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Salt damage to plants has been attributed to a combination of several factors including mainly osmotic stress and the accumulation of toxic ions. Recent findings in our laboratory showed that phospholipid hydroperoxide glutathione peroxidase (PHGPX), an enzyme active in the cellular antioxidant system, was induced by salt in citrus cells and mainly in roots of plants. Following this observation we studied the two most important enzymes active in elimination of reactive oxygen species, namely, superoxide dismutase (SOD) and ascorbate peroxidase (APX), to determine whether a general oxidative stress is induced by salt. While Cu/Zn-SOD activity and cytosolic APX protein level were similarly induced by salt and methyl viologen, the response of PHGPX and other APX isozymes was either specific to salt or methyl viologen, respectively. Unlike PHGPX, cytosolic APX and Cu/Zn-SOD were not induced by exogenously added abscisic acid. Salt induced a significant increase in SOD activity which was not matched by the subsequent enzyme APX. We suggest that the excess of H2O2 interacts with lipids to form hydroperoxides which in turn induce and are removed by PHGPX. Ascorbate peroxidase seems to be a key enzyme in determining salt tolerance in citrus as its constitutive activity in salt-sensitive callus is far below the activity observed in salt-tolerant callus, while the activities of other enzymes involved in the defence against oxidative stress, namely SOD, glutathione reductase and PHGPX, are essentially similar.

This paper evaluates the impact of long-term supplementation of different forms of zinc and selenium on the content of these substances in the blood and hair of goats. Two analogous supplementation experiments were performed, 37 goats divided into four groups were used in the first trial with the Zn supplementation. Group A (n = 10) was the control group, goats in the group B (n = 9) were supplemented with zinc oxide, Group C (n = 9) with zinc lactate and Group D (n = 9) with zinc chelate. The second trial with Se supplementation was carried out on 20 goats divided into four groups. Group E (n = 5) was the control group, Group F (n = 5) was supplied with a selenium lactate-protein complex, Group G (n = 5) with sodium selenite and Group H (n = 5) with selenium yeast. Three months later Zn and Se concentrations were determined in whole blood, plasma, and hair. Glutathione peroxidase (GSH-Px) activity was determined in the Se supplementation trial group. At the end of the trial the Zn concentrations in plasma and whole blood were without major differences between the groups. The plasma concentration of Zn did not increase from the initial value at the start of the trial. In hair the average concentration of Zn was 95.2-100.0 mg/kg in all groups. No conclusive relation was confirmed between the values of Zn in hair and its concentration in blood. The Se concentration in whole blood (microg/L) at the end of trial in supplemented groups (F - 188.8+/-24.6; G - 197.2+/-10.9; H - 190.1+/-26.3) was significantly higher than in the control group (103.1+/-23.5). Similarly, the activity of GSH-Px (microkat/L) was significantly higher in all supplemented groups (F - 872.3+/-94.8; G - 659.5+/-176.4; H - 839.8+/-150.8) than in the control group (379.1+/-63.5). Se content in hair (microg/kg) was higher also in all trial groups (F - 242.3+/-41.5; G - 200.5+/-46.9; H - 270.0+/-106.8) than in the control group (174.7+/-38.0). However, it was significantly higher only in Group F. A conclusive correlation was identified between the Se concentration in whole blood and its content in hair (r = 0.54; P less than 0.05; n = 20). None of the supplemented forms of Zn increased its concentration in blood, plasma and hair. On the other hand, the administration of Se led to an increase in the Se concentration in blood, increased the activity of GSH-Px in whole blood and the Se content in hair. Hair can be considered as a suitable material for the diagnosis of long-term Se status in goats. Goats with sufficient Se status are those that have more than 160 microg/kg of Se in hair dry weight.

The present study examined the effects of derivatives of galactosides and glucosides in a polysaccharide extract from Euphorbia kansui (Euphorbiaceae) on exercise-induced oxidative stress in mice. Exhaustive swimming exercise significantly increases the degree of lipid peroxidation in terms of malondialdehyde content and reduces the antioxidant activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx). Our findings revealed that chronic oral treatment with the extract elevates enzymatic activities of SOD and GPx accompanied by a corresponding decrease in malondialdehyde. The antioxidative activities of these compounds against exercise-induced oxidative stress are correlated with various activities such as reducing the production of superoxide and hydroxyl radicals, inhibiting lipid peroxidation, enhancing antioxidative defenses, and increasing the production of SOD and GPx activity and expression in different tissues. These compounds may be involved in glycogen metabolism to meet the requirement of working skeletal muscles and act as antioxidants by terminating the chain reaction of lipid peroxidation to maintain the morphological stability of mitochondria in spinal motor neurons. These observations suggest that E. kansui has antioxidative and antifatigue properties and can be given as prophylactic and (or) therapeutic supplements for increasing antioxidant enzyme activities and preventing lipid peroxidation during strenuous exercise.

The goal of the experiment was to compare the effect of supplementation of inorganic and the new organically bound form of selenium (lactate-protein selenium complex) in feed for goats. Thirty-one goats were split into three groups as follows: control (C) without Se supplementation, AN group administered sodium selenite, ORG group administered lactate-protein Se complex. The total Se intake was 0.15 mg (group C) and 0.43 mg (groups AN and ORG). Se concentration and the activity of glutathione peroxidase (GSH-Px) in whole blood were evaluated. Samples were taken before the beginning of Se supplementation, 14 days, 30 days, 2 months, and 3 months after the beginning of supplementation. Average Se concentrations in the blood of C, AN and ORG goats before the supplementation were 109.6+/-34.3, 117.5+/-34.7, and 105.4+/-43.6 microg/L, respectively, GSH-Px activity was 745.3+/-289.2, 810.7+/-280.4, and 791.0+/-398.1 microkat/L, respectively. There was a significant increase in both Se concentrations and GSH-Px activities in both experimental groups after Se supplementation. At the end of the experiment Se concentrations in the blood of AN and ORG groups amounted to 168.5+/-12.2 and 168.8+/-26.8 microg/L, resp., and GSH-Px activity was 1,178.0+/-127.3 and 1,030.1+/-152.3 microkat/L, resp. A markedly quicker increase in GSH-Px activity was recorded in the AN group - one month after the beginning of Se supplementation in comparison with three months in the ORG group. The results thus show that the effects of selenite and the lactate-protein Se complex are similar with regard to Se status, but the increase in GSH-Px activity occurred much faster with selenite, which therefore appears to be a more biologically available form of Se.

The present study examines whether a subchronic probucol treatment of rats offers protection against ischemia-reperfusion (IR) injury in isolated perfused hearts. Sprague-Dawley rats were treated every second day per week with probucol (cumulative dose 120 mg/kg body mass, i.p.) for 4 weeks. In the probucol group, baseline myocardial antioxidant enzyme, glutathione peroxidase (GSHPx), activity was increased (p < 0.05), whereas superoxide dismutase (SOD) and catalase (CAT) activities were not changed. Baseline oxidative stress, as indicated by the myocardial lipid peroxidation, was less (p < 0.05) in the probucol group. Isolated hearts were subjected to 60 min global I and 20 min R. Recovery of the contractile function in globally ischemic hearts upon reperfusion was 36% in untreated group and 74% in the probucol group. After IR, GSHPx and CAT activities were significantly (p < 0.05) higher in the probucol group compared with the control group, whereas SOD did not change. Lipid peroxidation owing to IR was significantly less in the probocol group. These data suggest that probucol treatment improves endogenous antioxidant reserve and protects against increased oxidative stress following IR injury.

The aim of this study was to evaluate the effect of aerobic training (16 weeks - T1 and 24 weeks - T2) on oxidative stress biomarkers. To this end, GSH, GSH-peroxidase (GSH-Px) and catalase (CAT) activity were analysed in plasma. Nine bulls (3-4 years) were included in this work. The exercise training protocol was performed in a track three days per week for 24 weeks and consisted of 400 m warming up, 1,200 m to 4-5 m/s, two minutes' resting, 1,200 m to 4-5 m/s and, finally, 400 m walking. The results reflected that GSH-Px activity was higher at T1 (6.18+/-0.45) than at baseline (T0; 2.31+/-0.08) while the GSH level (2.98+/-0.37) was lower vs. T0 (14.59+/-3.40). Moreover, there were significant increases in GSH-Px (18.23+/-1.36) and CAT (2.52+/-0.04) activities and the recovery of basal values in GSH (11.75+/-2.84) in T2. In conclusion, the type of training carried out in this study involved two well-defined stages: (i) a period of perturbation, followed by (ii) adaptation. The former stage was characterised by the induction of oxidative stress manifested as a decrease in the GSH, and the latter (T2) by the recovery of this non-enzymatic antioxidant.

Cold acclimation of Scots pine did not affect the susceptibility of photosynthesis to photoinhibition. Cold acclimation did however cause a suppression of the rate of CO2 uptake, and at given light and temperature conditions a larger fraction of the photosystem II reaction centres were closed in cold-acclimated than in nonacclimated pine. Therefore, when assayed at the level of photosystem II reaction centres, i.e. in relation to the degree of photosystem closure, cold acclimation caused a significant increase in resistance to photoinhibition; at given levels of photosystem II closure the resistance to photoinhibition was higher after cold acclimation. This was particularly evident in measurements at 20° C. The amounts and activities of the majority of analyzed active oxygen scavengers were higher after cold acclimation. We suggest that this increase in protective enzymes and compounds, particularly superoxide dismutase, ascorbate peroxidase, glutathione reductase and ascorbate of the chloroplasts, enables Scots pine to avoid excessive photoinhibition of photosynthesis despite partial suppression of photosynthesis upon cold acclimation. An increased capacity for light-induced de-epoxidation of violaxanthin to zeaxanthin upon cold acclimation may also be of significance.

Three experiments involving 192 crossbred boars evaluated the effects of dietary Se (0 or .5 ppm) and vitamin E (0 or 220 IU/kg) on growth, tissue Se, and alpha-tocopherol concentrations, and on semen quality and its subsequent effect on fertilization rate in mature gilts. Diets formulated used torula yeast and dextrose or cornstarch as the basal feedstuffs and were provided from weaning through sexual maturity. The basal diets averaged .063 ppm Se and 3.46 mg alpha-tocopherol/kg diet. Experiment 1 was a 2 X 2 factorial and conducted as a randomized complete block design in six replicates. Boars were allotted at weaning (initial BW 7.7 kg) with growth and feed performance determined to 145 kg BW. Five boars were killed at weaning and three from each treatment group at periodic intervals to 145 kg BW. Serum and tissue Se and alpha-tocopherol concentration and glutathione peroxidase (GSH-Px) activity were subsequently determined. No performance benefit from either nutrient was demonstrated. Tissue (serum, liver, and testis) GSH-Px activity and Se and alpha-tocopherol concentrations were higher (P .01) at each period when that respective nutrient fortified the diet. Testis GSH-Px activity increased from weaning to 145 kg BW even when Se was not added to the diet. Experiment 2 was conducted after training three boars from each treatment group of Exp. 1 for semen collection. From 9 mo of age and for a 16-wk period, semen was collected three times weekly and the volume, sperm concentration, motility, and percentage of normal and abnormal sperm were determined. Boars fed either the nonfortifed Se or vitamin E diets had sperm with lower motilities (P .01) and a higher percentage of sperm cells with bent and shoehook tails (P .01). Diets low in added Se seemed to have a greater detrimental effect on the percentage of motile and abnormal sperm than diets inadequate in vitamin E. Sperm cells had a high concentration of Se and alpha-tocopherol, and a high GSH-Px activity.

The aim of our study was to compare the concentration of selenium and the activity of glutathione peroxidase (GSH-Px) in the whole blood of goats and their kids. The experiment involved 25 gravid, clinically healthy goats of the white shorthaired breed. On the day of delivery, we took whole blood from the mother and her newborn kid before the kid drank the first colostrum. In mothers, the measured average concentration of Se in whole blood was 149.60+/-45.01 microg/L, the average concentration of Se in kids was 87.91+/-29.66 microg/L. The average activity of GSH-Px was 938.46+/-341.09 microkat/L in the blood of mothers and 658.20+/-339.13 microkat/L in the blood of kids. Regression and correlation analyses revealed a significant relation between the concentration of Se in the blood of mothers and their kids and the activity of GSH-Px in mothers and their kids. Se conc. and GSH-Px activity were lower in newborn kids than in their mothers, reaching approximately 60-70% of the mother's levels. There were also sifnificant relations between Se conc. and GSH-Px activity in the blood of goats and kids. Se conc. of 100 microg/L corresponds to the GSH-Px activity of 699.51 microkat/L in the blood of mothers and 720.34 microkat/L in the blood of kids. AS shown by our results, Se concentration in the blood of newborn kids is about 40% lower than that of their mothers.