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"Santos, F C P"
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Effect of Gamma Irradiation on Ultimate Tensile Strength of Enamel and Dentin
by
SOARES C. J.
,
PEREIRA P. N. R.
,
NAVES L. Z.
in
Biological and medical sciences
,
Biological effects of radiation
,
Collagen - radiation effects
2010
The effect of gamma irradiation therapy on the ultimate tensile strength (UTS) of enamel and dentin in relation to prism orientation, dentin tubule orientation, and location is unknown. It was hypothesized that tubule and prism orientation, location, and irradiation have an effect on the UTS of dental structures. Forty human third molars were used, half of which were subjected to 60 Gy of gamma irradiation, in daily increments of 2 Gy. The specimens were evaluated by microtensile testing. Results showed that irradiation treatment significantly decreased the UTS of coronal and radicular dentin and of enamel, regardless of tubule or prism orientation. With or without irradiation, enamel was significantly stronger when tested parallel to its prismatic orientation. Coronal and radicular dentin of non-irradiated specimens presented significantly higher UTS when tested perpendicularly to tubule orientation. However, when the teeth were irradiated, the influence of tubule orientation disappeared, demonstrating that irradiation is more harmful to organic components.
Journal Article
Does the addition of chlorhexidine to glass ionomer cements influence its antimicrobial effect and survival rate? A systematic review
2022
Purpose
To evaluate the influence of the addition of chlorhexidine on the antimicrobial effect and on the survival of restorations performed with glass ionomer cement.
Methods
Nine databases were used to search for randomized clinical trials that compared the survival rate and the antimicrobial effect of glass ionomer cement (GIC) restorations with and without the incorporation of chlorhexidine (CHX), without restrictions on year or language. Cochrane Collaboration’s Risk of Bias 2 was used to assess the risk of bias. The GRADE approach was used to assess the certainty of evidence.
Results
From 593 studies found, seven met the inclusion criteria. The concentration of CHX varied between 0.5 and 2%. In general, the addition of CHX to GIC promoted reductions in
Streptococcus mutans
and
Lactobacillus acidophilus
burdens when compared to those without CHX. No study showed a difference in the survival of restorations between GIC with CHX and conventional GIC. Individual risk of bias varied from low to high and the certainty of evidence was classified as very low.
Conclusions
Based on a very low level of certainty, the evidence suggests that the incorporation of CHX in GIC might improve the antimicrobial effects for a short time, in addition to having little influence on the survival of the restoration.
Journal Article
Genomic and epidemiological monitoring of yellow fever virus transmission potential
2018
The yellow fever virus (YFV) epidemic in Brazil is the largest in decades. The recent discovery of YFV in Brazilian Aedes species mosquitos highlights a need to monitor the risk of reestablishment of urban YFV transmission in the Americas. We use a suite of epidemiological, spatial, and genomic approaches to characterize YFV transmission. We show that the age and sex distribution of human cases is characteristic of sylvatic transmission. Analysis of YFV cases combined with genomes generated locally reveals an early phase of sylvatic YFV transmission and spatial expansion toward previously YFV-free areas, followed by a rise in viral spillover to humans in late 2016. Our results establish a framework for monitoring YFV transmission in real time that will contribute to a global strategy to eliminate future YFV epidemics.
Journal Article
DEFORESTATION MONITORING IN DIFFERENT BRAZILIAN BIOMES: CHALLENGES AND LESSONS
by
Maia, J. S.
,
Vinhas, L.
,
Martins, F. S. R. V.
in
Deforestation
,
Monitoring
,
Satellite imagery
2020
Monitoring the conversion of native vegetation has challenged Brazilian government and scientists since the 1980s. In the case of the Amazonian forests, the Amazon Gross Deforestation Monitoring Project - PRODES has developed an effective methodology that provides consistent annual data on deforestation areas on a scale of 1:250,000, since 1988. In this article, we present some aspects of the evolution of this methodology, the key processes to produce accurate deforestation maps during the last 30 years and the new challenges that the Project would face. A central lesson is that no computational technique has, to date, been able to achieve the quality of deforestation maps produced by visual interpretation of satellite images and manual mapping.
Journal Article
Microtensile Specimen Attachment and Shape-Finite Element Analysis
by
SOARES C. J.
,
SANTOS-FILHO P. C. F.
,
ARMSTRONG S. R.
in
Bisphenol A-Glycidyl Methacrylate - chemistry
,
Dental Bonding - methods
,
Dental Materials - chemistry
2008
Microtensile bond strength values are influenced by specimen shape and attachment method to the gripping device during testing. We hypothesized that stress distribution inside the testing specimen is affected by microtensile specimen shape and attachment method. Rectangular, hourglass-, and dumbbell-shaped specimens, all with a 1 mm2 cross-sectional testing region, were modeled as indirect ceramic restorations luted to dentin. Three specimen attachments were investigated: (1) posterior surface; (2) posterior, superior, and lateral surfaces; and (3) all surfaces. Qualitative and quantitative analyses were carried out according to von Mises’ criteria. Stress analysis showed a direct correlation between attachment modes and stress distribution, with shear stresses observed in models with less surface attachment. Increasing the number of faces for specimen attachment to the metallic gripping device resulted in a more homogeneous and regular distribution of stress, with tensile stress concentrated at the adhesive interface. Dumbbell-shaped specimens showed improved stress distribution compared with rectangular and hourglass-shaped specimens.
Journal Article
Genomic Surveillance of Yellow Fever Virus Epizootic in São Paulo, Brazil, 2016 – 2018
2020
São Paulo (SP), a densely inhabited state in southeast Brazil that contains the fourth most populated city in the world, recently experienced its largest yellow fever virus (YFV) outbreak in decades. YFV does not normally circulate extensively in SP, so most people were unvaccinated when the outbreak began. Surveillance in non-human primates (NHPs) is important for determining the magnitude and geographic extent of an epizootic, thereby helping to evaluate the risk of YFV spillover to humans. Data from infected NHPs can give more accurate insights into YFV spread than when using data from human cases alone. To contextualise human cases, identify epizootic foci and uncover the rate and direction of YFV spread in SP, we generated and analysed virus genomic data and epizootic case data from NHP in SP. We report the occurrence of three spatiotemporally distinct phases of the outbreak in SP prior to February 2018. We generated 51 new virus genomes from YFV positive cases identified in 23 different municipalities in SP, mostly sampled from non-human primates between October 2016 and January 2018. Although we observe substantial heterogeneity in lineage dispersal velocities between phylogenetic branches, continuous phylogeographic analyses of generated YFV genomes suggest that YFV lineages spread in SP state at a mean rate of approximately 1km per day during all phases of the outbreak. Viral lineages from the first epizootic phase in northern SP subsequently dispersed towards the south of the state to cause the second and third epizootic phases there. This alters our understanding of how YFV was introduced into the densely populated south of SP state. Our results shed light on the sylvatic transmission of yellow fever in highly fragmented forested regions in SP state and highlight the importance of continued surveillance of zoonotic pathogens in sentinel species. Competing Interest Statement The authors have declared no competing interest.
Optimizing procedures for antioxidant phenolics extraction from skin and kernel of peanuts with contrasting levels of drought tolerance
by
MASSARIOLI, A. P
,
ALENCAR, S. M. de
,
RAMOS, J. P. C
in
Antioxidants
,
Chromatography
,
Clustering
2022
Peanut is an affordable legume known for its nutritional value and phenolic content. The kernel and skin of 14 peanut genotypes contrasting in drought tolerance had their phenolic profiles determined and reactive oxygen species (ROS) scavenging activity evaluated. Firstly, temperature and % EtOH to extract antioxidant phenolic compounds were optimized using response surface methodology (RSM). The optimized extraction conditions, 60 ºC and 35% EtOH for kernels and 40 ºC and 60% EtOH for skins, were further adopted, and phenolic compounds were identified and quantified using high-performance liquid chromatography coupled with electrospray ionizationquadrupole- time of flight-mass spectrometry (HPLC-ESI-QTOF-MS) and high-performance liquid chromatography with photodiode array detector (HPLC-PDA). As a result, phenolic acids and glycosidic/non-glycosidic flavonoids were found. Principal component analysis was conducted, and the pairwise score plot of the skin extracts based on individual phenolic compounds showed a trend of genotype clustering based not only on drought tolerance but also on botanical type of germplasm. Therefore, our results demonstrate the status quo for antioxidant phenolic compounds of peanut genotypes contrasting in drought tolerance grown under natural field conditions.
Journal Article
Carotenoid biosynthesis structural genes in carrot (Daucus carota): isolation, sequence-characterization, single nucleotide polymorphism (SNP) markers and genome mapping
by
JUST, B. J
,
SIMON, P. W
,
BOITEUX, L. S
in
Base Sequence
,
beta-carotene
,
Biological and medical sciences
2007
In this study, we utilized published carrot sequences as well as heterologous PCR approaches with primers derived from sequence information of other plant species to isolate 24 putative genes coding for carotenoid bio-synthesis enzymes in carrot. Twenty-two of these genes were placed on the carrot genetic linkage map developed from a cross between orange-rooted and white- rooted carrot. The carotenoid genes were distributed in eight of the nine linkage groups in the carrot genome recommending their use for merging maps. Two genes co-localized with a genomic region spanning one of the most significant quantitative trait loci (QTL) for carotenoid accumulation.
Journal Article