Higher GPx Research Articles

Investigation of the protective effects of different forms of selenium in freezing dog semen: Comparison of nanoparticle selenium and sodium selenite.

This study aimed to investigate the protective effects of nanoparticle selenium (SeNP) and sodium selenite (SS) on preventing oxidative stress during the freezing process of dog semen. A total of six dogs were used in the study. The ejaculate was collected from dogs three times at different times by massage method. A total of 18 ejaculates were used and each ejaculate was divided in five experimental groups. The experimental groups were designed to tris extender containing no antioxidants control, 1 μg/mL SeNP1, 2 μg/mL SeNP2, and 1 μg/mL SS1 and 2 μg/mL SS2. Extended semen were equilibrated for 1 h at 4°C, then frozen in liquid nitrogen vapour and stored in liquid nitrogen (~-196°C). After thawing, semen samples were evaluated in terms of CASA motility and kinematic parameters, spermatozoa plasma membrane integrity and viability (HE Test), spermatozoa morphology (SpermBlue) and DNA fragmentation (GoldCyto). Antioxidant enzyme activity (glutathione peroxidase; GPX, superoxide dismutase; SOD, catalase; CAT) and lipid peroxidation (malondialdehyde; MDA) were evaluated in frozen-thawed dog sperm. When the results were evaluated statistically, the progressive motility, VCL, and VAP kinematic parameters in the SeNP1 group were significantly higher than the control group after thawing (p < .05). The highest ratio of plasma membrane integrity and viable spermatozoa was observed in the SeNP1 group, but there was no statistical difference found between the groups (p > .05). Although the ratio of total morphological abnormality was observed to be lower in all groups to which different selenium forms were added, compared to the control group, no statistical difference was found. Spermatozoa tail abnormality was significantly lower in the SeNP1 group than in the control and SS2 group (p < .05). The lowest ratio of fragmented DNA was observed in the SeNP1 group, but there was no statistical difference was found between the groups (p > .05). Although there was no statistical difference between the groups in the evaluation of sperm antioxidant profile, the highest GPX, SOD and CAT values and the lowest lipid peroxidation values were obtained in the SeNP1 group. As a result, it was determined that 1 μg/mL dose of SeNP added to the tris-based extender in dog semen was beneficial on spermatological parameters, especially sperm kinematic properties and sperm morphology, and therefore nanoparticle selenium, a nanotechnology product, made a significant contribution to the freezing of dog semen.

Abstract 2550: Investigating glutathione peroxidases as potential prognostic factors in uterine corpus endometrial cancer

Abstract Introduction: Uterine corpus endometrial cancer (UCEC) is one of the deadliest women’s reproductive cancers in the United States, and mortality rates have not improved in the last 30 years due to poor prognostic methodologies. Altered expression patterns of Glutathione Peroxidases (GPX1-8) have been connected to the outcome of many cancers. Still, GPX expression patterns and their use as prognostic biomarkers in UCEC have yet to be explored. This project aimed to evaluate the potential utility of GPX1-8 as prognostic biomarkers for UCEC. Methods: To identify GPX1-8 expression alterations in UCEC tumors, the UCEC tissue samples (n=543) from the Cancer Genome Atlas Database (TCGA) dataset were analyzed using the University of Alabama at Birmingham Cancer Data Analysis portal (UALCAN) software to statistically compare mRNA levels between UCEC tumor samples and non-tumorigenic uterine tissue. To determine the impacts of GPX1-8 expression on overall survival (OS) and relapse-free survival (RFS), the UCEC TCGA dataset was analyzed using the pan-cancer RNA seq platform using Kaplan-Meier Plotter (KM plotter). The patient cohort was split into groups according to high GPX expression status and low GPX expression status using the trichotomization function in KM plotter. Hazard ratio (HR), 95% confidence interval (95% CI), and log-rank P value were calculated using the KM plotter platform. Results: GPX1, GPX2, GPX4, GPX7, and GPX8 were differentially expressed in UCEC tumor tissue compared to non-cancerous uterine tissue. However, unfavorable OS in patients associated with low GPX4 expression in UCEC tumor samples (P=0.0043, HR=0.39, 95% CI=0.2-0.76) only. Unfavorable RFS in UCEC patients only correlated with low GPX1 expression (P=0.019, HR=0.43, 95% CI=0.21-0.89) or high GPX6 expression (P=0.0032, HR=2.37, 95% CI=1.31-4.27) in UCEC tumor samples. Conclusion: Low GPX1 and GPX4 expression and high GPX6 expression may be novel unfavorable UCEC prognostic markers. Citation Format: Alexis Dukesherer, Calli A. Davison-Versagli. Investigating glutathione peroxidases as potential prognostic factors in uterine corpus endometrial cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2550.

Resveratrol relieves chronic heat stress-induced liver oxidative damage in broilers by activating the Nrf2-Keap1 signaling pathway

Heat stress (HS) affects poultry production and welfare, causing enormous damage to poultry. Resveratrol, an antioxidant and anti-inflammatory natural plant polyphenol, is widely used in agriculture for the prevention of oxidative stress-related diseases. This study aimed to explore the effects and potential mechanism of resveratrol on liver oxidative damage in heat-stressed broilers. Sixty SPF chickens were randomly divided into control, heat stress (HS) and HS+ resveratrol (resveratrol) groups. Broilers were exposed to 35 ± 2 ℃ (8 h/d) for 7 consecutive days to induce HS, and the other 16 h/d were kept at 23 ± 2 ℃, similar to the control group. Broilers received 400 mg/kg resveratrol in the basic diet 2 days before exposure to HS and for the following 7 days. The results showed that resveratrol improved growth performance by increasing the average daily gain (ADG) and reducing the feed conversion ratio (FCR), compared with the HS group. Heat stress reduced liver weight and index, increased inflammatory cell infiltration in the liver, enhanced serum AST levels, and decreased TP and ALB II levels, which resulted in liver injury in broilers, and resveratrol effectively alleviated liver injury. Moreover, supplementation with resveratrol enhanced the activities of liver antioxidant enzymes resulting in higher GPX and SOD levels than those in the heat-stressed broilers, and decreased MDA levels. Furthermore, resveratrol alleviated liver oxidative stress by activating the gene and protein levels of Nrf2 and HO-1, enhancing NQO1 and SOD1 gene levels, and decreasing protein levels of HSP70, p62, and Keap1, and thereby alleviated the liver injury of heat-stressed broilers. Compared with the HS group, Nrf2 immunofluorescence was significantly up-regulated in the livers of resveratrol group. These results suggest that resveratrol can enhance the liver antioxidant function by activating the Nrf2-Keap1 signaling pathway to promote growth performance in broilers under HS.

Glutathione Peroxide and Glutathione to Disulfide Glutathione Ratio in Presbycusis: a Case-control Study.

Background:Presbycusis is a gradual hearing loss caused by the ageing process. This is a chronic condition that affects the elderly population, and sensorineural progressive bilateral symmetry occurs with predominantly high-frequency hearing loss. The ability to discriminate speech decreases; hence, most of the affected patients have conversation problems, especially in noisy environments.This situation is a serious problem among elderly individuals. Social isolation, depression, and paranoia can be related to presbycusis.Objective:The aim of this study was to investigate GPx and the GSH:GSSG ratio as risk factors for presbycusis.Methods:A case-control study was conducted to determine the role of GPx activity with the GSH:GSSG ratio as a presbycusis risk factor in 60 subjects aged 55 to 75 years old during the period of August 2012 - April 2014. All of the subjects passed an ENT examination, pure tone audiometry, and tympanometry. The activity of GPx was measured with the Paglia and Valentine method, and the GSH:GSSG ratio was measured by the calorimetric method.Results:The activity of GPx and the GSH:GSSG ratio were significantly different between the groups (p<0.05), and the odds ratio for high GPx with a low GSH:GSSG ratio was 135 (CI 95%: 5.17–20,028.88).Conclusion:High GPx activity with a low GSH:GSSG ratio is a risk factor for presbycusis.

Maghemite nano-fertilization promotes fluoride tolerance in rice by restoring grain yield and modulating the ionome and physiome

The present manuscript elucidated the ameliorative potential of nano-maghemite (FeNPs) against the hazardous effects of fluoride toxicity in the sensitive rice cultivar, IR-64. Fluoride pollution triggered bioaccumulation in root, shoot and spikelets which inhibited reproduction, agronomic development and mineral uptake. Suppressed activity of enzymatic antioxidants and excessive cobalt translocation manifested severe ROS-induced oxidative injuries. Seedling priming with FeNPs reduced fluoride bioaccumulation and promoted efficient uptake of macroelements and micronutrients like potassium, calcium, iron, zinc, copper, nickel, manganese, selenium and vanadium and reduced the translocation of cobalt in mature seedlings during stress. This altogether triggered growth and activated the enzymes like SOD, CAT, APX and GPOX. High accumulation of non-enzymatic antioxidants like proline, anthocyanins, flavonoids, phenolics along with stimulated GSH synthesis (determined from high GR, GST and GPX activity) and glyoxalase activity enabled FeNP-pulsed plants to efficiently scavenge ROS, O2-, H2O2 and methylglyoxal, and mitigate oxidative injuries. The ROS production was also lowered due to suppressed NADPH oxidase activity. This ensured subsequent revitalization of Hill activity and the level of photosynthetic pigments. Due to reduced fluoride partitioning and improved nutritional sink, the grain and panicle development in FeNP-primed, stressed seedlings were more stimulated than even control sets. Overall, our findings supported by statistical modelling established the potential of iron-nanotechnology in promoting safe rice cultivation even in fluoride-polluted environments.

Glutathione Peroxidase Activity Is Altered in Vascular Cognitive Impairment-No Dementia and Is a Potential Marker for Verbal Memory Performance

Background:Coronary artery disease (CAD) increases risk for vascular cognitive impairment-no dementia (VCIND), a precursor to dementia, potentially through persistent oxidative stress.Objective:This study assessed peripheral glutathione peroxidase activity (GPX), which is protective against oxidative stress, in VCIND versus cognitively normal CAD controls (CN). GPX activity was also evaluated as a biomarker of cognition, particularly verbal memory.Methods:120 CAD patients with VCIND (1SD below norms on executive function or verbal memory (VM)) or without (CN) participated in exercise rehabilitation for 24 weeks. Neurocognitive and cardiopulmonary fitness (VO2 peak) assessments and plasma were collected at baseline and 24-weeks.Results:GPX was higher in VCIND compared to CN (F1,119 = 3.996, p = 0.048). Higher GPX was associated with poorer baseline VM (β= –0.182, p = 0.048), and longitudinally with VM decline controlling for sex, body mass index, VO2 peak, and education (b[SE] = –0.02[0.01], p = 0.004). Only CN participants showed improved VM performance with increased fitness (b[SE] = 1.30[0.15], p < 0.005).Conclusion:GPX was elevated in VCIND consistent with a compensatory response to persistent oxidative stress. Increased GPX predicted poorer cognitive outcomes (verbal memory) in VCIND patients despite improved fitness.

Exposure to aluminum, aluminum + manganese and acid pH triggers different antioxidant responses in gills and liver of Astyanax altiparanae (Teleostei: Characiformes: Characidae) males

Exposure to aluminum (Al) and aluminum + manganese (Mn) can trigger an increase in reactive oxygen species (ROS) and modify the activity of oxidative defense enzymes. This study investigated whether exposure to Al and Al + Mn at acid pH for 24 and 96 h causes oxidative stress evidenced by antioxidants and oxidative damage in the gills and liver of sexually mature Astyanax altiparanae males. The fish were subsequently immersed in metal-free water for 24 and 96 h to see whether they recovered from the effects of these metals. Exposure to an acid pH boosted the activity of gill superoxide dismutase (SOD) at 96 h and the fish did not recover when immersed for the same period in water at neutral pH. Exposure to Al increased glutathione (GSH) levels (24 h) in the gills, returning to control levels during the recovery period, showing the efficiency of the antioxidant system in preventing lipid peroxidation of the gills and liver. Mn did not modify the activity of the enzymes studied, but did trigger late hepatic lipid peroxidation during the recovery period. The group exposed to Al + Mn exhibited several alterations, including increased concentration of GSH, as well as higher GPx and GR activity in the gills. Despite the defensive responses triggered by acute exposure, during the recovery period there were alterations in catalase (96 h) and an increase in hepatic metallothionein (24 h), but this did not prevent hepatic lipid peroxidation. Al and Al + Mn produced different effects, and the timing of enzymatic and non-enzymatic antioxidant defenses also differed.

Use of Selenium-enriched olive leaves in the feed of growing rabbits: Effect on oxidative status, mineral profile and Selenium speciation of Longissimus dorsi meat

In the present study the use of Selenium-fortified olive leaves as potential dietary source of Se in rabbit nutrition was evaluated. Sixty New Zealand White rabbits (35 days of age) were randomly assigned to the following dietary treatments: standard diet (C), and C supplemented with either 10% olive leaves (OL) or 10% Selenium-fortified olive leaves (SeOL; 100 mg/L of foliar spray sodium selenate solution). At 70 days of age, 10 rabbits per group were slaughtered and the oxidative status, mineral profile and Selenium speciation of Longissimus dorsi meat was analyzed. Meat of the SeOL group exhibited better oxidative status (lower TBARS, higher GPx and α-tocopherol values) and a 5-fold higher Se content compared to that of the other treatments. The main Se form was SeMet (7-fold higher in the SeOL group), followed by SeCys2. The present trial demonstrates the possibility of using agro-industrial by-products as ingredients in rabbit feeds, thereby enriching meat bioactive compound content.

Inflammatory and oxidative stress phenotypes in transgenic sickle cell mice

The Townes mouse model of homozygous sickle cell disease (SS) has emerged as the major experimental model for studying pathophysiological mechanisms of human sickle cell disease (SCD). We therefore investigated hematological and hemorheological parameters as well as organ-specific inflammatory and oxidative stress molecular profiles in these animals in steady state conditions. Evidences of SCD-related intravascular hemolysis, impaired red blood cell (RBC) deformability, leukocytosis and altered plasma nitric oxide byproducts (NOx) level were found in the SS mice. The SS mice have damaged, enlarged and dysfunctional spleen as attested by high AOPP levels, low SOD and GPx activities and low pro-inflammatory cytokines mRNA expression. SS mice exhibited cardiomegaly, high cardiac mRNA levels of proinflammatory markers and low cardiac GPx activity. While lungs did not display any noticeable defects, liver and kidney were particularly sensitive to oxidative stress and inflammation as suggested by high AOPP levels in both organs, elevated renal NF-κB and TNF-α, and increased hepatic VCAM-1 and IL-1β. Our data indicate a tissue-specific phenotype regarding oxidative stress and inflammation in SS mice that may help to optimize the development of novel potential drug treatments.

Determining Gene Expression Profile of GPX 1 in the Liver of Diabetic Rats Treated with Capsaicin by Real-Time PCR

The purpose of the present study was to determine the Glutathione Peroxidase 1 (GPX 1) gene expression by Real Time PCR in the liver of healthy and diabetic rats treated with capsaicin. Twenty Sprague-Dawley rats were used in our study. Rats were divided into four groups: Group I: diabetic rats (n=5), Group II: capsaicin injected rats (n=5), Group III: Capsaicin injected diabetic rats (n=5), and Group IV: control rats (n=5). Capsaicin injection began 72 h after streptozotocin (STZ) injection. Capsaicin (1 mg/kg) was prepared in 10% ethanol, 1% Tween 20, and 80% sterile water and subcutaneously injected daily in both Groups II and III for two weeks. The results of RT-PCR conducted to determine GPX 1 gene expression indicated that capsaicin treated diabetic rats had higher GPX 1 expression compared to all groups including control (P<0.05). As a result, capsaicin causes an increase in GPX 1 gene expression at transcription level in the diabetic rat liver. Further investigation is needed to determine if such an increase occurs at protein level using various methods such as western-blot analysis.

Antioxidant Defense in Overt and Subclinical Hypothyroidism

Oxidative stress as a result of disequilibrium between free radical generation and antioxidant status has been implicated in several pathologies including thyroid diseases. Studies on antioxidant status in overt (OHT) and subclinical hypothyroidism (SHT) are controversial and limited. The aim of this study was to determine the effect of OHT and SHT on antioxidant status. Thirty-six patients with OHT, 36 patients with SHT, and 39 healthy euthyroid subjects as the control group were included in the study. Plasma levels of malondialdehyde (MDA), reduced glutathione (GSH) and total antioxidant capacity (TAC) as ferric reducing ability of plasma (FRAP), and erythrocyte antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GPx), SOD/GPx ratios, catalase (CAT), and glutathione reductase (GR) were analyzed in all groups. MDA and GPx values were elevated, while GSH, FRAP, SOD, and SOD/GPx ratio were decreased in both patient groups compared with controls. No change in activities of CAT and GR were observed in both the patient groups. Significant differences were observed between OHT and SHT groups with high MDA, GPX and low GSH, FRAP, SOD, and SOD/GPx ratio in OHT group. Thus, hypothyroid patients have a deficient antioxidant defense in the form of decreased activity of SOD, decreased levels of FRAP and GSH along with an increase in GPx activity. The severity of the disease appears to decide the degree of deficiency and our findings also point to this, in the form of decrease in SOD, FRAP, and GSH observed being more in OHT than in SHT patients. Hormonal changes and increased lipid peroxidation, which also vary with severity of disease, appear to contribute to the antioxidant deficiency.

Comparing functional metabolic effects of marginal and sufficient selenium supply in sheep

This study was performed to characterise key data of long-term ovine Se metabolism and to work out the best biomarker of Se status. An upgrade from marginal (<0.05mg Se/kg diet, ‘Se−’) to sufficient (0.2mg Se/kg diet, ‘Se+’) nutritional Se supply using sodium selenite was monitered biweekly by analysing Se concentration, glutathione peroxidase (Gpx) activity and routine biochemistry in blood/serum over 2 years. Se, Cu, Zn, cytosolic Gpx and thioredoxin reductase (TrxR) activity were measured in the liver (biopsies/post-mortem). Se, Gpx, TrxR, glutathione-S-transferase-alpha (aGST) and iodothyronine deiodinase (Dio1) were analysed in the kidney, heart muscle and thyroid. Relative mRNA expression of hepatic aGST1 and Gpx1 was determined.Improvement of Se supply strongly increased serum and liver Se concentration within 10 and 20 days, respectively followed by a plateau. Whereas the achievement of a maximum whole blood Gpx activity was reached after 3 months, serum Gpx3 activity increased with high variations. Hepatic Gpx activity reached a maximum during days 100–200, decreasing thereafter. Distinct group differences in Se and cytosolic Gpx activity were evident in all organs (except Se in kidney). TrxR and Dio1 activity was affected only in the liver. The Se− sheep showed an ongoing decrease in serum Se concentration within 2 years, whereas liver Se remained almost unaffected. High relative Gpx1 mRNA expression in the Se+ group was consensual to high hepatic Gpx activity. Relative mRNA expression of hepatic aGST1 was higher in the Se− sheep. Clinical signs and abnormalities in routine biochemistry were absent.In summary, the best biomarker of Se deprivation and nutritional Se upgrade, respectively was Se in serum. Moreover, hepatic Se concentrations reliably reflected the upgrade of Se supply within days. Whole blood Gpx reacts slowly depending on newly formed erythrocytes restricting its diagnostic use. Vital organs are affected by Se deficiency due to a decrease of cytosolic Gpx activity attenuating the antioxidative system. Cellular up-regulation of aGST1 mRNA expression in the Se− group is assumed to partially compensate for the decreased antioxidant defence due to a loss in Gpx activity. This sheep model appears advantageous for long-term studies on sub-clinical metabolic effects in experimental modifiable nutritional Se supply.

Characterization of selenium‐containing glutathione transferase zeta1–1 with high GPX activity prepared in eukaryotic cells

Accumulating evidence shows that glutathione peroxidase (GPX, EC.1.11.1.9), one of the most important antioxidant selenoenzymes, plays an essential role in protecting cells and tissues against oxidative damage by catalyzing the reduction of hydrogen peroxide by glutathione. Unfortunately, because of the limited availability and poor stability of GPX, it has not been used clinically to protect against oxidative stress. To overcome these problems, it is necessary to generate mimics of GPX. In this study, we have used directed mutagenesis and the inclusion of a selenocysteine (Sec) insertion sequence to engineer the expression in eukaryotic cells of human glutathione transferase zeta1-1 (hGSTZ1-1) with Sec in the active site (seleno-hGSTZ1-1). This modification converted hGSTZ1-1 into an active GPX and is the first time this has been achieved in eukaryotic cells. The GPX activity of seleno-hGSTZ1-1 is higher than that of GPX from bovine liver, indicating Sec at the active site plays an important role in the determination of catalytic specificity and performance. Kinetic studies revealed that the ping-pong catalytic mechanism of Se-hGSTZ1-1 is similar to that of the natural GPX.

Effects of water stress and inoculation with plant growth promoting rhizobacteria (PGPR) on antioxidant status and photosynthetic pigments in basil ( Ocimum basilicum L.)

Effects of water stress and inoculation with plant growth promoting rhizobacteria (PGPR) on antioxidant activity and photosynthetic pigments were studied in basil plants. A field experiment was conducted at the University of Zabol in Iran during 2010 growing season. The experiment laid out as split plot based on randomized complete block design with three replications. Three levels of water stress W 1 = 80 (control), W 2 = 60 and W 3 = 40% of the field capacity (FC) as main plots and four levels of bacterial species consisting of S 1 = Pseudomonades sp., S 2 = Bacillus lentus, S 3 = Azospirillum brasilens, S 4 = combination of three bacterial species and S 5 = control (without use of bacterial) as sub plots. The results revealed that water stress caused a significant change in the antioxidant activity. The highest concentration CAT and GPX activity were in W 3 treatments. By increasing water stress from control to W 3, chlorophyll content in leaves was increased but Fv/Fm and APX activity decreased. Application of rhizobacteria under water stress improved the antioxidant and photosynthetic pigments in basil plants. S 1 = Pseudomonades sp. under water stress, significantly increased the CAT enzyme activity, but the highest GPX and APX activity and chlorophyll content in leaves under water stress were in S 4 = combination of three bacterial species.

Voluntary exercise training in mice increases the expression of antioxidant enzymes and decreases the expression of TNF-α in intestinal lymphocytes

Acute exercise in mice induces intestinal lymphocyte (IL) apoptosis. Freewheel running reduces apoptosis and forced exercise training increases splenocyte antioxidant levels. The purpose of this study was to examine the effect of freewheel running and acute exercise on mouse IL numbers and concentrations of apoptosis and antioxidant proteins and pro-inflammatory cytokines in IL. Female C57BL/6 mice had access to in-cage running wheels (RW) or cages without wheels (NRW) for 16 weeks and were randomized at the end of training to no exercise control (TC) or to treadmill exercise with sacrifice after 90 min of running (TREAD; 30 min, 22 m min −1; 30 min, 25 m min −1; 30 min, 28 m min −1; 2° slope). IL were analyzed for pro-(caspase 3 and 7) and anti-(Bcl-2) apoptotic proteins, endogenous antioxidants (glutathione peroxidase: GPx; catalase: CAT) and the pro-inflammatory cytokine, TNF-α. RW mice had higher cytochrome oxidase ( p < 0.001) and citrate synthase ( p < 0.01) activities in plantaris and soleus muscles and higher GPx and CAT expression in IL ( p < 0.05) (indicative of training) compared with NRW mice. TNF-α expression was lower ( p < 0.05) and IL numbers higher ( p < 0.05) in RW vs. NRW mice. No training effect was observed for apoptotic protein expression, although TREAD resulted in higher caspase and lower Bcl-2. These results suggest that freewheel running in mice for 16 weeks enhances antioxidant and reduces TNF-α expression in IL but does not reduce pro-apoptotic protein expression after acute exercise. Results are discussed in terms of implications for inflammatory bowel diseases where apoptotic proteins and TNF-α levels are elevated.

Physiological responses of Matricaria chamomilla to cadmium and copper excess

Physiological responses of Matricaria chamomilla plants exposed to cadmium (Cd) and copper (Cu) excess (3, 60, and 120 microM for 7 days) with special emphasis on phenolic metabolism were studied. Cu at 120 microM reduced chamomile growth, especially in the roots where it was more abundant than Cd. Notwithstanding the low leaf Cu amount (37.5 microg g(-1) DW) in comparison with Cd (237.8 microg g(-1) DW) at 120 microM, it caused reduction of biomass accumulation, F(v)/F(m) ratio and soluble proteins. In combination with high accumulation of phenolics, strong reduction of proteins and high GPX activity in the roots, this supports severe redox Cu properties. In terms of leaf phenylalanine ammonia-lyase (PAL) activity, it seems that Cd had a stimulatory effect during the course of the experiment, whereas Cu was found to stimulate it after 7-day exposure. The opposite trend was visible in the roots, where Cd had a stimulatory effect at high doses but Cu mainly at the highest dose. This supports the assumption of different PAL time dynamics under Cd and Cu excess. A dose of 60 and 120 microM Cu led to 2- and 3-times higher root lignin accumulation while the same Cd doses increased it by 33 and 68%, respectively. A Cu dose of 120 microM can be considered as limiting for chamomile growth under conditions of present research, while resistance to high Cd doses was confirmed. However, PAL and phenolics seemed to play an important role in detoxification of Cd- and Cu-induced oxidative stress.

Fluidity and oxidative stress in erythrocytes from very low birth weight infants during their first 7 days of life

Objective: To study the evolution of lipid peroxidation, enzymatic antioxidants response, lipid profile and membrane fluidity in erythrocytes from very low birth weight (VLBW) infants during their first 7 days of extra-uterine life.Study design: One hundred and twenty infants were selected and divided in two groups according to their weight and gestational age. Hydroperoxides, fatty-acid profile, fluidity (DPH and TMA-DPH) and catalase, SOD and GPx activities were measured in erythrocytes.Results: VLBW group showed higher concentration of hydroperoxides and lower membrane fluidity during the first 72 h, lower SOD activity during the first 3 h and higher GPx activity during the first 7 days of life. Also, this group showed lower n-3 polyunsaturated fatty-acids percentage with respect to the term group.Conclusion: Erythrocytes from VLBW infants showed higher oxidative damage and lower fluidity in their membranes, at least during the first 3 days of extra-uterine life, which may cause alterations in their functions and flexibility.

Plasma glutathione peroxidase by ELISA and relationship to selenium level

Background Many assays have investigated GPx activity but there are few reports of immunoreactive methods of GPx plasma determinations and their relationship with plasma selenium. Methods A cross-sectional analysis of selenium and GPx was carried out on 170 adults randomly selected from the electoral role. Blood samples were collected and analysed for plasma GPx using a commercial enzyme-linked immunosorbent assay (ELISA) kit and plasma selenium using magnetic sector ICP–MS. Further investigations of GPx level were carried out using one-dimensional (1D) and two-dimensional (2D) polyacrylamide gel electrophoresis (PAGE). Results Plasma GPx was associated with plasma Se level ( r 2 = 0.24, P < 0.0001). Mean (range) Se was 108.9 (67.4–268.0) μg/l. Mean (range) plasma GPx was 18.5 (3.8–43.8) μg/ml, significantly higher than the theoretical mean GPx of around 6.5–6.9 μg/ml based on ICP–MS results and the proportion of Se in intact GPx. GPx was higher in males than females and lower in current than non-smokers and ex-smokers. PAGE analysis of glycine dissociated ELISA wells revealed GPx as well as a number of unknown proteins with significant variability between high and low GPx samples. Conclusions Plasma GPx is correlated with Se status, however, there is considerable GPx variability between patients and ELISA methods appear to significantly overestimate true plasma GPx.

Arsenate Causes Differential Acute Toxicity to Two P-deprived Genotypes of Rice Seedlings (Oryza sativa L.)

Significant genotypic difference in response to arsenate toxicity in rice (Oryza sativa) was investigated in root elongation, arsenate uptake kinetics, physiological and biochemical response and arsenic (As) speciation. Uptake kinetics data showed that P-deprived genotype 94D-54 had a little higher As uptake than P-deprived 94D-64, but the difference was not large enough to cause acute toxicity in P-deprived 94D-54. There was no difference in tissue P concentrations between the two genotypes under P deficient conditions. In addition, arsenic speciation in plant tissues (using high performance liquid chromatography-inductively coupled plasma mass spectrometry) was not different between P pretreatments and between genotypes. P-deprived genotype 94D-54 suffered much higher stress induced by arsenate toxicity than P-deprived genotype 94D-64, in terms of lipid peroxidation, tissue H2O2 concentrations and exosmosis of K, P and As. However, P-deprived 94D-54 also had higher overproduction of enzymatic antioxidants (with higher GPX, SOD, CAT) and NPT (non-protein thiols) than P-deprived 94D-64. It appeared that, the higher sensitivity of P-deprived 94D-54 to arsenate toxicity might cause the overproduction of NPT, thus leading to the depletion of GSH and to the accumulation of H2O2. The differential sensitivity of the two genotypes has major implications for breeding rice for As affected paddy soil.

Biomimetic studies on anti-thyroid drugs and thyroid hormone synthesis.

The selenium analogues of anti-thyroid drugs exhibit their anti-thyroid action by a mechanism different from that of MMI. The selenium analogue of MMI and related selenium compounds exhibit high GPx activity, providing a novel method for the reversible inhibition of thyroid hormone biosynthesis.