O aprendizado baseado em problemas - PBL

O Aprendizado Baseado em Problemas (ou “Problem Based Learning – PBL”) é uma técnica de ensino que utiliza problemas (que podem ser casos clínicos, problemas epidemiólogicos, dilemas éticos etc) a serem discutidos em um grupo relativamente pequeno de alunos. Em aplicação em vários centros universitários desde a década de 1960, dois grandes centros são referência no mundo todo: asuniversidades de McMaster, no Canadá e a de Maastricht, na Holanda. Nesses grupos, chamados grupos tutoriais, todos dão sua contribuição e, ao final, objetivos de estudo são delimitados. Depois, fora do grupo tutorial, os objetivos são estudados utilizando os meios à disposição (biblioteca, consulta a especialistas, Internet) sendo rediscutidos em outro grupo tutorial. Currículos baseados nessa técnica deensino são habitualmente estruturados em blocos e não mais em disciplinas tradicionais, além de contarem com espaços livres na grade curricular para que o aluno possa estudar. Apesar das vantagens sobre os métodos tradicionais como por exemplo tornar o aluno mais independente na busca do conhecimento, permitir maior integração entre as disciplinas, implicar em capacitação constante do corpo docente,aparentemente os alunos formados por esse método não apresentam vantagens sobre os alunos de métodostradicionais nas provas e concursos realizados imediatamente ao final do curso médico, mas alguns estudos sugerem maior retenção do conhecimento após um ano.The Problem Based Learning – PBL is a teaching technique that makes use of problems (which can be clinical cases, epidemiological problems, ethic dilemmas etc) to be discussed in a relatively small group of students. It has been applied to many university centres since the 1960’s, and two centres are reference around the world: the McMaster (Canada) and Maastricht (Nederlands) universities. In these groups, so called tutorial groups, everyone gives his contribution and, at the end, the study objectives are delimited. Afterwards, outside the tutorial group, the objectives are studied by the utilisation of the resources available (library, specialist consulting, Internet) and discussed again in another tutorial group. Curriculum based on this teaching technique are commonly structured in modules rather than traditional disciplines, besides counting on free time in the curricular grade so that the student can learn. Despite the advantages over the traditional methods as, for example, making the student more independent insearch for knowledge, allowing a better discipline integration and implying a constant actualisation of the teachers, apparently the students graduated by this method have not shown any advantages over students graduated by the traditional method concerning the tests and contests taken immediately after the medical course, but some studies suggest a better knowledge retention after one year

Effects of Repeated Stress on Distal Airway Inflammation, Remodeling and Mechanics in an Animal Model of Chronic Airway Inflammation

Background/Aims: Epidemiological studies suggest that stress has an impact on asthmatic exacerbations. We evaluated if repeated stress, induced by forced swimming, modulates lung mechanics, distal airway inflammation and extracellular matrix remodeling in guinea pigs with chronic allergic inflammation. Methods: Guinea pigs were submitted to 7 ovalbumin or saline aerosols (1-5 mg/ml during 4 weeks; OVA and SAL groups). Twenty-four hours after the 4th inhalation, guinea pigs were submitted to the stress protocol 5 times a week during 2 weeks (SAL-S and OVA-S groups). Seventy-two hours after the 7th inhalation, guinea pigs were anesthetized and mechanically ventilated. Resistance and elastance of the respiratory system were obtained at baseline and after ovalbumin challenge. Lungs were removed, and inflammatory and extracellular matrix remodeling of distal airways was assessed by morphometry. Adrenals were removed and weighed. Results: The relative adrenal weight was greater in stressed guinea pigs compared to non-stressed animals (p < 0.001). Repeated stress increased the percent elastance of the respiratory system after antigen challenge and eosinophils and lymphocytes in the OVA-S compared to the OVA group (p < 0.001, p = 0.003 and p < 0.001). Neither collagen nor elastic fiber contents were modified by stress in sensitized animals. Conclusions: In this animal model, repeated stress amplified bronchoconstriction and inflammatory response in distal airways without interfering with extracellular matrix remodeling. Copyright (C) 2011 S. Karger AG, Base

Evidences of Herbal Medicine-Derived Natural Products Effects in Inflammatory Lung Diseases

Pulmonary inflammation is a hallmark of many respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD), and acute respiratory syndrome distress (ARDS). Most of these diseases are treated with anti-inflammatory therapy in order to prevent or to reduce the pulmonary inflammation. Herbal medicine-derived natural products have been used in folk medicine and scientific studies to evaluate the value of these compounds have grown in recent years. Many substances derived from plants have the biological effects in vitro and in vivo, such as flavonoids, alkaloids, and terpenoids. Among the biological activities of natural products derived from plants can be pointed out the anti-inflammatory, antiviral, antiplatelet, antitumor anti-allergic activities, and antioxidant. Although many reports have evaluated the effects of these compounds in experimental models, studies evaluating clinical trials are scarce in the literature. This review aims to emphasize the effects of these different natural products in pulmonary diseases in experimental models and in humans and pointing out some possible mechanisms of action

Y-27632 is associated with corticosteroid-potentiated control of pulmonary remodeling and inflammation in guinea pigs with chronic allergic inflammation

Abstract\ud \ud Background\ud Previously, we showed that treatment with the Rho-kinase inhibitor Y-27632 was able to control airway responsiveness, inflammation, remodeling, and oxidative stress in an animal model of asthma, suggesting that this drug is beneficial in asthma. However, studies evaluating the effects of these inhibitors in conjunction with corticosteroids on chronic pulmonary inflammation have not been conducted. Therefore, we evaluated the effects of treatment with the Rho-kinase inhibitor Y-27632, with or without concurrent dexamethasone treatment, on airway and lung tissue mechanical responses, inflammation, extracellular matrix remodeling, and oxidative stress in guinea pigs with chronic allergic inflammation.\ud \ud \ud Methods\ud The guinea pigs were subjected to seven ovalbumin or saline inhalation exposures. Treatment with Y-27632 (1 mM) and dexamethasone (2 mg/kg) started at the fifth inhalation. Seventy-two hours after the seventh inhalation, the pulmonary mechanics were evaluated and exhaled nitric oxide (ENO) levels were determined. The lungs were removed and histological analysis was performed using morphometry.\ud \ud \ud Results\ud The treatment of guinea pigs with the Rho-kinase inhibitor and dexamethasone (ORC group) decreased ENO, the maximal mechanical responses after antigen challenge, inflammation, extracellular matrix remodeling and oxidative stress in the lungs.\ud This therapeutic strategy reduced the levels of collagen and IFN-γ in the airway walls, as well as IL-2, IFN-γ, 8-iso-PGF2α and NF-κB in the distal parenchyma, when compared to isolated treatment with corticosteroid or Rho-kinase inhibitor (P < 0.05) and reduced the number of TIMP-1-positive cells and eosinophils in the alveolar septa compared to corticosteroid-treated animals (P < 0.05). The combined treatment with the Rho-kinase inhibitor and the corticosteroid provided maximal control over the remodeling response and inflammation in the airways and parenchyma.\ud \ud \ud Conclusions\ud Rho-kinase inhibition, alone or in combination with corticosteroids, can be considered a future pharmacological tool for the control of asthma.We thank Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) for their financial support

Extracellular Matrix Component Remodeling in Respiratory Diseases: What Has Been Found in Clinical and Experimental Studies?

Changes in extracellular matrix (ECM) components in the lungs are associated with the progression of respiratory diseases, such as asthma, chronic obstructive pulmonary disease (COPD), and acute respiratory distress syndrome (ARDS). Experimental and clinical studies have revealed that structural changes in ECM components occur under chronic inflammatory conditions, and these changes are associated with impaired lung function. In bronchial asthma, elastic and collagen fiber remodeling, mostly in the airway walls, is associated with an increase in mucus secretion, leading to airway hyperreactivity. In COPD, changes in collagen subtypes I and III and elastin, interfere with the mechanical properties of the lungs, and are believed to play a pivotal role in decreased lung elasticity, during emphysema progression. In ARDS, interstitial edema is often accompanied by excessive deposition of fibronectin and collagen subtypes I and III, which can lead to respiratory failure in the intensive care unit. This review uses experimental models and human studies to describe how inflammatory conditions and ECM remodeling contribute to the loss of lung function in these respiratory diseases