Aberrant immunity in the oral cavity-a link with rheumatoid arthritis?

There are well established epidemiological links between rheumatoid arthritis and periodontitis. Recent data have started to shed light on the mechanisms that might underlie the relationship between these two complex diseases. Unravelling the roles of distinct pathways involved in these mechanisms has the potential to yield novel preventative and therapeutic strategies for both diseases. Perhaps most intriguingly, this represents an area where understanding the biology in the oral cavity might reveal fundamental advances in understanding immune regulation and the relationships between the host and microbiome. Here we seek to discuss aspects of the adaptive immune response that might link periodontitis and rheumatoid arthritis.

Periodontitis and rheumatoid arthritis-Global efforts to untangle two complex diseases.

Understanding the impact of oral health on rheumatoid arthritis (RA) will inform how best to manage patients with both periodontitis and RA. This review seeks to provide an update on interventional and mechanistic investigations, including a brief summary of European Research programs investigating the link between periodontitis and RA. Recent clinical studies are described that evaluate how the treatment of one disease impacts on the other, as are studies in both humans and animal models that have sought to identify the potential mechanisms linking the two diseases.

COVID-19 Adaptations with Virtual Microscopy.

This chapter aims to discuss and compare the different approaches used to teach histology to dental students before and during the COVID-19 pandemic and reflect on the best practices to be retained. Prior to the COVID-19 pandemic, the University of Glasgow School of Dentistry converted its large and unique collections of microscopy slides into digital files to curate this unique asset and protect it for prosperity. Initially, a virtual microscopy (VM) educational platform was purchased to allow digital teaching of histology, oral biology, and oral pathology. Prior to COVID-19, dental undergraduate students received VM teaching via a blended learning approach with theoretical content preceding a practical discussion session using VM. Some teachers in later years of the dental course experimented with flipped class strategies. At the beginning of 2020, with the lockdown restrictions imposed, the teaching content all had to move to remote online learning with virtual sessions, recorded video classes, online content, videotelephony, and online chat, allowing the students to undertake the content asynchronously and remotely. To overcome the interactive limitations of online delivery, a Microsoft Team was created in some sessions and used to support active small group learning and teaching of general histology allowing students to share histological annotations with their peers and tutors. The experience of teaching histology using only virtual and online content has had a positive academic outcome for the students as all first year students had passed their exams. However, we also recognise several limitations, such as the restrictive interpersonal interaction using videotelephony and online chat as well as the ad hoc feedback. The processes used and the challenges and benefits of VM will be discussed in this chapter.

The Oral Microbiome of Denture Wearers Is Influenced by Levels of Natural Dentition.

OBJECTIVES: The composition of dental plaque has been well defined, whereas currently there is limited understanding of the composition of denture plaque and how it directly influences denture related stomatitis (DS). The aims of this study were to compare the microbiomes of denture wearers, and to understand the implications of these towards inter-kingdom and host-pathogen interactions within the oral cavity. METHODS: Swab samples were obtained from 123 participants wearing either a complete or partial denture; the bacterial composition of each sample was determined using bar-coded illumina MiSeq sequencing of the bacterial hypervariable V4 region of 16S rDNA. Sequencing data processing was undertaken using QIIME, clustered in Operational Taxonomic Units (OTUs) and assigned to taxonomy. The dentures were sonicated to remove the microbial flora residing on the prosthesis, sonicate was then cultured using diagnostic colorex Candida media. Samples of unstimulated saliva were obtained and antimicrobial peptides (AMP) levels were measured by ELISA. RESULTS: We have shown that dental and denture plaques are significantly distinct both in composition and diversity and that the oral microbiome composition of a denture wearer is variable and is influenced by the location within the mouth. Dentures and mucosa were predominantly made up of Bacilli and Actinobacteria. Moreover, the presence of natural teeth has a significant impact on the overall microbial composition, when compared to the fully edentulous. Furthermore, increasing levels of Candida spp. positively correlate with Lactobacillus spp. AMPs were quantified, though showed no specific correlations. CONCLUSIONS: This is the first study to provide a detailed understanding of the oral microbiome of denture wearers and has provided evidence that DS development is more complex than simply a candidal infection. Both fungal and bacterial kingdoms clearly play a role in defining the progression of DS, though we were unable to show a defined role for AMPs.

Polymicrobial Candida biofilms: friends and foe in the oral cavity.

The role of polymicrobial biofilm infections in medicine is becoming more apparent. Increasing number of microbiome studies and deep sequencing has enabled us to develop a greater understanding of how positive and negative microbial interactions influence disease outcomes. An environment where this is particularly pertinent is within the oral cavity, a rich and diverse ecosystem inhabited by both bacteria and yeasts, which collectively occupy and coexist within various niches as biofilm communities. Studies within this environment have however tended to be subject to extensive independent investigation, in the context of either polymicrobial bacterial communities or yeast biofilms, but rarely both together. It is clear however that they are not mutually exclusive. Therefore, this review aims to explore the influence of candidal populations on the composition of these complex aggregates and biofilm communities, to investigate their mechanistic interactions to understand how these impact clinical outcomes, and determine whether we can translate how this knowledge can be used to improve patient management.

Stories of family, stories of self: developmental pathways to interpretive thought during adolescence.

Research has shown that a hallmark of adolescent development is the growing capacity to interpret human intentionality. In this chapter, the authors examine developmental change in this capacity, which they have termed interpretive thought, in two types of stories, family and autobiographical, told by Canadian youth aged ten to seventeen years. Illustrative examples reveal that youth coordinate an increasing number of psychological components and in so doing, create increasingly abstract and coherent psychological profiles of self and others.

Hepatitis C: diagnosis and treatment.

Hepatitis C, a common chronic bloodborne infection, is found in approximately 2 percent of adults in the United States. Chronic infection is associated with serious morbidity and mortality (e.g., cirrhosis, hepatocellular carcinoma). Testing for hepatitis C is recommended for at-risk populations, and confirmatory testing includes quantification of virus by polymerase chain reaction. The U.S. Preventive Services Task Force recommends against routine screening for hepatitis C virus infection in asymptomatic adults who are not at increased risk of infection (general population). It found insufficient evidence to recommend for or against routine screening in adults at high risk of infection. Current therapy for chronic hepatitis C virus includes pegylated interferon and ribavirin. Therapy is based on factors that predict sustained virologic response, and the goal of therapy is to slow or halt progression of fibrosis and prevent the development of cirrhosis. In the future, multidrug regimens in combination with current therapies may be developed. Patients with chronic hepatitis C virus infection should be advised to abstain from alcohol use. Currently, there is no vaccine available to prevent hepatitis C virus infection; however, persons infected with hepatitis C virus should be vaccinated for hepatitis A and B. The American Association for the Study of Liver Diseases recommends ultrasound surveillance for hepatocellular carcinoma in persons with chronic hepatitis C virus infection and cirrhosis.

Activation of human acid sphingomyelinase through modification or deletion of C-terminal cysteine.

One form of Niemann-Pick disease is caused by a deficiency in the enzymatic activity of acid sphingomyelinase. During efforts to develop an enzyme replacement therapy based on a recombinant form of human acid sphingomyelinase (rhASM), purified preparations of the recombinant enzyme were found to have substantially increased specific activity if cell harvest media were stored for several weeks at -20 degrees C prior to purification. This increase in activity was found to correlate with the loss of the single free thiol on rhASM, suggesting the involvement of a cysteine residue. It was demonstrated that a variety of chemical modifications of the free cysteine on rhASM all result in substantial activation of the enzyme, and the modified cysteine responsible for this activation was shown to be the C-terminal residue (Cys629). Activation was also achieved by copper-promoted dimerization of rhASM (via cysteine) and by C-terminal truncation using carboxypeptidase Y. The role of the C-terminal cysteine in activation was confirmed by creating mutant forms of rhASM in which this residue was either deleted or replaced by a serine, with both forms having substantially higher specific activity than wild-type rhASM. These results indicate that purified rhASM can be activated in vitro by loss of the free thiol on the C-terminal cysteine via chemical modification, dimerization, or deletion of this amino acid residue. This method of activation is similar to the cysteine switch mechanism described previously for matrix metalloproteinases and could represent a means of posttranslational regulation of ASM activity in vivo.

A biochemical and pharmacological comparison of enzyme replacement therapies for the glycolipid storage disorder Fabry disease.

Fabry disease is a lysosomal storage disease arising from deficiency of the enzyme alpha-galactosidase A. Two recombinant protein therapeutics, Fabrazyme (agalsidase beta) and Replagal (agalsidase alfa), have been approved in Europe as enzyme replacement therapies for Fabry disease. Both contain the same human enzyme, alpha-galactosidase A, but they are produced using different protein expression systems and have been approved for administration at different doses. To determine if there is recognizable biochemical basis for the different doses, we performed a comparison of the two drugs, focusing on factors that are likely to influence biological activity and availability. The two drugs have similar glycosylation, both in the type and location of the oligosaccharide structures present. Differences in glycosylation were mainly limited to the levels of sialic acid and mannose-6-phosphate present, with Fabrazyme having a higher percentage of fully sialylated oligosaccharides and a higher level of phosphorylation. The higher levels of phosphorylated oligomannose residues correlated with increased binding to mannose-6-phosphate receptors and uptake into Fabry fibroblasts in vitro. Biodistribution studies in a mouse model of Fabry disease showed similar organ uptake. Likewise, antigenicity studies using antisera from Fabry patients demonstrated that both drugs were indistinguishable in terms of antibody cross-reactivity. Based on these studies and present knowledge regarding the influence of glycosylation on protein biodistribution and cellular uptake, the two protein preparations appear to be functionally indistinguishable. Therefore, the data from these studies provide no rationale for the use of these proteins at different therapeutic doses.