Variation in surface texture measurements

Surface texture influences cellular response to implants, implant wear, and fixation, yet measurement and reporting of surface texture can be confusing and ambiguous. Seven specimens of widely different surface textures were submitted to three internationally renowned laboratories for surface texture characterization. The specimens were from dental implants, orthopedic implants, and femoral heads. Areas to be measured were clearly marked; simplified instructions were supplied but specific measurement parameters were not requested. Techniques used included contact profilometry, two- and three-dimensional laser profilometry, and atomic force microscopy. Four to thirteen parameters were reported, 2D or 3D, including R(a) or S(a); only three were common to all centers. The results varied by as much as +/-300-1000%, depending on technique and surface type. Some surfaces were not measurable by some techniques. One dental implant surface was reported with R(a) of 0.17, 0.85, 1.9, and 4.4 microm. The CoCr femoral head ranged from an R(a) of 0.011 to 0.10 microm; the zirconia head from 0.006 to 0.05 microm. Similar variability was reported for the other parameters. Useful surface texture characterization requires reporting of all measurement parameters. Comparisons between studies may be compromised if differences in technique are not considered.     

上釉技术对氧化钇稳定四方相氧化锆多晶陶瓷粘接及力学性能的影响

文题释义：氧化钇稳定四方相氧化锆多晶陶瓷：是以氧化钇为稳定剂、四方相为主要物相的氧化锆陶瓷，其具有较高的抗弯强度(900-1 200 MPa)和断裂韧性(9-10 MPa·m^1/2)。由于这些优异的机械性能，氧化钇稳定四方相氧化锆多晶陶瓷成为口腔冠桥修复中应用最广泛的陶瓷之一。 相变增韧机制：为氧化锆增韧的一种方法。稳定剂使四方相氧化锆在室温下可以处于亚稳态，但是在应力作用下亚稳态的四方相氧化锆易转化为单斜相氧化锆，同时伴有3%-5%的体积膨胀，这个过程能弥合微裂纹且消耗断裂能，提高氧化锆陶瓷的韧性。 背景：任何表面处理都应在不损害原有氧化钇稳定四方相氧化锆多晶陶瓷强度的前提下提高其粘接强度。目前缺乏上釉技术对氧化钇稳定四方相氧化锆多晶陶瓷粘接强度影响的资料，并且其对氧化钇稳定四方相氧化锆多晶陶瓷力学性能的影响尚不明确。 目的：评估上釉技术对氧化钇稳定四方相氧化锆多晶陶瓷力学行为及其与树脂水门汀粘接强度的影响。 方法：制作氧化钇稳定四方相氧化锆多晶陶瓷试件并随机分为4组：A组，表面不做任何处理；B组，110 μm氧化铝颗粒喷砂；C组，上釉+氢氟酸酸蚀；D组，上釉+氢氟酸酸蚀+硅烷化。检测每组试件的表面显微形貌、粗糙度、晶相结构、元素组成、剪切粘接强度和弯曲强度，并观察剪切粘接强度测试后所有断面的断裂模式。 结果与结论：①经表面处理后的试件粗糙度明显增大，降序排列依次为C组(0.62±0.01) μm、D组(0.55±0.02) μm、B组(0.11±0.02) μm、A组(0.05±0.01) μm，5组间粗糙度比较差异有显著性意义(P < 0.05)；②B组试件表面含有2.2%单斜相氧化锆，而其他组含量均为零；③除锆和氧2种元素外，B组还含有铝元素6.49%，C和D组分别含有硅元素18.67%和25.78%；④A、B、C、D组的剪切粘接强度分别为(3.11±0.40)，(4.23±0.45)，(6.62±0.60)，(10.46±0.83) MPa，组间两两比较差异均有显著性意义(P < 0.05)；⑤A、B、C和D组的三点弯曲强度分别为(961.07±75.53)，(1 234.73±114.09)，(1 024.28±120.51)，(1 036.09±80.10) MPa，其中A、C和D组两两比较差异无显著性意义(P > 0.05)，B组与A、C、D组比较差异有显著性意义(P < 0.05)；⑥结果表明，上釉技术未明显提升氧化钇稳定四方相氧化锆多晶陶瓷的弯曲强度，但上釉后经氢氟酸蚀刻并硅烷化处理可显著增强氧化钇稳定四方相氧化锆多晶陶瓷与树脂水门汀之间的粘接强度。 ORCID: 0000-0002-8066-2498(徐小敏) 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     

Bone growth enhancement in vivo on press-fit titanium alloy implants with acid etched microtexture

Early bone ongrowth secures long-term fixation of primary implants inserted without cement. Implant surfaces roughened with a texture on the micrometer scale are known to be osseoconductive. The aim of this study was to evaluate the bone formation at the surface of acid etched implants modified on the micro-scale. We compared implants with a nonparticulate texture made by chemical milling (hydrofluoric acid, nitric acid) (control) with implants that had a dual acid etched (hydrofluoric acid, hydrochloric acid) microtexture surface superimposed on the primary chemically milled texture. We used an experimental joint replacement model with cylindrical titanium implants (Ti-6Al-4V) inserted paired and press-fit in cancellous tibia metaphyseal bone of eight canines for 4 weeks and evaluated by histomorphometric quantification. A significant twofold median increase was seen for bone ongrowth on the acid etched surface [median, 36.1% (interquartile range, 24.3-44.6%)] compared to the control [18.4% (15.6-20.4%)]. The percentage of fibrous tissue at the implant surface and adjacent bone was significantly less for dual acid textured implants compared with control implants. These results show that secondary roughening of titanium alloy implant surface by dual acid etching increases bone formation at the implant bone interface.     

Influence of a zirconia sandblasting treated surface on peri-implant bone healing: An experimental study in sheep

A sandblasting process with round zirconia (ZrO₂) particles might be an alternative surface treatment to enhance the osseointegration of titanium dental implants. Our previous study on sheep compared smooth surface titanium implants (control) with implant surfaces sandblasted with two different granulations of ZrO₂. As the sandblasted surfaces proved superior, the present study further compared the ZrO₂ surface implant with other surface treatments currently employed: machined titanium (control), titanium oxide plasma sprayed (TPS) and alumina sandblasted (Al-SL) at different times after insertion (2, 4 and 12 weeks). Twelve sheep were divided into three groups of four animals each and underwent implant insertion in tibia cortical bone under general anaesthesia. The implants with surrounding tissues were subjected to histology, histomorphometry, scanning electron microscopy and microhardness tests. The experimentation indicated that at 2 weeks Zr-SL implants had the highest significant bone ingrowth (p < 0.05) compared to the other implant surfaces, and a microhardness of newly formed bone inside the threads significantly higher than that of Ti. The present work shows that the ZrO₂ treatment produces better results in peri-implant newly formed bone than Ti and TPS processing, whereas its performance is similar to the Al-SL surface treatment.     

Stereo imaging and cytocompatibility of a model dental implant surface formed by direct laser fabrication

Direct laser fabrication (DLF) allows solids with complex geometry to be produced by sintering metal powder particles in a focused laser beam. In this study, 10 Ti6Al4V alloy model dental root implants were obtained by DLF, and surface characterization was carried out using stereo scanning electron microscopy to produce 3D reconstructions. The surfaces were extremely irregular, with approximately 100 microm deep, narrow intercommunicating crevices, shallow depressions and deep, rounded pits of widely variable shape and size, showing ample scope for interlocking with the host bone. Roughness parameters were as follows: R(t), 360.8 microm; R(z), 358.4 microm; R(a), 67.4 microm; and R(q), 78.0 microm. Disc specimens produced by DLF with an identically prepared surface were used for biocompatibility studies with rat calvarial osteoblasts: After 9 days, cells had attached and spread on the DLF surface, spanning across the crevices, and voids. Cell density was similar to that on a commercial rough microtextured surface but lower than on commercial smooth machined and smooth-textured grit-blasted, acid-etched surfaces. Human fibrin clot extension on the DLF surface was slightly improved by inorganic acid etching to increase the microroughness. With further refinements, DLF could be an economical means of manufacturing implants from titanium alloys.     

Three-dimensional printing and porous metallic surfaces: a new orthopedic application

As-cast, porous surfaced CoCr implants were tested for bone interfacial shear strength in a canine transcortical model. Three-dimensional printing (3DP) was used to create complex molds with a dimensional resolution of 175 microm. 3DP is a solid freeform fabrication technique that can generate ceramic pieces by printing binder onto a bed of ceramic powder. A printhead is rastered across the powder, building a monolithic mold, layer by layer. Using these 3DP molds, surfaces can be textured "as-cast," eliminating the need for additional processing as with commercially available sintered beads or wire mesh surfaces. Three experimental textures were fabricated, each consisting of a surface layer and deep layer with distinct individual porosities. The surface layer ranged from a porosity of 38% (Surface Y) to 67% (Surface Z), whereas the deep layer ranged from 39% (Surface Z) to 63% (Surface Y). An intermediate texture was fabricated that consisted of 43% porosity in both surface and deep layers (Surface X). Control surfaces were commercial sintered beaded coatings with a nominal porosity of 37%. A well-documented canine transcortical implant model was utilized to evaluate these experimental surfaces. In this model, five cylindrical implants were placed in transverse bicortical defects in each femur of purpose bred coonhounds. A Latin Square technique was used to randomize the experimental implants left to right and proximal to distal within a given animal and among animals. Each experimental site was paired with a porous coated control site located at the same level in the contralateral limb. Thus, for each of the three time periods (6, 12, and 26 weeks) five dogs were utilized, yielding a total of 24 experimental sites and 24 matched pair control sites. At each time period, mechanical push-out tests were used to evaluate interfacial shear strength. Other specimens were subjected to histomorphometric analysis. Macrotexture Z, with the highest surface porosity, failed at a significantly higher shear stress (p = 0.05) than the porous coated controls at 26 weeks. It is postulated that an increased volume of ingrown bone, resulting from a combination of high surface porosity and a high percentage of ingrowth, was responsible for the observed improvement in strength. Macrotextures X and Y also had significantly greater bone ingrowth than the controls (p = 0.05 at 26 weeks), and displayed, on average, greater interfacial shear strengths than controls, although they were not statistically significant.     

Surface topography of zirconia implants does not alter action potentials of isolated rat sciatic nerves

The purpose of this study was to explore the effects of airborne-particle abrasion and selective infiltration etching of a yttrium-partially stabilized tetragonal zirconia polycrystal (Y-TZP) implant surfaces on nerve conduction. Particle-abraded Y-TZP (P/Y-TZP), selective infiltration etched Y-TZP (SIE/Y-TZP), and commercially pure titanium (CP-Ti) were used in the study (n = 5).The compound action potentials of the right and left sciatic nerves of eight sacrificed rats were quantified at the in vitro level. The implants were brought into intimate contact with the nerves and the time required for initiation of compound action potentials (TcAP), depolarization (Dp), repolarization (Rp), and amplitude of evoked compound action potentials (cAPs) were recorded before and after contact with the implants. The difference in cAPs between the basal response and after contact with CP-Ti implant was significant (p < 0.05). Time-dependent changes in cAPs of P/Y-TZP and SIE/Y-TZP groups and their basal nerve responses were similar (p > 0.05). Within- and between-subject comparisons revealed that TcAP, Dp, and Rp values for all groups were similar (p > 0.05). Particle-abraded and selective infiltration-etched zirconia implant surfaces do not alter nerve conduction beyond physiologic limits.     

In vivo effects of RGD-coated titanium implants inserted in two bone-gap models

RGD (Arg-Gly-Asp) coating has been suggested to enhance implant fixation by facilitating the adhesion of osteogenic cells to implant surfaces. Orthopedic implants are unavoidably surrounded partly by gaps, and these regions represent a challenging environment for osseointegration. We examined the effects of cyclic RGD-coated implants on tissue integration and implant fixation in two cancellous bone-gap models. In canines, we inserted loaded RGD-coated implants with 0.75-mm gap (n = 8) and unloaded RGD-coated implants with 1.5-mm gap (n = 8) into the distal femur and proximal tibia, respectively. Control gap implants without RGD were inserted contralaterally. The titanium alloy (Ti-6Al-4V) implants were plasma sprayed and cylindrical. The observation period was 4 weeks and the fixation was evaluated by push-out test and histomorphometry. Mechanical implant fixation was improved for RGD-coated implants. Unloaded RGD-coated implants showed a significant increase in bone whereas both loaded and unloaded implants showed a significant reduction in fibrous tissue anchorage. The results are encouraging, because RGD had an overall positive effect on the fixation of titanium implants in regions where gaps exist with the surrounding bone. RGD peptide coatings can potentially be used to enhance tissue integration in these challenging environments.     

Effects of sevoflurane on NF-кB and TNF-α expression in renal ischemia–reperfusion diabetic rats

Background

Ischemia–reperfusion (I/R) injury is the main reason of acute renal failure. However, inflammatory response and cell apoptosis are important mechanisms implicated in I/R injury. Recent studies indicated that nuclear factor kappa B (NF-кB) and tumor necrosis factor α (TNF-α) are both involved in these mechanisms. Sevoflurane reduces NF-кB and TNF-α expression in rats’ heart and decreases their renal I/R injury. However, few studies are available regarding the effect of sevoflurane on kidney of diabetic rats. Therefore, the aim of this study was to evaluate sevoflurane effect on NF-кB and TNF-α expression in diabetic rats to decrease renal I/R injury.

Methods

Male Sprague–Dawley rats were divided into five groups: Group A, non-diabetic rats underwent sham operation; Group B, non-diabetic rats with renal I/R injury; Group C, diabetic rats underwent sham operation; Group D, diabetic rats with renal I/R injury; Group E, diabetic rats with renal I/R injury after sevoflurane pretreatment. Rats of Group E were exposed to 2.5% sevoflurane for 30 min. After 24 h, creatinine (Cr), blood urea nitrogen (BUN), renal cell apoptosis, and NF-кB and TNF-α expression in kidney were assessed.

Results

Renal cell apoptosis, NF-кB, and TNF-α expression were significantly higher in diabetic rats with renal I/R injury group compared to diabetic rats that underwent sham operation (P < 0.01). These changes were significantly reduced by sevoflurane (P < 0.01).

Conclusion

Sevoflurane exerted a protective effect against renal injury by lowering the expression of NF-кB and TNF-α in renal I/R diabetic rats.

Graphical abstract

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A study on the effect of dual blasting with TiO2 on titanium implant surfaces on functional attachment in bone

In the present study, the effect of a dual treatment of titanium implants and the subsequent bone response after implantation were investigated. Coin-shaped c.p. titanium implants were placed into the tibias of 12 rabbits. The implant, which was dually blasted with TiO2 particles of two different sizes, was compared with implants that were blasted with only one of these particle sizes. Implants in group 1 were grit blasted with small particles, 22-28 microm in size, and group 2 with coarser particles, 180-220 microm size. These two treatments gave different surface micro textures. To test the effect of a combination of two different treatments, group 3 implants were blasted first with the 180- to 220-microm and subsequently with the 22- to 28-microm particles. The surface topography of the implant specimens was examined by scanning electron microscopy and by a confocal laser scanner and a numeric evaluation of S(a), S(t), and S(dr) was recorded. Group 2 implants, which were blasted with only the coarse particles, showed a significantly better functional attachment (p < 0.001) than the other two groups. Group 1, which was blasted with only small particles, showed the lowest retention in bone. There was a positive correlation between the topographical and mechanical evaluation of the surfaces.     

Differential fine-tuning of cochlear implant material-cell interactions by femtosecond laser microstructuring

Cochlear implants (CIs) can restore hearing in deaf patients by electrical stimulation of the auditory nerve. To optimize the electrical stimulation, the number of independent channels must be increased by reduction of connective tissue growth on the electrode surface and selective neuronal cell contact. The femtosecond laser microstructuring of the electrode surfaces was performed to investigate the effect of fibroblast growth on the implant material. A cell culture model system was established to evaluate cell-material interactions on these microstructured CI-electrode materials. Fibroblasts were used as a cell culture model for connective tissue formation, and differentiating neuronal-like cells were employed to represent neuronal cells. For nondestructive microscopic examination of living cells on the structured surfaces, the cells were genetically modified to express green fluorescent protein. To investigate the special interaction between the electrode material and the tissue we used electrode material which is originally used for manufacturing CI for human applications, namely platinum (contact material) and silicone carrier material (LSR 30, HCRP 50). Microstructures of various dimensions (groove width 1-10 microm) were generated by using femtosecond laser ablation. The highest fibroblast growth rate was observed on platinum, but cell growth rates on the silicone carrier material were lower. Microstructuring reduced fibroblast cell growth on platinum significantly. On the microstructured silicone, a trend to lower cell growth rates was observed. In addition, microgrooves on platinum surfaces can direct neurite outgrowth parallel to the grooves. The implications of the results are discussed with respect to the design of a microstructured CI surface.     

长径比差异对牙种植体-颌骨界面的应力分布影响

目的探讨不同长径比下牙种植体-颌骨界面的应力分布差异,为新型牙种植体结构的设计提供依据。方法运用Geomagic studio、SolidWorks和ANSYS Workbench软件建立下颌骨三维有限元模型,并根据种植体颈部有、无螺纹分成A、B两组进行仿真实验,对下颌磨牙分别施加不同的斜向咬合力和垂直向咬合力,对比分析牙种植体和周围骨组织的应力分布情况。结果长径比相同的情况下,同一种植体模型在斜向载荷作用下的等效应力峰值明显高于垂直载荷;在斜向和垂直两种载荷作用下,A、B组种植体模型应力主要集中于种植体颈部。斜向载荷作用下,A、B组种植体应力变化范围分别为144.74～374.67、161.52～475.38 MPa;垂直载荷作用下,A、B组种植体应力变化范围分别为101.28～187.40、110.08～210.32 MPa,A组种植体模型最大应力显著小于B组。结论临床上医生可根据长径比2.67初步选择标准种植体,同时结合患者颌骨状况进行选择。     

Interfacial shear strength of titanium implants in bone is significantly improved by surface topographies with high pit density and microroughness

Surface structure of implants influences bone response and interfacial shear strength between implants and bone. The aim of this study was to find topographical parameters that correlate with the interfacial shear strength. Two groups of sand-blasted titanium screws were implanted in 17 sheep tibia, each for 2-52 weeks: (A) acid pickled with HF/HNO(3); (B) acid etched with HCl/H(2)SO(4). Screw removal torque was measured and surface topography of both implant groups was studied by scanning electron microscopy, optical profilometry, and scanning probe microscopy. The roughness as well as the surface area of type A surface was higher in the scan region of 100 microm, but the microroughness and surface area of type B surface was higher in the scan region of 10 microm. A significantly higher removal torque (interfacial shear strength) of the surface treatment type B (412 +/- 60 Ncm) compared to surface treatment type A (157 +/- 33 Ncm) was found after 52 weeks of implantation in sheep due to differences in microroughness of both types of screws. It was also shown that the specification of the parameters Delta(a), R(a) and R(q) was not sufficient to characterize the properties of the implant surfaces. The analysis of R(q) parameter over wavelengths was required to characterize the size, shape and distribution of the implant surface structures.     

Bone response to endosseous titanium implants surface-modified by blasting and chemical treatment: a histomorphometric study in the rabbit femur

This study evaluated the effects of the addition of oxide structure with submicron-scale porous morphology on the periimplant bone response around titanium (Ti) implants with microroughened surfaces. Hydroxyapatite-blasted Ti implants with (experimental) and without (control) a porous oxide structure produced by chemical treatment were investigated in a rabbit femur model. Surface characterizations and in vivo bone response at 4 and 8 weeks after implantation were compared. The experimental implants had submicron-scale porous surface structure consisted of anatase and rutile phase, and the original R(a) values produced by blasting were preserved. The histomorphometric evaluation demonstrated statistically significantly increased bone-to-implant contact (BIC) for experimental implants, both in the three best consecutive threads (p < 0.01) and all threads (p < 0.05) at 4 weeks. There was no remarkable difference in the BIC% or bone area percentage between the two groups at 8 weeks. The porous Ti oxide surface enhanced periimplant bone formation around the Ti implants with microroughened surfaces at the early healing stage. Based on the results of this study, the addition of crystalline Ti oxide surface with submicron-sized porous morphology produced by chemical treatment may be an effective approach for enhancing the osseointegration of Ti implants with microroughened surfaces by increasing early bone-implant contact.     

Biomechanical and histomorphometric investigations on two morphologically differing titanium surfaces with and without fluorohydroxyapatite coating: an experimental study in sheep tibiae

The influence of fluorohydroxyapatite (FHA) coating and surface roughness of Ti6Al4V implants on bone response was investigated. Uncoated and FHA-coated screws with lower (LR and LR+FHA; Ra: 5.7+/-0.2 microm) and higher (HR and HR+FHA; Ra: 21.8+/-0.9 microm) surface roughness, were inserted into the diaphyses of 8 sheep tibiae. Twelve weeks after implantation, extraction torque and bone-to-implant contact were evaluated. The smoothest surfaces showed an improved extraction torque and significant differences were observed between LR and HR (-24.6%, p<0.0005), LR and HR+FHA (-30.7%, p<0.0005), LR+FHA and HR (-17.4%, p<0.005), and LR+FHA and HR+FHA (-24.0%, p<0.005). The bone-to-implant contact data paralleled the biomechanical data: the smoother the surface, the greater the bone-to-implant contact. Significant (p<0.0005) decreases in bone-to-implant contact were observed between LR+FHA and HR (-24.2%), and between LR+FHA and HR+FHA (-29.2%). The current findings suggest that LR surfaces significantly improve the osteointegration rate of implanted cortical screws independently of the FHA coating.     

Long Term Outcomes of Pediatric Liver Transplantation According to Age

Liver transplantation (LT) has been the key therapy for end stage liver diseases. However, LT in infancy is still understudied. From 1992 to 2010, 152 children had undergone LT in Seoul National University Hospital. Operations were performed on 43 patients aged less than 12 months (Group A) and 109 patients aged over 12 months (Group B). The mean age of the recipients was 7 months in Group A and 74 months in Group B. The patients'' survival rates and post-LT complications were analyzed. The mean Pediatric End-stage Liver Disease score was higher in Group A (21.8) than in Group B (13.4) (P = 0.049). Fulminant hepatitis was less common in Group A (4.8%) than in Group B (13.8%) (P = 0.021). The post-transplant lymphoproliferative disorder and portal vein complication were more common in Group A (14.0%, 18.6%) than in Group B (1.8%, 3.7%) (P = 0.005). However, the 1, 5, and 10 yr patient survival rates were 93%, 93%, and 93%, in Group A and 92%, 90%, and 88% in Group B (P = 0.212). The survival outcome of pediatric LT is excellent and similar regardless of age. LTs in infancy are not riskier than those of children.

Graphical Abstract

相似文献   

依赖天冬氨酸特异性半胱氨酸蛋白酶-3的肝细胞凋亡在肝硬化大鼠肝缺血再灌注损伤中的作用

目的:探讨肝硬化大鼠肝缺血/再灌注(I/R)损伤是否与肝细胞凋亡相关及天冬氨酸特异性半胱氨酸蛋白酶-3(caspase-3)活性变化与肝细胞凋亡的关系。方法:Pringle法复制肝I/R模型,将肝硬化大鼠随机分为2组:A组:单纯肝门阻断;B组:血流阻断+抑制剂:N-苯甲基氧化碳酰-缬氨酸-丙氨酸-天冬氨酸-氟化丙酮(ZVAD-fmk)15mg/kg;取无肝硬化大鼠,作单纯肝门阻断为C组。各组肝门阻断时间均为30min,再灌注72h。比较3组的血清天冬氨酸转氨酶(AST)、肝组织的caspase-3活性和肝细胞凋亡数。结果:A组大鼠肝组织caspase-3活性、肝细胞凋亡数在再灌注后6h达高峰,分别为(18.1±1.8)μmolAMC·h^-1·g^-1(tissue)和20.9%±4.9%,与I/R前的(6.6±2.0)μmolAMC·h^-1·g^-1(tissue)和0.5%±0.3%相比,P＜0.01。肝细胞凋亡数、caspase-3的活性随灌注时间的延长而减低,两者随时间的变化一致。3组中A组肝损伤最严重,表现为再灌注后6h血清AST最高,与B、C组比较有显著差异,大鼠7d生存率只为62.5%。进一步研究表明,再灌注后6h,A组的肝组织caspase-3活性、肝细胞凋亡数亦明显比B、C组高。结论:肝细胞凋亡是肝硬化大鼠肝I/R损伤的主要病理改变。肝细胞凋亡的发生可能主要依赖于肝组织caspase-3活性的改变,抑制caspase-3能明显减轻肝I/R损伤。肝硬化肝脏比无硬化肝脏对缺血损伤敏感性高的病理机制与依赖caspase-3的肝细胞凋亡密切相关。     

慢性乙型肝炎患者ALT水平与HBV特异性CTL、非特异性CTL计数的关系

目的 探讨慢性乙型肝炎(CHB)患者丙氨酸转氦酶(ALT)水平与乙型肝炎病毒(HBV)特异性细胞毒性T淋巴细胞(CTL)、非特异性CTL的关系.方法 148例CHB患者根据ALT水平分为3组:甲组35例,ALT≥2×正常值上限(ULN)-5×ULN(100～250 IU/L);乙组53例,ALT＞5×ULN～≤10×ULN(251～500 IU/L);丙组60例,ALT＞10×ULN(＞500 IU/L),用流式细胞仪检测非特异性CTL,对其中74例(甲组17例,乙组27例,丙组30例)人白细胞抗原(HLA)-A2阳性CHB患者检测HBV特异性CTL.比较三组的HBV特异性CTL、非特异性CTL、HBV DNA水平和HBeAg阳性率.结果 HBV特异性CTL:甲组[(0.42±0.10)%]高于乙组[(0.25±0.08)%],t=6.37,P＜0.01,乙组高于丙组[(0.17±0.004)%]t=5.14,P＜0.01.非特异性CTL:甲组[(15.01±3.01)%]低于乙组[(18.1±5.02)%],t=2.81,P＜0.01,乙组低于丙组[(21.5±6.11)%]t=3.07,P＜0.01.HBV DNA水平:甲组[(4.97±0.86)log10拷贝/m1]低于乙组[(5.92±0.92)log10拷贝/ml],t=4.87,P＜0.01,乙组低于丙组[(6.37±0.71)log10拷贝/ml]t=2.92,P＜0.01.HBeAg阳性:甲组15例(42.86%),低于乙组(32例,占60.38%),x2=2.59,P＞0.05,乙组低于丙组(41例,占68.33%),x2=0.788,P＞0.05,甲组低于丙组x2=5.929,P＜0.05.结论 CHB患者非特异性CTL越高,ALT水平越高[1],而HBV特异性CTL越低,HBV复制越强.     

Influence of surface characteristics on bone integration of titanium implants. A histomorphometric study in miniature pigs

The purpose of the present study was to evaluate the influence of different surface characteristics on bone integration of titanium implants. Hollow-cylinder implants with six different surfaces were placed in the metaphyses of the tibia and femur in six miniature pigs. After 3 and 6 weeks, the implants with surrounding bone were removed and analyzed in undecalcified transverse sections. The histologic examination revealed direct bone-implant contact for all implants. However, the morphometric analyses demonstrated significant differences in the percentage of bone-implant contact, when measured in cancellous bone. Electropolished as well as the sandblasted and acid pickled (medium grit; HF/HNO3) implant surfaces had the lowest percentage of bone contact with mean values ranging between 20 and 25%. Sandblasted implants with a large grit and titanium plasma-sprayed implants demonstrated 30-40% mean bone contact. The highest extent of bone-implant interface was observed in sandblasted and acid attacked surfaces (large grit; HCl/H2SO4) with mean values of 50-60%, and hydroxylapatite (HA)-coated implants with 60-70%. However, the HA coating consistently revealed signs of resorption. It can be concluded that the extent of bone-implant interface is positively correlated with an increasing roughness of the implant surface.