scholarly journals Age-dependent changes of airway and lung parenchyma in C57BL/6J mice

2007 ◽  
Vol 102 (1) ◽  
pp. 200-206 ◽  
Author(s):  
Kewu Huang ◽  
Richard Rabold ◽  
Brian Schofield ◽  
Wayne Mitzner ◽  
Clarke G. Tankersley
Keyword(s):  
Respiratory System ◽  
Elastic Fiber ◽  
Lung Parenchyma ◽  
Tissue Mechanics ◽  
Fiber Content ◽  
Collagen Content ◽  
Lung Mechanics ◽  
Elastin Fiber ◽  
Age Dependent ◽  
Tissue Elastance

In the current study, we hypothesize that senescent-dependent changes between airway and lung parenchymal tissues of C57BL/6J (B6) mice are not synchronized with respect to altered lung mechanics. Furthermore, aging modifications in elastin fiber and collagen content of the airways and lung parenchyma are remodeling events that differ with time. To test these hypotheses, we performed quasi-static pressure-volume (PV) curves and impedance measurements of the respiratory system in 2-, 20-, and 26-mo-old B6 mice. From the PV curves, the lung volume at 30 cmH2O pressure (V30) and respiratory system compliance (Crs) were significantly ( P < 0.01) increased between 2 and 20 mo of age, representing about 80–84% of the total increase that occurred between 2 and 26 mo of age. Senescent-dependent changes in tissue damping and tissue elastance were analogous to changes in V30 and Crs; that is, a majority of the parenchymal alterations in the lung mechanics occurred between 2 and 20 mo of age. In contrast, significant decreases in airway resistance (R) occurred between 20 and 26 mo of age; that is, the decrease in R between 2 and 20 mo of age represented only 29% ( P > 0.05) of total decrease occurring through 26 mo. Morphometric analysis of the elastic fiber content in lung parenchyma was significantly ( P < 0.01) decreased between 2 and 20 mo of age. To the contrary, increased collagen content was significantly delayed until 26 mo of age ( P < 0.01, 2 vs. 26 mo). In conclusion, our data demonstrate that senescent-dependent changes in airway and lung tissue mechanics are not synchronized in B6 mice. Moreover, the reduction in elastic fiber content with age is an early lung remodeling event, and the increased collagen content in the lung parenchyma occurs later in senescence.

scholarly journals Variation in senescent-dependent lung changes in inbred mouse strains

2007 ◽  
Vol 102 (4) ◽  
pp. 1632-1639 ◽  
Author(s):  
Kewu Huang ◽  
Wayne Mitzner ◽  
Richard Rabold ◽  
Brian Schofield ◽  
Hannah Lee ◽  
...  
Keyword(s):  
Gene Expression ◽  
Matrix Metalloproteinase ◽  
Inbred Mouse ◽  
Elastic Fiber ◽  
Lung Parenchyma ◽  
Inbred Strains ◽  
Lung Mechanics ◽  
Mouse Strains ◽  
Elastic Recoil ◽  
Age Dependent

Previous studies from our laboratories showed lung development differences between inbred strains of mice. In the present study, the C57BL/6J (B6) and DBA/2J (D2) strains were examined for senescent-dependent differences with respect to the lung structure and function. Specifically, we hypothesize that senescent changes in lung vary between strains due to identifiable gene expression differences. Quasi-static pressure-volume curves and respiratory impedance measurements were performed on 2- and 20-mo-old B6 and D2 mice. Lung volume at 30 cmH2O (V30) pressure was significantly ( P < 0.01) increased with age in both strains, but the increase was proportionally greater in D2 (68%) than in B6 (40%) mice. In addition, decreased elastic recoil pressure at 50% of V30 and a reduction in airway resistance as a function of positive end-expiratory pressure were observed in 20-mo-old D2 mice but not in B6 mice. Morphometric analysis of lung parenchyma showed significant decreases in elastic fiber content with age in both strains, but the collagen content was significantly ( P < 0.01) increased with age in D2 but not B6 mice at 20 mo. Furthermore, using quantitative RT-PCR methods, gene expression differences between strains suggested that D2 mice significantly ( P < 0.05) downregulated the expressions of elastin ( Eln) and procollagen I, III, and VI ( Col1a1, Col3a1, and Col6a3) in lung tissue at 20 mo of age. These age-dependent changes were accompanied by an increased gene expression in matrix metalloproteinase 9 ( Mmp9) in D2 and an increase in tissue inhibitor of matrix metalloproteinase ( Timp1 and Timp4) in B6 mice. In conclusion, the results from the present study demonstrate that lung mechanics of both strains show significant age-dependent changes. However, changes in D2 mice are accelerated relative to B6 mice. Moreover, gene expression differences appear to be involved in the strain-specific changes of lung mechanic properties.

Variability in preterm lamb lung mechanics after intra-amniotic endotoxin is associated with changes in surfactant pool size and morphometry

2004 ◽  
Vol 287 (5) ◽  
pp. L992-L998 ◽  
Author(s):  
J. Jane Pillow ◽  
Alan H. Jobe ◽  
Rachel A. Collins ◽  
Zoltán Hantos ◽  
Machiko Ikegami ◽  
...  
Keyword(s):  
Low Frequency ◽  
Tissue Mechanics ◽  
Pool Size ◽  
Lung Mechanics ◽  
Forced Oscillation Technique ◽  
Respiratory Impedance ◽  
Tissue Impedance ◽  
Lung Structure ◽  
Alveolar Surfactant ◽  
Tissue Elastance

Antenatal exposure to intra-amniotic (IA) endotoxin initiates a complex series of events, including an inflammatory cascade, increased surfactant production, and alterations to lung structure. Using the low frequency forced oscillation technique as a sensitive tool for measurement of respiratory impedance, we aimed to determine which factors contributed most to measured changes in lung mechanics. Respiratory impedance data obtained from sedated preterm lambs exposed to either IA injection with saline or 20 mg of endotoxin 1, 2, 4, and 15 days before delivery at 125 days gestation were studied, and association with indexes of standard lung morphometry, inflammatory response, and alveolar surfactant-saturated phosphatidylcholine (Sat PC) pool size was demonstrated. Reduction in tissue impedance with increasing interval between exposure and delivery was evident as early as 4 days after IA endotoxin injection, coinciding with resolution of inflammatory reaction, increased alveolar surfactant pools, and contribution of alveolar ducts to the parenchymal fraction, and a later decrease in the tissue component of the parenchymal fraction. Decreases in tissue damping (resistance) were more marked than decreases in tissue elastance. Log alveolar Sat PC accounted for most variability in tissue damping (88.9%) and tissue elastance (73.4%), whereas tissue fraction contributed 2 and 6.4%, respectively. The alveolar Sat PC pool size was the sole factor contributing to change in tissue hysteresivity. No changes were observed in airway resistance. Despite the complex cascade of events initiated by antenatal endotoxin exposure, variability in lung tissue mechanics is associated primarily with changes in alveolar Sat PC pool and lung morphology.

Effects of lung volume on lung and chest wall mechanics in rats

1999 ◽  
Vol 86 (1) ◽  
pp. 16-21 ◽  
Author(s):  
T. Hirai ◽  
K. A. McKeown ◽  
R. F. M. Gomes ◽  
J. H. T. Bates
Keyword(s):  
Chest Wall ◽  
Respiratory System ◽  
Lung Volume ◽  
Small Animal ◽  
Tissue Mechanics ◽  
Lung Mechanics ◽  
Open Chest ◽  
Pressure Volume Relationship ◽  
Volume Resistance ◽  
Relationship Of

To investigate the effect of lung volume on chest wall and lung mechanics in the rats, we measured the impedance (Z) under closed- and open-chest conditions at various positive end-expiratory pressures (0–0.9 kPa) by using a computer-controlled small-animal ventilator (T. F. Schuessler and J. H. T. Bates. IEEE Trans. Biomed. Eng. 42: 860–866, 1995) that we have developed for determining accurately the respiratory Z in small animals. The Z of total respiratory system and lungs was measured with small-volume oscillations between 0.25 and 9.125 Hz. The measured Z was fitted to a model that featured a constant-phase tissue compartment (with dissipation and elastance characterized by constants G and H, respectively) and a constant airway resistance (Z. Hantos, B. Daroczy, B. Suki, S. Nagy, and J. J. Fredberg. J. Appl. Physiol. 72: 168–178, 1992). We matched the lung volume between the closed- and open-chest conditions by using the quasi-static pressure-volume relationship of the lungs to calculate Z as a function of lung volume. Resistance decreased with lung volume and was not significantly different between total respiratory system and lungs. However, G and H of the respiratory system were significantly higher than those of the lungs. We conclude that chest wall in rats has a significant influence on tissue mechanics of the total respiratory system.

scholarly journals Hyperoxia-induced changes in mouse lung mechanics: forced oscillations vs. barometric plethysmography

2001 ◽  
Vol 90 (6) ◽  
pp. 2221-2230 ◽  
Author(s):  
Ferenc Peták ◽  
Walid Habre ◽  
Yves R. Donati ◽  
Zoltán Hantos ◽  
Constance Barazzone-Argiroffo
Keyword(s):  
Respiratory System ◽  
Airway Resistance ◽  
Tissue Mechanics ◽  
Lung Damage ◽  
Lung Mechanics ◽  
Forced Oscillations ◽  
Whole Body ◽  
Mouse Lung ◽  
Diffuse Lung Disease ◽  
Respiratory System Resistance

Hyperoxia-induced lung damage was investigated via airway and respiratory tissue mechanics measurements with low-frequency forced oscillations (LFOT) and analysis of spontaneous breathing indexes by barometric whole body plethysmography (WBP). WBP was performed in the unrestrained awake mice kept in room air ( n = 12) or in 100% oxygen for 24 ( n = 9), 48 ( n = 8), or 60 ( n = 9) h, and the indexes, including enhanced pause (Penh) and peak inspiratory and expiratory flows, were determined. The mice were then anesthetized, paralyzed, and mechanically ventilated. Airway resistance, respiratory system resistance at breathing frequency, and tissue damping and elastance were identified from the LFOT impedance data by model fitting. The monotonous decrease in airway resistance during hyperoxia correlated best with the increasing peak expiratory flow. Respiratory system resistance and tissue damping and elastance were unchanged up to 48 h of exposure but were markedly elevated at 60 h, with associated decreases in peak inspiratory flow. Penh was increased at 24 h and sharply elevated at 60 h. These results indicate no adverse effect of hyperoxia on the airway mechanics in mice, whereas marked parenchymal damage develops by 60 h. The inconsistent relationships between LFOT parameters and WBP indexes suggest that the changes in the latter reflect alterations in the breathing pattern rather than in the mechanical properties. It is concluded that, in the presence of diffuse lung disease, Penh is inadequate for characterization of the mechanical status of the respiratory system.

Effects of undernutrition on respiratory mechanics and lung parenchyma remodeling

2004 ◽  
Vol 97 (5) ◽  
pp. 1888-1896 ◽  
Author(s):  
Cristina Márcia Dias ◽  
Caroline P. Pássaro ◽  
Viviane Ramos Cagido ◽  
Marcelo Einicker-Lamas ◽  
Jennifer Lowe ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Bronchoalveolar Lavage ◽  
Chest Wall ◽  
Bronchoalveolar Lavage Fluid ◽  
Elastic Fiber ◽  
Lavage Fluid ◽  
Fiber Content ◽  
Lung Mechanics ◽  
Type I ◽  
Ctrl Group

Undernutrition thwarts lung structure and function, but there are disagreements about the behavior of lung mechanics in malnourished animals. To clarify this issue, lung and chest wall mechanical properties were subdivided into their resistive, elastic, and viscoelastic properties in nutritionally deprived (ND) rats and correlated with the data gathered from histology (light and electron microscopy and elastic fiber content), and bronchoalveolar lavage fluid analysis (lipid and protein content). Twenty-four Wistar rats were assigned into two groups. In the control (Ctrl) group the animals received food ad libitum. In the ND group, rats received one-third of their usual daily food consumption until they lost 40% of their initial body weight. Lung static elastance, viscoelastic and resistive pressures (normalized by functional residual capacity), and chest wall pressures were higher in the ND group than in the Ctrl group. The ND group exhibited patchy atelectasis, areas of emphysema, interstitial edema, and reduced elastic fiber content. The amount of lipid and protein in bronchoalveolar lavage fluid was significantly reduced in the ND group. Electron microscopy showed 1) type II pneumocytes with a reduction in lamellar body content, multilamellated structures, membrane vesicles, granular debris, and structurally aberrant mitochondria; and 2) diaphragm and intercostals with atrophy, disarrangement of the myofibrils, and deposition of collagen type I fibers. In conclusion, undernutrition led to lung and chest wall mechanical changes that were the result from a balance among the following modifications: 1) distorted structure of diaphragm and intercostals, 2) surfactant content reduction, and 3) decrease in elastic fiber content.

Oral tolerance attenuates changes in in vitro lung tissue mechanics and extracellular matrix remodeling induced by chronic allergic inflammation in guinea pigs

2008 ◽  
Vol 104 (6) ◽  
pp. 1778-1785 ◽  
Author(s):  
Adriane S. Nakashima ◽  
Carla M. Prado ◽  
Tatiana Lanças ◽  
Viviane C. Ruiz ◽  
David I. Kasahara ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Lung Tissue ◽  
Guinea Pigs ◽  
Oral Tolerance ◽  
Elastic Fiber ◽  
Allergic Inflammation ◽  
Tissue Mechanics ◽  
Fiber Content ◽  
Extracellular Matrix Remodeling ◽  
Matrix Remodeling

Recent studies emphasize the presence of alveolar tissue inflammation in asthma. Immunotherapy has been considered a possible therapeutic strategy for asthma, and its effect on lung tissue had not been previously investigated. Measurements of lung tissue resistance and elastance were obtained before and after both ovalbumin and acetylcholine challenges. Using morphometry, we assessed eosinophil and smooth muscle cell density, as well as collagen and elastic fiber content, in lung tissue from guinea pigs with chronic pulmonary allergic inflammation. Animals received seven inhalations of ovalbumin (1–5 mg/ml; OVA group) or saline (SAL group) during 4 wk. Oral tolerance (OT) was induced by offering ad libitum ovalbumin 2% in sterile drinking water starting with the 1st inhalation (OT1 group) or after the 4th (OT2 group). The ovalbumin-exposed animals presented an increase in baseline and in postchallenge resistance and elastance related to baseline, eosinophil density, and collagen and elastic fiber content in lung tissue compared with controls. Baseline and post-ovalbumin and acetylcholine elastance and resistance, eosinophil density, and collagen and elastic fiber content were attenuated in OT1 and OT2 groups compared with the OVA group. Our results show that inducing oral tolerance attenuates lung tissue mechanics, as well as eosinophilic inflammation and extracellular matrix remodeling induced by chronic inflammation.

scholarly journals Different contributions from lungs and chest wall to respiratory mechanics in mice, rats, and rabbits

2019 ◽  
Vol 127 (1) ◽  
pp. 198-204 ◽  
Author(s):  
Roberta Südy ◽  
Gergely H. Fodor ◽  
André Dos Santos Rocha ◽  
Álmos Schranc ◽  
József Tolnai ◽  
...  
Keyword(s):  
Chest Wall ◽  
Respiratory System ◽  
Respiratory Mechanics ◽  
Esophageal Pressure ◽  
Tissue Mechanics ◽  
Lung Mechanics ◽  
Laboratory Animals ◽  
Forced Oscillation Technique ◽  
Small Laboratory ◽  
Positive End Expiratory Pressure

Changes in lung mechanics are frequently inferred from intact-chest measures of total respiratory system mechanics without consideration of the chest wall contribution. The participation of lungs and chest wall in respiratory mechanics has not been evaluated systematically in small animals commonly used in respiratory research. Thus, we compared these contributions in intact-chest mice, rats, and rabbits and further characterized the influence of positive end-expiratory pressure (PEEP). Forced oscillation technique was applied to anesthetized mechanically ventilated healthy animals to obtain total respiratory system impedance (Zrs) at 0, 3, and 6 cmH2O PEEP levels. Esophageal pressure was measured by a catheter-tip micromanometer to separate Zrs into pulmonary (ZL) and chest wall (Zcw) components. A model containing a frequency-independent Newtonian resistance (RN), inertance, and a constant-phase tissue damping (G) and elastance (H) was fitted to Zrs, ZL, and Zcw spectra. The contribution of Zcw to RN was negligible in all species and PEEP levels studied. However, the participation of Zcw in G and H was significant in all species and increased significantly with increasing PEEP and animal size (rabbit > rat > mice). Even in mice, the chest wall contribution to G and H was still considerable, reaching 47.0 ± 4.0(SE)% and 32.9 ± 5.9% for G and H, respectively. These findings demonstrate that airway parameters can be assessed from respiratory system mechanical measurements. However, the contribution from the chest wall should be considered when intact-chest measurements are used to estimate lung parenchymal mechanics in small laboratory models (even in mice), particularly at elevated PEEP levels. NEW & NOTEWORTHY In species commonly used in respiratory research (rabbits, rats, mice), esophageal pressure-based estimates revealed negligible contribution from the chest wall to the Newtonian resistance. Conversely, chest wall participation in the viscoelastic tissue mechanical parameters increased with body size (rabbit > rat > mice) and positive end-expiratory pressure, with contribution varying between 30 and 50%, even in mice. These findings demonstrate the potential biasing effects of the chest wall when lung tissue mechanics are inferred from intact-chest measurements in small laboratory animals.

Age-dependent variations of diastolic stiffness and collagen content in rat ventricular myocardium

1984 ◽  
Vol 92 (2) ◽  
pp. 93-106 ◽  
Author(s):  
Vanda Cappelli ◽  
R. Forni ◽  
C. Poggesi ◽  
C. Reggiani ◽  
L. Ricciardi
Keyword(s):  
Ventricular Myocardium ◽  
Collagen Content ◽  
Diastolic Stiffness ◽  
Age Dependent

scholarly journals Lung Mechanics in Type L CoVID-19 Pneumonia: A Pseudo-Normal ARDS.

2020 ◽  
Author(s):  
Lorenzo Viola ◽  
Emanuele Russo ◽  
Marco Benni ◽  
Emiliano Gamberini ◽  
Alessandro Circelli ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Respiratory System ◽  
Respiratory Mechanics ◽  
Blood Gases ◽  
Lung Mechanics ◽  
Prone Positioning ◽  
Arterial Blood Gases ◽  
Arterial Blood ◽  
Esophageal Balloon ◽  
Early Phases

Abstract Background. This study was conceived to provide systematic data about lung mechanics during early phases of CoVID-19 pneumonia, as long as to explore its variations during prone positioning. Methods. We enrolled four patients hospitalized in the Intensive Care Unit of “M. Bufalini” hospital, Cesena (Italy); after the positioning of an esophageal balloon, we measured mechanical power, respiratory system and transpulmonary parameters and arterial blood gases every 6 hours, just before decubitus change and 1 hour after prono-supination. Results. Both respiratory system and transpulmonary compliance and driving pressure confirmed the pseudo-normal respiratory mechanics of early CoVID-19 pneumonia (respectively, CRS 40.8 ml/cmH2O and DPRS 9.7 cmH2O; CL 53.1 ml/cmH2O and DPL 7.9 cmH2O). Interestingly, prone positioning involved a worsening in respiratory mechanical properties (CRS,SUP 56.3 ml/cmH2O and CRS,PR 41.5 ml/cmH2O – P 0.37; CL,SUP 80.8 ml/cmH2O and CL,PR 53.2 ml/cmH2O – P 0.23). Conclusions. Despite the severe ARDS pattern, respiratory system and lung mechanical properties during CoVID-19 pneumonia are pseudo-normal and tend to worsen during pronation. Trial registration. Restrospectively registered.

How changes in the serial distribution of bronchoconstriction affect lung mechanics

1993 ◽  
Vol 74 (6) ◽  
pp. 2838-2847 ◽  
Author(s):  
F. M. Robatto ◽  
S. Simard ◽  
M. S. Ludwig
Keyword(s):  
Direct Effect ◽  
Coefficient Of Variation ◽  
Lung Parenchyma ◽  
Lung Mechanics ◽  
Response Curves ◽  
Mechanical Heterogeneity ◽  
Airway Constriction ◽  
Lung Resistance ◽  
Lung Periphery ◽  
Central Airway

It is generally accepted that methacholine (MCh) acts predominantly on the central airways and histamine (H) acts on the lung periphery. We hypothesized therefore that lung mechanics would be affected differently by H and MCh aerosols. In 12 anesthetized paralyzed open-chest mongrel dogs, we obtained MCh (0.1–30 mg/ml, n = 6) and H (0.1–30 mg/ml, n = 6) concentration-response curves. The alveolar capsule technique was used to partition lung resistance (RL) into airway (Raw) and tissue (Rti) components. The degree of mechanical heterogeneity across the lung was assessed by computing the coefficient of variation for five alveolar pressures during relaxed expirations. RL increased 823 +/- 202% after H and 992 +/- 219% after MCh. Rti increased 784 +/- 192% after H and 1,014 +/- 279% after MCh. Raw increased 1,098 +/- 297% after H and 1,275 +/- 332% after MCh. Elastance increased 342 +/- 53% after H and 423 +/- 88% after MCh. The coefficient of variation increased 279 +/- 65% after H and 252 +/- 55% after MCh. The patterns of change were similar throughout the H and MCh concentration-response curves. We conclude that H and MCh have comparable effects on lung mechanics and that the degree and pattern of heterogeneity inside the lung after constriction are the same regardless of the agent used. These data support the hypothesis that H and MCh have some similar direct effect on the lung parenchyma. Parenchymal deformation after MCh-induced central airway constriction alone would be unlikely to explain increases in Rti of this magnitude or changes in lung mechanics so similar to those induced by H.

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