赤芍粗提物对变形链球菌影响的实验研究

目的研究赤芍粗提物对变形链球菌的生长、产酸、粘附及合成胞外多糖的影响。方法采用倍比稀释法测定不同浓度赤芍粗提物抑制变形链球菌生长的情况,通过统计学方法确定最低抑菌浓度（minimal inhibitory concentration,MIC）;再以MIC及低于MIC的4个倍比稀释浓度配制含药的胰酶解酪蛋白-植物蛋白胨-酵母提取物（trypticase-phytone-yeast extract medium,TPY）液体培养基,测定赤芍粗提物对变形链球菌产酸、粘附及合成胞外多糖能力的影响。结果赤芍粗提物抑制变形链球菌体外生长的MIC为12.5g/L;当赤芍粗提物浓度≥3.13g/L时有较明显地抑制变形链球菌产酸、粘附、合成水溶性胞外多糖的作用;当赤芍粗提物浓度≥6.25g/L时能明显抑制变形链球菌合成水不溶性胞外多糖。结论达到一定浓度的赤芍粗提物对变形链球菌的生长、产酸、粘附及合成胞外多糖均有一定的抑制作用。     

壳寡聚糖抑制变形链球菌的致龋能力

目的研究壳寡聚糖(chitooligosaccharide,COS)对变形链球菌生长、产酸及粘附能力的影响。方法选用变形链球菌标准株ATCC 25175,采用对倍稀释法测定COS对变形链球菌的最低抑菌浓度(minimum inhibitory concentration,MIC)和最低杀菌浓度(minimum bactericidal concentration,MBC);采用菌落计数法,通过时间—杀菌曲线的变化,分析COS对细菌生长速度的影响;将COS及变形链球菌菌悬液各1 m L接种于无菌试管内厌氧培养,使COS的终浓度分别达到1/2 MIC、1/4 MIC、1/8MIC,测定上清液p H变化并绘制p H曲线;采用液体闪烁计数法测定壳寡聚糖对变形链球菌粘附羟磷灰石能力的影响。结果 COS对变形链球菌的MIC和MBC分别为2.00 g/L和4.00 g/L;COS能有效抑制变形链球菌的生长,较高浓度时对细菌还具有杀菌作用。亚抑菌浓度的COS可显著影响变形链球菌的产酸性和粘附能力,并且这种抑制作用呈浓度依赖性。结论 COS对变形链球菌的生长、产酸和粘附能力均有抑制作用。     

白假丝酵母菌对变形链球菌产酸能力的影响

目的 初步探讨白假丝酵母菌对变形链球菌产酸能力的影响.方法 实验分A、B、C、D四组,依次为白假丝酵母菌单独培养、变形链球菌单独培养、两菌混合培养、空白对照组.在不同葡萄糖浓度(0.01 ～ 0.15 mol/L)或不同初始pH值(7.0～4.0)下,将两菌单独或混合培养48 h后,测定上清液pH值,采用析因设计资料的方差分析判断两菌的产酸能力间是否存在交互作用,并以变形链球菌单独培养(B组)为参照,评价两菌混合培养(C组)的产酸能力.结果 不同葡萄糖浓度下,白假丝酵母菌均可抑制变形链球菌的产酸力(P＜ 0.001).葡萄糖浓度小于或等于0.10 mol/L时,C组产酸量小于B组(P＜0.05);葡萄糖浓度达到0.15 mol/L时,B、C两组的产酸量差异无统计学意义(P＞0.05).pH为7.0～5.5时,白假丝酵母菌抑制变形链球菌的产酸力(P＜ 0.001)；pH≤5时,白假丝酵母菌对变形链球菌的产酸力无影响(P＞0.05).初始pH为7.0时,C组产酸量小于B组(P＜0.05)；初始pH降至6.5、6.0时,C组与B组差异无统计学意义(P＞0.05)；初始pH降至5.5以下时,C组的产酸量大于B组(P＜0.05).本实验条件下,混合培养的总产酸量随培养基的葡萄糖浓度升高呈增多趋势,随初始pH降低呈减少趋势.结论 白假丝酵母菌对变形链球菌产酸能力的影响及两菌混合培养的产酸力均与培养基葡萄糖浓度和初始pH有关.     

变形链球菌超声提取物对牙髓细胞增殖和天然免疫受体基因mRNA表达的影响

目的:观察变形链球菌超声提取物对牙髓细胞的增殖活性、天然免疫受体基因mRNA表达的影响。方法:采用组织块法原代培养牙髓细胞,通过不同浓度的变形链球菌超声提取物(1、10、100μg/ml)作用于牙髓细胞,MTT法检测牙髓细胞的增殖活性;荧光定量PCR检测牙髓细胞NOD2、TLR2和TLR4 mRNA的表达水平。结果:1μg/ml变形链球菌超声提取物处理24 h可促进牙髓细胞的增殖;10μg/ml和100μg/ml处理24 h和48 h可明显抑制细胞增殖。变形链球菌超声提取物(10μg/ml)作用于牙髓细胞后,NOD2、TLR2和TLR4 mRNA表达量均增加。结论:变形链球菌超声提取物可抑制牙髓细胞的生长,促进NOD2、TLR2和TLR4 mRNA的表达。     

柠檬提取物对变形链球菌乳酸脱氢酶和蔗糖酶活性的影响

目的 观察柠檬提取物对变形链球菌(Streptococcus mutans,Sm)乳酸脱氢酶、蔗糖酶活性的影响,探讨柠檬酸提取物抑制Sm致龋活力的相关机制.方法 采用二倍稀释法,用含2%蔗糖的胰蛋白胨大豆肉汤将柠檬提取物的抑菌浓度稀释为0.64、0.32、0.16、0.08及0.04 g/L共5个质量浓度的溶液(5个实验组),以胰蛋白胨大豆肉汤液体培养基作为空白对照组.加入Sm菌液,厌氧培养6、18、24及48 h,采用还原性辅酶Ⅰ氧化法测定乳酸脱氢酶活性、用pH计测定培养液的pH变化值(△pH),同时采用3,5-二硝基水杨酸显色法测定蔗糖酶的活性.结果 随着柠檬提取物浓度的升高(0.04～0.64 g/L),乳酸脱氢酶、蔗糖酶活性和△pH均逐渐降低(P＜0.01):加入Sm厌氧培养24 h后,Sm乳酸脱氢酶活性从(0.8025±0.0913)×103 U/L降至(0.2099±0.0283)×103 U/L,Sm蔗糖酶活性从(-0.0107±0.0003)×103U/L降至(-0.0078±0.0002)×103 U/L,Sm △pH从2.8067±0.0404降至2.5033±0.0416(24 h).各实验组之间及与空白对照组之间差异有统计学意义(P＜0.01);柠檬提取物对Sm产酸的抑制作用与对乳酸脱氢酶活性的抑制作用之间呈正相关(r=0.8120～0.9918,P＜0.01).结论 低于抑菌浓度的柠檬提取物对Sm乳酸脱氢酶活性和蔗糖酶活性及产酸能力都具有显著抑制作用,作用强度具有浓度依赖性,对对数期细菌抑制作用强于其他生长周期,具有防龋药物的潜能.     

复方五倍子煎剂对变形链球菌抑菌作用的实验研究

目的:观察复方五倍子制剂对变形链球菌的抑制作用。方法:将五倍子、大黄、甘草等10味中草药制成煎剂(GER) ,测量其不同浓度对变形链球菌生长、产酸、粘附等作用的抑制效果。结果:当GRE浓度为10 0 %时(最终浓度2 0 %W /V) ,细菌生长量仅为对照组的3 5 .6% ;粘附率下降12 .7% ;pH值升高1.5 4。药物浓度为5 0 %时(最终浓度10 %W /V) ,与对照组比较,细菌生长和粘附作用分别下降43 .8%和10 .6% ,pH值升高1.18。结论:GRE对变形链球菌有一定的抑制作用。     

siRNA干扰对变形链球菌耐氟菌ffh基因产酸能力的影响

目的:探讨变形链球菌耐氟菌(UA159-FR)ffh基因 siRNA干扰后对产酸能力的影响。方法:电穿孔法将siRNA转入UA159-FR与ffh基因序列靶向位点结合,将干扰前后细菌分别加入BHI培养液,含5%糖类的葡萄糖、蔗糖、乳糖、淀粉中培养,pH调至7.5,24 h后测终末pH。结果:转染结果成功;干扰前后不同糖培养基中变形链球菌耐氟菌ffh基因对产酸有显著差异(P<0.05);干扰前后在常规、葡萄糖、及乳糖中差异极显著(P<0.01);蔗糖中差异显著(P<0.05);淀粉中无显著差异。结论:变形链球菌耐氟菌中基因ffh对产酸能力影响显著。     

蜂胶抑制变形链球菌生长和粘附的体外研究

目的:研究蜂胶对变形链球菌生长和粘附的影响.方法:①抑菌实验;分别将水溶性蜂胶和醇溶性蜂胶提取物等比稀释,采用钢管琼脂扩散法对变形链球菌和远缘链球菌做抑菌实验,测定最小抑菌浓度.②粘附抑制实验:在含不同浓度水溶性和醇溶性蜂胶,洗必泰,乙醇的轻唾液体培养基中培养变形链球菌,8天后测定粘附于毛细管表面变形链球菌量,并进行比较.结果:对变形链球菌和远缘链球菌最小抑菌浓度分别是:水溶性蜂胶为0.031625%和0.25%;醇溶性蜂胶均为0.078%.蜂胶各组及洗必泰组均可显著抑制变形链球菌的粘附(P＜0.05),0.5%水溶性蜂胶组,醇溶性蜂胶组及洗必泰组抑制粘附作用更强,三组之间无显著性差异(P＞0.05).结论:水溶性蜂胶和醇溶性蜂胶对变形链球菌生长和粘附都有显著的抑制作用.     

对氨基苯甲酸对变形链球菌表面疏水性的影响

目的　研究血链球菌合成的生态调节因子---对氨基苯甲酸(PABA)对变形链球菌细胞表面疏水性的影响,从而进一步了解PABA影响细菌粘附的机制。方法　在不同PABA浓度(10-9g/L、10-7g/L、10-4g/L)的改良Carls- son液体培养基中厌氧培养变形链球菌,并采用微生物粘着碳氢化合物法测试细胞表面疏水性。结果　低浓度的 PABA可增强变形链球菌细胞表面疏水性,当浓度增加到一定范围则可降低其细胞表面疏水性。结论　PABA可能通过降低细菌非特异性疏水作用而抑制变形链球菌的粘附。     

银杏叶提取物对口腔致龋变形链球菌的作用研究

目的 :为探讨天然植物银杏叶的提取物对临床分离的致龋变形链球菌的体外抗菌实验。方法 :随机选取DMFT≥ 3的成人 5 4名 ,取牙菌斑接种于培养基中 37℃厌氧培养筛选传代 3次 ,每株均在 6个不同的药物浓度下进行抑菌实验 ,观察最小抑菌浓度 (MIC)。结果 :银杏叶的提取物对临床筛选出的 33例致龋变形链球菌株 ,最小抑菌浓度MIC5 0和MIC90分别为6 2 5g/L和 12 5g/L。结论 :在天然植物的提取物中 ,银杏叶提取物对临床致龋变形链球菌有较好的抑制作用     

维吾尔族不同龋敏感儿童变形链球菌临床分离株表面蛋白A区遗传多态性研究

目的:分析维吾尔族高龋和无龋儿童变形链球菌临床分离株表面蛋白A区基因遗传多态性与其黏附能力的关系。方法:通过细菌贴壁法进行维吾尔族儿童高龋组(dmft≥5)和无龋组(dmft=0)变链菌临床株黏附试验。选取黏附能力较强和较弱的菌株,提取细菌DNA,经PCR扩增其表面蛋白A区编码基因spaP-a后,利用限制性内切酶HaeⅢ进行限制性片段长度多态性分析。结果:高龋组黏附能力(33.92±8.79)%强于无龋组(27.53±7.45)%,差异有统计学意义(P<0.05)。经HaeⅢ酶切后,高黏附力组和低黏附力组变链菌均出现了A、B两种基因型,且在两组菌株中的分布情况不同,A基因型在高黏附力组居多,B基因型在低黏附力组居多,差异有统计学意义(P<0.05)。测序证实spaP-a基因的特异性碱基突变引起酶切位点改变而产生基因多态性。结论:维吾尔族不同龋敏感儿童变链菌临床株spaP-a基因具有得遗传多态性可能是其黏附能力出现差异的原因之一。     

六种茶叶对口腔常见致病菌的抑菌作用

目的：选用普通绿茶、龙井茶、红茶、茉莉花茶、紫阳茶、乌龙茶的水浸液对龋齿致病菌和牙周炎可疑致病菌变形链球菌、牙龈卟啉单胞菌、中间普氏菌、具核梭杆菌进行抑菌研究。探讨饮茶防龋的作用及防牙周病的可能性。方法：6种茶叶的水浸液倍比稀释5个浓度，用杯碟法对4种细菌进行抑菌实验，测量抑菌环直径。结果：6种茶较高浓度的水浸液(24mg／ml)均对变链菌都有抑菌作用；普通绿茶、红茶、茉莉花茶、乌龙茶水浸液饮用浓度(12mg／ml)即对变链菌有抑菌作用；普通绿茶水浸液在低浓度(6mg／ml)对变链菌就有抑菌作用。普通绿茶和红茶水浸液在饮用浓度(12mg／ml)对具核梭杆菌有很好的抑菌效果；普通绿茶和茉莉花茶的水浸液浓度在48mg／ml对牙龈卟啉单胞菌有抑菌作用。高浓度(48mg／ml)的普通绿茶水浸液对牙龈卟啉单胞菌、中间普氏菌、变形链球菌、具核梭杆菌均有抑菌作用。结论：普通绿茶的抑菌效果好于其它茶叶。     

绿茶多酚和氟化钠对变链菌形态学及酶学的影响

目的：为深入探讨绿茶多酚防龋机理。方法：以氟化钠为对照,观察了绿茶多酚对变链菌形态学及其蔗糖酶、葡糖基转移酶（ＧＴＦ）和乳酸脱氢酶（ＬＤＨ）的影响,同时检测了培养液中蛋白含量和ｐＨ值的改变。结果：绿茶多酚和氟化钠对ＧＴＦ均有抑制作用,前者强于后者,而对蔗糖酶影响不明显。绿茶多酚对ＬＤＨ无明显影响,不能阻止培养基ｐＨ的下降,对菌液蛋白总量无明显改变;而氟化钠对ＬＤＨ有影响,明显减少培养基ｐＨ值的下降,且使菌液蛋白总量明显增加。结论：绿茶多酚对ＧＴＦ具有很强的抑制作用,这是其抗变链菌致病作用的主要途径之一。     

Inhibition of Streptococcus mutans adhesion to buccal epithelial cells by an aqueous extract of Thymus vulgaris

OBJECTIVES: The aim of this study was to investigate the effect of an extract of Thymus vulgaris (thyme) on the growth of Streptococcus mutans (S. mutans) and the adhesion of this bacterium to human buccal epithelial cells. METHODS: Different concentrations of an aqueous extract of thyme were prepared and the effects investigated on growth of S. mutans. Furthermore, the effect of these extracts on adhesion of S. mutans to buccal epithelial cells was also investigated and compared with the effects of chlorhexidine digluconate. RESULTS: The data revealed that exposure of S. mutans to thyme extract showed a time and concentration-dependent decrease in bacterial viability. The greatest effect was observed when S. mutans had been exposed to 20% thyme extract for a period of 48 h which resulted in 96% inhibition of bacterial growth. Furthermore, the adhesion of S. mutans to buccal epithelial cells was also reduced when either buccal epithelial cells or S. mutans had been pre-incubated with different concentrations of aqueous thyme extracts (83-98% and 75-89% inhibition respectively). There was also greater reduction in the adherence of bacterial cells to buccal epithelial cells after mouth rinsing with 20% aqueous thyme extract compared to rinsing with chlorhexidine digluconate (45% and 89% inhibition of bacterial adhesion respectively). CONCLUSION: The diminished adherence of S. mutans to buccal epithelial cells after exposure to various concentrations of aqueous thyme extract as well as the antimicrobial properties of this plant may have clinical relevance.     

The antibacterial activity of plant extracts containing polyphenols against Streptococcus mutans

The minimum inhibitory concentrations (MIC) of commercially available and 70% aqueous propanone (P70) extracts from plants chosen for polyphenol content on Streptococcus mutans and other bacteria were determined using a standard susceptibility agar dilution technique to investigate their potential use as anticariogenic agents. The effects on adhesion of S. mutans to glass were also studied. The lowest MICs were for the P70 extracts of red grape skin (0.5 mg ml(-1)) and green tea and sloe berry skin (2 mg ml(-1)). The commercial extracts generally had a lower activity with a minimum MIC of 2 mg ml(-1) for tea extracts, grape seed extracts and Pynogenol (extract of maritime pine). All other extracts had MICs of > or = 4 mg ml(-1). Unfermented cocoa had greater antimicrobial activity than fermented cocoa and the activity of the fractionated extract increased with the extent of epicatechin polymerization. Epicatechin polymer had an MIC of 1 mg ml(-1) and an MBC of 64 mg ml(-1). Selected extracts were tested against other oral bacteria and showed activity against gram-positive organisms. P70 extracts of unfermented cocoa, epicatechin polymer fraction, green tea and red grape seed were bacteriostatic and prevented acid production when added at the MIC to cultures of S. mutans grown in a chemically defined medium supplemented with either glucose or sucrose. There was a reduction in viability which was greater when added to washed cells, but there were some viable cells after 24 h. The extracts also reduced adherence of S. mutans to glass.     

Comparative studies on the effect of crude aqueous (CA) and solvent (CM) extracts of clove on the cariogenic properties of Streptococcus mutans

A study was conducted to compare the efficiency of crude aqueous (CA) and solvent extracts (CM) of clove on the caries-inducing properties of Streptococcus mutans. The cariogenic properties investigated included the cell adhesion, cell-surface hydrophobicity and glucan synthesis activities of S. mutans. There was a significant difference between the effect of the CA and CM extracts on the adhesion of S. mutans (P < 0.05) within a concentration range of 5-15 mg/ml, the CM extract demonstrating a slightly higher inhibitory effect. However, the effect of the CM extract on the cell-surface hydrophobicity of S. mutans was weaker than that of the CA extract. The two extracts were found to reduce the synthesis of water-insoluble glucan (WIG) by almost 50% at a concentration as low as 0.5 mg/ml and the CM extract exhibited a significantly higher inhibitory effect than the CA extract (P < 0.05). The present findings indicate that both the CA and CM extracts exert inhibitory effects on the cariogenic properties of S. mutans and that the CA extract is as equally effective as the CM extract.     

壳寡聚糖对变形链球菌表面疏水性的影响

目的:研究壳寡聚糖对变形链球菌细胞表面疏水性的影响,从而进一步了解壳寡聚糖影响细菌黏附的机制。方法:使用不同浓度(10-2、10-1、1g/L)的壳寡聚糖溶液处理变形链球菌,并采用微生物黏着碳氢化合物法测试细胞表面疏水性。结果:随壳寡聚糖浓度增加,变形链球菌ATCC25175细胞表面疏水性有显著性降低。结论:壳寡聚糖可能通过降低细菌表面疏水作用而抑制变形链球菌的黏附。     

绿茶多酚防龋涂膜对口腔主要致龋菌的抑制作用

作者通过对绿茶多酚防龋涂膜抑菌效果的观察。发现绿茶多酚防龋涂膜对变形链球菌、远缘链球菌及乳酸杆菌具有明显的抑制作用。生长实验显示变形链球菌及远缘链球菌的生长抑制率与绿茶多酚防龋涂膜的浓度成正比，证明绿茶多酚防龋涂膜具有一定的防龋作用。     

血链球菌细菌素对牙龈卟啉单胞菌形貌及力学性质的影响

目的:研究血链球菌细菌素(简称血链素)对牙龈卟啉单胞菌(Porphyromonas gingivalis,P.g)形貌特征及力学性质的影响。方法:1)复苏、传代并鉴定血链球菌标准菌株ATCC10556、牙龈卟啉单胞菌标准菌株ATCC33277。2)将血链球菌低温高速离心、细胞破碎等方法提取血链素,使之作用于P.g,于37 ℃厌氧培养48 h。3)采用原子力显微镜(AFM)的接触模式,观察血链素作用前后P.g菌体的形貌变化。4)利用AFM测定血链素作用前后P.g的力-距离曲线,并计算黏附力及杨氏模量。结果:1)通过AFM的观察:P.g在血链素的作用下,菌体直径缩小、平均粗糙度及平均峰高度增加(P<0.05)。2)通过AFM的观察:血链素作用后,P.g的黏附力、杨氏模量显著降低(P<0.001)。正常P.g的黏附力平均值为(0.70±0.10) nN、杨氏模量平均值为(5.54±0.16) MPa;经血链素作用后P.g的黏附力平均值为(0.50±0.10) nN、杨氏模量平均值为(3.97±0.64) MPa。结论:1)血链素可引起牙龈卟啉单胞菌形貌特征发生改变。2)血链素可导致牙龈卟啉单胞菌的黏附力及杨氏模量降低。     

Antibacterial activity of polyphenol components in oolong tea extract against Streptococcus mutans

The purpose of the present study was to determine the antibacterial activity of oolong tea extract on oral streptococci, including Streptococcus mutans and Streptococcus sobrinus, and to identify the response to its components. Antibacterial activity was found when the extract was added to S. mutans cells in chemically defined medium but not in complex broth media. Further, pretreatment with bovine serum albumin reduced the antibacterial activity. The extract showed antibacterial activity against all of the oral streptococci examined, with the highest activity against S. mutans MT8148R. This activity was found to originate from a monomeric polyphenol-rich fraction, and it was stronger than that of pure polyphenols. Moreover, some combinations of monomeric polyphenols showed the highest level of antibacterial activity. These results suggest that the antibacterial activity of oolong tea extract is caused by a synergistic effect of monomeric polyphenols, which can easily bind to proteins.