Bioequivalence of meat products treated with high pressure processing

The effects of high pressure on the composition of food products have not been evaluated extensively. Since, it is necessary to take in consideration the possible effects in basis to the changes induced in the bio molecules by the application of high pressures. The main effect on protein is the denaturation, because the covalent bonds are not affected; however hydrogen bonding, hydrophobic and intermolecular interactions are modified or destroyed. 1 High pressure can modify the activity of some enzymes. If this is done the proteolysis and lipolysis could be more or less intense and the content of free amino acids and fatty acids will be different. This could be related to the bioavailability of these compounds. Low pressures (100 MPa) have been shown to activate some enzymes (monomeric enzymes). Higher pressures induce loss of the enzyme activity. However some enzymes are very stable (ex. Lipase ~ 600 - 1000 MPa). Lipoxygenase is less stable, and there is little information about the effects on antioxidant enzymes. Other important issue is the influence of high pressure on oxidation susceptibility. This could modify the composition of lipids if the degree of the oxidation would have been higher or lower than in the traditional product. Pressure produces the damage of cell membranes favouring the contact between substrates and enzymes, exposure to oxidation of membrane fatty acids and loos of the efficiency of vitamin E. These effects can also affect to protein oxidation. In this study different compounds were analysed to establish the differences between non-treated and high-pressure treated products.

Reduction of oxidative cellular damage by overexpression of the thioredoxin TRX2 gene improves yield and quality of wine yeast dry active biomass

Background: Wine Saccharomyces cerevisiae strains, adapted to anaerobic must fermentations, suffer oxidative stress when they are grown under aerobic conditions for biomass propagation in the industrial process of active dry yeast production. Oxidative metabolism of sugars favors high biomass yields but also causes increased oxidation damage of cell components. The overexpression of the TRX2 gene, coding for a thioredoxin, enhances oxidative stress resistance in a wine yeast strain model. The thioredoxin and also the glutathione/glutaredoxin system constitute the most important defense against oxidation. Trx2p is also involved in the regulation of Yap1p-driven transcriptional response against some reactive oxygen species. Results: Laboratory scale simulations of the industrial active dry biomass production process demonstrate that TRX2 overexpression increases the wine yeast final biomass yield and also its fermentative capacity both after the batch and fed-batch phases. Microvinifications carried out with the modified strain show a fast start phenotype derived from its enhanced fermentative capacity and also increased content of beneficial aroma compounds. The modified strain displays an increased transcriptional response of Yap1p regulated genes and other oxidative stress related genes. Activities of antioxidant enzymes like Sod1p, Sod2p and catalase are also enhanced. Consequently, diminished oxidation of lipids and proteins is observed in the modified strain, which can explain the improved performance of the thioredoxin overexpressing strain. Conclusions: We report several beneficial effects of overexpressing the thioredoxin gene TRX2 in a wine yeast strain. We show that this strain presents an enhanced redox defense. Increased yield of biomass production process in TRX2 overexpressing strain can be of special interest for several industrial applications.

Review. Characterization and selection of hexaploid wheats containing resistance to Heterodera avenae or Mayetiola destructor introgressed from Aegilops

Cereal cyst nematode (CCN, Heterodera avenae) and Hessian fly (HF, Mayetiola destructor) are two major pests affecting wheat crops worldwide including important cereal areas of Spain. Aegilops ventricosa and Ae. triuncialis were used as donors in a strategy to introduce resistance genes (RG) for these pests in hexaploid wheat (Triticum aestivum L.). Two 42 chromosomes introgression lines have been derived from Ae. ventricosa: H-93-8 and H-93-33 carrying genes Cre2 and H27 conferring resistance to CCN and HF, respectively. Line TR-3531 with 42 chromosomes has been derived from Ae. triuncialis and carries RGs conferring resistance for CCN (Cre7) and for HF (H30). Alien material has been incorporated in lines H-93 by chromosomal substitution and recombination, while in line TR-3531 homoeologous recombination affecting small DNA fragments has played a major role. It has been demonstrated that Cre2, Cre7, H27 and H30 are major single dominant genes and not allelic of other previously described RGs. Biochemical and molecular-biology studies of the defense mechanism triggered by Cre2 and Cre7 have revealed specific induction of peroxidase and other antioxidant enzymes. In parallel to these basic studies advanced lines carrying resistance genes for CNN and/or HF have been developed. Selection was done using molecular markers for eventually «pyramiding» resistance genes. Several isozyme and RAPD markers have been described and, currently, new markers based on transposable elements and NBS-LRR sequences are being developed. At present, two advanced lines have already been included at the Spanish Catalogue of Commercial Plant Varieties.

Mouse hepatic oval cells require Met-dependent PI3K to impair TGF-β-Induced oxidative stress and apoptosis.

We have previously shown that oval cells harboring a genetically inactivated Met tyrosine kinase (Met−/− oval cells) are more sensitive to TGF-β-induced apoptosis than cells expressing a functional Met (Metflx/flx), demonstrating that the HGF/Met axis plays a pivotal role in oval cell survival. Here, we have examined the mechanism behind this effect and have found that TGF-β induced a mitochondria-dependent apoptotic cell death in Metflx/flx and Met−/− oval cells, associated with a marked increase in levels of the BH3-only proteins Bim and Bmf. Bmf plays a key role during TGF-β-mediated apoptosis since knocking down of BMF significantly diminished the apoptotic response in Met-/- oval cells. TGF-β also induced oxidative stress accompanied by NADPH oxidase 4 (Nox4) mRNA up-regulation and decreased protein levels of antioxidant enzymes. Antioxidants inhibit both TGF-β-induced caspase 3 activity and Bmf up-regulation, revealing an oxidative stress-dependent Bmf regulation by TGF-β. Notably, oxidative stress-related events were strongly amplified in Met−/− oval cells, emphasizing the critical role of Met in promoting survival. Pharmacological inhibition of PI3K did impair HGF-driven protection from TGF-β-induced apoptosis and increased sensitivity of Metflx/flx oval cells to TGF-ß by enhancing oxidative stress, reaching apoptotic indices similar to those obtained in Met−/− oval cells. Interestingly, both PI3K inhibition and/or knockdown itself resulted in caspase-3 activation and loss of viability in Metflx/flx oval cells, whereas no effect was observed in Met−/− oval cells. Altogether, results presented here provide solid evidences that both paracrine and autocrine HGF/Met signaling requires PI3K to promote mouse hepatic oval cell survival against TGF-β-induced oxidative stress and apoptosis.

Catalase in fluvial biofilms: a comparison between different extraction methods and example of application in a metal-polluted river

Antioxidant enzymes are involved in important processes of cell detoxification during oxidative stress and have, therefore, been used as biomarkers in algae. Nevertheless, their limited use in fluvial biofilms may be due to the complexity of such communities. Here, a comparison between different extraction methods was performed to obtain a reliable method for catalase extraction from fluvial biofilms. Homogenization followed by glass bead disruption appeared to be the best compromise for catalase extraction. This method was then applied to a field study in a metal-polluted stream (Riou Mort, France). The most polluted sites were characterized by a catalase activity 4–6 times lower than in the low-polluted site. Results of the comparison process and its application are promising for the use of catalase activity as an early warning biomarker of toxicity using biofilms in the laboratory and in the field

Dietary modulation of plasma antioxidant deficiencies: effect of mediterranean diet

Estudi elaborat a partir d’una estada al National Research Institute for Food and Nutrition, Itàlia, des de novembre del 2006 fins a febrer del 2007. La capacitat antioxidant total (TAC) en plasma pot ser un bon biomarcador del estat antioxidant dels humans. Prenent les mostres de dos projectes diferents de recerca s’ha mesurat la TAC mitjançant el FRAP (ferric reductant antioxidant potencial) i el TRAP (total radical-trapping antioxidant parameter ). D’una banda el PREDIMED, és un estudi prospectiu aleatoritzat i controlat, amb una cohort d’ individus sense patología vascular coneguda, però amb un alt risc de patir-la. En aquest es valora la utilitat d’una intervenció dietética del tipus mediterrània en la prevenció primària de la malaltia cardiovascular. L’altre és el de biodisponibilitat en humans dels metabòlits dels polifenols presents en els solubles de cacau, un estudi crònic (28 dies) on es vol mesurar la influència de la llet en l’absorció dels polifenols del cacau, en voluntaris amb elevat risc de sofrir patologia cardiovascular.

Perioperative stress in dogs underwent elective surgery: evaluation of the antioxidant activity

Projecte de recerca elaborat a partir d’una estada al Department of Biological Science a la University of Lincoln, a la Gran Bretanya, entre octubre i desembre del 2006. L'objectiu del present assaig va ser desciure les respostes antioxidants d'estrès en gossos sotmesos a cirurgia electiva, en condicions de pràctica clínica normals, durant les fases de preoperatori i postoperatori.Setze gossos van ser sotmesos a orquiectomia o ovariohisterectomia electives, utilitzant un protocol quirúrgic estàndard. Durant les fases preoperatoria i postoperatoria, cada animal va ser confinat a la Unitat de Cures Intensives, temps durant el qual es va estudiar la seva resposta antioxidant. Els valors obtinguts a diferents temps van ser comparats amb el valor basal, que s'havia obtingut del mateix animal estant aquest en el seu ambient habitual. No es van detectar variacions significants causades per l'estrès perioperatori. Els valors màxims es van observar durant la fase preoperatoria, just després que l'animal fós confinat a la Unitat de Cures Intensives, moment en el que l'estrès percebut era degut a les amenaces psicològiques de una àrea restringida i de la manipulació per persones desonegudes. L'abscència de variacions significants podrien ser degudes al sistema i el temps d'emmagatzement de les mostres. En humana s'han descrit les alteracions en l'activitat dels antioxidants sèrics després d'un mes d'emmagatzematent. Per definir l'estabilitat, després de la recollida de mostres, de l'activitat dels antioxidants en sèrum de gos és necessari realitzar més estudis.

Polymorphisms of pyrimidine pathway enzymes encoding genes and HLA-B*4001 carriage in stavudine-associated lipodystrophy in HIV-infected patients.

: To assess in a cohort of Caucasian patients exposed to stavudine (d4T) the association of polymorphisms in pyrimidine pathway enzymes and HLA-B*4001 carriage with HIV lipodystrophy syndrome (HALS). 336 patients, 187 with HALS and 149 without HALS, and 72 controls were recruited. HALS was associated with the presence of a low expression, thymidylate synthase (TS) genotype polymorphism. Methylene-tetrahydrofolate reductase (MTHFR) gene polymorphisms and HLA-B*4001 carriage were not associated with HALS or d4T-TP intracellular levels. In conclusion HALS is associated with combined low-expression TS and MTHFR associated with high activity polymorphisms but not with HLA-B*4001 carriage.

Activities of amino acid metabolizing enzymes in the stomach and small intestitine of developing rats

The activities of aspartate and alanine transaminase, serine dehydratase, arginase, glutamate dehydrogenase, adenylate deaminase and glutamine synthetase were determined in the stomach and small intestine of developing rats. Despite the common embryonic origin of the intestine and stomach, their enzymes showed quite different activity levels and patterns of development, depending on their roles. Most enzyme activities were low during late intrauterine life and after birth, attaining adult levels with the change of diet at weaning. No arginase activity was found in the stomach and no changes were detected in adenylate deaminase in the stomach or intestine throughout the period studied. Alanine transaminase, serine dehydratase and, to some extent, glutamine synthetase levels, significantly higher in late intrauterine life, decreased after birth, suggesting that the foetal stomach has a transient ability to handle amino acids.

Liquid fructose down-regulates liver insulin receptor substrate 2 and gluconeogeneic enzymes by modifying nutrient sensing factors in rats

High consumption of fructose-sweetened beverages has been linked to a high prevalence of chronic metabolic diseases. We have previously shown that a short course of fructose supplementation as a liquid solution induces glucose intolerance in female rats. In the present work, we characterized the fructose-driven changes in the liver and the molecular pathways involved. To this end, female rats were supplemented or not with liquid fructose (10%, w/v) for 7 or 14 days. Glucose and pyruvate tolerance tests were performed, and the expression of genes related to insulin signaling, gluconeogenesis and nutrient sensing pathways was evaluated. Fructose-supplemented rats showed increased plasma glucose excursions in glucose and pyruvate tolerance tests and reduced hepatic expression of several genes related to insulin signaling, including insulin receptor substrate 2 (IRS-2). However, the expression of key gluconeogenic enzymes, glucose-6-phosphatase and phosphoenolpyruvate carboxykinase, was reduced. These effects were caused by an inactivation of hepatic forkhead box O1 (FoxO1) due to an increase in its acetylation state driven by a reduced expression and activity of sirtuin 1 (SIRT1). Further contributing to FoxO1 inactivation, fructose consumption elevated liver expression of the spliced form of X-box-binding-protein-1 as a consequence of an increase in the activity of the mammalian target of rapamycin 1 and protein 38-mitogen activated protein kinase (p38-MAPK). Liquid fructose affects both insulin signaling (IRS-2 and FoxO1) and nutrient sensing pathways (p38-MAPK, mTOR and SIRT1), thus disrupting hepatic insulin signaling without increasing the expression of key gluconeogenic enzymes.

Grx5 is a mitochondrial glutaredoxin required for the activity of iron/sulfur enzymes

Yeast cells contain a family of three monothiol glutaredoxins: Grx3, 4, and 5. Absence of Grx5 leads to constitutive oxidative damage, exacerbating that caused by external oxidants. Phenotypic defects associated with the absence of Grx5 are suppressed by overexpression ofSSQ1 and ISA2, two genes involved in the synthesis and assembly of iron/sulfur clusters into proteins. Grx5 localizes at the mitochondrial matrix, like other proteins involved in the synthesis of these clusters, and the mature form lacks the first 29 amino acids of the translation product. Absence of Grx5 causes: 1) iron accumulation in the cell, which in turn could promote oxidative damage, and 2) inactivation of enzymes requiring iron/sulfur clusters for their activity. Reduction of iron levels in grx5 null mutants does not restore the activity of iron/sulfur enzymes, and cell growth defects are not suppressed in anaerobiosis or in the presence of disulfide reductants. Hence, Grx5 forms part of the mitochondrial machinery involved in the synthesis and assembly of iron/sulfur centers.

Engineered Trx2p industrial yeast strain protects glycolysis and fermentation proteins from oxidative carbonylation during biomass propagation

Background: In the yeast biomass production process, protein carbonylation has severe adverse effects since it diminishes biomass yield and profitability of industrial production plants. However, this significant detriment of yeast performance can be alleviated by increasing thioredoxins levels. Thioredoxins are important antioxidant defenses implicated in many functions in cells, and their primordial functions include scavenging of reactive oxygen species that produce dramatic and irreversible alterations such as protein carbonylation. Results: In this work we have found several proteins specifically protected by yeast Thioredoxin 2 (Trx2p). Bidimensional electrophoresis and carbonylated protein identification from TRX-deficient and TRX-overexpressing cells revealed that glycolysis and fermentation-related proteins are specific targets of Trx2p protection. Indeed, the TRX2 overexpressing strain presented increased activity of the central carbon metabolism enzymes. Interestingly, Trx2p specifically preserved alcohol dehydrogenase I (Adh1p) from carbonylation, decreased oligomer aggregates and increased its enzymatic activity. Conclusions: The identified proteins suggest that the fermentative capacity detriment observed under industrial conditions in T73 wine commercial strain results from the oxidative carbonylation of specific glycolytic and fermentation enzymes. Indeed, increased thioredoxin levels enhance the performance of key fermentation enzymes such as Adh1p, which consequently increases fermentative capacity.

Reduced antioxidant defense in early onset first-episode psychosis: a case-control study

Background:Our objective is to determine the activity of the antioxidant defense system at admission in patients with early onset first psychotic episodes compared with a control group. Methods: Total antioxidant status (TAS) and lipid peroxidation (LOOH) were determined in plasma. Enzyme activities and total glutathione levels were determined in erythrocytes in 102 children and adolescents with a first psychotic episode and 98 healthy controls. Results: A decrease in antioxidant defense was found in patients, measured as decreased TAS and glutathione levels. Lipid damage (LOOH) and glutathione peroxidase activity was higher in patients than controls. Our study shows a decrease in the antioxidant defense system in early onset first episode psychotic patients. Conclusions: Glutathione deficit seems to be implicated in psychosis, and may be an important indirect biomarker of oxidative stress in early-onset schizophrenia. Oxidative damage is present in these patients, and may contribute to its pathophysiology.

Potential of antioxidant extracts produced by aqueous processing ofrenewable resources for the formulation of cosmetics

The performance of natural extracts obtained from underutilized and residual vegetal and macroalgal biomass processed with food-grade green solvents was compared with that of commercial antioxidants. Selected extracts were obtained from two terrestrial sources: winery byproducts concentrate (WBC) and chestnut burs hydrothermally fractionated extract (CBAE), and from two underutilized seaweeds: Sargassum muticum extracts, either extracted with ethanol (SmEE) or after alginate extraction and hydrothermal fractionation (SmAE) and from Ulva lactuca processed by mild acid extraction and membrane concentration (UlAE). These extracts showed in vitro antioxidant properties comparable to commercial antioxidants and were safe for topical use based on the absence of skin-irritant effects at 0.1% on reconstructed human tissues. The stability of several cosmetic model emulsions was assessed during accelerated oxidation assays. The incorporation of natural extracts produced from renewable underutilized resources at 0.4-0.5% in an oil-in-water emulsions reduced lipid oxidation during storage.

Oxidative Stress and Antioxidant Activity in Hypothermia and Rewarming. Can RONS Modulate the Beneficial Effects of Therapeutic Hypothermia?

Hypothermia is a condition in which core temperature drops below the level necessary to maintain bodily functions. The decrease in temperature may disrupt some physiological systems of the body, including alterations in microcirculation and reduction of oxygen supply to tissues. The lack of oxygen can induce the generation of reactive oxygen and nitrogen free radicals (RONS), followed by oxidative stress, and finally, apoptosis and/or necrosis. Furthermore, since the hypothermia is inevitably followed by a rewarming process, we should also consider its effects. Despite hypothermia and rewarming inducing injury, many benefits of hypothermia have been demonstrated when used to preserve brain, cardiac, hepatic, and intestinal function against ischemic injury. This review gives an overview of the effects of hypothermia and rewarming on the oxidant/antioxidant balance and provides hypothesis for the role of reactive oxygen species in therapeutic hypothermia.