Neutrophil tolerance to oxidative stress induced by hypoxia/reoxygenation

Assessment of metabolomic variations among individuals returning to plain areas after exposure to high altitudes: a metabolomic analysis of human plasma samples with high-altitude de-acclimatization syndrome

Background

High altitude de-acclimatization (HADA) is gradually becoming a public health concern as millions of individuals of different occupations migrate to high-altitude areas for work due to economic growth in plateau areas. HADA affects people who return to lower elevations after exposure to high altitudes. It causes significant physiological and functional changes that can negatively impact health and even endanger life. However, uncertainties persist about the detailed mechanisms underlying HADA.

Methods

We established a population cohort of individuals with HADA and assessed variations in metabolite composition. Plasm samples of four groups, including subjects staying at plain (P) and high altitude (H) as well as subjects suffering from HADA syndrome with almost no reaction (r3) and mild-to-moderate reaction (R3) after returning to plain from high altitude, were collected and analyzed by Liquid Chromatography-Mass Spectrometry metabolomic. Multivariate statistical analyses were used to explore significant differences and potential clinical prospect of metabolites.

Result

Although significantly different on current HADAS diagnostic symptom score, there were no differences in 17 usual clinical indices between r3 and R3. Further multivariate analyses showed isolated clustering distribution of the metabolites among the four groups, suggesting significant differences in their metabolic characteristics. Through K-means clustering analysis, we identified 235 metabolites that exhibited patterns of abundance change consistent with phenotype of HADA syndrome. Pathway enrichment analysis indicated a high influence of polyunsaturated fatty acids under high-altitude conditions. We compared the metabolites between R3 and r3 and found 107 metabolites with differential abundance involved in lipid metabolism and oxidation, suggesting their potential role in the regulation of oxidative stress homeostasis. Among them, four metabolites might play a key role in the occurrence of HADA, including 11-beta-hydroxyandrosterone-3-glucuronide, 5-methoxyindoleacetate, 9,10-epoxyoctadecenoic acid, and PysoPC (20:5).

Conclusion

We observed the dynamic variation in the metabolic process of HADA. Levels of four metabolites, which might be provoking HADA mediated through lipid metabolism and oxidation, were expected to be explore prospective indices for HADA. Additionally, metabolomics was more efficient in identifying environmental risk factors than clinical examination when dramatic metabolic disturbances underlying the difference in symptoms were detected, providing new insights into the molecular mechanisms of HADAS.

Oxy-Inflammation in Humans during Underwater Activities

Underwater activities are characterized by an imbalance between reactive oxygen/nitrogen species (RONS) and antioxidant mechanisms, which can be associated with an inflammatory response, depending on O2 availability. This review explores the oxidative stress mechanisms and related inflammation status (Oxy-Inflammation) in underwater activities such as breath-hold (BH) diving, Self-Contained Underwater Breathing Apparatus (SCUBA) and Closed-Circuit Rebreather (CCR) diving, and saturation diving. Divers are exposed to hypoxic and hyperoxic conditions, amplified by environmental conditions, hyperbaric pressure, cold water, different types of breathing gases, and air/non-air mixtures. The "diving response", including physiological adaptation, cardiovascular stress, increased arterial blood pressure, peripheral vasoconstriction, altered blood gas values, and risk of bubble formation during decompression, are reported.

Cerebral, cardiac and skeletal muscle stress associated with a series of static and dynamic apnoeas

PURPOSE

This study sought to explore, for the first time, the effects of repeated maximal static and dynamic apnoeic attempts on the physiological milieu by assessing cerebral, cardiac and striatal muscle stress-related biomarkers in a group of elite breath-hold divers (EBHD).

METHODS

Sixteen healthy males were recruited (EBHD = 8; controls = 8). On two separate occasions, EBHD performed two sets of five repeated maximal static apnoeas (STA) or five repeated maximal dynamic apnoeas (DYN). Controls performed a static eupnoeic protocol to negate any effects of water immersion and diurnal variation on haematology (CTL). Venous blood samples were drawn at 30, 90, and 180 min after each protocol to determine S100β, neuron-specific enolase (NSE), myoglobin, and high sensitivity cardiac troponin T (hscTNT) concentrations.

RESULTS

S100β and myoglobin concentrations were elevated following both apnoeic interventions (p < 0.001; p ≤ 0.028, respectively) but not after CTL (p ≥ 0.348). S100β increased from baseline (0.024 ± 0.005 µg/L) at 30 (STA, +149%, p < 0.001; DYN, +166%, p < 0.001) and 90 min (STA, +129%, p < 0.001; DYN, +132%, p = 0.008) following the last apnoeic repetition. Myoglobin was higher than baseline (22.3 ± 2.7 ng/ml) at 30 (+42%, p = 0.04), 90 (+64%, p < 0.001) and 180 min (+49%, p = 0.013) post-STA and at 90 min (+63%, p = 0.016) post-DYN. Post-apnoeic S100β and myoglobin concentrations were higher than CTL (STA, p < 0.001; DYN, p ≤ 0.004). NSE and hscTNT did not change from basal concentrations after the apnoeic (p ≥ 0.146) nor following the eupnoeic (p ≥ 0.553) intervention.

CONCLUSIONS

This study suggests that a series of repeated maximal static and dynamic apnoeas transiently disrupt the blood-brain barrier and instigate muscle injury but do not induce neuronal-parenchymal damage or myocardial damage.

Innate Neutrophil Memory Dynamics in Disease Pathogenesis

Neutrophils, the most abundant leukocytes in circulation and the first responders to infection and inflammation, closely modulate both acute and chronic inflammatory processes. Resting neutrophils constantly patrol vasculature and migrate to tissues when challenges occur. When infection and/or inflammation recede, tissue neutrophils will be subsequently cleaned up by macrophages which collectively contribute to the resolution of inflammation. While most studies focus on the anti-microbial function of neutrophils including phagocytosis, degranulation, and neutrophil extracellular traps (NETs) formation, recent research highlighted additional contributions of neutrophils beyond simply controlling infectious agents. Neutrophils with resolving characteristics may alter the activities of neighboring cells and facilitate inflammation resolution, modulate long-term macrophage and adaptive immune responses, therefore having important impacts on host pathophysiology. The focus of this chapter is to provide an updated assessment of recent progress in the emerging field of neutrophil programming and memory in the context of both acute and chronic diseases.

Physiology, pathophysiology and (mal)adaptations to chronic apnoeic training: a state-of-the-art review

Breath-hold diving is an activity that humans have engaged in since antiquity to forage for resources, provide sustenance and to support military campaigns. In modern times, breath-hold diving continues to gain popularity and recognition as both a competitive and recreational sport. The continued progression of world records is somewhat remarkable, particularly given the extreme hypoxaemic and hypercapnic conditions, and hydrostatic pressures these athletes endure. However, there is abundant literature to suggest a large inter-individual variation in the apnoeic capabilities that is thus far not fully understood. In this review, we explore developments in apnoea physiology and delineate the traits and mechanisms that potentially underpin this variation. In addition, we sought to highlight the physiological (mal)adaptations associated with consistent breath-hold training. Breath-hold divers (BHDs) are evidenced to exhibit a more pronounced diving-response than non-divers, while elite BHDs (EBHDs) also display beneficial adaptations in both blood and skeletal muscle. Importantly, these physiological characteristics are documented to be primarily influenced by training-induced stimuli. BHDs are exposed to unique physiological and environmental stressors, and as such possess an ability to withstand acute cerebrovascular and neuronal strains. Whether these characteristics are also a result of training-induced adaptations or genetic predisposition is less certain. Although the long-term effects of regular breath-hold diving activity are yet to be holistically established, preliminary evidence has posed considerations for cognitive, neurological, renal and bone health in BHDs. These areas should be explored further in longitudinal studies to more confidently ascertain the long-term health implications of extreme breath-holding activity.

Six weeks of dynamic apnoeic training stimulates erythropoiesis but does not increase splenic volume

Purpose

This study examined the influence of dynamic apnoea training on splenic volume and haematological responses in non-breath-hold divers (BHD).

Methods

Eight non-BHD performed ten maximal dynamic apnoeas, four times a week for  six weeks. Splenic volumes were assessed ultrasonically, and blood samples were drawn for full blood count analysis, erythropoietin, iron, ferritin, albumin, protein and osmolality at baseline, 24 h post the completion of each week’s training sessions and seven days post the completion of the training programme. Additionally, blood samples were drawn for haematology at 30, 90, and 180 min post session one, twelve and twenty-four.

Results

Erythropoietin was only higher than baseline (6.62 ± 3.03 mlU/mL) post session one, at 90 (9.20 ± 1.88 mlU/mL, p = 0.048) and 180 min (9.04 ± 2.35 mlU/mL, p = 0.046). Iron increased from baseline (18 ± 3 µmol/L) post week five (23 ± 2 µmol/L, p = 0.033) and six (21 ± 6 µmol/L; p = 0.041), whereas ferritin was observed to be lower than baseline (111 ± 82 µg/L) post week five (95 ± 75 µg/L; p = 0.016), six (84 ± 74 µg/L; p = 0.012) and one week post-training (81 ± 63 µg/L; p = 0.008). Reticulocytes increased from baseline (57 ± 12 × 10⁹/L) post week one (72 ± 17 × 10⁹/L, p = 0.037) and six (71 ± 17 × 10⁹/L, p = 0.021) while no changes were recorded in erythrocytes (p = 0.336), haemoglobin (p = 0.124) and splenic volumes (p = 0.357).

Conclusions

Six weeks of dynamic apnoeic training increase reticulocytes without altering mature erythrocyte concentration and splenic volume.

Hematologic changes after short term hypoxia in non-elite apnea divers under voluntary dry apnea conditions

Purpose

This study investigated the acute changes in full spectrum differential blood cell count including reticulocytes and immature reticulocytes after a voluntary maximal dry apnea in non-elite divers. Aim of the present study is to obtain information on important regulatory compensation mechanisms and to provide insights into apneic regulatory processes.

Methods

Ten apnea divers performed a voluntary dry mean apnea time of 317 sec [SD ±111 sec]. Differential blood cell count including reticulocytes was measured before and immediately after a single maximal breath-hold. To evaluate kinetics, blood samples were also taken after 30 min and 4 h. Value distributions are presented with dot plots. P-values were calculated using a mixed linear model for time dependency. Four difference values were compared to baseline values with Dunnett’s procedure.

Results

Significant changes were found in red blood cell parameters for erythrocytes, red cell distribution width, hematocrit, hemoglobin, MCV, reticulocytes and immature reticulocytes, and in white blood cell parameters for leucocytes, lymphocytes, immature granulocytes, monocytes, basophile granulocytes, neutrophil granulocytes and eosinophil granulocytes and for thrombocytes.

Conclusion

Adaptive mechanisms regarding cell counts in elite apnea divers are not readily transferable to non-elite recreational sportspersons. Divers and physicians should be aware of the limited adaptive performance of humans in the case of extended apnea.

Immune and inflammatory responses to freediving calculated from leukocyte gene expression profiles

Freedivers hold their breath while diving, causing blood oxygen levels to decrease (hypoxia) while carbon dioxide increases (hypercapnia). Whereas blood gas changes are presumably involved in the progression of respiratory diseases, less is known about their effect on healthy individuals. Here we have used gene expression profiling to analyze elite athletes' immune and inflammatory responses to freediving. Blood was collected before and 1 and 3 h after a series of maximal dynamic and static freediving apneas in a pool, and peripheral blood gene expression was mapped on genome-wide microarrays. Fractions of phenotypically distinct immune cells were computed by deconvolution of the gene expression data using Cibersort software. Changes in gene activity and associated biological pathways were determined using R and GeneGo software. The results indicated a temporary increase of neutrophil granulocytes, and a decrease of cytotoxic lymphocytes; i.e., CD8+ T cells and resting NK cells. Biological pathway associations indicated possible protective reactions: genes involved in anti-inflammatory responses to proresolving lipid mediators were upregulated, whereas central factors involved in granule-mediated lymphocyte cytotoxicity were downregulated. While it remains unresolved whether freediving alters the immune system's defensive function, these results provide new insight into leukocyte responses and the protection of homeostasis in healthy athletes.

Association between Serum Interleukin-17A Level and High-Altitude Deacclimatization Syndrome

High-altitude deacclimatization syndrome (HADAS) is emerging as a severe public health issue that threatens the quality of life of individuals who return to lower altitude from high altitude. In this study, we measured serum levels of SOD, MDA, IL-17A, IL-10, TNF-α, and HADAS score in HADAS subjects at baseline and 50th and 100th days and to evaluate the relationship between interleukins, including IL-17A, and HADAS. Our data showed that and the serum IL-17A levels and HADAS score decreased over time in the HADAS group, and serum IL-17A levels were significantly higher in the HADAS group at baseline and 50th day compared with controls (p < 0.05). Furthermore, baseline serum levels of MDA and TNF-α were significantly higher, while SOD and IL-10 levels were lower in HADAS subjects compared with controls (p < 0.05). It is interesting that serum levels of IL-17A were clearly interrelated with HADAS incidence and severity (p < 0.05). ROC curve analysis showed that combined serum IL-17A and IL-10 levels were a better predictor of HADAS incidence than serum levels of IL-17A or IL-10 alone. These data suggest that serum levels of IL-17A are a novel predictive index of HADAS.

Effects of docosahexaenoic supplementation and in vitro vitamin C on the oxidative and inflammatory neutrophil response to activation

We studied the effects of diet supplementation with docosahexaenoic (DHA) and in vitro vitamin C (VitC) at physiological concentrations on oxidative and inflammatory neutrophil response to phorbol myristate acetate (PMA). Fifteen male footballers ingested a beverage enriched with DHA or a placebo for 8 weeks in a randomized double-blind study. Neutrophils were isolated from blood samples collected in basal conditions at the end of nutritional intervention. Neutrophils were cultured for 2 hours at 37°C in (a) control media, (b) media with PMA, and (c) media with PMA + VitC. PMA induces neutrophil degranulation with increased extracellular myeloperoxidase and catalase activities, nitric oxide production, expression of the inflammatory genes cyclooxygenase-2, nuclear factor κβ, interleukin 8 and tumor necrosis factor α, and interleukin 6 production. DHA diet supplementation boosts the exit of CAT from neutrophils but moderates the degranulation of myeloperoxidase granules induced by PMA. VitC facilitates azurophilic degranulation of neutrophils and increases gene expression of myeloperoxidase induced by PMA. VitC and DHA diet supplementation prevent PMA effects on inflammatory gene expression, although together they do not produce additional effects. DHA diet supplementation enhances antioxidant defences and anti-inflammatory neutrophil response to in vitro PMA activation. VitC facilitates neutrophil degranulation but prevents an inflammatory response to PMA.

Neurotoxicity in rats induced by the poisonous dreamfish (Sarpa salpa)

CONTEXT

Consumption of Sarpa salpa Linn. (Sparidae) in certain periods of the year is inadvisable because it can cause central nervous system disorders resulting in sea food poisoning.

AIMS

The present study assesses the cytotoxic effects of compounds, not-yet identified, present in the organ extracts of S. salpa, collected in autumn, the period corresponding to the peak in human health problems.

MATERIALS AND METHODS

The toxicity was assessed by mouse bioassay of aqueous extract of the fish organs. Wistar rats received daily extracts of different organs of S. salpa by gastric gavage for 7 d (0.3 mL of extract/100 g body weight BW). The dose of tissue extracts of viscera, liver, brain, and flesh of S. salpa administered to rats was as follows: 172, 313, 2050, and 2660 mg/kg BW, respectively. No deaths occurred during the period of treatment.

RESULTS

The lethal dose (LD50) determined for the crude ciguatoxin (neurotoxins) extracts of viscera, liver, brain, and flesh of S. salpa was as follows: 1.2, 2.2, 14.4, and 18.6 g/kg mouse, respectively. Changes in locomotor activity during the first 2 h and failure in breathing and no evident signs of gastrointestinal problems were recorded. We observed (1) induction of oxidative stress, indicated by an increase in lipid peroxidation (TBARS) in groups that received extracts of liver (+425%) or viscera (+433%), and a significant decrease in antioxidant enzyme activities (SOD, CAT, and GPx) in cerebral cortex tissue by 13%, 25%, and 25% (LT: animals receiving liver extracts) and by 16%, 26%, and 27% (VT: animals receiving viscera extracts), respectively. In contrast, the administration of extracts of flesh and brain induced an increase in antioxidant enzyme activities (SOD, CAT, and GPx) in cerebral cortex tissue by 26%, 23%, and 44% (FT: flesh extract) and 28%, 24%, and 46% (BT: brain extract), respectively; (2) a significant decrease for acetylcholinesterase (AChE) activity in cerebral cortex was recorded in FT, BT, LT, and VT by 27, 34, 58, and 78%, respectively. Moreover, a significant decrease of AChE activity in plasma was recorded in FT, BT, LT, and VT by 16, 21, 38, and 48%, respectively; (3) the histological findings confirmed the biochemical results.

CONCLUSIONS

Liver and especially the visceral part of S. salpa presented toxicity, which clearly indicates the danger of using this fish as food.

Brain responses to emotional stimuli during breath holding and hypoxia: an approach based on the independent component analysis

Voluntary breath holding represents a physiological model of hypoxia. It consists of two phases of oxygen saturation dynamics: an initial slow decrease (normoxic phase) followed by a rapid drop (hypoxic phase) during which transitory neurological symptoms as well as slight impairment of integrated cerebral functions, such as emotional processing, can occur. This study investigated how breath holding affects emotional processing. To this aim we characterized the modulation of event-related potentials (ERPs) evoked by emotional-laden pictures as a function of breath holding time course. We recorded ERPs during free breathing and breath holding performed in air by elite apnea divers. We modeled brain responses during free breathing with four independent components distributed over different brain areas derived by an approach based on the independent component analysis (ICASSO). We described ERP changes during breath holding by estimating amplitude scaling and time shifting of the same components (component adaptation analysis). Component 1 included the main EEG features of emotional processing, had a posterior localization and did not change during breath holding; component 2, localized over temporo-frontal regions, was present only in unpleasant stimuli responses and decreased during breath holding, with no differences between breath holding phases; component 3, localized on the fronto-central midline regions, showed phase-independent breath holding decreases; component 4, quite widespread but with frontal prevalence, decreased in parallel with the hypoxic trend. The spatial localization of these components was compatible with a set of processing modules that affects the automatic and intentional controls of attention. The reduction of unpleasant-related ERP components suggests that the evaluation of aversive and/or possibly dangerous situations might be altered during breath holding.

Protective effects of meat from lambs on selenium nanoparticle supplemented diet in a mouse model of polycyclic aromatic hydrocarbon-induced immunotoxicity

Increased environmental oxidative stress caused primarily by chemicals like polycyclic aromatic hydrocarbons, plays significant role in human diseases. A representative compound, 7,12-dimethylbenz(a)anthracene (DMBA), was used for modeling oxidative damages including the significant decrease of the antioxidant capacity of the blood. Selenium has antioxidant effects but with a narrow therapeutic window. In our current studies to avoid accidental overdose and toxicity selenium was given to meat-producing animals. The standard rodent diet of mice was replaced by meat from lambs either on standard or selenium-enriched diet. Selenium concentration of lamb meat was enhanced three times by nano-selenium administration and an increase in the antioxidant capacity of the blood of mice was measured after the indirect selenium supplementation. Protective effects were also observed against DMBA-induced immunotoxicity. Twice the amount of white blood cells and among them three times more phagocytes survived. Similarly, in their renewal system in bone marrow twice the amount of cells survived and regenerative capacity of granulopoiesis was four times higher than in control DMBA-damaged mice. Our findings suggest functional dietary benefits of lamb meat enriched with selenium by feeding lambs with nanoparticle selenium supplements.

Hepatotoxicity in rats induced by the poisonous dreamfish (Sarpa salpa)

AIMS

The present study was aimed to assess the cytotoxic effects of not-yet identified compounds present in organ extracts of Sarpa salpa, collected in autumn, the period with a peak in health problems.

METHODS

The toxicity was assessed by mouse bioassay of extract of the fish's organs. Wistar rats received daily extracts of different organs of S. salpa by gastric gavage for 7 d (0.3 ml of extract/100 g body weight, BW). The dose of tissue extracts of viscera, liver, brain and flesh of S. salpa administered to rats were as follows: 17.2, 31.3, 205, 266 mg/100g BW, respectively. No deaths occurred during the period of treatment.

RESULTS

The lethal dose (LD50%) determined for the crude ciguatoxin (neurotoxins) extracts of viscera, liver, brain and flesh of S. salpa were as follows: 1.2, 2.2, 14.4, 18.6 g/kg mouse, respectively. Changes in locomotor activity during the first 2 h and failure breathing and no evident signs of gastrointestinal problems were recorded. We observed: (1) Induction of oxidative stress, indicated by an increase in lipid peroxidation (TBARS) in groups that received extracts of liver (+490%) or viscera (+592%). Accompanied by a significant decrease in antioxidant enzyme activities (SOD, CAT, GPx) in liver tissue by 15%, 17%, 18% (LT: animals receiving liver extracts) and by 19%, 22%, 22% (VT: animals receiving viscera extracts), respectively. In contrast the administration of extracts of flesh and brain induced an increase in antioxidant enzyme activities (SOD, CAT, GPx) in liver tissue by 15%, 19%, 15% (FT: flesh extract) and 18%, 55%, 55% (BT: brain extract), respectively; (2) A significant increase in total metallothionein levels in liver tissue was recorded in (FT), (BT), (LT) and (VT) by 55%, 88%, 255% and 277%, respectively, (3) The histological findings confirmed the biochemical results.

CONCLUSIONS

Liver and especially visceral part of S. salpa presented toxicity, which clearly indicates the danger of using this fish as food.

Effects of docosahexaenoic acid diet supplementation, training, and acute exercise on oxidative balance in neutrophils

Diet supplementation with omega-3 fatty acids could influence the oxidative equilibrium, enhancing a pro-oxidant status. The aim was to determine the effects of diet supplementation with docosahexaenoic acid (DHA), training, and acute exercise on oxidative balance in neutrophils. Fifteen volunteer male soccer players were randomly assigned to a placebo or experimental group. The placebo group was supplemented with an almond-based beverage whereas the experimental group was supplemented with the same beverage enriched with DHA, in addition to their Mediterranean-type diet. Three blood samples were taken: in basal conditions at the beginning of the nutritional intervention and after 8 weeks of training season in basal and postexercise conditions. The training season significantly increased the antioxidant defenses of neutrophils, such as catalase, glutathione peroxidase and glutathione reductase enzyme activities; and decreased oxidative damage markers such as malondialdehyde, carbonyl and nitrotyrosine indexes. Oxidative damage markers decreased in neutrophils after acute exercise, which primed neutrophils to produce reactive oxygen and nitrogen species (RONS) after immune stimulation with zymosan or phorbol myristate acetate in trained footballers. DHA supplementation resulted in no significant effects on oxidative stress balance in neutrophils. In conclusion, DHA supplementation did not modify the adaptive response of the antioxidant system of neutrophils to training or the production of RONS induced by immune stimulation after acute exercise.

Biochemical responses of Mytilus galloprovincialis as biomarkers of acute environmental pollution caused by the Don Pedro oil spill (Eivissa Island, Spain)

In the present work, the potential use of several antioxidant and detoxification biomarkers in the digestive gland of wild mussels (Mytilus galloprovincialis) for biomonitoring the marine pollution induced by the Don Pedro oil spill has been investigated. Two locations from the East to South-East of Eivissa (Ibiza) and Formentera islands were selected, one extensively affected by the oil spill and the other one not affected and considered as the control area. Mussels were sampled one, two and six months after the Don Pedro accident. Polycyclic aromatic hydrocarbon (PAH) levels were significantly increased in the soft tissues of mussels in the affected area one month after the disaster, returning to normal values after six months. Markers of oxidative damage in lipids--malondialdehyde, and in proteins--carbonyl derivates, and antioxidant enzyme--catalase, superoxide dismutase and glutathione peroxidase, activities significantly increased as result of the spill oil after one month, returning to basal values at two month sampling time. Glutathione/glutathione disulfide ratio (GSH/GSSG), as a marker of the redox status, was reduced after one and two months indicating a more oxidized situation. Markers of detoxification--glutathione-S-transferase and cytochrome P4501A activities and metallothionein gene expression--were significantly increased by the oil spill one month after the accident, returning to the basal values at two month sampling time. In conclusion, the Don Pedro accident induced a transient situation of PAHs pollution resulting in enhanced antioxidant and detoxification defense systems in the wild mussel M. galloprovincialis returning to normal levels six months from the spill. The selected biomarkers are a useful tool for biomonitoring the response to acute exposure to pollutants in marine mussels.

Effects of maximal static apnea on antioxidant defenses in trained free divers

PURPOSE

To investigate the effects of maximal static apnea on plasma antioxidant status, oxidative stress, and antioxidant enzyme activities in trained free divers.

METHODS

Blood was taken from apnea-trained (Tr) and control (Con) subjects at baseline (B) and after one (A1), three (A3), and five (A5) apneas. Trolox equivalent antioxidant capacity (TEAC), ferric reducing ability of plasma (FRAP), uric acid, and bilirubin assays assessed plasma antioxidant status and malondialdehyde (MDA) quantified the oxidative stress response. The activities of erythrocyte antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) were determined at baseline and after the fifth apnea.

RESULTS

TEAC was significantly higher in divers versus controls after A1 (P < 0.05). A group effect of SOD activity indicated higher activity throughout the protocol in Tr (mean +/- SD; Con, 43.2 +/- 10.1 U.g Hb; Tr, 50.1 +/- 7.3 U.g Hb; P = 0.04). With no other group differences, the groups' data were combined. Apnea significantly increased SOD (B, 44.1 +/- 11.1 U.g Hb; A5, 48.1 +/- 7.5 U.g Hb; P < 0.05) and GPx activity (B, 60.5 +/- 14.9 U.g Hb; A5, 70.1 +/- 16.0 U.g Hb; P = 0.02); however, CAT activity decreased (B, 5.25 +/- 0.59 U.mg Hb; A5, 5.00 +/- 0.53 U.mg Hb; P = 0.03). MDA was unaffected by apnea (P = 0.32).

CONCLUSIONS

Trained free divers have increased SOD activity during apnea; however, there is little difference in their antioxidant and oxidative stress responses compared with controls. In both groups, acute changes in antioxidant enzyme activities suggest that they may protect from excessive antioxidant depletion and oxidative stress during apnea.

Intense physical activity enhances neutrophil antioxidant enzyme gene expression. Immunocytochemistry evidence for catalase secretion

We studied the effects of intense exercise on the neutrophil antioxidant enzyme activities and gene expression. Blood samples were taken from seven cyclists in basal conditions and 3 h after two competition stages of 165 km. Serum creatine kinase (CK) activity, plasma carbonyl derivatives and uric acid levels increased after exercise. The cycling stage induced neutrophilia and increased myeloperoxidase (MPO) activity and reactive oxygen species (ROS) production. Antioxidant enzyme activities (catalase, glutathione peroxidase and superoxide dismutase) decreased after exercise, although gene expression increased. Immunocytochemistry showed catalase (CAT) enzyme equally distributed between the cytoplasm and organelles before exercise, and after exercise the cytoplasmic CAT levels were reduced and were absent in the compartments. After in vitro stimulation with opsonized zymosan (OZ) the extracellular CAT levels increased. This suggests a CAT secretion in order to avoid neutrophil-induced oxidative damage at a local level or to regulate the function of ROS as extracellular signalling molecules.

Scuba diving enhances endogenous antioxidant defenses in lymphocytes and neutrophils

The aim was to study the effects of a scuba diving session on the lymphocyte antioxidant system, NO synthesis, the capability to produce reactive oxygen species and the antioxidant response in neutrophils. For that purpose seven male divers performed an immersion at a depth of 40 m for 25 min. The same parameters were measured after an hyperbaric oxygen (HBO) treatment at resting conditions in a hyperbaric chamber. Lymphocyte H2O2 production rose after diving and after HBO treatment. Glutathione peroxidase (GPx) and catalase activities increased after diving in lymphocytes, while after HBO exposure only increased GPx activity. Lymphocyte HO-1 mRNA expression increased after diving and after HBO exposure, while iNOS levels and nitrite levels significantly increased after diving. The hyperoxia associated to scuba diving leads to a condition of oxidative stress with increased lymphocyte H2O2 production, HO-1 expression, NO synthesis and antioxidant enzyme adaptations in order to avoid oxidative damage.

Sleep disturbances, oxidative stress and cardiovascular risk parameters in postmenopausal women complaining of insomnia

OBJECTIVE

The aim of this work was to investigate cardiovascular risk factors and oxidative stress parameters as well as sleep disturbances in polysomnography recordings of 38 postmenopausal women with insomnia.

METHODS

Polysomnography recordings were performed on subjects for sleep analysis. Oxidative stress parameters were analyzed by measuring blood concentration of catalase, superoxide dismutase (SOD), thiobarbituric acid reactive substances (TBARS) and glutathione. For cardiovascular risk factors, we measured plasma levels of homocysteine, folic acid and vitamin B6.

RESULTS

Findings of polysomnography recordings revealed: 68% experienced decreased sleep efficiency, 50% had apnea, 7.8% had periodic leg movements and 2.6% had bruxism (involuntary gnashing and grinding of the teeth during sleep). Our results showed that the majority of our subjects presented normal concentrations of the parameters studied according to standards reached in our laboratory. The only notable exception was TBARS. In this case, only 21% displayed normal values. We also found inverse correlations between SOD activity and both age and time of menopause.

CONCLUSIONS

Although all women complained of insomnia, 50% of them demonstrated apnea during polysomnography recordings. Of the parameters measuring oxidative stress, only TBARS levels were increased in our sample. Some clinical data, such as time of onset of menopause, may be associated with the oxidative stress status of these women, probably due to the lack of estrogen and to sleep disturbances, such as apnea.

Enzymatic antioxidant response of a labrid fish (Coris julis) liver to environmental caulerpenyne

Exposure of marine animals to certain toxic compounds can enhance reactive oxygen species production with subsequent damage to macromolecules and alterations in oxidant defenses levels. Caulerpenyne is the major metabolite synthesized by Caulerpa species, used as chemical defense affecting several cellular and molecular targets. We assessed the changes produced by the presence of Caulerpa spp. in the activities of antioxidant enzymes as well as lipid peroxidation levels in liver of the teleost Coris julis. Fish were captured at two stations with Caulerpa species-Caulerpa taxifolia and Caulerpa prolifera-and at a region with the seagrass Posidonia oceanica as negative control. Caulerpenyne concentration was significantly higher in C. prolifera than in C. taxifolia (p<0.05). Glutathione S-transferase, glutathione peroxidase and glutathione reductase activities were significantly higher in both Caulerpa stations compared to the P. oceanica (p<0.05). No statistical difference (p>0.05) existed in catalase activity between groups. Glutathione reductase activity is significantly higher in C. prolifera station than in C. taxifolia (p<0.05). Despite the variations in the antioxidant enzyme activities, there was no significant difference in malondialdehyde concentration. In conclusion, the production of caulerpenyne by Caulerpa species could induce an antioxidant adaptation in the liver of C. julis in order to prevent oxidative damage.

Vitamin C supplementation influences the antioxidant response and nitric oxide handling of erythrocytes and lymphocytes to diving apnea

OBJECTIVE

We have investigated the influence of vitamin C diet supplementation on the antioxidant response and nitrite levels in lymphocytes and erythrocytes during diving apnea.

SUBJECTS

Seven male professional apnea divers participated in a double blind crossover study. Divers were randomly assigned to either vitamin C supplemented or placebo groups. The subjects did not take any other supplements than the ones provided for this study.

INTERVENTION

One group was supplemented with vitamin C capsules (1 g per day) for 7 days while the other group took a placebo composed of lactose. The usual dietary habits of participants were assessed using a self-reported 7-days 24-h recall before the day of the study. Blood samples were taken under basal conditions, immediately after diving apnea for 4 h and after 1 h of recovery.

RESULTS

Catalase activity increased in erythrocytes (23%) and superoxide dismutase increased in lymphocytes (35%) during the recovery only in the placebo group. Lymphocyte ascorbate levels increased in the supplemented group after diving (85%) and maintained high at recovery. Plasma nitrite levels increased about twofold in both groups during the recovery. Erythrocyte nitrite levels increased after diving (50%) and about twofold during the recovery in the supplemented group. Nitrite levels and iNOS levels in lymphocytes were higher in the placebo group than in the supplemented during the recovery. Erythrocyte carbonyl derivates were unchanged in all situations.

CONCLUSIONS

Vitamin C supplementation influenced the antioxidant response and NO handling in erythrocytes and lymphocytes to the oxidative stress induced by hypoxia-reoxygenation.