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Biomedical subjects

Y Imai

Publications and source records attributed to Y Imai.

At least 955 records · Page 53Linked to original sources
PubMed1989

A morphological and immunohistochemical study of lymphoid germinal centers in synovial and lymph node tissues from rheumatoid arthritis patients with special reference to complement components and their receptors.

Rheumatoid arthritis (RA) is one of the immune complex (IC) diseases in which lymphoid germinal centers (GCs) are found in the synovial tissue. Simultaneously, patients with RA often show swelling of lymph nodes. The morphology and function of the lymph-node GCs in patients with RA is not clear. The aim of this study was to evaluate the differences in morphology and immunoreactions to complement (C) components, their receptors, and IgM-rheumatoid factor (RF) between synovial GCs and lymph-node GCs in RA. Furthermore, the relationship between these immunoreactive substances and follicular dendritic cells (FDCs) in GCs was investigated. The tissues examined were 41 RA synovial specimens, seven RA lymph nodes with massive lymphadenopathy, and 10 non-RA lymph nodes. The number of synovial GCs was relatively decreased in comparison with lymph-node GCs in RA, and the diameter of each synovial GC was smaller than that of each lymph-node GC. The synovial GCs were edematous and less cellular, and moreover, those from RF-seronegative cases were smaller than those from RF-seropositive cases. On the other hand, the lymph-node GCs in RA were larger, more cellular and hyperplastic, but contained more tingible-body macrophages (TBMs) and neutrophils. In the GCs of both synovial tissues and lymph nodes in RA, early C components (C1q, C4, C3c, C3d), IgM-RF, and C3b receptor (C3bR) and C3d receptor (C3dR) were expressed as a lacy network by light microscopy, and were demonstrated on the surfaces of FDCs and lymphocytes, and in the intercellular spaces by electron microscopy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Modulation of tryptophan hydroxylase activity by phospholipids: stimulation followed by inactivation.

The activity of tryptophan hydroxylase from the rat brainstem was stimulated rapidly three- to fourfold by the addition of phosphatidylinositol or phosphatidylserine. However, the activity of the enzyme once stimulated was decreased gradually by subsequent incubation with the phospholipid at 37 degrees C, reaching a level below the original activity after 1 h of incubation. The presence of ferrous ion almost perfectly protected the enzyme against this phospholipid inactivation. The activity of the enzyme inactivated by incubation with the phospholipid was not only restored, but also increased further by incubation at 37 degrees C with ferrous ion and dithiothreitol. Gel filtration analysis revealed that the enzyme stimulated by phosphatidylinositol was eluted in a void volume together with the phospholipid vesicles, but the enzyme inactivated by incubation with phosphatidylinositol was eluted at a later region apart from the vesicles. These results, taken together, suggest the possible involvement of cellular membranes in the regulation of tryptophan hydroxylase in the central nervous system.

Animals↗
PubMed1989

Straddling tricuspid valve without a ventricular septal defect.

A four year old girl with pulmonary atresia had a straddling tricuspid valve without an interventricular communication. The overriding tricuspid valve had two orifices, which connected with the right and the left ventricles. Valve tissue separated both orifices and was firmly connected to the crest of the ventricular septum, thus sealing off the expected interventricular communication. Surgical correction was performed and the outcome was satisfactory.

Child, Preschool↗
PubMed1989

Prostate: MR imaging with an endorectal surface coil.

An endorectal surface coil has been developed to obtain high-resolution magnetic resonance images of the prostate. The probe consists of a surface coil mounted on the inner surface of a balloon. The balloon is concave to ensure tight seating against the prostate. The coil has been used in 15 patients with biopsy-proved prostatic carcinoma and in two healthy volunteers. The axial images were obtained with a 12-16-cm field of view and a 3-mm section thickness. Compared with images obtained with a body coil, the surface coil images better demonstrate prostatic anatomy and pathologic conditions.

Humans↗
PubMed1989

Role of vasopressin in cardiovascular response to central cholinergic stimulation in rats.

The cardiovascular effects of centrally administered cholinomimetics were examined in conscious Long-Evans and Brattleboro rats. Carbachol (1 microgram/kg) or physostigmine (50 micrograms/kg) induced a long-lasting increase in blood pressure and a decrease in heart rate in Long-Evans rats whereas no bradycardia was observed in Brattleboro rats, and the pressor response was significantly less than that in Long-Evans rats. The cardiovascular responses to nicotine (30 micrograms/kg) in Brattleboro rats were not different from those in Long-Evans rats. Intravenous vasopressin antagonist, d(CH2)5Tyr(Me) arginine vasopressin, significantly attenuated the pressor response and eliminated the bradycardic response to carbachol in Long-Evans rats. However, the pressor response to carbachol in Brattleboro rats was still significantly less than that in Long-Evans rats treated with vasopressin antagonist. Intravenous phentolamine partially inhibited the pressor response to carbachol in Long-Evans rats and completely eliminated it in Brattleboro rats. Combined intravenous treatment with phentolamine and vasopressin antagonist completely eliminated the pressor response to carbachol in Long-Evans rats. Centrally administered methylatropine eliminated either the hypertensive or bradycardic response to carbachol in Long-Evans rats. These results indicate that the pressor and bradycardic response to carbachol or physostigmine is mediated by the central muscarinic receptor mechanism. Hypertensive response to intracerebroventricularly administered carbachol in normal rats is mediated both by an increase in central sympathetic outflow and in circulating vasopressin. The bradycardia seems to be mediated mainly by vasopressin.

Animals↗
PubMed1989

Increase in plasma noradrenaline concentration after the administration of phentolamine in the patients with "latent" left-sided heart failure.

We measured increments of peripheral venous pressure induced by dynamic leg exercise (delta VP) in 10 healthy subjects (Group C) and 70 patients with heart diseases which primarily affect the left-side of the heart. None of the subjects showed apparent symptoms of left- or right-sided heart failure. The patients were divided into 2 groups on the basis of delta VP, namely, Group N (delta VP less than 35 mmH2O, n = 30, normal reaction) and Group H (delta VP greater than or equal to 35 mmH2O, n = 40, abnormal reaction). We measured the increments of plasma concentrations of noradrenaline (delta NAPH) and adrenaline (delta APH) with infusion of phentolamine (PH). Parallel studies with nitroglycerin and prazosin supplied strong evidence that delta NAPH was brought about mainly by the blockade of alpha 2-receptors at the sympathetic nerve terminals. Thus, we estimated the degree of sympathetic nerve activity from the central nervous system by opening using PH the negative feed-back loop for noradrenaline (NA) release at the sympathetic nerve terminals, and this degree of sympathetic nerve activity was compared with the degree of delta VP. The results obtained were 1) there was a rough overall correlation between delta VP and delta NAPH in the subjects of Groups C, N and H, and 2) delta NAPH was significantly higher in Group H than in Groups C and N. These results suggest that much reliance can be placed on the measured increment of plasma NA concentration in response to the administration of PH in assessing the degree of enhanced sympathetic nerve activity in the patients with "latent" left-sided heart failure.

Adult↗
PubMed1989

Calcitonin gene-related peptide in the human hypothalamus.

Calcitonin gene-related peptide (CGRP)-like immunoreactivity (LI) in the human hypothalamus was investigated by radioimmunoassay and by immunocytochemistry. CGRP-LI was detected from two hypothalami obtained at autopsy (2.1 and 7.0 ng/g wet tissue) by radioimmunoassay. Reverse phase high performance liquid chromatography revealed that most of the CGRP-LI in the human hypothalamus was eluted in an identical position with synthetic human CGRP. For immunocytochemistry, human hypothalami obtained at autopsy were fixed and cryostat-sectioned at 40 microns. Free floating sections were immunostained with antibody to CGRP. CGRP-immunoreactive cell bodies were found in the supraoptic nucleus, paraventricular nucleus and infundibular nucleus. These findings indicate that CGRP exists in the cell bodies of the supraoptic nucleus, paraventricular nucleus and infundibular nucleus in the human hypothalamus and CGRP may play some roles in the endocrine and other functions of the human hypothalamus.

Aged↗
PubMed1989

Modulation of cardiovascular depressant action of clonidine by pentobarbital anesthesia in rats.

The influence of pentobarbital anesthesia (5 mg/100 g, i.p.) on the cardiovascular depressor effect of clonidine administered intracerebroventricularly (i.c.v.) and intravenously (i.v.) was examined in rats. In conscious rats the hypotensive potency of i.v. clonidine [effective dose of clonidine which induced a decrease in blood pressure of 15 mmHg; ED15 = 7 (micrograms/kg)] is greater than that of i.c.v. clonidine (ED15 = 24.3), while in anesthetized rats that of i.c.v. clonidine (ED15 = 0.7 microgram/kg) was greater than that of i.v. clonidine (ED15 = 3.5 micrograms/kg). Pentobarbital anesthesia potentiated the hypotensive potency of i.c.v. clonidine in conscious rats by 50 times, while it potentiated that of i.v. clonidine only by 2 times. The bradycardic potency of i.v. and i.c.v. clonidine was also potentiated by pentobarbital anesthesia. These pieces of evidence suggest that in conscious rat, the hypotensive action of i.c.v. clonidine is opposed by a centrally mediated hypertensive effect of the drug and that pentobarbital anesthesia suppresses the clonidine sensitive pressor center and so potentiates the hypotensive effect of i.c.v. clonidine.

Anesthesia↗
PubMed1989

Similarity in amplitude of the nocturnal fall in blood pressure in old and young patients with essential hypertension.

The influence of age on the nocturnal fall in blood pressure (BP) was examined in essential hypertensive patients as well as normal subjects. BP was monitored every 5 min for 24 hr by means of a finger volume oscillometric device. Average daytime BP was similar in the 3 age groups [young: less than 40 (years), n = 49, average daytime systolic BP (ASBP) = 132 +/- 20 mmHg, average daytime diastolic BP (ADBP) = 82 +/- 17 mmHg; adult: 40 less than or equal to less than 60, n = 110, ASBP = 127 +/- 19 mmHg, ADBP = 86 +/- 13 mmHg; old: 60 less than or equal to, n = 33, ASBP = 131 +/- 17 mmHg. ADBP = 83 +/- 11, mean +/- S.D.]. The nocturnal fall in BP was observed in all age groups and its amplitude (delta BP = average daytime BP - average nighttime BP) in the old patients (delta SBP = 13 +/- 11 mmHg, delta DBP = 10 + 8 mmHg) was similar to that in the young patients (delta SBP = 11 +/- 8 mmHg, delta DBP = 10 +/- 8 mmHg). The results suggests that information on the nocturnal behavior of BP is valuable in treating aged essential hypertensives to prevent cerebral and/or myocardial ischemia during sleep.

Adolescent↗
PubMed1989

Comparison of immunoreactive renin and plasma renin activity in human plasma.

Measurement of immunoreactive plasma renin concentration (PRC) using direct radioimmunoassay (RIA) was compared with the common procedure, measurement of plasma renin activity (PRA). The sensitivity of the PRC assay was 5 pg/ml. In 67 normal subjects aged 45.2 +/- 1.2 year, the mean PRC value was 17.0 +/- 0.9 pg/ml in the recumbent position and 38.0 +/- 5.4 pg/ml in the upright position. In patients with high renin essential hypertension and renovascular hypertension, discrepancies were observed between changes in PRA and PRC at 60 min after the administration of captopril. In a patient with Bartter's syndrome PRC was markedly elevated (393 pg/ml) and the changes in PRA and in PRC after captopril were very different (452% vs. 1249%). In all 10 cases of primary hyperaldosteronism PRC was less than 5 pg/ml. The correlation coefficient between PRC and PRA was 0.85 (n = 227, p less than 0.01). The slope of the regression line between PRA and PRC decreased in proportion to PRC values. Direct RIA for PRC is likely to be useful for the determination of plasma active renin when renin levels are high or substrate concentrations are abnormal. Moreover, the combined use of PRA and PRC measurements might be useful in assessing abnormalities in renin substrate concentration as well as in PRC.

Adolescent↗
PubMed1989

The circadian variation of blood pressure and heart rate in patients with hyperthyroidism.

The circadian variation of blood pressure (BP) and heart rate (HR) was examined in 18 normal subjects, 15 patients with essential hypertension treated with beta-blockers and 21 patients with hyperthyroidism. Most of the patients with hyperthyroidism were also treated with beta-blockers. The 24 hr BP was measured with an ambulatory blood pressure monitoring device (UBP-100) every 5 min. A nocturnal fall in BP and HR was observed in the patients with essential hypertension treated with beta-blockers and the patients with mild to moderate hyperthyroidism as well as normal subjects. On the other hand, in patients with severe hyperthyroidism the nocturnal fall was observed in HR alone, and the fall was small in its amplitude. There was a significant negative correlation between triiodothyronine (T3) level and percentage amplitude of the nocturnal fall in systolic BP (n = 21, r = -0.5, p less than 0.01). However, this relation was not significant in diastolic BP and HR. These results indicate that excess thyroid hormone may modulate the circadian variation of BP and HR.

Adrenergic beta-Antagonists↗
PubMed1989

Passive transepithelial cationic fluxes across the frog skin under short-circuit conditions.

The short-circuit current (Isc) across the frog skin in the steady state reflects the active Na+ transport. Inhibition of the Na+-K+ pump by ouabain causes slow decay of Isc. It has been suggested that this slow ouabain effect on Isc could be due to the asymmetric ionic permeations of frog skin. That is, Na+ flux at the apical membrane and K+ flux at the basolateral membrane transiently generate the transepithelial cationic fluxes and are measured as the Isc even under the condition of active Na+ transport arrest. However, this hypothesis on the transient Isc has not been studied experimentally. In the present study, transient inward and outward Isc were observed alternately even after pump arrest by changing the ionic compositions of the bathing solutions in a Ussing's chamber. The time constant of Isc decay was 20-30 min. The Isc responses were quicker and stronger on the isolated epithelia than on the whole skin. Both Isc responses were blocked by amiloride, a Na+ channel blocker. Measurements of the ionic composition of isolated epithelia under experimental conditions indicate that the passive Na+ flux across the apical membrane and the passive K+ flux across the basolateral membrane cause both transient inward and outward Isc under the ouabain-treated condition of frog skin.

Animals↗
PubMed1989

[Study on fatigue toughness of dental materials. 1. Compressive strength on various luting cements and composite resin cores].

In this study, we investigated compressive strength of various luting cements and composite resin cores in both dry and wet condition, and then influences of repeating load on compressive strength in wet condition of distilled water at 37 degrees C. As frequency of repeating load increased, compressive strength of all materials decreased. It means that the repeated load cycling test used in this study is adequate for evaluating durability of various dental materials. The results were as follows: 1. In the condition of no loading in both dry and wet condition, resin cement indicated the highest compressive strength of all cements examined and was followed by glass ionomer cement, zinc phosphate cement and polycarboxylate cement. Glass ionomer cement was notably influenced in wet condition. 2. After 10,000 cycles of loading in wet condition, resin cement indicated the highest compressive strength again and was followed by glass ionomer cement, polycarboxylate cement and zinc phosphate cement. In particular, compressive strength of zinc phosphate cement decreased remarkably. 3. In the condition of no loading, visible light-cured composite resin core was superior to chemical one. Visible light one was notably influenced in wet condition. 4. After 10,000 cycles of loading, visible light-cured composite resin core was superior to chemical one.

Composite Resins↗
PubMed1989

Change of intrahepatic expression of hepatitis-B core antigen during the clinical course of type-B chronic hepatitis.

The intrahepatic expression of hepatitis-B core antigen (HBcAg) was investigated in 54 liver biopsy specimens from 24 chronic type-B hepatitis patients, by the peroxidase-anti-peroxidase technique. The HBcAg localization pattern in the hepatocyte correlated with the evolution of serum alanine aminotransferase (ALAT) values. The clinical course were classified into three phases, as follows: pre-exacerbation phase (A phase), with minimal abnormal range of ALAT (40-100 KU) for 6 to 12 months; exacerbation phase (B phase) with elevated ALAT (more than 100 KU) for 3 to 6 months; and post-exacerbation and subsiding phase (C phase) for 3 months after phase B, showing decreased ALAT values. Nineteen of the 54 biopsied specimens belonged to the A phase, 21 to the B phase, and 14 to the C phase. In the A phase the hepatocytic HBcAg was variably expressed as nuclear, cytoplasmic, and membranous in location in the same specimens. In the B phase, HBcAg expression decreased in the nucleus, but increased in the cytoplasmic-membranous pattern. The intrahepatic HBcAg expression in the C phase decreased in all patterns. The mean level of ALAT in cases of cytoplasmic-membranous HBcAg expression was higher than that in cases of nuclear HBcAg expression. Four of six patients who underwent liver biopsies in the A, B, and C phases showed remarkable decreases of cytoplasmic and membranous HBcAg expression in the C phase. These findings suggest that cytoplasmic and membranous localization of HBcAg can be related to both liver cell injury and active inflammatory processes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Ultrastructural localization of Cu, Zn-SOD in hepatocytes of patients with various liver diseases.

The ultrastructural localization of copper, zinc-superoxide dismutase (Cu, Zn-SOD) in the liver of patients with acute hepatitis, chronic hepatitis, liver cirrhosis and alcoholic fatty liver was studied by means of the indirect immunoperoxidase technique. In hepatocytes Cu, Zn-SOD was found to be localized in perinuclear cisternae, rough endoplasmic reticulum (rER), vesicles and Golgi apparatus. The Cu, Zn-SOD was also detected around the lipid droplets in hepatocytes as well as on the cytoplasmic membrane in cases of liver cirrhosis. These findings suggest that Cu, Zn-SOD is produced in the rER in hepatocytes and protects the cells from cellular injury caused by superoxide anion radical in various disorders of the liver.

Endoplasmic Reticulum↗
PubMed1989

Ultrastructural analysis of HNK-1+ cells in human peripheral blood and lymph nodes.

HNK-1 positive (HNK-1+) cells in human peripheral blood and lymph nodes were comparatively analysed by means of immunohistochemistry and immunoelectron microscopy. In peripheral blood, the HNK-1+ cells were grouped into large granular lymphocytes (LGLs), small lymphocytes and intermediate forms, all of which had many fine cytoplasmic processes. Except for smooth-surfaced lymphocytes, they could not be distinguished from helper/inducer T (OKT4/Leu3a) cells and suppressor/cytotoxic T (OKT8/Leu2a) cells. In double staining, HNK-1+T3- cells and HNK-1+T3+ cells could not be clearly distinguished in terms of morphology, although the former contained many LGLs. The HNK-1+ cells in the lymph nodes accumulated in the light zones of the germinal centers (GCs). These cells were small to medium-sized lymphocytes with few electron-dense granules and exclusively co-expressed helper/inducer T cell antigens (HNK-1+T4+). Their cytoplasmic projections were interwoven with those of the follicular dendritic cells which trap immune complexes for a long duration. These configurations suggest that HNK-1+T4+ cells in GCs are engaged in an immunological regulation of germinal center cells. On the other hand, large blastic HNK-1+ cells were scattered outside the GCs and some of them were in the process of mitosis. Furthermore, HNK-1+LGL-like cells with a few large electron-dense granules were rarely seen. These observations indicate that the HNK-1+ cells in the lymph nodes may proliferate outside GCs and differentiate into LGLs with a strong natural killer function.

Adult↗