口腔环境因素对血型链球菌和变形链球菌生长的影响：I.粘蛋白的影响

采用连续培养方法，以粘蛋白作为化学限定培养基中的限定性因子，观察血型链球菌（以下简称血链菌）和变形链球菌（以下简称变链菌）Ｉｎｇｂｒｉｔｔ（ｃ）的生长状态。结果显示变链菌不能生长于以粘蛋白作为唯一营养源的培养基中，而血链菌可以生长；两菌混合培养时的生长量均有所提高，表明两菌有协同降解粘蛋白作用。     

口腔环境因素对血型链球菌和变形链球菌生长的影响 Ⅰ．粘蛋白的影响

采用连续培养方法，以粘蛋白作为化学限定培养基中的限定性因子，观察血型链球菌（以下简称血链菌）和变形链球菌（以下称简称变链菌）Ｉｎｇｂｒｉｔｔ（ｃ）的生长状态。结果显示变链菌不能生长于以粘蛋白作为唯一营养源的培养基中，而血链菌可以生长；两菌混合培养时的生长量均有所提高，表明两菌有协同降解粘蛋白作用。     

超氧化物歧化酶对变链菌生长和粘附影响的实验研究

目的：了解超氧化物歧化酶（ＳＯＤ）对变链菌Ｉｎｇｂｒｉｔ、６７１５生长和粘附的影响情况。方法：用麦氏比浊法分别比较不同浓度ＳＯＤ对两种变链菌蔗糖琼脂培养基纯培养的细菌生长量；用液闪计数值比较ＳＯＤ对两种变链菌体外在羟基磷灰石（ＨＡ）上的粘附量。结果：在ＳＯＤ存在时，两种致龋菌的生长量大于没有ＳＯＤ时的生长量；ＳＯＤ作用于获得性膜和致龋菌的体外粘附过程时，两种致龋菌的粘附量显著降低，ＳＯＤ作用于致龋菌生长过程，变链菌Ｉｎｇｂｒｉｔ的粘附量升高，变链菌６７１５的粘附量显著降低。结论：外源性ＳＯＤ促进致龋菌的生长，使致龋菌的粘附量发生改变     

酪蛋白磷酸肽钙磷复合体对变形链球菌产酸影响的实验研究

目的 研究酪蛋白磷酸肽钙磷复合体（casein phosphopeptide-amorphic calcium phosphate，CPP-ACP）对变形链球菌产酸的影响，探讨CPP-ACP作为一种生物防龋制剂的可行性。方法 将变形链球菌加入含不同浓度CPP-ACP的蔗糖培养基中，厌氧培养48h，用精密pH计检测培养基上清液的pH值，计算pH的变化值ApH（初始pH值-终末pH值）。结果 随CPP-ACP浓度的升高，培养基上清液的pH值升高，ApH降低，即变形链球菌的产酸量降低（P〈0．01）。结论 CPP-ACP对变形链球菌产酸具有抑制作用，且随CPP-ACP浓度的升高抑制作用增强。     

两种糖对变异链球菌产酸能力影响的比较研究

目的:通过测量变异链菌代谢高果糖玉米糖浆(high-fructose corn syrup,HFCS)和蔗糖后△pH值的变化,比较两种糖对变异链球菌产酸能力的影响。方法:配制质量浓度为0.25%、0.5%、1%、3%和5%的高果糖玉米糖浆和蔗糖培养基,将变异链球菌UA159于上述各培养基37℃微需氧培养,分别于培养1、4、8、24、48 h各个时间点,用酸度计测量培养前后的pH值,计算ΔpH值,代表变异链球菌的产酸能力。结果:在本研究设定的糖浓度范围和培养时间段内,高果糖玉米糖浆(HFCS)和蔗糖培养基中的ΔpH值均随时间的延长而增大,在培养4～8 h内,HFCS培养基内pH值下降速度快于蔗糖培养基。在培养4、8、24 h时,5种浓度的HFCS培养基中ΔpH值均明显大于蔗糖培养基,差异均有统计学意义(P<0.05),而在培养1 h和48 h时,两种糖培养基中ΔpH值的变化无统计学意义(P>0.05)。结论:在培养4～8 h内,HFCS利于变异链球菌代谢产酸,而在24～48 h内,蔗糖则显示出较强的持续产酸能力。     

牙菌斑中产酸菌和非产酸菌体外糖代谢实验研究

本实验对变链菌、粘放菌单独培养和变链菌加粘放菌韦荣氏菌混合培养这三组细菌在含糖培养基中产酸和pH值进行了分析。结果表明:变链菌和粘放菌产生大量乳酸是导致pH下降的主要因素,也是细菌致龋的主要有机酸;而韦荣氏菌与这些细菌之间存在食物链,可将乳酸分解为乙酸和丙酸等弱酸,从而使乳酸量显著减少,pH值有所回升。     

赤藓糖醇和木糖醇对变异链球菌生长和产酸作用的对比研究

目的对比相同浓度下赤藓糖醇和木糖醇对变异链球菌生长和产酸的影响。方法分别用含0.5%、1%、2%、4%、8%、12%、16%赤藓糖醇和木糖醇的TPY培养基在厌氧条件下培养变异链球菌,分别于0、2、4、6、8、10、12、18、24 h测量液体培养基的光密度值（A值）和pH值,运用SPSS描绘其变化曲线图。结果在0.5%、1%、2%浓度下,赤藓糖醇培养基的A值较木糖醇培养基高,pH值较木糖醇培养基低,说明变异链球菌在含0.5%、1%、2%赤藓糖醇的培养基内的生长和产酸能力明显较相同浓度木糖醇培养基高。在8%、12%、16%浓度下,赤藓糖醇培养基的A值较木糖醇培养基低,pH值较木糖醇培养基高,说明变异链球菌在含8%、12%、16%赤藓糖醇的培养基内的生长和产酸能力明显较相同浓度木糖醇培养基低。结论对比木糖醇,低浓度下赤藓糖醇对变异链球菌生长和产酸的抑制作用较弱,高浓度下赤藓糖醇的抑菌效果更强。     

咀嚼无糖口香糖对含漱蔗糖溶液后牙菌斑原位pH值的影响

目的 通过对牙菌斑原位pH值变化的动态监测，观察咀嚼无糖口香糖对牙菌斑原位pH值的影响。方法 采用受试者自身对照的临床试验方法，选择16名健康成人志愿者为受试者，年龄23～32岁，其中男性6名，女性10名。首先测定受试者48h菌斑的静止pH值，以及受试者用10％蔗糖溶液含漱1min后在5、10、20和30min时菌斑的pH值，取得受试者的Stephan曲线作为基线对照；而后观察咀嚼两种益达无糖口香糖对含漱10％蔗糖溶液后菌斑pH值变化的影响。菌斑原位pH值的测定采用pH微电极接触法在口内直接测量。结果 含漱10％蔗糖溶液后立即开始咀嚼无糖口香糖可使菌斑pH值在各检测时间点(含漱10％蔗糖溶液后5、10、20和30min)均维持在静止pH水平，无明显下降；含漱10％蔗糖溶液后在5min时开始咀嚼无糖口香糖则使菌斑pH值从含漱蔗糖溶液后5min时的5．59迅速回升至10min时的6．98。结论 受到蔗糖攻击后，咀嚼无糖口香糖可迅速缓冲菌斑的酸性产物，升高菌斑pH值。     

酪蛋白磷酸肽钙磷液对发酵乳杆菌产酸影响的实验研究

目的：研究酪蛋白磷酸肽钙磷液（CPP-ACP）对发酵乳杆菌产酸的影响，探讨CPP-ACP作为一种生物防龋制剂的可行性。方法：将发酵乳杆菌加入含不同浓度CPP-ACP的蔗糖培养基中，厌氧培养48h，用精密pH计检测培养基上清液的pH值，计算pH的变化值ApH（初始pH值一终末pH值）。结果：随着CPP-ACP液浓度的升高，培养基上清液的pH值升高，ApH降低，即发酵乳杆菌的产酸量降低。结论：CPP-ACP对发酵乳杆菌的产酸有一定抑制作用。     

中药白芨对变链菌产酸和黏附影响的实验研究

目的:研究白芨水煎剂(BSD)对变链菌的产酸和黏附是否具有抑制作用,初步探讨中药白芨防龋作用的机理.方法:利用液体稀释法测出MIC值,选取MIC值以下4个浓度梯度,分别加入含有变链菌的培养基中,用pH计测定培养前后上清液的△pH值,并用比浊法观察其对变链菌黏附的影响.结果:△pH值实验前后与对照组相比有显著性差异(P<0.05),白芨水煎剂对变链菌的黏附抑制率最高为66.67%.结论:白芨水煎剂具有抑制变链菌产酸和黏附的作用.     

New culture media for the isolation of Streptococcus mutans and Lactobacillus in the saliva of head- and neck-irradiated patients

The reduction in salivary flow in patients subjected to head and neck irradiation induces changes in the oral microflora and increases the risk of oral mucosal infections. The frequent presence of fungi, particularly Candida, in the oral environment of these patients complicates identification of the most important cariogenic bacteria with the commercial CRT Bacteria (Ivoclar Vivadent) culture media. Such identification is important for the application of chemical measures to control cariogenic bacteria in these patients, since it has been shown that simple fluoride application is unable to control caries in this population. OBJECTIVE: The aim of this study was to obtain a simple medium that inhibits Candida spp. growth and allows the specific growth of Streptococcus mutans and Lactobacillus spp. Thus, reliable counts of cariogenic species can be achieved. MATERIALS AND METHODS: Stimulated saliva samples from 30 head- and neck-radiotherapy patients were seeded in commercial CRT Bacteria culture medium and in two different media designed by our group: mitis salivarius bacitracin agar (MSBA), containing 5% potassium tellurite and fluconazole 64 microg/ml (MSBTPF) for the isolation of Streptococcus; and Man, Rogosa and Sharpe (MRS) agar, containing bacitracin 0.2 U/ml and fluconazole 32 microg/ml (MRSBF) for the isolation of Lactobacillus spp. RESULTS: Candida growth was inhibited 100% in the media developed in this study. In all the samples seeded, growing of colonies in MRSBF was identified as Lactobacillus, while in CRT Bacteria for Lactobacillus spp. this species was only isolated in 48.1% of the samples. S. mutans was identified in 71.4% of the colonies that grown in MSBTPF medium, while in CRT Bacteria for S. mutans, this species was only identified in 35% of the colonies obtained. CONCLUSION: The culture medium developed in the present study was able to inhibit the 100% of Candida spp. growth. These new media permit reliable counts of cariogenic bacteria in irradiated patients.     

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。     

Direct and immune-cell-mediated effects of Bacteroides gingivalis on bone metabolism in vitro

We investigated direct and immune-cell-mediated effects of Bacteroides gingivalis on bone metabolism in vitro. Fetal mouse long-bone rudiments were cultured under aerobic conditions in the presence of (a) intact bacteria, (b) low molecular weight (MW less than 1000) metabolic products of the bacteria, or (c) conditioned media of mouse spleen cells activated by whole bacteria. A suspension of intact bacteria, added directly to the bone culture, had no effect on bone resorption or bone formation. Low molecular weight (MW less than 1000) excretion products of the bacteria inhibited bone resorption and transiently reduced mineralization of the diaphysis, while the growth in length of the bones was not affected. However, conditioned media of bacteria-activated spleen cells strongly enhanced bone resorption and increased osteoclast numbers in the bone culture, while inhibiting mineral formation in the diaphysis. This led to a strongly negative mineral balance. These data do not support a direct effect of either bacteria or bacterial products on bone tissue as a likely explanation for bone loss in periodontal disease. Rather, they favour the concept that the loss of bone in this disease is an indirect effect of the host response, resulting from the contact of immune cells with the bacteria. This implies that bacterial invasion of the connective tissue of the gingiva may not be a prerequisite for alveolar bone loss.     

Comparison of five selective media for the growth and enumeration of Streptococcus mutans

BACKGROUND: Although a few growth media are available for selective isolation of the cariogenic bacteria, Streptococcus mutans (S. mutans), it is still unclear as to which is the most efficacious. This study compared the selectivity and sensitivity of five different media for growing a laboratory strain of S. mutans (NCTC 10449), and for enumerating S. mutans from teeth of a group of young children, aged 2-10 years. METHODS: The media tested in this study were mitis salivarius with bacitracin (MSB), mitis salivariuskanamycin-bacitracin (MSKB), glucose-sucrose-tellurite-bacitracin (GSTB), trypticase soy-sucrose-bacitracin (TYS20B) and tryptone-yeast-cysteine-sucrose-bacitracin (TYCSB) agars. These were prepared according to the respective manufacturer's instructions. RESULTS: The results showed that at concentrations of bacteria 1 x 10(3) to 1 x 10(10)/mL, the recovery of the laboratory S. mutans strain was highest in TYCSB agar, followed by in descending order by TYS20B, MSB, GSTB, and MSKB (p<0.01). Similar results were obtained using dental plaque samples collected from swabs of the teeth of a group of children. In the clinical samples, TYCSB again showed the highest recovery rates of S. mutans compared to the other four media. Results were reproduced at dilutions of the samples at 1:20 x 10(6) to 1:2 x 10(6), and S. mutans concentrations of 1.6 to 7.7 Log 10 CFU/mL. In addition, there were highest ratios of mutans to non-mutans bacteria in TYCSB compared to the other media, suggesting high selectivity of this media for mutans species. CONCLUSION: The results of our study suggest that TYCSB is the most sensitive and selective media for culture of S. mutans for laboratory and clinical studies.     

Colonization of the cleft nasal floor by anaerobic oral flora in patients with oronasal fistulae.

OBJECTIVES: Aerobic oral bacteria only rarely colonize the cleft nasal floor in patients with patent oronasal fistula. There are no studies that have investigated whether anaerobic oral flora colonize this site and whether attempting to culture them is useful for assessing the patency of oronasal fistulae in the clinic. DESIGN: A prospective study of 13 patients with cleft with patent unilateral oronasal fistulae. Microbiological culture swabs were taken from the oral cavity and both nasal floors, with the unaffected side being used as a control. Following aerobic and anaerobic culture, bacterial isolates were identified and compared. MAIN OUTCOME MEASURE: A significant growth of anaerobic oral bacteria from the cleft nasal floor when compared with the unaffected side. RESULTS: Aerobic oral flora was cultured from the oral cavity in all 13 patients. A light growth of aerobic oral flora was found in the cleft nasal floor in two patients, and anaerobic oral flora was cultured from the cleft nasal floor in the same two patients. No statistical correlation was found between growth of anaerobic flora and the cleft nasal floor (p =.48). CONCLUSIONS: Like aerobic oral flora, anaerobic oral bacteria would appear to only rarely colonize the cleft nasal floor in patients with oronasal fistulae. This additional investigation does not appear to be helpful in the assessment of oronasal fistulae in the clinic.     

Study of bacterial viability within human supragingival dental calculus

BACKGROUND: There is evidence that supragingival calculus contains unmineralized channels and lacunae. The purpose of this study was to investigate the viability of bacteria within these areas. METHODS: Supragingival calculus harvested from patients with moderate to severe chronic periodontitis was immediately frozen to -70 degrees C. Six samples were cryosectioned, stained with a bacterial viability kit, and examined with fluorescence microscopy. Controls comprised heat treatment of cryosections prior to staining. Four additional samples were stained and examined whole in a confocal laser scanning microscope (CLSM). Nine additional samples were prepared for bacterial culture, after initial irradiation with ultraviolet light to kill viable organisms on the covering plaque layer. Test samples were crushed to expose internal bacteria, while two controls were used without crushing. RESULTS: Viable bacteria, as identified using the bacterial viability stain, were found within cavities/lacunae in supragingival calculus cryosections. Similar results were obtained from whole calculus samples using CLSM. Of the nine experimental samples where bacterial culture was attempted, five provided positive bacterial culture under both aerobic and anaerobic conditions; one showed positive growth under aerobic conditions only; while one showed no bacterial growth. The controls showed no bacterial growth. CONCLUSIONS: From this study, it appears that viable aerobic and anaerobic bacteria may be present within supragingival calculus, specifically within the internal channels and lacunae. Clinically, this may be important, since incomplete removal of supragingival calculus may expose these reservoirs of possible pathogenic bacteria and be a factor in the recurrence of periodontal diseases after treatment.     

Osteogenesis in composite grafts of allogenic demineralized bone powder and porous hydroxylapatite

This study evaluated the osteoinductive capabilities of porous hydroxylapatite (PH) and the tissue response following intramuscular implantation of PH alone or in combination with demineralized bone powder (DBP). Six rhesus monkeys each received the implants in three separate soft tissue pockets created in the thoracic region. The implants consisted of 2 cc of either PH alone or DBP alone, or a 1:1 combination of DBP and PH. Two animals were killed at 2 weeks, two at 4 weeks, and two at 12 weeks postimplantation. Histologically, bone formation was seen in the DBP mixed with PH and in the DBP group as early as 4 weeks postimplantation; bone was also occasionally observed within the pores of the PH particles. The PH alone showed no evidence of formation of bone and the material was surrounded by a thick layer of fibrous tissue. It was concluded that PH is not osteoinductive, but can act as a scaffold for growth of bone, and that when mixed with an osteoinductive material, it allows for formation of bone within the implant.     

常见致龋菌代谢组学鉴定的初步研究

目的初步将基于核磁共振的代谢组学方法应用于口腔致龋菌的鉴定,期望寻找一种能快速鉴定口腔致龋菌的方法。方法在改良TPY培养基中接种变形链球菌及粘性放线菌,用比浊法绘制生长曲线,选择两种细菌生长后4个时期的培养液检测核磁共振波谱,用主成分分析法进行数据分析。结果主成分分析显示两组数据内部有集中的聚类关系,可以区分两种细菌。结论代谢组学技术有望应用于口腔细菌的快速鉴定。     

髓石中Nanobacteria细菌的分离、培养与鉴定

目的 从髓石中分离Nanobacteria，并进行培养和鉴定。方法 收集新鲜的27颗髓石分为9个样本，每个样本含3颗髓石，进行Nanobacteria的分离、培养，观察该菌形态学及生长特性，采用VOBKossa染色、Nanobacteria单克隆抗体8D10和G188免疫组化和间接免疫荧光染色、Hoechst染色和VOBKossa染色双重染色法联合进行Nanobacteria鉴定。结果 本次实验7个样本中所分离、培养出的细菌形态学特征与生长特性与Nanobacteria相似，VOBKossa染色呈阳性反应，单克隆抗体免疫组化染色和间接免疫荧光染色阳性。双重染色实验中，样本Hoechst染色呈阴性反应，VOBKossa染色呈阳性反应，而牙髓细胞的Hoechst染色可见胞核呈明显阳性反应，有2个样本中未见细菌生长。结论 髓石中可分离得到Nanobacteria，该菌的生物学特性可能在髓石的形成中起重要作用。     

黄芪浸出液对致龋菌的体外抑菌实验

选择甘肃产黄芪为原料,制成水浸出液,研究其对口腔常见致龋菌的抑制效果,并与国外致龋菌抑菌产品(MI)进行比较.以变形链球菌、乳酸杆菌为实验菌株,用选择性培养基进行液体培养,在培养基中添加不等量的药物,测培养24 h后菌液的A值、pH值;用SPSS 13.0对数据进行统计分析.黄芪浸出液对变形链球菌、乳酸杆菌的生长、产酸均有抑制效果,抗菌效果与MI相当.