ABSTRACT
Cross-talk between skeletal muscle and tendon is important for tissue homeostasis. Whereas the skeletal muscle response to tendon injury has been well-studied, to the best of our knowledge the tendon response to skeletal muscle injury has been neglected. Thus, we investigated calcaneal tendon extracellular matrix (ECM) remodeling after gastrocnemius muscle injury using a rat model. Wistar rats were randomly divided into four groups: control group (C; animals that were not exposed to muscle injury) and harvested at different time points post gastrocnemius muscle injury (3, 14, and 28 days) for gene expression, morphological, and biomechanical analyses. At 3 days post injury, we observed mRNA-level dysregulation of signaling pathways associated with collagen I accompanied with disrupted biomechanical properties. At 14 days post injury, we found reduced collagen content histologically accompanied by invasion of blood vessels into the tendon proper and an abundance of peritendinous sheath cells. Finally, at 28 days post injury, there were signs of recovery at the gene expression level including upregulation of transcription factors related to ECM synthesis, remodeling, and repair. At this time point, tendons also presented with increased peritendinous sheath cells, decreased adipose cells, higher Young's modulus, and lower strain to failure compared to the uninjured controls and all post injury time points. In summary, we demonstrate that the calcaneal tendon undergoes extensive ECM remodeling in response to gastrocnemius muscle injury leading to altered functional properties in a rat model. Tendon plasticity in response to skeletal muscle injury merits further investigation to understand its physiological relevance and potential clinical implications.
ABSTRACT
O sucesso da erradicação da transmissão autóctone do vírus da poliomielite nas Américas, levou os Ministros da Saúde dos países membros da Organização Pan-Americana da Saúde - OPAS a assumirem, em 1994, a meta de eliminação do sarampo até o ano 2000. O Plano de Eliminação do Sarampo inclui as estratégias: imunização das crianças de 9 meses a 14 anos de uma só vez e a manutenção de altas coberturas vacinais em menores de 1 ano; campanhas periódicas a cada 2 a 4 anos para menores de 4 anos; a implementação dos sistemas de vigilância epidemiológica, para detectar casos suspeitos de sarampo. O impacto das ações adotadas em vários países da América caracterizou-se pela drástica redução da incidência da doença, estimulando a OPAS a realizar uma avaliação, visando conhecer a verdadeira situação epidemiológica da doença e a capacidade dos sistemas de vigilância epidemiológica em detectar casos/surtos oportunamente e aplicar as medidas de controle de forma ágil. A metodologia, desenvolvida pela OPAS, é de caráter qualitativo com componentes quantitativos. Apresenta-se neste trabalho a avaliação realizada no Brasil nos Estados de São Paulo e Bahia. Os resultados apontam para um sistema de vigilância moroso, que não permite a detecção oportuna de casos ou surtos e que o Plano de Eliminação não representava prioridade política nos anos posteriores a sua implementação em 1992.
The successful eradication of the transmission of autochthonous wild poliomyelitis virus in the Americas, encouraged the Ministers of Health of the members States of the Pan-American Health Organization - PAHO - in 1994 to adopt the goal of eliminating measles in the Region by the year 2000. The Measles Elimination Plan consist of four basic strategies: a one time vaccination of all children between 9 months and 14 years in national campaign; maintenance of high vaccination coverages in children less than 1 year; periodic vaccination campaigns, every 2/4 years to detect suspected cases of measles in children less than 4 years and the implementation and strengthening of epidemiological surveillance system. A drastic reduction in the incidence of the disease was observed in the Americas which stimulated PAHO, to carry out an evaluation of the measles epidemiological surveillance system with the objective to determine the true epidemiological situation and the system's capacity in to detect suspected cases of measles or outbreaks and implement control measures in a timely fashion. The methodology was developed by PAHO, and consists mainly on qualitative attributes with quantitative components. The evaluation was realized in the Brazilian States of Bahia and São Paulo and revealed that the measles surveillance system is slow, not allowing the timely detection of cases or outbreaks and that the Elimination Plan was not considered a political priority in the years following its implementation in 1992.
