Swimming training potentiates the recovery of femoral neck strength in young diabetic rats under insulin therapy.

OBJECTIVE: To test whether swimming training benefits femoral neck strength in young diabetic rats under insulin therapy. METHODS: A total of 60 male Wistar rats (age: 40 days) were divided equally into the following six groups: control sedentary, control exercise, diabetic sedentary, diabetic exercise, diabetic sedentary plus insulin and diabetic exercise plus insulin. Diabetes was induced with a unique intraperitoneal injection (60 mg/kg body weight) of streptozotocin. Seven days after the injection and after 12 hours of fasting, the animals with blood glucose levels ≥300 mg/dL were considered diabetic. Seven days after the induction of diabetes, the animals in the exercise groups were subjected to progressive swimming training (final week: 90 min/day; 5 days/week; 5% load) for eight weeks. The animals in the insulin groups received a daily dose of insulin (2-4 U/day) for the same period. RESULTS: Severe streptozotocin-induced diabetes reduced the structural properties of the femoral neck (trabecular bone volume, trabecular thickness and collagen fiber content). The femoral neck mechanical properties (maximum load and tenacity) were also impaired in the diabetic rats. Insulin therapy partially reversed the damage induced by diabetes on the structural properties of the bone and mitigated the reductions in the mechanical properties of the bone. The combination of therapies further increased the femoral neck trabecular bone volume (∼30%), trabecular thickness (∼24%), collagen type I (∼19%) and type III (∼13%) fiber contents, maximum load (∼25%) and tenacity (∼14%). CONCLUSIONS: Eight weeks of swimming training potentiates the recovery of femoral neck strength in young rats with severe streptozotocin-induced diabetes under insulin therapy.

Swimming training potentiates the recovery of femoral neck strength in young diabetic rats under insulin therapy

OBJECTIVE: To test whether swimming training benefits femoral neck strength in young diabetic rats under insulin therapy. METHODS: A total of 60 male Wistar rats (age: 40 days) were divided equally into the following six groups: control sedentary, control exercise, diabetic sedentary, diabetic exercise, diabetic sedentary plus insulin and diabetic exercise plus insulin. Diabetes was induced with a unique intraperitoneal injection (60 mg/kg body weight) of streptozotocin. Seven days after the injection and after 12 hours of fasting, the animals with blood glucose levels ≥300 mg/dL were considered diabetic. Seven days after the induction of diabetes, the animals in the exercise groups were subjected to progressive swimming training (final week: 90 min/day; 5 days/week; 5% load) for eight weeks. The animals in the insulin groups received a daily dose of insulin (2-4 U/day) for the same period. RESULTS: Severe streptozotocin-induced diabetes reduced the structural properties of the femoral neck (trabecular bone volume, trabecular thickness and collagen fiber content). The femoral neck mechanical properties (maximum load and tenacity) were also impaired in the diabetic rats. Insulin therapy partially reversed the damage induced by diabetes on the structural properties of the bone and mitigated the reductions in the mechanical properties of the bone. The combination of therapies further increased the femoral neck trabecular bone volume (∼30%), trabecular thickness (∼24%), collagen type I (∼19%) and type III (∼13%) fiber contents, maximum load (∼25%) and tenacity (∼14%). CONCLUSIONS: Eight weeks of swimming training potentiates the recovery of femoral neck strength in young rats with severe streptozotocin-induced diabetes under insulin therapy.

Propriedades mecânicas de aloenxertos meniscais de coelhos após preservação em glicerina e reidratação em NaCl 0,9% / Mechanical properties of rabbit meniscal allografts after glycerin preservation and rehydration in NaCl 0.9%

Foram avaliadas as propriedades mecânicas, força, deformação e tensão ao limite elástico, tensão ao ponto de ruptura e índice de rigidez, de meniscos frescos e meniscos transplantados por 70 dias em joelhos de coelhos, após preservação em glicerina. O primeiro grupo (tratado) foi formado por seis meniscos mediais do joelho esquerdo, coletados de animais oriundos de criação comercial. Esses meniscos foram armazenados em glicerina 98% por um período de 45-60 dias; em seguida, foram reidratados em solução salina a 0,5% de enrofloxacina, por 12 horas, e implantados em joelhos de outros seis coelhos, submetidos à meniscectomia. Após 70 dias da cirurgia, foi realizada a eutanásia dos animais e retirada dos aloenxertos para avaliação mecânica. O segundo grupo (controle) foi composto por seis meniscos mediais, retirados dos joelhos contralaterais (direito) dos mesmos animais. Para a amostra estudada, não houve diferença estatisticamente significante entre os grupos controle e tratado para nenhuma das variáveis analisadas, demonstrando que a reidratação de aloenxertos meniscais, após preservação em glicerina, mantém as características mecânicas desses, após 70 dias de implantação, semelhantes às de meniscos frescos.

We evaluated the mechanical properties, strength, strain and stress to the elastic limit, the rupture stress point and stiffness index of fresh menisci and menisci transplanted for 70 days in the knees of rabbits after preservation in glycerin. The first group (treated) was formed by six medial menisci of the left knee, collected from these animals for commercial breeding. These menisci were stored in 98% glycerin for a period of 30-60 days, and then rehydrated in a solution in 0.5% saline enrofloxacin for 12 hours, and implanted in the knees of another six rabbits underwent meniscectomy . After 70 days of surgery was performed the euthanasia of animals and removal of allografts for mechanical evaluation. The second group (control) consisted of six medial menisci, removed from the contralateral knees (right) of the same animals. For the sample studied, had no statistically significant difference between control and treated groups for any of the variables analyzed, showing that the rehydration of meniscal allografts after preservation in glycerin keeps the mechanical characteristics of these, after 70 days of implantation, similar to the meniscus fresh.

Diferenciação de células-tronco mesenquimais derivadas do tecido adiposo em cardiomiócitos / Differentiation of adipose tissue-derived mesenchymal stem cells into cardiomyocytes

FUNDAMENTO: O potencial de renovação e proliferação dos cardiomiócitos, in vivo, é pequeno, e por isso, o músculo cardíaco apresenta limitada capacidade de repor células perdidas. Na tentativa de minimizar os danos oriundos de lesões hipóxico-isquêmicas e daquelas que acometem o sistema de condução do coração, a terapia celular com células-tronco mesenquimais (MSC) vem sendo utilizada, inclusive com cardiomiócitos diferenciados a partir de MSC. OBJETIVO: O presente trabalho comparou três protocolos distintos de indução de diferenciação objetivando a sugestão de um método viável para a diferenciação de maior número de células funcionais que expressem fenótipo cardiomiogênico. MÉTODOS: Culturas de MSC obtidas de tecido adiposo de ratos jovens da linhagem Lewis transgênicos para proteína verde fluorescente (GFP) foram submetidos a três diferentes meios de diferenciação cardiogênica: Planat-Bérnard, 5-azacitidina e meio Planat-Bérnard + 5-azacitidina e observadas quanto a expressão de marcadores celulares cardíacos. RESULTADOS: Nos três protolocos utilizados observou-se formação da proteína alfa-actinina sarcomérica no citoesqueleto das células submetidas à diferenciação, expressão de conexina 43 na membrana nuclear e citoplasmática e formação de gap junctions, necessárias para a propagação do impulso elétrico no miocárdio, contudo, em nenhum protocolo foi observada contração espontânea das células submetidas à diferenciação cardiogênica. CONCLUSÃO: A indução com 5-azacitidina proporcionou diferenciação celular cadiomiogênica efetiva e similar à encontrada com o meio Planat-Bénard e, por ser um protocolo mais simples, rápido e com menor custo torna-se o método de eleição.

BACKGROUND: Cardiomyocytes have small potential for renovation and proliferation in vivo. Consequently, the heart muscle has limited capacity of self-renewal. Mesenchymal stem cells (MSC) therapy, as well as MSC differentiated into cardiomyocytes, has been used in the attempt to minimize the effects of ischemic-hypoxic lesions and those affecting the electrical conduction system of the heart. OBJECTIVE: The present study compared three distinct protocols for induced differentiation of MSC into cardiomyocytes aimed at finding a viable method for producing a large number of functional cells expressing cardiomyogenic phenotype. METHODS: Mesenchymal stem cells were obtained from the adipose tissue of young transgenic Lewis rats expressing green fluorescent protein (GFP), and submitted to three distinct differentiation-inducing media: 1) Planat-Bérnard, 2) 5-azacytidine, and 3) Planat-Bérnard + 5-azacytidine; further, these cells were identified based on the expression of cardiac cell markers. RESULTS: All three protocols detected the expression of sarcomeric-alpha-actinin protein in the exoskeleton of cells, expression of connexin-43 in the nuclear and cytoplasmic membrane, and formation of gap junctions, which are necessary for electrical impulse propagation in the myocardium. However, no spontaneous cell contraction was observed with any of the tested protocols. CONCLUSION: Induction with 5-azacytidine provided an effective cadiomyogenic cellular differentiation similar to that obtained with Planat-Bénard media. Therefore, 5-azacytidine was the method of choice for being the simplest, fastest and lowest-cost protocol for cell differentiation.

Imobilização articular prolongada e remobilização / Prolonged articular immobilization and remobilization

Foram avaliados os aspectos clínicos e morfofisiológicos da articulação do joelho de ratos após imobilização prolongada e remobilização com atividade livre e natação. Trinta e quatro ratos adultos machos (Wistar) foram alocados aleatoriamente em um dos quatro grupos: sem imobilização (G1, n = 4, grupo controle), com imobilização (G2, n = 10), imobilização e remobilização com atividade livre (G3, n = 10), imobilização e remobilização com atividade livre e natação (G4, n = 10). A imobilização degenerou as células sinoviais, em relação ao controle, indicando diminuição da produção de fluido sinovial e redução do suprimento nutricional à cartilagem e, tanto a atividade livre na gaiola quanto sua associação com a natação influenciaram positivamente o retorno das condições morfológicas da cápsula, anteriores à imobilização.

The aim of this study was to evaluate the clinical and morphophysiological aspects of the rat knee articulation after immobilization and remobilization with free activity and swimming. Thirty four adult male rats (Wistar) were randomly allocated into one of four groups: without immobilization, (G1, n = 4, control group), with immobilization (G2, n = 10), immobilization and remobilization with free activity (G3, n = 10), and immobilization and remobilization with free activity and swimming (G4, n = 10). Synovial cells were degenerated by immobilization indicating decreased synovial fluid production and reduced nutritional supplying to the cartilage and both free cage activity and its association with swimming influenced positively the return of the capsule morphologic conditions to those before immobilization.