Biomedical subjects

F J Kelly

Publications and source records attributed to F J Kelly.

At least 55 records · Page 3Linked to original sources

PubMed1999

Compromised concentrations of ascorbate in fluid lining the respiratory tract in human subjects after exposure to ozone.

OBJECTIVES: Ozone (O3) imposes an oxidative burden on the lung in two ways. Firstly, directly as a consequence of its oxidising character during exposure, and secondly, indirectly by engendering inflammation. In this study the second pathway was considered by ascertaining the impact of O3 on the redox state of the fluid lining the respiratory tract 6 hours after challenge. METHODS: Nine subjects were exposed in a double blind crossover control trial to air and 200 ppb O3 for 2 hours with an intermittent exercise and rest protocol. Blood samples were obtained and lung function (forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1)) assessed before, immediately after, and 6 hours after exposure. Bronchoalveolar lavage (BAL) was performed 6 hours after challenge. Inflammation was assessed in BAL fluid (total and differential cell counts, plus myeloperoxidase concentrations), and plasma and BAL fluid redox state were determined by measuring concentrations of antioxidants and markers of oxidative damage. RESULTS: Neutrophil numbers in BAL fluid increased 2.2-fold (p = 0.07) 6 hours after exposure and this was accompanied by increased myeloperoxidase concentrations in BAL fluid (p = 0.08). On the other hand, BAL fluid macrophage and lymphocyte numbers decreased 2.5-fold (p = 0.08) and 3.1-fold (p = 0.08), respectively at this time. Of the antioxidants examined, only ascorbate in BAL fluid was affected by O3, falling in all subjects relative to air values (0.1 (0.0-0.3) v 0.3 (0.2-1.2) mumol/l (p = 0.008)). A marginal decrease in plasma ascorbate was also detected at this time (p < 0.05). Although the decrease in macrophage numbers seemed to be causally related to the increase in neutrophils (R = -0.79), myeloperoxidase concentrations (R = -0.93) and ascorbate concentrations (R = 0.6), no clear associations were apparent between ascorbate changes and neutrophils or myeloperoxidase concentration after O3. CONCLUSIONS: Ascorbate in the fluid lining the respiratory tract is depleted as a consequence of O3 exposure at 6 hours after exposure. This was contemporaneous with, although not quantitatively related to the increase in neutrophil numbers and myeloperoxidase concentrations. Decreased macrophage numbers 6 hours after O3 related to the degree of neutrophilic inflammation with populations conserved where ascorbate concentration in the fluid lining the respiratory tract were high after exposure. These results imply that ascorbate has a critical protective role against inflammatory oxidative stress induced by O3.

Adult↗

PubMed1999

Modeling the interactions of particulates with epithelial lining fluid antioxidants.

Oxidative stress may be a fundamental mode of injury associated with inspired particles. To examine this, we determined the ability of three carbon black particles (CBPs; M120, M880, and R250) and two forms of silicon dioxide, amorphous (Cabosil) and crystalline (DQ12) quartz, to deplete epithelium lining fluid antioxidant defenses. Single and composite antioxidant solutions of uric acid, ascorbic acid (AA), and reduced glutathione (GSH) were examined in the presence of particle concentrations of 150 microgram/ml. Uric acid was not depleted by any particle considered. AA was depleted in a near-linear fashion with time by the three different CBPs; however, AA depletion rates varied markedly with CBP type and decreased in the presence of metal chelators. An initially high GSH depletion rate was noted with all CBPs, and this was always accompanied by the appearance of oxidized glutathione. Exposure to Cabosil or DQ12 did not result in the loss of GSH. Together, these data demonstrate that particle type, size, and surface area are all important factors when considering particle-antioxidant interactions in the airways.

Air Pollutants↗

PubMed1999

Persistent airway inflammation but accommodated antioxidant and lung function responses after repeated daily exposure to nitrogen dioxide.

Nitrogen dioxide (NO2) is a common indoor and outdoor air pollutant that may induce deterioration of respiratory health. In this study the effects of repeated daily exposure to NO2 on airway antioxidant status, inflammatory cell and mediator responses, and lung function were examined. Healthy nonsmoking subjects were exposed under controlled conditions to air (once) and to 2 ppm of NO2 for 4 h on four consecutive days. Lung function measurements were made before and immediately after the end of each exposure. Bronchoscopy with endobronchial biopsies, bronchial wash (BW), and bronchoalveolar lavage (BAL) was carried out 1.5 h after the air exposure and after the last exposure to NO2. Repeated NO2 exposure resulted in a decrease in neutrophil numbers in the bronchial epithelium. The BW revealed a twofold increase in content of neutrophils (p < 0.05) and a 1.5-fold increase in myeloperoxidase (MPO) (p < 0.01) indicative of both migration and activation of neutrophils in the airways. After the fourth NO2 exposure, antioxidant status of the airway fluid was unchanged. Significant decrements in FEV1 and FVC were found after the first exposure to NO2, but these attenuated with repeated exposures. Together, these data indicate that four sequential exposures to NO2 result in a persistent neutrophilic inflammation in the airways, whereas changes in pulmonary function and airway antioxidants are resolved. We conclude that NO2 is a proinflammatory air pollutant under conditions of repeated exposure.

Adult↗

PubMed1999

Treatment of pulmonary exacerbations of cystic fibrosis leads to improved antioxidant status.

Many cystic fibrosis (CF) patients have increased circulating levels of oxidation products and/or decreased antioxidant status. This study investigated whether treatment of pulmonary exacerbations decreased oxidative stress in CF patients. Seventeen adult patients were studied at the beginning and end of treatment with intravenous antibiotics. Plasma concentrations of the antioxidants ascorbic acid, alpha-tocopherol, uric acid and total reduced thiols, together with plasma retinol, lipid hydroperoxides, malondialdehyde and protein carbonyl levels were determined. Median (interquartile range) pretreatment and post-treatment levels were compared using the Wilcoxon signed rank test. Clinical resolution was reflected by improved spirometry. Significant increases were observed in plasma ascorbic acid (pre 30.4 (15.7-38.6) microM, post 35.2 (27.3-49.6) microM), alpha-tocopherol (pre 19.7 (13.6-25.2) microM, post 25.2 (19.3-31.6) microM) and retinol (pre 1.9 (1.5-2.5) microM, post 2.7 (1.7-3.5) microM). No change in plasma total reduced thiols occurred following treatment (pre 409 (366-420) microM, post 392 (366-423) microM), whereas uric acid fell with treatment (pre 307 (274-394) microM, post 260 (216-317) microM). Neither plasma protein carbonyls or malondialdehyde levels altered with treatment (protein carbonyls pre 0.47 (0.28-1.27), post 0.67 (0.42-0.83) nM x mg protein(-1); malondialdehyde pre 0.75 (0.53-1.18), post 0.84 (0.65-1.15) microM). Lipid hydroperoxides levels did decrease following treatment (53 (18-85) versus 17 (10-55) nM). This study demonstrated that treatment of infective exacerbations resulted in increased plasma levels of some antioxidant vitamins. No immediate change in plasma protein oxidation was observed, but lipid oxidation was decreased.

Adult↗

PubMed1999

Ozone-induced lung function decrements do not correlate with early airway inflammatory or antioxidant responses.

This study sought to clarify the early events occurring within the airways of healthy human subjects performing moderate intermittent exercise following ozone challenge. Thirteen healthy nonsmoking subjects were exposed in a single blinded, crossover control fashion to 0.2 parts per million (ppm) O3 and filtered air for 2 h, using a standard intermittent exercise and rest protocol. Lung function was assessed pre- and immediately post-exposure. Bronchoscopy was performed with endobronchial mucosal biopsies, bronchial wash (BW) and bronchoalveolar lavage (BAL) 1.5 h after the end of the exposure period. Respiratory tract lining fluid (RTLF) redox status was assessed by measuring a range of antioxidants and oxidative damage markers in BW and BAL fluid samples. There was a significant upregulation after O3 exposure in the expression of vascular endothelial P-selectin (p<0.005) and intercellular adhesion molecule-1 (p<0.005). This was associated with a 2-fold increase in submucosal mast cells (p<0.005) in biopsy samples, without evidence of neutrophilic inflammation, and a decrease in BAL fluid macrophage numbers (1.6-fold, p<0.005), with an activation of the remaining macrophage subset (2.5-fold increase in % human leukocyte antigen (HLA)-DR+ cells, p<0.005). In addition, exposure led to a 4.5-fold and 3.1-fold increase of reduced glutathione (GSH) concentrations, in BW and BAL fluid respectively (p<0.05), with alterations in urate and alpha-tocopherol plasma/RTLF partitioning ratios (p<0.05). Spirometry showed reductions in forced vital capacity (p<0.05) and forced expiratory volume in one second (p<0.01), with evidence of small airway narrowing using forced expiratory flow values (p<0.005). Evidence was found of O3-induced early adhesion molecule upregulation, increased submucosal mast cell numbers and alterations to the respiratory tract lining fluid redox status. No clear relationship was demonstrable between changes in these early markers and the lung function decrements observed. The results therefore indicate that the initial lung function decrements are not predictive of, or causally related to the O3-induced inflammatory events in normal human subjects.

Adult↗

PubMed1999

Antioxidant consumption and repletion kinetics in nasal lavage fluid following exposure of healthy human volunteers to ozone.

To obtain information on the real-time events occurring within human respiratory tract lining fluids (RTLFs) during ozone exposure, sequential nasal lavage was performed on 13 human volunteers exposed on separate occasions to 0.2 parts per million O3 and filtered air (2-h exposures, with intermittent exercise). Nasal lavage was performed and blood samples obtained at four time points throughout each exposure: pre-exposure (Pre-E), 1 h into exposure (1h-E), immediately post-exposure (0h-PE) and 1 h post-exposure (1h-PE). Endobronchial mucosal biopsies were obtained at 1.5 h-post exposure (1.5h-PE). Nasal RTLF neutrophilia was not apparent during, or 1.5 h after, 03 exposure. Furthermore, activation of the pre-existing neutrophil population did not occur. Airway permeability was not altered by this 03 exposure regimen. Sequential lavage resulted in significant washout of RTLF ascorbic acid, reduced glutathione, extracellular superoxide dismutase and myeloperoxidase at 1h-E, 0h-PE and 1.5h-PE relative to baseline Pre-E values. In contrast, RTLF uric acid (UA), total protein and albumin concentrations did not display washout kinetics. Of the antioxidants examined, only UA was clearly depleted by 03, concentrations, falling by 6.22 micromol x L(-1) at 1h-E, compared with 1.61 micromol x L(-1) (p<0.01) during control air exposure. The establishment of a new pseudo-steady-state concentration of RTLF UA (70% of Pre-E values) during the second hour of O3 exposure was coincident with a small but significant increase in plasma UA concentration (19.27 (O3) versus 1.95 micromol x L(-1) (air), p<0.05). These data demonstrate that inhalation of 0.2 parts per million 03 results in the depletion of nasal respiratory tract lining fluid uric acid and that this regional loss of uric acid leads to a small increase in plasma uric acid concentration. Whilst the reaction of uric acid with inspired 03 may confer protection locally, the role of upper airway uric acid as a sink for inhaled O3 is not supported by these findings.

Adult↗

PubMed1999

Acute and chronic renal effects of recombinant human TGF-beta2 in the rat.

The expression of transforming growth factor-beta (TGF-beta) correlates with the incidence of renal glomerular and interstitial injury, however, nothing is known of the effect of these proteins on renal hemodynamics. This study examines the renal hemodynamic and morphologic effects of recombinant human TGF-beta2 in normal male Sprague Dawley rats. Acute infusion of TGF-beta (1.2 microg/kg per min) induced no hemodynamic changes, except for a modest though significant fall in mean arterial pressure. Administering TGF-beta2 at varying doses (20, 100, and 400 microg/kg) for 9 wk caused modest increases in systolic BP and proteinuria and minimal tubular interstitial fibrosis, however, renal hemodynamic end points were not significantly altered. TGF-beta2 (800 microg/kg) was also administered to volume-depleted rats for 7 consecutive days. In contrast to the findings in volume-replete animals, administration of TGF-beta2 to volume-depleted rats caused a marked reduction in GFR and medullary blood flow. Histologic fibrosis of the medullary vasa recta and cortical interstitium was seen, but glomeruli were unaffected. Thus, acute and short-term chronic TGF-beta2 administration did not induce major renal changes in the volume-replete state, however, TGF-beta2 combined with volume depletion caused medullary hypoperfusion and reduced GFR.

Analysis of Variance↗

PubMed1999

Oxidative stress in cancer prone genetic diseases: a review.

A number of congenital conditions include oxidative stress as a phenotypic hallmark, in spite of very distinct genotypic assets. These disorders include some rare chromosomal instability syndromes and two frequent congenital conditions, Down's syndrome and cystic fibrosis. All of these disorders generate severe biomedical and social handicaps in their progression, resulting in neurological symptoms or malformations, early ageing and cancer proneness. The onset of oxidative stress has been related to excess formation or defective detoxification of reactive oxygen species. Investigations conducted so far have focussed on individual disorders and have utilised a range of different methodologies, so leading to a number of unanswered questions regarding the role(s) for oxidative stress in these disorders. Comparative studies are required, based on homogeneous methods, to provide insights into the pathogenesis of each individual condition, which may open up new avenues for studying ageing and cancer.

Chromosome Aberrations↗

PubMed1998

Developmental differences in superoxide production in isolated guinea-pig hearts during reperfusion.

The production of free radicals on reperfusion has been implicated as an important factor governing post-ischemic recovery of cardiac function. Although the response of the heart to ischemia and reperfusion is known to change during cardiac development, it is not known if different rates of free radical production play a role in these altered responses. The aim of this investigation was to determine if the production of the superoxide anion (O2-) on reperfusion differs in the immature and mature heart. Immature hearts, obtained from 3-day premature guinea pigs (delivered by cesarean section) were compared with those from adults (7 weeks old). Using the isolated Langendorff preparation. O2- production was measured during reperfusion following ischemic durations [0 (aerobic control), 15, 20, 30, and 60 min, n = 6/group] by the reduction of succinylated ferricytochrome c in the perfusate. Both immature and mature hearts exhibited bell-shaped relationship between ischemic duration and peak O2- production on reperfusion: (13.4 +/- 5.9; 22.2 +/- 5.4; 23.0 +/- 7.8; 59.3 +/- 16.2; 33.7 +/- 15.1; 32.6 +/- 8.5 nmol/min/g wet weight in the immature heart and 15.7 +/- 1.9; 55.0 +/- 30.2; 82.8 +/- 14.0; 78.8 +/- 33.8; 40.6 +/- 16.4; 45.4 +/- 13.1 nmol/min/g wet weight in the mature heart after 0; 15; 20; 30; 45 and 60 min of ischemia, respectively). A similar relationship was also demonstrated with O2- production over the 20-min reperfusion period: (134.0 +/- 57.1; 106.5 +/- 46.2; 199.3 +/- 50.6; 362.0 +/- 99.5; 375.0 +/- 60.9; 221.0 +/- 73.0 nmol/20 min/g wet weight in the immature heart and 97.8 +/- 54; 282.0 +/- 139.0; 933.3 +/- 210.3; 964.0 +/- 374.0; 443.0 +/- 106.0; 352.0 +/- 1551.0 nmol/20 min/g wet weight in the mature heart after 0, 15, 20, 30, 45 and 60 min of ischemia, respectively). Mature hearts consistently produced more O2- than immature hearts on reperfusion, while there was no significant difference in their capacity to produce O2- during aerobic perfusion. We conclude that the immature heart may be at less risk from the free radical component of reperfusion injury than the mature heart.

Age Factors↗

PubMed1998

Modeling the interactions of ozone with pulmonary epithelial lining fluid antioxidants.

Water soluble antioxidant--ascorbate (AA), urate (UA), and reduced glutathione (GSH)--consumption by ozone (O3) was investigated in a range of pulmonary epithelial lining fluid (ELF) models. Antioxidants were exposed individually and as a composite mixture, with and without human albumin to a range of ambient O3 concentrations: 0-1500 ppb using a continually mixed, interfacial exposure setup. We observed the following: (1) UA constituted the most o3-reactive substrate in each of the models examined. Reactivity hierarchies in each were as follows: UA > AA >> GSH (individual antioxidant), UA > AA > GSH (composite antioxidant), and UA >> AA approximately equal to GSH (composite antioxidant + albumin). Consumption of GSH as a pure antioxidant solution was associated with a 2:1 stoichiometric conversion of GSH to GSSG. This simplistic relationship was lost in the more complex models. (3) Consumption of antioxidants by O3 occurred without alteration of sample pH. (4) Protein carbonyl formation was observed when albumin alone was exposed to O3. However, in the presence of the composite antioxidant solution no evidence of this oxidative modification was apparent. These data indicate that GSH does not represent an important substrate for O3. In contrast, UA displays high reactivity consistent with its acting as a sacrificial substrate in the ELF. As UA concentrations are highest in the ELF of the proximal airways, its localization, allied to its reactivity, suggesting that it plays important roles, both in conferring protection locally and also by "scrubbing" O3, from inhaled air, limiting its penetration to the more sensitive distal lung.

Antioxidants↗

PubMed1998

Congenital disorders sharing oxidative stress and cancer proneness as phenotypic hallmarks: prospects for joint research in pharmacology.

In spite of very distinct genotypic assets, a number of congenital conditions include oxidative stress as a phenotypic hallmark. These disorders include Fanconi's anaemia, ataxia telangiectasia, xeroderma pigmentosum and Bloom's syndrome, as well as two frequent congenital conditions: Down's syndrome and cystic fibrosis. Cancer proneness is a clinical feature shared by these disorders, while other manifestations include early ageing, neurological symptoms or congenital malformations. The onset of oxidative stress has been related to excess formation, or defective detoxification, of reactive oxygen species (ROS). This can arise from either the abnormal expression or inducibility of ROS-detoxifying enzymes, or by defective absorption of nutrient antioxidants. Resulting oxidative injury has been characterized through: (i) DNA, protein or lipid oxidative damage; (ii) excess ROS formation (in vitro and ex vivo); (iii) sensitivity to oxygen-related toxicity; (iv) improvement of cellular defects by either hypoxia or antioxidants; and (v) circumstantial evidence for in vivo oxidative stress (as e.g. clastogenic factors). Investigations conducted so far have been confined to individual disorders. Comparative studies of selected indicators for oxidative stress could provide further insights into the pathogenesis of each individual condition. Such a unified approach may have wide-ranging consequences for studies of ageing and cancer.

Aging↗

PubMed1998

Hypothermic preservation of isolated rat lungs in modified bicarbonate buffer, EuroCollins solution or St Thomas' Hospital cardioplegic solution.

OBJECTIVES: Inadequate preservation solutions limit lung storage times and, consequently, transplant programs. To address this problem we established an isolated, ventilated and perfused rat lung preparation. Here we report the effects of hypothermic storage in EuroCollins solution, St Thomas' Hospital cardioplegic solution and a modified bicarbonate buffer solution. METHODS: Lungs from male Wistar rats (230-330 g) were perfused via the pulmonary artery with modified bicarbonate buffer (37 degrees C, 15 ml/min, constant flow) and ventilated by positive pressure (tidal volume:1.6-1.8 ml, 80 breaths/min). Vascular resistance (pulmonary artery pressure:perfusate flow ratio) and airways compliance (tidal volume:tracheal pressure ratio) were measured. After a control perfusion period (20 min), lungs were flushed with, then immersed in, bicarbonate buffer (4 degrees C) for varying periods (0-24 h). After storage, lung function was assessed during 20 min reperfusion. Having established a suitable period for study, storage in EuroCollins, St Thomas' Hospital cardioplegic solution or bicarbonate buffer were compared. RESULTS: Pulmonary compliance (ml/cmH2O) was significantly (P < 0.05) reduced in lungs stored for 6 h in modified bicarbonate buffer (0.026 +/- 0.008), EuroCollins solution (0.013 +/- 0.002) or St Thomas' Hospital solution (0.025 +/- 0.005) compared to unstored lungs (0.068 +/- 0.007). Vascular resistance, (1.32 +/- 0.13 cmH2O/ml per min) in unstored lungs, was similar in lungs stored in St Thomas' Hospital solution but increased significantly in lungs stored in modified bicarbonate buffer (3.22 +/- 0.78 cmH2O/ml per min) or EuroCollins solution (4.66 +/- 0.57 cmH2O/ml per min). CONCLUSIONS: Hypothermic storage of rat lungs for 6 h in modified bicarbonate buffer or St Thomas' Hospital solution causes less increase in vascular resistance on reperfusion than EuroCollins solution.

Animals↗

PubMed1998

Antioxidant defenses in lung lining fluid of broilers: impact of poor ventilation conditions.

Lung lining fluid antioxidants represent a potentially important protective barrier of lung epithelial cells to damaging effects of air pollutants, yet no information is apparently available concerning lung lining fluid antioxidants in broilers. Therefore, goals of this study were to establish uric acid, ascorbic acid, reduced (GSH) and oxidized (GSSG) glutathione, and protein concentrations in lung lining fluid obtained from male broiler chickens maintained for 6 to 7 wk within environmentally controlled rooms (Control) or chronically exposed to high levels of dust and ammonia within a broiler rearing house (House). The entire respiratory tract was carefully removed following an overdose of anesthetic and lavage fluid was collected after flushing the lungs with heparin-saline (10 mL per lung). There was no difference in GSH, but GSSG, uric acid, and protein concentrations were higher in House birds than in Controls. An increase in the GSSG to total glutathione (GSx) ratio, an indicator of oxidative stress, was also observed in birds maintained in the House environment. Ascorbic acid was not detected in House-reared birds and detected in only 4 of 12 Controls. Regression analysis revealed positive correlations between lung lining fluid protein and uric acid (r = 0.71; P < 0.01), protein and GSSG (r = 0.73; P < 0.01), and uric acid and GSSG concentrations (r = 0.69, P < 0.01). Additionally, GSSG was positively correlated (r = 0.66; P < 0.01) with the right ventricular weight ratio, an index commonly used in identifying the development of pulmonary hypertension syndrome in broilers. These data, the first to document lung lining fluid antioxidants in avian species, indicate an oxidative stress can be detected in fluid of broilers exposed to high levels of dust and ammonia in a simulated poultry house environment.

Animals↗

PubMed1998

Effects of 0.2 ppm ozone on biomarkers of inflammation in bronchoalveolar lavage fluid and bronchial mucosa of healthy subjects.

Short-term exposure to ozone at peak ambient levels induces neutrophil influx and impairs lung function in healthy humans. In order to investigate the mechanisms contributing to neutrophil recruitment and to examine the role of T-cells in the acute inflammatory response, we exposed 12 healthy humans to 0.2 parts per million (ppm) of ozone and filtered air on two separate occasions for 2 h with intermittent periods of rest and exercise (minute ventilation = 30 L x min(-1)). Fibreoptic bronchoscopy was performed 6 h after the end of exposures. Total protein, tryptase, histamine, myeloperoxidase, interleukin (IL)-8 and growth-related oncogene-alpha (Gro-alpha) were measured and total and differential cell counts were performed in bronchoalveolar lavage (BAL) fluid. Flow cytometry was performed on BAL cells to study total T-cells, T-cell receptors (alphabeta and gammadelta), T-cell subsets (CD4+ and CD8+ cells) and activated T-cell subsets (CD25+). Using immunohistochemistry, neutrophils, mast cells, total T-cell numbers, T-cell subsets, CD25+ T-cells and leukocyte endothelial adhesion molecules including P-selectin, E-selectin, intercellular adhesion molecule (ICAM)-1 and vascular adhesion molecule (VCAM)-1 were quantified in the bronchial biopsies. Paired samples were available from nine subjects. Following ozone exposure there was a threefold increase in the proportion of polymorphonuclear neutrophils (PMNs) (p=0.07) and epithelial cells (p=0.05) in BAL fluid. This was accompanied by increased concentrations of IL-8 (p=0.01), Gro-alpha (p=0.05) and total protein (p=0.058). A significant positive correlation was demonstrated between the two chemokines and proportion of PMNs in BAL fluid. After ozone exposure there was a significant decrease in the CD4/CD8 ratio (p=0.05) and the proportion of activated CD4+ (p=0.01) and CD8+ T-cells (p=0.04). However, no significant changes were demonstrable in any of the inflammatory markers studied in the biopsies. Short-term exposure of healthy humans to 0.2 ppm ozone induced a neutrophil influx in peripheral airways at 6 h post exposure, but no apparent inflammatory response in proximal airways. This response seems to be mediated at least in part by interleukin-8 and growth-related oncogene-alpha.

Adult↗

PubMed1998

Bronchiolitis obliterans syndrome in lung transplant recipients is associated with increased neutrophil activity and decreased antioxidant status in the lung.

Long-term survival of lung transplant recipients is limited by the advent of obliterative bronchiolitis and irreversible airways obstruction, e.g. bronchiolitis obliterans syndrome (BOS). This study investigated whether inflammatory cells and their activation markers were increased in bronchoalveolar lavage (BAL) and transbronchial biopsies (TBB) from patients with BOS. Levels of antioxidants in BAL fluid were also assessed. BAL fluid and TBB from six single-lung, two bilateral-lung, and five heart-lung transplanted patients with diagnosis of BOS were compared with 13 transplant recipients without BOS. BAL fluid levels of myeloperoxidase (MPO), eosinophil cationic protein (ECP) and interleukin (IL)-8 were used as markers for the activation and attraction of neutrophils and eosinophils, respectively. Immunohistochemical staining of TBB with monoclonal antibodies to MPO and ECP (EG2) was performed. Significantly increased BAL percentages of neutrophils and levels of MPO were found in patients with BOS. The findings correlated well with the degree of monoclonal staining for MPO in TBB. BAL levels of ECP and IL-8 were significantly increased in BOS patients. BAL concentrations of the water-soluble antioxidants ascorbate, urate and glutathione were generally lower in BOS patients. The results indicate that neutrophil infiltration and activation, as well as oxidative stress, may play a role in the development and/or progression of bronchiolitis obliterans syndrome. Markers for neutrophil activation could have a potential role in monitoring disease activity in patients with this syndrome.

Adolescent↗

PubMed1998

Nasal cavity lining fluid ascorbic acid concentration increases in healthy human volunteers following short term exposure to diesel exhaust.

To determine if diesel exhaust (DE) exposure modifies the antioxidant defense network within the respiratory tract lining fluids, a randomized, single blinded, crossover control study using nasal lavage and flexible video bronchoscopy with bronchial and bronchoalveolar lavage was performed. Fifteen healthy, non-smoking, asymptomatic subjects were exposed to filtered air or diluted diesel exhaust (300mg m(-3) particulates, 1.6ppm nitrogen dioxide) for one hour on 2 separate occasions, at least three weeks apart. To examine the kinetics of any DE-induced antioxidant reactions, nasal lavage fluid and blood samples were collected prior to, immediately after, and 5 1/2 hours post exposure. Bronchoscopy was performed 6 hours after the end of DE exposure. Ascorbic acid, uric acid and reduced glutathione (GSH) concentrations were determined in nasal, bronchial, bronchoalveolar lavage and plasma samples. Malondialdehyde (MDA) and protein carbonyl concentrations were determined in plasma and bronchoalveolar lavage samples. Nasal lavage ascorbic acid concentration increased 10-fold during DE exposure [1.02 (0.26-2.09) Vs 7.13 (4.66-10.79) micromol/L(-1)], but returned to basal levels 5.5 hours post-exposure [0.75 (0.26-1.51) micromol/L(-1)]. There was no significant effect of DE exposure on nasal lavage uric acid or GSH concentration. DE exposure did not influence plasma, bronchial wash, or bronchoalveolar lavage antioxidant concentrations and no change in MDA or protein carbonyl concentrations were found. The physiological response to acute DE exposure is an increase in the level of ascorbic acid in the nasal cavity. This response appears to be sufficient to prevent further oxidant stress in the respiratory tract of normal individuals.

Adult↗

PubMed1998

Use of antioxidants in the prevention and treatment of disease.

Considerable interest has risen in the idea that oxidative stress is instrumental in the etiology of numerous human diseases. Oxidative stress can arise through the increased production of reactive oxygen species (ROS) and/or because of a deficiency of antioxidant defenses. Antioxidant deficiencies can develop as a result of decreased antioxidant intake (such as vitamins C and E), synthesis of enzymes (such as superoxide dismutase and glutathione peroxidase) or increased antioxidant utilization. Insufficient antioxidant enzyme synthesis may in turn be due to decreased micronutrient availability (such as selenium, magnese, copper and zinc). Of those diseases linked with oxidative stress, cardiovascular disease provides the strongest evidence for the protective role of antioxidants. A high consumption of fruit and vegetables, which are good sources of antioxidants, is associated with a lower coronary risk. More specifically, there is evidence of a reduced coronary risk in populations with high blood levels of the antioxidant nutrients, vitamins C and E. Evidence is also accumulating that diabetes, and microvascular complications associated with diabetes, involve oxidative stress and have compromised antioxidant status. In addition, patients who develop acute respiratory distress syndrome (ARDS) also exhibit clear evidence of oxidative stress. Definitive proof for active oxygen formation and oxidative cell damage being causative rather than a result of other underlying these pathologies remains elusive; however, evidence is sufficiently compelling to suggest that antioxidants are potential therapeutic agents in the above conditions.

Antioxidants↗

PubMed1997

Nitrogen dioxide depletes uric acid and ascorbic acid but not glutathione from lung lining fluid.

The aim of this study was to determine the kinetics of the reactions between the gaseous free-radical pollutant, nitrogen dioxide (NO2), and the water-soluble antioxidants present in respiratory tract lining fluid (RTLF). Samples of RTLF, recovered from 12 subjects (mean age 54.1+/-16.3 years; eight male, four female) as bronchoalveolar lavage (BAL) fluid were exposed ex vivo to NO2 [50-1000 parts per billion (ppb)] for 4 h. For comparison, similar exposures were carried out with single and composite solutions with relevant RTLF antioxidant concentrations. Ascorbic acid (AA), uric acid (UA), GSH depletion, and GSSG and malondialdehyde (MDA) formation were determined with time. In the three models, UA and AA were consumed in a time- and NO2-concentration-related fashion. In addition, their rate of depletion correlated positively with their initial concentration (UA, r=0.92, P<0.05; AA, r=0.94, P<0.05). Little difference was found between the rate of loss of AA (2.2+/-0. 2; 1.9+/-0.5; 1.4+/-0.3 nmol.l-1.h-1.ppb-1), and that of UA (2.4+/-0. 2; 2.1+/-0.6; 1.3+/-0.2 nmol.l-1.h-1.ppb-1) in the three RTLF models examined (single, composite, BAL fluid respectively). GSH loss from BAL fluid (0.2+/-0.1) was significantly less than that seen in either single (1.4+/-0.3) or composite (1.2+/-0.5 nmol.l-1.h-1. ppb-1) antioxidant solutions. In all cases, GSH consumption was significantly less than AA or UA. As model complexity increased, the rate of individual antioxidant loss decreased, such that in BAL fluid, AA, UA and GSH consumption rates were significantly less (P<0. 05) than in the pure or composite antioxidant mixtures. In BAL fluid, little GSSG production was observed at any NO2 concentration. MDA concentration, determined as a measure of lipid peroxidation, did not change following exposure to 50, 150 or 400 ppb NO2, but increased MDA was seen in BAL fluid from 8/12 subjects following exposure to 1000 ppb NO2 for 1 h or more. In conclusion, NO2, at environmentally relevant concentrations, depletes BAL fluid of the antioxidant defences, UA and AA, but not GSH.

Antioxidants↗