RESUMO
Silver (Ag) coatings have been incorporated into many medical materials due to its ability to eradicate harmful microbes. In this study, glass microspheres (SiO2-Na2O-CaO-Al2O3) were synthesized and employed as substrates to investigate the effect Ag coating has on glass solubility and the subsequent biological effects. Initially, glasses were amorphous with a glass transition point (T(g)) of 605â and microspheres were spherical with a mean particle diameter of 120 µm (±27). The Ag coating was determined to be crystalline in nature and its presence was confirmed using scanning electron microscopy and X-ray photoelectron spectroscopy. Ion release determined that Ag-coated (Ag-S) microspheres increased the Na(+) release rate but slightly reduced the Ca(2+) and Si(4+) release compared to an uncoated control (UC-S). Additionally, the Ag-S reduced the pH to just above neutral (7.3-8.5) compared to the UC-S (7.7-9.1). Antibacterial testing determined significant reductions in planktonic Escherichia coli (p = 0.000), Staphylococcus epidermidis (p = 0.000) and Staphylococcus aureus (p = 0.000) growth as a function of the presence of Ag and with respect to maturation (1, 7, and 30 days). Testing for toxicity levels using L929 Fibroblasts determined higher cell viability for the Ag-S at lower concentrations (5 µg/ml); in addition, no significant reduction in cell viability was observed with higher concentrations (15, 30 µg/ml).
Assuntos
Antibacterianos/química , Materiais Revestidos Biocompatíveis/química , Vidro/química , Prata/química , Antibacterianos/farmacologia , Infecções Bacterianas/prevenção & controle , Linhagem Celular , Materiais Revestidos Biocompatíveis/farmacologia , Escherichia coli/efeitos dos fármacos , Humanos , Microesferas , Prata/farmacologia , Solubilidade , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus epidermidis/efeitos dos fármacos , Difração de Raios XRESUMO
In 330 consecutive anesthetics administered over a period of 24 months, an improved method of upper extremity intravenous regional anesthesia, entitled "the second wrap technique," included wrapping the extremity a second time with a Martin rubber bandage after the extremity was prepared and draped. In addition, a Penrose drain tourniquet often was applied during injection of the 0.5% lidocaine. No complications occurred. The technique provides a nearly bloodless operative field, improves the anesthesia, diminishes tourniquet pain, lessens the contraindications, and requires no premedication. The only contraindications are allergy to lidocaine, infection, operating time over 2 hours, and severe hypertension.
