RESUMEN
BACKGROUND: Muscle fiber regeneration is essential to maintain normal muscle fiber populations and muscle mass by continuous replacement of fibers lost to acute muscle injury or overuse. However, the extent of ongoing muscle fiber regeneration in the laryngeal muscles is unknown. OBJECTIVE: The present study provides statistically unbiased, quantitative estimates of the content of regenerating fibers in the human thyroarytenoid muscle over the adult lifespan. DESIGN: In the adult, only regenerating muscle fibers express the developmental myosin isoform. Therefore, regenerating fibers were identified using immunohistochemical techniques. The content of regenerating muscle fibers in the entire muscle volume was then estimated using stereological techniques. Through the use of a computer-automated sampling protocol, stereological data were collected from sets of isotropic uniform random cryostat sections. Overprojection error was minimized by using a confocal laser-scanning microscope to image thin optical sections for use as sample fields. SUBJECTS: Eight autopsy cases, subjects ranging in age from 19 to 81 years. RESULTS: The summed length of fibers expressing developmental myosin increased significantly (P=.02) with age when compared with the overall muscle fiber length. CONCLUSIONS: This finding indicates that muscle fibers maintain the capability for spontaneous regeneration, and that the proportion of regenerating fibers increases as the thyroarytenoid muscle ages. This increase is possibly a compensatory response to an age-related increase in muscle fiber injury or death.
Asunto(s)
Músculos Laríngeos/fisiología , Fibras Musculares Esqueléticas/fisiología , Regeneración/fisiología , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Inmunohistoquímica , Masculino , Persona de Mediana EdadRESUMEN
The quest for nasal symmetry and balance with the face often mandates the need for implantable materials to sculpt and rebuild the nasal skeleton and the overlying tissues. A suitable implant must be biocompatible, strong, and elastic. Implant materials that may be used in the nose can be divided into four groups: autografts, homografts, xenografts, and alloplasts. Each type of implant is reviewed and discussed in the context of rhinoplasty and nasal reconstruction.
Asunto(s)
Cartílago/trasplante , Prótesis e Implantes , Rinoplastia/métodos , Materiales Biocompatibles , Humanos , Trasplante Autólogo , Trasplante HomólogoRESUMEN
BACKGROUND: When performing septorhinoplasty, deviated segments of septal cartilage can be straightened using cartilage or bone as splinting grafts. In some cases, autologous material is not available without an additional surgical procedure to harvest cartilage or bone. It is possible that resorbable plates can be used to splint and straighten deviated cartilage. Experience using bioresorbable rigid fixation devices on cartilage has been limited. OBJECTIVE: To examine early histopathologic changes of rabbit ear cartilage and adjacent soft tissue following implantation with bioresorbable plates. DESIGN: Nonrandomized, placebo-controlled trial. SUBJECTS: Twelve adult New Zealand white rabbits. MATERIALS AND METHODS: Ten adult New Zealand white rabbits (20 ears) underwent stenting of intact ear cartilage with LactoSorb plates (Lorenz, Jacksonville, Fla). Rabbits were killed 28 days after implantation, and the soft tissue, plates, and cartilage were harvested and prepared for histological examination. As controls, 2 rabbits (4 ears) underwent dissection and closure without stenting. RESULTS: Six rabbits experienced superficial skin breakdown on the ventral surface of the ear caused by excessive wound tension of the implant. The cartilage-plate interface and the surrounding soft tissues stenting the dorsal side of the ear remained free of inflammation or necrosis for all animals. Simple elevation of the perichondrium revealed no differences in the appearance of the cartilage between the control and test rabbits. CONCLUSIONS: Resorbable plates have no deleterious effects on cartilage during the first month of implantation. While short-term studies have documented the safety and efficacy of using bioresorbable plates, further studies are recommended.