Biomedical subjects

G Nasu

Publications and source records attributed to G Nasu.

9 recordsLinked to original sources

PubMed1993

[Estimation of filtration variables in isolated rat lungs for evaluation of pulmonary microvascular permeability].

In order to evaluate the microvascular permeability of donor lungs, we calculated the filtration variables; K (reflection coefficient), simultaneously. For the calculation of filtration variables, the isolated rat lungs were kept in zone three conditions (pulmonary arterial pressure > pulmonary venous pressure > alveolar pressure). We used Krebs-Henseleit solution (K-H) with 6% bovine serum albumin for the perfusate, and maintained perfusion using a constant pressure circuit system. The pulmonary venous and alveolar pressures were maintained at 2.5 and 2.0 cmH2O, respectively, and pulmonary arterial pressure was set so that change in lung weight occurred. We increased both pulmonary arterial and venous pressures by 3 cmH2O simultaneously, and obtained the initial filtration rate. Then we diluted the perfusate with K-H to about half concentration, and obtained the initial filtration rate. We obtained values of filtration variables of K=4.55 mg.min-1.cm H2O-1.g-1], Ppmv=0.59 cmH2O, and sigma =0.617. These values agree with values from previous reports. Since these three filtration variables are interrelated, this method for simultaneous measurement is more accurate than independent measurements. The chief advantages of this method are that it does not require direct measurement of interstitial pressure or collection of lymph fluid, and all variables are obtained simultaneously. Using this method, the vascular permeability of isolated rat lungs, can be estimated.

Animals↗

PubMed1992

[Radioaerosol inhalation and perfusion imaging studies in immediate postoperative phase after lobectomy].

In order to determine the changes in pulmonary ventilation-perfusion imaging after lobectomies, we examined 11 patients using radioaerosol inhalation and perfusion scintigraphies, before and after the operations. We employed 99mTc-labeled albumin aerosol generated by a jet nebulizer for the inhalation imaging, and 99mTc-labeled macroaggregated albumin for the perfusion imaging, respectively. Prior to the operations, there were no (major) defects of imagings on the lung fields. Immediately after the operations, however, we could not detect any abnormal findings on chest roentgenograms, we found detects of imagings on the lung fields in either inhalation or perfusion scintigraphy whose area were mismatching. It took more than 3 weeks for these defects of imagings to disappear. In conclusion, these findings suggest that postoperative hypoxemia might be occurred by these mismatchings.

Administration, Inhalation↗

PubMed1991

[Evaluation of cardio-pulmonary function for lobectomy under the condition of selective pulmonary arterial occlusion test (SPAO)].

We performed selective pulmonary arterial occlusion test (SPAO) and unilateral pulmonary arterial occlusion test (UPAO) in 30 patients with lung cancer who would be undertaken right lower lobectomy or middle and lower lobectomy, and evaluated the preoperative cardio-pulmonary function. The lung hemodynamics during SPAO were different from those during UPAO. This indicates that SPAO evaluated reserve capacity of vascular bed in the right upper lobe which would be remained at the surgery. Moreover, the ratio of total pulmonary vascular resistance during SPAO to that of before SPAO was not differed in two groups, one was a group with and the other was a group without impaired reserve capacity of vascular bed in the contralateral lung. This suggests that reserve capacity of pulmonary vascular bed including right upper lobe would be well compensated even in the patients with highly impaired capacity in the contralateral lung. Based on these findings, we performed lung resections in 9 patients, who were judged contraindications for lung resection by the results of UPAO, and no patient suffered postoperative cardio-pulmonary complications. Total pulmonary vascular resistance immediately after the right middle and lower lobectomy were equal to those during SPAO. Thus we conclude that SPAO is very useful technique for evaluating cardiopulmonary function after right lower lobectomy or middle and lower lobectomy, and that it would be possible to extend the boundaries of safety for lung resection based on evaluation of cardio-pulmonary function by SPAO.

Aged↗

PubMed1991

[Lung function after lobectomy in chronic pulmonary emphysema].

We compared the prediction of postoperative pulmonary function in two groups: chronic pulmonary emphysema (CPE) group (n = 30) and normal control group (n = 41). These patients had a lobectomy because of lung cancer. We measured pulmonary function test (FVC, EFV1, TLC, FRC, RV, DLco), and pulmonary perfusion scan before and after surgery. We found correlation between the predicted and measured postoperative values very close in control group. Whereas, in CPE group, these correlations were very low especially in FVC and FEV1. We also calculated the pulmonary function on the operated and the non-operated sides. The correlation were very high without FEV1 in control group and all the measured values did not correlate to the predicted values. On the non-operated side, the correlations were high in both control and CPE groups. From these results we can conclude that it is difficult to predict the postoperative pulmonary function in the case of chronic pulmonary emphysema.

Chronic Disease↗

PubMed1990

[Activated pulmonary intravascular macrophages increase pulmonary microvascular permeability in sheep].

Pulmonary intravascular macrophages (PIMs) reside in the alveolar capillaries of sheep lung. However, the role of PIMs activation in the mechanism of increasing pulmonary microvascular permeability is not clear. We determined, using awake sheep with chronic lung lymph fistulas, the effects of intraarterial infusion of latex beads emulsion (1 microns in diameter) on lung lymph-dynamics. Sheep were divided into 3 groups; control, low dose latex and high dose latex groups. In control group, their lymph-dynamics were stable during the experimental period. In low dose latex group (5.46 x 10(9) beads/kg), lung lymph flow increased during the infusion period, but lung lymph protein clearance did not change. In high dose latex group (5.46 x 10(10) beads/kg), lung lymph flow began to increase during the infusion period and remained high, and lung lymph protein clearance increased significantly during and after the infusion of latex beads emulsion. The latex beads mainly distributed to lungs, and 70% of the beads were caught by PIMs in their phagosomes. These findings suggest that the activation of PIMs through their phagocytic uptake of circulating microparticles increases pulmonary microvascular permeability.

Animals↗

PubMed1989

[Possible involvement of vascular endothelium-derived relaxing factor induced by platelet-activating factor (PAF) on human pulmonary artery after contraction in vitro].

We studied the effects of platelet-activating factor (PAF) on human pulmonary vascular smooth muscle in vitro. 10(-6) M PAF elicited slight contractions in 2 of 7 endothelium-denuded arterial strips, but did not elicit distinct contractions or relaxations in the other strips. After incubation with PAF at 10(-7) M, the contractions of pulmonary vascular smooth muscle induced by histamine and prostaglandin F2 alpha were significantly decreased. Preincubation of 10(-3) M indomethacin did not affect the inhibitory effects of PAF, but these disappeared with removal of endothelium. These results suggest that the inhibitory effects of PAF on human pulmonary vascular smooth muscle contractions may appear not through the cyclooxygenase products but the endothelium-derived relaxing factor.

Female↗

PubMed1989

[Pulmonary hemodynamics during mild exercise in COPD].

The effects of mild exercise on pulmonary hemodynamics and ventilatory responses in COPD were studied. Six patients with FEV1% less than 70% received 20 watt exercise tests by cycle ergometers for 5 minutes. Changes in hemodynamics and ventilation were observed before and during exercise. Nine patients with an FEV1% of more than 70% also received exercise tests as controls. There were no different in changes in respiratory frequency, tidal volume and minute ventilation between control and COPD group. However, the mean pulmonary arterial pressure were higher in the COPD group than in the control group before exercise. Moreover increments of mean pulmonary arterial pressure by exercise were also greater in COPD group. It was concluded that hemodynamics in COPD are much more influenced by mild exercise than in healthy subjects.

Adult↗

PubMed1989

[Pulmonary fibrosis after endotoxin-induced permeability edema].

To know the pathogenesis of the lung fibrosis after ARDS, we investigated the role of PMN-elastase after endotoxin-induced pulmonary edema in awake sheep with chronic lung lymph fistulas. The permeability of the pulmonary circulation increased 2 hours after endotoxin injection. Four hours after endotoxin injection, WBC migrated to the lung interstitium and the number of WBC in BALF increased. Endotoxin increased PMN-elastase in plasma and lymph whereas the level of alpha-1-protease inhibitor (alpha-1-PI) did not change. The activity of alpha-1-PI measured by trypsin inhibitory capacity was zero in the exudative phase. The level of PMN-elastase in lymph was significantly higher 1 week after endotoxin injection than baseline levels. Histologically, pulmonary fibrosis developed 1 week after endotoxin injection. These results suggest that inflammatory mediators released from PMN play an important part in progress to the fibrotic phase after ARDS.

Animals↗

PubMed1989

[A case of reexpansion pulmonary edema during thoracotomy].

A case of reexpansion pulmonary edema during thoracotomy is presented. A high edema fluid-plasma protein concentration ratio suggested an increase in pulmonary vascular permeability. A marked increase in the percentages of polymorphonuclear leukocytes (PMN) and high concentration of PMN-elastase in edema fluid suggested activated PMN-mediated vascular endothelial injury, which caused an increase in permeability. Edema fluid and plasma contained high concentrations of Thromboxane B2 and 6-keto-PGF1 alpha at the stage of increased permeability. This suggested these chemical mediators participated in the mechanisms of increased permeability in reexpansion pulmonary edema.

Adult↗