Anti-biofilm effect of glass ionomer cements incorporated with chlorhexidine and bioactive glass

The effect of glass ionomer cement and resin-modified glass ionomer cement incorporated with chlorhexidine and bioactive glass on antimicrobial activity and physicochemical properties were investigated.The experimental results showed that groups incorporated with 1% chlorhexidine exhibited a significant reduction of optical density values of the bacterial suspension and increased the degradation of Streptococcus mutans biofilm.However,groups incorporated with 10% bioactive glass did not affect the optical density values and the biofilm formation.The mechanical properties of the materials and the polymerization were not influenced by the addition of chlorhexidine.Nevertheless,the compressive strength was lower when the materials were incorporated with bioactive glass.It can be concluded that glass ionomer cements incorporated with chlorhexidine can maintain its mechanical properties as well as reduce early S mutans biofilm formation.Controlled release/sustained release technology may be required to optimize the antibacterial activity of glass ionomer cements incorporated with bioactive glass.     

Ag_2O/TiO_2微球对变异链球菌生物膜形成的影响

生物膜状变异链球菌(Streptococcus mutans)是导致龋齿的主要细菌,为抑制该细菌,采用沉积沉淀法制备Ag_2O/TiO_2复合物,并以X射线衍射、电感耦合等离子体质谱和透射电镜对所合样品的组成和形貌进行表征。通过抑菌圈和最低抑菌浓度(MIC)法测定Ag_2O/TiO_2对Streptococcus mutans的抗菌活性,此外Ag_2O/TiO_2对Streptococcus mutans生物膜形成、产酸和胞外多糖(EPS)的影响进行测定。结果显示所合成的Ag_2O/TiO_2复合物为直径2～3 mm的微球,其中Ag_2O在Ag_2O/TiO_2中所占质量分数为24.80%。Ag_2O/TiO_2对浮游状Streptococcus mutans的MIC值为64 mg/L,且能显著抑制Streptococcus mutans产酸。125 mg/L Ag_2O/TiO_2能减少61.9%生物膜形成,水可溶性的EPS和水不可溶性的EPS的产生分别减少56.1%和69.5%。结果表明Ag_2O/TiO_2可能是一种有效的预防龋齿材料。     

高良姜根茎的化学成分及抗口腔菌活性测定

对中药高良姜的化学成分进行研究,利用硅胶柱层析、SephadexLH-20柱层析及重结晶等方法进行分离纯化,得到黄酮及二苯庚烷类化合物共10个,通过波谱技术鉴定结构,并采用MTT法进行actinomyces viscosus ATCC 27044黏性放线菌和streptococcus mutans ATCC 25175变链球菌两种口腔菌的活性测定,结果显示仅化合物6对黏性放线菌有一定的抑菌活性,其余化合物均无明显活性.     

桦木酮缩氨基硫脲铜、银、钯、镉金属配合物的合成、表征与生物活性研究

运用拼合原理,合成了4种桦木酮缩氨基硫脲配体及其铜、银、镉、钯金属配合物,通过核磁共振氢谱(¹H NMR)、红外光谱(IR)、元素分析、热重谱(TG)、飞行时间质谱(MALDI-TOF-MS)和元素分析对配体和配合物进行了结构表征.以最小抑菌浓度(MIC)评价了S.aureus 4220、S.mutans 3289、S.mutans 3065、E.coli 1924和E.coli 1356的抑菌活性.结果表明:Ag(L₄)₂Cl₂·2H₂O对S.aureus 4220、S.mutans 3065和E.coli 1924具有相对较好的抑制作用; Ag(L₁)₂NO₃·2MeOH、Cu(L₃)₂Cl₂·H₂O、Ag(L₃)₂Cl·3H₂O、Cd(L₃)₂Cl₂、Cu(L₄)₂Cl₂和Ag(L₄)₂Cl₂·2H₂O对Hela细胞有显著的抑制作用.     

Bacteria adherence properties of nitrided layer on Ti6Al4V by the plasma nitriding technique

The nitrided layer on Ti6A14V substrate was prepared by the plasma nitriding technique. The sample was characterized by X-ray diffraction （XRD）, glow discharge optical emission spectroscopy （GDOES）, X-ray photoelectron spectroscopy （XPS）, and rough-meter. X- ray diffraction analysis reveals that TiN, Ti2N and Ti phase exist in the nitrided layer subsurface. GDOES analysis shows the thickness of the nitrided layer is about 3 ~tm. XPS analysis shows that there is higher N, lower A1 and lower V in the nitrided layer surface than in the Ti6A14V surface. Rough-meter analysis results show the roughness of the nitrided layer is greater than that of Ti6A14V alloy base. The bacteria adherence property of the nitrided layer on Ti6A14V substrate on the Streptococcus mutans was investigated and compared with that of Ti6A14V alloy by fluorescence microscope. It shows that the nitrided layer inhibits the bacteria adherence.     

土壤拮抗放线菌的筛选及YYHS-2菌株的分类

采用平板分离法从抚顺东部山区不同植被类型土壤中分离出627株放线菌,对其进行皿内琼脂平板、发酵液及拮抗菌的拮抗性筛选。结果表明,YYHS-2等菌株对金黄色葡萄球菌(Staphylococcus aureus)、枯草芽孢杆菌(Bacillius subtilis)、大肠杆菌(Escherichia coli)、变形链球菌(Streptococcus mutans)等4种供试病原真菌具有强烈的拮抗作用。根据YYHS-2菌株的形态特征、培养特征、生理生化特征及细胞壁化学成分分析,均符合阎逊初放线菌分类系统中关于链霉菌的定义,可确定YYHS-2菌株归属于链霉菌属(Streptomyces)。     

费马大定理：Abel猜想的一个证明

1 IntroductionIn 1823 Abel made a conjecture in a particular case of Fermat's last theorem:If n>2and x,y and z are nonzero integers such thatx~n+y~n=z~n(1)then none of x,y or z can be a prime power(see P.Ribenboim[1],p.25).It is clear that we may assume,without loss of generality,that(x,y)=(x,z)=(y,z)=1and 0相似文献   

Urban management in China： Problems and solutions

Withtherapidgrowthoftheeconomy,upto2003,China’surbanizationrateaccountedfor40.5%(seeFig.1).Theurbanizationprocesshasenteredaperiodofacceleratedgrowth.Urbandevelopmentplaysanim portantroleinChina’seconomicgrowth.Inrecentyears,municipalgovernmentshavebegu…     

Observer design for matrix second-order linear systems： a parametric approach

1　IntroductionMatrixsecond orderlinear (MSOL)systemscapturethedynamicbehaviorofmanynaturalphenomenaapplicationshavebeenfoundinmanyfields ,suchasvibrationandstructuralanalysis ,spacecraftcontrolandrobotcontrol,hence ,moreattentionhavebeenattracted[1～ 6] .In [2 ],thecontrollabilityandobservabilityofMSOLsystemsstudieddirectlyinthematrixsecond orderframework .Theobserverdesigntechniqueintroducedinthelate 60s[7] hasbeendevelopedquickly .Manyresearchersconsideredthedesignofvariouskindsofobserv…     

百千瓦级高峰值功率Tm：YLF激光器

为研制一款具有高峰值功率与高光束质量的2μm波段固体激光器,搭建二极管激光器(laser diode,LD)单端抽运声光调Q Tm∶YLF激光器.激光器的输出中心波长为1 879 nm,采用声光调Q技术,得到重复频率为2 k Hz的脉冲激光输出,峰值功率达到100. 2 kW,最大单脉冲能量为5. 25 m J,最短脉冲宽度为52. 2 ns,光-光转换率为30%,斜率效率为33%.光束M2因子分别为x方向1. 51和y方向1. 71,光束质量良好.该激光器同时具有高峰值功率与优良光束质量的特点,可广泛用于透明塑料的精细加工、激光医疗以及工业打标等领域.     

Biocompatibility Studies on Bone Marrow Stromal Cells with Chitosan-gelatin Blends

1　IntroductionSuccessfulmanagementofcartilagedefectsremainsamajorclinicalchallengetoorthopedicsurgeons .Theneedformoreeffectivemethodsofrepairingcartilagedefectshaspromptedinvestigationintotheutilityoftissueengi neeringapproachesrecently .Thechoiceofbiom…     

碳酸钙微球合成、修饰及作为基因载体的研究

采用聚苯乙烯磺酸钠（PSS）作为调控剂,将其加入到氯化钙和碳酸钠溶液反应体系中成功制备出表面粗糙的碳酸钙微球（粒径平均约为510nm）,采用场发射扫描电镜（FE-SEM）、红外光谱（FTIR）、X-射线衍射（XRD）和动态光散射（DLS）等对碳酸钙微球颗粒进行表征。MTT实验显示碳酸钙微球毒性具有浓度依赖性,在终浓度〈1mg/mL时,细胞存活率都可达60%以上,显示出很低的细胞毒性,具有良好的生物相容性。不同pH值条件下碳酸钙微球的降解实验结果显示碳酸钙微球在酸性pH下能够更快速地降解,说明碳酸钙微球能够响应酸性pH值,具有pH依赖性。将碳酸钙微球经PEI表面修饰后用于负载质粒DNA,通过琼脂糖凝胶电泳及体外转染实验结果证实碳酸钙微球能够有效负载质粒DNA,并可在癌细胞内成功表达发出绿色荧光。这些研究结果显示将碳酸钙微球作为一种安全的非病毒基因载体用于基因治疗领域具有潜在的应用价值。     

魔芋葡甘低聚糖硫酸酯抗柯萨奇病毒B3药理作用

用不同浓度HOGS的维持液培养Hela细胞,MTT法测定药物对细胞的毒性作用;培养上清液滴定TCID50;按HOGS与病毒的不同作用方式进行分组,采用CPE观察法结合MTT法得出其抗CVB3活性最好的一组并进一步得出其抗CVB3半数有效浓度及治疗指数.结果显示HOGS对细胞无明显毒性作用,半数中毒浓度TC50为0.167 7 mg/mL;HOGS对CVB3直接作用的效果随着时间的延长有所增强,中和3 h后效果最好,其半数有效浓度IC50为0.775 7 mg/mL治疗指数TI为4.63;HOGS对CVB3侵入细胞的阻断作用组随着时间的延长其效果也较有所增强,作用4 h后IC50为0.351 7 mg/mL的TI为2.10.通过对HOGS抗病毒药理作用的研究可证实HOGS具有一定的直接抗CVB3作用并且对细胞有较好的保护作用,对CVB3的吸附、穿入等环节随着时间的延长其效果较有所增强.     

半夏凝集素的分离纯化及其对HeLa细胞生长的影响

利用甘露糖-Sepharose4B亲和柱从半夏总蛋白中分离纯化得到一种12kD的半夏凝集素,经质谱分析明确其为半夏凝集素单体。将该12kD凝集素单体作用于体外培养的HeLa细胞,MTT法检测细胞活性并用倒置相差显微镜观察凝集素对HeLa细胞生长状态的影响。结果显示：低浓度（O．004、0．02、0．1mg／mL）半夏凝集素具有一定促进HeLa细胞增殖的作用;高浓度（0．5、1mg／mL）半夏凝集素有一定抑制Hela细胞增殖的作用。     

壳聚糖膜的制备及其表面浸润性

采用流延法,通过调节壳聚糖溶液的质量分数制备表面结构不同的壳聚糖膜,并通过扫描电子显微镜和静态接触角测定仪对膜表面形貌及浸润性进行了研究。结果表明,壳聚糖溶液的质量分数是壳聚糖膜表面形貌的重要影响因素。在壳聚糖溶液的质量分数由2%增至8%条件下,所制备的壳聚糖膜的表面结构从有较强立体层次感的簇状凸起逐渐变得层次感降低,纹路密集,并出现很多紧密排列的小颗粒;膜表面的浸润性发生细微变化,在空气中均表现为既亲水又亲油的特性,而在水中油滴的表面接触角平均高达150°以上,即达到超疏油性。     

Laccase biosensor using magnetic multiwalled carbon nanotubes and chitosan/silica hybrid membrane modified magnetic carbon paste electrode

A simple and rapid strategy to construct laccase biosensor for determination of catechol was investigated. Magnetic multiwalled carbon nanotubes (MMCNT) which possess excellent capability of electron transfer were prepared by chemical coprecipitation method. Scanning electron microscope (SEM) and vibrating sample magnetometer (VSM) were used to identify its surfacetopography and magnetization, respectively. Laccase was immobilized on the MMCNT modified magnetic carbon paste electrode by the aid of chitosan/silica (CS) hybrid membrane. Using current-time detection method, the biosensor shows a linear response related to the concentration of catechol in the range from 10⁻⁷ to 0.165×10⁻³ mol/L. The corresponding detection limit is 3.34×10⁻⁸ mol/L based on signal-to-noise ratios (S/N) ≥3 under the optimized conditions. In addition, its response current retains 90% of the original after being stored for 45 d. The results indicate that this proposed strategy can be expected to develop other enzyme-based biosensors.     

In vitro and in vivo characterization of homogeneous chitosan-based composite scaffolds

With a homogeneous distribution of hydroxyapatite (HAP) crystals in polymer matrix, composite scaffolds chitosan/ HAP and chitosan/collagen/HAP were fabricated in the study. XRD, SEM and EDX were used to characterize their components and structure, in vitro cell culture and in vivo animal tests were used to evaluate their biocompatibility. HAP crystals with rod-like shape embeded in chitosan scaffold, while HAP fine-granules bond with collagen/chitosan scaffold compactly. A homogenous distribution of Ca and P elements both in chitosan/HAP scaffold and chitosan/collagen/HAP scaffold was defined by EDX pattern. The presence of collagen brought a more homogenous distribution of HAP due to its higher ability to induce HAP precipitation. The results of in vitro cell culture showed that the composite’s biocompatibility was enhanced by the homogenous distribution of HAP. In vivo animal studies showed that the in vivo biodegradation was effectively improved by the addition of HAP and collagen, and was less influenced by the homogeneous distribution of HAP when compared with a concentrated distribution one. The composite scaffolds with a homogeneous HAP distribution would be excellent alternative scaffolds for bone tissue engineering.     

Hexagonal hematite platelets synthesized from pyrite cinders by hydrothermal process

Well-crystallized hexagonal hematite (α-Fe2O3) platelets were synthesized by hydrothermal process,using a highly concentrated ferric hydroxide as precursor.The precursor was prepared by adding ammonia to the ferric sulfate solution which was obtained by leaching pyrite cinders with sulfuric acid.Structure and morphology of the synthesized products were investigated by X-ray diffraction,scanning electron microscope,transmission electron microscope and selected area electron diffraction.The results reveal tha...     

乙二胺桥联2-甲基邻菲罗啉镧(Ⅲ)配合物的合成及抗癌活性

合成并表征了乙二胺桥联2-甲基邻菲罗啉配体及其镧(Ⅲ)配合物,研究了配合物对人的HL60白血病、PC-3MIE8前列腺癌、BGC-823胃癌、MDA-MB-435乳腺癌、Bel-7402肝癌、Hela宫颈癌等6种瘤株的体外抗肿瘤活性及其与DNA的作用方式。结果表明,该化合物对实验的6种瘤株均具有明显的生长抑制作用,其作用机理可能是配合物以部分插入方式,同时伴随共价作用和静电作用与DNA发生作用,进而影响基因调控与表达,从而抑制肿瘤细胞的生长,最终导致癌细胞的死亡。     

凋亡蛋白对Bcl-2家族几个基因表达影响

凋亡蛋白（Apoptin）只诱导肿瘤细胞或转化的细胞凋亡,但其作用机制还不十分清楚．从鸡贫血病毒总DNA中克隆出凋亡蛋白基因,构建pcDNA3．1／CT—Apoptin—GFP—TOPO融合表达的载体．用该载体转染HHCC单层传代细胞24h后,观察到绿色荧光蛋白表达,同时观察到细胞形态呈凋亡特征变化．提取细胞总RNA,按SuperArray芯片操作方法检测到实验组Bcl-2家族中的BimL,Bcl-2,Bax和Bak基因上调表达．Bcl-2家族在细胞凋亡的过程中作用重要．凋亡蛋白诱导HHCC细胞凋亡过程中,促凋亡的BimL,Bax和Bak基因上调,抗凋亡的Bcl-2基因也上调．可能BimL与Bcl-2竞争性结合导致Bax或Bak释放,最终诱导细胞凋亡．揭示Bcl-2家族的基因参与凋亡蛋白诱导的HHCC细胞凋亡过程．