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Biomedical subjects

T Oguchi

Publications and source records attributed to T Oguchi.

At least 91 records · Page 5Linked to original sources
PubMed1993

Three yeast genes, PIR1, PIR2 and PIR3, containing internal tandem repeats, are related to each other, and PIR1 and PIR2 are required for tolerance to heat shock.

We isolated three highly homologous genes, PIR1, PIR2 and PIR3, collectively called the PIR genes. The remarkable feature of their putative amino acid sequence is that they contain a sequence consisting of 18-19 amino acid residues repeated tandemly seven to ten times. Genes homologous to PIR were found in Kluyveromyces lactis and Zygosaccharomyces rouxii but not in Schizosaccharomyces pombe, suggesting that a set of PIR genes plays some role in budding yeast. Bias of codon usage seen in each of the PIR translation products suggests that they are expressed abundantly. The fact that disruption of each gene is viable indicates that none of them is essential. The double disruptants, pir1 pir2, were viable under various conditions, such as higher temperature (37 degrees C) or high salt concentration, but showed a slow-growing phenotype on an agar slab. Furthermore, they were sensitive to heat shock. Addition of a pir3 disruption to the pir1 pir2 double disruptant brought about no phenotypic difference from the original double mutant. PIR1 and PIR3 are closely linked to each other and are on chromosome XI.

Amino Acid Sequence↗
PubMed1993

Is pentobarbital appropriate for basal anesthesia in the working rat heart model?

In the present study we have examined the effects of the general anesthetic agents for the excision of the heart on the hemodynamic function of the ischemic perfused heart. Animals were divided into three groups. In one group rats were anesthetized with sodium pentobarbital intraperitoneally. Animals of the second and third groups were anesthetized with inhalation anesthetics, sevoflurane and isoflurane, respectively. The hearts were then rapidly excised and perfused by a working heart model. After control perfusion, whole-heart ischemia was induced by one-way aortic valve for 15 min followed by reperfusion for 30 min. During preischemic control period, cardiac output (CO) and left ventricular dP/dT maximum (LV dP/dT max) in the isoflurane group were significantly higher than those in the pentobarbital group. During reperfusion, CO and LV dP/dT max in the isoflurane and sevoflurane groups recovered more rapidly than those in the pentobarbital group. Although there were no significant differences in myocardial ATP and glycogen levels among the groups, myocardial lactate in the pentobarbital group was significantly higher than those in the sevoflurane and isoflurane groups. These results suggest that intraperitoneal pentobarbital anesthesia, administered prior to heart excision, may affect the performance of the ischemic perfused heart thereafter. Therefore, we would suggest that isolation of hearts by means of inhalation anesthesia is better than by means of pentobarbital in the working rat heart.

Administration, Inhalation↗
PubMed1992

Effects of propafenone on function and metabolism in the ischemic working rat heart.

We examined the effects of propafenone, a new anti-dysrhythmic agent, on myocardial function and metabolism in ischemic working rat heart preparations. In the treated hearts, propafenone, 0.3 micrograms/ml and 3 micrograms/ml, were added to Krebs-Henseleit bicarbonate buffer perfusate throughout the experiments. Whole heart ischemia was induced through a one-way aortic valve for 15 min followed by 'reperfusion for 30 min. After induction of ischemia, the cardiac output, peak aortic systolic pressure, left ventricular dP/dtmax, and myocardial ATP concentration were greater in the treated hearts than in the untreated ones. All hearts in the untreated group developed ventricular fibrillation (Vf) at the beginning of the reperfusion period. On the other hand, no treated hearts had Vf at any time during the experiment. However, propafenone, 3 micrograms/ml, evoked a negative inotropic effect before and after ischemia. These results indicate that propafenone may contribute to early recovery from ischemia in myocardial function and metabolism, although it has a negative inotropic action.

Adenosine Triphosphate↗
PubMed1992

Effects of prostacyclin analogue, OP-2507, on function and metabolism in the ischemic working rat heart.

We examined the effects of a new stable prostacyclin analogue, OP-2507, on myocardial function and metabolism in the ischemic working rat heart preparation. The hearts were perfused with Krebs-Henseleit bicarbonate (KHB) buffer, and whole heart ischemia was induced by one-way aortic valve for 15 min follows by reperfusion for 30 min. In the treated hearts, OP-2507, 20 ng.ml(-1), was administered to KHB buffer from the beginning to the end of experiment. During ischemia, coronary flow in the OP-2507 group increased significantly more than that in the control group. The mechanical performance of both groups was impaired after ischemia. However, the recovery of coronary flow, cardiac output, peak systolic pressure and LV dP/dT(max) was significantly higher in the treated group than in the control group. The incidence of ventricular fibrillation during reperfusion was 100% and 25% in the control and the OP-2507 groups, respectively. Myocardial ATP content was significantly higher in the treated hearts than that in the control hearts. These results indicate that this stable prostacyclin analogue is beneficial in myocardial ischemia, even without its well known action of preventing platelet aggregation.

Journal Article↗
PubMed1991

Protective effects of prostaglandin I2 analogues on CPK release in rat's heart-lung preparation.

The effects of prostaglandin I(2) analogues (PGI(2)-a: op-41483 and op-2507) on oxygen toxicity during hyperoxic perfusion were evaluated in an experiment on isolated rat heart lung preparation, with the release of creatine phosphokinase (CPK) in the perfusate blood. There were no significant differences in heart rate and right atrial pressure between PGI(2)-a treated and untreated hearts. The CPK release from the heart with oxygen was significantly higher than that of the air ( P < 0.001). However, the CPK release from the PGI(2)-a treated hearts was significantly less than that from the untreated hearts ( P < 0.05). These results indicate that PGI(2)-a may prevent cell damage which was induced by hyperoxia.

Journal Article↗
PubMed1991

Functional and metabolic effects of propafenone in the rat heart-lung preparation.

The effects of propafenone on cardiac function and myocardial metabolism were assessed in the isolated rat heart-lung preparation. Propafenone 0.3, 3 or 30 microg.ml(-1) was administered 5 min after the start of perfusion. Heart rate decreased in the 30 microg.ml(-1) group significantly following the drug administration. The highest dose of propafenone (30 microg.ml(-1)) reduced cardiac output significantly, and this dose was associated with a higher incidence of arrhythmias than the other groups. Although there were no significant differences in myocardial lactate and glycogen concentrations among groups, ATP content in the 30 microg.ml(-1) group was significantly less than that in the control group. As therapeutic plasma concentration of propafenone is about 0.6 (range 0.06 to 1.0) microg.ml(-1), 30 microg.ml(-1) is 50 times greater than its concentration. These results suggest that the negative inotropic and chronotropic effects of propafenone are almost same with those of lidocaine which we have previously reported.

Journal Article↗
PubMed1991

[Epidural anesthesia with high dose fentanyl for thoracic surgeries].

Twenty-two elective thoracic surgeries were performed under epidural high dose fentanyl anesthesia. These included 11 mastectomies, 3 lung lobectomies, and 8 operations for esophageal carcinoma. Through an epidural catheter, 10 micrograms.kg-1 fentanyl with [E (+)] or without [E (-)] epinephrine (1: 100,000) was given. N2O (66%) and enflurane (0.2-0.8%) were also administered, and muscle relaxants were given as needed. The onset and duration of the action were approximately 20 minutes and 3 hours, respectively. Anesthesia was maintained with enflurane (up to 0.4%) in 17 patients (77.3%). There were no differences between the E (+) group and the E (-) group. Systolic pressure, diastolic pressure and heart rate during operations were about 30% lower than those observed before the operations. Patients recovered from anesthesia rapidly. Naloxone was administered intravenously in 6 patients after mastectomies or lung lobectomies (42.9%), whose respiratory rate was below 10.min-1. The patients with short operating time (shorter than 2 hours) needed more naloxone. Troubles did not occur either in the recovery room or in the ward with both naloxone and non-naloxone groups.

Adult↗
PubMed1991

Anaesthetic management of dilated cardiomyopathy with severe ventricular dysrhythmias.

A 67-year-old man with dilated cardiomyopathy underwent subtotal gastrectomy. The risks due to anaesthesia and surgery were considered to be very high because of the severe dysrhythmias and renal dysfunction. Anaesthesia was induced with fentanyl and midazolam and maintained with additional fentanyl, midazolam, and 60% nitrous oxide. Dobutamine, dopamine, lignocaine and a temporary pacemaker were used to control cardiovascular responses during surgery. Mild hypotension and tachycardia occurred, but neither circulatory failure nor other major complications were observed during and after the operation.

Aged↗
PubMed1990

Interaction between calcium channel blockers and volatile anaesthetics in the rat heart-lung preparation.

We have studied the effects of the calcium channel blockers verapamil, diltiazem and nifedipine and the volatile anaesthetics halothane, enflurane and isoflurane on myocardial metabolism after postischaemic reperfusion in the rat isolated heart-lung preparation. In the presence of the volatile anaesthetics, the preparations were perfused for 10 min, made globally ischaemic for 8 min, and then reperfused for 10 min. Each of the calcium blockers was administered 5 min before ischaemia. Three hearts in the halothane-verapamil group (n = 10) failed to recover from the ischaemia and the recovery time in the same group was significantly longer than in the enflurane-verapamil or isoflurane-verapamil groups. Although there was no significant difference in myocardial lactate concentrations among the groups, ATP and glycogen contents in the halothane-verapamil group were significantly less than those in the other groups. The results suggest that the combination of halothane and verapamil causes significant myocardial depression during recovery from ischaemia and subsequent metabolic deterioration.

Anesthetics↗
PubMed1990

Prevalence of anti-HCV antibody in blood donors in the Tokyo area.

Prospective studies of posttransfusion hepatitis carried out in the past decade showed that 18.1% of the blood transfusions resulted in non-A non-B hepatitis in Japan. As an approach to the prevention of posttransfusion non-A non-B hepatitis (PTNANB), anti-hepatitis C virus (HCV) positivity was measured in 2,970 blood donations in the Tokyo area, and in 200 children aged between 6 and 15 years. Thirty-four cases were anti-HCV-positive, showing an overall positivity of 1.14%. None of the 200 children younger than 15 years old were positive. Correlation of anti-HCV positivity with the serum ALT levels was observed, but by reducing the accepted ALT levels from 35 Karmen Units (KU) down to 25 KU, it is estimated that 62.5% of the observed PTNANB would still have occurred, and 5.1% of the donated blood could not be used for transfusion. On the other hand, it is estimated that the majority of PTNANB could be prevented, with the loss of 1.14% of donated blood units, using the anti-HCV screening test.

Adolescent↗