Comparative study of decellularization techniques to obtain natural extracellular matrix scaffolds of human peripheral-nerve allografts.

BACKGROUND: We hypothesize that adding sonication cycles to the process of decellularization of cadaveric human peripheral nerves will increase the removal of cell debris and myelin sheath, increasing their utility as allografts. METHODS: Our aim of this study was to develop a decellularization protocol that allows the removal of cells and myelin sheath without detrimental effects on nerve architecture. Segments of ulnar and median nerves from human donors, isolated both before and after cardiac arrest, were subjected to two methods of decellularization: two-detergent-based (M1) and the same method with sonication added (M2). We evaluated the histology of unprocessed and decellularized nerves (n = 24 per group) for general morphology, presence of cell nuclei, nuclear remnants, collagen fibers, and myelin. We performed immunohistochemistry to verify the removal of Schwann cells associated with histomorphometry. We used scanning electron microscopy (EM) to evaluate the ultrastructure of both native and decellularized nerves. The efficacy of decellularization was assessed by analysis of genomic DNA. RESULTS: Histology confirmed that both decellularization protocols were adequate and maintained natural nerve architecture. Scanning EM showed that 3D ultrastructural architecture also was maintained. Histomorphometric parameters showed a more complete removal of the myelin with the M2 protocol than with M1 (p = 0.009). Fiber diameter and density were not modified by decellularization methods. CONCLUSIONS: Sonication can be a complementary method to decellularization of peripheral nerve allografts with sonication increasing the effectiveness of detergent-based protocols for the removal of unwanted cellular components from peripheral nerve allografts.

Caracterização de estafilococos encontrados em dinheiro brasileiro coletado em ambiente hospitalar / Characterization of staphylococcus found in brasilian money collected in hospital environment hospital

S. aureus, S. epidermidis e S. saprophyciticus são as principais espécies do gênero Staphylococcus para as áreas relacionadas à saúde. Distinguem-se porque são onipresentes e potencialmente patogênicas. Ademais, têm apresentado resistência a medicamentos em número crescente de casos. Os objetivos dos autores são examinar a colonização por Staphylococcus do dinheiro brasileiro coletado em ambiente hospitalar; identificar aquelas três espécies; e determinar a sensibilidade ou resistência das cepas de S. aureus à penicilina G, oxacilina, eritromicina, sulfa, clindamicina e vancomicina. Concluíram que o dinheiro pode ser um reservatório de bactérias, inclusive das do gênero Staphylococcus. Esta é uma das razões por que práticas de higiene e controle de infecções, como a lavagem das mãos com sabão comum ou detergente, têm importância particular no ambiente nosocomial