Clinically, patients with vitamin B deficiency have high levels of TNF in their cerebrospinal fluid compared to nondeficient control patients. High levels of TNF in the aqueous humour of glaucoma patients have been reported. TNF and TNFR also appear to be upregulated in human glaucomatous optic nerve heads in parallel with the degree of optic nerve degeneration. Experimentally, it was recently found that intravitreal injections of TNF lead to RGC cell death and optic nerve degeneration. It is possible that vitamin B mediates TNF through a superoxidedependent pathway. Overexpression of SOD is known to inhibit apoptosis and render cells impervious to the cytotoxic effects of TNF. One potential mechanism involves superoxide signaling TNF for apoptosis when vitamin B is deficient, based on the recent findings that superoxide is an important molecule for TNF induction in microglia cells. Whether TNF is released predominately from retinal glia or neuronal cells in vitamin B deficiency is worth exploring, and further research would <a href="http://www.targetmol.com/compound/Penciclovir"></a>
elucidate the cellular and molecular relationship between vitamin B, superoxide anion, and TNF.It is possible that increased superoxide anion production due to vitamin B deficiency signals TNF, which will then signal for apoptosis.It is unknown whether TNF is coming from the retinal neuronal cells or retinal glia.These results corroborate previous studies demonstrating a novel role for vitamin B in maintaining cellular redox status, and support the hypothesis that optic neuropathies in patients with vitamin B deficiency may result from a misplaced signal for cell death from excess superoxide generation.Our results have important implications for the ocular health of populations at risk of vitamin B deficiency, most notably the elderly, vegans, and third world populations.Further study examining the prevalence of vitamin B deficiency in patients with optic neuropathies could prove informative for implementing preventative therapy for high risk populations.Journal of neurochemistry. Investigative ophthalmology visual science. Investigative ophthalmology visual science. Free radical biology medicine. Two approaches, each using quantities of dietary cyanocobalamin, were compared; the first was based on whole body retention for dand the second was based on nycthemeral portal net flux of vitamin B.In the first trial, blocks of pigs were formed according to their vitamin B status.Within each block, pig was killed and tissues were sampled for vitamin B determination.The remaining piglets were fed g daily of cyanocobalamin for d.Urine was sampled twice daily, and the pigs were killed and sampled as CONT pigs.The total content of vitamin B in the carcass, urine, and intestinal tract was affected by the dietary treatments. Estimates of dietary vitamin B requirements in postweaning pigs are based on studies carried out before and vary from to gkg.Typical amounts used by the feed industry range between and gkg showed that supplements of and gkg of vitamin B would be required in weaner or growerfinisher pigs, respectively.Moreover, intestinal fate of cyanocobalamin should be investigated fully because growth performance of young pigs was enhanced by at least after a parenteral administration of the vitamin. In the present study, approaches were used to determine bioavailability of quantities of dietary cyanocobalamin in growing pigs.