Evaluation of redox profiles in exogenous subclinical hyperthyroidism at two different levels of TSH suppression.

OBJECTIVE: Evaluate the relationship between exogenous subclinical hyperthyroidism and oxidative stress through the analysis of the redox profile of patients with subclinical hyperthyroidism exogenous (SCH) grade I (TSH = 0.1 to 0.4 IU/mL) and grade II (TSH < 0.1 IU/mL). SUBJECTS AND METHODS: We analyzed 46 patients with SCH due to the use of TSH suppressive therapy with LT4 after total thyroidectomy along with 6 control euthyroid individuals (3M and 3W). Patients were divided into two groups, G1 with TSH ≥ 0.1-0.4 IU/mL (n = 25; and 7M 14W) and G2 with TSH < 0.1 IU/mL (n = 25; and 4M 21W). Venous blood samples were collected to measure the levels of markers for oxidative damage (TBARS, FOX and protein carbonylation), muscle and liver damage (CK, AST, ALT, GGT) and antioxidants (GSH, GSSG and catalase). RESULTS: Individuals in G2 showed a GSH/GSSG ratio ~ 30% greater than those in G1 (p = 0.004) and a catalase activity that was 4 times higher (p = 0.005). For lipid peroxidation, the levels measured in G2 were higher than both control and G1 (p = 0.05). No differences were observed for both protein carbonyl markers. G1 and G2 presented with greater indications of cell injury markers than the control group. CONCLUSION: TSH suppression therapy with LT4 that results in subclinical hyperthyroidism can cause a redox imbalance. The greater antioxidant capacity observed in the more suppressed group was not sufficient to avoid lipid peroxidation and cellular damage.

Evaluation of redox profiles in exogenous subclinical hyperthyroidism at two different levels of TSH suppression

ABSTRACT Objective: Evaluate the relationship between exogenous subclinical hyperthyroidism and oxidative stress through the analysis of the redox profile of patients with subclinical hyperthyroidism exogenous (SCH) grade I (TSH = 0.1 to 0.4 IU/mL) and grade II (TSH < 0.1 IU/mL). Subjects and methods: We analyzed 46 patients with SCH due to the use of TSH suppressive therapy with LT4 after total thyroidectomy along with 6 control euthyroid individuals (3M and 3W). Patients were divided into two groups, G1 with TSH ≥ 0.1-0.4 IU/mL (n = 25; and 7M 14W) and G2 with TSH < 0.1 IU/mL (n = 25; and 4M 21W). Venous blood samples were collected to measure the levels of markers for oxidative damage (TBARS, FOX and protein carbonylation), muscle and liver damage (CK, AST, ALT, GGT) and antioxidants (GSH, GSSG and catalase). Results: Individuals in G2 showed a GSH/GSSG ratio ~ 30% greater than those in G1 (p = 0.004) and a catalase activity that was 4 times higher (p = 0.005). For lipid peroxidation, the levels measured in G2 were higher than both control and G1 (p = 0.05). No differences were observed for both protein carbonyl markers. G1 and G2 presented with greater indications of cell injury markers than the control group. Conclusion: TSH suppression therapy with LT4 that results in subclinical hyperthyroidism can cause a redox imbalance. The greater antioxidant capacity observed in the more suppressed group was not sufficient to avoid lipid peroxidation and cellular damage.

Human papillomavirus infection and cervical cancer precursor lesions in women living by Amazon rivers: investigation of relations with markers of oxidative stress.

Objective To investigate the relation between oxidative stress markers, human papillomavirus infection and cervical cancer precursor lesions. Methods The study comprised women aged 14 to 60 years living in communities located by Amazon rivers in the state of Pará (Itaituba, Limoeiro do Ajuru and Bragança, 126, 68 and 43 women respectively). Papanicolau smears and polymerase chain reaction tests for human papillomavirus DNA detection were performed. Blood samples were collected to test malondialdehyde, total and oxidized glutathione levels. Results Malondialdehyde, total and oxidized glutathione concentrations did not differ significantly (p>0.05) between women with and without low-grade squamous intraepithelial lesions across communities. Malondialdehyde levels (8.02nmols/mL) were almost five times higher in human papillomavirus-positive compared to human papillomavirus-negative women (1.70nmols/mL) living in Itaituba (statistically significant difference; p<0.05). Malondialdehyde levels did not differ significantly (p>0.05) between human papillomavirus-positive and human papillomavirus-negative women living in remaining communities. Significant (p<0.05) differences in total glutathione levels between human papillomavirus-positive and human papillomavirus-negative women (8.20µg/mL and 1.47µg/mL, respectively) were limited to those living in Bragança. Conclusion Malondialdehyde and total glutathione levels were significantly associated with human papillomavirus infection. However, lack of similar associations with squamous lesions suggest oxidative stress alone does not explain correlations with cervical carcinogenesis. Other factors may therefore be involved.

Human papillomavirus infection and cervical cancer precursor lesions in women living by Amazon rivers: investigation of relations with markers of oxidative stress / Infecção por papilomavírus humano e lesões precursoras do câncer cervicouterino em Ribeirinhas da Amazônia: avaliação da relação com marcadores de estresse oxidativo

ABSTRACT Objective To investigate the relation between oxidative stress markers, human papillomavirus infection and cervical cancer precursor lesions. Methods The study comprised women aged 14 to 60 years living in communities located by Amazon rivers in the state of Pará (Itaituba, Limoeiro do Ajuru and Bragança, 126, 68 and 43 women respectively). Papanicolau smears and polymerase chain reaction tests for human papillomavirus DNA detection were performed. Blood samples were collected to test malondialdehyde, total and oxidized glutathione levels. Results Malondialdehyde, total and oxidized glutathione concentrations did not differ significantly (p>0.05) between women with and without low-grade squamous intraepithelial lesions across communities. Malondialdehyde levels (8.02nmols/mL) were almost five times higher in human papillomavirus-positive compared to human papillomavirus-negative women (1.70nmols/mL) living in Itaituba (statistically significant difference; p<0.05). Malondialdehyde levels did not differ significantly (p>0.05) between human papillomavirus-positive and human papillomavirus-negative women living in remaining communities. Significant (p<0.05) differences in total glutathione levels between human papillomavirus-positive and human papillomavirus-negative women (8.20μg/mL and 1.47μg/mL, respectively) were limited to those living in Bragança. Conclusion Malondialdehyde and total glutathione levels were significantly associated with human papillomavirus infection. However, lack of similar associations with squamous lesions suggest oxidative stress alone does not explain correlations with cervical carcinogenesis. Other factors may therefore be involved.

RESUMO Objetivo Avaliar a relação de marcadores de estresse oxidativo com a infecção pelo papilomavírus humano e as lesões precursoras do câncer cervical. Métodos Foram incluídas mulheres ribeirinhas da Amazônia (a saber: 126 do município de Itaituba, 68 de Limoeiro do Ajuru e 43 de Bragança), todas do Estado do Pará, de 14 a 60 anos. Foram realizados testes Papanicolau e de reação em cadeia de polimerase para a detecção de DNA do papilomavírus humano. Coleta de amostras de sangue foi realizada para a avaliação do malondialdeído e a determinação da glutationa total e oxidada. Resultados As concentrações oxidativas do malondialdeído e os teores de glutationa total e oxidada não apresentaram diferença significativa (p>0,05) nas mulheres com e sem lesão intraepitelial escamosa de baixo grau, em todas as comunidades pesquisadas. Mulheres com papilomavírus humano em Itaituba apresentaram níveis de malondialdeído (8,02nmols/mL) quase cinco vezes maior quando relacionadas àquelas sem o HPV (1,70nmols/mL), com diferença estatística significativa (p<0,05). As outras comunidades não mostraram diferença estatística significativa entre as concentrações de malondialdeído nas mulheres com e sem papilomavírus humano (p>0,05). Os teores de glutationa total mostraram diferença significativa (p<0,05) somente em Bragança naquelas com (8,20µg/mL) e sem a infecção pelo papilomavírus humano (1,47µg/mL). Conclusão Houve associação significativa da resposta oxidativa do malondialdeído e da glutationa total com a infecção pelo papilomavírus humano, porém não houve diferença quando associada à lesão escamosa, sugerindo que o estresse oxidativo isoladamente não explica a relação com a carcinogênese do colo uterino, que deve ser influenciada ainda por outros fatores.

l-glutamine and l-alanine supplementation increase glutamine-glutathione axis and muscle HSP-27 in rats trained using a progressive high-intensity resistance exercise.

In this study we investigated the chronic effects of oral l-glutamine and l-alanine supplementation, either in their free or dipeptide form, on glutamine-glutathione (GLN-GSH) axis and cytoprotection mediated by HSP-27 in rats submitted to resistance exercise (RE). Forty Wistar rats were distributed into 5 groups: sedentary; trained (CTRL); and trained supplemented with l-alanyl-l-glutamine, l-glutamine and l-alanine in their free form (GLN+ALA), or free l-alanine (ALA). All trained animals were submitted to a 6-week ladder-climbing protocol. Supplementations were offered in a 4% drinking water solution for 21 days prior to euthanasia. Plasma glutamine, creatine kinase (CK), myoglobin (MYO), and erythrocyte concentration of reduced GSH and glutathione disulfide (GSSG) were measured. In tibialis anterior skeletal muscle, GLN-GSH axis, thiobarbituric acid reactive substances (TBARS), and the expression of heat shock factor 1 (HSF-1), 27-kDa heat shock protein (HSP-27), and glutamine synthetase were determined. In CRTL animals, high-intensity RE reduced muscle glutamine levels and increased GSSG/GSH rate and TBARS, as well as augmented plasma CK and MYO levels. Conversely, l-glutamine-supplemented animals showed an increase in plasma and muscle levels of glutamine, with a reduction in GSSG/GSH rate, TBARS, and CK. Free l-alanine administration increased plasma glutamine concentration and lowered muscle TBARS. HSF-1 and HSP-27 were high in all supplemented groups when compared with CTRL (p < 0.05). The results presented herein demonstrate that l-glutamine supplemented with l-alanine, in both a free or dipeptide form, improve the GLN-GSH axis and promote cytoprotective effects in rats submitted to high-intensity RE training.

Correlation of TGF-ß1 and oxidative stress in the blood of patients with melanoma: a clue to understanding melanoma progression?

TGF-ß1 and oxidative stress are involved in cancer progression, but in melanoma, their role is still controversial. Our aim was to correlate plasma TGF-ß1 levels and systemic oxidative stress biomarkers in patients with melanoma, with or without disease metastasis, to understand their participation in melanoma progression. Thirty patients were recruited for melanoma surveillance, together with 30 healthy volunteers. Patients were divided into two groups: Non-metastasis, comprising patients with tumor removal and no metastatic episode for 3 years; and Metastasis, comprising patients with a metastatic episode. The plasmatic cytokines TGF-ß1, IL-1 ß, and TNF-α were analyzed by ELISA. For oxidative stress, the following assays were performed: malondialdehyde (MDA), advanced oxidation protein products (AOPP) levels, total radical-trapping antioxidant parameter (TRAP) and thiol in plasma, and lipid peroxidation, SOD and catalase activity and GSH in erythrocytes. Patients with a metastatic episode had less circulating TGF-ß1 and increased TRAP, thiol, AOPP and lipid peroxidation levels. MDA was increased in both melanoma groups, while catalase, GSH, and IL-1ß was decreased in Non-metastasis patients. Significant negative correlations were observed between TGF-ß1 levels and systemic MDA, and TGF-ß1 levels and systemic AOPP, while a positive correlation was observed between TGF-ß1 levels and erythrocyte GSH. Lower levels of TGF-ß1 were related to increased oxidative stress in Metastasis patients, reinforcing new evidence that in melanoma TGF-ß1 acts as a tumor suppressor, inhibiting tumor relapse. These findings provide new knowledge concerning this cancer pathophysiology, extending the possibilities of investigating new therapies based on this evidence.

Behavior of Oxidative Stress Markers in Alcoholic Liver Cirrhosis Patients.

Alcohol is the most socially accepted addictive substance worldwide, and its metabolism is related with oxidative stress generation. The aim of this work was to evaluate the role of oxidative stress in alcoholic liver cirrhosis (ALC). This study included 187 patients divided into two groups: ALC, classified according to Child-Pugh score, and a control group. We determined the levels of reduced and oxidized glutathione (GSH and GSSG) and the GSH/GSSG ratio by an enzymatic method in blood. Also, protein carbonyl and malondialdehyde (MDA) content were estimated in serum. MDA levels increased in proportion to the severity of damage, whereas the GSH and GSSG levels decreased and increased, respectively, at different stages of cirrhosis. There were no differences in the GSH/GSSG ratio and carbonylated protein content between groups. We also evaluated whether the active consumption of or abstinence from alcoholic beverages affected the behavior of these oxidative markers and only found differences in the MDA, GSH, and GSSG determination and the GSH/GSSG ratio. Our results suggest that alcoholic cirrhotic subjects have an increase in oxidative stress in the early stages of disease severity and that abstinence from alcohol consumption favors the major antioxidant endogen: GSH in patients with advanced disease severity.

Blood markers of oxidative stress predict weaning failure from mechanical ventilation.

Patients undergoing mechanical ventilation (MV) often experience respiratory muscle dysfunction, which complicates the weaning process. There is no simple means to predict or diagnose respiratory muscle dysfunction because diagnosis depends on measurements in muscle diaphragmatic fibre. As oxidative stress is a key mechanism contributing to MV-induced respiratory muscle dysfunction, the aim of this study was to determine if differences in blood measures of oxidative stress in patients who had success and failure in a spontaneous breathing trial (SBT) could be used to predict the outcome of MV. This was a prospective analysis of MV-dependent patients (≥72 hrs; n = 34) undergoing a standard weaning protocol. Clinical, laboratory and oxidative stress analyses were performed. Measurements were made on blood samples taken at three time-points: immediately before the trial, 30 min. into the trial in weaning success (WS) patients, or immediately before return to MV in weaning failure (WF) patients, and 6 hrs after the trial. We found that blood measures of oxidative stress distinguished patients who would experience WF from patients who would experience WS. Before SBT, WF patients presented higher oxidative damage in lipids and higher antioxidant levels and decreased nitric oxide concentrations. The observed differences in measures between WF and WS patients persisted throughout and after the weaning trial. In conclusion, WF may be predicted based on higher malondialdehyde, higher vitamin C and lower nitric oxide concentration in plasma.

Sb(V) reactivity with human blood components: redox effects.

We assessed the reactivity of Sb(V) in human blood. Sb(V) reactivity was determined using an HPLC-HG-AFS hyphenated system. Sb(V) was partially reduced to Sb(III) in blood incubation experiments; however, Sb(III) was a highly unstable species. The addition of 0.1 mol L(-1) EDTA prevented Sb(III) oxidation, thus enabling the detection of the reduction of Sb(V) to Sb(III). The transformation of Sb(V) to Sb(III) in human whole blood was assessed because the reduction of Sb(V) in human blood may likely generate redox side effects. Our results indicate that glutathione was the reducing agent in this reaction and that Sb(V) significantly decreased the GSH/GSSG ratio from 0.32 ± 0.09 to 0.07 ± 0.03. Moreover, the presence of 200 ng mL(-1) of Sb(V) increased the activity of superoxide dismutase from 4.4 ± 0.1 to 7.0 ± 0.4 U mL(-1) and decreased the activity of glutathione peroxidase from 62 ± 1 to 34 ± 2 nmol min(-1) mL(-1).

Blood pressure-lowering effect of dietary (-)-epicatechin administration in L-NAME-treated rats is associated with restored nitric oxide levels.

Epidemiological and intervention studies have shown that the intake of certain chocolates or cocoa products decreases blood pressure (BP) in humans. (-)-Epicatechin is the most abundant flavanol present in cocoa seeds and its derived foods. This work investigates the effects of dietary (-)-epicatechin on BP in rats that received N(ω)-nitro-l-arginine methyl ester (L-NAME) for 4 days. (-)-Epicatechin administration prevented the 42mm Hg increase in BP associated with the inhibition of NO production in a dose-dependent manner (0.2-4.0g/kg diet). This BP effect was associated with a reduction in L-NAME-mediated increase in the indexes of oxidative stress (plasma TBARS and GSSG/GSH(2) ratio) and with a restoration of the NO concentration. At the vascular level, none of the treatments modified NOS expression, but (-)-epicatechin administration avoided the L-NAME-mediated decrease in eNOS activity and increase in both superoxide anion production and NOX subunit p47(phox) expression. In summary, (-)-epicatechin was able to prevent the increase in BP and in oxidative stress and restored NO bioavailability. The fact that (-)-epicatechin is present in several plants usually consumed by humans gives the possibility of developing diets rich in those plants or pharmacological strategies using that flavonoid to diminish BP in hypertensive subjects.

The effects of periodized concurrent and aerobic training on oxidative stress parameters, endothelial function and immune response in sedentary male individuals of middle age.

The vascular endothelium plays a key role in arterial wall homeostasis by preventing atherosclerotic plaque formation. A primary causal factor of endothelial dysfunction is the reactive oxygen species. Aerobic exercise is ascribed as an important adjuvant therapy in endothelium-dependent cardiovascular disease. However, little is known about the effects of concurrent (aerobic + strength) training on that. For a comparison of the effects of aerobic and concurrent physical training on endothelial function, oxidative stress parameters and the immunoinflammatory activity of monocytes/macrophages, 20 adult male volunteers of middle age were divided into a concurrent training (CT) programme group and an aerobic training group. The glutathione disulphide to glutathione ratio (GSSG/GSH) and plasma lipoperoxide (LPO) levels, as well as flow-mediated dilation (FMD), monocyte/macrophage functional activity (zymosan phagocytosis), body lipid profiles, aerobic capacity (maximal oxygen uptake) and strength parameters (one-repetition maximum test), were measured before and after the exercise training programmes. The CT exhibited reduced acute effects of exercise on the GSSG/GSH ratio, plasma LPO levels and zymosan phagocytosis. The CT also displayed improved lipid profiles, glycaemic control, maximal oxygen uptake and one-repetition maximum test values. In both the aerobic training and the CT, training improved the acute responses to exercise, as inferred from a decrease in the GSSG/GSH ratios. The aerobic sessions did not alter basal levels of plasma LPO or macrophage phagocytic activity but improved FMD values as well as lipid profiles and glycaemic control. In summary, both training programmes improve systemic redox status and antioxidant defences. However, the aerobic training was more efficient in improving FMD in the individuals studied.

Reduction in plasma levels of inflammatory and oxidative stress indicators after Roux-en-Y gastric bypass.

BACKGROUND: Obesity is considered to be associated with high levels of oxidative stress and inflammation. Anticipated weight loss secondary to bariatric surgery may offer an opportunity to evaluate this association. We studied a few markers of oxidative stress and inflammation in 20 obese patients submitted to Roux-en-Y gastric bypass (RYGBP). METHODS: Variations in plasma levels of indicators of oxidative stress (malondialdehyde (MDA), superoxide dismutase (SOD), catalase, glutathione (GSH), glutathione disulfide (GSSG), and total radical antioxidant parameter (TRAP)) and inflammation (alpha1-acid glycoprotein (AGP) and C-reactive protein (CRP)), as well as variations in plasma levels of leptin, glucose, glycated hemoglobin (HbA1c), and insulin were investigated in the preoperative period and 12 months postsurgery in 20 class III obese individuals submitted to bariatric surgery (obese group) and 20 non-obese individuals (control group). RESULTS: Twelve months postsurgery, there was a significant reduction (p < 0.01) in median values of BMI (46.75/30.17 kg/m(2)) and in plasma levels of MDA (16.70/9.11 nmol/g prot), SOD (10.70/9.24 U/mgHb), GSSG (210.80/148.20 mM/g of Hb), AGP (125.70/75.80 mg/dL), CRP (1.31/0.38 mg/dL), and leptin (15.04/3.58 ng/mL). A significant drop (p < 0.05) in plasma levels of HbA1c (5.81/4.98%) was also observed. On the other hand, a significant increase in plasma levels of GSH (2.002/2.823 mM/g of Hb) and TRAP (585.40/815.48 microM Trolox), p < 0.01, and in catalase plasma levels (12.06/13.22 Deltat/mgHb/min), p < 0.05, was seen. No statistically significant variations in glucose (96.3/84.8 mg/dL) or insulin plasma levels (9.91/7.88 U/mL) occurred. Calculated homeostasis model assessment index did not statistically change 12 months postsurgery (2.36/1.66). CONCLUSIONS: In the preoperative period, the obese group individuals showed higher oxidation and inflammation levels and lower indices of antioxidant defense than those of the control group. One year after RYGBP, an improvement in antioxidant protection, associated with a reduction in inflammatory and oxidative markers, was observed, indicating that these individuals presented a lower degree of oxidative stress.

Quantification of plasma reduced glutathione, oxidized glutathione and plasma total glutathione in healthy cats.

Glutathione is an important intracellular tripeptide with multiple functions. Abnormal glutathione metabolism is thought to play an important role in various diseases of cats. However, no data regarding concentration of plasma glutathione are available for domestic cats. This study discusses the development of a rapid, simple high pressure liquid chromatography method for measurement of reduced glutathione (GSH), oxidized glutathione (GSSH) and total glutathione (GSHt) in plasma, for the purpose of establishing baseline data for future studies. The mean concentrations of GSH, GSSH and GSHt were 4.51+/-1 microM; 19.44+/-3.79 microM (expressed as GSH equivalent) and 23.59+/-3.89 microM, respectively. This is the first report of plasma glutathione concentrations in this species.

Age-associated analysis of oxidative stress parameters in human plasma and erythrocytes.

Oxidative damage accumulation in macromolecules has been considered as a cause of cellular damage and pathology. Rarely, the oxidative stress parameters in healthy humans related to the individual age have been reported. The purpose of this study was to examine the redox status in plasma and erythrocytes of healthy individuals and determine correlations between these parameters and the aging process. The following parameters were used: malondialdehyde (MDA), protein carbonyls (PCO), 4-hydroxy-2,3-trans-nonenal (HNE), reduced glutathione (GSH), glutathione disulfide (GSSG) and uric acid (UA) in blood and plasma samples of 194 healthy women and men of ages ranging from 18 to 84 years. The results indicate that the balance of oxidant and antioxidant systems in plasma shifts in favor of accelerated oxidation during ageing. That is demonstrated by increases of MDA, HNE, GSSG and by the slight decrease of erythrocytic GSH with age. As the content of UA is more determined by metabolic and nutritional influences than by the balance between prooxidants and antioxidants there was no significant age-related change observed. For plasma concentrations of HNE the first time age-dependent reference values for healthy humans are presented.

In vivo rates of erythrocyte glutathione synthesis in adults with sickle cell disease.

Despite reports of lower GSH concentration in sickle cell disease (SCD), the in vivo kinetic mechanism(s) responsible for GSH deficiency is unknown. To determine whether suppressed synthesis was responsible for the lower erythrocyte GSH concentration, we used a primed intermittent infusion of [(2)H(2)]glycine to measure erythrocyte GSH synthesis in vivo in 23 individuals with homozygous beta(s) SCD and 8 healthy controls. Erythrocyte cysteine concentration, the rate-limiting precursor for GSH synthesis, plasma markers of oxidant damage, and dietary intakes of energy and protein were also measured. Compared with values of controls, SCD subjects had significantly lower erythrocyte GSH (P < 0.04) and cysteine concentrations (P < 0.004) but significantly faster fractional rates of GSH synthesis (P < 0.02). The absolute rates of GSH synthesis in SCD subjects compared with control subjects was greater by approximately 57% (P = 0.062). However, the concentrations of markers of oxidative damage, plasma derivatives of reactive oxygen metabolites, plasma nitrotyrosine, urinary isoprostane-to-creatinine ratio, and GSH-to-GSSG ratio, as well as dietary intakes of energy, protein, and GSH precursor amino acids, were not different between SCD subjects and controls. The findings of this study suggest that the lower erythrocyte GSH of SCD patients is not due to suppressed synthesis or impaired regeneration but rather to increased consumption. In addition, the lower erythrocyte cysteine concentration plus the faster rate of GSH synthesis strongly suggest that the endogenous cysteine supply is not sufficient to meet all anabolic demands; hence, cysteine may be a conditionally essential amino acid in individuals with SCD.

Oxidative stress in asphyxiated term infants resuscitated with 100% oxygen.

OBJECTIVE: To test the hypothesis that resuscitation of asphyxiated infants with pure oxygen causes hyperoxemia and oxidative stress.Study design Asphyxiated term newborn infants (n = 106) were randomly resuscitated with room air (RAR = 51) or 100% oxygen (OxR = 55). The Apgar score, time of the first cry, and establishment of a sustained pattern of respiration were recorded. Assays performed included: blood gases; reduced glutathione (GSH) and oxidized glutathione (GSSG) in whole blood; glutathione-related enzyme activities; and superoxide dismutase activity (SOD) in erythrocytes. RESULTS: The RAR group needed less time of ventilation for resuscitation (5.3 +/- 1.5 vs 6.8 +/- 1.2 min; P <.05). Pure oxygen caused hyperoxemia (PO(2), 126.3 +/- 21.8 mm Hg) that did not occur with the use of room air (PO(2), 72.2 +/- 6.8 mm Hg). GSH was decreased and GSSG, the glutathione cycle enzymes, and SOD activities were increased in both asphyxiated groups. However, the 100% oxygen-resuscitated group showed significantly greater alterations that correlated positively with hyperoxemia. CONCLUSIONS: Asphyxia causes oxidative stress in the perinatal period, and resuscitation with 100% oxygen causes hyperoxemia and increased oxidative stress. Because there are no advantages to resuscitation with 100% oxygen, room air may be preferred under certain circumstances for the resuscitation of asphyxiated neonates.

Oxidative stress causes intracellular reversible S-thiolation of chicken hemoglobin under diamide and xanthine oxidase treatment.

Time courses of total (GSH-t), disulfide (GSSG), and mixed disulfide (PSSG) forms of glutathione were studied in chicken blood submitted to oxidative stress induced by diamide or by the reactive oxygen species (ROS)-producing system xanthine/xanthine oxidase (X/XO). Diamide-treated blood induced an immediate increase in GSSG and PSSG, while X/XO produced a slow and sustained stress with increased values of GSSG and PSSG only after 30 and/or 60 min of incubation. Both total protein S-thiolation (mixed disulfide with glutathione) and dethiolation and hemoglobin A S-thiolation and dethiolation were clearly observed. Hemoglobin A (Hb A) was the major S-thiolated protein. We further characterized chicken Hb S-thiolation through the reaction of Hb with GSSG or the GSH/GSSG redox couple. Methemoglobin levels did not change with diamide or with X/XO treatment. Present results suggest that the most reactive cysteine pair of Hb A, the major chicken Hb, might function as an antioxidant under in vivo oxidative stress conditions.

Involvement of available SH groups in the heterogeneity of hemoglobin from the tortoise Geochelone carbonaria.

Geochelone carbonaria hemoglobin (Hb) was analyzed by polyacrylamide gel electrophoresis (PAGE) and purified by ion exchange chromatography on CM-cellulose. Seven fractions were obtained using fresh Hb preparations. CM-cellulose chromatography of Hb reacted with iodoacetamide, showed one minor (HbI) and one major band (HbII). Analysis of the molecular masses of recently collected Hb and of aged solutions determined by gel filtration showed that polymerization increased with the duration of storage. The reaction with oxidized glutathione changed the electrophoretic pattern of Hb, and highlighted the bands corresponding to glutathionyl-Hb. The presence of these bands in fresh Hb solutions and in alkylated preparations suggests that they may occur in vivo. PAGE under dissociating conditions showed that the hemolysate contained 3 different polypeptide chains (G1, G2 and G3). Both Hb components shared the G1 globin chain with HbI containing G1 and G2 and HbII, G1 and G3 chains.