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Coronavirus disease-2019 (COVID-19) is primarily a respiratory disease, however, an increasing number of reports indicate that SARS-CoV-2 infection can also cause severe neurological manifestations, including precipitating cases of probable Parkinson's disease. As microglial NLRP3 inflammasome activation is a major driver of neurodegeneration, here we interrogated whether SARS-CoV-2 can promote microglial NLRP3 inflammasome activation. Using SARS-CoV-2 infection of transgenic mice expressing human angiotensin-converting enzyme 2 (hACE2) as a COVID-19 pre-clinical model, we established the presence of virus in the brain together with microglial activation and NLRP3 inflammasome upregulation in comparison to uninfected mice. Next, utilising a model of human monocyte-derived microglia, we identified that SARS-CoV-2 isolates can bind and enter human microglia in the absence of viral replication. This interaction of virus and microglia directly induced robust inflammasome activation, even in the absence of another priming signal. Mechanistically, we demonstrated that purified SARS-CoV-2 spike glycoprotein activated the NLRP3 inflammasome in LPS-primed microglia, in a ACE2-dependent manner. Spike protein also could prime the inflammasome in microglia through NF-κB signalling, allowing for activation through either ATP, nigericin or α-synuclein. Notably, SARS-CoV-2 and spike protein-mediated microglial inflammasome activation was significantly enhanced in the presence of α-synuclein fibrils and was entirely ablated by NLRP3-inhibition. Finally, we demonstrate SARS-CoV-2 infected hACE2 mice treated orally post-infection with the NLRP3 inhibitory drug MCC950, have significantly reduced microglial inflammasome activation, and increased survival in comparison with untreated SARS-CoV-2 infected mice. These results support a possible mechanism of microglial innate immune activation by SARS-CoV-2, which could explain the increased vulnerability to developing neurological symptoms akin to Parkinson's disease in COVID-19 infected individuals, and a potential therapeutic avenue for intervention.
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COVID-19 , Doença de Parkinson , Humanos , Camundongos , Animais , Inflamassomos/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Microglia/metabolismo , alfa-Sinucleína/metabolismo , SARS-CoV-2 , Glicoproteína da Espícula de Coronavírus/metabolismo , COVID-19/metabolismo , Camundongos TransgênicosRESUMO
Amyotrophic lateral sclerosis (ALS) is a fatal and rapidly progressing motor neuron disease without effective treatment. Although the precise mechanisms leading to ALS are yet to be determined, there is now increasing evidence implicating components of the innate immune complement system in the onset and progression of its motor phenotypes. This review will survey the clinical and experimental evidence for the role of the complement system in driving neuroinflammation and contributing to ALS disease progression. Specifically, it will explore findings regarding the different complement activation pathways involved in ALS, with a focus on the terminal pathway. It will also examine potential future research directions for complement in ALS, highlighting the targeting of specific molecular components of the system.
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Esclerose Lateral Amiotrófica/imunologia , Proteínas do Sistema Complemento/metabolismo , Imunidade Inata/fisiologia , Esclerose Lateral Amiotrófica/metabolismo , Animais , HumanosRESUMO
OBJECTIVE: Tissue conditioners are composed of poly(ethyl methacrylate) (PEMA) powder and plasticizer/ethanol mix liquid. Butyl phthalyl butyl glycolate (BPBG) plasticizer is commonly used in tissue conditioners, but the main concern with phthalate plasticizer is its leachability and biocompatibility, especially the estrogenic activity and cytotoxicity of phthalate. Therefore, acetyl tributyl citrate (ATBC) plasticizer has been introduced and formulated as plasticizer in tissue conditioner; however its leachability characteristics are still unknown. Furthermore, the effect of foodsimulating liquids toward leachability of BPBG and ATBC plasticizers has not been documented. The objective of this study was to compare the effect of food-simulating liquids on the leachability of plasticizers and hardness of two experimental tissue conditioners containing BPBG and ATBC plasticizers. MATERIALS AND METHODS: Ten experimental materials were prepared using PEMA polymer powder with 95% plasticizer (BPBG and ATBC) and 5% ethanol by volume, using powder to liquid ratio of 1.67:1, and the thickness was controlled at 3 mm. Shore A hardness value was measured after immersion in distilled water, artificial saliva, 25% ethanol/water mix, 3% citric acid, and coconut oil at 37°C. Measurements were taken at 2 hours and 1, 2, 3, 4, 7, 10, 14, 21, 28, 42, 56, and 84 days. Six readings were taken for each sample and hardness change was calculated and statistically analyzed using Wilcoxon signed-rank test. RESULTS: Increase in hardness value was noted for both plasticizers over time with the highest increase was when immersed in coconut oil. Shore A hardness value was significantly higher in ATBC after 84 days of immersion in all food-simulating liquids. The increase in hardness is due to plasticizer/ethanol leaching; however, as ethanol content was the same (5%), the hardness change is attributed to the leaching of plasticizers. CONCLUSION: Leaching of both plasticizers was highest in coconut oil indicating that tissue conditioners may have a shorter intraoral lifetime in patients eating high-fat diet.
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Background: Accumulating evidence underscores the pivotal role of heightened inflammation in the pathophysiology of stress-related diseases, but the underlying mechanisms remain elusive. The complement system, a key effector of the innate immune system, produces the C5-cleaved activation product C5a upon activation, initiating inflammatory responses through the canonical C5a receptor 1 (C5aR1). While C5aR1 is expressed in stress-responsive brain regions, its role in stress responsiveness remains unknown. Methods: To investigate C5a-C5aR1 signaling in stress responses, mice underwent acute and chronic stress paradigms. Circulating C5a levels and messenger RNA expression of C5aR1 in the hippocampus and adrenal gland were measured. C5aR1-deficient mice were used to elucidate the effects of disrupted C5a-C5aR1 signaling across behavioral, hormonal, metabolic, and inflammation parameters. Results: Chronic restraint stress elevated circulating C5a levels while reducing C5aR1 messenger RNA expression in the hippocampus and adrenal gland. Notably, the absence of C5aR1 signaling enhanced adrenal sensitivity to adrenocorticotropic hormone, concurrently reducing pituitary adrenocorticotropic hormone production and enhancing the response to acute stress. C5aR1-deficient mice exhibited attenuated reductions in locomotor activity and body weight under chronic stress. Additionally, these mice displayed increased glucocorticoid receptor sensitivity and disrupted glucose and insulin homeostasis. Chronic stress induced an increase in C5aR1-expressing microglia in the hippocampus, a response mitigated in C5aR1-deficient mice. Conclusions: C5a-C5aR1 signaling emerges as a key metabolic regulator during stress, suggesting that complement activation and dysfunctional C5aR1 signaling may contribute to neuroinflammatory phenotypes in stress-related disorders. The results advocate for further exploration of complement C5aR1 as a potential therapeutic target for stress-related conditions.
How the immune system, particularly the complement system, influences responses to stress has not been fully clear. In this study, we focus on C5a-C5aR1 signaling, a part of the immune system, and found that it significantly affects stress-related reactions in mice. In chronic stress, we observed increased inflammation, altered hormonal responses, and disrupted metabolic regulation. Mice lacking C5aR1 showed reduced stress-induced behavioral changes, indicating that this receptor may play a vital role in modulating the stress response. Understanding these immune mechanisms sheds light on stress-related disorders and may open avenues for therapeutic interventions.
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As the Southern Ocean cooled to -1.8 °C over the past 40 My, the teleostean clade Notothenioidei diversified and, under reduced selection pressure for an oxygen-transporting apparatus, became less reliant on hemoglobin and red blood cells. At the extreme of this trend, the crown group of Antarctic icefishes (Channichthyidae) lost both components of oxygen transport. Under the decreased selection scenario, we hypothesized that the Antarctic dragonfishes (Bathydraconidae, the red-blooded sister clade to the icefishes) evolved lower blood hemoglobin concentrations because their globin gene complexes (α- and ß-globin gene pairs linked by a regulatory intergene) transcribe globin mRNAs less effectively than those of basal notothenioids (e.g., the Nototheniidae [notothens]). To test our hypothesis, we 1) sequenced the α/ß-intergenes of the adult globin complexes of three notothen and eight dragonfish species and 2) measured globin transcript levels in representative species from each group. The typical nototheniid intergene was â¼3-4 kb in length. The bathydraconid intergenes resolved into three subclasses (long [3.8 kb], intermediate [3.0 kb], and short [1.5-2.3 kb]) that corresponded to the three subclades proposed for the taxon. Although they varied in length due to indels, the three notothen and eight dragonfish intergenes contained a conserved â¼90-nt element that we have previously shown to be required for globin gene transcription. Using the quantitative polymerase chain reaction, we found that globin mRNA levels in red cells from one notothen species and from one species of each dragonfish subclade were equivalent statistically. Thus, our results indicate that the bathydraconids have evolved adult globin loci whose regulatory intergenes tend to be shorter than those of the more basal nototheniids yet are equivalent in transcriptional efficacy. Their low blood hemoglobin concentrations are most likely due to reduction in hematocrit.
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Adaptação Biológica/genética , DNA Intergênico/genética , Evolução Molecular , Globinas/genética , Perciformes/genética , Sequências Reguladoras de Ácido Nucleico/genética , Animais , Sequência de Bases , Cromossomos Artificiais Bacterianos/genética , Clonagem Molecular , Perfilação da Expressão Gênica , Globinas/metabolismo , Dados de Sequência Molecular , Análise de Sequência de DNA , Especificidade da EspécieRESUMO
Once widely considered an immune-privileged organ, the brain is now known to be intimately intertwined with immune-system activation. In particular, the complement system, an enzymatic cascade conferring innate immunity, has crucial functions for several neurodevelopmental and neuromigratory mechanisms. Recent advances have demonstrated the neurological importance of complement activation in the adult brain, whereby phagocytosis of weakened synapses biologically encodes "forgetting" of information through complement activation. Neurophysiologically, complement factors can also influence the brain's computational processes, increasing neuronal calcium influx and neurotransmitter release and altering synaptic strength. The complement system's effects on synaptic connectivity can also be observed in many pathological conditions including epilepsy, schizophrenia, and viral-induced cognitive deficits, where perturbations of complement-stimulated synaptic remodelling lead to severe dysfunction. In this review we provide an overview of current knowledge for complement in neurodevelopment, and examine recent evidence highlighting a critical physiological role of complement in the plasticity of the adult brain. This is especially relevant due to the explosion of complement-targeted therapeutics in clinical trials to treat neurological disorders.
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Proteínas do Sistema Complemento , Epilepsia , Encéfalo , Humanos , Plasticidade Neuronal/fisiologia , Neurônios , Sinapses/patologiaRESUMO
PURPOSE: To determine the hardness and Young's moduli of both commercial and experimental vinyl poly siloxane (VPS). METHODS: The purpose of this study was to develop a medium-bodied experimental (Exp-I, II, III, IV, and V) VPS impression materials and to analyse their effects on hardness and Young's modulus and compare them with three commercial VPS materials (Aquasil, Elite, and Extrude) using Shore A hardness tester. Measurements were recorded after 1, 24, 72, and 168 hours of mixing. The results were analysed with one-way ANOVA and post hoc Tukey's test using the SPSS PASW statistical 22 software. RESULTS: Commercial and experimental vinyl polysiloxane exhibited higher Shore A hardness values with time (i.e., 1 hour after mixing, 24 hours after mixing, 72 hours after mixing, and 1 week after mixing). All Comml and Exp VPS demonstrated a significant increase (ANOVA, p < 0.05) in hardness at increasing time points. Generally, all commercial VPS exhibited significantly higher values for Shore A hardness compared to all Exp formulations. For commercial products, Elt M presented significantly highest values at all-time points followed by Aq M then Extr M. Exp-I was significantly harder than all other Exp VPS at all-time points. Young's modulus values were directly related to Shore A hardness; materials with higher Shore A hardness values had higher Young's moduli. CONCLUSION: Continued polymerisation of elastomeric impression materials results in increased hardness over time. Hardness, Young's moduli, and rigidity of the set commercial and experimental VPS materials were within the required limits. Shore A hardness and Young's moduli were directly proportional to each other, and commercial and experimental materials had enough rigidity to contain the stone during pouring.
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Materiais para Moldagem Odontológica/química , Polivinil/química , Siloxanas/química , Módulo de Elasticidade , Dureza , Teste de Materiais , Elastômeros de SiliconeRESUMO
OBJECTIVES: One hundred years after the Flexner report remade medical education in North America, many countries are reviewing the purpose and organisation of medical education. In Canada, a national study is being undertaken to define important issues and challenges for the future of medical education. The objectives of this paper are to describe the process of conducting an empirical environmental scan at a national level, and to present the research findings of this scan. METHODS: Thirty national key informant interviews were conducted, transcribed and coded to identify key themes. Interview data were triangulated with data sourced from 34 commissioned literature reviews and a series of national focus groups. RESULTS: Ten key issues or priorities were identified and used to generate detailed review papers used by the Association of Faculties of Medicine of Canada to create a blueprint for the evolution of medical education. The new priorities have major implications for areas ranging from admissions, curriculum content, educational process and the need to articulate the purpose and responsibilities of medical schools in society. DISCUSSION: This research provides a case study of how an empirical research approach can be used to identify and validate priorities for changes in medical education at a national level. This approach may be of interest in other countries.
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Currículo/tendências , Educação Médica/tendências , Canadá , Feminino , Previsões , Humanos , Masculino , Literatura de Revisão como Assunto , Fatores SocioeconômicosRESUMO
OBJECTIVES: To study the effects of incorporating a further crosslinking agent and a novel surfactant on the water absorption behaviour of experimental VPS impression materials. METHODS: Part 1: The water uptake behaviour of Aquasil-Ultra-Monophase (AqM) was studied gravimetrically in three media (DW, 1%NaOCl and Perform ID), at 23 °C and 37 °C, over a period of one and four-months (n = 5) to gain information on long-term immersion. Part 2: Five experimental materials were formulated: Exp-I and II as hydrophobic and Exp-III-V as hydrophilic, containing an additional cross-linking agent (TFDMSOS) and Rhodasurf CET-2 surfactant. Their water uptake and desorption (both at 23 °C) properties (gravemetrically), solubility, pH and diffusion coefficient (DC) data were compared with three commercial, hydrophilic VPS impression materials, over seven days (n = 5). The results were analysed statistically. RESULTS: Part 1: Significant differences in water absorbed by AqM were observed in the three media at 23 °C. Aq M had a significantly higher uptake in 2% Perform ID, than in DW and NaOCl. At 37 °C, over four-months the uptake profiles were more enhanced and differed. Part 2: All Exp and commercial materials significantly increased in weight in both media (DW and 1% NaOCl at 23 °C), with differing uptake profiles and non-reached equilibrium. Exp-VPS absorbed significantly less water than commercial-VPS. Desorption of all VPS from both parts was faster than absorption, followed Fickian diffusion kinetics and reached equilibrium within 1-3 days. Desorption DCs for Exp-VPS were higher than commercial materials (10-10 versus 10-11 m2 s-1). The solubility was higher in 1% NaOCl compared to DW. The pH of DW after immersion of samples significantly increased compared to 1% NaOCl. SIGNIFICANCE: The incorporation of novel cross-linking agent, TFDMSOS and non-ionic surfactant, Rhodasurf CET-2, (ethoxylated-cetyl-oleyl alcohol) improved the dimensional stability of hydrophilic Exp-VPS in DW and 1% NaOCl. These materials merit further research in producing accurate casts of the patient's anatomy following disinfection.
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Tensoativos , Água , Materiais para Moldagem Odontológica , Humanos , Interações Hidrofóbicas e Hidrofílicas , Teste de Materiais , Polivinil , SiloxanasRESUMO
OBJECTIVE: Resin-modified glass ionomer cements (RMGICs) present several advantages (e.g. fluoride release), but their reported cytotoxicity has been associated with hydroxyethyl methacrylate (HEMA) monomer release. Therefore, different monomers were tested for use in RMGICs in order to improve their biocompatibility and reduce monomer release. METHODS: Eight experimental liquid compositions were prepared replacing different percentages of HEMA (conventional monomer used in commercial RMGICs) with hydroxypropyl-methacrylate (HPM) and/or tetrahydrofurfuryl-methacrylate (THFM), which are known to have better biocompatibility. Moreover, two commercial materials (Fuji-Plus and RelyX) and two compositions, based on these (home), were included as controls. Monomer release of all materials (commercial, home and experimental) were tested using high-performance liquid chromatography (HPLC) methods after immersing discs in deionized-water (DW) or ethanol:DW. Cytotoxicity of the materials extracts was tested on normal human oral fibroblast line (NHOF-1) using 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) assay. RESULTS: Three experimental materials containing THFM (F3, R3 and R4) showed less or similar monomer release compared to corresponding commercial products. Furthermore, two experimental materials (F3 and F4) showed similar effects on NHOF-1 cells compared to the negative control medium. SIGNIFICANCE: The lower monomer release and higher cell viability of some experimental THFM compositions are encouraging. THFM partially replacing HEMA is potentially a suitable alternative for producing biocompatible RMGICs.
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Cimentos de Ionômeros de Vidro , Cimentos de Resina , Cimentos de Ionômeros de Vidro/toxicidade , Humanos , Teste de Materiais , Metacrilatos/toxicidadeRESUMO
The perciform suborder Notothenoidei provides a compelling opportunity to study the adaptive radiation of a marine species flock in the cold Southern Ocean surrounding Antarctica. To enable genome-level studies of these psychrophilic fishes, we estimated the sizes of the genomes of 11 Antarctic species and generated high-quality BAC libraries for 2, the notothen Notothenia coriiceps and the icefish Chaenocephalus aceratus. Our results indicate that evolution of phylogenetically derived notothenioid families, [e.g., the icefishes (Channichthyidae)], was accompanied by genome expansion. Species (n=6) of the basal family Nototheniidae had C values that ranged between 0.98 and 1.20 pg, whereas those of the icefishes, the notothenioid crown group, were 1.66-1.83 pg (n=4 species). The BAC libraries VMRC-19 (N. coriiceps) and VMRC-21 (C. aceratus) comprised 12X and 10X coverage of the respective genomes and had average insert sizes of 138 and 168 kb. Greater than 60% of paired BAC ends sampled from each library ( approximately 0.1% of each genome) contained repetitive sequences, and the repetitive element landscapes of the 2 genomes (13.4% of the N. coriiceps genome and 14.5% for C. aceratus) were similar. The representation and depth of coverage of the libraries were verified by identification of multiple Hox gene contigs: six discrete Hox clusters were found in N. coriiceps and at least five Hox clusters were found in C. aceratus. Given the unusual anatomical and physiological adaptations of the notothenioids, the availability of these BAC libraries sets the stage for expanded analysis of the psychrophilic mode of life.
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Cromossomos Artificiais Bacterianos , Genoma , Animais , DNA/química , Citometria de Fluxo , Peso Molecular , Especificidade da EspécieRESUMO
OBJECTIVES: Tetrahydrofurfuryl-methacrylate (THFM) and hydroxypropyl-methacrylate (HPM) were used to partially or fully replace HEMA in experimental RMGICs. The experimental materials were compared with home and commercial products in terms of degree of conversion, polymerization shrinkage and exotherm. METHODS: Two commercial RMGICs used were Fuji-Plus (FP, GC, Japan) and RelyX-Luting (RX, 3M-ESPE, USA). Two additional in-house liquids were prepared based on the commercial materials liquids. Eight experimental liquid compositions (F1, F2, F3 and F4 based on Fuji-Plus; R1, R2, R3 and R4 based on RelyX-Luting) were prepared replacing 100% HEMA with HPM in F1 and R1 or 70%/30% HPM/THFM in F2 and R2. 50% HEMA was replaced with THFM in F3 and R3 compared to 30% in F4 and R4. All liquids were mixed with the corresponding commercial powder. Degree of conversion was determined using Fourier-transform infrared spectroscopy (FT-IR). Polymerization shrinkage and exotherm were measured using the bonded-disk method. RESULTS: Compositions containing HPM (F1 and R1) showed lower degree of conversion compared to experimental compositions containing THFM, home and commercial materials (p<0.0001). FP-commercial showed significantly higher polymerization shrinkage and exotherm compared to all other materials in both groups (p<0.0001). FP-commercial showed higher degree of polymerization shrinkage and exotherm at 5min compared to all materials due to the incorporation of an additional cross-linker (glycerol-dimethacrylate). In general, compositions containing THFM, presented polymerization shrinkage and degree of conversion values similar to their corresponding commercial products. SIGNIFICANCE: THFM monomer showed promising results and could be potentially useful in the development of new RMGICs with improved properties.
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Cimentos de Ionômeros de Vidro , Cimentos de Resina , Resinas Acrílicas , Resinas Compostas , Cinética , Teste de Materiais , Metacrilatos , Polimerização , Dióxido de Silício , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
The provision of timely and optimal patient care is a priority in pediatric academic health science centres. Timely access to care is optimized when there is an efficient and consistent referral system in place. In order to improve the patient referral process and, therefore, access to care, an innovative web-based system was developed and implemented. The Ambulatory Referral Management System enables the electronic routing for submission, review, triage and management of all outpatient referrals. The implementation of this system has provided significant metrics that have informed how processes can be improved to increase access to care. Use of the system has improved efficiency in the referral process and has reduced the work associated with the previous paper-based referral system. It has also enhanced communication between the healthcare provider and the patient and family and has improved the security and confidentiality of patient information management. Referral guidelines embedded within the system have helped to ensure that referrals are more complete and that the patient being referred meets the criteria for assessment and treatment in an ambulatory setting. The system calculates and reports on wait times, as well as other measures.
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Difusão de Inovações , Hospitais Pediátricos , Encaminhamento e Consulta/organização & administração , Canadá , Sistemas de Apoio a Decisões Clínicas/organização & administração , Eficiência Organizacional , Guias como Assunto , Acessibilidade aos Serviços de SaúdeRESUMO
Interspecific hybridization or barriers to hybridization may have contributed to the diversification of Antarctic icefishes (Channichthyidae), but data supporting these hypotheses is scarce. To understand the potential for hybridization and to investigate reproductive isolating mechanisms among icefish species, we performed in vitro fertilization experiments using eggs from a female blackfin icefish Chaenocephalus aceratus and sperm from a male of another genera, the ocellated icefish Chionodraco rastrospinosus. Sequencing of genomic and mitochondrial DNA confirmed the intergeneric hybrid nature of resulting embryos which successfully developed and hatched as active larvae at about four and a half months during the Antarctic winter. This result demonstrates the compatibility of gametes of these two species and the viability of resulting zygotes and larvae. Due to logistic constraints and the slow developmental rate of icefishes, we could not test for long-term hybrid viability, fertility, fitness, or hybrid breakdown. Analysis of our fishing records and available literature, however, suggests that the strongest barriers to hybridization among parapatric icefish species are likely to be behavioral and characterized by assortative mating and species-specific courtship and nesting behaviors. This conclusion suggests that, in long-lived fish species with late sexual maturity and high energetic investment in reproduction like icefishes, pre-mating barriers are energetically more efficient than post-mating barriers to prevent hybridization.
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Hibridização Genética , Perciformes/genética , Isolamento Reprodutivo , Animais , Ecossistema , Perciformes/fisiologiaRESUMO
OBJECTIVES: To formulate experimental hydrophobic and hydrophilic vinyl polysiloxane (VPS) impression materials ab initio, comprising a novel cross-linking agent, tetra-functional (dimethylsilyl) orthosilicate (TFDMSOS), and a non-ionic surfactant, Rhodasurf CET-2 (ethoxylatedcetyl-oleyl alcohol), and to investigate their effects on tear strength (TS). METHODS: Five experimental formulations (Exp I-V) were prepared and compared with three medium bodied commercial VPS impression materials (Aq M, Elt M, Extr M). Tear test was performed on trouser test specimens (n=12 per material), at four time points (immediately, 24, 72 and 168 hours after setting). FTIR spectroscopy was used for identifying functional bonds and cross-linking. The results were analysed with one-way ANOVA, two-way ANOVA and post hoc Tukey's test using the SPSS PASW statistical 22 software. RESULTS: The material with novel cross-linking agent (Exp II) had significantly higher TSs at all-time points compared to Exp I (control; pË0.05). Materials incorporating both TFDMSOS and surfactant (Exp III, IV and V), had further significantly increased TS at all-time points, which were concentration dependent. Extr M had a significantly lower TS (immediately after setting and at 24 hours) compared to all Exp and other commercial materials, with the exception of Elt M (difference not significant). The TSs of Exp II-V, after 72 and 168 hours, were significantly higher for than all commercial products and Exp I. FTIR spectra showed the consumption of Si-H groups indicating crosslinking had taken place with the addition of TFDMSOS and surfactant which contributed to an increase in the TS. SIGNIFICANCE: TFDMSOS cross-linking agent increased the TS of Exp II significantly at all-time points compared to the control. Novel surfactant further significantly increased TS, and it was also concentration dependent. Exp VPS with improved TS have been developed, addressing one of the drawbacks of commercial VPS materials.
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Reagentes de Ligações Cruzadas/química , Materiais para Moldagem Odontológica/química , Polivinil/química , Siloxanas/química , Tensoativos/química , Técnica de Moldagem Odontológica , Interações Hidrofóbicas e Hidrofílicas , Ácidos Oleicos/química , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
Hemogen is a vertebrate transcription factor that performs important functions in erythropoiesis and testicular development and may contribute to neoplasia. Here we identify zebrafish Hemogen and show that it is considerably smaller (â¼22â kDa) than its human ortholog (â¼55â kDa), a striking difference that is explained by an underlying modular structure. We demonstrate that Hemogens are largely composed of 21-25 amino acid repeats, some of which may function as transactivation domains (TADs). Hemogen expression in embryonic and adult zebrafish is detected in hematopoietic, renal, neural and gonadal tissues. Using Tol2- and CRISPR/Cas9-generated transgenic zebrafish, we show that Hemogen expression is controlled by two Gata1-dependent regulatory sequences that act alone and together to control spatial and temporal expression during development. Partial depletion of Hemogen in embryos by morpholino knockdown reduces the number of erythrocytes in circulation. CRISPR/Cas9-generated zebrafish lines containing either a frameshift mutation or an in-frame deletion in a putative, C-terminal TAD display anemia and embryonic tail defects. This work expands our understanding of Hemogen and provides mutant zebrafish lines for future study of the mechanism of this important transcription factor.
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OBJECTIVES: To investigate working and setting times, compressive fracture strength (CFS), compressive modulus (CM), three-point flexure strength (TFS) and tensile flexure modulus (TFM) of commercial, control and experimental RMGICs. METHODS: RelyX Luting (RX, 3M-ESPE) and Fuji Plus (FP, GC), two control home liquids and eight new liquid compositions (F1-F4 and R1-R4) comprising different percentages of the monomer HPM (hydroxypropyl-methacrylate) and/or THFM (tetrahydrofurfuryl-methacrylate) with the original monomer HEMA (2-hydroxyethyl-methacrylate) were used in this study. The polymerization was initiated chemically (using benzene sulfonic acid sodium-salt in FP powder and potassium persulfate/ascorbic acid in RX powder). Home and experimental liquids were mixed with the corresponding commercial powder. An oscillating rheometer was used to measure the working and setting times (n=6). 20 cylinders per material (6.0±0.1mm height, 4.0±0.1mm diameter) were fabricated for CFS and CM testing, 20bars per material (25.0±0.1mm length, 2.0±0.1mm width, 2.0±0.1mm thickness) were made for TFS and TFM testing. RESULTS: All RX compositions showed longer setting times (p≤0.0001) and lower CFS values compared to their FP counterparts (p≤0.0001). The TFS testing showed that commercial and home RMGICs behaved as brittle materials with linear load/deflection curve while experimental materials showed plastic ductile deformation before fracture. F3, F4 and F2 showed significantly higher CFS values compared to the corresponding home material (p≤0.0001). SIGNIFICANCE: All new experimental compositions demonstrated working and setting times that are clinically acceptable. The new experimental FP compositions containing THFM (especially F3 and F4) demonstrated improved mechanical properties compared to their corresponding home material.
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Cimentos de Ionômeros de Vidro/química , Cimentos de Resina/química , Resinas Compostas/química , Força Compressiva , Teste de Materiais , Metacrilatos/química , Polimerização , Resistência à TraçãoRESUMO
OBJECTIVES: To formulate experimental hydrophilic (Exp) VPS impression materials incorporating a novel surfactant (Rhodasurf CET-2), and to compare their contact angles (CAs) with commercial materials, before/after disinfection. METHODS: CAs were measured immediately after setting and after disinfection (1% NaOCl; 30min and 24h), together with their change whilst a droplet remained on the materials surface (over 10, 20, 30 60 and 120s), on three commercial (Aquasil Ultra-Monophase [Aq M], Elite HD-Monophase [Elt M], Extrude Medium-bodied [Extr M]) and four experimental (Exp I-IV) materials, using the Drop Shape Analysis 100 technique. The results were compared statistically. RESULTS: CAs of all experimental materials were within the range of those obtained for the commercial materials, with the exception of Exp-IV, which presented with the lowest CAs at the three time points. The control Exp-I was hydrophobic at all three time points (CAs â¼100+), as was Elite. Immediately after setting, Aq M had low CAs but these increased significantly after 30min of disinfection. After twenty four hours' disinfection CAs of all Exp/commercial VPS increased significantly compared to immediately after setting. The CAs of droplets left on the material (120s) decreased with time, even after disinfection, except for Exp-I. SIGNIFICANCE: The novel surfactant Rhodasurf CET-2 in Exp-III and IV, is an effective surfactant, retaining a low CA after disinfection, compared with Igepal CO-530 in Aq M. Disinfecting VPS impression materials for more than 30min increases their surface CAs, and therefore prolonged disinfection periods should be avoided.
Assuntos
Materiais para Moldagem Odontológica , Polivinil , Siloxanas , Humanos , Interações Hidrofóbicas e Hidrofílicas , Teste de Materiais , Propriedades de Superfície , TensoativosRESUMO
OBJECTIVES: To develop two experimental temporary crown and bridge materials with improved physicomechanical properties. METHODS: Commercial materials: Trim (TR, monomethacrylate, Bosworth) and Quicktemp2 (QT, dimethacrylate, Schottlander). EXPERIMENTAL MATERIALS: isobutyl methacrylate/poly(ethyl methacrylate) (IBMA/PEM) and n-butyl methacrylate/PEM (nBMA/PEM), both monomethacrylates. For water absorption/desorption studies rectangular samples (40 mm × 10 mm × 1 mm) of each material were prepared, immersed in deionized water (DW, control) and artificial saliva (AS), and weighed at regular time intervals. %solubility and diffusion coefficients (D) for uptake/loss processes were calculated and compared with theoretical predictions. Polymerization exotherm (cylindrical samples 10 mm × 18 mm) and flexural moduli were measured (three point bending; rectangular samples 80 mm × 10 mm × 4 mm, dry and after 9 days storage in DW). The data were compared statistically. RESULTS: QT and nBMA/PEM had lower %equilibrium uptakes/loss in DW (0.68%/0.884% and 0.64%/0.895% respectively). QT had the lowest water absorption/desorption D (P<0.05) compared to the three monomethacrylates, in DW and AS. %solubility for all systems showed no differences in DW (P>0.05), but a difference for QT in AS (P<0.05). QT reached its maximum temperature rapidly (â¼2 min; 3 monomethacrylates â¼7-13 min). The commercial materials exhibited high peak temperatures (â¼51°C, P<0.05; experimental materials â¼43°C). QT had a higher flexural modulus (â¼4 GPa; 3 monomethacrylates â¼0.7-1 GPa) for dry and wet samples. The moduli for commercial materials reduced significantly after immersion in DW; there was no difference between the dry and wet experimental materials samples (P>0.05). SIGNIFICANCE: The experimental materials merit further studies since they presented with lower setting exotherms, and contained no phthalate plasticizer, thus being less of a risk to patients.
Assuntos
Coroas , Materiais Dentários/química , Restauração Dentária Temporária , Prótese Parcial , Metacrilatos/química , Ácidos Polimetacrílicos/química , Análise do Estresse Dentário , Módulo de Elasticidade , Teste de Materiais , Polimerização , SolubilidadeRESUMO
OBJECTIVE: To investigate water uptake, desorption, diffusion coefficient, solubility and dimensional changes of four experimental RMGICs in deionized water (DW) and artificial saliva (AS), and compare with two commercial RMGICs and control home liquids based on the two commercial materials used. METHODS: Two commercial RMGICs, RelyX Luting (RX, 3M ESPE) and Fuji Plus (FP, GC), two control home liquids and four new liquid compositions (F1, F2, R1, R2) comprising different percentages of the monomer THFM (tetrahydrofurfuryl-methacrylate) with the original monomer HEMA (2-hydroxyethyl-methacrylate) were used in this study. Home and experimental liquids were mixed with the corresponding commercial powder. Disk-shaped specimens (16mm diameter 1mm thickness) were immersed in DW/AS at 37°C (n=6) and weighed at regular time intervals. Percentage weight change with time was recorded. At 24 weeks, disks were desorbed in an oven at 37°C to minimum weight. RESULTS: All new compositions showed lower water uptake and dimensional (volume) changes than the commercial products in both DW and AS. On desorption, FP showed higher weight loss compared to materials in the same group in both solutions (p<0.0001), with the exception of F2 in DW (p=0.283). RX had higher weight loss compared to R1 and R2 in DW and AS (p<0.0001). Fickian diffusion was confirmed for all materials immersed in DW and AS. SIGNIFICANCE: The experimental compositions in this study have shown promising results when tested in both DW and AS with lower water uptakes and volume changes than commercial materials. This may lead to wider applications than current commercial materials.