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Query: UMLS:C0032285 (pneumonia)
 54,520 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The high in-hospital mortality of ARDS has not diminished over the past 10 years, despite improvements in supportive intensive care. Much of the mortality arises from infections, particularly sepsis and pneumonia, and from organ failure, especially kidney failure. The rapid advances in understanding the interlocking pathophysiologic mechanisms of ARDS have not yet been translated into therapeutic trials of new methods for diminishing the injury or for stimulating normal repair. In part, this is because it is difficult to predict which high-risk patients will develop ARDS and then intervene early in the injury process. Patients in whom the risk for ARDS is extremely high have a very high mortality even without ARDS, thereby making efficacy of an early or prophylactic therapy quite difficult to prove. In spite of severe pathologic abnormalities, including fibrosis, early in the course of ARDS, most survivors return to almost normal pulmonary function. The few cases that have been studied with serial biopsies demonstrate resolution of fibrosis. This amazing recovery poses many fascinating questions about how the lung repairs itself. Given the heterogeneous causes of ARDS and the large number of structural, cellular, and biochemical abnormalities described, one can postulate that any one of numerous factors is important in normal repair. Most promising of these are the degree of basement membrane damage, the control of type II cell proliferation and differentiation, the control of collagen synthesis, the anatomic localization of fibrosis, and the control of collagenase action. These interactions of epithelial and mesenchymal tissues probably recreate the process of lung development in the injured adult lung. At a clinical level, the role of oxygen toxicity remains a significant issue. Oxygen acting as an oxidant may be partially responsible for the small airways disease seen in approximately one quarter to one third of survivors. The mortality data stress the need for better ways of preventing and diagnosing lung infections. Better definition of the clinical factors that put survivors at risk for persistent loss of lung function is also needed, and could define a subgroup in which trials of agents designed to improve repair would be most worthwhile. More information about the long-term pathologic course, though difficult to obtain, would also be very important. Perhaps some registry of ARDS survivors would permit closer follow-up and make available more late autopsy pathology when these people die of other causes. The rapid time course of ARDS provides an ideal testing ground for agents designed to either decrease lung injury or stimulate repair.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Pulmonary sequelae and lung repair in survivors of the adult respiratory distress syndrome. 333 67

Sheep antibodies to bovine type I collagen were employed in the immunohistochemical detection of type I collagen in lung tissue sections of irradiated LAF1 mice. A video image digitizing system was developed to estimate collagen levels, by assigning a numerical value (0-63) to each of approximately 53,800 picture elements (pixels) in the microscope field, according to the collagen-dependent fluorescence intensity at each locus. For lungs harvested 52 weeks subsequent to graded doses of 60Co gamma radiation between 0 and 10 Gy, a dose-dependent increase in type I collagen was observed in the alveolar walls. A reproducible increase was evident for doses as low as 5 Gy: doses of 7 to 10 Gy elicited type I collagen levels significantly elevated with respect to those of age-matched controls. These results are consistent with a role for type I collagen in the development of radiation-induced pulmonary fibrosis. The assay system developed here will be used to explore the role of connective tissue macromolecules in the development of radiation pneumonitis and fibrosis.
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PMID:A semiquantitative probe for radiation-induced normal tissue damage at the molecular level. 351 95

Intranasal (or intratracheal) administration of a tissue-destructive protease from Legionella pneumophila to guinea-pigs produced areas of haemorrhagic pneumonia in the lungs after 1/2 h. By 24 h there was confluent consolidation in all lobes. Histological and ultrastructural studies showed alveolar haemorrhage, vesiculation and necrosis of type I alveolar epithelium and endothelium, followed by progressive exudation of oedema fluid, fibrin, PMN and macrophages. Damage to type II cell lamellated bodies and discharge of lamellar material were significant features of the lesion. Collagenase activity was indicated by morphological degradation of collagen fibres in severely affected interalveolar septa. The pathological changes of Legionnaires' disease pneumonia can thus be reproduced experimentally by the administration of a L. pneumophila tissue-destructive protease, suggesting that production of this protease in vivo during L. pneumophila infection may play an important role in causing the pneumonia.
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PMID:Pulmonary damage caused by a protease from Legionella pneumophila. 352 50

During a recent nosocomial outbreak, 20 critically ill patients with acute Legionnaires' disease were admitted to the intensive care unit of Hopital Bichat, Paris. Pulmonary specimens were obtained at surgery or immediately after death in 12 patients and were examined by light, immunofluorescent, and electron microscopy. Five of these 12 patients showed evidence of pulmonary fibrosis. In all of these five patients, infection with Legionella pneumophila was evidenced by bacteriologic methods, and other diseases known to cause fibrosis were excluded. The condition of four patients deteriorated rapidly with respiratory failure, and they died with pulmonary fibrosis. Only one patient finally recovered but was left with pulmonary sequelae. Two distinctive morphologic patterns were observed, one in which interstitial fibrosis was predominant and one in which intra-alveolar organization and fibrosis were also present. The alveolar epithelial lining and the basement membranes were disrupted in all patients, as evidenced by ultrastructural observations and by immunofluorescent studies showing gaps in the distribution of type 4 collagen and laminin. Types 1 and 3 collagen accumulated in areas corresponding to thickened interstitium and intra-alveolar fibrosis. Thus, some patients who survive the acute pneumonia of Legionnaires' disease may develop pulmonary fibrosis, and this process may lead to functional impairment or death despite prompt and appropriate treatment.
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PMID:Pulmonary fibrosis following pneumonia due to acute Legionnaires' disease. Clinical, ultrastructural, and immunofluorescent study. 353 46

This article outlines the principles of radiobiology that can explain the time of onset, duration, and severity of the complex reactions of the lung to ionizing radiation. These reactions have been assayed biochemically, cell kinetically, physiologically, and pathologically. Clinical and experimental data are used to describe the acute and late reactions of the lung to both external and internal radiation including pneumonitis, fibrosis and carcinogenesis. Acute radiation pneumonitis, which can be fatal, develops in both humans and animals within 6 months of exposure to doses greater than or equal to 8 Gy of low LET radiation. It is divisible into a latent period lasting up to 4 weeks; an exudative phase (3-8 weeks) and with an acute pneumonitic phase between 2 and 6 months. The latter is an inflammatory reaction with intra-alveolar and septal edema accompanied by epithelial and endothelial desquamation. The critical role of type II pneumonocytes is discussed. One favored hypothesis suggests that the primary response of the lung is an increase in microvascular permeability. The plasma proteins overwhelm the lymphatic and other drainage mechanisms and this elicits the secondary response of type II cell hyperplasia. This, in its turn, produces an excess of surfactant that ultimately causes the fall in compliance, abnormal gas exchange values, and even respiratory failure. The inflammatory early reaction may progress to chronic fibrosis. There is much evidence to suggest that pneumonitis is an epithelial reaction and some evidence to suggest that this early damage may not be predictive of late fibrosis. However, despite detailed work on collagen metabolism, the pathogenesis of radiation fibrosis remains unknown. The data on radiation-induced pulmonary cancer, both in man and experimental animals from both external and internal irradiation following the inhalation of both soluble and insoluble alpha and beta emitting radionuclides are reviewed. Emphasis is placed on the data showing that alpha emitters are at least an order of magnitude more hazardous than beta/gamma radiation and on recent data showing that the more homogeneous the irradiation of the lung, the greater is the carcinogenic hazard which contradicts the so-called "hot particle" theory.
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PMID:Radiation effects in the lung. 354 78

Altogether 274 patients with different pulmonary diseases were examined for the activity of trypsin and elastase of the blood and the level of their inhibitors. The concentration of antibodies to collagen and elastin was also measured. In acute chronic pneumonia or exacerbation, the activity of the enzymes increased, the concentration of antibodies to collagen and elastin rose. In acute pneumonia, the titer of antibodies to collagen and elastin persisted for 1-1.5 months, in CNPD and tuberculosis for 4-8 months.
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PMID:[Protease activity and the level of antibodies to connective tissue elements in various lung diseases]. 389 Feb 58

The histopathologic and ultrastructural features of intraluminal organizing and fibrotic changes were studied in open lung biopsies and autopsy specimens from 373 patients with interstitial lung disorders, including hypersensitivity pneumonitis (n = 44), idiopathic pulmonary fibrosis (n = 92), collagen-vascular diseases (n = 20), chronic eosinophilic pneumonia (n = 10), pulmonary histiocytosis X (n-90), pulmonary sarcoidosis (n = 62), pneumoconioses (n = 25), Legionnaire's disease (n = 5), drug- and toxin-induced pneumonitis (n = 4), radiation-induced pneumonitis (n = 2), lymphangioleiomyomatosis (n = 11), and chronic organizing pneumonia of unknown cause (n = 8). Three patterns of intraluminal organization and fibrosis were recognized: 1) intraluminal buds, which partially filled the alveoli, alveolar ducts and/or distal bronchioles; 2) obliterative changes, in which loose connective tissue masses obliterated the lumens of alveoli, alveolar ducts or distal bronchioles, and 3) mural incorporation of previously intraluminal connective tissue masses, which fused with alveolar, alveolar ductal, or bronchiolar structures and frequently became reepithelialized. All three patterns had common morphologic features, suggesting that, regardless of their severity, they resulted from a common pathogenetic mechanism, ie, the migration of activated connective tissue cells, through defects in the epithelial lining and its basement membrane, from the interstitial into the intraluminal compartment. Intraluminal buds were observed most frequently in hypersensitivity pneumonitis, chronic eosinophilic pneumonia, and organizing pneumonia of unknown cause. Mural incorporation and, to a lesser extent, obliterative changes were observed in most interstitial disorders and were very prominent in idiopathic pulmonary fibrosis. Mural incorporation and obliterative changes play an important role in pulmonary remodeling, especially when several adjacent alveoli and/or other air spaces are involved. Under these circumstances, intraluminal organization can mediate the fusion of adjacent alveolar structures by intraluminal connective tissue.
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PMID:Intraluminal fibrosis in interstitial lung disorders. 395 68

Collagenolytic enzyme release in alveolar structures is probably one of the initial events leading to impaired balance between collagen synthesis and degradation in the connective matrix of the lung, resulting in pulmonary fibrosis. The collagenolytic activity was determined in the bronchoalveolar fluid of 40 normal subjects or patients with miscellaneous pulmonary diseases and was found to be present in seventeen, viz.: 7/7 patients with interstitial fibrosis, irrespective of its origin: 4/4 patients with radiation pneumonitis; 4/15 patients with sarcoidosis and 2/2 patients with transient eosinophilic pneumopathy. There was no evidence of fibrosis in the 23 patients who showed no collagenolytic activity. Thus, collagenolytic enzymes are present in the alveolar structures of patients with interstitial pulmonary diseases of diverse origin capable of leading to fibrosis. Monitoring the release of this enzyme by bronchoalveolar lavage could be useful to evaluate the risk of fibrosis in such patients.
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PMID:[Fibrotic interstitial pneumopathies. Collagenolytic activity of the alveolar fluid]. 622 16

72 cases of diffuse interstitial lung diseases were observed from 1969 to 1976. Specimens removed from 47 patients were subjected to the whole spectrum of reactions. According to variation of both elastin and collagen, the following groups were outlined: group A: mycobacteriosis, farmer's lung, sarcoidosis and silicosis; group B: chronic eosinophilic pneumonia, lymphocytic interstitial pneumonia, post-tuberculous pulmonary fibrosis, and group C: X-ray pneumopathy, desquamative interstitial pneumonia, sclerodermic pneumopathy and chronic pulmonary fibrosis (primary chronic fibroadenomyosis). Each of these groups presents a close relationship between histochemical, radiological, clinical and functional findings.
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PMID:Diffuse interstitial lung diseases: a histochemical approach. 623 29

Bronchoalveolar lavage (BAL) was carried out in six patients with radiation pneumonitis, the early radiation-induced lung damage that usually leads to radiation fibrosis. Protein analysis by immuno-electrophoresis and polyacrylamide gel electrophoresis of BAL fluid revealed leakage of circulatory proteins, including high molecular weight components. Cell count of BAL fluid showed an increased number of lymphocytes; these proved to be activated on cell cycle analysis in one patient. Collagenolytic activity, assessed by degradation of radiolabelled type I human collagen, was present in BAL fluid of all six patients. The following mechanisms are therefore considered to participate in the pathogenesis of radiation-induced lung damage: 1) permeability oedema, which led to acute respiratory distress syndrome in one case of hyperacute radiation pneumonitis, 2) lymphocyte alveolitis possibly perpetuated by activated lymphocytes, and 3) release of collagenolytic enzymes in alveolar structures contributing to fibrotic processes.
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PMID:Bronchoalveolar lavage in radiation pneumonitis. 647 94


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