in Tb.Sp and SMI as compared to the findings in OPG^−/− mice (P < 0.05). However, higher apparent BMD and more compact plate-like trabeculae were observed in the mandible after treatment with zoledronate as compared to the findings in the proximal tibia. No significant differences were found in any parameter in both zoledronate groups. Conclusions  The present study showed that zoledronate could reverse the significant bone loss in mice mandibles that was induced by OPG gene deficiency. This preventive effect, which was accompanied with considerable inhibition of bone turnover, differed in the mandible and in the proximal tibia and was independent of the OPG pathway. Drs. Sheng and Xu contributed equally to this work.     

Focal segmental glomerulosclerosis with intramembranous vesicle-like microstructures and podocytic infolding lesion

A 42-year-old woman was admitted to Kyushu University hospital because of 6 months' history of bilateral leg edema. Upon admission, ascites and pleural effusion as well as systemic edema were noted. Laboratory tests revealed hypoalbuminemia of 1.5 g/dl and massive proteinuria of 10 g/day. She was diagnosed with nephrotic syndrome. Renal biopsy revealed diffuse thickening of the glomerular basement membrane (GBM) and a crescent-like extracapillary lesion with segmental sclerosis in four of 11 glomeruli. Immunoglobulins and complements were negative by immunofluorescence examination. Therefore, we diagnosed this as focal segmental glomerulosclerosis (FSGS) rather than membranous nephropathy. Using an electron microscope, we observed a thickening of the GBM with numerous intramembranous vesicle-like microstructures and an infolding of the podocyte into the GBM. Since the microstructures were partly demarcated by a unit membrane and some of them were located very closely to the infolded podocyte, we speculated that the microstructures were derived from the podocyte. The unique electron microscopic finding of our case is a disease entity rather than a reactive phenomenon.     

Variations of microstructure, mineral density and tissue elasticity in B6/C3H mice

200-MHz scanning acoustic microscopy (SAM) and synchrotron radiation μCT (SR-μCT) were used to assess microstructural parameters, acoustic impedance Z and tissue degree of mineralization of bone (DMB) in site-matched regions of interest in femoral bone of two inbred strains. Transverse femoral sections taken from 5 C57BL/6J@Ico (B6) and 5 C3H/HeJ@Ico (C3H) mice (5.5 months old) were explored. Mass density ρ, elastic coefficient c₁₁ and Young's modulus E₁ were locally derived in the distal epiphysis, distal metaphysis for trabecular bone and mid-diaphysis for cortical bone using a rule-of-mixture model. Structural parameter estimations obtained from X-ray tomographic and acoustic images were almost identical. Both strains had the same bone diameter, but the C3H mice had greater cortical thickness and smaller cancellous diameter than did B6 mice. The average DMB and impedance values were in the range between 1.13 and 1.33 g cm^− 3 and 5.8 and 7.8 Mrayl, respectively. All tissue parameters were lower in B6 mice than in C3H mice. However, interstrain differences of DMB were much less (up to 3.8%) than differences of Z (up to 13.2%). SAM and SR-μCT fulfill the requirement for a simultaneous evaluation of cortical bone microstructure and material properties at the tissue level. However, SAM provides a quantitative estimate of elastic properties at the tissue level that cannot be captured by SR-μCT. The strong differences in the measured acoustic impedances among the two inbred strains indicate that the impedance is a good parameter to detect genetic variations of the skeletal phenotype in small animal models.     

小径微孔聚氨酯人工血管的制备条件对微观结构与性能的影响

目的　研究小径微孔聚氨酯 (polyurethane,PU)人工血管的制备条件对微观结构和力学性能的影响。　方法　采用浸渍 -沥滤法制备 PU小径微孔人工血管 ,通过改变模径、PU材料、盐粒大小、盐胶比和浸渍次数等制备条件 ,控制人工血管的尺寸参数和微观结构 ,测定 PU血管的力学性能 ,观察血管尺寸参数和微观结构对其性能的影响。　结果　 PU小径血管内径 2～ 4 mm,壁厚 0 .6～ 1.2 mm,密度 0 .2 3～ 0 .4 9g/ cm3,孔径 4 2～ 95μm,孔隙率5 6 %～ 80 %。血管的径向顺应性 1.2 %～ 7.4 %· 13.3k Pa- 1 ,水渗透性 0 .2 9～ 12 .4 4 g/ (cm2 · min) ,轴向抗张强度1.5 5～ 4 .36 MPa,爆破强度 6 0～ 30 0 k Pa,缝线撕裂强度 19.5～ 96 .2 N/ cm2 。相同尺寸时 ,Chro- noflex制备的小径血管的顺应性和水渗透性优于 PCU- 15 0 0制备的小径血管 ,而 PCU- 15 0 0小径血管的轴向抗张强度、爆破强度和缝线撕裂强度优于 Chro- noflex小径血管。　结论　通过选择材料和优化制备条件 ,可制得具有合适孔径和孔隙率 ,顺应性和其它性能与天然血管匹配的 PU小径血管。     

Diffuse-interface theory for structure formation and release behavior in controlled drug release systems

A common method of controlling drug release has been to incorporate the drug into a polymer matrix, thereby creating a diffusion barrier that slows the rate of drug release. It has been demonstrated that the internal microstructure of these drug–polymer composites can significantly impact the drug release rate. However, the effect of processing conditions during manufacture on the composite structure and the subsequent effects on release behavior are not well understood. We have developed a diffuse-interface theory for microstructure evolution that is based on interactions between drug, polymer and solvent species, all of which may be present in either crystalline or amorphous states. Because the theory can be applied to almost any specific combination of material species and over a wide range of environmental conditions, it can be used to elucidate and quantify the relationships between processing, microstructure and release response in controlled drug release systems. Calculations based on the theory have now demonstrated that, for a characteristic delivery system, variations in microstructure arising due to changes in either drug loading or processing time, i.e. evaporation rate, could have a significant impact on both the bulk release kinetics and the uniformity of release across the system. In fact, we observed that changes in process time alone can induce differences in bulk release of almost a factor of two and typical non-uniformities of ±30% during the initial periods of release. Because these substantial variations may have deleterious clinical ramifications, it is critical that both the system microstructure and the control of that microstructure are considered to ensure the device will be both safe and effective in clinical use.