酪蛋白磷酸多肽钙磷复合体的应用顺序对乳牙牙本质粘结强度的影响

目的探讨酪蛋白磷酸多肽钙磷复合体(casein phosphopetide-amorphic calcium phosphat, CPP-ACP)应用顺序对乳牙牙本质粘结强度及对乳牙牙本质小管封闭作用的影响。方法选取人56颗无龋乳磨牙,磨除牙合面釉质,制备牙本质平面。将其中48颗乳磨牙随机分3大组(n=16)。A组:仅酸蚀15 s。B组:涂CPP-ACP后酸蚀15 s。C组:酸蚀15 s后涂CPP-ACP。各组分为2小组(n=8),其中AN,BN,CN组使用Prime&Bond NT(NT)全酸蚀粘结剂,AS,BS,CS组使用Single bond 2(SB2)全酸蚀粘结剂。制作树脂粘结试件,电子万能试验机测定剪切强度(SBS值)。其余8个乳磨牙随机分成4组(n=2),分别为空白组(S1组)、酸蚀组(S2组)、酸蚀后涂CPP-ACP组(S3组)、涂CPP-ACP后酸蚀组(S4组)分别用扫描电镜观察粘结前牙本质小管封闭情况。结果剪切实验结果为AN组、BN组、CN组剪切强度无统计学差异(P>0.05);AS组,BS组,CS组剪切强度也无统计学差异(P>0.05);AN组>AS组,BN组>BS组,CN组>CS组差异有统计学意义(P<0.05)。扫描电镜结果为S3组中牙本质小管封闭数目最多。结论在酸蚀后应用CPP-ACP处理乳牙牙本质不影响NT和SB2两种全酸蚀粘结剂的粘结强度;可以达到有效的牙本质小管封闭;Prime&Bond NT(NT)全酸蚀粘结系统的粘结强度高于Single bond 2(SB2)。     

Complement C3 isoforms in Austrelaps superbus

Complement C3 plays a pivotal role in both classical and alternate pathways. Lower organisms (urochordates and fishes) have multiple isoforms whereas higher organisms have a single C3 gene. In cobras, a closely related protein cobra venom factor (CVF) is expressed in their venom gland. We have recently shown that Austrelaps superbus contains two isoforms (AVF-1 and AVF-2) of CVF-like proteins in the venom gland. To understand the origin of these proteins and their similarity to C3 protein, we examined C3-like proteins in the liver. Here we describe the complete cDNA sequences of two isoforms (AsC3-1 and AsC3-2) of complement C3 found in A. superbus liver. This is the first report of molecular isoforms of C3 in a reptilian organism. These isoforms display the overall domain structure of complement C3 proteins. Real-time quantitative analysis shows that there is a 144-fold difference in their mRNA expression levels. We also demonstrate by Southern blot experiments that the venom gland isoforms (AVF-1 and AVF-2) and the liver isoforms (AsC3-1 and AsC3-2) are the products of four individual genes. The putative promoter regions of these four genes are highly similar ( approximately 99% identical) to each other. These genes represent a unique case where despite being identical at the genomic level, exhibit tissue specificity and differential gene regulation. These genes offer a system to identify the tissue-specific regulatory proteins that are responsible for the constitutive expression of complement C3 in liver and inducible expression of AVF genes in the venom gland of A. superbus.     

Er:YAG 激光和酸蚀预处理对自粘结树脂水门汀粘结强度的影响

目的:探讨Er:YAG 激光和酸蚀预处理对自粘结树脂水门汀粘结强度的影响?方法:44颗前磨牙根据对牙本质表面预处理方式的不同随机分为4组:对照组?Er:YAG 激光组?酸蚀组(35%磷酸)?Er:YAG 激光+酸蚀组?每组11颗牙中随机选出1颗切取3 mm厚牙本质片,按相应分组要求预处理后进行扫描电镜观察;每组剩余10颗牙制备一致标准牙本质表面后按相应分组要求预处理,用自粘结树脂水门汀RelyXTM Unicem将其与Everest ZS 氧化锆瓷片粘结,24 h后测试各组剪切粘结强度并进行统计分析?结果:扫描电镜观察显示采用不同方式预处理后,牙本质表面形态改变明显;统计分析结果显示剪切粘结强度由高到低为Er:YAG 激光组(7.18 ± 2.54)MPa?Er:YAG 激光+酸蚀组(5.50 ± 2.09)MPa?对照组(4.05 ± 1.04)MPa?酸蚀组(3.61 ± 0.70)MPa;Er:YAG 激光组?Er:YAG 激光+酸蚀组与对照组有显著性差异(P < 0.05),酸蚀组与对照组无显著性差异(P > 0.05)?结论:酸蚀对自粘结树脂粘结强度的改变无明显影响,Er:YAG 激光预处理能有效提高自粘结树脂与牙本质和氧化锆瓷的粘结强度?     

前阳离子脂质体的构建及有关性质研究

 目的制备前阳离子脂质体并考察其相关性质。方法化学合成含二硫键的胆固醇衍生物(2-[[4-[(羟甲基)二硫]-1-亚氨丁基]氨基]乙基]氨基甲酸胆固醇酯,CHETA);薄膜分散-膜挤压法制备空白前阳离子脂质体;以鱼精蛋白缩合质粒DNA再与空白前阳离子脂质体作用,形成载基因前阳离子脂质体;粒度电位测定仪测定前阳离子脂质体的粒径和Zeta电位,电镜观察形态;考察在二硫键还原酶二硫苏糖醇的作用下前阳离子脂质体Zeta电位变化情况;以LacZ为报告基因转染HepG2细胞,X-gal原位染色定性观察,并定量测定β-半乳糖苷酶活性和总蛋白含量计算转染效率。结果前阳离子脂质体形态近似于球体,平均粒径为145.8 nm(PDI=0.086),Zeta电位为-33.83 mV,载基因前阳离子脂质体转染肝癌细胞HepG2转染效率为12.18 mU·mg^-1 protein,是裸质粒的10.5倍。结论二硫键修饰的前阳离子脂质体是具有发展潜力的非病毒载体。     

不同树脂粘结剂及硅烷偶联剂对玻璃纤维桩与牙本质粘结强度的影响

[目的]评价不同树脂粘结剂及不同组份硅烷偶联剂对玻璃纤维桩与牙本质粘结强度的影响.[方法]将24颗单根管离体牙去除牙冠经常规根管治疗和预备,粘固MATCHPOST玻璃纤维桩.将每颗牙根垂直牙长轴切割出3个3.0mm的片段作为测试样本.根据涂布硅烷偶联剂的组份不同将离体牙随机均分为A组（双组份组）和B组（单组份组）;根据...     

光固化复合树脂与金属基底的瓷剥脱面间的粘结强度

目的：测定光固化复合树脂与金属烤瓷修复体金属基底的瓷剥脱面间的粘结强度,评价有机硅烷偶联剂对粘结强度的影响。方法：钴铬合金的瓷剥脱面用氧化铝喷砂、氢氟酸蚀刻后分为6个组,每组一半使用偶联剂,一半不使用偶联剂,分别与6种光固化复合树脂粘结,粘结试件经过冷热水温差循环后测定剪切粘结强度。结果：有偶联剂组剪切粘结强度为10．16～15．54MPa,分别高于无偶联剂组剪切粘结强度(6．11～9．01MPa);其中两种光固化复合树脂的粘结强度高于其它四种树脂。结论：光同化复合树脂与金属基底的瓷剥脱面间可获得较高的粘结强度,金属基底的瓷剥脱面经有机硅烷偶联剂处理后有利于提高其与树脂间的粘结强度不同的树脂类型对二间的粘结强度有影响。     

Water structure in [Phe4 Val6] antamanide • 12H2O crystallized from dioxane

Crystals of [Phe⁴ Val⁶] antamanide (cyclic[ValProProPhePhe]₂) grown from dioxane/H₂O, with space group P2₁2₁2 and cell parameters a= 15.099(4), b = 22.008(5) and c = 11.024(3) Å, are almost identical to crystals grown from H₂O/acetone, the structure of which was determined a number of years ago. Perpeptide molecule there are the equivalent of 12 water molecules occupying 16 sites in both crystals; however, in the new investigation a number of water molecules present at one-half occupancy have been found in different positions than in the earlier analysis. The interpretation of the hydrogen bonding between peptide/water and between water/water is much more satisfactory. Pentagonal water assemblies are present in the solvent channel. There is a distinct indication of the occurrence of a bifurcated bond between two water molecules, as well as the presence of three-center hydrogen bonds joining three water molecules. This may be the first experimental example of a bifurcated bond between two water molecules.     

Implant Surface Modification Using Laser Guided Coatings: In Vitro Comparison of Mechanical Properties

Purpose: Plasma-sprayed hydroxyapatite (HA)-coated implants show failures along the coating–substrate interface due to poor bond strength. We analyzed HA coatings obtained by pulsed laser deposition (PLD) and compared them to commercially used plasma-sprayed coatings with respect to their bond strength to titanium alloy (Ti-6Al-4V), as well as surface roughness alterations produced by each of the two deposition methods.
Materials and Methods: Twelve titanium alloy disks were plasma-sprayed under commercial implant coating conditions, and 24 titanium alloy disks were coated using PLD. All coatings were characterized by the presence of the different calcium phosphate (CaP) phases. The plasma-sprayed coatings (n = 12) were predominantly HA, and the pulsed laser-deposited coatings were hydroxydyapatite (n = 12) and HA coating with a tetra calcium phosphate (TTCP) phase (n = 12). The surface roughness was analyzed before and after the coating processes to assess roughness changes to the surface by the coatings. The adhesive bond strengths of these coatings to the substrate titanium alloy was tested and compared. Scheffé's test was used to analyze the statistical significance of the data.
Results: The surface roughness alteration following PLD was a decrease of 0.2 μm, whereas following plasma spraying the decrease was 1.0 μm. Bond strengths were as follows [mean (SD) in MPa]: pulsed laser-deposited HA coatings: 68.3 (17.8); pulsed laser-deposited HA with tetra-CaP: 55.2 (21.1); plasma-sprayed HA 17.0 (2.8). The multivariate Scheffé's test revealed that HA coatings obtained by PLD had significantly increased bond strengths compared with the plasma sprayed ones ( p ≤ 0.05).
Conclusions: HA coatings obtained by PLD showed greater adherence to titanium alloy. PLD offers an alternative method to produce thinner coatings with better adherence properties, along with precise control over the deposition process.     

Variation at the mu-opioid receptor gene (OPRM1) influences attachment behavior in infant primates

In a variety of species, development of attachment to a caregiver is crucial for infant survival and partly mediated by the endogenous opioids. Functional mu-opioid receptor gene polymorphisms are present in humans (OPRM1 A118G) and rhesus macaques (OPRM1 C77G). We hypothesized that rhesus infants carrying a gain-of-function OPRM1 77G allele would experience increased reward during maternal contact and would, therefore, display increased measures of attachment. We collected behavioral data from rhesus macaques (n = 97) during early infancy and at 6 months of age, across four cycles of maternal separation (4 days) and reunion (3 days). Animals were genotyped for the OPRM1 C77G polymorphism, and the effects of this allele on attachment-related behaviors were analyzed. Infants carrying the G allele exhibited higher levels of attachment behavior during early infancy. During prolonged periods of maternal separation, although infant macaques homozygous for the C allele exhibited decreases in their levels of distress vocalization with repeated separation, this response persisted in G allele carriers. The OPRM1 77G allele also affected social preference during reunion. C/G infants spent increasing amounts of time in social contact with their mothers as a function of repeated separation and were less likely to interact with other individuals in the social group, a pattern not observed among infants with the C/C genotype. These findings suggest a role for OPRM1 variation in the expression of attachment behavior in human subjects, especially as a function of separation from the caregiver.