Marek Kasielski

Uric Acid but Not Apple Polyphenols Is Responsible for the Rise of Plasma Antioxidant Activity after Apple Juice Consumption in Healthy Subjects

Objective: To determine whether (1) rapid consumption of 1 L of apple juice increases blood antioxidant capacity, measured as ferric-reducing ability of plasma (FRAP) and serum 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity, and (2) apple polyphenols or fructose-induced elevation of plasma uric acid contributes to post-juice increase of blood antioxidant activity. Methods: The study involved 12 (mean age 32 ± 5 years, mean body weight 73 ± 7 kg) healthy nonsmoking subjects. Tested subjects consumed 1 L of clear apple juice and then FRAP; serum DPPH-scavenging activity, serum uric acid, and total plasma phenolics and quercetin levels were measured just before juice ingestion and 1, 2.5, and 4 hours after ingestion. This was repeated 3 times with 4-day intervals, but volunteers drank either 1 L of clear apple juice without polyphenols (placebo), or 1 L of cloudy apple juice (positive control), or 1 L of water (negative control) at the time. All juices had similar content of sugars (i.e., saccharose, glucose, and fructose) and precisely defined composition of phenolics and antioxidant activity. Results: Consumption of all 3 juices transiently increased FRAP and serum DPPH-scavenging activity, with peak values at 1 hour post-juice ingestion. This was paralleled by the rise of serum uric acid, but no significant changes in plasma total phenolics and quercetin levels were observed after all dietary interventions. At the same time, no substantial differences were found between juices (especially between clear apple juice and clear apple juice without polyphenols) concerning the measured variables. A strong significant correlation was noted instead between serum uric acid and plasma antioxidant activity at all analyzed time points, before and after juice ingestion. Plasma total phenolics and quercetin levels were not associated with FRAP and serum DPPH radical-scavenging activity. Conclusions: We have demonstrated that rapid consumption of apple juice increased plasma antioxidant activity in healthy subjects; this was caused by the fructose-induced rise of serum uric acid levels, but was not due to the presence of antioxidant polyphenols in juice. Thus, short-term consumption of apple juice seems not to be the effective dietary intervention to augment plasma antioxidant activity due to the concomitant possibility for uric acid to be a risk factor for several diseases, as verified by other authors.

Elevated exhalation of hydrogen peroxide in patients with systemic sclerosis

Background Systemic sclerosis is accompanied by an influx of activated phagocytes into distal airways. These cells release H2O2, which may evaporate from the airways surface and be detected in expired breath condensate. We tested whether patients with systemic sclerosis exhale more H2O2 than healthy subjects and whether breath condensate H2O2 levels correlate with some clinical parameters.

Myocardial oxidative stress in patients with active infective endocarditis

BACKGROUND Infective endocarditis (IE) induces the rise of pro-inflammatory cytokines. Some of them can stimulate oxidants production in myocardium with subsequent peroxidative damage to various biomolecules. We compared indices of oxidative stress: H2O2, thiobarbituric acid-reactive substances (TBARs), thiols in myocardium specimens between patients with active IE and those with valvular heart disease (VHD) of rheumatic etiology who underwent surgical valve replacement. METHODS 17 left ventricle papillary muscle specimens and 28 specimens of auricle of the right heart were collected from 45IE patients, and 16 papillary muscle and 12 auricle specimens from 28 VHD patients, respectively. Patients groups had similar NYHA functional class and majority of echocardiographic indices of heart morphology. H2O2 and TBARs were determined fluorometrically in myocardium homogenates whereas thiols with photometric method. Between and within groups comparisons and mutual correlations between variables were analyzed. RESULTS H2O2 generation from all myocardium specimens and auricles was 2.14- and 2.59- times higher (p<0.001) in IE patients than in VHD group. Auricles had the highest H2O2 levels within IE group. TBARs were 10-times higher (p<0.05) in IE when compared to VHD group in auricles and papillary muscles. Thiols did not differ between groups. H2O2 positively correlated with TBARs and negatively with thiols in all IE myocardium specimens (r=0.31 and r=-0.46, p<0.05) and auricles (r=0.58 and r=-0.67, p<0.05), respectively. No such associations were noted in VHD specimens. CONCLUSIONS Active IE induces enhanced myocardial production of H2O2 and formation of TBARs which proves occurrence of oxidative stress in the heart.

No evidence of enhanced oxidant production in blood obtained from patients with obstructive sleep apnea

BackgroundObstructive sleep apnea syndrome (OSAS) is a recognized risk factor for cardiovascular morbidity and mortality, perhaps due to causative exacerbations of systemic oxidative stress. Putative oxidative stress related to numerous episodes of intermittent hypoxia, may be an oxidants chief driving force in OSAS patients.MethodsWe assessed the resting and n-formyl-methionyl-leucyl-phenylalanine (fMLP)- induced whole blood chemiluminescence (as a measure of oxidant production by polymorphonuclear leukocytes and monocytes), ferric reducing ability of plasma (FRAP) and H2O2 generation in the whole blood of 27 untreated OSAS patients, 22 subjects after a night of CPAP therapy and 11 controls without OSAS. All of them were matched to age, BMI (body mass index) and smoking habits. All parameters were measured before and after polysomnography-controlled sleep, individual results were obtained as a mean from duplicated experiments.ResultsNo significant differences were distinguished between evening and morning blood chemiluminescence, H2O2 activity and FRAP within and between all three study groups.For instance patients with untreated OSAS had similar morning and evening resting whole blood chemiluminescence (2.3 +/- 2.2 vs. 2.4 +/- 2.2 [aU·10-4 phagocytes]), total light emission after stimulation with fMLP (1790 +/- 1371 vs. 1939 +/- 1532 [aU·s·10-4 phagocytes]), as well as FRAP after 3 min. plasma incubation (602 +/- 202 vs. 671 +/- 221 [uM]). Although, in the subgroup of 11 patients with severe OSAS (apnea/hypopnea index 58 +/- 18/h and oxygen desaturation index 55 +/- 19/h), the morning vs. evening resting chemiluminescence and total light emission after stimulation with fMLP observed a propensity to elevate 2.5 +/- 2.7 vs. 1.9 +/- 1.8 [aU·10-4 phagocytes] and 1778 +/- 1442 vs. 1503 +/- 1391 [aU·s·10-4 phagocytes], respectively, these did not attain statistical significance (p > 0.05).ConclusionOur investigation exposed no evidence in the overproduction of oxidants via circulating phagocytes, once considered a culprit in the oxidative stress of OSAS patients.

Elevated resting and agonist-induced whole blood chemiluminescence in patients with active infective endocarditis

Infective endocarditis (IE) and surgical procedures related to cardiac surgery are accompanied by inflammatory responses that may alter production of oxidants by phagocytes. This study evaluates luminol enhanced whole blood chemiluminescence (LBCL) as a measure of oxidative production by circulating phagocytes in 26 IE patients in comparison to 27 matched patients with acquired valvular heart disease and 25 healthy controls. Blood was collected the day before and 3, 7, 12 and 21 days after valve replacement surgery for LBCL measurement; resting (rCL) and agonist (fMLP)-stimulated total light emission (tCL). Preoperative rCL and tCL with values observed after 3, 7, 14, and 21 days from surgery were higher (P<0.01) in patients with IE than in healthy controls. Median preoperative rCL, and tCL was about 2.5-times higher (P<0.01) in IE group than in patients with valvular heart disease (4.3 vs. 1.7 U/10(4) phagocytes and 2473 vs. 782 Uxs/10(4) phagocytes). Three days after valve replacement, LBCL rose three times (P<0.01) in both operated groups. With patient recovery, LBCL decreased and no differences were noted between groups. Patients with IE had elevated LBCL reflecting increased oxidants release from circulating phagocytes that may predispose to the development of oxidative stress.