Reformulated meat products protect against ischemia-induced cardiac damage.

The protective effects of the antioxidants present in food are of great relevance for cardiovascular health. This study evaluates whether the extracts from reformulated meat products with a reduction in fat and/or sodium content exert a cardioprotective effect against ischemia-induced oxidative stress in cardiomyocytes, compared with non-meat foods. Ischemic damage caused loss of cell viability, increased reactive oxygen species and lipid peroxidation and decreased the antioxidant activity. Pretreatment for 24 h with digested or non-digested extracts from reformulated meat products led to protection against ischemia-induced oxidative damage: increased cell viability, reduced oxidative stress and restored the antioxidant activity. Similar results were obtained using extracts from tuna fish, but not with the extracts of green peas, salad or white beans. These results suggest that reformulated meat products have a beneficial impact in protecting cardiac cells against ischemia, and they may represent a source of natural antioxidants with benefits for cardiovascular health.

Soluble TNFα receptor type I and hepcidin as determinants of development of anemia in the long-term follow-up of heart failure patients.

BACKGROUND: Anemia is common in patients with chronic heart failure (CHF) and is associated with a worse prognosis. This study aims to identify the biological mechanisms which reflect evolutionary changes in the hemoglobin concentrations in heart failure patients who are still not anaemic. METHODS: Fifty-nine patients (54 ± 14 years, 83% males) with CHF (LVEF 28 ± 10%), who did not have anemia, and had not received any previous transfusions, were included. The parameters studied were: iron metabolism (ferritin, iron, transferrin, soluble transferrin receptor (sTfR), hepcidin); inflammation (C-reactive protein, soluble TNFα receptor I (sTNFRI), interleukin 6); and myocardial stress (NT-proBNP, high sensitivity TnT, growth differentiation factor 15). All parameters were measured on inclusion and 1 year after inclusion. RESULTS: Baseline hemoglobin (g/dL) was 14.7 ± 1.5 and at 1 year of follow-up it showed a significant decrease of -0.4 (RIC: -0.7 to -0.06) (p=0.02). At baseline, only the sTNFRI was a predictor of a decrease in hemoglobin 1 year later (p=0.007). During follow-up, the increase in sTNFRI (p=0.002, r=-0.39) and hepcidin (p=0.006, r=-0.35) were both associated with a decrease in hemoglobin. Similarly, the patients who became anemic (13%) had higher levels of hepcidin (p=0.001) and sTNFRI (p=0.008). The remaining parameters did not show any relationship with the evolution in the hemoglobin. CONCLUSIONS: In CHF patients without anemia, the increase in the inflammatory state (sTNFRI) and the following deterioration in the iron metabolism (hepcidin) were the main determinants of a decrease in hemoglobin and the appearance of anemia in the long term follow-up period.

Variant amino acids in different domains of the human melanocortin 1 receptor impair cell surface expression.

The alpha melanocyte-stimulating hormone receptor (MC1R) is a heptahelical G protein-coupled receptor (GPCR) found in the plasma membrane of melanocytes. By mediating the melanogenic response to melanocortins, MC1R is a major determinant of mammalian pigmentation. The human MC1R gene is unusually polymorphic. Many loss-of-function alleles have been described, but the molecular basis for their functional impairment remains most often unknown. Here we report a study of two natural MC1R loss-of-function variants, Leu93Arg and Arg162Pro, and two artificial mutants, Cys35Ala and a deleted form missing the last five amino acids in the carboxyl tail. When expressed in HEK 293T cells, those mutants neither bound an iodinated hormone analogue nor elicited cAMP increases in response to saturating doses of a superpotent agonist. Cell surface expression of mutant receptors was dramatically decreased respect to the wild type form, in spite of smaller changes in total protein abundances and intracellular stability. Accordingly, aberrant processing with intracellular retention is the most likely cause of loss-of-function for those mutants. Therefore, mutations in virtually any region of the heptahelical protein, including its extracellular N terminus, a transmembrane fragment, intracellular loops or carboxyl terminal cytosolic extension, seem to compromise normal MC1R processing.

The melanocortin-1 receptor carboxyl terminal pentapeptide is essential for MC1R function and expression on the cell surface.

The pigmentary actions of the melanocortins are mediated by the melanocortin-1 receptor (MC1R), a seven transmembrane domains receptor positively coupled to Gs and the cAMP cascade. In order to define the structure-function relationships of potentially relevant domains in MC1R, particularly its C-terminal cytosolic tail, we generated and analyzed several variants with C-terminal deletions, as well as point mutants in selected residues of the human MC1R. We show that the MC1R C-terminal pentapeptide is essential for proper receptor expression on the plasma membrane, and that residues Thr314, Cys315 and Trp317 are at least partially responsible for this effect.

Regulation of ornithine decarboxylase in B16 mouse melanoma cells: synergistic activation of melanogenesis by alphaMSH and ornithine decarboxylase inhibition.

Ornithine decarboxylase (ODC) is the rate-limiting enzyme in the biosynthesis of polyamines, a family of cationic compounds required for optimal cell proliferation and differentiation. Within mammalian melanocytes, the expression of genes regulating cell growth and/or differentiation can be controlled by alpha-melanocyte-stimulating hormone (alphaMSH) and other melanogenesis modulating agents. In the B16 mouse melanoma model, alphaMSH stimulates melanogenesis by upmodulation of tyrosinase (tyr) activity, whereas the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) inhibits melanin synthesis. Therefore, we analyzed the regulation of ODC by these agents, as related to changes in the melanogenic pathway. Treatment of B16 cells with TPA or alphaMSH rapidly stimulated ODC activity. The effect was stronger for TPA and appeared mainly posttranslational. Irreversible inhibition of ODC with the active site-directed inhibitor alpha-difluoromethylornithine (DFMO) did not block TPA-mediated inhibition of tyr. Conversely, prolonged treatment of B16 cells with DFMO stimulated tyr activity by a posttranslational mechanism, probably requiring polyamine depletion. Combination treatment with alphaMSH and DFMO synergistically activated tyr. Therefore, ODC induction is not involved in the melanogenic response of B16 cells to alphaMSH. Rather, increased intracellular concentrations of polyamines following ODC induction might constitute a feedback mechanism to limit melanogenesis activation by alphaMSH.