455 Ann. For. Sci. 60 (2003) 455–460 © INRA, EDP Sciences, 2003 DOI: 10.1051/forest:2003038 Original article Mature trees versus seedlings: Differences in leaf traits and gas exchange patterns in three co-occurring Mediterranean oaks Sonia MEDIAVILLA*, Alfonso ESCUDERO Departamento de Ecología, Facultad de Biología, Universidad de Salamanca, 37071 Salamanca, Spain (Received 19 February 2002; accepted 1 August 2002) Abstract – We studied gas-exchange patterns and leaf traits of seedlings and mature trees of three coexisting Mediterranean oaks with contrasting leaf habits (the evergreen Quercus ilex, and the deciduous Q. faginea and Q. pyrenaica) during the well-watered part of the growth season. Leaf life span in Q. ilex seedlings was shorter than in mature trees, whereas for the deciduous species the differences in leaf life span between both growth stages were less pronounced. In all species leaves on seedlings displayed a lower mass per unit area and lower nitrogen content than on mature trees. However, owing to their larger stomatal conductance, leaves on seedlings usually showed larger photosynthetic nitrogen-use efficiency and lower water-use efficiency than on mature trees. Stomatal conductance and CO 2 assimilation rate were lower in Q. ilex than in the two deciduous species at the mature stage. However, the interspecific differences in gas exchange rates related to differences in leaf longevity disappeared at the seedling stage because in Q. ilex the seedlings showed a much higher stomatal conductance than the adults. Thus, seedlings of the three species showed a common strategy, regardless of the leaf life span, probably as a response to the competition from the herbaceous layer. growth stages / leaf gas-exchange / leaf traits / Quercus sp. Résumé – Arbres adultes versus semis : différences de caractéristiques foliaires des types d’échanges gazeux chez trois espèces coexistantes de Quercus. Les échanges gazeux et les caractéristiques foliaires des semis et des arbres adultes de trois espèces coexistantes de chênes méditerranéens présentant des caractéristiques foliaires contrastées (une espèce à feuille persistante Quercus ilex et deux espèces à feuille caduque Q. faginea et Q. pyrenaica) ont été étudiés lors des phases les plus favorables de la saison de croissance. La longévité foliaire des semis a été inférieure à celle des adultes pour Q. ilex et similaire pour les deux autres espèces. Les feuilles des semis ont un poids plus faible par unité de surface et une moindre teneur en azote que celle des adultes. Cependant, à cause de leur plus forte conductance stomatique, les semis ont montré une meilleure efficience d’utilisation de l’azote dans la photosynthèse et une plus faible efficience d’utilisation de l’eau que les arbres adultes. La conductance stomatique et l’assimilation de CO 2 ont été plus faibles pour Q. ilex par rapport aux deux autres espèces à l’état adulte. Cependant, les différences interspécifiques dans les échanges gazeux ont disparu au stade semis, et les semis de Q. ilex ont présenté une conductance stomatique beaucoup plus forte que les arbres adultes. Les plantules de trois espèces ont donc présenté une stratégie commune, indépendamment de leur longévité foliaire, vraisemblablement en réponse à la concurrence de la strate herbacée. stades de croissance / échanges gazeux foliaires / caractéristiques foliaires / Quercus sp. 1. INTRODUCTION Seedling establishment and juvenile growth are critical periods in the life cycle of tree species [20], and the morpho- logical and physiological leaf attributes during these periods are key factors for recruitment and survival of tree popula- tions. Furthermore, many aspects of leaf morphology and physiology may vary with tree age [11, 28]. Comparative stud- ies of different growth stages may provide essential informa- tion for understanding the strategies adopted by the species at different stages of their life cycle, as well as the selective pres- sures Gas Exchange across Respiratory Surfaces Gas Exchange across Respiratory Surfaces Bởi: OpenStaxCollege The structure of the lung maximizes its surface area to increase gas diffusion Because of the enormous number of alveoli (approximately 300 million in each human lung), the surface area of the lung is very large (75 m2) Having such a large surface area increases the amount of gas that can diffuse into and out of the lungs Basic Principles of Gas Exchange Gas exchange during respiration occurs primarily through diffusion Diffusion is a process in which transport is driven by a concentration gradient Gas molecules move from a region of high concentration to a region of low concentration Blood that is low in oxygen concentration and high in carbon dioxide concentration undergoes gas exchange with air in the lungs The air in the lungs has a higher concentration of oxygen than that of oxygen-depleted blood and a lower concentration of carbon dioxide This concentration gradient allows for gas exchange during respiration Partial pressure is a measure of the concentration of the individual components in a mixture of gases The total pressure exerted by the mixture is the sum of the partial pressures of the components in the mixture The rate of diffusion of a gas is proportional to its partial pressure within the total gas mixture This concept is discussed further in detail below Lung Volumes and Capacities Different animals have different lung capacities based on their activities Cheetahs have evolved a much higher lung capacity than humans; it helps provide oxygen to all the muscles in the body and allows them to run very fast Elephants also have a high lung capacity In this case, it is not because they run fast but because they have a large body and must be able to take up oxygen in accordance with their body size 1/10 Gas Exchange across Respiratory Surfaces Human lung size is determined by genetics, gender, and height At maximal capacity, an average lung can hold almost six liters of air, but lungs not usually operate at maximal capacity Air in the lungs is measured in terms of lung volumes and lung capacities ([link] and [link]) Volume measures the amount of air for one function (such as inhalation or exhalation) Capacity is any two or more volumes (for example, how much can be inhaled from the end of a maximal exhalation) Human lung volumes and capacities are shown The total lung capacity of the adult male is six liters Tidal volume is the volume of air inhaled in a single, normal breath Inspiratory capacity is the amount of air taken in during a deep breath, and residual volume is the amount of air left in the lungs after forceful respiration Lung Volumes and Capacities (Avg Adult Male) Volume/Capacity Definition Volume Equations (liters) Tidal volume (TV) Amount of air inhaled during a normal breath 0.5 - Expiratory reserve volume (ERV) Amount of air that can be exhaled after a normal exhalation 1.2 - Inspiratory reserve volume (IRV) Amount of air that can be further inhaled after a normal inhalation 3.1 - 2/10 Gas Exchange across Respiratory Surfaces Lung Volumes and Capacities (Avg Adult Male) Volume/Capacity Definition Volume Equations (liters) Residual volume (RV) Air left in the lungs after a forced exhalation 1.2 - Vital capacity (VC) Maximum amount of air that can be moved in or out of the lungs in a single respiratory cycle 4.8 ERV+TV+IRV Inspiratory capacity (IC) Volume of air that can be inhaled in addition to a normal exhalation 3.6 TV+IRV Functional residual capacity (FRC) Volume of air remaining after a normal exhalation 2.4 ERV+RV Total lung capacity (TLC) Total volume of air in the lungs after a maximal inspiration 6.0 RV+ERV+TV+IRV Forced expiratory volume (FEV1) How much air can be forced out of the lungs over a specific time period, usually one second ~4.1 to 5.5 - The volume in the lung can be divided into four units: tidal volume, expiratory reserve volume, inspiratory reserve volume, and residual volume Tidal volume (TV) measures the amount of air that is inspired and expired during a normal breath On average, this volume is around one-half liter, which is a little less than the capacity of a 20-ounce drink bottle The expiratory reserve volume (ERV) is the additional amount of air that can be exhaled after a normal exhalation It is the reserve amount that can be exhaled beyond what is normal Conversely, the inspiratory reserve volume (IRV) is the additional amount of air that can be inhaled after a normal inhalation The residual volume (RV) is the amount of air that is left after expiratory reserve volume is exhaled The lungs are never completely empty: There is always some air left in the lungs after a maximal exhalation If this residual volume did not exist and the lungs emptied completely, the lung tissues would stick together and the energy necessary to re-inflate the lung could be too great to overcome Therefore, there is always some air remaining in the lungs Residual volume is ...Original article Effect of fungal infection on leaf gas-exchange and chlorophyll fluorescence in Quercus ilex Bouchra El Omari, Isabel Fleck*, Xavier Aranda, Asumpció Moret and Martí Nadal Unitat de Fisiologia Vegetal, Departament de Biologia Vegetal, Facultat de Biologia, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain (Received 17 January 2000 ; accepted 14 September 2000) Abstract – Experiments were conducted to study the susceptibility to infection by two fungal pathogens, Cryphonectria parasitica or Phomopsis spp. of undisturbed holm oaks (Quercus ilex) and the resprout from the stump of trees after excision of the shoot. Leaf gas-exchange and chlorophyll a fluorescence were recorded on plants growing in natural conditions for two years, as markers of dis- ease progress at the first stages of infection. In infected plants, pathogen-induced stomatal closure limited photosynthesis and increased contribution of energy dissipating processes protecting PSII integrity, as shown by higher non-photochemical quenching (NPQ). Excision treatment reduced susceptibility to infection and favoured water availability in resprouts, which showed higher gas- exchange rates. Quercus ilex / Cryphonectria parasitica /Phomopsis spp. / gas-exchange / chlorophyll fluorescence Résumé – Effet de l’infection fongique sur les échanges gazeux et la fluorescence de la chlorophylle chez Quercus ilex. Le but de ce travail est l’étude de la susceptibilité des plants élagués (cas du chêne vert), à l’infection par Cryphonectria parasitica et Phomopsis spp. Pendant deux années, les échanges gazeux et la fluorescence de la chlorophylle d’un groupe de plants croissants dans des conditions environnementales naturelles ont été étudiés. Ces paramètres ont été des marqueurs convenables de l’évolution de la maladie durant les premières étapes de l’infection. Chez les plants infectés, le progrès de la maladie a été mis en évidence par la réduction de l’assimilation de CO 2 et l’augmentation de la participation des processus de dissipation thermique de l’énergie révélée par un NPQ élevé (Non-photochemical quenching). L’élagage induit une diminution de la susceptibilité à l’infection et permet une haute disponibilité hydrique chez les rejets assurant ainsi des taux élevés d’échanges gazeux. Quercus ilex / Cryphonectria parasitica / Phomopsis spp. / échanges gazeux / fluorescence de la chlorophylle Abbreviations A, net photosynthesis; g, stomatal conductance; F, fluorescence intensity at any point; F o , F' o minimum flu- orescence yield in dark-adapted and light-adapted state; F m , F' m maximum fluorescence yield in dark-and light- adapted state; F v /F m , quantum yield of PS II photochem- istry in dark-adapted state; ∆F/F' m , quantum yield of PS II photochemistry in light-adapted state); NPQ, non-photo- chemical quenching; q P , photochemical quenching; F' v /F' m intrinsic efficiency of open PS II centers during illumination; PS II , photosystem II; PAR, photosynthetic active radiation. Ann. For. Sci. 58 (2001) 165–173 165 © INRA, EDP Sciences, 2001 * Correspondence and reprints Fax. (34) 93 4112842; e-mail: isabelf@bio.ub.es B. El Omari et al. 166 1. INTRODUCTION Holm oaks (Quercus ilex L.) are often subject to envi- ronmental constraints (drought, high and low tempera- tures and fire), typical of the Mediterranean forests. Resprouting from underground organs after perturba- tions is common [40]. Increased rates of gas-exchange and growth have been observed in resprouts after fire or clear-cut [14, 15, 26, 36], due to increased water [13, 17, 30] and/or nitrogen [16, 20] availability for smaller crowns. Quercus species are also often affected by fungal pathogens such as Cryphonectria parasitica (Murrill) Barr. and Phomopsis spp. [31, 32, 33]. In Mediterranean forests, C. parasitica is common in chest- nut and rare in holm oak, but this fungus could become a serious threat to the latter because several species of Note Leaf gas exchange and carbohydrate concentrations in Pinus pinaster plants subjected to elevated CO 2 and a soil drying cycle Catherine Picon-Cochard Jean-Marc Guehl Unité de recherches en écophysiologie forestière, Équipe bioclimatologie-écophysiologie, Inra Nancy, 54280 Champenoux, France (Received 15 December 1997; accepted 31 March 1998) Abstract - Plants of maritime pine (Pinus pinaster Ait.) were acclimated for 2 years under ambient (350 μmol mol -1 ) and elevated (700 μmol mol -1 ) CO 2 concentrations ([CO 2 ]). In the summer of the second growing season, the plants were subjected to a soil drying cycle for 6 days. Drought reduced plant transpiration rate and net CO 2 assimilation rate (A) by about 80 %. Elevated [CO,] induced a substantial increase of A (+105 % and +229 % in well-watered and in droughted plants, respectively) and of the needle starch (+145 %) and sucrose (+20 %) concentrations, whatever the watering regime. Drought did not significantly affect starch and sucrose concentrations, while hexose concentrations were slightly increased in the most severe drought condition (predawn water potential value equal to -1.5 MPa). The stimulating effect of elevated [CO,] on A was maintained along the drying cycle, whereas no significant CO 2 effect was observed on the soluble carbohydrate concentration. These compounds did not contribute to an enhance- ment of osmotic adjustment under elevated [CO 2] in P. pinaster. (© Inra/Elsevier, Paris.) elevated [CO 2] / drought / leaf gas exchange / carbohydrate / Pinus pinaster Résumé - Échanges gazeux foliaires et concentrations en glucides de plants de Pinus pinaster soumis à un enrichissement en CO 2 de l’air et à un dessèchement du sol. Des semis de pin maritime (Pinus pinaster Ait.) ont été acclimatés pendant deux ans à 350 et à 700 μmol mol -1 de concentrations en CO 2 atmosphérique [CO,]. Au cours de l’été de la deuxième saison de croissance, les plants ont été soumis à un dessèchement du sol pendant 6 j. La sécheresse a réduit d’environ 80 % la transpiration de la plante entière et l’assimilation nette de CO 2 (A). L’enrichissement en CO, de l’air a induit une augmentation marquée de l’assimilation nette de CO, (+105 % et +229 % en conditions de bonne alimentation hydrique et de sécheresse, respectivement), ainsi que des concentra- tions en amidon (+145 %) et en saccharose (+20 %), quelle que soit l’alimentation hydrique. Le traitement sécheresse n’a pas signifi- cativement affecté les concentrations en amidon et en saccharose, tandis que les concentrations en hexoses ont légèrement augmenté en condition de sécheresse sévère (valeur du potentiel hydrique de base égale à -1.5 MPa). L’effet stimulant de la [CO 2] sur A était maintenu au cours du dessèchement du sol, alors que cela n’était pas observé pour la concentration en glucides solubles. Ces compo- sés ne contribuent pas à une augmentation de l’ajustement osmotique par l’enrichissement en CO 2 de l’air chez P. pinaster. (© Inra/Elsevier, Paris.) enrichissement en CO 2 / sécheresse / échanges gazeux foliaires / glucides / Pinus pinaster 1. INTRODUCTION Maritime pine (Pinus pinaster Ait.) is recognised as a drought-avoiding species with a high stomatal sensiti- vity to soil drought, since stomatal closure occurs befo- re any alteration of leaf water status [6, 12]. Other regu- * Correspondence and reprints picon@clermont.inra.fr lation mechanisms may postpone water deficit effects on plant Open Access Available online http://ccforum.com/content/9/5/R471 R471 Vol 9 No 5 Research Respiratory compliance but not gas exchange correlates with changes in lung aeration after a recruitment maneuver: an experimental study in pigs with saline lavage lung injury Dietrich Henzler 1 , Paolo Pelosi 2 , Rolf Dembinski 3 , Annette Ullmann 4 , Andreas H Mahnken 5 , Rolf Rossaint 6 and Ralf Kuhlen 7 1 Senior Anesthesiologist, Anesthesiology Department, University Hospital RWTH Aachen, Germany 2 Professor of Anesthesiology, Environment, Health and Safety Department, University of Insubria, Varese, Italy 3 Intensivist, Surgical Intensive Care Department, University Hospital RWTH Aachen, Germany 4 Resident, Anesthesiology Department, University Hospital RWTH Aachen, Germany 5 Department of Clinical Radiology, University Hospital RWTH Aachen, Germany 6 Professor of Anesthesiology, Anesthesiology Department, University Hospital RWTH Aachen, Germany 7 Head, Surgical Intensive Care Department, University Hospital RWTH Aachen, Germany Corresponding author: Dietrich Henzler, mail@d-henzler.de Received: 8 May 2005 Revisions requested: 27 May 2005 Revisions received: 10 Jun 2005 Accepted: 24 Jun 2005 Published: 13 Jul 2005 Critical Care 2005, 9:R471-R482 (DOI 10.1186/cc3772) This article is online at: http://ccforum.com/content/9/5/R471 © 2005 Henzler et al., licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/ 2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is cited. Abstract Introduction Atelectasis is a common finding in acute lung injury, leading to increased shunt and hypoxemia. Current treatment strategies aim to recruit alveoli for gas exchange. Improvement in oxygenation is commonly used to detect recruitment, although the assumption that gas exchange parameters adequately represent the mechanical process of alveolar opening has not been proven so far. The aim of this study was to investigate whether commonly used measures of lung mechanics better detect lung tissue collapse and changes in lung aeration after a recruitment maneuver as compared to measures of gas exchange Methods In eight anesthetized and mechanically ventilated pigs, acute lung injury was induced by saline lavage and a recruitment maneuver was performed by inflating the lungs three times with a pressure of 45 cmH 2 O for 40 s with a constant positive end- expiratory pressure of 10 cmH 2 O. The association of gas exchange and lung mechanics parameters with the amount and the changes in aerated and nonaerated lung volumes induced by this specific recruitment maneuver was investigated by multi slice CT scan analysis of the whole lung. Results Nonaerated lung correlated with shunt fraction (r = 0.68) and respiratory system compliance (r = 0.59). The arterial partial oxygen pressure (PaO 2 ) and the respiratory system compliance correlated with poorly aerated lung volume (r = 0.57 and 0.72, respectively). The recruitment maneuver caused a decrease in nonaerated lung volume, an increase in normally and poorly aerated lung, but no change in the distribution of a tidal breath to differently aerated lung volumes. The fractional changes in PaO 2 , arterial partial carbon dioxide pressure (PaCO 2 ) and venous admixture after the recruitment maneuver did not correlate with the changes in lung volumes. Alveolar recruitment correlated only with changes in the plateau pressure (r = 0.89), respiratory system compliance (r = 0.82) and parameters obtained from the pressure-volume curve. Conclusion A recruitment maneuver by repeatedly hyperinflating the lungs led to an increase of poorly aerated and a decrease of nonaerated lung mainly. Changes in aerated and nonaerated lung volumes were adequately represented by respiratory compliance but not by changes in oxygenation or shunt. ARDS = acute Open Access Available online http://ccforum.com/content/13/1/R17 Page 1 of 6 (page number not for citation purposes) Vol 13 No 1 Research Effects of interventional lung assist on haemodynamics and gas exchange in cardiopulmonary resuscitation: a prospective experimental study on animals with acute respiratory distress syndrome Günther Zick, Dirk Schädler, Gunnar Elke, Sven Pulletz, Berthold Bein, Jens Scholz, Inéz Frerichs and Norbert Weiler Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Arnold-Heller-Straße 3, D- 24105 Kiel, Germany Corresponding author: Günther Zick, zick@anaesthesie.uni-kiel.de Received: 19 Sep 2008 Revisions requested: 27 Sep 2008 Revisions received: 20 Jan 2009 Accepted: 11 Feb 2009 Published: 11 Feb 2009 Critical Care 2009, 13:R17 (doi:10.1186/cc7716) This article is online at: http://ccforum.com/content/13/1/R17 © 2009 Zick et al.; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0 ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Introduction Interventional lung assist (ILA), based on the use of a pumpless extracorporeal membrane oxygenator, facilitates carbon dioxide (CO 2 ) elimination in acute respiratory distress syndrome (ARDS). It is unclear whether an ILA system should be clamped during cardiopulmonary resuscitation (CPR) in patients with ARDS or not. The aim of our study was to test the effects of an ILA on haemodynamics and gas exchange during CPR on animals with ARDS and to establish whether the ILA should be kept open or clamped under these circumstances. Methods The study was designed to be prospective and experimental. The experiments were performed on 12 anaesthetised and mechanically ventilated pigs (weighing 41 to 58 kg). One femoral artery and one femoral vein were cannulated and connected to an ILA. ARDS was induced by repeated bronchoalveolar lavage. An indwelling pacemaker was used to initiate ventricular fibrillation and chest compressions were immediately started and continued for 30 minutes. In six animals, the ILA was kept open and in the other six it was clamped. Results Systolic and mean arterial pressures did not differ significantly between the groups. With the ILA open mean ± standard deviation systolic blood pressures were 89 ± 26 mmHg at 5 minutes, 71 ± 28 mmHg at 10 minutes, 63 ± 33 mmHg at 20 minutes and 83 ± 23 mmHg at 30 minutes. The clamped ILA system resulted in systolic pressures of 77 ± 30 mmHg, 90 ± 23 mmHg, 72 ± 11 mmHg and 72 ± 22 mmHg, respectively. In the group with the ILA system open, arterial partial pressure of CO 2 was significantly lower after 10, 20 and 30 minutes of CPR and arterial partial pressure of oxygen was higher 20 minutes after the onset of CPR (191 ± 140 mmHg versus 57 ± 14 mmHg). End-tidal partial pressure of CO 2 decreased from 46 ± 23 Torr (ILA open) and 37 ± 9 Torr (ILA clamped) before intervention to 8 ± 5 Torr and 8 ± 10 Torr, respectively, in both groups after 30 minutes of CPR. Conclusions Our results indicate that in an animal model of ARDS, blood pressures were not impaired by keeping the ILA system open during CPR compared with the immediate clamping of the ILA with the onset of CPR. The effect of ILA on gas exchange implied a beneficial effect. Introduction Interventional Lung Assist (ILA) describes a technique, which uses a pumpless arteriovenous extracorporeal membrane oxy- genator to facilitate carbon dioxide (CO 2 ) removal. Its ability to remove CO 2 has been well demonstrated [1-6]. The aim of the extracorporeal CO 2 elimination by the ILA system is to decrease the minute ventilation and the peak inspiratory pres- sure and thereby reduce the risk of barotrauma associated with mechanical ventilation in patients with acute respiratory ... population, career opportunities as a respiratory therapist are expected to remain strong 4/10 Gas Exchange across Respiratory Surfaces Gas Pressure and Respiration The respiratory process can be better... pressure of oxygen is: 5/10 Gas Exchange across Respiratory Surfaces (760 mm Hg − 47 mm Hg) × 0.21 = 150 mm Hg These pressures determine the gas exchange, or the flow of gas, in the system Oxygen... Therefore, understanding the partial pressure of each gas will aid in understanding how gases move in the respiratory system Gas Exchange across the Alveoli In the body, oxygen is used by cells