Bond durability when applying phosphate ester monomer–containing primers vs. self-adhesive resin cements to zirconia: Evaluation after different aging conditions

PurposeThis study aimed to evaluate bond durability when applying 2 phosphate ester monomer-containing self-adhesive resin cements alone, versus a combination of phosphate ester monomer-containing primer conditioning plus 2 conventional resin cements requiring primers, to zirconia after different artificial aging methods.MethodsWe cemented air-abraded zirconia plates to composite resin cylinders with self-adhesive resin cements (MS; RU) alone or cemented them with traditional resin cements (ZRV; ZVN) after pre-conditioning with a zirconia primer. A shear bond strength (SBS) test were performed after subjecting them to 19 different aging conditions (n = 15) comprising 30,000× thermocycles, air storage at room temperature (RT), water storage at RT, or at 37 °C for 24 h, 1 week, 1, 3, 6, and 12 months. Zirconia powders mixed with zirconia primer or 2 self-adhesive resin cements were characterized by X-ray photoelectron spectroscopy.ResultsGroups MS and ZVN obtained the highest SBS after all of aging methods. SBS after 6 months of storage was similar to SBS after 24 h of storage, while both were higher than SBS after 1 year of storage. Water storage at 37 °C provided higher SBS than RT water storage did. We detected a Zr–O–P bond in both self-adhesive resin cement/zirconia powder mixtures.ConclusionsApplication of self-adhesive resin cements alone could be an alternative to pre-conditioning with a zirconia primer followed by the application of conventional resin cements. Formation of Zr–O–P bonds contributed to the bonding improvement of self-adhesive resin cements. Different aging conditions affected SBS values.     

不同基原秦皮、香豆素单体抗菌作用对比研究

目的研究4种基原秦皮提取物、5种香豆素单体、5种单体混合物、苦枥白蜡树树皮已知香豆素指纹区样品、未知成分指纹区样品的体外抑菌作用。方法采用体外抑菌试验微量定量检测方法,测定最小抑菌浓度及最低杀菌浓度。结果4种基原秦皮苦枥白腊树、尖叶白腊树、白腊树、宿柱白腊树树皮均有明显抑菌、杀菌作用,抑菌强度依次为：宿柱白腊树〉苦枥白腊树〉尖叶白腊树〉白腊树。5种香豆素单体秦皮素、秦皮乙素对9种细菌均有明显抑菌、杀菌作用,秦皮甲素、秦皮苷对金黄色葡萄球菌、表皮葡萄球菌有一定抑菌、杀菌作用,抑菌作用依次为：秦皮素〉秦皮乙素〉秦皮甲素〉秦皮苷〉6,7-二甲氧基-8-羟基香豆素。苦枥白腊树树皮提取物对所试9种细菌均有明显抑菌作用;单体混合物,已知香豆素指纹区样品对金黄色葡萄球菌、表皮葡萄球菌、乙型溶血性链球菌、绿脓杆菌、大肠杆菌、肺炎克雷伯氏菌、卡他菌有明显抑菌作用;未知成分指纹区样品对金黄色葡萄球菌有明显抑菌作用,对表皮葡萄球菌、甲型溶血性链球菌、乙型溶血性链球菌、大肠杆菌、沙门氏菌也有一定抑菌作用。结论秦皮抑菌强弱与已知香豆素成分含量高低基本一致。秦皮中苷元的抑菌作用优于苷,5种香豆素类单体中秦皮素、秦皮乙素抑菌作用最强。     

自动顶空气相色谱法同时测定食品包装材料中氯乙烯、1,1-二氯乙烷和1,2-二氯乙烷单体

目的:建立食品包装材料中残留氯乙烯、1,1-二氯乙烷和1,2-二氯乙烷单体含量的自动顶空毛细管气相色谱分析方法。方法:准确称取样品于顶空瓶中,加入N,N二甲基乙酰胺,加盖密封,放入自动顶空进样器,供气相色谱分析,外标法定量。采用DB-624毛细管柱和火焰离子化检测器测定。结果:在本实验条件下,氯乙烯、1,1-二氯乙烷和1,2-二氯乙烷单体线性关系良好(r分别为0.9950、0.9992和0.9977)。平均回收率为84%～102%,相对标准偏差(RSD)为0.29%～1.72%。结论:该法简便、快速、灵敏、准确,适合食品包装材料中残留氯乙烯、1,1-二氯乙烷和1,2-二氯乙烷单体的测定。     

骨水泥单体对新西兰白兔心肺功能的影响

目的:通过动物实验探讨骨水泥单体(MMA)对新西兰白兔心肺功能的影响。方法:将28只新西兰白兔随机分为4组,每组7只。对照组静脉注射0.35ml生理盐水,其余各组静脉注射不同剂量的MMA,即:MAX(0.35ml)组、MID(0.10ml)组和MIN(0.02ml)组。静注后动态观察实验动物的血压心率变化;检测动脉血氧分压;观察实验动物心肺的病理改变。结果:MAX组7例均出现明显的血压下降、心律异常和氧分压下降,有6例死亡;MID组出现中等程度的血压下降和氧分压下降,无1例死亡;MIN组出现轻微的血压下降,心律异常和氧分压下降;对照组心率血压和血氧分压无明显变化。病理显示MAX组和MID组动物肺组织出血水肿,MAX组心脏标本可见心内膜下血栓。结论:MMA有心肌和肺毒性,具有剂量依赖性。MMA毒性可能是骨水泥植入综合征致病因素之一。     

2味治疗白癜风中药的有效单体成分鉴定

目的:探讨补骨脂和女贞子2味中药治疗白癜风的有效单体成分,为临床合理用药提供参考依据。方法:采用不同提取方法提取样品,以薄层色谱(TLC)法进行定性鉴别。结果:TLC法检出补骨脂中含有山柰素、柚皮素、补骨脂素、异补骨脂素、阿魏酸和齐墩果酸;女贞子中含有山柰素、柚皮素、阿魏酸和齐墩果酸。结论:所建方法简便、可靠、重现性好,证实了2味中药含有多种激活酪氨酸酶活性的单体化合物。     

聚乳酸中单体残留的定量检测方法

目的建立以二氯甲烷为溶剂的聚乳酸中丙交酯单体残留的定量检测方法。方法气相色谱法,溶剂为二氯甲烷,内标物为2,6-二甲基-γ-吡喃酮,沉淀剂为丙酮:环己烷=3:16。结果在0.5~10.0μg/ml范围内,峰面积与浓度呈良好的线性关系(r2=0.9990),平均回收率为94.8%。结论本方法准确,重现性好,可用于聚乳酸中残留单体含量的定量检测。     

氯乙烯接触工人的染色体损伤状况及其影响因素

[目的]3年随访观察氯乙烯接触工人的染色体损伤状况,并探讨其与性别、年龄、氯乙烯暴露时间、吸烟、饮酒、氯乙烯代谢酶多态等因素间的关系。[方法]从2004年4月至2007年4月对某化工厂77名氯乙烯接触工人进行随访,采用外周血淋巴细胞胞质分裂阻滞微核（CBMN）试验检测染色体损伤状况,比较3年内微核细胞率变化情况;采用PCR-RFLP法检测CYP2E1、CYP2D6基因多态;采用PCR法检测GSTT1、GSTM1基因缺失情况。[结果]2007年所检测的微核细胞率高于2004年,两者相差3.63％。（P〈0.05）;多因素Poisson回归分析表明,微核细胞率有随工龄的延长而升高的趋势,CYP2E1（CG／CC）基因型和CYP2D6（CG／GG）基因型为危险因素,两者的相对危险度（frequency ratio,FR）分别为1.29（95％CI：1.02-1.63）和1.40（95％CI：1.12-1.77）;未见GSTT1和GSTM1基因型对微核细胞率变化有明显影响。[结论]氯乙烯作业工龄、CYP2E1和CYP2D6基因等因素与氯乙烯致染色体损伤进程有关。     

Parkinson disease-associated mutation R1441H in LRRK2 prolongs the “active state” of its GTPase domain

Mutation in leucine-rich-repeat kinase 2 (LRRK2) is a common cause of Parkinson disease (PD). A disease-causing point mutation R1441H/G/C in the GTPase domain of LRRK2 leads to overactivation of its kinase domain. However, the mechanism by which this mutation alters the normal function of its GTPase domain [Ras of complex proteins (Roc)] remains unclear. Here, we report the effects of R1441H mutation (Roc_R1441H) on the structure and activity of Roc. We show that Roc forms a stable monomeric conformation in solution that is catalytically active, thus demonstrating that LRRK2 is a bona fide self-contained GTPase. We further show that the R1441H mutation causes a twofold reduction in GTPase activity without affecting the structure, thermal stability, and GDP-binding affinity of Roc. However, the mutation causes a twofold increase in GTP-binding affinity of Roc, thus suggesting that the PD-causing mutation R1441H traps Roc in a more persistently activated state by increasing its affinity for GTP and, at the same time, compromising its GTP hydrolysis.Mutation in leucine-rich-repeat kinase 2 (LRRK2) is a common cause of Parkinson disease (PD) (1–5). LRRK2 is a large (2,527-aa) multidomain protein consisting of seven putative domains (2), including a Ras-like GTPase domain called Ras of complex proteins (Roc), followed by a domain called C-terminal of Roc (COR), which is then followed by a kinase domain (Kin). It remains unclear how perturbations of these activities result in disease; however, the most common mutation in LRRK2-associated PD, G2019S in the kinase domain, shows higher kinase activity than wild type; therefore, its overactivation might be associated with disease pathogenesis (6).The tandem Roc-COR-Kin arrangement suggests that their activities might be coupled such that the GTPase activity of Roc might modulate the kinase activity. Indeed, several studies have shown that GTP binding to the Roc domain regulates the activity of the Kin domain (7, 8). Moreover, a PD-associated mutation in the Roc domain (R1441C) has been shown to have higher kinase activity (9), thus suggesting that mutations in the Roc domain, also up-regulate kinase activity.Understanding the function of Roc and its mechanism of action is important for understanding the mechanism of PD pathogenesis and therapeutic development. However, because of the lack sufficient quantity of protein samples amendable for detailed investigations, the biochemical properties and enzymatic activities of the Roc domain of LRRK2 are poorly understood.Here, we describe a stably folded construct of human Roc domain that enabled us to investigate quantitatively its biochemical and enzymatic properties. The results revealed that a PD-causing mutation R1441H in the Roc domain renders it less active at hydrolyzing GTP, as well as having higher affinity for GTP, than its wild-type counterpart, thereby increasing the residence time of its GTP-bound “active state,” which is associated with PD pathogenesis (8).     

糖尿病合并冠心病患者F1+2及SFMC的变化及意义

为探讨F1 2及SFMC在糖尿病合并冠心病中的变化及意义，采用酶联免疫吸附法(ELISA)检测28例糖尿病合并冠心病患者(试验组)静脉血凝血酶原片段1 2(F1 2)及纤维蛋白单体复合物(SFMC)水平，并与25例单纯糖尿病患者(对照组)进行比较。结果显示，试验组F1 2、SFMC水平均明显高于对照组(P＜0．005、＜0．01)，其它出凝血指标如凝血酶原时间(PT)、活化部分凝血活酶时间(APTT)、纤维蛋白原(Fbg)、血浆因子Ⅶ促凝活性(FⅦ：c)等两组比较无明显差异(P＞0．05)。试验组与对照组空脂血糖(FBG)、甘油三酯（TG)、总胆固醇(TC)、高密度脂蛋白胆固醇(HDL—C)水平无明显差异(P＞0，05)；低密度脂蛋白胆固醇(LDL—C)水平有显著性差异(P＜0．05)。两组血流变学中全血比粘度(中切)、血浆比粘度无显著性差异(P＞0．05)，红细胞压积、红细胞聚集指数有显著性差异(P＜0.05)。提示血栓前状态与糖尿病合并冠心病有密切关系，F1 2及SFMC可以作为糖尿病患者发生冠心病的预测指标。     

Structure–properties relationships in dental adhesives: Effect of initiator,matrix monomer structure,and nano-filler incorporation

Objectives

This is a confirmatory study to evaluate the effect of photoinitiator type and concentration, matrix monomer chemical structure, and nanoparticle incorporation on the physical and mechanical properties of an experimental dentin bonding agent.