Exploring the oral microbiota of children at various developmental stages of their dentition in the relation to their oral health

<p>Abstract</p> <p>Background</p> <p>An understanding of the relation of commensal microbiota to health is essential in preventing disease. Here we studied the oral microbial composition of children (N = 74, aged 3 - 18 years) in natural transition from their deciduous to a permanent dentition and related the microbial profiles to their oral health status. The microbial composition of saliva was assessed by barcoded pyrosequencing of the V5-V6 hypervariable regions of the 16 S rRNA, as well as by using phylogenetic microarrays.</p> <p>Results</p> <p>Pyrosequencing reads (126174 reads, 1045 unique sequences) represented 8 phyla and 113 higher taxa in saliva samples. Four phyla - Firmicutes, Bacteriodetes, Proteobacteria and Actinobacteria - predominated in all groups. The deciduous dentition harboured a higher proportion of Proteobacteria (Gammaproteobacteria, Moraxellaceae) than Bacteroidetes, while in all other groups Bacteroidetes were at least as abundant as Proteobacteria. Bacteroidetes (mainly genus <it>Prevotella</it>), Veillonellaceae family, Spirochaetes and candidate division TM7 increased with increasing age, reflecting maturation of the microbiome driven by biological changes with age.</p> <p>Microarray analysis enabled further analysis of the individual salivary microbiota. Of 350 microarray probes, 156 gave a positive signal with, on average, 77 (range 48-93) probes per individual sample.</p> <p>A caries-free oral status significantly associated with the higher signal of the probes targeting <it>Porphyromonas catoniae </it>and <it>Neisseria flavescens</it>.</p> <p>Conclusions</p> <p>The potential role of <it>P. catoniae </it>and <it>N. flavescens </it>as oral health markers should be assessed in large-scale clinical studies. The combination of both, open-ended and targeted molecular approaches provides us with information that will increase our understanding of the interplay between the human host and its microbiome.</p

Analyses of the Microbial Diversity across the Human Microbiome

Analysis of human body microbial diversity is fundamental to understanding community structure, biology and ecology. The National Institutes of Health Human Microbiome Project (HMP) has provided an unprecedented opportunity to examine microbial diversity within and across body habitats and individuals through pyrosequencing-based profiling of 16 S rRNA gene sequences (16 S) from habits of the oral, skin, distal gut, and vaginal body regions from over 200 healthy individuals enabling the application of statistical techniques. In this study, two approaches were applied to elucidate the nature and extent of human microbiome diversity. First, bootstrap and parametric curve fitting techniques were evaluated to estimate the maximum number of unique taxa, Smax, and taxa discovery rate for habitats across individuals. Next, our results demonstrated that the variation of diversity within low abundant taxa across habitats and individuals was not sufficiently quantified with standard ecological diversity indices. This impact from low abundant taxa motivated us to introduce a novel rank-based diversity measure, the Tail statistic, (“τ”), based on the standard deviation of the rank abundance curve if made symmetric by reflection around the most abundant taxon. Due to τ’s greater sensitivity to low abundant taxa, its application to diversity estimation of taxonomic units using taxonomic dependent and independent methods revealed a greater range of values recovered between individuals versus body habitats, and different patterns of diversity within habitats. The greatest range of τ values within and across individuals was found in stool, which also exhibited the most undiscovered taxa. Oral and skin habitats revealed variable diversity patterns, while vaginal habitats were consistently the least diverse. Collectively, these results demonstrate the importance, and motivate the introduction, of several visualization and analysis methods tuned specifically for next-generation sequence data, further revealing that low abundant taxa serve as an important reservoir of genetic diversity in the human microbiome

Pyrosequencing as a tool for better understanding of human microbiomes

Next-generation sequencing technologies have revolutionized the analysis of microbial communities in diverse environments, including the human body. This article reviews several aspects of one of these technologies, the pyrosequencing technique, including its principles, applications, and significant contribution to the study of the human microbiome, with especial emphasis on the oral microbiome. The results brought about by pyrosequencing studies have significantly contributed to refining and augmenting the knowledge of the community membership and structure in and on the human body in healthy and diseased conditions. Because most oral infectious diseases are currently regarded as biofilm-related polymicrobial infections, high-throughput sequencing technologies have the potential to disclose specific patterns related to health or disease. Further advances in technology hold the perspective to have important implications in terms of accurate diagnosis and more effective preventive and therapeutic measures for common oral diseases

Nothing Lasts Forever: Environmental Discourses on the Collapse of Past Societies

The study of the collapse of past societies raises many questions for the theory and practice of archaeology. Interest in collapse extends as well into the natural sciences and environmental and sustainability policy. Despite a range of approaches to collapse, the predominant paradigm is environmental collapse, which I argue obscures recognition of the dynamic role of social processes that lie at the heart of human communities. These environmental discourses, together with confusion over terminology and the concepts of collapse, have created widespread aporia about collapse and resulted in the creation of mixed messages about complex historical and social processes

Targeted delivery of small interfering RNA to angiogenic endothelial cells with liposome-polycation-DNA particles.

Angiogenesis is an attractive target for cancer therapy, due to its central position in tumor growth and development. Vascular Endothelial Growth Factor (VEGF) and its receptors (VEGFRs) play a key role in the angiogenic process. A promising strategy for targeting VEGF-mediated angiogenesis is RNA interference (RNAi) using short interfering RNA (siRNA). However, for efficacious RNAi a well-designed siRNA delivery system is crucial. Liposome-Polycation-DNA (LPD) particles form a promising system for siRNA delivery to tumors. In order to target angiogenic endothelial cells, LPD particles may be modified with a targeting ligand, such as a cyclic Arg-Gly-Asp (RGD) peptide that specifically binds to integrins expressed on tumor-associated endothelial cells. In the current study, RGD-targeted PEGylated LPD particles containing VEGFR-2 siRNA were prepared and optimized with respect to their size and charge by varying protamine content, carrier DNA content for stronger complexation, and PEGylation density. The size of the optimized particles was around 200 nm and the ζ-potential was approximately +20 mV. The uptake and silencing efficacy of the RGD-targeted PEGylated LPD particles were evaluated in H5V cells (murine endothelial cells) and Human Umbilical Vein Endothelial cells (HUVECs). When compared to non-targeted LPD particles, enhanced uptake and silencing of VEGFR-2 expression was observed for RGD-targeted PEGylated LPD particles. In conclusion, the RGD-targeted PEGylated LPD particles containing VEGFR-2 siRNA presented here may be a promising approach for targeting VEGF-mediated angiogenesis in cancer therapy

Western Star, 1914-09-09

The Western Star began publication on Newfoundland's west coast on 4 April 1900, appearing weekly with brief semiweekly periods up to 1952, when it became a daily. As of 17 April 2019 it continues as a free weekly community paper

Preliminary characterization of the oral microbiota of Chinese adults with and without gingivitis

<p>Abstract</p> <p>Background</p> <p>Microbial communities inhabiting human mouth are associated with oral health and disease. Previous studies have indicated the general prevalence of adult gingivitis in China to be high. The aim of this study was to characterize in depth the oral microbiota of Chinese adults with or without gingivitis, by defining the microbial phylogenetic diversity and community-structure using highly paralleled pyrosequencing.</p> <p>Methods</p> <p>Six non-smoking Chinese, three with and three without gingivitis (age range 21-39 years, 4 females and 2 males) were enrolled in the present cross-sectional study. Gingival parameters of inflammation and bleeding on probing were characterized by a clinician using the Mazza Gingival Index (MGI). Plaque (sampled separately from four different oral sites) and salivary samples were obtained from each subject. Sequences and relative abundance of the bacterial 16 S rDNA PCR-amplicons were determined via pyrosequencing that produced 400 bp-long reads. The sequence data were analyzed via a computational pipeline customized for human oral microbiome analyses. Furthermore, the relative abundances of selected microbial groups were validated using quantitative PCR.</p> <p>Results</p> <p>The oral microbiomes from gingivitis and healthy subjects could be distinguished based on the distinct community structures of plaque microbiomes, but not the salivary microbiomes. Contributions of community members to community structure divergence were statistically accessed at the phylum, genus and species-like levels. Eight predominant taxa were found associated with gingivitis: TM7, <it>Leptotrichia</it>, <it>Selenomonas</it>, <it>Streptococcus</it>, <it>Veillonella</it>, <it>Prevotella</it>, <it>Lautropia</it>, and <it>Haemophilus</it>. Furthermore, 98 species-level OTUs were identified to be gingivitis-associated, which provided microbial features of gingivitis at a species resolution. Finally, for the two selected genera <it>Streptococcus </it>and <it>Fusobacterium</it>, Real-Time PCR based quantification of relative bacterial abundance validated the pyrosequencing-based results.</p> <p>Conclusions</p> <p>This methods study suggests that oral samples from this patient population of gingivitis can be characterized via plaque microbiome by pyrosequencing the 16 S rDNA genes. Further studies that characterize serial samples from subjects (longitudinal study design) with a larger population size may provide insight into the temporal and ecological features of oral microbial communities in clinically-defined states of gingivitis.</p