Influência da restrição alimentar de vitamina A sobre o coração de ratas adultas

A deficiência de vitamina A é problema de saúde pública mundial e as principais populações acometidas são crianças e gestantes. Existem 250 milhões de pessoas no mundo com esta deficiência e sua principal causa é a redução da ingestão deste composto. O conceito de deficiência de vitamina A consta da depleção de estoques hepáticos associada à redução do retinol sérico. A deficiência de vitamina A é sabidamente prejudicial à fase embriogênica cardíaca. Após o nascimento, na idade adulta,~ vitamina A exerce papel na manutenção da estrutura e função do coração e su~ suplementação parece ser benéfica como atenuante da remodelação cardíaca. Pouco se sabe, no entanto, sobre a influência da deficiência de vitamina A sobre o coração após o nascimento, já que esta carência não é comum na população adulta, devido ao grande estoque hepático. Existe, entretanto, o transporte de vitamina A, para os tecidos, pela via dos quilomicrons. Esta via é dependente da ingestão vitamínica e não de seus estoques. Sendo assim, é possível que a ingestão inadequada deste composto, cause redução tecidual desta vitamina previamente à depleção dos estoques hepáticos e ao aparecimento da deficiência de vitamina A. Considerando que mais da metade da população brasileira, incluindo adultos, apresenta ingestão de vitamina A inferior a 50% das recomendações, a redução tecidual deste composto passa a ser uma possibilidade ainda não estudada nos tecidos, como o coração. Portanto, formulamos a hipótese que a ingestão inadequada de vitamina A, na ausência de deficiência deste composto, ou seja, com manutenção da retinolemia sé rica e estoques hepáticos, leva à redução vitamínica no tecido cardíaco causando remodelação. Assim, foram estudadas 91 ratas Wistars...Pregnancy and childhood Vitamin A deficiency is an important public health concern. There are 250 million people around the world with this deficiency. The inadequate ingestion of this nutrient is the most important cause of it. Low serum retinol concentration and liver stores severely depleted are the biochemical findings in vitamin A deficiency. Cardiac embryonic development requires vitamin A. Postnatal heart are also a retinoid target organ, including the remodeling processo In spite of it, there are few studies about vitamin A deficiency at postnatal heélrt. Esterified retinol transported in chylomicron to tissues is reduced in low vitamin A ingestion and can cause target organ deficiency in spite of preserved serum and hepatic vitamin A. The hypothesis of this study is that inadequate vitamin A ingestion, without systemic deficiency of this nutrient, produces low heart levels of vitamin A, resulting in cardiac remodeling. Wistars female rats were studied: 45 at control group and 46 at diet reduced in vitamin A (RvitA) group. Control rats were born from dams fed with AIN-93 diet sufficient in vitamin A, during pregnancy and lactation. RvitA rats were born from dams fed with AIN-93 vitamin A-free diet, during pregnancy and lactation. Liver vitamin A was measured in sixteen newborns of each group. Twenty nine control rats were fed onto the same diet during weaning and post weaning period. Thirty RvitA rats were fed onto vitamin A-free diet during weaning and vitamin A containing 0,18 retinol equivalent (RE)(g of diet post weantng. When the animais were 200-250g, they were subjected to a transthoracic echocardiographic exam and to isolated rat heart study. Blood, liver and heart samples were collected to vitamin A dosage, to oxidative stress evaluation, to energetic metabolism evaluation, and to hypertrophy and fibrosis measurements.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Cardiovascular remodeling induced by passive smoking

Coronary heart disease (CHD) is the most common cause of death in many developed countries. The major risk factors for CHD are smoking, high blood pressure, diabetes, high cholesterol levels, and lack of physical activity. Importantly, passive smoke also increases the risk for CHD. The mechanisms involved in the effects of passive smoke in CHD are complex and include endothelial dysfunction, lipoprotein modification, increased inflammation and platelet activation. Recently, several studies have shown that exposure to tobacco smoke can result in cardiac remodeling and compromised cardiac function. Potential mechanisms for these alterations are neurohumoral activation, oxidative stress, and MAPK activation. Although the vascular effects of cigarette smoke exposure are well known, the effects of tobacco smoking on the heart have received less attention. Therefore, this review will focus on the recent findings as to the effects of passive smoking in acute and chronic phases of vascular and cardiac remodeling. © 2009 Bentham Science Publishers Ltd

Cardiac remodeling induced by smoking: Concepts, relevance, and potential mechanisms

Cardiac or ventricular remodeling is characterized by molecular, cellular, and interstitial alterations that lead to changes in heart size, mass, geometry and function in response to a given insult. Currently, tobacco smoke exposure is recognized as one of these insults. Indeed, tobacco smoke exposure induces the enlargement of the left-sided cardiac chambers, myocardial hypertrophy, and ventricular dysfunction. Potential mechanisms for these alterations include hemodynamic and neurohormonal changes, oxidative stress, inflammation, nitric oxide bioavailability, matrix metalloproteinases and mitogen-activated protein kinase activation. This review will focus on the concepts, relevance, and potential mechanisms of cardiac remodeling induced by tobacco smoke. © 2012 Bentham Science Publishers

Mejora de calidad de imagen de sistemas difusivos por absorción inducida

El fenómeno óptico de la difusión, también conocido como scattering o esparcimiento, siempre supone un obstáculo en los procesos, técnicas y aplicaciones ópticas; pues, aunque la exigencia en la precisión de los resultados no sea muy alta, si lo será con seguridad la pérdida de información que se produce. Es por ello que aquellas técnicas, sistemas o instrumentos que nos ayuden a mitigar los efectos producidos por este fenómeno ganan al menos cierta atención. En este proyecto exploramos uno de las posibles vías que nos podría ser útil en aquellas situaciones donde se requiera un cierto grado de precisión en la imagen y no se tenga por causa de algún sistema difusivo interpuesto. Esta vía consiste, como veremos, en la adición al sistema difusivo de un componente absorbente, que eliminaría en parte la radiación difundida causante de la turbidez de la imagen. Ya con anterioridad a este proyecto se demuestra la efectividad del carbón negro en polvo para conseguir dicha absorción. En el presente trabajo utilizaremos otros absorbentes, entre ellos el grafeno, estudiando las relativamente poco exploradas cualidades ópticas de este famoso material. ABSTRACT The scattering optical phenomena is always an obstacle in processes, techniques and optical applications, because, even in cases with a non required high level of accuracy of the results, the loss of information will surely be high. That is why those techniques, systems or instruments that help us to mitigate the effects produced by this phenomenon, deserve some attention. In this project we explore one of the possible methods that could be useful in situations in which a certain degree of precision in the image is required and we don't have it, due to some diffusive system interposed. This method, as we will see, consists on the addition to the diffusive system of an absorbent component, that would eliminate the scattered radiation that causes the turbidity of the image. Before this project, the effectiveness of carbon black powder to achieve this absorption was demonstrated. In the present work we will use other absorbers, including graphene, studying the relatively poorly explored optical characteristics of this famous material

Paralisia periódica hipocalêmica tireotóxica em paciente de ascendência africana

Thyrotoxic hypokalemic periodic paralysis (THPP) is an endocrine emergency marked by recurrent attacks of muscle weakness associated with hypokalemia and thyrotoxicosis. Asiatic male patients are most often affected. On the other hand, African descents rarely present this disease. The case described shows an afrodescendant patient with hypokalemia and tetraparesis, whose diagnosis of hyperthyroidism was considered during this crisis. The THPP, although rare, is potentially lethal. Therefore, in cases of flaccid paresis crisis this diagnosis should always be considered, especially if associated with hypokalemia. In this situation, if no previous diagnosis of hyperthyroidism, this should also be regarded.A paralisia periódica hipocalêmica tireotóxica (PPHT) é uma urgência endocrinológica caracterizada por ataques recorrentes de fraqueza muscular, associados à hipocalemia e à tireotoxicose. Essa patologia ocorre mais frequentemente em pacientes do sexo masculino, de origem asiática, sendo rara sua apresentação em pessoas de ascendência africana. O caso descrito mostra um paciente afrodescendente que apresentou tetraparesia associada à hipocalemia. Durante esse episódio foi realizado o diagnóstico de hipertireoidismo. A PPHT, embora rara, é potencialmente letal. Portanto, em casos de crises de paresias flácidas, essa hipótese diagnóstica deve ser sempre considerada, principalmente se associada à hipocalemia. Nessa situação, se não houver diagnóstico prévio de hipertireoidismo, este também deve ser considerado.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Energy Metabolism in Cardiac Remodeling and Heart Failure

Fatty acids are the main substrates used by mitochondria to provide myocardial energy under normal conditions. During heart remodeling, however, the fuel preference switches to glucose. In the earlier stages of cardiac remodeling, changes in energy metabolism are considered crucial to protect the heart from irreversible damage. Furthermore, low fatty acid oxidation and the stimulus for glycolytic pathway lead to lipotoxicity, acidosis, and low adenosine triphosphate production. While myocardial function is directly associated with energy metabolism, the metabolic pathways could be potential targets for therapy in heart failure. © 2013 by Lippincott Williams & Wilkins

Piomiosite tropical: apresentações atípicas

A piomiosite tropical é uma infecção primária dos músculos, que ocorre principalmente em países tropicais. Inicialmente, suas manifestações são leves e inespecíficas, o que dificulta o diagnóstico. A história natural dessa doença costuma ser benigna, com raras complicações. Essa apresentação descreve quatro casos de piomiosite, com manifestações e complicações peculiares.Tropical pyomyositis is a primary infection of the skeletal muscles, that occurs mainly in tropical countries. At onset its manifestation is nonspecific, thereby hindering the diagnostic. The natural history of this disease is commonly benign, with rare complications. This presentation describes four cases of pyomyositis with peculiar manifestations and complications

Deficiência de tiamina como causa de cor pulmonale reversível

A deficiência de tiamina pode apresentar quatro formas clássicas de apresentação clínica: polineuropatia periférica, anorexia e fraqueza muscular (beribéri seco); insuficiência cardíaca de alto débito com sinais congestivos (beribéri úmido); beribéri associado ao choque (Shoshin beribéri) e encefalopatia de Wernicke. Neste relato, descrevemos quadro sugestivo de hipertensão pulmonar grave e cor pulmonale, com estase jugular, hepatite congestiva e edema generalizado, que apresentou reversão completa após administração de tiamina.Thiamine deficiency may present four classic clinical forms: peripheral polyneuropathy, anorexia and muscular weakness (dry beriberi); high output heart failure with signs of congestion (wet beriberi); beriberi associated with shock (Shoshin beriberi) and Wernicke's encephalopathy. In this report we describe a picture that is suggestive of severe pulmonary hypertension and cor pulmonale, with jugular stasis, congestive hepatitis and generalized edema that reversed completely after the administration of thiamine