Operation Everest III: energy and water balance

We hypothesized that hypoxia decreases energy intake and increases total energy requirement and, additionally, that decreased barometric pressure increases total water requirement. Energy and water balance was studied over 31 days in a hypobaric chamber at 452-253 Torr (corresponding to 4,500-8,848 m altitude), after 7 days acclimatization at 4,350 m. Subjects were eight men, age 27+/-4 years (mean+/-SD), body mass index 22.9+/-1.5 kg/m(2). Food and water intake was measured with weighed dietary records, energy expenditure and water loss with labelled water. Insensible water loss was calculated as total water loss minus urinary and faecal water loss. Energy intake at normoxia was 13.6+/-1.8 MJ/d. Energy intake decreased from 10.4+/-2.1 to 8.3+/-1.9 MJ/d (

Structure and reactivity of surface oxides on Pt(110) during catalytic CO oxidation

We present the first structure determination by surface x-ray diffraction during the restructuring of a model catalyst under reaction conditions, i.e., at high pressure and high temperature, and correlate the restructuring with a change in catalytic activity. We have analyzed the Pt(110) surface during CO oxidation at pressures up to 0.5 bar and temperatures up to 625 K. Depending on the O2/CO pressure ratio, we find three well-defined structures: namely, (i) the bulk-terminated Pt(110) surface, (ii) a thin, commensurate oxide, and (iii) a thin, incommensurate oxide. The commensurate oxide only appears under reaction conditions, i.e., when both O2 and CO are present and at sufficiently high temperatures. Density functional theory calculations indicate that the commensurate oxide is stabilized by carbonate ions (CO2−3). Both oxides have a substantially higher catalytic activity than the bulk-terminated Pt surface

Setup for human sera MALDI profiling: The case of rhEPO treatment

The implementation of high-throughput technologies based on qualitative and quantitative methodologies for the characterization of complex protein mixtures is increasingly required in clinical laboratories. MALDI profiling is a robust and sensitive technology although the serum high dynamic range imposes a major limitation hampering the identification of less abundant species decreasing the quality of MALDI profiling. A setup to improve these parameters has been performed for recombinant human erythropoietin (rhEPO) monitoring in serum, analyzing the effects of two commercially available columns (MARS Hu7 and Hu14) for immunodepletion, and two matrices (\u3b1-cyano-4-hydroxycinnamic acid and 2\u2032,4\u2032-dihydroxyacetophenone) for peak quality improvement. The immunodepletion capability of both columns was determined by 2-D DIGE, which precisely revealed the efficacy of Hu14 in protein removal and the serum dynamic range decrement. In addition, the type of matrix, the sample dilution, and the efficacy of optimized parameters were used for serum profiling of ten healthy subjects before and after rhEPO treatment. The principal component analysis indicates that a combination of Hu14 column and 2\u2032,4\u2032-dihydroxyacetophenone matrix increases data quality allowing the discrimination between treated and untreated samples, making serum MALDI profiling suitable for clinical monitoring of rhEP

Induction of erythroferrone in healthy humans by micro-dose recombinant erythropoietin or high-altitude exposure

The erythropoietin (Epo)-erythroferrone (ERFE)-hepcidin axis coordinates erythropoiesis and iron homeostasis. While mouse studies have established that Epo-induced ERFE production represses hepcidin synthesis by inhibiting hepatic BMP/SMAD signaling, evidence for the role of ERFE in humans is limited. To investigate the role of ERFE as a physiological erythroid regulator in humans, we conducted two studies: first, 24 males received six injections of saline (placebo), recombinant Epo (rhEpo) 20 UI kg-1 (micro-dose) or 50 UI kg-1 (low-dose). Second, we quantified ERFE in 22 subjects exposed to high altitude (3800 m) for 15 hours. In the first study, total hemoglobin mass (Hbmass) increased after low- but not after micro-dose injections, when compared to placebo. Serum ERFE levels were enhanced by rhEpo, remaining higher than after placebo for 48 (micro-dose) or 72 hours (low-dose) post-injections. Conversely, hepcidin levels decreased when Epo and ERFE arose, before any changes in serum iron parameters occurred. In the second study, serum Epo and ERFE increased at high altitude. The present results demonstrate that in healthy humans ERFE responds to slightly increased Epo levels not associated with Hbmass expansion and down-regulates hepcidin in an apparently iron-independent way. Notably, ERFE flags micro-dose Epo, thus holding promise as novel anti-doping biomarker

Skeletal Muscle Myofibrillar and Sarcoplasmic Protein Synthesis Rates Are Affected Differently by Altitude-Induced Hypoxia in Native Lowlanders

As a consequence to hypobaric hypoxic exposure skeletal muscle atrophy is often reported. The underlying mechanism has been suggested to involve a decrease in protein synthesis in order to conserve O2. With the aim to challenge this hypothesis, we applied a primed, constant infusion of 1-13C-leucine in nine healthy male subjects at sea level and subsequently at high-altitude (4559 m) after 7–9 days of acclimatization. Physical activity levels and food and energy intake were controlled prior to the two experimental conditions with the aim to standardize these confounding factors. Blood samples and expired breath samples were collected hourly during the 4 hour trial and vastus lateralis muscle biopsies obtained at 1 and 4 hours after tracer priming in the overnight fasted state. Myofibrillar protein synthesis rate was doubled; 0.041±0.018 at sea-level to 0.080±0.018%⋅hr−1 (p<0.05) when acclimatized to high altitude. The sarcoplasmic protein synthesis rate was in contrast unaffected by altitude exposure; 0.052±0.019 at sea-level to 0.059±0.010%⋅hr−1 (p>0.05). Trends to increments in whole body protein kinetics were seen: Degradation rate elevated from 2.51±0.21 at sea level to 2.73±0.13 µmol⋅kg−1⋅min−1 (p = 0.05) at high altitude and synthesis rate similar; 2.24±0.20 at sea level and 2.43±0.13 µmol⋅kg−1⋅min−1 (p>0.05) at altitude. We conclude that whole body amino acid flux is increased due to an elevated protein turnover rate. Resting skeletal muscle myocontractile protein synthesis rate was concomitantly elevated by high-altitude induced hypoxia, whereas the sarcoplasmic protein synthesis rate was unaffected by hypoxia. These changed responses may lead to divergent adaptation over the course of prolonged exposure

Laue-DIC : a new method for improved stress field measurements at the micrometer scale

A better understanding of the effective mechanical behavior of polycrystalline materials requires an accurate knowledge of the behavior at a scale smaller than the grain size. The X-ray Laue microdiffraction technique available at beamline BM32 at the European Synchrotron Radiation Facility is ideally suited for probing elastic strains (and associated stresses) in deformed polycrystalline materials with a spatial resolution smaller than a micrometer. However, the standard technique used to evaluate local stresses from the distortion of Laue patterns lacks accuracy for many micromechanical applications, mostly due to (i) the fitting of Laue spots by analytical functions, and (ii) the necessary comparison of the measured pattern with the theoretical one from an unstrained reference specimen. In the present paper, a new method for the analysis of Laue images is presented. A Digital Image Correlation (DIC) technique, which is essentially insensitive to the shape of Laue spots, is applied to measure the relative distortion of Laue patterns acquired at two different positions on the specimen. The new method is tested on an in situ deformed Si single-crystal, for which the prescribed stress distribution has been calculated by finite-element analysis. It is shown that the new Laue-DIC method allows determination of local stresses with a strain resolution of the order of 10-5