Category: Effects of Injury

Acute and Subacute Effects of Injury on the Canine Alveolar Septum: Results (9)

Assuming that repair processes have not kept pace with injury, the development of through-and-through septal gaps (ie, pores and fenestrae) might produce more rapid airspace enlargement if they occurred at septal junctions rather than in the alveolar wall between junctions. Retraction of the edges of a gap at the junction of three alveolar walls might lead to coalescence of three adjacent airspaces, rather than just…

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Acute and Subacute Effects of Injury on the Canine Alveolar Septum: Results (8)

Figure_5

Because of the striking similarity between papain-induced emphysema and human panlobular emphysema both morphologically and physiologically and the further similarity between normal canine and human lungs in the disposition of interstitial septal gaps, alveolar macrophages and type 2 cells which we have demonstrated, it would seem prudent to study this convenient model further. The complexities of the pathogenesis of emphysema need to be probed more…

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Acute and Subacute Effects of Injury on the Canine Alveolar Septum: Results (7)

It appears that the mere presence of neutrophils in the lung does not produce emphysema. On the other hand, MacNee et al, recently reported that cigarette smoking was accompanied by retention of radioactively labelled neutrophils from the lungs of smokers who smoked during their study. Based on experimental studies showing margination of neutrophils preferentially in the alveolar vessels of rabbit lungs and on regional differences…

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Acute and Subacute Effects of Injury on the Canine Alveolar Septum: Results (6)

Acute and Subacute Effects of Injury on the Canine Alveolar Septum: Results (6)

This notion gains credibility from the work of Sage et al confirmed by Lwebuga-Mukasa et al, which showed that type 2 cells in culture produce all of the major protein constituents of the alveolar basement membrane, which is a component of the alveolar septal interstitial matrix. More recently, Crouch et al demonstrated the synthesis of three collagenous macromolecules by cultured type 2 cells. These studies…

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Acute and Subacute Effects of Injury on the Canine Alveolar Septum: Results (5)

Clustering of type 2 cells in alveolar “corners” or septal junctions in mouse lungs has been described previously by Adamson and Bowden. Brains report on lungs fixed by intravascular perfusion shows alveolar macrophages also clustered at the alveolar septal junction. We have shown in previous studies that in normal human lungs preserved by vascular perfusion-fixation, type 2 cells, alveolar macrophages and septal interstitial gaps all…

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Acute and Subacute Effects of Injury on the Canine Alveolar Septum: Results (4)

Figure_4

On the other hand, the prevalence of gaps in the septal interstitium of the two-week specimen was strikingly increased over that of controls (Fig 4; Table 4). Most of these gaps were occupied by type to severe emphysema which were produced by papain. Gil and Weibel and Brain et al have shown the necessity of the vascular perfusion method of lung fixation, in order to…

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Acute and Subacute Effects of Injury on the Canine Alveolar Septum: Results (3)

Figure_2

Transmission Electron Microscopy In all six specimens examined by transmission electron microscopy (control as well as treated), gaps in the interstitium of the alveolar septum of lung alveoli were located predominantly at sites of junctions of alveolar septa and were occupied by type 2 cells (Fig 2 and 3; Table 2). This was especially prominent in the two- and four-week animals. In three of six…

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Acute and Subacute Effects of Injury on the Canine Alveolar Septum: Results (1)

Figure_1

Light Microscopy There was an influx of polymorphonuclear leukocytes into the lungs of the 4-h saline and 4-h papain dogs, into all three compartments of the alveolus: the airways, the capillaries and the interstitium. This was more pronounced in the normal saline dog, but prominent also in the 4-h papain dog where it was accompanied by hemorrhage, whereas in all other specimens (control, two-week, and…

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Acute and Subacute Effects of Injury on the Canine Alveolar Septum: Methods (5)

Acute and Subacute Effects of Injury on the Canine Alveolar Septum: Methods (5)

Septal continuity, however, was maintained by the alveolar epithelium, usually by a type 2 cell. Less commonly, continuity was maintained by the nucleated portion of a type 1 cell, and least commonly, by a thin single or double layer of type 1 cell cytoplasm. All septal discontinuities, all alveolar macrophages and all epithelial cell types were identified as to location on each alveolar profile, and…

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