Experimental pulmonary emphysema was produced in a mongrel dog by inhalation of aerosolized papain. Histometrical studies demonstrated the development of pulmonary emphysema in dogs similar to panacinar emphysema in humans after inhalation of papain. The alveolar surface area/unit lung volume (S/V) was then determined by the of point counting. method The S/V in emphysematous lungs (n=12) was 75.64±11.52 and that in control lungs 127.64±22.94 (n=13) p<0.001. The distribution of S/V was of a normal pattern both in the emphysematous and control lungs. In spite of the difference in S/V value between the emphysematous and control lungs, the range of standard deviation was almost the same in both groups. The above results suggests that the degree of destruction of alveoli was almost uniform and that the destroyed alveoli were almost evenly destributed within the lobe examined. Neither inflammatory nor fibrotic changes were found in bronchi and bronchioles.

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In order to clarify the pathophysiology of pulmonary emphysema, the relationship between pulmonary compliance and S/V (alveolar surface area/unit lung volume), a criterion of the degree of destruction of alveoli, was investigated in the papain-induced emphysematous lung. The pressure-volume relationship could be approximated by an equation V=V₀ (l-e^-kp) in the present experiment, where V₀ is lung volume at infinite transpulmonary pressure and k is a constant which represents the characteristic of individual lung elasticity.
In the emphysematous lung and control lung k was 0.259±0.050cmH₂O^-1 and 0.176±0.064cmH₂O^-1 respectively. Since the former was significantly larger than the latter, k could be interpreted as an index of static pulmonary compliance. The S/V ratio in the emphysematous lung (73.56±11.10mm²/mm³, n=10) was found to be smaller than that in the control lung (125.64±19.14mm²/mm³, n=11, p<0.001).
Thus the destruction of alveoli in the emphysematous lung was confirmed. The coefficient of correlationship between k and S/V (γ=-0.786) indicated that an increase in pulmonary compliance due to a decrease in elasticitywas parallel to the degree of destruction of alveoli in the emphysematous lung.

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This study was undertaken to elucidate the role of respiratory tract fluid in the mucociliary transport system, a major defence mechanism of the lung.
The mucus-depleted frog palate and several kinds of mucus, including human sputum, were used for the experimental model and viscoelastic measurements of mucus were made.
The results were as follows.
1) In the frog palate, mucus could be easily separated from cilia by washing, and the mucus-depleted frog palate was proved to be a convenient and appropriate model for this study.
2) Only by adding appropriate mucus were small particles (diameter 15μm) effectively transported uphill against gravity and across unciliated areas, and fairly large particles (diameter 500μm) could also be transported. It is obvious from these data that the ciliary transport requires not only ciliary beating but also the presence of appropriate mucus.
3) Human mucoid sputum was proved to be one of the most appropriate types of mucus for effective ciliary transport.
4) The alternation of sputum properties, led to impairment of the promotion of ciliary transport.
5) From the comparative study of viscoelasticity of human sputum and other mucus or solutions, it was speculated that some rheological properties other than viscoelasticity are also important for the ciliary transport.
These results suggest that the presence of respiratory tract fluid is essential for the ciliary transport, and urge us to reconsider the current therapy by expectorants which is, to a great extent, oriented toward decreasing viscosity of sputum.

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The hypotensive action of arachidonic acid (AA), a precursor of prostaglandin E₂ and F_2α, has been considered as an evidence of prostaglandin (PG) biosynthesis in vivoa. Recently, however, en route to the biosynthesis of PG, new compounds, endoperoxide intermediates, have been isolated in sheep vesicular gland that are extremely short-lived and further transformed enzymatically to amuch more potent oxane derivative, thromboxane A₂ which has a half-life of 30sec. in the human platelets. Although both of these compounds are, in some cases, hundreds of times more potent than PGs on platelet, smooth muscle strips and fat cells, their biosynthesis and physiological significance in the lung in vivo have not been fully elucidated.
The purpose of the present work is, therefore, to clarify the possible physiological roles of PG endoperoxides and thromboxane A₂ in the lung by investigating the effect of AA on airway and pulmonary vasculature in guinea pigs in vivo and in isolated perfused lungs.
The following results were obtained:
1) Intravenous administration of AA caused a dose-related decrease in systemic blood pressure and increases in right ventricular and airway pressures in vivo.
2) These effects were specifically inhibited by indomethacin, a potent inhibitor of PG biosynthesis, but not influenced by either vagotomy, anti-serotonin, anti-histamine drugs nor α-adrenergic blockade. Other unsaturated fatty acids, oleic, linoleic and linolenic acids, did not cause any changes in circulation and airways of guinea pigs.
3) AA caused marked increases in pulmonary arterial and airway pressures also in isolated lungs perfused with Krebs-bicarbonate solution, and the action of AA was inhibited by indomethacin (ID₅₀=0.25μg/ml).
4) The amounts of PGE₂ and PGF_2α released from the lungs following the injection of AA (300μg) were estimated by bioassay with rat stomach strip after solvent partition and thin-layer chromatography. Both PGE₂ and PGF_2α were obtained only in low yields (PGE₂: 45±7ng, PGF_2α: 153±30ng).
5) Pulmonary vasoconstriction and bronchoconstriction induced by AA were not altered by the treatment of diphloretin phosphate, a specific antagonist of PGs.
6) A vasoactive substance which contracts rabbit aorta, rabbit celiac artery and rabbit mesenteric artery was released into the effluent from the lungs by AA. The half-life of this substance was about 30sec. at 37°C.
7) The pulmonary vasoconstricting and bronchoconstricting substance appeared in the effluent from the lungs by AA was also unstable, with a half life of 30sec. at 37°C.
Based on these results, it is possible that the pulmonary pressor and bronchoconstrictive action of AA is mainly due to the thromboxane A₂ converted from AA in the lung. It is suggested, therefore, that pathophysiological stimuli that are known to release PGs may release thromboxane A₂ which could be attributed to pulmonary and systemic disorders by its much more potent activity than primary PGs.

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The patient was a 67 year old male, with an abnormal shadow suggesting a mass lesion on the plain chest X-ray picture taken when he had his hoarseness checked. The lesion appeared to protrude from the mediastinum into the right pleural cavity. On X-ray in the supine position, however, the lesion appeared shifted laterally and the lower portion was observed to have a stalk-like structure which was attached to the diaphragm. The case was operated upon and it was disclosed that the mass was not of the mediastinum nor of the lung. It was freely anchored in the pleural cavity with upper polar and lower polar stalks attached to the side of mediastinum. What was more, the lower polar stalk was larger than the upper polar stalk. Both stalks had grossly visible nutritive blood vessels. The tumor was easily removed by severance of the stalks. Histologically the most likely diagnosis was benign pleural mesothelioma. Benign mesotheliomas are well defined and often have a stalk. The present case with two stalks is rare among them.

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A 65 year-old female bird fancier had complained of dry cough since one month previously without fever, dyspnea and shortness of breath. On auscultation, crepitant rales were audible and chest x-ray film revealed ground-glass and small nodular shadows in both lung fields. These regressed gradually without any treatment. Lung biopsy showed scattered granulomas with a few giant cells. Skin test was positive only to budgerigar's droppings after 20 minutes and 6 hours. Biopsy findings of the skin were not inconsistent with Arthus reaction. Precipitation with budgerigar's serum and droppings were negative.

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