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T Shibamoto

Publications and source records attributed to T Shibamoto.

At least 91 records · Page 5Linked to original sources
PubMed1992

Spatial and temporal differing control of sympathetic activities during hemorrhage.

We performed simultaneous multifiber recordings of cardiac, renal (RNA), hepatic (HNA), adrenal, and splenic sympathetic nerve activities during 10 min of sustained hemorrhagic hypotension to a mean blood pressure of 50 mmHg. One minute after bleeding in dogs with intact baroreceptors, all measured nerve activities increased significantly, and a gradual decline toward prebleeding level followed. Only RNA showed a great inhibition below prebleeding level. In cervically vagotomized dogs, all nerve activities showed significantly higher levels than prebleeding control throughout the experiment. The initial increase in HNA observed at 1 min postbleeding in animals with intact baroreceptors was attenuated. HNA in the vagotomized group showed a gradual increase so that 5 min postbleeding, HNA reached a peak level that was maintained until the end of the experiment. Sympathoinhibition in RNA and decrease in heart rate during hemorrhagic hypotension were reversed to significant increases after vagotomy. In contrast, animals with denervation of the carotid sinus and aortic nerves showed initial increases in nerve activities followed by recovery to prebleeding control level within 2 min postbleeding. After complete denervation of systemic baroreceptors, rapid hemorrhage did not cause any significant change in sympathetic nerve activity in any nerve. These results indicate that early reflex response to hemorrhage in regional sympathetic nerves is unidirectional sympathoexcitation mediated by summative unloading of both arterial baroreceptors and cardiopulmonary receptors. When greater than 1 min passed after bleeding and sustained hypotension of 50 mmHg was established, a reflex mechanism through the vagal afferents participated to inhibit the unidirectional sympathoexcitation mediated by unloading of arterial baroreceptors, with different magnitude in different innervated organs.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Glands↗
PubMed1992

Pulmonary vascular response to anaphylaxis in isolated canine lungs.

We determined changes in vascular resistance and microvascular permeability during anaphylactic reaction in isolated canine lungs perfused at constant pressure with autologous blood. In lungs with anaphylaxis induced by an intra-arterial injection of Ascaris suum antigen (10 mg), pulmonary vascular resistance and capillary pressure assessed as double occlusion pressure increased transiently by 10 times and 6.3 mmHg, respectively. Pre- to postcapillary vascular resistance ratio decreased from 0.89 +/- 0.05 to 0.21 +/- 0.06, suggesting predominant pulmonary venoconstriction. In lungs perfused in the antidromic direction from the pulmonary vein to the artery, anaphylaxis caused marked precapillary vasoconstriction, consistent with pulmonary venoconstriction. Vascular permeability assessed using the capillary filtration coefficient and isogravimetric capillary pressure did not change significantly for 3 h in either group. No changes were found in any variables in the saline-injected control lungs. The final weight of the anaphylactic lungs was significantly greater than that of the control lungs. Thus we conclude that anaphylaxis in isolated canine lung produces an increase in capillary pressure due to pulmonary venoconstriction without significant changes in vascular permeability. Pulmonary edema accompanied by anaphylactic hypotension may result from an increase in pulmonary hydrostatic intravascular pressure but not an increase in pulmonary vascular permeability.

Anaphylaxis↗
PubMed1991

Diagnosis of paraaortic and pelvic lymph node metastasis of gynecologic malignant tumors by ultrasound-guided percutaneous fine-needle aspiration biopsy.

Transabdominal ultrasonography was done in patients with gynecologic malignancies to detect paraaortic and pelvic lymphadenopathy. Of the 78 patients who underwent ultrasonic examination of pelvic lymph nodes, pelvic lymphadenopathy was detected in 24, of whom ultrasound-guided percutaneous fine-needle aspiration biopsies (FNAB) were done in 16. Of these 16 patients, the results of 13 biopsies were positive. Of the 41 patients who underwent ultrasonographic examination of the paraaortic lymph nodes, 27 had paraaortic lymphadenopathy. Ultrasound-guided percutaneous FNAB were done in 26 of these 27 patients, with positive findings in 21 of the 26. It was concluded that ultrasound-guided percutaneous FNAB is useful in detecting metastatic lymph nodes in gynecologic malignancies.

Abdominal Neoplasms↗
PubMed1991

Inhibitory effect of lichen constituents on mutagenicity induced by heterocyclic amines.

Physodic acid, one of the main constituents of Hypogymnia enteromorpha, inhibited the mutagenicity of indirect mutagens, including benzo[a]pyrene and heterocyclic amines in Salmonella typhimurium TA 98. In contrast, it was not effective against direct mutagens such as 6-nitropiperonal and adriamycin. Its antimutagenicity was not associated with free-radical scavenging or antioxidative activities. Physodic acid seemed to inhibit the formation of reactive metabolites, such as N-hydroxy-Trp-P-2, by blocking the hepatic microsomal oxidation systems. Another component of H. enteromorpha, physodalic acid, also inhibited mutagenicity of a heterocyclic amine, Trp-P-2, in S. typhimurium TA 98, even though it was reportedly mutagenic in S. typhimurium TA 100.

Animals↗
PubMed1991

Gas chromatographic analysis of malonaldehyde and 4-hydroxy-2-(E)-nonenal produced from arachidonic acid and linoleic acid in a lipid peroxidation model system.

Malonaldehyde (MA) and 4-hydroxynonenal (4-HN) formed upon oxidation with Fe2+/H2O2 from arachidonic acid and linoleic acid, and their ethyl esters were analyzed by gas chromatography (GC). The MA and 4-HN produced were reacted with N-methylhydrazine (NMH) to give 1-methylpyrazole and 5(1'-hydroxyhexyl)-1-methyl-2-pyrazoline, respectively. The derivatives were analyzed by GC on a fused silica capillary column using a nitrogen-phosphorus detector. With arachidonic acid, more MA and 4-HN were formed from the ester (88 nmol/mg and 23 nmol/mg, respectively) than from the free acid (25 nmol/mg and 9 nmol/mg, respectively). In contrast, with linoleic acid, more MA and 4-HN were produced from the free acid (53 nmol/mg and 13 nmol/mg, respectively) than from the ester (39 nm/mg and 8 nmol/mg, respectively).

Aldehydes↗
PubMed1991

Fructose 1,6-diphosphate augments paraquat injury in isolated dog lungs.

Paraquat (PQ; 1,1'-dimethyl-4,4'-bipyridylium dichloride), a widely used herbicide, causes pulmonary edema by a cyclic oxidation and reduction reaction with oxygen molecules with the production of oxygen free radicals. Because fructose 1,6-diphosphate (FDP) has recently been shown to inhibit the generation of oxygen free radicals by activated neutrophils, we determined the effects of FDP on PQ-induced increase in microvascular permeability in isolated blood-perfused dog lungs. Vascular permeability was assessed using the capillary filtration coefficient (Kf,c) and isogravimetric capillary pressure (Pc,i). There was no change in these variables over 5 h in the control lungs treated with saline (n = 5). A significant increase in Kf,c and a decrease in Pc,i, both of which indicated increased vascular permeability, were observed at 5 h of perfusion with 4 x 10(-3) M PQ (n = 5). Unexpectedly, an increase in microvascular permeability occurred within 4 h after administration of PQ in the lungs that were pretreated with FDP (2.7-14.2 mM, n = 6). Moreover the increases of Kf,c in the FDP-pretreated lungs were significantly greater than those in the lungs treated with PQ alone. Also, the final-to-initial lung weight ratio of the FDP-pretreated group was greater than those of the other groups. Thus the FDP dose used in the present study accentuated rather than prevented the PQ lung injury.

Animals↗
PubMed1991

Effect of hypertonic saline infusion on renal vascular resistance in anesthetized dogs.

Changes in renal vascular resistance (RVR) and their mechanisms were investigated following infusion of 7.5% hypertonic saline (4 ml/kg) in anesthetized dogs. In all animals the left kidney was perfused at a constant perfusion flow (59 +/- 6 ml/min) with heparinized blood using a pulsatile roller pump. Renal perfusion pressure (RPP), systemic blood pressure (SBP), central venous pressure (CVP), and heart rate (HR) were measured simultaneously. Electrical stimulation of renal sympathetic nerves was also performed to evaluate the neurally mediated change in renal vasculature before and after infusion of hypertonic saline. In animals with intact vagi, intravenous administration of hypertonic saline resulted in significant increases in both mean blood pressure (MBP) and CVP, and caused significant decreases in HR and RVR. These effects were not affected by bilateral cervical vagotomy. In both intact and vagotomized animals, changes in RVR in response to renal nerve stimulation were attenuated after infusion of hypertonic saline. These results suggest that reduction in RVR after intravenous infusion of hypertonic saline is not a reflex effect mediated by vagal afferents. Instead, vascular response of the renal artery to hypertonic saline may result from a suppression of neurotransmission from renal sympathetic nerve endings to renal vascular smooth muscle.

Animals↗
PubMed1991

[Anticoagulant].

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Acrylic Resins↗
PubMed1991

[Treatment and prognosis of pT2 endometrial carcinoma].

Between January, 1966 and December, 1988, 66 patients with surgical-pathological stage II adenocarcinoma of the endometrium who were treated with abdominal simple or radical hysterectomy at the Osaka National Hospital were studied retrospectively. The 5-year survival rate for all patients was 75.7%. In 33 patients adenocarcinoma had invaded the cervical stroma. These patients demonstrated a significantly lower survival (60.0%) than those patients whose involvement was limited to the endocervical gland (91.7%) (p less than 0.05). For all patients, both with endocervical glandular involvement and cervical stromal invasion, radical hysterectomy improved survival rates more than did simple hysterectomy, but the difference was not statistically significant. The factor found to have a significant influence on survival was the maximal depth of invasion of the myometrium (p less than 0.05). The histologic grade, on the other hand, did not appear to influence survival. It is suggested that patients with minimal involvement of the cervix can be satisfactorily treated with simple hysterectomy, while patients with gross cervical spread should be treated with radical hysterectomy.

Adenocarcinoma↗
PubMed1990

Contribution of baroreceptor reflexes to blood pressure and sympathetic responses to cholecystokinin and vasoactive intestinal peptide in anesthetized dogs.

The effects of synthetic vasoactive intestinal peptide (VIP) and cholecystokinin (CCK) on systemic blood pressure and renal nerve activity were studied before and after cervical vagotomy, and sino-aortic denervation with vagotomy in anesthetized dogs. Intravenous injection of VIP (5 micrograms/kg) in animals with an intact neuraxis produced a significant decrease in systemic blood pressure and a significant increase in renal nerve activity. These responses to VIP did not change after vagotomy and after complete denervation, VIP did not cause any change in renal nerve activity, even during hypotension. The level of hypotension after complete denervation was greater than that under other conditions. These results indicate that the cardiovascular effects of VIP are reduced by activation of the systemic baroreceptors. Intravenous injection of CCK (10 micrograms/kg) in animals with an intact neuraxis produced significant decreases in blood pressure and renal nerve activity. These responses to CCK were abolished in animals with cervical vagotomy only. However, following complete denervation of the carotid sinus and total section of the vagal nerves, CCK caused a significant increase in blood pressure and renal sympathetic nerve activity. These results indicate that the sympathetic depressor effect of CCK may be mediated by activation of the vagal afferents, and that the sympathetic pressor effect may be due to a direct action of CCK on the central nervous system. Thus, each gastrointestinal peptide may regulate the cardiovascular system through a different mechanism.

Anesthesia↗
PubMed1990

Gas chromatographic analysis of reactive carbonyl compounds formed from lipids upon UV-irradiation.

Peroxidation of lipids produces carbonyl compounds; some of these, e.g., malonaldehyde and 4-hydroxynonenal, are genotoxic because of their reactivity with biological nucleophiles. Analysis of the reactive carbonyl compounds is often difficult. The methylhydrazine method developed for malonaldehyde analysis was applied to simultaneously measure the products formed from linoleic acid, linolenic acid, arachidonic acid, and squalene upon ultraviolet-irradiation (UV-irradiation). The photoreaction products, saturated monocarbonyl, alpha,beta-unsaturated carbonyls, and beta-dicarbonyls, were derivatized with methylhydrazine to give hydrazones, pyrazolines, and pyrazoles, respectively. The derivatives were analyzed by gas chromatography and gas chromatography-mass spectrometry. Lipid peroxidation products identified included formaldehyde, acetaldehyde, acrolein, malonaldehyde, n-hexanal, and 4-hydroxy-2-nonenal. Malonaldehyde levels formed upon 4 hr of irradiation were 0.06 micrograms/mg from squalene, 2.4 micrograms/mg from linolenic acid, and 5.7 micrograms/mg from arachidonic acid. Significant levels of acrolein (2.5 micrograms/mg) and 4-hydroxy-2-nonenal (0.17 micrograms/mg) were also produced from arachidonic acid upon 4 hr irradiation.

Acetaldehyde↗
PubMed1990

Reflex effects on renal nerve activity and renal vascular tone during occlusion of superior mesenteric artery in anesthetized dogs.

This study was designed to evaluate the contribution of the systemic baroreceptor reflex on renal nerve activity (RNA) and renal vascular resistance (RVR) during occlusion of the superior mesenteric artery (SMAO) in anesthetized dogs. Animals were divided into two groups; RVR evaluated group and RNA measured group. For evaluation of changes in RVR, the left kidney was perfused at a constant flow with heparinized blood by using a pulsatile roller pump. Renal perfusion pressure, arterial blood pressure and heart rate were measured simultaneously. During SMAO, MAP and RVR increased significantly in animals with intact systemic baroreceptors. After combined denervation of the carotid sinus and vagal nerves, a significant enhancement of this RVR response during SMAO occurred and the level of changes in RVR were significantly greater than those in animals with an intact neuraxis. In the RNA measured group, renal sympathetic nerve activity, arterial blood pressure and heart rate were measured simultaneously before and during SMAO. During SMAO, MAP and RNA increased significantly in animals with intact systemic baroreceptors. These MAP and RNA responses to SMAO were significantly enhanced in animals with combined denervation of the carotid sinus and vagal nerves. These results indicate that SMAO evokes an increase in arterial blood pressure, renal sympathetic nerve activity and renal vascular resistance. The reflex increase in renal nerve activity and renal vascular tone during SMAO is modified and minimized by an activation of systemic baroreceptors.

Adrenergic Fibers↗
PubMed1990

Inhibitory effect of renal nerve activity during canine anaphylactic hypotension.

We have examined baroreceptor regulation of renal nerve activity (RNA) during anaphylactic hypotension that affects renal nerve activity. In anesthetized dogs, mean blood pressure (MBP), heart rate (HR), and RNA were simultaneously measured. To test for a normally functioning baroreceptor reflex in each animal, a transient hypotension was induced by an intravenous injection of sodium nitroprusside (4 micrograms/kg). Nitroprusside produced a reflex increase in RNA (+63 +/- 12% at -20 mmHg and +139 +/- 8% at -40 mmHg) and HR (+13 +/- 1 beats/min at -20 mmHg and +21 +/- 2 beats/min at -40 mmHg). However, intravenous administration of Ascaris suum antigen in animals with an intact neuraxis caused a decrease in RNA (-15 +/- 14% at -20 mmHg and -42 +/- 11% at -40 mmHg blood pressure during the antigen-induced hypotension) in parallel with a fall in systemic blood pressure. HR responses were -5 +/- 2 beats/min at -20 mmHg and -10 +/- 1 beats/min at -40 mmHg during the hypotension induced by the antigen. In animals with combined denervation of the carotid sinus and vagal nerves, HR did not change significantly during anaphylactic hypotension. However, a decrease in RNA remained (-60 +/- 4% at -20 mmHg and -72 +/- 4% at -40 mmHg of hypotension). The decrease in RNA after antigen administration was significantly greater after denervation than in animals with an intact neuraxis. These results indicate that systemic baroreceptor reflex control of RNA is reduced during anaphylactic hypotension. Impaired reflex control of sympathetic nerve activity may result from an impairment of sympathetic outflow through the central nervous system.

Anaphylaxis↗
PubMed1990

Derecruitment of filtration surface area in paraquat-injured isolated dog lungs.

The capillary filtration coefficient (Kf,c) is a sensitive and specific index of vascular permeability if surface area remains constant, but derecruitment might affect Kf,c in severely damaged lungs with high vascular resistance. We studied the effect of high and low blood flow rates on Kf,c in papaverine-pretreated blood-perfused isolated dog lungs perfused under zone 3 conditions with and without paraquat (PQ, 10(-2) M). Three Kf,cs were measured successively at hourly intervals for 5 h. These progressed sequentially from isogravimetric blood flow with low vascular pressure (I/L) to high flow with low vascular pressure (H/L) to high flow with high vascular pressure (H/H). The blood flows of H/L and H/H were greater than or equal to 1.5 times that of I/L. There were no significant changes in Kf,c in lungs without paraquat over a 50-fold range of blood flow rates. At 3 h after PQ, I/L-Kf,c was significantly increased and both isogravimetric capillary pressure and total protein reflection coefficient were decreased from base line. At 4 and 5 h, H/L-Kf,c was significantly greater than the corresponding I/L-Kf,c (1.01 +/- 0.22 vs. 0.69 +/- 0.09 and 1.26 +/- 0.19 vs. 0.79 +/- 0.10 ml.min-1.cmH2O-1.100 g-1, respectively) and isogravimetric blood flow decreased to 32.0 and 12.0% of base line, respectively. Pulmonary vascular resistance increased to 12 times base line at 5 h after PQ. We conclude that Kf,c is independent of blood flow in uninjured lungs. However, Kf,c measured at isogravimetric blood flow underestimated the degree of increase in Kf,c in severely damaged and edematous lungs because of a high vascular resistance and derecruitment of filtering surface area.

Animals↗
PubMed1990

PO2 modulation of paraquat-induced microvascular injury in isolated dog lungs.

We determined the effects of paraquat (PQ) concentrations ranging from 10(-3) to 10(-2) M and three levels of venous PO2 [hypoxia (41 +/- 3 Torr), normoxia (147 +/- 8 Torr), and hyperoxia (444 +/- 17 Torr)] in the presence of 4 x 10(-3) M PQ on microvascular permeability in isolated blood-perfused dog lungs. Capillary filtration coefficient (Kf,c) increased and isogravimetric capillary pressure (Pc,i) decreased 3 h after perfusion with 10(-2) M PQ (n = 7) and 5 h after perfusion with 4 x 10(-3) M PQ (n = 6) but not with 10(-3) M PQ (n = 4). In hyperoxic lungs perfused with 4 x 10(-3) M PQ, Kf,c increased to nine times the base-line value 5 h after PQ [0.15 +/- 0.01 to 1.35 +/- 0.25 (SE) ml.min-1.cmH2O-1.100 g-1]. Pc,i significantly decreased from a base-line value of 9.4 +/- 0.2 to 7.1 +/- 0.4 cmH2O at 3 h. In hypoxic lungs perfused with 4 x 10(-3) M PQ (n = 5), Pc,i and Kf,c changes were not significantly different from those in normoxic lungs treated with PQ. Thus both hyperoxia and an increased dose of PQ shortened the latent period and increased the severity of the PQ-induced microvascular permeability lesion, but hypoxia failed to prevent the PQ damage.

Animals↗
PubMed1990

Reflex responses on blood pressure and renal nerve activity to local intra-arterial injection of capsaicin in anesthetized dogs.

The present study was performed to examine effects of intra-arterial and intravenous injection of capsaicin on efferent renal sympathetic nerve activity (RNA) in pentobarbital anesthetized dogs. In animals with intact baroreceptors, intra-arterial injection of capsaicin (4 +/- 1 microgram) produced significant increases in mean blood pressure (MBP) and heart rate (HR) by +43 +/- 8 mmHg and +33 +/- 15 beats/min at 20 s after the injection, respectively. There followed a recovery toward the control so that 60 s after the intra-arterial injection changes in MBP and HR were +8 +/- 5 mmHg and +18 +/- 8 beats/min, respectively. RNA showed a biphasic response, comprising of an initial increase (+52 +/- 28% of the control at 20 s) followed by a decrease by -30 +/- 8% of the control 60 s after the injection. Following bilateral cervical vagotomy the initial increase in RNA did not differ significantly from the value of RNA in animals with intact baroreceptors. However, the later decrease in RNA reversed above the control so that 60 s after the injection change in RNA was +5 +/- 10% of the control. Complete baroreceptor denervation showed a similar response on RNA in the vagotomized animals (+49 +/- 9 and +14 +/- 10% of the control at 20 and 60 s after the injection, respectively). In contrast, intravenous injection of capsaicin (6 +/- 1 microgram/kg) resulted in significant decreases in MBP (-19 +/- 11 mmHg) and HR (-9 +/- 4 beats/min). RNA at 20 s after the injection showed a unidirectional decrease by -16 +/- 7% of the control in animals with intact baroreceptors. These responses reversed above the control after cervical vagotomy. Thus, these data indicate that activation of C-fiber afferents in skeletal muscles by intra-arterial injection of capsaicin results in renal sympathoexcitation, and that the later sympathoinhibition is mediated by combined activation of systemic baroreceptors.

Animals↗
PubMed1989

Dexamethasone in the treatment of acute mountain sickness.

Cerebral edema occurs in fatal cases of acute mountain sickness. Dexamethasone, commonly used to treat cerebral edema due to other causes, also reduces the symptoms of acute mountain sickness when given prophylactically. However, the efficacy of dexamethasone in the treatment of established acute mountain sickness remains uncertain. To investigate this question, we exposed six men in a hypobaric chamber to a simulated altitude of 3700 m (barometric pressure, 64 kPa [481 mm Hg]) for 48 hours on two occasions. Acute mountain sickness was diagnosed with use of a symptoms questionnaire, and dexamethasone (4 mg every six hours) or placebo was then given in a randomized, double-blind, crossover fashion. Dexamethasone reduced the symptoms of acute mountain sickness by 63 percent (P less than 0.05), whereas placebo had a minimal effect (reduction by 23 percent; P not significant). In spite of this response, one subject had mild cerebral edema on brain CT after both placebo and dexamethasone. Dexamethasone had no effect on fluid shifts, oxygenation, sleep apnea, urinary catecholamine levels, the appearance of chest radiographs or perfusion scans, serum electrolyte levels, hematologic profiles, or the results of psychometric tests. Dexamethasone treatment was complicated by mild hyperglycemia in all subjects (mean [+/- SE] glucose level, 7.3 +/- 1.3 mmol per liter [132 +/- 23 mg per deciliter]). We conclude that dexamethasone effectively reduces the symptoms of acute mountain sickness. However, it did not improve objective physiologic abnormalities related to exposure to high altitudes. We therefore recommend that dexamethasone be used only when descent is impossible, or to facilitate cooperation in evacuation efforts.

Acute Disease↗