A very fast ion-pair reversed-phase HPLC method for the separation of the most significant nucleotides and their degradation products in human red blood cells

A simple and fast ion pair reversed-phase high-performance liquid chromatographic method has been developed for the simultaneous determination of ATP, ADP, AMP, GTP, GDP, IMP, NADP+, NADPH+, NAD+, NADH, ADP-ribose, inosine, adenosine, hypoxanthine, and xanthine. This method allows us to have a complete picture of the most important nucleotides present in fresh human erythrocytes. Furthermore it is particularly useful in the study of the erythrocyte adenine nucleotide catabolism allowing the detection of degradation products such as IMP, inosine, adenosine, hypoxanthine, and xanthine. The separation of the compounds under investigation is achieved in less than 15 min using a reversed-phase 3-micron Supelcosil LC-18 column and adding tetrabutylammonium, as ion-pair agent, to the buffers. The short time of analysis, the high reproducibility of the system, and the accurate evaluation of the compounds of interest make this method particularly suitable for routine analysis. Finally it is possible to use this assay as an alternative method of measuring activities of enzymes which catalyze reactions involving some of these compounds, as in the case of Na+-K+ ATPase, AMP deaminase, and adenosine deaminase.

Antioxidant properties of a novel phycocyanin extract from the blue-green alga Aphanizomenon flos-aquae

Aphanizomenon flos-aquae (AFA) is a fresh water unicellular blue-green alga (cyanophyta) rich in phycocyanin (PC), a photosynthetic pigment with antioxidant and anti-inflammatory properties. The purpose of this study was to evaluate the ability of a novel natural extract from AFA enriched with PC to protect normal human erythrocytes and plasma samples against oxidative damage in vitro. In red blood cells, oxidative hemolysis and lipid peroxidation induced by the aqueous peroxyl radical generator [2,2'-Azobis (2-amidinopropane) dihydrochloride, AAPH] were significantly lowered by the AFA extract in a time- and dose-dependent manner; at the same time, the depletion of cytosolic glutathione was delayed. In plasma samples, the natural extract inhibited the extent of lipid oxidation induced by the pro-oxidant agent cupric chloride (CuCl2); a concomitant increase of plasma resistance to oxidation was observed as evaluated by conjugated diene formation. The involvement of PC in the antioxidant protection of the AFA extract against the oxidative damage was demonstrated by investigating the spectral changes of PC induced by AAPH or CuCl2. The incubation of the extract with the oxidizing agents led to a significant decrease in the absorption of PC at 620 nm accompanied with disappearance of its blue color, thus indicating a rapid oxidation of the protein. In the light of these in vitro results, the potential clinical applications of this natural compound are under investigation.

Differences in blood and semen oxidative status in fertile and infertile men, and their relationship with sperm quality

Oxidative stress plays a fundamental role in the aetiology of male infertility by negatively affecting sperm quality and function. Assessment of blood and seminal plasma oxidative profiles might be a valuable tool to improve evaluation of sperm reproductive capacity and functional competence. This study examined the lipid-soluble antioxidant profile and levels of lipid peroxidation both in blood and seminal plasma samples of infertile and fertile males, in relation to semen parameters. Total antioxidant capacity (TAC) and vitamin E concentrations were significantly (P<0.05) lower in seminal plasma of infertile men compared with fertile subjects; concurrently, a significant accumulation of malondialdehyde was found in infertile patients (P=0.032 compared with controls), which was negatively correlated with sperm motility and morphology. In blood samples, infertile men presented lower concentrations of TAC, carotenoids and vitamin E than fertile subjects; TAC and carotenoids were positively correlated with sperm motility, morphology and concentration. Finally, blood TAC and vitamin E concentrations were positively correlated with the corresponding seminal values, confirming the close relationship between blood and semen antioxidants. All these results indicated the possibility of using not only seminal antioxidants but also blood antioxidants as biochemical markers to support sperm quality evaluation. Oxidative stress induced by reactive oxygen species (ROS) has been widely recognized as one of the major causes of male infertility; indeed, excessive ROS production can negatively impact sperm quality and function. The assessment of blood and seminal plasma oxidative profiles has been suggested as a valuable tool to improve the evaluation of sperm reproductive capacity and functional competence in infertile men. With this in mind, in the present study we examined the lipid soluble antioxidant profile (carotenoids and vitamins A and E) and the levels of lipid peroxidation (malondialdehyde; MDA) both in blood and seminal plasma samples of infertile and fertile males, in correlation with semen parameters namely motility, morphology and concentration. As a result, we obtained evidence that the total antioxidant capacity (TAC) and the concentrations of vitamin E of seminal plasma samples were significantly lower in infertile men than in fertile subjects; at the same time, a significant accumulation of MDA was found in infertile patients. MDA, in turn, negatively correlated with sperm motility and morphology, thus confirming that oxidative damage to lipids impairs sperm quality. In blood samples, infertile men presented lower TAC and lower concentrations of carotenoids and vitamin E than fertile subjects; interestingly, TAC and carotenoid concentrations were positively correlated with sperm motility, morphology, and concentration, confirming the close relationship between blood antioxidants and sperm quality. In conclusion, all these results suggested that the examination of blood and semen oxidative profiles might furnish useful information on sperm quality and function in infertile men.

Oxidative stress and antioxidant status in patients undergoing prolonged exposure to hyperbaric oxygen

OBJECTIVES

To evaluate the condition of oxidative stress in patients undergoing prolonged exposure to hyperbaric oxygen (HBO) and the possible modifications of the antioxidant defense systems in the absence of antioxidant supplementation.

DESIGN AND METHODS

Twelve patients exposed to 15 HBO treatments for pathological conditions related to hypoxia were included in the study. Oxidative stress indices as well as plasma and erythrocyte antioxidant levels were measured in blood samples collected both at the 1st and 15th HBO session.

RESULTS

The repeated exposures to HBO led to a significant accumulation of plasmatic reactive oxygen metabolites (ROM) and malondialdehyde (MDA). After 15 HBO sessions, no relevant differences were detected for reduced glutathione (GSH), alpha-tocopherol, and retinol plasma levels; however, a significant decrease in erythrocyte superoxide dismutase (SOD) and catalase (CAT) activity was observed when compared to the 1st HBO exposure; glutathione peroxidase (GPx) activity remained almost unchanged.

CONCLUSIONS

In the absence of antioxidant supplementation, the prolonged HBO treatment leads to a condition of oxidative stress that seems to affect in particular the response of the enzymatic antioxidant defense system; the possible relationship between the chemical modifications of the enzymes caused by oxygen reactive species and the consequent inactivation of the proteins is under investigation.

Potential role of levocarnitine supplementation for the treatment of chemotherapy-induced fatigue in non-anaemic cancer patients

Ifosfamide and cisplatin cause urinary loss of carnitine, which is a fundamental molecule for energy production in mammalian cells. We investigated whether restoration of the carnitine pool might improve chemotherapy-induced fatigue in non-anaemic cancer patients. Consecutive patients with low plasma carnitine levels who experienced fatigue during chemotherapy were considered eligible for study entry. Patients were excluded if they had anaemia or other conditions thought to be causing asthenia. Fatigue was assessed by the Functional Assessment of Cancer Therapy-Fatigue quality of life questionnaire. Treatment consisted of oral levocarnitine 4 g daily, for 7 days. Fifty patients were enrolled; chemotherapy was cisplatin-based in 44 patients and ifosfamide-based in six patients. In the whole group, baseline mean Functional Assessment of Cancer Therapy-Fatigue score was 19.7 (+/-6.4; standard deviation) and the mean plasma carnitine value was 20.9 microM (+/-6.8; standard deviation). After 1 week, fatigue ameliorated in 45 patients and the mean Functional Assessment of Cancer Therapy-Fatigue score was 34.9 (+/-5.4; standard deviation) (P<.001). All patients achieved normal plasma carnitine levels. Patients maintained the improved Functional Assessment of Cancer Therapy-Fatigue score until the next cycle of chemotherapy. In selected patients, levocarnitine supplementation may be effective in alleviating chemotherapy-induced fatigue. This compound deserves further investigations in a randomised, placebo-controlled study.

Bioreactivity and biocompatibility of a vitamin E-modified multi-layer hemodialysis filter

BACKGROUND

The present study was designed to test the biocompatibility of a new vitamin E-modified multi-layer membrane (CL-E filter), as well as its ability to protect against oxygen free radicals during hemodialysis (HD).

METHODS

We investigated, both in vitro and in vivo, the bioreactivity of the filter with respect to the blood antioxidants and its ability to prevent lipoperoxidation. The effects on the leukocyte respiratory burst were also studied. Cuprammonium rayon was used as a comparison material (CL-S filter).

RESULTS

The in vitro results demonstrated that, under controlled conditions, CL-E is able to preserve blood antioxidants, and particularly vitamin E, from the spontaneous consumption observed in the incubation with CL-S filters and in control incubations. In accordance with this observation, the rate of the oxidative demolition of lipids either in plasma and red blood cells (RBC) or from rat brain homogenate decreased after the exposure to CL-E filters in comparison with the CL-S filter. Moreover, in the absence of any significant cytotoxic effects due to both the types of material studied, the production of oxygen free radicals and nitric oxide (NO) by leukocytes was higher after their in vitro exposure to CL-S, but was quite similar to that of the control leukocytes after exposure to CL-E. In vivo, a one-month treatment with the CL-E filter increased plasma vitamin E by 84.3% with respect to treatment with CL-S; this gain slightly decreased to 68.9% when CL-E treatment was prolonged to three months. In the RBC, vitamin E was found to have increased by 76.7% and 113.4% at one and three months, respectively. Plasma glutathione (GSH) levels determined at three months were significantly increased from 0.10 +/- 0.02 to 0.33 +/- 0.12 mumol/ml, while the erythrocyte GSH was only slightly increased. The leukocyte function estimated as responsiveness to soluble chemical stimuli in CL-S-treated patients was significantly improved both qualitatively and quantitatively after CL-E treatment. The presence of an increased number of mononuclear cells undergoing programmed cell death (apoptosis) in CL-S-treated patients (18.8 +/- 1.7% vs. a control value of 6.5 +/- 2.3%) as well as the apoptogenic effect of their plasma in vitro on U937 cells was significantly corrected after CL-E treatment (mean decrease in apoptotic mononuclear cells at 24 hours of culture, 25.5% and 27.1% at 1 and 3 months, respectively). The anti-apoptogenic effect of CL-E treatment showed a close dependence on the increase in vitamin E in the blood cell compartment.

CONCLUSIONS

This study suggests that this vitamin E-modified membrane can be considered a highly biocompatible material, the antioxidant properties of which can exert a site-specific and timely scavenging function against oxygen free radicals in synergy with a hypostimulatory action on the PMN respiratory burst.

Purification and characterization of phycocyanin from the blue-green alga Aphanizomenon flos-aquae

Aphanizomenon flos-aquae (AFA) is a blue-green alga and represents a nutrient-dense food source. In this study the presence of phycocyanin (PC), a blue protein belonging to the photosynthetic apparatus, has been demonstrated in AFA. An efficient method for its separation has been set up: PC can be purified by a simple single step chromatographic run using a hydroxyapatite column (ratio A620/A280 of 4.78), allowing its usage for health-enhancing properties while eliminating other aspecific algal components. Proteomic investigation and HPLC analysis of purified AFA phycobilisomes revealed that, contrary to the well-characterized Synechocystis and Spirulina spp., only one type of biliprotein is present in phycobilisomes: phycocyanins with no allo-phycocyanins. Two subunit polypeptides of PC were also separated: the beta subunit containing two bilins as chromophore and the alpha subunit containing only one.

Overexpression of Erythrocyte Glutathione S-Transferase in Uremia and Dialysis

Background: Overexpression of glutathione S-transferase (GST; EC 2.5.1.18) has been documented in the erythrocytes of patients with chronic renal failure, and this event may well be of relevance from a clinical standpoint. In fact, it could serve as a marker of uremic toxicity overall, which can contribute to impair the function and survival of the erythrocytes. However, the biochemical details of this phenomenon are poorly understood.

Methods: In this study, we characterized the expression of GST in erythrocytes of 118 uremic patients under different clinical conditions. The mechanisms responsible for the regulation of protein expression and enzyme activity were investigated in light of different dialysis approaches, oxidative stress, uremic toxins, erythrocyte age, and erythropoietin (EPO) supplementation.

Results: Mean GST activity in uremic patients was highly overexpressed with respect to controls, and this phenomenon was exclusively attributable to an increased expression of GST. Overexpression of GST did not appear to be dependent on oxidative stress and was not influenced by vitamin E supplementation. In the same manner, both erythrocyte age and EPO supplementation apparently did not interfere with the GST concentrations, which were the same in controls and patients. Preliminary experiments suggested that high-molecular weight or protein-bound toxins could play some role in the overexpression of GST.

Conclusions: GST expression may be a useful marker for the individual accumulation of uremic toxins as well as of the efficiency of new dialysis strategies in removing them.

The effect of PMMA-based protein-leaking dialyzers on plasma homocysteine levels

BACKGROUND

Hyperhomocysteinemia is a well-recognized independent risk factor for cardiovascular disease in end-stage renal disease (ESRD) patients. Since homocysteine (Hcy) largely binds to serum proteins (80 to 90%), in this study we investigated the possibility that polymethylmethacrylate (PMMA)-based protein-leaking dialyzers could reduce total plasma Hcy (tHcy) levels in ESRD patients.

METHODS

Two matched groups of patients (N = 13) showing mild to intermediate hyperhomocysteinemia on standard hemodialysis (HD) with conventional non-protein-leaking dialyzers were included. In the control group membranes were maintained the same, while the study group was switched to protein-leaking dialyzers (BK-F series; Toray, Japan) and studied for 6 months. tHcy was measured by high performance liquid chromatography (HPLC) at baseline and after 1, 3, and 6 months. Proteins and Hcy were also measured in the spent dialysate.

RESULTS

The pre-HD levels of tHcy in the control group remained close to baseline values (26.6 +/- 5.0 micromol/L), while in the study group at 1, 3, and 6 months they decreased from a baseline value (in micrormol/L) of 25.3 +/- 5.9 to 21.5 +/- 4.5, 16.9 +/- 4.0, and 17.2 +/- 4.2, respectively (P < 0.01 for values at 3 and 6 months vs. baseline). The intra-HD drop of tHcy (Delta HDHcy) slightly but progressively decreased during the 3 steps on protein-leaking dialyzers and a positive correlation was found between Delta HDHcy and pre-HD levels of tHcy. In spent dialysate samples from protein-leaking dialyzer-treated patients, the amount of protein-bound Hcy (bHcy) was approximately 10 times higher than in non-protein-leaking dialyzers, but the Delta HDHcy observed in non-protein-leaking dialyzers and protein-leaking dialyzers was comparable. Serum proteins and albumin were only slightly affected by protein-leaking dialyzers.

CONCLUSION

This study demonstrates that protein-leaking dialyzers used with a pure diffusive technique significantly lower pre-HD tHcy (approximately 33% of starting levels after 3 months of treatment) in ESRD patients. A possible underlying mechanism for this effect could be the removal of large molecular weight solutes responsible for a defective metabolism of the Hcy, as the removal of bHcy with protein-leaking dialyzers seems not sufficient, per se, to explain this steady reduction of tHcy levels in pre-HD.

Erythrocyte redox state in uremic anemia: effects of hemodialysis and relevance of glutathione metabolism

Reduced and oxidized glutathione and pyridine coenzymes, glutathione-related enzymes and Cu,Zn-superoxide dismutase (Cu,Zn-SOD) were investigated in the RBC of patients with chronic renal failure (CRF) and in age- and sex-matched controls. The effects of hemodialysis (HD) were also studied. A defective RBC redox state was shown in the CRF group based on a decreased GSH/GSSG ratio and NADPH levels. Increased activities of glutathione transferase (GSH-S-T) and Cu,Zn-SOD were observed before HD. Dialysis apparently restores the levels of antioxidant enzymes and at the same time strongly affects the redox state. Thus we can speculate that HD can generate severe redox impairment inducing damage in RBC and plasma antioxidant enzymes. Increased erythrocyte GSSG and GSM-S-T levels coupled with a reduced hexose monophosphate shunt (HMPS) function may be useful indexes of oxidative stress in uremic anemia.

Redox state, antioxidative activity and lipid peroxidation in erythrocytes and plasma of chronic ambulatory peritoneal dialysis patients

Red blood cells and plasma reduced and oxidized glutathione levels, glutathione peroxidase (GSH-Px) activity, thiobarbituric acid reactants (TBAR) of both chronic ambulatory peritoneal dialysis (CAPD) patients and a matched control group were investigated in this study. Oxidized and reduced pyridinic nucleotides in red blood cells (RBC), in which NADPH is a direct expression of hexose monophosphate shunt function, were also studied. The results obtained indicate that RBC and plasma are exposed to oxidative stress in CAPD. This condition is characterized by a decreased GSH/GSSG ratio, particularly evident in RBC as a consequence of the GSSG accumulation. Lipid peroxidation is increased, as indicated by raised TBAR levels, and reduced pyridinic nucleotides are decreased. Increased GSH-Px levels and unmodified or slightly increased GSH content were observed in the RBC but not in plasma, which showed decreased GSH and unmodified peroxidase activity. Peroxidase correlated positively with TBAR levels in the RBC lysates. In a subgroup of patients treated with erythropoietin (vs. untreated patients and controls) no differences were observed in the glutathione-related parameters studied. These data suggest that a mechanism for adaptation to oxidative conditions may be present in CAPD and its effects on RBC integrity are discussed in comparison with the hemodialysis conditions previously studied.

Biological effects of oxidant stress in haemodialysis: the possible roles of vitamin E

Oxidative stress has been proposed to play a role in many disease states, including cardiovascular and infectious diseases, cancer, diabetes and neurodegenerative pathologies. The fact that these diseases have an increased incidence in uremia, and particularly in dialysis patients, suggests an increased exposure to oxidative stress in this condition. In haemodialysis (HD), the absence of a complete correction of the uremic toxicity together with the untoward effects of the dialysis, malnutrition and the progressive worsening of the clinical condition, can lead to a high susceptibility to oxidative stress by an abnormal production of oxidants - including reactive oxygen species (ROS) and uremic toxins with prooxidant function - and defective antioxidant protection. One of the most investigated biological effects of the oxidative stress in the HD patients is lipid peroxidation in plasma and blood cell membranes. Moreover, we have recently described how abnormal apoptosis in peripheral blood leukocytes is associated with cell oxidative stress (intracellular thiol depletion). Vitamin E, in both in vitro and in vivo conditions, has been proposed to partially correct these effects. In this review we evaluated some features of two new dialysis strategies using an antioxidant approach to the protection against the oxidant stress in HD. Their rationale is based on the emerging role of vitamin E in counteracting some biological effects associated with oxidant stress namely lipid peroxidation and apoptosis. These techniques use: 1) the recirculation of the dialysate through a suspension of vitamin E-enriched liposomes combined with the supplementation by the dialysate with ascorbic acid, this method has been called hemolipodialysis; 2) the coating of the dialysis membrane with vitamin E (vitamin E- modified dialysis membranes). These unconventional approaches to the antioxidant therapy in HD open a widely unexplored and promising field in the evolution of the biomaterials and dialysis quality.

Glycoxidation and inflammatory markers in patients on treatment with PMMA-based protein-leaking dialyzers

BACKGROUND

High-molecular-weight solutes such as glycation and oxidation protein products are putative proinflammatory mediators found in the uremic blood. The elimination of these and other large solutes by protein-leaking dialyzers (PLD) might help to correct the inflammatory status of maintenance hemodialysis (HD) patients.

METHODS

Two matched groups of 13 standard 3 times/week HD patients were treated for 6 months with PMMA-based PLD and non-protein-leaking dialyzers (NPLD), respectively. At baseline, 1, 3, and 6 months, we measured the blood levels of the inflammatory cytokines IL-1beta, TNF-alpha, IL-6, the acute-phase protein C-reactive protein (CRP), the adhesion molecules ICAM-1, VCAM-1, and selectine-E, the chemotaxis factors MCP-1, and the glycation and oxidation protein end products pentosidine, protein carbonyls, and AOPP.

RESULTS

In all the patients at baseline, pre-HD levels of glycation and oxidation protein markers, and inflammatory parameters were significantly higher than in healthy control subjects (P < 0.01 or greater). After 6 months, in the group on treatment with PLD, but not in that on NPLD, there was a significant decrease (P < 0.05 or greater) of pre-HD values of total pentosidine (mainly represented by pentosidine in serum albumin; -43%), protein carbonyls (-42%), AOPP (-38%), and the inflammatory cytokines IL-1beta (-49%), IL-6 (-39%), and TNF-alpha (-20%), while IL-10 and INF-gamma increased by 67% and 37%, respectively. Proinflammatory cytokines, and particularly IL-6, showed a positive correlation with the levels of circulating pentosidine. Protidemia was not significantly modified at the end of the study in both the groups.

CONCLUSION

The results in this pilot study show that the removal of large solutes by PLD can improve some indices of chronic inflammation in HD patients. Further studies are required to determine the relevance of the individual solutes removed with PLD as proinflammatory mediators in the uremic environment.

Biomarkers of oxidation, inflammation and cartilage degradation in osteoarthritis patients undergoing sulfur-based spa therapies

OBJECTIVES

To investigate the effects of sulfur-based spa therapies on oxidation, inflammation and cartilage degradation biomarkers in osteoarthritis (OA) patients.

DESIGN AND METHODS

Analyses were performed before therapy (T0), after therapy (T1) and 1 month after its suspension (T2), in OA subjects undergoing mud bath treatments in combination (group A) or not (group B) with hydropinotherapy, and compared with those of patients not subjected to spa therapies (group C).

RESULTS

No modifications in plasma/serum biomarker concentrations were observed throughout the study in non-treated patients, while a significant reduction in oxidation, inflammation and cartilage degradation parameters was evidenced in patients of group A. Group B presented a favorable biochemical profile at T1 but not at T2.

CONCLUSIONS

To ensure the long term preservation of the chondroprotective effects of sulfur-based therapies, standard mud bath treatments should be associated with hydropinotherapy in order to maintain reduced oxidative, inflammatory and degradative stimuli longer.

Peroxynitrite-induced oxidation of plasma lipids is enhanced in stable hemodialysis patients

BACKGROUND

The relationship between end-stage renal disease (ESRD), hemodialysis, and oxidative stress is controversial. To determine whether ESRD causes oxidative stress, we measured basal levels of plasma F2-isoprostanes as a marker of lipid peroxidation in vivo, and peroxynitrite-stimulated formation of F2-isoprostanes, as a marker of the oxidizibility of plasma lipids in vitro, before and after routine hemodialysis.

METHODS

Total plasma F2-isoprostanes were measured by gas chromatography-mass spectrometry (GC-MS) before and after the oxidation of plasma lipids with the peroxynitrite-generating compound, 3-morpholino-sydnonimine (SIN-1), in 23 patients with ESRD patients undergoing regular hemodialysis, and 14 controls. Plasma vitamin E concentrations were measured by high-performance liquid chromatography (HPLC).

RESULTS

There was no difference in basal plasma concentrations of F2-isoprostanes in the ESRD group prior to hemodialysis, 246 +/- 20 pg/mL, compared to controls, 252 +/- 28 pg/mL, or immediately on completion of hemodialysis, 236 +/- 14 pg/mL. Incubation of control plasma with SIN-1 caused the formation of F2-isoprostanes with plasma concentrations increasing to 987 +/- 54 pg/mL at 6 hours. The formation of F2-isoprostanes stimulated by SIN-1 was markedly enhanced in the plasma obtained from patients undergoing hemodialysis at 1861 +/- 174 pg/mL, P < 0.001, and SIN-1-induced formation of F2-isoprostanes was further increased in plasma obtained immediately after hemodialysis at 2437 +/- 168 pg/mL, P < 0.001. Incubation of plasma with SIN-1 resulted in the net consumption of vitamin E.

CONCLUSION

Although basal plasma F2-isoprostanes were similar in patients with ESRD compared with controls, the presence of oxidative stress in patients with ESRD was unmasked when the plasma was stressed by peroxynitrite generated from SIN-1, and this was enhanced further by hemodialysis.

Antioxidative effects of sulfurous mineral water: protection against lipid and protein oxidation

OBJECTIVES

To investigate the antioxidative properties of sulfurous drinking water after a standard hydropinic treatment (500 ml day(-1) for 2 weeks).

SUBJECTS/METHODS

Forty apparently healthy adults, 18 men and 22 women, age 41-55 years old. The antioxidant profile and the oxidative condition were evaluated in healthy subjects supplemented for 2 weeks with (study group) or without (controls) sulfurous mineral water both before (T0) and after (T1) treatment.

RESULTS

At T1, a significant decrease (P<0.05) in both lipid and protein oxidation products, namely malondialdehyde, carbonyls and AOPP, was found in plasma samples from subjects drinking sulfurous water with respect to controls. Concomitantly, a significant increment (P<0.05) of the total antioxidant capacity of plasma as well as of total plasmatic thiol levels was evidenced. Tocopherols, carotenoids and retinol remained almost unchanged before and after treatment in both groups.

CONCLUSIONS

The improved body redox status in healthy volunteers undergoing a cycle of hydropinic therapy suggests major benefits from sulfurous water consumption in reducing biomolecule oxidation, possibly furnishing valid protection against oxidative damage commonly associated with aging and age-related degenerative diseases.

Influence of ovarian stimulation for IVF/ICSI on the antioxidant defence system and relationship to outcome

Ovarian stimulation is used with IVF/intracytoplasmic sperm injection (ICSI) cycles to obtain multiple oocytes and improve pregnancy rates; however, it also induces perturbation in the oxidant-antioxidant balance leading to oxidation stress. The present study monitored the plasma antioxidant status in women undergoing a long agonist protocol of ovarian stimulation at three different time points: at baseline (T0), after pituitary suppression (T1) and on the day of oocyte retrieval (T2). The antioxidant composition of follicular fluid samples collected on T2 was also evaluated. Significant decreases (P < 0.05) of plasma vitamin C, vitamin E and carotenoids were found between T1 and T2 but not between T0 and T1. At T2, high plasma vitamin E was associated with high numbers of total and mature oocytes retrieved per patient, which, in turn, were favourable for achieving pregnancy. Accordingly, women who became pregnant presented higher vitamin E concentrations both in plasma and FF than those who did not. In conclusion, this study confirmed the occurrence of significant modifications of the plasma antioxidant profile during ovarian stimulation with gonadotrophins; at the same time, it was found that both systemic and follicular antioxidant status may be related to IVF/ICSI outcome.

Oxidative damage during hemodialysis using a vitamin-E-modified dialysis membrane: a preliminary characterization

A comparison of the oxyradical exposure during hemodialysis (HD) carried out with vitamin-E-modified cellulose (CL-E) or conventional membranes, studying red blood cell (RBC) and plasma lipoperoxidation and RBC glutathione metabolism, was done. In this preliminary characterization of a new and original approach to the prevention of free radical damage in HD, the results obtained indicate that lipoperoxidation in plasma and RBC is decreased and therefore oxidative damage can be significantly decreased using CL-E dialysis membranes instead of conventional membranes.

Protein thiols and glutathione influence the nitric oxide-dependent regulation of the red blood cell metabolism

Nitric oxide (NO) can modulate red blood cell (RBC) glycolysis by translocation of the enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPD) (EC 1.2.1.12) from the cytosolic domain of the membrane protein band 3 (cdb3) in the cytosol. In this study we have investigated which NO-reactive thiols might be influencing GAPD translocation and the specific role of glutathione. Two highly reactive Cys residues were identified by transnitrosylation with nitrosoglutathione (GSNO) of cdb3 and GAPD (K(2) = 73.7 and 101.5 M(-1) s(-1), respectively). The Cys 149 located in the catalytic site of GAPD is exclusively involved in the GSNO-induced nitrosylation. Reassociation experiments carried out at equilibrium with preparations of RBC membranes and GAPD revealed that different NO donors may form -SNO on, and decrease the affinity between, GAPD and cdb3. In intact RBC, the NO donors 3-morpholinosydnonimine (SIN-1) and peroxynitrite (ONOO(-)) significantly increased GAPD activity in the cytosol, glycolysis measured as lactate production, and energy charge levels. Our data suggest that ONOO(-) is the main NO derivative able to cross the RBC membrane, leading to GAPD translocation and -SNO formation. In cell-free experiments and intact RBC, diamide (a thiol oxidant able to inhibit GAPD activity) was observed to reverse the effect of SIN-1 on GAPD translocation. The results demonstrate that cdb3 and GAPD contain reactive thiols that can be transnitrosylated mainly by means of GSNO; these can ultimately influence GAPD translocation/activity and the glycolytic flux.

Vitamin E, lipid profile, and peroxidation in hemodialysis patients

BACKGROUND

Hypertriglyceridemia, lipid peroxidation, and abnormalities of the plasma fatty acid (PUFA) profile may be important risk factors for the atherosclerotic cardiovascular disease in hemodialysis (HD) patients.

METHODS

We investigated how these factors are affected by vitamin E supplementation carried out by oral administration (clinical study 1) and dialysis with vitamin E-modified dialyzers (clinical study 2).

RESULTS

In the HD patients, conditions of relative vitamin E deficiency were observed [lowered vitamin E/triglyceride (TG) ratio] in the presence of high levels of thiobarbituric acid reactants (TBARs) and decreased levels of the polyunsaturated fraction of PUFAs paired with an increased amount of monounsaturated ones (MUFA). In both studies, vitamin E supplementation significantly increased the levels of vitamin E in the plasma without affecting TG levels and provided a partial correction of TBAR levels. Of note was the relative increase in the PUFA fraction, which gave solid proof of an anti(per)oxidant effect of vitamin E supplementation in HD patients. Vitamin E supplementation was also observed to increase plasma levels of reduced glutathione and NOx (NO2 + NO3).

CONCLUSION

The results suggest that vitamin E supplementation may be an effective accessory therapy to combat oxidative stress-lowering lipid peroxidation in HD patients.