颈部推拿对兔颈动脉粥样硬化重度狭窄病变的#br# 血管拉伸力学特性的影响 颈部推拿对兔颈动脉粥样硬化重度狭窄病变的血管拉伸力学特性的影响

目的　探讨颈部推拿手法对兔颈动脉粥样硬化（CAS）重度狭窄的血管拉伸力学特性的影响。 方法　45只新西兰兔随机分为颈椎旋转组（n=12）、推桥弓组（n=12）、模型对照组（n=12）和空白对照组（n=9），在颈椎旋转组、推桥弓组和模型对照组建立左侧CAS模型，并分别接受颈椎旋转手法、推桥弓手法干预3周，模型对照组和空白对照组不作手法干预。取左侧颈动脉进行单轴拉伸试验和病理观察，比较四组兔颈动脉的拉伸力学特性。 结果　（1）26只兔造模成功，其中颈椎旋转组、推桥弓组、模型对照组兔颈动脉的最大载荷显著高于空白对照组，同时最大应变显著低于空白对照组(P<0.05)；（2）颈椎旋转组兔颈动脉的弹性模量显著高于模型对照组、推桥弓组和空白对照组（P<0.05），而推桥弓组兔颈动脉的弹性模量与模型对照组相比差异无统计学意义(P>0.05)。 结论　动脉粥样硬化病变可致兔颈动脉血管拉伸力学特性下降，而颈部旋转推拿治疗可导致严重粥样硬化病变并重度狭窄的兔颈动脉弹性下降，为临床安全应用颈部推拿手法提供了参考。     

Osteogenetic changes in elongated styloid processes of Eagle syndrome patients

Abnormal elongation of the styloid process, or Eagle syndrome, can be painful, and is associated with differential diagnoses including cranio-facial malformations and vasculo-neurological disturbances. The precise molecular mechanism leading to styloid process elongation is unknown. In this study, elongated styloid processes with periosteal fibrous ligament tissue were obtained from three patients with Eagle syndrome and examined by immunohistochemical methods using different antisera. In all cases, marked bony deposition was found at the apex of the styloid process. The osteogenetic proteins, such as osteonectin, osteocalcin, BMP-2, BMP-4, and RANKL were strongly positive by immunohistochemistry in both the ligament fibers and the periosteal membrane attached to the styloid process apex. Staining for protective proteins, HO-1, HSP-70, and HSP-90 was also positive. These results suggest that styloid process elongation is related to increased expression of osteogenetic and protective proteins. Therefore, we propose that Eagle syndrome results from a protective response to increased tensile stress in the ligament attached to the styloid process, which could also signal osteogenetic protein expression in the periosteal fibrous tissue.     

常规消毒对ProTaper镍钛根管锉抗拉强度的影响

目的 探讨超声清洗时间和消毒灭菌频率对镍钛根管锉的抗拉性能的影响,以了解超声清洗和高温高压消毒灭菌法在镍钛根管锉灭菌中应用的安全性和可行性.方法 采用全新的ProTaper S2锉和F2锉各25支,分为5组:标准组(未处理)、对照组(未超声-高压灭菌)、A组(超声震荡50 min+高压灭菌5次)、B组(超声震荡100 min+高压灭菌10次)、C组(超声震荡150 min+高压灭菌15次),分别用万能测试仪对其进行抗拉伸强度的性能试验.结果 S2及F2的标准组之间的抗拉伸强度差异无统计学意义(P>0.05),提示样本间不存在差异性;经不同时间超声清洗及不同次数高温高压处理的S2镍钛锉抗拉伸强度测试结果显示:对照组、A组、B组、C组分别为(76.58±4.87)MPa、(71.00±5.39)MPa、(72.33±3.43)MPa、(66.81±4.08)MPa;F2镍钛锉抗拉伸强度结果分别为:(111.75±6.83)MPa、(110.46±3.88)MPa、(107.29±3.89)MPa、(94.53±6.61)MPa;A、B组与对照组的ProTaper S2锉和F2锉的抗拉强度差异均无统计学意义(P>0.05),即镍钛锉经超声震荡50 min+高压灭菌5次及超声震荡100 min+高压灭菌10次消毒后,其抗拉伸强度无明显影响;C组与对照组间差异存在统计学意义(P<0.05),即镍钛锉经超声震荡150 min+高压灭菌15次消毒后,对其抗拉伸强度有影响.结论 常规超声-高压灭菌消毒超过一定频率可能增加ProTaper系统镍钛根管锉折断可能性.     

In vitro characterisation of arterial stiffening: From the macro- to the nano-scale

Accurate measurement of the material properties of arterial tissue is important for better characterisation of diseases and the development of reliable computational models. There are a number of in vitro techniques that are applied to study the biomechanical properties of arterial tissue. This review article presents data obtained using tensile testing, nanoindentation, scanning acoustic microscopy (SAM) and atomic force microscopy (AFM). Each of these techniques provides material property information at a different spatial resolution and in many ways are complementary techniques. The lack of consensus in the literature with regard to the appropriate stress and strain definitions that should be used when reporting tensile testing data is also highlighted. The potential of higher spatial resolution techniques, which provide data at micro-scale (nanoindentation and SAM) and nano-scale (AFM) for application to the characterisation of human aortic tissue are discussed. Finally, studies, which have examined age-related changed in the aorta at these different length scales, are highlighted.     

Comparative Evaluation of Bond Strengths of Different Core Materials with Various Luting Agents Used for Cast Crown Restorations

The coronal cast restoration continues to be used commonly to restore mutilated, endodontically treated teeth. The tensile bond strength of luting cements is of critical importance as many of failures are at the core and the crown interface. An invitro study with aim to evaluate and compare bond strengths of luting cements between different core materials and cast crowns. A total of 45 extracted identical mandibular second premolars were endodontically treated and divided into 3 groups of 15 each. Specimens in first group were restored with cast post and core (Group C), and specimens in second group were restored with stainless steel parapost and composite core material (Group B) and specimens in third group were restored with stainless steel parapost and glass ionomer core build (Group G). Standardized crown preparation was done for all the specimens to receive cast crowns. Each group was further divided into 3 subgroups and were cemented using 3 different luting cements namely, resin cement, polycarboxylate cement, glass ionomer cement (Type I). The samples of each subgroup (n = 5) were subjected to tensile testing using Universal Testing Machine at a crosshead speed of 2 mm/min till the dislodgement of crown from the core surface was observed. The bond strengths were significantly different according one way ANOVA (F-150.76 and p < 0.0000). The results of the study showed that the specimens cemented with resin cement in cast core, composite core and glass ionomer core exhibited significantly higher bond strengths as compared to specimens cemented with glass ionomer and polycarboxylate cement. Composite resin core and resin cement combinations were superior to all other cement and core combinations tested.     

不同振动频率对3种粘接剂粘固种植体基桩时拉伸强度的影响

目的:比较不同振动频率对3种粘结剂粘结种植体基桩与钴铬烤瓷合金基底冠之间拉伸强度的影响。方法:制备90个纯钛种植体基桩及与基桩相匹配的钴铬合金基底冠。按不同的振动频率分为5组,0点组、7点组、8点组、9点组和10点组,分别用氧化锌丁香油水门汀(zinc oxide-eugenol,ZOE)、玻璃离子水门汀(glass ionomercement,GIC)和种植粘结剂(premier implant cement,PIC)粘结金属基底冠和基桩。以握笔式将洁牙机工作头的前端部分与基桩长轴垂直接触颈缘,螺旋振动15min,测试拉伸强度。结果:同一种粘结剂的粘结作用下,随着洁牙机振动频率的增加,种植体的基桩与基底冠产生的脱位力之间存在显著性差异(P<0.05);在同一振动频率作用下,不同粘结剂对种植体基桩与基底冠产生的脱位力存在显著性差异(P<0.05);洁牙机的振动频率与脱位力之间呈负相关关系(P<0.05)。结论:不同振动频率对金属冠与基桩之间拉伸强度有显著性影响。     

Peel bond strength of resilient liner modified by the addition of antimicrobial agents to denture base acrylic resin

In order to prolong the clinical longevity of resilient denture relining materials and reduce plaque accumulation, incorporation of antimicrobial agents into these materials has been proposed. However, this addition may affect their properties.

Objective

This study evaluated the effect of the addition of antimicrobial agents into one soft liner (Soft Confort, Dencril) on its peel bond strength to one denture base (QC 20, Dentsply).

Material and Methods

Acrylic specimens (n=9) were made (75x10x3 mm) and stored in distilled water at 37ºC for 48 h. The drug powder concentrations (nystatin 500,000U - G2; nystatin 1,000,000U - G3; miconazole 125 mg - G4; miconazole 250 mg - G5; ketoconazole 100 mg - G6; ketoconazole 200 mg - G7; chlorhexidine diacetate 5% - G8; and 10% chlorhexidine diacetate - G9) were blended with the soft liner powder before the addition of the soft liner liquid. A group (G1) without any drug incorporation was used as control. Specimens (n=9) (75x10x6 mm) were plasticized according to the manufacturers'' instructions and stored in distilled water at 37ºC for 24 h. Relined specimens were then submitted to a 180-degree peel test at a crosshead speed of 10 mm/min. Data (MPa) were analyzed by analysis of variance (α=0.05) and the failure modes were visually classified.

Results

No significant difference was found among experimental groups (p=0.148). Cohesive failure located within the resilient material was predominantly observed in all tested groups.

Conclusions

Peel bond strength between the denture base and the modified soft liner was not affected by the addition of antimicrobial agents.     

Comparative Evaluation of Tensile Bond Strength between Silicon Soft Liners and Processed Denture Base Resin Conditioned by Three Modes of Surface Treatment: An Invitro Study

Soft denture liners act as a cushion for the denture bearing mucosa through even distribution of functional load, avoiding local stress concentrations and improving retention of dentures there by providing comfort to the patient. The objective of the present study was to compare and evaluate the tensile bond strengths of silicone-based soft lining materials (Ufi Gel P and GC Reline soft) with different surface pre treatments of heat cure PMMA denture base acrylic resin. Stainless steel dies measuring 40 mm in length; 10 mm in width and 10 mm in height (40 × 10 × 10) were machined to prepare standardized for the polymethyl methacrylate resin blocks. Stainless steel dies (spacer for resilient liner) measuring 3 mm thick; 10 mm long and 10 mm wide were prepared as spacers to ensure uniformity of the soft liner being tested. Two types of Addition silicone-based soft lining materials (room temperature polymerised soft lining materials (RTPSLM): Ufi Gel P and GC Reline soft) were selected. Ufi Gel P (VOCO, Germany), GC Reline soft (GC America) are resilient, chairside vinyl polysiloxane denture reliners of two different manufacturers. A total of 80 test samples were prepared of which 40 specimens were prepared for Group A (Ufi Gel P) and 40 specimens for Group B (GC Reline soft). In these groups, based on Pre-treatment of acrylic resin specimens each group was subdivided into four sub groups of 10 samples each. Sub-group I—without any surface treatment. Sub-group II—sand blasted Sub-group III—treated with Methyl Methacrylate monomer Sub-group IV-treated with chemical etchant Acetone. The results were statistically analysed by Kruscal Wallis test, Mann–Whitney U test, and Independent t test. The specimens treated with MMA monomer wetting showed superior and significant bond strength than those obtained by other surface treatments. The samples belonging to subgroups of GC Reline soft exhibit superior tensile bond strength than subgroups of Ufi Gel P. The modes of failure of all specimens were mostly adhesive in nature. Surface pre treatments by chemical means improved the bond strength between the silicone liners and denture base.     

Ventralight ST and SorbaFix Versus Physiomesh and Securestrap in a Porcine Model

Background and Objectives:

The objective of this study was to compare mesh contracture, adhesion characteristics, tissue ingrowth, and histologic response of Ventralight ST/SorbaFix (C.R. Bard/Davol, Warwick, RI, USA) with Physiomesh/Securestrap (Ethicon, Somerville, NJ, USA) in a porcine model of laparoscopic ventral hernia repair.

Methods:

Standard laparoscopic technique was used to bilaterally implant meshes in 10 female Yorkshire swine. Each animal received either two Ventralight ST meshes (oval shaped, 10.2 × 15.2 cm) or two Physiomesh meshes (oval shaped 10 × 15 cm), one on either side of the midline. The meshes were fixated to the intact peritoneum with either SorbaFix (for animals receiving Ventralight ST) or Securestrap (for animals receiving Physiomesh). There were 5 animals in each group, yielding 10 of each mesh-fixation combination. Mesh contracture, adhesion characteristics, tissue ingrowth, and histologic response were evaluated after 14 days by image analysis, mechanical testing, and histologic staining (hematoxylin-eosin, Masson trichrome, picrosirius red, and von Willebrand factor).

Results:

Ventralight ST/SorbaFix and Physiomesh/Securestrap exhibited a similar percentage of mesh contracture, percentage of adhesion coverage, adhesion tenacity, collagen deposition, and levels of necrosis (P > .05 in all cases). However, Ventralight ST/SorbaFix exhibited significantly less inflammation (P = .0001), fibrosis (P = .0017), hemorrhage (P = .0001), and angiogenesis (P = .0032) and significantly greater strength of tissue ingrowth (P = .0003) than Physiomesh/Securestrap after the 14-day implantation period.

Conclusions:

Ventralight ST/SorbaFix exhibited more favorable strength of tissue ingrowth and histologic response and similar mesh contracture and adhesion characteristics compared with Physiomesh/Securestrap over a short-term 14-day implantation period in a preclinical porcine model.     

拉应力对体外培养人足跟皮肤成纤维细胞增殖影响的实验研究

目的：观察拉应力对人足跟外倒皮肤成纤维细胞增殖的影响,为预防跟骨骨折术后切口边缘皮肤坏死、切口不愈合提供一定的理论依据.方法：取40岁男性足跟外侧皮肤成纤维细胞培养及传代后,分Oh组、6h组、24 h组进行拉应力加载试验,检测培养液中TGF-β1、IL-6含量,使用透射电镜、光镜观察线粒体、细胞核的变化.结果：在10％的拉应力下,成纤维细胞随着承受应力的时间增加,线粒体逐渐减少,TGF-β1和IL-6的分泌受到抑制,细胞增殖逐渐受到抑制.结论：人足跟外侧皮肤长时间处于拉应力状态是跟骨骨折手术后切口边缘皮肤坏死、切口不愈合的重要原因.