spx蛋白调控作用的研究进展

变异链球菌是人类龋病的主要致龋菌,在口腔内感受各种应激条件的变化,其致病性与其在各种应激环境中的耐受情况密切相关。spx蛋白是一种革兰阳性细菌全局性调节因子,在变异链球菌的应激耐受、生存和致龋过程中起着重要的作用。本文就spx蛋白及spx／tx—C末端结构域复合体结构、非致龋菌的spx蛋白及其调控功能、变异链球菌spx蛋白及其调控作用等研究进展作一综述。     

口腔龋坏组织中变异链球菌与乳酸杆菌的作用研究

目的分析人龋坏组织中变异链球菌与乳酸杆菌在不同分组中的培养计数及不同细菌主导的病例数,研究变异链球菌和乳酸杆菌在致龋过程中的协同作用。方法选取甘肃省靖煤公司总医院口腔科110例龋病患者,按照不同龋坏程度、不同年龄、不同龋坏性质分组采集龋坏组织,在选择培养基上培养,计数菌落数量。统计2种细菌在不同分组中的检出率、细菌计数平均数及不同致龋菌病例数,研究二者的致龋作用。结果变异链球菌和乳酸杆菌的细菌计数平均数随着龋坏程度增加而增高（P<0.05）,在老年组患者中变异链球菌和乳酸杆菌数量增高（P<0.05）,在龋病活动期增高（P<0.05）。随着龋坏程度的增加,变异链球菌和乳酸杆菌共同致龋病例数增高（P<0.05）,在老年人龋坏中共同致龋病例数增高（P<0.05）,变异链球菌和乳酸杆菌共同致龋作用与龋病的静止与活动无相关性。结论变异链球菌和乳酸杆菌随着龋坏程度的增加,共同致龋作用增强;老年人龋齿中,二者的协同作用占主导作用;在龋病活动期与静止期中,变异链球菌和乳酸杆菌仅存在数量上的区别,二者的单独致龋能力均在活动期增强,但共同致龋作用与龋病的活动与静止无关联。     

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。     

变形链球菌与血链球菌的质子移位膜ATP酶的研究概况

口腔变形链球菌是龋病的主要致病菌,血链球菌为牙周有益菌。口腔致龋菌的致龋能力主要是其产酸性和耐酸性,而ATP酶是耐酸性的决定因素,是变形链球菌等致龋菌的固有毒力因子。本文以大肠杆菌为参照,对变形链球菌和血链球菌ATP酶的基因结构进行比较,探讨口腔致龋菌的质子移位膜ATP酶的结构特性。     

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。     

酪蛋白裂解酶P对变异链球菌致龋性的影响

变异链球菌是人类龋病的主要致病菌,不仅在数量上优势明显,而且其产酸和耐酸能力较强,其生物膜黏附于牙表面是其毒性致龋的首要步骤。酪蛋白裂解酶P（ClpP）是细菌体内一种介导蛋白质水解的热休克蛋白,可清除细菌体内的变性蛋白质,影响细菌的生物膜形成并且在细菌对生存环境的诸多应激反应中发挥着一定的作用。本文就ClpP,变异链球菌ClpP,其他致病微生物的ClpP等研究进展作一综述。     

变异链球菌葡聚糖结合蛋白B的生物学特性研究进展

变异链球菌是人类龋病的主要致病菌,葡聚糖结合蛋白是其重要的毒力因子之一.葡聚糖结合蛋白B在变异链球菌的致龋、维持细菌形态、发挥细胞壁生理功能等方面有重要作用,同时其N端具有免疫原性,可应用于免疫防龋.下面就葡聚糖结合蛋白B的生物学特性研究进展作一综述.     

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。     

白色念珠菌与龋病相关性的研究进展

白色念珠菌是口腔中重要的机会致病真菌。近年来,研究发现它能与口腔常见致龋菌变异链球菌发生相互作用,对维持口腔正常的微生态平衡具有重要作用;同时白色念珠菌自身具有黏附、产酸、耐酸等作用,能使牙体硬组织脱矿,并能产生胶原蛋白酶降解牙体硬组织的有机质,具有致龋潜能。本文从白色念珠菌在患龋人群中的检出率、致龋潜力、与变异链球菌的交互作用、与其他口腔细菌的交互作用4个方面进行综述,以期拓展对口腔微生物在龋病中作用的认识,为龋病的临床防治提供新思路。     

变异链球菌葡萄糖基转移酶转录调控因子的研究进展

葡萄糖基转移酶是变异链球菌自身合成的一种重要的固有酶,是变异链球菌重要的致龋因子,它以蔗糖作为代谢底物,合成生物膜重要的胞外多糖葡聚糖,葡聚糖一方面介导细菌蔗糖依赖的生物膜形成,另一方面当外源性糖源缺乏时,被降解供细菌继续代谢。因此可以通过控制葡萄糖基转移酶而控制龋病的发生发展。本文就变异链球菌葡萄糖基转移酶基因转录的调控因子作一综述。     

Antibody responses to mutans streptococci in children.

Because mutans streptococci (Streptococcus mutans, S. sobrinus) are considered the main causative bacteria in human dental caries, immune responses to these bacteria have aroused much research interest over the last two decades. Studies in man have focused mainly on salivary and serum antibodies developing naturally in response to oral colonization by mutans streptococci, or in relation to the development of dental caries. Although both salivary (IgA) and serum-derived (IgG) antibodies have been shown in many studies to protect against the adherence of and to interfere with the metabolism of mutans streptococci, no conclusive evidence relating to their clinical significance is available. In young children, serum IgG antibodies to S. mutans seem more important than salivary IgA antibodies in relation to protection against dental caries. In studies in animals and, recently, in man, monoclonal IgG antibodies to S. mutans protein antigen I/II ("adhesin") have provided effective protection against mutans streptococci. Whether they could also prevent dental caries in man is not yet known.     

The association of bacterial adhesion with dental caries.

Saliva adhesion of bacteria is a key event in oral biofilm formation. Here, we used partial least-squares (PLS) analysis to correlate adhesion of cariogenic (Streptococcus mutans Ingbritt) and commensal (Actinomyces naeslundii LY7) model bacteria, and their agglutinin and acidic proline-rich protein ligands, respectively, with high and low caries experiences in 38 children reflecting today's skewed caries distribution. Adhesion of S. mutans was among the factors correlating strongest with high caries experience when PLS modeled together with traditional factors (e.g., sugar intake, lactobacilli counts). Saliva phenotypes with high agglutinin levels and Db-s (an acidic PRP variant) coincided with both high caries experience and S. mutans adhesion. A. naeslundii adhesion correlated with low caries experience. Non-Db phenotypes (i.e., acidic PRP-1 and PRP-2 variants) coincided with both low caries experience and S. mutans, but high A. naeslundii, adhesion. Thus, bacterial adhesion may modulate susceptibility and resistance to dental caries.     

高温需要A蛋白与口腔变异链球菌的致龋性

变异链球菌是龋齿的主要致病菌,细菌表面多糖合成物、对牙面的黏附聚集、生物膜形成是其重要的生理学致病因子.高温需要(Htr)A是一种细菌细胞质的热休克蛋白,对于细菌耐受环境变化,特别是温度的增高,pH值和氧化还原电势的变化有重要的意义.下面就HtrA与变异链球菌致病因子相关的研究进行综述.     

Hydrophobicity test in mutans streptococci

Kinetic hydrophobic measurements were performed by confronting 40 mutans streptococci from thirty 10- to 20-year-old patients with 200 ml hexadecane (Sigma). Fourteen patients had high dental caries risk (Group A), dmft + DMFT > 5 with 3 or more active caries, and 16 had low dental caries risk (Group B), dmft + DMFT < 3 without active caries. Twenty bacteria from Group A and 20 bacteria from Group B were typed using De La Higuera's procedure and confirmed by API strip (bio-Merieux). From the 14 patients in Group A we obtained 12 S. mutans (8 hydrophobic/4 non-hydrophobic), 5 S. sobrinus (4 hydrophobic/1 non-hydrophobic) and 3 S. rattus (hydrophobic). From the 16 patients in Group B we obtained 11 Streptococcus mutans (10 non-hydrophobic/1 hydrophobic), 7 Streptococcus sobrinus (6 non-hydrophobic/ 1 hydrophobic) and 2 Streptococcus rattus (hydrophobic). Patients with high dental caries risk have a higher prevalence of hydrophobic bacteria than patients with low dental caries risk (p = 0.0003). All typed S. rattus were hydrophobic.     

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。     

表兄链球菌的检测与儿童猛性龋的关系

目的：探讨表兄链球菌(Streptococcus sobrinus,S. sobrinus)与儿童猛性龋的关系。方法：根据前期郑州市区猛性龋调查结果,随机抽样选择3～5岁儿童66例,其中猛性龋、普通高龋及无龋组各22例。采用TYCSB培养基作变形链球菌(Streptococcus mutans, S. mutans )及S. sobrinus初步筛选,结合生理生化鉴定,并采用聚合酶链反应作最终鉴定。采用 SPSS10.0软件包对实验组与对照组S.mutans和S.sobrinus的检出率进行χ²检验,组间均数作t检验。结果： S. sobrinus在各组儿童牙菌斑中均不能脱离S. mutans而单独检出,猛性龋组S. mutans检出率高于高龋组,差异无显著性(P>0.05),而2组儿童S. sobrinus检出率的差异有显著性(P<0.05);猛性龋组与无龋组S. mutans检出率差异显著(P<0.05),S. sobrinus检出率差异显著(P< 0.01)。同时检出S. mutans和S. sobrinus的样本,其猛性龋的发生率及龋失补牙数、龋失补牙面数和平滑面龋均数与只能检出S. mutans及2种细菌均不能检出的样本的差异有显著性(P< 0.01)。结论：S. mutans与S. sobrinus是儿童猛性龋的主要致病菌,S. sobrinus与儿童猛性龋的发生有关。S. sobrinus对儿童猛性龋的发生、发展具有协同作用。     

Quantitative determination of Streptococcus mutans by using competitive polymerase chain reaction

Mutans streptococci are among the range of pathogens strongly related to human dental caries. The determination of total amounts of these pathogens as well as their proportion in relation to other oral bacteria is of interest for the assessment of the risk that a patient runs of developing dental caries. This paper presents a competitive polymerase chain reaction (PCR) method for the specific quantitative determination of Streptococcus mutans which uses a homologous DNA for internal standardisation. For quantification of these bacteria, calibration curves were obtained by coamplification of known amounts of S. mutans DNA in the presence of different known amounts of the competitor DNA. The same procedure was performed with known amounts of cultured S. mutans cells. In a clinical study, the reliability of the newly developed quantitative PCR method was assessed by comparing its results with those obtained in parallel with a standard chair side culture method. The described method enables a rapid and exact determination of unknown amounts of S. mutans and could provide an efficient tool for evaluating the caries risk in a patient and to monitor the efficiency of preventive and therapeutic measures.