| 1. |
- Koefoed-Nielsen, Jacob, et al.
(författare)
-
Alveolar recruitment can be predicted from airway pressure-lung volume loops : an experimental study in a porcine acute lung injury model
- 2008
-
Ingår i: Critical Care. - : Springer Science and Business Media LLC. - 1364-8535 .- 1466-609X. ; 12:1, s. R7-
-
Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: Simple methods to predict the effect of lung recruitment maneuvers (LRMs) in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are lacking. It has previously been found that a static pressure-volume (PV) loop could indicate the increase in lung volume induced by positive end-expiratory pressure (PEEP) in ARDS. The purpose of this study was to test the hypothesis that in ALI (1) the difference in lung volume (DeltaV) at a specific airway pressure (10 cmH2O was chosen in this test) obtained from the limbs of a PV loop agree with the increase in end-expiratory lung volume (DeltaEELV) by an LRM at a specific PEEP (10 cmH2O), and (2) the maximal relative vertical (volume) difference between the limbs (maximal hysteresis/total lung capacity (MH/TLC)) could predict the changes in respiratory compliance (Crs), EELV and partial pressures of arterial O2 and CO2 (PaO2 and PaCO2, respectively) by an LRM. METHODS: In eight ventilated pigs PV loops were obtained (1) before lung injury, (2) after lung injury induced by lung lavage, and (3) after additional injurious ventilation. DeltaV and MH/TLC were determined from the PV loops. At all stages Crs, EELV, PaCO2 and PaO2 were registered at 0 cmH2O and at 10 cmH2O before and after LRM, and DeltaEELV was calculated. Statistics: Wilcoxon's signed rank, Pearson's product moment correlation, Bland-Altman plot, and receiver operating characteristics curve. Medians and 25th and 75th centiles are reported. RESULTS: DeltaV was 270 (220, 320) ml and DeltaEELV was 227 (177, 306) ml (P < 0.047). The bias was 39 ml and the limits of agreement were - 49 ml to +127 ml. The R2 for relative changes in EELV, Crs, PaCO2 and PaO2 against MH/TLC were 0.55, 0.57, 0.36 and 0.05, respectively. The sensitivity and specificity for MH/TLC of 0.3 to predict improvement (>75th centile of what was found in uninjured lungs) were for EELV 1.0 and 0.85, Crs 0.88 and 1.0, PaCO2 0.78 and 0.60, and PaO2 1.0 and 0.69. CONCLUSION: A PV-loop-derived parameter, MH/TLC of 0.3, predicted changes in lung mechanics better than changes in gas exchange in this lung injury model.
|
|
| 2. |
- Nielsen, Niels D, et al.
(författare)
-
Apneic oxygenation combined with extracorporeal arteriovenous carbon dioxide removal provides sufficient gas exchange in experimental lung injury
- 2008
-
Ingår i: ASAIO journal (1992). - 1058-2916 .- 1538-943X. ; 54:4, s. 401-405
-
Tidskriftsartikel (refereegranskat)abstract
- We hypothesized that apneic oxygenation, using an open lung approach, combined with extracorporeal CO2 removal, would provide adequate gas exchange in acute lung injury. We tested this hypothesis in nine anesthetized and mechanically ventilated pigs (85-95 kg), in which surfactant was depleted from the lungs by repeated lung lavage. After a lung recruitment maneuver, the tracheal tube was connected to 20 cm H2O continuous pressure (100% O2) for oxygenation of the blood. A pumpless membrane ventilator (interventional lung assist by Novalung) was connected in an arteriovenous shunt for CO2 removal. PaO2 and PaCO2 were recorded for 3.5 hours. PaO2 was 464 (403, 502) mm Hg (median and interquartile range) throughout the experiment. The O2 uptake through the lungs was 185 (164, 212) ml/min. PaCO2 increased asymptotic towards 60 mm Hg. The CO2 removal through the membrane ventilator was 180 (150, 180) ml/min. Thus, the method provided adequate gas exchange in this experimental model, suggesting that it might have potential as an alternative treatment modality in acute lung injury.
|
|
| 3. |
- Schael, S, et al.
(författare)
-
Precision electroweak measurements on the Z resonance
- 2006
-
Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
-
Forskningsöversikt (refereegranskat)abstract
- We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
|
|
| 4. |
- Aidas, Kestutis, et al.
(författare)
-
Gauge-origin independent magnetizabilities from hybrid quantum mechanics/molecular mechanics models: Theory and applications to liquid water
- 2007
-
Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614. ; 442:4-6, s. 322-328
-
Tidskriftsartikel (refereegranskat)abstract
- The theory of a hybrid quantum mechanics/molecular mechanics (QM/MM) approach for gauge-origin independent calculations of the molecular magnetizability using Hartree-Fock or Density Functional Theory is presented. The method is applied to liquid water using configurations generated from classical Molecular Dynamics simulation to calculate the statistical averaged magnetizability. Based on a comparison with experimental data, treating only one water molecule quantum mechanically appears to be insufficient, while a quantum mechanical treatment of also the first solvation shell leads to good agreement between theory and experiment. This indicates that the gas-to-liquid phase shift for the molecular magnetizability is to a large extent of non-electrostatic nature. (c) 2007 Elsevier B.V. All rights reserved.
|
|
| 5. |
- Aidas, Kestutis, et al.
(författare)
-
Solvent effects on NMR isotropic shielding constants. A comparison between explicit polarizable discrete and continuum approaches
- 2007
-
Ingår i: The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory. - : American Chemical Society (ACS). - 1520-5215. ; 111:20, s. 4199-4210
-
Tidskriftsartikel (refereegranskat)abstract
- The gas-to-aqueous solution shifts of the O-17 and C-13 NMR isotropic shielding constants for the carbonyl chromophore in formaldehyde and acetone are investigated. For the condensed-phase problem, we use the hybrid density functional theory/molecular mechanics approach in combination with a statistical averaging over an appropriate number of solute-solvent configurations extracted from classical molecular dynamics simulations. The PBE0 exchange-correlation functional and the 6-311++G(2d,2p) basis set are used for the calculation of the shielding constants. London atomic orbitals are employed to ensure gauge-origin independent results. The effects of the bulk solvent molecules are found to be crucial in order to calculate accurate solvation shifts of the shielding constants. Very good agreement between the computed and experimental solvation shifts is obtained for the shielding constants of acetone when a polarizable water potential is used. Supermolecular results based on geometry-optimized molecular structures are presented. We also compare the results obtained with the polarizable continuum model to the results obtained using explicit MM molecules to model the bulk solvent effect.
|
|
| 6. |
- Dahl, Michael K., et al.
(författare)
-
Using an expiratory resistor, arterial pulse pressure variations predict fluid responsiveness during spontaneous breathing : an experimental porcine study
- 2009
-
Ingår i: Critical Care. - : Springer Science and Business Media LLC. - 1364-8535 .- 1466-609X. ; 13:2, s. R39-
-
Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: Fluid responsiveness prediction is difficult in spontaneously breathing patients. Because the swings in intrathoracic pressure are minor during spontaneous breathing, dynamic parameters like pulse pressure variation (PPV) and systolic pressure variation (SPV) are usually small. We hypothesized that during spontaneous breathing, inspiratory and/or expiratory resistors could induce high arterial pressure variations at hypovolemia and low variations at normovolemia and hypervolemia. Furthermore, we hypothesized that SPV and PPV could predict fluid responsiveness under these conditions. METHODS: Eight prone, anesthetized and spontaneously breathing pigs (20 to 25 kg) were subjected to a sequence of 30% hypovolemia, normovolemia, and 20% and 40% hypervolemia. At each volemic level, the pigs breathed in a randomized order either through an inspiratory and/or an expiratory threshold resistor (7.5 cmH2O) or only through the tracheal tube without any resistor. Hemodynamic and respiratory variables were measured during the breathing modes. Fluid responsiveness was defined as a 15% increase in stroke volume (DeltaSV) following fluid loading. RESULTS: Stroke volume was significantly lower at hypovolemia compared with normovolemia, but no differences were found between normovolemia and 20% or 40% hypervolemia. Compared with breathing through no resistor, SPV was magnified by all resistors at hypovolemia whereas there were no changes at normovolemia and hypervolemia. PPV was magnified by the inspiratory resistor and the combined inspiratory and expiratory resistor. Regression analysis of SPV or PPV versus DeltaSV showed the highest R2 (0.83 for SPV and 0.52 for PPV) when the expiratory resistor was applied. The corresponding sensitivity and specificity for prediction of fluid responsiveness were 100% and 100%, respectively, for SPV and 100% and 81%, respectively, for PPV. CONCLUSIONS: Inspiratory and/or expiratory threshold resistors magnified SPV and PPV in spontaneously breathing pigs during hypovolemia. Using the expiratory resistor SPV and PPV predicted fluid responsiveness with good sensitivity and specificity.
|
|
| 7. |
- Forchhammer, Mads C., et al.
(författare)
-
Zackenberg in a circumpolar context
- 2008
-
Ingår i: Advances in Ecological Research. - 0065-2504. ; 40, s. 499-544
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Throughout the Northern Hemisphere, changes in local and regional climate conditions are coupled to the recurring and persistent large-scale patterns of pressure and circulation anomalies spanning vast geographical areas, the so-called teleconnection patterns. Indeed, the atmospheric fluctuations described by the North Atlantic Oscillation (NAO) are closely associated with the last four decades of inter-annual variability in local snow and ice conditions observed in the Arctic. Since the NAO has also been connected with changes in the global climate, the behaviour of species, communities and other ecosystem elements at Zackenberg in relation to the NAO enables us to view these in circumpolar and global contexts. Large-scale systems like the NAO constitute the link between the global change and local climate variability to which ecosystem components respond. Here, we place selected ecosystem elements from the monitoring programme Zackenberg Basic presented in previous chapters in a circumpolar context related to NAO-mediated climatic changes. We begin by linking the local variability in winter weather conditions at Zackenberg to fluctuations in the NAO. We then proceed by linking the observed intra- and inter-annual behaviour of selected ecosystem elements to changes in the NAO. The functional ecosystem characteristics in focus are landscape gas exchange dynamics phenological patterns at different trophic levels, consumer-resource dynamics and community stability. The influence of the NAO is presented and discussed in a broader perspective based on information obtained from other arctic localities. The relation between the NAO and the Zackenberg winter weather, is nonlinear, reflecting differential effects of the NAO as the index moves between high and low phases. The inverse hyperbolic relationship found between the NAO and the amount of winter snow was also evident as non-linear response in organisms and systems to inter-annual changes in the NAO. Responses investigated included growth and reproduction in plants and animals, population dynamics and synchrony, inter-trophic interactions and community stability together with system feedback dynamics.
|
|
| 8. |
- Hoac, Tien, et al.
(författare)
-
Short-term effects of selenium supplementation of cows' feed on the content and distribution of selenium, copper and zinc in bovine milk, whey and blood plasma.
- 2008
-
Ingår i: Journal of Dairy Research. - 0022-0299. ; 75:3, s. 326-334
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of selenium supplementation of feed on the Se content in bovine milk, whey and plasma, and on the distribution of Se, Zn and Cu in whey and plasma was investigated. In a cross-over study two groups of cows were given a basal feed with 0.16 ppm selenite (approx. 3 mg Se/d) with or without 25 mg yeast Se/d for 2 weeks. In the supplemented group the Se content increased 10-fold in milk, 10-fold in whey and 2-fold in plasma, and after the cessation of the supplementation, selenium in milk decreased with a calculated half-life of 3.5 d. In another experiment, two groups of cows were given either 100 mg yeast Se/d for 1 week or only the basal feed. The increase in Se content in both whole and defatted milk was 40-50-fold, and in whey it was approx. 20-fold. Size-exclusion chromatography of whey using inductively coupled plasma mass spectrometry for detection showed that supplementation increased the proportion of Se in the beta-lactoglobulin-alpha-lactalbumin fraction. Distribution of Cu and Zn was essentially unaffected. In plasma, supplementation increased the Se content in all major Se fractions like selenoprotein P, albumin and low-molecular-weight compounds, but the distribution profiles of Zn and Cu underwent no major changes. The study showed for the first time the rapid kinetics of the Se increase and decrease in milk after the initiation and cessation of supplementation, respectively, and the preferential appearance of Se in the beta-lactoglobulin-alpha-lactalbumin fraction of whey. Milk highly enriched in selenium will be a useful tool for different research purposes.
|
|
| 9. |
- Koefoed-Nielsen, Jacob, et al.
(författare)
-
Does a solitary lobar collapse give pressure-lung volume relationship similar to that found in acute respiratory distress syndrome? A porcine experimental study
- 2008
-
Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 28:6, s. 391-397
-
Tidskriftsartikel (refereegranskat)abstract
- Background: The underlying pathophysiology causing different shapes of static pressure–lung volume (PV) curves is not fully elucidated. In this study the aim was to examine the influence of a solitary lobar collapse on inflation–deflation PV curves. The hypothesis was that a lobar collapse would induce the same changes in the PV-curve as those found in experimental acute lung injury (ALI) and in acute respiratory distress syndrome (ARDS). Methods: In four mechanically ventilated, anaesthetized pigs, the right lower lobe was collapsed by selective lavage and exsufflation. End-expiratory lung volume and static inflation–deflation PV curves of the respiratory system, the chest wall and the lung were obtained before formation of the collapse. After creation of the collapse, the same measurements were performed in the non-collapsed lung and in the whole lung including the lobar collapse. In two animals computed tomography was performed to verify the lobar collapse. Results: The solitary lobar collapse changed the PV curve by inducing a significant hysteresis and a right shift of lower inflexion point (LIP) on the inflation limb, but had minimal influence on the deflation limb. After creation of the lobar collapse, LIP was found at the pressure at which the collapse started to expand. Conclusions: PV curves of lungs with solitary lobar collapse are similar to those found in ALI/ARDS. Inspiratory LIP indicated start of recruitment, and expiratory curves did not indicate the pressure at which collapse occurred.
|
|
| 10. |
- Peluso, Marco, et al.
(författare)
-
Bulky DNA adducts, 4-aminobiphenyl-haemoglobin adducts and diet in the European Prospective Investigation into Cancer and Nutrition (EPIC) prospective study
- 2008
-
Ingår i: British Journal of Nutrition. - 1475-2662 .- 0007-1145. ; 100:3, s. 489-495
-
Tidskriftsartikel (refereegranskat)abstract
- In contrast to some extensively examined food mutagens, for example, aflatoxins, N-nitrosamines and heterocyclic amines, some other food contaminants, in particular polycyclic aromatic hydrocarbons (PAH) and other aromatic compounds, have received less attention. Therefore, exploring the relationships between dietary habits and the levels of biomarkers related to exposure to aromatic compounds is highly relevant. We have investigated in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort the association between dietary items (food groups and nutrients) and aromatic DNA adducts and 4-aminobiphenyl-Hb adducts. Both types of adducts are biomarkers of carcinogen exposure and possibly of cancer risk, and were measured, respectively, in leucocytes and erythrocytes of 1086 (DNA adducts) and 190 (Hb adducts) non-smokers. An inverse. statistically significant, association has been found between DNA adduct levels and dietary fibre intake (P=0.02), vitamin E (P =0.04) and alcohol (P=0.03) but not with other nutrients or food groups. Also, an inverse association between fibre and fruit intake, and BMI and 4-aminobiphenyl-Hb adducts (P=0.03, 0.04, and 0.03 respectively) was observed. After multivariate regression analysis these inverse correlations remained statistically significant, except for the correlation adducts v. fruit intake. The present study suggests that fibre intake in the usual range can modify the level of DNA or Hb aromatic adducts, but Such role seems to be quantitatively modest. Fibres could reduce the formation of DNA adducts in different manners, by diluting potential food mutagens and carcinogens in the gastrointestinal tract, by speeding their transit through the colon and by binding carcinogenic substances.
|
|
