Relationship of periodontal clinical parameters with bacterial composition in human dental plaque

More than 600 bacterial species have been identified in the oral cavity, but only a limited number of species show a strong association with periodontitis. The purpose of the present study was to provide a comprehensive outline of the microbiota in dental plaque related to periodontal status. Dental plaque from 90 subjects was sampled, and the subjects were clustered based on bacterial composition using the terminal restriction fragment length polymorphism of 16S rRNA genes. Here, we evaluated (1) periodontal clinical parameters between clusters; (2) the correlation of subgingival bacterial composition with supragingival bacterial composition; and (3) the association between bacterial interspecies in dental plaque using a graphical Gaussian model. Cluster 1 (C1) having high prevalence of pathogenic bacteria in subgingival plaque showed increasing values of the parameters. The values of the parameters in Cluster 2a (C2a) having high prevalence of non-pathogenic bacteria were markedly lower than those in C1. A cluster having low prevalence of non-pathogenic bacteria in supragingival plaque showed increasing values of the parameters. The bacterial patterns between subgingival plaque and supragingival plaque were significantly correlated. Chief pathogens, such as Porphyromonas gingivalis, formed a network with other pathogenic species in C1, whereas a network of non-pathogenic species, such as Rothia sp. and Lautropia sp., tended to compete with a network of pathogenic species in C2a. Periodontal status relates to non-pathogenic species as well as to pathogenic species, suggesting that the bacterial interspecies connection affects dental plaque virulence.     

Comparison of bacterial composition between human saliva and dental unit water system

The bacterial compositions between the dental unit water system and human saliva were characterized and compared by direct sequence analysis of 16S rDNA clone libraries. Based on the species richness estimation, bacterial diversity in the dental unit water system (DUW) was more diverse than that of the human saliva (HS). The Chao1 estimates of species richness in HS and DUW samples were 12.0 and 72.4, respectively. The total numbers of OTUs observed in the combined libraries accounted for 83% (HS) and 59% (DUW) of the Chao1 diversity estimate as defined at the 80% similarity threshold. Based on the sequence analysis, the phylum Proteobacteria was the major group in both clone libraries at phylum level. DUW clone library contained 80.0% Proteobacteria, 8.0% Bacteroides, 4.0% Nitrospira, 4.0% Firmicutes, 2.0% Planctomycetes and 2.0% Acidobacteria. On the other hand, human saliva (HS) clone library contained 55.5% Proteobacteria, 36.1% Firmicutes and 8.4% Bacteroides. The majority of bacteria identified belonged to phylum Proteobacteria in both samples. In dental unit water system (DUW), Alphaproteobacteria was detected as the major group. There was no evidence of the bacterial contamination due to a dental treatment. Most sequences were related to microorganisms derived from biofilm in oligotrophic environments.     

Effect of utilization of substrates on the composition of dental plaque

Abstract The microbiota in the mouth is subjected to substrate limitations. In this study we have evaluated the role of competition for carbon and energy substrates on the proportions of 2 microbial species in a simplified plaque ecosystem in gnotobiotic rats. Germ-free rats were inoculated with a combination of Streptococcus sanguis and Streptococcus mutans , or with a combination of Streptococcus milleri and S. mutans . The available carbon and energy sources were varied through the host's diet. 3 Experimental diets were tested: (i) a basal diet low in soluble carbohydrates; (ii) an arginine-supplemented diet; (iii) a sucrose-supplemented diet. Arginine is used for growth by S. sanguis and S. milleri , but not by S. mutans . Sucrose is rapidly fermented by all 3 species.
The total number of viable organisms on the dentition increased when arginine or sucrose were supplied in the diet. With the arginine-supplemented diet, S. sanguis and S. milleri increased while S. mutans decreased. With the sucrose-supplemented diet, S. mutans increased while S. sanguis and S. milleri decreased. These results were explained by assuming that the organism with the highest growth rate on the supplementary substrate competes most favourably. Changes in the environmental pH, due to breakdown of sucrose and arginine, might also have affected the competition between the streptococci. In addition, production of extracellular glucans from sucrose could be a competitive advantage for S. mutans .     

Oxidized LDL from subjects with different dietary habits modifies atherogenic processes in endothelial and smooth muscle cells

Low-density lipoprotein (LDL) activates a number of processes involved in atherogenesis and vasoconstriction. Evidence suggests that oxidation increases the atherogenicity of LDL. We investigated the effects of oxidized LDL (ox-LDL) on cytotoxicity, prostacyclin (PGI2), and cyclic guanosine-3',5'-monophosphate (cGMP) production in rat vascular smooth muscle cell (VSMC) and rat heart endothelial cell (EC) culture, as well as EC- and VSMC-mediated LDL oxidation. Native LDL (n-LDL) was isolated from subjects on three long-term diets with differing fatty acid content (control diet rich in saturated fat and vegetarian and fish diets). The Cu2+-catalyzed oxidation of n-LDL was monitored using conjugated diene formation and stopped at various time points to achieve 20%, 45%, 70%, and 100% levels of ox-LDL. The lag phase of oxidation by Cu2+ was shortest and thiobarbituric acid-reactive substance (TBARS) formation by VSMC-mediated oxidation was highest with n-LDL obtained from the fish diet group. There were no differences between the ox-LDLs obtained from the different diet groups in their cytotoxicity in EC culture. The degree of oxidation did not influence LDL cytotoxicity. In VSMC culture PGI2 production was increased by ox-LDLs from all diet groups. In EC culture only the extensively oxidized LDLs obtained from the vegetarian diet group were able to induce PGI2 production. The LDLs did not affect basal cGMP production in either EC or VSMC culture.     

Fatty acid composition of fish species with different feeding habits from an Arctic Lake

We compared the composition and content of fatty acids (FAs) in fish with different feeding habits (sardine (least) cisco Coregonus sardinella, goggle-eyed charr (pucheglazka) form of Salvelinus alpinus complex, humpback whitefish Coregonus pidschian, broad whitefish Coregonus nasus, boganid charr Salvelinus boganidae, and northern pike Esox lucius from an Arctic Lake. Feeding habits of the studied fish (planktivore, benthivore, or piscivore) significantly affected the composition of biomarker fatty acids and the ratio of stable isotopes of carbon and nitrogen in their biomass. The hypothesis on a higher content of eicosapentaenoic and docosahexaenoic acids in the fish of higher trophic level (piscivores) when compared within the same taxonomic group (order Salmoniformes) was confirmed.     

不同能量代谢率的山羊瘤胃微生物结构与组成的差异性

【背景】能量代谢率是衡量饲粮利用效率的一个重要组成部分,提高反刍动物对不同营养物质所含能量的消化代谢率,有助于提高反刍动物对能量的利用效率。【目的】通过高通量测序技术比较不同能量代谢率的山羊瘤胃微生物结构与组成的差异。【方法】以19只山羊作为试验动物,通过代谢试验和呼吸测热试验筛选出高能量代谢率表型组(HEU)和低能量代谢率表型组(LEU)山羊各5只。分别采集HEU、LEU组每只山羊瘤胃内容物,提取微生物总DNA,用细菌通用引物对细菌16S rRNA基因的高可变区进行PCR扩增,利用Illumina Mi Seq平台对扩增子进行高通量测序,并用QIIME等软件对测序序列进行生物信息学分析。【结果】拟杆菌门(44.20%±9.39%)、厚壁菌门(16.40%±5.44%)和变形菌门(11.30%±7.42%)在两组山羊瘤胃微生物中均为优势菌门,其中厚壁菌门是两组中共享的优势菌门。LEU组(6.71%±2.47%)中芽孢杆菌纲相对丰度显著高于HEU组(P0.05)。两组相对丰度最高的目均为乳酸杆菌目,LEU组(4.98%±1.88%)乳酸杆菌目相对丰度显著高于HEU组(P0.05)。在科水平,有7个科的相对丰度在组间差异性显著(P0.05)。拟杆菌科在两组中均为相对丰度最高的科,LEU组(3.64%±1.32%)拟杆菌科的相对丰度显著高于HEU组(P0.05)。在属水平,有9个属的相对丰度在组间差异性显著(P0.05)。HEU组(0.61%±0.36%)仅有普雷沃氏菌属的相对丰度显著高于LEU组(0.16%±0.07%),其他8个属的相对丰度均显著低于LEU组(P0.05)。其中瘤胃球菌属在HEU组(2.53%±0.62%)和LEU组(4.19%±1.43%)中均为相对丰度最高的属。【结论】不同能量代谢率的山羊瘤胃微生物结构与组成存在显著性差异。     

Lactobacilli in human dental caries and saliva

Samples (98 plaque and 72 saliva) from 93 patients with dental caries were investigated for Lactobacillus species which comprised 65 (62.5%) of 104 isolates. Yeasts (20.1%), Streptococcus spp. (8.7%), Staphylococcus spp. (2.9%) and a few unidentified species (5.8%), were also found. The Lactobacillus isolates were L. brevis (24.6%) L. fermentum (18.5%) L. casei (16.9%), L. delbrueckii (15.4%), L. plantarum (9.23%), L. acidophilus (7.69%), L. jensenii (4.62%), L. salivarius (1.54%) and L. gasseri (1.54%). The most common species was L. brevis (24.6%). The strains tested for beta-lactamase production showed 75.4% positive. All the Lactobacillus strains were tested for bacteriocin production against Escherichia coli, Salmonella spp., Shigella dysenteriae, S. sonnei, Klebsiella spp. and Campylobacter sp. All the lactobacilli except L. jensenii produced bacteriocin against at least one of the indicator organisms. The involvement of Lactobacillus in dental caries was established, although its role and mechanism is not well understood. The ability of Lactobacillus spp. to protect their host against certain diseases by inhibiting the growth of potential pathogens was evident.     

Doctors' drinking habits and consumption of alcohol.

Alcohol consumption and drinking habits among Finnish doctors were studied as part of a survey of stress and burnout. A questionnaire containing 99 questions or groups of questions was sent to all 3496 practising doctors aged under 66 randomly selected from the registry of the Finnish Medical Association. Altogether 2671 doctors (76%) responded; this sample was representative of the Finnish medical profession. The average weekly consumption of alcohol during the past year and various aspects of drinking behaviour were assessed, and the presence or absence of symptoms and diseases often encountered among heavy drinkers and addicts was determined. The data were analysed separately for men and women, for those aged less than or equal to 40 and greater than 40, and for the men with high and low alcohol consumption and with high and low scores on the index of drinking habits. Selected variables related to work, stress, and coping were correlated with alcohol consumption and drinking behaviour. The median consumption of alcohol among male doctors was 4876 g (6.2 litres) and among female doctors 2226 g (2.8 litres) of absolute alcohol per person per year and was higher in those aged over 40. Beer was most commonly drunk by men and wine by women. Increased alcohol consumption was associated with older age, disappointment with career, heavy smoking, use of benzodiazepines, stress and burnout symptoms, suicidal thoughts, general dissatisfaction, and diseases related to alcohol. Drinking habits were heavier among doctors working in community health centres, those taking long sick leaves, younger doctors disappointed with their careers or the atmosphere at work, and older doctors immersed in their work. Alcohol consumption among doctors seems to be higher than that of the general population in Finland, and heavy drinking seems to be associated with stress and burnout.     

The similarity of the microbiological flora of dental plaque collected from discrete contralateral sites on rat molar teeth

Streptococci, actinomycetes, actinobacilli, veillonellae, neisseriae, and lactobacilli were isolated from the anterior fissures of the second mandibular molar teeth of Sprague-Dawley rats. In individual animals, there were no great differences between the percentage bacterial composition of plaque collected from discrete sites on different sides of the same mouth. This bilateral similarity was apparent with each of four diets, irrespective of the cariogenicity of the diet. These findings indicate why the pattern of carious attack in rats is bilaterally symmetrical.     

Corrosion behaviour of the Co-Cr-Mo dental alloy in solutions of different composition and different pH values

The purpose of this study was to examine how Co-Cr-Mo dental alloy behaves in the solutions of different pH value and different composition over a relatively long period of time. Co-Cr-Mo dental alloy was exposed in vitro to either simulated saliva (phosphate buffer pH 6.0), a highly acidic medium resembling the extreme conditions in the oral cavity (phosphate buffer pH 3.5), and in lactic acid at pH which occurs under the dental plaque (lactic acid pH 3.5). The alloy samples were immersed in these three solution for 1, 2, 3, 4, 5, 6, 7, 14, 21, and 30 days. Solutions were analysed with the ICP-AES. The analysis showed that during one month cobalt (Co), chromium (Cr), iron (Fe), zinc (Zn) and nickel (Ni) ions had been released from tested samples in all three solutions. The results of this study indicate that the leaching of the Co, Cr, Fe, Zn and Ni ions in the solution was dependent both upon the nature of the solution in which the alloy was immersed and the duration of the immersion (p < 0.001).     

The salivary flow rate and composition of whole and parotid resting and stimulated saliva in young and old healthy subjects

Resting and stimulated whole and parotid salivary composition and flow rate were examined in 63 healthy volunteers. No significant differences were found between the young and old in secretion rates and salivary concentrations of sodium, potassium, calcium, magnesium, and total protein. The activity of amylase in the resting and stimulated parotid saliva was significantly lower in the old.     

Biogenesis of methane in primate dental plaque

Dental plaque samples collected from monkeys (Macaca mulatta) were found to contain a large amount of dissolved methane gas (0.6 nmol CH4/mg wet wt plaque). Enrichment cultures inoculated with dental plaque obtained from Macaca fascicularis produced methane when the medium contained ethanol, methanol, lactate, acetate or a hydrogen + CO2 atmosphere. Methane formation in the enrichments was inhibited by oxidation of the culture medium, autoclaving or the addition of 2-bromoethane sulfonic acid (BES). The methane producing enrichments were observed to contain fluorescent cocci occurring singly and in short chains. It was concluded that methane formation in the monkey dental plaque was the result of the presence of methanogenic bacteria.     

牙菌斑生物膜的形成与控制

牙菌斑生物膜是附着于牙釉质表面,由复杂的微生物群落构成的一种聚集体。牙菌斑生物膜的形成与生长对口腔健康有着直接或间接的影响,许多研究证实口腔疾病如龋齿和牙周病都与细菌的积累及牙菌斑的形成有关。在牙菌斑生物膜形态建成过程中,牙齿表面最初的定殖菌对生物膜的微生物组成和结构至关重要,这些初级定殖菌决定了后续与之结合形成共生体的微生物种类和数量。不同的微生物组成可能在与生物膜形成相关的口腔病理状况中发挥不同的作用。因此,本文就牙菌斑生物膜的生长及控制进行综述,介绍其微生物的早期定殖和成熟过程、以及通过物理和化学方法对牙菌斑生物膜的控制,以期为了解牙菌斑生物膜的形成机制及相关口腔疾病的预防和治疗提供有价值的参考。     

Streptococcus mutans and oral streptococci in dental plaque

The human oral microbial biota represents a highly diverse biofilm. Twenty-five species of oral streptococci inhabit the human oral cavity and represent about 20 % of the total oral bacteria. Taxonomy of these bacteria is complex and remains provisional. Oral streptococci encompass friends and foes bacteria. Each species has developed specific properties for colonizing the different oral sites subjected to constantly changing conditions, for competing against competitors, and for resisting external agressions (host immune system, physico-chemical shocks, and mechanical frictions). Imbalance in the indigenous microbial biota generates oral diseases, and under proper conditions, commensal streptococci can switch to opportunistic pathogens that initiate disease in and damage to the host. The group of "mutans streptococci" was described as the most important bacteria related to the formation of dental caries. Streptococcus mutans, although naturally present among the human oral microbiota, is the microbial species most strongly associated with carious lesions. This minireview describes the oral streptococci ecology and their biofilm life style by focusing on the mutans group, mainly S. mutans. Virulence traits, interactions in the biofilm, and influence of S. mutans in dental caries etiology are discussed.