Mechanism of antibacterial property of micro scale rough surface formed by fine-particle bombarding.

Fine-particle bombardment (FPB) is typically used to modify metal surfaces by bombarding them with fine particles at high speed. FPB is not a coating technique but is used for forming microscale concavities and convexities on a surface. Previously, we reported that an FPB-treated surface showed antibacterial effects; however, the underlying mechanisms remain unclear. We hypothesized that the pitch size of concavity and convexity, and irregular microscale pattern of FPB-treated surfaces might contribute to the antibacterial performance. In this study, we applied FPB to stainless-steel surfaces and evaluated the antibacterial effects of the FPB-treated surfaces based on ISO 22,196:2007. The FPB-treated surfaces exhibited antibacterial activity against Escherichia coli, with an antibacterial activity value (R) of two or more. Furthermore, our experiments suggest that the antibacterial mechanism of the FPB-treated surface can be attributed to increased oxidative stress in bacteria owing to physical stress from the rough surface. The antibacterial effect of FPB-treated surfaces offers an effective measure against drug-resistant bacteria.

The antibacterial activity of FPB-treated surfaces can be attributed to increased oxidative stress induced by physical stress from the FPB-generated rough surface.

Facilitative effects of Eucommia ulmoides on fatty acid oxidation in hypertriglyceridaemic rats.

BACKGROUND: Tea made from Eucommia ulmoides leaves is widely consumed as a health food, since recent studies have revealed various pharmacological effects of the tea, e.g. a hypotriglyceridaemic effect. This study was conducted to elucidate the mechanisms underlying the plasma triglyceride-lowering effect of E. ulmoides leaves. RESULTS: Rats were divided into four groups: a normal group, a group fed a high-fat/high-fructose diet (untreated group) and two groups fed a high-fat/high-fructose diet and E. ulmoides tea (4 or 20 g L(-1) extract, treated groups). Plasma triglyceride concentrations were reduced in treated groups in a dose-dependent manner compared with the untreated group. DNA microarray analysis revealed that genes involved in hepatic α-, ß- and ω-oxidation, mainly related to the peroxisome proliferator-activated receptor α and δ signalling pathway, were up-regulated in the treated group. High-performance liquid chromatography analysis showed that E. ulmoides leaves contain three phytochemicals that make up 60 mg g(-1) of the material and are likely to be the active components. CONCLUSION: This study indicates that the promotion of fatty acid oxidation, probably by the action of phytochemicals, participates in the ameliorative effect of E. ulmoides leaves on hypertriglyceridaemia. These findings provide the scientific evidence for the functionality of E. ulmoides.

Antibacterial effect on microscale rough surface formed by fine particle bombarding.

Fine particle bombarding (FPB) is typically utilized to modify metal surfaces by bombarding them with fine particles at high-speed. The diameters of the particles range from several to tens of micrometers. FPB forms fine microscale concavities and convexities on a surface. As FPB-treated surfaces are widely used in the food industry, the influence of bacteria on their surface must be considered. In this study, we examined the antibacterial activity of microscale rough surfaces formed by FPB. We applied FPB to a stainless-steel surface and evaluated the antibacterial effect of FPB-treated surfaces based on JIS Z 2801 (a modified test method from ISO 22196:2007). Our results indicated that the FPB-treated surfaces (FPB-1 (avg. pitch: 0.72 µm) and FPB-2 (avg. pitch: 3.56 µm)) exhibited antibacterial activity both against Escherichia coli and Staphylococcus aureus.