Hydrogen Peroxide-Dependent Conversion of Nitrite to Nitrate as an Essential Feature of Bovine Milk Catalase, Agricultural Research Organization, Institute of Animal Science, Israel. Nissim Silanikove, Agricultural Research Organization, Institute of Animal Science, Israel., The Veterinary Institute, Israel Gabriel Leitner, The Veterinary Institute, Israel

Scenario of NO cycling and metabolism in mammary secretion ( Free radicals Biol Med, 2005 )

Xanthine dose-dependently enhance the conversion of nitrite to nitrate. Silanikove et al, Journal of Agriculture Chemistry Food Science, 2009 Under the experimental conditions, approximately 40 µM of xanthine are converted to urate via XO within 2 h

Relative changes in lipid oxidation in milk Silanikove et al, Journal of Agriculture Chemistry Food Science, 2009 milk stored for 6 hours in the dark at 4 0 C (A), Effects of catalase inhibitor (B), nitrite (10 mM) (C) and nitrite + catalase (D) inhibitor

Effect of storing raw milk in the dark at 4 0 C with and without catalase inhibitor Silanikove et al, Journal of Agriculture Chemistry Food Science, 2009

Effect of storing raw milk in the dark at 4 0 C with and without catalase inhibitor Silanikove et al, Journal of Agriculture Chemistry Food Science, 2009

Conclusions Regarding the Control of Oxidative Stability in Milk XO and catalase works interactively as an antioxidant system Formation of nitrogen dioxide is a key process in oxidative stress in milk. Thus, controlling this process should improve milk oxidative stability The function of catalase is rate limited by hydrogen peroxide, which is provided by the activity of XO

Effect of LPS: 6 cows served as control, in second set of six cows one of the front and one rear glands were treated with LPS (10 ml with 10 µg/ ml LPS) while the contra-lateral glands served as running control. The cows milk were sampled at -24h, 0 h (before treatment) and 24, 48 and 76 h post- treatment The data were analyzed for the effect of treatment and time at a single gland level

Effect of LPS on milk yield

Effect of LPS on lactose concentration

Effect of LPS on whey proteins concentration

Effect of LPS on proteose peptones concentration

Effect of LPS lactoferrin concentration

Effect of LPS on XO activity and urate concentration

Effect of LPS on LPO activity, nitrite and nitrotyrosine concentrations

Effect of LPS on catalase activity, and nitrate concentrations

Updated scenario of NO-cycling in milk

Novel findings: Effect of LPS on lactate, malate and citrate concentrations

Cytosolic and mitochondrial glycolysis

Lactic acid metabolism

Cytosolic formation of malic acid

Low lactose and high lactic acid in broth media affect the growth of pathogenic type of E coli

The acute conversion of the epithelial cells metabolism from principally mitochondrial-oxidative to principally cytosolic (glycolysis) allows the diversion of metabolic resources normally used to synthesize milk to support the immune system. In turn, the acute increase in the concentration of lactate and malate in milk and the parallel reduction in lactose concentration are probably effective mean in restraining invading E Coli growth. CONCLUSIONS

SPECULTIVE CONCLUSION The main function of PMN under acute inflammation is to backup for the disruption of the epithelial tight junction integrity in order to prevent sepsis and lethality