Breath water-based doubly labelled water method for the noninvasive determination of CO2 production and energy expenditure in mice

ABSTRACT

We explored a novel doubly labelled water (DLW) method based on breath water (BW-DLW) in mice to determine whole body CO₂ production and energy expenditure noninvasively. The BW-DLW method was compared to the DLW based on blood plasma. Mice (n?=?11, 43.5?±?4.6?g body mass (BM)) were administered orally a single bolus of doubly labelled water (1.2?g H₂¹⁸O kg BM^?1 and 0.4?g ²H₂O kg BM^?1, 99 atom% (AP) ¹⁸O or ²H). To sample breath water, the mice were placed into a respiration vessel. The exhaled water vapour was condensed in a cold-trap. The isotope enrichments of breath water were compared with plasma samples. The ²H/¹H and ¹⁸O/¹⁶O isotope ratios were measured by means of isotope ratio mass spectrometry. The CO₂ production (RCO₂) was calculated from the ²H and ¹⁸O enrichments in breath water and plasma over 5 days. The isotope enrichments of breath water vs. plasma were correlated (R²?=?0.89 for ²H and 0.95 for ¹⁸O) linearly. The RCO₂ determined based on breath water and plasma was not different (113.2?±?12.7 vs. 111.4?±?11.0?mmol?d^–1), respectively. In conclusion, the novel BW-DLW method is appropriate to obtain reliable estimates of RCO₂ avoiding blood sampling.     

Study of the mechanism of the negative secondary ionic emission by selective superficial oxidation and adsorption

With the aid of a speed analyser mass spectrograph able to function in an ultra vacuum, it was shown in previous work by conducting a study of the speed of ejection of secondary ions O^? emitted under the impact of ions K⁺ by copper target, that under certain experimental conditions at least two different origins of this emission could be demonstrated. The hypothesis that we thus adopted was that the O^? ions having the greatest ejection speed could originate from the layer adsorbed on the surface, whereas the O^? ions having the weakest ejection speed could originate from the oxide. In order to confirm this hypothesis, we conducted the following experiments.We oxidized a copper target with a natural isotope ¹⁸₈O of oxygen. The spectrogram of the negative secondary emission involved then, in addition to the ions of the adsorbed layers (H^?, C^?, CH^?, ¹⁶₈O^?, ¹⁶₈O^?,...) the ion ¹⁶₈OH^?, which could only originate from a chemical compound formed at the time of the reaction of the oxidation.In a second series of experiments, we introduced molecular oxygen ¹⁸₈O₂ into the system, beginning with an initial pressure of 10^?8 torr up to a pressure of 10^?5 torr. The mass spectrogram again contained, over and above the aforementioned ions, the ion ¹⁸₈O^?. Here this ion could only originate from the adsorbed layers, since the experimental conditions favored the chemical and physical adsorptions.In addition, the energy analysis of the ions ¹⁸₈O^? obtained in the two instances allows us to say that the ion O^? originating from the rupture of the chemical junction Cu₂O has a weaker speed of ejection than the ion O^? originating from the adsorbed layer of gas. In conclusion, the experiment shows that the energy transfer from the incident particle to the ejected particle, by means of the atoms in the target, leads to a speed of ejection which is discrete but weak, in the case of the particle originating from the rupture of a chemical junction; whereas in the case of particles originating from the adsorbed layers of gas, the speeds of ejection are greater and have a widespread distribution.     

Infrared spectroscopy of CO2 isotopologues from 2200 to 7000 cm−1: I—Characterizing experimental uncertainties of positions and intensities

Fourier transform spectra of carbon dioxide enriched in ¹⁷O and ¹⁸O have been recorded in LADIR (Paris, France) with the Bruker IFS 125-HR between 2000 and 9000 cm^?1 at an unapodized resolution of 0.0056 cm^?1. In this contribution we present a total of 1861 line positions and intensities retrieved for 46 bands of ¹²CO₂ isotopologues between 2000 and 7000 cm^?1 including the ¹⁶O¹²C¹⁶O, ¹⁷O¹²C¹⁷O, ¹⁸O¹²C¹⁸O, ¹⁶O¹²C¹⁸O, ¹⁶O¹²C¹⁷O, and ¹⁷O¹²C¹⁸O species. The objective of this first part of work was to examine the absolute concentrations of various CO₂ isotopologues in the sample by comparing our measurements of the line intensities to those available in literature and in HITRAN 2008. The accuracy of the determined abundances of the various isotopologues in our sample could be estimated to be about 2–7% for all above listed isotopologues except for ¹⁷O¹²C¹⁷O for which the accuracy on abundance is estimated to be around 20%. The accuracy of the line positions retrieval is better than 0.1×10^?3 cm^?1. We estimate the relative uncertainty of the line intensities retrieval to be around 1–2% (except for very weak lines), whereas the absolute accuracy to be around 3–15% depending mainly on the accuracy of the determination of the partial pressures for the various isotopologues in our sample, but also on the line strengths and on the spectral region. The estimation of the partial pressures of the various CO₂ isotopologues is crucial for retrieving absolute values of line intensities, but this is not an easy task because there are no absolute calibration standards for CO₂ intensities. Among the results obtained in this work, measurements are obtained for the first time for the 10011–00001 band of ¹⁷O¹²C¹⁷O, ¹⁶O¹²C¹⁷O, ¹⁶O¹²C¹⁸O, and ¹⁸O¹²C¹⁸O species, for the 00011–00001 band of ¹⁷O¹²C¹⁸O, and for the 2001i–00001 (i=1, 2, and 3) bands of the ¹⁶O¹²C¹⁷O isotopologue.     

Analysis of the Fourier transform spectra of 12C17O2 and 12C17O18O: The ν2 (15 μm) region

The vibration-rotation spectra of the ν₂ fundamental of ¹²C¹⁷O₂ and ¹²C¹⁷O¹⁸O have been obtained by Fourier transform spectroscopy at 0.05 cm^?1 resolution. The data were fitted by a least-squares routine to obtain a number of the molecular constants. The band center for ¹²C¹⁷O₂ lies at 662.0716 cm^?1 while that for ¹²C¹⁷O¹⁸O is at 659.7057 cm^?1. The difference bands ν₁ - ν₂ have also been observed for the two molecular species.     

Infrared spectrum of isotopic carbon dioxide in the region of bending fundamental ν2

Infrared absorption spectra of ¹³C¹⁶O₂, ¹³C¹⁸O₂, ¹⁶O¹³C¹⁷O, ¹⁶O¹³C¹⁸O, and ¹⁶O¹²C¹⁸O have been measured in the wavenumber region 570–780 cm^?1 with a spectral resolution of about 0.005 cm^?1. The data were recorded at room temperature with a Fourier transform spectrometer using a ¹³C-enriched sample of carbon dioxide. The fundamentals ν₂ and several “hot” bands have been identified and effective molecular constants have been derived.     

Infrared spectrum of CO2 in the region of the bending fundamental ν2

The infrared spectrum of CO₂ in the region 540–830 cm^?1 has been studied with a Fourier spectrometer at a resolution of 0.010 cm^?1. In addition to the fundamental ν₂, more than 10 “hot” band transitions of ¹²C¹⁶O₂ have been identified. The rotational constants involved have been derived. Special care has been taken in obtaining accurate constants for the level 01¹0. The ν₂ fundamentals of the isotopic molecules ¹³C¹⁶O₂, ¹⁶O¹²C¹⁸O, and ¹⁶O¹²C¹⁷O have also been observed in a natural sample.     

The CO coadsorption and reactions of sulfur,hydrogen and oxygen on clean and sulfided Mo(100) and on MoS2(0001) crystal faces

The chemisorption and reactivity of O₂ and H₂ with the sulfided Mo(100) surface and the basal (0001) plane of MoS₂ have been studied by means of Thermal Desorption Spectroscopy (TDS), Auger Electron Spectroscopy (AES) and Low Energy Electron Diffraction (LEED). These studies have been carried out at both low (10^?8–10^?5Torr) and high (1 atm) pressures of O₂ and H₂. Sulfur desorbs from Mo(100) both as an atom and as a diatomic molecule. Sulfur adsorbed on Mo(100) blocks sites of hydrogen adsorption without noticeably changing the hydrogen desorption energies. TDS of ¹⁸O coadsorbed with sulfur on the Mo(100) surface produced the desorption of SO at 1150 K, and of S, S₂ and O, but not SO₂. A pressure of 1 × 10^?7 Torr of O₂ was sufficient to remove sulfur from Mo(100) at temperatures over 1100 K. The basal plane of MoS₂ was unreactive in the presence of 1 atm of O₂ at temperatures of 520 K. Sputtering of the MoS₂ produced a marked uptake of oxygen and the removal of sulfur under the same conditions.     

The behaviour of carbon species produced by CO disproportionation on Ru(1, 1, 10) and Ru(001) surfaces

The behaviour of adsorbed CO on Ru(001) flat and Ru(l,1,10) stepped surfaces in the CO pressure range between 10^?6 and 10¹ Pa has been investigated by TDS, AES, LEED and UPS. The disproportionation of CO proceeds rapidly on the stepped surface and its apparent activation energy was obtained to be 20 kJ mol^?1 at nearly zero coverage. The carbon species produced by CO disproportionation show non-uniform reactivity with ¹⁸O₂ and provide four CO desorption peaks in TPR spectra, which are assigned to α-C¹⁸O,ß-C¹⁸O and those derived from carbidic and graphitic carbons. At smaller carbon coverage, only α-CO and β-CO were observed, but with increasing coverage the amount of ß-CO reaches a maximum and carbidic carbon is newly formed. Further increase of carbon deposition gives graphitic carbon. The conversion from carbidic to graphitic carbon and the dissolution into the bulk took place upon heating to 1000 K. It is remarkable that very active carbon species are converted to molecular CO through the reaction with O₂ even at low temperature such as 200 K. It was also confirmed that active carbon species are formed on Ru surface during COH₂ reaction.     

Basic studies of the oxygen surface chemistry of silver: Chemisorbed atomic and molecular species on pure Ag(111)

The interaction of oxygen with Ag(111) has been studied over the pressure range 10^?2?1.0 Torr. Thermal desorption measurements using isotopically labelled molecules unambiguously establish the presence of a stable chemisorbed dioxygen species which co-exists with adsorbed atomic oxygen. Dissolved oxygen undergoes exchange with the latter species but not with the former. The maximum dioxygen population is found to be markedly sensitive to gas dosing pressure; a model is proposed which accounts for these observations and for related observations on alkali-doped Ag. XP and UP spectral features can be correlated with the two types of oxygen species; angle-resolved XP and Auger spectra indicate that O₂ (a) resides on the metal surface whereas O(a) is located within the surface. The XP spectra also suggest that in the case of O₂(a) the molecular axis may lie perpendicular to the surface.     

Quantum chemical study of the (Z)-2-penten-1-ol (HOCH2–CH = CHCH2CH3) + OH + O2 reactions

ABSTRACT

The mechanism and products of the reaction of (Z)-2-penten-1-ol [(Z)-PO21] with OH radical in the presence of O₂ have been elucidated by using high-level quantum chemical methods CCSD(T)/6-311+G(d,p)//BH&;HLYP/6-311++G(d,p). The calculations clearly indicate that addition channels contribute maximum to the total reaction and H-abstraction channels can be neglected at temperatures of 220–500 K. The rate constant for the reaction of OH radical with (Z)-PO21 at 298 K is computed to be 1.22 × 10^?10 cm³ molecule^?1 s^?1, which is in stronger agreement with the previously reported experimental values. The kinetic data obtained over the temperature range 220?500 K are used to derive an non-Arrhenius expression: k = 3.69 × 10^?13 × exp(1763.7/T) cm³ molecule^?1 s^?1. For the reaction of (Z)-PO21with OH radical in the presence of O₂, the major primary reaction products found in this study are propanal [CH₃CH₂C(O)H] and glycolaldehyde [HOCH₂C(O)H], whereas formaldehyde [HC(O)H], 2-hydroxybutanal [CH₃CH₂CH(OH)C(O)H] and the epoxide P18 are anticipated to be minor products. The calculated results are consistent with the recent experimental observations.     

A new Technique for Measurement of Myocardial O2-Utilization

The coronary reserve of mammalian hearts is significantly heterogeneous. From this phenomenon we conclude on a heterogeneous energy-demand, i.e., ATP-demand and therefore on a nonuniform ischemic tolerance of cardiomyocytes.

Our aim was to establish a method for direct quantification of cardiomyocyte energy production. According to Langendorff, 10 isolated rabbit hearts were perfused with oxygen enriched Krebs-Henseleit solution. Using the stable oxygen isotope ¹⁸O₂, respiratory water of 7 hearts was labelled, and samples were taken from the coronary venous effluent. Defined cardiac tissue areas were lyophylized. Using the guanidine-hydrochloride technique, μl-water samples from the tissue and the coronary venous effluent were quantitatively converted to CO₂. With the help of mass-spectrometry the δ¹⁸O/¹⁶O-isotope ratios were determined and related to the SMOW-scale.

Compared to control hearts, a significant shift to higher SMOW-values within respiratory water from ¹⁸O-labelled hearts was detected (mean = 14.61%). Control hearts (maximal scatter = 1.42%) as well as ¹⁸O-labelled hearts (4.06%) showed high reproducibilit, of the method. With the employed experimental setup, significant regional differences were not detected. The kinetics of the coronary venous effluent showed a tendency toward saturation with H₂ ¹⁸O within 2 min after starting the ¹⁸O₂-perfusion. After 50 s perfusion increase in SMOW-values reached statistical significance.     

Isotope effects in Raman spectra of crystalline alkali-metal chlorates and bromates

Halogen and oxygen atom isotope effects have been observed in Raman spectra of single crystal NaClO₃, KClO₃, NaBrO₃, and KBrO₃. Orientational splitting of ³⁵Cl¹⁶O₂¹⁸O^? and ³⁷Cl¹⁶O₂¹⁸O^? ion vibrational modes was observed in KClO₃. Splitting of the v₁ mode of ⁷⁹Br and ⁸¹Br isotopes of singly substituted ¹⁷O and ¹⁸O bromate ions in NaBrO₃ and KBrO₃ is on the order of 1.5 cm^?1 in agreement with a calculation of isotopic frequencies. However, the predicted splitting between v₁ of the major isotopes, ⁷⁹Br¹⁶O₃^? and ⁸¹Br¹⁶O₃^?, was not observed, and the results of a band contour analysis suggest that a single k = 0 phonon is derived from the totally symmetric stretching mode of both species.     

Mathematical Modelling of the Role of Intra- and Extracellular Activity of Carbonic Anhydrase and Membrane Permeabilities of HCO3, H2O and CO2 in 18O Exchange

Abstract

Numerical simulation of ¹⁸O exchange between CO₂, H₂O and HCO₃ ^? explains the ratio mass 46/mass 44 (=C¹⁸O¹⁶O/C¹⁶O₂) measured by mass spectrometry to approximately 1% relative mean difference. In the presence of intact red blood cells the reaction takes place extra- and intracellularly at different reaction rates. Because CO₂ hydration/dehydration is accelerated intracellularly by carbonic anhydrase, a difference in intra- and extracellular concentration of labelled reactants occurs. The ensuing transfer of reactants across the cell membrane depends on their membrane permeabilities which are approximately P_{CO 2} ? 2 cm/s, P_{H 2 O} ? 0.002 cm/s and P_{HCO 3} ? 0.00015 cm/s (values from the literature). We found that the numerical simulation is affected most by P_{HCO 3} . The influence of the other permeabilities is at least ten times less. Therefore within the range of normal literature values, P_{HCO 3} is the only permeability that has a rate limiting effect on ¹⁸O exchange. This is why, in turn, P_{HCO 3} can be derived from an experimentally determined time course of mass 46/mass 44 by a fitting procedure. Another crucial parameter that can be estimated from the experimental results is the intraerythrocytic carbonic anhydrase activity A_i .     

Influence of nanocrystalline phases on the electrical properties of lithium titanate phosphate glass ceramics mixed with Ga2O3 nanocrystals

Several glass ceramic compositions dispersed with Ga₂O₃ nanocrystals, in the series samples (100???x)[0.4Li₂O–0.1TiO₂–0.5P₂O₅]?+?xGa₂O₃ with x?=?0, 2, 4, 6, 8, and 10?mol% of Ga₂O₃ were synthesized via high-energy ball milling technique and labeled as lithium gallium titanate phosphate glass (LTPG _x ) (x is the mol% of Ga₂O₃ nanocrystals). The compositions have been selected on the basis of thermal stability data obtained from differential thermal analysis. X-ray diffraction studies indicate nanocrystalline phase formation in the controlled crystallized glasses. The variation of electrical conductivity was explained in the light of growth of nanocrystalline phases. The best bulk conductivity (σ?=?7.03?×?10^?4?S?cm^?1, at 303?K) was achieved by the sample containing 8?mol% of Ga₂O₃ nanocrystals content, labeled as LTPG₈ sample. The activation energy for conduction (E_{a σ} ) is obtained from the temperature dependent of conductivity data, which is fitted to Arrhenius equation. The single super curve in the scaling spectra suggested the temperature-independent relaxation phenomenon.     

17O12C17O and 18O12C17O spectroscopy in the 1.6 μm region

Near infrared spectra of a carbon dioxide sample enriched with oxygen-17 have been recorded using a high-resolution continuous scan Fourier transform interferometer fitted with a femto OPO/Idler laser source. Cavity enhanced absorption has been achieved in a static gas cell allowing an optimal rms noise equivalent absorption of 1.2?×?10^?10?cm^?1?Hz^?1/2 per spectral element to be reached, corresponding to α_min?=?10^?8?cm^?1. Spectra were calibrated against acetylene reference line positions. Three bands in the 3ν₁?+?ν₃ tetrad in both ¹²C¹⁷O₂ and ¹²C¹⁷O¹⁸O have been identified and rotationally analyzed, as well as some related hot bands, eight of which are newly reported and three with their analysis updated compared with a preliminary report (X. de Ghellinck d’Elseghem Vaernewijck et al., Chem. Phys. Lett. 514, 29 (2011)).     

A diode laser spectrometer for symmetry selective detection of ozone isotopomers

A tunable diode laser absorption spectrometer operating in the 10 μm range is described, which for the first time permits simultaneous detection and quantification of the five naturally most abundant ozone isotopomers: ¹⁶O₃, ¹⁶O¹⁶O¹⁸O, ¹⁶O¹⁸O¹⁶O, ¹⁶O¹⁶O¹⁷O, and ¹⁶O¹⁷O¹⁶O. Ozone samples of 25 μmole size are analysed with an estimated accuracy of 6‰ (2σ). This level of accuracy is demonstrated by comparing spectroscopically determined isotopologue enrichments of ¹⁶O₂ ¹⁷O and ¹⁶O₂ ¹⁸O with mass spectrometer measurements. Samples for the comparison were generated from natural oxygen in an electric discharge under two different pressure conditions. The precision obtained is sufficient to study both the isotopic and the symmetry dependence of the unique oxygen isotope anomaly in ozone formation, which shows isotopomer specific fractionation values well in the 10% range. PACS 42.60.By; 42.55.Px; 33.20.Ea     

The 5v 3 bands of 18O enriched ozone: line positions of 16O16O18O, 16O18O16O, 16O18O18O and 18O16O18O

The four 5v ₃ bands of ¹⁸O enriched ozone have been observed and analysed for the first time. Two species (¹⁶O¹⁸O¹⁶O and ¹⁸O¹⁶O¹⁸O) belong to the C_2v symmetry group and two other (¹⁸O¹⁸O¹⁶O and ¹⁶O¹⁶O¹⁸O) to the C_s symmetry group. They have been recorded at a resolution of 0.008 cm^?1 with a pathlength of 32.16 m. Despite the very weak absorptions observed, almost 250 energy levels have been derived for each of the 4 species, with J ? 35 and K _a ? 13, and suitable sets of Hamiltonian parameters have been determined. For 3 species it has been necessary to account for the resonance between the (005) and (311) states to correctly reproduce the spectra observed. These resonances, anharmonic for C_2v, and hybrid (both anhar-monic and Coriolis) for C_s symmetry confirm the accidentally extremely strong coupling between the (005) and (311) states for ¹⁶O₃, due in that case to the very close distance between unperturbed energy levels. This work also confirms the excellent prediction of band centres of these four species derived from the recently determined isotopically invariant molecular potential function.     

Infrared Spectra of the Anion-Radicals of Benzophenone and Some of Its Isotopic Isomers

Abstract

Band assignment of the infrared spectra of the anion-radicals of benzophenone-d_O, -d₁₀ and ¹⁸O has been given on the basis of isotopic shifts. The frequency of the ν_C=O band decreases by ca. 270 cm^?1 with the transformation of neutral keton into anion-radical, due to the strong electron-withdrawing character of the carbonyl group; frequencies of the other modes decrease slightly, down to 30 cm^?1.     

Experimental and ab initio structure of BrN02

Abstract

The ν₂ fundamental bands of different isotopomers of BrN0₂ (⁷⁹Br¹⁵N¹⁶O₂, ⁸¹Br¹⁵N¹⁶O₂, ⁷⁹Br¹⁴N¹⁸O₂, and ⁷⁹Br¹⁴N¹⁶O¹⁸O) located around 13 µm were recorded using highresolution Fourier transform infrared spectrometry. More than 8000 lines of all these isotopomers were reproduced using a Watson-type A-reduced Hamiltonian with a rootmean-square deviation of better than 7×10^?4 cm^?1 for the four isotopomers. Rotational and centrifugal distortion constants for the ν₂=1 states as well as for the vibrational ground states of these isotopomers were determined. For the first time, an analysis of the ground-state rotational constants obtained in this study combined with the constants obtained in our previous work on the ν₂ bands of ⁷⁹Br¹⁴N¹⁶O₂, and ⁸¹Br¹⁴N¹⁶O₂, has allowed us to calculate the r_m, structure of nitryl bromide. The structural parameters obtained were r_m(Br–N)=2.0118(l6) Å, r_m(N–O)=l.l956(12) Å and α(O–N–O)=131.02(12)Å. A new ab initio structure of nitryl bromide calculated at the CCSD(T)/SDBaug-cc-pVQZ level of theory is presented and was found to be in fair agreement with the experimental structure.     

Mössbauer studies of phosphate glasses for the immobilisation of toxic and nuclear wastes

Various iron-containing phosphate glasses were investigated by Mössbauer spectroscopy. Iron was found to occur predominantly as Fe³⁺ in all glasses, and largely occupied sites with distorted octahedral coordination for both redox states. Using a base glass of nominal composition 60 P₂O₅–40 Fe₂O₃ (mol%), stepwise molar replacement of Fe₂O₃ by (0.67 Na₂O?×?0.33 Al₂O₃) increased the redox ratio, Fe²⁺/ΣFe, from 0.13 at 40% Fe₂O₃ to 0.25 at 10% Fe₂O₃. The centre shift increased and quadrupole splitting decreased by up to ～20% over this range, interpreted as a decrease in the average distortion of Fe sites from cubic symmetry, and an increase in average iron coordination. Literature revealed that recoil-free fraction ratio f (Fe³⁺)?/?f (Fe²⁺)?≈?1.3 in iron phosphate glasses, and this was considered when assessing redox. Mössbauer parameters of these and other glasses demonstrated a combination of structural stability and compositional flexibility which makes them so suitable for waste immobilisation.