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Biomedical subjects

H Toga

Publications and source records attributed to H Toga.

At least 37 records · Page 2Linked to original sources
PubMed1994

Effect of pulmonary blood flow on microvascular pressure profile determined by micropuncture in perfused cat lungs.

To clarify the role of the pulmonary microvasculature in adjusting to increased pulmonary blood flow, we measured arteriolar and venular pressure by the servo-null micropuncture method while changing the pulmonary blood flow in isolated perfused cat lungs. We divided the lung vasculature into three longitudinal segments: 1) arterial (pulmonary artery to 30- to 50-microns arteriole), 2) microvascular (between 30- to 50-microns arteriole and venule), and 3) venous (30- to 50-microns venule to left atrium). The vascular resistance was calculated by dividing the pressure gradient by the flow. The pressure gradient of the microvascular segment did not increase, whereas the pressure gradient of the arterial and venous segments increased simultaneously with flow rate. Total and microvascular resistance decreased with increase of flow rate. Resistances of the arterial and venous segments did not change with increase in flow. We conclude that the microvasculature plays a crucial role in preventing pulmonary hypertension with increases in flow by decreasing microvascular resistance.

Animals↗
PubMed1994

[A case of diffuse alveolar hemorrhage accompanied by mesangial proliferative glomerulonephritis with positive perinuclear anti-neutrophil cytoplasmic antibody].

A 62-year-old man was admitted to our hospital because of low-grade fever and hemoptysis. Chest roentgenogram revealed diffuse infiltrative shadows with air bronchograms. Bronchoalveolar lavage fluid demonstrated bloody fluid, including many hemosiderin-laden macrophages. In addition, his laboratory data on admission revealed elevation of serum creatinine and BUN, and proteinuria and hematuria on urinalysis. Renal needle biopsy showed atrophic glomeruli and mesangial proliferative glomerulonephritis without crescent formation. A history of wheezing and slight eosinophila was also present, and we therefore suspected allergic granulomatous angitis. We performed airway sensitivity and reversibility tests, which were positive, and so we judged that he had an asthmatic component. Perinuclear antineutrophil cytoplasmic antibody (P-ANCA) was positive (x 1000) with ELISA. We diagnosed diffuse alveolar hemorrhage with mesangial proliferative glomerulonephritis and bronchial asthma. His general condition improved with oral administration of corticosteroid (50 mg/day) and immunosuppressive agent (cyclophosphamide; 50 mg/day), and his major symptoms disappeared within a few days.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed1994

[Bronchial arterial hemodynamics after thoracic irradiation therapy in lung cancer patients].

We evaluated bronchial arterial hemodynamics after thoracic irradiation therapy. We performed bronchial arteriography in 9 patients (8 males and 1 female) with lung cancer who received thoracic irradiation (58-72 Gy). Three patients had adenocarcinoma, 3 squamous cell carcinoma, 2 small cell carcinoma and 1 large cell carcinoma. Their clinical stages were 6 in stage IIIB and 3 in stage IV. Eight of these cases also received chemotherapy by intra-bronchial arterial infusion of anti-cancer agents (Carboplatin and/or Cisplatin). The bronchial arterial supply was patent except in the one complete remission case (small cell carcinoma of stage IIIB). In the five cases developing radiation pneumonitis, bronchial arteries demonstrated angiogenesis in the radiation fields, despite which pulmonary arteriography and/or pulmonary perfusion scintigrams showed a decreased pulmonary arterial supply. Bronchial arterial hemodynamics demonstrated no significant damage in the bronchial arteries by the thoracic irradiation therapy and/or bronchial arterial infusion of anti-cancer agents. It is suggested that patent bronchial arteries after radiation therapy promote local recurrences of lung cancer. In 5 cases, including 2 local relapsed cases and 3 cases showing no remarkable response to radical radiation therapy, we performed bronchial arterial infusion of anti-cancer agents after radiation therapy, with good responses obtained. We conclude that thoracic irradiation did not damage bronchial arteries as compared with pulmonary arteries, and that in local relapsed and radio-resistant cases bronchial arterial infusion of anti-cancer agents after radiation therapy is a useful approach.

Adult↗
PubMed1993

Tone dependent nitric oxide production in ovine vessels in vitro.

We have determined the role of endogenous nitric oxide (NO) in regulation of vasomotor tone in ovine intrapulmonary and mesenteric vessels with resting tension and elevated vasomotor tone. Third generation intrapulmonary vessel rings and mesenteric vessel rings, 2-3 mm in diameter, were isolated from 20 sheep. NO production in the vessels was assessed by the change in tension induced by NG-nitro-L-arginine methyl ester (L-NAME), a competitive inhibitor of NO synthase. In vessels under resting tension, 10(-4) to 10(-3) M L-NAME induced a significant increase in tension only in veins but not in arteries. When tone was elevated with phenylephrine or U 46,619, a thromboxane A2 analogue, there was now a significant increase in tension in arteries with 10(-4) M L-NAME and in veins with 10(-5) M L-NAME. The increase in tension induced by L-NAME in veins was greater than that in arteries and greater when tone was elevated than under resting tension. Responses of pulmonary and mesenteric vessels were similar. Our data suggest that NO may play a role in regulating venous tone under baseline conditions and that the role of NO in regulation of vasomotor tone becomes more significant in the presence of nonspecific elevation of vasomotor tone in both arteries and veins. We speculate that endogenous NO production may be one mechanism by which pulmonary and systemic vessels counter the effects of vasoconstrictive agents.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1993

[Case report and review of literature on seasonal distribution and pathogenesis of acute eosinophilic pneumonia in Japan].

A 49-year-old female was admitted because of high grade fever and dyspnea. Chest roentgenogram revealed diffuse reticulo-linear shadows. Laboratory findings showed peripheral blood eosinophilia, and blood gas analysis demonstrated severe hypoxemia. A few days after admission, her symptoms and signs improved, and the abnormal shadows on the chest roentgenograms decreased without treatment. To determine the diagnosis and evaluate the pathological findings and pathogenesis, we performed open lung biopsy. Bronchoalveolar lavage at the operation revealed increased total cell count and increased markedly, number of eosinophils, and the open lung biopsy specimen showed acute interstitial pneumonia with eosinophilic infiltration. We performed a study of precipitating antibodies against fourteen kinds of fungi and environmental provocation tests, with all results being negative. We diagnosed this case as having acute eosinophilic pneumonia clinicopathologically (Allen, 1989). We reviewed 22 cases with acute eosinophilic pneumonia previously reported in Japan including our case. These 22 cases demonstrated a seasonal tendency of onset in spring and summer. Eleven of 22 cases were tested for precipitating antibodies to several fungi, 3 of which showed positive results against Trichosporon cutaneum, Trichoderma viride and Aspergillus species. The clinical features of acute eosinophilic pneumonia resemble those of summer type hypersensitivity pneumonitis. Therefore, it is important to diagnose AEP on the basis of clinical symptoms, and precipitating antibody, viral titer and pathological findings.

Acute Disease↗
PubMed1993

[A case of radiation pneumonitis caused by treatment of lung cancer which revealed marked hypervasculality on bronchial arteriography].

A 44-year-old man was admitted to our hospital because of hemoptysis. He had been admitted to our ward in June 1991, after resection of a brain tumor at another hospital due to cerebral metastasis of lung cancer (adenocarcinoma). Systemic chemotherapy and pulmonary irradiation therapy were performed during the first hospitalization. Radiation pneumonitis occurred 1 month after the completion of radiotherapy, which responded to administration of corticosteroids. One year and 4 months later after the completion of radiotherapy, he was readmitted to our hospital because of hemoptysis. Chest computed tomogram and bronchoscopy showed no recurrence of lung cancer, so pulmonary arteriography and bronchial arteriography were performed to investigate the cause of hemoptysis. Pulmonary arteriograms showed diminished vascularity in the area of radiation fibrosis, but a bronchial arteriogram showed inflammatory hypervascularization in the same field. We considered that the bronchial arterial angiogenesis induced by radiation pneumonitis was the cause of hemoptysis. Bronchial arteriography is necessary in cases of radiation pulmonary fibrosis with hemoptysis without obvious recurrence of tumor. If the growth of new blood vessels in the bronchial artery can be induced by radiation therapy, the administration of anti-cancer agents to the bronchial artery should be considered in the treatment of recurrent lung cancer after radiation therapy.

Adenocarcinoma↗
PubMed1992

In vitro responses of ovine intrapulmonary arteries and veins to endothelin-1.

We determined responses of third-generation intrapulmonary arteries and veins of fetal, newborn, and adult sheep to endothelin-1 (ET) and the role of endothelium and cyclooxygenase metabolites in ET effects in adult sheep lung vessels. Presence of endothelium in vessel rings was confirmed by response to endothelium-dependent vasodilators, acetylcholine or bradykinin. Vessel tension induced by ET was expressed as a percentage of tension induced by 100 mM KCl. We found that arteries and veins contracted to 10(-9) to 10(-6) M ET in a dose-dependent manner. Veins exhibited greater sensitivity to ET than arteries in all age groups. Arteries and veins of adult sheep lungs were more sensitive to ET than those of fetal and newborn lambs. In adult sheep lung vessels, pretreatment with indomethacin (5 x 10(-6) M) and SQ 29548, a thromboxane A2-prostaglandin H2 receptor antagonist (10(-5) M), significantly attenuated venous contraction to ET; arterial contraction was unaffected. Denuding vessels of endothelium did not affect responses to ET. We conclude that, in ovine lungs, veins are more sensitive to ET than arteries and that developmental differences in pulmonary vascular responses to ET exist.

Aging↗
PubMed1992

Vascular effects of platelet-activating factor in lambs: role of cyclo- and lipoxygenase.

In adult sheep, platelet-activating factor (PAF) effects include systemic hypotension and pulmonary hypertension. To identify developmental differences in vascular responses to PAF, we studied the effects of C18- and C16-PAF in 49 +/- 2- (SE) day-old lambs. Responses of upstream (arteries and microvessels) and venous segments of the lung to C18-PAF were determined both in vivo and in isolated lungs. In isolated lungs, the role of eicosanoids in PAF effects was also determined. In vivo, both C18- and C16-PAF caused a significant increase in systemic and pulmonary vascular resistance. The magnitude of vascular responses to C16-PAF was greater than that to C18-PAF. C18-PAF constricted both upstream and venous segments of the pulmonary circulation. Cyclooxygenase inhibition in isolated lungs attenuated arterial constriction to C18-PAF, whereas simultaneous cyclooxygenase and lipoxygenase inhibition completely blocked the effects of C18-PAF. In summary, in contrast to PAF effects in adult sheep, PAF constricts both systemic and pulmonary vessels in lambs, with significant pulmonary venous constriction. Eicosanoids, especially lipoxygenase products, play a major role in mediating PAF effects in the lung.

Anesthesia↗
PubMed1991

Endothelin effects in isolated, perfused lamb lungs: role of cyclooxygenase inhibition and vasomotor tone.

We have determined the sites of action of endothelin-1 (ET) in the lamb pulmonary circulation. The influence of cyclooxygenase inhibition and baseline vasomotor tone on ET effects was also studied. Lungs of 14 lambs (6-9 wk of age, 12.1 +/- 0.6 kg body wt) were isolated and perfused with blood. Group I lungs (n = 5) were untreated, group II lungs (n = 5) were treated with indomethacin to inhibit cyclooxygenase, and group III lungs (n = 4) were treated with indomethacin and a thromboxane A2 analogue, U-46619, to elevate vasomotor tone. All lungs were perfused with constant flow in zone 3, with left atrial and airway pressures being 8 and 6 cmH2O, respectively. We measured pulmonary arterial pressure and, by the micropuncture servo-null method, pressures in 20- to 50-microns diameter subpleural venules, both before and after each dose of ET was infused (50, 100, 250, and 500 ng/kg). Group I lungs, with high baseline vasomotor tone, exhibited a biphasic response to ET; 50-100 ng/kg of ET dilated both arteries and veins, whereas 500 ng/kg of ET constricted both arteries and veins. In group II lungs with low vasomotor tone, all doses of ET caused constriction of arteries only. In group III lungs (indomethacin treated with elevated vasomotor tone), 50-100 ng/kg of ET caused dilation of arteries and veins, whereas 500 ng/kg of ET induced constriction, this time only in arteries. We conclude that ET has both dilator and constrictor effects in arteries and veins of isolated, perfused lamb lungs. ET-induced arterial and venous dilation is dependent on initial vasomotor tone but not on cyclooxygenase metabolites.(ABSTRACT TRUNCATED AT 250 WORDS)

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1990

[Pharyngeal area measured by acoustic reflection technique while breathing room-air].

Although there have been many reports on the airway area measured by breathing 80% He-20% O2 (He-O2) using the acoustic reflection technique (ART), there have been no reports on that by breathing room-air (Air) because of the lack of accuracy in evaluating the trachea. When measuring with He-O2, accidental introduction of Air into the airway makes the measurement inaccurate. Moreover, it is a time-consuming method and is hardly applicable to dyspneic patients. Therefore, we tried to assess whether the airway area, especially the upper airway, can be measured while breathing Air. In order to compare the areas determined by the two methods, area-distance functions from the pharynx to the trachea were arbitrarily divided into 9 divisions at interval of 2.8 cm. Each of these divisions was respectively compared. We took averages of the pharyngeal, tracheal areas in 8 normal subjects. We found no significant difference between the oropharyngeal area measured by breathing Air and that measured by breathing He-O2, and found a significant correlation between them. There was a significant correlation between the hypopharyngeal areas when using the two methods. The average tracheal area by breathing Air is 4.96 +/- 0.50 cm2, which is 40% above that when measured using He-O2 (3.55 +/- 0.32 cm2). In contrast, the average pharyngeal area when breathing Air is 4.13 +/- 0.93 cm2, which overestimates that by breathing He-O2, namely 3.54 %/- 0.84 cm2 by only 17%. In conclusion, it is possible and useful to estimate the pharyngeal area by breathing Air.

Acoustics↗
PubMed1989

Mouth pressure curve on abrupt interruption of airflow during forced expiration.

An attempt was made to investigate how the mouth pressure curve represents the process of air flowing into the collapsed segment downstream to the choke point when the airflow is abruptly interrupted at the mouth during forced expiration. Immediately after the interruption of airflow, the mouth pressure suddenly increased (phase 1), followed by a slower rise in pressure (phase 2) within approximately 100 ms until the pressure reached the alveolar pressure. The pleural and alveolar pressures remained constant during this process. The first phase of the abrupt rise represented the pressure induced by the instantaneous interruption of the airflow itself. Analysis of the supramaximal flow (Vsupramax) observed after resumption of the airflow suggested that the choke point remained constant during the second phase of the mouth pressure after interruption of maximal flow (Vmax). From these results, examination of the second phase of the mouth pressure curve may provide useful information about the downstream segment of the airway.

Adult↗
PubMed1989

Airway pressure-volume curve estimated by flow interruption during forced expiration.

We attempted to estimate the pressure-volume characteristics of airways downstream from the choke point when the airflow was abruptly interrupted during forced expiration. The change of gas volume of the downstream segment after interruption could be estimated by multiplying the maximum flow (Vmax) immediately before interruption by the interruption time because the Vmax is maintained for a short period after airflow interruption at the mouth, as described in our previous report (J. Appl. Physiol. 66: 509-517, 1989). For the pressure of the downstream segment, we used the mouth pressure itself. Airway compliance, a slope of the pressure-volume curve, was measured in an airway model in eight normal subjects, in six patients with chronic obstructive pulmonary disease (COPD), and in one patient with tracheobronchopathia osteochondroplastica. Airway compliance was 0.96 ml/cmH2O in normal subjects and 2.49 ml/cmH2O in COPD patients. This difference of airway compliance was believed to be caused by the longitudinal expansion of the downstream segment and changes in the properties of the airway wall.

Adult↗
PubMed1989

High-frequency ventilation by bilateral phrenic nerve stimulation in dogs.

We succeeded in achieving good gas exchange by oscillatory phrenic nerve stimulation (PNS) in dogs. In 7 out of 14 dogs, adequate gas exchange was attained by PNS at 3, 4 and 5 pulses per sec (pps). VE increased with stimulation frequency up to 4 or 5 pps, but decreased above 6 pps. We also applied sinusoidal oscillation using a piston pump at the trachea in the same dogs to analyze the mechanical properties of the respiratory system. The V/P ratio, oscillatory volume divided by driving pressure, decreased markedly at 6 Hz while the pleural pressure remained constant up to 10 Hz. These facts indicate that the fall in VE is due to mechanical properties of the airway and lung, and not due to failure of the ventilatory pump system. We conclude that frequencies of 3-5 pps in high-frequency ventilation are optimal for maintaining effective gas transport when the diaphragma is used as the oscillatory generator.

Animals↗
PubMed1988

Mouth pressure curve on abrupt interruption of airflow during forced expiration.

The mouth pressure curve after abrupt interruption during forced expiratory maneuver was investigated to evaluate the collapsing state of the airway downstream to the choke point. Immediately after the airflow interruption at the mouth by means of the electromagnetic valve, the mouth pressure suddenly increased (1st phase), followed by a slower rise (2nd phase) within about 100 msec until the pressure reaches the alveolar pressure. The pleural and alveolar pressures remained constant during this process. It was evidenced that, from point of view of mean flow, the airflow flowed at a rate of Vmax through the choke point during the second phase. Thus, it is strongly suggested that the choke point remained at the same point during the 2nd phase. From these results, the 2nd phase of the mouth pressure is expected to represent the specific characteristics for the downstream airway.

Forced Expiratory Flow Rates↗
PubMed1988

Airway pressure-volume curve estimated by flow interruption during forced expiration.

The pressure-volume characteristics of the airway downstream to the choke point was estimated with abrupt interruption of airflow at the mouth during forced expiration. The pressure was measured at the mouth and the volume was given by the maximum flow immediately before interruption multiplied by interruption time. The compliance of the airway downstream to the choke point, i.e., a slope of the pressure-volume curve, was 1.04 ml/cmH2O at 50% FVC, and increased in lower lung volumes, in 7 healthy subjects. Whereas, in a case of tracheo-bronchopathia osteochondroplastica, its value decreased markedly.

Airway Resistance↗