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Query: UMLS:C0034067 (emphysema)
 11,506 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Research on the pathogenesis of experimental emphysema has involved studies of the distribution of and destruction of elastin in the alveolar interstitium. The ill-defined organization of elastin in the alveolar interstitium makes it difficult to identify the elastin specifically by staining procedures ordinarily used for electron microscopy. This problem becomes more significant when the elastic tissue is fragmented during emphysema development and localization of the elastin fragments is essential. Therefore, a specific technique using high-titer antibodies against purified canine lung elastin was developed. The primary antibody was used on preembedded or etched postembedded sections. Localization of the antielastin IgG was accomplished with ferritin-labeled rabbit antisheep IgG as the secondary antibody. Treatment with the preimmune serum gave negligible ferritin background staining. The antielastin antibody did not react with lung connective tissue proteins such as the microfibrillar component of elastin or collagen or proteoglycan. The antielastin antibody appeared to be species specific. The method may be useful for studies of experimental emphysema.
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PMID:Immunologic localization of elastin by electron microscopy. 8 14

Both clinical and experimental evidence implicate proteolytic enzymes active against elastin in the pathogenesis of emphysema. Paradoxically, however, the elastin content of emphysematous human lungs at autopsy has been normal. When emphysema was produced in hamsters by a single intratracheal injection of 25 units of porcine pancreatic elastase, the elastin content of the lungs was reduced from 1.40 +/- 0.22 mg. in controls to 0.43 +/- 0.10 mg. 24 hours after injection, and histologic sections showed that many elastic fibers had disappeared. The elastin content of the lungs gradually increased, approaching normal values by 2 months after injection. The incorporation of 14C-proline into elastin was markedly elevated during the first 2 weeks after injection, decreasing nearly to normal by 2 months. The synthesis of collagen was also increased, indicated by an increase in the collagen content of the lung, an increase in the prolyl hydroxylase activity, and an increase in incorporation of labeled proline into collagen. During the period of active resynthesis of elastin, small clumps of microfibrils and elastic fibrils were visible by electron microscopy within grooves on the surface of septal connective tissue cells in the lungs. Many elastic fibers seen in histologic sections up to 4 months after injection were of abnormal configuration and disorganized.
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PMID:The induction of emphysema with elastase. II. Changes in connective tissue. 17 9

A previous study of hamsters, 21 days after intratracheal treatment with pancreatic elastase, showed development of emphysema, shift of the volume-pressure curve up an to the left, with both air and saline filling, and increase in quasistatic lung compliance. There was also a striking increase in vital capacity and lung volume at transpulmonary pressure of 25 cm H2O (TLC25); however, 21 days after collagenase treatment, there was only a slight increase in TLC25. The lung volume changes were not consistent with the theory that the collagen fiber network is responsible for limiting distension of the lung. This report considers saline-filled volume-pressure curves studied in excised hamster lungs after incubation with endotracheally instilled pancreatic elastase or clostridial collagenase solutions. Fluid retained in the lungs after the first infusion-withdrawal cycle was significantly greater in lungs treated with elastase than in lungs treated with collagenase or in control lungs. Total fluid volume at full inflation was similar in the 3 groups. Chord compliance of lungs treated with collagenase was greater at high volume range than that in lungs treated with elastase or control lungs; chord compliance of elastase-treated lungs was higher at mid-volume range than that of collagenase-treated or control lungs. The results of these in vitro studies are consistent with the theory of independently functioning elastic and collagen fiber networks, with the latter limiting lung distensibility at high volumes, and the former providing great extensibility at low volumes. Events that are part of the repair process after elastase injury may result in a change in the orientation of collagen in alveolar tissue and appear to account for the differing effects of in vivo and in vitro elastase treatment on the static mechanical properties of the lungs.
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PMID:In vitro effects of elastase and collagenase on mechanical properties of hamster lungs. 18 Aug 55

Human polymorphonuclear neutrophilic leukocytes (PMNs) contain large amounts of neutral proteases that can degrade elastin, collagen, proteoglycan, and basement membrane. The instillation of one of the purified enzymes (elastase) into dog lungs in vivo causes degradation of elastic fibers and other alveolar septal components and results in anatomic changes similar to those of human pulmonary emphysema. Cigarette smoking is a major risk factor associated with pulmonary emphysema in man. One mechanism for this association may be interference with the regulation of PMN elastase activity by alveolar antiproteases. This possibility is supported by the observation that the oxidizing activity of tobacco smoke inactivates alpha 1-proteinase inhibitor in vitro. Macrophages also secrete an elastolytic protease, albeit at low levels. The short-term exposure of cultured mouse macrophages to cigarette smoke augments the rate of elastase secretion by these cells. Mouse macrophage elastase is not inhibited by alpha 1-proteinase inhibitor or alpha 2-macroglobulin. This unusual property of macrophage elastase may facilitate its attack upon elastin over prolonged intervals despite very low levels of macrophage elastase production. A unified hypothesis of lung injury in pulmonary emphysema is presented, involving both PMN and macrophage elastases and the actions of cigarette smoke. (Am J Pathol 97:111--136, 1979).
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PMID:Lung injury induced by leukocytic proteases. 49 91

Experimental emphysema in the guinea pig was made by intracheal instillation of porcine pancreatic elastase in order to analyze the proteolytic factors related to the pathogenesis of pulmonary emphysema. Ultrastructural and morphometric studies were performed in the elastase-induced emphysema in vivo. The following results were obtained: 1) Ultrastructural studies in vivo revealed that interstitial edema and degradation of fibrous tissue already occurred 2 hours after elastase instillation. Subsequently we observed fragmentations of elastin and dissociation between elastic tissue and collagen fibers 2 days later. Apparent degradation and fragmentation of elastin was found after 7 days. 2) Morphometric studies by electron microscope on elastase-induced experimental emphysema showed significant degradation of elastin fragments. Thus, it was suggested the importance of elastolytic process on the pathogenesis of pulmonary emphysema.
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PMID:Ultrastructural studies of elastase-induced experimental emphysema. 50 80

Following exposure to an aerosol of 0.1 per cent. (0.005M) cadmium chloride in physiologic saline, rat lungs were examined at 1 hour, 1, 2, 3, 4, 5, 7, 10 and 21 days. Light microscopy showed that damage was most marked about respiratory bronchioles with a prominent increase in interstitial cells. Up to 3 days the intestitial cells were closely packed and monocytic in type, but on the fourth and fifth days, the cellular density had decreased and elongated cells resembling fibroblasts appeared. By 7 days the interstitial cells were predominantly fibroblastic. Ultrastructurally the fibroblasts were active with prominent rough endoplasmic reticulum and numerous, single, haphazardly scattered collagen fibrils in lacunae at the cell margins. At 21 days after injury, interstitial collagen was seen as well organised, mature bundles. The fibrosis was seen in a peribronchiolar position with distoration of the bronchiole and adjacent alveoli. We suggest that the peribronchiolar localisation of fibrosis is the probable cause of centriacinar emphysema resulting from acute cadmium fume poisoning in man.
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PMID:Peribronchiolar fibrosis following acute experimental lung damage by cadmium aerosol. 51 43

An overview of the pulmonary macrophage is provided, with particular emphasis on the origin of this cell and the adaptive mechanisms whereby the macrophagic system is able to respond to increased inhalant loads of organic and inorganic pollutants. Evidence is presented which favors an hematopoietic origin for the alveolar macrophage with a monocytic transportation compartment in the blood and an interstitial cell compartment in the lung in which cellular division and maturation may occur. Through the simple mechanism of increased cellular turnover this system of mononuclear phagocytes rapidly adapts to most inhalant challenges. In addition to its primary tasks phagocyte and destroyer of microorganisms the macrophage plays a pivotal role in the genesis of silicotic fibrosis, and it is possible that similar mechanisms may hold for a variety of cryptogenic fibroses. Paradoxically, destruction of collagen by the dual mechanisms of phagocytosis and the secretion of lytic enzymes may also occur. The relevance of this secretory function of the macrophage to the pathogenesis of destructive diseases of the lung such as emphysema remains to be determined.
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PMID:The pulmonary macrophage. 79 68

To examine whether alteration of 7S collagen in the alveolar basement membrane is related to the condition and prognosis of diffuse interstitial lung diseases (idiopathic interstitial pneumonia: IIP, collagen vascular diseases, sarcoidosis, and hypersensitivity pneumonitis), we measured serum 7S collagen levels in 123 patients with diffuse interstitial lung disease and other lung diseases. Patients with diffuse lung diseases (diffuse interstitial lung disease, pulmonary emphysema, and diffuse panbronchiolitis: DPB) showed significantly higher serum levels of 7S collagen than healthy normal controls. Serum 7S collagen levels in IIP and collagen vascular diseases were significantly higher than those in pulmonary emphysema and DPB. In cases of IIP, serum 7S collagen levels in the active stage were significantly higher than those in the inactive stage. Furthermore, the prognosis of patients with higher serum 7S collagen levels was significantly poorer than those of patients with lower serum 7S collagen levels. In infectious pulmonary diseases, serum 7S collagen levels of patients with adult respiratory distress syndrome (ARDS) were significantly higher than those of patients without ARDS. Autopsy specimens obtained from patients with positive serum 7S collagen showed diffuse alveolar damage and/or diffuse pulmonary hemorrhage in the alveolar areas. Immunohistochemical staining for 7S collagen showed disruption and/or loss of the alveolar basement membrane. The authors conclude that serum level of 7S collagen is useful for estimating the activity of diffuse interstitial lung diseases as an index of the destruction of alveolar structure.
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PMID:[Serum 7S collagen levels in diffuse interstitial lung diseases--an index of the destruction of alveolar structure]. 128 29

In order to determine biological aggressiveness of settled dusts and dusts collected using the gravimetric method, experimental studies were carried out, including: 1) evaluation of the physicochemical parameters (size of dust particles, content of silica, metals and other chemical compounds); 2) evaluation of the haemolytic activity; 3) experimental of evaluation fibrogenic potentials by means of: a) intraperitoneal test--to identify morphological type of reactive changes in peritoneum and; b) intratracheal test--to determine the level of hydroxyproline (collagen) in lungs and the morphological type of reactive changes. Albino rats were used for the experiment. The animals were divided into ten groups which received a single intratracheal injection of 50 mg of mining dust in 0.9% NaCl suspension. Comparative evaluation of biological aggressiveness of mining dusts was conducted basing on findings of collagen levels in lungs. After the end of the experimental period (3 and 6 months) histopathological examination of the lungs and mediastinal lymph nodes was made and the collagen levels in the pulmonary tissue (following Stegeman) were determined. As evidenced by the results of the pathomorphological examination and statistical analysis: 1) after intratracheal injection the mining dusts induced changes within the respiratory system e.g. inflammatory process and emphysema.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Evaluation of fibrotic effects from dusts originating from KWK "Brzeszcze" on lung tissue]. 133 42

Pulmonary capillaries have extremely thin walls to allow rapid exchange of respiratory gases across them. Recently it has been shown that the wall stresses become very large when the capillary pressure is raised, and in anaesthetised rabbits, ultrastructural damage to the walls is seen at pressures of 40 mm Hg and above. The changes include breaks in the capillary endothelial layer, alveolar epithelial layer, and sometimes all layers of the wall. The strength of the thin part of the capillary wall can be attributed to the type IV collagen in the extracellular matrix. Stress failure of pulmonary capillaries results in a high-permeability form of oedema, or even frank haemorrhage, and is apparently the mechanism of neurogenic pulmonary oedema and high-altitude pulmonary oedema. It also explains the exercise-induced pulmonary haemorrhage that occurs in all racehorses. Several features of mitral stenosis are consistent with stress failure. Overinflation of the lung also leads to stress failure, a common cause of increased capillary permeability in the intensive care environment. Stress failure also occurs if the type IV collagen of the capillary wall is weakened by autoantibodies as in Goodpasture's syndrome. Neutrophil elastase degrades type IV collagen and this may be the starting point of the breakdown of alveolar walls that is characteristic of emphysema. Stress failure of pulmonary capillaries is a hitherto overlooked and potentially important factor in lung and heart disease.
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PMID:Stress failure of pulmonary capillaries: role in lung and heart disease. 809 42


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