Markers of oxidative stress in erythrocytes during aging in humans

Age-dependent changes in glutathione-s-transferase: correlation with total plasma antioxidant potential and red cell intracellular glutathione

The correlation between antioxidant capacity and oxidative damage during aging has been reported in several tissues in different species. Glutathione-S-transferases (GST) can metabolise endogenous and exogenous toxins and carcinogens by catalysing the conjugation of diverse electrophiles with reduced glutathione (GSH). We observe a significant (P < 0.001) increase in plasma GST activity as a function of human age (r = 0.5675). A significant (P < 0.001) positive correlation (r = 0.8979) is observed between GST activity and total plasma antioxidant potential measured as ferric reducing ability of the plasma (FRAP). GST activity and red cell intracellular GSH also show a significant positive correlation (r = 0.7014). We hypothesize that the increased activity of plasma GST is a manifestation of increased generation of ROS and a concomitant decrease in the level of plasma antioxidant capacity during aging.

Protective effect of resveratrol on markers of oxidative stress in human erythrocytes subjected to in vitro oxidative insult

Resveratrol is a natural polyphenolic compound found largely in the skin of red grapes. Growing evidence suggests that resveratrol may play an important role in the prevention of many human diseases. Many of the biological actions of this polyphenol have been attributed to its antioxidant properties. The present study was undertaken to evaluate the effect of resveratrol on intracellular reduced glutathione (GSH) and membrane sulphydryl groups in erythrocytes subjected to oxidative stress in vitro by incubating with t-BHP (10 microm). The study was aimed to test the efficacy of the antioxidant effect of resveratrol on human erythrocytes. Subjecting erythrocytes to oxidative stress (in vitro) by incubating them with t-BHP (10 microm) caused a significant decrease in the intracellular GSH level and membrane -SH content compared with basal values. Incubation of erythrocytes/membranes with resveratrol (1-100 microm final conc) resulted in significant protection against the t-BHP-induced oxidative stress as evidenced by the increase in GSH level and membrane -SH content. It was observed that the effect of resveratrol is dose/concentration and time-dependent. Since resveratrol is naturally present in many fruits and vegetables, a diet rich in resveratrol may provide protection against degenerative diseases.

Protective effect of resveratrol on formation of membrane protein carbonyls and lipid peroxidation in erythrocytes subjected to oxidative stress

Many of the biological actions of resveratrol have been attributed to its antioxidant properties. In this work, we subjected human erythrocytes to in vitro oxidative stress by incubating them with tert-butylhydroperoxide (t-BHP). This caused a significant increase in the malondialdehyde (MDA) level and the protein carbonyl group content above the basal values. The presence of trans-resveratrol at micromolar concentrations in the incubation medium protected the erythrocytes from t-BHP-induced oxidative stress, as evidenced by the decrease in the MDA level and the protein carbonyl group content. The effect of resveratrol was concentration and time-dependent. Our findings help to explain some of the beneficial effects of resveratrol.

Age and breeding effort as sources of individual variability in oxidative stress markers in a bird species

Oxidative stress is the imbalance between the production of pro-oxidant substances and the level of antioxidant defenses, which leads to oxidative damage. It has been proposed that senescence is the result of accumulated oxidative damage throughout life. In birds, the sources of individual variability in oxidative stress are still poorly understood. Among these sources, age, as related to senescence, should be particularly relevant. Furthermore, recent findings suggest that breeding effort may also deeply influence susceptibility to oxidative stress. However, there is still no evidence of a link between breeding effort and oxidative damage in any vertebrate. Here we analyzed 288 captive red-legged partridges (Alectoris rufa) across a wide age range (i.e., 1-8 yr old), thus including potentially senescent birds. In spite of limitations due to the cross-sectional approach, results revealed that old birds produced less offspring and endured higher levels of oxidized glutathione and peroxidized lipids in erythrocytes than did middle-aged individuals. Old birds also showed higher plasma total antioxidant status and uric acid levels than did younger birds, but lower amounts of circulating carotenoids. Furthermore, hatching success was negatively correlated to lipid peroxidation in females but not in males, supporting the hypothesis that breeding effort promotes oxidative damage.

Prevention of selenite-induced cataractogenesis in Wistar albino rats by aqueous extract of garlic

PURPOSE

The main aim of this study was to evaluate the inhibitory impacts of the aqueous extract of garlic (Ga) on the formation of cataract induced by sodium selenite (Se).

METHODS

Thirty-two Wistar albino rat pups (4 equal groups: G1, G2, G3, and G4) were treated as follows: G1, subcutaneous (s.c.) and intraperitoneal (i.p.) injection of normal saline (0.3 mL) on postpartum (day 10); G2, i.p. injection of aqueous extract of garlic (1 mL/kg body weight) and s.c. injection of normal saline (0.3 mL) on postpartum (day 10); G3, s.c. injection of sodium selenite (20 nmol/g body weight) and i.p. injection of normal saline (0.3 mL) on postpartum (day 10); and G4, s.c. injection of sodium selenite (20 nmol/g body weight) and i.p. injection of aqueous extract of garlic (1 mL/kg body weight) on postpartum (day 10). Daily i.p. injections of aqueous extract of garlic (in G2 and G4) and normal saline (in G1 and G3) were continued for 14 days. The development of cataract was assessed over a period of 2 weeks after injection of sodium selenite. For further examination, the rats' lenses were removed and analyzed for glutathione (GSH), malondialdehyde (MDA) levels, and superoxide dismutase (SOD), glutathione peroxidase (GPX) activities.

RESULTS

In G3 (Se-treated group), all rats developed grade 3 cataract in both eyes. However, in G1 (untreated control group), G2 (Ga-treated group), and G4 (Ga-Se-treated group), the lenses in both eyes of all rats remained clear (P < 0.0001). This clinical finding was associated with higher GSH level and GPX, SOD activities and lower level of MDA in the Se- and Ga-treated group (G4) compared with SS-treated group (G3) rat lenses (P < 0.003).

CONCLUSIONS

Intraperitoneal injection of the Ga in rat model appeared to effectively prevent Se-induced cataract, thus such herbal remedy may be considered for treatment of cataract.

Markers of oxidative stress in erythrocytes and plasma during aging in humans

Aging is an inevitable universal biological process, which can be characterized by a general decline in physiological function with the accumulation of diverse adverse changes and increased probability of death. Among several theories, oxidative stress/free radical theory offers the best mechanistic elucidation of the aging process and other age -related phenomenon. In the present paper , we discuss the aging process and have focused on the importance of some reliable markers of oxidative stress which may be used as biomarkers of the aging process.

[Changes in oxidative stress biomarkers induced by puberty]

AIM

Evaluate the influence of puberty in oxidative stress.

SUBJECTS AND METHODS

The study included 38 prepubescent males with Tanner G(1)-P(1) and 32 healthy pubescent boys with Tanner G(3-4)-P(3-4). Weight, height and body mass index, heart rate, blood pressure values were within the 50 percentile 50+/-1SD for their age. The biomarkers were measured in saliva, as a good correlation between saliva and plasma levels has been reported in lipoperoxidation products, reduced glutathione and catalase.

RESULTS

Pubescent boys had significantly higher levels of lipoperoxidation products (P<0.001) compared with the prepubertal group, with no significant differences in the other parameters measured. There was a significant positive correlation between lipoperoxides and reduced glutathione in these children.

CONCLUSION

It is the first time that an increase of lipoperoxidation products has been reported in pubertal boys and this biomarker could play a role in the development of oxidative stress in this stage of life.

Preliminary evidence for cell membrane amelioration in children with cystic fibrosis by 5-MTHF and vitamin B12 supplementation: a single arm trial

Background

Cystic fibrosis (CF) is one of the most common fatal autosomal recessive disorders in the Caucasian population caused by mutations of gene for the cystic fibrosis transmembrane conductance regulator (CFTR). New experimental therapeutic strategies for CF propose a diet supplementation to affect the plasma membrane fluidity and to modulate amplified inflammatory response. The objective of this study was to evaluate the efficacy of 5-methyltetrahydrofolate (5-MTHF) and vitamin B12 supplementation for ameliorating cell plasma membrane features in pediatric patients with cystic fibrosis.

Methodology and Principal Findings

A single arm trial was conducted from April 2004 to March 2006 in an Italian CF care centre. 31 children with CF aged from 3 to 8 years old were enrolled. Exclusion criteria were diabetes, chronic infections of the airways and regular antibiotics intake. Children with CF were supplemented for 24 weeks with 5-methyltetrahydrofolate (5-MTHF, 7.5 mg /day) and vitamin B12 (0.5 mg/day). Red blood cells (RBCs) were used to investigate plasma membrane, since RBCs share lipid, protein composition and organization with other cell types. We evaluated RBCs membrane lipid composition, membrane protein oxidative damage, cation content, cation transport pathways, plasma and RBCs folate levels and plasma homocysteine levels at baseline and after 24 weeks of 5-MTHF and vitamin B12 supplementation. In CF children, 5-MTHF and vitamin B12 supplementation (i) increased plasma and RBC folate levels; (ii) decreased plasma homocysteine levels; (iii) modified RBC membrane phospholipid fatty acid composition; (iv) increased RBC K⁺ content; (v) reduced RBC membrane oxidative damage and HSP70 membrane association.

Conclusion and Significance

5-MTHF and vitamin B12 supplementation might ameliorate RBC membrane features of children with CF.

Trial Registration

ClinicalTrials.gov NCT00730509

Variability of body weight, pulse pressure and glycaemia strongly predict total mortality in elderly type 2 diabetic patients. The Verona Diabetes Study

BACKGROUND

Ageing is characterized by a decreased functional reserve, a concept defined as homeostenosis. We assessed the impact of long-term exposure to the average value (mean) or to the variability (coefficient of variation) of fasting glycaemia, body mass index (BMI) and pulse pressure on total mortality in a cohort of type 2 diabetic patients.

METHODS

Fasting glycaemia, BMI and pulse pressure values were collected over a period of 3 years in 1 319 type 2 diabetic patients who were subsequently followed up for 10 years. For each patient, the means and the coefficients of variation of fasting glycaemia, BMI and pulse pressure were computed. The adverse impact of these risk factors on total mortality was assessed in patients aged < 65 years (n = 565) and in those aged > or = 65 years (n = 754), separately.

RESULTS

During the 10 years of follow-up, 438 patients died. In younger diabetic patients, the means of fasting glycaemia [hazard ratio (HR) of III tertile versus I tertile = 2.11, 95% confidence interval (CI): 1.22-3.64], BMI (HR = 1.88, 1.12-3.14) and pulse pressure (HR = 2.36, 1.34-4.16) were independently associated with total mortality, while in older patients they were not. In contrast, the coefficients of variation of glycaemia (HR = 1.56, 1.17-2.08), BMI (HR = 1.34, 1.03-1.75) and pulse pressure (HR = 1.34, 1.03-1.74) independently predicted total mortality only in older patients.

CONCLUSIONS

Our findings suggest that the variability of fasting glycaemia, body weight and blood pressure (BP) is independently associated with an increased risk of all-cause mortality in older type 2 diabetic patients. Future studies are required to confirm the reproducibility of our findings.

Protective Role of Myricetin on Markers of Oxidative Stress in Human Erythrocytes Subjected to Oxidative Stress

The protective effect of myricetin against tert-butylhydroperoxide (t-BHP) induced oxidative stress in human erythrocytes was investigated. Incubating erythrocytes with t-BHP (10−5M) caused development of oxidative stress, as evidenced by significant ( p < 0.05) increase in erythrocyte malondialdedyde (MDA) and protein carbonyl content, and decrease in intracellular reduced glutathione (GSH), membrane sulphydryl (-SH) groups. Incubation of erythrocytes with myricetin, simultaneously with t-BHP, protected the erythrocytes from oxidative stress, an effect which was dose-dependent. The results demonstrate that myricetin attenuates t-BHP induced oxidative damage, suggesting that supplementation of diet with myricetin/myricetin rich food may be beneficial in all pathological conditions where the antioxidant system of the body is overwhelmed.

L-cysteine influx in erythrocytes as a function of human age

In erythrocytes, although three amino acids are required for the synthesis of reduced glutathione (GSH), the rate of GSH synthesis is determined only by the availability of L-cysteine. Cysteine supplementation has been shown to ameliorate several parameters that are known to degenerate during human aging; this has led to an interesting hypothesis that aging could be a cysteine deficiency syndrome. In the present study, we measured L-cysteine influx in human erythrocytes by suspending cells in solution containing 10 mM L-cysteine. We show a significant decline in the influx of L-cysteine in erythrocytes during aging in humans. The decrease in cysteine influx correlates with the decrease in antioxidant potential of plasma measured in terms of FRAP (ferric-reducing ability of plasma) during aging. We conclude that a decreased influx of L-cysteine may be an important factor contributing to the development of oxidative stress in human erythrocytes during aging.