血人参总黄酮纯化工艺的优化及其对酪氨酸酶的抑制作用研究＊

目的 优化大孔吸附树脂分离纯化血人参总黄酮的工艺条件，研究血人参总黄酮对酪氨酸酶的抑制作用。方法 以吸附率、解吸率等为考察指标，采用静态吸附-解吸试验对6种不同型号的大孔吸附树脂进行筛选，优选最佳的树脂型号。采用单因素试验考察上样液pH、上样液浓度、上样体积、上样体积流量、洗脱溶剂、洗脱液体积流量、洗脱剂体积对血人参总黄酮纯化的影响，确定最佳纯化工艺；以L-酪氨酸、L-多巴为底物，测定血人参总黄酮对酪氨酸单酚酶和二酚酶的抑制作用，并对其抑制机理和抑制类型进行分析。结果 AB-8型大孔吸附树脂对血人参总黄酮的分离纯化效果最好。最佳纯化工艺参数为：上样液pH为4、上样体积为70 mL（4.7 BV）、上样体积流量为1 mL·min^-1、上样液浓度为5.38 mg·mL^-1、洗脱溶剂为70%乙醇、洗脱剂体积流量为3 mL·min^-1、洗脱剂体积为120 mL（8 BV），血人参总黄酮对酪氨酸单酚酶和二酚酶均有抑制作用，其最大半数抑制浓度分别为88.78 mg·L^-1和36.46 mg·L^-1，对二酚酶的抑制类型为可逆非竞争性抑制。结论 AB-8型大孔吸附树脂可用于纯化血人参总黄酮，纯化后血人参总黄酮的纯度为46.01%，建立的工艺条件稳定可靠。纯化后的血人参总黄酮对酪氨酸酶有抑制作用，抑制类型为可逆非竞争性抑制。     

High‐Performance Polybenzoxazine Derived from Polyfunctional Benzoxazine Composed of an Oligonuclear Phenolic Compound Having a 4,4′‐Dimethylenebiphenyl Linker

A novel polyfunctional benzoxazine monomer, OP‐a , is synthesized from aniline, formaldehyde, and an oligonuclear phenolic compound (OP) with a 4,4′‐dimethylenebiphenyl group as the phenol linker. After thermal curing of OP‐a up to 240 °C, a brown‐colored, transparent polybenzoxazine ( POP‐a ) film is obtained. The mechanical and thermal properties of the POP‐a film are investigated by tensile test, dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). The POP‐a film is extremely tough compared with a typical polybenzoxazine ( PB‐a ) film. The elongation at break of the POP‐a film is 7.6%, which is surprisingly large for the highly cross‐linked thermoset. The high cross‐link density is suggested from the very high storage modulus (over 1 GPa) above the glass transition temperature (T _g) observed by DMA. The T _g of POP‐a is also improved significantly to T _g = 223 °C, which is approximately 50 °C higher than that of PB‐a . Moreover, TGA reveals that the thermal stability of POP‐a is also enhanced.     

基于NIRS技术和PCA-SVM算法6种树脂及其他类中药的快速鉴别

目的:利用近红外漫反射光谱(NIRS)法,结合主成分分析(PCA)和支持向量机(SVM)联用算法,建立6种树脂及其他类中药安息香(Benzoinum),琥珀(Succinum),没药(Myrrha),乳香(Olibanum),松香(Colophonium),天竺黄(Bambusaen Concretio Silicea)的NIR模式识别模型,用于该6味中药的快速鉴别。方法:收集上述6种中药样品,经性状鉴别和理化分析确定正品药材55批,粉碎成均匀粉末,在4 000~12 000 cm~(-1)光谱区,采集各样品粉末的NIR光谱,选取特征谱段9 000~5 400,5 000~4 000 cm~(-1)为建模谱段,分别采用矢量归一化法(vector normalization,VN),一阶导数法(first derivative,FD),二阶导数法(second derivative,SD)3种不同光谱预处理方法进行预处理并分别进行PCA降维。根据主成分空间散点图,优选最佳预处理方法。利用最佳预处理方法处理后光谱的PCA降维数据,建立SVM模式识别模型,SVM模型参数c和g采用网格搜索法结合五折交叉验证进行寻优。对比不同主成分数所建PCA-SVM模型的预测准确率,确定最佳的主成分数,最终建立6种中药NIR快速鉴别模型。结果:在9 000~5 400,5 000~4 000 cm~(-1)建模谱段,确定最佳光谱预处理方法为SD,SD预处理光谱PCA降维后,确定最佳主成分数为3个,累计贡献率达93.57%。经网格搜索法确定最佳SVM建模参数组为c=65 536,g=512。所建PCA-SVM模型对训练集和验证集样品预测正确率均达100%,模型五折交叉验证准确率亦达100%。结论:所建的6种中药NIR光谱PCA-SVM鉴别模型,预测准确率高,模型预测能力强,结合NIRS技术无损、快速的优点,该模型可用于上述6种中药的无损、快速鉴别。     

A mathematical model for post-irradiation hardening of photoactivated composite resins

A generalized mathematical model for the post-irradiation hardness of photoactivated resins is presented. This model describes a ratio of hardness values as a function of time after irradiation. The low error and generalized character of the model indicate similarities in the post-irradiation hardening of adequately irradiated resins. Using a ratio of hardness at the bottom surface to the final hardness of the top surface, an inadequately irradiated resin can be identified by deviation from the generalized model. Such deviations are noted throughout the hardening process and are recommended as a means of readily identifying deficient photoactivation.     

丙酮及甲基丙烯酸甲酯表面处理对基托树脂与软衬材料粘接效果的影响

目的 研究丙酮及甲基丙烯酸甲酯表面处理对基托树脂与软衬材料间微渗漏、粘接强度及基托树脂抗弯强度的影响.方法 制备30 mm×30 mm×2 mm树脂块36块,根据随机数字表随机均分为3组,每组12块,丙酮组:树脂块粘接面浸泡于丙酮溶液中30 s;甲基丙烯酸甲酯组:树脂块粘接面浸泡于甲基丙烯酸甲酯溶液中180 s;对照组:不进行表面处理.两树脂块间衬以2 mm软衬材料后粘接,冷热循环5000次,浸泡于131Ⅰ溶液中24h后计数γ射线,即微渗漏数.制备36块30 mm×10 mm ×7.5 mm树脂块,分组及表面处理同上.两树脂块间衬以3 mm软衬材料后粘接,冷热循环5000次后,测试拉伸强度,即粘接强度.制备18块65 mm× 10 mm×3.3 mm树脂块,分组及表面处理同上,涂布软衬材料粘接剂后测试抗弯强度.结果 丙酮组和甲基丙烯酸甲酯组的微渗漏数(520.0±562.2和493.5±447.9)均小于对照组(1369.5±590.2,P＜0.05);丙酮组和甲基丙烯酸甲酯组粘接强度[(1.5±0.4)和(1.4±0.5) MPa]均大于对照组[(0.9±0.2) MPa,P＜0.05];两实验组间微渗漏数和粘接强度差异均无统计学意义(P＞0.05);3组抗弯强度差异均无统计学意义(P＞0.05).结论 丙酮及甲基丙烯酸甲酯表面处理可减少软衬材料与基托树脂间微渗漏,增加两者间粘接强度,未导致基托树脂抗弯强度下降.     

Patterns of cell death and cell cycle profiles of cultured WEHI 13 var fibroblasts exposed to eluates of composite resins used for direct and indirect restorations

Previous studies have shown that in vitro exposure to single compounds released from composite resins may induce cell death. In the present study the effects of eluates from commercially available composite resins used for direct or indirect restorations were evaluated on the cell cycle progression and type of cell death of cultured WEHI 13 var fibroblasts. Cells exposed to eluates of the materials were assessed for cytotoxicity by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay for cell death, for cell cycle profiles by flow cytometry, for caspase-3 biochemically and by immunocytochemistry, and for morphological changes by fluorescence microscopy with acridine orange. The direct composite resin eluates induced extensive apoptosis, followed by secondary necrosis. This was accompanied by cell enlargement, micromultinucleation, chromatin disintegration, cell cycle arrest at different phases, and caspase-3 activation. The composites for indirect restorations were much less cytotoxic at all biological end-points investigated. The findings suggest that composite resins used for direct and indirect dental restorations differ in their cytotoxic potential and their ability to affect basic cellular functions. This underlines the impact of improved polymerization with respect to their biologic behavior.     

MWCNTs／PMMA复合材料制备及力学性能研究

目的：制备多壁纳米碳管（MWCNTs），并将其用于聚甲基丙烯酸甲酯（PMMA）增强，研究其力学性能变化。方法：用化学气相沉积（ChemicalVaporDeposition，CVD）法制备MWCNTs，将1mgMWCNTs均匀分散于15mL牙托水中，制备MwCNTs／PMMA复合材料，测试复合材料的力学性能，观察断面形貌。结果：制备出MWCNTs均匀分散的MwCNTs／PMMA复合材料，复合材料的拉伸强度、延伸率较对照组有显著提高（P〈0．05），弯曲强度与对照组相比无明显差异（P〉0．05）。复合材料断面可见碳管与树脂之间结合良好，MWCNTs均匀弥散分布在树脂基体中。结论：应用CVD法制备MWCNTs用于增强基托树脂，可有效改善其力学性能。     

Changes in pituitary and prolactin cells of Wistar rats after two dental fillings with bisphenolic resins

Bisphenol-A (BPA) is used to manufacture dental materials such as sealants, fillings and cements. There is evidence of its estrogenic effects on recipients after the placement of dental sealants. Pituitary and especially prolactin (PRL) cells are targets for estrogens.

Objectives

The aim of this research was to determine if BPA eluted from dental resins can alter the proliferation of pituitary cells and PRL cells in the short, medium and long term in a case-control assay.

Methods

Two dental fillings were inserted in the lower incisors of Wistar rats divided into groups sacrificed after one, three, five and seven months. Immunocytochemical treatment was carried out in order to determine proliferating cell nuclear antigen (PCNA) positive cells, PRL-positive cells, PRL- and PCNA-positive cells.

Results

A significant increase of PCNA-positive cells after one (p < 0.05), three (p < 0.01) and five months (p < 0.01) was recorded. PRL-positive cells showed no statistically significant difference between intervened animals and controls. PRL- and PCNA-positive cells manifested a significant increase after five months (p < 0.05). A significant decrease in proliferating cells was observed after seven months (p < 0.05) for PCNA-positive cells and (p < 0.01) for PRL- and PCNA-positive cells.

Conclusion

Low quantities of BPA eluted during mastication can affect immunocytochemical patterns of pituitary cells, increasing cellular proliferation in the short, medium and long term although PRL cell population remained unaffected after dental fillings.     

INFLUENCE OF POST-CURE TREATMENTS ON HARDNESS AND MARGINAL ADAPTATION OF COMPOSITE RESIN INLAY RESTORATIONS: AN IN VITRO STUDY

Objectives:

The purpose of this study was to evaluate the Vickers hardness number (VHN) and the in vitro marginal adaptation of inlay restorations of three hybrid composite resins (Filtek Z250, Opallis and Esthet-X) subjected to two post-cure treatments.

Material and Methods:

For the microhardness test, three different groups were prepared in accordance with the post-cure treatments: control group (only light cure for 40 s), autoclave group (light cure for 40 s + autoclave for 15 min at 130°C); and microwave group (light cure for 40 s + microwave for 3 min at 450 W). To assess the marginal adaptation, the composite resin was inserted incrementally into a mesial-occlusal-distal cavity brass mold and each increment light-cured for 40 s. A previous reading in micrometers was taken at the cervical wall, using a stereomicroscope magnifying glass equipped with a digital video camera and image-analysis software. Subsequently, the specimens were subjected to the post-cure treatments (autoclave and microwave) and a reading was taken again at the cervical wall. Data were compared using ANOVA for the hardness test, split-plot ANOVA for the adaptation assessment and Tukey''s test for multiple comparisons. A significance level of 5% was adopted for all analyses.

Results:

The post-cure treatments increased the hardness of conventional composites (p<0.001) and the gap values of inlay restorations (p<0.01). Filtek Z250 showed higher hardness (p<0.001) and lower gap values than Opallis and Esthet-X (p<0.05). Gap values did not exceed 90 μm for any of the experimental conditions.

Conclusion:

The post-cure treatments increased the VHN and the gap values on the cervical floor of composite resin inlays. Moreover, Filtek Z250 showed the best results, with higher hardness and lower gap values.