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

Emphysema was induced in rats by chronic exposure to a papain aerosol according to established methods. The emphysematous changes were evaluated by previously described histological and biochemical parameters and by a new method employing infiltration of the lungs with vinyl acetate to make casts of the air spaces of the pulmonary tree. The weights and gross and microscopic appearance of the casts demonstrated the emphysematous changes in lungs of the papain-treated rats. Vinyl acetate casting may offer a new and useful tool in evaluating experimental induction of emphysema in rats.
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PMID:Vinyl acetate casts of emphysematous rat lungs. 6 Apr 83

The soluble material derived from the respirable fraction of mouldy hay dust has anti-complementary as well as enzyme activity. The anti-complementary activity resides in a heavy molecular weight fraction (approx. 800,000) and acts directly on C1 without combination with or alteration of IgG or IgM. The enzyme function has a lower molecular weight (approx. 30,000-38,000) and is related to papain in that IgG is split into two distinct components of similar molecular weight and with antigenic determinants the same as Fab and Fc pieces respectively. C1 activation leads to C3-9 depletion and on a per sample basis it is calculated that the soluble mouldy hay dust material is up to sixty-six times more active at C3-9 activation than the particulate material in mouldy hay dust. It is probable that the capacity to activate C1 resides in other dusts and may be a basis for non-immune histamine release in the lungs when such a dust is inhaled. It is also probable that non-specific skin reactions are related to C1 activation. The finding of an enzyme with papain-like activity is significant since the introduction of papain into the lungs of the experimental animal leads to emphysema and this has been described as a feature of farmer's lung.
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PMID:The effect of soluble material from mouldy hay dust on the complement system. 11 44

By intratracheal injection of the protease Papain to experimental animals parenchymal changes in the lung can be induced, that resemble human emphysema. Papain (dosage 26 to 112 mg, 1 to 4 injections) was given intratracheally to 8 bastard dogs, (weighing from 12.5 to 20 kg) during light general anesthesia. Pulmonary function was assessed in weekly intervals and related to morphologic changes in the lung. Static compliance of the lung and FRC measured during respiratory arrest were increased after papain, bronchial resistance, measured while artificially ventilated at constant pressure was also increased. Changes of static lung compliance and FRC were seen after the first administration of papain, but further increased with time of observation and after multiple doses of papain. Increase of resistance was not found before 5 weeks. At quiet breathing resistance was not increased at all. No significant changes were found of arterial pO2 and pCO2, pH, standard and actual bicarbonate, diffusion capacity for O2, tidal volume, minute ventilation and ventilatory rate. Morphological findings confirmed the changes described by others. Pulmonary function appears to be pathological at a time when morphology still seems to be normal. The question is discussed to what extent the model of experimental emphysema induced by proteolytic enzymes can contribute to the understanding of human pulmonary emphysema. Lung function in the course of experimental emphysema is compared with function in different clinical types of emphysema.
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PMID:[Pulmonary function in papain induced emphysema in dogs (author's tranls)]. 24 21

As part of an evaluation of the effects of left lung transplantation in dogs with papain emphysema of the right lung, differential lung blood flows were estimated by in vivo scintiscan of 99Mc-macroaggregated albumin (99mTc-MAA) and, after sacrifice, by direct counting of isotopically labeled carbonized microspheres. In six dogs, percentage flow to the right lung was calculated at the following four times: before and after induction of papain emphysema and 2 and 6 weeks after left lung autotransplantation. After the induction of right lung emphysema, the right lung in four of six animals continued to receive more than 50 percent of the total pulmonary blood flow. No correlation could be established between right lung blood flow determined by carbonized microsphere distribution (true right lung blood flow) and the flow determined by anterior and posterior scintiscans (apparent right lung blood flow). This discrepancy was caused by gross distortion of the right, emphysematous lungs, which had herniated into the left hemithoraces. This herniation was demonstrated by coronal slices taken through the thoraces of two additional dogs with right lung emphysema that were given radiolabeled carbonized microspheres and 99Tc-MAA and frozen after sacrifice. These results indicate that external scintiscans for which the particulate distribution technique are used are invalid in circumstances of altered lung geometry.
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PMID:Differential lung blood flows in experimental unilateral emphysema: nonvalidity of perfusion scans. 37 52

Lung emphysema was produced in 80 rats by tracheal chronic constriction and repeated instillations of 0.1% papain solution intratracheally. 17 animals survived 90 days of the experiment; a complete examination was performed on 14 experimental and 11 control animals. 9 rats of the experimental group had pulmonary hypertension, in 5 other rats the pulmonary arterial blood pressure was not different from that in the controls. The experimental animals with hypertension had arterial hypoxemia and increased weight of the right ventricle. All experimental rats (with and without pulmonary hypertension) had increased air spaces in the lung and thickened media of distal pulmonary vessels. After breathing 100% oxygen for 20 min, the pulmonary arterial blood pressure in animals with pulmonary hypertension decreased but did not reach the control level. The decrease of the mean pulmonary arterial blood pressure after oxygen breathing correlated well with the initial level of pulmonary hypertension and with the degree of hypoxemia during air breathing.
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PMID:Pulmonary hypertension in rats with papain emphysema. 52 27

The functional residual capacity (FRC), static compliance (Cst) of the respiratory system, minute ventilation, and arterial blood gas levels were studied in the prone, the suprine, and the right and left lateral decubitus positions in dogs with papain-induced emphysema of the right lung alone and were compared with control values. The FRC and Cst of the respiratory system were significantly increased in experimental animals in all four positions, as compared with controls. This was due entirely to increases in FRC and Cst for the right lung alone; for the unexposed left lung the FRC and Cst were significantly reduced, as compared to controls. The mean arterial oxygen tension (PaO2) was decreased in all positions, except the right lateral decubitus position, in which the mean PaO2 was not different from controls. This model demonstrates that in unilaterally distributed, experimentally induced emphysema, alterations alterations in the position of the body alone may significantly alter the FRC, Cst, and gas exchange either favorably or unfavorably, depending upon the position.
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PMID:Physiologic effects of the position of the body in experimental unilateral emphysema. 66 39

In an effort to determine the mechanism of papain action in causing an emphysema-like lesion in hamsters, the number and types of cells and the activities of two lysosomal enzymes in the lung were determined after papain exposure. Three and four weeks after a 3-h exposure to an aerosol of 3% papain the following alterations in lung structure and function were observed: (1) the mean linear intercept, or average distance between adjacent alveoli, was increased; (2) the internal surface area declined; (3) the dynamic compliance was elevated at low breathing frequencies. The numbers of cells present free in the lung increased from a control value of 2.0 +/- 0.2 x 10 (6) to 6.6 +/- 0.5 x 10 (6) 5 days after exposure. The free beta-glucuronidase, alysosomal enzyme, likewise increased over threefold during the first 3 days after exposure. These results are consistent with the hypothesis that papain induces an inflammatory-type responses, and this may be in part responsible for inducing the lesion.
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PMID:Pathogenesis of papain-induced emphysema in the hamster. 68 Sep 50

Induction of experimental emphysema by protease was performed with several proteases both in vivo and in vitro to compare the ability of inducing emphysematous change and their elastolytic activity. The following results were obtained. 1) Only elastase and papain have emphysema inducing capacity. Emphysematous changes induced by elastase in vitro were dose dependent. But papain has no genuine elastolytic activity. Nature of the emphysema-inducing capacity of papain remains obscure. 2) Advantages of using the isolated lung for experiment were discussed, especially for the small dose required for enzyme-instillation. Moreover, there is no interferencey by endogeneous enzyme or protease-inhibitors. 3) Guinea pig is useful for the experiemnt of emphysema-induction both in vivo and in vitro. Minimal requirement of elastase is 50 microgram in vitro and 250 microgram for in vivo experiment.
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PMID:Protease-induced experimental emphysema: the relationship between elastolytic activity and emphysema induction. 74 21

The Syrian hamster was chosen as an animal model for experimental studies of papain aerosol-induced emphysema. The extent of the developed lesions correlated with concentration of papain and progressed with time following exposure. The same correlations of dose and time were similar to those found in man and were evaluated physiologically and histologically. The intratracheal administration of alpha1-antitrypsin prior to exposure to the single dose of papain aerosol prevented the development of lesions, whereas systemic administration of alpha1-antitrypsin did not.
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PMID:The hamster as a model for experimental pulmonary emphysema. 77 94

Pulmonary function studies after single-lung homotransplantation in dogs with experimentally induced emphysema. Pulmonary emphysema was induced in 8 bastard dogs by intratracheal instillation of papain (dose 2 mg/kg 3 to 5 times in 6 to 10 weeks). Development of emphysema was documented by weekly pulmonary function studies. The emphysematous animals underwent single-lung homotransplantation. Postoperative studies of lung function were performed immediately after transplantation and 1 week postoperatively. Bronchospirometric measurement revealed that ventilatory function and oxygen consumption of the graft was at least equal to the animal's own emphysematous lung. Up to 1 week after transplantation there is no evidence of serious ventilation-perfusion imbalance.
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PMID:[Changes of lung function in experimentally induced emphysema before and after unilateral homotransplantation of the canine lung]. 80 59


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