Reactive oxygen species (ROS), oxygen radicals and antioxidants: Where are we now, where is the field going and where should we go?

The field of oxygen free radicals, antioxidants and reactive oxygen species (ROS) has exploded in the past few decades, and BBRC has published several seminal papers. ROS can cause oxidative damage, but also play fundamental roles in living organisms, in such processes as signal transduction and defence against pathogens. ROS underpin every aspect of human biology. Indeed, an endless stream of published papers refers to the biological roles of "ROS". Sadly, much of this work is mechanistically meaningless. To make progress, the detailed molecular mechanisms of action of ROS must be elucidated and appropriate methodology must be used to measure them and the oxidative damage that they can cause, as emphasized in a recent review by Murphy et al. Attention must also switch from clinical studies involving administration of high-dose supplements of vitamins E, C and ß-carotene for the treatment or prevention of human disease into other promising diet-derived cytoprotective agents. One of them may be ergothioneine.

The long term effects of intrascrotal low dose and high dose N-acetylcysteine on testis damage in rat model of testicular torsion.

BACKGROUND/PURPOSE: During testicular torsion, the testes face oxidative damage owing to ischemia/reperfusion. We studied the long term effects of the intrascrotal administration of N-acetylcysteine (NAC) during detorsion procedure in a rat model of testicular torsion. METHODS: Twenty-eight rats were divided into 4 groups: (1) Control group: No procedure was done (2): Torsion-detorsion group: Testis torsion applied for 3 h (3): Low Dose Group: After testis torsion-detorsion (for 3 h) 10 mg/kg NAC was given into tunica vaginalis (4): High Dose Group: After testis torsion-detorsion (for 3 h) 100 mg/kg NAC was given into tunica vaginalis. We measured dimensions of the testes and examined pathological findings and Johnsen and Cosantino Scores. RESULTS: For testes height and volume, high dose NAC group had better results than the torsion-detorsion group (p = 0.019, p = 0.049). Testes weight showed no difference (p = 0.204). Sertoli cell number per tubule in the high dose NAC group was statistically different than the torsion-detorsion group (p = 0.017). CONCLUSIONS: When NAC was given intrascrotally at a dose of 100 mg/kg, it decreased the loss of testis volume and height, and Sertoli cell number per tubule was similar to the control group. These results suggest that the higher dose intrascrotal NAC administered during detorsion may have a protective effect.

The Effect of Intravenous Selenium on Oxidative Stress in Critically Ill Patients with Acute Respiratory Distress Syndrome.

OBJECTIVE: To modulate the inflammatory response in respiratory distress syndrome (ARDS) with selenium. BACKGROUND: Selenium replenishes the glutathione peroxidase proteins that are the first line of defense for an oxidative injury to the lungs. METHODS: Forty patients with ARDS were randomized into two groups: the SEL+ group being administered sodium selenite and the SEL- group receiving normal saline for 10 days. Blood samples were taken on Day-0, DAY-7, and Day-14 for assessment of IL-1 beta, IL-6, C-reactive protein, GPx-3, and selenium. Ferric reducing antioxidant power (FRAP) was measured in the bronchial wash fluids. Pearson correlation and repeated measure analysis were performed to examine the effects of selenium on the inflammatory markers. RESULTS: Sodium selenite replenished selenium levels in the SEL+ group. Selenium concentrations were linearly correlated to serum concentrations of GPx3 (R value: 0.631; P < 0.001), and FRAP (R value: -0.785; P < 0.001). Serum concentrations of both IL 1-beta (R value: -0.624; P < 0.001) and IL-6 (R value: -0.642; P < 0.001) were inversely correlated to the serum concentrations of selenium. There was a meaningful difference between two groups in airway resistance and pulmonary compliance changes (P values 0.008 and 0.028, respectively). CONCLUSION: Selenium restored the antioxidant capacity of the lungs, moderated the inflammatory responses, and meaningfully improved the respiratory mechanics. Despite these changes, it had no effect on the overall survival, the duration of mechanical ventilation, and ICU stay. Selenium can be used safely; however, more trials are essential to examine its clinical effectiveness.

Effects of quercetin on heart nitric oxide metabolism in l-NAME treated rats.

This study investigated the effects of a quercetin-supplemented diet on the biochemical changes installed in the heart of NO-deficient rats in terms of oxidants production and NO bioavailability determinants. Sprague-Dawley rats were subjected to Nω-nitro-l-arginine methyl ester (l-NAME) treatment (360 mg/L l-NAME in the drinking water, 4 d) with or without supplementation with quercetin (4 g/kg diet). l-NAME administration led to increased blood pressure (BP) (30%), decreased nitric oxide synthase (NOS) activity (50%), and increases in NADPH oxidase (NOX)-dependent superoxide anion production (60%) and p47phox protein level (65%). The co-administration of quercetin prevented the increase in BP and the activation of NOX but did not modify the decrease in NOS activity caused by l-NAME. In addition, quercetin affected oxidative stress parameters as glutathione oxidation, and the activities of oxidant detoxifying enzymes superoxide dismutase, glutathione peroxidase, and catalase. Thus, quercetin administration counteracts l-NAME effects on NO bioavailability determinants in vivo, essentially through controlling NOX-mediated superoxide anion production.

Hyperbaric Oxygen Reduces Aspergillus fumigatus Proliferation In Vitro and Influences In Vivo Disease Outcomes.

Recent estimates suggest that more than 3 million people have chronic or invasive fungal infections, causing more than 600,000 deaths every year. Aspergillus fumigatus causes invasive pulmonary aspergillosis (IPA) in patients with compromised immune systems and is a primary contributor to increases in human fungal infections. Thus, the development of new clinical modalities as stand-alone or adjunctive therapy for improving IPA patient outcomes is critically needed. Here we tested the in vitro and in vivo impacts of hyperbaric oxygen (HBO) (100% oxygen, >1 atmosphere absolute [ATA]) on A. fumigatus proliferation and murine IPA outcomes. Our findings indicate that HBO reduces established fungal biofilm proliferation in vitro by over 50%. The effect of HBO under the treatment conditions was transient and fungistatic, with A. fumigatus metabolic activity rebounding within 6 h of HBO treatment being removed. In vivo, daily HBO provides a dose-dependent but modest improvement in murine IPA disease outcomes as measured by survival analysis. Intriguingly, no synergy was observed between subtherapeutic voriconazole or amphotericin B and HBO in vitro or in vivo with daily HBO dosing, though the loss of fungal superoxide dismutase genes enhanced HBO antifungal activity. Further studies are needed to optimize the HBO treatment regimen and better understand the effects of HBO on both the host and the pathogen during a pulmonary invasive fungal infection.

Modifying Effect of Autotransfusion of Mesenchymal Stromal Cells on the Production of Reactive Oxygen Species and Cytokines by Mononuclear Cells in Patients with Chronic Heart Failure.

We studied in vivo modifying effect of autotransfusion of human bone marrow mesenchymal stromal cells on ROS generation and production of cytokines (TNFα,TNFß, IL-1α, IL-10, IFNγ, and GM-CSF) and PGE2 by mononuclear cells of patients (N=21) with chronic heart failure. These parameters were evaluated prior to (control) and after (immediately and on day 14) intravenous administration of stromal cells in doses of 100-200×106. Immediately after autotransfusion, significant increase of in vitro zymosan-induced chemiluminescence of blood mononuclear cells from 10 patients was observed. At later terms after autotransfusion (day 14), inhibition of chemiluminescent activity of blood mononuclear cells was revealed in 50% patients. We discuss possible mechanisms of involvement of transplanted autologous bone marrow mesenchymal stromal cells in reprogramming of blood mononuclear phagocytes from the pro- to anti-inflammatory phenotype under conditions of their in vivo interaction manifesting in transition from activation to inhibition of ROS-producing activity of macrophages and significant suppression of in vitro LPS-induced production of TNFα and GM-CSF by blood mononuclears against the background of significantly elevated TNFß, IL-10, and IL-1α concentrations.

Hyperbaric Oxygen Sensitizes Anoxic Pseudomonas aeruginosa Biofilm to Ciprofloxacin.

Chronic Pseudomonas aeruginosa lung infection is characterized by the presence of endobronchial antibiotic-tolerant biofilm, which is subject to strong oxygen (O2) depletion due to the activity of surrounding polymorphonuclear leukocytes. The exact mechanisms affecting the antibiotic susceptibility of biofilms remain unclear, but accumulating evidence suggests that the efficacy of several bactericidal antibiotics is enhanced by stimulation of aerobic respiration of pathogens, while lack of O2 increases their tolerance. In fact, the bactericidal effect of several antibiotics depends on active aerobic metabolism activity and the endogenous formation of reactive O2 radicals (ROS). In this study, we aimed to apply hyperbaric oxygen treatment (HBOT) to sensitize anoxic P. aeruginosa agarose biofilms established to mimic situations with intense O2 consumption by the host response in the cystic fibrosis (CF) lung. Application of HBOT resulted in enhanced bactericidal activity of ciprofloxacin at clinically relevant durations and was accompanied by indications of restored aerobic respiration, involvement of endogenous lethal oxidative stress, and increased bacterial growth. The findings highlight that oxygenation by HBOT improves the bactericidal activity of ciprofloxacin on P. aeruginosa biofilm and suggest that bacterial biofilms are sensitized to antibiotics by supplying hyperbaric O2.

Ten misconceptions about antioxidants.

Oxidative damage is a common cellular event involved in numerous diseases and drug toxicities. Antioxidants prevent or delay oxidative damage, and therefore there has been extensive research into the discovery of natural and newly designed antioxidants. Initial excitement regarding the potential health benefits of antioxidants has diminished. Currently, it is even claimed that antioxidants increase mortality. The antioxidant pendulum appears to swing from healthy to toxic and from general panacea to insignificant ingredient. Owing to the polarity of views towards antioxidants, nutritional recommendation ranges from advice to increase antioxidant status in plasma to the notion that it is a useless measurement. Such views, lacking sufficient scientific support, lead to misconceptions, which in our opinion hinder the rational use of food supplements and impedes the design and development of new antioxidant drugs. As a result, good opportunities might easily be missed.

Electrolysis of physiological salt solution generates a factor that relaxes vascular smooth muscle

Oxygen-derived free radicals have been implicated in many important functions in the biological system. Electrical field stimulation (EFS) causes arterial relaxation in animal models. We found that EFS applied to neither muscle nor nerve but to Krebs solution caused a relaxation of rat aorta that had been contracted with phenylephrine. In the present study, therefore, we investigated the characteristics of this EIRF (electrolysis-induced relaxing factor) using rat isolated aorta. Results indicated that EIRF acts irrespective of the presence of endothelium. EIRF shows positive Griess reaction and is diffusible and quite stable. EIRF-induced relaxation was stronger on PE-contracted aorta than on KCl-contracted one, and inhibited by the pretreatment with methylene blue. Zaprinast, a cGMP-specific phosphodiesterase inhibitor, potentiated the EIRF-induced relaxation. NG-nitro-L-arginine, NO synthase inhibitor, did not inhibit the EIRF-induced relaxation. Deferroxamine, but not ascorbic acid, DMSO potentiated the EIRF-induced relaxation. These results indicate that electrolysis of Krebs solution produces a factor that relaxes vascular smooth muscle via cGMP-mediated mechanism.