Primary squamous cell carcinoma of the thyroid diagnosed as anaplastic carcinoma: failure in fine-needle aspiration cytology?

A case of primary squamous-cell carcinoma (SCC) of the thyroid which had been initially diagnosed as an anaplastic carcinoma (ATC) is described: female, 73 years old, with a fast-growing cervical nodule on the left side and hoarseness for 3 months. Ultrasonography showed a 4.5 cm solid nodule. FNA was compatible with poorly differentiated carcinoma with immunoreactivity for AE1/AE3, EMA. Thyroidectomy was performed. Histopathological examination showed a nonencapsulated tumor. Immunohistochemistry disclosed positivity for AE1/AE3, p53,p63, and Ki67. The diagnosis was ATC. A second opinion reported tumor consisting of squamous cells, with intense inflammatory infiltrate both in tumor and in the adjacent thyroid, with final diagnosis of SCC, associated with Hashimoto thyroiditis. No other primary focus of SCC was found. Patient has shown a 48-month survival period. Clinically, primary SCCs of the thyroid and ATCs are similar. The distinction is often difficult particularly when based on the cytological analysis of FNA material.

Effect of UV-photofunctionalization on oral bacterial attachment and biofilm formation to titanium implant material

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação da diluição do DNA extraido de material parafinado para amplificação em PCR

Introduction: Several reasons may lead to the failure of polymerase chain reaction (PCR) using DNA purified from paraffin-embedded materials: presence of inhibitors and degradation of target DNA. DNA dilution will often reduce the concentration of potential inhibitors and still contain enough DNA to allow PCR amplification. Objective: To evaluate the dilution influence of DNA purified from paraffin-embedded materials on β-globin PCR amplification. Material and Method: Paraffin-embedded blocks from 30 patients with oropharynx squamous cell carcinomas, diagnosed and treated at the Oral Oncology Center were selected. DNA extraction was performed using QIAmp minikit (Quiagen). DNA was quantified and evaluated for purity by spectrophotometer analysis. Two groups were formed with different amounts of DNA: group I had the originally extracted DNA and group II had the same DNA, however diluted with ultrapure water addition. PCR was performed in both groups using oligonucleotides for human β-globin gene. Results: For Group I, amplification of the β-globin gene sequence was successful in 33.33% of the samples and for Group II, in 23.33%. Conclusion: Dilution of the DNA extracted of paraffin-embedded materials did not modify statistically the amount of positive samples β-globin gene amplified in PCR, although the results suggest that this is a way to increase the method for efficacy amplification of PCR.

Failure behavior modeling of slender reinforced concrete columns subjected to eccentric load

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

NUMERICAL AND ANALYTICAL VERIFICATION OF A MULTISCALE COMPUTATIONAL MODEL FOR IMPACT PROBLEMS IN HETEROGENEOUS VISCOELASTIC MATERIALS WITH EVOLVING DAMAGE

Composites are engineered materials that take advantage of the particular properties of each of its two or more constituents. They are designed to be stronger, lighter and to last longer which can lead to the creation of safer protection gear, more fuel efficient transportation methods and more affordable materials, among other examples. This thesis proposes a numerical and analytical verification of an in-house developed multiscale model for predicting the mechanical behavior of composite materials with various configurations subjected to impact loading. This verification is done by comparing the results obtained with analytical and numerical solutions with the results found when using the model. The model takes into account the heterogeneity of the materials that can only be noticed at smaller length scales, based on the fundamental structural properties of each of the composite’s constituents. This model can potentially reduce or eliminate the need of costly and time consuming experiments that are necessary for material characterization since it relies strictly upon the fundamental structural properties of each of the composite’s constituents. The results from simulations using the multiscale model were compared against results from direct simulations using over-killed meshes, which considered all heterogeneities explicitly in the global scale, indicating that the model is an accurate and fast tool to model composites under impact loads. Advisor: David H. Allen

A new damage model for composite laminates

Aircraft composite structures must have high stiffness and strength with low weight, which can guarantee the increase of the pay-load for airplanes without losing airworthiness. However, the mechanical behavior of composite laminates is very complex due the inherent anisotropy and heterogeneity. Many researchers have developed different failure progressive analyses and damage models in order to predict the complex failure mechanisms. This work presents a damage model and progressive failure analysis that requires simple experimental tests and that achieves good accuracy. Firstly, the paper explains damage initiation and propagation criteria and a procedure to identify the material parameters. In the second stage, the model was implemented as a UMAT (User Material Subroutine), which is linked to finite element software, ABAQUS (TM), in order to predict the composite structures behavior. Afterwards, some case studies, mainly off-axis coupons under tensile or compression loads, with different types of stacking sequence were analyzed using the proposed material model. Finally, the computational results were compared to the experimental results, verifying the capability of the damage model in order to predict the composite structure behavior. (C) 2011 Elsevier Ltd. All rights reserved.

Computational and experimental characterization of a low-cost piezoelectric valveless diaphragm pump

Flow pumps act as important devices in areas such as Bioengineering, Medicine, and Pharmacy, among other areas of Engineering, mainly for delivering liquids or gases at small-scale and precision flow rate quantities. Principles for pumping fluids based on piezoelectric actuators have been widely studied, since they allow the construction of pump systems for displacement of small fluid volumes with low power consumption. This work studies valveless piezoelectric diaphragm pumps for flow generation, which uses a piezoelectric ceramic (PZT) as actuator to move a membrane (diaphragm) up and down as a piston. The direction of the flow is guaranteed by valveless configuration based on a nozzle-diffuser system that privileges the flow in just one pumping direction. Most research efforts on development of valveless flow pump deal either with computational simulations based on simplified models or with simplified physical approaches based on analytical models. The main objective of this work is the study of a methodology to develop a low-cost valveless piezoelectric diaphragm flow pump using computational simulations, parametric study, prototype manufacturing, and experimental characterization. The parametric study has shown that the eccentricity of PZT layer and metal layer plays a key role in the performance of the pump.

Theoretical models to predict the mechanical behavior of thick composite tubes

This paper shows theoretical models (analytical formulations) to predict the mechanical behavior of thick composite tubes and how some parameters can influence this behavior. Thus, firstly, it was developed the analytical formulations for a pressurized tube made of composite material with a single thick ply and only one lamination angle. For this case, the stress distribution and the displacement fields are investigated as function of different lamination angles and reinforcement volume fractions. The results obtained by the theoretical model are physic consistent and coherent with the literature information. After that, the previous formulations are extended in order to predict the mechanical behavior of a thick laminated tube. Both analytical formulations are implemented as a computational tool via Matlab code. The results obtained by the computational tool are compared to the finite element analyses, and the stress distribution is considered coherent. Moreover, the engineering computational tool is used to perform failure analysis, using different types of failure criteria, which identifies the damaged ply and the mode of failure.

Study of an anisotropic polymeric cellular material under compression loading

This paper emphasizes the influence of micro mechanisms of failure of a cellular material on its phenomenological response. Most of the applications of cellular materials comprise a compression loading. Thus, the study focuses on the influence of the anisotropy in the mechanical behavior of cellular material under cyclic compression loadings. For this study, a Digital Image Correlation (DIC) technique (named Correli) was applied, as well as SEM (Scanning Electron Microscopy) images were analyzed. The experimental results are discussed in detail for a closed-cell rigid poly (vinyl chloride) (PVC) foam, showing stress-strain curves in different directions and why the material can be assumed as transversely isotropic. Besides, the present paper shows elastic and plastic Poisson's ratios measured in different planes, explaining why the plastic Poisson's ratios approach to zero. Yield fronts created by the compression loadings in different directions and the influence of spring-back phenomenon on hardening curves are commented, also.

Clinical evaluation of the failure rates of metallic brackets

OBJECTIVES: The aim of this study was to evaluate in vivo the bonding of metallic orthodontic brackets with different adhesive systems. MATERIAL AND METHODS: Twenty patients (10.5-15.1 years old) who had sought corrective orthodontic treatment at a University Orthodontic Clinic were evaluated. Brackets were bonded from the right second premolar to the left second premolar in the upper and lower arches using: Orthodontic Concise, conventional Transbond XT, Transbond XT without primer, and Transbond XT associated with Transbond Plus Self-etching Primer (TPSEP). The 4 adhesive systems were used in all patients using a split-mouth design; each adhesive system was used in one quadrant of each dental arch, so that each group of 5 patients received the same bonding sequence. Initial archwires were inserted 1 week after bracket bonding. The number of bracket failures for each adhesive system was quantified over a 6-month period. RESULTS: The number of debonded brackets was: 8- Orthodontic Concise, 2- conventional Transbond XT, 9- Transbond XT without primer, and 1- Transbond XT + TPSEP. By using the Kaplan-Meier methods, statistically significant differences were found between the materials (p=0.0198), and the Logrank test identified these differences. Conventional Transbond XT and Transbond XT + TPSEP adhesive systems were statistically superior to Orthodontic Concise and Transbond XT without primer (p<0.05). There was no statistically significant difference between the dental arches (upper and lower), between the dental arch sides (right and left), and among the quadrants. CONCLUSIONS: The largest number of bracket failures occurred with Orthodontic Concise and Transbond XT without primer systems and few bracket failures occurred with conventional Transbond XT and Transbond XT+TPSEP. More bracket failures were observed in the posterior region compared with the anterior region.

Computational Modeling of Cardiac Excitation-Contraction Coupling in Physiological and Pathological Conditions

The cardiomyocyte is a complex biological system where many mechanisms interact non-linearly to regulate the coupling between electrical excitation and mechanical contraction. For this reason, the development of mathematical models is fundamental in the field of cardiac electrophysiology, where the use of computational tools has become complementary to the classical experimentation. My doctoral research has been focusing on the development of such models for investigating the regulation of ventricular excitation-contraction coupling at the single cell level. In particular, the following researches are presented in this thesis: 1) Study of the unexpected deleterious effect of a Na channel blocker on a long QT syndrome type 3 patient. Experimental results were used to tune a Na current model that recapitulates the effect of the mutation and the treatment, in order to investigate how these influence the human action potential. Our research suggested that the analysis of the clinical phenotype is not sufficient for recommending drugs to patients carrying mutations with undefined electrophysiological properties. 2) Development of a model of L-type Ca channel inactivation in rabbit myocytes to faithfully reproduce the relative roles of voltage- and Ca-dependent inactivation. The model was applied to the analysis of Ca current inactivation kinetics during normal and abnormal repolarization, and predicts arrhythmogenic activity when inhibiting Ca-dependent inactivation, which is the predominant mechanism in physiological conditions. 3) Analysis of the arrhythmogenic consequences of the crosstalk between β-adrenergic and Ca-calmodulin dependent protein kinase signaling pathways. The descriptions of the two regulatory mechanisms, both enhanced in heart failure, were integrated into a novel murine action potential model to investigate how they concur to the development of cardiac arrhythmias. These studies show how mathematical modeling is suitable to provide new insights into the mechanisms underlying cardiac excitation-contraction coupling and arrhythmogenesis.

Computational insight into materials properties

The aim of the work was to explore the practical applicability of molecular dynamics at different length and time scales. From nanoparticles system over colloids and polymers to biological systems like membranes and finally living cells, a broad range of materials was considered from a theoretical standpoint. In this dissertation five chemistry-related problem are addressed by means of theoretical and computational methods. The main results can be outlined as follows. (1) A systematic study of the effect of the concentration, chain length, and charge of surfactants on fullerene aggregation is presented. The long-discussed problem of the location of C60 in micelles was addressed and fullerenes were found in the hydrophobic region of the micelles. (2) The interactions between graphene sheet of increasing size and phospholipid membrane are quantitatively investigated. (3) A model was proposed to study structure, stability, and dynamics of MoS2, a material well-known for its tribological properties. The telescopic movement of nested nanotubes and the sliding of MoS2 layers is simulated. (4) A mathematical model to gain understaning of the coupled diffusion-swelling process in poly(lactic-co-glycolic acid), PLGA, was proposed. (5) A soft matter cell model is developed to explore the interaction of living cell with artificial surfaces. The effect of the surface properties on the adhesion dynamics of cells are discussed.

"Experimental and computational approaches to historical masonry structures: A study in the direction of filling the gap"

The assessment of historical structures is a significant need for the next generations, as historical monuments represent the community’s identity and have an important cultural value to society. Most of historical structures built by using masonry which is one of the oldest and most common construction materials used in the building sector since the ancient time. Also it is considered a complex material, as it is a composition of brick units and mortar, which affects the structural performance of the building by having different mechanical behaviour with respect to different geometry and qualities given by the components.

Complication and failure rates in patients treated for chronic periodontitis and restored with single crowns on teeth and/or implants

Objectives: To assess the biological and technical complication rates of single crowns on vital teeth (SC-V), endodontically treated teeth without post and core (SC-E), with a cast post and core (SC-PC) and on implants (SC-I). Material and methods: From 392 patients with chronic periodontitis treated and documented by graduate students during the period from 1978 to 2002, 199 were reexamined during 2005 for this retrospective cohort study, and 64 of these patients were treated with SCs. Statistical analysis included Kaplan–Meier survival functions and event rates per 100 years of object-time. Poisson regression was used to compare the four groups of crowns with respect to the incidence rate ratio of failures, and failures and complications combined over 10 years and the entire observation period. Results: Forty-one (64%) female and 23 (36%) male patients participated in the reexamination. At the time of seating the crowns, the mean patient age was 46.8 (range 24–66.3) years. One hundred and sixty-eight single unit crowns were incorporated. Their mean follow-up time was 11.8 (range 0.8–26.4) years. During the time of observation, 22 biological and 11 technical complications occurred; 19 SC were lost. The chance for SC-V (56) to remain free of any failure or complication was 89.3% (95% confidence interval [CI] 76.1–95.4) after 10 years, 85.8% (95% CI 66–94.5) for SC-E (34), 75.9% for SC-PC (39), (95% CI 58.8–86.7) and 66.2% (95% CI 45.1–80.7) for SC-I (39). Over 10 years, 95% of SC-I remained free of failure and demonstrated a cumulative incidence of failure or complication of 34%. Compared with SC-E, SC-I were 3.5 times more likely to yield failures or complications and SC-PC failed 1.7 times more frequently than did SC-E. SC-V had the lowest rate of failures or complications over the 10 years. Conclusions: While SCs on vital teeth have the best prognosis, those on endodontically treated teeth have a slightly poorer prognosis over 10 years. Crowns on teeth with post and cores and implant-supported SCs displayed the highest incidence of failures and complications.