Oxidative Stress In Humans Research Articles

Identification and quantification of phenanthrene ortho-quinones in human urine and their association with lipid peroxidation

Although human exposure to polycyclic aromatic hydrocarbons (PAH) has been associated with in vivo oxidative damage, and hydroxyPAH metabolites have been used as biomarkers to assess PAH-induced oxidative stress, few studies have looked at the likely causative compounds for oxidative stress in humans - PAH quinones. We developed a method using pre-column derivatization - liquid chromatography-heated electrospray ionization-tandem mass spectrometry (LC-HESI-MS/MS) to analyze ortho-phenanthrene quinones (PheQs) in human urine. 1,2-PheQ and 3,4-PheQ were identified and quantified in 3 mL of human urine; their total concentrations were higher in cigarette smokers (0.79 ± 0.98 nmol/6h urine) than in nonsmokers (0.20 ± 0.98 nmol/6h urine) (p < 0.01). The total of 1,2-PheQ and 3,4-PheQ were more strongly correlated with urinary (Z)-7-[1R,2R,3R,5S)-3,5-dihydroxy-2-[(E,3S)-3-hydroxyoct-1-enyl]cyclopentyl]hept-5-enoic acid (8-iso-PGF2α), a biomarker of lipid peroxidation (R2 = 0.53, p < 0.001), than the other phenanthrene metabolites including phenanthrene tetraol (PheT), phenanthrene-1,2-dihydrodiol (1,2-PheD), and total phenanthrene phenols (OHPhe), consistent with the concept that PheQs and likely other PAH quinones play a causal role in the generation of reactive oxygen species (ROS) in humans. Thus, PheQs may be suitable as biomarkers to assess human exposure to oxygenated PAH and the subsequent oxidative damage. This study provides unique support, by analysis of human urinary metabolites, for the PAH quinone mediated oxidative damage hypothesis of PAH carcinogenesis.

Bisphenols and Oxidative Stress Biomarkers-Associations Found in Human Studies, Evaluation of Methods Used, and Strengths and Weaknesses of the Biomarkers.

Bisphenols, particularly bisphenol A (4,4′-(hexafluoroisopropylidene)-diphenol) (BPA), are suspected of inducing oxidative stress in humans, which may be associated with adverse health outcomes. We investigated the associations between exposure to bisphenols and biomarkers of oxidative stress in human studies over the last 12 years (2008‒2019) related to six health endpoints and evaluated their suitability as effect biomarkers. PubMed database searches identified 27 relevant articles that were used for data extraction. In all studies, BPA exposure was reported, whereas some studies also reported other bisphenols. More than a dozen different biomarkers were measured. The most frequently measured biomarkers were 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-OHdG), 8-iso-prostaglandin F2α (8-isoprostane) and malondialdehyde (MDA), which almost always were positively associated with BPA. Methodological issues were reported for MDA, mainly the need to handle samples with caution to avoid artefact formation and its measurements using a chromatographic step to distinguish it from similar aldehydes, making some of the MDA results less reliable. Urinary 8-OHdG and 8-isoprostane can be considered the most reliable biomarkers of oxidative stress associated with BPA exposure. Although none of the biomarkers are considered BPA- or organ-specific, the biomarkers can be assessed repeatedly and non-invasively in urine and could help to understand causal relationships.

Mechanism of Action of TiO2: Recommendations to Reduce Uncertainties Related to Carcinogenic Potential.

The Risk Assessment Committee of the European Chemicals Agency issued an opinion on classifying titanium dioxide (TiO2) as a suspected human carcinogen upon inhalation. Recent animal studies indicate that TiO2 may be carcinogenic through the oral route. There is considerable uncertainty on the carcinogenicity of TiO2, which may be decreased if its mechanism of action becomes clearer. Here we consider adverse outcome pathways and present the available information on each of the key events (KEs). Inhalation exposure to TiO2 can induce lung tumors in rats via a mechanism that is also applicable to other poorly soluble, low-toxicity particles. To reduce uncertainties regarding human relevance, we recommend gathering information on earlier KEs such as oxidative stress in humans. For oral exposure, insufficient information is available to conclude whether TiO2 can induce intestinal tumors. An oral carcinogenicity study with well-characterized (food-grade) TiO2 is needed, including an assessment of toxicokinetics and early KEs.

Characteristics and potential inhalation exposure risks of PM2.5–bound environmental persistent free radicals in Nanjing, a mega–city in China

PM2.5–bound toxic elements and organic pollutants have been extensively investigated, while limited information is available for environmental persistent free radicals (EPFRs) associated with PM2.5, which may lead to oxidative stress in the human lung when exposed to PM2.5. In this study, the levels and types of PM2.5–bound EPFRs present in Nanjing, a mega–city in China, were analyzed. PM2.5–bound EPFRs were found to mainly be a mixture of carbon– and oxygen–centered radicals. The concentration of PM2.5–bound EPFRs ranged from 2.78 × 1012 to 1.72 × 1013 spins m−3, with an average value of 7.61 × 1012 spins m−3. The half–life of the PM2.5–bound EPFRs was calculated to be an average of 83.5 days when stored at room temperature, with only weak correlations observed between EPFRs and conventional air pollutants (NO2, O3, CO and PM2.5)/PM2.5–bound transition metals (Cu, Zn, Cr, Mn, V, Cd, and Ni) and significant correlations between EPFRs and SO2/PM2.5–bound Fe. PM2.5–bound EPFRs can induce the formation of reactive oxygen species (ROS) in both water and a H2O2 solution, which are used to simulate lung solution of a healthy person and patient, respectively. Therefore, PM2.5–bound EPFRs can lead to potential oxidative stress in humans. Overall, PM2.5–bound EPFRs show an obvious temporal variation and can pose potential health risks to humans via the induction of ROS in the lung solution.

Impact of posttranslational modifications on atomistic structure of fibrinogen.

Oxidative stress in humans is related to various pathophysiological processes, which can manifest in numerous diseases including cancer, cardiovascular diseases, and Alzheimer’s disease. On the atomistic level, oxidative stress causes posttranslational modifications, thus inducing structural and functional changes into the proteins structure. This study focuses on fibrinogen, a blood plasma protein that is frequently targeted by reagents causing posttranslational modifications in proteins. Fibrinogen was in vitro modified by three reagents, namely sodium hypochlorite, malondialdehyde, and 3-morpholinosydnonimine that mimic the oxidative stress in diseases. Newly induced posttranslational modifications were detected via mass spectrometry. Electron microscopy was used to visualize changes in the fibrin networks, which highlight the extent of disturbances in fibrinogen behavior after exposure to reagents. We used molecular dynamics simulations to observe the impact of selected posttranslational modifications on the fibrinogen structure at the atomistic level. In total, 154 posttranslational modifications were identified, 84 of them were in fibrinogen treated with hypochlorite, 51 resulted from a reaction of fibrinogen with malondialdehyde, and 19 were caused by 3-morpholinosydnonimine. Our data reveal that the stronger reagents induce more posttranslational modifications in the fibrinogen structure than the weaker ones, and they extensively alter the architecture of the fibrin network. Molecular dynamics simulations revealed that the effect of posttranslational modifications on fibrinogen secondary structure varies from negligible alternations to serious disruptions. Among the serious disruptions is the oxidation of γR375 resulting in the release of Ca2+ ion that is necessary for appropriate fibrin fiber formation. Folding of amino acids γE72–γN77 into a short α-helix is a result of oxidation of γP76 to glutamic acid. The study describes behaviour of fibrinogen coiled-coil connecter in the vicinity of plasmin and hementin cleavage sites.

Effects of Tomato Juice Intake on Salivary 8-Oxo-dG Levels as Oxidative Stress Biomarker after Extensive Physical Exercise.

Reactive oxygen species (ROS) at a normal level are important molecules involved in several cellular processes including immune response and cell signalling. Overproduction of ROS may lead to elevated oxidative stress and consequently to age-related diseases. Most of the studies related to oxidative stress in humans have been done on blood samples. However, blood sampling might be painful, requires special qualified personnel, and has to be performed at medical centers. An alternative to blood is saliva. Saliva sampling is noninvasive and can be performed by the donor. Biomarker determination in saliva is becoming an important part of laboratory diagnosis, but method development is needed before it can be used in the clinics. In the present investigation, 16 donors performed extensive physical exercise by cycling and keeping their heart rate at 80% of maximum for 20 minutes. The physical activity was repeated 3 times: before tomato juice intake, after daily intake of 100 ml tomato juice during 3 weeks, and finally 3 weeks after finishing tomato juice intake (washout period). The level of the stress biomarker, salivary 8-oxo-dG, was determined before and after the physical activity. The results indicate that (a) 20 min extensive physical activity increases the level of 8-oxo-dG in saliva significantly (p = 0.0078) and (b) daily intake of 100 ml tomato juice may inhibit (p = 0.052) overproduction of salivary 8-oxo-dG by 20 min physical activity. We conclude that the 20 min extensive physical activity increases the level of salivary 8-oxo-dG in healthy donors and 100 ml daily intake of tomato juice may inhibit the increase of 8-oxo-dG in saliva.

Alteration of Metal Elements in Radiation Injury: Radiation-Induced Copper Accumulation Aggravates Intestinal Damage

Ionizing radiation causes damage to a variety of tissues, especially radiation-sensitive tissues, such as the small intestine. Radiation-induced damage is caused primarily by increased oxidative stress in the body. Studies have shown that trace metal elements play an irreplaceable role in oxidative stress in humans, which may be associated with radiation-induced tissue damage. However, the alteration and functional significance of trace metal elements in radiation-induced injury is not clear. In this study, we explored the association between radiation-induced damage and 7 trace metal elements in mouse models. We found that the concentration of zinc and copper in mice serum was decreased significantly after irradiation, whereas that of nickel, manganese, vanadium, cobalt, and stannum was not changed by inductively coupled plasma mass spectrometry. The role of copper in radiation-induced intestines was characterized in detail. The concentration of copper was increased in irradiated intestine but reduced in irradiated heart. Immunohistochemistry staining showed that copper transporter protein copper transport 1 expression was upregulated in irradiated mouse intestine, suggesting its potential involvement in radiation-induced copper accumulation. At the cellular level, the addition of CuCl2 potentiated radiation-induced reactive oxygen species in intestine-derived human intestinal epithelial cell and IEC-6 cells. Moreover, the level of copper in damaged cells may be related to the severity of radiation-induced damage as evidenced by a cell viability assay. These results indicate that copper may be involved in the progression of radiation-induced tissue damage and may be a potential therapeutic target.

Preliminary screening of the possible protective effect of Moroccan propolis against chromium-induced nephrotoxicity in animal model.

Background and Aim:Hexavalent chromium (Cr (VI)) compounds have been shown to induce nephrotoxicity associated with oxidative stress in humans and animals. The aim of the present study was to investigate the nephroprotective effect of bee propolis, as highly antioxidant natural product, in vivo using an animal model.Materials and Methods:First of all, total phenol and flavonoid contents of propolis sample were estimated in vitro. Afterward, to study the protective effect of propolis on renal damages caused by an injection of a single dose of potassium dichromate (15 mg/kg b.wt), 24 male Wister rats were divided into test and control groups. Propolis treatment was performed by oral gavage of 100 mg/kg b.wt/day, while the control groups received water instead. The 24 h urine was collected and blood samples were withdrawn before and after each treatment for further analysis.Results:Propolis revealed to be rich in polyphenols and flavonoids. Chromate provoked a nephrotoxic effect expressed by a drastic decrease in glomerular filtration assessed by creatinine clearance. However, the administration of propolis attenuated the renal damages induced by the chromate. This attenuation can be seen by the increase of creatinine clearance when comparing propolis treated group to the non-treated group.Conclusion:Propolis showed a protective potential against chromate-induced nephrotoxicity through the amelioration of chromate’s toxic effects. It might be concluded that propolis could be effective as chemoprotectant in the management of potassium dichromate-induced nephrotoxicity.

Rapid and reliable HILIC-MS/MS method for monitoring allantoin as a biomarker of oxidative stress

Allantoin is an excellent biomarker of oxidative stress in humans as the main product of uric acid oxidation by reactive oxygen species. Yet, allantoin determination is still not routinely performed in clinical laboratories. Therefore, we developed a fast, simple, selective, and sensitive UHPLC-MS/MS method for allantoin determination in human serum using an isotopically labeled internal standard. Our analytical protocol provided high sensitivity by mass spectrometry detection and high throughput by HILIC-MS/MS analysis within 4 min, with one-step serum sample preparation approximately within 7 min. Lastly, our protocol was fully validated to demonstrate its reliability in allantoin determination in human serum. The method showed an excellent linear range from 0.05 to 100 μM, with precision ranging from 1.8 to 11.3% (RSD), and with accuracy (relative error %) within ±6.0%. The method was then applied to analyze the concentration of allantoin in serum samples from 71 patients with chronic gout without treatment with xanthine oxidase inhibitors. The median serum allantoin concentration in the cohort was 2.8 μM (n = 71). Overall, our simple analytical protocol has the potential to be easily implemented in clinical routine practice for monitoring allantoin as a key oxidative stress biomarker.

Classification of drug molecules for oxidative stress signalling pathway.

In humans, oxidative stress is involved in the development of diabetes, cancer, hypertension, Alzheimers’ disease, and heart failure. One of the mechanisms in the cellular defence against oxidative stress is the activation of the Nrf2‐antioxidant response element (ARE) signalling pathway. Computation of activity, efficacy, and potency score of ARE signalling pathway and to propose a multi‐level prediction scheme for the same is the main aim of the study as it contributes in a big amount to the improvement of oxidative stress in humans. Applying the process of knowledge discovery from data, required knowledge is gathered and then machine learning techniques are applied to propose a multi‐level scheme. The validation of the proposed scheme is done using the K‐fold cross‐validation method and an accuracy of 90% is achieved for prediction of activity score for ARE molecules which determine their power to refine oxidative stress.

Strenuous Exercise Increases the Risk of Oxidative Stress in Ironman Triathlon Participants

Regular physical activity has been linked to greater overall health. Literature review and studies have also defined regular physical activity as a reducer of life-threatening illnesses such as cardiovascular disease, diabetes and obesity. However, long increments of strenuous exercise can produce oxidative stress and muscle fatigue in the human body. The increase in oxygen consumption during strenuous exercise leads to elevated reactive oxygen species (ROS). Cells continuously produce free radicals and reactive oxygen species as part of metabolic processes in the body. These free radicals are neutralized by an antioxidant defense system in the body consisting of enzymes, such as catalase, and non-enzymatic antioxidants. An Ironman Triathlon consists of a 2.4-mile (3.86 km) swim, a 112-mile (180.25 km) bicycle ride and a marathon 26.2-mile (42.2 km) run, raced in that order and without a break. It is widely considered by athletes to be one of the most demanding sporting events in the world. It is hypothesized that a physically challenging event such as the Ironman Triathlon can be linked to elevated cortisol levels, increased occurrence of DNA damage, elevated concentrations of ROS, and consequently increased oxidative stress in humans. In order to derive conclusive results regarding the hypothesis, groups containing athletes who completed the full Ironman race, the half Ironman race, and a control group of moderately active individuals were established and individuals were required to report Garmin Smartwatch health and wellness data. The half Ironman consists of a 1.2-mile (1.93 km) swim, a 56-mile (90.12 km) bicycle ride and a marathon 13.1-mile (21.1 km) run, raced in that order and without a break. Several protocols were then applied to derive data necessary to complete the research. After the participants were selected, their saliva was collected in a non-invasive fashion and was used in the Elisa Saliva Kit to determine cortisol concentration. The saliva samples were also utilized to perform DNA and RNA extraction; and the resulting products were analyzed for quantity and quality of the DNA and RNA. Real time PCR allows scientists to monitor PCR while it is occuring. In this technique, luminescence is produced by reporter molecules as the PCR products increase with every cycle. To determine ROS concentration, the ROS-Glo assay, which provides a light signal that is proportional to the ROS in a given sample, was utilized. An additional marker of oxidative stress is 8-oxo-2-deoxyguanosine(8-oxo-dG). The OxiSelect™ Oxidative DNA Damage ELISA uses antibody and antigen interactions to report the concentration of 8-oxo-dG in a sample. Furthermore, the results indicate an increase in enzymatic indicators of elevated ROS, elevated cortisol levels, and disruption of sleep in the participating athletes after the race. In conclusion, the athletes who completed the full Ironman triathlon experienced increased amounts of oxidative stress than their less active counterparts in the control group, as was denoted by the elevated cortisol levels, increased 8-oxo-dG concentrations, and increased ROS concentrations.Such a rigorous event negatively impacted participants and caused oxidative stress. <strong>Faculty Sponsor</strong>: Noelle Cutter

Antioxidant Activities in vitro of Water and Liposoluble Extracts Obtained by Different Species of Edible Insects and Invertebrates.

A new global interest in entomophagy, the practice of eating insects, and invertebrates, arise from the impellent necessity of preserving agriculture resources and to obtain a drastic reduction of the ecological impact of animal food on the planet. The composite nutritional content, direct consequences of a plant-based feeding, associated with the undoubtedly ecological properties, suggest for insects a role as sustainable and functional foods. We aim to investigate the ability of water and liposoluble extracts, obtained by 12 commercially available edible insects and two invertebrates, to display an antioxidant effect in vitro. Results show that water-soluble extracts of grasshoppers, silkworm, and crickets display the highest values of antioxidant capacity (TEAC), 5-fold higher than fresh orange juice, while evening cicada, giant water bugs, Thai zebra tarantula, and black scorpions have negligible values. Grasshoppers, African caterpillars, and crickets have the highest levels of reducing power (FRAP), double than fresh orange juice. Grasshoppers, black ants, and mealworms contain the highest levels of total polyphenols, while Thai zebra tarantula, black scorpions, and giant water bugs are positioned at the bottom of the ranking. The liposoluble fraction of silkworm, evening cicada, and African caterpillars shows highest level of TEAC, twice than olive oil, while Thai zebra tarantula, palm worm, and black ants are placed at the bottom of the ranking. Edible insects and invertebrates represent a potential source of antioxidant ingredients with an efficiency related to their taxonomy and eating habits. More evidences are needed in order to understand if the practice of eating insects and invertebrates might contribute to modulate oxidative stress in humans.

Evaluation of oxidative stress in cigarette smoking peoples before and after the treatment with vitamin c in Holley Kerbala

The purpose of this study was to estimate some biochemical parameters in smoker peoples before and after the treatment with vitamin C. The study carried out in kerbala province from October 2018 to January 2019. Fifty male volunteers participated in this study, the volunteers was smoked twenty cigarrete daily for twenty years. The blood was drawn from smokers before the treatment and after the treatment (two months) with vitamin c. All chemical analysis is measured by medical chemo analyzer instruments. There was a significant increase in Malondialdehyde ( MDA), Aspartate aminotransferase( AST), Alanine aminotransferase (ALT), Alkaline phosphatase (ALP), Total Bilirubin, urea and creatinine and in smoking peoples as compared to non smoker groups, at the same time there was significant decrease in superoxide dismutase (SOD),catalase (CAT) activities in smoking groups as compared to control group, however after treatment the smokers with vitamin C the biochemical changes return near to normal values. We concluded the Cigar rete has adverse effects on liver and kidney and increase the oxidative stress in humans, vitamin c decrease the oxidative stress in smoker persons due to have the potent antioxidant effect.

Allantoin as a Marker of Oxidative Stress: Inter- and Intraindividual Variability in Urinary Concentrations in Healthy Individuals

Altered systemic oxidative stress is a consequence of environmental exposures and diseases, among other stress factors. The extent of oxidative stress in humans is assessed through the analysis of oxidative stress biomarkers (OSBs) in biospecimens such as urine. Allantoin is an OSB, a specific product of the oxidation of uric acid, that is measurable in urine. In this study, concentrations and inter- and intraindividual variability in urinary concentrations of allantoin were determined in healthy individuals. The results were compared with those found for other OSBs of lipids, proteins, and DNA in the same set of samples. Allantoin was found in all urine samples (N = 515), at concentrations that ranged from 0.88 to 41.7 mmol mol–1 creatinine (0.90 to 112 μg mL–1 urine). The intraclass correlation coefficient (ICC) of urinary allantoin measured in samples collected longitudinally for over a month from 19 individuals (0.74 for creatinine corrected and 0.80 for volumetric concentrations) showed an excellent ...

Guaraná (Paullinia cupana) catechins and procyanidins: Gastrointestinal/colonic bioaccessibility, Caco-2 cell permeability and the impact of macronutrients

Abstract Guarana (Paullinia cupana) seeds are rich in flavan-3-ols (catechins) and reduce oxidative stress in humans. We determined the concentration and in vitro bioaccessibility of catechins in guarana seeds from two geographical origins, and measured their Caco-2 permeability. The effect of macronutrients on catechins’ bioaccessibility and Caco-2 permeability was also evaluated. Guarana seeds from southern Bahia and Maues contained, respectively, 30.0 and 26.8 mg catechin/g, 20.2 and 20.0 mg epicatechin/g, 3.7 and 3.8 mg procyanidin B1/g, and 3.3 and 4.9 mg procyanidin B2/g. Bioaccessibility ranged between 65 and 95% for catechin monomers and 50–140% for dimers. Casein inhibited bioaccessibility of catechin dimers, while vegetable oil improved bioaccessibility of total procyanidins. Guarana catechin monomers and dimers were able to permeate through Caco-2 cell monolayers (Papp 0.31–0.35 × 10−6 cm/s) without effect from co-digested macronutrients. Guarana seeds are a source of highly bioaccessible catechins, which can permeate the intestinal epithelium with negligible effect from macronutrients.

Vitamin B12 in Relation to Oxidative Stress: A Systematic Review.

The triage theory posits that modest micronutrient deficiencies may induce reallocation of nutrients to processes necessary for immediate survival at the expense of long-term health. Neglected processes could in time contribute to the onset of age-related diseases, in which oxidative stress is believed to be a major factor. Vitamin B12 (B12) appears to possess antioxidant properties. This review aims to summarise the potential antioxidant mechanisms of B12 and investigate B12 status in relation to oxidative stress markers. A systematic query-based search of PubMed was performed to identify eligible publications. The potential antioxidant properties of B12 include: (1) direct scavenging of reactive oxygen species (ROS), particularly superoxide; (2) indirect stimulation of ROS scavenging by preservation of glutathione; (3) modulation of cytokine and growth factor production to offer protection from immune response-induced oxidative stress; (4) reduction of homocysteine-induced oxidative stress; and (5) reduction of oxidative stress caused by advanced glycation end products. Some evidence appears to suggest that lower B12 status is related to increased pro-oxidant and decreased antioxidant status, both overall and for subclinically deficient individuals compared to those with normal B12 status. However, there is a lack of randomised controlled trials and prospective studies focusing specifically on the relation between B12 and oxidative stress in humans, resulting in a low strength of evidence. Further work is warranted.

Intake of Oxidized Proteins and Amino Acids and Causative Oxidative Stress and Disease: Recent Scientific Evidences and Hypotheses.

The exposure to reactive oxygen species (ROS) is an inevitable consequence of living in an aerobic world. The species contribute to the occurrence of oxidative stress in humans in which an uncontrolled production of ROS exceeds the endogenous antioxidant defences leading to the oxidative damage to essential cellular components, such as lipids, proteins, and DNA. The influence of diet on the modulation of the systemic redox status is recognized and, while some dietary components are found to be protective (that is, fruits and vegetables), others are recognized as pro-oxidants (that is, processed meat and other animal-source protein foods). Oxidized proteins and amino acids are potential promoters of luminal and postprandial oxidative stress; preliminary studies have actually reported noxious effects of these species in cultured cells and in experimental animals. However, the underlying pathological mechanisms remain poorly understood. The application of advanced methodological approaches based on mass spectrometric technologies and OMICS disciplines has enabled the elucidation of the molecular basis of the pathological effects of dietary oxidized proteins and amino acids. The present review collects the most recent evidences of the health risks of dietary protein oxidation and proposes reasonable hypotheses and future perspectives on the field.

Regulation of functional amino acids on oxidative stress in pigs

Rapid generation of free radical species in the body impairs the antioxidant-oxidative balance, which further causes oxidative stress in humans and animals. In the pig industry, various factors can induce oxidative stress, including birth process, weaning stress, mycotoxin contamination, and feeding environment. Oxidative stress is generally accompanied by other pathologies, which further exerts an important effect on growth performance and healthy status. Currently, various functional amino acids (i.e., sulfur-containing amino acids, glutamic acid, arginine, and tryptophan) are reported to exhibit a potential antioxidant ability. Thus, dietary supplementation with functional amino acids may exert a preventive or therapeutic effect on oxidative stress in pigs. This review mainly discusses the birth-, weaning-, mycotoxins-, and feeding environment-induced oxidative stress and nutritional regulation in pigs, which may provide a reference for the study and scientific application in pig nutrition.

How stable is oxidative stress level? An observational study of intra- and inter-individual variability in urinary oxidative stress biomarkers of DNA, proteins, and lipids in healthy individuals

Oxidative stress in humans is affected by the health and nutritional status as well as exposure to external environmental factors. To evaluate the effects of external factors, an assessment of baseline levels as well as diurnal variations in oxidative stress status of healthy individuals is needed. In this study, we examined intra- and inter-individual variability of oxidative stress biomarkers (OSBs) of lipids (malondialdehyde [MDA] and four F2-isoprostane isomers, namely, 8-isoprostaglandinF2α [8-PGF2α], 11β-prostaglandinF2α [11-PGF2α], 15(R)-prostaglandinF2α [15-PGF2α], and 8-iso,15(R)-prostaglandinF2α [8,15-PGF2α]); proteins (o,o′-dityrosine [diY]); and DNA (8-hydroxy-2′-deoxyguanosine [8-OHdG]) in urine from healthy individuals. The significance of creatinine correction, which is typically used to account for urinary dilution, on OSB concentrations was evaluated. Analysis of 515 urine samples, collected longitudinally from 19 healthy individuals daily for over a month, showed inter-individual coefficient of variation (CV) in concentrations from 112% for MDA to 272% for 15-PGF2α. Intra-individual CV in concentrations ranged from 29% for 8-OHdG to 149% for 15-PGF2α. MDA was the most abundant OSB found in urine. The intra- and inter-individual variability in F2-isoprostane concentrations were higher than the values calculated for diY, 8-OHdG, and MDA. All seven OSB concentrations were significantly correlated with each other and with creatinine. Creatinine normalization of OSB concentrations improved predictability in OSB concentrations over time. Our results suggest that 8-OHdG, showing the highest ICC (0.96), yielded more reproducible measurements with a low CV, and is the most suitable biomarker of OSB in spot urine samples. The measured concentrations and diurnal variability in urinary OSB levels in healthy individuals reported in this study are useful as a benchmark for future toxicological and epidemiological studies.

Heavy metals in human urine, foods and drinking water from an e-waste dismantling area: Identification of exposure sources and metal-induced health risk

Electronic waste or e-waste dismantling activities are known to release metals. However, the human exposure pathways of metals, and their association with oxidative stress in e-waste dismantling areas (EDAs) remain unclear. In this study, our results revealed elevated geometric mean concentrations in vegetables (Cd 0.096 and Pb 0.35 µg/g fw), rice (Cd 0.15, Pb 0.20, and 12.3 µg/g fw), hen eggs (Cd 0.006 and Pb 0.071 µg/g fw), and human urine (Cd 2.12, Pb 4.98, Cu 22.2, and Sb 0.20 ng/mL). Our calculations indicate that rice consumption source accounted for the overwhelming proportion of daily intakes (DIs) of Cd (61–64%), Cu (85–89%), and Zn (75–80%) in children and adults living in EDA; vegetables were the primary contributors to the DIs of Cd (30–32%); and rice (20–29%), vegetables (28–38%), and dust ingestion (26–45%) were all important exposure sources of Pb. Risk assessment predicted that DIs of Cd, Pb, Cu, and Zn via food consumption poses health risks to local residents of EDAs, and the urinary concentrations of analyzed metals were significantly (Pearson correlation coefficient: r = 0.324–0.710; p < 0.01) associated with elevated 8-OHdG, a biomarker of oxidative stress in humans.