Evaluation of a Physical-Chemical Protocol for Porcine Tracheal Decellularization.

INTRODUCTION/OBJECTIVE: Tracheal resection with primary reconstruction is the definitive treatment for many tracheal benign and malignant diseases. When primary resection is not deemed feasible as a result of the length of the stenosis, airway transplantation may become a solution. Tissue engineering offers an alternative way for creating tracheal substitutes. The development of tracheal allograft transplantation includes the decellularized tracheal scaffolds made of extracellular matrix that are seeded with the receptor's cells. Many protocols are used to obtain a decellularized scaffold. Most of them consist of cyclical physical-chemical steps with enzymes. This study proposes a protocol for decellularization based only in physical-chemical steps. METHODS: Decellularization of pig tracheal segments was carried out using a standardized protocol consisting of freezing and thawing, 10 cycles of agitation, exposure to sodium deoxycholate, and washing. The degree of decellularization was determined by quantifying residual DNA. We also analyzed the morphology under hematoxylin and eosin staining. RESULTS: Fourteen porcine tracheal segments were decellularized. All scaffolds obtained showed less than 2% of residual DNA (mean 20 ± 8 ng/mg) when compared to the fresh samples (mean 850 ± 123 ng/mg), P = .001. Morphological analysis showed that the epithelium and mixed glands were completely removed. It was possible to identify residual nuclei inside the cartilaginous rings (73.7 ± 12 × 26 ± 8 nuclei/field, P < .001). CONCLUSION: The protocol tested was able to provide effective decellularization of porcine tracheas.

Airway pathology in severe asthma is related to airflow obstruction but not symptom control.

BACKGROUND: Patients with asthma present structural and inflammatory alterations that are believed to play a role in disease severity. However, airway remodeling and inflammation have not been extensively investigated in relation to both symptom control and airflow obstruction in severe asthmatics. We aimed to investigate several inflammatory and structural pathological features in bronchial biopsies of severe asthmatics that could be related to symptom control and airflow obstruction after standardized treatment. METHODS: Fifty severe asthmatics received prednisone 40 mg/d for 2 weeks and maintenance therapy with budesonide/formoterol 400/12 µg twice daily + budesonide/formoterol 200/6 µg as needed for 12 weeks. Endobronchial biopsies were performed at the end of 12 weeks. We performed extensive immunopathological analyses of airway tissue inflammation and remodeling features in patients stratified by asthma symptom control and by airflow obstruction. RESULTS: Airway tissue inflammation and remodeling were not associated with symptom control. Asthmatics with persistent airflow obstruction had greater airway smooth muscle (Asm) area with decreased periostin and transforming growth factor beta-positive cells within Asm bundles, in addition to lower numbers of chymase-positive mast cells in the submucosa compared to patients with nonpersistent obstruction. CONCLUSIONS: Symptom control in severe asthmatics was not associated with airway tissue inflammation and remodeling, although persistent airflow obstruction in these patients was associated with bronchial inflammation and airway structural changes.

Histopathological Findings Associated With Gastroesophageal Reflux Disease and Aspiration After Lung Transplantation: Initial Brazilian Single-Center Experience.

BACKGROUND: Gastro-esophageal reflux disease (GERD) and broncho-aspiration (BA) are known to increase the risk for chronic lung allograft dysfunction (CLAD). However, specific lung injury mechanisms are not clearly known. The objective of the study was to describe histopathological findings in surveillance lung transbronchial biopsies that can be correlated with episodes of BA in the lung allograft. METHODS: This retrospective analysis of surveillance transbronchial biopsies was performed in lung transplant recipients, with available data of broncho-alveolar fluid (cultures and cytology), lung function parameters, and esophageal functional tests. RESULTS: Were analyzed 11 patients, divided into 3 groups: (1) GERD group: 4 patients with GERD and CLAD diagnosis; (2) control group: 2 patients without GERD or CLAD; and (3) BA group: 5 patients with foreign material in lung biopsies. A histopathological pattern of neutrophilic bronchitis (NB) was present in 4 of 4 cases in the GERD group and in 1 of 5 cases in the BA group in 2 or more biopsy samples; culture samples were all negative; the 5 NB-positive patients developed CLAD and died (3/5) or needed re-transplantation (2/5). The other 3 patients in the BA group had GERD without NB or CLAD. Both patients in the control group had transient NB in biopsies with positive cultures but remained free of CLAD. CONCLUSIONS: Surveillance transbronchial biopsies may provide useful information other than the evaluation of acute cellular rejection and can help to identify high-risk patients for allograft dysfunction related to gastro-esophageal reflux.

Toll-like receptors 2, 3 and 4 and thymic stromal lymphopoietin expression in fatal asthma.

BACKGROUND: Airway inflammation in asthma involves innate immune responses. Toll-like receptors (TLRs) and thymic stromal lymphopoietin (TSLP) are thought to be involved in airway inflammation, but their expression in asthmatics' both large and small airways has not been investigated. OBJECTIVE: To analyse the expression of TLR2, TLR3, TLR4 and TSLP in large and small airways of asthmatics and compare their expression in smoking and non-smoking asthmatics; to investigate whether TLR expression is associated with eosinophilic or neutrophilic airway inflammation and with Mycoplasma pneumoniae and Chlamydophila pneumoniae infection. METHODS: Using immunohistochemistry and image analysis, we investigated TLR2, TLR3, TLR4 and TSLP expression in large and small airways of 24 victims of fatal asthma, FA, (13 non-smokers, 11 smokers) and nine deceased control subjects (DCtrl). TLRs were also measured in 18 mild asthmatics (MA) and 12 healthy controls (HCtrl). M. pneumoniae and C. pneumoniae in autopsy lung tissue were analysed using real-time polymerase chain reaction. Airway eosinophils and neutrophils were measured in all subjects. RESULTS: Fatal asthma patients had higher TLR2 in the epithelial and outer layers of large and small airways compared with DCtrls. Smoking asthmatics had lower TLR2 levels in the inner and outer layers of the small airways than non-smoking asthmatics. TSLP was increased in the epithelial and outer layers of the large airways of FA. FA patients had greater TLR3 expression in the outer layer of large airways and greater TLR4 expression in the outer layer of small airways. Eosinophilic airway inflammation was associated with TLR expression in the epithelium of FA. No bacterial DNA was detected in FA or DCtrls. MA and HCtrls had only a small difference in TLR3 expression. CONCLUSIONS AND CLINICAL RELEVANCE: Increased expression of TLR 2, 3 and 4 and TSLP in fatal asthma may contribute to the acute inflammation surrounding asthma deaths.

Exercise inhibits allergic lung inflammation.

Aerobic conditioning (AC) performed either during or after sensitization reduces allergic inflammation in mice; however, the effects of AC performed before and during allergic sensitization on airway inflammation are unknown. Mice were divided into Control, AC, OVA, and AC + OVA groups. Mice were trained in a treadmill followed by either ovalbumin (OVA) sensitization or saline administration. Peribronchial inflammation, OVA-specific IgE and IgG1 titers, the expression of Th1 and Th2 cytokines, and airway remodeling were evaluated, as well as the expression of Eotaxin, RANTES, ICAM-1, VCAM-1, TGF-ß and VEGF. Aerobic conditioning performed before and during allergic sensitization displayed an inhibitory effect on the OVA-induced migration of eosinophils and lymphocytes to the airways, a reduction of IgE and IgG1 titers and an inhibition of the expression of Th2 cytokines. The AC + OVA group also demonstrated reduced expression of ICAM-1, VCAM-1, RANTES, TGF-ß and VEGF, as well as decreased airway remodeling (p<0.05). The effects of AC before and during the sensitization process inhibit allergic airway inflammation and reduce the production of Th2 cytokines and allergen-specific IgE and IgG1.

Creatine activates airway epithelium in asthma.

Airway epithelium plays important roles in the pathophysiology of asthma. Creatine supplementation (Cr) was shown to increase asthma features in a murine model of allergic asthma; however, the role of the airway epithelium in this inflammatory response is not known. BALB/c mice were divided into control, creatine supplementation, ovalbumin-sensitized (OVA) and OVA plus creatine supplementation groups. OVA sensitization occurred on days 0, 14, 28 and 42, and ovalbumin challenge from days 21-53. Cr was also given on days 21-53. Total and differential cells counts in BALF were evaluated. Quantitative epithelial expression of interleukin (IL)-4, IL-5, IL-13, CCL11, CCL5, CCL2, iNOS, VCAM-1, ICAM-1, NF-κB, VEGF, TGF-ß, IGF-1, EGFR, TIMP-1, TIMP-2, MMP-9, MMP-12 and arginase II were performed. Cr increased the number of total cells and eosinophils in BALF, the epithelial content of goblet cells and the epithelial expression of IL-5, CCL2, iNOS, ICAM-1, NF-κB, TGF-ß, TIMP-1 and MMP-9 when compared to the control group (p<0.05). Creatine supplementation also exacerbated goblet cell proliferation, and IL-5 and iNOS expression by epithelial cells compared to the OVA group (p<0.01). Creatine up-regulates the pro-inflammatory cascade and remodelling process in this asthma model by modulating the expression of inflammatory mediators by epithelial cells.

High-affinity immunoglobulin E receptor expression is increased in large and small airways in fatal asthma.

BACKGROUND: IgE and its high-affinity receptor FcɛRI play an important role in allergy and asthma. The distribution of FcɛRI expression in the airways and within the airway wall, however, is largely unknown. OBJECTIVE: In this study, we aimed to map the distribution of FcɛRI in different layers of large airways (LA) and small airways (SA) in lung tissue from non-smoking and smoking patients who died of asthma [fatal asthma (FA)] and non-smoking controls (CTR). METHODS: Postmortem lung tissue from 24 cases of non-smoking FA, 13 smoking FA patients and from 19 subjects who died of non-pulmonary causes (CTR) was immunohistochemically stained for FcɛRI and AA1 (mast cell tryptase marker). The expression of these markers was analysed in inner, muscle, and outer layers of both LA and SA by image analysis. RESULTS: FcɛRI expression was higher in non-smoking and smoking FA compared with CTR in the inner and outer layer of SA. In the outer layer of LA, FcɛRI expression was higher in non-smoking FA compared with CTR. AA1 was higher in non-smoking FA compared with smoking FA and CTR in the outer layer of the SA, which was correlated with FcɛRI in this layer. CONCLUSION: Our results show that the expression of FcɛRI is higher in both LA and SA in FA compared with CTR. These differences are predominantly found in the outer layer where they can be attributed in part to the increased mast cell numbers. These results indicate an increased capacity to mount IgE-mediated reactions in FA, both in LA and SA.

Severe novel influenza A (H1N1) infection in cancer patients.

BACKGROUND: The natural history and consequences of severe H1N1 influenza infection among cancer patients are not yet fully characterized. We describe eight cases of H1N1 infection in cancer patients admitted to the intensive care unit of a referral cancer center. PATIENTS AND METHODS: Clinical data from all patients admitted with acute respiratory failure due to novel viral H1N1 infection were reviewed. Lung tissue was submitted for viral and bacteriological analyses by real-time RT-PCR, and autopsy was conducted on all patients who died. RESULTS: Eight patients were admitted, with ages ranging from 55 to 65 years old. There were five patients with solid organ tumors (62.5%) and three with hematological malignancies (37.5%). Five patients required mechanical ventilation and all died. Four patients had bacterial bronchopneumonia. All deaths occurred due to multiple organ failure. A milder form of lung disease was present in the three cases who survived. Lung tissue analysis was performed in all patients and showed diffuse alveolar damage in most patients. Other lung findings were necrotizing bronchiolitis or extensive hemorrhage. CONCLUSIONS: H1N1 viral infection in patients with cancer can cause severe illness, resulting in acute respiratory distress syndrome and death. More data are needed to identify predictors of unfavorable evolution in these patients.

Exercise reduces effects of creatine on lung.

We recently demonstrated that creatine supplementation increased some features of lung allergic sensitization in mice. On the other hand, other studies have shown that aerobic exercise inhibited allergic airway inflammation and remodeling. We hypothesized that aerobic exercise may decrease the exacerbatory effects of the creatine supplementation in a murine model of asthma. Balb/c mice were divided into six groups: Control, Creatine (Cr), Low Intensity Exercise+Creatine (Low+Cr), Ovalbumin (OVA), Ovalbumin+Creatine (OVA+Cr) and Ovalbumin+Creatine+Low Intensity Exercise (OVA+Cr+Low). OVA-sensitized groups were sensitized with OVA intraperitoneal injections (days 0, 14, 28, and 42). Aerosol challenge (OVA 1%) and Cr treatment (0.5 g/kg/day) were initiated on Day 21 until Day 53. Low intensity exercise began on day 22 and was sustained until day 50. Low intensity exercise in the presence of creatine supplementation in sensitized mice resulted in a decreased number of eosinophils in BALF (p<0.001) and in the airways (p<0.001), and a decreased density of inflammatory cells positive to IL-4 (p<0.001) and IL-5 (p<0.001), airway collagen (p<0.001) and elastic fibers (p<0.001) content, airway smooth muscle thickness (p<0.001) and bronchoconstriction index (p<0.05) when compared with OVA+Cr group. These results suggest that aerobic exercise reduces the exacerbatory effects of creatine supplementation in chronically sensitized mice.

Pulmonary periarterial inflammation in fatal asthma.

BACKGROUND: To date, little information has been available about pulmonary artery pathology in asthma. The pulmonary artery supplies the distal parts of the lungs and likely represents a site of immunological reaction in allergic inflammation. The objective of this study was to describe the inflammatory cell phenotype of pulmonary artery adventitial inflammation in lung tissue from patients who died of asthma. METHODS: We quantified the different inflammatory cell types in the periarterial region of small pulmonary arteries in lung tissue from 22 patients who died of asthma [fatal asthma (FA)] and 10 control subjects. Using immunohistochemistry and image analysis, we quantified the cell density for T lymphocytes (CD3, CD4, CD8), B lymphocytes (CD20), eosinophils, mast cells (chymase and tryptase), and neutrophils in the adventitial layer of pulmonary arteries with a diameter smaller than 500 microm. RESULTS: Our data (median/interquartile range) demonstrated increased cell density of mast cells [FA=271.8 (148.7) cells/mm2; controls=177.0 (130.3) cells/mm2, P=0.026], eosinophils [FA=23.1 (58.6) cells/mm2; controls=0.0 (2.3) cells/mm2, P=0.012], and neutrophils [FA=50.4 (85.5) cells/mm2; controls=2.9 (30.5) cells/mm2, P=0.009] in the periarterial space in FA. No significant differences were found for B and T lymphocytes or CD4+ or CD8+ subsets. Chymase/tryptase positive (MCCT) mast cells predominated over tryptase (MCT) mast cells in the perivascular arterial space in both asthma patients and controls [MCCT/(MCCT+MCT)=0.91 (0-1) in FA and 0.75 (0-1) in controls, P=0.86]. CONCLUSIONS: Our results show that the adventitial layer of the pulmonary artery participates in the inflammatory process in FA, demonstrating increased infiltration of mast cells, eosinophils, and neutrophils, but not of T and B lymphocytes.

Airway smooth muscle thickness in asthma is related to severity but not duration of asthma.

Asthma is characterised by an increased airway smooth muscle (ASM) area (ASM(area)) within the airway wall. The present study examined the relationship of factors including severity and duration of asthma to ASM(area). The perimeter of the basement membrane (PBM) and ASM(area) were measured on transverse sections of large and small airways from post mortem cases of fatal (n = 107) and nonfatal asthma (n = 37) and from control subjects (n = 69). The thickness of ASM (ASM(area)/PBM) was compared between asthma groups using multivariate linear regression. When all airways were considered together, ASM(area)/PBM (in millimetres) was increased in nonfatal (median 0.04; interquartile range 0.013-0.051; p = 0.034) and fatal cases of asthma (0.048; 0.025-0.078; p<0.001) compared with controls (0.036; 0.024-0.042). Compared with cases of nonfatal asthma, ASM(area)/PBM was greater in cases of fatal asthma in large (p<0.001) and medium (p<0.001), but not small, airways. ASM(area)/PBM was not related to duration of asthma, age of onset of asthma, sex or smoking. No effect due to study centre, other than that due to sampling strategy, was found. The thickness of the ASM layer is increased in asthma and is related to the severity of asthma but not its duration.

Extracellular matrix components and regulators in the airway smooth muscle in asthma.

There is an intimate relationship between the extracellular matrix (ECM) and smooth muscle cells within the airways. Few studies have comprehensively assessed the composition of different ECM components and its regulators within the airway smooth muscle (ASM) in asthma. With the aid of image analysis, the fractional areas of total collagen and elastic fibres were quantified within the ASM of 35 subjects with fatal asthma (FA) and compared with 10 nonfatal asthma (NFA) patients and 22 nonasthmatic control cases. Expression of collagen I and III, fibronectin, versican, matrix metalloproteinase (MMP)-1, -2, -9 and -12 and tissue inhibitor of metalloproteinase-1 and -2 was quantified within the ASM in 22 FA and 10 control cases. In the large airways of FA cases, the fractional area of elastic fibres within the ASM was increased compared with NFA and controls. Similarly, fibronectin, MMP-9 and MMP-12 were increased within the ASM in large airways of FA cases compared with controls. Elastic fibres were increased in small airways in FA only in comparison with NFA cases. There is altered extracellular matrix composition and a degradative environment within the airway smooth muscle in fatal asthma patients, which may have important consequences for the mechanical and synthetic functions of airway smooth muscle.

Inflammatory cell mapping of the respiratory tract in fatal asthma.

BACKGROUND: The site and distribution of inflammation in the airways of asthmatic patients has been largely investigated. Inflammatory cells are distributed in both large and small airways in asthma. It has been demonstrated that distal lung inflammation in asthma may significantly contribute to the pathophysiology of the disease. The upper airways have also been implicated in the overall asthmatic inflammation. Although it is now accepted that lung inflammation is not restricted to the intrapulmonary airways in asthma, little is known about cell distribution in the other lung compartments and their relation to the intrapulmonary airways. OBJECTIVE: We aimed to map the inflammatory process in fatal asthma (FA), from the upper airways to the lung parenchyma. METHODS: Eosinophil, neutrophil, mast cell and lymphocyte content were determined in nasal mucosa, the trachea, intrapulmonary airways and parenchyma (peribronchiolar and distal) of 20 patients with FA and 10 controls. RESULTS: Eosinophil content was higher in all studied areas in FA compared with controls (P<0.02). Mast cell content was higher in the outer area of larger airways, small membranous bronchioles and in peribronchiolar parenchyma of FA compared with controls (P<0.04). CD3+, CD4+and CD20+cells showed increased content in FA intrapulmonary airways compared with controls (P<0.05). There was a positive correlation between CD4+cell content in nasal mucosa and larger airways in asthmatics. Increased neutrophil content was observed only in peribronchiolar parenchyma of FA (P=0.028). CONCLUSION: Eosinophils present a widespread distribution within the respiratory tract in FA, from the nasal mucosa to the distal lung. The outer wall of small membranous bronchioles is the main site of inflammatory changes in FA. There is a localized distribution of alveolar inflammation at the peribronchiolar region for mast cells and neutrophils. Our findings provide further evidence of the importance of the lung periphery in the pathophysiology of FA.

Pulmonary amoebiasis presenting as superior vena cava syndrome.

Pulmonary amoebiasis without liver involvement occurs sporadically as a result of haematogenous spread from a primary site, the colon. The case history is presented of a patient who developed superior vena cava syndrome due to a pulmonary amoebic abscess without liver involvement. He was initially suspected of having a neoplasm but a combination of tests including histological examination of the H&E stained excised tissue, immunofluorescence using anti-Entamoeba histolytica antibodies, and serology confirmed the diagnosis of amoebiasis. To our knowledge this is the first description of pulmonary amoebiasis presenting as superior vena cava syndrome.

A simple method for the differential characterization of alveoli and alveolar ducts in injured lungs.

RATIONALE AND HYPOTHESIS: Previous studies evaluating the histoarchitecture of distal airspaces have been shown to be limited by the difficulty in adequately differentiating alveoli and alveolar ducts. This limitation has been specially noticed in studies addressing lung recruitment and in situations of diffuse alveolar damage (DAD), where generic nominations for distal airspaces had to be created, such as "peripheral airspaces" (PAS) and "large-volume gas-exchanging airspaces" (LVGEA). Elastic stains have been largely used to describe normal lung structures. Weigert's resorcin-fuchsin staining (WRF) demarcates the thickened free portions of the ductal septum facilitating its recognition. We hypothesized that this staining could help in differentiating alveoli from alveolar ducts in distorted lung parenchyma. MATERIAL AND METHODS: Samples of control lungs and of DAD lungs induced by mechanical ventilation (VILI) were stained with hematoxylin-eosin (HE) and with WRF. Using morphometry we assessed the volume proportion of alveoli, alveolar ducts and LVGEA in control and VILI lungs. RESULTS: WRF stained VILI lungs showed a significant decrease in the volume proportion of LVGEA and alveoli and a significant increase in the volume proportion of alveolar ducts when compared to HE stained samples. CONCLUSION: We conclude that WRF staining is useful to distinguish alveolar ducts from alveoli in a DAD model, and suggest that it should be routinely used when morphometric studies of lung parenchyma are performed.

Pneumoconiosis after sericite inhalation.

BACKGROUND: Between 1997 and 1999 three sericite plant workers in Parana, Brazil, were diagnosed with pneumoconiosis. AIMS: To investigate and describe the radiological, clinical, and pathological changes in miners and millers exposed to sericite dust with mineralogical characteristics of inhaled dust. METHODS: The working premises were visited to examine the sericite processing and to classify the jobs according to make qualitative evaluation. Respirable dust was collected and the amount of crystalline silica and particle size distribution were measured. Forty four workers were examined by a standard questionnaire for respiratory symptoms, spirometry, and chest x ray. Material from an open lung biopsy was reviewed for histopathological and mineralogical analysis, together with sericite samples from the work site to compare the mineral characteristics in lung lesions and work area. RESULTS: Respirable dust contained 4.5-10.0% crystalline silica. Particle size distribution showed a heavy burden of very fine particles (23-55%) with a mean diameter of <0.5 microm. Mean age of sericite miners was 41.0 (11.9) and mean number of years of exposure was 13.5 (10.1). In 52.3% of workers (23/44), chest radiographs presented a median category of 1/0 or above, and 18.2% (8/44) had a reduced FEV1. There was a significant association between exposure indices and x ray category. Histological studies of the lung biopsy showed lesions compatible with mixed dust fibrosis with no silicotic nodules. x Ray diffraction analysis of the lung dust residue and the bulk samples collected from work area showed similar mineralogical characteristics. Muscovite and kaolinite were the major mineral particle inclusions in the lung. CONCLUSION: Exposure to fine sericite particles is associated with the development of functional and radiological changes in workers inducing mixed dust lesions, which are distinct histologically from silicosis.

Morphological changes of carotid bodies in acute respiratory distress syndrome: a morphometric study in humans.

Carotid bodies are chemoreceptors sensitive to a fall of partial oxygen pressure in blood (hypoxia). The morphological alterations of these organs in patients with chronic obstructive pulmonary disease (COPD) and in people living at high altitude are well known. However, it is not known whether the histological profile of human carotid bodies is changed in acute clinical conditions such as acute respiratory distress syndrome (ARDS). The objective of the present study was to perform a quantitative analysis of the histology of carotid bodies collected from patients who died of ARDS. A morphometric study of carotid bodies collected during routine autopsies was carried out on three groups: patients that died of non-respiratory diseases (controls, N = 8), patients that presented COPD and died of its complications or associated diseases (N = 7), and patients that died of ARDS (N = 7). Morphometric measurements of the volume fraction of clusters of chief cells were performed in five fields on each slide at 40X magnification. The numerical proportion of the four main histological cell types (light, dark, progenitor and sustentacular cells) was determined analyzing 10 fields on each slide at 400X magnification. The proportion of dark cells was 0.22 in ARDS patients, 0.12 in controls (P<0.001), and 0.08 in the COPD group. The proportion of light cells was 0.33 (ARDS), 0.44 (controls) (P<0.001), and 0.36 (COPD). These findings suggest that chronic and acute hypoxia have different effects on the histology of glomic tissue.

Morphological changes of carotid bodies in acute respiratory distress syndrome: a morphometric study in humans

Carotid bodies are chemoreceptors sensitive to a fall of partial oxygen pressure in blood (hypoxia). The morphological alterations of these organs in patients with chronic obstructive pulmonary disease (COPD) and in people living at high altitude are well known. However, it is not known whether the histological profile of human carotid bodies is changed in acute clinical conditions such as acute respiratory distress syndrome (ARDS). The objective of the present study was to perform a quantitative analysis of the histology of carotid bodies collected from patients who died of ARDS. A morphometric study of carotid bodies collected during routine autopsies was carried out on three groups: patients that died of non-respiratory diseases (controls, N = 8), patients that presented COPD and died of its complications or associated diseases (N = 7), and patients that died of ARDS (N = 7). Morphometric measurements of the volume fraction of clusters of chief cells were performed in five fields on each slide at 40X magnification. The numerical proportion of the four main histological cell types (light, dark, progenitor and sustentacular cells) was determined analyzing 10 fields on each slide at 400X magnification. The proportion of dark cells was 0.22 in ARDS patients, 0.12 in controls (P<0.001), and 0.08 in the COPD group. The proportion of light cells was 0.33 (ARDS), 0.44 (controls) (P<0.001), and 0.36 (COPD). These findings suggest that chronic and acute hypoxia have different effects on the histology of glomic tissue

Repetitive high-pressure recruitment maneuvers required to maximally recruit lung in a sheep model of acute respiratory distress syndrome.

OBJECTIVE: To compare the effects of two different recruitment maneuvers repeated multiple times on gas exchange lung injury, hemodynamic, and lung mechanics. DESIGN: Randomized prospective comparison. SETTINGS: Animal research laboratory. SUBJECT: Nineteen fasted Hampshire sheep. INTERVENTIONS: In 15 27-kg sheep with saline lavage lung injury, we compared the effects of two recruitment maneuvers: 40 cm H2O continuous positive airway pressure for 60 secs and 40 cm H2O positive end-expiratory pressure with 20 cm H2O pressure control, rate 10 breaths/min, inspiratory to expiratory ratio 1:1 for 2 mins. Each recruitment maneuver was repeated four times, every 30 mins after a 30-sec ventilator disconnection. An additional group received no recruitment maneuvers. Animals were assigned randomly to the three groups and ventilated with 20 cm H2O positive end-expiratory pressure, pressure control 15 cm H2O, rate 20 breaths/min, inspiratory to expiratory ratio 1:1, and Fio2 1.0 between recruitment maneuver periods. MEASUREMENTS AND MAIN RESULTS: Significant and marked increases in Pao2 were observed in the pressure control recruitment maneuver group but only after the second recruitment maneuver. In both the control group and continuous positive airway pressure groups, Pao2 did not significantly increase after any recruitment maneuver compared with baseline injury. There was a significant decrease in cardiac output immediately after some continuous positive airway pressure recruitment maneuvers and a significant increase in mean pulmonary artery pressure in both continuous positive airway pressure and pressure control groups immediately after recruitment maneuvers, but these changes resolved within 10 mins. There were no marked histologic differences between groups and no volutrauma. CONCLUSION: In this model, maximal lung recruitment was obtained with 40 cm H2O positive end-expiratory pressure and 20 cm H2O pressure control applied repetitively every 30 mins for 2 mins without physiologic or histologic harm. Multiple recruitment maneuvers in some animals were required for maximum effect.

Extracellular matrix and oscillatory mechanics of rat lung parenchyma in bleomycin-induced fibrosis.

We investigated in vivo and in vitro oscillatory mechanics in bleomycin-induced fibrotic lungs and correlated these with morphometric changes in the collagen-elastin matrix and contractile cells. Fischer rats received bleomycin sulfate (BLEO,1.5 U) or saline intratracheally. Four weeks later tracheal flow and tracheal and alveolar pressure (using alveolar capsules) were measured in open-chested rats during mechanical ventilation (V T = 8 ml/kg, f = 1 Hz, PEEP = 4 cm H(2)O). Total lung, tissue, and airway resistance (R) and lung elastance (E) were calculated. In addition, excised parenchymal strips (10 x 2 x 2 mm) were studied in the organ bath. Strips were attached to a force transducer at one end and to a servo-controlled lever arm that effected length (L) changes at the other. Sinusoidal oscillations were applied (f = 1 Hz, amplitude = 2. 5% resting L and tension = 0.7 g) and R, E, and hysteresivity (eta) were calculated. Strips were then exposed to acetylcholine (ACh, 10(-)(3) M). The amount of collagen and elastic fibers in the parenchymal strip was assessed semiquantitatively by point-counting in 5-micrometer-thick sections stained with either Sirius Red or Weigert's Resorcin-fuchsin. alpha-Smooth-muscle-specific actin was detected immunohistochemically. Both in vivo and in vitro, R, E, and eta were significantly increased in BLEO rats (p < 0.05). The % increase in R, E and eta after Ach was greater in BLEO rats (p < 0. 01). There was also a significant increase in the volume proportion of collagen, elastic fibers, and actin in the parenchyma (p < 0.01). In BLEO rats, baseline R and E were correlated with the volume proportion of collagen in the parenchyma. We conclude that changes in the collagen-elastin matrix contribute to changes in the viscoelastic properties of bleomycin-treated rat lungs. Dolhnikoff M, Mauad T, Ludwig MS. Extracellular matrix and oscillatory mechanics of rat lung parenchyma in bleomycin-induced fibrosis.