In-vivo and in-vitro biocompatibility evaluations of silver nanoparticles with antimicrobial activity.

In this study, the biocompatibility and antimicrobial activity of silver nanoparticles (Ag NPs) were evaluated in vitro and in vivo. The cytotoxicity of Ag NPs (average diameter: 2-5 nm) against CHO-K1 cells was determined via WST-8 assay, and their genotoxicity was examined via Salmonella typhimurium reverse mutation assay (Ames test). The acute toxicity and intracutaneous reactivity of Ag NPs were evaluated using animal models of mice and rabbits, respectively. The antibacterial effects of Ag NPs on the Gram (-) bacterial strains of Escherichia coli ATCC 8739 and Pseudomonas aeruginosa ATCC 9027 and on the Gram (+) bacterial strains of Staphylococcus aureus ATCC 6538p and Bacillus subtilius ATCC 6633 were determined by measuring the minimum inhibitory concentrations. The Ag NPs were highly cytotoxic to the L-929 cells at over 2 ppm but were non-cytotoxic at lower than 1 ppm. Moreover, the Ag NPs at 1 ppm or lower did not show genotoxicity, acute toxicity and intracutaneous reactivity. It was also found that the Ag NPs exerted effective antimicrobial activities on both the Gram (-) and (+) bacterial strains within the range from 0.06 to 0.98 ppm for 50% MIC.

Cell-free layer formation in small arterioles at pathological levels of erythrocyte aggregation.

OBJECTIVE: To test our hypothesis that an elevation in the aggregation level of red blood cells found in human pathological conditions will significantly enhance cell-free layer formation in small arterioles. METHODS: Visualization of arteriolar blood flow in rat cremaster muscle was carried out in both normal and reduced flow conditions before and after Dextran 500 infusion to simulate physiological and pathological levels of red blood cell aggregation in humans. RESULTS: Both normalized mean (p < 0.0001) and SD (p < 0.002) of the layer width were significantly enhanced after hyper-aggregation induction in reduced flow conditions (mean pseudoshear rate = 57.3 ± 7.2/sec). Normalized mean and SD of the layer width generally increased with decreasing vessel radius and this effect was most pronounced with hyper-aggregation in reduced flow conditions. The threshold pseudoshear rate at which the layer formation became more pronounced when compared with non-aggregating condition was higher with hyper-aggregation (217/sec) than normal-aggregation induction (139/sec). CONCLUSION: Our findings confirmed the formation of a prominent cell-free layer in the arterioles under higher shear conditions at pathological aggregation levels and this effect became more pronounced in smaller arterioles in normalizing the layer to the vessel radius.

Selective sterilization of Vibro parahaemolyticus from a bacterial mixture by low-amperage electric current.

The objective of this study was to investigate the possibility of using low-amperage electrical treatment (LAET) as a selective bacteriocide. Mixtures containing Escherichia coli, Staphylococcus aureus, and Vibrio parahaemolyticus were treated with different electric current intensities and for different times. The results showed that at 263 mA, treating bacteria for 100 ms eliminated all V. parahaemolyticus colonies. Although LAET reduced the populations of the three microorganisms, V. parahaemolyticus was more injured by LAET than S. aureus and E. coli when treated at the same processing conditions.

Inactivation of Listeria monocytogenes in brine and saline by alternating high-voltage pulsed current.

The inactivating efficiency of alternating high-voltage pulsed (AHVP) current was investigated in brine (20 w/v% NaCl) and saline (0.9 w/v% NaCl) inoculated with 1x 10(7) cells/ml of Listeria monocytogenes. AHVP current at 12 V with 1 pulse completely inactivated L. monocytogenes in brine within 3 ms, while the bacteria in saline were fully inactivated by 10-pulsed electric treatment at 12 V within the same time. Electron microscopic observation demonstrated substantial structural damage of electrically treated L. monocytogenes in brine. These results suggest that AHVP treatment would be effective for the rapid and complete inactivation of L. monocytogenes in brine or saline solution.

The biological activities of (1,3)-(1,6)-beta-d-glucan and porous electrospun PLGA membranes containing beta-glucan in human dermal fibroblasts and adipose tissue-derived stem cells.

In this study, we investigated the possible roles of (1,3)-(1,6)-beta-d-glucan (beta-glucan) and porous electrospun poly-lactide-co-glycolide (PLGA) membranes containing beta-glucan for skin wound healing, especially their effect on adult human dermal fibroblast (aHDF) and adipose tissue-derived stem cell (ADSC) activation, proliferation, migration, collagen gel contraction and biological safety tests of the prepared membrane. This study demonstrated that beta-glucan and porous PLGA membranes containing beta-glucan have enhanced the cellular responses, proliferation and migration, of aHDFs and ADSCs and the result of a collagen gel contraction assay also revealed that collagen gels contract strongly after 4 h post-gelation incubation with beta-glucan. Furthermore, we confirmed that porous PLGA membranes containing beta-glucan are biologically safe for wound healing study. These results indicate that the porous PLGA membranes containing beta-glucan interacted favorably with the membrane and the topical administration of beta-glucan was useful in promoting wound healing. Therefore, our study suggests that beta-glucan and porous PLGA membranes containing beta-glucan may be useful as a material for enhancing wound healing.