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Biomedical subjects

R Ishii

Publications and source records attributed to R Ishii.

At least 19 recordsLinked to original sources
PubMed1995

Relationship between histamine receptors in the brain and diazepam-induced hyperphagia in rats.

We investigated whether histaminergic neurons in the brain are involved in diazepam-induced hyperphagia in rats. Pretreatment with intracerebroventricular (ICV) injection of either histamine H1-receptor antagonist, pyrilamine (10 and 30 micrograms) or histamine H2-receptor antagonist, famotidine (3 and 10 micrograms) did not affect only diazepam (1 mg/kg, subcutaneous, SC)-induced hyperphagia in nondeprived rats, but also spontaneous feeding in food-deprived rats. In addition, pretreatment with ICV injection of histamine H3-receptor antagonist, thioperamide, and histamine H3-receptor agonist, (R) alpha methylhistamine, enhanced and inhibited diazepam-induced hyperphagia (1 mg/kg, SC) in nondeprived rats, respectively. However, thioperamide and (R) alpha methylhistamine did not affect spontaneous feeding in food-deprived rats. These findings suggest that histaminergic neurons are not directly involved in diazepam-induced hyperphagia in rats. Furthermore, enhancement or inhibition of diazepam-induced hyperphagia by histamine H3-receptor antagonist or agonist may occur via histamine H3-receptors localized in the other neurons in the rat brain.

Animals↗
PubMed1995

High potassium-evoked release of ATP from rabbit pulmonary artery via endogenous noradrenaline.

1. High potassium 30 mM and noradrenaline at 10 microM significantly evoked the release of ATP and produced remarkable vasoconstriction in the rabbit pulmonary artery. 2. Phentolamine and prazosin at 0.1 microM inhibited ATP release but not vasoconstriction by 30 mM potassium. 3. 30 mM potassium significantly evoked the release of noradrenaline. 4. There was a significant positive correlation between the amounts of release of total purines, sum of ATP, ADP, AMP and adenosine, and noradrenaline evoked by 30 mM potassium. 5. 30 mM potassium-evoked ATP release was significantly reduced by denudation of endothelium.

Adenosine Triphosphate↗
PubMed1995

Effects of graded infusion rates of propofol on cardiovascular haemodynamics, coronary circulation and myocardial metabolism in dogs.

We have studied the effects of a 30-min infusion of propofol 6, 9, 12, 15, 18 and 21 mg kg-1 h-1 on cardiovascular haemodynamics, coronary circulation and myocardial metabolism in 12 mongrel dogs. Mean plasma concentrations of propofol after infusion of 6 and 21 mg kg-1 h-1 increased from 2.9 (SEM 0.3) to 11.5 (0.1) micrograms ml-1. Propofol produced a progressive decrease in arterial pressure. Heart rate tended to decrease at 15, 18 and 21 mg kg-1 h-1 and cardiac index decreased significantly at infusion rates > or = 9 mg kg-1 h-1. Systemic vascular resistance tended to increase except at 21 mg kg-1 h-1 and left ventricular systolic and diastolic function were depressed. Both coronary sinus blood flow and myocardial oxygen consumption decreased in parallel with a decrease in left ventricular minute work index without producing lactate. Propofol produced progressive decreases in coronary blood flow and myocardial oxygen consumption but did not exert adverse effects on the coronary circulation.

Anesthetics, Intravenous↗
PubMed1995

Comparison of the effects of halothane, isoflurane, and sevoflurane on atrioventricular conduction times in pentobarbital-anesthetized dogs.

It is not known how sevoflurane affects the cardiac conduction system. We compared the effects of halothane, isoflurance, and sevoflurane on specialized atrioventricular (AV) conduction times in eight pentobarbital-anesthetized dogs. AV conduction times with three inhaled anesthetics at end-tidal concentrations of 1 and 2 minimum alveolar anesthetic concentration (MAC), were measured by His-bundle electrocardiography during both sinus rhythm and right atrial pacing at a slightly higher rate than sinus one. Heart rate and arterial pressure were simultaneously recorded. Halothane prolonged AV nodal conduction time during sinus rhythm (A-H interval) at 2 MAC compared with the control value, whereas isoflurane and sevoflurane did not alter the A-H interval, His-Purkinje conduction time (H-V interval), and ventricular conduction time (H-S interval) during sinus rhythm at 1 and 2 MAC. All three inhaled anesthetics did not change AV conduction times during right atrial pacing. No significant difference in AV conduction times was observed between isoflurane and sevoflurane. Heart rate during sinus rhythm remained unchanged despite a decrease in arterial pressure with three inhaled anesthetics. The property of sevoflurane and isoflurane which does not affect the cardiac conduction system may be important in the stability of the cardiac rhythm during anesthesia with these drugs.

Anesthesia, Intravenous↗
PubMed1995

Absence of tolerance to hypotensive effects of clonidine in spontaneously hypertensive rats.

Development of tolerance to the hypotensive effects of clonidine was investigated in spontaneously hypertensive rats (SHR). Clonidine (125 micrograms/kg/day) was administered subcutaneously for 5 weeks using an osmotic infusion pump. During the whole infusion period, significant hypotensive and bradycardiac effects were observed. Plasma clonidine concentrations were maintained relatively constant at about 2 ng/ml during the infusion period. On termination of treatment with clonidine, both the blood pressure and heart rate rapidly recovered to the control levels. These findings suggest that clonidine does not cause tolerance to its hypotensive effects in SHR with the present administration regimen.

Animals↗
PubMed1995

Retrieval of a migrated detachable coil--case report.

A 74-year-old female presented with intraventricular and subarachnoid hemorrhage due to probable rupture of a basilar artery (BA) aneurysm or a superior cerebellar artery (SCA) aneurysm. She was treated by endovascular therapy using detachable coils through the BA. The BA aneurysm was completely occluded, but part of a coil migrated into the BA from the SCA aneurysm during the procedure. The migrated coil was retrieved using a snare type endovascular retrieving device. The snare loop required concentric closure around the coil by simultaneous pulling of the corewire and a slight forward movement of the tip of the snare catheter. The SCA aneurysm was successfully occluded 1 week later using a shorter coil.

Aged↗
PubMed1995

Magnetic resonance imaging and histology of a large cystic meningioma--case report.

A 9-year-old boy presented with a meningioma containing a large cyst. Magnetic resonance (MR) imaging demonstrated tumor cells in the solid part of the tumor, part of the cyst wall, and cyst septum. The presence of the tumor cells in the thin cyst wall or the cyst septum is important to recognize preoperatively, and MR imaging is very useful to differentiate intratumoral cysts from peritumoral cysts in meningiomas.

Child↗
PubMed1995

[Pharmacokinetics of SK & F 104864 in experimental animals. I. Plasma level].

A camptothecin derivative, SK & F 104864 (topotecan), was injected for 30 minutes into the rabbit ear vein at a dose of 2 mg/kg or 5 mg/kg, and the plasma concentration was assayed by a HPLC method. The plasma level of SK & F 104864 (lactone form) decreased bi-exponentially with mean alpha and beta half-lives of 0.101 h and 0.849 h at 2 mg/kg, respectively, and 0.518 h and 7.57 h at 5 mg/kg, respectively. The AUCs were 0.846 micrograms.h/ml at 2 mg/kg and 2.14 micrograms.h/ml at 5 mg/kg. The plasma level of total topotecan (SK & F 104864 plus SK & F 105992) decreased bi-exponentially with mean alpha and beta half-lives of 0.696 h and 9.07 h at 2 mg/kg, respectively, and 0.795 h and 8.97 h at 5 mg/kg, respectively. The AUCs were 2.15 micrograms.h/ml at 2 mg/kg and 5.73 micrograms.h/ml at 5 mg/kg. The AUCs of lactone form were 39.3% of total topotecan at the 2 mg/kg dose and 37.3% at the 5 mg/kg dose, respectively. After intravenous bolus injection of SK & F 104864 at 20 mg/kg into Sarcoma 180 bearing mice, the alpha and beta half-lives of SK & F 104864 were 0.401 h and 3.99 h, respectively, and the AUC was 5.49 micrograms.hr/ml. The alpha and beta half-lives of total topotecan were 0.517 h and 4.27 h, respectively, and the AUC was 9.88 micrograms.hr/ml. The ratio of lactone form to total topotecan was 55.6%.

Animals↗
PubMed1995

[Pharmacokinetics of SK & F 104864 in experimental animals. II. Tissue distribution].

After intravenous bolus injection of a camptothecin derivative, SK & F 104864 (topotecan), at 20 mg/kg into Sarcoma 180 bearing mice, the tissue concentration of total topotecan (SK & F 104864 plus SK & F 105992) in the mice decreased bi-exponentially, and the beta half-lives in most tissues were longer than those in plasma. The AUCs of total topotecan were extremely large in the kidney, that was followed by the pancreas > intestine > stomach > spleen > liver > thymus > lung > tumor > uterus > plasma. The concentration of total topotecan after 24 hours decreased to less than 2% of the peak level in most tissues except the kidney.

Animals↗
PubMed1995

[Severe bradycardia and hypotension during epidural anesthesia in a patient undergoing hemorrhoidectomy].

Severe bradycardia and hypotension developed suddenly in two patients undergoing hemorrhoidectomy under lumbar epidural anesthesia in the jackknife position, about 5 to 10 min after epidural administration of buprenorphine. Severe vago-vagal reflex was supposed to have been induced with buprenorphine in a situation where venous return was decreased by epidural anesthesia and the jackknife position.

Anesthesia, Epidural↗
PubMed1994

Magnetic resonance imaging of ecchordosis physaliphora--case report.

A rare case of ecchordosis physaliphora clearly demonstrated by magnetic resonance (MR) imaging is described in a 48-year-old male who presented with right hearing disturbance and reduction in sensation in the right side of his face due to a large cystic schwannoma. MR imaging revealed the large cystic schwannoma as well as an abnormal clival lesion. The clival lesion was hypointense on T1-weighted images and hyperintense on T2-weighted images, and not enhanced by gadolinium-diethylenetriamine-penta-acetic acid (Gd-DTPA) administration. The clival lesion was partially removed. The histological diagnosis was ecchordosis physaliphora. The postoperative course was uneventful. The absence of enhancement of ecchordosis physaliphora by Gd-DTPA administration may be a characteristic finding, in contrast to chordoma which is generally enhanced.

Brain Neoplasms↗
PubMed1992

[Effects of sodium hyaluronate on the nociceptive response of rats with experimentally induced arthritis].

Antinociceptive effects of sodium hyaluronate (Na-HA) were studied on the basis of improvement in the graded abnormal gait elicited by arthritis induced by intra-articular administration of monosodium urate crystal (MSU) to rats. One hour before MSU injection, intra-articular administration of a 1.0% solution of Na-HA with different molecular weights, ranging from 4.70 x 10(5) to 2.02 x 10(6) (HA-200), improved the score of abnormal gait in a molecular weight-dependent manner in the experimental arthritis model. Similarly, administrations of HA-200 at concentrations ranging from 0.1 to 1.0% prior to MSU treatment resulted in improvement of the score in abnormal gait in a dose-dependent manner. To elucidate the antinociceptive mechanisms of Na-HA, effects of pretreatment with Na-HA (1.0%) of different molecular weights on prostaglandin E2 (PGE2) and bradykinin (BK) releases in synovial fluid 3 hr after MSU injection were studied. Increases in PGE2 and BK concentration in the synovial fluid were depressed in a molecular weight-dependent manner by Na-HA (1.0%) pretreatment. These results indicate that Na-HA attenuates the nociceptive responses inflicted by the MSU-induced arthritis. Such an antinociceptive effect may be due to the inhibition of PGE2 and BK synthesis in the synovial joint of rats.

Analgesics↗
PubMed1992

[Hemodynamics and serum nitroglycerin concentration during intraoperative use of nitroglycerin patches].

We investigated the effect of number of nitroglycerin (TNG) as patches, containing 5 mg of TNG per sheet, on hemodynamics in 29 adult patients undergoing elective surgery. Patients were randomly allocated to four groups according to the number of the sheets applied (0, 2, 5 and 10 sheets). Hemodynamics as well as plasma TNG concentration were measured at 4 points (just before and 30, 60 or 120 minutes after application of TNG patch) in each group (n > or = 6). Plasma TNG concentrations depended on the number of the sheets and increased until 120 min after the application. Mean arterial pressure decreased gradually and significantly after applying two sheets or more. However, no relation was observed between the plasma concentration of TNG and the decrease in mean arterial pressure. We conclude that induced hypotension can not be intensified by increasing the number of the sheets of TNG patch.

Administration, Cutaneous↗
PubMed1992

[Usefulness of 99mTc-ECD SPECT in diseases of the central nerve system: special reference to a comparison with 123I-IMP and 99mTc-HM-PAO SPECT].

The usefulness of a new cerebral perfusion imaging radiopharmaceutical, 99mTc-ethyl cysteinate dimer (ECD), was clinically evaluated. The subjects of this study were 14 patients with neurological disorders including 10 patients with cerebral infarction and 4 patients with other diseases. A total of 15 examinations was performed. 99mTc-HM-PAO or 123I-IMP SPECTs were performed simultaneously, and the findings from those examinations were compared with 99mTc-ECD. As to the count ratio of lesions to normal area (L/N), the L/N ratio in severe ischemic patients was lower in 99mTc-ECD than in 99mTc-HM-PAO or 123I-IMP. In mild ischemic patients, on the other hand, the L/N ratio was the lowest in 123I-IMP. When the relationship between rCBFs obtained from 123I-IMP and the values of L/N in 99mTc-ECD or 99mTc-HM-PAO was compared, the values of L/N in 99mTc-ECD or 99mTc-HM-PAO were found to have decreased linearity with increasing rCBF. In a patient showing luxury perfusion, the accumulation pattern of 99mTc-ECD was different from that of the other two radiopharmaceuticals, and focal defect was revealed in 99mTc-ECD SPECT. On the dynamic SPECT of 99mTc-ECD in a patient with meningioma, the tumor showed a change from high to low perfusion with the passage of time. This finding indicated that care should be taken in the evaluation of accumulation of 99mTc-ECD. Therefore, 99mTc-ECD was found to be useful as a cerebral perfusion agent. In addition, as accumulation of 99mTc-ECD might somehow reflect metabolism in some cases, further careful investigation of many cases should be carried out.

Adult↗
PubMed1991

[Neurosurgical management of dialyzed patients].

Cerebrovascular disease is a lethal complication for patients with renal failure because of the hemostatic disturbance and equivocality about management of the central nervous system. Appropriate management of the renal failure in neurosurgical patients was considered on the basis of experience. Hemodialysis (HD), which is the most common dialysis method, has a serious disadvantage: the elevation of intracranial pressure during dialysis due to the "disequilibrium syndrome." It is important to stabilize the serum osmolarity during dialysis in order to prevent the disequilibrium syndrome. From this point of view, continuous ambulatory peritoneal dialysis (CAPD) has great advantages; serum osmolarity is not rapidly changed and no anticoagulants are required during dialysis. CAPD is recommended as the first method of choice in neurosurgical management of renal failure patients. However, if a patient has to be maintained with HD because of a history of laparotomy or peritonitis, it is essential to keep the serum osmolarity as stable as possible using the extracorporeal ultrafiltration method, hypernatremic HD, bicarbonate HD, and intravenous administration of glycerol.

Adult↗
PubMed1991

[Diurnal variation of intraocular pressure in low tension glaucoma].

Around-the clock intraocular pressure (IOP) measurement were performed in 104 eyes of 52 low tension glaucoma (LTG) cases. Subjects were all hospitalized and IOP measurements were done every 2 hours from 6:00 AM to 12:00 PM and every 3 hours from 12:00 PM to 6:00 AM. All LTG patients met the following criteria, (1) glaucomatous optic nerve head change and corresponding visual field defect, (2) normal open angle, (3) IOP less than or equal to 21mmHg at any time of IOP measurement, (4) no obvious neurological or rhinological disorders that could affect the optic nerve, (5) no history of hemodynamic crisis or cardiovascular disorders except mild hypertension. Peak IOPs were most frequently observed at 10:00 AM, but about 55% of all observed peaks were in the time period from 6:00 PM to 8:00 AM. Most troughs were observed from 2:00 PM to 10:00 PM. The mean IOP, the diurnal variation and the difference between both eyes in the same person averaged 14.1, 4.9, and 0.6mmHg, respectively. Assuming that the period of rhythm is 24 hours, the results of IOP measurements fitted a cosine curve using the least square method. In 44% of all eyes, significant correlation coefficient (r greater than or equal to 0.6, p less than 0.05) between the measured and the predicted IOPs was noted, and an equation, IOP = 14.3 + 1.7cos 2 pi (t/24-0.4 radian), was obtained. Comparing the present results with former ones, we concluded that the IOP changes in LTG patients were similar to those in normal individuals.

Circadian Rhythm↗