Plasma Hydroperoxide Concentrations Research Articles

Plasma Oxidative State Induced by Exercise in Young Heat-Not-Burn Cigarette Users.

Oxidative state, a risk factor for several diseases, is increased by habitual conventional cigarette (CC) smoking. Reports have demonstrated that heat-not-burn cigarettes (HNBCs), which have recently become popular among smokers, generate less oxidative state than CC in smokers with a long smoking history. However, no previous study has examined oxidative state in young HNBC users. Previously, we reported that exercise induces a greater oxidative state in young CC smokers than in never-smokers of similar age, but there was no difference in resting oxidative state. This study aimed to clarify the resting and exercise-induced oxidative states in young HNBC users, compared with those in never-smokers and CC users of similar age. Healthy young never-smokers, HNBC users, and CC users were recruited, and they underwent the Wingate anaerobic test. Blood samples were collected before and after exercise, and the plasma hydroperoxide concentration, a marker of oxidative state, was measured. No significant differences in pre-exercise plasma hydroperoxide concentrations were detected among never-smokers, HNBC users, and CC users (n = 10 each). Plasma hydroperoxide concentration was significantly increased after exercise in all participants. The exercise induced a significant increase in plasma hydroperoxide concentration in HNBC users compared with that in never-smokers (p < .005), but it was significantly decreased compared with that in CC users (p < .01). The use of HNBC increased exercise-induced plasma oxidative state compared with that in never-smokers, indicating that HNBC may lead to the risk of oxidative damage. This study, for the first time, reports exercise-induced oxidative state in young HNBC users compared with never-smokers and CC users. The exercise-induced oxidative state in HNBC users was higher than that in never-smokers and lower than that in CC users. Our study suggests that the use of HNBCs increases the risk of acute oxidative damage.

Timescale and colony-dependent relationships between environmental conditions and plasma oxidative markers in a long-lived bat species.

To increase the applicability and success of physiological approaches in conservation plans, conservation physiology should be based on ecologically relevant relationships between physiological markers and environmental variation that can only be obtained from wild populations. Given their integrative and multifaceted aspects, markers of oxidative status have recently been considered in conservation physiology, but still need to be validated across environmental conditions and locations. Here, we examined whether inter-annual variation in two oxidative markers, plasma antioxidant capacity and plasma hydroperoxides, followed inter-annual variation in temperature anomalies and associated vegetation changes in four colonies of long-lived greater mouse-eared bats (Myotis myotis) monitored over five consecutive years. We found that the plasma antioxidant capacity of bats decreased while plasma hydroperoxide concentrations increased with increasing temperature anomalies occurring in the two weeks before blood sampling. Moreover, the antioxidant defences of these bats reflected vegetation indices, which themselves reflected the thermal conditions experienced by bats in their foraging habitat. Variation in oxidative markers therefore appears to be due to variation in thermoregulatory costs and to indirect changes in foraging costs. Overall, these results validate the use of markers of oxidative status in conservation physiology to monitor thermal perturbations recently experienced by animals in their natural habitat. However, even though oxidative markers varied in the same direction in all four bat colonies across years, the amplitude of their response differed. If these different physiological responses reflect different performances (e.g. productivity, survival rate) between colonies, this implies that, if necessary, conservation measures may need to be applied at the local scale.

A Mild-Exercise Support Program and Its Affect on Physical Strength and Metabolic Improvement in the Elderly

In the present study, we investigated the effectiveness of a support program that involved sessions of mild exercise that lasted for approximately 90 minutes practiced over a period of 3 months by 26 healthy elderly men and women (66.8 ± 4.3 years of age) who had never had guidance on health-promoting exercise. Before and after the program, the subjects underwent examinations to assess the effects on their physical strength, blood, glucose metabolism, lipid metabolism, and oxidative stress. We also studied the effects of the continuation of physical training in 8 men and women (67.6 ± 4.7 years of age) who participated in a similar exercise program for an additional 12 months (15 months in total). The 3-month physical training improved the leg strength (measured as the consecutive number of steps made up onto and then back down from a footstool in 30 seconds) (p &lt; 0.01), and significantly lowered the serum malondialdehyde-modified low-density lipoprotein (MDL-LDL) levels (p &lt; 0.01). In the 8 subjects who continued the additional 12 months of training, the increased leg strength was retained throughout the 15-months (p &lt; 0.05), and the time required to walk 400 m was significantly shortened from 279 ± 14 to 255 ± 24 seconds (p &lt; 0.05). Among the blood biochemistry parameters tested, high-density lipoprotein cholesterol (HDL-C) showed an 11% increase from 62.8 ± 14.7 to 69.4 ± 13.0 mg/dl (p &lt; 0.05). In addition, the plasma hydro peroxide concentration (derivatives of reactive oxygen metabolites [d-roms]) was decreased by 28% from 394 ± 52 to 284 ± 32 U.Carr (p &lt; 0.01), showing a marked decrease in oxidative stress from a moderate level to a normal level. These results suggest that, when continued long term, even a mild exercise program that is easily implementable by elderly people can produce noticeable measures of better health, particularly with respect to walking ability and oxidative stress.

Sow environment during gestation: part I. Influence on maternal physiology and lacteal secretions in relation with neonatal survival

In pig husbandry, pregnant females are often exposed to stressful conditions, and their outcomes on maternal and offspring health have not been well evaluated. The present study aimed at testing whether improving the welfare of gestating sows could be associated with a better maternal health during gestation, changes in the composition of lacteal secretions and improvement in piglet survival. Two contrasted group-housing systems for gestating sows were used, that is, a French conventional system on slatted floor (C, 49 sows) and an enriched system using larger pens on deep straw (E, 57 sows). On the 105th days of gestation (DG105), sows were transferred into identical farrowing crates on slatted floor. Saliva was collected from all sows on DG35, DG105 and DG107. Blood samples were collected on DG105 from all sows and on the 1st day of lactation (DL1) from a subset of them (C, n=18; E, n=19). Colostrum and milk samples were collected from this subset of sows at farrowing (DL0) and DL4. Saliva concentration of cortisol was greater in C than in E sows at DG35 and DG105, and dropped to concentrations comparable to E sows after transfer into farrowing crates (DG107). On DG105, plasma concentrations of haptoglobin, immunoglobulins G (IgG) and A (IgA), blood lymphocyte counts and plasma antioxidant potential did not differ between groups (P > 0.10), whereas blood granulocyte count, and plasma hydroperoxide concentration were lower in E than in C sows (P < 0.05). Concentrations of IgG and IgA in colostrum and milk did not differ between the two groups. The number of cells did not differ in colostrum but was greater in milk from E than C sows (P < 0.05). Pre-weaning mortality rates were lower in E than C piglets (16.7% v. 25.8%, P < 0.001), and especially between 12 and 72 h postpartum (P < 0.001). Plasma concentration of IgG was similar in E and C piglets on DL4. In conclusion, differences in salivary cortisol, blood granulocyte count and oxidative stress markers between groups suggested improved welfare and reduced immune solicitation during late gestation in sows of the E compared with the C system. However, the better survival observed for neonates in the E environment could not be explained by variations in colostrum composition.

Effects of hydroxytyrosol dose on the redox status of exercised rats: the role of hydroxytyrosol in exercise performance

BackgroundHydroxytyrosol (HT) is a polyphenol found in olive oil that is known for its antioxidant effects. Here, we aimed to describe the effects of a low and high HT dose on the physical running capacity and redox state in both sedentary and exercised rats.MethodsMale Wistar rats were allocated into 6 groups: sedentary (SED; n = 10); SED consuming 20 mg/kg/d HT (SED20; n = 7); SED consuming 300 mg/kg/d HT (SED300; n = 7); exercised (EXE; n = 10); EXE consuming 20 mg/kg/d HT (EXE20; n = 10) and EXE consuming 300 mg/kg/d HT (EXE300; n = 10). All the interventions lasted 10 weeks; the maximal running velocity was assessed throughout the study, whereas daily physical work was monitored during each training session. At the end of the study, the rats were sacrificed by bleeding. Hemoglobin (HGB) and hematocrit (HCT) were measured in the terminal blood sample. Moreover, plasma hydroperoxide (HPx) concentrations were quantified as markers of lipid peroxidation.ResultsIn sedentary rats, HT induced an antioxidant effect in a dose-dependent manner without implications on running performance. However, if combined with exercise, the 300 mg/kg/d HT dosage exhibited a pro-oxidant effect in the EXE300 group compared with the EXE and EXE20 groups. The EXE20 rats showed a reduction in daily physical work and a lower maximal velocity than the EXE and EXE300 rats. The higher physical capacity exhibited by the EXE300 group was achieved despite the EXE300 rats expressing lower HGB levels and a lower HCT than the EXE20 rats.ConclusionsOur results suggest that a high HT dose induces a systemic pro-oxidant effect and may prevent the loss of performance that was observed with the low HT dose.

Circulating Glutamate and Taurine Levels Are Associated with the Generation of Reactive Oxygen Species in Paroxysmal Atrial Fibrillation.

Atrial fibrillation (AF) is the most common cardiac arrhythmia, but its proarrhythmic mechanism remains to be elucidated. Glutamate (Glu) and taurine (Tau) are present in the myocardium at substantially higher concentrations than in the plasma, suggesting their active role in myocardium. Here, we tested the hypothesis that the metabolism of Glu and Tau is altered in association with the generation of reactive oxygen species (ROS) in patients with AF. Fifty patients with paroxysmal AF and 50 control subjects without a history of AF were consecutively enrolled. Circulating Glu and Tau levels were measured and correlations between Glu/Tau and ROS levels were examined. Glu/Tau content was significantly higher in patients with AF versus controls (Glu: 79.2 ± 23.9 versus 60.5 ± 25.2 nmol/L; Tau: 78.8 ± 19.8 versus 68.5 ± 20.8 nmol/L; mean ± standard deviation (SD), p < 0.001 for both). Glu/Tau levels also showed an independent association with AF by multiple logistic regression analysis. Glu and Tau levels both showed significant positive associations with plasma hydroperoxide concentrations. These data suggest a novel pathophysiological role of Glu and Tau in association with ROS production in paroxysmal AF, providing new insights into the elevated amino acid content in cardiac disease.

Cigarette Smoking does not Induce Plasma or Pulmonary Oxidative Stress after Moderate-intensity Exercise

[Purpose] Cigarette smoking increases oxidative stress, which is a risk factor for several diseases. Moreover, strenuous exercise has been shown to induce plasma and pulmonary oxidative stress in young cigarette smokers. However, no previous reports have demonstrated whether plasma and pulmonary oxidative stress occur after moderate-intensity exercise. Therefore, the aim of this study was to clarify whether moderate-intensity exercise induces pulmonary and plasma oxidative stress in smokers. [Subjects] Ten young male smokers and 10 young male nonsmokers participated in this study. [Methods] Plasma hydroperoxide concentrations were measured at baseline and then immediately and 15 min after moderate-intensity exercise. Hydrogen peroxide concentrations in exhaled breath condensate were measured at baseline and after exercise. [Results] No significant interactions were found between smokers and nonsmokers in terms of hydroperoxide or hydrogen peroxide concentrations following moderate-intensity exercise at any time point. [Conclusion] These findings suggested that moderate-intensity exercise did not induce plasma or pulmonary oxidative stress in young cigarette smokers.

Plasma oxidative stress is induced by single‐sprint anaerobic exercise in young cigarette smokers

Cigarette smoking increases oxidative stress, which is a risk factor for several diseases. Smoking has also been reported to enhance plasma oxidative stress during strenuous exercise. However, no prior study has examined the changes in plasma oxidative stress after single-sprint anaerobic exercise in cigarette smokers. The purpose of this study was to investigate these changes in young cigarette smokers by measuring reactive oxygen species generation and total antioxidant content. Participants were 15 male smokers (mean age: 25·9±2·9years) and 18 male non-smokers (mean age: 24·2±4·3years). Hydroperoxide concentration and biological antioxidant potential (BAP) in plasma were measured at baseline and after the Wingate anaerobic test. A significant interaction between group and time was observed for plasma hydroperoxide concentration (P=0·037). Plasma hydroperoxide concentration was significantly increased after exercise in both smokers and non-smokers (P=0·001 and <0·001, respectively). However, no significant interaction was observed between groups by time on plasma BAP (P=0·574), and a main effect of time was observed (P<0·001). Plasma BAP was significantly increased after exercise in both groups (both, P<0·001). These findings indicate that plasma oxidative stress is higher in cigarette smokers than in non-smokers after single-sprint anaerobic exercise, which may increase the risk of oxidative damage.

O-β-N-acetyl-D-glucosaminidase in erythrocytes of Italian air force acrobatic pilots

Italian air force acrobatic pilots are occupationally susceptible to oxidative stress damage that can lead to overt signs and symptoms of hypoxia. We propose erythrocyte glycohydrolases as new, sensitive markers to assess oxidative stress. We measured erythrocyte concentrations of beta-D-glucuronidase (GCR), hexosaminidase, O-beta-N-acetyl-D-glucosaminidase (O-GlcNAcase), plasma membrane fluidity and plasma hydroperoxides from 19 pilots and compared these to 40 matched healthy subjects. Plasma hydroperoxide concentrations and the erythrocyte ghosts' fluorescence anisotropy were significantly lower in the pilots. Concentrations of GCR, O-GlcNAcase and hexosaminidase in pilots were significantly different from controls, being lower, higher and higher, respectively. Pilots, in spite of their oxidative stress, are better protected than controls, probably as a result of their physical training and proper diet. Our results confirm that erythrocytes, with their 120-day life span, are a useful model for investigating physiopathological conditions, and glycohydrolases are good markers for monitoring oxidative stress, even in healthy people.

Hemolytic suppression roles of taurine in yellowtail Seriola quinqueradiata fed non-fishmeal diet based on soybean protein

To elucidate the hemolytic suppression roles of taurine and the necessity of dietary taurine supplementation in yellowtail Seriola quinqueradiata fed a diet without fishmeal, juvenile fish with an initial body weight of 250 g were fed for 40 weeks in floating net cages on soybean protein diets supplemented with 0, 3.0, 4.5 and 6.0% taurine. Taurine concentration of the experimental diets were 0.03, 33.9, 52.8 and 71.6 mg/g, respectively. On the 21st week, fish fed the taurine unsupplemented diet had inferior growth and feed performances, higher death, and there were incidences of green liver and hemolytic anemia. In this group, hepatic and plasma taurine concentrations, serum osmolality and osmotic tolerance of erythrocytes (EC50 value) were significantly lower, and plasma hydroperoxide concentration was markedly higher than in the taurine supplemented groups. These conditions markedly improved corresponding with the increase of dietary taurine concentration. These results indicate that taurine plays a role in hemolytic suppression through osmoregulation and biomembrane stabilization in fish. In addition, it is suggested that yellowtail requires dietary taurine as an essential nutrition for maintaining physiological condition normally.

Measurement of plasma hydroperoxide concentration by FOX-1 assay in conjunction with triphenylphosphine

Introduction: Hydroperoxides are well-recognized reactive oxygen species which are associated with oxidative stress, a phenomenon of current clinical interest as oxidative stress is associated with a number of disease condition. Ferrous ion oxidation xylenol orange (FOX) methods of hydroperoxide estimation has outdated other methods available for hydroperoxide estimation. Two versions FOX assays are described in the literature, FOX-1 and FOX-2, in which FOX-1 is more sensitive. Methods: we increased the sensitivity of FOX-1 assay by stabilizing the reagent pH 1.7–1.8. Analogous to FOX-2 assay, we have modified FOX-1 assay by using it in conjunction with triphenylphosphine and butylated hydroxytoluene, thus increasing the specificity of FOX-1 assay for hydroperoxide. By modified FOX-1 method, we estimated plasma hydroperoxide concentration of normal human subjects and of diabetic patients and compared with FOX-2 method. Results: The FOX-1 method showed a significant high value of plasma hydroperoxide concentration compared to FOX-2 method both in normal subjects and diabetic patients with a significant correlation. By modified FOX-1 method, the recovery percentage of cumene hydroperoxide was better in biological samples when compared to FOX-2 method. Conclusion: The modified FOX-1 method is equally specific for hydroperoxide determination when compared to FOX-2 but is more sensitive.

Moderate coffee consumption increases plasma glutathione but not homocysteine in healthy subjects.

The consumption of unfiltered coffee, containing bioactive diterpenes, causes an increase in plasma homocysteine concentration. A slight increase in plasma homocysteine is also caused by large quantities of filtered coffee. Coffee terpenes also raise plasma glutathione in mice. To verify the effect of Italian-style coffee consumption on the plasma concentration of glutathione and homocysteine in healthy subjects. Twenty-two volunteers consumed five cups of coffee per day for 1 week and maintained their usual diet. Five subjects were enrolled as controls. The intervention trial was preceded and followed by seven coffee-free days. Plasma glutathione increased by 16% (P < 0.05) on coffee consumption, and returned to the original concentration after the washout period. The increase in plasma homocysteine concentration (13% after 1 week of coffee intake) was not significant. No differences in glutathione or homocysteine concentration were observed in the control group. No variation of plasma hydroperoxide concentration was detectable. A coffee intake regimen, representing the average consumption of coffee drinkers in Italy, increased the plasma concentration of glutathione, but no significant increase in the plasma homocysteine concentration was detected.

Effects of dietary antioxidant supplementation on oxidative damage and resistance to oxidative damage during prolonged exercise in sled dogs.

To determine effects of dietary antioxidant supplementation on plasma concentrations of antioxidants, exercise-induced oxidative damage, and resistance to oxidative damage during exercise in Alaskan sled dogs. 62 Alaskan sled dogs. Dogs were matched for age, sex, and ability and assigned to 1 of 3 groups: sedentary and nonsupplemented (control [C]; n = 21), exercised and supplemented (S; 22), and exercised and nonsupplemented (N; 19). Dogs in group S were given 400 units of alpha-tocopherol acetate, 3 mg of beta-carotene, and 20 mg of lutein orally per day for 1 month, then dogs in groups S and N completed 3 days of exercise. Blood samples were collected before and after 1 and 3 days of exercise and after 3 days of rest. Plasma antioxidant concentrations were determined, and oxidative damage to DNA (plasma 7,8 dihydro-8-oxo-2'deoxyguanosine [8-oxodG] concentration) and membrane lipids (plasma hydroperoxide concentration) and resistance of plasma lipoproteins to oxidation were assessed. Supplementation increased plasma concentrations of alpha-tocopherol, beta-carotene, and lutein. Plasma concentration of alpha-tocopherol increased and concentration of lutein decreased in group S with exercise. Concentration of 8-oxodG decreased in group S but increased in group N during and after exercise. Lag time of in vitro oxidation of lipoprotein particles increased with exercise in group S only. Dietary supplementation with antioxidants resulted in increased plasma concentrations of antioxidants. Moreover, supplementation decreased DNA oxidation and increased resistance of lipoprotein particles to in vitro oxidation. Antioxidant supplementation of sled dogs may attenuate exercise-induced oxidative damage.

Reperfusion injury is greater with delayed restoration of venous outflow in concurrent arterial and venous limb injury.

Complex limb trauma often involves combined arterial and venous injury, and the resultant ischaemia-reperfusion injury (IRI) causes both local and remote organ injury. This study assessed the influence of the timing of restoration of venous drainage on IRI. Male New Zealand white rabbits (n = 36) were randomized into six groups: sham operation (group 1) and unilateral hind limb arterial and venous occlusion for 1 h followed by no reflow for 2 h (group 2), arterial and venous reflow for 2 h (group 3), arterial reflow alone for 2 h (group 4), arterial reflow alone for 1 h followed by arterial and venous (delayed) reflow for a further 1 h (group 5), and pretreatment with an enteral combination antioxidant before occlusion of both artery and vein and delayed venous reflow (group 6). Plasma hydroperoxide (HPO) and glutathione peroxidase concentration, hind limb skeletal muscle and lung tissue wet : dry weight ratios and myeloperoxidase (MPO) concentration were measured. The plasma HPO level in the femoral vein effluent was significantly greater after delayed venous reflow (mean(s.e.m.) 2. 02(0.54) micromol/l) than in control animals (0.98(0.10) micromol/l) (P < 0.05). There was also a significantly greater tissue wet : dry weight ratio after delayed venous reflow than in controls, in skeletal muscle (mean(s.e.m.) 6.89(0.14) versus 5.34(0.54); P < 0. 05) and lung (9.20(1.14) versus 7.23(0.38); P < 0.05) tissue. Lung tissue MPO activity was significantly greater after delayed venous reflow compared with controls (3.20(0.28) versus 1.86(0.14) units/g; P < 0.005), and also in comparison to simultaneous arterial and venous reflow (2.40(0.24) units/g; P < 0.05). In the antioxidant pretreatment group there was no significant increase in plasma HPO concentration, tissue MPO level or tissue wet : dry weight ratio compared with the control group. In combined major arterial and venous injury of the limb, delayed restoration of venous drainage leads to significantly greater local skeletal muscle injury and remote neutrophil-mediated lung injury. These results support the clinical rationale for early restoration not only of arterial inflow but also venous drainage by means of intraluminal shunts.

In major limb vessel trauma, reperfusion injury is increased by delayed venous reflow and prevented by antioxidant pretreatment

Abstract Background Clinical experience of the early use of intraluminal shunts in major limb trauma at this centre aimed at restoring arterial inflow and venous outflow has been shown to reduce amputation rates and morbidity. In a model of combined arterial and venous limb vessel trauma, ischaemia–reperfusion injury caused by delayed restoration of venous drainage locally on skeletal muscle and remotely on lung was studied. Furthermore, using antioxidant pretreatment the possibility of reversing these detrimental effects was investigated. Methods New Zealand white rabbits (n = 36) were randomized into six groups: (1) sham operation; unilateral hind limb arterial and venous occlusion for 1 h followed by (2) no reflow for 2 h; (3) arterial and venous reflow for 2 h; (4) arterial reflow alone for 2 h; (5) arterial reflow for 1 h followed by arterial and venous (delayed) reflow for a further 1 h; (6) pretreatment with an enteral combination antioxidant before combined arterial and venous occlusion with delayed venous reflow. Plasma hydroperoxide (HPO) concentration in the femoral vein was a measure of lipid peroxidation. Hindlimb skeletal muscle and lung wet-to-dry weight ratio reflected tissue oedema, and myeloperoxidase (MPO) tissue levels estimated neutrophil sequestration. Plasma glutathione peroxidase (GPx) levels in systemic vein (SV) and femoral vein effluent (FV) reflected antioxidant status. Hindlimb skeletal muscle injury was graded histologically. Results Conclusion In combined major arterial and venous vessel injury of the limb, delayed venous repair leads to significantly greater local skeletal muscle injury and remote neutrophil-mediated lung damage. Reversal of these detrimental effects with antioxidant pretreatment suggests that failure of antioxidant scavenging systems may be central to the injury accentuated by delayed venous drainage. These results support the clinical rationale for early restoration of not only arterial inflow but also venous drainage by intraluminal shunts.

The effect of hormone replacement therapy on the oxidation of low density lipoprotein in postmenopausal women

The oxidative modification of low density lipoprotein (LDL) is important in the pathogenesis of atherosclerosis, and oestrogen has been shown to inhibit copper and cell mediated oxidation of LDL in vitro. We have investigated the effect of oral and transdermal oestrogens (oestradiol valerate 1 mg, conjugated equine oestrogens 0.625 mg and patches releasing 50 μg oestradiol daily), oestrogen implants (oestradiol 50 mg) and oral combined oestrogen and progestogen (oestradiol valerate 2 mg with medroxyprogesterone acetate 5 mg and oestradiol valerate 2 mg with norethisterone acetate 1 mg), on the susceptibility of LDL to oxidation in postmenopausal women (total n=56). Oxidation of LDL was initiated by the addition of copper ions, and monitored by measurement of conjugated dienes. Changes in fasting serum levels of total cholesterol, LDL, HDL and triglycerides were also evaluated, as were changes in LDL composition. Total cholesterol decreased by 5.5% ( P<0.05) with CEE, 6.8% with oestradiol implants ( P<0.05), 9.3% with oestradiol+MPA ( P<0.01) and 10% with oestradiol+norethisterone ( P<0.05). There were reductions in LDL with oral oestradiol valerate (7.8%) ( P<0.05), CEE (13.8%) ( P<0.01) and oestradiol combined with MPA (12.7%) ( P<0.05). HDL increased by 7.1% ( P<0.01) and 6.3% ( P<0.05), with oestradiol valerate and CEE respectively, and decreased by 9% ( P<0.05) with implants and by 14.7% with oestradiol combined with norethisterone ( P<0.01). Triglycerides were significantly increased with CEE (14.9%) and reduced with oestradiol implants (15.2%) (both P<0.05). While there was no change in the ratio of `cholesterol ester' to `free cholesterol' within LDL with any of the HRT preparations, a reduction in total cholesterol and cholesterol ester content of LDL occurred with transdermal oestradiol and a reduction in free cholesterol occurred with oestradiol plus MPA. Although we found a small but significant decrease in plasma hydroperoxide concentration four weeks after insertion of the oestradiol implant from 1.17±0.06 to 1.03±0.04 μmol/l ( P<0.05), we found no significant change in the lag time to oxidation, or in the maximum rate of propagation of the reaction, after treatment with any of the above forms of hormone replacement therapy. This study does not therefore support the role of oestrogens as antioxidants in vivo.

E-selectin plasma concentration is influenced by glycaemic control in NIDDM patients: possible role of oxidative stress.

Although elevated levels of soluble E-selectin and intercellular cell adhesion molecules-1 (ICAM-1) have been reported in non-insulin-dependent diabetes mellitus (NIDDM), it is not clear by what mechanism this elevation occurs and whether or not it is related to glycaemic control. In this study we analyse: 1) the relation of glycaemic control with the concentrations of E-selectin, vascular cell adhesion molecules-1 (VCAM-1) and ICAM-1 in NIDDM patients: 2) whether metabolic control can affect the oxidative stress (as measured by plasma hydroperoxide concentration and susceptibility of LDL to in vitro oxidation) and hence the adhesion molecule plasma concentrations. Thirty-four (19 males and 15 females) poorly controlled NIDDM patients were studied. All parameters were evaluated at the beginning of the study and after 90 days of dietary and pharmacological treatment. The treatment decreased HbA1c (p < 0.001), E-selectin (p < 0.001), plasma hydroperoxides (p < 0.003) and the susceptibility of LDL to in vitro oxidation (lag phase) (p < 0.0001). Before treatment HbA1c, lag phase and lipid hydroperoxides correlated with E-selectin plasma concentration (r = 0.51, -0.57 and 0.54, respectively, p < 0.01). There was also a correlation between HbA1c and lag phase (p < 0.01) and between HbA1c and lipid hydroperoxides (p < 0.01). In addition, the variations of HbA1c, lag phase and lipid hydroperoxide values correlated with those for E-selectin concentration after 90 days' treatment (r = 0.54, -0.64 and 0.61, respectively, p < 0.01). In multiple linear correlation analysis, however, the partial correlation coefficients of HbA1c (basal and variations) with E-selectin concentration (basal and variations) fell to non-significant values (r = 0.12 and 0.25, respectively) when LDL lag phase and plasma hydroperoxides were kept constant. The results indicate that the improvement of metabolic control in NIDDM patients is associated with a decrease of E-selectin plasma levels; they also suggest that glycaemic control per se is not directly implicated in determining E-selectin plasma concentration; glycaemic control could affect E-selectin concentration through its effect on oxidative stress.

Contribution of hyperoxia to lipid peroxidation in coronary artery operations: Should we keep a low oxygen tension?

Oxygen free radicals are known to play a significant role in the morbidity associated with cardiac operations. They seem to be produced through two major pathways, heart ischemia-reperfusion I and leukocyte aetivation. 2 Another possible pathway might be the hyperoxia that occurs during cardiopulmonary bypass (CPB) and within a short period during which the patient is still supported by mechanical ventilation. The contribution of hyperoxia to oxygen free radical generation and consequent lipid peroxidation in cardiac operations has to date not been addressed. The purpose of the present study was to elucidate the role of hyperoxia in lipid peroxidation during cardiac operations. Patients and methods. After obtaining informed consent, we entered 24 conseeutive patients scheduled for routine coronary artery operation into the study. Patients in cardiogenic shock were excluded from the study. The mean age was 63.2 _+ 2.1 years (range 44 to 83) and there were 17 men and 7 women. Ischemic time was 46.8 + 3.2 minutes (range 24 to 92) CPB time 98.7 _+ 5.4 minutes (range 67 to 174), and blood partial 02 tension (Po2) during CPB 45.4 -+ 1.2 kPa (range 29 to 57). Anesthesia was instituted with fentanyl, pancuronium, and isoflurane. A membrane oxygenator (CML membrane hollow-fiber oxygenator, Cobe Inc., Lakewood, Colo.) was used for extracorporeal circulation and pH management was done with the pH-stat method. Myocardial protection was achieved with the use of intermittent fibrillation. The nasopharyngeal temperature was maintained at approximately 32 ° C during the CPB period. No patient received drugs known specifically to scavenge free radicals (allopurinol, mannitol, captopril, and desferrioxamine). Anesthetists and perfusionists responsible for controlling the degree of oxygenation were blind to the study. Peripheral venous blood samples for determination of whole plasma hydroperoxide concentrations (WPHC) were obtained before the operation and 1, 6, 24, and 72 hours after CPB was discontinued. The venous blood

Measurement of Plasma Hydroperoxide Concentrations by the Ferrous Oxidation-Xylenol Orange Assay in Conjunction with Triphenylphosphine

We describe the application of the FOX2 (ferrous oxidation in xylenol orange, version 2) method to the measurement of hydroperoxides in plasma. Authentic plasma hydroperoxides can be determined by a strategy in which the hydroperoxide reductant, triphenylphosphine, is used to discriminate between the background signal generated by ferric ions present in plasma and that generated by hydroperoxide in plasma. The approach was validated by extraction of total lipids from plasma using ethyl acetate prior to assay with the FOX2 reagent. Plasma from 23 normal individuals contained hydroperoxide in the range of 0.22 to 7.8 μM with a mean of 3.02 μM and a population standard deviation of 1.85 μM. After partitioning with ethyl acetate, plasma hydroperoxide levels ranged from 0.22 to 6.22 μM, with a mean value of 2.52 μM and a population standard deviation of 1.65 μM.