Comparative study of sodium, potassium, ionized calcium, urea and creatinine circadian rhythm documented in samples of capillary and venous blood from healthy subjects

Circadian rhythms of sodium, potassium, ionized calcium, creatinine and urea concentrations were determined in venous and capillary blood of practically healthy volunteers (10 women and 8 men). Electrolytes were determined on the ionoselective analyzer Microlyte (KONE, Finland). Circadian rhythmicity of parameters was revealed in venous and capillary blood by means of group-mean cosinor analysis. Acrophases of the rhythms occurred in the late evening (Na) or in the first (K, venous ionized Ca) and in the second half (creatinine, urea) of sleep. Circadian rhythms of electrolytes (except ionized Ca rhythm) and final products of nitrous metabolism in capillary blood turned out to be the markers of the corresponding indices rhythms of venous blood.     

Lactate concentration differences in plasma, whole blood, capillary finger blood and erythrocytes during submaximal graded exercise in humans

The aim of the study was to investigate the distribution of lactate in plasma, whole blood, erythrocytes, and capillary finger blood, before and during submaximal exercise. Ten healthy male subjects performed submaximal graded cycle ergometer exercise for 20-25 min. Venous blood samples and capillary finger blood samples were taken before exercise and every 5th min during exercise for lactate determination. The plasma lactate concentration was significantly higher (P less than 0.001, approximately 50%) than in the erythrocytes. This difference was not altered by the venous blood lactate concentration or exercise intensity. A significant difference (P less than 0.01) in lactate concentration was also found between capillary whole blood and venous whole blood. It was concluded that direct comparisons between lactate in capillary finger blood, venous whole blood and plasma could not be made.     

Changes in the concentrations of Na+, K+ and Cl? in secretion from the skin during progressive increase in exercise intensity

A simple method for sampling skin secretion in 1-min periods was developed for investigating the effects of progressive increases in exercise intensity on Na+, K+ and Cl- secretions from the skin of the forearm. Ten healthy male subjects performed exercise consisting of eight stepwise increases in intensity from 50 to 225 W, with a 25-W increase at each step. Exercise at each step was for 3 min followed by a 1-min recovery period. Samples of blood and skin secretion were taken during the recovery period. Significant positive correlations were found between the mean concentrations of Na+ and Cl- and between those of K+ and Cl- in the skin secretion. The concentrations of electrolytes in the skin secretion also showed significant correlations with the blood lactate concentrations. The inflection points for secretions of Na+, K+ and Cl- were 4.04, 3.61 and 3.83 mmol.l-1 of blood lactate; 64.42, 61.96 and 62.14% of maximal oxygen consumption (VO2max); and exercise intensities of 123.01, 117.65 and 125.07 W, respectively. No significant differences were observed between the value of 67.27% of VO2max or 134.00W at the onset of blood lactate accumulation (OBLA) and the inflection points. From these results we concluded that changes in electrolyte concentrations in skin secretion during incremental exercise according to this protocol were closely related with the change in the blood lactate concentration, and that the inflection points for electrolytes may have been near the exercise intensity at OBLA.     

Electron spin resonance spectroscopic detection of oxygen-centred radicals in human serum following exhaustive exercise

Free radicals or oxidants are continuously produced in the body as a consequence of normal energy metabolism. The concentration of free radicals, together with lipid peroxidation, increases in some tissues as a physiological response to exercise – they have also been implicated in a variety of pathologies. The biochemical measurement of free radicals has relied in the main on the indirect assay of oxidative stress by-products. This study presents the first use of electron spin resonance (ESR) spectroscopy in conjunction with the spin-trapping technique, to measure directly the production of radical species in the venous blood of healthy human volunteers pre- and post-exhaustive aerobic exercise. Evidence is also presented of increased lipid peroxidation and total antioxidant capacity post-exercise. Accepted: 30 October 1997     

Oxidative DNA damage and plasma antioxidant capacity in type 2 diabetic patients with good and poor glycaemic control

Diabetes mellitus is a complex metabolic disorder characterized by a disturbance in glucose metabolism. Recent evidence suggests that increased oxidative damage as well as reduction in antioxidant capacity could be related to the complications in patients with type 2 diabetes. The aim of this study was to measure plasma antioxidant status in type 2 diabetic patients with good and poor glycaemic control and its relationship with oxidative DNA damage. Thirty-nine type 2 diabetic patients and eighteen healthy subjects were recruited for this study. We found that diabetic patients had slightly, but not significantly lower antioxidant capacity, measured with the "ferric reducing ability of plasma" (FRAP) assay, than healthy subjects. On the contrary, oxidative DNA damage (measured by the Comet assay) in leukocytes obtained from diabetic patients was significantly higher compared to healthy subjects. Taking into account glucose control, we found that the FRAP level was significantly (p<0.05) lower in diabetic subjects with poor glycaemic control than healthy subjects, while patients with good glycaemic control had FRAP values similar to controls. We also observed an unexpected positive correlation between FRAP values and oxidative DNA damage in diabetic patients; moreover, a positive correlation was found between FRAP and glucose level or HbA(1c) in patients with poor glycaemic control. In conclusion, our results confirm that patients with type 2 diabetes have a higher oxidative DNA damage than healthy subjects and that plasma antioxidant capacity is significantly lower only in patients with poor glycaemic control, moreover, in these patients FRAP values are positively correlated with glycaemic levels and HbA(1c). These observations indicate that a compensatory increase of the antioxidant status is induced as a response to free radical overproduction in type 2 diabetes. Therefore, the addition of antioxidant supplements to the current pharmacological treatment could have potentially beneficial effects in diabetic patients with poor glycaemic control.     

Interplay between the pro-oxidant and antioxidant systems and proinflammatory cytokine levels,in relation to iron metabolism and the erythron in depression

As there is strong evidence for inflammation and oxidative stress in depression, the aim of this study was to elucidate the relationship between oxidative imbalance and cellular immune response and to ask whether these processes are linked with iron metabolism in depressed patients. Blood was collected from patients diagnosed with recurrent depressive disorder (n=15) and from healthy controls (n=19). Whole-blood reduced glutathione (GSH), erythrocyte superoxide dismutase (SOD-1), glutathione peroxidase (GPx-1), glutathione reductase, malondialdehyde (MDA), and methemoglobin (MetHb) and plasma H₂O₂ were assayed spectrophotometrically. The serum heme oxygenase 1 (HO-1), cytokine, neopterin, and iron statuses were measured by ELISA. DNA damage was analyzed by comet assay. Serum concentrations of ferritin and soluble transferrin receptor were assayed by ELISA. MetHb saturation was analyzed spectrophotometrically in red blood cell hemolysate. The erythron variables were measured using a hematological analyzer. We observed a significant decrease in GPx-1 and SOD-1 activities and decreased levels of HO-1 and GSH in depressed patients compared to controls. Conversely, compared with controls, we found increased concentrations of MDA and H₂O₂ and more DNA damage in depressed patients. Furthermore, the levels of the proinflammatory cytokine interleukin-6 and of neopterin were increased in depressed patients along with decreased hemoglobin and hematocrit. A strong association between antioxidant defense, cytokine levels, and iron homeostasis was also revealed. These findings show that depression is associated with increased oxidative stress, inflammation, and restrictions on the available iron supply for red blood cell production. Furthermore, decreased antioxidant defense correlates with an increased cellular inflammatory response, whereas both concur with erythron and iron status, the latter explained by significant canonical correlations with the set of free radical scavenging enzymes and proinflammatory enzymes. The strong links between immune function, oxidative stress, and iron homeostasis suggest the presence of a self-sustaining multipathway mechanism that may progressively worsen, i.e., throughout accumulation of oxidative damage, producing the functional and structural consequences associated with depression. Hence, identifying viable therapeutic strategies to tackle oxidative stress and accompanying physiological disturbances, including inflammation and anemia, of chronic disease provides more opportunities for the treatment and, ultimately, prevention of depression.     

Energy budget,oxidative stress and antioxidant in striped hamster acclimated to moderate cold and warm temperatures

The mechanism of the rate of living-free radical theory suggests that higher rate of oxidative metabolism results from greater rate of mitochondria oxidative phosphorylation, leading to a consequent increase in production of free radicals. However, the relation between metabolic rate and oxidative stress is tissue dependent in animals acclimated to cold temperatures. Here we examined oxidative stress, reflected by changes of antioxidant activity and other related markers, in striped hamsters acclimated to moderate cold (15 °C), room (23 °C) or warm temperature (30 °C) for 6 weeks, by which either higher or lower metabolic rate was induced experimentally. Energy intake and the rate of metabolism and nonshivering thermogenesis were increased at 15 °C, but decreased at 30 °C compared with that at 23 °C. Effects of temperatures on the markers of both oxidative stress and antioxidant activities were rarely significant. The percentages of positive correlation between the 11 tissues (brain, BAT, liver, heart, lung, kidneys, stomach, small and large intestine, caecum and skeletal muscle) were 14.5% (8/55) for catalase (CAT), 7.3% (4/55) for the capacity of inhibition of hydroxyl free radical (CIH), 5.5% (3/55) for activities of superoxide dismutase (SOD), 1.8% (1/55) for total antioxidant capacity (T-AOC), 4.3% (2/46) for H₂O₂ and 11.1% (4/36) for the capacity of inhibition of hydroxyl free radical (CIH). This indicated that the tissue-dependent changes of both oxidative stress and antioxidant activity were less consistent among the different tissues. Finally the data from this study were less consistent with the prediction of the mechanism of the rate of living-free radical theory.     

Disruption of mitochondrial redox circuitry in oxidative stress

The present review and commentary considers oxidative stress as a disruption of mitochondrial redox circuitry rather than an imbalance of oxidants and antioxidants. Mitochondria contain two types of redox circuits, high-flux pathways that are central to mechanisms for ATP production and low-flux pathways that utilize sulfur switches of proteins for metabolic regulation and cell signaling. The superoxide anion radical (hereafter termed "superoxide", O2*-), a well known free radical product of the high-flux mitochondrial electron transfer chain, provides a link between the high-flux and low-flux pathways. Disruption of electron flow and increased superoxide production occurs due to inhibition of electron transfer in the high-flux pathway, and this creates aberrant "short-circuit" pathways between otherwise non-interacting components. A hypothesis is presented that superoxide is not merely a byproduct of electron transfer but rather is generated by the mitochondrial respiratory apparatus to serve as a positive signal to coordinate energy metabolism. Electron mediators such as free Fe(3+) and redox-cycling agents, or potentially free radical scavenging agents, could therefore cause oxidative stress by disrupting this normal superoxide signal. Methods to map the regulatory redox circuitry involving sulfur switches (e.g., redox-western blotting of thioredoxin-2, redox proteomics) are briefly presented. Use of these approaches to identify sites of disruption in the mitochondrial redox circuitry can be expected to generate new strategies to prevent toxicity and, in particular, promote efforts to re-establish proper electron flow as a means to counteract pathologic effects of oxidative stress.     

Antioxidant activity and biologic properties of a procyanidin-rich extract from pine (Pinus maritima) bark, pycnogenol.

There is growing interest in the biologic activities of plant extracts such as that obtained from the bark of the French maritime pine Pinus maritima, Pycnogenol. Pycnogenol (PYC) is a standardized extract composed of a mixture of flavonoids, mainly procyandins and phenolic acids. Studies indicate that PYC components are highly bioavailable. Uniquely PYC displays greater biologic effects as a mixture than its purified components do individually indicating that the components interact synergistically. PYC has been reported to have cardiovascular benefits, such as a vasorelaxant activity, angiotensin-converting enzyme (ACE) inhibiting activity, and the ability to enhance the microcirculation by increasing capillary permeability. Investigations of the cellular mechanisms of these therapeutic effects have demonstrated that PYC has strong free radical-scavenging activity against reactive oxygen and nitrogen species. The oligomeric components of PYC contribute significantly to the ESR free radical signal. PYC also participates in the cellular antioxidant network as indicated by its ability to regenerate the ascorbyl radical and to protect endogenous vitamin E and glutathione from oxidative stress. PYC modulates NO metabolism in activated macrophages by quenching the NO radical and inhibiting both iNOS mRNA expression and iNOS activity. The spectrum of different effects of NO in the circulation and the nervous system suggest the potential applications of PYC in immune and circulatory disorders as well as in neurodegenerative disease. PYC can bind to proteins, altering their structure and thereby modulating the activity of key enzymes and proteins involved in metabolic pathways. PYC effects redox-sensitive signal transduction pathways and alters gene expression. Aspects of PYC's activity are presented and discussed together with possible future implications and directions in the field of flavonoid research.     

Ammonia Neurotoxicity and the Mitochondrial Permeability Transition

Ammonia is a neurotoxin that predominantly affects astrocytes. Disturbed mitochondrial function and oxidative stress, factors implicated in the induction of the mitochondrial permeability transition (MPT), appear to be involved in the mechanism of ammonia neurotoxicity. We have recently shown that ammonia induces the MPT in cultured astrocytes. To elucidate the mechanisms of the MPT, we examined the role of oxidative stress and glutamine, a byproduct of ammonia metabolism. The ammonia-induced MPT was blocked by antioxidants, suggesting a causal role of oxidative stress. Direct application of glutamine (4.5-7.0 mM) to cultured astrocytes increased free radical production and induced the MPT. Treatment of astrocytes with the mitochondrial glutaminase inhibitor, 6-diazo-5-oxo-L-norleucine, completely blocked free radical formation and the MPT, suggesting that high ammonia concentrations in mitochondria resulting from glutamine hydrolysis may be responsible for the effects of glutamine. These studies suggest that oxidative stress and glutamine play major roles in the induction of the MPT associated with ammonia neurotoxicity.     

Effect of chronic exposure to aspartame on oxidative stress in brain discrete regions of albino rats

This study was aimed at investigating the chronic effect of the artificial sweetener aspartame on oxidative stress in brain regions of Wistar strain albino rats. Many controversial reports are available on the use of aspartame as it releases methanol as one of its metabolite during metabolism. The present study proposed to investigate whether chronic aspartame (75 mg/kg) administration could release methanol and induce oxidative stress in the rat brain. To mimic the human methanol metabolism, methotrexate (MTX)-treated rats were included to study the aspartame effects. Wistar strain male albino rats were administered with aspartame orally and studied along with controls and MTX-treated controls. The blood methanol level was estimated, the animal was sacrificed and the free radical changes were observed in brain discrete regions by assessing the scavenging enzymes, reduced glutathione, lipid peroxidation (LPO) and protein thiol levels. It was observed that there was a significant increase in LPO levels, superoxide dismutase (SOD) activity, GPx levels and CAT activity with a significant decrease in GSH and protein thiol. Moreover, the increases in some of these enzymes were region specific. Chronic exposure of aspartame resulted in detectable methanol in blood. Methanol per se and its metabolites may be responsible for the generation of oxidative stress in brain regions.     

自由基稳衡性动态

虽然自由基具有很活泼的化学性质 ,但在需氧生物的进化中却一直保持着自由基稳衡性动态的特征 ,体现于某些生物程序 ,包括 :在生理情况下履行其生理作用 ;维持其产生与清除于接近平衡 ;余剩的自由基引发生物大分子的损伤及其损伤可被修复。营养素及其代谢物和“必需”抗氧化剂对自由基稳衡态的正常维持起着关键性作用。谷胱甘肽及其它生物物质的稳衡性动态与自由基稳衡性动态有着协调的相互关系。在各种生活条件下 ,不同年龄的健康人体内自由基稳衡性动态应维持良好 ,以预防衰老前氧化应激与氧化损伤的发生     

Ubiquinol-10 and ubiquinone-10 levels in umbilical cord blood of healthy foetuses and the venous blood of their mothers

Abstract

Despite their being good markers of oxidative stress for clinical use, little is known about ubiquinol-10 (reduced coenzyme Q₁₀) and ubiquinone-10 (oxidized coenzyme Q₁₀) levels in foetuses and their mothers. This study investigates oxidative stress in 10 healthy maternal venous, umbilical arterial and venous bloods after vaginal delivery by measuring ubiquinol-10 and ubiquinone-10 levels. Serum ubiquinol-10 and ubiquinone-10 levels were measured by HPLC with a highly sensitive electrochemical detector. Maternal venous ubiquinol-10 and ubiquinone-10 levels were significantly higher than umbilical arterial and venous levels (all p < 0.001). However, the ubiquinone-10/total coenzyme Q₁₀ (CoQ₁₀) ratio, which reflects the redox status, was significantly higher in umbilical arterial and umbilical venous blood compared to maternal venous blood (all p < 0.001). The ubiquinone-10/total CoQ₁₀ ratio was higher in umbilical arterial than in umbilical venous blood (p < 0.01). The present study demonstrated that foetuses were under higher oxidative stress than their mothers.     

Resistance to oxidative stress shows low heritability and high common environmental variance in a wild bird

Oxidative stress was recently demonstrated to affect several fitness‐related traits and is now well recognized to shape animal life‐history evolution. However, very little is known about how much resistance to oxidative stress is determined by genetic and environmental effects and hence about its potential for evolution, especially in wild populations. In addition, our knowledge of phenotypic sexual dimorphism and cross‐sex genetic correlations in resistance to oxidative stress remains extremely limited despite important evolutionary implications. In free‐living great tits (Parus major), we quantified heritability, common environmental effect, sexual dimorphism and cross‐sex genetic correlation in offspring resistance to oxidative stress by performing a split‐nest cross‐fostering experiment where 155 broods were split, and all siblings (n = 791) translocated and raised in two other nests. Resistance to oxidative stress was measured as both oxidative damage to lipids and erythrocyte resistance to a controlled free‐radical attack. Both measurements of oxidative stress showed low additive genetic variances, high common environmental effects and phenotypic sexual dimorphism with males showing a higher resistance to oxidative stress. Cross‐sex genetic correlations were not different from unity, and we found no substantial heritability in resistance to oxidative stress at adult age measured on 39 individuals that recruited the subsequent year. Our study shows that individual ability to resist to oxidative stress is primarily influenced by the common environment and has a low heritability with a consequent low potential for evolution, at least at an early stage of life.     

Free radicals in exhaled breath condensate in cystic fibrosis and healthy subjects

Many markers of airway inflammation and oxidative stress can be measured non-invasively in exhaled breath condensate (EBC). However, no attempt has been made to directly detect free radicals using electron paramagnetic resonance (EPR) spectroscopy. Condensate was collected in 14 children with cystic fibrosis (CF) and seven healthy subjects. Free radicals were trapped by 5,5-dimethyl-1-pyrroline-N-oxide. EPR spectra were recorded using a Bruker EMX^® spectrometer. Secondly, to study the source of oxygen centered radical formation, catalase or hydrogen peroxide was added to the condensate. Radicals were detected in 18 out of 21 condensate samples. Analysis of spectra indicated that both oxygen and carbon centered radicals were trapped. Within-subject reproducibility was good in all but one subject. Quantitatively, there was a trend towards higher maximal peak heights of both oxygen and carbon centered radicals in the children with CF. Catalase completely suppressed the signals in condensate. Addition of hydrogen peroxide resulted in increased radical signal intensity. Detection of free radicals in EBC of children with CF and healthy subjects is feasible using EPR spectroscopy.     

Free radicals in exhaled breath condensate in cystic fibrosis and healthy subjects

Many markers of airway inflammation and oxidative stress can be measured non-invasively in exhaled breath condensate (EBC). However, no attempt has been made to directly detect free radicals using electron paramagnetic resonance (EPR) spectroscopy. Condensate was collected in 14 children with cystic fibrosis (CF) and seven healthy subjects. Free radicals were trapped by 5,5-dimethyl-1-pyrroline-N-oxide. EPR spectra were recorded using a Bruker EMX^® spectrometer. Secondly, to study the source of oxygen centered radical formation, catalase or hydrogen peroxide was added to the condensate. Radicals were detected in 18 out of 21 condensate samples. Analysis of spectra indicated that both oxygen and carbon centered radicals were trapped. Within-subject reproducibility was good in all but one subject. Quantitatively, there was a trend towards higher maximal peak heights of both oxygen and carbon centered radicals in the children with CF. Catalase completely suppressed the signals in condensate. Addition of hydrogen peroxide resulted in increased radical signal intensity. Detection of free radicals in EBC of children with CF and healthy subjects is feasible using EPR spectroscopy.     

The effect of a sauna on blood oxygen transport and the prooxidant-antioxidant balance in untrained subjects

The effect of sauna on blood oxygen transport and the prooxidant-antioxidant state was studied in 18- to 22-year-old men. The course of heat treatment was performed once a week for five months, i.e., twenty procedures in total. A sauna procedure consisted of two exposures for 5 and 10 min at a temperature of 85?C90°C and humidity of 10?C15%. In young men, dry-air bath exposure resulted in respiratory alkalosis, increased pO₂, and a decreased affinity of hemoglobin to oxygen in the venous blood, which increased the transportation of O2 to tissues. A single sauna procedure was associated with the development of oxidative stress, which was expressed as an enhancement of free radical processes and a decrease in antioxidant defense. Oxidative stress intensity decreased after the course of heat treatment. An elevation of nitric oxide formation could modify oxygen-dependent processes in the body.     

Iron-Induced Oxidative Stress in Erythrocyte Membranes of Non-Insulin-Dependent Diabetic Nigerians

The presence of higher level of endogenous free radical reaction products in the erythrocyte ghost membrane (EGM) of Non-insulin-dependent diabetes mellitus (NIDDM) subjects compared with that of normal healthy controls has been demonstrated. The EGMs of NIDDM subjects were also shown to be more susceptible to exogenously generated oxidative stress than those of normal healthy individuals. The decreased level of reactive thiol groups in the EGM of NIDDM individuals supported this observation. We propose that the presence of significant levels of non-heme iron in the EGM of NIDDM subjects is an indication of the potential for iron-catalysed production of hydroxy and other toxic radicals which could cause continuous oxidative stress and tissue damage. Oxygen free radicals could therefore be responsible for most of the erythrocyte abnormalities associated with non-insulin-dependent diabetes and could indeed be intimately involved in the mechanism of tissue damage in diabetic complications.     

Exercise,free radicals,and lipid peroxidation in type 1 diabetes mellitus

Indirect biochemical techniques have solely been used to ascertain whether type 1 diabetes mellitus patients are more susceptible to resting and exercise-induced oxidative stress. To date there is no direct evidence to support the contention that type 1 diabetic patients have increased levels of free radical species. Thus, the aim of this study was to use electron spin resonance (ESR) spectroscopy in conjunction with alpha-phenyl-tert-butylnitrone (PBN) spin trapping to measure pre- and postexercise free radical concentration in the venous blood of young male patients with type 1 diabetes mellitus (HbA(1c) = 8.2 +/- 1%, n = 12) and healthy matched controls (HbA(1c) = 5.5 +/- 0.2%, n = 13). Supporting measures of lipid peroxidation (malondialdehyde and lipid hydroperoxides), ambient blood glucose and selected antioxidants were also measured. The diabetic patients presented with a comparatively greater concentration of free radicals as measured by ESR and lipid hydroperoxides (LH) compared to the healthy group (p <.05, pooled rest and exercise data), although there was no difference in malondialdehyde (MDA) concentration. alpha-Tocopherol was comparatively lower in the healthy group (p <.05, pooled rest and exercise data vs. diabetic group) due to a selective decrease during physical exercise (p <.05 vs. rest). The hyperfine coupling constants recorded from the ESR spectra (a(Nitrogen) = 1.37 mT and abeta(Hydrogen) = 0.17 mT) are suggestive of either oxygen or carbon-centered species and are consistent with literature values. We suggest that the greater concentration of oxidants seen in the diabetic group may be due to increased glucose autoxidation as a function of this pathology and/or a lower exercise-induced oxidation rate of the major lipid soluble antioxidant alpha-tocopherol. We suggest that the ESR-detected radicals are secondary species derived from decomposition of LH because these are the major initial reaction products of free radical attack on cell membranes.