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Biomedical subjects

R Tsukahara

Publications and source records attributed to R Tsukahara.

12 recordsLinked to original sources
PubMed1999

Efficacy of cutting balloon angioplasty for lesions at the ostium of the coronary arteries.

We evaluated 37 patients (39 lesions, 11 women/26 men, median age of 66 years old) with coronary ostial lesions who underwent cutting balloon angioplasty (CB). Seventy-four patients (78 lesions, 18 women/56 men, median age of 65 years old) who had undergone plain old balloon angioplasty (POBA) for coronary ostial lesions were also enrolled as the control group. At clinical diagnosis, unstable angina was seen in 8.1% of the CB group and in 9.5% of the POBA group. Post myocardial infarction silent ischemia was seen in 28.3% of the POBA group and 32.4% of the CB group. The success rate was 94.8% in the CB group and 84.6% in the POBA group. The frequency of intimal dissection was not significantly different between the two groups. However, all cases of intimal dissection in the CB group were mild (either type A or B), whereas the POBA group included many cases of severe intimal dissection (types B through F). No cardiac event was observed in the CB group. However, in the POBA group, cardiac death occurred in 1.4% and emergency bypass surgery occurred in 0.7% of the patients. Calculating the restenosis rate based on the cumulative percent diameter stenosis curve resulted in 43% for the CB group and 53% of the POBA group. We concluded that the cutting balloon was useful for ostial lesions as compared to plain old balloon angioplasty.

Aged↗
PubMed1997

The recruitment pattern of single vasoconstrictor neurons in human.

The aim of this study is to determine the recruitment pattern among individual vasoconstrictor neurons under the baroreceptor-mediated influence in man. Spikes of single vasoconstrictor units were detected from microneurograms with a template-matching method. A total of 39 single vasoconstrictor units were detected. Single vasoconstrictor units were different from each other in their susceptibility to be activated in response to changes in the R-R interval or blood pressure. The units with higher firing probability had a shorter threshold R-R interval and a higher threshold diastolic blood pressure than units with lower firing probability. In sympathetic responses consisting of only one spike (single-spike responses), units with a lower threshold frequently appeared and units with a higher threshold joined mull-spike responses. The units with a short threshold R-R interval tended to have a long inhibitory latency from R wave, suggesting low conduction velocity. The correlation between firing probability and firing threshold and that between appearance in single-spike response and multi-spike response suggest a hierarchical manner of recruitment of vasoconstrictor units. For beat-to-beat responses, however, some deviation from the hierarchical recruitment was also observed.

Adult↗
PubMed1995

Effects of premotion silent period on single motor unit firing at initiation of a rapid contraction.

We compared the single motor unit (SMU) activity between movements with a premotion silent period (PMSP) and without PMSP in EMG. Fourteen SMUs in the gastrocnemius muscle and 6 SMUs in the soleus muscle were recorded from 5 volunteers during isometric plantar flexion. Tonically firing SMUs failed to fire just before the onset of a rapid contraction with PMSP more frequently than without PMSP. SMUs tended to fire within 10 msec (the gastrocnemius SMUs) or 20 msec (the soleus SMUs) from the onset of the phasic EMG discharge when PMSP occurred. In a rapid contraction without PMSP, the initial firing of SMUs occurred with longer latency than that in a rapid contraction with PMSP. The latency of the initial SMU firing in a rapid contraction related to the preceding time of the last SMU firing during a sustained contraction to the onset of the phasic EMG discharge. When the preceding firing was long enough, the latency distributed around 10 msec. On the other hand, for shorter preceding times, the latency lengthened with shortening of the preceding time. It is suggested that the PMSP makes the preceding time long and increases the susceptibility of motor units to the descending command at the initiation of a rapid contraction.

Adult↗
PubMed1995

Percutaneous transluminal coronary angioplasty for culprit lesions in patients with post myocardial infarction angina based on dextrocardia and anomalous coronary arteries. Case reports and methods.

Four cases of successful coronary angioplasty for anomalous coronary arteries, including dextrocardia associated with three-vessel disease, single left coronary artery with proximal left anterior descending lesion, anomalous right coronary artery (RCA) from adjacent left coronary sinus of Valsalva associated with proximal RCA lesion, and anomalous left circumflex angulated lesion bifurcated from the RCA, were encountered. Four cases with 8 target lesions who had a mean age of 63.5 +/- 11.5 years old are presented. All the targets lesions were completely dilated through balloon angioplasty, including use of a newly developed support device for cases with large jeopardized myocardium. The factors for complete revascularization were appropriate selection of catheters and originality and ingenuity of procedural technique based on the anatomic characteristics.

Aged↗
PubMed1994

Lack of association between cholesterol and coronary heart disease mortality and morbidity and all-cause mortality in persons older than 70 years.

OBJECTIVES: To determine whether elevated serum cholesterol level is associated with all-cause mortality, mortality from coronary heart disease, or hospitalization for acute myocardial infarction and unstable angina in persons older than 70 years. Also, to evaluate the association between low levels of high-density lipoprotein cholesterol (HDL-C) and elevated ratio of serum cholesterol to HDL-C with these outcomes. DESIGN: Prospective, community-based cohort study with yearly interviews. PARTICIPANTS: A total of 997 subjects who were interviewed in 1988 as part of the New Haven, Conn, cohort of the Established Population for the Epidemiologic Study of the Elderly (EPESE) and consented to have blood drawn. MAIN OUTCOME MEASURES: The risk factor-adjusted odds ratios of the 4-year incidence of all-cause mortality, mortality from coronary heart disease, and hospitalization for myocardial infarction or unstable angina were calculated for the following: subjects with total serum cholesterol levels greater than or equal to 6.20 mmol/L (> or = 240 mg/dL) compared with subjects with cholesterol levels less than 5.20 mmol/L (< 200 mg/dL); subjects in the lowest tertile of HDL-C level compared with those in the highest tertile; and subjects in the highest tertile of the ratio of total serum cholesterol to HDL-C level compared with those in the lowest tertile. RESULTS: Elevated total serum cholesterol level, low HDL-C, and high total serum cholesterol to HDL-C ratio were not associated with a significantly higher rate of all-cause mortality, coronary heart disease mortality, or hospitalization for myocardial infarction or unstable angina after adjustment for cardiovascular risk factors. The risk factor-adjusted odds ratio for all-cause mortality was 0.99 (95% confidence interval [CI], 0.56 to 2.69) for the group who had cholesterol levels greater than or equal to 6.20 mmol/L (> or = 240 mg/dL) compared with the group that had levels less than 5.20 mmol/L (< 200 mg/dL); 1.00 (95% CI, 0.59 to 1.70) for the group in the lowest tertile of HDL-C compared with those in the highest tertile; and 1.03 (95% CK, 0.62 to 1.71) for subjects in the highest tertile of the ratio of total serum cholesterol to HDL-C compared with those in the lowest tertile. CONCLUSIONS: Our findings do not support the hypothesis that hypercholesterolemia or low HDL-C are important risk factors for all-cause mortality, coronary heart disease mortality, or hospitalization for myocardial infarction or unstable angina in this cohort of persons older than 70 years.

Aged↗
PubMed1993

[Two cases of acute leukemia with t(6;9) (p23;q34)].

Two cases of acute leukemia with a t (6;9) (p23;34) chromosome abnormality are reported. The first case was a 34-year-old female who was hospitalized in October 1989. A diagnosis of FAB-M1 was made. Chromosomal analysis of the bone marrow cells showed a 46, XX, t (6;9) (p23;q34). Complete remission was achieved after two courses of BHAC-DMP therapy. In September 1991, at the time of relapse, chromosomal analysis revealed two abnormal clones consisting of a 46, XX, t (6;9) (p23;q34), -12, -17, +der (12) t (12;17) (p11.2;q11.2) with a residual normal clone. She died in February 1992. The second case was a 42-year-old male who was hospitalized in January 1990. He was diagnosed as having RAEB. Chromosomal analysis of the bone marrow cells showed 46, XY, t (6;9) (p23;q34). Three months later, the disease progressed to acute leukemia accompanied by leg ulceration with leukemic cell infiltration. Small-dose ara-C therapy was given, but with no effect. After two subsequent courses of therapy with low-dose etoposide, complete remission was achieved. Four months later, relapse occurred, and the patient died of sepsis in February 1991. In the literature, 31 cases of myeloproliferative disorders with t (6;9) have been reported.

Acute Disease↗
PubMed1992

[A case of nonbacterial thrombotic endocarditis presenting positive findings by two-dimensional echocardiography].

A 55-year-old woman was admitted to our hospital because of left hemiparesis. Brain CT and cerebral angiography demonstrated cerebral embolism due to occlusion of the sphenoidal part of the right middle cerebral artery. Two-dimensional echocardiography revealed mitral valve vegetation measuring 10 x 7 mm and slight mitral-valve regurgitation. Blood cultures were negative. She developed disseminated intravascular coagulation. Chest roentgenography and abdominal ultrasonography showed multiple liver and lung tumors, but she died before the primary lesion was detected. At autopsy, adenocarcinoma of the gall bladder was found. Friable vegetation was attached to the auricular surface of the mitral valve. Microscopic examination confirmed the diagnosis of nonbacterial thrombotic endocarditis. Although echocardiography is an important tool for diagnosing nonbacterial thrombotic endocarditis, few reports have described echocardiographic detection of nonbacterial thrombotic endocarditis. Because vegetation of nonbacterial thrombotic endocarditis is smaller than that of infective endocarditis (less than 3 mm), it is difficult for echocardiography to detect nonbacterial thrombotic endocarditis. Thus, a negative examination does not exclude the possibility of nonbacterial thrombotic endocarditis. To make an antemortem diagnosis of nonbacterial thrombotic endocarditis, we must perform echocardiography carefully in cases of cerebral infarction with carcinoma and/or DIC.

Adenocarcinoma↗
PubMed1991

[Myocardial viability in old myocardial infarction as evaluated by T1-201 SPECT and two-dimensional echocardiography].

Myocardial viability of the infarcted area was evaluated in 49 patients with old myocardial infarction by thallium-201 myocardial single photon emission computed tomography (SPECT), two-dimensional echocardiography (2 DE) and electrocardiography (ECG). The following results were obtained: 1. T1 uptake (%TU) correlated significantly with the % systolic thickening ratio (% delta Th) and the interventricular septal excursion (IVSE) (r = 0.66, r = 0.75), suggesting that both parameters are useful in predicting myocardial viability of the infarcted areas. 2. In 18 patients, the % delta Th was 0, IVSE ranged from -3 mm to +3 mm, and a positive correlation between %TU and IVSE was present, suggesting an advantage of IVSE over % delta Th as a parameter. 3. Forty-nine patients were categorized into 4 groups based on their ECG findings; 3 with QS and complete RBBB (Group A); 19 with QS and ST elevation (Group B); 10 with QS without ST elevation (Group C); and 17 with non-QS (Group D). All of %TU, % delta TH and IVSE increased in the order of Groups A < B < C < D. 4. The bull's eye method showed redistribution in 5 of 19 patients (26%) in Group B, 5 of 19 (26%) with % delta Th < or = 0 and 2 of 9 (22%) with IVSE < or = 0. These results suggested that transmural myocardial infarction, which has been considered irreversible, may be viable and PTCA or coronary bypass surgery is recommended if ECG or 2DE gives indications of myocardial viability.

Adult↗
PubMed1989

Effects of pre-motion electromyographic silent period on dynamic force exertion during a rapid ballistic movement in man.

The effects of pre-motion silent period (PSP) on dynamic force exertion were studied in ten healthy subjects performing ballistic elbow extensions. The experiments were designed to evaluate the significance of mean differences between the averaged dynamic force curves of two groups: PSP-presence groups and PSP-absence groups. The presence of PSP was judged quantitatively and automatically by means of a newly developed method using statistical analysis. The results indicated that there were two effects of PSP on dynamic force exertion: one was a reducing effect, observed prior to the movement; the other was a reinforcing effect, observed in the first part of the ballistic movement. The duration of the reinforcement was significantly correlated with the duration of the reducing effect of PSP. The findings suggested that the reinforcement of dynamic force may be produced by the pre-stretch of agonistic muscles caused by prior force reduction due to PSP occurrence. The fact that PSP plays an important role in dynamic force exertion suggests that PSP may be incorporated in the central motor control system designed to interrupt the background activity, to stretch the agonist and to reinforce the dynamic force.

Adult↗
PubMed1985

Postural adjustments for jumping reaction movement in mentally retarded children: findings from EMG patterns.

EMG patterns during a jumping reaction task were studied in 53 mentally retarded children. EMGs were recorded from the knee extensors (VM and RF) and the knee flexors (hamstrings). Lack of synchronization between onset of phasic discharge in the VM and the RF and between onset in the hamstrings and the knee extensors was characteristic of retarded children. Deviation from the EMG pattern of normal adults decreased with increasing MA. The premotor time tended to be prolonged with increasing time differences between the VM and the RF responses. Shorter RT between the VM and the RF was consistent across EMG patterns. These were more apparent in subjects with MAs above 7 than in those with MAs below 6. It is suggested that the asynchronized EMG pattern reflects postural requirements due to poor formation of preparatory set.

Adolescent↗
PubMed1985

Developmental trends of jumping reaction time by means of EMG in mentally retarded children.

Developmental trends of jumping reaction time (RT) in mentally retarded children were studied cross-sectionally. Fifty-three boys, ranging in CA from 7 to 18 years, took part in the jumping RT task. RT measurements were obtained from EMG of an agonist muscle (rectus femoris). There was a significant decrease in RT with increasing CA. Correlation between RT and MA was highly significant, but discontinuity in the distribution was found between MA of 6 and 7 years. The subjects with a MA below 6 were characterized by large variability as well as slowness in RT. RT was not correlated with CA holding MA constant among the subjects with a MA below 6. The subjects with a MA above 7 showed relatively small variability within and between subjects. RT in subjects with a MA above 7 decreased with CA holding MA constant but RIV showed no change. RT in children with a very low MA is prolonged by inefficiency which reflects difficulty in maintaining attention or arousal level. The efficiency in information processing may change between the MAs of 6 and 7 years.

Adolescent↗