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Biomedical subjects

R Ishii

Publications and source records attributed to R Ishii.

At least 91 records · Page 5Linked to original sources
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↗
PubMed1995

Characterization of the facilitatory prejunctional purinoceptor on adrenergic nerves of the rabbit ear artery.

The effects of a number of purinoceptor agonists and antagonists on the release of endogenous norepinephrine (NE) from electrically field-stimulated (2 ms, 4 Hz) rabbit ear arteries were determined. NE was quantified by high-performance liquid chromatography and electrochemical detection techniques. Both P1- and P2-purinoceptor agonists enhanced the release of NE in a concentration-dependent manner (0.1 microM-100 microM), the relative order of potency being beta, gamma-methylene ATP (beta gamma-mATP) > 2-chloroadenosine (2CA) > ATP > L-phenylisopropyl-adenosine > 2-methylthio ATP > 5'N-ethylcarboxamido-adenosine. Adenosine and alpha, beta-methylene ATP (alpha beta-mATP) at 100 microM did not significantly enhance the electrical field stimulation-evoked release of NE. None of drugs changed the spontaneous overflow of NE. Pretreatment with alpha beta-mATP (1, 10 microM), a P2x-purinoceptor desensitizing agent, and 8-sulfophenyl theophylline (8SPT; 1 and 10 microM), a P1-purinoceptor antagonist, caused a shift to right of the concentration-release curve for beta gamma-mATP. alpha beta-mATP and 8SPT did not by themselves significantly affect the spontaneous overflow and the electrical field stimulation-evoked release of NE. Pretreatment of alpha beta-mATP (30 microM) and 8SPT (30 microM) antagonized facilitation of NE release by 2CA (10 microM). The concentration-contraction curve for beta gamma-mATP (1-300 microM) in the rabbit ear artery was shifted to the right by alpha beta-mATP (30 microM) but not by 8SPT (30 microM).(ABSTRACT TRUNCATED AT 250 WORDS)

2-Chloroadenosine↗
PubMed1994

Cerebellar hemorrhage complicating cervical durotomy and revision C1-C2 fusion.

STUDY DESIGN: A case of cerebellar hemorrhage complicating cervical durotomy and revision C1-C2 fusion is reported. There has been only one report on cerebellar hemorrhage after cervical durotomy. SUMMARY OF BACKGROUND DATA: The patient became comatose approximately 16 hours after surgery. According to a review of the recovery room records, the patient's cerebellar hemorrhage probably occurred some time within the first 10 hours after the procedure and not during the operation. METHODS: The authors reviewed reports on complicated cerebellar hemorrhage, and the causative factors were studied. CONCLUSION: Postoperative drainage of cerebrospinal fluid, especially when negative pressure is applied, may play a role in the occurrence of cerebellar hemorrhage.

Aged↗
PubMed1994

Methoxamine-induced release of endogenous ATP from rabbit pulmonary artery.

Methoxamine, an alpha 1-adrenoceptor agonist, significantly increased the overflow of ATP, ADP and AMP, but not adenosine, by a prazosin-sensitive mechanism in the rabbit pulmonary artery. Among the adenine nucleotides released, the amount of ATP was larger than those of the other two. Such release of adenine nucleotides was not induced by clonidine, an alpha 2-adrenoceptor agonist, and isoproterenol, a beta-adrenoceptor agonist. Methoxamine-induced release was observed in the absence of extracellular calcium, but was not observed at a low temperature, 27 degrees C. This suggests an extracellular calcium-independent and temperature-dependent ATP-releasing mechanism coupled with alpha 1-adrenoceptors in rabbit pulmonary artery.

Adenosine Triphosphate↗
PubMed1994

Relationship between hypotensive effects and plasma concentrations of clonidine in spontaneously hypertensive rats: continuous treatment and sudden termination of clonidine infusion.

1. Clonidine was administered subcutaneously (62.5, 125 and 250 micrograms/kg/day) for 8 days using an osmotic infusion pump in spontaneously hypertensive rats (SHR). Clonidine, administered at 125 and 250 micrograms/kg/day at 48 hr after infusion, respectively, and thereafter were maintained at this level throughout the infusion period. 3. After terminating clonidine infusion, a rapid drug elimination from the plasma was manifested in both groups (125 and 250 micrograms/kg/day) with plasma clonidine levels, resulting in a decrease below 0.5 ng/ml at 4 and 6 hr, respectively. Four hours after terminating clonidine infusion at 125 and 250 micrograms/kg/day, transient but not remarkable increases in blood pressure and heart rate were observed only in the latter group compared with the values before termination. 4. These findings reveal that marked hypotensive effects were induced by relatively high doses (125 and 250 micrograms/kg/day) of clonidine in SHR, but no remarkable withdrawal symptoms after termination of clonidine infusion were observed. Therefore, unwanted withdrawal symptoms probably occur when an extremely high dose (250 micrograms/kg/day or more) of clonidine was infused for a long period (8 days or more) in SHR.

Animals↗
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↗
PubMed1994

[Meralgia paresthetica after spinal anesthesia].

A 27-year-old man underwent appendectomy under spinal anesthesia with 0.3% dibucaine 2.7 ml. The perioperative course was uneventful. The surgical procedure, however, lasted for 1.5 hours in the supine position. On the second postoperative day, a postspinal headache occurred and lasted for 18 days. On the seventh postoperative day the patient complained of numbness along the anterolateral aspect of the left thigh innervated by the lateral cutaneous nerve. There was no reflex or motor deficit indicative of the involvement of other nerves. The disorder was diagnosed as meralgia paresthetica caused by the surgical procedures. The numbness disappeared after the oral administration of mecobalamin in several days. In the treatment of a case like this, it is important to exclude neurological complications caused by spinal anesthesia.

Administration, Oral↗
PubMed1994

[A method of tracheal intubation tried in a patient with multicentric reticulohistiocytosis].

A 48-year-old woman had suffered from multiple destructive arthritis, skin nodules and skin ulcer of bilateral legs caused by multicentric reticulohistiocytosis for 16 years. Skin transplantation and total hip joint replacement were scheduled. Tracheal intubation was anticipated to be difficult because of destructive arthritis of the temporomandibular joint. We tried a new method to intubate the trachea through a laryngeal mask. After topical application of 8% lidocaine to the oropharynx, a size 4 laryngeal mask was inserted and its cuff was inflated by 20 ml of air. Anesthesia was induced with 4% sevoflurane in 50% nitrous oxide via laryngeal mask. A fiberscope through a tracheal tube was inserted through the laryngeal mask into the trachea. A tracheal tube with the internal diameter of 6.5 mm, was successfully intubated. This method gave little discomfort to the patient.

Female↗
PubMed1993

Methoxamine enhances the release of endogenous noradrenaline from rabbit ear artery: possible involvement of ATP.

The effect of methoxamine, an alpha 1-adrenoceptor agonist, on the electrically-evoked release of endogenous noradrenaline was examined in the isolated rabbit ear artery. Noradrenaline was quantified by high performance liquid chromatography-electrochemical detection. The release of adenine nucleotides and nucleosides by methoxamine was examined using high performance liquid chromatography-fluorescence detection. The release of noradrenaline evoked by electrical field stimulation (EFS) at 4 Hz was reduced by tetrodotoxin 0.3 mumol/l and clonidine 1 mumol/l by approximately 80% and 50%, respectively. On the other hand, methoxamine at 10 but not 1 mumol/l enhanced the release of noradrenaline to approximately twice the control, and the enhancement was prevented by prazosin 1 mumol/l. The facilitatory action of methoxamine was also abolished after desensitization of P2-purinoceptors by alpha,beta-methylene ATP 30 mumol/l as well as by the presumed P2-purinoceptor antagonist suramin given at 10 mumol/l. Exogenous ATP 10 mumol/l significantly enhanced the EFS-evoked release of noradrenaline, and the enhancement was abolished by alpha,beta-methylene ATP and suramin. None of the drugs changed the spontaneous outflow of noradrenaline. These results indicate that endogenous ATP, acting at prejunctional purinoceptors, may participate in the facilitatory effect of methoxamine. Indeed, methoxamine 10 mumol/l significantly enhanced the spontaneous outflow of ATP and, less so, ADP. The methoxamine evoked release of ATP and ADP was antagonized by prazosin 1 mumol/l. It is concluded that methoxamine releases endogenous ATP from postjunctional sites which then, via prejunctional purinoceptors, facilitates action potential-evoked release of noradrenaline in rabbit ear artery.

Adenine Nucleotides↗
PubMed1993

Stress hormone responses to major intra-abdominal surgery during and immediately after sevoflurane-nitrous oxide anaesthesia in elderly patients.

We studied the responses of plasma epinephrine, norepinephrine, adrenocorticotropic hormone (ACTH), cortisol, and antidiuretic hormone (ADH) during and immediately after sevoflurane-nitrous oxide anaesthesia supplemented with vecuronium in seven elderly patients (mean 76.6 +/- 1.7 SEM) who underwent major intra-abdominal surgery. The plasma concentrations of norepinephrine, ACTH, cortisol, and ADH increased in response to surgical procedures (P < 0.05). The plasma concentration of ADH increased to a peak concentration of 189.1 +/- 20.7 pg.ml-1 30 min after skin incision (P < 0.05). The plasma concentrations of epinephrine, norepinephrine, ACTH, and cortisol increased to peak concentrations of 408.6 +/- 135.5 pg.ml-1, 635.7 +/- 167.8 pg.ml-1, 222.6 +/- 48.0 pg.ml-1, and 113.6 +/- 67.5 micrograms.dl-1, respectively immediately after tracheal extubation (P < 0.05). We conclude that, in the elderly patients, the responses of stress hormones to major intra-abdominal surgery were preserved during sevoflurane-nitrous oxide anaesthesia sufficient to prevent increases in arterial pressure and heart rate. The strongest responses of epinephrine, norepinephrine, ACTH, and cortisol were elicited immediately after tracheal extubation.

Abdomen↗
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↗