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Biomedical subjects

J Nejima

Publications and source records attributed to J Nejima.

36 records · Page 2Linked to original sources
PubMed1995

[Superselective local infusion therapy with tissue-plasminogen activator for acute massive pulmonary thromboembolism: preliminary clinical experience].

Three cases of acute massive pulmonary thromboembolism were treated with the superselective infusion of tissue-plasminogen activator. Superselective pulmonary angiography immediately after administration of tissue-plasminogen activator demonstrated angiographic improvement in all patients. No complications were encountered during or after the procedure. It is considered that superselective infusion of tissue-plasminogen activator can be an effective therapy for massive pulmonary thromboembolism.

Acute Disease↗
PubMed1991

[Regional myocardial blood flow measurement with radioactive microspheres in dogs with myocardial ischemia].

In order to evaluate the radioactive microsphere technique used in our laboratory for measuring regional myocardial blood flow (RMBF) in dogs with myocardial ischemia, simultaneous blood flow measurements with three different nuclide (141Ce, 51Cr or 113Sn)-labeled microspheres were performed after coronary artery occlusion. There were excellent correlations between all paired RMBF values in 80 samples. The linear regression lines were expressed as: 51Cr = 1.09x 141Ce-0.02 (r = 0.996, SEE = 0.06); 113Sn = 0.99x 141Ce + 0.01 (r = 0.997, SEE = 0.05); 113Sn = 0.90x 51Cr + 0.03 (r = 0.991, SEE = 0.08). The duplicate variability ranged from 5.5 +/- 0.7 to 9.9 +/- 1.1%. When RMBF was measured before and after intravenous administration of nipradilol (0.2 mg/kg), a new beta-blocker, in a dog with myocardial ischemia, RMBF fell in the normal zone (23.6 +/- 1.6%), and did not change in the severely ischemic zone. Thus, this study demonstrated that RMBF can be measured accurately and repeatedly with radioactive microspheres in dogs with regional myocardial ischemia.

Adrenergic beta-Antagonists↗
PubMed1991

[Clinical features and treatment of ventricular tachycardia associated with acute myocardial infarction].

Three hundred and ninety-two consecutive patients with acute myocardial infarction (AMI) were studied to delineate the clinical features of ventricular tachycardia (VT) (three or more VPC). The incidence of VT in AMI was 23.5% and was higher in inferior AMI (29.8%) than in anterior AMI (19.3%) (p less than 0.05). The incidence of ventricular fibrillation (VF) and mortality were higher in the VT group than in the non-VT group. VT was most frequent on the first day after the onset of AMI. However, another peak of the occurrence of VT was observed in the 4th week after AMI in the anterior AMI group, but not in the inferior AMI group. The late-onset VT had a rapid heart rate during the VT attack (209 +/- 42 vs 170 +/- 62 beats/min, p less than 0.05) which frequently developed to VF (20.9 vs 8.4%, p less than 0.05). This was associated with severe heart failure and indicated a poor prognosis (mortality; 75.0 vs 24.2%, p less than 0.01), when compared with VT that occurred in the early period after the onset of AMI. The effectiveness of the thump-version for the termination of VT was 60.9%. Lidocaine was effective at 57.1%.

Aged↗
PubMed1990

Role of intact cardiac nerves and reflex mechanisms in desensitization to catecholamines in conscious dogs.

To study chronic catecholamine desensitization, mini-osmotic pumps were implanted subcutaneously to deliver NE, (0.5 micrograms/kg/min) or saline over 3-4 wk in dogs instrumented with left ventricular (LV) pressure gauges and arterial and left atrial pressure catheters. An acute challenge to NE (0.4 micrograms/kg/min) in intact, conscious dogs increased LV dP/dt by 1,531 +/- 208 mmHg/s before NE pumps, and by a similar amount, 1,340 +/- 166 mmHg/s, 3-4 wk after NE pumps. In contrast, an acute challenge to isoproterenol (ISO, 0.4 micrograms/kg/min) increased LV dP/dt by 5,344 +/- 532 mmHg/s before NE pumps, and significantly less (P less than 0.05; 2,425 +/- 175 mmHg/s) after NE pumps. In the presence of ganglionic and alpha 1-adrenergic blockades, NE (0.4 micrograms/kg/min) increased LV dP/dt by 3,656 +/- 468 mmHg/s before NE pumps and significantly less (P less than 0.01; 1,459 +/- 200 mmHg/s) after NE pumps. Confirming this, an acute challenge to NE (0.4 micrograms/kg/min) in dogs with arterial baroreceptor denervation increased LV dP/dt by 3,732 +/- 896 mmHg/s before NE pumps, and significantly less (P less than 0.05, 1,725 +/- 408 mmHg/s) after NE pumps. In addition, in cardiac denervated dogs, NE (0.4 micrograms/kg/min) increased LV dP/dt by 9,901 +/- 1,404 mmHg/s before NE pumps and significantly less (P less than 0.01, 2,690 +/- 306 mmHg/s) after NE pumps. Desensitization of heart rate responses to NE challenge was also more apparent in the absence of reflex mechanisms. Thus, neural reflex mechanisms play a major role in physiological expression of cardiac desensitization to catecholamines in conscious dogs.

Animals↗
PubMed1989

Increased myocardial infarct size because of reduced coronary collateral blood flow in beagles.

Effects of permanent left circumflex coronary artery occlusion (CAO) were examined in conscious purebred beagles and mongrel dogs, instrumented with miniature left ventricular (LV) pressure gauges, wall thickness gauges in the ischemic zone, catheters in left atrium and aorta, and snares around the left circumflex coronary artery. Blood flow was measured using the radioactive microsphere technique before CAO and at 5 min, 1, 3, and 24 h after CAO. Although CAO reduced myocardial blood flow similarly in beagles and mongrels, significantly less (P less than 0.05) recovery of myocardial blood flow was observed over the following 24-h period in beagles. Infarct size, as determined by triphenyltetrazolium chloride and expressed as percentage of area at risk, was larger (P less than 0.05) in beagles (62.0 +/- 5.1%) than mongrels (42.5 +/- 4.2%). Thus beagles do not tolerate ischemia as well as mongrel dogs and possess fewer functional coronary collaterals resulting in larger infarcts after CAO.

Animals↗
PubMed1989

Superoxide dismutase reduces reperfusion arrhythmias but fails to salvage regional function or myocardium at risk in conscious dogs.

To determine if oxygen free radical scavengers administered before coronary artery reperfusion can limit reperfusion arrhythmias, increase the return of regional function in ischemic myocardium, and reduce tissue necrosis at 1 week after 90-minute coronary artery occlusion and reperfusion, conscious dogs were treated with superoxide dismutase (SOD) and catalase before and for 1 hour after coronary artery reperfusion. Another group was treated with recombinant SOD (rSOD) because the commercially available SOD and catalase contained endotoxin. The conscious dogs were studied 3-4 weeks after implanting left ventricular pressure gauges, ultrasonic wall thickness gauges in the posterior left ventricular wall, left atrial catheters, and arterial catheters, Doppler flow transducers, and hydraulic occluders on the left circumflex coronary artery. The only beneficial effect observed was that the number of arrhythmic beats per minute in the rSOD-treated group was significantly lower (p less than 0.05) when compared with a control group after coronary artery reperfusion. Treatment neither increased the amount of recovery of wall thickening in the ischemic zone nor reduced infarct size when expressed either as a percentage of the area at risk or as a function of collateral blood flow in the ischemic zone. For example, infarct size as a percentage of the area at risk was 32.6 +/- 5.8%, 37.4 +/- 6.4%, 28.3 +/- 5.1% in the control, SOD and catalase-, and rSOD-treated groups, respectively. Thus, although treatment with oxygen free radical scavengers invoked a transient reduction in the number of reperfusion arrhythmias, this treatment in conscious dogs failed to improve regional myocardial dysfunction or reduce the amount of necrosis when compared with a control group. The lack of a sustained salutary effect may indicate that longer periods of treatment with free radical scavengers are required in chronic preparations.

Animals↗
PubMed1989

Chronic norepinephrine elicits desensitization by uncoupling the beta-receptor.

The goal of this study was to determine the mechanism of beta-adrenergic receptor desensitization after chronic elevation of circulating NE levels. Osmotic minipumps containing either NE or saline were implanted subcutaneously in dogs for 3-4 wk. Physiologic desensitization to isoproterenol was confirmed in conscious dogs, i.e., left ventricular dP/dt increased in response to isoproterenol (0.4 micrograms/kg per min) by 5,625 +/- 731 mmHg/s in control dogs with saline pumps, and significantly less, P less than 0.01, by 2,093 +/- 263 mmHg/s in dogs with NE pumps. Myocardial beta-adrenergic receptor density as determined with 125I-cyanopindolol binding was 49% higher (p less than 0.05) in the NE pump group. However, beta-adrenergic receptor agonist binding with isoproterenol demonstrated a significant shift into the low affinity state for the animals with NE pumps. Basal, GTP plus isoproterenol, 5'-guanylylimidodiphosphate, sodium fluoride, and forskolin-stimulated adenylate cyclase activity in the NE pump group were significantly depressed (P less than 0.05) by amounts ranging from 20 to 40%. The functional activity of the guanine nucleotide binding protein Gs was also reduced (P less than 0.05) in animals with NE pumps. Thus, the process of desensitization in response to chronic elevation of NE levels in intact, normal dogs does not involve a decrease in beta-adrenergic receptor density. Rather, it is characterized by reduced adenylate cyclase activation and uncoupling of the beta-adrenergic receptor in association with decreased activity of the GTP-coupling protein Gs.

Adenylyl Cyclases↗
PubMed1989

Characteristics of symptomatic and asymptomatic myocardial ischemia during ambulatory electrocardiographic monitoring in patients with angina pectoris.

The purpose of the present study was to clarify the characteristics of myocardial ischemic attacks in patients with exertional angina (EA, 56 cases), exertional and rest angina (ERA, 28 cases), rest angina (RA, 4 cases), and variant angina (VA, 39 cases). The Holter electrocardiographic findings were compared among the four types of angina pectoris. The frequency of symptomatic ischemic attacks in descending order was 46.0% in EA, 29.0% in ERA, 28.1% in RA, and 21.6% in VA, while the frequency of asymptomatic ischemic attacks was in the reverse order. The maximal heart rates during symptomatic ischemic attacks were in descending order, EA, ERA, RA, and VA. The maximal heart rate during ischemic attacks was significantly lower in patients with spontaneous angina than in those with exercise-induced ischemia for all types of angina (p less than 0.05, respectively). Further, the difference in maximal heart rate during ischemic attacks between the ambulatory electrocardiogram and exercise test was greater in patients with RA and VA than in those with EA. Therefore, this suggests that increased coronary vascular tone is a cause of spontaneous ischemic attacks in each type of angina pectoris.

Aged↗
PubMed1988

Reduction of size of myocardial infarction with nicorandil, a new antianginal drug, after coronary artery occlusion in dogs.

The effects of nicorandil, a new antianginal drug, on size of myocardial infarction were studied in anesthetized, open-chest dogs after left anterior descending coronary artery occlusion. To quantify the extent of the hypoperfused zone, 99mTc-albumin microspheres were injected into the left atrium 1 min after occlusion. Fifteen minutes after occlusion, dogs were randomly assigned to a control group or a nicorandil-treated group that received immediately after assignments 100 micrograms/kg of nicorandil followed by a continuous infusion of 30 micrograms/kg/min for 6 h. Six hours after occlusion, the left ventricle was cut into 3 mm thick slices for triphenyltetrazolium chloride staining and autoradiography. The extent of the hypoperfused zone (26.1% +/- 3.1% of the left ventricle in the control vs. 23.2% +/- 3.7% in the treated group, mean +/- SEM) was not different between the two groups. The ratio of the extent of myocardial necrosis to the extent of the hypoperfused zone was significantly smaller in the treated group (64.3% +/- 7.2%, n = 7, p less than 0.05) than in the control group (92.6% +/- 9.2%, n = 7). Thus, nicorandil administered early after coronary artery occlusion reduced the size of myocardial infarction by 31%.

Animals↗
PubMed1988

Evaluation of a new antianginal agent, nipradilol, in effort angina using holter monitoring.

The purpose of this study was to investigate the efficacy, effective dose, administration frequency and antianginal effect of a new antianginal agent, nipradilol, in 12 patients with stable effort angina. A single blind design was employed; the test consisted of an observation period (1 week) and a treatment period (1-2 weeks). Twenty four hour Holter monitoring was performed on the penultimate day of each period. Nipradilol was administered twice a day at a daily dose of 3-12 mg (mean 7.9 +/- 3.3 mg). The mean frequency of ST-segment depression was 7.1 +/- 6.7 times per day at baseline and 3.1 +/- 2.7 after drug administration, showing a significant reduction (p less than 0.05). The suppression of ST-segment depression and decrease in heart rate due to this drug persisted for 12 hours following administration. The plasma drug concentration at a daily dose of 12 mg peaked at 9.5 +/- 2.4 ng/ml 1 hour after administration and the 12 hour value was 2.3 +/- 1.2 ng/ml. No side effects were observed. Therefore, it seems that, when administered twice a day (total daily dose 6 mg) this drug is effective in effort angina and that the antianginal effect is mainly attributable to beta-adrenoceptor blockade.

Adrenergic alpha-Antagonists↗
PubMed1987

Prognosis of patients with persistent negative U wave following myocardial infarction.

In order to clarify the clinical significance of a persistent negative U wave in patients with myocardial infarction, the clinical features and prognosis of a group of such patients were compared with a group without negative U waves. The persistent negative U wave was defined as the presence of a negative U wave at the time of discharge. The subjects were classified into 2 groups: group A--55 patients (50 males and 5 females, 59 +/- 10 years) with negative U waves; group B--70 patients (55 males and 15 females, 61 +/- 9 years) without negative U waves. The average follow-up periods were 49 +/- 21 months in group A and 42 +/- 18 months in group B. Negative U waves appeared in leads where r or R waves were present, but were not observed in leads with a QS pattern. The incidences of a diseased left anterior descending artery, multi-vessel disease, left ventricular wall motion abnormality and left ventricular ejection fraction below 50% were higher in group A than in group B. The recurrence of myocardial infarction was 18.2% in group A and 7.1% in group B, and the number of patients treated with antianginal drugs was higher in group A than in group B. The rate of recurrence of myocardial infarction at 1, 3 and 5 years was 6%, 17% and 26%, respectively in group A and 6%, 8% and 11%, respectively in group B. Thus, it was concluded that patients in group A require more active treatment than those in group B.

Adult↗
PubMed1987

Factors influencing the clinical course and the long-term prognosis of patients with variant angina.

The purpose of this study was to clarify the factors influencing the clinical course and prognosis in variant angina. Also, the mechanism of acute myocardial infarction in variant angina is reviewed. The subjects were 110 patients with variant angina who, after the initial visit or admission, were observed for a period of at least 2 months, the average observation period being 68 +/- 49 months (range: 2 months-16 years). The incidence of acute myocardial infarction was 21.8% of these patients and 87.5% of the infarctions occurred within 1 month of the initial visit or admission. In variant angina, the average rate over 1 year was 2.2%; however, in classical angina the rate was 3.7% and in postinfarction angina 5.0%. The mortality rate was 5.5%, with death in the majority of cases occurring within 1 month, as in myocardial infarction. When treatment was stopped, spontaneous remission occurred in at least 26 of the 110 cases (23.6%). Beyond 3 months, the remission continued in 19 of these 26 cases. Seven cases had acute myocardial infarction in spite of the suppression of anginal attacks with administration of calcium antagonists. Apparently coronary spasm is the cause of anginal attacks, and the cause of acute myocardial infarction in patients with variant angina appears to be coronary thrombus formation.

Adult↗
PubMed1986

Comparative effects of nicardipine, a new calcium antagonist, on size of myocardial infarction after coronary artery occlusion in dogs.

To examine whether nicardipine, a dihydropyridine derivative, limits size of myocardial infarction, and to compare the protective effects of nicardipine administered before and early and late after coronary artery occlusion, 99mTc-labeled albumin microspheres were injected into the left atrium during 5 min temporary coronary artery occlusion to determine the extent of the hypoperfused zone (the area at risk). The coronary arteries were then reperfused for 45 min before 6 hr permanent coronary artery occlusion. Fifteen minutes before permanent occlusion, dogs were randomly assigned to a control group (n = 11), a pretreatment group (n = 9), which received at this point 10 micrograms/kg of nicardipine as a loading dose followed by a continuous infusion of 8 micrograms/kg/hr for 6 hr, an early treatment group (n = 9), in which nicardipine treatment was initiated 15 min after occlusion, or a late treatment group (n = 8), in which nicardipine administration was delayed for 3 hr. Six hours after coronary artery occlusion, the hearts were excised and the left ventricle of each was cut into 3 mm thick slices and stained with triphenyltetrazolium chloride. The extent of myocardial necrosis was measured by planimetry of the unstained areas. Thereafter, the same slices were autoradiographed and the extent of the hypoperfused zone was measured by planimetry of the "cold spot." The extent of the hypoperfused zone was identical among the four groups. In the control group, the ratio of the extent of myocardial necrosis to the extent of the hypoperfused zone was 95.8 +/- 3.8% (mean +/- SEM). However, it was significantly smaller in the pretreatment group (59.9 +/- 13.3%, p less than .05) and the early treatment group (49.0 +/- 10.6%, p less than .01) than in the control group. In the late treatment group, this value was not different from that in the control group (86.5 +/- 7.1%). There was a close inverse correlation between reduction of infarct size and the extent of the hypoperfused zone in the pretreatment and early treatment groups. Thus, nicardipine administered before or early after coronary artery occlusion limited infarct size by 37% to 49%, whereas when administration was delayed for 3 hr infarct size was not reduced. Furthermore, nicardipine had more striking effects on the ischemic myocardium of dogs with small hypoperfused zones than on that of dogs with large hypoperfused zones.

Animals↗
PubMed1985

Ventricular tachycardia associated with acute myocardial infarction--features, therapeutic effect and prognosis.

This study was performed to delineate the precise features and the treatment of ventricular tachycardia (VT) with acute myocardial infarction (AMI). Results indicate: 1) the incidence of VT in 310 AMI patients was 16.1% (50 patients); 2) the higher incidence of ventricular fibrillation and mortalities were observed in VT group compared with non-VT group; 3) the incidence of VT was higher in inferior infarction group (21.0%) than anterior group (13.1%); 4) more frequent VT were seen in patients with more severe heart failure; 5) two peaks of VT occurrence, on the first day and in the 4th week after the onset of AMI, were recognized especially in anterior infarction group; 6) supraventricular arrhythmias were more frequent than ventricular premature beats during one minute preceding VT; 7) the successful termination of VT was achieved in 63.9% of episodes by thump-version, 61.5% by lidocaine, 66.7% by disopyramide and 100% by mexiletine; 8) prophylactic effect on VT by class Ia antiarrhythmic agents seemed stronger than others; 9) IABP was effective to prevent VT in some cases; 10) poor prognosis was determined by frequent and later onset of VT, and combination of severe heart failure.

Aged↗
PubMed1985

Prominent negative U wave in variant angina pectoris.

The extremely prominent negative U wave occasionally appears during a cardiac attack in variant angina pectoris. The clinical profile of the negative U wave was therefore studied in 80 patients with variant angina pectoris (VA) and 33 controls with resting angina pectoris (RA). The prominent negative U wave appeared in 55 of the patients with VA (68.8% of patients) and in 10 of the patients with RA (30.3%); thus, there was a significant difference in the appearance of the wave between the 2 groups of patients (p less than 0.001). The leads in which the negative U wave appeared were mostly consistent with those in which the ST segment was elevated. The negative U wave began to appear at about the time when ST-segment elevation began to improve; the wave then gradually became very prominent and then eventually disappeared. The patients with VA and also those with RA on whose ECGs the negative U wave appeared during exercise testing also had negative U waves during spontaneous episodes of angina. An investigation of the frequency of appearance of ST deviation and negative U waves during exercise testing, regardless of the type of angina pectoris, disclosed that the negative U wave appeared in 14 of 20 patients with ST-segment elevation (70% of patients), while the negative U wave appeared in only 52 of 519 patients with either no ST change or ST-segment depression (10.4%); thus, there was a significant difference in the appearance of the negative U wave between these 2 groups (p less than 0.001). Coronary cinearteriography failed to disclose any apparent difference between the appearance of the negative U wave and the presence of stenosis. The prognosis of VA and RA in patients with negative U waves was less favorable compared to those without negative U waves. In particular, we noted that of the 10 patients with RA associated with negative U waves, 4 died. Although the mechanism of the negative U wave is not yet known, we believe that the above findings contribute to its elucidation.

Adult↗
PubMed1983

Evaluation of effects of antiarrhythmics on ventricular premature contraction.

Although subjective symptoms and brief recording of ECG have been used for an efficacy evaluation of new antiarrhythmics on ventricular premature contraction (VPC), incidence of subjective complaints in VPC was under 25% and number of VPC for 3 min did not correlate enough to those for 24 hours, indicating these parameters are not appropriate for such a trial. Number of VPC automatically counted by DECG (continuous ECG recording for 24 hours) showed high accuracy, while day to day variation of VPC arose as the next problem. While cases of more than about 7,000/day showed very little day to day variation, cases of less than about 1,000/day had poor reproducibility, indicating that the former group can be used for the trials of new antiarrhythmics, but not the latter group. For cases with medium magnitude of VPC variation, DECG should be recorded twice during the period without drug administration and application of the paired t-test for number of VPC in each corresponding hour may bring a good evaluation.

Anti-Arrhythmia Agents↗