Probiotics are formulations containing live microorganisms or microbial stimulants that have some beneficial influence on the maintenance of a balanced intestinal microbiota and on the resistance to infections. The search for probiotics to be used in prevention or treatment of enteric infections, as an alternative to antibiotic therapy, has gained significant impulse in the last few years. Several studies have demonstrated the beneficial effects of lactic acid bacteria in controlling infection by intestinal pathogens and in boosting the hosts nonspecific immune response. Here, we studied the use of Lactobacillus acidophilus UFV-H2b20, a lactic acid bacterium isolated from a human newborn from Viçosa, Minas Gerais, Brazil, as a probiotic. A suspension containing 10 8 cells of Lactobacillus acidophilus UFV-H2b20 was inoculated into groups of at least five conventional and germfree Swiss mice to determine its capacity to stimulate the host mononuclear phagocytic activity. We demonstrate that this strain can survive the stressing conditions of the intestinal tract in vivo. Moreover, the monoassociation of germfree mice with this strain for seven days improved the hosts macrophage phagocytic capacity, as demonstrated by the clearance of a Gram-negative bacterium inoculated intravenously. Monoassociated mice showed an undetectable number of circulating E. coli, while 0.1% of the original inoculum was still present in germfree animals. Mice treated with viable or heat-killed Lactobacillus acidophilus UFV-H2b20 presented similarly improved clearance capacity when compared with germfree controls. In addition, monoassociated mice had twice the amount of Kupffer cells, which are responsible for the clearance of circulating bacteria, compared to germfree controls. These results suggest that the L. acidophilus strain used here stimulates a nonspecific immune response and is a strong candidate to be used as a probiotic.

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Single application of glycine in a final dose of 40 mg/kg to the surface of the parietal area of rat brain produced a potent vasodilatory effect. The diameter of arterioles increased to 250% from the baseline level 1-3 min after treatment. These changes persisted for 5-10 min. In the follow-up period the diameter of vessels progressively decreased to the baseline level. Repeated application of glycine in the same dose also induced dilation of arterioles. Application of physiological saline under similar conditions did not produce these changes.

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Model experiments on biomicroscopy of mesenteric microvessels in laboratory rats were performed to evaluate the effect of natural metabolites (e.g., amino acid glycine) on the microcirculation. The effect of glycine was determined from a change in the diameter of arterioles. Application of glycine (0.1 ml, 1 M) to the mesenteric surface was followed by arteriolar dilation (by 50-80%). Histamine-induced disturbances in the microcirculation were not observed after preapplication of glycine. Under these conditions, pretreatment with histamine was accompanied by reversible changes. Our results suggest that the natural metabolite glycine has a prophylactic and therapeutic effect on microcirculatory disturbances, which are induced by inflammatory-and-allergic mediator histamine.