Modelagem matemática da resposta biológica da pele com tecido ulcerado do pé diabético e olho com retinopatia diabética

Dissertação (Mestrado em Engenharia Biomédica). Universidade de Brasília, Brasília, 2019.Com a evolução da pesquisa, houve, também, a crescente preocupação com a ética e métodos que poderiam substituir o uso de cobaias animais nos experimentos científicos. Ao longo dos últimos anos, cientistas vêm buscando métodos alternativos às cobaias animais. Um destes métodos – a modelagem matemática –, embora não erradique o uso de animais em experimentos, pode ajudar a reduzir o uso de animais em experimentos. Sistemas matemáticos estão presentes no nosso redor. Desde pequenos átomos até reações em estrelas, a matemática rege os mais diversos sistemas de todo universo. Entender a matemática envolvida nestes processos permite uma melhor compreensão de fenômenos físicos, químicos e biológicos e, desta forma, manipulá-los para uma melhoria na qualidade de vida das pessoas. Este estudo propõe uma modelagem de dois aspectos biológicos: a resposta da pele humana à pressão e, também, uma análise dinâmica dos componentes do olho humano. Estes modelos foram baseados na da Teoria Bond Graph e validados com o uso do programa MATLAB®. Em ambos os casos, são utilizados análise de controle comparando dois quadros: um indivíduo saudável e outro portador de diabetes. Esta abordagem visa contribuir para o conceito de Controle Orgânico. É importante ressaltar que um fenômeno não é representado por apenas um único modelo, mas, sim, por uma gama de modelos. O ponto de partida deste trabalho foi a modelagem de um sistema físico similar, utilizando elementos mecânicos e elétricos para expressar o comportamento dos sistemas em termos análogos. Depois, foi desenhado o Bond Graph do modelo, de onde foram extraídas as equações do espaço de estados. A partir destas equações, foram realizadas simulações aplicando a Teoria de Controle Moderno para validar os modelos obtidos. Foram aplicadas entradas impulso e degrau, e extraído tanto o Diagrama de Bode como o Root Locus dos sistemas estudados. Os sistemas representando o cenário saudável dos órgãos em questão apresentaram comportamento similar ao de um sistema físico estável, enquanto os sistemas enfermos apresentaram características instáveis: o olho com retinopatia diabética apresentou um comportamento oscilatório prolongado, enquanto a pele adoecida apresentou instabilidade. Apesar de existirem poucos estudos similares na literatura, os resultados demonstraram confiabilidade e estabilidade do modelo desenvolvido e teve um desempenho satisfatório.With the evolution of research, there was also a growing concern with ethics and methods that could replace the use of animal guinea pigs in scientific experiments. Over the last few years, scientists have been looking for alternative methods to animal guinea pigs. One of these methods - mathematical modeling - while not eradicating the use of animals in experiments, can help reduce their use. Mathematical systems are all around us. From small atoms to star reactions, mathematics governs the most diverse systems in the entire universe. Understanding the mathematics involved in these processes allows a better understanding of physical, chemical and biological phenomena and thus manipulate them for an improvement in people's quality of life. This study proposes a modeling of two biological aspects: the response of human skin to pressure and also a dynamic analysis of the components of the human eye. These models were based on the Bond Graph Theory and validated using the MATLAB® tool. In both cases, control analysis is used comparing two frames: a healthy individual and another with diabetes. This approach aims to contribute to the concept of Organic Control. It is important to stress that a phenomenon is not represented by just a single model, but rather by a range of models. The starting point of this work was to model a similar physical system, using mechanical and electrical elements to show the behavior of the systems in analogous terms. Then, the Bond Graph of the model was drawn, from which state space equations were extracted. From these equations, simulations were performed applying the Modern Control Theory to validate the obtained models. Pulse and step inputs were applied, and both the Bode Diagram and Root Locus were extracted from the studied systems. The systems representing the healthy scenario of the organs in question presented behavior similar to that of a stable physical system, while the diseased systems presented unstable characteristics: the eye with diabetic retinopathy showed a prolonged oscillatory behavior, while the diseased skin showed instability. Although there are few similar studies in the literature, the results demonstrated reliability and stability of the developed model and had a satisfactory performance

Bioética na pesquisa de engenharia biomédica : diminuição do uso de animais em experimentos científicos

Atividades de pesquisa utilizando animais são realizadas desde a antiguidade, o bem-estar do animal não era prioridade. Com a evolução da pesquisa, houve, também, a crescente preocupação com a ética e métodos que poderiam substituir o uso de cobaias animais nos experimentos científicos. Tal conscientização manifestou-se já no início do século XIX, na Inglaterra, com o surgimento de movimentos que se dedicavam a mudar as atitudes do homem em relação aos animais. Desde então, ativistas argumentam que métodos alternativos são capazes de substituir a utilização de animais em pesquisa, e que, por isso, a utilização de seres vivos é considerada como obsoleta. Por outro lado, alguns cientistas argumentam que a experimentação é o que traz frutos das pesquisas. O presente trabalho apresenta um levantamento de dissertações e teses defendidas no Instituto de Biologia da Universidade de Brasília no ano de 2017 que realizaram testes in vitro e in vivo além de trazer uma reflexão sobre o assunto e visa ressaltar as vantagens do uso de métodos alternativos. Para este estudo, foram utilizados artigos e dissertações das bases de dados CAPES e PubMed, bem como outras referências presentes neles. Concluiu-se que, embora não haja tecnologia suficiente para erradicar o uso de animais em experimentos, existem diversos métodos alternativos que não comprometem o estudo realizado

Evidence in practice of tissue healing with latex biomembrane : integrative review

Wound healing is a perfectly coordinated cascade of cellular, molecular, and biochemical events which interact in tissue reconstitution. Chronic diseases such as pressure ulcers (PU) and diabetes mellitus (DM) are considered risk factors for wound healing. Patients with such diseases often have higher sepsis, infection, and complication rates, since they have revascularization inhibition and low growth factor expression. Thus, latex biomembrane (LBM), a biocompatible material, derived from the latex of the rubber tree (Hevea brasiliensis) appears to create tendencies as an angiogenic-inducing tissue healing agent and as biomaterial, resulting from its structural qualities and its low cost when compared to conventional treatments. Therefore, this work aims at summarizing the results, experiments, and scientific findings that certify or recommend the use of LBM as a new technique to be applied effectively in the treatment of wounds. An integrative review was held in the BIREME, LILACS, Burns, MEDLINE, PubMed, and SciELO databases, from 2000 to 2016, using the following descriptors: “healing,” “diabetes mellitus,” “wounds,” and “latex membrane.” As a result, 600 experiments (out of 612) presented satisfactory results; however, 33% of the cases received explicit recommendations, 11% required more studies on the subjects, and 1% was denied. On the other hand, half of the studies did not expressly endorse its use, despite presenting satisfactory results. The LBM was characterized as a good therapeutic alternative in cases of wounds, including chronic diseases, such as diabetes mellitus and PU, due to its relevant potential for wound healing stimulation, acceleration of cell tissue mending and revascularization, or the reestablishment of angiogenic functions (creation of new blood vessels). The LBM was also confirmed to be safe as a biocompatible material whose structural qualities (elasticity, adaptability, impermeability, and possibility of suture), devoid of toxicity, allowed interaction between tissues and presented no hypersensitivity inducer and no antimicrobial effect

Cardiac Evaluation in the Acute Phase of Chagas’ Disease with Post-Treatment Evolution in Patients Attended in the State of Amazonas, Brazil

Abstract Background: In the past two decades, a new epidemiological profile of Chagas’ disease (CD) has been registered in the Brazilian Amazon where oral transmission has been indicated as responsible for the increase of acute cases. In the Amazonas state, five outbreaks of acute CD have been registered since 2004. The cardiac manifestations in these cases may be characterized by diffuse myocarditis, with alteration in the electrocardiogram (ECG) and transthoracic echocardiogram (TTE). Objective: To perform a cardiac evaluation in autochthonous patients in the acute phase and at least one year after submitted to treatment for acute CD and evaluate the demographic variables associated with the presence of cardiac alterations. Methods: We evaluated patients diagnosed with acute CD through direct parasitological or serological (IgM) methods from 2007 to 2015. These patients were treated with benznidazole and underwent ECG and TTE before and after treatment. We assumed a confidence interval of 95% (CI 95%, p < 0.05) for all variables analyzed. Results: We observed 63 cases of an acute CD in which oral transmission corresponded to 75%. Cardiac alterations were found in 33% of the cases, with a greater frequency of ventricular repolarization alteration (13%), followed by pericardial effusion (10%) and right bundle branch block and left anterior fascicular block (2%). The follow-up occurred in 48 patients with ECG and 25 with TTE for a mean period of 15.5 ± 4.1 months after treatment. Of these, 8% presented normalization of the cardiac alterations in ECG, 62.5% remained with the normal exams. All of the patients presented normal results in TTE in the post-treatment period. As for the demographic variables, isolated cases presented more cardiac alterations than outbreaks (p = 0.044) as well as cases from Central Amazonas mesoregion (p = 0.020). Conclusions: Although cardiac alterations have not been frequent in most of the studied population, a continuous evaluation of the clinical-epidemiological dynamics of the disease in the region is necessary in order to establish preventive measures

Effect of exposure to a light‑emitting diode (LED) on the physicochemical characteristics of natural latex biomembranes used to treat diabetic ulcers

Purpose Natural latex biomembrane has shown high therapeutic potential for the treatment of diabetic ulcers when associated with phototherapy. In this study, physical and chemical alterations in the latex biomembranes were evaluated after exposure to light-emitting diode (LED) irradiation and after contact with NaCl solution. Methods There were three experimental groups: natural latex biomembranes (1) in natura; (2) after 35 min of LED light irradiation; and (3) after immersion in NaCl 0.9 g% solution. The samples were analyzed by tensile strength test, thermogravimetry, contact angle wettability, and Fourier-transform infrared spectroscopy. Results The biomembranes that were submitted to contact with NaCl aqueous solution or exposure to LED did not undergo impairment of mechanical resistance. The thermogravimetry analysis indicated that increasing temperature led to mass loss in all samples, referring to their decomposition temperatures. In the wettability test, biomembranes exposed to LED showed a signifcant reduction in the contact angle between 0 and 10 min, indicating an increase in hydrophilicity, suggesting water storage capacity. The Fourier-transform infrared spectrometry assay showed that there was a more signifcant reduction in vibration intensity after immersion in NaCl solution compared to untreated biomembranes. An increase in the intensity of the entire spectrum of biomembranes exposed to LED was observed in comparison with the other samples, which may be related to photodegradation caused by LED light irradiation. Conclusion The biomembranes underwent signifcant changes in its chemical structure after being subjected to diferent types of exposure and maintained its elasticity and tensile strength properties, in addition to showing good water retention capacity after exposure to LED. Thus, it maintains many of its properties for application as a tissue-regenerating biomaterial, even when subjected to LED irradiation and a humid environment