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Biomedical subjects

K Amano

Publications and source records attributed to K Amano.

At least 271 records · Page 15Linked to original sources
PubMed1988

Preferential infiltration of macrophages during early stages of insulitis in diabetes-prone BB rats.

The subpopulation of lymphoid cells at the different stages of insulitis in BB rats was determined by immunohistochemical techniques with various monoclonal antibodies, including the recently developed OX41, which distinguishes macrophages from T-lymphocytes, OX19 for pan-T-lymphocytes, W3/25 for both helper T-lymphocytes and macrophages, OX8 for cytotoxic T-lymphocytes and natural killer cells, and OX12 for B-lymphocytes. The major population of infiltrated cells found during the early stages of insulitis appeared to be macrophages. This preceded invasion by a mixed population of cells, including both T- and B-lymphocytes and/or natural killer cells. The preferential infiltration of macrophages during the early stages of insulitis strongly suggested that there might be an initial change in the target beta-cells that precedes their immune destruction, although the amplification of immune response by activated T-lymphocytes and natural killer cells at a later stage seemed to be required for the clinical expression of the disease.

Animals↗
PubMed1988

[Phonocardiographic and two-dimensional and pulsed Doppler echocardiographic studies of Still's murmurs].

The prevalence of Still's murmur was examined by phonocardiographic study, and the clinical significance of this murmur was investigated using pharmacodynamic phonocardiography and echocardiography. Still's murmur was present in 224 of 9,478 cases (2.4%) in school children. Its prevalence was 143 in 4,524 (3.2%) in elementary school children and this was significantly greater than that in middle school youngsters who numbered 81 among 4,954 (1.6%) (p less than 0.001). There were neither abnormal findings on two-dimensional echocardiography, nor pathological regurgitant signals on pulsed Doppler examination. After the inhalation of amyl nitrite, Still's murmur was accentuated by 5.3 +/- 3.0 dB, and was louder in the expiratory than in the inspiratory phase by 4.7 +/- 3.5 dB.

Age Factors↗
PubMed1988

[Distribution patterns of hypertrophy at the apical level in patients with giant negative T waves: identification by magnetic resonance imaging].

To clarify the distribution patterns of hypertrophy at the apical level in patients with giant negative T waves (GNT), ECG-gated magnetic resonance imaging (MRI) was performed in 10 patients with GNT and in five normal controls. End-diastolic left ventricular short-axis images at the basal and apical levels were obtained in all subjects. Thicknesses of the septal, anterior, lateral and posterior walls at these two levels were measured and distribution of hypertrophied myocardium (more than or equal to 15 mm) at the apical level was examined. The ratio (R) of the maximal thickness at the apical level over that at the basal level was calculated. In normal subjects, the mean apical wall thickness was 8.7 +/- 1.9 mm. In the GNT group, the wall thickness was always greater than the mean value +3 SD of the normal control, and there were no differences among the four segmental walls. The hypertrophic portions at the apex were circumferential in three, septal-anterior-lateral in two, septal-anterior in two, septal in one, anterior in one and lateral in one. In patients with GNT, the average maximal thickness at the apical level was 19.3 +/- 3.2 mm; by location, four cases in the septum, four in the anterior wall and two in the lateral wall, and the average minimum thickness was 11.7 +/- 3.7 mm; all in the posterior wall. The R was more than 1.3 in nine patients with GNT and less than 1.0 in all normal subjects. In conclusion, there was a variety of patterns of apical hypertrophy, and the R greater than or equal to 1.3 was characteristic in patients with GNT.

Adult↗
PubMed1988

[Correlation of left ventricular outflow obstruction with mitral regurgitation].

Our previous study of mitral regurgitation in obstructive hypertrophic cardiomyopathy suggested that left ventricular outflow obstruction due to systolic anterior motion of the distal residual anterior mitral leaflet may hydrodynamically induce mid-systolic mitral regurgitation. To test this hypothesis, we examined whether drug-induced left ventricular outflow obstruction in dogs might cause mitral regurgitation. Dobutamine, 20-60 micrograms/kg/min, induced the obstruction due to mitral systolic anterior motion with mitral-septal contact in 11 of 18 dogs. Pulsed Doppler and contrast echocardiography demonstrated that mitral regurgitation was concomitantly induced in the 11 dogs. The regurgitation was prominent during mid-systole from the onset to the end of mitral-septal contact. Two-dimensional echocardiography showed reduction of the mitral annular dimension and anterior shifts of the mitral valve coaptation during drug infusion in the 11 dogs. Accordingly, the distal portion of the mitral valve, especially of its anterior leaflet, became residual, and moved anteriorly in early systole and protruded into the outflow tract during mid-systole. Catheter-tip pressure recordings simultaneous with two-dimensional echocardiographic observation revealed that the outflow pressure gradient occurred across the protruding distal residual mitral valve. The onset and the end of the pressure gradient were nearly simultaneous with those of the mitral-septal contact. After cessation of the infusion, the mid-systolic mitral regurgitation disappeared together with the obstruction. These results indicate a close relationship between left ventricular outflow obstruction and mid-systolic mitral regurgitation, and strongly support the hypothesis that the obstruction due to systolic anterior motion of the distal residual anterior mitral leaflet is responsible for mitral regurgitation.

Animals↗
PubMed1988

[Mitral valve prolapse in patients with post-operative atrial septal defect: a preliminary report].

To investigate the clinical significance of mitral valve prolapse (MVP) in patients with atrial septal defect, we investigated 90 patients using various techniques including phonocardiography, mechanocardiography and echocardiography. The examinations were repeated pre- and post-operative periods, and the particular attention was paid on the behavior of the mitral valve motion after surgery. Post-operatively, the incidence of MVP was 56% (50 of 90 patients) compared with the preoperative incidence of 78%. Improvement of MVP was only 24%, and there was no case in which MVP newly developed after surgery. Clinical and laboratory data indicated that the cases with MVP after surgery had larger Qp/Qs, higher pulmonary pressures and larger right ventricular dimension pre-operatively, but had no relationship to the age of surgery and the deformity index of the left ventricle. MVP after surgery was not associated with significant mitral regurgitation.

Adolescent↗
PubMed1988

Diabetic cardiomyopathy: the relationship between 201-thallium myocardial scintigraphic perfusion defect and left ventricular function in asymptomatic diabetics.

To investigate the significance of perfusion defects in asymptomatic diabetics, 40 mildly diabetic men, mean age 49 +/- 9.7 years, without clinical or exercise electrocardiographic evidence of ischemic cardiac disease, were evaluated: 1) sixteen (40%) showed no filling defect (G1). Mild defects (G2) and moderate defects (G3) were observed in 12 and 12, respectively; 2) the percent washout ratio was diminished in none of G1, in 3 of G2 and in 11 of G3; 3) there were no differences in age, duration of diabetes, FBS, HbA1c, serum cholesterol, smoking or BP. Obesity index was greater in G3 (121 +/- 15%, p less than 0.01) compared to G1 and 2 (103 +/- 9%, 108 +/- 9%); 4) the percent fractional shortening by echo was decreased in G2 and G3 (35 +/- 6%, 33 +/- 8%, p less than 0.01) compared to G1 (42 +/- 5%). The systolic time interval was higher in G3 (0.42 +/- 0.09, p less than 0.05) compared to G1 and G2 (0.35 +/- 0.05, 0.36 +/- 0.06); 5) radionuclide ventriculographic studies showed a lower peak filling rate at rest in G2 (2.4 +/- 0.5 EDV/sec, p less than 0.025) compared to G3 and G1 (2.9 +/- 0.6 EDV/sec, 3.2 +/- 0.7 EDV/sec). The rate of increase in cardiac output was significantly lower in G3 compared to G1 and G2 (59 +/- 28%, 96 +/- 49%, 97 +/- 31%, p less than 0.05). These results suggest the possibility of detecting metabolic derangements was myocardial scintigraphic perfusion abnormalities which might be a causal factor of myocardial dysfunction in diabetics.

Cardiomyopathies↗
PubMed1988

[Identification of location of electrode tip during percutaneous retrogasserian glycerol injection (PRGI) with blink reflexes elicited by direct stimulation of trigeminal complex (DBR)].

In order to identify the location of the electrode tip during percutaneous retrogasserian glycerol injection (PRGI), the blink reflex (DBR) following direct stimulation of the trigeminal complex (the gasserian ganglion, trigeminal rootlets, or the 3rd division of the trigeminal nerve) was obtained from 6 patients with trigeminal neuralgia. 1) The waveform of the DBR was very similar to that of the blink reflex (BR) elicited by percutaneous stimulation of the 1st division of the trigeminal nerve. However, the latency of early reflex (R1) as well as late reflex (R2) of the DBR was approximately 2 msec shorter than that of the conventional BR. 2) When the electrode tip was introduced into the gasserian ganglion, the DBR showed the largest response under the same recording condition, whereas the DBR was not recorded when the tip of the electrode was placed into either the arachnoid space or the subdural space. The each DBR response, however, showed the same configuration when the electrode tip was situated at the territory of the 1st, 2nd or 3rd division of the trigeminal nerve within the gasserian ganglion or the trigeminal cistern. 3) The DBR always appeared under the anesthesia with the intravenous administration of 10 mg diazepam and 30 mg pentazocine. 4) Based on the present study, the DBR proved to be an usuful parameter in determining whether the electrode tip is introduced into the trigeminal complex or not, particularly in the case of patients having no reliable sensory response to electrical stimulation.

Aged↗
PubMed1988

[Experimental study of the 6-day subrenal capsule assay by cyclophosphamide pretreatment].

For the purpose to suppress the host immune reaction in subrenal capsule assay (SRCA) using normal immunocompetent mice, the effects of cyclophosphamide (CPM) pre-treatment (CPM 180 mg/kg day-1 s.c.) were compared with cyclosporine A (CSA) treatment (CSA 60 mg/kg s.c. daily). CPM and CSA suppressed host reaction until day 6 and day 12, respectively. However, in the histological evaluation of day 6 tumor, there was no difference between two groups. Mouse serum levels of CPM were measured by a bioassay as indicated by the cytotoxicity against P388 cells, to evaluate its residual activity against implanted tumor. No cytotoxicity was observed in the serum of 36 hr. after CPM injection. The antitumor activities of several chemotherapeutic agents against serially transplanted human esophageal cancer xenograft (IMEs-1) in untreated control group and CPM pre-treated group of SRCA were compared with the subcutaneous transplantation assay in nude mice. In all agents, the drug activities in CPM pre-treated group were similar to that in nude mice assay system. The increase of toxicity in CPM pre-treated group was very light. The immunosuppressive activity of CPM were also tested in 14 clinical samples. CPM suppressed the host reaction satisfactorily in all samples. These results suggest the usefulness of CPM pretreatment for suppressing the host reaction in SRCA.

Animals↗
PubMed1987

Structure and biological relationships of Coxiella burnetii lipopolysaccharides.

Lipopolysaccharides (LPSs) extracted from nine strains of Coxiella burnetii were analyzed for chemical compositions, molecular heterogeneity by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and lethal toxicities in galactosamine-sensitized mice. The structure of a unique disaccharide of hydrolyzed phase I LPS was determined to be galactosaminuronyl-alpha (1-6)-glucosamine (GalNU-alpha (1-6)-GlcN, C12H22N2O10) with an Mr of 354. The Mr of LPSs of C. burnetii intra- and interspecific strains and the content of GalNU-alpha (1-6)-GlcN and two sugars, virenose and dihydrohydroxystreptose, were used as biochemical markers of truncated LPSs. Smooth-phase I LPS contained all three compounds, semi-rough-phase I LPS did not contain virenose, and rough-phase II LPS contained none of the three compounds. These analyses indicate that the intermediate to larger Mr LPSs require the addition of GalNU-alpha (1-6)-GlcN and dihydrohydroxystreptose to obtain the major (10.5 kDa), the intermediate (between 10.5 and 27 kDa), and the minor (23 kDa) LPS bands. The addition of virenose to the major and the minor bands produced the large Mr phase I LPSs. Extreme microheterogeneity in the banding profile ranging in Mr from the 2.5 to 10.5 kDa may be due to unidentified components, while the microheterogeneity in Mr of the 10.5-kDa and larger LPS bands is related to variations in the compounds described here. All of the LPSs were toxic in galactosamine-sensitized mice, albeit they were 100-1000-fold less toxic than Escherichia coli and Salmonella typhimurium endotoxin.

Animals↗
PubMed1987

Surgical treatment of hypertensive intracerebral haematoma by CT-guided stereotactic surgery.

Ninety consecutive cases of hypertensive intracerebral haematoma were treated with CT guided stereotactic evacuation. The patients were composed of 61 males and 29 females, ranging from 42 to 87 years old. The location of haematoma was either in the putamen (59 cases) or in the thalamus (31 cases). The average volume of the evacuated haematoma was 21.4 ml in the putaminal haematoma and 14.0 ml in the thalamic haematoma. Postoperative follow-up study in 46 patients showed good recovery of neurological deficits both in putaminal and thalamic group. Criteria of surgical indication of CT-guided stereotactic evaluation of intracerebral haematoma were advocated based on the author's clinical experience.

Adult↗
PubMed1987

Short latency somatosensory-evoked potentials--direct recording from the human midbrain and thalamus.

Short latency somatosensory-evoked potentials were recorded from the human thalamus and the midbrain during stereotactic operations. Several subcomponents were recognized on the peak of N18. These were recorded with maximal amplitude at the border between the caudal portion of the thalamus and the rostral midbrain. Two positive-negative responses, not previously shown, were observed between P14 and N18. These responses were prominent in the rostral midbrain. These findings indicate that the ascending phase of N18, and the N18 itself, are the compound potential generated in the mesodiencephalic junction.

Brain Mapping↗
PubMed1987

Deficiency of peptidoglycan and lipopolysaccharide components in Rickettsia tsutsugamushi.

Analyses of chemical composition in whole cells of Rickettsia tsutsugamushi were performed and compared with those of the other rickettsiae and gram-negative bacteria. The results indicated that R. tsutsugamushi does not contain detectable amounts of 3-deoxy-D-mannooctulosonic acid, heptose, muramic acid, or glucosamine (less than 2, less than 2, less than 3, and less than 3 nmol/mg, respectively). The microorganism was found to contain four kinds of fatty acids (16:0, 18:0, 18:1, and 18:2), but not hydroxy fatty acids. Furthermore, in analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by silver or Coomassie blue staining, lipopolysaccharide bands were not detected in preparations treated with proteinase K. It is concluded that R. tsutsugamushi has little or no peptidoglycan or lipopolysaccharide.

Bacterial Proteins↗
PubMed1987

[Left ventricular short-axis plane for magnetic resonance imaging: its clinical importance and applications].

Left ventricular short-axis images were obtained by ECG-gated magnetic resonance imaging (MRI) in nine patients with hypertrophic cardiomyopathy and seven patients with chest pain, all of whom had diagnostic cardiac catheterization including angiography. The accuracy and usefulness of the short-axis image in MRI for measuring wall thickness and dimension and for calculating ejection fraction were evaluated. All patients were examined on an examination couch in the right anterior oblique position in optimal positions to obtain the left ventricular long-axis images in the Z-X plane (conventional coronal plane). Next, the paraxial mode was used to obtain the short-axis images by rotating the Y-Z plane (conventional sagittal plane) around the Y axis. The intervals between the trigger on the middle point of the upstroke of the R wave and the 90 degree pulse of saturation recovery spin echo sequence were 40 msec and 340 msec with a 34 msec echo delay time for the end-diastolic and end-systolic images, respectively. Short-axis images in MRI in end-diastole were utilized to measure wall thickness and dimension in patients with hypertrophic cardiomyopathy and the measurements obtained were compared with those of echocardiography. As for calculating ejection fraction in patients with chest pain, the length of the left ventricular long axis (L) was measured using the MRI long-axis image. The intraventricular sectional area at four levels (S1, S2, S3, S4) were measured using the MRI short-axis image in end-diastole and in end-systole. Left ventricular end-diastolic and end-systolic volumes were calculated using the following formula: V = 1/2 X (L -4.5) X S1 + 1.5 X (S1 + S2 + S3) + 1/3 X 1/2 X (L -4.5) X S4. Ejection fraction by MRI was compared with that by cardiac catheterization (single plane, area-length method). The measurements of wall thickness and dimension by MRI correlated well with those by echocardiography (r = 0.97, p less than 0.01). Ejection fraction calculated by MRI correlated significantly with that by cardiac catheterization (r = 0.82, p less than 0.05). We concluded that the left ventricular short-axis image in MRI is satisfactorily accurate for measuring wall thickness and dimension, and useful for evaluating the left ventricular ejection fraction.

Angina Pectoris↗