RESUMO
Skeletal muscle, the major processor of dietary glucose, stores it in myriad glycogen granules. Their numbers vary with cellular location and physiological and pathophysiological states. AI models were developed to derive granular glycogen content from electron-microscopic images of human muscle. Two UNet-type semantic segmentation models were built: "Locations" classified pixels as belonging to different regions in the cell; "Granules" identified pixels within granules. From their joint output, a pixel fraction pf was calculated for images from patients positive (MHS) or negative (MHN) to a test for malignant hyperthermia susceptibility. pf was used to derive vf, the volume fraction occupied by granules. The relationship vf (pf) was derived from a simulation of volumes ("baskets") containing virtual granules at realistic concentrations. The simulated granules had diameters matching the real ones, which were measured by adapting a utility devised for calcium sparks. Applying this relationship to the pf measured in images, vf was calculated for every region and patient, and from them a glycogen concentration. The intermyofibrillar spaces and the sarcomeric I band had the highest granular content. The measured glycogen concentration was low enough to allow for a substantial presence of non-granular glycogen. The MHS samples had an approximately threefold lower concentration (significant in a hierarchical test), consistent with earlier evidence of diminished glucose processing in MHS. The AI models and the approach to infer three-dimensional magnitudes from two-dimensional images should be adaptable to other tasks on a variety of images from patients and animal models and different disease conditions.
Assuntos
Glicogênio , Músculo Esquelético , Humanos , Glicogênio/metabolismo , Músculo Esquelético/metabolismo , Músculo Esquelético/diagnóstico por imagem , Inteligência Artificial , Microscopia Eletrônica/métodosRESUMO
Introducción Las fracturas del platillo tibial posterolateral exigen un abordaje que permita una buena visualización de la superficie articular para su restitución anatómica, restablecimiento de la altura y un espacio adecuado para la aplicación del material de osteosíntesis y fijación estable. Hay diversos abordajes descritos en la literatura que no proporcionan la visualización deseada o conllevan múltiples limitaciones y/o complicaciones. El propósito de este estudio es describir una modificación a la técnica quirúrgica de la osteotomía de la fíbula para el manejo de las fracturas de platillo tibial posterolateral. Materiales y métodos Se presentan los resultados clínicos de una serie de casos retrospectiva de 15 pacientes con fracturas de platillo tibial posterolateral que al momento del estudio tenían un seguimiento promedio de 6 meses. Resultados Los resultados funcionales en escala de Lysholm fueron excelentes en 3 pacientes, buenos en 8 y regulares en 4. En todos los pacientes se logró una reducción satisfactoria de la superficie articular de la tibia, sin pérdida de altura de la misma, con alineación adecuada, sin síntomas de inestabilidad, todos con consolidación de la fíbula que no retrasó la rehabilitación, no hubo lesiones del nervio peroneal ni problemas con la piel; se presentó un caso de infección superficial que se manejó con antibióticos orales sin complicaciones. Discusión El abordaje descrito facilita una amplia exposición de la superficie articular, es técnicamente fácil y reproducible, permite la reducción y fijación necesaria, con menor riesgo de complicaciones, con la cual se conserva el aporte vascular de la tibia proximal, se evita el daño a la articulación tibiofibular proximal y se propicia una mayor área de consolidación de la osteotomía. Ésta técnica puede utilizarse sola o en combinación con otros abordajes, para fracturas agudas o crónicas con mala unión. Consideramos que el abordaje con la técnica descrita es una alternativa para el manejo de las fracturas posterolaterales, con resultados alentadores.
Background Fractures of the posterolateral tibial plateau require an approach that allows a good visualization of the articular surface for its anatomical restitution, restoration of height and an adequate space for the application of osteosynthesis material and stable fixation. There are several approaches described in the literature that do not provide the desired visualization or involve multiple limitations and / or complications. The purpose of this study is to describe a modification to the surgical technique of the fibula osteotomy for the management of posterolateral tibial plate fractures. Methods We present the clinical results of a retrospective case series of 15 patients with posterolateral tibial plate fractures that at the time of the study had an average follow-up of 6 months. Results Functional results in Lysholm scale were excellent in 3 patients, good in 8 and regular in 4. Good results were obtained in all patients with a reduction of the tibia articular surface, without loss of height of the same, with alignment adequate, without symptoms of instability, all with consolidation of the fibula that did not delay rehabilitation, there were no peroneal nerve injuries or problems with the skin; There was a case of superficial infection that was managed with oral antibiotics without complications. Discussion The described approach facilitates a broad exposure of the articular surface, is technically easy and reproducible, allows the necessary reduction and fixation, with a lower risk of complications, with which the vascular supply of the proximal tibia is conserved, the damage is avoided to the proximal tibiofibular joint and a greater area of consolidation of the osteotomy is favored. This technique can be used alone or in combination with other approaches, for acute or chronic fractures with poor union. We consider that the approach with the described technique is an alternative for the management of posterolateral fractures, with encouraging results.
Assuntos
Humanos , Joelho , Procedimentos Cirúrgicos Operatórios , Fraturas ÓsseasRESUMO
Here we compare excitation-contraction coupling in single muscle cells of frogs and rats. Because amphibians have isoform 3 (or b) of the ryanodine receptor/Ca2+ release channel, in addition to 1 (a), which is also present in the mammal, any extra feature present in the frog may in principle be attributed to isoform 3. Ca2+ release under voltage clamp depolarization has a peak and a steady phase in both taxonomic classes, but the peak is more marked in the frog, where the ratio of amplitudes of the two phases is voltage-dependent. This dependence is a hallmark of CICR. Confocal imaging identified Ca2+ sparks in the frog, but not in the voltage-clamped rat cells. Because Ca2+ sparks involve CICR both observations indicate that the contribution of CICR is minor or null in the mammal. The "couplon" model well accounts for observations in the frog, but assumes a structure that we now know to be valid only for the rat. A revised model is proposed, whereby the isoform 3 channels, located parajunctionally, are activated by CICR and contribute its characteristic global and local features. Several issues regarding the roles of different channels remain open to further study.
Assuntos
Animais , Ratos , Cálcio/metabolismo , Canal de Liberação de Cálcio do Receptor de Rianodina/fisiologia , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Contração Muscular/fisiologia , Retículo Sarcoplasmático/fisiologia , Anuros , Isoformas de Proteínas/fisiologia , Modelos Biológicos , Potenciais da Membrana/fisiologia , Especificidade da Espécie , Sinalização do Cálcio/fisiologiaRESUMO
Los A.A. han ideado unas zapatas movibles que permiten transformar cualquier cama de una plaza en oscilante. Esto permite prevenir las úlceras por presión y demás complicaciones