Poor bioavailability of vitamin D from ultraviolet-irradiated D-rich yeast in rats.

Ultraviolet-irradiated yeast (Saccharomyces cerevisiae) can be used to biofortify bakery products with vitamin D, but in bread, it was not effective in increasing serum 25-hydroxyvitamin D [25(OH)D] in humans, possibly because of the low digestibility of the yeast matrix. We investigated the effects of vitamin D-rich intact yeast cells and their separated fraction, yeast cell walls, which we hypothesized to provide vitamin D in a more bioavailable form, on serum 25(OH)D and its metabolites in growing female Sprague-Dawley rats (n = 54) compared to vitamin D and D supplements (8 treatment groups: 300 or 600 IU vitamin D/d, and a control group, 8-week intervention). The D supplement groups had the highest 25(OH)D concentrations, and the vitamin D supplement at the 600-IU dose increased 25(OH)D better than any yeast form (P < .

An adult zebrafish model for preclinical tuberculosis vaccine development.

Tuberculosis remains a major global health challenge despite extensive vaccination schemes with the current live vaccine, Bacillus Calmette-Guérin. Tuberculosis vaccine research has been hampered by a scarcity of animal models which replicate human disease and are suitable for large-scale studies. We have shown recently that Mycobacterium marinum, a close relative of Mycobacterium tuberculosis, causes an infection resembling human tuberculosis in adult zebrafish (Danio rerio).

Mycobacterium marinum causes a latent infection that can be reactivated by gamma irradiation in adult zebrafish.

The mechanisms leading to latency and reactivation of human tuberculosis are still unclear, mainly due to the lack of standardized animal models for latent mycobacterial infection. In this longitudinal study of the progression of a mycobacterial disease in adult zebrafish, we show that an experimental intraperitoneal infection with a low dose (≈ 35 bacteria) of Mycobacterium marinum, results in the development of a latent disease in most individuals. The infection is characterized by limited mortality (25%), stable bacterial loads 4 weeks following infection and constant numbers of highly organized granulomas in few target organs.