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Biomedical subjects

T Takaro

Publications and source records attributed to T Takaro.

At least 37 records · Page 2Linked to original sources
PubMed1981

Alterations in stress distributions around interalveolar pores after exposure to papain in dogs.

Electron microscopic examination of dog lungs after exposure to papain for as little as 30 min showed removal of surfactant material from the pores of Kohn, and significant enlargement of the pores. We analyzed these early events in terms of structural mechanics, and concluded that: (1) The approximate doubling of the average diameter indicates a lowering of the effective modulus of elasticity in the vicinity of the pores to less than 50% of its original value, which is consistent with the destruction of elastin. (2) The removal of the surfactant material, which normally occludes the pores, results in the loss of the force caused by surface tension, which normally acts at the rim of the pore, and alleviates maximal tissue stress. This lost force can result in a stress increase on the elastin by as much as 20 to 30% of its strength. (3) The whole lung volume pressure deflation curves obtained in hamsters after exposure to papain show a significant increase in compliance associated with papain treatment. Degradation in the elastic modulus of the tissue, caused by the papain, contributes to such an increase. On the other hand, surface tension measurements from canine lung extracts after exposure to papain yield results that should contribute to a decrease in compliance. Because papain treatment destroys the continuity of the lining layer, this contribution is minimized, and the effect on the tissue dominates, resulting in a net increase in compliance.

Animals↗
PubMed1980

Long-term results of internal mammary artery implantation for coronary artery disease: a controlled trial by the participants of the Veterans Administration Coronary Bypass Surgery Cooperative Study Group.

One hundred forty-six adult men from sixteen Veterans Administration hospitals were entered in a controlled prospective clinical trial. Seventy-one patients were randomly allocated to receive implantation of the internal mammary artery into the left ventricular myocardium for chronic ischemic heart disease with angina pectoris, and 75 were assigned to the control group. The two treatment groups were similar at baseline with respect to sixteen clinical and angiographic factors thought to have prognostic importance. Most of the patients were operated on before 1970. Operative mortality was 12%, and implant patency in 52% of eligible patients studied 1 year after operation was 67%. At the end of follow-up extending up to 12 years (mean, 9.3 years), cumulative survival for both groups was similar. Over half of the patients (58%) had died at the end of 10 years (5% per year). While the hypothesis on which the operation was based appears to be valid, the degree of revascularization achievable in most patients did not affect longevity.

Adult↗
PubMed1980

Early ultrastructural changes in papain-induced experimental emphysema.

These studies show that very soon after exposure of canine lungs to crude papain mixed with a marker (India ink), the alveolar surface-active lining was both morphologically and functionally altered, and alveolar macrophages were destroyed in significant numbers. These changes occurred before other identifiable major alterations. The morphologic changes were characterized by replacement of the normal alveolar surface lining by an amorphous material adhering to the alveolar surfaces and penetrating the pores of Kohn, which were significantly enlarged. Type II epithelial cells and alveolar macrophages were increased in number, with a significant proportion of the latter observed to be disintegrating. Polymorphonuclear leukocytes were also noted in increased numbers, but this was also observed in control lungs (instilled only with saline plus India ink). Functionally the alveolar surface lining as studied in lung extracts showed an abnormal stability index after either in vivo or in vitro exposure to crude papain. These findings suggest that the early effects of this exogenous protease on the lung are interrelated, alveolar surface lining injury appearing to set the stage for accelerated macrophage lysis, with the probable release of phagocytosed exogenous protease as well as intracellular endogenous proteases. These events may represent early steps in the pathogenesis of experimental papain-induced pulmonary emphysema.

Animals↗
PubMed1979

Iatrogenic coronary artery stenosis following aortic valve replacement.

Until recnetly, coronary arterial perfusion was one of the best methods to protect myocardium during aortic valve replacement. However, the insertion of perfusion cannulas may produce immediate traumatic lesions and late stenosis of the coronary arteries, with grave consequences. Two patients with normal coronary arteries prior to operation developed obstruction of the maximal left main coronary artery following aortic replacement. One of these patients represents the first case of iatrogenic coronary arterial stenosis in which the aortic valve was replaced with a porcine bioprosthesis. Accelerating angina pectoris and ventricular arrhythmias were the presenting clinical manifestations. Aorta-coronary bypass grafting to the left anterior descending and circumflex coronary arteries was successfully performed in one patient, while the other patient died before investigative procedures could be undertaken. Any patient whose aortic valve has been replaced and who develops angina pectoris a few months after operation should be suspected of having developed stenosis of the proximal coronary artery. Coronary angiography should be perfomed promptly. Once the lesion is recognized, the operaiton should be performed posthaste because these lesions are life threatening owing to their proximal location and rapid evolution.

Aortic Valve↗
PubMed1978

Esophagopleural fistula following pulmonary resection.

The development of esophagopleural fistula following pulmonary resection is an uncommon but serious complication. The fistula may appear either soon after operation, due to direct trauma to the esophagus or to its blood supply during extensive dissection, or later, in association with the development of a bronchopleural fistula and empyema following the pulmonary resection. Treatment of these fistulas is usually complicated, and the recovery period is prolonged. Control of infection, hyperalimentation, obliteration of the empyema space, and closure of the fistula with a muscle or pleural flap are recommended methods of management. The pathogenesis, treatment, results, and prevention of this complication are discussed.

Adult↗
PubMed1978

Insidious strut fractures in a DeBakey-Surgitool aortic valve prosthesis.

Recent reports of cage wear occurring in DeBakey-Surgitool aortic valve prostheses prompted us to examine with image intensification all our patients who have had this type of prosthesis implanted. One patient, who was asymptomatic, was discovered to have a prosthesis with two fractured struts. This patient's prosthetic valve was replaced successfully with a stented porcine heterograft prosthesis. Including the valve removed from this patient, 8 DeBakey-Surgitool aortic valves with structural defects have been reported to the manufacturer. In the absence of a catastrophic event, patients with valves having fractured or worn struts may be totally asymptomatic, and routine periodic roentgenographic examination may be the only way of detecting strut wear or fracture.

Adolescent↗
PubMed1978

Physiologic effects of the position of the body in experimental unilateral emphysema.

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.

Animals↗
PubMed1978

Survival of men treated for chronic stable angina pectoris. A cooperative randomized study.

During 1972 to 1974, 686 men aged 27 to 67 years, admitted to thirteen Veterans Administration Hospitals with stable angina, resting or exercise electrocardiographic abnormalities, "graftable" arteries, and abnormal left ventricular function (80 percent) were randomly assigned to surgery (332) or medical (354) treatment. There was no significant difference in clinical, angiographic, and ventriculographic characteristics. The over-all operative mortality rate (30 days) was 5.8 percent, 5 percent in the 95 percent who had saphenous vein aorta-coronary bypass alone. Eighty-nine percent of the 79 percent recatheterized at 1 year had at least one patent graft. Longevity for patients with one, two, and three vessel disease who were treated surgically was comparable to that previously described, but did not differ from that of the medically treated groups. Survival in the over-all surgical group was 86 percent at 4 years as compared to 83 percent in the medical group, which in these "operative candidates" is better than usually cited. This difference was eliminated when the 90 patients (13 percent) with left main disease, whose longevity was significantly improved (p = 0.005) by the operation, were excluded. Despite this exclusion, a slight trend in favor of surgery was still discernible in the largest subgroup, those having triple vessel disease with an abnormal left ventricle.

Adult↗
PubMed1978

Ultrastructural studies of canine interalveolar pores (of Kohn).

Normal canine lungs were prepared for ultrastructural studies using two different routes for fixation: the airways route and the vascular route. Using the airways route, under conditions of controlled pressure, scanning and transmission electron microscopic studies of alveolar surfaces allowed identification of an average of 19 alveolar pores per exposed alveolar surface, each pore averaging approximately 3 micron. in diameter. The alveolar surface was honeycombed in appearance, with the walls of multiple capillaries bulging into the alveolar space. Using the other route, vascular perfusion of the lungs with the fixative and controlling pressures in both the vascular and airway compartments, scanning electron microscopic studies showed that most exposed alveoli exhibited a smooth or slightly wrinkled surface, essentially devoid of pores and averaging only three pores per alveolus. By transmission electron microscopy, alveolar surfaces were found to be covered with an extracellular material suggestive of lung surfactant; alveolar pores, averaging approximately 1 micron. in diameter, were filled with the same material. It is concluded that most alveolar pores of normal dogs are bridged by and filled with lung surfactant. These findings can be demonstrated most reliably by using vascular perfusion of the lungs for introducing the fixative.

Animals↗