Porphyromonas gingivalis outer membrane vesicles modulate cytokine and chemokine production by gingipain-dependent mechanisms in human macrophages.

OBJECTIVE: The aim was to determine the changes of inflammatory mediator expression in human macrophages stimulated with outer membrane vesicles purified from Porphyromonas gingivalis. DESIGN: outer membrane vesicles purified by ultracentrifugation from ATCC 33277 and W83 P. gingivalis strains were used for stimulating human macrophages and determine their inflammatory mediator expression changes. U937 monocyte cells line were differentiated into macrophages and stimulated with outer membrane vesicles for 30 min and six hours. In Independent experiments, the outer membrane vesicles and viable bacteria control were pre-treated with the gingipain inhibitors KYT-1 and KYT-36 (Arg-gingipain and Lys-gingipain, respectively) or Polymyxin-B to block the lipopolysaccharide activity to evaluate the secretion changes of immune mediators IL-1ß, IL-6, TNF-α, IL-8, MCP-1, MIP-1α and RANTES by flow cytometry. A factorial ANOVA was used to analyze the data. RESULTS: The outer membrane vesicles of P. gingivalis ATCC 33277 displayed higher Arg-gingipain activity than those obtained from the P. gingivalis W83 strain (0.6 U/µg vs. 0.46 U/µg). Although the outer membrane vesicles of P. gingivalis stimulated the production of cytokines and chemokines, specific Arg-gingipain and Lys-gingipain inhibition induced significant increases in IL-1ß, IL-6, IL-8, MCP-1, and RANTES levels, and this induction was significantly greater at 6 h compared to 30 min (*p < 0.05). On the contrary, TNF-α secretion decreased when gingipains were blocked. CONCLUSIONS: outer membrane vesicles may play a dual role during P. gingivalis infection based on their ability to induce changes in the immune responses of human macrophages, probably via gingipain-dependent events.

Dentists' Perceptions of Personal Infection Control Measurements in Response to COVID-19.

OBJECTIVE: To explore through focus groups (FGs) the perceptions of dental practitioners (DPs) from different countries of the challenges of implementing coronavirus disease 2019 (COVID-19) related biosafety measures, especially personal protection equipment (PPE), during the COVID-19 pandemic period. METHODS: DPs from Colombia, Germany, the United Kingdom, and the United States were invited to participate in country-based FGs. These were facilitated by an experienced moderator who explored the factors that guided the implementation of COVID-19 related biosafety measures and PPE use. Data were analyzed through thematic analysis on the basis of categories defined by the researchers deductively and inductively. RESULTS: A total of 25 DPs participated in 3 FGs (Colombia:n = 8; United Kingdom: n = 7; United States: n = 9) and 1 in an in-depth interview (Germany). DPs described using several processes to judge which guidance document to adopt and which aspects of the guidance were important in their practice. These included making judgments concerning the views of any indemnity organization to which the DPs were responsible, the staff's views in the practice, and the views of patients. In the absence of a single overarching guidance document, DPs filtered the available information through several considerations to find a level of PPE that they deemed "implementable" in local practice. CONCLUSIONS: The findings suggest that the implementation of evidence-based practice is subject to modification through a lens of what is "feasible" in practice. KNOWLEDGE TRANSFER STATEMENT: Clinicians, educators, and policy makers can use the results of this study to understand the process through which guidance is transformed into implementable patient care pathways in the dental practice.

Resin-Dentin Bonding Interface: Mechanisms of Degradation and Strategies for Stabilization of the Hybrid Layer.

Several studies have shown that the dentin-resin interface is unstable due to poor infiltration of resin monomers into the demineralized dentin matrix. This phenomenon is related to the incomplete infiltration of the adhesive system into the network of exposed collagen fibrils, mainly due to the difficulty of displacement and subsequent replacement of trapped water between interfibrillar spaces, avoiding adequate hybridization within the network of collagen fibrils. Thus, unprotected fibrils are exposed to undergo denaturation and are susceptible to cyclic fatigue rupture after being subjected to repetitive loads during function. The aqueous inclusions within the hybrid layer serve as a functional medium for the hydrolysis of the resin matrix, giving rise to the activity of esterases and collagenolytic enzymes, such as matrix metalloproteinases, which play a fundamental role in the degradation process of the hybrid layer. Achieving better interdiffusion of the adhesive system in the network of collagen fibrils and the substrate stability in the hybrid layer through different strategies are key events for the interfacial microstructure to adequately function. Hence, it is important to review the factors related to the mechanisms of degradation and stabilization of the hybrid layer to support the implementation of new materials and techniques in the future. The enzymatic degradation of collagen matrix, together with resin leaching, has led to seeking strategies that inhibit the endogenous proteases, cross-linking the denudated collagen fibrils and improving the adhesive penetration removing water from the interface. Some of dentin treatments have yielded promising results and require more research to be validated. A longer durability of adhesive restorations could resolve a variety of clinical problems, such as microleakage, recurrent caries, postoperative sensitivity, and restoration integrity.

Description of high rates of unapparent and simultaneous multiple dengue virus infection in a Colombian jungle settlement.

Dengue disease statistics is mainly based on consulting patients with febrile illness, but misdiagnosed and asymptomatic cases are important to measure dengue epidemiology in endemic areas. The main objective of this work was to determine the prevalence of IgM and IgG antibodies or NS1 antigen and viral RNA in a group of healthy volunteers from an isolated village in Colombian Chocó rain forest. It found 51.7% of virologically PCR confirmed asymptomatic cases, despite low IgM seroprevalence. It was confirmed that all four serotypes are in the circulation and in 17.2% of individuals it detected natural coinfections of two or three different serotypes simultaneously. This is the first report in Colombia evaluating viremia in asymptomatic volunteers. These findings pose a big concern about the transmission of dengue virus by asymptomatic individuals because they can spread the virus without take appropriate control measures.

Nerve growth factor and neurotrophin-3 modulate the rabies infection of adult sensory neurons in primary cultures.

With the aim of determining if the proportion of rabies virus (RV)-infected adult neurons from dorsal root ganglion are affected by in vitro treatment with different neurotrophins, experiments using Nerve Growth Factor (NGF), Brain Derived Neurotrophic Factor (BDNF) or Neurotrophin-3 (NT-3) as supplements for cells in culture were performed. Cultures treated with three different concentrations of each of the neurotrophins mentioned were infected with Challenge Virus Standard RV strain. An indirect immunoperoxidase technique was performed for the detection and counting of infected cells. NGF (2 ngml(-1) and 10 ngml(-1)) and NT-3 (1 ngml(-1) and 5 ngml(-1)) induced a significant reduction of infected neurons. None of the cultures treated with BDNF showed changes in the percentage of infected neurons. Likewise, the proportion of infected non-neuronal cells (Schwann cells and fibroblasts) was not altered by the treatment with neurotrophins. In addition, morphometric analysis of total and virus-immunoreactive neurons in culture were carried out, the neurotrophin treatment induced variations in the profile of neurons preferentially infected, since cell diameters in the infected cell population are different in the presence of NGF and NT-3. Data presented here could indicate a putative participation of neurotrophin receptor or biochemical modifications induced by neurotrophin treatment that affect the infection. The primary culture of dorsal root ganglion cells from adult mice is a very useful model for studying the basic phenomena of the RV-neuron interaction.

Partial inhibition of the in vitro infection of adult mouse dorsal root ganglion neurons by rabies virus using nicotinic antagonists.

The infection of target cells by rabies virus is effected through membrane receptors. Several authors have suggested that nicotinic receptors could be used by this virus, but no direct experimental evidence is available. In this study mouse dorsal root ganglia cells were treated with various nicotinic antagonists (dihydro-beta-eritroidine, mecamilamine, d-tubocurarin, hexametonium, alpha-bungarotoxin and erabutoxin). After incubation, the cultures were infected with rabies virus. Cells were fixed, and processed for immunodetection of rabies virus. Treatment with mecamilamine or d-tubocurarine reduced the percentage of infected neurons. None of the antagonists tested changed the percentage of infected non-neuronal cells.

Description of high rates of unapparent and simultaneous multiple dengue virus infection in a Colombian jungle settlement

Dengue disease statistics is mainly based on consulting patients with febrile illness, but misdiagnosed and asymptomatic cases are important to measure dengue epidemiology in endemic areas. The main objective of this work was to determine the prevalence of IgM and IgG antibodies or NS1 antigen and viral RNA in a group of healthy volunteers from an isolated village in Colombian Chocó rain forest. It found 51.7% of virologically PCR confirmed asymptomatic cases, despite low IgM seroprevalence. It was confirmed that all four serotypes are in the circulation and in 17.2% of individuals it detected natural coinfections of two or three different serotypes simultaneously. This is the first report in Colombia evaluating viremia in asymptomatic volunteers. These findings pose a big concern about the transmission of dengue virus by asymptomatic individuals because they can spread the virus without take appropriate control measures.