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Biomedical subjects

R Shimizu

Publications and source records attributed to R Shimizu.

At least 73 records · Page 4Linked to original sources
PubMed1997

Effects of magnesium sulphate on atrioventricular conduction times and surface electrocardiogram in dogs anaesthetized with sevoflurane.

We have studied the effects of magnesium on atrioventricular (AV) conduction times and surface electrocardiogram during both sinus rhythm and atrial pacing in seven dogs anaesthetized with 1 MAC of sevoflurane. A bolus dose of magnesium sulphate (MgSO4) 30, 60 and 90 mg kg-1 significantly increased plasma magnesium concentrations from 1.3 (SEM 0.1) to 15.3 (1.3) mg dl-1. MgSO4 significantly prolonged A-H (AV nodal conduction time during sinus rhythm), St-H (intra-atrial and AV nodal conduction time during atrial pacing) and H-S (total ventricular conduction time) intervals at doses > or = 30 mg kg-1 ; H-V interval (His-Purkinje conduction time) at doses > or = 60 mg kg-1; RR and PR intervals and QRS duration at doses > or = 30 mg kg-1 in a dose-related manner during both sinus rhythm and atrial pacing. QTc interval remained unchanged during sinus rhythm. The doses of MgSO4 used did not have deleterious effects on AV conduction times and surface electrocardiogram during 1 MAC of sevoflurane anaesthesia. This finding suggests that MgSO4 in high doses was safe and may be indicated for cardiac arrhythmia and hypertension during sevoflurane anaesthesia. However, further study is required to apply these findings to clinical anaesthesia.

Anesthetics, Inhalation↗
PubMed1997

The lumbar extradural structure changes with increasing age.

We have examined the extradural space using a flexible extraduroscope in 74 patients undergoing extradural anaesthesia at the L2-3 interspace. Extraduroscopy showed that the extradural space becomes widely patent and the fatty tissue in the extradural space diminishes with increasing age. We postulate that these age-related structural changes may affect the spread of local anaesthetic in the extradural space.

Adipose Tissue↗
PubMed1997

Effects of the pregnant uterus on the extradural venous plexus in the supine and lateral positions, as determined by magnetic resonance imaging.

To clarify the effects of the pregnant uterus on the extradural venous plexus in the supine and lateral positions, we studied magnetic resonance (MR) images of the lumbar spine in three parturients. T2-weighted axial MR images were obtained with the parturient in the supine and lateral positions. On each slice level in the same subject, the MR images were compared with the control MR images obtained before pregnancy. When the parturient lay supine, the pregnant uterus compressed the inferior vena cava and almost totally obstructed it; the extradural venous plexus was engorged. On turning the parturient into the lateral position, the inferior vena cava was free from compression, and the engorged extradural venous plexus was found to shrink to the level of the non-pregnant state.

Adult↗
PubMed1997

Effects of magnesium sulphate on the cardiovascular system, coronary circulation and myocardial metabolism in anaesthetized dogs.

We have studied the effects of i.v. bolus doses of magnesium sulphate (MgSO4) 60, 90 and 120 mg kg-1 on haemodynamic state, the coronary circulation and myocardial metabolism in nine dogs anaesthetized with pentobarbitone and fentanyl. MgSO4 produced dose-dependent decreases in arterial pressure, heart rate, left ventricular dP/dtmax and left ventricular minute work index (LVMWI) and an increase in the time constant of left ventricular isovolumic relaxation. Stroke volume increased, systemic vascular resistance decreased and cardiac output did not change significantly. MgSO4 produced decreases in coronary perfusion pressure, coronary vascular resistance and myocardial oxygen consumption (MVO2). Coronary sinus blood flow, lactate extraction ratio and the ratio of LVMWI to myocardial MVO2, that is an index of cardiac efficiency, did not change significantly. This study indicated that the depressant effect of MgSO4 on cardiac function was offset by lowering of peripheral vascular resistance, so that cardiac pump function remained effective, and the almost constant coronary sinus blood flow resulted from the decrease in coronary vascular resistance even at higher doses.

Animals↗
PubMed1997

Magnetic resonance imaging of the extradural space of the thoracic spine.

To clarify the anatomy of the extradural space of the thoracic spine, we have compared magnetic resonance (MR) images of the thoracic spine with those of the lumbar spine. In 20 healthy volunteers, T2-weighted axial MR images were obtained at the levels of the C7-T1, T7-8, T11-12 and L2-3 vertebrae. The posterior extradural space seen in the slice through the intervertebral disc varied in shape and size depending on the vertebral level, and the shape of the space converted from triangular to crescent-shaped on moving from the lumbar to the thoracic spine. In particular, the posterior extradural space was almost absent at the C7-T1 level, indicating that the posterior extradural fat was rudimentary or non-existent at the thoracocervical level. At this level, the dura mater seemed to be in direct contact with the ligamentum flavum. Segmentation of the posterior extradural space was commonly observed at the L2-3 and T11-12 levels; however, incomplete segmentation of the posterior extradural space was often present at the T7-8 level.

Adult↗
PubMed1997

An inhibitor of poly(adenosine 5'-diphosphoribose) synthetase, 3-aminobenzamide, does not improve cardiovascular depression, bronchospasm, or survival associated with systemic anaphylaxis in rabbits in vivo.

We investigated whether an inhibitor of poly(adenosine 5'-diphosphoribose) synthetase (PARS) is beneficial in anaphylaxis. Twenty-eight rabbits were randomly allocated to three groups: Group I (control) received .9% NaCl solution 10 min before antigen challenge followed by the infusion of the same solution. Group II (3-aminobenzamide 20 mg.kg-1) received 20 mg.kg-1 of 3-aminobenzamide (a PARS inhibitor) 10 min before antigen challenge followed by the continuous infusion of 20 mg.kg-1 of 3-aminobenzamide. Group III received 40 mg.kg-1 10 min before antigen challenge followed by the continuous infusion of 20 mg.kg-1 of 3-aminobenzamide. Survival were similar between three groups. Heart rate, mean arterial pressure (MAP), central various pressure, and pulmonary resistance did not differ between three groups. Dynamic pulmonary compliance did not differ in the early phase after the antigen challenge; however, it was significantly lower in Group III than in Groups I and II 15 min after the initiation of anaphylaxis. 3-aminobenzamide per se did not affect heart rate, MAP, central venous pressure, pulmonary resistance, or dynamic pulmonary compliance in animals without systemic anaphylaxis. In conclusion, this PARS inhibitor did not improve cardiovascular depression or bronchospasm in the early phase of systemic aggregated anaphylaxis in rabbits in vivo, implying that the pathophysiological changes associated with systemic anaphylaxis may not be related to activation of an energy-consuming DNA repair cycle triggered by PARS.

Anaphylaxis↗
PubMed1997

Relationship between pharmacokinetics and the analgesic effect of indomethacin in the rat.

The relationship between the pharmacokinetic properties and the analgesic effect of indomethacin (IDM) was evaluated on a carrageenin-induced inflammation model in the rat. Rats were administered the drug in one of two ways: intravenous (i.v.) IDM bolus or i.v. IDM infusion. The analgesic activity was measured by Randall-Selitto test. No correlation was observed between the analgesic effect and the plasma IDM concentration after i.v. bolus administration of IDM. However, in the case of infusion, IDM produced a dose-dependent analgesic effect. In this paper, we demonstrated that the plasma concentration of IDM maintained by i.v. infusion had a prolonged analgesic effect on the carrageenin-induced inflammation model.

Animals↗
PubMed1997

Random amplified polymorphic DNA analysis and variation of essential oil components of Atractylodes plants.

Total DNAs were prepared from the leaves of Atractylodes lancea DE CANDOLLE, A. chinensis KOIDZUMI, A. lancea var. simplicifolia KITAMURA, A. japonica KOIDZUMI ex KITAMURA and A. ovata DE CANDOLLE. The DNAs were subjected to random amplified polymorphic DNA (RAPD) analysis. Some primers showed the definitive polymorphic DNA patterns in A. lancea, A. japonica and A. ovata. The RAPD of A. lancea var. simplicifolia and one of A. chinensis gave similar patterns to those of A. lancea, but one of the other A. chinensis gave a similar pattern to A. japonica. Furthermore, quantitative analysis of atractylon, hinesol, beta-eudesmol and atractylodin in the rhizomes was done using gas chromatography. Though atractylon was detected not only in A. japonica and A. ovata but also in some of A. lancea, their RAPD profiles revealed the presence of intraspecific variation with A. lancea.

Chromatography, Gas↗
PubMed1997

[The spread of subarachnoid hyperbaric dibucaine in the term parturient].

To study the effect of patient's age, height, body mass index (BMI), site of injection, and volume injected on determining the spread of hyperbaric spinal anesthesia in the term parturient, we performed a retrospective analysis on 86 parturients who had received 0.3% hyperbaric dibucaine for cesarean section. All patients received subarachnoid injection of the drug in the left lateral decubitus position on a horizontal operating table. After the drug was injected, the final cephalad level of analgesia to pinprick was measured. Multiple regression analysis revealed that BMI and volume injected had relatively stronger relation with the spread of sensory analgesia, when compared to the others. However, neither of them was a significant determinant of the level of analgesia. In conclusion, patient's age, height, BMI, site of injection and volume injected were not significant determinants of hyperbaric dibucaine spinal anesthesia in the term parturient.

Anesthesia, Obstetrical↗
PubMed1997

[Prostagrandin E1-induced hypotension well maintains cerebral circulation and carbon dioxide reactivity in non-neurosurgical patients under sevoflurane-anesthesia].

To evaluate the effect of prostagrandin E1 (PGE1)-induced hypotension on cerebral blood flow (CBF) and carbon dioxide (CO2) reactivity of CBF, regional cerebral hemoglobin oxygen saturation (rSo2) was measured in non-neurosurgical patients (n = 10) under sevoflurane-anesthesia using near infrared spectroscopy. PGE1 was infused intravenously to maintain arterial pressure at a level of about 75% of the MAP (hypotensive group) under sevoflurane-anesthesia alone (normotensive group). Ventilation was controlled to adjust PaCO2 to hypocapnia (25-30 mmHg), normocapnia (35-40 mmHg) and hypercapnia (45-50 mmHg) in both normotensive and hypotensive groups. rSo2 during hypotension did not change by hypocapnia and normocapnia, but significantly increased by hypercapnia, compared with rSo2 during normotension. Significant correlations between rSo2 and PaCO2 during both normotensive and hypotensive groups were observed. Slope of the regression line of rSo2 and PaCO2 did not differ between the normotensive and hypotensive groups. When arterial oxygen content and cerebral metabolic rate of oxygen are constant, changes in rSo2 correlate with those of CBF. Therefore, CBF and CO2 reactivity of CBF that indicates autoregulation in response to changes in CO2 during hypotension were maintained as those during normotension. The results show that PGE2-induced hypotension maintains CBF and CO2 reactivity well in non-neurosurgical patients under sevoflurane anesthesia.

Adolescent↗
PubMed1997

Tec protein-tyrosine kinase is involved in the thrombopoietin/c-Mpl signaling pathway.

Thrombopoietin (TPO) is the ligand of the proto-oncogene product, c-Mpl, and supports the growth and maturation of megakaryocytic cells. Although much attention has been paid to the in vivo role of the TPO/c-Mpl system in the context of maintenance of circulating platelets, still little is understood about how activation of c-Mpl leads to mitogenesis and differentiation inside cells. Tec protein-tyrosine kinase (PTK) is the prototype of a recently emerging subfamily of nonreceptor type PTKs. Tec has been demonstrated to be activated by a wide range of cytokine stimulations. In this paper we show that TPO stimulation also rapidly enhances tyrosine-phosphorylation and activity of the Tec kinase in a human TPO-dependent cell line. In addition, the Vav protein, a blood cell-specific signaling molecule, is shown to be tyrosine-phosphorylated in response to TPO and to be constitutively associated with the Tec protein. From this evidence, we conclude that Tec is involved in the intracellular signaling system of TPO/c-Mpl.

Cell Cycle Proteins↗
PubMed1997

[Premixing lidocaine reduces the incidence and severity of pain on injection of propofol].

The purpose of this study was to confirm the effect of premixed lidocaine for the reduction of pain during injection of propofol in adult patients. We conducted a prospective, randomized, double-blind trial on 106 patients. In the study group (n = 54), lidocaine 40 mg (2 ml of lidocaine 2%) was added to 180 mg of propofol (18 ml). In the control group (n = 52), 2 ml of normal saline was added to 180 mg of propofol. The pain on injection was rated as none, mild, moderate, or severe. Eleven patients (20.4%) in the study group experienced pain compared with 25 (48.1%) in the control group. Thirteen in the control group complained moderate or severe pain compared with only one in the study group. In conclusion, lidocaine 40 mg premixed with 180 mg propofol significantly reduces the incidence and severity of pain associated with propofol injection.

Adult↗
PubMed1997

[Massive bleeding from the ruptured liver and the inferior vena cava controlled with autotransfusion and cerebral ischemia treated with mild hypothermia].

A patient suffered massive bleeding from the ruptured liver and laceration of the inferior vena cava due to traffic accident, and developed hypotension and decreased level of consciousness. The patient was transferred to our hospital for an emergency operation against intra-abdominal massive bleeding. This massive bleeding was controlled with autotransfusion using washing salvaging autotransfusion device (Cell Savor). Suspected brain ischemia was treated with intended mild hypothermia. When blood pressure decreased to 30 mmHg of systolic pressure over 7 minutes during the operation, suggesting the possible brain ischemia, mild hypothermia was maintained at 33.8 degrees C. Total bleeding volume was 16,700 ml, and total transfused volume was 10,700 ml. Of total transfused volume, 4,500 ml was washed salvaged blood using the intraoperative autotransfusion device. No neurological deficit was found during the postoperative course. The patient was discharged uneventfully on the 20th postoperative day. In conclusion, intraoperative autotransfusion with washed salvaged blood is a useful method for treatment of massive bleeding, and mild hypothermia is efficacious for protecting the brain from ischemia resulting from accidental hypotension.

Accidents, Traffic↗
PubMed1997

[Intraoperative re-rupture of gastric varix immediately after the start of an operation in a patient with liver cirrhosis].

Gastroesophageal variceal hemorrhage is a rare complication during an operation. We present a case of gastric variceal re-rupture during an emergent operation for devascularization of the gastric veins. The patient was a 72-year old man with liver cirrhosis, who developed gastric variceal hemorrhage on the day of surgery. Sclerotherapy with an endoscope was performed, and the hemorrhage was controlled four hours before entering the operating theater. The induction of anesthesia and tracheal intubation were done with rapid sequence because the patient was regarded as full stomach. Induction was completed successfully. However, gastric varix ruptured immediately after the beginning of the surgery. The hemorrhage into the stomach amounted to 2,165 ml. The patient developed hypotension of 40 mmHg of systolic pressure for 15 minutes. With fluid resuscitation, continuous infusion of dopamine and ligation of varix, the patient recovered from this hypotensive event. No neurological deficit developed postoperatively. Portal hypertension results from increased resistance to portal venous blood flow or increased portal venous blood flow. Therefore, increased intravascular volume may play a significant role in precipitating variceal hemorrhage. In this case, abrupt circulatory change due to inadequate depth of anesthesia may partly cause massive hemorrhage. In conclusion, since potential adverse effects of increased blood volume and hepatic resistance on variceal hemorrhage must be considered during anesthesia, patients with episode of variceal hemorrhage should be treated as full stomach although endoscopic findings before the surgery indicate controlled hemorrhage from varix.

Aged↗