Estrogen plus progestin increase superoxide dismutase and total antioxidant capacity in postmenopausal women.

OBJECTIVE: This cross-sectional study aimed to evaluate the behavior of blood antioxidant enzymes (superoxide dismutase (SOD), catalase and glutathione peroxidase), plasma total antioxidant capacity and oxidative damage (lipid oxidation and protein carbonyl levels) and their relationship with the serum levels of steroid hormones in premenopausal and postmenopausal women without and with estrogen alone (ET) or estrogen plus progestin therapy (EPT). METHODS: Blood was collected from four groups of subjects: premenopausal women (n = 24), postmenopausal women without hormone therapy (n = 31), postmenopausal women with ET (n = 12) and postmenopausal women with EPT (n = 16). RESULTS: The activities of the different SOD isoforms (CuZnSOD and MnSOD) and the plasma total antioxidant power were significantly higher in the postmenopausal women under EPT than in the postmenopausal women without hormone replacement therapy (HRT). Only CuZnSOD activity was increased in women receiving ET compared to the postmenopausal women without HRT. However, no differences were observed in the levels of lipid or protein oxidation or in the non-enzymatic plasma antioxidants (uric acid and albumin) among the groups. The duration of HRT and serum estrogen levels were positively correlated to the blood CuZnSOD activity and to plasma total antioxidant power, whereas the serum progesterone levels were positively correlated to CuZnSOD activity and negatively correlated to protein carbonyl groups. Interestingly, the total antioxidant power of plasma was positively correlated to CuZnSOD and glutathione peroxidase activities. CONCLUSION: We conclude that EPT increases blood MnSOD and CuZnSOD activity in postmenopausal women, leading to an increased plasma total antioxidant capacity. This finding may be relevant to the prevention of oxidative stress-related disorders in postmenopausal women.

Estabilidade oxidativa e perfil de ácidos graxos do leite de vacas suplementadas com óleo de linhaça na dieta associado ou não ao selenito de sódio injetável / Oxidative stability and fatty acid profile content of milk from cows fed linseed oil diet with or without injectable sodium selenite

Avaliou-se o efeito da suplementação com óleo de linhaça na dieta, com ou sem injeção de selenito de sódio, sobre o perfil de ácidos graxos e sobre a estabilidade oxidativa do leite de vacas leiteiras. Catorze vacas foram distribuídas em três tratamentos: as do grupo 1, que receberam diariamente 400mL de óleo de linhaça (LIN); as do grupo 2, 400mL de óleo de linhaça + 0,2mg/kg de selenito de sódio IM (LINSe); e as do grupo 3 (controle), que não foram tratadas (C). O óleo foi fornecido diariamente após 15 dias da aplicação única de selenito de sódio, e o experimento teve duração de quatro semanas. Os animais suplementados com o óleo de linhaça produziram leite com altas porcentagens de ácido linoleico conjugado (CLA) e de ômega 3, contudo mais suscetível à oxidação. A aplicação injetável de selenito de sódio mostrou-se eficaz ao impedir a oxidação prematura do leite. Concluiu-se que a inclusão do óleo de linhaça na dieta de vacas leiteiras resulta em aumento do CLA, do ômega 3 e, consequentemente, da oxidação do leite, necessitando, assim do uso de substâncias antioxidantes ou promotores antioxidantes, como o selenito de sódio injetável.

The aim of the present study was to evaluate the effect of dietary linseed oil supplementation with or without injectable sodium selenite on the fatty acid profile and oxidative stability of milk from dairy cows. Fourteen cows were allocated into four treatment groups: Group 1 which received 400mL of linseed oil daily (LIN); Group 2, 400mL of linseed oil + 0,2mg/BW sodium selenite IM (LINSe); Group 3, untreated controls (C). The oil was supplied daily after 15 days of a single application of sodium selenite and during 4 weeks. Animals supplemented with linseed oil produced milk with higher levels of conjugated linoleic acid (CLA) and omega 3, but were also more susceptible to oxidation. The application of sodium selenite was effective to prevent premature oxidation of milk. We concluded that the supplementation of a cow's diet with linseed oil promoted increased CLA and omega 3 in milk, which in turn becomes more susceptible to oxidation, requiring the use of antioxidants or promoters of antioxidant activity such as injectable sodium selenite.

Non-genomic, direct modulatory effect of 17ß-estradiol, progesterone and their synthetic derivatives on the activity of human erythrocyte CuZn superoxide dismutase.

This study aimed to evaluate whether natural or synthetic steroid hormones could directly modulate the activity of the different superoxide dismutase (SOD) isoforms found in human blood fractions without changing enzyme expression. Enzyme samples of human erythrocytes, the human platelet-rich plasma fraction (PRP) or isolated CuZnSOD, which was purified from human erythrocytes were pre-incubated with natural steroids (17ß-estradiol 17-acetate and progesterone) and their synthetic derivatives (ß-estradiol 3-benzoate and medroxyprogesterone 17-acetate). Then, CuZn and MnSOD activities were measured using the xanthine/xanthine oxidase/nitroblue tetrazolium method. Hormones had no effect on MnSOD activity from the PRP, but we show for the first time that natural and synthetic steroid hormones have a direct, bell-shaped effect on the activity of CuZnSOD from both male and female human erythrocytes. Low (physiological) hormone concentrations caused a dose-dependent increase in enzyme activity, which disappeared at higher hormone concentrations. In addition, the combination of synthetic and natural estrogens and progestins had a synergistic stimulatory effect on the activity of CuZnSOD from human erythrocytes. The molecular interaction between CuZnSOD and steroid hormones was preliminarily studied. Natural hormones did not change the electrophoretic mobility of SOD under denaturing conditions, but they did increase the absorption spectra of SOD in the 230-290 nm range. These data suggest that hormone-mediated modulation of CuZnSOD is related to subtle changes in protein conformation, possibly related to Trp and Phe residues. We propose that this effect may account for the physiological regulation of enzyme activity during conditions where steroid hormones undergo alterations as the ovulatory cycle.

Lead content of dietary calcium supplements available in Brazil.

The lead and calcium content of calcium supplements available in Brazil were determined by graphite furnace and flame atomic absorption spectrometry, respectively. Samples were microwave-digested in concentrated HNO(3). Citric acid was used as a chemical modifier in the lead analysis. Supplements were classified into six categories: oyster industrialized (OI, n=4), oyster prepared in pharmacy (OP, n=3), refined industrialized (RI, n=6), refined prepared in pharmacy (RP, n=3), bone meal (B, n=3), and dolomite (D, n=4). Lead levels (microg g(-1) of measured calcium) were higher in D products (2.33), followed by OI, RP, OP, and RI products (1.46, 1.32, 1.29, 0.75), while B products had levels lower than the limit of quantification (0.02 microg g(-1) unit weight). Daily lead intake of eight supplements exceeded the limit of California, USA (1.5 microg g(-1) calcium), but none exceeded the federal limit of USA (7.5 microg g(-1) calcium) or the provisional tolerable lead intake by FAO/WHO (25 microg kg(-1) per week).