Although the pathogenesis of ischemia reperfusion (IR) injury is based on complex mechanisms, free radicals play a central role. We evaluated membrane fluidity and lipid peroxidation during pancreas transplantation (PT) performed in 12 pigs (six donors and six recipients). Fluidity was measured by fluorescence spectroscopy, and malondialdehyde (MDA) and 4-hydroxyalkenals (4-HDA) concentrations were used as an index of lipid oxidation. Pancreatic tissues were collected as follows: (A) donor, immediately before vascular clamping; (B) graft, following perfusion lavage with University of Wisconsin preservation fluid; (C) graft, after 16 h of cold ischemia; and (D) recipient, 30 min vascular postreperfusion. Fluidity and MDA and 4-HDA concentrations were similar in cases A, B, and C. However, there was significant membrane rigidity and increased lipid peroxidation after reperfusion (D). These findings suggest that reperfusion exaggerates oxidative damage and may account for the rigidity in the membranes of allografts during PT.
The liver stem cell niche is a specialized and dynamic microenvironment with biomechanical and biochemical characteristics that regulate stem cell behavior. This is feasible due to the coordination of a complex network of secreted factors, small molecules, neural, blood inputs and extracellular matrix (ECM) components involved in the regulation of stem cell fate (self-renewal, survival, and differentiation into more mature phenotypes like hepatocytes and cholangiocytes). In this review, we describe and summarize all the major components that play essential roles in the liver stem cell niche, in particular, growth factor signaling and the biomechanical properties of the ECM.
La lipomatosis del ciclista, también llamada induración nodular perineal del ciclista, es una entidad benigna poco frecuente. Aunque desconocida por la mayoría de los cirujanos, es más conocida por especialistas en medicina deportiva y por los propios deportistas profesionales y aficionados. Consiste en una lipomatosis simétrica bilateral en la zona isquiática, que frecuentemente resulta dolorosa al tacto, lo que dificulta e incluso imposibilita la práctica deportiva. Presentamos el caso clínico de un varón de 48 años, aficionado al ciclismo, que consultó porque las molestias que le producía le imposibilitaban la práctica del ciclismo. Se realizó una exéresis quirúrgica de las dos tumoraciones, pudiendo retomar la práctica de su deporte habitual a los 3 meses. El tratamiento de la lipomatosis del ciclista mediante resección quirúrgica de las tumoraciones es una técnica eficaz que permite la total recuperación del paciente.
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