Concept: Hydrogen peroxide
Experts agree that careful cleaning and disinfection of environmental surfaces are essential elements of effective infection prevention programs. However, traditional manual cleaning and disinfection practices in hospitals are often suboptimal. This is often due in part to a variety of personnel issues that many Environmental Services departments encounter. Failure to follow manufacturer’s recommendations for disinfectant use and lack of antimicrobial activity of some disinfectants against healthcare-associated pathogens may also affect the efficacy of disinfection practices. Improved hydrogen peroxide-based liquid surface disinfectants and a combination product containing peracetic acid and hydrogen peroxide are effective alternatives to disinfectants currently in widespread use, and electrolyzed water (hypochlorous acid) and cold atmospheric pressure plasma show potential for use in hospitals. Creating “self-disinfecting” surfaces by coating medical equipment with metals such as copper or silver, or applying liquid compounds that have persistent antimicrobial activity surfaces are additional strategies that require further investigation. Newer “no-touch” (automated) decontamination technologies include aerosol and vaporized hydrogen peroxide, mobile devices that emit continuous ultraviolet (UV-C) light, a pulsed-xenon UV light system, and use of high-intensity narrow-spectrum (405 nm) light. These “no-touch” technologies have been shown to reduce bacterial contamination of surfaces. A micro-condensation hydrogen peroxide system has been associated in multiple studies with reductions in healthcare-associated colonization or infection, while there is more limited evidence of infection reduction by the pulsed-xenon system. A recently completed prospective, randomized controlled trial of continuous UV-C light should help determine the extent to which this technology can reduce healthcare-associated colonization and infections. In conclusion, continued efforts to improve traditional manual disinfection of surfaces are needed. In addition, Environmental Services departments should consider the use of newer disinfectants and no-touch decontamination technologies to improve disinfection of surfaces in healthcare.
Thirdhand smoke (THS) is the accumulation of secondhand smoke on environmental surfaces. THS is found on the clothing and hair of smokers as well as on surfaces in homes and cars of smokers. Exposure occurs by ingestion, inhalation and dermal absorption. Children living in homes of smokers are at highest risk because they crawl on the floor, touch parents' clothing/hair and household objects. Using mice exposed to THS under conditions that mimic exposure of humans, we show that THS increases cellular oxidative stress by increasing superoxide dismutase (SOD) activity and hydrogen peroxide (H2O2) levels while reducing the activity of antioxidant enzymes catalase and glutathione peroxidase (GPx) that break down H2O2 into H2O and O2. This results in lipid peroxidation, protein nitrosylation and DNA damage. Consequences of these cell and molecular changes are hyperglycemia and insulinemia. Indeed, we found reduced levels of insulin receptor, PI3K, AKT, all important molecules in insulin signaling and glucose uptake by cells. To determine whether these effects on THS-induced insulin resistance are due to increase in oxidative stress, we treated mice exposed to THS with the antioxidants N-acetyl cysteine (NAC) and alpha-tocopherol (alpha-toc) and showed that the oxidative stress, the molecular damage, and the insulin resistance, were significantly reversed. Conversely, feeding the mice with chow that mimics “western diet”, which is known to increase oxidative stress, while exposing the mice to THS, further increased the oxidative stress and aggravated hyperglycemia and insulinemia. In conclusion, THS exposure results in insulin resistance in the form of non-obese type II diabetes (NODII) through oxidative stress. If confirmed in humans, these studies could have a major impact on how people view exposure to environmental tobacco toxins, in particular to children, elderly and workers in environments where tobacco smoke has taken place.
Swimming in indoor pools treated with combined chemical treatments (e.g. ozone) may reduce direct exposure to disinfection byproducts and thus have less negative effects on respiratory function compared to chlorinated pools. The aim of this study is to analyze the effects of a short-term training intervention on respiratory function and lung epithelial damage in adults exercising in indoor swimming pool waters treated with different disinfection methods (chlorine vs. ozone with bromine).
Although acute exhaustive exercise is known to increase liver reactive oxygen species (ROS) production and aerobic training has shown to improve the antioxidant status in the liver, little is known about mitochondria adaptations to aerobic training. The main objective of this study was to investigate the effects of the aerobic training on oxidative stress markers and antioxidant defense in liver mitochondria both after training and in response to three repeated exhaustive swimming bouts.
To evaluate the performance of vaporized hydrogen peroxide (VHP) for the bio-decontamination of the high efficiency particulate air (HEPA) filter unit.
Sarcopenia is the progressive loss of skeletal muscle that contributes to the decline in physical function during aging. A higher level of oxidative stress has been implicated in aging sarcopenia. The current study aims to determine if the higher level of oxidative stress is a result of increased superoxide (O2 ) production by the NADPH oxidase (NOX) enzyme or decrease in endogenous antioxidant enzyme protection.
Insulin resistance is defined as a reduced ability of insulin to stimulate glucose utilization. C57BL/6 mice fed with a high-fat diet (HFD) are a model of insulin resistance. In skeletal muscle, hydrogen peroxide (H2O2) produced by NADPH oxidase 2 (NOX2) is involved in signaling pathways triggered by insulin. We evaluated oxidative status in skeletal muscle fibers from insulin-resistant and control mice by determining H2O2 generation (HyPer probe), reduced-to-oxidized glutathione ratio and NOX2 expression. After eight weeks of HFD, insulin-dependent glucose uptake was impaired in skeletal muscle fibers when compared with control muscle fibers. Insulin-resistant mice showed increased insulin-stimulated H2O2 release and decreased reduced-to-oxidized glutathione ratio (GSH/GSSG). In addition, p47phox and gp91phox (NOX2 subunits) mRNA levels were also high (~3-fold in HFD mice compared to controls), while protein levels were 6.8- and 1.6-fold higher, respectively. Using apocynin (NOX2 inhibitor) during the HFD feeding period, the oxidative intracellular environment was diminished and skeletal muscle insulin-dependent glucose uptake restored. Our results indicate that insulin-resistant mice have increased H2O2 release upon insulin stimulation when compared with control animals, which appears to be mediated by an increase in NOX2 expression.
Depressive disorders often run in families, which, in addition to the genetic component, may point to the microbiome as a causative agent. Here, we employed a combination of behavioral, molecular and computational techniques to test the role of the microbiota in mediating despair behavior. In chronically stressed mice displaying despair behavior, we found that the microbiota composition and the metabolic signature dramatically change. Specifically, we observed reduced Lactobacillus and increased circulating kynurenine levels as the most prominent changes in stressed mice. Restoring intestinal Lactobacillus levels was sufficient to improve the metabolic alterations and behavioral abnormalities. Mechanistically, we identified that Lactobacillus-derived reactive oxygen species may suppress host kynurenine metabolism, by inhibiting the expression of the metabolizing enzyme, IDO1, in the intestine. Moreover, maintaining elevated kynurenine levels during Lactobacillus supplementation diminished the treatment benefits. Collectively, our data provide a mechanistic scenario for how a microbiota player (Lactobacillus) may contribute to regulating metabolism and resilience during stress.
Oxidative stress has long been associated with aging and has recently been linked to psychiatric disorders, including psychosis and depression. We identified multiple antipsychotics and antidepressants that extend Caenorhabditis elegans lifespan and protect the animal from oxidative stress. Here, we report that atypical antidepressants activate a neuronal mechanism that regulates the response to oxidative stress throughout the animal. While the activation of the oxidative stress response by atypical antidepressants depends on synaptic transmission, the activation by reactive oxygen species does not. Lifespan extension by atypical antidepressants depends on the neuronal oxidative stress response activation mechanism. Neuronal regulation of the oxidative stress response is likely to have evolved as a survival mechanism to protect the organism from oxidative stress, upon detection of adverse or dangerous conditions by the nervous system.
Neutrophils form the first line of host defense against infections that combat pathogens using two major mechanisms, the phagocytosis or the release of neutrophil extracellular traps (NETs). The netosis (NET formation) exerts additional, unfavorable effects on the fitness of host cells and is also involved at the sites of lung infection, increasing the mucus viscosity and in the circulatory system where it can influence the intravascular clot formation. Although molecular mechanisms underlying the netosis are still incompletely understood, a role of NADPH oxidase that activates the production of reactive oxygen species (ROS) during the initiation of NETs has been well documented. Since several commonly used drugs can affects the netosis, our current study was aimed to determine the effects of selected mucolytic, anti-inflammatory and cardiovascular drugs on NET formation, with a special emphasis on ROS production and NADPH oxidase activity. The treatment of neutrophils with N-acetylcysteine, ketoprofen and ethamsylate reduced the production of ROS by these cells in a dose-dependent manner. NET formation was also modulated by selected drugs. N-acetylcysteine inhibited the netosis but in the presence of H2O2 this neutrophil ability was restored, indicating that N-acetylcysteine may influence the NET formation by modulating ROS productivity. The administration of ethamsylate led to a significant reduction in NET formation and this effect was not restored by H2O2 or S. aureus, suggesting the unexpected additional side effects of this drug. Ketoprofen seemed to promote ROS-independent NET release, simultaneously inhibiting ROS production. The results, obtained in this study strongly suggest that the therapeutic strategies applied in many neutrophil-mediated diseases should take into account the NET-associated effects.