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Biomedical subjects

K Amano

Publications and source records attributed to K Amano.

At least 235 records · Page 13Linked to original sources
PubMed1990

Cardiac magnetic resonance imaging in evaluation of anatomical structure and function of the ventricles.

Cardiac magnetic resonance imaging (MRI) is being widely employed for evaluation of cardiovascular anatomies and functions. However, the indications for cardiac MRI to obtain information which cannot be obtained using other conventional methods have not yet been determined. To demonstrate of usefulness of MRI in delineating the apex of the left ventricle and free wall of the right ventricle, end-diastolic short axis MRI images were obtained in 20 patients with apical hypertrophy and in 9 normal volunteers. To compare the accuracy of estimations of left ventricular volumes obtained using the modified Simpson's method of MRI with that using the MRI area length method, 19 patients, in whom left ventriculography had been performed, were studied. The apex of the left ventricle was evaluated circumferentially and distribution of hypertrophied muscles was defined. Sixty-five percent of the length of the right ventricular free wall was clearly delineated. Correlation coefficients of the ejection fraction between MRI and angiography were 0.85 with the modified Simpson's method of MRI, and 0.62 with the area length method of MRI. Three themes were chosen to demonstrate good clinical indications for cardiac MRI.

Cardiac Volume↗
PubMed1990

Changes in the mixed venous blood oxygen saturation during the acute phase of myocardial infarction and administration of dobutamine.

Clinical significance of the continuous monitoring of mixed venous oxygen saturation (SvO2) by Catheter Oxymetry System was evaluated in 45 patients with acute myocardial infarction (AMI). Patients with AMI were classified into 4 groups according to Forrester's hemodynamic classification. The mean SvO2 value for each group was 70.4 +/- 4.1% for subset I, 54.7 +/- 6.9% for subset II, 55.8 +/- 9.8 for subset III, and 47.0 +/- 8.0% for subset IV. Subsets II, III, and IV showed significantly low values compared to subset I (p less than 0.01). The relationship between PCW and SvO2 level was expressed by the negative regression line y = -0.8x + 73.8 (r = -0.64, p less than 0.01). The curve representing the relationship between CI and SvO2 level was expressed by the equation y = 53.8 logx + 42.7 (r = 0.68, p less than 0.01). The SvO2 level of the 14 patients who showed a significantly low value of 56.9 +/- 8.2% before administration of 5 micrograms/kg/min dobutamin, increased to a mean value of 66.8 +/- 7.9%, as well as the CI after 60 min. However, PCW demonstrated no pronounced changes because of dobutamine administration. Since the SvO2 level highly correlated to the cardiac pumping function in acute phase of myocardial infarction, polygraphic monitoring of SvO2 was found to be a useful index for evaluating changes in the hemodynamics. It was also a very useful measure in evaluating the effects of dobutamin.

Aged↗
PubMed1990

Studies on autoimmunity for initiation of beta-cell destruction. V. Decrease of macrophage-dependent T lymphocytes and natural killer cytotoxicity in silica-treated BB rats.

Administration of silica, which is selectively toxic to macrophages, to young BB rats resulted in the prevention of insulitis and diabetes. However, the mechanism leading to the prevention of an autoimmune process in silica-treated BB rats is not known. This study was undertaken to investigate the mechanism involved in prevention of insulitis and diabetes. Neonates of diabetes-prone BB (DPBB) rats injected with concanavalin A (ConA)-activated spleen cells from silica-treated DPBB (STDPBB) rats did not develop insulitis or diabetes, whereas DPBB neonates injected with ConA-activated spleen cells from the untreated DPBB rats developed both insulitis and diabetes. Not only was there a decrease of natural killer (NK) cell activity in splenocytes from STDPBB rats, but there was also a significant reduction in the number of immunocytes such as T lymphocytes (helper/inducer and cytotoxic/suppressor) and NK cells. The number of macrophages in both spleen and peripheral blood was significantly decreased in STDP rats compared with untreated DP rats. In contrast to the changes in T lymphocytes and NK cell activity, there was no change in target beta-cells in STDPBB rats with regard to the susceptibility to adoptive transfer of insulitis. It is concluded that the prevention of insulitis and diabetes in STDPBB rats is due to a decrease in macrophage-dependent T lymphocytes and NK cell cytotoxicity.

Animals↗
PubMed1990

Clivus epidural hematoma. Case report.

A rare case of epidural hematoma of the clivus is reported in an 11-year-old girl involved in a traffic accident which caused a severe hyperextension injury. Only one similar case has been reported in the literature. The mechanism for the formation of the hematoma of this region is discussed.

Child↗
PubMed1990

[Blood pressures at work, home and during sleep in patients with essential hypertension: analysis by ambulatory blood pressure monitoring].

Blood pressure (BP) recordings were obtained every 30 min using a noninvasive ambulatory BP recorder during 24 hours in 93 subjects with hypertension. Recordings were analyzed in four different situations: (1) annual check up at the health service center, (2) at work, (3) at home, and (4) during sleep. Subjects with BP higher than 160/95 mmHg in any of the three situations were defined as established hypertensive (n = 36); Subjects with 140-159/90-94 mmHg, as the borderline hypertensive (n = 32); and subjects with BP lower than 139/89 mmHg, as the normotensive (n = 25). Four successive systolic and diastolic BP values were averaged and served as 24-hour BP patterns. Systolic BP over 140 mmHg, diastolic BP over 90 mmHg and mean BP over 107 mmHg were defined as a s-hyperbaric index (s-HBI), d-HBI and m-HBI, respectively. The normotensive group showed a marked decrease of BP after recordings explained by the "white coat phenomenon". The 24-hour recordings in all the three groups showed the highest BP at work and the lowest during sleep. The situational BP changes were generally similar, but the established hypertensive group showed larger BP differences between work and home (SBP 8.8 +/- 9.0 mmHg, 7.8 +/- 8.3 mmHg). For differentiating the three groups, the hyperbaric index was better than the 24-hour average BP. The average home BP showed a good correlation with the 24-hour average BP [SBP: r = 0.94 (p less than 0.01), DBP: r = 0.85 (p less than 0.01)]. Especially, BPs recorded before sleep predicted well the 24-hour average BP. An average of multiple BP measurements before sleep is thought to represent a 24-hour average BP more closely than a conventionally used single recording at home or after awakening.

Adult↗
PubMed1990

[Paradoxical left ventricular blood flow during the isovolumic relaxation period in non-obstructive hypertrophic cardiomyopathy: Doppler and M-mode echocardiographic study].

The left ventricular blood flow pattern during the isovolumic relaxation period was investigated in 17 patients with apical hypertrophy (mean 54 +/- 8 years) and 30 with asymmetric septal hypertrophy without left ventricular outflow obstruction (mean 54 +/- 14 years). Thirty-five age-matched normal subjects served as controls (mean 51 +/- 10 years). All cases were examined by pulsed Doppler echocardiography simultaneously with phonocardiography. In all the control subjects, an apically-directed flow was observed, which occurred simultaneously with the onset of the second heart sound. In contrast, a basally-directed flow was detected during the isovolumic relaxation period in 13 patients (76%) with apical hypertrophy and in 28 (93%) with asymmetric septal hypertrophy. In these cases, an apically-directed flow was often observed before the second heart sound. Standard M-mode echocardiography revealed a significant increase in the left ventricular short-axis dimension at the base during the isovolumic period in patients with hypertrophic cardiomyopathy, while the normal controls showed no significant change. Moreover, peak velocity of the basally-directed flow correlated significantly with the rapidity of dilatation of the basal dimension (r = 0.61, p less than 0.01). Thus, this basally-directed blood flow in the left ventricle during the isovolumic relaxation period may be caused by the asynchronous left ventricular dilatation during the isovolumic period.

Adult↗
PubMed1990

[Chemical analysis and immunochemical characterization of serotype-specific antigens from the strains of Actinobacillus actinomycetemcomitans which were frequently found in the periodontal pockets of the patients of localized juvenile periodontitis].

Serotype-specific polysaccharide antigens of Actinobacillus actinomycetemcomitans ATCC 29523 (serotype a), Y4 (serotype b) and NCTC 9710 (serotype c) were extracted from whole cells by autoclaving. The extracts were purified by chromatography on DEAE-Sephadex A-25 and Sephacryl S-300 columns. The purified polysaccharide antigens formed a single precipitin band with the corresponding anti-a, b or c serum on immunodiffusion. Analysis of component sugars by GLC, HPLC, GLC-MS, NMR together with specific optical rotation data showed that the serotype a antigen consisted of 6-Deoxy-D-talose, the serotype b antigen consisted of L-rhamnose and D-fucose, and the serotype c antigen consisted of 6-Deoxy-L-talose. Structural analysis indicated that these antigens were composed of closely related repeating units, -3)-6-deoxy-alpha-D-Talp-(1-2)-6-deoxy-alpha-D-Talp-(1- (serotype a), -3)-alpha-D-Fucp-(1-2)-beta-L-Rhap-(1- (serotype b) and -3)-6-deoxy-alpha-L-Talp-(1-2)-6-deoxy-alpha-L-Talp-(1- (serotype c). 13C and 1H-NMR analyses suggested that the serotype a and c polysaccharides carried approximately one acetyl group per two sugar residues, although the acetylated position was not identified. In quantitative precipitin inhibition tests, the component sugars showed very low inhibition, whereas the partial hydrolysates of these antigens were effective inhibitors. These results suggest that the serotype-specific antisera recognize larger oligosaccharide units.

Aggregatibacter actinomycetemcomitans↗
PubMed1990

[Studies on antibiotic skin testing].

Commercially available antibiotics for injection are supplied with test ampules. Users are instructed to dissolve them to make 300 micrograms/ml solution for intradermal pretests to avoid allergic reactions. Sometimes this concentration is too low to prevent anaphylactic reactions. In the present study, we tried to find the maximum concentration for the intradermal tests which would have high sensitivity without giving nonspecific, false positive reactions. We investigated intradermal tests with cephalothin (CET) in a patient who suffered from anaphylaxis after drip infusion with CET, although she was judged to be negative to CET by the usual intradermal test prior to the infusion. Her CET skin test was negative at a concentration of 150 micrograms/ml and positive at 300 micrograms/ml 6 weeks after anaphylaxis, but negative at 300 micrograms/ml and positive at 1000 micrograms/ml 4 and 7 years after anaphylaxis. Prick tests were always negative, even with the maximum soluble concentration of CET, 200 mg/ml. Nonspecific reactions to intradermal tests at concentrations as high as 1000 micrograms/ml were examined with 20 kinds of penicillins and cephems in 51 healthy subjects without histories of drug allergies. Very few false positive reactions were observed, except in 5 out of 24 cases with cefotiam. Intradermal tests at 3000 micrograms/ml, however, frequently resulted in nonspecific reactions. We conclude that 1000 micrograms/ml, not 300 micrograms/ml solutions should be used for intradermal tests to prevent allergic reactions to the injection of antibiotics.

Anti-Bacterial Agents↗
PubMed1989

Purification of angiotensin-converting enzyme from human intestine.

Angiotensin-converting enzyme (ACE) activity in the intestinal whole homogenate was showed as three peaks on a column of Sephacryl S-300 HR gel filteration. Over 90% of total ACE activity was found in a soluble fraction separated with an ultracentrifuge of the intestinal homogenate, and the ACE activities were detected as two peaks on the same column. On the other hand, two peaks of ACE activities were found in a membrane-bound fraction of treated with trypsin on the Sephacryl column and confirmed with the two peaks of the soluble fraction, while the fraction extracted with Triton X-100 of the membrane-bound fraction showed only one peak as major peak. All ACE peaks were inhibited by addition of EDTA or captopril and by absence of chloride ion completely. We purified one ACE from the soluble fraction by lisinopril-linked Sepharose 6B affinity column chromatography and Cellulofine GCL-200 gel filteration. This enzyme was a 1323-fold purification and its final recovery was 25%. The molecular weight of this enzyme (180,000) was larger than that of ACE from human kidney (170,000), estimated by 7.5% SDS-PAGE. The Km value of the enzyme for HHL was 2.1 mM. The enzyme activity was competitively inhibited by captopril.

Chromatography, Affinity↗
PubMed1989

Immunochemical and structural characterization of a serotype-specific polysaccharide antigen from Actinobacillus actinomycetemcomitans Y4 (serotype b).

A serotype-specific polysaccharide antigen of Actinobacillus actinomycetemcomitans Y4 (serotype b) was extracted from whole cells by autoclaving. The extract was purified by chromatography on DEAE-Sephadex A-25 and Sephacryl S-300 columns. The purified polysaccharide antigen formed a single precipitin line with anti-type b serum but not with anti-type a serum and anti-type c serum. The antigen was composed of 43.9% L-rhamnose, 49.1% D-fucose, and a trace amount of fatty acid. Methylation analysis, Smith degradation, and optical rotation data showed that the antigen was a polymer consisting of a disaccharide repeating unit, ----3)-alpha-D-fucopyranosyl-(1----2)-beta-L-rhamnopyranosyl-(1----. In quantitative precipitin inhibition tests, D-fucose and L-rhamnose showed very low inhibition, but the partial hydrolysate of the purified antigen was an effective inhibitor, suggesting that the serotype b specific antiserum recognizes the larger oligosaccharide units.

Actinobacillus↗
PubMed1989

Aortic regurgitation associated with hypertrophic cardiomyopathy: a colour Doppler echocardiographic study.

The frequency, severity, and cause of aortic regurgitation were assessed by colour Doppler and cross sectional echocardiography in 87 patients (mean SD) age 57 (12) years) with hypertrophic cardiomyopathy, and 48 age matched controls (57 (8) years). Aortic regurgitant murmurs were recorded in only three of 87 patients and in none of the controls. Colour Doppler echocardiography showed an aortic regurgitant signal in 20 (23%) of the patients and three (6%) of the 48 controls. The colour Doppler signals typical of aortic regurgitation were limited to the left ventricular outflow tract. There were no significant differences between patients with hypertrophic cardiomyopathy with and without aortic regurgitation in terms of age (59 years v 56 years), blood pressure (140/84 mm Hg v 136/80 mm Hg), aortic diameter (34 mm v 33 mm), or frequency of calcification of the aortic valve (15% v 10%) and of systolic anterior motion of the mitral valve with mitral-septal contact (25% v 16%). On cross sectional echocardiograms, the degree of septal protrusion into the left ventricular outflow tract during systole was significantly more prominent (15 v 10 mm), and the portion of the basal septum that protruded most deeply into the left ventricular outflow tract was significantly closer to the aortic annulus in patients with aortic regurgitation than in those without it (11 v 14 mm). Mild aortic regurgitation was found in almost a quarter of patients with hypertrophic cardiomyopathy. The regurgitation was related to the morphological abnormality of the left ventricular outflow tract.

Adolescent↗
PubMed1989

[Antiarrhythmic action of beta-blocking agent in patients with mitral valve prolapse having premature ventricular contractions].

To investigate the origin and evaluate the effect of one of the most potent beta blocker, carteolol, on premature ventricular contractions (PVCs) in patients with mitral valve prolapse (MVP), 21 patients (35 +/- 12 years; mean +/- SD) including 10 with PVCs were studied by simultaneous electrocardiography and echocardiography before and after intravenous injection of carteolol. In all 21 MVP patients including 10 MVP patients with PVCs, carteolol (6 micrograms/kg/2 min, i.v.) caused significant decrease in systolic and diastolic blood pressures and in heart rate. Carteolol markedly (25% or more) reduced frequency of PVCs in four of the 10 patients, but no significant changes in five, and PVCs were increased in frequency in the remaining one. However, in all 21 MVP patients, carteolol did not change left ventricular end-diastolic and end-systolic dimensions, and the degree of MVP nor mitral regurgitant areas evaluated by color Doppler echocardiography. These results were exactly the same as those of the patients with PVCs. In conclusion, intravenous injection of beta-blocker, carteolol, reduced PVCs in 40% of the MVP patients with PVCs, but this antiarrhythmic action is not related to the degree of mitral valve prolapse, or mitral regurgitation evaluated by Doppler method.

Adolescent↗
PubMed1989

[Prevalence of mitral valve prolapse in patients with premature ventricular contractions and the relationship between the prolapse and the types of premature contractions].

To assess the prevalence of mitral valve prolapse (MVP) in patients with premature ventricular contractions (PVCs), 109 patients with PVCs (M: 69, F: 40, 42 +/- 20 years; mean +/- SD) and 50 control subjects (M: 38, F: 12, 47 +/- 10 years) were studied by echocardiography. MVP was diagnosed by two-dimensional echocardiography. The criterion for mitral valve prolapse by two-dimensional echocardiography is extension of the mitral leaflet to the left atrial side beyond the plane of the mitral annulus. In addition, 60 patients with PVCs were examined by 24-hour Holter ECG and scored by the Lown's classification. Results were as follows: 1) MVP was detected more frequently in patients with PVCs than in the control subjects (22/109, 20% vs 3/50, 6%, p less than 0.05) by echocardiography. 2) PVC patients with MVP were significantly younger than patients without MVP (34 +/- 14 vs 47 +/- 21 yrs, p less than 0.05), but there were no significant differences between these two groups as to sex, left atrial diameter and left ventricular dimension. 3) The 24-hour Holter ECG revealed that the high grade PVCs (Lown grade III & IV) was more closely related to the absence of MVP (20/45, 44% vs 4/11, 36%), though this trend did not reach statistical significance. It was suggested that MVP is not a major determinant of PVC, and life-threatening arrhythmias are more likely related to cases without MVP.

Adult↗
PubMed1989

[Mitral valve prolapse in patients with surgically-closed atrial septal defect].

To evaluate the prevalence, causes and clinical significance of mitral valve prolapse (MVP) associated with surgically-closed atrial septal defect (ASD), 90 patients (M: 41, F: 49) were studied using two-dimensional and color-coded Doppler echocardiography. Among the 90 patients, preoperative echocardiograms were available in 27. MVP was found in 21 of the 27 patients (78%) preoperatively, but it was found in 59% (16/27) postoperatively. In total, MVP was detected in 50 of the 90 patients (56%) postoperatively. The postoperative MVP group had higher pulmonary-to-systemic flow ratios (3.6 +/- 1.9 vs 2.8 +/- 1.1, p less than 0.05) and higher mean pulmonary arterial pressures (21 +/- 11 vs 13 +/- 5 mmHg, p less than 0.01) at the time of surgery. Between the two groups with or without MVP postoperatively, there was no difference (p less than 0.05) in age at surgery, the postoperative duration and left ventricular (LV) deformity index both in pre- and postoperative states. A mitral regurgitant (MR) murmur was recorded in seven patients postoperatively. However, only two had clinically severe MR. It was concluded that MVP is frequently detected in patients with closure of ASD and it is related neither to degree of the LV deformity nor to age at operation; rather, it is related to the severity of the preoperative hemodynamic state. Clinically significant MR is rare in the postoperative period.

Adolescent↗