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Biomedical subjects

R Shimizu

Publications and source records attributed to R Shimizu.

At least 253 records · Page 14Linked to original sources
PubMed1989

[Effects of acute hypoxia on cardiovascular dynamics, myocardial metabolism and ECG in dogs].

In pentobarbital-pancuronium anesthetized open chest dogs, left ventricular pressure (LVP), first derivative of LVP (dp/dt) and left ventricular end-diastolic pressure (LVEDP) were measured by a micromanometer tipped catheter, stroke volume and cardiac output (CO) by an electromagnetic flow meter and coronary sinus blood flow (CSBF), by a thermal dilution catheter, respectively. Mean arterial pressure (mAP), mean pulmonary arterial pressure (mPAP), lead II of ECG and esophageal temperature were monitored. Blood gas, catecholamines and lactate of arterial blood and coronary sinus blood were measured and myocardial lactate extraction ratio (MCL) was calculated. As an index of contraction, maximum positive dp/dt (+dp/dt max), and as an index of relaxation, the time constant (T) of isovolumic left ventricular pressure fall were employed, respectively. Acute hypoxia was induced by the inhalation of a 5% O2-95% N2 gas mixture and arterial blood oxygen pressure was maintained between 15 and 20 mmHg. Along with the advancement of hypoxia, +dp/dt max, CO and mAP gradually increased and peaked in 5 minutes. Thereafter, these parameters began to decrease and CO fell to zero in 20 minutes. mPAP and HR slowly increased and peaked in 9 and in 12 minutes, respectively. T was progressively prolonged throughout the hypoxia. CSBF/CO ratio was increased and stayed at a high level even after CO began to decrease. MCL decreased and changed from positive values to negative ones in 5 minutes. Epinephrine and norephinephrine concentrations slowly increased and peaked in 16 minutes. A gradual decrease in the R wave, shortening of the R-R interval and lengthening of the QTc interval were observed in ECG. This study indicated that the left ventricular relaxing function was impaired earlier than contracting function by acute hypoxia and that conversion of the augmented left ventricular contractile state to the depressed one coincided with conversion of myocardial lactate extraction to its production.

Acute Disease↗
PubMed1989

[Three cases of thyroid cancer, including a component of squamous cell carcinoma].

A squamous cell carcinoma of the thyroid gland is rare and its prognosis is poor. Three cases of a rare thyroid cancer are reported, the first case being an adenosquamous cell carcinoma of a 75-year-old male and the second case being a pure squamous cell carcinoma of a 64-year-old male. These two cases were pathologically diagnosed on autopsy. The overall duration of these two cases was 6 months. The third case involved a 62-year-old male. His pathological diagnosis was a mixed squamous cell carcinoma and an undifferentiated carcinoma. Postoperatively 50 Gy of irradiation was performed. This patient is still alive and has shown no evidence of recurrence for 16 months.

Adenocarcinoma↗
PubMed1988

The distance from the skin to the epidural space.

To determine whether there is any systemic relationship between the distance from the skin to the epidural space and physical constitution, the distance from the skin to the epidural space was measured in 1007 epidural punctures. The distance from the skin to the epidural space in male was greater than that in female ( P << 0.001). However, the analysis of the distance from the skin to the epidural space of the selected patients who had both a weight of 50-60 kg and a height of 1.5-1.7 m indicated no statistical difference between male and female. The best correlation was found between the distance from the skin to the epidural space and body weight. The correlation between the distance from the skin to the epidural space and height was less striking. Ninety-five percent of the patients who received epidural puncture at the thoraco-cervical area (C7-T2) had a distance to the epidural space of 4.0-6.9 cm; 87% at the lower-thoracic area (T8-T10), 4.0-6.9 cm; 93% at the thoraco-lumbar area (T12-L2), 3.0-4.9 cm; 85% at the mid-lumbar area (L2-L4), 3.0-4.9 cm. These results may be useful for young anesthesiologists to master epidural block safely and efficiently.

Journal Article↗
PubMed1988

Effects of sevoflurane on cardiovascular dynamics, coronary circulation and myocardial metabolism in dogs.

The effects of 2.5% and 5% of sevoflurane anesthesia on hemodynamics and myocardial metabolism were studied in pentobarbital-pancuronium anesthetized dogs. The interaction between nicardipine and 2.5% sevoflurane was also examined. Sevoflurane produced dose-dependent ( P << 0.05 to P << 0.01) decreases in systolic arterial pressure (SAP), heart rate (HR), cardiac index (CI), left ventricular minute work index (LVMWI), maximum rate of rise of left ventricular pressure (LV dP/dt), the time constant of fall in isovolumic left ventricular pressure (T) and systemic vascular resistance (SVR), whereas stroke volume index (SVI) and left ventricular end-diastolic pressure (LVEDP) remained unchanged. Central venous pressure (CVP) was significantly ( P << 0.05) increased at 5%. Myocardial oxygen consumption (MV(O)(2)), and myocardial lactate extraction ratio (ML ext) were decreased in a dose-dependent manner ( P << 0.05). Myocardial oxygen extraction ratio (M(O)(2) ext) was significantly ( P << 0.01) decreased at 5%. The ratio of the left ventricular minute work index to myocardial oxygen consumption (LVMWI/MV(O)(2)), i.e., left ventricular efficiency was significantly decreased only at 5% ( P << 0.05). Coronary sinus blood flow (CSBF) was significantly ( P << 0.05) decreased only at 2.5% sevoflurane and coronary vascular resistance (CVR) was significantly ( P << 0.01) decreased only at 5% sevoflurane. The ratio of CSBF to CO (CSBF/CO) showed a tendency to increase as sevoflurane concentrations were increased. Nicardipine (0.01 mg.kg(-1)) administered intravenously under 2.5% sevoflurane caused significant ( P << 0.05 to P << 0.01) decreases in SAP, HR, LV dP/dt, SVR, and CVR, and increases in CVP, SVI, CI, and CSBF ( P << 0.05 to P << 0.01). CSBF/CO remained unchanged. MV(O)(2), M(O)(2) ext, and ML ext were significantly ( P << 0.05 to P << 0.01) decreased. LVMWI/MV(O)(2) showed a tendency to increase. It is concluded that sevoflurane causes a rapidly and easily controlled cardiovascular depression and may not have unfavorable effects on coronary circulation and myocardial metabolism. Nicardipine exerts a synergistic myocardial depressant effect on sevoflurane, in terms of both cardiovascular dynamics and myocardial metabolism.

Journal Article↗
PubMed1988

Incorporation of partially purified cation channels from cardiac sarcolemmal membrane into planar lipid bilayers.

Voltage-dependent calcium channels are vital to cardiac muscle contraction. Therefore it is very important to isolate physiologically active channel proteins, however there have been few reports on their solubilization and reconstitution. Highly purified sarcolemmal membranes from bovine cardiac muscle were solubilized with octylglucoside, partially purified by gel filtration, and reconstituted into planar lipid bilayer by the direct insertion method. At least, two cation channel activities were observed: one with about 4.2 pS and the other with about 28 pS in conductance. From the reversal potential, it was concluded that Ba2+ ions are the current carrier through these two channels.

Animals↗
PubMed1988

Analgesic dose-response relation in cervical epidural block.

The relationship between the age and the spread of analgesia from different epidural anesthetic doses was examined by studying analgesic dose responses in cervical epidural analgesia. Two different anesthetic doses (5 ml or 10 ml) of 2% mepivacaine were injected into the cervical epidural space at a constant pressure (80 mmHg) using an intravenous apparatus, and the spread of analgesia to pinprick was assessed. The significant correlation was found between the patient's age and the number of spinal segments blocked (5 ml : r = 0.8498, P < 0.01, 10 ml : r = 0.5988, P < 0.01). The inverse linear relationship was found between the patient's age and the segmental dose requirement (5 ml : r = -0.6754, P < 0.01, 10 ml : r = -0.5784, P < 0.01). Patients under 39 years of age showed a direct relationship between the dose injected and the number of spinal segments blocked, enabling prediction of the number of segments blocked with a given dose of local anesthetic. Doubling the epidural dose approximately doubled the number of spinal segments blocked. The analgesic dose-response relation in patients over 60 years of age differed from that in patients under 39 years of age and doubling the epidural dose did not double the number of spinal segments blocked. Progressively more extensive analgesia was obtained from a given dose of local anesthetic with advancing age. It was difficult to limit the extent of analgesia by injecting a smaller dose of local anaesthetic in the elderly.

Journal Article↗
PubMed1988

The effect of verapamil on halothane-epinephrine or digitalis-induced ventricular dysrhythmias in dogs.

The effect of verapamil on ventricular dysrhythmias was evaluated using two canine models. In one model, ventricular dysrhythmias were induced by 1% halothane-epinephrine (1.5 approximately 30 micro g/kg/min.) in 20 dogs (Group I). In the other model, ventricular dysrhythmias were induced by digoxin (0.1 approximately 0.2 mg/kg) in 27 dogs (Group II). Verapamil (0.2 approximately 0.5 mg/kg) was given to treat these ventricular dysrhythmias. When verapamil was ineffective, lidocaine (1 approximately 2 mg/kg) was given following the administration of verapamil. In 7 dogs of group II, lidocaine alone was given. Verapamil was effective in 16 animals of group I, and in 10 animals of group II. Lidocaine was ineffective in the remaining 4 of group I, whereas effective in the remaining 17, including those given lidocaine alone of group II. From these findings, it was inferred that Ca(2+) dependent abnormal automaticity and/or re-entry may be more closely related to the genesis of halothane-epinephrine-induced ventricular dysrhythmias refractory to lidocaine, whereas triggered activity may be more closely related to that of digitalis-induced ventricular dysrhythmias. In conclusion, verapamil was more effective against halothane-epinephrine-induced ventricular dysrhythmias than against digitalis-induced ventricular dysrhythmias.

Journal Article↗
PubMed1988

Site-specific mutagenesis of the human interleukin-1 beta gene: the role of arginine residue at the N-terminal region.

Using the expression system for site-specific mutagenesis in Escherichia coli, we have made deletion mutants at the N-terminal or C-terminal region of human interleukin-1 beta (IL-1 beta) consisting of 153 amino acids. The truncated mutants showed that at least 147 amino acids (numbers 4-150) in IL-1 beta are necessary for the exertion of biological activity. When we changed the arginine at the 4th position (Arg4) in IL-1 beta to other specific amino acids, there was a marked difference in the relative extent of biological and receptor binding activities among the mutants. The order of the mutants was Arg4 = Lys4 greater than Gln4 greater than Gly4 = des-Arg4 greater than Asp4. Our results demonstrate that the arginine residue at the 4th position in IL-1 beta is important, but not essential, for IL-1 beta to exhibit its biological and receptor binding activities, and the positive charge at this site plays a key role for IL-1 beta to exert the activities.

Arginine↗
PubMed1988

[Transfer of cefuzonam into female genital organs].

Cefuzonam (CZON) was given intravenously at a 1 gram dose to 24 patients prior to abdominal total hysterectomy for uterine myoma. Concentrations of CZON in the serum of cubital vein, uterine artery, and in tissues of uterus and adnexa uteri were measured by the bioassay method. Bilateral uterine arteries were clamped at 15 and 30 minutes and 1, 2, 4 and 6 hours after the administrations of the drug. Measurements were done on 4 patients at each sampling. Concentrations of CZON in the serum of cubital vein and uterine artery changed in a similar manner with respective half-lives of 52.0 minutes and 48.2 minutes. Peak concentrations in oviduct, ovary, endometrium, myometrium, cervix uteri and portio vaginalis were reached at 15 minutes after drug administration. The peak concentration in the ovary was as high as 37.5 micrograms/g, and those in other tissues varied between 17.6 and 25.5 micrograms/g. Tissue concentrations decreased gradually after their peaks in similar manners to those in serum, and their half-lives ranged between 37.4 and 53.7 minutes. From these results, it was found that CZON was transferred to female genital organs in high enough concentrations to inhibit growth of bacteria which were often isolated from the pelvic inflammatory diseases, and CZON seemed to be highly effective to clinical pelvic inflammatory diseases.

Adnexa Uteri↗
PubMed1987

Epidural pressure and its relation to spread of epidural analgesia.

The relationships between the epidural pressures following the injection of local anesthetic solution and the spread of epidural analgesia were investigated. In 46 patients, 15 ml of 2% mepivacaine was injected into the lumbar epidural space at a constant rate (1 ml/sec) using an electropowered syringe pump. Injection pressures and residual pressures were recorded and the spread of analgesia to pinprick was assessed. The changes of the epidural pressures during and following the injection of a volume of local anesthetic solution in old subjects were significantly smaller than those in young subjects (P < 0.05). The spread of analgesia closely correlated with the epidural pressures during and following the injection of local anesthetic solution. The most close correlation was found between the epidural pressure immediately after the completion of injection and the spread of analgesia (r = -0.5659, P < 0.001). In conclusion, the lower the terminal injection pressure and the residual pressures associated with higher age, the wider the spread of epidural analgesia.

Journal Article↗