Search PubMed⌕ Search

Biomedical subjects

S Okubo

Publications and source records attributed to S Okubo.

At least 145 records · Page 8Linked to original sources
PubMed1988

Serum doxapram and respiratory neuromuscular drive in normal man.

To investigate the means by which doxapram affects the control of ventilation, ventilatory function and P0.1 have been related to serum doxapram concentration during a 45-min infusion of doxapram hydrochloride in 7 healthy, conscious subjects under normoxic conditions. Serum doxapram concentrations increased during the infusion: 1.88, 2.48, 3.42, and 3.97 micrograms/ml after 5, 10, 30 and 45 min, respectively. The majority of significant changes in the measurements from the baseline were observed at 30 and 45 min: VE, VT, P0.1, P0.1/end-tidal CO2 tension, VT/Ti and blood pressure were increased, and end-tidal CO2 tension was decreased. No significant changes in Pdimax, Ti/Ttot, VE/P0.1, and P0.1/(VT/Ti) were observed. A correlation was observed between the % increases in P0.1 and VE and doxapram concentration, and between VE and P0.1. The doxapram-induced increase in VE appears to be caused by increased neural drive. It is related to the serum drug concentration in the conscious subject.

Adult↗
PubMed1988

Nodular regenerative hyperplasia of the liver associated with primary pulmonary hypertension.

Nodular regenerative hyperplasia (NRH), a rare hyperplastic condition of the liver, is reported in two patients with primary pulmonary hypertension (PPH). The first patient was a 26-year-old man who died of PPH and showed multiple NRH without cirrhosis of the liver. The second patient was a 25-year-old man who had a PPH with pulmonary arterial thrombi and NRH of the liver. NRH has been described in association with immune disease, hematopoietic disorder, and diabetes mellitus, so that NRH with PPH is considered to be very rare. Histologic findings of the lungs show typically plexogenic pulmonary arteriopathy in both cases, and the livers of these patients are composed of multiple nodules that are histologically represented by slightly larger hepatocytes arranged in a cobblestone-like fashion, and are ultramicroscopically characterized by massive proliferation of mitochondria. The pathogenetic association of nodular regenerative hyperplasia with primary pulmonary hypertension will be discussed.

Adult↗
PubMed1988

Flow and volume dependence of pulmonary mechanics in anesthetized cats.

The effects of inspiratory flow rate and inflation volume on pulmonary mechanics were investigated in six anesthetized-paralyzed cats ventilated by constant-flow inflation. Pulmonary mechanics were assessed using the technique of rapid airway occlusion during constant-flow inflation which allows measurement of the intrinsic pulmonary resistance (RLmin) and of the overall "pulmonary flow resistance" (RLmax), which includes the additional pulmonary pressure losses due to time constant inequalities within the lung and/or stress adaptation. We observed that, at fixed inflation volume, 1) RLmin fitted Rohrer's equation, 2) RLmax was higher at low than intermediate flows, and 3) RLmax-RLmin decreased progressively with increasing flow. At fixed flow, RLmax increased, whereas RLmin decreased with increasing volume. We conclude that during eupneic breathing in cats, the pulmonary flow resistance as conventionally measured includes a significant component reflecting stress adaptation.

Airway Resistance↗
PubMed1988

Long-term respiratory effects of neonatal hypoxia in the rat.

Rats maintained in a hypoxic environment during the 1st wk after birth decrease body growth and O2 consumption (VO2) and increase minute ventilation (VE). At the same time the lungs undergo changes in structure, which suggests a protection of the gas exchange area (Mortola et al. J. Appl. Physiol. 61: 1329-1336, 1986). In this study we asked to what extent these adaptive changes would persist after return to normoxia. Newborn rats were kept in 10% O2 during the 1st wk of life, then returned to normoxic breathing, and measurements were performed weekly. Body weight (BW) increased very little during the week of hypoxia, but after return to normoxia body growth was more than in control rats, and eventually BW reached the control value at 2 mo of age. Both VO2/BW (measured manometrically) and VE/BW (measured by flow plethysmography or by the barometric method) were above control in the 1st wk after hypoxia, probably reflecting the higher O2 demands of the rapidly growing animals. However, VE remained elevated even at 7-8 wk of age (i.e., postpuberty), at a time when both BW and VO2 were as in controls. Measurements of blood gases at this age indicated that the persistent hyperventilation was not due to hypoxemia and was accompanied by hypocapnia and alkalosis. Hematocrit and heart mass-to-BW ratio, elevated in hypoxia, returned to control values within 1 wk, whereas dry lung weight-to-BW ratio remained above the control values as much as during the hypoxic exposure. These results suggest that early postnatal hypoxia in the rat could have long-term effects on the regulation of breathing.

Age Factors↗
PubMed1988

Chest wall and respiratory system mechanics in cats: effects of flow and volume.

The effects of inspiratory flow rate and inflation volume on the resistive properties of the chest wall were investigated in six anesthetized paralyzed cats by use of the technique of rapid airway occlusion during constant flow inflation. This allowed measurement of the intrinsic resistance (Rw,min) and overall dynamic inspiratory impedance (Rw,max), which includes the additional pressure losses due to time constant inequalities within the chest wall tissues and/or stress adaptation. These results, together with our previous data pertaining to the lung (Kochi et al., J. Appl. Physiol. 64: 441-450, 1988), allowed us to determine Rmin and Rmax of the total respiratory system (rs). We observed that 1) Rw,max and Rrs,max exhibited marked frequency dependence; 2) Rw,min was independent of flow (V) and inspired volume (delta V), whereas Rrs,min increased linearly with V and decreased with increasing delta V; 3) Rw,max decreased with increasing V, whereas Rrs,max exhibited a minimum value at a flow rate substantially higher than the resting range of V; 4) both Rw,max and Rrs,max increased with increasing delta V. We conclude that during resting breathing, flow resistance of the chest wall and total respiratory system, as conventionally measured, includes a significant component reflecting time constant inequalities and/or stress adaptation phenomena.

Animals↗
PubMed1988

Effects of selective alpha 1-adrenoceptor blockade in dogs with hypoxic pulmonary vasoconstriction.

The acute effects of the selective alpha 1-blocker, E-643 (Bunazosine), on experimental pulmonary hypertension (PH) caused by hypoxic pulmonary vasoconstriction (HPV) in mongrel dogs were examined. Ninety second ventilation with 5% O2 and 95% N2 was used for hypoxic stimulation. The effects of E-643 were evaluated at doses of 1, 5, 10, 20 and 50 micrograms/kg in this order until the systemic arterial mean pressure (SAm) had decreased by 20 mmHg when compared with the control value during room air ventilation. PaO2 and PaCO2 decreased by 64.6 +/- 11.0 Torr and 2.4 +/- 2.5 Torr, respectively, and the pH increased by 0.031 +/- 0.012 during hypoxic ventilation. These blood gas changes affected during hypoxic stimulation were almost the same before E-643 administration. Progression of arterial blood hypoxemia due to E-643 administration during room air ventilation was not observed. SAm decreased by 8.0 +/- 11.9 mmHg after E-643 administration, while left atrial mean pressure (LAm) and cardiac output (CO) did not change significantly. Prior to E-643 administration, mean pulmonary arterial pressure (PAm) and pulmonary vascular resistance (PVR) increased by 6.4 +/- 3.3 mmHg and 6.2 +/- 3.8 HRU, respectively, during the 90 sec hypoxic ventilation period. After E-643 administration, the increases in PAm and PVR were 3.9 +/- 1.7 mmHg and 3.3 +/- 2.3 HRU, respectively. The suppression of increases in PAm and PVR was significant. The conclusion is that E-643, a selective alpha 1-blocker, is effective at restraining HPV in the dog model.

Adrenergic alpha-Antagonists↗
PubMed1988

Idiopathic isolated pulmonary arteritis with chronic cor pulmonale.

Multiple obstructions of the proximal pulmonary arteries were found in a patient with pulmonary hypertension and chronic cor pulmonale without any systemic arterial lesions. An operation to relieve severe stenosis at the right main pulmonary artery provided great clinical improvement. Pathologic examination of the biopsied specimen revealed a nonspecific panarteritis with giant cells consistent with idiopathic isolated pulmonary arteritis.

Arteritis↗
PubMed1988

Efficacy of absolute ethanol injection for upper gastrointestinal massive bleedings with hemorrhagic shock.

We applied the absolute ethanol injection method in 182 cases of massive bleeding with hemorrhagic shock before the performance of emergency endoscopy in 627 cases of upper gastrointestinal bleeding at our department and five related institutions since June 1979. Following results were obtained: Temporary hemostasis could not be obtained in only 2 (1.1%) out of 182 cases; in the remaining 180 cases bleeding was ceased. Rebleeding was seen in 15 cases (8.2%) and new bleeding in 17 cases (9.3%). In 21 (66%) of these cases hemostasis was obtained again by the absolute ethanol injection method. Eight patients (4.4%) underwent emergency operation and 4 patients (2.2%) died from bleeding. The complete hemostasis was obtained in 170 cases (93.4%).

Adolescent↗
PubMed1988

[Antiemetic treatment with metoclopramide and high-dose lorazepam and additional long-term treatment with lorazepam during CDDP administration].

We studied the antiemetic effects of a combination therapy consisting of metoclopramide (MCP) and high-dose lorazepam (HiLor; 3-4.5 mg/day) in patients with lung cancer who were being treated with cis-diamminedichloroplatinum (CDDP). This study was designed in order to compare the antiemetic efficacy of two different-term treatments. In the short-term treatment, MCP and HiLor were given for three days after the beginning of the CDDP regimen (group 1). In the long-term treatment (group 2), the same dose of MCP and a decreased dose of HiLor (1.5-3 mg/day) were administered for another three days (eventually for 6 days). Thirty-one trials were evaluated in eighteen patients for 8 days after the CDDP treatments initiated. The frequency of episodes of vomiting was less than two times in 70% and 82% of trails, in group 1 and group 2, respectively. This finding indicates that the combination therapy of MCP and HiLor for a long period would be the same or more effective than that of MCP and steroid agents. Furthermore, in group 2, the frequency and severity of late emesis were significantly less than in group 1, and appetite recovery was observed significantly earlier than in group 1. There was no side effect related to the administration of MCP and HiLor during this study. These findings suggested that the combination treatment of MCP and HiLor with a decreased dose of HiLor for a long period was markedly effective for antiemesis in patients treated with CDDP, especially for the prophylaxis of CDDP-induced late emesis.

Antineoplastic Combined Chemotherapy Protocols↗