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Tu DH, Yi C, Liu Q, Huang L, Yang G, Qu R. Longitudinal changes in the volume of residual lung lobes after lobectomy for lung cancer: a retrospective cohort study. Sci Rep 2024; 14:12055. [PMID: 38802642 PMCID: PMC11130117 DOI: 10.1038/s41598-024-63013-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 05/23/2024] [Indexed: 05/29/2024] Open
Abstract
It is unclear how the residual lobe volume changes over time after lobectomy. This study aims to clarify the temporal patterns of volume changes in each remaining lung lobe post-lobectomy. A retrospective review was conducted on patients who underwent lobectomy for lung cancer at Yueyang Central Hospital from January to December 2021. Lung CT images were reconstructed in three dimensions to calculate the volumes of each lung lobe preoperatively and at 1, 6, and 12 months postoperatively. A total of 182 patients were included. Postoperatively, the median total lung volume change rates relative to preoperative values were -20.1%, -9.3%, and -5.9% at 1, 6, and 12 months, respectively. Except for the right middle lobe in patients who underwent right upper lobectomy, the volumes of individual lung lobes exceeded preoperative values. The volume growth of the lung on the side of the resection was significantly more than that of the lung on the opposite side. For left lobectomy patients, the right lower lobe's volume change rate exceeded that of the right upper and middle lobes. Among right lobectomy patients, the left lower lobe and the relatively inferior lobe of right lung had higher volume change rates than the superior one. Right middle lobe change rate was more in patients with right lower lobectomy than right upper lobectomy. Six months postoperatively, FEV1% and right middle lobectomy were positively correlated with the overall volume change rate. One year postoperatively, only age was negatively correlated with the overall volume change rate. 75 patients had pulmonary function tests. Postoperative FEV1 change linearly correlated with 1-year lung volume change rate, but not with theoretical total lung volume change rate or segmental method calculated FEV1 change. Time-dependent compensatory volume changes occur in remaining lung lobe post-lobectomy, with stronger compensation observed in the relatively inferior lobe compared to the superior one(s). Preoperative lung function and age may affect compensation level.
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Affiliation(s)
- De-Hao Tu
- Department of Thoracic Surgery, Yueyang Central Hospital, Yueyang, Hunan, China
| | - Chong Yi
- Department of Pulmonary and Critical Care Medicine, Yueyang Central Hospital, Yueyang, Hunan, China
| | - Qianyun Liu
- Department of Medical Imaging, Yueyang Central Hospital, Yueyang, Hunan, China
| | - Lingmei Huang
- Department of Pulmonary and Critical Care Medicine, Yueyang Central Hospital, Yueyang, Hunan, China
| | - Guang Yang
- Department of Thoracic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jie Fang Avenue, Wuhan, 430030, Hubei, China
| | - Rirong Qu
- Department of Thoracic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jie Fang Avenue, Wuhan, 430030, Hubei, China.
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2
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McGinn EA, Bye E, Gonzalez T, Sosa A, Bilodeaux J, Seedorf G, Smith BJ, Abman SH, Mandell EW. Antenatal Endotoxin Induces Dysanapsis in Experimental Bronchopulmonary Dysplasia. Am J Respir Cell Mol Biol 2024; 70:283-294. [PMID: 38207120 DOI: 10.1165/rcmb.2023-0157oc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 01/10/2024] [Indexed: 01/13/2024] Open
Abstract
Bronchopulmonary dysplasia (BPD), the chronic lung disease of prematurity, is characterized by impaired lung development with sustained functional abnormalities due to alterations of airways and the distal lung. Although clinical studies have shown striking associations between antenatal stress and BPD, little is known about the underlying pathogenetic mechanisms. Whether dysanapsis, the concept of discordant growth of the airways and parenchyma, contributes to late respiratory disease as a result of antenatal stress is unknown. We hypothesized that antenatal endotoxin (ETX) impairs juvenile lung function as a result of altered central airway and distal lung structure, suggesting the presence of dysanapsis in this preclinical BPD model. Fetal rats were exposed to intraamniotic ETX (10 μg) or saline solution (control) 2 days before term. We performed extensive structural and functional evaluation of the proximal airways and distal lung in 2-week-old rats. Distal lung structure was quantified by stereology. Conducting airway diameters were measured using micro-computed tomography. Lung function was assessed during invasive ventilation to quantify baseline mechanics, response to methacholine challenge, and spirometry. ETX-exposed pups exhibited distal lung simplification, decreased alveolar surface area, and decreased parenchyma-airway attachments. ETX-exposed pups exhibited decreased tracheal and second- and third-generation airway diameters. ETX increased respiratory system resistance and decreased lung compliance at baseline. Only Newtonian resistance, specific to large airways, exhibited increased methacholine reactivity in ETX-exposed pups compared with controls. ETX-exposed pups had a decreased ratio of FEV in 0.1 second to FVC and a normal FEV in 0.1 second, paralleling the clinical definition of dysanapsis. Antenatal ETX causes abnormalities of the central airways and distal lung growth, suggesting that dysanapsis contributes to abnormal lung function in juvenile rats.
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Affiliation(s)
- Elizabeth A McGinn
- Pediatric Heart Lung Center, Department of Pediatrics
- Department of Pediatric Critical Care Medicine
| | - Elisa Bye
- Pediatric Heart Lung Center, Department of Pediatrics
| | | | - Alexander Sosa
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Jill Bilodeaux
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | | | - Bradford J Smith
- Pediatric Heart Lung Center, Department of Pediatrics
- Department of Pediatric Pulmonary and Sleep Medicine, and
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Steven H Abman
- Pediatric Heart Lung Center, Department of Pediatrics
- Department of Pediatric Pulmonary and Sleep Medicine, and
| | - Erica W Mandell
- Pediatric Heart Lung Center, Department of Pediatrics
- Department of Neonatology, University of Colorado School of Medicine, Aurora, Colorado; and
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3
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McGinn EA, Mandell EW, Smith BJ, Duke JW, Bush A, Abman SH. Dysanapsis as a Determinant of Lung Function in Development and Disease. Am J Respir Crit Care Med 2023; 208:956-963. [PMID: 37677135 PMCID: PMC10870865 DOI: 10.1164/rccm.202306-1120pp] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Accepted: 09/07/2023] [Indexed: 09/09/2023] Open
Affiliation(s)
| | - Erica W. Mandell
- Pediatric Heart Lung Center, Department of Pediatrics
- Department of Neonatology
| | - Bradford J. Smith
- Pediatric Heart Lung Center, Department of Pediatrics
- Department of Pediatric Pulmonary and Sleep Medicine, and
- Department of Bioengineering, Anschutz School of Medicine, University of Colorado–Denver, Aurora, Colorado
| | - Joseph W. Duke
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona; and
| | - Andrew Bush
- Center for Pediatrics and Child Health, Imperial College of Medicine, London, United Kingdom
| | - Steven H. Abman
- Pediatric Heart Lung Center, Department of Pediatrics
- Department of Pediatric Pulmonary and Sleep Medicine, and
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4
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Trachsel D, Erb TO, Hammer J, von Ungern‐Sternberg BS. Developmental respiratory physiology. Paediatr Anaesth 2022; 32:108-117. [PMID: 34877744 PMCID: PMC9135024 DOI: 10.1111/pan.14362] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 12/02/2021] [Accepted: 12/05/2021] [Indexed: 12/25/2022]
Abstract
Various developmental aspects of respiratory physiology put infants and young children at an increased risk of respiratory failure, which is associated with a higher rate of critical incidents during anesthesia. The immaturity of control of breathing in infants is reflected by prolonged central apneas and periodic breathing, and an increased risk of apneas after anesthesia. The physiology of the pediatric upper and lower airways is characterized by a higher flow resistance and airway collapsibility. The increased chest wall compliance and reduced gas exchange surface of the lungs reduce the pulmonary oxygen reserve vis-à-vis a higher metabolic oxygen demand, which causes more rapid oxygen desaturation when ventilation is compromised. This review describes the various developmental aspects of respiratory physiology and summarizes anesthetic implications.
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Affiliation(s)
- Daniel Trachsel
- Pediatric Intensive Care and PulmonologyUniversity Children’s Hospital of Basel UKBBBaselSwitzerland
| | - Thomas O. Erb
- Department AnesthesiologyUniversity Children’s Hospital of Basel UKBBBaselSwitzerland
| | - Jürg Hammer
- Pediatric Intensive Care and PulmonologyUniversity Children’s Hospital of Basel UKBBBaselSwitzerland
| | - Britta S. von Ungern‐Sternberg
- Department of Anaesthesia and Pain ManagementPerth Children’s HospitalPerthWAAustralia,Division of Emergency Medicine, Anaesthesia and Pain MedicineMedical SchoolThe University of Western AustraliaPerthWAAustralia,Perioperative Medicine TeamTelethon Kids InstitutePerthWAAustralia
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5
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Yilmaz C, Dane DM, Tustison NJ, Song G, Gee JC, Hsia CCW. In vivo imaging of canine lung deformation: effects of posture, pneumonectomy, and inhaled erythropoietin. J Appl Physiol (1985) 2020; 128:1093-1105. [PMID: 31944885 DOI: 10.1152/japplphysiol.00647.2019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Mechanical stresses on the lung impose the major stimuli for developmental and compensatory lung growth and remodeling. We used computed tomography (CT) to noninvasively characterize the factors influencing lobar mechanical deformation in relation to posture, pneumonectomy (PNX), and exogenous proangiogenic factor supplementation. Post-PNX adult canines received weekly inhalations of nebulized nanoparticles loaded with recombinant human erythropoietin (EPO) or control (empty nanoparticles) for 16 wk. Supine and prone CT were performed at two transpulmonary pressures pre- and post-PNX following treatment. Lobar air and tissue volumes, fractional tissue volume (FTV), specific compliance (Cs), mechanical strains, and shear distortion were quantified. From supine to prone, lobar volume and Cs increased while strain and shear magnitudes generally decreased. From pre- to post-PNX, air volume increased less and FTV and Cs increased more in the left caudal (LCa) than in other lobes. FTV increased most in the dependent subpleural regions, and the portion of LCa lobe that expanded laterally wrapping around the mediastinum. Supine deformation was nonuniform pre- and post-PNX; strains and shear were most pronounced in LCa lobe and declined when prone. Despite nonuniform regional expansion and deformation, post-PNX lobar mechanics were well preserved compared with pre-PNX because of robust lung growth and remodeling establishing a new mechanical equilibrium. EPO treatment eliminated posture-dependent changes in FTV, accentuated the post-PNX increase in FTV, and reduced FTV heterogeneity without altering absolute air or tissue volumes, consistent with improved microvascular blood volume distribution and modestly enhanced post-PNX alveolar microvascular reserves.NEW & NOTEWORTHY Mechanical stresses on the lung impose the major stimuli for lung growth. We used computed tomography to image deformation of the lung in relation to posture, loss of lung units, and inhalational delivery of the growth promoter erythropoietin. Following loss of one lung in adult large animals, the remaining lung expanded and grew while retaining near-normal mechanical properties. Inhalation of erythropoietin promoted more uniform distribution of blood volume within the remaining lung.
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Affiliation(s)
- Cuneyt Yilmaz
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - D Merrill Dane
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Nicholas J Tustison
- Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, Virginia
| | - Gang Song
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - James C Gee
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Connie C W Hsia
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
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6
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Dane DM, Yilmaz C, Gyawali D, Iyer R, Menon J, Nguyen KT, Ravikumar P, Estrera AS, Hsia CCW. Erythropoietin inhalation enhances adult canine alveolar-capillary formation following pneumonectomy. Am J Physiol Lung Cell Mol Physiol 2019; 316:L936-L945. [PMID: 30785346 DOI: 10.1152/ajplung.00504.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Paracrine erythropoietin (EPO) signaling in the lung recruits endothelial progenitor cells, promotes cell maturation and angiogenesis, and is upregulated during canine postpneumonectomy (PNX) compensatory lung growth. To determine whether inhalational delivery of exogenous EPO augments endogenous post-PNX lung growth, adult canines underwent right PNX and received, via a permanent tracheal stoma, weekly nebulization of recombinant human EPO-containing nanoparticles or empty nanoparticles (control) for 16 wk. Lung function was assessed under anesthesia pre- and post-PNX. The remaining lobes were fixed for detailed morphometric analysis. Compared with control treatment, EPO delivery significantly increased serum EPO concentration without altering systemic hematocrit or hemoglobin concentration and abrogated post-PNX lipid oxidative stress damage. EPO delivery modestly increased post-PNX volume densities of the alveolar septum per unit of lung volume and type II epithelium and endothelium per unit of septal tissue volume in selected lobes. EPO delivery also augmented the post-PNX increase in alveolar double-capillary profiles, a marker of intussusceptive capillary formation, in all remaining lobes. EPO treatment did not significantly alter absolute resting lung volumes, lung and membrane diffusing capacities, alveolar-capillary blood volume, pulmonary blood flow, lung compliance, or extravascular alveolar tissue volumes or surface areas. Results established the feasibility of chronic inhalational delivery of growth-modifying biologics in a large animal model. Exogenous EPO selectively enhanced cytoprotection and alveolar angiogenesis in remaining lobes but not whole-lung extravascular tissue growth or resting function; the nonuniform response contributes to structure-function discrepancy, a major challenge for interventions aimed at amplifying the innate potential for compensatory lung growth.
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Affiliation(s)
- D Merrill Dane
- Department of Internal Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Cuneyt Yilmaz
- Department of Internal Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Dipendra Gyawali
- Department of Internal Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Roshni Iyer
- Department of Internal Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Jyothi Menon
- Department of Bioengineering, University of Texas at Arlington , Arlington, Texas
| | - Kytai T Nguyen
- Department of Bioengineering, University of Texas at Arlington , Arlington, Texas
| | - Priya Ravikumar
- Department of Internal Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Aaron S Estrera
- Department of Cardiothoracic Surgery, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Connie C W Hsia
- Department of Internal Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
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7
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Dane DM, Yilmaz C, Gyawali D, Iyer R, Ravikumar P, Estrera AS, Hsia CCW. Perfusion-related stimuli for compensatory lung growth following pneumonectomy. J Appl Physiol (1985) 2016; 121:312-23. [PMID: 27150830 DOI: 10.1152/japplphysiol.00297.2016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 05/04/2016] [Indexed: 12/14/2022] Open
Abstract
Following pneumonectomy (PNX), two separate mechanical forces act on the remaining lung: parenchymal stress caused by lung expansion, and microvascular distension and shear caused by increased perfusion. We previously showed that parenchymal stress and strain explain approximately one-half of overall compensation; the remainder was presumptively attributed to perfusion-related factors. In this study, we directly tested the hypothesis that perturbation of regional pulmonary perfusion modulates post-PNX lung growth. Adult canines underwent banding of the pulmonary artery (PAB) to the left caudal (LCa) lobe, which caused a reduction in basal perfusion to LCa lobe without preventing the subsequent increase in its perfusion following right PNX while simultaneously exaggerating the post-PNX increase in perfusion to the unbanded lobes, thereby creating differential perfusion changes between banded and unbanded lobes. Control animals underwent sham pulmonary artery banding followed by right PNX. Pulmonary function, regional pulmonary perfusion, and high-resolution computed tomography of the chest were analyzed pre-PNX and 3-mo post-PNX. Terminally, the remaining lobes were fixed for detailed morphometric analysis. Results were compared with corresponding lobes in two control (Sham banding and normal unoperated) groups. PAB impaired the indices of post-PNX extravascular alveolar tissue growth by up to 50% in all remaining lobes. PAB enhanced the expected post-PNX increase in alveolar capillary formation, measured by the prevalence of double-capillary profiles, in both unbanded and banded lobes. We conclude that perfusion distribution provides major stimuli for post-PNX compensatory lung growth independent of the stimuli provided by lung expansion and parenchymal stress and strain.
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Affiliation(s)
- D Merrill Dane
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas; and
| | - Cuneyt Yilmaz
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas; and
| | - Dipendra Gyawali
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas; and
| | - Roshni Iyer
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas; and
| | - Priya Ravikumar
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas; and
| | - Aaron S Estrera
- Department of Cardiothoracic Surgery, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Connie C W Hsia
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas; and
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8
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Abstract
Structural and functional complexities of the mammalian lung evolved to meet a unique set of challenges, namely, the provision of efficient delivery of inspired air to all lung units within a confined thoracic space, to build a large gas exchange surface associated with minimal barrier thickness and a microvascular network to accommodate the entire right ventricular cardiac output while withstanding cyclic mechanical stresses that increase several folds from rest to exercise. Intricate regulatory mechanisms at every level ensure that the dynamic capacities of ventilation, perfusion, diffusion, and chemical binding to hemoglobin are commensurate with usual metabolic demands and periodic extreme needs for activity and survival. This article reviews the structural design of mammalian and human lung, its functional challenges, limitations, and potential for adaptation. We discuss (i) the evolutionary origin of alveolar lungs and its advantages and compromises, (ii) structural determinants of alveolar gas exchange, including architecture of conducting bronchovascular trees that converge in gas exchange units, (iii) the challenges of matching ventilation, perfusion, and diffusion and tissue-erythrocyte and thoracopulmonary interactions. The notion of erythrocytes as an integral component of the gas exchanger is emphasized. We further discuss the signals, sources, and limits of structural plasticity of the lung in alveolar hypoxia and following a loss of lung units, and the promise and caveats of interventions aimed at augmenting endogenous adaptive responses. Our objective is to understand how individual components are matched at multiple levels to optimize organ function in the face of physiological demands or pathological constraints.
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Affiliation(s)
- Connie C.W. Hsia
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Dallas M. Hyde
- California National Primate Research Center, University of California at Davis, Davis, California, USA
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9
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Thane K, Ingenito EP, Hoffman AM. Lung regeneration and translational implications of the postpneumonectomy model. Transl Res 2014; 163:363-76. [PMID: 24316173 DOI: 10.1016/j.trsl.2013.11.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 10/30/2013] [Accepted: 11/18/2013] [Indexed: 10/26/2022]
Abstract
Lung regeneration research is yielding data with increasing translational value. The classical models of lung development, postnatal alveolarization, and postpneumonectomy alveolarization have contributed to a broader understanding of the cellular participants including stem-progenitor cells, cell-cell signaling pathways, and the roles of mechanical deformation and other physiologic factors that have the potential to be modulated in human and animal patients. Although recent information is available describing the lineage fate of lung fibroblasts, genetic fate mapping, and clonal studies are lacking in the study of lung regeneration and deserve further examination. In addition to increasing knowledge concerning classical alveolarization (postnatal, postpneumonectomy), there is increasing evidence for remodeling of the adult lung after partial pneumonectomy. Though limited in scope, compelling data have emerged describing restoration of lung tissue mass in the adult human and in large animal models. The basis for this long-term adaptation to pneumonectomy is poorly understood, but investigations into mechanisms of lung regeneration in older animals that have lost their capacity for rapid re-alveolarization are warranted, as there would be great translational value in modulating these mechanisms. In addition, quantitative morphometric analysis has progressed in conjunction with developments in advanced imaging, which allow for longitudinal and nonterminal evaluation of pulmonary regenerative responses in animals and humans. This review focuses on the cellular and molecular events that have been observed in animals and humans after pneumonectomy because this model is closest to classical regeneration in other mammalian systems and has revealed several new fronts of translational research that deserve consideration.
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Affiliation(s)
- Kristen Thane
- Department of Clinical Sciences, Regenerative Medicine Laboratory, Tufts University Cummings School of Veterinary Medicine, North Grafton, Mass
| | - Edward P Ingenito
- Division of Pulmonary, Critical Care, and Sleep Medicine, Brigham and Women's Hospital, Boston, Mass
| | - Andrew M Hoffman
- Department of Clinical Sciences, Regenerative Medicine Laboratory, Tufts University Cummings School of Veterinary Medicine, North Grafton, Mass.
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10
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Ravikumar P, Yilmaz C, Dane DM, Bellotto DJ, Estrera AS, Hsia CCW. Defining a stimuli-response relationship in compensatory lung growth following major resection. J Appl Physiol (1985) 2014; 116:816-24. [PMID: 24481960 DOI: 10.1152/japplphysiol.01291.2013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Major lung resection is a robust model that mimics the consequences of loss-of-functioning lung units. We previously observed in adult canines, following 42% and 58% lung resection, a critical threshold of stimuli intensity for the initiation of compensatory lung growth. To define the range and limits of this stimuli-response relationship, we performed morphometric analysis on the remaining lobes of adult dogs, 2-3 years after surgical removal of ∼ 70% of lung units in the presence or absence of mediastinal shift. Results were expressed as ratios to that in corresponding control lobes. Lobar expansion and extravascular tissue growth (∼ 3.8- and ∼ 2.0-fold of normal, respectively) were heterogeneous; the lobes remaining next to the diaphragm exhibited a greater response. Tissue growth and capillary formation, indexed by double-capillary profiles, increased, regardless of mediastinal shift. Septal collagen fibers increased up to 2.7-fold, suggesting a greater need for structural support. Compared with previous cohorts following less-extensive resection, tissue volume and gas-exchange surface areas increased significantly only in the infracardiac lobe following 42% resection, exceeded two- to threefold in all lobes following 58% resection, and then exhibited diminished gains following ∼ 70% resection. In contrast, alveolar-capillary formation increased with incremental resection without reaching an upper limit. Overall structural regrowth was most vigorous and uniform following 58% resection. The diminishment of gains in tissue growth, following ∼ 70% resection, could reflect excessive or maldistributed mechanical stress that threatens septal integrity. Results also suggest additional independent stimuli of alveolar-capillary formation, possibly related to the postresection augmentation of regional perfusion.
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Affiliation(s)
- Priya Ravikumar
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
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11
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Dane DM, Yilmaz C, Estrera AS, Hsia CCW. Separating in vivo mechanical stimuli for postpneumonectomy compensation: physiological assessment. J Appl Physiol (1985) 2012; 114:99-106. [PMID: 23104695 DOI: 10.1152/japplphysiol.01213.2012] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Following right pneumonectomy (PNX), the remaining lung expands and its perfusion doubles. Tissue and microvascular mechanical stresses are putative stimuli for initiating compensatory lung growth and remodeling, but their relative contributions to overall compensation remain uncertain. To temporally isolate the stimuli related to post-PNX lung expansion (parenchyma deformation) from those related to the sustained increase in perfusion (microvascular distention and shear), we replaced the right lung of adult dogs with a custom-shaped inflated prosthesis. Following stabilization of perfusion and wound healing 4 mo later, the prosthesis was either acutely deflated (DEF group) or kept inflated (INF group). Physiological studies were performed pre-PNX, 4 mo post-PNX (inflated prosthesis, INF1), and again 4 mo postdeflation (DEF) compared with controls with simultaneous INF prosthesis (INF2). Perfusion to the remaining lung increased ~76-113% post-PNX (INF1 and INF2) and did not change postdeflation. Post-PNX (INF prosthesis) end-expiratory lung volume (EELV) and lung and membrane diffusing capacities (DL(CO) and DM(CO)) at a given perfusion were 25-40% below pre-PNX baseline. In the INF group EELV, DL(CO) and DM(CO) remained stable or declined slightly with time. In contrast, all of these parameters increased significantly after deflation and were 157%, 26%, and 47%, respectively, above the corresponding control values (INF2). Following delayed deflation, lung expansion accounted for 44%-48% of total post-PNX compensatory increase in exercise DL(CO) and peak O(2) uptake; the remainder fraction is likely attributable to the increase in perfusion. Results suggest that expansion-related parenchyma mechanical stress and perfusion-related microvascular stress contribute in equal proportions to post-PNX alveolar growth and remodeling.
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Affiliation(s)
- D Merrill Dane
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9034, USA
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12
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Hsia CCW, Tawhai MH. What can imaging tell us about physiology? Lung growth and regional mechanical strain. J Appl Physiol (1985) 2012; 113:937-46. [PMID: 22582216 DOI: 10.1152/japplphysiol.00289.2012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The interplay of mechanical forces transduces diverse physico-biochemical processes to influence lung morphogenesis, growth, maturation, remodeling and repair. Because tissue stress is difficult to measure in vivo, mechano-sensitive responses are commonly inferred from global changes in lung volume, shape, or compliance and correlated with structural changes in tissue blocks sampled from postmortem-fixed lungs. Recent advances in noninvasive volumetric imaging technology, nonrigid image registration, and deformation analysis provide valuable tools for the quantitative analysis of in vivo regional anatomy and air and tissue-blood distributions and when combined with transpulmonary pressure measurements, allow characterization of regional mechanical function, e.g., displacement, strain, shear, within and among intact lobes, as well as between the lung and the components of its container-rib cage, diaphragm, and mediastinum-thereby yielding new insights into the inter-related metrics of mechanical stress-strain and growth/remodeling. Here, we review the state-of-the-art imaging applications for mapping asymmetric heterogeneous physical interactions within the thorax and how these interactions permit as well as constrain lung growth, remodeling, and compensation during development and following pneumonectomy to illustrate how advanced imaging could facilitate the understanding of physiology and pathophysiology. Functional imaging promises to facilitate the formulation of realistic computational models of lung growth that integrate mechano-sensitive events over multiple spatial and temporal scales to accurately describe in vivo physiology and pathophysiology. Improved computational models in turn could enhance our ability to predict regional as well as global responses to experimental and therapeutic interventions.
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Affiliation(s)
- Connie C W Hsia
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390-9034, USA
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13
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Wongtrakool C, Wang N, Hyde DM, Roman J, Spindel ER. Prenatal nicotine exposure alters lung function and airway geometry through α7 nicotinic receptors. Am J Respir Cell Mol Biol 2012; 46:695-702. [PMID: 22246862 DOI: 10.1165/rcmb.2011-0028oc] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Maternal smoking during pregnancy has been associated with adverse effects on respiratory health. Whereas the epidemiologic link is incontrovertible, the mechanisms responsible for this association are still poorly understood. Although cigarette smoke has many toxic constituents, nicotine, the major addictive component in cigarette smoke, may play a more significant role than previously realized. The objectives of this study were to determine whether exposure to nicotine prenatally leads to alterations in pulmonary function and airway geometry in offspring, and whether α7 nicotinic acetylcholine receptors (nAChRs) mediate these effects. In a murine model of in utero nicotine exposure, pulmonary function, airway size and number, methacholine response, and collagen deposition were examined. Exposure periods included Gestation Days 7-21, Gestation Day 14 to Postnatal Day 7, and Postnatal Days 3-15. Prenatal nicotine exposure decreases forced expiratory flows in offspring through α7 nAChR-mediated signals, and the critical period of nicotine exposure was between Prenatal Day 14 and Postnatal Day 7. These physiologic changes were associated with increased airway length and decreased diameter. In addition, adult mice exposed to prenatal nicotine exhibit an increased response to methacholine challenge, even in the absence of allergic sensitization. Collagen expression was increased between adjacent airways and vessels, which was absent in α7 nAChR knockout mice. These observations provide a unified mechanism of how maternal smoking during pregnancy may lead to lifelong alterations in offspring pulmonary function and increased risk of asthma, and suggest potential targets to counteract those effects.
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Ueda K, Tanaka T, Hayashi M, Tanaka N, Li TS, Hamano K. Clinical Ramifications of Bronchial Kink After Upper Lobectomy. Ann Thorac Surg 2012; 93:259-65. [DOI: 10.1016/j.athoracsur.2011.08.065] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Revised: 08/17/2011] [Accepted: 08/24/2011] [Indexed: 12/25/2022]
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Hsia CCW, Dane DM, Estrera AS, Wagner HE, Wagner PD, Johnson RL. Shifting sources of functional limitation following extensive (70%) lung resection. J Appl Physiol (1985) 2008; 104:1069-79. [PMID: 18258800 DOI: 10.1152/japplphysiol.01198.2007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We previously found that, following surgical resection of approximately 58% of lung units by right pneumonectomy (PNX) in adult canines, oxygen-diffusing capacity (Dl(O(2))) fell sufficiently to become a major factor limiting exercise capacity, although the decline was mitigated by recruitment, remodeling, and growth of the remaining lung units. To determine whether an upper limit of compensation is reached following the loss of even more lung units, we measured pulmonary gas exchange, hemodynamics, and ventilatory power requirements in adult canines during treadmill exercise following two-stage resection of approximately 70% of lung units in the presence or absence of mediastinal distortion. Results were compared with that in control animals following right PNX or thoracotomy without resection (Sham). Following 70% lung resection, peak O(2) uptake was 45% below normal. Ventilation-perfusion mismatch developed, and pulmonary arterial pressure and ventilatory power requirements became markedly elevated. In contrast, the relationship of Dl(O(2)) to cardiac output remained normal, indicating preservation of Dl(O(2))-to-cardiac output ratio and alveolar-capillary recruitment up to peak exercise. The impairment in airway and vascular function exceeded the impairment in gas exchange and imposed the major limitation to exercise following 70% resection. Mediastinal distortion further reduced air and blood flow conductance, resulting in CO(2) retention. Results suggest that adaptation of extra-acinar airways and blood vessels lagged behind that of acinar tissue. As more lung units were lost, functional compensation became limited by the disproportionately reduced convective conductance rather than by alveolar diffusion disequilibrium.
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Affiliation(s)
- Connie C W Hsia
- Pulmonary and Critical Care Medicine, Univ. of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9034, USA
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16
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Friedrich L, Pitrez PMC, Stein RT, Goldani M, Tepper R, Jones MH. Growth rate of lung function in healthy preterm infants. Am J Respir Crit Care Med 2007; 176:1269-73. [PMID: 17885265 PMCID: PMC2176107 DOI: 10.1164/rccm.200703-476oc] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE It remains unclear whether premature birth, in the absence of neonatal respiratory disease, results in abnormal growth and development of the lung. We previously reported that a group of healthy infants born at 32-34 weeks' gestation and without respiratory complications had decreased forced expiratory flows and normal forced vital capacities at 2 months of age. OBJECTIVES Our current study evaluated whether these healthy infants born prematurely exhibited improvement or "catch-up" in their lung function during the second year of life. METHODS Longitudinal measurements of forced expiratory flows by the raised volume rapid thoracic compression technique were obtained in the first and the second years of life for infants born prematurely at 32.7 (range, 30-34) weeks' gestation (n = 26) and infants born at full term (n = 24). MEASUREMENTS AND MAIN RESULTS Healthy infants born prematurely demonstrate decreased forced expiratory flows and normal forced vital capacities in the first and second years of life. In addition, the increases in lung function with growth were similar to full-term infants. CONCLUSIONS Persistently reduced flows in the presence of normal forced vital capacity and the absence of catch-up growth in airway function suggest that premature birth is associated with altered lung development.
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Affiliation(s)
- Luciana Friedrich
- Department of Pediatrics, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
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17
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Wongtrakool C, Roser-Page S, Rivera HN, Roman J. Nicotine alters lung branching morphogenesis through the alpha7 nicotinic acetylcholine receptor. Am J Physiol Lung Cell Mol Physiol 2007; 293:L611-8. [PMID: 17545491 PMCID: PMC2665174 DOI: 10.1152/ajplung.00038.2007] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
There is abundant epidemiological data linking prenatal environmental tobacco smoke with childhood asthma and wheezing, but the underlying molecular and physiological mechanisms that occur in utero to explain this link remain unelucidated. Several studies suggest that nicotine, which traverses the placenta, is a causative agent. Therefore, we studied the effects of nicotine on lung branching morphogenesis using embryonic murine lung explants. We found that the expression of alpha(7) nicotinic acetylcholine receptors, which mediate many of the biological effects of nicotine, is highest in pseudoglandular stage lungs compared with lungs at later stages. We then studied the effects of nicotine in the explant model and found that nicotine stimulated lung branching in a dose-dependent fashion. alpha-Bungarotoxin, an antagonist of alpha(7) nicotinic acetylcholine receptors, blocked the stimulatory effect of nicotine, whereas GTS-21, a specific agonist, stimulated branching, thereby mimicking the effects of nicotine. Explants deficient in alpha(7) nicotinic acetylcholine receptors did not respond to nicotine. Nicotine also stimulated the growth of the explant. Altogether, these studies suggest that nicotine stimulates lung branching morphogenesis through alpha(7) nicotinic acetylcholine receptors and may contribute to dysanaptic lung growth, which in turn may predispose the host to airway disease in the postnatal period.
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Affiliation(s)
- Cherry Wongtrakool
- Emory Univ. School of Medicine, Division of Pulmonary, Allergy and Critical Care, Whitehead Biomedical Research Bldg., 615 Michael St., Rm. 205-M, Atlanta, GA 30322, USA.
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Ravikumar P, Yilmaz C, Dane DM, Johnson RL, Estrera AS, Hsia CCW. Developmental signals do not further accentuate nonuniform postpneumonectomy compensatory lung growth. J Appl Physiol (1985) 2006; 102:1170-7. [PMID: 17138837 DOI: 10.1152/japplphysiol.00520.2006] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mechanical forces imposed on lung tissue constitute major stimuli for normal lung development and postpneumonectomy (PNX) compensatory growth and remodeling. Superimposing developmental signals on PNX signals augments compensatory alveolar growth but exaggerates airway-parenchymal dissociation (i.e., dysanaptic lung growth); the latter tends to offset benefits derived from the former. In adult dogs after PNX, lobar expansion and growth of the remaining lobes were markedly non-uniform (Ravikumar et al. J Appl Physiol 97:1567-1574, 2004). We hypothesized that superimposing developmental and post-PNX signals further accentuates nonuniformity of lobar growth. We used high-resolution computed tomography (HRCT) to follow regional lung expansion and growth in foxhounds undergoing right PNX at 2.5 mo of age compared with litter-matched control (Sham) animals; scans were performed 4 and 10 mo following surgery, i.e., before and after somatic maturity. Air and tissue volumes were measured in each lobe; tissue volume estimated by HRCT includes air-free tissue and blood in small vessels <1 mm. Interlobar nonuniformity of tissue volume was absent at 4 mo but evident 10 mo after PNX; growth of the remaining left lower lobe gradually lagged behind other lobes. At maturity, nonuniformity of lobar growth in pneumonectomized puppies was similar to that previously reported in pneumonectomized adults. We conclude that superimposing developmental and post-PNX signals enhances some aspects of compensatory lung growth and remodeling without altering its nonuniform spatial distribution.
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Affiliation(s)
- Priya Ravikumar
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390-9034, USA
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19
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Abstract
Growth of the lung involves unique structure-function interactions not seen in solid organs. Mechanical feedback between the lung and thorax constitutes a major signal that sustains developmental as well as compensatory lung growth. After the loss of lung units as by pneumonectomy (PNX), increased mechanical stress and strain on the remaining units induce adaptive responses to augment oxygen transport, including 1) recruitment of alveolar-capillary reserves, 2) remodeling of existing tissue, and 3) regenerative growth of acinar tissue when strain exceeds a critical threshold. Alveolar hypoxia, hormones, and growth factors may feed into the mechanical feedback system to modify an existing growth response but are unlikely to initiate compensatory growth in the absence of sufficient mechanical signals. Whereas endogenous post-PNX alveolar growth preserves normal structure-function relationships, experimental manipulation of selected metabolic pathways can distort these relationships. Finally, PNX widens the disparity between the rapidly adapting acini and slowly adapting conducting airways and blood vessels, leading to disproportionate airflow and hemodynamic dysfunction and secondary hypertrophy of the right ventricle and respiratory muscles that limits overall organ function despite regeneration of gas exchange tissue. These are key concepts to consider when formulating approaches to stimulate or augment compensatory growth in chronic lung disease.
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Affiliation(s)
- Connie C W Hsia
- Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9034, USA
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20
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Abstract
The lung is unique in its double sources of perfusion from the pulmonary and systemic circulations. One striking difference between the two circulations is the capacity for angiogenesis. The bronchial circulation has a capacity that seems quite similar to all systemic arteries, whereas the pulmonary circulation seems relatively inert in this regard. Extra-alveolar pulmonary arteries can grow somewhat in length, and septal capillaries seem to have the capability of reforming, but these processes do not seem to occur with nearly the same intensity associated with the bronchial arteries. In this review, we emphasize these differences between the two circulations of the lung, anticipating that future research will allow more focused probing into the molecular signaling that regulates the novel mechanistic and pathological pathways of each.
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Affiliation(s)
- Wayne Mitzner
- Department of Environmental Health Sciences, Johns Hopkins Medical Institutions, 615 North Wolfe St., Baltimore, MD 21205, USA.
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Van Winkle LS, Fanucchi MV, Miller LA, Baker GL, Gershwin LJ, Schelegle ES, Hyde DM, Evans MJ, Plopper CG. Epithelial cell distribution and abundance in rhesus monkey airways during postnatal lung growth and development. J Appl Physiol (1985) 2004; 97:2355-63; discussion 2354. [PMID: 15298983 DOI: 10.1152/japplphysiol.00470.2004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Lung development is both a pre- and postnatal process. Although many lung diseases have their origins in early childhood, few quantitative data are available on the normal growth and differentiation of both the conducting airways and the airway epithelium during the postnatal period. We examined rhesus monkey lungs from five postnatal ages: 4-6 days and 1, 2, 3, and 6 mo. Airways increase significantly in both length and circumference as monkeys increase significantly in body weight from 5 days to 6 mo. In this study we asked: as basement membrane surface area increases, does the epithelial cell organization change? To answer this question, we quantified total epithelial cell mass using high-resolution light micrographs and morphometric techniques on sections from defined airway regions: trachea, proximal intrapulmonary bronchus (generations 1 or 2), and distal intrapulmonary bronchus (generations 6-8). Epithelial thickness decreased in the smaller, more distal, airways compared with trachea but did not change with age in the trachea and proximal bronchus. The volume fraction of all cell types measured did not change significantly. Ciliated cells in the distal bronchus and goblet cells in the trachea both decreased in abundance with increasing age. Overall, the epithelial cell populations changed little in terms of mass or relative abundance to each other during this period of active postnatal lung growth. Regarding the proximal conducting airway epithelium, we conclude that 1) the steady-state abundance is tightly regulated to keep the proportion of cell types constant, and 2) establishment of these cell types occurs before 4-6 days postnatal age. We conclude that growth of the proximal airways occurs primarily in length and lags behind that of the lung parenchyma.
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Affiliation(s)
- Laura S Van Winkle
- Dept. of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616-8732, USA.
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Dane DM, Yan X, Tamhane RM, Johnson RL, Estrera AS, Hogg DC, Hogg RT, Hsia CCW. Retinoic acid-induced alveolar cellular growth does not improve function after right pneumonectomy. J Appl Physiol (1985) 2004; 96:1090-6. [PMID: 14506099 DOI: 10.1152/japplphysiol.00900.2002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To determine whether all- trans retinoic acid (RA) treatment enhances lung function during compensatory lung growth in fully mature animals, adult male dogs ( n = 4) received 2 mg·kg-1·day-1po RA 4 days/wk beginning the day after right pneumonectomy (R-PNX, 55-58% resection). Litter-matched male R-PNX controls ( n = 4) received placebo. After 3 mo, transpulmonary pressure (TPP)-lung volume relationship, diffusing capacities for carbon monoxide and nitric oxide, cardiac output, and septal volume (Vtiss-RB) were measured under anesthesia by a rebreathing technique at two lung volumes. Lung air and tissue volumes (Vair-CTand Vtiss-CT) were also measured from high-resolution computerized tomographic (CT) scans at a constant TPP. In RA-treated dogs compared with controls, TPP-lung volume relationships were similar. Diffusing capacities for carbon monoxide and nitric oxide were significantly impaired at a lower lung volume but similar at a high lung volume. Whereas Vtiss-RBwas significantly lower at both lung volumes in RA-treated animals, Vair-CTand Vtiss-CTwere not different between groups; results suggest uneven distribution of ventilation consistent with distortion of alveolar geometry and/or altered small airway function induced by RA. We conclude that RA does not improve resting pulmonary function during the early months after R-PNX despite histological evidence of its action in enhancing alveolar cellular growth in the remaining lung.
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Affiliation(s)
- D Merrill Dane
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390-9034, USA
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Abstract
For over a century, canines have been used to study adaptation to surgical lung resection or pneumonectomy (PNX) that results in a quantifiable and reproducible loss of lung units. As reviewed by Schilling (1965), the first successful experimental pneumonectomies were performed in dogs and rabbits in 1881. By the early 1920s, it was appreciated that dogs can function normally with one remaining lung that increases in volume to fill the thoracic cavity (Andrus, 1923; Heuer and Andrus, 1922; Heuer and Dunn, 1920); these pioneering observations paved the way for surgeons to perform major lung resection in patients. Reports in the 1950s (Schilling et al., 1956) detail surprisingly well-preserved work performance in dogs following staged resection of up to 70% of lung mass. Since then, the bulk of the literature on post-PNX adaptation has shifted to rodents, especially for defining molecular mediators of compensatory lung growth. Because rodents are smaller and easier to handle, more animals can be studied over a shorter duration, resulting in time and cost savings. On the other hand, key aspects of lung anatomy, development, and time course of response in the rodent do not mimic those in the human subject, and few rodent studies have related structural adaptation to functional consequences. In larger mammals, anatomical lung development more closely resembles that in humans, and physiological function can be readily measured. Because dogs are natural athletes, functional limits of compensation can be characterized relatively easily by stressing oxygen transport at peak exercise. Thus, the canine model remains useful for relating structure to function, defining sources and limits of adaptation as well as evaluating therapeutic manipulation. This chapter summarizes key concepts of compensatory lung growth that have been consolidated from canine studies: (i) structure-function relationships during adaptation, (ii) dysanaptic (unequal) nature of compensation, and (iii) signals for initiation of cellular growth.
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Affiliation(s)
- Connie C W Hsia
- Department of Internal Medicine, Pulmonary and Critical Care Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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Hsia CCW, Johnson RL, Wu EY, Estrera AS, Wagner H, Wagner PD. Reducing lung strain after pneumonectomy impairs oxygen diffusing capacity but not ventilation-perfusion matching. J Appl Physiol (1985) 2003; 95:1370-8. [PMID: 12794035 DOI: 10.1152/japplphysiol.00338.2003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
After pneumonectomy (Pnx), mechanical strain on the remaining lung is an important signal for adaptation. To examine how mechanical lung strain alters gas exchange adaptation after Pnx, we replaced the right lung of adult dogs with a custom-shaped inflatable silicone prosthesis. The prosthesis was kept 1) inflated (Inf) to reduce mechanical strain of the remaining lung and maintain the mediastinum in the midline, or 2) deflated (Def) to allow lung strain and mediastinal shift. Gas exchange was studied 4-7 mo later at rest and during treadmill exercise by the multiple inert gas elimination technique while animals breathed 21 and 14% O2 in balanced order. In the Inf group compared with Def group during hypoxic exercise, arterial O2 saturation was lower and alveolar-arterial O2 tension difference higher, whereas O2 diffusing capacity was lower at any given cardiac output. Dispersion of the perfusion distribution was similar between groups at rest and during exercise. Dispersion of the ventilation distribution was lower in the Inf group at rest, associated with a much higher respiratory rate, but rose to similar levels in both groups during hypoxic exercise. Mean pulmonary arterial pressure at a given cardiac output was higher in the Inf group, whereas peak cardiac output was similar between groups. Thus creating lung strain by post-Pnx mediastinal shift primarily enhances diffusive gas exchange with only minor effects on ventilation-perfusion matching, consistent with the generation of additional alveolar-capillary surfaces but not conducting airways and blood vessels.
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Affiliation(s)
- Connie C W Hsia
- Pulmonary and Critical Care Medicine, Dept. of Internal Medicine, Univ. of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9034, USA
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Hsia CCW, Yan X, Dane DM, Johnson RL. Density-dependent reduction of nitric oxide diffusing capacity after pneumonectomy. J Appl Physiol (1985) 2003; 94:1926-32. [PMID: 12562671 DOI: 10.1152/japplphysiol.00525.2002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Airway lengthening after pneumonectomy (PNX) may increase diffusive resistance to gas mixing (1/D(G)); the effect is accentuated by increasing acinar gas density but is difficult to detect from lung CO-diffusing capacity (Dl(CO)). Because lung NO-diffusing capacity (Dl(NO)) is three- to fivefold that of Dl(CO), whereas 1/D(G) for NO and CO are similar, we hypothesized that a density-dependent fractional reduction would be greater for Dl(NO) than for Dl(CO). We measured Dl(NO) and Dl(CO) at two tidal volumes (Vt) and with three background gases [helium (He), nitrogen (N(2)), and sulfur hexafluoride (SF(6))] in immature dogs 3 and 9 mo after right PNX (5 and 11 mo of age). At maturity (11 mo), background gas density had no effect on Dl(NO), Dl(CO), or Dl(NO)-to-Dl(CO) ratio in sham controls. In PNX animals, Dl(NO) declined 25-50% in SF(6) relative to He and N(2), and Dl(NO)/Dl(CO) declined approximately 50% in SF(6) relative to He at a Vt of 15 ml/kg, consistent with a significant 1/D(G). At 5 mo of age, Dl(NO)/Dl(CO) declined 25-45% in SF(6) relative to He and N(2) in both groups, but Dl(CO) increased paradoxically in SF(6) relative to N(2) or He by 20-60%. Findings suggest that SF(6), besides increasing 1/D(G), may redistribute ventilation and/or enhance acinar penetration of the convective front.
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Affiliation(s)
- Connie C W Hsia
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9034, USA
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