The Effect of Chitosan Incorporation on Physico-Mechanical and Biological Characteristics of a Calcium Silicate Filling Material.

OBJECTIVES: A tricalcium silicate-based cement, Biodentine™, has displayed antibiofilm activity when mixed with chitosan powder. This study aimed to assess the effect of chitosan incorporation on the physico-mechanical and biological properties of Biodentine™. METHODS: In this study, medium molecular weight chitosan powder was incorporated into Biodentine™ in varying proportions (2.5 wt%, 5 wt%, 10 wt%, and 20 wt%). The setting time was determined using a Vicat apparatus, solubility was assessed by calculating weight variation after water immersion, radiopacity was evaluated and expressed in millimeters of aluminum, the compressive strength was evaluated using an Instron testing machine, and the microhardness was measured with a Vickers microhardness tester. In addition, surface topography of specimens was analyzed using scanning electron microscopy, and the effect of chitosan on the viability of human embryonic kidney (HEK 293) cells was measured by a colorimetric MTT assay. RESULTS: Incorporation of 2.5 wt% and 5 wt% chitosan powder delivered an advantage by speeding up the setting time of Biodentine material. However, the incorporation of chitosan compromised all other material properties and the crystalline structure in a dose-dependent manner. The chitosan-modified material also showed significant decreases in the proliferation of the HEK 293 cells, signifying decreased biocompatibility. SIGNIFICANCE: Chitosan incorporation into calcium silicate materials adversely affects the physical and biological properties of the material. Despite the increased antimicrobial activity of the modified material, the diminution in these properties is likely to reduce its clinical value.

Addressing Healthcare Utilization and Costs for Older Adults with Limited Mobility Through a Multidisciplinary Home-Based Primary Care Program.

INTRODUCTION: Home-based primary care (HBPC) has shown promise in the management of multiple chronic conditions for patients who are homebound or who have limited mobility. The objective of this study was to implement and evaluate an HBPC program that integrates the services of clinical pharmacists and community aging services providers in a community-based setting. METHODS: Mountain Area Health Education Center's (MAHEC) HBPC program brought together an interdisciplinary team including medical providers, pharmacists, and community aging services providers to conduct home visits with older adults (age 50+). A single-arm, prepost analysis was conducted to determine differences from the year before program enrollment to the year postenrollment. We examined the frequency of health care visits, high-cost health care utilization (emergency department [ED] utilization and hospitalizations), and health care costs. Descriptive statistics characterized the study population and outcomes. Fisher's Exact Tests were used to determine if there was a significant difference between years. RESULTS: There were 130 home visits with 62 patients enrolled in the program. The Medicare Annual Wellness Visit (AWV) was completed for 32 (51.6%) patients. There were 13 (21.0%) and 12 (19.4%) individuals who had at least 1 ED visit and hospitalization, respectively, pre-enrollment as compared with 8 (12.9%) and 9 (14.5%) individuals postenrollment (p-value = 0.05, p-value = 0.06). During the postenrollment year, patient enrollees had an average per-member-per-month (PMPM) cost of $1567.96 as compared with $3053.21 in the year prior. CONCLUSIONS: Pharmacist and community agency services-integrated HBPC was implemented in the community setting. There was a decrease in high-cost health care utilization and total health care expenditures for patients as compared with the previous year.

Limitations of using 16S rRNA microbiome sequencing to predict oral squamous cell carcinoma.

A new era of next-generation sequencing has changed our perception of the oral microbiome in health and disease, and with this there is a growing understanding that the oral microbiome is a contributing factor to oral squamous cell carcinoma (OSCC), a malignancy of the oral cavity. This study aimed to analyse the trends and relevant literature based on the 16S rRNA oral microbiome in head and neck cancer using next-generation sequencing technologies, and to conduct a meta-analysis of the studies with OSCC cases and healthy controls. A literature search using the databases Web of Science and PubMed was conducted in a scoping-like review to collect information based on the study design, and plots were generated using RStudio. We selected case-control studies using 16S rRNA oral microbiome sequencing analysis in OSCC cases versus healthy controls for re-analysis. Statistical analyses were conducted using R. Out of 916 original articles, we filtered and selected 58 studies for review, and 11 studies for meta-analysis. Differences between sampling type, DNA extraction methods, next-generation sequencing technology and region of the 16S rRNA were identified. No significant differences in the α- and ß-diversity between health and oral squamous cell carcinoma were observed (p < 0.05). Random Forest classification marginally improved predictability of four studies (training set) when split 80/20. We found an increase in Selenomonas, Leptotrichia and Prevotella species to be indicative of disease. A number of technological advances have been accomplished to study oral microbial dysbiosis in oral squamous cell carcinoma. There is a clear need for standardization of study design and methodology to ensure 16S rRNA outputs are comparable across the discipline in the hope of identifying 'biomarker' organisms for designing screening or diagnostic tools.

Adrenal Ganglioneuroblastoma of Adult Onset: A Literature Review.

Ganglioneuroblastomas (GNBs) are a rare subtype of neoplastic tumors that arise from the autonomic nervous system and contain both mature gangliocytes and immature neuroblasts. The primary age group affected by GNBs is the pediatric population, with less than 50 cases of adult GNBs existing in the literature. To the authors' best knowledge, only 21 cases of GNBs arising in the adrenal glands of adults have been reported. Herein we present a literature review examining the symptoms, treatment type, age, and sex of adults, and the presence of tumor metastases and calcification from the 21 cases reported in the literature.

Acetylcholine Receptors in Mesenchymal Stem Cells.

Mesenchymal stem cells (MSCs) are well known for their regenerative potential. Even though the ability of MSCs to proliferate and differentiate has been studied extensively, there remains much to learn about the signaling mechanisms and pathways that control proliferation and influence the differentiation phenotype. In recent years, there has been growing evidence for the utility of non-neuronal cholinergic signaling systems and that acetylcholine (ACh) plays an important ubiquitous role in cell-to-cell communication. Indeed, cholinergic signaling is hypothesized to occur in stem cells and ACh synthesis, as well as in ACh receptor (AChR) expression, has been identified in several stem cell populations, including MSCs. Furthermore, AChRs have been found to influence MSC regenerative potential. In humans, there are two major classes of AChRs, muscarinic AChRs and nicotinic AChRs, with each class possessing several subtypes or subunits. In this review, the expression and function of AChRs in different types of MSC are summarized with the aim of highlighting how AChRs play a pivotal role in regulating MSC regenerative function.

The Positive Association of Plasma Levels of Vitamin C and Inverse Association of VCAM-1 and Total Adiponectin with Bone Mineral Density in Subjects with Diabetes.

CONTEXT: Population studies have shown a trend in decreasing vitamin C status and increasing prevalence of osteoporosis in patients with diabetes and non-diabetic people. Dietary vitamin C consumption is linked to improvement in bone mineral density (BMD) in epidemiological studies. VCAM-1 and adiponectin are known to activate osteoclasts, which increase bone loss. AIM: This study examined whether there is any association between the circulating level of vitamin C and BMD and whether the beneficial effect of vitamin C on BMD was linked to a simultaneous decrease in circulating levels of adiponectin and VCAM-1 in subjects with diabetes. METHODS: Patients with diabetes (T2D, n = 74) and age-matched non-diabetic controls (n = 26) were enrolled in this study. Fasting blood levels of glycemia, adiponectin, VCAM-1, inflammation biomarkers, and vitamin C were determined in both groups. The BMD of the lumbar spine (L1-L4), left femur, and right femur was determined using a DXA scan in subjects with diabetes. RESULTS: Patients with diabetes had lower levels of vitamin C and higher levels of VCAM-1 and inflammatory cytokines. There was a significant positive association between vitamin C blood levels and lumbar spine BMD as well as a significant negative association between total adiponectin and VCAM-1 levels with that of vitamin C and lumbar BMD in patients with diabetes. Total adiponectin and VCAM-1 also showed a negative association with BMD of both the right and left femurs. The inter-relationship among the circulating levels of vitamin C and VCAM-1 and BMD was strong and is a novel finding. CONCLUSIONS: This study reports a positive association of circulating vitamin C levels and the BMD and that the beneficial effects of vitamin C on BMD could be linked to a simultaneous lowering in circulating VCAM-1 and total adiponectin levels. Thus, dietary vitamin C consumption has potential to lower inflammation and the risk of osteoporosis in subjects with diabetes.

Meta-analysis of caries microbiome studies can improve upon disease prediction outcomes.

As one of the most prevalent infective diseases worldwide, it is crucial that we not only know the constituents of the oral microbiome in dental caries but also understand its functionality. Herein, we present a reproducible meta-analysis to effectively report the key components and the associated functional signature of the oral microbiome in dental caries. Publicly available sequencing data were downloaded from online repositories and subjected to a standardized analysis pipeline before analysis. Meta-analyses identified significant differences in alpha and beta diversities of carious microbiomes when compared to healthy ones. Additionally, machine learning and receiver operator characteristic analysis showed an ability to discriminate between healthy and disease microbiomes. We identified from importance values, as derived from random forest analyses, a group of genera, notably containing Selenomonas, Aggregatibacter, Actinomyces and Treponema, which can be predictive of dental caries. Finally, we propose the most appropriate study design for investigating the microbiome of dental caries by synthesizing the studies, which had the most accurate differentiation based on random forest modelling. In conclusion, we have developed a non-biased, reproducible pipeline, which can be applied to microbiome meta-analyses of multiple diseases, but importantly we have derived from our meta-analysis a key group of organisms that can be used to identify individuals at risk of developing dental caries based on oral microbiome inhabitants.

Screening the Tocriscreen™ bioactive compound library in search for inhibitors of Candida biofilm formation.

Biofilms formed by Candida species present a significant clinical problem due to the ineffectiveness of many conventional antifungal agents, in particular the azole class. We urgently require new and clinically approved antifungal agents quickly for treatment of critically ill patients. To improve efficiency in antifungal drug development, we utilized a library of 1280 biologically active molecules within the Tocriscreen 2.0 Micro library. Candida auris NCPF 8973 and Candida albicans SC5314 were initially screened for biofilm inhibitory activity using metabolic and biomass quantitative assessment methods, followed up by targeted evaluation of five selected hits. The initial screening (80% metabolic inhibition rate) revealed that there was 90 and 87 hits (approx. 7%) for C. albicans and C. auris, respectively. Additionally, all five compounds selected from the initial hits exhibited a biofilm inhibition effect against several key Candida species tested, including C. glabrata and C. krusei. Toyocamycin displayed the most potent activity at concentrations as low as 0.5 µg/mL, though was limited to inhibition. Darapladib demonstrated an efficacy for biofilm inhibition and treatment at a concentration range from 8 to 32 µg/mL and from 16 to 256 µg/mL, respectively. Combinational testing with conventional antifungals against C. albicans strains demonstrated a range of synergies for planktonic cells, and notably an anti-biofilm synergy for darapladib and caspofungin. Together, these data provide new insights into antifungal management possibilities for Candida biofilms.

Candida albicans and Enterococcus faecalis biofilm frenemies: When the relationship sours.

The opportunistic yeast Candida albicans and lactic acid bacteria Enterococcus faecalis are frequently co-isolated from various infection sites on the human body, suggesting a common interkingdom interaction. While some reports suggest an antagonism, the reason for their co-isolation therefore remains unclear. The purpose of this study was to undertake a detailed characterisation of this dual-species interaction. We used standard biofilm characterisation methodologies alongside an RNASeq analysis to assess the response of C. albicans to E. faecalis. We evaluated the relevance of pH to dual-species biofilm interactions and demonstrated that E. faecalis rapidly and significantly impacted C. albicans morphogenesis and biofilm formation, which was mirrored by levels of gene expression. These transcripts were enriched in amino acids biosynthesis and metabolism pathways in co-cultures, a finding that guided our investigation into pH related mechanism. We were able to demonstrate the direct role of E. faecalis induced low pH, which inhibited C. albicans hyphal morphogenesis and biofilm formation. The results suggest that the anti-candidal effect of E. faecalis is not based solely on a single mechanism, instead it may involve various mechanisms, which collectively reflects the complexity of interaction between C. albicans and E. faecalis and impacts treatment outcomes.

Small molecule based anti-virulence approaches against Candida albicans infections.

Fungi are considered "silent killers" due to the difficulty of, and delays in diagnosis of infections and lack of effective antifungals. This challenge is compounded by the fact that being eukaryotes, fungi share several similarities with human cellular targets, creating obstacles to drug discovery. Candida albicans, a ubiquitous microbe in the human body is well-known for its role as an opportunistic pathogen in immunosuppressed people. Significantly, C. albicans is resistant to all the three classes of antifungals that are currently clinically available. Over the past few years, a paradigm shift has been recommended in the management of C. albicans infections, wherein anti-virulence strategies are considered an alternative to the discovery of new antimycotics. Small molecules, with a molecular weight <900 Daltons, can easily permeate the cell membrane and modulate the signal transduction pathways to elicit desired virulence inhibitory actions against pathogens. This review dissects in-depth, the discoveries that have been made with small-molecule anti-virulence approaches to tackle C. albicans infections.

Chitosan Enhances the Anti-Biofilm Activity of Biodentine against an Interkingdom Biofilm Model.

Endodontic infection is a biofilm disease that is difficult to irradicate with current treatment protocols, and as such, persistent micro-organisms may lead to ongoing or recurrent disease. The potential for the use of enhanced filling materials to modify biofilm regrowth is a promising strategy. This current study aimed to evaluate the anti-biofilm efficacy of calcium silicate cements modified with chitosan. The development of mono-species and multi-species biofilms on ProRoot MTA, Biodentine and bovine dentine discs were explored using quantitative microbiology analysis. The effect on regrowth of biofilms was assessed following the addition of chitosan to each cement. In comparison to a dentine substrate, both materials did not show the ability to inhibit biofilm regrowth. Biodentine incorporated with chitosan displayed a dose-dependent reduction in multi-species biofilm regrowth, unlike MTA. Notably, interkingdom biofilms were shown to enhance bacterial tolerance in the presence of chitosan. This study demonstrates the potential to enhance the antimicrobial properties of Biodentine. The findings highlight the need for appropriate model systems when exploring antimicrobial properties of materials in vitro so that interspecies and interkingdom interactions that modify tolerance are not overlooked while still supporting the development of innovative materials.

Filling the Void: An Optimized Polymicrobial Interkingdom Biofilm Model for Assessing Novel Antimicrobial Agents in Endodontic Infection.

There is a growing realization that endodontic infections are often polymicrobial, and may contain Candida spp. Despite this understanding, the development of new endodontic irrigants and models of pathogenesis remains limited to mono-species biofilm models and is bacterially focused. The purpose of this study was to develop and optimize an interkingdom biofilm model of endodontic infection and use this to test suitable anti-biofilm actives. Biofilms containing Streptococcus gordonii, Fusobacterium nucleatum, Porphyromonas gingivalis, and Candida albicans were established from ontological analysis. Biofilms were optimized in different media and atmospheric conditions, prior to quantification and imaging, and subsequently treated with chlorhexidine, EDTA, and chitosan. These studies demonstrated that either media supplemented with serum were equally optimal for biofilm growth, which were dominated by S. gordonii, followed by C. albicans. Assessment of antimicrobial activity showed significant effectiveness of each antimicrobial, irrespective of serum. Chitosan was most effective (3 log reduction), and preferentially targeted C. albicans in both biofilm treatment and inhibition models. Chitosan was similarly effective at preventing biofilm growth on a dentine substrate. This study has shown that a reproducible and robust complex interkingdom model, which when tested with the antifungal chitosan, supports the notion of C. albicans as a key structural component.

Phase Change-Driven Negative Activation Energies in Pd/Carbon-Based/Organic Getter Hydrogenation Reactions.

The hydrogenation of 1,4-diphenylbutadiyne (DPB) blended with carbon-supported Pd (DPB-Pd/C) in the form of pellets was investigated by isothermal-isobaric experiments at 1333 Pa of H2 and in the temperature range of 291-315 K. The extracted kinetics were then used in conjunction with a complementary constant rate of H2 input experimentation to model the performance of a DPB-catalysis/support system as a function of temperature and H2 partial pressure. First-principles density functional theory (DFT) calculations were also performed to shed light on the molecular level energetics of DPB and its intermediate states. A seemingly puzzling formation of alternate positive activation energy barrier (higher reaction rate with higher temperature) and negative activation energy barrier (higher reaction rate with lower temperature) zones during the hydrogenation process was discovered. However, this observed phenomenon can be logically explained in terms of the associated phase changes and H2 transport in the material. This work provides a good illustration of a rarely encountered chemical process with a negative activation energy barrier.

Comparison of Three Endodontic Irrigant Regimens against Dual-Species Interkingdom Biofilms: Considerations for Maintaining the Status Quo.

Endodontic infections are often interkingdom biofilms, though current clinical management rarely considers this phenomenon. This study aimed to evaluate new and standard endodontic antimicrobial regimens against simple and complex Candida albicans and Enterococcus faecalis mono- and dual-species biofilms. C. albicans and E. faecalis mono- and dual-species biofilms were grown upon Thermanox™ coverslips and treated for 5 min with 3% NaOCl, 3% NaOCl followed by 17% EDTA, or 9% HEDP dissolved in 3% NaOCl. The number of cells remaining immediately after treatment at 0 h and after 72 h of regrowth were assessed using real-time quantitative PCR. All three treatment arms showed a similar positive antimicrobial effect on C. albicans and E. faecalis in both mono- and dual-species biofilms following initial treatment, resulting in ≥98% reduction in colony forming equivalent (CFE). Regardless of species or biofilm type (mono- or dual- species), the antimicrobial effect of NaOCl:HEDP mixture was comparable to that of NaOCl alone, with both showing significant regrowth after 72 h, whereas sequential treatment with NaOCl and EDTA consistently prevented significant regrowth. Our data suggest that sequential irrigation with NaOCl and EDTA remains the antimicrobial strategy of choice as it significantly reduces biofilm persistence and regrowth in our experimental dual-species biofilm conditions.

Detection, treatment and prevention of endodontic biofilm infections: what's new in 2020?

Endodontic disease, a biofilm infection of the root canal space, is a significant cause of dental morbidity worldwide. Endodontic treatment, or root canal treatment, as it is commonly known is founded on the ability to eradicate microbial biofilm infection and prevent re-infection of the highly complex root canal space. Despite many "advances" in clinical endodontics we have seen little improvement in outcomes. The aim of this critical review paper is to provide a contemporary view of endodontic microbiology and biofilm polymicrobiality, provide an understanding of the host response, and how together these impact upon clinical treatment. Ultimately, it is intended to provide insight into novel opportunities and strategies for the future diagnostics, treatment, and prevention of endodontic disease.

Moisture Corrosion of LiH: A Kinetic Investigation by DRIFT Spectroscopy.

Lithium hydride (LiH) is a unique, ionic compound with applications in a variety of industries. Unfortunately, LiH is very reactive toward H2O even at ppm levels, forming oxide (Li2O) and hydroxide (LiOH) corrosion layers while outgassing H2. An effective means to eliminate unwanted outgassing is vacuum-heating to convert LiOH into Li2O, although subsequent re-exposure to moisture during transport/handling reconverts some Li2O back to LiOH. A corrosion growth model for previously vacuum-baked LiH is necessary for long-term prediction of the hydrolysis of LiH. In this work, a para-linear hydroxide corrosion growth model is proposed for the reaction of previously vacuum-baked LiH samples with moisture. This model, composed of two competing diffusion reaction fronts at the LiOH/Li2O and Li2O/LiH interfaces, is validated experimentally by subjecting a previously vacuum-baked polycrystalline LiH sample to 35 ppm of H2O at room temperature while monitoring the corrosion growth as a function of time with diffuse-reflectance infrared Fourier transform (DRIFT) spectroscopy. The para-linear growth model for the hydrolysis of previously vacuum-baked LiH proposed in this report can also serve as a template for the hydrolysis of other hygroscopic oxides grown on metal or metal hydride substrates.

Hydrogen Uptake Kinetics of 1,4-Bis(phenylethynyl)benzene (DEB) Rubberized Coating on Silicone Foam Substrate.

The hydrogen uptake kinetics of 1,4-bis(phenylethynyl)benzene, or DEB, mixed with palladium (Pd) on activated carbon in a rubber matrix coating on top of a porous silicone foam substrate are investigated. First, isothermal isobaric hydrogenation experiments were performed under different temperatures and H2 pressures to extract the uptake kinetics. The H2 uptake models based on the measured kinetic parameters were then employed to investigate/simulate the performance of the getter under dynamic application environments. The actual hydrogenation characteristics in this type of getter are multifaceted and involve actual H2 concentration in the getter matrix, micrometer-scale diffusion of atomic hydrogen away from Pd sites, precipitation of hydrogenated DEB crystals at the coating surfaces, and mobility of fresh DEB molecules. The kinetic analysis/modeling methodology described in this report can serve as a template for other gas-solid reactions as well. Besides possessing a good hydrogen capacity and excellent performance, this type of rubberized getter also offers some unique advantages over traditional solid getter: flexible structure and protection of the Pd catalyst from exposure to the environment.

Candida albicans Biofilm Heterogeneity and Tolerance of Clinical Isolates: Implications for Secondary Endodontic Infections.

AIM: Endodontic infections are caused by the invasion of various microorganisms into the root canal system. Candida albicans is a biofilm forming yeast and the most prevalent eukaryotic microorganism in endodontic infections. In this study we investigated the ability of C. albicans to tolerate treatment with standard endodontic irrigants NaOCl (sodium hypochlorite), ethylenediaminetetraacetic acid (EDTA) and a combination thereof. We hypothesized that biofilm formed from a panel of clinical isolates differentially tolerate disinfectant regimens, and this may have implications for secondary endodontic infections. METHODOLOGY: Mature C. albicans biofilms were formed from 30 laboratory and oral clinical isolates and treated with either 3% NaOCl, 17% EDTA or a sequential treatment of 3% NaOCl followed by 17% EDTA for 5 min. Biofilms were then washed, media replenished and cells reincubated for an additional 24, 48 and 72 h at 37 °C. Regrowth was quantified using metabolic reduction, electrical impedance, biofilm biomass and microscopy at 0, 24, 48 and 72 h. RESULTS: Microscopic analysis and viability readings revealed a significant initial killing effect by NaOCl, followed by a time dependent significant regrowth of C. albicans, but with inter-strain variability. In contrast to NaOCl, there was a continuous reduction in viability after EDTA treatment. Moreover, EDTA significantly inhibited regrowth after NaOCl treatment, though viable cells were still observed. CONCLUSIONS: Our results indicate that different C. albicans biofilm phenotypes grown in a non-complex surface topography have the potential to differentially tolerate standard endodontic irrigation protocols. This is the first study to report a strain dependent impact on efficacy of endodontic irrigants. Its suggested that within the complex topography of the root canal, a more difficult antimicrobial challenge, that existing endodontic irrigant regimens permit cells to regrow and drive secondary infections.

Filaggrin gene loss-of-function mutations constitute a factor in patients with multiple contact allergies.

BACKGROUND: Polysensitivity is defined as three or more positive patch test reactions. The role of filaggrin gene (FLG) loss-of-function mutations in patients with polysensitivity has not been studied when barrier bypass and possible preceding barrier damage have been excluded. OBJECTIVES: To determine whether FLG loss of function mutations play a role in patients with multiple contact sensitivities when barrier bypass is excluded. METHODS: One hundred and sixty-nine patients with three or more, non-cross-reacting, positive patch test reactions were prospectively enrolled in this study. Exclusion criteria were a history of hand dermatitis, nickel and metal implants, and stasis dermatitis. Subjects were patch tested with the North American extended patch test series, and with other relevant haptens. DNA was obtained and sequenced for the following FLG loss-of-function mutations: R501X, 2282del4, R2447X, and S3247X. RESULTS: One hundred and sixty-five patients were genotyped for the four FLG mutations. There was a significant association between R501X mutation and polysensitivity. For the other three tested mutations, there were no significant associations with polysensitivity. When all mutations were combined, there was a significant association between loss-of-function FLG mutations and polysensitivity in patients with a history of atopic dermatitis. CONCLUSION: When skin barrier bypass is excluded, there is a significant association between polysensitivity and FLG loss-of-function mutations.