L-Valine

PURPOSE: ;The aim of this study was to evaluate which amino acid(s) among the 20 standard protein amino acids is indispensable for the survival of cultured human corneal endothelial cells (HCECs).;METHODS: ;HCECs were cultured in amino acid screening media that were missing 1 specific amino acid, and cell growth was evaluated. After this first selection, we conducted a further evaluation of cell growth in response to the addition of 4 amino acids (cysteine, methionine, valine, and arginine) to amino acid-free culture media. We then evaluated the antioxidant effect of cysteine compared with other antioxidants in terms of apoptosis of HCECs, rabbit corneal endothelial cell (CECs), monkey CECs, and ex vivo human donor corneas.;RESULTS: ;Culture in an amino acid-free Dulbecco Modified Eagle Medium (DMEM) decreased the cell numbers to 11.0% when compared with culture in normal DMEM. Removal of cysteine, methionine, valine, or arginine from DMEM significantly suppressed cell numbers (27.7%, 61.4%, 75.5%, and 60.6%, respectively) (P < 0.01), whereas removal of other amino acids did not significantly decrease cell numbers. A lack of cysteine induced apoptosis, but addition of antioxidants reversed this.

This study was conducted to examine the effects of dietary valine on the physical and flavor characteristics, fatty acid (FA) profile, antioxidant status and Nrf2-dependent antioxidant enzyme gene expression in the muscle of young grass carp (Ctenopharyngodon idella) fed increasing levels of valine (4.3, 8.0, 10.6, 13.1, 16.9 and 19.1 g/kg) for 8 weeks. Compared with the control group, the group fed valine showed improved physical characteristics of fish fillets (increased relative shear force, hydroxyproline, protein and lipid levels and decreased cathepsin B and L activities, as well as cooking loss, were observed). Moreover, valine improved the flavor of young grass carp fillets by increasing the amino acid (AA) concentration in fish muscle (increased aspartic acid, threonine, glutamine, cystine, methionine, leucine, tyrosine, phenylalanine, lysine, histidine, arginine and valine concentrations were observed). Additionally, optimal valine supplementation increased the potential health benefits to humans by decreasing the saturated FA (C15:0 and C16:0) concentration and increasing the unsaturated FA (monounsaturated FAs (MUFAs), such as C16:1, C18:1c+t and C20:1, and polyunsaturated FAs (PUFAs), such as C18:3n-3, C20:2 and C22:6) concentration.

Thrombospondin-1 (TSP-1) is a matrix protein implicated in mechanisms of wound healing. TSP-1 contains the sequence cysteine-serine-valine-threonine-cysteine-glycine (CSVTCG) that has been shown to function primarily as a cell adhesion domain. Our laboratory has isolated a novel receptor specific for the CSVTCG adhesive domain of TSP-1. Immunohistochemical staining techniques and computerized image analysis were used to identify and quantitate TSP-1 and its CSVTCG receptor in surgically created colon anastomotic wounds. Histopathologic and quantitative examination demonstrated increased expression of TSP-1 and its CSVTCG receptor in areas of wound healing. These findings suggest a role for TSP-1 and its CSVTCG receptor in wound healing. The control of expression and activity of these molecules may eventually be the basis for the development of wound healing agents that could significantly reduce the morbidity from surgical intervention.