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M Fujiwara

Publications and source records attributed to M Fujiwara.

At least 415 records · Page 23Linked to original sources
PubMed1990

Changes in signal transduction in Alzheimer's disease.

We studied the signal transduction system including the receptor and protein kinase C (PKC) in Alzheimer's disease (AD) brains. We used 3H-TCP as a ligand for the NMDA receptor-ion channel complex. The total concentrations of 3H-TCP binding sites were significantly reduced in AD frontal cortex. 3H-TCP binding sites spared in AD brains retained the affinity for the ligand and the reactivity to NMDA, L-glutamate, and glycine. We utilized antibodies to assess the degree of involvement of different PKC isoforms in AD. The concentration of PKC (beta II) was lower in AD particulate fractions and higher in AD cytosol fractions. Immunocytochemical studies revealed reduced numbers of anti-PKC (beta II)-immunopositive neurons. Anti-PKC (alpha) faintly stained entire plaques and surrounding glial cells. Anti-PKC (beta I) stained dystrophic plaque neurites. Anti-PKC (beta II) stained the amyloid-containing portions of plaques. These results suggest an involvement of second messenger cascades in the pathogenesis of AD in addition to neurotransmitters and their receptors.

Aged↗
PubMed1990

Intracellular accumulation of isoproterenol enhances the lactate production in the perfused rat heart.

Effects of intracellular accumulation of isoproterenol (ISO) on lactate production were examined in perfused rat heart. The lactate production during ISO perfusion in rat heart was increased and subsequent addition of an inhibitor of catechol-O-methyl transferase (COMT) further enhanced the production, and the enhanced production was significantly reduced by uptake2 inhibitor. The perfusion with ISO free-medium in the heart with high intracellular accumulation of ISO produced lactate more than that in the low intracellular accumulation. The present experiments demonstrated that the enhanced lactate production is accompanied by intracellular accumulation of ISO in the perfused rat heart, and suggested that the accumulated ISO may activate intracellular beta-adrenoceptors in the rat heart.

Animals↗
PubMed1990

A novel experimental model of giant cell myocarditis induced in rats by immunization with cardiac myosin fraction.

It is suspected that autoimmune disease processes are involved in the pathogenesis of a part of giant cell myocarditis. However, evidence for autoimmunity has rarely been demonstrated in clinical investigations. In this study, we have demonstrated a new animal model of autoimmune myocarditis characterized by the appearance of multinucleated giant cells. Lewis rats were immunized twice with human cardiac myosin fraction in complete Freund's adjuvant. Cardiac myosin fraction was prepared from the ventricular muscle of human hearts. Three weeks after the first immunization, acute and severe myocarditis was elicited in all rats. This myocarditis was characterized by massive pericardial effusion, enlargement of the heart, and gray discoloration of the cardiac muscle. Microscopically, there was marked cellular infiltration consisting of mononuclear cells, neutrophils, fibroblasts, and a considerable number of multinucleated giant cells. Extensive myocardial necrosis was also present. The heart weights increased from the third week to the fourth week and then gradually decreased. The titer of anti-myosin antibodies began to elevate from the second week and remained high until the sixth week. In the sixth week, inflammation became smoldering and the multinucleated giant cells disappeared. These findings indicate that the cardiac myosin fraction contains myocarditogenic antigen and that giant cell myocarditis can be induced by autoimmune involvement. To our knowledge, this is the first report of experimental giant cell myocarditis, which is closely similar to human giant cell myocarditis in its histology and clinical course.

Animals↗
PubMed1990

Ductal lesions of exocrine glands and insulitis induced by L3T4+ T cells following graft-versus-host reaction due to major histocompatibility complex class II disparity.

Recently, we have demonstrated characteristic hepatic lesions resembling primary biliary cirrhosis (PBC) in semiallogeneic F1 hybrid mice with major histocompatibility complex (MHC) class II-disparate graft-versus-host reaction (GVHR). In the present study, we tried to reveal other ductal lesions in extrahepatic organs, including salivary glands and pancreas. Murine strains used are C57BL/6 (B6), B6 mutant bm1, and bm12. bm1 carries a mutant gene at the H-2K locus of MHC and bm12 carries a mutant gene at the I-A locus of MHC of the B6 strain. The (B6 x bm1)F1, (B6 x bm12)F1, and (bm1 x bm12)F1 mice were injected intravenously with 1 x 10(7) B6 L3T4+ or Lyt-2+ T cells and were sacrificed on the 14th day postinjection for histological examinations. Mononuclear cell infiltration was detected around the ducts of salivary glands only in (B6 x bm12)F1 mice injected with B6 L3T4+ T cells. A moderate to marked level of cell infiltration was demonstrated in pancreas of (B6 x bm12)F1 recipients similar to nonobese diabetic (NOD) mice. By immunohistochemical examinations, infiltrating cells were shown to consist not only of L3T4+ but also of Lyt-2+ T cells, even after the inoculation of L3T4+ cells. These results are discussed in reference to mechanisms of organ-specific autoimmune diseases, especially insulitis in NOD mice which show insulin-dependent diabetes mellitus.

Animals↗
PubMed1990

Immunomodulatory effect of a newly synthesized compound, TOK-8801 (N-(2-phenylethyl)-3,6,6-trimethyl-5,6-dihydroimidazo [2,1-b]thiazole-2-carboxamide) on antibody production in vivo and delayed-type hypersensitivity in mice.

The immunopharmacological effects of a newly synthesized compound in vivo, TOK-8801 (N-(2-phenylethyl)-3,6,6-trimethyl-5,6-dihydroimidazo[2,1-b]thi azo le-2- carboxamide), on the anti-SRBC plaque-forming cell (PFC) response and delayed-type hypersensitivity (DTH) reaction were investigated. Oral administration of TOK-8801 (0.1-10 mg/kg) resulted in the suppression of the PFC responses to varying doses of antigen (5 x 10(6), 2 x 10(7), 1 x 10(8)) in C3H/He strain mice (7 W) which are high responders to SRBC antigen. On the other hand, the compound augmented the PFC response in aged mice (8-9 months) in which the PFC response was markedly depressed compared with that in young mice. In the experiment of the methylated human serum albumin-induced DTH reaction, TOK-8801 augmented the reaction in low responder (C57BL/6) mice by oral administrations of 0.1-1 mg/kg for 5 days from the sensitization, whereas suppressed the reaction in high responder (ICR) mice. These immunopharmacological actions of TOK-8801 were compared in dose and activity with those of lobenzarit and bucillamine. Thus, these results suggest that TOK-8801 may act as an immunomodulating agent and would be expected to be a useful agent for autoimmune diseases such as rheumatoid arthritis.

Adjuvants, Immunologic↗
PubMed1990

Immunohistochemical detection of major histocompatibility complex antigens and quantitative analysis of tumour-infiltrating mononuclear cells in renal cell cancer.

In order to investigate the anti-tumour immune responsiveness of patients with renal cell cancer (RCC), we examined 30 such patients for the degree of expression of major histocompatibility complex (MHC) class I and class II antigens on RCC and the populations of tumour-infiltrating mononuclear cells (TIM). Normal renal tubular cells expressed class I but not class II antigens. Most of the tumour cells expressed class I antigens in 25 (83%) cases, but the proportion of such cells was reduced in five cases, three of which were of granular cell type histologically. Class II antigens were detected in all specimens with class I positivity. Various numbers of TIM were detected in 25 cases, being composed mainly of T cells and a smaller number of macrophages. Examination for the phenotype of T cells showed that CD8-positive cells were the dominant population. B cells were not detected. Quantitative analysis revealed that the numbers of TIM were significantly lower in cases showing class I reduction than in those with normal class I expression. Therefore, it was clear that class I antigens were preserved in RCC cells in most cases. Furthermore, a higher rate of reduction of class I antigens was observed in cases of granular cell type, which has been reported to have a worse prognosis than the clear cell type. The present data suggest that degree of the expression of MHC class I antigen on RCC might influence the host immune responsiveness against it.

Adult↗
PubMed1990

Immunochemical identification of the ADP-ribosyltransferase in botulinum C1 neurotoxin as C3 exoenzyme-like molecule.

Botulinum C1 neurotoxin and C3 exoenzyme were purified to apparent homogeneity from the culture filtrate of Clostridium botulinum type C strain 003-9. Both preparations catalyzed ADP-ribosylation of the same substrate, the Mr 22,000 rho gene product (Gb). When the light and heavy chains of C1 toxin were separated, ADP-ribosyltransferase activity in the toxin was quantitatively recovered in the light chain fraction. Anti-C1 toxin antiserum precipitated the ADP-ribosyltransferase activity and the neurotoxicity of C1 toxin in parallel, whereas it had no effect on C3 exoenzyme. On the other hand, anti-C3 exoenzyme antiserum precipitated the ADP-ribosyltransferase activities of both C3 exoenzyme and C1 toxin. This antibody, however, did not precipitate the neurotoxicity of C1 toxin. The ADP-ribosyltransferase in C1 toxin was quantitatively adsorbed onto the anti-C3 antibody column and separated from the majority of C1 toxin protein. The enzyme was then eluted with acidic urea and Western blotting analysis of this eluate revealed the appearance of a protein band positively stained with anti-C3 antibody at a position similar to that of C3 exoenzyme. Quantitative determination by enzyme-linked immunosorbent assay showed that the C3-like immunoreactivity is present in the C1 toxin molecules at the molecular ratio of 1 to 1,000. These results suggest that the ADP-ribosyltransferase activity in C1 toxin is expressed by a C3-like molecule which is present in a small amount in the toxin preparation and appears to bind to the toxin component(s). The above results also indicate that the ADP-ribosyltransferase in C1 toxin is not related to its neurotoxin action.

Antibodies, Bacterial↗
PubMed1990

Therapeutic effect of 15-deoxyspergualin on the progression of lupus nephritis in MRL mice. I. Immunopathological analyses.

The effect of 15-deoxyspergualin (DSP), a newly developed immunosuppressive agent, on the development of spontaneously occurring lupus glomerulonephritis in MRL-lpr mice was examined. Administration of the drug was initiated at the age of 13 or 17 weeks, when polyclonal B cell activation and lupus nephropathy were apparent or became prominent. Treatment with DSP for up to 19 weeks of age at a dose of 2 mg/kg twice a day or 5 mg/kg daily strongly suppressed the increment of IgG-producing cell numbers in the spleen and serum levels of immune complexes and anti-DNA antibodies. Glomerular histological score estimated by light microscopy and IgG and C3 deposition in renal glomeruli were improved, compared with untreated control mice. Thus, DSP was shown to suppress the progression of polyclonal B cell activation and lupus nephropathy in MRL/lpr mice. These results suggest that DSP may be used as a therapeutic agent for systemic lupus erythematosus.

Animals↗
PubMed1990

Terminal deletion of chromosome 10q and its clinical features.

A male case with terminal deletion of chromosome 10q has growth retardation, craniofacial dysmorphism, congenital heart disease and other minor anomalies. The karyotypic formula is 46, XY, del (10), (q26.1----qter) by a high resolution G-banding staining. There are few differences in clinical features between our case and the previously reported cases.

Abnormalities, Multiple↗
PubMed1990

[3H]N-[1-(2-thienyl)cyclohexyl]-3,4-piperidine ([3H]TCP) binding in human frontal cortex: decreases in Alzheimer-type dementia.

We studied [3H]N-[1-(2-thienyl)cyclohexyl]-3,4-piperidine [( 3H]TCP) binding to human frontal cortex obtained at autopsy from 10 histologically normal controls and eight histopathologically verified cases with Alzheimer-type dementia (ATD). Extensively washed membrane preparations were used to minimize the effects of endogenous substances. In ATD frontal cortex, the total concentration (Bmax) of [3H]TCP binding sites was significantly reduced by 40-50%. The apparent dissociation constant (KD) values showed no significant change. The reduction in binding capacity was also apparent in Triton X-100-treated membrane preparations, and there was a linear correlation between the number of [3H]TCP binding sites and that of N-methyl-D-aspartate (NMDA)-sensitive [3H]glutamate binding sites. [3H]TCP binding sites spared in ATD brains retained the affinity for the ligand and the reactivity to NMDA, L-glutamate, and glycine. These results suggest that the primary change in NMDA receptor-ion channel complex in ATD brains is the reduction of its number, possibly reflecting the loss of neurons bearing these receptor complexes, and that the functional linkage within the receptor complexes spared in ATD brains remains normal.

Alzheimer Disease↗
PubMed1990

Effects of choline administration on in vivo release and biosynthesis of acetylcholine in the rat striatum as studied by in vivo brain microdialysis.

The purpose of the present study is to clarify the effects of the administration of choline on the in vivo release and biosynthesis of acetylcholine (ACh) in the brain. For this purpose, the changes in the extracellular concentration of choline and ACh in the rat striatum following intracerebroventricular administration of choline were determined using brain microdialysis. We also determined changes in the tissue content of choline and ACh. When the striatum was dialyzed with Ringer solution containing 10 microM physostigmine, ACh levels in dialysates rapidly and dose dependently increased following administration of various doses of choline and reached a maximum within 20 min. In contrast, choline levels in dialysates increased after a lag period of 20 min following the administration. When the striatum was dialyzed with physostigmine-free Ringer solution, ACh could not be detected in dialysates both before and even after choline administration. After addition of hemicholinium-3 to the perfusion fluid, the choline-induced increase in ACh levels in dialysates was abolished. Following administration of choline, the tissue content of choline and ACh increased within 20 min. These results suggest that administered choline is rapidly taken up into the intracellular compartment of the cholinergic neurons, where it enhances both the release and the biosynthesis of ACh.

Acetylcholine↗
PubMed1990

Enhancement of in vivo tyrosine hydroxylation in the rat adrenal gland under hypoxic conditions.

We examined the effects of hypoxia (8% O2) on in vivo tyrosine hydroxylation, a rate-limiting step for catecholamine synthesis, in the rat adrenal gland. The hydroxylation rate was determined by measuring the rate of accumulation of 3,4-dihydroxyphenylalanine (DOPA) after decarboxylase inhibition. One hour after hypoxic exposure, DOPA accumulation decreased to 60% of control values, but within 2 h it doubled. At 2 h, the apparent Km values for tyrosine and for biopterin cofactor of tyrosine hydroxylase (TH) in the soluble fraction were unchanged, whereas the Vmax value increased by 30%. The content of total or reduced biopterin was unchanged, but the content of tyrosine increased by 80%. Tyrosine administration had little effect on DOPA accumulation under room air conditions but enhanced DOPA accumulation under hypoxia. After denervation of the adrenal gland, the hypoxia-induced increase in DOPA accumulation and in the Vmax value was abolished, whereas the hypoxia-induced increase in tyrosine content was persistent. These results suggest that in vivo tyrosine hydroxylation is enhanced under hypoxia, although availability of oxygen is reduced. The enhancement is the result of both an increase in tyrosine content coupled with increased sensitivity of TH to changes in tyrosine tissue content and of an increase in dependence of TH on tyrosine levels. The increase in the sensitivity of TH and in the Vmax value is neurally induced, whereas the increase in tyrosine content is regulated by a different mechanism.

Adrenal Glands↗
PubMed1990

Enhancement of dopamine release in vivo from the rat striatum by dialytic perfusion of 6R-L-erythro-5,6,7,8-tetrahydrobiopterin.

We have previously reported that intracerebroventricular administration of 6R-L-erythro-5,6,7,8-tetrahydrobiopterin (6R-BH4), a cofactor for tyrosine hydroxylase, enhances biosynthesis of 3,4-dihydroxyphenylethylamine (dopamine) in the rat brain. In the present study, we have more precisely examined the effects of 6R-BH4 on dopamine release in vivo from the rat striatum using brain microdialysis. The amount of dopamine collected in striatal dialysates was determined using HPLC with electrochemical detection after purification with an alumina batch method. When the striatum was dialyzed with Ringer solution containing various concentrations of 6R-BH4 (0.25, 0.5, and 1.0 mM), dopamine levels in striatal dialysates increased in a concentration-dependent manner. Biopterin had little effect on dopamine levels in dialysates. The 6R-BH4-induced increase in dopamine levels in dialysates was abolished after pretreatment with tetrodotoxin (50 microM) added to the perfusion fluid, but after pretreatment with nomifensine (100 mg/kg, intraperitoneal injection), an inhibitor of dopamine uptake mechanism, a larger increase was observed. After inhibition of tyrosine hydroxylase by pretreatment with alpha-methyl-p-tyrosine (250 mg/kg, intraperitoneal injection), most of the increase persisted. These results suggest that 6R-BH4 has a dopamine-releasing action, which is not dependent on biosynthesis of dopamine.

Animals↗
PubMed1990

Effects of hypoxia on the catecholamine release, Ca2+ uptake, and cytosolic free Ca2+ concentration in cultured bovine adrenal chromaffin cells.

The purpose of the present study is to clarify the effects of hypoxia on catecholamine release and its mechanism of action. For this purpose, using cultured bovine adrenal chromaffin cells, we examined the effects of hypoxia on high (55 mM) K(+)-induced increases in catecholamine release, in cytosolic free Ca2+ concentration ([Ca2+]i), and in 45Ca2+ uptake. Experiments were carried out in media preequilibrated with a gas mixture of either 21% O2/79% N2 (control) or 100% N2 (hypoxia). High K(+)-induced catecholamine release was inhibited by hypoxia to approximately 40% of the control value, but on reoxygenation the release returned to control levels. Hypoxia had little effect on ATP concentrations in the cells. In the hypoxic medium, [Ca2+]i (measured using fura-2) gradually increased and reached a plateau of approximately 1.0 microM at 30 min, whereas the level was constant in the control medium (approximately 200 nM). High K(+)-induced increases in [Ca2+]i were inhibited by hypoxia to approximately 30% of the control value. In the cells permeabilized by digitonin, catecholamine release induced by Ca2+ was unaffected by hypoxia. Hypoxia had little effect on basal 45Ca2+ uptake into the cells, but high K(+)-induced 45Ca2+ uptake was inhibited by hypoxia. These results suggest that hypoxia inhibits high K(+)-induced catecholamine release and that this inhibition is mainly the result of the inhibition of high K(+)-induced increases in [Ca2+]i subsequent to the inhibition of Ca2+ influx through voltage-dependent Ca2+ channels.

Adenosine Triphosphate↗
PubMed1990

Phosphoinositide breakdown in rat hippocampal slices: sensitivity to glutamate induced by in vitro anoxia.

We examined the effects of in vitro anoxia on phosphoinositide (PI) breakdown in rat hippocampal slices stimulated by glutamate and quisqualate. In addition to assays of accumulations of 3H-inositol phosphates (3H-IPs) degraded from prelabeled PI, we adopted direct assay procedures of inositol 1,4,5-triphosphate (1,4,5-IP3) using 1,4,5-IP3-specific binding protein to determine the formation of 1,4,5-IP3. The first effect, observed with anoxic incubation by itself, was the diminished quisqualate (10(-5) M)-stimulated accumulation of 3H-IPs degraded from prelabeled PI under prolonged anoxia. Quisqualate caused a transient increase in 1,4,5-IP3 formation in the early phase of anoxia, similar to that under oxygenated conditions. Glutamate (10(-5) M), under normal conditions, influenced neither the accumulation of 3H-IPs nor the formation of 1,4,5-IP3. Also, the accumulation of 3H-IPs under prolonged anoxia was unaffected. The same concentration of glutamate, however, gave rise to a transient increase in 1,4,5-IP3 content in the early phase of anoxia, similar to that caused by quisqualate. The second effect, observed by oxygenation following anoxia, was the induction of glutamate-stimulated accumulation of 3H-IPs. When the hippocampal slices were oxygenated following a sufficiently long (greater than 30-min) exposure to anoxia, glutamate (10(-5) M) caused a significant increase in accumulation of 3H-IPs degraded from prelabeled PI. Quisqualate-stimulated accumulation of 3H-IPs under oxygenated incubations was also increased by prior exposure of slices to anoxia. These results support the hypothesis that an exposure of hippocampal slices to anoxia induces a sensitivity of the PI breakdown pathway to glutamate and that, given an oxygen supply following sufficiently long exposure to anoxia, the slices maintain their sensitivity to glutamate with an apparent increase in the accumulation of 3H-IPs.

Animals↗
PubMed1990

Differential calcium dependence between the release of endogenous dopamine and noradrenaline from rat brain synaptosomes.

The characteristics of the release of endogenous dopamine and noradrenaline from rat brain synaptosomes were studied using HPLC with an electrochemical detector. The spontaneous release of dopamine and noradrenaline was inhibited by approximately 50-60% in a Ca2(+)-free medium or a 100 microM La3(+)-containing medium. Also, the high-K+ (30 mM)-evoked release of dopamine and noradrenaline was inhibited by approximately 50-60% in a Ca2(+)-free medium or a 100 microM La3(+)-containing medium. From these results, the ratio of the Ca2(+)-dependent component to the total release of noradrenaline seemed to be similar to that of dopamine. On the other hand, 20 microM La3+ or 1 microM diltiazem inhibited both the spontaneous and 30 mM K(+)-evoked release of dopamine by approximately 50-60% but inhibited neither the spontaneous nor the 30 mM K(+)-evoked release of noradrenaline. The K(+)-evoked rise in intrasynaptosomal Ca2+ concentration was mostly blocked in Ca2(+)-free medium or 100 microM La3(+)-containing medium but was only partially blocked by 20 microM La3+ or 1 microM diltiazem. These data indicate alternative possibilities in that the Ca2(+)-dependent release of noradrenaline might be less sensitive to a change of intracellular Ca2+ concentration than that of dopamine and that the calcium channels directly involved in the noradrenaline release may be more resistant to diltiazem and La3+ than those involved in the dopamine release.

Animals↗