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Biomedical subjects

T Tomaru

Publications and source records attributed to T Tomaru.

At least 73 records · Page 4Linked to original sources
PubMed1991

[Hemodynamic effects of endothelin in anesthetized dogs].

The purpose of the present study was to investigate and compare the hemodynamic responses that can be elicited in anesthetized dogs by intravenous administration of endothelin at rates of 300 (group E-I, n = 9) and 600 pmol.kg-1 (group E-II, n = 9) for 15 minutes. In group E-I, no significant pressure response was observed after administration of endothelin and cardiac index remained unchanged throughout the experiment. However, right and left ventricular work indices increased significantly but left ventricular maximum dp/dt and pulmonary vascular resistance decreased significantly. In group E-II, mean arterial pressure increased significantly by elevating systemic vascular resistance with marked decrease in cardiac index. However, right and left ventricular work indices remained unchanged throughout the experiment. On the other hand, each dose of endothelin significantly increased pulmonary capillary wedge pressure and left ventricular end-diastolic pressure but decreased heart rate. The present data revealed that the hemodynamic effects were different according to the doses of endothelin infused. In conclusion, our results show that endothelin (600 pmol.kg-1 BW) produces a long lasting increase in arterial pressure and endothelin-induced pressure responses are caused by an elevation in systemic vascular resistance.

Anesthesia, General↗
PubMed1991

[A comparison of the endocrine effects of hypotension induced by nicardipine with those by sodium nitroprusside in dogs].

Plasma catecholamines, plasma renin activity, plasma aldosterone and plasma cortisol during hypotension induced by sodium nitroprusside and nicardipine were studied in 27 mongrel dogs under 0.87% halothane in oxygen. They were randomly divided into three groups: sodium nitroprusside (group S: n = 8), nicardipine (group N: n = 8) and controls (group C: n = 9). Group C received no vasodilator therapy and served as a control. Mean arterial pressure was reduced and maintained at 60 mmHg for 60 minutes in hypotensive groups. No changes were noted in plasma catecholamines and plasma cortisol in group C throughout the experiment, but plasma renin activity and plasma aldosterone decreased progressively. During hypotension induced by sodium nitroprusside and nicardipine, plasma epinephrine was significantly higher than the control value. However, after the hypotensive drugs were discontinued, plasma epinephrine decreased slightly. During and after induced hypotension, plasma renin activity of group N and group S were significantly higher than the control values. The highest levels of plasma renin activity 36.7 ng.ml-1.hr-1 in group N and 23.2 ng.ml-1.hr-1 in group S were observed. Plasma aldosterone concentration was significantly higher than the control value in group N. The maximum increase occurred 30 minutes after discontinuation of the nicardipine and the highest concentration of plasma aldosterone was three times control value. In contrast, in group S, plasma aldosterone was unchanged from the control value. Plasma cortisol concentration of group N was significantly increased than the control value. However, in group S, plasma cortisol concentration showed a slight but not significant increase.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldosterone↗
PubMed1990

Temperature monitoring during peripheral thermo-optical laser recanalization in humans.

To determine probe temperature required to achieve laser thermal recanalization of human peripheral arteries, temperature was monitored at the probe tip using a K-type thermocouple and displayed on a computer screen in real-time in 21 procedures. Recanalization was performed using a Spectraprobe-PLR delivering both laser light and heat in patients with prolonged ischemic limb symptoms. Laser recanalization of totally occluded peripheral arteries (occlusion length = 5.3 +/- 3.8 cm) was done percutaneously (17 procedures) or intraoperatively (4 procedures), after unsuccessful attempts of recanalization using standard guide wire and balloon angioplasty techniques. Probes were activated using argon laser irradiation starting at 5 W and increased by 1-W increments until successful recanalization, or up to a maximum of 12 W. Laser recanalization was achieved in 16/21 (76%) procedures at a mean temperature of 178 +/- 120 degrees C (range 64-503 degrees C) and a mean time of 12.4 +/- 14.1 s. Eleven of the 16 (69%) recanalizations occurred at probe temperature lower than 160 degrees C. Recanalization was achieved at a mean power of 7 +/- 2 W. Perforation occurred in 6 arteries at peak probe temperatures ranging from 73 to 502 degrees C. Perforations occurred in 4 of 6 densely calcific vessels which required high probe temperatures (greater than 250 degrees C). An important feature of temperature monitoring was the immediate detection of probe dysfunction. Although recanalization temperature had a wide range, the majority of recanalizations occurred at probe temperature below 160 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

[Hemodynamic features of hypotension induced by nicardipine in dogs].

Hemodynamic features of hypotension induced by nicardipine were studied in 18 mongrel dogs under 0.87% halothane in oxygen (1MAC). They were randomly allocated to one of two groups. Group C received no vasodilator therapy and served as control and group N received infusion of nicardipine. Mean arterial pressure decreased and was maintained at 60 mmHg for 60 minutes in group N. No change was noted in hemodynamic variables measured in group C throughout the experiment. During and after induced hypotension in group N, cardiac index (CI), stroke volume index (SVI), central venous pressure (CVP), and right ventricular stroke work index (RVSWI) increased significantly compared with the control values. On the other hand, systemic vascular resistance (SVR) was significantly reduced, reaching 25% of the control value at the end of hypotension period. Heart rate showed a progressive increase but not significantly. Left ventricular maximum dp/dt showed a moderate increase during hypotension, but then decreased gradually to the control value after induced hypotension. Left ventricular stroke work index (LVSWI) and pulmonary vascular resistant (PVR) were unchanged from the control value during and after induced hypotension. The data indicate that nicardipine is a potent systemic vasodilator with hyperdynamic hemodynamic effects in addition to significant increase in right ventricular function.

Animals↗
PubMed1990

[Endocrine effects of hypotension induced by nicardipine in rabbits].

Endocrine effects of hypotension induced by nicardipine, a calcium antagonist, were studied in 18 male rabbits under halothane anesthesia. They were randomly divided into two groups; nicardipine (group N; n = 10) and controls (group C; n = 8). No change was noted in plasma catecholamines in group C throughout the experiment, but plasma renin activity decreased progressively. During and after induced hypotension, in group N, plasma epinephrine was significantly higher than the control value. The highest level of plasma epinephrine was seven times of the control value during 30 minutes after induction of hypotension. Plasma norepinephrine of group N was significantly higher than the controls. The maximum increase occurred 60 minutes after induction of hypotension. Plasma renin activity of group N was significantly higher than the control value. Compared with the control value (15.1 +/- 1.8 ng.ml-1.hr-1), plasma renin activity was activated 30 and 60 minutes after induction of hypotension (55.5 +/- 6.0 ng.ml-1.hr-1, P less than 0.001, 50.3 +/- 7.1 ng.ml-1.hr-1, P less than 0.01, respectively). In conclusion, our data show that hypotension by nicardipine activates the renin-angiotensin-sympathetic system.

Animals↗
PubMed1990

[Plasma and red blood cell cyanide concentrations during hypotension induced by sodium nitroprusside or by a nitroprusside-trimetaphan mixture in rabbits].

Plasma and red blood cells cyanide concentrations during hypotension induced by sodium nitroprusside and a nitroprusside-trimetaphan mixture were studied in 29 male rabbits under halothane anesthesia. They were randomly divided into three groups; Nitroprusside (group N; n = 10), A nitroprusside-trimetaphan mixture (group M; n = 10), Controls (group C; n = 9). No changes were noted in plasma and red blood cells cyanide concentrations in group C throughout the experiment. During and after induced hypotension, in group N, plasma cyanide concentration was significantly higher than the control value. The maximum increase occurred 60min after induction of hypotension and the highest concentration of plasma cyanide was six times the control value. In contrast, in group M, plasma cyanide concentration was unchanged from the control value. However, during and after induced hypotension, red blood cells cyanide concentrations of group N and group M were significantly higher compared with the control values. Red blood cells concentrations of cyanide increased for 30 and 60 min during induced hypotension in group N (27.11 +/- 3.9 micrograms.ml-1, P less than 0.001, 46, 73 +/- 4.7 micrograms.ml-1, P less than 0.001, respectively) and in group M (0.31 +/- 0.05 micrograms.ml-1, P less than 0.05, 0.29 +/- 0.03 micrograms.ml-1, P less than 0.05, respectively). In conclusion, the data suggest that a nitroprusside-trimetaphan mixture is a safe method for hypotensive anesthesia.

Animals↗
PubMed1989

Effect of CO2 and blood media on laser probe temperature.

Blood may limit laser ablation of arterial plaque by decreasing thermal energy transfer from metal-capped probes to arterial occlusions. Since a gas is a good insulator of heat, CO2 may be a better medium for laser recanalization. To study this possibility, a metal-capped fiber was positioned in a segment of blood-filled polyethylene tubing and activated with an argon laser. Probe temperatures were measured in blood and as the blood was displaced by flowing CO2 gas. Probe temperatures were higher at all powers studied in CO2 gas than in blood. Maximum probe temperatures averaged 518 +/- 24 degrees C after CO2 infusion versus 320 +/- 7 degrees C in blood, (P less than 0.0001). Blood aggregate formation was noted on the probe surface in blood but not in CO2 medium. Thus CO2 gas may be a preferable medium for laser recanalization, since higher probe temperatures are achieved, and the probe surface remains free of insulating blood coagulate.

Angioplasty, Balloon↗
PubMed1989

Enhancement of arterial thrombolysis with native tissue type plasminogen activator by pretreatment with heparin or batroxobin: an angioscopic study.

The enhancement of canine arterial thrombolysis with native tissue type plasminogen activator (nt-PA) obtained from human-derived normal cells by pretreatment with heparin or the defibrinogenating agent, batroxobin, was evaluated with angioscopy. The nt-PA, 0.25 mg/kg, was infused intravenously to lyse 1-hour-old thrombus (eight thrombosed arteries without medication, seven with nt-PA alone, seven with nt-PA and heparin, and seven with nt-PA plus batroxobin). Angioscopy provided a cross-sectional view of the vessel lumen with clear visualization of the thrombus. Thirty minutes after nt-PA infusion, the percent luminal obstruction decreased from 74 to 61 in nt-PA alone (p less than .025), from 77 to 37 in nt-PA plus heparin (p less than .005), and from 79 to 25 in nt-PA plus batroxobin (p less than .005). Fifteen minutes after drug infusion, plasma fibrinogen levels decreased to 89% of preinfusion value in nt-PA alone, to 84% in nt-PA plus heparin, and to less than 5% in nt-PA plus batroxobin. Thus rapid infusion of nt-PA alone provided slight thrombolytic effects. However, heparin and batroxobin showed marked enhancement of thrombolytic effects of nt-PA.

Angiography↗
PubMed1989

The thrombolytic effects of native tissue-type plasminogen activator (AK-124) on experimental canine coronary thrombosis.

To evaluate the thrombolytic effects of the native tissue-type plasminogen activator (t-PA), the authors used a thrombus model simulating clinical situations. The native t-PA (AK-124) was obtained from human-derived normal cells. Experimental canine coronary thrombosis was produced by partial constriction and endothelial denudation of the vessel. In 19 dogs, coronary occlusive thrombus was produced. Three hours after total occlusion of the coronary artery with thrombus, the authors attempted the thrombolytic therapy in 16 dogs. Histologically, three-hour thrombus was composed of a mixture of platelet aggregates, fibrin, and blood cells. They infused 0.375 mg/kg t-PA intravenously in 7 dogs and 20,000 IU/kg urokinase (UK) in 9. Coronary recanalization was achieved in 5 (71%) with t-PA infusion and 6 (67%) with UK infusion. Plasma fibrinogen levels decreased to 76% of preinfusion value in the dogs with t-PA infusion and to 34% in those with UK infusion. Coronary reocclusion occurred in 2 dogs with t-PA and 3 with UK. Thus, the native t-PA (AK-124) can provide coronary thrombolysis without severe depletion of plasma fibrinogen levels.

Animals↗
PubMed1989

[Comparison of effects on carbohydrate metabolism of hypotension induced by sodium nitroprusside and a nitroprusside-trimetaphan mixture in rabbits].

Effects on carbohydrate metabolism of hypotension induced by sodium nitroprusside and a nitroprusside-trimetaphan mixture were studied in 29 male rabbits under halothane anesthesia. They were randomly divided into three groups; Nitroprusside (Group N; n = 10), A Nitroprusside-Trimetaphan Mixture (Group M; n = 10), Control (Group C; n = 9). No changes were noted in blood glucose, blood lactate, blood pyruvate and lactate/pyruvate ratio in Group C throughout the experiment. During induced hypotension, blood glucose, blood lactate, blood pyruvate and L/P ratio of group N were significantly higher than the control value. On the other hand, in group M, blood glucose and blood pyruvate tended to increase slightly but not significantly. In contrast, in group M, L/P ratio remained unchanged. The results suggest that sodium nitroprusside tended to cause tissue hypoxia more markedly than a nitroprusside-trimetaphan mixture. The mechanism may be that a mixture of nitroprusside and trimetaphan maintained the carbohydrate metabolism (including gluconeogenesis, glucogenolysis) during induced hypotension. In conclusion, our results suggest that a nitroprusside-trimetaphan mixture is a safe method for hypotensive anesthesia.

Animals↗
PubMed1989

[A case of primary erythromelalgia (erythermalgia) treated with neural blockade].

A case of primary erythromelalgia which was treated successfully with lumbar sympathetic block and total spinal block (TSB) is reported. The patient was a 21-year-old woman with 18-year history of pain, burning, swelling, redness and warm sensation in both feet and lower part of the legs that caused the patient to soak her feet and legs frequently in ice cold water in order to obtain pain relief. The patient had been treated with a variety of medications including aspirin, indomethacin, methysergide maleate, and carbamazepine with no relief. Recently, the excessive exposure to cold water had caused extensive immersion foot (trench foot) with secondary infection (fusarium infection). Treatment with bilateral lumbar sympathetic block had markedly improved the symptom. Furthermore, treatment with TSB against causalgic state was performed 8 times for 4 months. During this period, the patient experienced the symptom which was much milder than those before treatment with TSB. Lumbar sympathetic block and TSB are useful methods for treatment of primary erythromelalgia.

Adult↗
PubMed1989

[Comparison of endocrine effects of hypotension induced by sodium nitroprusside, trimetaphan camsylate and a nitroprusside-trimetaphan mixture in rabbits].

Endocrine effects of hypotension induced by nitroprusside, trimetaphan and a nitroprusside-trimetaphan mixture were studied in 34 male rabbits under halothane anesthesia. They were randomly divided into four groups; nitroprusside (group N; n = 8), trimetaphan (group T; n = 10), a nitroprusside-trimetaphan mixture (group M; n = 8) and controls (group C; n = 8). No change was noted in plasma catecholamines measured in group C throughout the experiment, but plasma renin activity decreased progressively. During induced hypotension, plasma catecholamines and plasma renin activity of group N were significantly higher than the control value. In contrast, in group T plasma epinephrine decreased significantly. On the other hand, in group M, plasma renin activity showed a slight but not significant increase, while plasma catecholamines remained unchanged. This may have occurred since a mixture of nitroprusside and trimetaphan produced the dissociation of renin-angiotensin-sympathoadrenal loop. In conclusion, these results suggest that a nitroprusside-trimetaphan mixture is a useful method for hypotensive anesthesia by inhibiting the excessive activation of renin-angiotensin-sympathetic system.

Animals↗
PubMed1989

[The role of protein kinase C in left ventricular relaxation impaired by global ischemia].

The role of protein kinase C (C kinase) in the left ventricular relaxation impaired by global ischemia was investigated in anesthetised dogs. Left ventricular global ischemia model was made by coronary blood flow reduction and atrial pacing (100-180 beats/min). By this maneuver, the time constant T and left ventricular end-diastolic pressure (LVEDP) were increased in a pacing-rate dependent manner. Intracoronary infusion of H-7, an inhibitor of C kinase, suppressed the magnitudes of the increments of T and LVEDP, while intracoronary infusion of 12-O-tetradecanoyl-phorbol-13-acetate, an activator of C kinase, enhanced the increases of T and LVEDP caused by ischemia. In non-ischemic group, H-7 did not influenced T and LVEDP. The results indicate that C kinase is activated by myocardial ischemia and enhances impairment of left ventricular relaxation.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1988

Percutaneous pulmonary angioscopy using a guiding balloon catheter.

The applicability of angioscopy for observation of the pulmonary arterial lumen was examined in 7 anesthetized dogs and in 10 patients with various heart diseases during cardiac catheterization. A novel guiding balloon catheter (#11F shaft diameter and 1.5 cm in balloon diameter) was introduced through the right femoral vein into the pulmonary artery by Seldinger's method. Then, a fiberscope (1.3 or 1.8 mm in diameter) was introduced through the guiding catheter into the desired portion of the artery. The balloon was inflated, saline was infused, and the pulmonary arterial lumen was photographed on 16-mm color cinefilms. In all dogs and patients examined, an increase in diameter of the pulmonary artery during systole and the backflow of blood from the pulmonary vein were clearly demonstrated. Also, pulmonary thrombi or emboli experimentally induced in dogs could be observed. No complications were observed in the patients. The results indicate the experimental and clinical applicability of angioscopy using a guiding balloon catheter for observation of the pulmonary arterial lumen.

Adult↗
PubMed1988

Pathomorphological changes in experimentally induced canine myocardial infarction.

We performed a pathological study of experimental canine myocardial infarction (MI) induced by coronary thrombosis which was made by endothelial denudation and induction of luminal stenosis in 20 dogs (Group I). Another model of experimental MI by coronary ligation was also evaluated in Groups II and III. Thirteen dogs of Group I and 7 of Group II underwent persistent coronary occlusion for 6-8 h (Group IA and Group IIA), and 7 of Group I and 7 of Group II underwent coronary reperfusion with intravenous urokinase (UK) (20,000 IU/kg) in Group IB for 5 h following temporary coronary occlusion for 3 h (Groups IB and IIB). The remaining 5 dogs underwent coronary reperfusion for 5 h following intravenous 20,000 IU/kg UK after 3 h ligation. Microscopically, myocardial hemorrhage was present in 6 (86%) Group IB, 4 (31%) Group IA and in no Group IIA dogs (p less than .025 and p less than .005 vs. IB). Four Group IIB and 3 Group III dogs also showed myocardial hemorrhage. Moderate hemorrhage was present only in Group I and slight hemorrhage was frequently observed in reperfused hearts. Contraction band necrosis (CBN) was present in 8 (62%) Group IA, all Group IB, all Group IIB, and 4 (80%) Group III dogs. However, there was no hemorrhage with CBN in Group IIA (p less than .005 vs. IIB). Marked CBN was present only in Group I.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Preventive effects of batroxobin on experimental canine coronary thrombosis.

The thrombolytic effects of urokinase (UK) and preventive effects of batroxobin, heparin, and aspirin on the recurrence of thrombosis in the coronary artery were studied in 118 anesthetized dogs with severe endothelial denudation and luminal stenosis of the coronary artery. Occlusive thrombi developed in 68 (58%) preparations (dogs), accompanied by a decrease of coronary blood flow and pressure, an electrocardiographic ST elevation, and epicardial cyanosis. An intravenous infusion of 20,000 IU/kg of UK reopened the occluded coronary artery in all 32 preparations with 1-h-old thrombi, in 6 (86%) of 7 preparations with 2-h-old thrombi, and in 5 (83%) of 6 preparations with 3-h-old thrombi. However, recanalization was not observed in preparations with thrombi more than 4-h-old. Occlusion recurred within 6 h after recanalization in 2 (18%) of 18 preparations pretreated with batroxobin (1-2 BU/kg) (p less than .005 vs. control UK group), in 1 (14%) of 7 preparations administered a continuous infusion of 30 U/kg per h of heparin (p less than .05 vs. control UK group), in 4 (57%) of 7 preparations pretreated with 2 mg/kg of aspirin, and in 7 (64%) of 11 preparations not pretreated (control UK group). Complete prevention was observed only in the group administered 2 BU/kg of batroxobin. Histologically, these thrombi closely simulated clinical arterial thrombi. Myocardial hemorrhage and contraction band necrosis were observed in the reperfused hearts. In conclusion, experimental canine coronary thrombi more than 4-h-old were resistant to thrombolytic therapy, and batroxobin and heparin were effective in the prevention of coronary reocclusion.

Animals↗