Propriedades mecânicas e análise microestrutural de um concreto produzido com agregado da região Amazônica brasileira

Em virtude da escassez de agregado em algumas regiões na Amazônia, o presente trabalho tem comoobjetivo, avaliar as propriedades de concretos produzidos com agregado proveniente do leito do rioOiapoque. Fazendo um estudo comparativo relacionando as características entre os agregados graúdosutilizados na construção civil, em especial o material encontrado no leito do Rio Oiapoque, na cidade deOiapoque-AP, e o agregado graúdo oriundo da região metropolitana de Belém. Foram realizados ensaiospara avaliação das propriedades mecânicas, ensaios de desempenho e microestrutura dos concretos. Osresultados mostraram que a utilização do agregado de origem arenítica da região de Oiapoque nãoapresentou diferença na resistência à compressão e no módulo de elasticidade dos concretos em relaçãoao concreto produzidos com agregado disponibilizado comercialmente na região metropolitana de Belém,além disso não houve diferença entre os concretos quanto à taxa de absorção de cloretos ao longo dotempo e avanço na frente de carbonatação. A microestrutura eletrônica de varredura dos concretos,apresentaram uma microestrutura densa, mas normalmente encontrada em compósitos formulados à basede matriz cimentícias. Esses achados servem como evidências empíricas para a validação da utilização deuma jazida de agregado na Região Amazônica, contribuindo para o desenvolvimento de obras deinfraestrutura na região.Palavras-chave: Escassez de agregado, região amazônica, propriedades mecânicas, propriedades dedurabilidade

Biocompatibility and inflammatory response of silver tungstate, silver molybdate, and silver vanadate microcrystals

Silver tungstate (α-Ag2WO4), silver molybdate (β-Ag2MoO4), and silver vanadate (α-AgVO3) microcrystals have shown interesting antimicrobial properties. However, their biocompatibility is not yet fully understood. Cytotoxicity and the inflammatory response of silver-containing microcrystals were analyzed in THP-1 and THP-1 differentiated as macrophage-like cells, with the alamarBlue™ assay, flow cytometry, confocal microscopy, and ELISA. The present investigation also evaluated redox signaling and the production of cytokines (TNFα, IL-1β, IL-6, and IL-8) and matrix metalloproteinases (MMP-8 and -9). The results showed that α-AgVO3 (3.9 μg/mL) did not affect cell viability (p > 0.05). α-Ag2WO4 (7.81 μg/mL), β-Ag2MoO4 (15.62 μg/mL), and α-AgVO3 (15.62 μg/mL) slightly decreased cell viability (p ≤ 0.003). All silver-containing microcrystals induced the production of O2 − and this effect was mitigated by Reactive Oxygen Species (ROS) scavenger and N-acetylcysteine (NAC). TNFα, IL-6 and IL-1β were not detected in THP-1 cells, while their production was either lower (p ≤ 0.0321) or similar to the control group (p ≥ 0.1048) for macrophage-like cells. The production of IL-8 by both cellular phenotypes was similar to the control group (p ≥ 0.3570). The release of MMP-8 was not detected in any condition in THP-1 cells. Although MMP-9 was released by THP-1 cells exposed to α-AgVO3 (3.9 μg/mL), no significant difference was found with control (p = 0.7). Regarding macrophage-like cells, the release of MMP-8 and -9 decreased in the presence of all microcrystals (p ≤ 0.010). Overall, the present work shows a promising biocompatibility profile of, α-Ag2WO4, βAg2MoO4, and α-AgVO3 microcrystals

Increasing the photocatalytic and fungicide activities of Ag3PO4 microcrystals under visible-light irradiation

The present study reports for the first time the performance of silver phosphate (Ag3PO4) microcrystals as photocatalyst (degradation of Rodamine B-RhB) and antifungal agent (against Candida albicans–C. albicans) under visible-light irradiation (455 nm). Ag3PO4 microcrystals were synthesized by a simple co-precipitation (CP) method at room temperature. The structural and electronic properties of the as-synthetized Ag3PO4 have been investigated before and after 4 cycles of RhB degradation under visible light using X-ray diffraction (XRD), micro-Raman spectroscopy, UV–Vis spectrophotometer and field emission scanning electron microscopy (FE-SEM) images. The antifungal activity was analyzed in planktonic cells and 48h-biofilm of C. albicans by colony forming units (CFU) counting, confocal laser and FE-SE microscopies. Statistical analysis was carried out using SPSS software. Morphological and structural modifications of Ag3PO4 were observed upon recycling. After 4 recycles, the material maintained its photodegradation property; an eightfold increase in the efficiency of Ag3PO4 was observed in planktonic cells and a two fold increase in biofilm when irradiated under visible light. Thus, higher antifungal effectiveness against C. albicans was obtained when associated with visible-light irradiation.Funding for open access charge: CRUE-Universitat Jaume

Effect of an additional hydrophilic versus hydrophobic coat on the quality of dentinal sealing provided by two-step etchand-rinse adhesives

OBJECTIVE: To test the hypothesis that the quality of the dentinal sealing provided by two-step etch-and-rinse adhesives cannot be altered by the addition of an extra layer of the respective adhesive or the application of a more hydrophobic, non-solvated resin. MATERIAL AND METHODS: full-crown preparations were acid-etched with phosphoric acid for 15 s and bonded with Adper Single Bond (3M ESPE), Excite DSC (Ivoclar/Vivadent) or Prime & Bond NT (Dentsply). The adhesives were used according to the manufacturers' instructions (control groups) or after application to dentin they were a) covered with an extra coat of each respective system or b) coated with a non-solvated bonding agent (Adper Scotchbond Multi-Purpose Adhesive, 3M ESPE). Fluid flow rate was measured before and after dentin surfaces were acid-etched and bonded with adhesives. RESULTS: None of the adhesives or experimental treatments was capable to block completely the fluid transudation across the treated dentin. Application of an extra coat of the adhesive did not reduce the fluid flow rate of adhesive-bonded dentin (p>0.05). Conversely, the application of a more hydrophobic non-solvated resin resulted in significant reductions in the fluid flow rate (p<0.05) for all tested adhesives. CONCLUSIONS: The quality of the dentinal sealing provided by etch-and-rinse adhesives can be significantly improved by the application of a more hydrophobic, non-solvated bonding agent

Revisiting the metallothionein genes polymorphisms and the risk of oral squamous cell carcinoma in a Brazilian population

Metallothioneins (MTs) gene polymorphisms have been associated with the ability of free radical scavenging and detoxification of heavy metals leading to cancer development. Our aim was to revisit, in a Brazilian population, single-nucleotide polymorphisms (SNPs) of the MT gene family previously associated with oral squamous cell carcinoma (OSCC). A case-control investigation with 28 OSCC patients and 45 controls was conducted, using conventional risk factors (tobacco use and alcohol consumption) as covariates. SNPs genotyping for rs8052334 (MT1B), rs964372 (MT1B), and rs1610216 (MT2A) was performed by PCR-RFLP, and SNPs for rs11076161 (MT1A) were analyzed by TaqMan assay. The only SNP associated with increased risk for OSCC was the MT-1A AA genotype (OR = 4.7; p = 0.01). We have also evidenced for the first time a significant linkage disequilibrium between the SNPs of MT-2A and MT-1A in this population with the highest frequency (30%) of the unfavorable haplotype G/A/C/T (rs1610216 / rs11076161 / rs964372 / rs8052334) of MT gene polymorphisms (OR = 6.2; p = 0.04). Interestingly, after removing the effects of conventional risk factors, we have uncovered the significance of the AA genotype of the rs11076161 with increased odds of 19-fold higher towards OSCC development. This is the first demonstration that a significant linkage disequilibrium among gene polymorphisms of the MT family may affect susceptibility to oral cancer, which is conditioned by the G/A/C/T haplotype (rs1610216/rs11076161/rs964372/ rs8052334) and the MT-1A gene polymorphism has a potential clinical utility for the OSCC risk assessment

Use of postpartum body condition score to identify the most fertile beef cows raised in extensive operations

The assessment of postpartum body condition score in beef cattle may be a useful tool to recommend technologies to improve reproductive efficiency based on nutrition and reproductive management. The variability and repeatability of body condition scores between 60-90 d postpartum were investigated in order to verify the possibility that such assessments could indicate the inheritance of fertility in beef cows. In three consecutive years a total of 3721 cows predominantly Hereford purebreds and crossbreds, kept on natural pastures in seven farms in the southern region of Rio Grande do Sul, Brazil, were evaluated. More than 60% of these cows had intermediate to superior body condition score (scale of five classes), varying significantly among farms and years studied. A low repeatability of scores in the same animal in two or three consecutive years was found, refuting the possibility of direct selection for higher fertility as a function of body condition score. Although the scoring system does not define fertility phenotypes, it allows the identification of the one in every 200 cows with the characteristic of being pregnant and maintaining high body condition scores during three consecutive years, which may serve as base animals for future genome association studies employing single nucleotide polymorphisms

Expressão imunohistoquímica do p53 carcinoma hepatocelular de pacientes brasileiros

Hepatocellular carcinoma (HCC) is an important type of cancer etiologically related to some viruses, chemical carcinogens and other host or environmental factors associated to chronic liver injury in humans. The tumor suppressor gene p53 is mutated in highly variable levels (0-52%) of HCC in different countries. OBJECTIVE: The objective of the present study was to compare the frequency of aberrant immunohistochemical expression of p53 in HCC occurring in cirrhotic or in non-cirrhotic patients as well as in liver cell dysplasia and in adenomatous hyperplasia. We studied 84 patients with HCC or cirrhosis. RESULTS: We detected p53 altered immuno-expression in 58.3% of patients in Grade III-IV contrasting to 22.2% of patients in Grade I-II (p = 0.02). Nontumorous areas either in the vicinity of HCC or in the 30 purely cirrhotic cases showed no nuclear p53 altered expression, even in foci of dysplasia or adenomatous hyperplasia. No significant difference was found among cases related to HBV, HCV or alcohol. CONCLUSION: The high frequency of p53 immunoexpression in this population is closer to those reported in China and Africa, demanding further studies to explain the differences with European and North American reports.O carcinoma hepatocelular (CHC) é um importante tipo de câncer relacionado etiologicamente a alguns vírus, carcinógenos químicos e outros fatores ambientais que causam danos crônicos ao fígado em humanos. A freqüência de mutação do gene p53 em CHC é altamente heterogênea (0-52%) nos diversos países. OBJETIVO: O objetivo deste estudo foi determinar, imuno-histologicamente, a freqüência da expressão anômala de p53 em CHCs em pacientes cirróticos versus não-cirróticos, bem como em displasia hepática e hiperplasia adenomatosa. Para isso, foram estudados 84 pacientes com carcinoma hepatocelular ou cirrose. RESULTADOS: Foram detectadas expressões do p53 alterado em 58,3% dos pacientes com CHC graus III-IV, contrastando com os 22,2% dos pacientes com CHC graus I-II (p = 0,02). Áreas não tumorais, tanto nas proximidades do CHC como nos 30 casos de cirrose não mostraram expressão nuclear alterada do p53, mesmo nas displasias ou hiperplasias adenomatosas. Quando se considerou HBV, HCV ou alcoolismo nos casos estudados, não se encontrou diferença significativa. CONCLUSÃO: A elevada freqüência de imuno-expressão de p53 nesta população é próxima à relatada na China e África, tornando necessárias outras pesquisas para explicar as diferenças com os CHC estudados na Europa e na América do Norte