Search PubMed⌕ Search

Biomedical subjects

S Yabuki

Publications and source records attributed to S Yabuki.

At least 73 records · Page 4Linked to original sources
PubMed1992

[Is radiofrequency catheter ablation available for treatment of ventricular tachycardias?--Effects of sequential unipolar applications using multiple electrode catheter].

The purpose of this study was to examine the effects of radiofrequency energy delivered to the canine endocardium in sequential unipolar applications using multipolar electrode catheter for treatment of ventricular tachycardias. Radiofrequency energy generated by the newly designed device (500 kHz) was delivered to the ventricular myocardium by a quadripolar electrode catheter. The device could indicate output and voltage and could calculate myocardial impedance. In order to determine the power of the ablation in vivo, sequential unipolar application was performed with various output in vitro. A continuous endocardial ablation was achieved with output beyond 15 W and with duration of 5 sec per one pole. According to our measurement, the myocardial impedance in vivo was about three times as large as that in vitro. Therefore, minimal output of 45 W in vivo was applied in the same manner in vitro, which resulted in continuous belt-shaped endocardial ablated lesion. Ventricular stimuli after sequential unipolar applications did not induce ventricular tachycardia in any of the dogs. We conclude that radiofrequency sequential unipolar application using the newly designed device produces a large ablated area and may be suitable for ablation of the foci of ventricular tachycardias.

Animals↗
PubMed1991

Chronic alcoholism impedes the recovery of renal function following renal ischemia.

The recovery of renal function following renal ischemia was studied using rats fed for 1-, 3-, and 5-week periods with an alcoholic diet (ethanol provided 36% of total calories). Renal ischemia was produced by clamping the renal artery and vein for 20 min. Renal function was determined 24 hr after the ischemia. In the absence of ischemic insult, the renal function of rats fed with an alcoholic diet for 1, 3, and 5 weeks was not significantly different from those of nonalcoholic rats. In nonalcoholic rats, renal function (24 hr postischemia) were: glomerular filtration rate (GFR) 430.4 +/- 29.6 microliters/min/g KW (kidney weight), renal plasma flow rate (RPFR) 1.4 +/- 0.17 ml/min/g KW, and fractional sodium excretion (FENa) 2.0 +/- 0.04% (mean +/- SE). Postischemic renal function of rats on 1- and 3-week alcoholic diets were essentially the same as that of the control rats. However, the 24-hr postischemic renal function of 5-week alcoholic diet rats was significantly depressed. The values were only 117.2 +/- 35.2 microliters/min/g KW (p less than 0.05) for GFR, 0.31 +/- 0.12 ml/min/g KW (p less than 0.05) for RPFR, and 7.46 +/- 3.59% for FENa. The present results demonstrate that the rat kidney subjected to prolonged alcohol ingestion was more susceptible to renal insult than a nonalcoholic kidney.

Alcoholism↗
PubMed1991

Beneficial effects of the urinary trypsin inhibitor urinastatin on renal insults induced by gentamicin and mercuric chloride (HgCl2) poisoning.

The authors investigated the protective effects of the urinary trypsin inhibitor urinastatin on acute renal failure induced in rats by gentamicin (240 mg/kg body weight i.p. for 3 days) and by mercuric chloride (3 mg/kg s.c.). In rats injected with gentamicin, glomerular filtration rate (GFR), renal plasma flow (RPF), and percent fractional sodium excretion (%FENa) were 151 +/- 51 microliters/min/100 g body weight, 0.69 +/- 0.31 ml/min/100 g and 0.73 +/- 0.32, respectively, whereas in rats given 100,000 U of urinastatin the renal function was significantly ameliorated (GFR 318 +/- 43 microliters/min/100 g RPF 1.41 +/- 0.35 ml/min/100 g), although the %FENa (0.46 +/- 0.26) was not significantly improved. A 50,000-unit dose of urinastatin prevented the deterioration of renal function to some extent following administration of gentamicin: GFR 219 +/- 66 microliters/min/100 g and RPF 0.93 +/- 0.43 ml/min/100 g. In the study using mercuric chloride, treatment with 75,000 U of urinastatin protected the kidney from HgCl2 poisoning, yielding values of 294 +/- 93 microliters/min/100 g (GFR), 1.03 +/- 0.41 ml/min/100 g (RPF), and 1.44 +/- 0.72 microliters/min/100 g (%FENa) as compared with respective values of 169 +/- 48 microliters/min/100 g, 0.7 +/- 0.18 ml/min/100 g, and 2.22 +/- 1.35 in the untreated rats. Renal histology revealed mild to moderate tubular epithelial changes in untreated rats, but preservation of an almost normal tubular structure in urinastatin-treated rats in both studies.

Animals↗
PubMed1991

[Prediction of severity of coronary artery disease by treadmill exercise testing].

Coronary angiography was performed in 250 patients with a significant ischemic ST segment change detected by symptom-limited maximum treadmill exercise testing, and relationship between anatomical severity of coronary artery disease and parameters in exercise testing was studied. The age of the patients ranged from 34 to 76 years (188 men, 62 women). One-vessel disease (1VD) was presented in 82 patients, two-vessel disease (2VD) in 42, three-vessel disease or left main coronary disease (3VD) in 26, and no significant stenosis was presented in 100 subjects (Normal). Functional aerobic impairement (FAI) was evaluated in each group as a parameter of exercise capacity, myocardial aerobic impairment (MAI) and heart rate impairment (HRI) were also evaluated as a parameter of maximum myocardial oxygen requirements and maximum heart rate, respectively. Using these parameters, discriminant analysis was performed to compare the group with significant coronary artery disease and the Normal group. Also, to compare the group with multi-vessel disease and the group with less than 2VD. Also, the 3VD group and the group with less than 3VD. FAI, MAI and HRI were significantly different (p less than 0.0001) in each group. The discriminant formula to separate the group of significant coronary artery disease from the Normal group was Z = -1.049 + 0.02 [FAI] +0.08 [MAI] +0.03 [HRI]. According to this formula, sensitivity was 92.5% and specificity was 71.5%. The discriminant formula to separate the group with multi-vessel disease from the group with less than 2VD was Z = -4.731 + 0.07 [FAI] +0.106 [MAI] +0.02 [HRI]. According to this formula, sensitivity was 96.3% and specificity was 78.8%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Coronary collateral vessels during the early period of acute myocardial infarction: their development].

The aim of this study was to investigate the incidence and development of coronary collateral circulations in patients with acute myocardial infarction (AMI). We categorized 165 patients with persistent 100% occlusion of the infarct-related artery into 6 groups according to the time from the onset of AMI to angiography. Group I consisted of 55 patients evaluated within 6 hours after the onset of AMI; Group II, 28 patients, between 6 and 12 hours after the onset; Group III, 12 patients, between 12 and 24 hours after the onset; Group IV, 11 patients, between 2 and 13 days after infarction; Group V, 46 patients, between 14 and 44 days after infarction; and Group VI, 13 patients, more than 45 days after infarction. Collateral vessels were applied a numerical score between 0 and 3 according to the degree of opacification of the native vessel distal to the occlusion. In 58%, 79%, 67%, 73%, 89%, and 92%, patients of Groups I to VI had evidence of collateral vessels, respectively. Well-developed collaterals were observed in 24% of Group I compared with 50%, 58%, 55%, 73% and 69% of patients in Groups II to VI, respectively. The mean coronary collateral scores were 0.9 +/- 0.1, 1.4 +/- 0.2, 1.4 +/- 0.3, 1.6 +/- 0.4, 2.0 +/- 0.2 and 2.2 +/- 0.3 for Groups I to VI, respectively. Patients with preinfarction angina had more well-developed collateral circulations than did patients without it, however, there was no significant correlation between the duration of previous angina and extent of coronary collaterals.

Adult↗
PubMed1991

[Cardiac rehabilitation in patients with acute myocardial infarction: assessments with T1-201 myocardial scintigraphy].

The effects of exercise training on myocardial perfusion during the first 3 months after acute myocardial infarction (AMI) were assessed by exercise myocardial scintigraphy and fibrinolytic examinations. Symptom-limited treadmill exercise with thallium-201 myocardial single photon emission CT (SPECT) and fibrinolytic examinations (tissue plasminogen activator antigen: tPA, plasminogen activator inhibitor-1 antigen : PAI-1) were performed 2 and 14 weeks after AMI in 13 patients with exercise training and in 12 patients without exercise training. For quantitative analysis, counts of region of interest in the infarct area and normal reference area were calculated on a polar map obtained from myocardial SPECT. Severity of the hypoperfused myocardium was determined as an initial percent uptake (%IU) and a delayed percent uptake (%DU). The difference (%DU-%IU) was defined as a parameter of residual ischemia in the infarct area (%redistribution : %RD). Total treadmill exercise duration according to the Bruce protocol increased significantly in the training group (351 +/- 89 to 431 +/- 118 sec, p < 0.01); whereas, there was no significant change in the non-training group (340 +/- 95 to 356 +/- 123 sec). In the training group the pressure-rate product and %DU increased significantly (225 +/- 55 to 259 +/- 58 mmHg.beats/min x 100, 59 +/- 19 to 65 +/- 20%, p < 0.01, respectively), and %RD decreased significantly (8.8 +/- 6.7 to 4.8 +/- 4.5%, p < 0.01), but there was no significant change in the non-training group (231 +/- 89 to 240 +/- 86 mmHg.beats/min x 100, 56 +/- 17 to 57 +/- 12% and 7.4 +/- 5.5 to 6.2 +/- 6.5%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Circulation↗
PubMed1991

[An experimental study on the alteration of myocardial tissue by radiofrequency catheter ablation: differences according to the frequency and the device].

To evaluate the alteration of myocardial tissue by radiofrequency (RF) catheter ablation according to differences of the frequency and the device, we applied RF catheter ablation to canine right ventricular myocardium in vitro. The devices delivering RF energy were LL-49(0. 49MHz, fixed voltage mode), RA-50 (13.56MHz, fixed watt mode) and HAT200 (0.52MHz, fixed watt mode with the capability of temperature adjustment). After RF catheter ablation were performed with a unipolar electrode catheter at various output under the same condition of contact, the ablated lesions by each device were compared. Histologically, we recognized coagulation layer with the necrosis of endocardium and the dissociation of myocardium in each experiment. The degree and the size of ablation layer was significantly larger in lower frequency delivery (p less than 0.05) and was significantly smaller by using the device with temperature adjustment as compared with the others (p less than 0.05). It was suggested that the alteration of myocardial tissue ablated with RF energy differ according to the frequency and the mode of output adjustment of the device.

Animals↗
PubMed1990

Out-of-hospital sudden cardiac death following myocardial infarction in urban population.

Samples of out patient sudden cardiac deaths in Kanagawa Urban prefecture from 1972-1987 and coronary risk factors were studied to determine the increase and/or decrease of myocardial infaction deaths. On the whole death from myocardial infarction increased chronologically, and the rate for females tended to be increased further. The age adjusted myocardial infarction deaths doubled over 10 years, while non-ischemic acute cardiac failure decreased with each generation. Other cardiac diseases tended to be reduced. Cigarette smoking was the highest in advanced countries in male. These findings suggest that deaths from myocard infarction approximately doubled in 10 years in all out-of hospital sudden cardiac deaths. Cigarette smoking from a young age was as great risk as future ischemic heart disease.

Adult↗
PubMed1990

[The effect of percutaneous transluminal coronary recanalization (PTCR) on late potentials detected by signal-averaged electrocardiogram in patients with previous myocardial infarction].

The purpose of this study was to assess the effect of percutaneous transluminal coronary recanalization (PTCR) on late potentials (LP) in patients with previous myocardial infarction (MI). The signal-averaged ECG was recorded by Fukuda VCM-3000 in 54 patients with anterior MI (average of 32 months after onset of MI). Fifty four patients were divided into two groups: Group A was comprised of 29 patients who underwent PTCR, and Group B was comprised of 25 patients who didn't receive PTCR. Ventricular arrhythmias detected by 24 hour Holter monitoring, and left ventriculographic findings were also evaluated. The presence of LP was defined as low amplitude signals (less than 15 microV) in the last 40 msec of the filtered QRS complex. The incidence of LP was significantly higher in Group B than in Group A (32% vs 7%, p less than 0.01). The presence of PVCs and ejection fraction (EF), LV end-diastolic volume (EDV), LV end-systolic volume (ESV) and % abnormally contracting segment (% ACS) were not significantly different in each respective groups. However, ESV and % ACS were significantly larger (p less than 0.05), and EF was significantly smaller (p less than 0.01) in patients with LP (+) than in patients with LP (-). LP was present in two patients who had undergone PTCR (TIMI grade 2) unsuccessfully, whereas it was not present in the 27 patients with successful PTCR (TIMI grade 3). It was concluded that successful recanalization of the infarct-related arteries may reduce the incidence of LP.

Aged↗
PubMed1990

[A case of mitochondrial myopathy with mononeuritis multiplex].

A case of mitochondrial myopathy with mononeuritis multiplex was described. A 55-year-old man was hospitalized because of blepharoptosis and muscle weakness. His mother also showed blepharoptosis in her elderly stage of life. He had been healthy until 46 years of age, when he first noticed difficulty of speech, followed by bilateral blepharoptosis, weakness of upper limbs, and sensory disturbance in the left occipital, and left upper and lower extremities. These symptoms progressed slowly. On admission, bilateral blepharoptosis was recognized. Slightly to moderate muscle wasting and weakness were observed in the face, neck, trunk, and extremities. Areflexia was observed in the upper extremities. Paresthesia was observed in the left occipital and left hip, and superficial sensation was impaired in the left upper and lower extremities. Electromyographic examination of extremities showed neurogenic changes in the distal muscles and myogenic changes in the proximal muscles. Motor conduction velocities were normal, but sensory conduction velocities decreased in amplitude on the left upper extremity and were not evoked on the left lower extremity. Muscle biopsy specimen revealed numerous "ragged-red" fibers. Cytochrome c oxidase stain showed a decrease in intensity of staining. A sural nerve biopsy showed slight axonal degeneration and slight loss of nerve fibers. Biochemical analysis on biopsy muscle showed partial deficiency of cytochrome c oxidase activity.

Humans↗
PubMed1990

Do the H2-receptor antagonists, cimetidine and famotidine, modify the degree of renal recovery following renal insult?

The effects of two different H2-receptor antagonists, cimetidine and famotidine, on the acute renal failure induced by 20 min of renal artery occlusion and gentamicin (240mg/kg BW, s. c., for 3 days) were investigated in Sprague-Dawley rats. The animals were treated with either cimetidine (80 or 160 mg/kg BW) or famotidine (4 or 8 mg/kg BW) mixed in the drinking water for 7 days. The low dose of cimetidine and famotidine did not alter the renal function in the absence of renal trauma. However, the high dose of cimetidine or famotidine decreased the GFR by 32% and 22%, whereas RPFR increased by 46% and 62%, and % FENa by 92% and 558%, respectively. The data for the renal function obtained 24 hrs after 20 min of renal ischemia demonstrated a decrease of 54% in GFR, a decrease of 47% in RPFR and an increase of 370% in %FENa over the non-ischemic control values (p less than 0.05). Cimetidine (80 mg/kg BW) or famotidine (4 mg/kg BW) did not modify the recovery of renal function following the ischemic insult, showing 55% and 539% decreases in GFR, 74% and 101% increases in RPFR, and 393% and 461% increases in %FENa over the non-ischemic control rats, respectively. Famotidine reduced the decrease in RPFR significantly during the recovery period following ischemia. In the gentamicin study, gentamicin treatment was found to lower the renal function significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Kidney Injury↗
PubMed1989

Kidneys of chronic alcoholic rats are more vulnerable to ischemic insult.

The effects of chronic ethanol ingestion on the rat kidney were studied. Rats were fed a liquid diet containing ethanol for 5 weeks to induce chronic alcoholism. Renal ischemia was introduced by clamping the renal artery and vein either for 10 or 20 min. The glomerular filtration rate (GFR) and the renal blood flow (RBF) were determined by using I125-iothalamate and I131-iodohippurate. In the absence of renal ischemia, there were no significant differences in the renal function between nonalcoholic rats (n = 5) and alcoholic rats (n = 5): 380 +/- 30 vs. 403 +/- 27 microliters/min/100 g body weight (BW) in GFR, and 3.1 +/- 0.1 vs. 3.1 +/- 0.2 ml/min/100 g BW in RBF. The recovery of GFR measured 2 h following 10-min renal ischemia in both groups was not significantly different; the values returned to 340 +/- 40 microliters/min/100 g BW (nonalcoholic rats) and 246 +/- 22 microliters/min/100 g BW (alcoholic rats), respectively. The changes of RBF following 10 min ischemia were also similar in both groups. However, the effects of alcoholism on the renal function became apparent when animals were subjected to more prolonged renal ischemia. In nonalcoholic rats (n = 5), GFR and RBF measured 2 h following 20 min renal ischemia were 245 +/- 51 microliters/min/100 g BW and 2.5 +/- 0.4 ml/min/100 g BW, whereas in alcoholic rats (n = 5) the GFR and RBF were significantly decreased to 93 +/- 15 microliters/min/100 g BW and 1.1 +/- 0.2 ml/min/100 g BW, respectively (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Alcoholism↗
PubMed1989

Effects of famotidine, a new histamine H2-receptor antagonist, on renal function.

The effects of famotidine on renal function were investigated. Eight healthy men (N) and 8 renal patients with varying degrees of renal failure (R.F.) participated in the trial. They were given either famotidine (40 mg) or cimetidine (800 mg) for 7 days. Cimetidine produced a significant decrease in creatinine clearance (from 131.6 +/- 12.9 to 107.7 +/- 3.4 ml/min (N), and 22.2 +/- 3.9 to 18.1 +/- 3.5 ml/min (R.F.], and increase in serum creatinine (from 0.96 +/- 0.05 to 1.09 +/- 0.04 mg/dl (N), and 3.46 +/- 0.62 to 3.86 +/- 0.51 mg/dl (R.F.], and a decrease in creatinine excretion (from 24.0 +/- 1.1 to 22.6 +/- 0.8 mg/kg/24 hr (N], respectively, although the reduction in creatinine excretion in the renal failure group was small. On the other hand, the famotidine treatment produced no significant changes in renal function in both subjects (creatinine clearance, 136.5 +/- 5.7 to 133.6 +/- 6.0 ml/min (N), and 21.9 +/- 3.6 to 20.9 +/- 4.1 ml/min (R.F.); serum creatinine, 0.98 +/- 0.02 to 0.99 +/- 0.02 mg/dl (N), and 3.24 +/- 0.43 to 3.46 +/- 0.55 mg/dl (R.F.); and urinary creatine, 25.1 +/- 1.0 to 25.3 +/- 1.0 mg/kg/24 hr (N), and 17.2 +/- 1.4 to 16.6 +/- 1.5 mg/kg/24 hr (R.F.]. There were no changes in the percent sodium excretion, or the serum and urinary beta 2-microglobulin in both groups.

Acetylglucosaminidase↗
PubMed1989

[Indications for PTCA for the infarcted myocardium without redistribution by T1-201 myocardial scintigraphy: the role of two-dimensional echocardiography].

Persistent myocardial hypoperfusion in delayed images demonstrated by preoperative exercise T1-201 myocardial scintigraphy may improve after PTCA. The purpose of this study was to test whether PTCA-induced improvement could be anticipated by means of preoperative two-dimensional echocardiography and exercise T1-201 myocardial scintigraphy. The subjects consisted of 24 patients with prior myocardial infarction, in whom serial exercise T1-201 myocardial scintigraphy had been performed during treadmill exercise testing. The patients were divided into three groups according to the results of two-dimensional echocardiography (Group I: eight patients with hypokinesis in the infarct zone; Group II: eight patients with akinesis without a thin wall in the infarct zone; Group III: eight patients with akinesis with a thin wall in the infarct zone). Results were as follows: 1. There was no significant difference in initial T1-uptake in all the 24 patients before and after PTCA, though significantly increased uptakes were observed in Groups I and II after PTCA. 2. There were significant differences in preoperative initial T1-uptakes among the three groups. 3. In Group II, the patients with postoperative scintigraphic improvement had significantly higher preoperative initial T1-uptakes. 4. The postoperative improvement of myocardial perfusion was accompanied by improvement in wall motion. Therefore, an infarct zone without delayed redistribution in T1-201 myocardial scintigraphy does not necessarily indicate scar tissue. However, it may represent hypokinetic or akinetic areas without thin walls on two-dimensional echocardiograms, suggesting a hibernating myocardial state due to chronic intermittent episodes of myocardial ischemia. In such cases, improvement of myocardial perfusion after PTCA can be expected.

Adult↗
PubMed1989

[Out-of-hospital sudden cardiac death: a comparative study spanning 10 years].

Incidence, etiology and time zones of sudden cardiac deaths were compared for 1986 and 1976. Totals of 1,140 cases of acute endogeneous deaths, 590 in 1986 and 550 in 1976, were sent for coroner's inquest in Kanagawa Prefecture. These were the materials for the present study. Sudden cardiac deaths included 239 (46.1%) in 1986 and 137 (37.4%) cases in 1976 in males, and 81 (47.1%) in 1986 and 74 (40.0%) cases in 1976 in females. There were 129 (21.9%) and 163 (29.6%) cases with cerebral hemorrhages in 1986 and 1976, respectively. The acute cardiac death was the most frequent cause among acute endogenous deaths, and it approximately doubled among males during an interval of 10 years. It was related to a marked increase in ischemic heart disease (from 89 to 170 cases) in males compared to a slight increase among females (from 58 to 76 cases). Non-ischemic acute cardiac deaths were frequently noted in males; 38 (27.7%) and 27 (11.4%) cases in 1976 and 1986, respectively. In ischemic heart disease, deaths most frequently occurred about midnight (from 12 a.m. to 1 a.m.) or in the evening (from 5 p.m. to 6 p.m.), and deaths due to acute cardiac failure occurred during sleep. Time zones of evening deaths in ischemic heart disease corresponded to the report of Muller et al., but, the peak about midnight was not reported. This difference may be explained by the circadian rhythm theory, however, heavy alcohol intake and spasmogenicity in the Japanese people may also play roles in midnight deaths.

Adolescent↗
PubMed1987

Cold-induced dysaesthesia in acute idiopathic polyneuritis.

Two cases are reported of cold-induced dysaesthesia occurring during an attack of acute idiopathic polyneuritis. Two similar cases found in the literature are reviewed. It is suggested that the dysaesthesia may be a localized symptom of cold sensitivity, with an initiating trigger in common with acute idiopathic polyneuritis.

Adolescent↗
PubMed1987

Current status of prehospital care of patients with acute myocardial infarction in Tokyo: analysis of 3-year experience with coronary care unit network.

To clarify the current status of prehospital care of patients with acute myocardial infarction (AMI) in the Tokyo metropolitan area, the availability of the coronary care unit (CCU) network during the past 3 years (January 1982 through December 1984) was analyzed, examining: final diagnosis, circumstances at the onset of AMI, course of transportation to CCU, time elapsed before admission, severity of AMI, and prognosis of patients. Of 6,939 patients admitted to CCU by means of the CCU network, 2,408 patients (34.7%) had AMI. The patient's decision time was, on the average, 12 hr 3 min, longer when the course of transportation to CCU was more complicated. The fatality for AMI was 17.2%. Causes of death were pump failure in 52.8%, arrhythmias in 62.8% and mechanical failure such as cardiac rupture in 8.5%. Patients with complicated AMI were admitted earlier and had a higher fatality than those without complications. Thus, community oriented programs are required to more fully inform the population at risk of AMI to shorten the patient's decision time, and more effective means to treat patients with pump failure and to prevent the development of pump failure need to be established.

Aged↗