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Biomedical subjects

K Machii

Publications and source records attributed to K Machii.

At least 55 records · Page 3Linked to original sources
PubMed1992

Naturally occurring Mycobacterium scrofulaceum infection in a laboratory mouse colony.

A contamination with Mycobacterium scrofulaceum was experienced in a colony of BALB/c-nu/nu mice. The contamination was noticed after introduction of C57BL/6 and C57BL/6. Lyt l. 1 strains into facilities that kept the colony. M. scrofulaceum seemed to be spread by oral infestation and cross-contamination of fecal excretions during handling of the mice. The organisms were shed continually or intermittently into feces of weaned nu/+ and nu/nu mice of BALB/c background, and were isolated from the mesenteric lymph nodes and spleen of some of the mice. Some of the bacillus-carrying mice developed serum antibody to M. scrofulaceum of IgG and IgA classes and gave a low degree of hypersensitivity to PPD from M. tuberculosis.

Animals↗
PubMed1992

Exercise training and the prevention of restenosis after percutaneous transluminal coronary angioplasty (PTCA).

To evaluate whether exercise training prevents the restenosis after percutaneous transluminal coronary angioplasty (PTCA), treadmill exercise with thallium-201 myocardial scintigraphy was performed at first and thirteenth week after PTCA in 18 patients with training and in 20 patients without training. Total treadmill exercise duration and maximal pressure rate product 13 weeks after PTCA increased significantly in the trained group, whereas there was no significant change in the untrained group. ST segment depression from the baseline did not change significantly in both groups. Myocardial perfusion obtained by Tl-201 scintigraphy improved significantly in the trained group, whereas there was no significant change in the untrained group. The restenosis rates at the third month after PTCA was 17% (3/18) in the trained group and 40% (8/20) in the untrained group. It is concluded that in patients with coronary artery disease, exercise training improves myocardial perfusion by preventing the progression of coronary artery stenosis after PTCA.

Angioplasty, Balloon, Coronary↗
PubMed1991

Acetylcholine-induced endothelium-dependent vascular smooth muscle relaxation in nitroglycerin-tolerant isolated rat aorta.

Nitroglycerin (NTG) tolerance is recognized clinically, and its pharmacological mechanism has been thought to be due to a decrease in the accumulation of cyclic GMP (cGMP) which is a second messenger of NTG. Endothelium-derived relaxing factor (EDRF) also relaxes vascular smooth muscle through the activation of soluble guanylate cyclase and the production of cGMP. The purpose of this study was to investigate acetylcholine (ACh)-induced endothelium-dependent relaxation and cGMP response in NTG-tolerant isolated rat aorta. Ring strips prepared from the thoracic aorta of male Wistar rats were mounted in tissue baths and contracted with 10(-6) M norepinephrine. NTG and ACh relaxation responses were compared before and after 1 h treatment with 5 x 10(-4) M NTG. The chronological changes in tissue cGMP levels by 10(-6) M NTG and ACh were compared between a control group (untreated) and NTG-tolerant group (treated with 5 x 10(-4) M NTG for 1 h). The NTG dose-response curve shifted markedly to the right, but the ACh dose-response curve shifted to the left after the induction of NTG tolerance. In the control group, both NTG and ACh elevated the tissue cGMP levels, but in the NTG-tolerant group only ACh elevated cGMP significantly. However, in the NTG-tolerant group, the cGMP increase induced by ACh was smaller than that in the control group. These results suggest that NTG tolerance does not decrease, but rather augments ACh-induced endothelium-dependent vascular smooth muscle relaxation in isolated rat aorta.

Acetylcholine↗
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↗
PubMed1991

[Effects of depth on the display of color Doppler flow imaging with transesophageal and transthoracic transducers: an experimental study].

Transesophageal color Doppler flow imaging has proved to provide an accurate and sensitive information for diagnosis of valvular regurgitation. However, it is necessary to understand the difference in the display of color Doppler image between transesophageal and conventional transthoracic transducers for quantitative assessment of valvular regurgitation. In this study, the effects of the depth between transducer and jet flow on color Doppler flow imaging were evaluated with the transesophageal (3.75 MHz) and conventional (2.5 MHz) transducers by using a flow phantom. A flow circuit was filled with saline in which nylon corpuscles (average diameter; 5 microns) were suspended to enhance the Doppler effects. A turbulent jet with constant flow velocity (Reynolds number; 3500) stimulating valvular regurgitant flow was produced in a water bath through a small orifice (2 mm) by constant driving pressure (100 mmHg). Color jet imaging in the long- and short-axis views were observed at each depth with both transducers. The measurement was made every 1 cm in depth from 3 to 12 cm. The color gain setting was fixed at the optimal point so as to get the maximal flow image with the minimal static background noise. We obtained larger image of the color jet signal with the conventional than the transesophageal transducer. Although a mosaic pattern was displayed more distinctly with the transesophageal transducer compared with that of the conventional transducer, the transesophageal image tended to become indistinct in the depth deeper than 8 cm. On the other hand, the transthoracic image was maintained relatively constant at any depth.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗
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

[Efficacy of combined therapy using coronary reperfusion and elective percutaneous transluminal coronary angioplasty for acute myocardial infarction].

The effects of elective percutaneous transluminal coronary angioplasty (PTCA) performed one month after coronary reperfusion therapy in patients with acute myocardial infarction (AMI) were observed using exercise Tl-201 myocardial scintigraphy performed before and after PTCA. Myocardial perfusion in Tl-201 scintigraphy was significantly greater in the early (less than 4 hours) and late (4-9 hours) reperfusion groups than in the total occlusion group one month after the onset of AMI. Both reperfusion groups showed significant improvement in myocardial perfusion after elective PTCA; whereas, the total occlusion group showed no significant improvement. In the early reperfusion group, there were no significant differences in myocardial perfusion between those with well developed and those with poorly developed collateral circulations one month after the onset of AMI. However, in the late reperfusion group, myocardial perfusion was greater in those with well developed collateral circulations compared to those with poorly developed collateral circulations. The grade of myocardial perfusion in the late reperfusion group with poorly developed collateral circulations did not differ significantly from that of the total occlusion group. There was significant improvement of myocardial perfusion in the early and late reperfusion groups with well developed collateral circulations after elective PTCA; whereas, no significant improvement was observed in the late reperfusion group with poorly developed collateral circulations. These findings indicate that the time interval from the onset of AMI to reperfusion and the grade of development of collateral circulations are the major determinants of myocardial perfusion after elective PTCA and after reperfusion therapy.

Adult↗
PubMed1990

[Significance of residual coronary artery stenosis after reperfusion therapy in acute myocardial infarction].

We evaluated the efficacy of reperfusion therapy in acute myocardial infarction in terms of postinfarction angina (PIA), reinfarction and coronary reocclusion. In 99 hospitalized patients with acute myocardial infarction within 6 hours after the onset of symptoms, 67 were treated using intracoronary thrombolysis (ICT) alone (Group T) and the remaining 32 using ICT followed by percutaneous transluminal coronary angioplasty (PTCA) (Group T + A). PTCA was performed for the arteries with high grade residual stenosis (TIMI grade 0, 1, 2) after ICT. Recatheterization was performed 28 +/- 12 days after hospitalization in 93% (62/67) of Group T and in all of Group T + A. There were no significant differences in age, sex, time interval from the onset to reperfusion, the extents of coronary artery disease and the Cohn grade of collaterals. However, anteroseptal infarction was more frequent in Group T than in Group T + A (p less than 0.05). Residual stenosis (diameter) at the end of intervention was 81 +/- 14% in Group T, and 48 +/- 15% in Group T + A, (p less than 0.01). Residual stenosis at recatheterization was 70 +/- 23% in Group T, and 55 +/- 22% in Group T + A (p less than NS). The incidence of PIA did not differ between the two groups (20.1% vs 6.2%). However, the incidence was higher in patients with residual stenosis of 70% or more than in those with residual stenosis of less than 70% (23.8% vs 2.9%, p less than 0.05). The incidence of reinfarction (re-elevation of CPK) did not differ between the two groups (7.4% in Group T, 6.2% in Group T + A); and neither did the incidence of coronary reocclusion at the time of recatheterization (14.5% vs 3.1%). We concluded that higher degree of residual stenosis at the end of intervention has a greater risk of PIA and reocclusion. Although differences were not statistically significant, the patients treated with ICT followed by PTCA seemed to have lower incidence of PIA and reocclusion compared with those treated with ICT alone, thus having better hospital prognosis.

Aged↗
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↗
PubMed1989

Infection of rabbits with Sendai virus.

Rabbits were either inoculated with Sendai virus (SV), strain MN, or caged with virus-inoculated rabbits on the same day of the viral inoculation, and examined for viral shedding and detection of viral antigens in the respiratory tract, histopathologic changes, and serum antibodies. Infectious virus was recovered from nasal swabs at postinoculation day (PID) 3 and disappeared by PID 10. Viral antigens were detected by immunofluorescence in epithelial cells of the nasal cavities, but not of the trachea and lungs from PID 3 to PID 10, and antibodies were detected after PID 7. Rabbits had no clinical manifestations and only exhibited a moderate increase in goblet cells of the nasal epithelium. In the transmission study, virus was recovered from one of three uninoculated rabbits at postexposure day (PED) 10 and antibodies were detected at PED 15 in the same rabbit. These data suggest that, although viral multiplication was limited to the nasal epithelium, laboratory rabbits are susceptible to Sendai virus infection.

Animals↗
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↗