Parameters for Measurement of Oxidative Stress in Diabetes Mellitus: Applicability of Enzyme-Linked Immunosorbent Assay for Clinical Evaluation

Roles of Oxidative Injury and Nitric Oxide System Derangements in Kawasaki Disease Pathogenesis: A Systematic Review

Kawasaki disease (KD) is an acute febrile vasculitis that occurs mostly in children younger than five years. KD involves multiple intricately connected inflammatory reactions activated by a cytokine cascade. Despite therapeutic advances, coronary artery damage may develop in some patients, who will be at risk of clinical cardiovascular events and even sudden death. The etiology of KD remains unclear; however, it may involve both genetic and environmental factors leading to aberrant inflammatory responses. Given the young age of onset, prenatal or perinatal exposure may be etiologically relevant. Multisystem inflammatory syndrome in children, a post-infectious hyper-inflammatory disorder associated with severe acute respiratory syndrome coronavirus 2, has features that overlap with those of KD. Available evidence indicates that vascular endothelial dysfunction is a critical step in the sequence of events leading to the development of cardiovascular lesions in KD. Oxidative stress and the dysregulation of the nitric oxide (NO) system contribute to the pathogenesis of inflammatory responses related to this disease. This review provides current evidence and concepts highlighting the adverse effects of oxidative injury and NO system derangements on the initiation and progression of KD and potential therapeutic strategies for cardiovascular pathologies in affected children.

Reactive Oxygen Species and Antioxidative Defense in Chronic Obstructive Pulmonary Disease

The respiratory system is continuously exposed to endogenous and exogenous oxidants. Chronic obstructive pulmonary disease (COPD) is characterized by chronic inflammation of the airways, leading to the destruction of lung parenchyma (emphysema) and declining pulmonary function. It is increasingly obvious that reactive oxygen species (ROS) and reactive nitrogen species (RNS) contribute to the progression and amplification of the inflammatory responses related to this disease. First, we described the association between cigarette smoking, the most representative exogenous oxidant, and COPD and then presented the multiple pathophysiological aspects of ROS and antioxidative defense systems in the development and progression of COPD. Second, the relationship between nitric oxide system (endothelial) dysfunction and oxidative stress has been discussed. Third, we have provided data on the use of these biomarkers in the pathogenetic mechanisms involved in COPD and its progression and presented an overview of oxidative stress biomarkers having clinical applications in respiratory medicine, including those in exhaled breath, as per recent observations. Finally, we explained the findings of recent clinical and experimental studies evaluating the efficacy of antioxidative interventions for COPD. Future breakthroughs in antioxidative therapy may provide a promising therapeutic strategy for the prevention and treatment of COPD.

Autofluorescence as a noninvasive biomarker of senescence and advanced glycation end products in Caenorhabditis elegans

To assess the utility of autofluorescence as a noninvasive biomarker of senescence in Caenorhabditis elegans, we measured the autofluorescence of individual nematodes using spectrofluorometry. The fluorescence of each worm increased with age. Animals with lower fluorescence intensity exhibited longer life expectancy. When proteins extracted from worms were incubated with sugars, the fluorescence intensity and the concentration of advanced glycation end products (AGEs) increased over time. Ribose enhanced these changes not only in vitro but also in vivo. The glycation blocker rifampicin suppressed this rise in fluorescence. High-resolution mass spectrometry revealed that vitellogenins accumulated in old worms, and glycated vitellogenins emitted six-fold higher fluorescence than naive vitellogenins. The increase in fluorescence with ageing originates from glycated substances, and therefore could serve as a useful noninvasive biomarker of AGEs. C. elegans can serve as a new model to look for anti-AGE factors and to study the relationship between AGEs and senescence.

Efficacy of a Methanolic Extract of Adansonia digitata Leaf in Alleviating Hyperglycemia, Hyperlipidemia, and Oxidative Stress of Diabetic Rats

Traditionally, in many countries, various parts of the Adansonia digitata (A. digitata) tree have been used in the treatment of many clinical ailments including diarrhea and dysentery. The phytochemical screening has indicated that the leaf extract of A. digitata contains flavonoids, saponins, mucilage, steroids, and alkaloids. Thus, this paper aims to evaluate the hyperglycaemic and hypolipidaemic effects of methanolic extract of A. digitata leaves (200 mg/kg and 400 mg/kg) in diabetic rats. The extract was administered orally for six weeks in the streptozotocin (STZ)-induced diabetic rats. The treatment with the extract caused a significant reduction in the blood glucose, glycosylated hemoglobin, cholesterol, triglycerides, low-density lipoprotein (LDL), interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-α), and malondialdehyde (MDA) levels by 46.7%, 46.15%, 48.91%, 43%, 60%, 66%, 45.45%, and 30.4%, respectively, as compared to the diabetic group after the sixth week of treatment. The leaf extract also mitigated the decline of high-density lipoprotein (HDL) level, RBCs count, hemoglobin level, packed cell volume (PCV %), and erythropoietin concentration in diabetic rats by 31%, 33.25%, 24.72%, 51.42%, and 220.68% with respect to the diabetic group. Also, the extract maintained the level of antioxidant enzymes, catalase (CAT) and superoxide dismutase (SOD), and reduced glutathione (GSH) in the diabetic rats. It also reduced the elevation in the white blood corpuscles (WBC) count in the STZ-induced diabetic rats. Our study, therefore, indicates that methanolic extract of A. digitata leaf exerts strong antidiabetic and hypolipidaemic properties in a dose-dependent manner by improving the hematological properties and redox parameters in the experimental diabetic rats.

Tissue specific oxidative stress profile in relation to glycaemic regulation in mice

BACKGROUND

Diabetes mellitus is a metabolic disorder characterized by hyperglycaemia resulting from uncontrolled glucose regulation. Reactive oxygen species are recognized as one link between hyperglycaemia and diabetic complications. Studies have shown that diabetes mellitus is associated with decreases in antioxidant potential and increased formation of free radicals leading to oxidative stress. The present study was undertaken because an unequivocal demonstration that control of hyperglycaemia can reduce oxidative stress is still lacking.

METHODS

In the present study, we investigated oxidative stress profile of normal, streptozotocin-induced diabetic, insulin-treated and untreated diabetic animals. On the one hand, oxidative damage caused to lipids, proteins and DNA was measured. On other hand, antioxidant defense was measured in terms of specific activities of antioxidant enzymes (AOEs) and antioxidant molecules.

RESULTS

It was observed that the damage to lipids, proteins and DNA caused by free radicals increased in diabetic animals compared with that in controls. In diabetic animals not treated with insulin, damage to all biological molecules increased further significantly (p ≤ 0.005). Changes in AOEs from different tissues were complex depicting a varied AOE level in different tissues. Insulin treatment significantly improved the oxidative stress profile in all tissues studies.

CONCLUSIONS

The control of hyperglycaemia improves oxidative stress profile, that is, the ability of cells to cope up with oxidative stress.

Oxidative stress, vitamin e, and antioxidant capacity in knee osteoarthritis

BACKGROUND

Osteoarthritis (OA) is a chronic progressive degenerative joint disorder which is characterised by strongly age-related regressive changes in articular cartilage. The objective of this study was to evaluate oxidative stress and antioxidant parameters in plasma and synovial fluid of patients with primary knee osteoarthritis.

MATERIAL AND METHODS

Thirty-five OA patients and 35 healthy controls were recruited for this study. Nitrite, malondialdehyde (MDA), vitamin E, Trolox Equivalent Antioxidant Capacity (TEAC), and Ferric Reducing Antioxidant Power (FRAP) levels in plasma and synovial fluid were determined.

RESULTS

Plasma nitrite levels in OA patients were significantly higher than those in healthy controls (p = 0.037). Furthermore, plasma MDA levels were significantly higher in OA patients than those in healthy controls (p < 0.001). Moreover, plasma vitamin E levels in OA patients were significantly lower than those in healthy controls (p < 0.001). Synovial fluid vitamin E levels of OA patients were significantly lower than paired plasma samples (p < 0.001). The total antioxidant capacities, as were measured by TEAC and FRAP assays in plasma of OA patients, were significantly lower than those in healthy controls (p < 0.01). MDA concentrations were positively correlated with nitrite concentrations but they were negatively associated with vitamin E and TEAC levels in synovial fluid of OA patients.

CONCLUSION

The increased plasma levels of nitrite and MDA and the decreased plasma levels of vitamin E, TEAC, and FRAP indicated that oxidative stress was present in OA patients. These findings suggest that oxidative stress plays a potential role in pathophysiology of knee osteoarthritis.

Profile of oxidant and antioxidant activity in prepubertal children related to age, gender, exercise, and fitness

Tissue damage resulting from oxidative stress induced by a pathological condition might have more serious consequences in children than in adults. Researchers have not yet identified particular markers — alone or in combination with others — of oxidative stress, or their role in pediatric diseases. The aim of this study was to identify gender-based biomarkers for measuring oxidative stress. Oxidative biomarkers were studied in 138 healthy Spanish children (85 boys, 53 girls) 7 to 12 years of age, at the prepubertal (Tanner I) stage, independent of body mass index (BMI), age, fitness (measured by 20-m shuttle run test), and physical activity (measured by participation in an after-school exercise program). The oxidative biomarkers measured were lipid peroxidation products, total nitrites, protein carbonyls, and oxidized glutathione (GSSG). The antioxidant biomarkers measured were total glutathione (TG), reduced glutathione (GSH), superoxide dismutase activity (SOD), and glutathione peroxidase activity. In the study population, height, weight, waist circumference, and BMI were lower in girls than in boys. For oxidative biomarkers, boys had higher levels of protein carbonyl than girls (p < 0.001). In spite of this, girls had higher levels of GSSG (p < 0.001) and TG (p = 0.001), and a lower GSH/GSSG ratio (p < 0.001) than boys. For the antioxidant response, girls had higher levels of SOD (p = 0.002) than boys. All analyses were adjusted for BMI, age, fitness, and physical activity. In conclusion, prepubertal girls had higher oxidative stress than boys, in addition to higher levels of SOD, independent of age, BMI, fitness, and physical activity.

Antihyperlipidaemic and antioxidant effect of the total flavonoids in Selaginella tamariscina (Beauv.) Spring in diabetic mice

Objectives

To investigate the antidiabetic, antihyperlipidaemic and antioxidant activity of total flavonoids in Selaginella tamariscina (Beauv.) Spring (TFST) in a mouse model of diabetes.

Methods

Normal mice, mice fed with a high-fat emulsion diet and streptozotocin (STZ)-induced diabetic mice were treated with TFST for 6 weeks. Serum glucose, insulin and lipid, hepatic steatosis, production of the protein visfatin and antioxidant indices were evaluated.

Key findings

TFST significantly decreased the concentration of fasting blood glucose, total cholesterol, triglycerides and low-density-lipoprotein cholesterol, while it increased the levels of insulin and high-density-lipoprotein cholesterol in diabetic mice. TFST also improved the results of the oral glucose tolerance test to a certain degree. Furthermore, both the free fatty acid levels in the liver and hepatic steatosis were ameliorated by TFST treatment. These changes may be be associated with decreased production of visfatin. Administration of TFST also significantly decreased the levels of malondialdehyde, nitric oxide and inducible nitric oxide synthase and increased the content of glutathione and the activity of superoxide dismutase, catalase, glutathione peroxidase and glutathione-S-transferase in the liver. No change in blood glucose levels were observed in the normal mice treated with TFST.

Conclusions

TFST showed an excellent effect in reducing the high blood glucose level but had no effect on normal blood glucose level. The antidiabetic activity of TFST could be explained by its antioxidant and antihyperlipidaemic activity, which finally elevated the insulin sensitivity of liver.

Diagnostic and Therapeutic Significance of the Oxidative Stress Parameters in Children

Pharmacotherapy of pediatric diseases represents a major challenge considering that the majority of medicines in everyday practice have not been pediatrically evaluated. The efficacy of therapy depends to a large extent on the knowledge of pathophysiological processes in the children organism at different ages. Therefore, research in that direction is of the utmost importance. An imbalance in the production of free oxygen/nitrogen species and parameters of antioxidative protection is a significant factor in many diseases (e.g. heart failure, pulmonary hypertension, asthma, neonatal sepsis, cancer etc.) in children of different age groups. Reactive oxygen/nitrogen species serve as cell signaling molecules for normal biologic processes. An increase in their generation can cause damages which can disrupt normal physiological cellular processes and eventually cause cell death. This review outlines the previous assessments of oxidative stress parameters in children of different ages for some diseases. Also, the potential diagnostic and therapeutic possibilities for the oxydative stress parameters in children have been considered.

Evaluation of a urinary multi-parameter biomarker set for oxidative stress in children, adolescents and young adults

The involvement of reactive oxygen species (ROS) and oxidative stress in pediatric diseases is an important concern, but oxidative stress status in healthy young subjects and appropriate methods for its measurement remain unclear. This study evaluated a comprehensive set of urinary biomarkers for oxidative stress in healthy children, adolescents and young adults. Results show that urinary excretion of acrolein-lysine, 8-hydroxy-2'-deoxyguanosine (8-OHdG), nitrite/nitrate and pentosidine were highest in the youngest subjects and decreased to constant levels by early adolescence. Urinary acrolein-lysine, 8-OHdG, nitrite/nitrate and pentosidine showed significant inverse correlations with age, but pyrraline did not change significantly with age. No significant differences in biomarkers were apparent between males and females. Younger subjects grow rapidly and sustain immune activation, and are probably exposed to high concentrations of ROS and nitric oxide. Consequently, they are more vulnerable to oxidation of lipids, proteins, DNA and carbohydrates. Normal reported values in this study are a basis for future studies of disease mechanisms involving oxidative stress and for future trials using antioxidant therapies for oxidative stress-related diseases in the pediatric field.

RAGE (Receptor for Advanced Glycation Endproducts), RAGE ligands, and their role in cancer and inflammation

The Receptor for Advanced Glycation Endproducts [RAGE] is an evolutionarily recent member of the immunoglobulin super-family, encoded in the Class III region of the major histocompatability complex. RAGE is highly expressed only in the lung at readily measurable levels but increases quickly at sites of inflammation, largely on inflammatory and epithelial cells. It is found either as a membrane-bound or soluble protein that is markedly upregulated by stress in epithelial cells, thereby regulating their metabolism and enhancing their central barrier functionality. Activation and upregulation of RAGE by its ligands leads to enhanced survival. Perpetual signaling through RAGE-induced survival pathways in the setting of limited nutrients or oxygenation results in enhanced autophagy, diminished apoptosis, and (with ATP depletion) necrosis. This results in chronic inflammation and in many instances is the setting in which epithelial malignancies arise. RAGE and its isoforms sit in a pivotal role, regulating metabolism, inflammation, and epithelial survival in the setting of stress. Understanding the molecular structure and function of it and its ligands in the setting of inflammation is critically important in understanding the role of this receptor in tumor biology.

Renal L-type fatty acid--binding protein in acute ischemic injury

Fatty acid-binding proteins (FABPs) bind unsaturated fatty acids and lipid peroxidation products during tissue injury from hypoxia. We evaluated the potential role of L-type FABP (L-FABP) as a biomarker of renal ischemia in both human kidney transplant patients and animal models. Urinary L-FABP levels were measured in the first urine produced from 12 living-related kidney transplant patients immediately after reperfusion of their transplanted organs, and intravital video analysis of peritubular capillary blood flow was performed simultaneously. A significant direct correlation was found between urinary L-FABP level and both peritubular capillary blood flow and the ischemic time of the transplanted kidney (both P < 0.0001), as well as hospital stay (P < 0.05). In human-L-FABP transgenic mice subjected to ischemia-reperfusion injury, immunohistological analyses demonstrated the transition of L-FABP from the cytoplasm of proximal tubular cells to the tubular lumen. In addition, after injury, these transgenic mice demonstrated lower blood urea nitrogen levels and less histological injury than injured wild-type mice, likely due to a reduction of tissue hypoxia. In vitro experiments using a stable cell line of mouse proximal tubule cells transfected with h-L-FABP cDNA showed reduction of oxidative stress during hypoxia compared to untransfected cells. Taken together, these data show that increased urinary L-FABP after ischemic-reperfusion injury may find future use as a biomarker of acute ischemic injury.