Important Source Of Free Radicals Research Articles

Characterization of the cardiorespiratory function and its relationship with oxidative stress in women exposed to wood smoke who live at high altitude (3,850 m a.s.l.)

Objective: To characterize the cardiorespiratory function and the state of oxidative stress resulting from the exposure towood smoke in women who live at high altitude (3,850 m a.s.l.). Materials and methods: An observational case-series study. The cardiorespiratory function was analyzed, and thebiomarkers of oxidative stress malondialdehyde (MDA) and carboxyhemoglobin (COHb) were quantified. Measures of centraltendency and dispersion were determined. The statistical methods of association and correlation were implemented. Results: Sixty (60) patients were included in the research. Fifty percent (50.00 %) of the participants showed clinicalevidence of heart disease and 25.00 % had clinical symptoms of respiratory disease. Forty-five percent (45.00 %) of thespirometries revealed normal values. Thirty-six point six seven percent (36.67 %) showed a decrease in the forced expiratoryvolume in one second (FEV₁), forced expiratory volume in one second/forced vital capacity ratio (FEV₁/FVC) and/or forced expiratory flow 25-75% (FEF25-75). A decrease in FEV₁/FVC, FEF25-75 and FVC occurred in 8.33 %, 3.33 % and 1.67 % ofthe study participants, respectively. Moreover, a 5.00 % decrease was found in more than two parameters. Sixty percent(60.00 %) of the electrocardiograms revealed normal values, 36.67 % presented an intraventricular conduction disorderand 3.33 % showed dextrorotation of the heart. Eighty-one point six seven percent (81.67 %) of the participants presentedan echocardiographic alteration, 73.33% showed valvular insufficiency, 20.00 % presented pulmonary hypertension and6.67 % had an enlarged right ventricle. The mean MDA was 6 µM/L ± 2, which was positively correlated with the age (p: 0.029).The median COHb accounted for 1.00 % (p25: 0.70 – p75: 1.68). No statistically significant association was found between theCOHb concentration and spirometric alterations. A positive correlation was found between MDA values and the right ventriclewall thickness (p: 0.001). Conclusions: The different alterations of the cardiorespiratory function found in the study population show that bothchronic exposure to wood smoke derivatives and hypobaric hypoxia are an important source of free radicals and leadto a permanent and sustained state of oxidative stress, which is responsible for the progressive deterioration of thecardiorespiratory function with no early clinical manifestation.

OP11 - The role of paraoxonase 2 (PON2) in modulating the oxidant-antioxidant balance of the peripheral blood mononuclear cells in newly diagnosed type 2 diabetic patients

Background Obesity is caused by chronic energy discrepancy between energy expenditure and intake. Monocytes by means of their respiratory burst (RB) are an important source of free radicals. The aim of the present study was to investigate the role of paraoxonase 2 (PON2) in the peripheral blood mononuclear cells (PBMNC) in newly diagnosed type 2 diabetic patients (NDT2D). Methods 367 NDT2D were compared regarding clinical, biochemical and oxidative stress parameters with 130 healthy subjects. All subjects were divided according to their body mass index (BMI) into overweight (BMI 25-29.9Kg/m2) and obese (BMI≥30kg/m2). The capacity of the PBMNC to release pro-oxidants and to neutralize them was determined by measuring the RB and the antioxidant enzyme PON2. Serum levels of leptin and adiponectin were determined by ELISA. For frucosamine, glutathione peroxidase (GPx) and superoxide dismutase (SOD) photometric methods were used. Results PON2 activity in PBMNC was significantly lower in NDT2D (p Conclusions The lower PON2 enzymatic activity in PBMNC is partly explained by abdominal obesity and insulin resistance. Up-regulation of monocyte PON2 activity may provide a compensatory protective mechanism against oxidative stress damage in early (prehyperglycaemic) phase of T2D. Acknowledgements This work was supported by a grant of the Romanian National Authority for Scientific Research, CNCS-UEFISCDI, project number PN-II-ID-PCE-2011-3-0429. Dr. Lixandru acknowledges the POSDRU/89/1.5/S/60746, from European Social Fund.

Fish Proteins as Targets of Ferrous-Catalyzed Oxidation: Identification of Protein Carbonyls by Fluorescent Labeling on Two-Dimensional Gels and MALDI-TOF/TOF Mass Spectrometry

Protein oxidation in fish meat is considered to affect negatively the muscle texture. An important source of free radicals taking part in this process is Fenton's reaction dependent on ferrous ions present in the tissue. The aim of this study was to investigate the susceptibility of cod muscle proteins in sarcoplasmic and myofibril fractions to in vitro metal-catalyzed oxidation and to point out protein candidates that might play a major role in the deterioration of fish quality. Extracted control proteins and proteins subjected to free radicals generated by Fe(II)/ascorbate mixture were labeled with fluorescein-5-thiosemicarbazide (FTSC) to tag carbonyl groups and separated by two-dimensional gel electrophoresis. Consecutive visualization of protein carbonyl levels by capturing the FTSC signal and total protein levels by capturing the SyproRuby staining signal allowed us to quantify the relative change in protein carbonyl levels corrected for changes in protein content. Proteins were identified using MALDI-TOF/TOF mass spectrometry and homology-based searches. The results show that freshly extracted cod muscle proteins exhibit a detectable carbonylation background and that the incubation with Fe(II)/ascorbate triggers a further oxidation of both sarcoplasmic and myofibril proteins. Different proteins exhibited various degrees of sensitivity to oxidation processes. Glyceraldehyde 3-phosphate dehydrogenase (GAPDH), nucleoside diphosphate kinase B (NDK), triosephosphate isomerase, phosphoglycerate mutase, lactate dehydrogenase, creatine kinase, and enolase were the sarcoplasmic proteins most vulnerable to ferrous-catalyzed oxidation. Moreover, NDK, phosphoglycerate mutase, and GAPDH were identified in several spots differing by their pI, and those forms showed different susceptibilities to metal-catalyzed oxidation, indicating that post-translational modifications may change the resistance of proteins to oxidative damage. The Fe(II)/ascorbate treatment significantly increased carbonylation of important structural proteins in fish muscle, mainly actin and myosin, and degradation products of those proteins were observed, some of them exhibiting increased carbonylation levels.

Pinealectomy increases oxidant damage in kidney and testis caused by hyperthyroidism in rats

Thyroid hormones regulate energy metabolism and act on mitochondria which are an important source of free radicals in the cell. The pineal gland activates antioxidant systems via melatonin secretion and thus has a protective function in body tissues. The present study was conducted to determine the oxidative damage caused by hyperthyroidism in kidney and testis tissues of pinealectomized rats. Experimental animals were allocated to three groups: 1, control group; 2, sham pinealectomy-hyperthyroidic group; and 3, pinealectomy-hyperthyroidic group. Hyperthyroidism was induced by A 3-week intraperitoneal administration of thyroxin after sham pinealectomy or pinealectomy. Malondialdehyde (MDA) and glutathione (GSH) levels were determined in kidney and testis tissues. MDA levels of the kidney and testis tissue in the pinealectomy and hyperthyroidic groups were significantly higher than those in the sham pinealectomy-hyperthyroidic group and the control group (p < 0.001). GSH levels of both kidney and testis tissues were significantly higher in the sham-pinealectomy-hyperthyroidic group when compared to the other two groups (p < 0.001). This increase in GSH levels was more evident in the pinealectomy-hyperthyroidic group than in the control group (p < 0.001). The results of our study demonstrate that MDA and GSH levels in kidney and testis tissues increased due to hyperthyroidism and that pinealectomy made the increase in MDA levels more apparent, while decreasing GSH levels.

Free radicals in hypoxic rat diaphragm contractility: no role for xanthine oxidase.

Recent evidence indicates that hypoxia enhances the generation of oxidants. Little is known about the role of free radicals in contractility of the rat diaphragm during hypoxia. We hypothesized that antioxidants improve contractility of the hypoxic rat diaphragm and that xanthine oxidase (XO) is an important source of free radicals in the hypoxic diaphragm. The effects of N-acetylcysteine (NAC; 18 mM), Tiron (10 mM), and the XO inhibitor allopurinol (250 microM) were studied on isometric and isotonic force generation during hypoxia (PO(2) approximately 7 kPa). NAC and Tiron decreased maximal force generation, slowed the shortening velocity, and decreased the power output. Fatigue rate was decreased in the presence of either NAC or Tiron. Allopurinol did not alter the contractility or fatigability of the diaphragm. During hyperoxia (PO(2) approximately 85 kPa), neither NAC nor allopurinol affected the contractility or fatigability of the diaphragm. Thus free radicals play a significant role in diaphragm contractility during hypoxia. Whether antioxidants exert a beneficial or harmful effect on muscle performance depends on the contraction pattern of the muscle. Free radicals generated by XO do not play a role in diaphragm contractility during either hypoxia or hyperoxia.

Role of xanthine oxidase in small bowel mucosal dysfunction after surgical stress.

The small intestine is highly susceptible to surgical stress even at remote locations. An earlier study using a rat model indicated that oxidative stress plays an important role in this process. The enzyme xanthine oxidase is an important source of free radicals in the small intestine. The role of this enzyme in intestinal damage after surgical stress was examined. Rats pretreated with xanthine oxidase inhibitors were subjected to surgical stress by opening the abdomen and handling the intestine, as done during laparotomy. Enterocytes at various stages of differentiation were isolated and the protection offered by xanthine oxidase inhibitors against damage due to surgical stress was determined and compared with normal controls. Protection against ultrastructural changes to the mucosa, as well as mitochondrial function was examined. Surgical stress affected both the villus as well as crypt cells, causing increased superoxide generation, accompanied by increased activity of xanthine oxidase. Xanthine oxidase inhibitors ameliorated the increased superoxide generation, and protected against mitochondrial damage and ultrastructural changes in the intestine. Surgical stress affects both the villus and crypt cell populations in the small intestine. The enzyme xanthine oxidase maybe an important mediator of surgical stress in the intestine.

Free Radicals and Glycoxidative Stress in Ageing and Age‐Related Diseases

Abstract. Free radicals and glycoxidative reactions are known to be associated with ageing on the level of the cell and whole organism. Free radicals are ubiquitous in living things and they lead to irreversible reactions in cell organelles and cell metabolism. One important source of free radicals is advanced glycation end products (AGEs) resulting from non‐enzymatic glycation and oxidation of proteins and lipids. Ageing, and thus life span, correlate with free radical generation and antioxidative defense as well as with advanced glycation end products. Most chronic diseases are also associated with free radicals and AGEs. Overproduction of free radicals accelerates cell ageing and is counteracted by antioxidants. Antioxidant status is in part amendable through nutritional and pharmacological interventions. AGE interaction with its receptor contributes also to accelerated ageing in many pathological conditions. Particularly vulnerable are long‐lived proteins, eg. in lens crystallin and skin collagen. The analysis of the mechanism generating free radicals and of the reaction of AGEs with cellular metabolism opens new avenues for the delaying of the development of chronic diseases such as atherosclerosis and neurodegenerative disease. On the other hand, the impact of free radicals on carcinogenesis may differ according to the cancer stage and hence the preventive potential of antioxidants is proposed to be different in early and late stages of cancer development. Free radicals and AGE products are important mediators of age‐related diseases and ageing per se. Intake of antioxidants over the life‐time determines, among other factors, the rate of ageing and the development of degenerative diseases. Interventive strategies such as soluble receptors for AGEs and effective antioxidants might become important therapeutic strategies in the near future.

Xanthine oxidase is not a major source of free radicals in focal cerebral ischemia

Xanthine oxidase (XO) has been proposed as an important source of free radicals during ischemia. This enzyme normally exists as a dehydrogenase (XD), but it is converted to XO in some ischemic tissues. Recently, treatment of animals with the XD and XO inhibitor allopurinol or with free radical scavengers before cerebral ischemia has been shown to reduce brain injury. Therefore, we studied conversion of XD to XO in three ischemic and nonischemic brain regions during focal cerebral ischemia resulting from permanent occlusion of the middle cerebral artery (MCAO) in anesthetized rats. In nonischemic brain, 16-22% of the enzyme was in the XO form. After 24 h of ischemia this value was not significantly different (10-15%). Neither the total activity of XO nor that of XD changed, indicating that there was no irreversible conversion of XD to XO. To further explore the possible role of XO, we examined the effect of various doses of allopurinol (5, 20, or 100 mg/kg given 1 h before MCAO or 100 mg/kg given 48, 24, and 1 h before MCAO) on uric acid accumulation, brain edema formation, and cerebral blood flow (CBF) 24 h after MCAO. All but the lowest dose of allopurinol greatly reduced the appearance of uric acid in the ischemic brain; however, only the highest dose of allopurinol had any beneficial effect on brain edema. This reduction in brain edema occurred without a significant improvement in CBF. Thus XO is probably not an important source of free radicals in this model of focal cerebral ischemia.