Biomedical subjects

M Tomoyasu

Publications and source records attributed to M Tomoyasu.

5 recordsLinked to original sources

PubMed2006

New method for evaluation of lung lymph flow rate with intact lymphatics in anaesthetized sheep.

AIM: Lung lymph has commonly been studied using a lymph fistula created by tube cannulation into the efferent duct of the caudal mediastinal node in sheep. In this method, the tail region of the caudal mediastinal node is resected and the diaphragm is cauterized to exclude systemic lymph contamination, and cannulation is performed into one of the multiple efferent ducts originating from the caudal mediastinal node. Moreover, the pumping activity of lymphatics might be diminished by cannulation. Therefore, the purpose of the study was to evaluate the flow rate of lung lymph with maintenance of intact lymphatic networks around the caudal mediastinal node to the thoracic duct in sheep. METHODS: An ultrasound transit-time flow meter was used to measure lung lymph flow. The thoracic duct was clamped just above the diaphragm and the flow probe was attached to the thoracic duct just after the last junction with an efferent duct from the caudal mediastinal node. The lung lymph flow rate was measured at baseline and under conditions of lung-oedema formation. RESULTS: The baseline lung lymph flow rate in our model was three- to sixfold greater than values obtained with the cannulation method. With oedema-formation, the lung lymph flow rate was the same as that measured using cannulation. CONCLUSION: The lung lymph flow was unexpectedly large under the conditions of the study, and our data suggest that the drainage effect of lymphatics is significant as a safety factor against pulmonary oedema formation.

Animals↗

PubMed2004

[Preoperative evaluation for lung resection using right ventricular hemodynamic functions by unilateral pulmonary arterial occlusion test].

We performed a unilateral pulmonary arterial occlusion (UPAO) test for the preoperative evaluation of right ventricular functions as a loading test in patients undergoing a lung resection without cardiac complications preoperatively. We investigated the relationship between changes in right ventricular hemodynamic functions and postoperative cardiac complications, namely right heart failure or arrhythmia. To evaluate the right ventricular hemodynamic function test, we measured the mean pulmonary arterial pressure, cardiac index, right ventricular ejection fraction end-diastolic volume, and stroke volume before and during the UPAO test using the thermodilution method, and calculated the total pulmonary vascular resistance and right ventricular stroke work indexes. The incidence of postoperative cardiac complications was not related to the changes in the total pulmonary vascular resistance index. However, the postoperative cardiac complications were common in patients whose right ventricular end-diastolic volume index was increased by more than 20% during the UPAO test. These results suggest that the changes in the right ventricular end-diastolic volume index during the UPAO test can predict postoperative cardiac complications in patients undergoing a pulmonary resection.

Arrhythmias, Cardiac↗

PubMed2002

Effect of phosphodiesterase III inhibitor (Olprinone) on thoracic duct lymph flow in anesthetized sheep with experimentally induced heart failure by endothelin-1.

We investigated the short-term effects of a phosphodiesterase III inhibitor (Olprinone) on hemodynamics and thoracic duct lymph flow in anesthetized open-chest sheep with heart failure induced by endothelin-1 (cardiogenic shock). Ultrasound transit-time flow probes were attached to the thoracic duct, the ascending aorta and the renal artery. Arterial, pulmonary and central venous pressures were monitored. Endothelin-1 was infused intravenously at a dosage that reduced cardiac output to 50% or more of baseline (n=11). The effects of Olprinone were examined (n=5) by intravenous infusion after endothelin-1 administration. Other sheep (n=6) were used as controls. Olprinone significantly increased cardiac output that had been decreased by endothelin-1 and further increased thoracic duct flow that had been increased by endothelin-1. Increased arterial and pulmonary pressures induced by endothelin-1 administration were rapidly decreased by Olprinone. Renal arterial flow and central venous pressure were, however, unchanged by Olprinone. Overall, Olprinone acutely improved experimental cardiogenic shock (heart failure) induced by endothelin-1, and maintained thoracic duct lymph flow at a high level after endothelin-1 administration.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed2000

A new model of lung metastasis for intravital studies.

We created anexperimental model of pulmonary metastasis based on subcutaneously implanted Lewis lung cancer in mice and observed in vivo the microcirculation of spontaneously metastasized tumors in the lung. The mice lung was held by a small handmade suction ring to stop cardiac and respiratory movement. Using fluorescent microscopy, tumor microcirculation and normal lung microcirculation in the same lung lobe were compared by measuring microvessel diameter and blood flow velocity [red blood cell (rbc) velocity]. In normal microcirculation, the mean values of microvessel diameter and rbc velocity were 10.4 +/- 2.7 microm and 188 +/- 63 microm/s, respectively. In tumor microcirculation, the mean values of the same were 10.6 +/- 3.3 microm and 105 +/- 40 microm/s. The rbc velocity in normal microcirculation was significantly higher (P < 0.001) than that in tumor microcirculation. The calculated shear rates of normal microcirculation and tumor microcirculation were 73.4 +/- 23.4 (/s) and 41.2 +/- 16.1 (/s), respectively. The shear rate of the tumor microcirculation was significantly slower (P < 0.001) than that of the normal microcirculation. We demonstrated a feasibility of observation and measurement of tumor microcirculation in the lung and confirmed that the physiologic data were compatible to those in the brain or in the liver reported by others. This model might be useful for studying metastatic tumor pathophysiology in the lung microcirculation.

Animals↗

PubMed1999

[Clinical comparison of diffuse malignant mesothelioma of the pleura and pseudomesotheliomatous carcinoma of the lung for each case].

Because we experienced each 1 operative case of diffuse malignant mesothelioma of the pleura and pseudomesotheliomatous carcinoma of the lung discovered with pleural effusion, clinical comparison investigated both. The first case was suspected diffuse malignant mesothelioma of the pleura before operation, and we performed pleuropneumonectomy. But the pathologic diagnosis was adenocarcinoma of the lung, what is so called pseudomesotheliomatous carcinoma. The second case had inhaled asbestos and his pleural effusion revealed high concentrations of hyaluronic acid. Thoracoscopic biopsy showed malignant mesothelioma, and we performed pleuropneumonectomy. The pathologic final diagnosis was diffuse malignant mesothelioma of the pleura. In clinical differential diagnosis of diffuse malignant mesothelioma of the pleura and pseudomesotheliomatous carcinoma of the lung, history of inhalation of asbestos and concentrations of hyaluronic acid in pleural effusion are helpful. And thoracoscopic biopsy is necessary in established diagnosis.

Adult↗