对氨基苯甲酸对变形链球菌生长影响的体外实验

目的:探讨不同浓度的对氨基苯甲酸(PABA)对变链菌生长的影响。方法:将变形链球菌ATCC25175(血清c 型)在改良Carlsson培养基中厌氧培养,实验组在其中加入不同浓度(10-10~10-3gPL)的PABA液厌氧培养48 h后采用紫外可见分光光度仪测定细菌浓度OD值(K=550 nm),并在琼脂平板上培养观察细菌生长情况,进行菌落计数。结果:菌液比浊及菌落计数结果均表明PABA确有促进变链菌生长的能力,当PABA的浓度从10-10~10-4gPL增大时,其促进变链菌生长的能力增强,但当PABA浓度增大到10-3gPL,则促进变链菌生长的能力开始下降。当PABA 浓度为10-9~10-3gPL时,实验组的细菌生长明显高于对照组(P<0105)。结论:当PABA的浓度为10-4gPL时,其促进变链菌生长的能力达最强,高于或低于此浓度,这种促生长作用均下降。     

对氨基苯甲酸对牙龈卟啉单胞菌生长代谢影响的研究

目的 通过对氨基苯甲酸（para-aminobenzoic acid,PABA)对牙龈卟啉单胞菌生长代谢的影响，研究血链球菌在龈下菌斑生态平衡中的作用。方法 在培养基中加入不同浓度的PABA，对牙龈卟啉单胞菌行常规厌氧培养，测定培养后的细菌浓度吸光度（A）值和胰酶样蛋白酶活性，并用扫描电镜观察菌细胞形态。结果 PABA能促进牙龈卟啉单胞菌的生长和胰酶样蛋白酶的活性，当PABA浓度为1mg/L时，其促进作用最强，随着PABA浓度的升高，促进作用降低，当PABA浓度为100mg/L时，无明显的促进作用。PABA还能对菌细胞的形态和粘附产生影响。结论 PABA能影响牙龈卟啉单胞菌的生长代谢，提示血链球菌可能对龈下菌班的微生态平衡具有调节作用。     

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。     

乳杆菌和变链菌的产酸脱矿实验研究

乳杆菌和变链菌为牙本质龋中的主要检出细菌 ,对 2种细菌产酸和引起牙本质脱矿能力的研究 ,有助于了解它们在牙本质龋发生发展中的作用。1　材料和方法1 1　培养基　ＴＳＢ(乳酪消化大豆胨肉汤培养基 ) :胰酶消化酪蛋白 17ｇ ,木瓜酶消化大豆胨 3ｇ ,氯化钠 5ｇ,磷酸氢二钾2 .5ｇ ,葡萄糖 2 .5ｇ ,蒸馏水 10 0 0ｍｌ。ＰＹＧ(蛋白胨酵母葡萄糖培养基 ) :蛋白胨 2 0ｇ ,0 0 2 5 %刃天青溶液 4ｍｌ,酵母浸出粉 10ｇ,盐酸半胱氨酸 0 .5ｇ ,ＶＰ盐溶液 40ｍｌ,葡萄糖 40ｇ,蒸馏水 10 0 0ｍｌ。1 2　细菌及培养　将乳杆菌临床分离株ＬＢ95 0 5 1…     

P物质和降钙素基因相关肽对成骨细胞增殖和活性的影响

目的:观察P物质(substance P,SP)和降钙素基因相关肽(calcitonin gene-related peptide,CGRP)对成骨细胞增殖和活性的影响。方法:采用新生大鼠颅盖骨组织块培养成骨细胞,再加入不同浓度的SP和CGRP,观察细胞生长数量及测定碱性磷酸酶活性。结果:SP和CGRP在浓度为1×10-8mol/L时对成骨细胞增殖的促进作用最强,SP在浓度为1×10-8mol/L,CGRP在浓度为1×10-12mol/L时对成骨细胞活性的促进作用最强,并均有统计学意义。结论:SP和CGRP均对成骨细胞增殖和活性有促进作用。     

酪蛋白磷酸肽钙磷复合体对发酵乳杆菌生长影响的实验研究

研究酪蛋白磷酸肽钙磷复合体(CPP-ACP)对发酵乳杆菌生长的影响,探讨CPP-ACP作为一种生物防龋制剂的可行性.将发酵乳杆菌接种到BHI培养基中厌氧培养,实验组中加入不同浓度[0.5%～5.0%(W/V)]的CPP-ACP溶液,厌氧培养48 h后采用噻唑蓝(MTT)比色分析法测定细菌液的吸光度A值(λ=550 nm).随CPP-ACP浓度的升高,发酵乳杆菌的吸光度值降低,即发酵乳杆菌的活菌数减少(P<0.01).CPP-ACP对发酵乳杆菌的生长具有抑制作用,且随CPP-ACP浓度的升高抑制作用增强.     

质子通透性与变形链球菌耐酸性关系的研究

变形链球菌 (以下简称变链菌 )是公认的龋病致病菌 ,其致龋性除与其对牙面的粘附能力和产酸性有关外 ,还与其耐酸性密切相关。对致龋菌而言 ,耐酸性 (ａｃｉｄｔｏｌｅｒａｎｃｅ/ａｃｉｄｕ ｒａｎｃｅ)是指细菌能在低 ｐＨ值环境中生长和代谢碳水化合物产酸的性能。致龋菌均能产酸 ,但并非所有能产酸的细菌均能致龋 ,因为随着菌斑ｐＨ值的降低 ,一些细菌失去产酸能力 ,在临界 ｐＨ值时 ,只有少数耐酸的细菌如变链菌和乳杆菌能生长[1] 。变链菌是菌斑中最耐酸的细菌之一 ,其各遗传种在ｐＨ值低至 4 .0时仍能代谢蔗糖产酸[2 ,3] ,而其它很多…     

冠部牙本质深龋细菌学分析

目的：探明牙本质深龋中的主要相关菌。方法：利用色谱法、裂解法等对龋坏牙本质分三层作细菌分离、鉴定、分析。结果：牙本质龋中的主要相关菌为乳杆菌和变链菌,龋内层牙本质中的细菌含量较外层少。结论：乳杆菌促进牙本质龋的发展,在牙本质龋进展中脱矿在先,细菌入侵在后。     

蔗糖浓度对牙菌斑生物膜细菌组成及pH值影响的体外实验

目的 研究不同蔗糖质量浓度对体外牙菌斑生物膜细菌组成和pH值的影响,探讨口腔微生物在蔗糖存在下的致龋能力.方法 采集有龋者(龋失补牙面数＞3)集合牙菌斑样本5例,混合后在不同质量浓度(0、1.5、3.0、5.0及20.0g/L)蔗糖中体外培养生物膜;对生物膜进行聚合酶链反应-变性梯度凝胶电泳分析和细菌量计数,并行pH值监测.结果 随着培养基中蔗糖质量浓度增加,生物膜细菌种类减少;随着蔗糖质量浓度的升高(0、1.5、3.0、5.0、20.0g/L),生物膜培养36 h后所能达到的最低pH值呈降低趋势,分别为5.4、4.7、4.5、4.2及4.2;在有蔗糖时,最终12 h生物膜培养达到pH最小值约需6h,相比最初12h(约需10 h)明显缩短;对生物膜细菌量进行单因素方差分析结果显示,在蔗糖质量浓度为5.0g/L时细菌量最大,向下蔗糖质量浓度依次为3.0、20.0、1.5及0g/L,各组间相比差异有统计学意义(P＜0.05).结论 蔗糖浓度可影响体外牙菌斑生物膜的细菌组成和pH值,含蔗糖的培养基可筛选出具有潜在强产酸和耐酸能力的菌群.     

深龋乳牙根管细菌学分析

目的本研究的目的是对患有深龋的乳牙根管内细菌进行分析。方法选择12颗深龋乳牙，其中3颗有冷热刺激痛，其余9颗无临床症状。分别在微需氧(80％N2，10％H2，10％CO2)及厌氧条件(90％N2，10％CQ)下进行患牙根管细菌分离和鉴定。结果结果显示有症状牙的菌落形成单位(Colony Fomation Unit，简称CFU，下同)比无症状牙高，但二者间的差异无显著性。在这两组中，根管细菌的组成相似，并且与深龋的细菌组成相似。变链菌和乳杆菌占可培养细菌的比例比其它细菌高，差异有显著性，而且变链菌和乳杆菌的检出率比其它细菌高，差异亦有显著性。专性厌氧菌，如消化链球菌、韦荣氏菌、梭杆菌和普氏菌也有所检出，但其检出率和占可培养菌百分比均很低。结论微需氧致龋菌是乳牙龋源性牙髓炎的主要致病菌。     

柠檬提取物对口腔致龋菌生长影响的研究

目的:检测柠檬提取物的生物安全性,研究柠檬提取物对主要致龋菌生长的影响,为进一步机制研究提供依据。方法:柠檬提取物ICR小鼠急性毒性试验(LD50试验):实验分两组,实验组柠檬水提浓缩液按0.05ml/10g.bw灌胃,空白对照组室温、阳光等饲养条件与实验组相同。饲养14d观察动物反应,第15天处死,解剖检查脏器情况;采用琼脂稀释法研究柠檬提取物对5种主要致龋菌(变异链球菌、血链球菌、内氏放线菌、远缘链球菌、嗜酸乳杆菌)生长的抑制作用,并采用菌落计数法检测柠檬提取物对5种细菌生长的影响。结果:ICR小鼠在14d观察期中未发现死亡现象,处死后检查各脏器无异常现象。柠檬提取物对变异链球菌、血链球菌、远缘链球菌的最小抑菌浓度MIC(minimum inhibitory concentration)为4.5g/L,对嗜酸乳杆菌和内氏放线菌的MIC为2.25g/L。5种致龋菌在柠檬提取物作用下,其生长曲线均在第6小时左右出现明显的转折点,实验组与阴性组的细菌菌量均有显著性差异(P<0.05)。结论:柠檬提取物样品LD50大于5000mg/kg.bw,属于实际无毒物质;柠檬提取物对口腔致龋菌的生长有抑制作用。     

The effect of pH on the sensitivity of species of Lactobacillus to chlorhexidine and the antibiotics minocycline and spiramycin

The purpose of this study was to determine the sensitivity of a range of Lactobacillus species to chlorhexidine, Minocycline, and Spiramycin, at a range of pH from 5.0 to 7.4. Strains of Streptococcus were also tested for their sensitivity to chlorhexidine, as a comparison between the genera. There were both inter- and intra-species variations in the sensitivity of these strains to chlorhexidine. The strains tested were sensitive at pH 6.7 to the following levels of chlorhexidine (micrograms/mL): L. casei (6 strains), 10-60; L. plantarum (4 strains), 40; L. fermentum (13 strains), 2-20; L. brevis (1 strain), 10; and L. acidophilus (3 strains), 10-60. The Streptococcus species were sensitive to 1-4 micrograms/mL (13 strains); 4-10 micrograms/mL (3 strains); and 10-20 micrograms/mL (2 strains). One strain was able to survive 20 micrograms/mL. Chlorhexidine was found to be less effective at lower pH levels. The following examples show sensitivity (micrograms/mL) at pH 6.5 followed by sensitivity at pH 5.0: L. casei (ATCC 15008), 40,60; L. plantarum (CH 374), 40,100; L. fermentum (CH 324) 10,40; L. acidophilus (ATCC 4356), 10,40; and S. mutans (BM 52), 2,2. All of the strains of Lactobacillus tested with Spiramycin were resistant at pH 5.0. Minocycline was less affected by changes in pH, but at pH 7.4 Lactobacillus strains were more resistant to Minocycline as compared with Spiramycin. Both of these antibiotics are bacteriostatic, and therefore may have a more limited effect than a bactericidal agent such as chlorhexidine. The Lactobacillus strains tested required higher concentrations of chlorhexidine than did the strains of Streptococcus for a killing effect in vitro.     

柚皮苷对犬骨髓基质细胞体外增殖及成骨分化的影响

目的:研究犬骨髓基质细胞(bone marrow stromal cells, BMSCs)在柚皮苷诱导下定向成骨及成骨分化能力。方法:抽取犬骨髓,贴壁法体外培养,流式细胞仪鉴定,加入不同浓度柚皮苷(1×10-5、1×10-6、1×10-7、1×10-8、1×10-9 mol/L)诱导,以CCK-8检测药物毒性,定量检测碱性磷酸酶、von Kossa检测钙结节形成。采用SPSS20.0软件包对数据进行统计学分析。结果:经流式细胞仪检测,CD34、CD45低表达、CD90高表达分别为0.126%、0.075%和95.4%;柚皮苷浓度在10-6、10-7 mol/L时,能明显促进细胞增殖;经柚皮苷诱导后,碱性磷酸酶含量显著提高,其中,浓度为10-6 mol/L时,ALP相对值最高(P<0.05);von Kossa钙结节检测呈阳性。结论:犬骨髓基质细胞在柚皮苷诱导下能分化为成骨细胞。柚皮苷浓度为10-6 mol/L时,能明显促进骨髓基质细胞的增殖及分化。     

In vitro evaluation of antimicrobial property of silver nanoparticles and chlorhexidine against five different oral pathogenic bacteria

Introduction

Numerous antimicrobial agents are used to eliminate oral biofilm. However due to emergence of multi drug resistant microorganisms, the quest to find out biologically safe and naturally available antimicrobial agents continues.

Dentin decontamination using chloramine T prior to experiments involving bacteria

OBJECTIVES: This study aims to investigate the importance of ISO11405 recommended storage regime for extracted teeth in surface disinfectant chloramine T (chlT) prior to use in biofilm or in vitro caries studies involving microorganisms. ChlT may be absorbed into dentin and undergoes breakdown with organic material. METHODS: Extracted roots were stored in chlT (2 days), rinsed and transferred to distilled deionised water. HPLC at regular intervals determined chlT elution. At 4 weeks roots were boiled in water and eluent assessed with HPLC. ChlT breakdown (+/-organic material) over time was monitored with HPLC. ChlT minimum inhibitory/bactericidal concentration (MIC/MBC) against Lactobacillus acidophilus was evaluated using L. acidophilus broth and chlT serial dilutions. RESULTS: No significant increase in chlT elution was detected between 2h and 4 weeks (ANOVA, Tukeys, p>0.05), although levels tended to increase with time. ChlT detected in water was 0.005%, corresponding to 0.05% in dentin. After boiling (4 weeks) chlT breakdown products in water corresponded to 0.015% in dentin. MIC/MBC of chlT against L. acidophilus was 0.031%. SIGNIFICANCE: ChlT breakdown is accelerated by organic material. L. acidophilus is highly sensitive to chlT. ChlT readily leaches from dentin but rinsing does not reduce chlT concentration below MIC/MBC. Low levels of chlT may remain but will probably be in a less active form. Teeth disinfected in chlT for use in research involving bacteria must be stored in distilled water for at least 2h to reduce chlT concentration below MBC, although longer will give greater elution and breakdown.     

In vitro antimicrobial and resistance-modifying activities of aqueous crude khat extracts against oral microorganisms

OBJECTIVES: To assess antimicrobial activities of aqueous crude khat (Catha edulis) extracts against a panel of oral microorganisms and to test their ability to modify bacterial resistance to tetracycline and penicillin in vitro. DESIGN: Lyophilized aqueous extracts were prepared from three khat cultivars. The agar dilution method of the NCCLS was used to test the extracts, at concentrations of 20-1.25 mg/ml, against 33 oral strains. MIC was defined as the lowest concentration at which there was no visible growth. Slight growth was defined as marked growth reduction (MGR). The E-test was used to determine the MICs of tetracycline and penicillin-G for three resistant strains in absence and presence of a sub-MIC of the khat extracts (5mg/ml). RESULTS: Eighteen strains (55%) were sensitive to the extracts (MICs 5-20 mg/ml). Most of these were periodontal pathogens with Porphyromonas gingivalis and Tannerella forsythensis being the most susceptible (MIC 5-10mg/ml). Veillonella parvula, Actinomyces israelii and some streptococci were not sensitive. Except for Lactobacillus acidophilus that showed MGR at 1mg/ml, cariogenic species were neither sensitive. The extracts were active against Streptococcus pyogenes (MIC 10-20 mg/ml) but not against Candida albicans and Staphylococcus aureus. The presence of the khat extracts at a sub-MIC resulted in a 2-4-fold potentiation of the tested antibiotics against the resistant strains. CONCLUSIONS: Khat has water-soluble constituents possessing selective antibacterial activity against oral bacteria. There is preliminary evidence for presence of an antibiotic resistance-modifying component. Further investigation is needed to identify the active components and assess their clinical relevance.     

血液链球菌产生对氨基苯甲酸的实验研究：Ⅰ.反相高效液相色谱 …

In order to study the synthesis of para-aminobenzoic acid (PABA) by S. mutans and the role of PABA in the interaction between S. mutans and S. sanguis, a reversed-phase high-performance liquid chromatography (RP-HPLC) for analysis of PABA was developed. The results showed that the optimal chromatographic parameters were flow rate of 1.5 ml/min, T = 55 +/- 2 degrees C, methanol/phosphate buffer of 10/90(by vol) (pH 2.2 0.1 mol/L), m-hydroxybenzoic acid as an internal standard. The method is simple, rapid accurate and useful.