基于响应面法优选美洲大蠊口腔原位温敏凝胶的制备研究

目的制备美洲大蠊Periplaneta americana口腔原位温敏凝胶。方法采用自由基聚合法首次以N-异丙基丙烯酰胺(NNIPAM)和甲基丙烯酸羟丙酯(HPMA)合成聚(N-异丙基丙烯酰胺-甲基丙烯酸羟丙酯)[P(NNIPAM-HPMA)]作为温敏材料;通过冷溶法制备美洲大蠊口腔原位温敏凝胶,采用Box-Behnken设计响应面法,以溶蚀时间、胶凝时间为评价指标,在固定美洲大蠊提取物用量基础上,对羟丙基甲基纤维素(HPMC)、聚乙烯吡咯烷酮(PVP K30)、P(NNIPAM-HPMA)的用量进行优选。结果通过原位聚合法合成了P(NNIPAM-HPMA)温敏材料;并用响应面法优选了可用于口腔的美洲大蠊原位温敏凝胶的处方,优选的处方为美洲大蠊提取物10%、HPMC 3.0%、PVP K30 9.5%、P(NNIPAM-HPMA) 10.0%,其溶蚀时间为2 h,胶凝时间8～9 s。结论优选得到美洲大蠊口腔原位温敏凝胶,为美洲大蠊提取物的口腔原位局部的临床应用奠定了科学依据。     

Time-varying characteristics of the induced membrane and its effects on bone defect repair

PurposeThis study intended to determine the properties of induced membranes after various periods of polymethyl methacrylate (PMMA) retention and the effect of different retention intervals on subsequent defect repair.MethodsModel of a critical bone defect in rabbits was prepared to obtain the induced membrane. For varying intervals of spacer insertion (2, 4, 6, 8, 12, 16, and 20 weeks postoperatively), angiogenesis, osteogenesis, and MSC-related properties were analyzed by immunohistochemistry and western-blot. Furthermore, 2, 4, 6, and 8 weeks after PMMA insertion, bone grafting was performed. Characteristics of defect repair were analyzed by X-ray and micro-CT analysis.ResultsThe induced membrane displayed angiogenesis, osteogenesis, and MSC-related properties from the 2- to 20-week intervals. Quantitation of protein expression (RUNX2, ALP, VEGF, TGF-beta, OCT4, and STRO1) revealed that selected proteins gradually rose to a high level at 4–8 weeks postoperatively and then decreased to a low level over a long time period. Following bone grafting, the most new bone formation was in the group when grafting was performed at 4 weeks, followed by the groups at 2 and 6 weeks, with the least in the group at 8 weeks.ConclusionThe induced membrane displays angiogenesis, osteogenesis, and MSC-related properties from the 2- to 20-week intervals. These were increased to a peak level at 4–8 weeks postoperatively and then gradually decreased. The optimal timing for bone grafting at the second stage in the presented model was 4 weeks after PMMA insertion.     

Occupational contact dermatitis in a manicurist

We report a case of a manicurist who developed an allergic skin reaction to acrylates, manifested by itchy erythema, papules, vesicles and fissures on her hands, fingertips, forearm and eyelids. Patch tests showed positive reactions to three nail products used: ethylene glycol dimethacrylate, 2‐hydroxyethyl methacrylate, ethyl acrylate and 2‐hydroxyethyl acrylate in (meth)acrylate series. By using gel nail products, our patient became sensitized to 2‐hydroxyethyl methacrylate. We assume that this had been the trigger, leading to the occurrence of cross‐reactions between numerous acrylates including ethylene glycol dimethacrylate, ethyl acrylate and 2‐hydroxyethyl acrylate. When handling nail products, it is necessary to prevent airway sensitization, contact sensitization and cross‐reaction between various acrylates.     

Microspheres of essential oil in polylactic acid and poly(methyl methacrylate) matrices and their blends

This study is focussed on micro-encapsulation of essential oils in polylactic acid (PLA) and a poly(methyl methacrylate) (PMMA) matrix as well as blends of the same. Microspheres were prepared by the solvent evaporation technique and characterised by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infra-red spectroscopy (FTIR). The encapsulation efficiencies and release profiles of the essential oils were studied by gas chromatography mass spectrometry (GC-MS) and head-space solid-phase microextraction GC-MS, respectively. Furthermore, the microspheres were tested for antibacterial activity against both Gram-negative and Gram-positive bacterial strains.

The results showed that the microspheres compositions (PLA/PMMA ratio) have significant effect on their characteristics. The process adopted for preparing the microspheres promoted formation of spherical particles at the sizes of 1.5–9.5?µm. The highest encapsulation efficiency of the prepared microspheres was observed in systems consisting of linalool (81.10?±?10.0?wt. % for PLA system and 76.0?±?3.3?wt. % for PMMA system). Confirmation was also made that the release rate of the microspheres was affected by the size of the same.     

Polymer hydration and stiffness at biointerfaces and related cellular processes

The direct and indirect (by changing mechanical properties) effects of hydration at interfaces on cellular processes and tissue diseases are reviewed. The essential effect of substrate stiffness on cellular processes was demonstrated in the last decade. The combined effect of surface stiffness and hydration at interfaces has garnered much less attention, though hydration and dehydration play important roles in biological processes. This review focuses on the studies that demonstrate how hydration affects biological processes at interfaces. Elevated sodium and dehydration stimulate inflammatory signaling in endothelial cells and promote atherosclerosis. Various types of implant and blood contacting device coatings with varied surface stiffness and hydration have been reported. Effect of hydration on polymer modulus of elasticity and viscoelasticity was discussed taking into account cells adhesion, migration, proliferation, differentiation on surfaces with various degree of hydration. Future directions of research were considered, including the use of nanotechnology to regulate the hydration degree.     

Particulate poly(methyl methacrylate) could stimulate proinflammatory CD4 T cell responses in a monocyte-dependent manner,and directly mediate cell death

Poly(methyl methacrylate) (PMMA) is a synthetic polymer that has been widely used in various medical implants. Traditionally considered a biologically inert material, it is now understood that PMMA may have proinflammatory properties. Here, we present a proof-of-concept study of the effect of PMMA on CD4 T cells. Using particulate PMMA, a material that resembled wear debris in orthopedic implants, to stimulate whole peripheral blood mononuclear cells, we found that the expression of IFNgamma, IL-4, IL-17, and TGFbeta could all be upregulated in CD4 T cells in a manner that was dependent on the dose of particulate PMMA. Furthermore, compared to direct anti-CD3/CD28 stimulation, PMMA preferentially stimulated the expression of IFNgamma and IL-17 but not the expression of IL-4 or TGFbeta. Interestingly, the presence of autologous monocytes was required, since PMMA had no stimulatory effect on isolated CD4 T cells. We further demonstrated that direct monocyte-CD4 T cell contact was required, and the costimulatory molecules CD80 and CD86 were involved for the optimal stimulation of CD4 T cells. PMMA also directly mediated the death of CD4 T cells in a manner that was dependent on dose but independent of the presence of monocytes. Overall, our study revealed that PMMA could induce CD4 T cell death, and also could result in CD4 T cell activation with a preference toward proinflammatory responses in a monocyte-dependent manner.     

Influence of polymerization conditions on monomer elution and microhardness of autopolymerized polymethyl methacrylate resin

Residual monomer contents and surface hardness are important factors in determining the serviceability of provisional restorations. The intent of this study was to systemically evaluate the effects of curing conditions on provisional polymethyl methacrylate (PMMA) resins which utilize a free-radical polymerization reaction. Combinations of the three curing factors of temperature, pressure, curing environment (water/air) were adjusted during the fabrication of autopolymerized specimen disks. The initial hardness of tested materials was measured with a microhardness tester 1 h after disc fabrication, and the amounts of residual methyl methacrylate (MMA) released into water were analyzed by reverse-phase HPLC after 7 d of water immersion. Results from multiple regressions showed that curing temperature was the dominant factor in improving resin surface hardness, whereas curing in water was the key factor for reducing the quantity of residual monomer. The pressure factor, which was thought to be critical for managing autopolymerized resins, showed no significant influences on the properties tested. ANOVA results showed that provisional PMMA resins cured in hot water, with or without pressure, significantly reduced the amount of residual MMA elution (up to 80%) and increased the microhardness values (up to 50%).     

三种甲基丙烯酸酯类脱敏剂的疗效比较

目的 :比较 3种甲基丙烯酸酯类脱敏剂的疗效。方法 :将 14 0例 2 5 7个患牙随机分为 4组 ,3个实验组分别用GLUMA、Seal&Protect和SingleBond进行脱敏治疗 ,对照组用 75 0g/L氟化钠甘油脱敏 ,比较各组的即刻疗效和 3个月后疗效。结果 :3个实验组的疗效均显著高于对照组 (P <0 .0 1) ,而 3组之间无显著差异(P >0 .0 5 ) ,3个月后亦然。结论 :GLUMA、Seal&Protect和SingleBond都是较为理想的脱敏剂。     

暂时冠桥修复材料聚合过程中髓腔内温度变化的体外研究

目的:体外测量6种暂时冠桥修复材料直接法制作暂时修复体时牙髓腔内温度的变化。方法:选取1个健康的人离体下颌第三磨牙,标准全冠预备后,将一热电偶置入髓腔,另一端与一电子温度计相连,将4种Bis-acryl复合树脂(Protemp3Garant、Luxatemp、ProtempⅡ和Fast-Temp)和2种聚甲基丙烯酸甲酯树脂(Quick Resin和Curefast)分别按照使用说明混合后,填入预先准备的硅橡胶印模中,在基牙上复位,记录实验材料聚合过程中髓腔内的温度变化。结果:ProtempⅡ组髓腔最大升温值(3.8℃)低于Protemp3Garant组(4.6℃)、Luxatemp组(4.8℃)和Fast-Temp组(4.8℃),有显著性差异(P<0.05),后三组之间无显著性差异(P>0.05)。4种Bis-acryl复合树脂最大升温值又显著低于QuickResin组(9.1℃)和Curefast组(8.7℃)(P<0.05),QuickResin和Curefast之间无显著性差异(P>0.05)。结论:4种Bis-acryl复合树脂聚合过程中髓腔升温低于两种聚甲基丙烯酸甲酯树脂,适合直接法制作暂时修复体。     

快速液压热聚合义齿基托材料的实验研究

目的 了解快速液压热聚合义齿基托材料的力学性能。方法 采用自行研制的新型液压自控牙用树脂聚合器和常规水浴两种方法加热固化义齿基托材料，进行挠度、抗弯曲强度、弹性模量、抗冲击强度及硬度的对比分折。结果 快速液压热聚合义齿基托材料的力学性能与水浴法相比无显著性差异，但可以明显缩短热处理时间且全过程自动完成。结论 快速新型液压自控牙用树脂聚合器简化了义齿制作的操作过程，明显缩短了热处理时间，可以准确快速制作出理想的义齿。