变异链球菌耐酸毒力因子质子移位膜ATP酶在龋病进展中的动态变化

目的 研究变异链球菌耐酸毒力因子质子移位膜ATP酶（F-ATPase）在不同pH环境和龋病发生发展过程中的表达,评价F-ATPase在龋病进展中的动态变化。方法 将变异链球菌菌悬液在不同pH（pH4.0~7.0）和不同葡萄糖浓度（含5%和不含葡萄糖）的BHI液体培养基中培养,检测F-ATPase基因的表达水平。将雄性Wistar大鼠随机分成致龋组和对照组,其中致龋组喂养致龋饲料及5%葡萄糖水,对照组喂养普通饲料。每2周采集菌斑样本,检测F-ATPase基因的表达水平。第11周时取大鼠上下颌骨标本,对磨牙进行龋损评定。结果1）5%葡萄糖浓度下变异链球菌F-ATPase基因的表达高于不含葡萄糖（P<0.05）,在pH5.0时F-ATPase基因的表达最高,pH4.0时表达最低（P<0.05）。2）成功构建了龋病动物模型,在龋病发生发展过程中,致龋组和对照组F-ATPase的表达逐渐增强,致龋组表达高于对照组（P<0.05）。结论 耐酸毒力因子F-ATPase的表达变化与龋病的发生发展密切相关。     

乳酸杆菌与变异链球菌在龋病中相互关系的研究进展

变异链球菌是目前公认的致龋细菌,与龋病的发生发展密切相关,对其毒力因子和致龋机制的研究已经比较深入。乳酸杆菌是口腔内常居菌群,其在龋病中所起作用存在一些争议。而且这两种细菌在龋病中的相互作用关系尚未明确。本文对其在龋病中的作用和关系以及可能的作用机制作一综述。     

靶向变异链球菌谷氨酸消旋酶的研究进展

变异链球菌是龋病发生的始动因子,与人类龋病密切相关。抑制变异链球菌致龋毒力相关的基因和酶,可影响细菌毒力因子的产生,降低细菌的致龋能力,有助于龋病的预防和治疗。谷氨酸消旋酶是一类不需辅助因子,专一催化L型和D型谷氨酸之间相互转化的酶,为细胞壁肽聚糖合成提供D-谷氨酸,是细菌生长的关键酶,目前已经成为研究和开发新型抗菌药物的新靶标。特异性靶向变异链球菌谷氨酸消旋酶,有望为龋病防治提供新的思路和方法。本文对谷氨酸消旋酶的分类、结构特征、酶抑制剂及基因遗传学等研究进展进行系统阐述,为进一步研究谷氨酸消旋酶与变异链球菌致龋毒力的关系,研发抗龋药物候选靶标提供理论基础。     

不同龋敏感儿童菌斑中变异链球菌数量及菌群比例的定量分析

目的 比较不同龋敏感儿童口腔菌斑中变异链球菌数量及其在菌群中比例的差异。方法 采集26名3~4岁不同龋敏感的儿童牙面菌斑,运用TaqMan探针实时荧光定量聚合酶链反应（PCR）检测有龋组和无龋组儿童菌斑中变异链球菌和总菌数量,以及变异链球菌在总菌群中所占的比例,并对结果进行分析比较。结果 有龋组和无龋组儿童每毫克菌斑中变异链球菌菌落数分别为1.33×105、1.16×103 CFU·mg-1,二者间差异有统计学意义（P=0.033）;每毫克干重菌斑中总菌落数分别为7.17×107、1.01×108 CFU·mg-1,二者间差异无统计学意义（P=0.418）;有龋组和无龋组变异链球菌在总菌中所占比例分别为0.058 6和0.018 6,二者间差异有统计学意义（P=0.008）。结论 无龋与患龋儿童牙面总菌群数量差异无显著性,但患龋儿童牙面菌斑中变异链球菌数量更多,在总菌群中所占比例更大。提示菌斑中变异链球菌与总菌的比例与儿童患龋风险密切相关,可以作为评估龋易感性和预测龋病发展趋势的新指标。     

口腔致龋生物膜中白色念珠菌与变异链球菌交互作用机制研究进展

变异链球菌是公认的牙菌斑生物膜主要致龋菌。龋病患者口腔检出白色念珠菌等真菌,尤其是平滑面龋、根面龋以及低龄儿童龋等。文献报道在菌斑生物膜形成过程中,白色念珠菌与变异链球菌之间具有一定的协同和拮抗作用,认为白色念珠菌通过上调葡糖基转移酶（glucosyltransferase,GTF）等多种表面蛋白和多糖,调控糖代谢从而影响变异链球菌的定植、增殖、生存与代谢产酸,增强其成膜致龋能力,而同时变异链球菌影响白色念珠菌的生存、致龋毒力、共聚集和黏附力。二者的相互作用是成膜致龋的重要推动因素,但可能存在时间或环境依赖性,值得深入探讨研究。     

Hsp100/Clp ATPase对变异链球菌毒力表达的调控及机制的研究进展

变异链球菌是龋病的始动因子,依赖其产酸、耐酸及形成生物膜等能力成为了口腔致龋环境中的优势菌。三磷酸腺苷（ATP）依赖的内肽酶Clp（Clp ATPase）属于热休克蛋白100家族（Hsp100）成员,通过调控基因表达和控制关键蛋白的活性影响细菌的多种生物学性能。Hsp100/Clp ATPase中某些成员可结合ATP依赖的丝氨酸蛋白水解酶ClpP形成功能复合体,活化、重组和降解变性蛋白质,维持细菌的蛋白质稳态,辅助细菌抵抗严苛的口腔环境。特异性靶向变异链球菌Hsp100/Clp ATPase有望为龋病防治提供新的思路和方法。本文就Hsp100/Clp ATPase的结构和分类,对变异链球菌基因、蛋白及生物学行为调控,及Hsp100/Clp ATPase靶向药物作用等研究进展进行系统阐述,为进一步分析Hsp100/Clp ATPase与变异链球菌致龋毒力的关系,研发抗龋药物候选靶标奠定基础。     

菌斑在龋齿发病中的作用

牙菌斑是引起人类两大口腔疾病———龋病和牙周病的始动因子。多年来 ,对牙菌斑的形态结构、生化代谢以及牙菌斑的致病性有关问题有大量的研究 ,本文就菌斑在龋病中的发病作用作一综述。1 菌斑的细菌学牙菌斑是口腔细菌的微生态环境 ,微生物在这种环境中进行复杂的代谢活动 ,伴随着这些细菌活动 ,牙齿发生龋坏。菌斑内细菌种类和含量不同 ,决定了它们致龋能力的差异[1] 。现公认的主要致龋菌为变形链球菌。近年来 ,远缘链球菌 (又称茸毛链球菌 )的致龋性受到重视 ,它可能具有更强的致龋潜力 ,对龋病的发生和活跃性可能更为重要。动物实验[2…     

不同龋敏感儿童口腔变异链球菌不同基因型临床分离株产酸力的实验研究

目的比较不同龋敏感儿童口腔变异链球菌不同基因型临床分离株对蔗糖进行酵解产生有机酸的能力。方法从不同龋敏感的3~5岁学龄前儿童口腔变异链球菌中选取66株变异链球菌临床分离株,用气相色谱法测定高龋、中龋和无龋儿童口腔变异链球菌不同基因型临床分离株产生各有机酸的量。结果不同龋敏感儿童不同基因型变异链球菌临床分离株产生有机酸的量的差异有统计学意义（P<0.05）,同一龋敏感儿童变异链球菌携带不同基因型菌株产酸量的差异也有统计学意义（P<0.05）,携带基因型数目越多的菌株其产酸量越多。变异链球菌临床分离株产生乳酸、乙酸、甲酸的量的差异有统计学意义（P<0.05）,乳酸多于乙酸和甲酸。结论不同龋敏感儿童口腔变异链球菌不同基因型菌株产酸力不同,携带基因型数目越多的菌株其产酸力越强。     

致龋菌、唾液缓冲能力与婴幼儿龋的相关性研究

目的探讨唾液中变形链球菌、乳酸杆菌和唾液pH值、缓冲能力与婴幼儿龋的关系。方法将178名42～54个月的儿童分为患龋组（患龋牙数≥5）87例和无龋组91人。吐唾法采集非刺激性唾液和嚼蜡法采集刺激性唾液各2ml，用选择性培养的方法检测刺激性唾液中变形链球菌、乳酸杆菌的检出率和计数水平；测定非刺激性及刺激性唾液的pH值和缓冲能力。结果患龋组唾液变形链球菌和乳酸杆菌的检出率分别为96．6％和79．3％，显著高于无龋组的63．7％和27．5％（P〈0．05）；患龋组两种细菌的计数水平比无龋组高近10倍。患龋组和无龋组刺激性唾液的初始pH值和对酸的缓冲能力均显著高于非刺激性唾液（P〈0．001）；患龋组刺激性和非刺激性唾液的初始pH值和缓冲能力均显著低于无龋组（P〈0．05）；无龋组中变形链球菌、乳酸杆菌和唾液pH值、缓冲能力之间无明显的相关性；患龋组刺激性唾液的缓冲能力与变形链球菌的计数水平显著相关（r=0．249，P〈0．05）。结论变形链球菌和乳酸杆菌是婴幼儿龋的重要致病菌；唾液的初始pH值和缓冲能力偏低可能是影响婴幼儿龋的重要因素。     

壳聚糖/姜黄素纳米复合物对变异链球菌致龋力的影响

目的:探讨壳聚糖/姜黄素纳米复合物对变异链球菌致龋力的影响。方法:将姜黄素与壳聚糖复合后形成含有不同浓度(0、0.01、0.05、0.10 mmol/L)姜黄素的壳聚糖/姜黄素纳米复合物(CS-Cur)。将CS-Cur作用于浮游态及生物膜状态下的变异链球菌,观察变异链球菌生长增殖曲线、培养物pH变化、细菌糖酵解能力,结晶紫染色评估变异链球菌生物膜的量,蒽酮法检测生物膜内非水溶性胞外多糖含量,菌落计数评估生物膜中所含细菌的量。通过以上实验评估变异链球菌在CS-Cur作用后致龋因子表达的变化。结果:CS-Cur作用于变异链球菌后,其生长增殖受到了抑制,该抑制随着Cur浓度升高而增强;变异链球菌培养物pH也无法下降至空白对照组水平;同时变异链球菌的糖酵解能力在CS-Cur作用后也有所下降;CS-Cur作用于变异链球菌后,结晶紫染色结果显示：变异链球菌所形成的生物膜的量下降(P<0.05);蒽酮检测胞外多糖结果显示：生物膜中所含的非水溶性胞外多糖显著减少(P<0.05);菌落计数结果显示：细菌数量也显著减少(P<0.05)。结论:CS-Cur纳米复合物对变异链球菌致龋因子的表...     

Nitric oxide modulates levels of salivary Lactobacilli

Abstract

Objective. Nitric Oxide (NO) is one of the most powerful antibacterial compounds. The aim of this study was to determine the association between salivary NO, dental caries and cariogenic bacteria. Materials and methods. The salivary NO concentration of 257 Korean children was analyzed by the Griess colorimetric reaction method. Salivary mutans streptococci (MS) and Lactobacilli (LB) were counted using the Dentocult MS and Dentocult LB kit, respectively. Dental caries status was examined using the WHO criteria. Confounders were age, gender, salivary flow rate and salivary buffer capacity. Analysis of covariance (ANCOVA) was used to evaluate the association among NO, salivary MS level, salivary LB level and dental caries status after adjusting for the effects of confounders. Results. A significant decrease was found in salivary NO levels as the salivary LB count increased after controlling for confounders (p = 0.049). However, the MS level, caries experience and active caries status showed no significant association. Conclusion. This result indicates that NO production might be a host defense mechanism against the growth of cariogenic bacteria.     

不同龋敏感儿童牙菌斑中4种致龋菌的动态监测分析

目的:监测无龋儿童组（caries free,CF）、低龄儿童龋组（early childhood caries,ECC）和重度低龄儿童龋组 (severe early childhood caries,S-ECC)牙菌斑中4种致龋菌的动态变化。方法:选取60名3~5岁儿童,对其进行龋病检查和牙菌斑样本收集,追踪观察1 a。采用实时荧光定量PCR技术对2次取样的4种致龋菌（变形链球菌、远缘链球菌、嗜酸乳杆菌和内氏放线菌）进行定量检测,计算各致龋菌所占总菌的比例。采用SPSS17.0软件包对实验数据进行χ²检验和配对t检验。结果:在基线及1 a后患龋率分别为66.7%和81.7%,差异无显著性（χ²=1.76,P>0.01）;龋失补牙面数分别为（5.80±2.53）和（7.90±1.76）,差异显著（t=3.51,P<0.01）。ECC、S-ECC组中,4种致龋菌所占比例在基线和1 a后有显著差异（P<0.01）。1 a后ECC、S-ECC组中变形链球菌、远缘链球菌之和所占比例显著高于基线水平（P<0.01）。变异链球菌与远缘链球菌之和所占总菌的比例与dmfs指数的变化在基线和1 a后均具有良好的线性关系。结论:菌斑中致龋菌的比例变化与低龄儿童龋密切相关,致龋菌所占总菌的比例越高,低龄儿童龋易感性就越高。     

Caries vaccines for the twenty-first century

Can infection with the dental caries pathogen, Streptococcus mutans, be intercepted or modified immunologically? Resolving this question requires answers to many questions: What are the pathways by which this cariogenic streptococcus enters and accumulates in the dental biofilm? Can bacterial components associated with virulence induce immune responses? What is the level of maturity of immune pathways in the oral cavity of the young child at the time of infection? Can immune strategies deal effectively with chronic S. mutans infections? Are these vaccines safe? Many such questions have been answered. For example, preclinical application of modern methods of mucosal vaccine design and delivery has routinely resulted in protection from dental caries caused by S. mutans infection, using antigens involved in the sucrose-independent or sucrose-dependent mechanisms of infection by these cariogenic streptococci. Passive administration of antibody to functional epitopes of S. mutans virulence antigens has also provided a degree of protection in preclinical studies and small-scale human investigations. The caries-protective capacity of active immunization with dental caries vaccines now awaits proof of principle in pediatric clinical trials.     

Virulence properties of cariogenic bacteria

The importance of Streptococcus mutans in the etiology of dental caries has been well documented. However, there is growing recognition that the cariogenic potential of dental plaque may be determined by the composite interactions of the total plaque bacteria rather than solely the virulence properties of a single organism. This study will examine how the interactions of S. mutans with other biofilm constituents may influence the cariogenicity of plaque samples. In order to begin to investigate the effects of nonmutans streptococci on the cariogenic potential of S. mutans, we have examined the effects of Streptococcus gordonii on the virulence properties of the former organisms. These studies have indicated that S.gordonii can attenuate several potential virulence properties of S. mutans including bacteriocin production, genetic transformation, and biofilm formation. Therefore, modulation of the interactions between plaque bacteria might be a novel approach for attenuating dental caries initiation.     

乳酸杆菌在儿童龋病中作用的研究进展

乳酸杆菌（LB）是一种产酸、耐酸性细菌,能高效代谢糖类产酸,使牙体组织脱矿,LB是龋病的主要致病菌,在龋病的发病中起到至关重要的作用,与龋病的发展密切相关,而儿童龋病又有其特点。本文对国内外儿童（年龄<12岁）龋病的流行病学、龋病的菌群分布、致病LB基因型及其与其他致病菌的相互作用在龋病发病中的作用等方面的研究进展作一综述。     

Salivary IgA to cariogenic bacteria in HIV-positive children and its correlation with caries prevalence and levels of cariogenic microorganisms

The interrelationship of HIV infection, dental caries and mucosal immune responses remains controversial. In our study population of 40 HIV-infected and 40 healthy control children (ages 2-5 years) there was a significantly higher prevalence of dental caries in HIV-infected children (P<0.05). The extent of caries correlated with the severity of HIV disease. To determine whether the immunosuppression that ensues after HIV infection could contribute to the increased caries prevalence, the concentrations of total IgA and IgA specific to cariogenic bacteria (Streptococcus mutans, Streptococcus sobrinus and Lactobacillus acidophilus) were determined in whole saliva by enzyme-linked immunosorbent assay. Levels of the same bacteria were also quantified in saliva using checkerboard DNA-DNA hybridization. A significantly increased level of total salivary IgA was found in the HIV-positive population (P < 0.05), but there were comparable titers of specific IgA to cariogenic bacteria in HIV-positive and healthy controls. The microbiological assessment also demonstrated similar levels of cariogenic microorganisms in both groups. We conclude that HIV-positive children appear to maintain the capacity to mount a mucosal immune response to cariogenic microorganisms, at least until late stages of disease.     

母子口腔中变形链球菌基因型的对照研究

目的：分析高龋、无龋儿童及其母亲口腔中变形链球菌（S．mutans）菌株的基因型，探讨S．mutans基因型与致龋活性的关系。方法：试剂盒法提取细菌染色体DNA，对20名儿童（高龋组10名，无龋组10名）及其母亲的共800株S．mutans临床分离株进行AP—PCR基因型分析。结果：高龋儿童携带的S．mutans基因型数目多于无龋儿童（P〈0．05），高龋儿童的母亲携带的S．mutans基因型数目显著多于无龋儿童的母亲（P〈0．01），高龋儿童母亲的DMFT值显著高于无龋儿童母亲（P〈0．01），高龋组和无龋组的共有基因型数目无统计学差异（P〉0．05）。结论：高龋个体比无龋个体携带更多的S．mutans基因型，个体携带的S．mutnm基因型数目与其致龋活性有关。     

根面龋细菌学初步分析

目的 :通过对根面龋菌斑微生物的定量分析 ,进一步了解根面龋的致龋机制。方法 :19例根面龋患者 ,根据临床表现分为活动性和非活动性龋 ,对其根面龋的菌斑微生物进行菌落计数。结果 :无论活动性还是非活动性根面龋 ,厌氧菌都有较高的检出率 ,活动性根面龋检出率更高 ,活动性根面龋中链球菌总菌、变链菌、放线菌和乳杆菌检查率稍高 ,在非活动性根面龋中韦永氏菌和新月单胞菌的检出率稍高。梭杆菌及类杆菌 (包括紫质单胞菌、普氏菌、脆弱类杆菌 )检出率二者相似。活动性根面龋的各菌菌落计数均多于非活动性根面龋 ,差别最明显的是变形链球菌和放线菌。结论 :变形链球菌 ,放线菌是根面龋由非活动性到活动性转变的优势菌     

A comparative study of Streptococcus mutans and lactobacilli in mothers and children with severe early childhood caries (SECC) versus a caries free group of children and their corresponding mothers

Early childhood caries (ECC) is recognized as an infectious disease. The first step in its development is primary infection by the bacterium S. mutans which has been identified as the primary etiologic factors in dental caries. Lactobacilli were also found to play a role in the progression of the disease. However, the underlying mechanism of immune response to caries is still unclear. The purpose of this study was to assess the level of cariogenic bacteria namely S. mutans and lactobacilli in caries free children, and children with SECC and their corresponding mothers. he study also aims at correlating the children's levels to their mothers. Sixty children and their mothers attending the dental clinic in King Abdulaziz University participated in our study. Their age ranged from 3 - 5 years. The study groups consisted of 30 children with SECC and a control group comprising of 30 caries free children. Children together with their mothers were examined and their caries level was recorded. Stimulated saliva was collected from each participant for bacterial, immunological assessment, and Lactobacilli counts in each sample were determined Children with SECC had higher levels of S. mutans and Lactobacilli than caries free children. The mothers of children with SECC had a statistically higher count of Lactobacilli than caries free children's mothers. However, the difference was not statistically significant with respect to their S. mutans counts. A significant relationship exists among the mother-child pair in the SECC group with respect to S. mutans level in saliva.     

Salivary IgA to cariogenic bacteria in HIV‐positive children and its correlation with caries prevalence and levels of cariogenic microorganisms

The interrelationship of HIV infection, dental caries and mucosal immune responses remains controversial. In our study population of 40 HIV‐infected and 40 healthy control children (ages 2–5 years) there was a significantly higher prevalence of dental caries in HIV‐infected children (P<0.05). The extent of caries correlated with the severity of HIV disease. To determine whether the immunosuppression that ensues after HIV infection could contribute to the increased caries prevalence, the concentrations of total IgA and IgA specific to cariogenic bacteria (Streptococcus mutans, Streptococcus sobrinus and Lactobacillus acidophilus) were determined in whole saliva by enzyme‐linked immunosorbent assay . Levels of the same bacteria were also quantified in saliva using checkerboard DNA–DNA hybridization. A significantly increased level of total salivary IgA was found in the HIV‐positive population (P < 0.05), but there were comparable titers of specific IgA to cariogenic bacteria in HIV‐positive and healthy controls. The microbiological assessment also demonstrated similar levels of cariogenic microorganisms in both groups. We conclude that HIV‐positive children appear to maintain the capacity to mount a mucosal immune response to cariogenic microorganisms, at least until late stages of disease.