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Biomedical subjects

H Imai

Publications and source records attributed to H Imai.

At least 523 records · Page 29Linked to original sources
PubMed1985

Intimal cell mass-derived atherosclerotic lesions in the abdominal aorta of hyperlipidemic swine. Part 1. Cell of origin, cell divisions and cell losses in first 90 days on diet.

Atherosclerotic lesions may originate and develop in a variety of ways. In this study we are focusing our attention on atherosclerotic lesions arising in normally occurring intimal cell masses (ICM) in the abdominal aortas of hyperlipidemic (HL) swine. Times chosen for study were 0, 14, 49 and 90 days on HL diet; mash-fed swine were used as controls. Total numbers of cells in the ICM of HL and mash swine were similar at 14 and 49 days; by 90 days the number of cells had increased dramatically in the HL swine to 8-fold greater than control values. Changes present at 49 days and thus preceding increase in cell numbers included extensive intracellular lipid accumulation with by count nearly half of the ICM cells involved and elevated tritiated thymidine labeling indices (LI) 4-fold greater than control. Differential cell counts by transmission electron microscopy were made on the ICM lesions in the HL swine at 49 and 90 days. More than 95% of all cells were smooth muscle cells (SMC), with relatively few monocytes being present. Calculations from the LI and total cell counts showed that the entire increase in cell numbers could be accounted for by divisions among the resident SMC in the ICM. Further calculations suggested that cell losses (deaths) from the ICM were minimal. Scanning electron microscopy studies reported elsewhere revealed no loss of endothelial integrity. The results suggest: (1) that the lesions arise by stimulation of the resident SMC in the ICM to hyperplastic activity, (2) that the role of monocytes in the early development of these lesions is minimal if any, (3) that in view of the intact endothelium platelets are not likely to play an important role, (4) that ICM cell death is not a major factor, (5) that the most likely candidate for the cell growth stimulatory role (? mitogen) is some component(s) of the excess lipid that accumulates in the ICM.

Animals↗
PubMed1985

Spontaneous glomerular IgA deposition in ddY mice: an animal model of IgA nephritis.

It was found that ddY mice derived from non-inbred dd-stock mice brought from Germany before 1920 and then raised in Japan developed spontaneously IgA dominant deposition in the glomerular mesangium. In this report we give a detailed natural history of the renal pathology of those mice. The animals were fed rodent laboratory chow and sacrificed in groups of 9 to 10 at 6, 10, 16, 24, 28, 40, and 59 weeks of age. The bladder urine was analyzed, serum immunoglobulins were measured, and the kidney specimens were evaluated with light, fluorescent, and electron microscopy. Proteinuria was (plus) to (2 plus) after 28 weeks and (2 plus) to (3 plus) at 59 weeks with negative hematuria. Mesangial cell proliferation began to appear at 16 weeks, then progressed to a definite proliferative glomerulonephritis. At 59 weeks an additional increase of the mesangial matrix occurred. By immunofluorescence, there were IgG of (2 plus), IgM (plus) to (2 plus), IgA (plus) and C3 (plus) in the glomeruli until 28 weeks. However, IgA started to be dominant at 40 weeks and the glomerular pattern was IgA (2 plus) to (3 plus), IgG (plus) to (2 plus), IgM (+/-) to (plus) and C3 (plus) to (2 plus) at 59 weeks. Polyclonal IgA and IgG2a among immunoglobulins steeply rose at 40 weeks, and at 59 weeks IgA increased by 850%, IgG2a by 280%, IgG1 by 170%, IgG2b by 90%, and IgM by 60%, as compared with their level at 6 weeks. There was no anti-nuclear antibody. Thus, ddY mice, at least after the age of 40 weeks, can be used as a new animal model for spontaneous IgA nephritis. The probable origin of IgA is also discussed.

Animals↗
PubMed1985

IgM monoclonal gammopathy accompanied by nodular glomerulosclerosis, urine-concentrating defect, and hyporeninemic hypoaldosteronism.

A 54-year-old male had monoclonal IgM-kappa light chains in the serum and free monoclonal kappa light chains in the urine. Renal biopsy revealed nodular glomerulosclerosis associated with the accumulation of kappa light chains. Isolated microscopic hematuria was present for over 1 year. He also showed a defect in urine concentration for which the light chains deposited along the basement membrane in the inner medullary tubules were judged to be responsible. When the glomerular filtration rate fell to 30 ml/min, the syndrome of mild renal failure, decreased potassium excretion, and hyporeninemic hypoaldosteronism developed, suggesting that kappa light chain nephropathy is a cause of this syndrome. Chemotherapy appeared to have some beneficial effects in maintaining renal function.

Aldosterone↗
PubMed1985

5-Hydroxytryptamine innervation of vessels in the rat cerebral cortex. Immunohistochemical findings and hydrogen clearance study of rCBF.

The role of the central 5-hydroxytryptamine (5-HT) neuron system in cerebral microcirculation of the rat was examined by immunohistochemical and hydrogen clearance methods. Immunohistochemical studies demonstrated 5-HT-immunoreactive nerve fibers along intraparenchymal blood vessels (arterioles, capillaries, and venules). Ultrastructural observation revealed that 5-HT-immunoreactive terminal boutons (0.3 to 1.0 micron in diameter) made contact with the basement membrane of the capillaries. After an intracerebral injection of 5,7-dihydroxytryptamine (5,7-DHT), a neurotoxin to the 5-HT neuron system, no 5-HT-immunoreactive nerve fibers were found around the injection site with immunohistochemical techniques. With the hydrogen clearance method, the 5,7-DHT-injected cortex showed no significant change in regional cerebral blood flow (rCBF) in the presence of normocapnia, but a significant increase in rCBF with hypercapnia, compared with the untreated cortex. These facts strongly suggest that the central 5-HT neuron system has an important role in carbon dioxide reactivity of the cerebral blood vessels.

Animals↗
PubMed1985

[Magnetic resonance imaging of cardiovascular thrombi].

Magnetic resonance imaging (MRI) was performed for 10 patients with cardiovascular thrombi using a 0.1-Tesla resistive type apparatus (ASAHI MARK-J). In all cases thrombi were clearly imaged by NMR and their shapes closely resembled those imaged by X-ray CT. Mural thrombi located within left ventricular aneurysms of two patients with old anteroseptal myocardial infarction were semilunar in form. A mural thrombus in the right ventricle of a patient with cardiovascular Behcet's disease was also clearly imaged. Mural thrombi within the enlarged left atrium of two patients with mitral valve stenosis and insufficiency were clearly demonstrated in both cross- and longitudinal sections. In three patients with thoracic aortic aneurysm, mural thrombi were recognized within the local dilatations of the aorta. In two patients with dissecting aortic aneurysm, mural thrombi were visualized within false lumen using MRI. Mean T1 values and standard deviations for the left ventricular cavity, the left ventricular wall, and the thrombi were 639 +/- 49, 349 +/- 17 and 316 +/- 84 msec, respectively. Mean T1 values of the thrombi were usually shorter than those of the left ventricular wall. Some supposedly fresh thrombi had longer T1 values, however.

Adult↗
PubMed1985

[Magnetic resonance imaging of cardiovascular diseases: advantages of coronal and sagittal planes].

The usefulness of coronal and sagittal sections of the cardiovascular system by magnetic resonance imaging was evaluated. Coronal, sagittal and transverse spin echo scans using ECG-non-gating and gating during systole and diastole were performed for five normal volunteers, 91 with heart diseases (25 valvular disease, 28 ischemic heart disease, 14 cardiomyopathies, 14 congenital malformations, four pericardial diseases, and six others) and 32 patients with aortic abnormalities (17 aneurysms, 10 dissections and five others) using a 2.5 KGauss unit. Cardiac gating necessitated six to eight min per scan, but it was mandatory to obtain clear images of the details. On the other hand, in most of the aortic abnormalities, diagnostic images were obtained by the ECG-non-gating technique which required only about 2.5 min per scan. Coronal and sagittal sections were useful for estimating the entire shape and size of each cardiac chamber and intracardiac thrombi, the extent of postinfarctional wall thinning and cardiac aneurysms, and hypertrophy or narrowing of both the ventricular outflow tracts and apex. These planes were particularly useful, and more contributory than transverse planes for detecting inferior myocardial damage such as infarction. A few coronal and sagittal scans were sufficient to diagnose extensive lesions of the aorta, such as atherosclerosis, dissections and the aortitis syndrome. Local lesions such as coarctation, supravalvular aortic stenosis, annulo-aortic ectasia and aneurysm, especially those originating in the inferior wall of the aortic arch were easily discovered. Since the main arteries, such as the innominate, left common carotid, left subclavian and renal arteries, were clearly demonstrated by coronal images, coronal scans were considered more useful than transverse ones for observing the relationship between these arteries and dissections or aneurysms of the arch and of the abdominal aorta.

Coronary Disease↗
PubMed1985

[Positron computed tomography for myocardial uptake of N-13 ammonia in patients with hypertrophic cardiomyopathy: a preliminary study].

In the present study, positron computed tomography (PCT) was used to evaluate the myocardial uptake of N-13 ammonia in patients with hypertrophic cardiomyopathy (HCM). Eight subjects including two normal persons, four patients with HCM, and two with old myocardial infarction (OMI) were selected for the study. N-13 ammonia was administered intravenously as a bolus and, commencing with the tracer injection, serial 30-second PCT scans were performed. The results were summarized as follows: The first scan exhibiting cardiac blood pool images revealed a reduced left ventricular cavity in the HCM subjects. After clearance of N-13 from the cardiopulmonary vasculature, the left ventricular myocardium was clearly visualized and an increased myocardial mass with characteristic morphology was demonstrated in the HCM subjects. Detailed analysis of the time-activity curves of the blood pool and myocardium derived from these serial scan images disclosed two uptake phases in the uptake mode of N-13 ammonia. In the initial phase within three minutes, the myocardial uptake of N-13 was rapid in the normal and OMI subjects, whereas its significant delay was observed in the HCM subjects. This may reflect an abnormal initial extraction of N-13 ammonia in the HCM patients compared with the other subjects. Subsequently, in the second phase, which was characterized by a gradual increase of N-13 in the myocardium, the HCM subjects revealed higher uptake ratios than did the others. This may indicate an increased extraction of metabolites of N-13 ammonia during the second phase. These preliminary results underscore the usefulness of dynamic PCT with N-13 ammonia for the assessment of HCM.

Adult↗
PubMed1984

Pupillo-motor areas in the rabbit visual cortex.

Pupillo-motor areas in the visual cortex of the rabbit were studied. Electrical stimulation of the rabbit visual cortex induced pupillary constriction or dilation. The low threshold area (0.5-1.0 mA) for pupillary dilation was in the form of a narrow band extending rostro-caudally along the boundary between the striate cortex (VI) and the occipital cortex (VII), where the binocular area of the visual field is represented. The pupillo-constrictory cortical points were also identified in the caudal part of the splenial gyrus (lateral part) and the pupillo-dilator points in the rostral part of the gyrus (lateral part).

Animals↗
PubMed1984

Direct, simultaneous determination of propranolol and its 4-hydroxy metabolite by liquid chromatography.

Propranolol and its active 4-hydroxy metabolite are determined by direct injection of spiked plasma samples onto a protein-coated ODS liquid chromatographic column. The recovery of propranolol and the 4-hydroxy metabolite is essentially quantitative and the reproducibility is good. The reproducibility and simplicity may be superior to the conventional HPLC analyses which include pretreatment, i.e., solvent extraction or deproteinization.

Chromatography, Liquid↗
PubMed1984

Afferents to the cortical pupillo-constrictor areas of the cat, traced with HRP.

Afferents of the cortical pupillo-constrictor areas (PCAs) of the cat were studied using the horseradish peroxidase method. PCAs receive heavy cortical inputs from areas 7, 19, 21, the lateral suprasylvian area, the splenial visual area, and subcortically from the claustrum, the intralaminar nuclei, the pulvinar-lateral posterior nuclear complex.

Afferent Pathways↗
PubMed1984

Mosaicism in female hybrid hares heterozygous for glucose-6-phosphate dehydrogenase. VI. Production of monotypism in the aortas of 4 of 10 mosaic hares fed cholesterol oxidation products.

The normal aortic tissue of black women heterozygous for glucose-6-phosphate dehydrogenase (G-6-PD) usually consists of two cell phenotypes (mosaicism). By electrophoresis two G-6-PD types are demonstrated (ditypism). Advanced atherosclerotic lesions from such women not infrequently yield samples displaying only one G-6-PD type (monotypism). Possible causes for the monotypism include (1) monoclonal origin of the lesion and (2) selective growth and/or survival advantage of one phenotype over the other. We have been attempting to produce monotypism in the aortas of a hybrid hare model that displays G-6-PD mosaicism in the normal state. In the current study 14 G-6-PD mosaic hares were fed a high-cholesterol diet for 6 to 17 months. All developed extensive moderately severe (as compared to humans) atherosclerotic lesions. No monotypic samples were found. Ten hares were fed (in addition to the standard high-cholesterol diet) small doses of one of two cholesterol oxidation products (25-hydroxycholesterol or triol) for 6 to 21 months. Four of the ten developed monotypic foci in either atherosclerotic lesions or normal aortic tissue or both. The reason for giving the oxidation products was because they are cytotoxic for cells in vitro and one (25-hydroxycholesterol) had been shown to be more toxic for one phenotype than the other with cultured fibroblasts from the mosaic hares (not infrequently resulting in the culture becoming monotypic). We suggest that the monotypism observed in vivo was probably produced by a mechanism similar to that operating in vitro.

Animals↗
PubMed1984

A light and electron microscopic immunohistochemical study of vasoactive intestinal polypeptide- and substance P-containing nerve fibers along the cerebral blood vessels: comparison with aminergic and cholinergic nerve fibers.

Vasoactive intestinal polypeptide (VIP)- and substance P-containing nerve fibers were observed in the cerebral blood vessels using an immunohistochemical technique. VIP-containing nerve fibers distributed in a spiral pattern, similar to that of muscle cells. Under electron microscopic observation, VIP-immunoreactive terminals lay close to a muscle cell in the inner layer of the adventitia. In contrast, substance P-containing nerve fibers showed a meshwork pattern in the outer layer of the adventitia. Using both acetylcholinesterase (AChE) staining and VIP immunohistochemistry, AChE-positive and VIP-immunoreactive nerve fibers revealed almost the same distribution in the same specimen. The present data suggest that VIP-containing nerve fibers may play a role in the smooth muscle control of the blood vessels, whereas substance P-containing nerve fibers may not take part in muscle control.

Animals↗