H2S photocatalytic oxidation over WO3/TiO2 Hombikat UV100.

Hydrogen sulfide (H2S) is a toxic, corrosive and malodorous compound with damaging effects even when present at a low concentration in air. Consequently, the development of efficient and environmentally friendly remediation technologies as an alternative to conventional techniques is justified for environmental reasons and public concern over human health and well-being. In the context of indoor air quality control, the use of photocatalysis over semi-conductor oxides could be a valuable alternative purification technology due to its wide-ranging effect and its easy way of implementation. The superiority of the TiO2 Hombikat UV100 photocatalyst in comparison with the Aeroxide© TiO2 P25 standard was already apparent in the UV-A photocatalytic oxidation of H2S. We report here on the first use of WO3/TiO2 UV100 photocatalysts for this reaction. Associating WO3 to TiO2 UV100 was not beneficial in terms of semiconductor coupling and of charge transfer between both phases. Even if such coupled wide band-gap oxide semi-conductor photocatalysts suffered from on-flow deactivation due to the formation of poisoning sulfates as ultimate reaction products continuously stored at the surface, by contrast, their ability to strongly lower and delay the release of SO2 to the gas phase was very positive for maintaining a weak selectivity into the unwanted SO2 by-product.

Milk fat globule membrane isolate induces apoptosis in HT-29 human colon cancer cells.

A native milk fat globule membrane (MFGM) isolate obtained from raw milk was assessed for its anticarcinogenic capacity using a colon cancer cell line (HT-29). To prevent microbial contamination and eliminate the presence of lipopolysaccharide (LPS) in the milk used for MFGM isolation, the milk was obtained from the mammary glands of cows using a catheter. Cell proliferation assays demonstrated a reduction of exponentially growing cancer cells of up to 53%, expressed as DNA synthesis (BrdU test), after 72 h stimulation with 100 µg of MFGM protein per mL. Using a similar MFGM concentration, the sulforhodamine B assay resulted in 57% reduction of cell density after 48 h incubation. This bioactivity was comparable to that of known anticancer drugs, 0.1 mM melphalan and 20 µM C2-ceramide, which achieved a cell division reduction of 25 and 40%, respectively, under the same experimental conditions. The toxic effect of the MFGM extracts on HT-29 cells was confirmed by the significant reduction in lactate dehydrogenase enzyme (LDH) by the residual viable cells. An increase of caspase-3 activity (up to 26%) led to the conclusion that MFGM has an apoptotic effect on HT-29 cancer cells.

Yogurt containing bioactive molecules produced by Lactobacillus acidophilus La-5 exerts a protective effect against enterohemorrhagic Escherichia coli in mice.

An active fraction extracted from Lactobacillus acidophilus La5 cell-free spent medium (LAla-5AF) was incorporated in a dairy matrix and tested to assess its antivirulent effect against enterohemorrhagic Escherichia coli (EHEC). Mice in experimental groups were fed for 4 days with yogurt supplemented with LAla-5AF. On the fifth day, mice were challenged with a single dose (10(7) CFU per mouse) of E. coli O157:H7. The clinical manifestations of the infection were significantly less severe in mice fed the yogurt supplemented with LAla-5AF. EHEC attachment and colonization was attenuated by LAla-5AF. Tumor necrosis factor alpha production was down-regulated, which might indicate a protective effect in the kidney during EHEC infection. To investigate the mechanisms associated with the in vivo effects observed, LAla-5AF was tested by reverse transcription real-time PCR to confirm its effects on the expression of several virulence genes of EHEC O157. The results showed that these fractions were able to down-regulate several virulence genes of EHEC, including stxB2, qseA, luxS, tir, ler, eaeA, and hlyB.

Characterization of immune-active peptides obtained from milk fermented by Lactobacillus helveticus.

The objectives of this research were to confirm the effect of compounds derived from milk fermented by Lactobacillus helveticus (LH-2) on the nonspecific host defence system, and isolate and characterize the active peptides that mediate the immune response. The cell-free supernatant obtained from the fermented milk and its fractions were tested in vitro for immuno-modulating activity using murine macrophages (RAW 264.7 cell line). Cytokine production (Interleukin-6 (IL-6), Tumor Necrosis Factor-alpha (TNF-alpha), and Interleukin-1beta (IL1-beta)), nitric oxide (NO) production and phagocytosis were used as biomarkers. Macrophages stimulated with cell-free supernatant of fermented milk showed higher production of cytokines and NO compared with macrophages stimulated with LPS (Lipopolysaccharide) and a commercial immunomodulator derived from beta-casein (f54-59). Phagocytosis was observed by macrophages stimulated with the supernatant. Two of nine fractions collected from the supernatant using size exclusion chromatography produced the highest response when used to stimulate macrophages. The results of the dose-response study of the effect of the fraction with the highest stimulation effect on the production of TNF-alpha showed a direct correlation between protein concentration and TNF-alpha release. The fraction contained four novel peptides, three derived from the hydrolysis of beta-casein and one from the hydrolysis of alpha-lactalbumin. These results confirm that fermentation of milk by Lactobacillus helveticus (LH-2) results in the production of specific peptides capable of modulating macrophage activity.