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Biomedical subjects

H Obara

Publications and source records attributed to H Obara.

At least 181 records · Page 10Linked to original sources
PubMed1990

The effect of diltiazem on the cardiovascular response to tracheal intubation.

The efficacy of diltiazem in the attenuation of the cardiovascular response to laryngoscopy and tracheal intubation was studied in patients who received 0.2 or 0.3 mg/kg diltiazem 60 seconds before the start of laryngoscopy. These data were compared with a control group who received saline. Each group consisted of 10 patients who had elective surgery. Patients who received saline showed a significant increase in mean arterial pressure and rate pressure product associated with tracheal intubation. These increases after tracheal intubation were reduced in diltiazem-treated patients compared with those of the control group (p less than 0.05). The data suggest that a bolus injection of diltiazem is a simple, practical and effective method to attenuate the hypertensive response to laryngoscopy and tracheal intubation.

Blood Pressure↗
PubMed1990

Perioperative effect of methylprednisolone given during lung surgery on plasma concentrations of C3a and C5a.

Methylprednisolone or saline (placebo) solution was infused intravenously in 28 patients undergoing elective lobectomy for lung cancer. The state of the complement system during and after surgery and the effects of methylprednisolone on biologically active products of complement were studied by measurements of plasma C3a and C5a anaphylatoxins and leukocyte counts in peripheral blood perioperatively. In the placebo group plasma concentrations of C3a were significantly increased on postoperative days 1 and 2, whereas C5a had risen significantly 6 hours after surgery and on days 1 and 2. Methylprednisolone infusion during surgery eliminated the postoperative elevation of C3a and C5a. The postoperative leukocyte count in peripheral blood was higher in the methylprednisolone group than in the controls. The observations indicated that methylprednisolone may reduce the influx of leukocytes from peripheral blood into the airways by attenuating production of biologically active complements.

Complement Activation↗
PubMed1989

The effect of hyperoxia on the lungs of rats deficient in essential fatty acids.

Morphological alterations in the lungs of rats deficient in either or both of vitamin E and essential fatty acids were investigated after exposure to hyperoxia for 48 h. In rats deficient in both vitamin E and essential fatty acids, there was damage to type-2 alveolar cells observed as swollen mitochondria and bleb formation in the cytoplasm. None of these changes was found in rats deficient in only one of these substances. Hyperoxia in rats deficient in both substance also caused destruction of the capillary endothelial cells and edema in the interstitium. The lungs of rats deficient in only one of the substances showed some edema in the capillary endothelial cells, but not destruction, and less interstitial edema. These findings suggest that simultaneous deficiency in vitamin E and essential fatty acids facilitates lung damage in rats exposed to hyperoxia.

Journal Article↗
PubMed1989

Effect of dopamine on parathyroid hormone release during surgery.

There is much evidence that dopamine (DA) may play an important role in modulating parathyroid gland function. DA stimulates parathyroid hormone (PTH) secretion in cattle, which increases ionized calcium, but is without such effect on humans under normal physiological conditions. Ionized calcium plays a major role in muscle contraction including myocardial contractility. Therefore, we studied the PTH response to infusion of DA (4 micrograms/kg/min) under pathophysiological states during two different types of surgery; gastrectomy with halothane anesthetics and open heart surgery with high-dose fentanyl anesthetics. There was no change in PTH concentration, as measured by radioimmunoassay, in patients undergoing gastrectomy, although infusion of DA in these patients was effective in lowering the prolactin levels. However, plasma PTH concentration significantly increased where DA was applied (4 micrograms/kg/min) in patients undergoing open heart surgery. These results suggest that DA may stimulate PTH secretion by an indirect mechanism in humans under pathophysiological states, although details of the mechanism are unknown, and that there is the possibility that DA would indirectly regulate the levels of electrolytes such as ionized calcium and phosphate in patients undergoing open heart surgery mediated by elevation of PTH.

Calcium↗
PubMed1989

Endothelium-dependent relaxation in isolated pulmonary arteries from rabbits exposed to hyperoxia.

The effects of hyperoxia and superoxide dismutase (SOD) administration on endothelium-dependent relaxation induced by acetylcholine in isolated rabbit pulmonary artery (PA) preparations were examined. Relaxation responses to papaverine, and contractile responses to KCl and norepinephrine were also assessed using a bioassay technique. Prolonged hyperoxia in rabbits for 3 days produced loss of endothelium-dependent relaxation of the PA, and significant attentuation of contractile response to KCl and relaxation response to papaverine. These changes were prevented by subcutaneous SOD administration. Histological examination using light and electron microscopy revealed focal edema, destruction, and detachment of the PA endothelium in the PA strip preparations from these rabbits. Thus, it is concluded that a high concentration of oxygen exposure in rabbits for 3 days produces not only histological damage in the PA endothelium, but also causes impairment of vascular reactivity to constricting and relaxing agents. Subcutaneous SOD administration prevented oxygen-induced PA damage.

Acetylcholine↗
PubMed1989

[An unclassifiable case of hypoplastic leukemia in old age treated successfully with vincristine and prednisolone].

An 80-year-old male was admitted because of dizziness and palpitation. Laboratory investigation revealed pancytopenia. A bone marrow aspirate showed a markedly hypocellular marrow with 41.6% blast cells. Peroxidase activity was negative and PAS reaction was block positive in the blast cells. Surface markers of these cells were positive for HLA-DR antigen and partially positive for CD13 (MY7). Other markers, such as T, B or myeloid antigens were all negative. These blast cells were classified as L1 according to the FAB system but suggested essentially unclassifiable in cell differentiation. The patient was treated successfully with vincristine and prednisolone and induced into complete remission although repeated marrow examination findings revealed hypocellular. As for the classification of hypoplastic leukemia, lymphoid or primitive "stem cell" leukemia also should be considered as other categories of acute leukemias and be treated according to each case.

Aged↗
PubMed1988

Continuous infusion of vecuronium in children.

The average dose of vecuronium required in children continuous infusion to attain a steady state block of 90% was determined. The electromyographic (EMG) response and mechanical response to supramaximal stimulation of the ulnar never recorded simultaneously, were significantly correlated in four children. The steady-state infusion rate requirement of vecuronium was 1.4 +/- 0.03 micro g/kg/min during 2% enflurane anesthesia and 3.1 +/- 0.03 micro g/kg/min during 1% halothane anesthesia. The spontaneous recovery time to 25% of the control by EMG during halothane and enflurane anesthesia was 12.6 +/- 1.1 and 10.3 +/- 1.5 min, respectively, after termination of the infusion. There was no cumulative effect after prolonged vecuronium infusion.

Journal Article↗
PubMed1988

Hypoxic contractile response in isolated human pulmonary artery: role of calcium ion.

The mechanism for hypoxic pulmonary vasoconstriction (HPVC) was investigated in human pulmonary arterial strips. Hypoxia in the presence of histamine (10(-6) M) caused marked pulmonary arterial contraction, which was reversed by O2. The hypoxic contraction in the presence of histamine was inhibited by diphenhydramine, but not by cimetidine. The hypoxic histamine-mediated contraction was attenuated but still present in the absence of extracellular Ca2+, or by the inhibitors of voltage-dependent Ca2+ influx. However, it was inhibited significantly by a further depletion of intracellular Ca2+, or by HA 1004, an intracellular calcium antagonist. A low concentration (10(-7) M) of a calcium ionophore, A23187, enhanced the hypoxic contraction in the presence of histamine, whereas procaine completely inhibited it. W-7, a calmodulin inhibitor, significantly decreased the hypoxic histamine-mediated contraction, but 12-O-tetradecanoylphorbol-13-acetate (TPA), a C-kinase promotor, had no effect. The hypoxic contractile response was also observed in the presence of both A23187 and KCl instead of histamine, but the hypoxia-induced contraction with KCl alone was much smaller than that. These results indicate that hypoxia in the presence of certain other vasoactive agents has a potent contractile effect on the human pulmonary artery and that the response is dependent on Ca2+. Enhancement of both Ca2+ influx and Ca2+ release from intracellular storage sites by hypoxia, which interacts with calmodulin, were suggested to be involved in the mechanism of HPVC.

Aged↗
PubMed1988

Maturation-related changes in dopamine-induced relaxation of isolated rabbit pulmonary artery.

Studies were performed on isolated pulmonary arterial segments to investigate dopamine receptor-mediated relaxant effects at different times during development. Dopamine receptor-mediated relaxant effects can only be observed when vessels are precontracted with prostaglandin F2 alpha and in the presence of alpha 1, alpha 2, beta, and serotonergic blockade. Helical strips of pulmonary arteries from rabbits of different ages (2, 7, 14, 30, and 90 days), partially precontracted by prostaglandin F2 alpha were tested for their responses to dopamine in the presence of prazosin (10(-6) M), yohimbine (10(-6) M), propranolol (10(-6) M), and methysergide (10(-6) M). Strips from 2- and 7-day-old rabbits were not induced to relax by dopamine, whereas those from 14-, 30-, and 90-day-old animals, after cumulative application of dopamine, underwent concentration-dependent relaxation. Dopamine (half the maximum response) concentration decreased during the development of rabbits from 14 to 90 days old. Mean values for apparent dopamine ED50 (half the maximum response) concentrations in the arteries of 14-, 30-, and 90-day old animals were 4.94 +/- 0.40, 2.02 +/- 0.30, and 0.113 +/- 0.028 microM, respectively. The effects of various dopamine antagonists on dopamine-induced relaxation were not markedly different at different ages. These findings indicate that dopamine receptor function is not fully developed in the pulmonary arteries of newborn rabbits, but matures as the age of the rabbit increases.

Aging↗
PubMed1988

Release of thromboxane A2 by low-dose almitrine in the hypoxic dog.

Potentiation of hypoxic pulmonary vasoconstriction by a low dose of almitrine bismesylate (1 microgram.kg-1.min-1) was evaluated in terms of blood chemical mediator concentrations. Time course changes in the blood concentrations of adrenaline, noradrenaline, serotonin, histamine, thromboxane TXB2 and 6-keto-PGF1 alpha were monitored after administration of almitrine bismesylate for 15 min at 1 microgram.kg-1.min-1) in hypoxic and normoxic beagles. The low almitrine dose significantly increased TXB2 levels in hypoxic beagles, but the levels remained virtually unchanged in the normoxic animals with almitrine bismesylate and in the hypoxic animals with solvent. TXB2 levels did not increase when the almitrine infusion was increased to 5 micrograms.kg-1.min-1 for 15 min in hypoxic conditions. These findings suggest that almitrine is involved in arachidonic acid metabolism at a low rate of infusion and that thromboxane release from hypoxic areas of the lung may cause local vasoconstriction.

6-Ketoprostaglandin F1 alpha↗
PubMed1987

Eventration of the diaphragm in infants and children.

The study reviews 18 infants and children with eventration of the diaphragm who were treated over a period of eight years. The affected diaphragm and pulmonary tissue were examined by light and electron microscopy. The 18 patients, ranging in age from 10 days to 6 years, were divided according to Thomas' classification into a group with the congenital (10 patients) and a group with the acquired type (8 patients). Fifteen of these patients underwent surgery with diaphragmatic plication. On microscopic examination, biopsies of the lung showed atelectasis and pneumonia. These pathological changes became increasingly diffuse and severe with age. The diaphragm in patients with the congenital type of eventration was occupied by diffuse fibroelastic tissue. In patients with the acquired type, the cross-striated muscles of the diaphragm showed degenerative changes such as fragmentation, and interstitial fibrosis of the diaphragm became prominent with age. The results of this clinical study suggest that, in order to reduce the pathological changes in the lung, early surgical plication should be performed even in patients with the acquired type, if respiratory and digestive symptoms are noted.

Diaphragmatic Eventration↗
PubMed1987

Effect of combined high-frequency oscillatory ventilation on rabbit alveolar type-2 cells.

The effects on lung tissue of high-frequency oscillatory ventilation combined with intermittent mandatory ventilation (HFO-IMV) were compared with those of conventional mechanical ventilation (CMV) by matching the mean tracheal pressure. Pulmonary alveolar type-2 cells and subcellular organelles from rabbit lung were morphometrically examined by electron microscopy. The volume and surface densities of lamellar bodies in alveolar type-2 cells from the animals ventilated with HFO-IMV were decreased significantly compared with those from the animals either ventilated with CMV or breathing spontaneously (control group). The cell surface to volume ratio in the HFO-IMV group showed a significant increase compared with the CMV groups, whereas other variables showed no differences between the three groups. These results suggest that the secretion of surfactant from alveolar type-2 cells was enhanced in HFO-IMV-treated animals compared with CMV-treated and control groups.

Animals↗