Efficient Silver Release From Ion Exchange Silver Dressings in Biologically Relevant Media.

INTRODUCTION: Silver-containing wound dressings commonly are used when there is a risk of infection. These commercial antimicrobial silver dressings have various compositions that use different substrates and/or silver sources. Common silver sources are ionic silver (Ag+) and metallic silver (Ag0). A third source of silver is ion exchange silver compounds (Ag+ complex), in which silver ions are encapsulated in an inorganic carrier to moderate the availability of the silver ions and are released via an ion exchange mechanism. OBJECTIVE: In this study, silver release of different types of silver dressings (Ag+, Ag0, Ag+ complex) in biologically relevant media is investigated. MATERIALS AND METHODS: Simulated wound fluid (SWF) and SWF in combination with 5% bovine serum albumin were used as the extraction media. RESULTS: The composition of the extraction media was found to strongly affect the release of silver. The silver released from most silver dressings peaked at ca 0.5 ppm of soluble silver without any protein in the extraction media. Apparent equilibria established between silver and the salts used for SWF were disrupted by the presence of the protein. This resulted in a dramatic increase in silver release over ionic solutions in the absence of the protein. Dressings differed dramatically in their silver release efficiency. The nature of the silver played a more significant role than the silver content in the dressings. CONCLUSIONS: The ion exchange (Ag+ complex) silver dressing was shown to be the most efficient among all the dressings tested for silver release.

Effects of maternal nicotine exposure on branching morphogenesis of mouse fetal lung: in vivo and in vitro studies.

Epidemiological evidence suggests that premature infants born to mothers who smoke have a lower incidence of neonatal respiratory distress syndrome. The mechanism has been proposed to be due to increased lung maturity. This in vivo study investigated the effect of maternal nicotine on lung development by evaluating the airway branching morphogenesis (ABM) in mice fetuses. Nicotine (0, 2 and 3 mg/kg/day) was administered intraperitoneally to pregnant mice from gestation day 9 to day 12 (4 days). ABM was determined on day 13 by photomicrographic analysis. The results revealed a significant reduction in ABM in the higher dose nicotine group. The mean number of airway branches was 3.7 +/- 0.1/lobe for the 3 mg/kg/day group, which was smaller than 4.6 +/- 0.2/lobe for the 2 mg/kg/day nicotine group, and 4.4 +/- 0.1/lobe for the control group (F = 9.4, p < 0.001). The mean number of buds was significantly smaller in both the 2 mg/kg/day group and the 3 mg/kg/day group (8.7 +/- 0.5/lobe, 9.0 +/- 0.4/lobe vs. 12.3 +/- 0.4/lobe in the control group, F = 20.3, p < 0.001). For the in vitro study, fetal lung lobes were isolated at the 12th gestation day. The lung explants were cultured in nicotine (0, 30, 60 ng/ml) for 48 hours; there were no differences in all the groups. The results do not support the hypothesis that nicotine stimulates fetal lung ABM either in vivo or in vitro.