RESUMO
BACKGROUND: No human model has emerged as an accepted standard to evaluate tissue filler longevity. OBJECTIVES: To validate a human model adequate to compare soft tissue filler degradation and tissue reaction. MATERIALS AND METHODS: We evaluated in 18 patients the persistence of hyaluronic acid (HA) filler injected into labial tissue analyzing hyaluronidase (HYAL) activity by means of in vitro and in vivo tests, MRI and histological and ultra-structural examination at 3 and 6 months postop. RESULTS: MRI examination revealed the presence of HA filler in a clear hyperintense area. Histology demonstrated fibroblast activation. The amount and the degradation rate of HYAL and HA did not show a linear correlation. CONCLUSION: MRI demonstrated the presence of HA in lip tissue even after 6 months. Biopsies at 3 months revealed tissue maturation and at 6 months confirmed the ability of HA to reorganize and integrate the extracellular matrix. The absence of linear correlation between HYAL and HA revealed that the result clinically is probably dependent on systemic factors which can determine HYAL activity and therefore HA longevity.
Assuntos
Fármacos Dermatológicos/farmacologia , Ácido Hialurônico/farmacologia , Hialuronoglucosaminidase/metabolismo , Lábio/efeitos dos fármacos , Adulto , Técnicas Cosméticas , Fármacos Dermatológicos/metabolismo , Fármacos Dermatológicos/farmacocinética , Ativação Enzimática/efeitos dos fármacos , Humanos , Ácido Hialurônico/metabolismo , Ácido Hialurônico/farmacocinética , Lábio/enzimologia , Lábio/ultraestrutura , Imageamento por Ressonância Magnética , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Modelos Biológicos , FotografaçãoRESUMO
Osmolality is the primary determinant of water movement across the intact blood-brain barrier (BBB), and we can predict that reducing serum osmolality would increase cerebral oedema and intracranial pressure. Brain injury affects the integrity of the BBB to varying degrees. With a complete breakdown of the BBB, there will be no osmotic/oncotic gradient, and water accumulates (brain oedema) consequentially to the pathological process. In regions with very moderate BBB injury, the oncotic gradient may be effective. Finally, osmotherapy is effective in brain areas with normal BBB; hypertonic solutions (mannitol, hypertonic saline) dehydrate normal brain tissue, with a decrease in cerebral volume and intracranial pressure. In patients with brain pathology, volume depletion and/or hypotension greatly increase morbidity and mortality. In addition to management of intravascular volume, fluid therapy must often be modified for water and electrolyte (mainly sodium) disturbances. These are common in patients with neurological disease and need to be adequately treated.