A new procedure to assess the energy requirements of lactation in Gambian women.

The combined 24-h energy expenditure (24-h EE) of mother and child was measured with a respiratory chamber (indirect calorimeter) in a group of 16 lactating Gambian women and was compared with that of a control group of 16 nonpregnant, nonlactating (NPNL) Gambian women. Breast-milk production (738 +/- 47 g/d: mean +/- SE) was adequate to allow a normal rate of growth of their 2-mo-old babies (28.0 +/- 2.4 g/d). The combined 24-h EE (mother and child) was higher (8381 +/- 180 kJ/d. P less than 0.001) than that of NPNL women (6092 +/- 121 kJ/d). Two-thirds of this differences could be attributed to the child's EE and one-third to a greater spontaneous physical activity of lactating women. The energy retained by the child for growth in conjunction with the calorimetric measurements allowed the calculation of the extra energy requirements for lactation, which were found to be 2100 kJ/d. These results confirm the values of the current dietary recommendations for lactation, based on the energy cost of milk production.

Study of the SRR1-gene family in Arabidopsis, yeast and mouse cells

Abstract: Light is a very important environmental cue for plants. In addition to the energy for photosynthesis, it also provides information that is essential for many processes including seed germination, seedlings development, neighbours detection or transition from the vegetative to the reproductive state. Plants evolved different photoreceptors, among which the phytochromes (PHY), which are red/far-red photoreceptors. This family is composed of 5 members in Arabidopsis thaliana, among which phyB plays the major role for detection of red light. Phytochromes are also able to reset the phase of the circadian clock, which is composed of a complicated network of genes able to produce rhythms of about 24 hours, even in constant conditions. SRR1 (Sensitivity to Red light Reduced) is a gene that was shown to act in the phyB pathway as well as in the circadian clock. It was proposed to play a role in the maintenance of rhythms of the core oscillator because of the circadian phenotype of the srr1 mutant in constant light and in constant darkness. In the present study, we present data confirming the role of SRR1 in the core oscillator. Moreover, we show that SRR1 levels are not limiting for circadian rhythms nor for light perception. We show that the protein levels, the sub-cellular localisation or the complex in which SRR1 is found are not regulated in a circadian manner. Orthologues of SRR1 exist in numerous eukaryotes, forming a new gene family. None of the members of this family have been described. Here, we present data suggesting that the mouse orthologue of SRR1 may not be required for oscillation of the circadian clock of mouse cells in culture. The yeast gene (called BER1 for Benomyl REsistant) was studied to understand the biochemical function of this gene family. Based on synthetic genetic screens, a role of Ber1 was inferred in microtubules dynamics, N-terminal acetylation of protein and proteasome biogenesis. The effect of Ber1 on microtubules was confirmed by the observation that the ber1Δ mutant is more resistant to microtubule-depolymerising drugs and microscopic examination of microtubules in ber 1 Δ mutants. Complementation assays of ber1 Δ mutants and srrl mutants failed to reveal any obvious functional conservation of the mouse, yeast and Arabidopsis orthologues. In conclusion, the SRR1 family might encode genes that either plays different roles in different organisms, or have similar biochemical function but are involved in diverse pathway. Résumé: La lumière est un des facteurs abiotiques les plus important pour les plantes. En plus de l'énergie fournie pour la photosynthèse, elle fourni également de l'information nécessaire pour différents processus comme la germination, le développement des jeunes plantules, la détection de plantes avoisinantes ou encore la transition entre le développement végétatif et reproductif. Plusieurs types de photorécepteurs sont apparus chez les plantes au cours de l'évolution, notamment les phytochromes (PHI, qui perçoivent la lumière rouge et rouge lointaine. Cette famille est composé de 5 membres chez Arabidopsis thaliana, parmi lesquels phyB est le principal récepteur pour la lumière rouge. Les phytochromes sont aussi utiles pour la synchronisation entre les cycles jour-nuit dus à la rotation de la terre et l'horloge circadienne. Cette dernière est composée d'un réseau compliqué qui permet la production de rythmes capables de perdurer même en conditions constantes. SRRI (Sensitivity to Red light Reduced) est un gène qui agit dans la voie de signalisation de phyB ainsi que dans l'horloge circadienne. Il a été proposé que SRRI joue un rôle dans la maintenance des rythmes de l'oscillateur principal à cause des phénotypes circadiens du mutant srrl observés en lumière et en obscurité continue. Dans ce travail, nous présentons des données confirmant le rôle de SRR1 dans l'oscillateur principal. Nous montrons que les niveaux d'expression de SRRI ne sont pas limitants pour les rythmes circadiens ou la perception de la lumière. Enfin, nous montrons que le niveau d'accumulation de la protéine, sa localisation subcellulaire ou encore la taille du complexe dans lequel SRRl est trouvé ne sont pas régulés de façon circadiennes. Des orthologues de SRRI existent chez de nombreux eucaryotes, formant une nouvelle famille de gènes. Aucun des membres de cette famille n'a été étudié avant ce travail. Nous présentons des données suggérant que l'orthologue de la souris n'est peut-être pas requis pour les oscillations de l'horloge circadienne de cellules de souris en culture. Le gène de la levure (appelé SERI pour Benomyl REsistant) a été étudié afin de mieux comprendre la fonction biochimique de cette famille de gène. Une analyse par crible synthétique léthal a révélé un rôle de Ber1 dans la dynamique des microtubules, l'acétylation des protéines en N-terminal et la biogenèse du protéasome. L'effet de Ber1 sur les microtubules a été confirmé par l'observation du mutant ber1 en présence de drogue capable de dépolymériser les microtubules. Celui-ci est plus résistant à ces drogues que le type sauvage. Des expériences de complémentation n'ont pas montré de conservation de la fonction entre SRRI et ses homologues de souris ou de levure. En conclusion, la famille SRRI code pour des gènes qui pourraient avoir soit des rôles différents selon les organismes, soit la même fonction biochimique mais qui serait utile pour des voies de signalisation différentes.

Protein energy malnutrition increases arginase activity in monocytes and macrophages.

BACKGROUND: Protein energy malnutrition is commonly associated with immune dysfunctions and is a major factor in susceptibility to infectious diseases. METHODS: In this study, we evaluated the impact of protein energy malnutrition on the capacity of monocytes and macrophages to upregulate arginase, an enzyme associated with immunosuppression and increased pathogen replication. RESULTS: Our results show that monocytes and macrophages are significantly increased in the bone marrow and blood of mice fed on a protein low diet. No alteration in the capacity of bone marrow derived macrophages isolated from malnourished mice to phagocytose particles, to produce the microbicidal molecule nitric oxide and to kill intracellular Leishmania parasites was detected. However, macrophages and monocytes from malnourished mice express significantly more arginase both in vitro and in vivo. Using an experimental model of visceral leishmaniasis, we show that following protein energy malnutrition, the increased parasite burden measured in the spleen of these mice coincided with increased arginase activity and that macrophages provide a more permissive environment for parasite growth. CONCLUSIONS: Taken together, these results identify a novel mechanism in protein energy malnutrition that might contributes to increased susceptibility to infectious diseases by upregulating arginase activity in myeloid cells.

Hémato-oncologie pédiatrique: de la biologie cellulaire aux traitements ciblés et individualisés [Pediatric hemato-oncology: from cellular biology to individualized targeted therapies].

Progresses in pediatric oncology over the last decades have been dramatic and allow current cure rates above 80%. There are mainly due to multicentre clinical trials aiming at optimizing chemotherapy protocols as well as local therapies in a stepwise approach. Most of the new anticancer drugs currently in development are based on targeted therapies, directed to specific targets present only in or on tumor cells, like growth factor receptors, mechanisms involved in proliferation, DNA repair, apoptosis, tumor invasion or angiogenesis. Concerning bone marrow transplantation also, new strategic approaches are in advanced development. They aim at reducing treatment induced toxicity and enhancing efficacy at the same time. This short paper would like to point out these new technologies, which should be known by the general practitioner.

Measuring cytoskeleton and cellular membrane mechanical properties by atomic force microscopy.

Atomic force microscope is an invaluable device to explore living specimens at a nanometric scale. It permits to image the topography of the sample in 3D, to measure its mechanical properties and to detect the presence of specific molecules bound on its surface. Here we describe the procedure to gather such a data set on living macrophages.

Pacing redistributes glycogen within the developing myocardium.

Electrical pacing at physiological rate induces myocardial remodeling associated with regional changes in workload, blood flow and oxygen consumption. However, to what extent energy-producing pathways are also modified within the paced heart remains to be investigated. Pacing could particularly affect glycogen metabolism since hypertrophy stimulates glycolysis and increased workload favors glucose over fat oxidation. In order to test this hypothesis, we used the embryonic chick heart model in which ventricular pacing rapidly resulted in thinning of the ventricle wall and thickening of the atrial wall. Hearts of stage 22HH chick embryos were submitted in ovo to asynchronous and intermittent ventricular pacing delivered at physiological rate during 24 h. The resulting alterations of glycogen content were determined in atrium, ventricle and conotruncus of paced and sham-operated hearts. Hemodynamic parameters of the paced and spontaneously beating hearts were derived from computerized image analysis of video recordings. With respect to sham, paced hearts showed a significant decrease in glycogen content (nmoles glucose units/microg protein; mean+/-S.D.) only in atrium (1.48+/-0.40 v 0.84+/-0.34, n=8) and conotruncus (0.75+/-0.28 v 0.42+/-0.23, n=8). Pacing decreased the end diastolic and stroke volumes by 34 and 44%, respectively. Thus, the rapid glycogen depletion in regions remote from the stimulation site appears to be associated with regional changes in workload and remodeling. These findings underscore the importance of the coupling mechanisms between metabolic pathways and myocardial remodeling in the ectopically paced heart.

Twenty-four-hour energy expenditure and basal metabolic rate measured in a whole-body indirect calorimeter in Gambian men.

By use of a respiration chamber, 24-hour energy expenditure (EE), diet-induced thermogenesis (DIT), and basal and sleeping EE were measured in 20 young rural Gambian men during the "hungry" season (weight, 60.8 +/- 1.4 kg) and in a group of 16 European men matched for body composition (weight, 66.9 +/- 1.9 kg). The 24-h EE was lower in Gambian than in European men (2047 +/- 46 vs 2635 +/- 74 kcal/d, p less than 0.001, respectively). Basal EE and sleeping EE were also lower in Gambian than in European men (1.05 +/- 0.02 vs 1.25 +/- 0.02 kcal/min and 1.0 +/- 0.02 vs 1.18 +/- 0.02 kcal/min, p less than 0.01, respectively). DIT was blunted in Gambian compared with European men (6.3 +/- 0.6% vs 12.1 +/- 0.5%, p less than 0.001 respectively). The net efficiency of walking was greater in Gambian than in European men (23.2 +/- 0.3% vs 20.1 +/- 0.4%, p less than 0.001, respectively). A low basal and sleeping EE, a reduced DIT, and a high work efficiency are important energy-sparing mechanisms in Gambian men, which allow them to cope with a marginal level of dietary intake during the hungry season.

Selected configuration interaction with truncation energy error and application to the Ne atom

Selected configuration interaction (SCI) for atomic and molecular electronic structure calculations is reformulated in a general framework encompassing all CI methods. The linked cluster expansion is used as an intermediate device to approximate CI coefficients BK of disconnected configurations (those that can be expressed as products of combinations of singly and doubly excited ones) in terms of CI coefficients of lower-excited configurations where each K is a linear combination of configuration-state-functions (CSFs) over all degenerate elements of K. Disconnected configurations up to sextuply excited ones are selected by Brown's energy formula, ΔEK=(E-HKK)BK2/(1-BK2), with BK determined from coefficients of singly and doubly excited configurations. The truncation energy error from disconnected configurations, Δdis, is approximated by the sum of ΔEKS of all discarded Ks. The remaining (connected) configurations are selected by thresholds based on natural orbital concepts. Given a model CI space M, a usual upper bound ES is computed by CI in a selected space S, and EM=E S+ΔEdis+δE, where δE is a residual error which can be calculated by well-defined sensitivity analyses. An SCI calculation on Ne ground state featuring 1077 orbitals is presented. Convergence to within near spectroscopic accuracy (0.5 cm-1) is achieved in a model space M of 1.4× 109 CSFs (1.1 × 1012 determinants) containing up to quadruply excited CSFs. Accurate energy contributions of quintuples and sextuples in a model space of 6.5 × 1012 CSFs are obtained. The impact of SCI on various orbital methods is discussed. Since ΔEdis can readily be calculated for very large basis sets without the need of a CI calculation, it can be used to estimate the orbital basis incompleteness error. A method for precise and efficient evaluation of ES is taken up in a companion paper

Basis set superposition error-counterpoise corrected potential energy surfaces : application to hydrogen peroxide ... X (X=F-, Cl-, Br-, Li+, Na+) complexes

Møller-Plesset (MP2) and Becke-3-Lee-Yang-Parr (B3LYP) calculations have been used to compare the geometrical parameters, hydrogen-bonding properties, vibrational frequencies and relative energies for several X- and X+ hydrogen peroxide complexes. The geometries and interaction energies were corrected for the basis set superposition error (BSSE) in all the complexes (1-5), using the full counterpoise method, yielding small BSSE values for the 6-311 + G(3df,2p) basis set used. The interaction energies calculated ranged from medium to strong hydrogen-bonding systems (1-3) and strong electrostatic interactions (4 and 5). The molecular interactions have been characterized using the atoms in molecules theory (AIM), and by the analysis of the vibrational frequencies. The minima on the BSSE-counterpoise corrected potential-energy surface (PES) have been determined as described by S. Simón, M. Duran, and J. J. Dannenberg, and the results were compared with the uncorrected PES

Determination of the direct band-gap energy of InAlAs matched to InP by photoluminescence excitation spectroscopy

A series of InxAl1-xAs samples (0.51≪x≪0.55)coherently grown on InP was studied in order to measure the band-gap energy of the lattice matched composition. As the substrate is opaque to the relevant photon energies, a method is developed to calculate the optical absorption coefficient from the photoluminescence excitation spectra. The effect of strain on the band-gap energy has been taken into account. For x=0.532, at 14 K we have obtained Eg0=1549±6 meV

The effect of counterpoise correction and relaxation energy term to the internal rotation barriers: application to the BF3 ...NH3 and C2H4 ...SO2 dimers

The relevance of the fragment relaxation energy term and the effect of the basis set superposition error on the geometry of the BF3⋯NH3 and C2H4⋯SO2 van der Waals dimers have been analyzed. Second-order Møller-Plesset perturbation theory calculations with the d95(d,p) basis set have been used to calculate the counterpoise-corrected barrier height for the internal rotations. These barriers have been obtained by relocating the stationary points on the counterpoise-corrected potential energy surface of the processes involved. The fragment relaxation energy can have a large influence on both the intermolecular parameters and barrier height. The counterpoise correction has proved to be important for these systems

A chemical Hamiltonian approach study of the basis set superposition error changes on electron densities and one- and two-center energy components

A comparision of the local effects of the basis set superposition error (BSSE) on the electron densities and energy components of three representative H-bonded complexes was carried out. The electron densities were obtained with Hartee-Fock and density functional theory versions of the chemical Hamiltonian approach (CHA) methodology. It was shown that the effects of the BSSE were common for all complexes studied. The electron density difference maps and the chemical energy component analysis (CECA) analysis confirmed that the local effects of the BSSE were different when diffuse functions were present in the calculations

Energy partitioning for "fuzzy" atoms

The total energy of molecule in terms of 'fuzzy atoms' presented as sum of one- and two-atomic energy components is described. The divisions of three-dimensional physical space into atomic regions exhibit continuous transition from one to another. The energy components are on chemical energy scale according to proper definitions. The Becke's integration scheme and weight function determines realization of method which permits effective numerical integrations

C-H···O H-bonded complexes: how does basis set superposition error change their potential-energy surfaces?

Geometries, vibrational frequencies, and interaction energies of the CNH⋯O3 and HCCH⋯O3 complexes are calculated in a counterpoise-corrected (CP-corrected) potential-energy surface (PES) that corrects for the basis set superposition error (BSSE). Ab initio calculations are performed at the Hartree-Fock (HF) and second-order Møller-Plesset (MP2) levels, using the 6-31G(d,p) and D95++(d,p) basis sets. Interaction energies are presented including corrections for zero-point vibrational energy (ZPVE) and thermal correction to enthalpy at 298 K. The CP-corrected and conventional PES are compared; the unconnected PES obtained using the larger basis set including diffuse functions exhibits a double well shape, whereas use of the 6-31G(d,p) basis set leads to a flat single-well profile. The CP-corrected PES has always a multiple-well shape. In particular, it is shown that the CP-corrected PES using the smaller basis set is qualitatively analogous to that obtained with the larger basis sets, so the CP method becomes useful to correctly describe large systems, where the use of small basis sets may be necessary

The hardness profile as a tool to detect spurious stationary points in the potential energy surface

The energy and hardness profile for a series of inter and intramolecular conformational changes at several levels of calculation were computed. The hardness profiles were found to be calculated as the difference between the vertical ionization potential and electron affinity. The hardness profile shows the correct number of stationary points independently of the basis set and methodology used. It was found that the hardness profiles can be used to check the reliability of the energy profiles for those chemical system