Microbiota present in cystic fibrosis lungs as revealed by whole genome sequencing.

Determination of the precise composition and variation of microbiota in cystic fibrosis lungs is crucial since chronic inflammation due to microorganisms leads to lung damage and ultimately, death. However, this constitutes a major technical challenge. Culturing of microorganisms does not provide a complete representation of a microbiota, even when using culturomics (high-throughput culture). So far, only PCR-based metagenomics have been investigated. However, these methods are biased towards certain microbial groups, and suffer from uncertain quantification of the different microbial domains. We have explored whole genome sequencing (WGS) using the Illumina high-throughput technology applied directly to DNA extracted from sputa obtained from two cystic fibrosis patients. To detect all microorganism groups, we used four procedures for DNA extraction, each with a different lysis protocol. We avoided biases due to whole DNA amplification thanks to the high efficiency of current Illumina technology. Phylogenomic classification of the reads by three different methods produced similar results. Our results suggest that WGS provides, in a single analysis, a better qualitative and quantitative assessment of microbiota compositions than cultures and PCRs. WGS identified a high quantity of Haemophilus spp. (patient 1) or Staphylococcus spp. plus Streptococcus spp. (patient 2) together with low amounts of anaerobic (Veillonella, Prevotella, Fusobacterium) and aerobic bacteria (Gemella, Moraxella, Granulicatella). WGS suggested that fungal members represented very low proportions of the microbiota, which were detected by cultures and PCRs because of their selectivity. The future increase of reads' sizes and decrease in cost should ensure the usefulness of WGS for the characterisation of microbiota.

Food for thought: the importance of glucose and other energy substrates for sustaining brain function under varying levels of activity.

The brain requires a constant and substantial energy supply to maintain its main functions. For decades, it was assumed that glucose was the major if not the only significant source of energy for neurons. This view was supported by the expression of specific facilitative glucose transporters on cerebral blood vessels, as well as neurons. Despite the fact that glucose remains a key energetic substrate for the brain, growing evidence suggests a different scenario. Thus astrocytes, a major type of glial cells that express their own glucose transporter, play a critical role in coupling synaptic activity with glucose utilization. It was shown that glutamatergic activity triggers an enhancement of aerobic glycolysis in this cell type. As a result, lactate is provided to neurons as an additional energy substrate. Indeed, lactate has proven to be a preferential energy substrate for neurons under various conditions. A family of proton-linked carriers known as monocarboxylate transporters has been described and specific members have been found to be expressed by endothelial cells, astrocytes and neurons. Moreover, these transporters are subject to fine regulation of their expression levels and localization, notably in neurons, which suggests that lactate supply could be adjusted as a function of their level of activity. Considering the importance of energetics in the aetiology of several neurodegenerative diseases, a better understanding of its cellular and molecular underpinnings might have important implications for the future development of neuroprotective strategies.

Synaptic plasticity and the Warburg effect.

Functional brain imaging studies show that in certain brain regions glucose utilization exceeds oxygen consumption, indicating the predominance of aerobic glycolysis. In this issue, Goyal et al. (2014) report that this metabolic profile is associated with an enrichment in the expression of genes involved in synaptic plasticity and remodeling processes.

Assessment of physical activity with a pedometer and its relationship with VO2max among adolescents in Switzerland.

OBJECTIVES: In the absence of a gold standard, the assessment of physical activity in children remains difficult. To record physical activity with a pedometer and to examine to what extent it is correlated with VO2max. METHODS: Survey on physical activity and fitness; 233 Swiss adolescents aged 11 to 15 carried a pedometer (Pedoboy) during seven consecutive days. VO2max was estimated through an endurance shuttle run test. RESULTS: The physical activity recorded by the pedometer did not vary from one day to the other (p > 0.05). The physical activity was higher among boys than among girls (p < 0.001) and higher among younger adolescents (6th versus 8th grade; p < 0.001). The correlation between physical activity and estimated VO2max was 0.30 (p < 0.01). CONCLUSIONS: The use of a pedometer to assess physical activity over one entire week is feasible among adolescents. The record provided by the pedometer gives an objective measure of the usual physical activity and, as such, is relatively well correlated with aerobic capacity.

Effect of a lifestyle intervention on adiposity and fitness in socially disadvantaged subgroups of preschoolers: a cluster-randomized trial (Ballabeina).

OBJECTIVE: A multidimensional lifestyle intervention performed in 652 preschoolers (72% of migrant, 38% of low educational level (EL) parents) reduced body fat, but not BMI and improved fitness. The objective of this study is to examine whether the intervention was equally effective in children of migrant and/or low EL parents.¦METHODS: Cluster-randomized controlled single blinded trial, conducted in 2008/09 in 40 randomly selected preschools in Switzerland. The culturally tailored intervention consisted of a physical activity program and lessons on nutrition, media use and sleep. Primary outcomes included BMI and aerobic fitness. Secondary outcomes included %body fat, waist circumference and motor agility.¦RESULTS: Children of migrant parents benefitted similarly from the intervention compared to their counterparts (p for interaction≥ 0.09). However, children of low EL parents benefitted less, although these differences did not reach statistical significance (p for interaction≥ 0.06). Average intervention effect sizes for BMI were -0.10, -0.05, -0.11 and 0.04 kg/m(2) and for aerobic fitness were 0.55, 0.20, 0.37 and -0.05 stages for children of non-migrant, migrant, middle/high EL and low EL parents, respectively.¦CONCLUSIONS: This intervention was similarly effective among preschoolers of migrant parents compared to their counterparts, while children of low EL parents benefitted less.

Gender differences in whole body fat oxidation kinetics during exercise

Introduction Discrepancies appear in studies comparing fat oxidation between men and women during exercise (1). Therefore, this study aimed to quantitatively describe and compare whole body fat oxidation kinetics between genders during exercise using a sinusoidal model (SIN) (2). Methods Twelve men and 11 women matched for age, body mass index (23.4±0.6 kg.m-2 and 21.5±0.8 kg.m-2, respectively) and aerobic fitness [maximal oxygen uptake ( ) (58.5±1.6 mL.kg FFM-1.min-1 and 55.3±2.0 mL.kg FFM-1.min-1, respectively) and power output ( ) per kilogram of fat-free mass (FFM)] performed submaximal incremental tests (Incr) with 5-min stages and 7.5% increment on a cycle ergometer. Respiratory and HR values were averaged over the last 2 minutes of each stage. All female study participants were eumenorrheic, reported regular menstrual cycles (28.6 ± 0.8 days) and were not taking oral contraceptives (OC) or other forms of exogenous ovarian hormones. Women were studied in the early follicular phase (FP) of their menstrual cycle (between days 3 and 8, where day 1 is the first day of menses). Fat oxidation rates were determined using indirect calorimetry and plotted as a function of exercise intensity. The SIN model (2), which includes three independent variables (dilatation, symmetry, translation), was used to mathematically describe fat oxidation kinetics and to determine the intensity (Fatmax) eliciting the maximal fat oxidation (MFO). Results During Incr, women exhibited greater fat oxidation rates from 35 to 85% , MFO (6.6 ± 0.9 vs. 4.5 ± 0.3 mgkg FFM-1min-1) and Fatmax (58.1 ± 1.9 vs. 50.0 ± 2.7% ) (P<0.05) than men. While men and women showed similar global shapes of fat oxidation kinetics in terms of dilatation and symmetry (P>0.05), the fat oxidation curve tended to be shifted towards higher exercise intensities in women (rightward translation, P=0.08). Conclusion These results showed that women, eumenorrheic, not taking OC and tested in FP, have a greater reliance on fat oxidation than men during submaximal exercise, but they also indicate that this greater fat oxidation is shifted towards higher exercise intensities in women compared with men. References 1. Blaak E. Gender differences in fat metabolism. Curr Opin Clin Nutr Metab Care 4: 499-502, 2001. 2. Cheneviere X, Malatesta D, Peters EM, and Borrani F. A mathematical model to describe fat oxidation kinetics during graded exercise. Med Sci Sports Exerc 41: 1615-1625, 2009.

Strategies of "Pseudomonas aeruginosa" to overcome copper limitation

Summary Copper is an important trace element and micronutrient for living organisms as it is the cofactor of several enzymes involved in diverse biological redox processes such as aerobic respiration, denitrification and photosynthesis. Despite its importance, copper may be poorly bioavailable in soils and aquatic environments, as well as in the human body, especially at physiological or alkaline pH. In this work, we have investigated the strategies that the versatile bacterium and opportunistic pathogen Pseudomonas aeruginosa has evolved to face and overcome copper limitation. The global response of the P. aeruginosa to copper limitation was assessed under aerobic conditions. Numerous iron uptake functions (including the siderophores pyoverdine and pyochelin) were down-regulated whereas expression of cioAB (encoding an alternative, copper-independent, cyanide-resistant ubiquinol oxidase) was up-regulated. Wild type P. aeruginosa was able to grow aerobically in a defined glucose medium depleted of copper by a copper chelator, whereas a cioAB mutant did not grow. Thus, P. aeruginosa relies on the CioAB enzyme to cope with severe copper deprivation. A quadruple cyo cco1 cco2 cox mutant, which was deleted for all known heme-copper terminal oxidases of P. aeruginosa, grew aerobically, albeit more slowly than did the wild type, indicating that the CioAB enzyme is capable of energy conservation. However, the expression of a cioA'-'lacZ fusion was less dependent on the copper status in the quadruple mutant than in the wild type, suggesting that copper availability might affect cioAB expression indirectly, via the function of the heme-copper oxidases. These results suggest that the CioAB enzyme can be used as a by-pass strategy to overcome severe copper limitation and perform aerobic respiration even if virtually no copper is available. The PA0114 gene, which encodes a protein of the SCOT/SenC family, was found to be important for copper acquisition and aerobic respiration in low copper conditions. A PA0114 (sent) mutant grew poorly in low copper media and had low terminal oxidase activity with TMPD (N,N,N',N'-tetramethyl-p-phenylenediamine), but expressed the CioAB enzyme at elevated levels. Addition of copper reversed these phenotypes, suggesting that periplasmic copper capture by the SenC protein is another strategy that helps P. aeruginosa to adapt to copper deprivation. RESUME Le cuivre est un micronutriment important pour les organismes vivants. Il représente le cofacteur de plusieurs enzymes impliquées dans une multitude de processus biologiques tels que la respiration aérobie, la dénitrification et la photosynthèse. Malgré son importance, le cuivre peut être peu disponible dans les sols, les environnements aquatiques et le corps humain, spécialement à pH physiologique ou alcalin. Dans ce travail nous avons étudié les stratégies développées par la bactérie pathogène opportuniste Pseudomonas aeruginosa PAO1 afm de faire face et de surmonter le manque de cuivre. La réponse globale de P. aeruginosa à la carence de cuivre a été analysée dans des conditions aérobie. Les résultats obtenus ont montré que plusieurs gènes impliqués dans l'acquisition du fer, tels que les gènes codant pour les sidérophores (pyoverdine et pyochéline), étaient réprimés, tandis que l'expression de l'opéron cioAB, codant pour l'oxydase terminale insensible au cyanure (CIO), était augmentée. La souche sauvage P. aeruginosa est capable de croître dans un milieu où la concentration en cuivre est limitée, due à la présence d'un chélateur spéciftque de cuivre, tandis que le mutant cioAB ne croît pas dans ces conditions. Nous avons conclu que P. aeruginosa nécessite l'oxydase terminale CIO pour faire face à la carence en cuivre. Un quadruple mutant affecté dans toutes les oxydases dépendantes du cuivre (cyo ccol cco2 cox) et appartenant aux oxydases de type hème-cuivre, peut croître en aérobie, néanmoins plus lentement que la souche sauvage, ce qui montre que l'enzyme CIO est capable de conserver l'énergie. L'expression de la fusion rapportrice cioA'-'IacZ chez le quadruple mutant est moins dépendante de la disponibilité de cuivre que chez la souche sauvage. Ces résultats suggèrent que la disponibilité de cuivre influence l'expression de cioAB d'une façon indirecte, par le biais des oxydases terminales de type héme-cuivre. Il est donc possible qu'en cas de carence de cuivre, P. aeruginosa utilise l'enzyme CIO comme stratégie afin de surmonter ce manque et de réaliser la respiration aérobie. Nous avons démontré que le gène PA0114, codant pour une protéine appartenant à la famille SCO1/SenC, est important dans l'acquisition et dans la respiration aérobie dans des environnements où le cuivre est présent en faible concentration. En ces conditions, la croissance du mutant senC est faible; de plus, l'activité des oxydases terminales en présence du donneur d'électrons TMPD (N,N,N,N'-tetraméthyl-p-phénylenediamine) est basse. Toutefois, l'addition de cuivre au milieu de culture permet de restaurer le phénotype du type sauvage. Ces résultats montrent que la protéine SenC est capable d'acquérir le cuivre et représente donc une autre stratégie chez P. aeruginosa pour s'adapter à un manque de cuivre.

Effects of weight loss and exercise on insulin resistance, and intramyocellular triacylglycerol, diacylglycerol and ceramide.

AIMS/HYPOTHESIS: Intramyocellular lipids, including diacylglycerol (DAG) and ceramides, have been linked to insulin resistance. This randomised repeated-measures study examined the effects of diet-induced weight loss (DIWL) and aerobic exercise (EX) on insulin sensitivity and intramyocellular triacylglycerol (IMTG), DAG and ceramide. METHODS: Sixteen overweight to obese adults (BMI 30.6 ± 0.8; 67.2 ± 4.0 years of age) with either impaired fasting glucose, or impaired glucose tolerance completed one of two lifestyle interventions: DIWL (n = 8) or EX (n = 8). Insulin sensitivity was determined using hyperinsulinaemic-euglycaemic clamps. Intramyocellular lipids were measured in muscle biopsies using histochemistry and tandem mass spectrometry. RESULTS: Insulin sensitivity was improved with DIWL (20.6 ± 4.7%) and EX (19.2 ± 12.9%). Body weight and body fat were decreased by both interventions, with greater decreases in DIWL compared with EX. Muscle glycogen, IMTG content and oxidative capacity were all significantly (p < 0.05) decreased with DIWL and increased with EX. There were decreases in DAG with DIWL (-12.4 ± 14.6%) and EX (-40.9 ± 12.0%). Ceramide decreased with EX (-33.7 ± 11.2%), but not with DIWL. Dihydroceramide was decreased with both interventions. Sphingosine was decreased only with EX. Changes in total DAG, total ceramides and other sphingolipids did not correlate with changes in glucose disposal. Stearoyl-coenzyme A desaturase 1 (SCD1) content was decreased with DIWL (-19.5 ± 8.5%, p < 0.05), but increased with EX (19.6 ± 7.4%, p < 0.05). Diacylglycerol acyltransferase 1 (DGAT1) was unchanged with the interventions. CONCLUSIONS/INTERPRETATION: Diet-induced weight loss and exercise training both improved insulin resistance and decreased DAG, while only exercise decreased ceramides, despite the interventions having different effects on IMTG. These alterations may be mediated through differential changes in skeletal muscle capacity for oxidation and triacylglycerol synthesis. TRIAL REGISTRATION: ClinicalTrials.gov NCT00766298.

Physical activity in free-living, overweight white and black women: divergent responses by race to diet-induced weight loss.

BACKGROUND: Black women are at greater risk of obesity than are white women, perhaps because of their lower levels of physical activity. OBJECTIVE: We compared free-living activity energy expenditure (AEE) in sedentary white and black women (in overweight and normal-weight states) and in never-overweight control subjects. DESIGN: Subjects included 46 women (23 white, 23 black) studied while overweight and after reaching a normal weight and 38 female control subjects (23 white, 15 black). Diet, without exercise training, resulted in a mean weight loss of 13 kg and a body mass index (in kg/m(2)) < 25. Body composition, sleeping energy expenditure, free-living total energy expenditure, and the energy cost of activity and aerobic capacity were assessed before and after weight loss under 4-wk, diet-controlled, weight-stable conditions and in the control subjects. AEE was defined as above-sleep energy expenditure. RESULTS: No significant racial differences in body composition, before or after weight loss, were found. After weight loss, AEE and aerobic capacity increased in the white women and decreased in the black women (P < 0.05 and P < 0.02, respectively). After weight loss, but not before, the white women had a significantly higher mean AEE than did the black women (2448 +/- 979 and 1728 +/- 1373 kJ/d, respectively; P < 0.05), approximating AEEs in the white (2314 +/- 1105) and black (2310 +/- 1251) control subjects. CONCLUSIONS: Relative to the responses of the white women to diet-induced weight loss, the black women became less fit and less physically active. Induction of a normal body weight in overweight black women appeared to produce a more obesity-prone state, favoring weight relapse.

Effects of exercise on the isoelectric patterns of erythropoietin.

OBJECTIVES: Recombinant erythropoietin has a strong impact on aerobic power and is therefore one of the most potent doping agents in endurance sports. The anti-doping control of this synthetic hormone relies on the detection, in the urine, of its isoelectric pattern, which differs from that of the corresponding natural hormone, the latter being typically more acidic than the former. However, a small number of natural urinary patterns, referred to as "atypical patterns," are less acidic than the dominant form. Based on anecdotal evidence, the occurrence of such patterns seems to be related to particular strenuous exercises. This study aimed to demonstrate this relation using a strenuous exercise protocol. DESIGN: Seven athletes took part in a training protocol including a series of supramaximal short-duration exercises. Urine and blood samples were collected throughout the protocols. SETTINGS: World Cycling Center, Aigle, Switzerland, and research laboratories. PARTICIPANTS: Seven top-level athletes (cyclists) were involved in this study. MAIN OUTCOME MEASURES: Erythropoietin (EPO) isoelectric patterns were obtained by submitting blood and urine samples to isoelectric focusing. Additional protein dosages were performed. RESULTS: Supramaximal short-duration exercises induced the transformation of typical urinary natural EPO patterns into atypical ones. None of the obtained atypical patterns fulfilled the 3 criteria mandatory for reporting an adverse analytical finding. Serum EPO patterns were not affected by the exercises that caused the transformation of urinary patterns. CONCLUSION: An exercise-induced transient renal dysfunction is proposed as a hypothetic explanation for these observations that rely on parallel investigations of proteinuria in the same samples.

Enhanced biodegradation of hexachlorocyclohexane (HCH) in contaminated soils via inoculation with Sphingobium indicum B90A.

Soil pollution with hexachlorocyclohexane (HCH) has caused serious environmental problems. Here we describe the targeted degradation of all HCH isomers by applying the aerobic bacterium Sphingobium indicum B90A. In particular, we examined possibilities for large-scale cultivation of strain B90A, tested immobilization, storage and inoculation procedures, and determined the survival and HCH-degradation activity of inoculated cells in soil. Optimal growth of strain B90A was achieved in glucose-containing mineral medium and up to 65% culturability could be maintained after 60 days storage at 30 degrees C by mixing cells with sterile dry corncob powder. B90A biomass produced in water supplemented with sugarcane molasses and immobilized on corncob powder retained 15-20% culturability after 30 days storage at 30 degrees C, whereas full culturability was maintained when cells were stored frozen at -20 degrees C. On the contrary, cells stored on corncob degraded gamma-HCH faster than those that had been stored frozen, with between 15 and 85% of gamma-HCH disappearance in microcosms within 20 h at 30 degrees C. Soil microcosm tests at 25 degrees C confirmed complete mineralization of [(14)C]-gamma-HCH by corncob-immobilized strain B90A. Experiments conducted in small pits and at an HCH-contaminated agricultural site resulted in between 85 and 95% HCH degradation by strain B90A applied via corncob, depending on the type of HCH isomer and even at residual HCH concentrations. Up to 20% of the inoculated B90A cells survived under field conditions after 8 days and could be traced among other soil microorganisms by a combination of natural antibiotic resistance properties, unique pigmentation and PCR amplification of the linA genes. Neither the addition of corncob nor of corncob immobilized B90A did measurably change the microbial community structure as determined by T-RFLP analysis. Overall, these results indicate that on-site aerobic bioremediation of HCH exploiting the biodegradation activity of S. indicum B90A cells stored on corncob powder is a promising technology.

Reproducibility of Fatmax and Fat Oxidation Rates during Exercise in Recreationally Trained Males.

Aerobic exercise training performed at the intensity eliciting maximal fat oxidation (Fatmax) has been shown to improve the metabolic profile of obese patients. However, limited information is available on the reproducibility of Fatmax and related physiological measures. The aim of this study was to assess the intra-individual variability of: a) Fatmax measurements determined using three different data analysis approaches and b) fat and carbohydrate oxidation rates at rest and at each stage of an individualized graded test. Fifteen healthy males [body mass index 23.1±0.6 kg/m2, maximal oxygen consumption ([Formula: see text]) 52.0±2.0 ml/kg/min] completed a maximal test and two identical submaximal incremental tests on ergocycle (30-min rest followed by 5-min stages with increments of 7.5% of the maximal power output). Fat and carbohydrate oxidation rates were determined using indirect calorimetry. Fatmax was determined with three approaches: the sine model (SIN), measured values (MV) and 3rd polynomial curve (P3). Intra-individual coefficients of variation (CVs) and limits of agreement were calculated. CV for Fatmax determined with SIN was 16.4% and tended to be lower than with P3 and MV (18.6% and 20.8%, respectively). Limits of agreement for Fatmax were -2±27% of [Formula: see text] with SIN, -4±32 with P3 and -4±28 with MV. CVs of oxygen uptake, carbon dioxide production and respiratory exchange rate were <10% at rest and <5% during exercise. Conversely, CVs of fat oxidation rates (20% at rest and 24-49% during exercise) and carbohydrate oxidation rates (33.5% at rest, 8.5-12.9% during exercise) were higher. The intra-individual variability of Fatmax and fat oxidation rates was high (CV>15%), regardless of the data analysis approach employed. Further research on the determinants of the variability of Fatmax and fat oxidation rates is required.

Role of glutamate in neuron-glia metabolic coupling.

The coupling between synaptic activity and glucose utilization (neurometabolic coupling) is a central physiologic principle of brain function that has provided the basis for 2-deoxyglucose-based functional imaging with positron emission tomography. Approximately 10 y ago we provided experimental evidence that indicated a central role of glutamate signaling on astrocytes in neurometabolic coupling. The basic mechanism in neurometabolic coupling is the glutamate-stimulated aerobic glycolysis in astrocytes, such that the sodium-coupled reuptake of glutamate by astrocytes and the ensuing activation of the Na(+)-K(+) ATPase triggers glucose uptake and its glycolytic processing, which results in the release of lactate from astrocytes. Lactate can then contribute to the activity-dependent fueling of the neuronal energy demands associated with synaptic transmission. Analyses of this coupling have been extended in vivo and have defined the methods of coupling for inhibitory neurotransmission as well as its spatial extent in relation to the propagation of metabolic signals within the astrocytic syncytium. On the basis of a large body of experimental evidence, we proposed an operational model, "the astrocyte-neuron lactate shuttle." A series of results obtained by independent laboratories have provided further support for this model. This body of evidence provides a molecular and cellular basis for interpreting data that are obtained with functional brain imaging studies.

Post-exercise parasympathetic reactivation and sensibility to hypoxia

Introduction Exposure to hypoxia leads to several reactions of the organism, which try to compensate the reduced oxygen level in the blood. Acute response is characterized by an increase in pulmonary ventilation (Hypoxia Ventilatory Response, HVR) and in cardiac output (cardiac response to hypoxia). Heart rate (HR) at rest and during exercise is higher at high altitude than at sea level, whereas HRmax is lower. These cardiac adaptations are partially explained by an increased sympathetic stimulation associated with a reduced parasympathetic tone (12). The precise mechanisms of HRmax decline in acute hypoxia are however still to be identified, although several hypothesis have been suggested, such as a direct effect of hypoxia on the electrophysiological properties, an influence of skeletal maximal VO2 or a modulation of the autonomic nervous system (8). Some authors have reported that endurance trained athletes present an increased sensitivity to hypoxia shown by a large reduction in VO2max and an important decrease in arterial saturation. (9,11, 13) A hypoxia test can assess the sensibility of chemoreceptors to the reduction of oxygen by calculating hypoxic ventilatory and cardiac responses, knowing that low sensibility is correlated with poor acclimatization. Two parameters results from the differences in ventilation (and heart rate) divided by the difference in the arterial oxygen saturation between normoxia and hypoxia (18). Objective The hypothesis tested by this study is that parasympathetic reactivation after moderate effort in hypoxic condition can be used as a marker of individual sensibility to hypoxia. Parasympathetic reactivation is a marker of vagal tone that predict endurance capacity and aerobic fitness (2,7). Methods Subjects This study uses data obtained from two groups of athletes participating into two larger studies about adaptation to hypoxia. One group is composed of elite athletes (Swiss ski mountaineering team), the other one of mid-level athletes (ski mountaineering amateurs). The particularity of this target population is that they often train at high altitude, and therefore could show a better response to hypoxia than athleltes of other disciplines. Protocol The athletes performed a submaximal exercise (6min run at 9 km/h, flat) followed by 10 min of seated rest either in an hypoxic chamber (simulated altitude of 3000m) or in normoxic conditions. During the resting phase parasympathetic reactivation was assessed by beat-to-beat HR measurements.A test of tolerance to altitude was also performed. Analysis Parasympathetic reactivation, assessed by the calculation of the root mean square of successive differences in the R-R intervals (RMSSD)(4), is compared to individual responses at altitude, in order to appreciate the correlation between the two phenomena.

Adaptation of aerobically growing Pseudomonas aeruginosa to copper starvation.

Restricted bioavailability of copper in certain environments can interfere with cellular respiration because copper is an essential cofactor of most terminal oxidases. The global response of the metabolically versatile bacterium and opportunistic pathogen Pseudomonas aeruginosa to copper limitation was assessed under aerobic conditions. Expression of cioAB (encoding an alternative, copper-independent, cyanide-resistant ubiquinol oxidase) was upregulated, whereas numerous iron uptake functions (including the siderophores pyoverdine and pyochelin) were expressed at reduced levels, presumably reflecting a lower demand for iron by respiratory enzymes. Wild-type P. aeruginosa was able to grow aerobically in a defined glucose medium depleted of copper, whereas a cioAB mutant did not grow. Thus, P. aeruginosa relies on the CioAB enzyme to cope with severe copper deprivation. A quadruple cyo cco1 cco2 cox mutant, which was deleted for all known heme-copper terminal oxidases of P. aeruginosa, grew aerobically, albeit more slowly than did the wild type, indicating that the CioAB enzyme is capable of energy conservation. However, the expression of a cioA'-'lacZ fusion was less dependent on the copper status in the quadruple mutant than in the wild type, suggesting that copper availability might affect cioAB expression indirectly, via the function of the heme-copper oxidases.