No abstract

Introduction: Envenomation by Bothrops snakes can produce local pain, edema, hemorrhage and myonecrosis.However, standard antivenom therapy is generally ineffective in neutralizing these effects so that alternative methods of treatment have been investigated. In experimental animals, low-level laser therapy (LLLT) attenuates the local effects of Bothrops venoms, but the benefits of LLLT on muscle function after envenomation are unclear. In this study, we examined the influence of LLLT on the contractile activity of mouse skeletal muscle injected with venom from Bothrops jararaca, the principal cause of snakebite in southeastern Brazil. Methods: Twenty-seven male mice were used. Mice were injected with venom (40 μg in 50 μl) in the right anterior tibialis muscle, after which the muscle tendon was exposed, connected to an isometric transducer and subjected to a resting tension of 1 g. A bipolar electrode was attached to the tibial nerve for electrical stimulation. The mice were randomly allocated to five groups: A -Control (n = 3), B -Venom 3 h (n = 6), C -Venom 9 h (n = 6), D -Venom + Laser 3 h (n = 6), E -Venom + Laser 9 h (n = 6). Results: The two groups that received LLLT post-venom showed improved muscle contraction and contracture in relation to muscle treated with venom alone. Conclusion: These results indicate that LLLT can improve muscle function after damage induced by B. jararaca venom.

Mandibular condyle articular cartilage participates in condylar postnatal growth and is responsible for adaptations to anatomical and/or biomechanical alterations throughout life. In a preliminary study in rabbits, differences were observed in the thickness of the layers of articular cartilage in control animals at 5 and 6 months (generally considered adults for this purpose). This study aimed to describe sagittally sectioned condylar cartilages stained with Picrosirius-hematoxylin in rabbits at 40 days and 5, 6, 8, 13, and 18 months to determine when histological maturity is reached. At 40 days, 5 layers were seen: fibrous, proliferative, transition, maturation, and hypertrophic. Older animals (5–18 months) lacked the transition layer. Fibrous, proliferative, and hypertrophic regions were considered for morphometric analysis. The thickness of the fibrous region did not change during the analyzed period (p = 0.1899). When proliferative and hypertrophic regions and the total thickness of the cartilage were compared, a difference was detected (p < 0.001). The thickness of the proliferative region was greatest at 40 days and decreased at 5 months; however, it increased at 6 months, when it was significantly thicker than at 5, 8, 13, and 18 months. Both the hypertrophic region and the total thickness were thickest at 40 days, intermediate at 5, 6, and 8 months, and thinnest at 13 and 18 months. In summary, our data suggest a physiological period of increased cartilage growth at 6 months. Additionally, rabbits at this age should be avoided in experiments involving condylar cartilage. Finally, 13-month-old rabbits have reached histological maturity of the condylar cartilage.

Á querida orientadora Profa. Dra. Elia Garcia Caldini grande incentivadora e idealizadora deste trabalho. Obrigada pelas horas agradáveis que passamos juntas, quando, com muita paciência, conduziu esse trabalho. À Dra. Maria Claudia Irigoyen, que disponibilizou o Laboratório de Hipertensão Experimental do InCor e sua equipe para as medidas de hemodinâmica, pelos valiosos conselhos. À Dra. Ivana Cinthya de Moraes da Silva, do Laboratório de Hipertensão Experimental do InCor, pelas explicações precisas sobre hemodinâmica e auxílio nas perfusões. À Profa Dra. Olga Maria de Toledo Correa, da Faculdade de Medicina do ABC, que sempre me iniciou na carreira acadêmica, por abrir seu laboratório para a realização das técnicas de microscopia de luz.