1,720,956 research outputs found
METAGENOMIC ANALYSIS OF PERIODONTAL BACTERIA ASSOCIATED WITH GENERALIZED AGGRESSIVE PERIODONTITIS
No full textGeneralized Aggressive Periodontitis - A Periodontal Chimera
No full textHealth Sciences: 1st Place (The Ohio State University Edward F. Hayes Graduate Research Forum)Objectives: Periodontitis is a disease of the surrounding tissues of the tooth (periodontium) in which the destruction leads to weakening of the tooth support and eventual tooth loss. Approximately 46% of adults in the US suffer from this disease.1 The current classification of periodontal diseases and conditions recognizes 3 forms of periodontitis: Chronic periodontitis (CP), Localized Aggressive Periodontitis (LAP), and Generalized Aggressive Periodontitis (GAP). All three are inflammatory conditions that are microbial in nature. GAP is considered the most destructive of the three conditions due to its rapid destruction of the periodontium and its wide distribution in the mouth. Previous close-ended approaches to examine the bacterial constituents of the 3 diseases were equivocal, however, the consensus is that CP and GAP are considered polymicrobial in nature, while LAP is attributed to a mono-infection of the bacterial species Aggregatibacter actinomycetemcomitans.2 Since evidence is emerging that taxonomically distinct periodontal biofilms are functionally congruent, the present investigation sought to characterize the functional potential within the subgingival bacteria of CP, GAP and LAP. Methods: Subgingival plaque samples were collected from deep and shallow sites of 25 patients with CP, 17 with GAP, and 17 with LAP. Whole-genome shotgun DNA sequencing was used to characterize the functions encoded in these microbial communities. Sequences were analyzed using the MG-RAST pipeline for subsystem classification, and Kraken for taxonomic identification. Organismal diversity and functional abundances were compared between groups using dissimilarity indices, differential abundance metrics and network analysis. Results: 11.5 million sequences per sample contributed to 5973 functionally annotated genes. Principal coordinate analysis revealed distinct clustering of the three diseases based on community membership, structure and functional potential (p<0.05, ANOSIM). GAP separated the distances between LAP and CP, concordant with concept of a mixed infection of the two diseases. GAP and CP had similar functions of fermentation, phage transfer, while GAP and LAP had similar virulence factors. Taxonomic analysis revealed the polymicrobial nature of all three conditions. Network analysis showed similar inter-bacterial interaction networks between GAP and LAP, with similar membership of Treponema denticola, Filifactor alocis, Tannerella forsythia and Porphyromonadaceae Spp. Implications: This is the first time that the three disease entities are shown to exist as a continuum rather than discrete disease entities. This paradigm shift in has major implications on the classification of disease. That is, the aggressive but localized nature of LAP is globalized to the entire periodontal tissues by the superimposition of CP. Moreover, these findings cast doubt on current empirical treatment protocols for GAP that follow closely the protocols made for LAP. Finally, the breadth of the microbial members in LAP extend beyond the single bacteria species which greatly expands our understanding of the disease.A five-year embargo was granted for this item
Assessment of Effectiveness of Three Aerosol Mitigation Methods for Orthodontic Debonding
Full text linkBackground: The COVID-19 pandemic has shown us that our infection
prevention and control (IPC) knowledge has some glaring gaps on what best ways to
treat dental patients, leading to a flurry of research to understand the best mitigation
strategies to reduce aerosols. One of these strategies was the addition of a Local
Exhaust Ventilation System (LEV), similar to the ones used in other fields as
construction, soldering and chemical engineering. Hypothesis: In this manuscript, we
investigated the additional effect of adding aerosol capture methods during orthodontic
debonding to investigate their added effect to high-volume evacuator (the golden
standard). Materials and Methods: We investigated three mitigation methods during
orthodontic debonding: 1) HVE, 2) HVE and saliva ejector, 3) HVE, saliva ejector and a
LEV device, BriteHive, which shares the dental chair's HVE connector. We have used a
randomized clinical trial approach to investigate whether the three methods are
statistically equivalent from each other (effect size of 0.2 standard deviations ~ 16%
from each other). And measured the aerosols generated from the three mitigation
strategies using two devices, Optical Particle Sizer (OPS) which measures particle
concentration across 13 different particle sizes, and DustTrak, which measures mass
concentration across different particle matter, PM sizes. Results: Mass concentration
showed that HVE and Saliva Ejector strategy had the lowest number of statistically
significant PM sizes, with only the total PM size being statistically significant.
Conclusion: The addition of Saliva Ejector to HVE should supersede both HVE, and
HVE, Saliva Ejector and BriteHive as the gold standard
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Changes in a Child's Subgingival Microbiome Following Prophylaxis - a Pilot Study
Full text linkBackground: Periodontitis is a multifactorial, complex chronic oral disease facilitated by oral microbes. Transmissibility studies of the past have shown that oral microbes are transmissible between individuals. Furthermore, periodontal disease phenotypes also appear to be inheritable to some extent, both from parent to child and between adults. Modern DNA sequencing has allowed for greater resolution and further insight into the transmission rates of the oral microbiome. In this study, transmission rates of the oral microbiome were investigated within the family unit, especially as it relates to the recolonization of the oral microbiome of the youngest child in multi-child families.Aims: 1) Identify the sources of subgingival microbiome within an individual. 2) Identify the effect of intimate contact between parents and child as well as between siblings and child in vertical and horizontal transmission of the microbiome. 3) Examine the effect of recolonization on the child after professional oral prophylaxis.Materials and methods: 14 families were recruited, each family having 1 mother, 1 father, and two or more children. Microbial samples were collected from each individual. Oral prophylaxis was then performed for the youngest child. An additional saliva sample was collected from the youngest child at day 3, and then all oral samples again collected for the youngest child at one week following prophylaxis. Samples were then processed and DNA isolated, sequenced (V1-V3), and passed through a computational pipeline (DADA2) to determine amplicon sequence variants (ASVs). These were then analyzed using a Bayesian analysis model to estimate the contribution of all samples to the subgingival microbiota of the youngest child.Results: The findings of this study are four-fold:1. Oral niche was the main driver of microbial separation. The microbes that were found in a specific location in the mouth were mainly selected due to the characteristics of that niche rather than by familial similarity or geographical proximity.2. Saliva was the conduit for oral cavity microbiota. Saliva was the main vehicle for microbial transmission between individuals. The saliva was made up of microbes from other areas of the mouth, including the tongue (58.9%), buccal mucosa (14.8%), supragingival plaque (1.1%), subgingival plaque (0.8%), and unknown sources (12.5%).3. Various sources of microbes contributed to the subgingival plaque of the child. Some of these sources were internal to the child, specifically the subgingival plaque already present at time 0 (46%), as well as the supragingival plaque at time 0 (9%), and buccal mucosal microbes (1%). Sources external to the child also existed. Both mother and father contributed about 3% each to the recolonization of the oral microbiome, while each sibling contributed approximately 8%. Of those sources external to the child, 8% was from subgingival sources, 4% from supragingival sources, and 1% was from the buccal. All other sources were negligible.4. The only close contact activities that had a statistically significant contribution to the subgingival plaque of the child included mother close sleeping with the child and saliva contribution, and father kissing the child on the cheek and buccal mucosal microbial transmission. Conclusion: Within the family unit, transmission of oral microbes does occur. This transmission is most pronounced between siblings (8%), and not as strongly from parent to child (3%) as originally expected. The majority of this transmission is via the saliva, which contains only 0.8% of subgingival bacteria. Even then, the major contributor to the subgingival microbes of the child from external sources is the subgingival bacteria of family members. As shown in this study, transmission of oral microbes between family members does occur, with greater importance seen in the contribution of siblings than expected. Thus, the treatment of periodontal disease may need to shift from an individual disease control model to a family-based, transmissible disease model
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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