Search PubMed⌕ Search

Biomedical subjects

H Kataoka

Publications and source records attributed to H Kataoka.

At least 55 records · Page 3Linked to original sources

Blue light-induced branching in Vaucheria. Requirement of nuclear accumulation in the irradiated region.

When a narrow region of the fresh water coenocytic alga, Vaucheria terrestris sensu Götz is irradiated with moderately intense blue light, a branch is induced from the center of the irradiated region after 4-5 h. Movement of organelles and microtubule bundles during the photocytomorphogenetic response were investigated. Chloroplasts in the cortical layer immediately started to accumulate in the blue light-irradiated region and their accumulation almost completely finished 30-40 min after the onset of light when the nuclei residing in endoplasm started to accumulate. Accumulation of nuclei was synchronized with disorientation and shortening of microtubule bundles, which originally run parallel to the cell axis. Not only amiprophos-methyl, a potent microtubule-decomposing reagent, but also cytochalasin A strongly inhibited the branch induction. Amiprophos-methyl completely and cytochalasin A mostly destroyed microtubules and completely inhibited nuclear accumulation, but both drugs allowed the accumulation of chloroplasts in the cortical layer of irradiated region. These indicate that the accumulation of nuclei is indispensable for branch induction while the chloroplast accumulation is insufficient by itself for branch induction. The ineffectiveness of cytochalasin A on chloroplast movement brings the conventional view of sliding movement of chloroplast on a long actin cable into question. The morphological and functional relationship between a nucleus and a microtubular bundle are discussed.

Cell Nucleus↗

Venous congestion is a major cause of neurological deterioration in spinal arteriovenous malformations.

OBJECTIVE: Although venous congestion is considered to be a major cause of progressive myelopathy in patients with spinal dural arteriovenous fistulae (DAVFs), the neurological deterioration in patients with spinal intradural arteriovenous malformations (AVMs) has been attributed to hemorrhage or to vascular steal. To reexamine this theory, we analyzed our own cases of spinal vascular diseases. METHODS: In 24 patients with spinal vascular diseases, those who demonstrated progressive myelopathy with T2 hyperintensity in the spinal cord on magnetic resonance imaging (MRI) were diagnosed as patients with congestive myelopathy. We further examined the clinical courses, MRI findings, and reversibility of these cases. RESULTS: Venous congestion was judged to be a cause of neurological deterioration in 13 patients (7 DAVFs, 6 intradural AVMs). The T2 signals on these patients' MRI scans were located in the center and extended over several levels not corresponding to distribution of ischemia due to arterial steal. Of the patients who were diagnosed with congestive myelopathy, no differences between those with DAVFs and those with intradural AVMs were apparent in terms of clinical manifestations and reversibility. Eight (four DAVFs, four intradural AVMs) of 13 patients experienced neurological improvement after treatment. All patients with poor outcomes had intervals from onset of more than 3 years and showed contrast enhancement of the spinal cord on MRI studies. CONCLUSION: Spinal intradural AVMs as well as spinal DAVFs can be a cause of venous congestive myelopathy. Regardless of its etiology, congestive myelopathy is potentially reversible if properly diagnosed and treated.

Adult↗

Functional evaluation of cytochrome P450 2D6 with Gly42Arg substitution expressed in Saccharomyces cerevisiae.

A single amino acid-substituted mutant protein, CYP2D6 (G42R) was expressed in Saccharomyces cerevisiae and its enzymatic properties were compared with those of other single (P34S, R296C and S486T) and double amino acid-substituted mutant proteins (P34S/S486T and R296C/S486T) expressed in yeast cells, all of which were known to occur in the CYP2D6 gene as single nucleotide polymorphisms. The protein levels of G42R, P34S and P34S/S486T in microsomal fractions and their oxidation capacities towards debrisoquine as a prototypic substrate and bunitrolol as a chiral substrate were different from those of wild-type CYP2D6, while the R296C, S486T and R296C/S486T behaved similarly to the wild-type in these indices. The CYP contents both in yeast microsomal and in whole cell fractions indicated that some part of G42R protein was localized in the endoplasmic reticulum membrane fraction, whereas most of G42R protein was in some subcellular fractions other than endoplasmic reticulum. In kinetic analysis, the G42R substitution increased apparent Km and decreased Vmax for debrisoquine 4-hydroxylation, while it increased both Km and Vmax for bunitrolol 4-hydroxylation. The P34S substitution did not drastically change Km but decreased Vmax for debrisoquine 4-hydroxylation, whereas Km was increased and Vmax unchanged or decreased for bunitrolol 4-hydroxylation by P34S substitution. These results suggest that the G42R substitution causes a change in the CYP2D6 conformation, which may be different from the change produced by the P34S substitution.

Amino Acid Substitution↗

Acid stimulates E-cadherin surface expression on gastric epithelial cells to stabilize barrier functions via influx of calcium.

BACKGROUND AND AIMS: E-cadherin, which is a [Ca2+]-dependent, homotypic cell-cell adhesion molecule, is expressed in gastrointestinal epithelial cells. Much has been learned about the down-regulation of E-cadherin expression in gastrointestinal tumours, Barrett's oesophageal dysplasia, and Crohn's disease, but the functions of this molecule in normal gastrointestinal mucosa are less known. METHODS: In this study, we investigated the relationship between E-cadherin expression and permeability using rat cultured gastric and intestinal epithelial cells following a 30-min exposure to various pH solutions. We also investigated the participation of [Ca2+] in these events. RESULTS: E-cadherin expression increased under acid (pH 4) but not alkali (pH 10 or 11) exposure only for gastric epithelial cells. Gastric epithelial permeability was maintained only against acid exposure while intestinal permeability increased under both conditions. Transient influx of [Ca2+] was only observed for gastric epithelial cells just after acid exposure. CONCLUSIONS: These findings suggest that E-cadherin expression on gastric epithelium stabilizes the epithelial barrier against acid, probably through influx of [Ca2+]. This event is thought to be one of the protective mechanisms in gastric mucosa against acid back-diffusion, which is one of the causes of peptic ulcer formation.

Acids↗

Role of oxidized LDL in atherosclerosis.

A critical event in the early stages of atherosclerosis is the focal accumulation of lipid-laden foam cells derived from macrophages. In various cholesterol-fed animal models of atherosclerosis, localized attachment of circulating monocytes to arterial endothelial cells appeared to precede the formation of foam cells. It is suggested that monocyte recruitment into early lesions depends on the endothelial adhesiveness for monocytes and lymphocytes. In vivo and in vitro experiments have identified molecules, such as ICAM-1, VCAM-1, and P-selectin, that can support the adhesion of monocytes and lymphocytes. Moreover, oxidized LDL, lysophosphatidyl-choline, and oxidized fatty acids induce the expression not only of these adhesion molecules but also of scavenger receptors, such as CD-36, SR-A, and LOX-1. Recently, we isolated and characterized the novel receptors for oxidized LDL, namely, LOX-1 and SR-PSOX. Expression of LOX-1 is found on endothelial cells, smooth muscle cells, and macrophages, whereas SR-PSOX is expressed on macrophages. In this paper the significance of oxidized LDL and its receptors, LOX-1 and SR-PSOX, in terms of atherogenesis is discussed.

Animals↗

Study on PDGF receptor beta pathway in glomerular formation in neonate mice.

The assembly of vascular endothelial cells (ECs) and smooth muscle cells is a critical event in the development of the cardiovascular system. Although the role of ECs in this event has been studied intensively, the cross-talk between the two cell components remains poorly understood. In this study, we blocked platelet-derived growth factor receptor (PDGFR) pathways in mice by antagonistic rat monoclonal antibody APB5 against murine PDGFR-beta and examined glomerular capillary formation.

Aging↗

Peroxisome proliferator-activated receptor a ligands increase lectin-like oxidized low density lipoprotein receptor-1 expression in vascular endothelial cells.

Lectin-like oxidized low density lipoprotein receptor-1 (LOX-1) is a receptor for atherogenic oxidized LDL expressed in vascular endothelial cells, smooth muscle cells, and macrophages. Peroxiosme proliferator-activated receptors (PPARs) include subfamilies PPARalpha and PPARgamma, which are expressed in endothelial cells and involved in transcriptional regulation of a large number of genes that affect lipoprotein and fatty acid metabolism as well as inflammation. We therefore explored the effects of PPARalpha and PPARgamma ligands on expression of LOX-1. Treatment of cultured bovine aortic endothelial cells (BAECs) with PPARalpha ligands (fenofibrate and WY14643) remarkably upregulated LOX-1 expression, which was detected by western and northern blot analyses. LOX-1 promoter-reporter gene assay showed that PPARalpha ligands activate transcription of the LOX-1 gene. PPARgamma ligands, in contrast, did not significantly affect LOX-1 expression in BAECs. PPARalpha appears to be a key regulator in promoting LOX-1 expression in BAECs. Upregulated expression of LOX-1 may modulate the catabolism of oxidized LDL and atherosclerotic progression.

Animals↗

Expression of scavenger receptor for phosphatidylserine and oxidized lipoprotein (SR-PSOX) in human atheroma.

Recently, we identified a novel macrophage cell-surface receptor for oxidized low-density lipoprotein (Ox-LDL), designated SR-PSOX (scavenger receptor for phosphatidylserine and oxidized lipoprotein). Here we examine SR-PSOX expression in human atherosclerotic lesions using carotid endarterectomy specimens from 21 patients, directional coronary atherectomy specimens from 11 patients, and normal aortas from 2 patients. RT-PCR analysis demonstrated that SR-PSOX expression was upregulated in atherosclerotic lesions, but undetectable in normal aortas. Immunohistochemistry showed that SR-PSOX was abundantly expressed by macrophages in the intima of atherosclerotic lesions. Taken together, SR-PSOX may be involved in Ox-LDL uptake and subsequent foam cell transformation in macrophages in vivo and therefore may play important roles in human atherosclerotic lesion formation.

Arteriosclerosis↗

[An adult case of systemic cat-scratch disease with hepatosplenic involvement].

A previously healthy 25-year-old female was admitted to our hospital in November, 1997, for treatment of a spike-fever of 2 weeks' duration. She had a cat in her house but reported no history of cat bites or scratches. No peripheral lymphadenopathy was detected. White blood cell count was within normal limits, but an increased C-reactive protein level of 11.4 mg/dl was noted. Infectious disease was suspected but ruled out as blood cultures were negative. Empiric therapy with clarithromyoin, isoniazid, and rifampicin was ineffective. In January, 1998, abdominal ultrasonogram revealed multiple hypoechoic mass lesions in the spleen and liver, and a splenectomy was performed in March. Histopathologic examination showed numerous necrotizing and caseating granulomas, which tested positive for Bartonella henselae DNA by PCR. Furthermore, the patient tested positive for B. henselae antibody by immunofluorescence assay. A diagnosis of systemic cat-scratch disease with hepatospnenic involvement was made. Combination therapy with minocycline, sulbactam/cefoperazone, and tosufloxacin was administered and her inflammatory findings improved gradually. We report an adult case of systemic cat-scratch disease with liver and spleen involvement in the non-immunocompromised host.

Adult↗

Involvement of alpha-PAK-interacting exchange factor in the PAK1-c-Jun NH(2)-terminal kinase 1 activation and apoptosis induced by benzo[a]pyrene.

Benzo[a]pyrene [B(a)P], a potent procarcinogen found in combustion products such as diesel exhaust and cigarette smoke, has been recently shown to activate the c-Jun NH(2)-terminal kinase 1 (JNK1) and induce caspase-3-mediated apoptosis in Hepa1c1c7 cells. However, the molecules of the signaling pathway that control the mitogen-activated protein kinase cascades induced by B(a)P and the interaction between those and apoptosis by B(a)P have not been well defined. We report here that B(a)P promoted Cdc42/Rac1, p21-activated kinase 1 (PAK1), and JNK1 activities in 293T and HeLa cells. Moreover, alpha-PAK-interacting exchange factor (alpha PIX) mRNA and its protein expression were upregulated by B(a)P. While overexpression of an active mutant of alpha PIX (DeltaCH) facilitated B(a)P-induced activation of Cdc42/Rac1, PAK1, and JNK1, overexpression of mutated alphaPIX (L383R, L384S), which lacks guanine nucleotide exchange factor activity, SH3 domain-deleted alphaPIX (Delta SH3), which lacks the ability to bind PAK, kinase-negative PAK1 (K299R), and kinase-negative SEK1 (K220A, K224L) inhibited B(a)P-triggered JNK1 activation. Interestingly, overexpression of alphaPIX (Delta CH) and a catalytically active mutant PAK1 (T423E) accelerated B(a)P-induced apoptosis in HeLa cells, whereas alphaPIX (Delta SH3), PAK1 (K299R), and SEK 1 (K220A, K224L) inhibited B(a)P-initiated apoptosis. Finally, a preferential caspase inhibitor, Z-Asp-CH2-DCB, strongly blocked the alphaPIX (Delta CH)-enhanced apoptosis in cells treated with B(a)P but did not block PAK1/JNK1 activation. Taken together, these results indicate that alphaPIX plays a crucial role in B(a)P-induced apoptosis through activation of the JNK1 pathway kinases.

Apoptosis↗

Lysophosphatidylcholine induces early growth response factor-1 expression and activates the core promoter of PDGF-A chain in vascular endothelial cells.

Lysophosphatidylcholine (lyso-PC), a polar phospholipid that is increased in atherogenic lipoproteins and atherosclerotic lesions, has been shown to transcriptionally induce the expression of endothelial genes relevant to atherogenesis. In cultured bovine aortic endothelial cells (BAECs), we show that lyso-PC induces the expression of early growth response factor (Egr)-1 and thereby activates the proximal promoter of the platelet-derived growth factor (PDGF)-A chain located 55 to 71 bp upstream from the transcription start site, which has been shown to be crucial for PDGF-A chain expression induced by fluid shear stress and fibroblast growth factor-1. Northern blot analyses showed that lyso-PC (10 to 20 micromol/L) transiently (30 minutes to 1 hour) induced expression of Egr-1 mRNA. Induced expression of Egr-1 mRNA, which was associated with increased amounts of Egr-1 protein in nuclei, preceded PDGF-A chain mRNA induction in lyso-PC-activated BAECS: Nuclear runoff assay revealed that lyso-PC stimulates transcription of the Egr-1 gene. Transient transfection of the oligonucleotide corresponding to the proximal promoter of the PDGF-A chain (oligo A) linked to the luciferase reporter gene revealed that lyso-PC can activate the core promoter of the PDGF-A chain by 5-fold. Insertion of a guanine at 3 sites in the oligo A abolished the lyso-PC-induced increases in luciferase activities. Electrophoretic mobility shift assay with use of radiolabeled oligo A showed a lyso-PC-inducible shift band, which was suppressed by excess amounts of unlabeled oligo A or an anti-Egr-1 antibody. In addition, lyso-PC-induced Egr-1 expression was inhibited by PD98059, a specific inhibitor of mitogen-activated protein kinase kinase-1 (MEK1), suggesting that lyso-PC-induced expression of Egr-1 depends on the MEK1/extracellular signal-regulated kinase pathway. Taken together, transcriptional activation of Egr-1-dependent genes by this atherogenic lipid may be a key regulator of atherogenesis.

Animals↗

Oxidized LDL modulates Bax/Bcl-2 through the lectinlike Ox-LDL receptor-1 in vascular smooth muscle cells.

Oxidized low density lipoprotein (Ox-LDL) induces apoptosis in vascular smooth muscle cells (VSMCs), which may increase atherosclerotic plaque instability. In this study, we examined the molecular mechanisms causing the Ox-LDL-induced apoptosis in VSMCs, especially focusing on the involvement of Bax/Bcl-2 and the lectinlike Ox-LDL receptor-1 (LOX-1). In cultured bovine aortic smooth muscle cells (BASMCs), Ox-LDL at high concentrations (>60 microg/mL) induced cell death as demonstrated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. DNA fragmentation was increased in BASMCs treated with high concentrations of Ox-LDL, indicating that the Ox-LDL-induced cell death in VSMCs was apoptosis. Ox-LDL upregulated LOX-1 expression through phosphorylation of extracellular signal-regulated kinase in BASMCs, and a neutralizing anti-LOX-1 monoclonal antibody, which can block LOX-1-mediated cellular uptake of Ox-LDL, prevented the Ox-LDL-induced apoptosis in BASMCs. This antibody also suppressed the increase in the Bax to Bcl-2 ratio induced by Ox-LDL in BASMCs. Furthermore, LOX-1 expression was well colocalized with Bax expression in the rupture-prone shoulder areas of human atherosclerotic plaques in vivo. LOX-1 may play an important role in Ox-LDL-induced apoptosis in VSMCs by modulating the Bax to Bcl-2 ratio. These molecular mechanisms may be involved in destabilization and rupture of atherosclerotic plaques.

Animals↗

Expression of SR-PSOX, a novel cell-surface scavenger receptor for phosphatidylserine and oxidized LDL in human atherosclerotic lesions.

Receptor-mediated endocytosis of oxidized low density lipoprotein (Ox-LDL) by macrophages and the subsequent foam cell transformation in the arterial intima are key events in early atherogenesis. Recently, we have identified a novel macrophage cell-surface receptor for Ox-LDL by expression cloning from a cDNA library of phorbol 12-myristate 13-acetate-stimulated THP-1 cells, designated as the scavenger receptor for phosphatidylserine and oxidized lipoprotein (SR-PSOX). Here, we examined SR-PSOX expression in human atherosclerotic lesions. Total cellular RNA and fresh frozen sections were prepared from human carotid endarterectomy specimens (from 21 patients) and directional coronary atherectomy specimens (from 11 patients). Fragments of human aortas of 2 patients without visible atherosclerotic lesions served as negative controls. Quantitative reverse transcription-polymerase chain reaction demonstrated that SR-PSOX mRNA expression was prominent in atherosclerotic lesions but undetectable in normal aortas. Immunohistochemistry showed that SR-PSOX was predominantly expressed by lipid-laden macrophages in the intima of atherosclerotic plaques in carotid endarterectomy and directional coronary atherectomy specimens, although its expression was not detectable in normal arterial wall. Double-labeled immunohistochemistry confirmed that SR-PSOX is expressed by intimal macrophages. Taken together, SR-PSOX may be involved in Ox-LDL uptake and subsequent foam cell transformation in macrophages in vivo and thus may play important roles in human atherosclerotic lesion formation.

Animals↗

Effects of transglottal pressure on fundamental frequency of phonation: study with a rubber model.

The fundamental frequency of phonation (F0) change per unit change in transglottal pressure (dF/dP) was studied at different extension lengths and masses of the vibrating part of a rubber model. The dF/dP was decreased when the vibrating part was extended, and also when the mass of the vibrating part was increased. In the former, the F0 was increased, and in the latter, the F0 was decreased. In humans, we have noticed that when the F0 was increased, the dF/dP first decreased and then increased, taking a V-shaped curve as a function of the F0. The present study reveals the mechanism underlying the V-shaped curve observed in humans.

Glottis↗

Identification and characterization of two distinct GnRH receptor subtypes in a teleost, the medaka Oryzias latipes.

We report the identification and characterization of two distinct GnRH receptor (GnRH-R) subtypes, designated GnRH-R1 and GnRH-R2, in a model teleost, the medaka Oryzias latipes. These seven-transmembrane receptors of the medaka contain a cytoplasmic C-terminal tail, which has been found in all other nonmammalian GnRH-Rs cloned to date. The GnRH-R1 gene is composed of three exons separated by two introns, whereas the GnRH-R2 gene has an additional intron and therefore consists of four exons and three introns. The GnRH-R1 and GnRH-R2 genes, both of which exist as single-copy genes in the medaka genome, were mapped to linkage groups 3 and 16, respectively. Inositol phosphate assays using COS-7 cells transfected with GnRH-R1 and GnRH-R2 demonstrated that they had remarkably different ligand sensitivities, although both receptors showed highest preference for chicken-II-type GnRH. Phylogenetic analysis showed the presence of three paralogous lineages for vertebrate GnRH-Rs and indicated that neither GnRH-R1 nor GnRH-R2 is the medaka ortholog to mammalian GnRH-Rs that lack a cytoplasmic tail. This, together with an observation that medaka-type GnRH had low affinity for GnRH-R1 and GnRH-R2, suggests that a third GnRH-R may exist in the medaka.

Amino Acid Sequence↗

Inactivation of rat cytochrome P450 2D enzyme by a further metabolite of 4-hydroxypropranolol, the major and active metabolite of propranolol.

Repetitive administration of propranolol (PL) in rats decreases the activities of cytochrome P450 (CYP) 2D enzyme(s) in hepatic microsomes. We examined the properties of 4-hydroxypropranolol (4-OH-PL) as an inactivator of rat liver microsomal CYP2D enzyme(s) using bunitrolol (BTL) 4-hydroxylation and PL 5- and 7-hydroxylations as indices of CYP2D enzyme activity. Rat microsomal BTL 4-hydroxylase activity was inhibited by the addition of 4-OH-PL to the incubation medium. The inhibition was greater after preincubation of microsomes with 4-OH-PL in the presence of NADPH than in its absence. The type of inhibition kinetics of BTL 4-hydroxylase by 4-OH-PL was changed from a competitive type to a noncompetitive type by the preincubation. The inhibition of rat liver microsomal PL 5- and 7-hydroxylases by 4-OH-PL was blocked efficiently by co-incubation with quinine, a typical inhibitor of rat CYP2D enzyme(s), or to a lesser extent by BTL. However, quinidine, a diastereomer of quinine, did not significantly protect against the enzyme inactivation. The protective capacities of the substrate and inhibitors reflected their affinities for rat CYP2D enzyme(s). BTL hydroxylase was not affected by either 1,4-naphthoquinone or 1,4-dihydroxynaphthalene which are possible metabolites of 4-OH-PL. These results provide further evidence to support the notion that PL is biotransformed by rat CYP2D enzyme(s) to 4-OH-PL, which is further oxidized to a chemically reactive metabolite in the active site. The inactivation of CYP is likely the result of covalent binding of the reactive species to an amino acid residue of the active site.

Adrenergic beta-Antagonists↗

[Effects of stress on allergic reaction].

The purpose of the present study was to investigate the effects of stress on allergic reaction. We studied changes in the contact hypersensitivity reaction (CHR) of mice exposed to foot shock (FS) stress or psychological (PSY) stress induced by the communication box. CHR was elicited by applying antigen (2,4-dinitrofluorobenzene, DNFB) to the ear of the mice at 4 days after DNFB sensitization. In acute stress experiments, DNFB-sensitized mice were exposed for 2 h to FS or PSY stress after contact challenge with DNFB. Acute FS stress significantly inhibited CHR immediately after the end of the stress period (3 h after DNFB-challenge), and a significant enhancement of the CHR was observed at 5 h after DNFB-challenge. The concentration of the serum corticosterone level of the mice exposed to acute FS stress significantly increased compared to the control mice, immediately after stress loading. Both CHR and serum corticosterone levels after acute PSY stress loading were almost the same as those of the control groups. The temporary decrease of the inflammatory reaction at CHR caused by acute FS stress loading may have been correlated with serum corticosterone produced by the stress, and the increase of corticosterone may act as a trigger of enhancement of the CHR (delayed-type hypersensitivity). Chronic stress experiments were designed to expose mice to FS or PSY stress 2 h daily after sensitization with DNFB. These chronic stresses caused a significant reduction in the body weight of mice. The temporary decrease effect on the CHR of chronic FS stress-loaded mice was similar to the acute FS stress-loaded mice. In contrast, no significant enhancement of the CHR (late phase) at 24 h and 48 h after challenge was observed. Although the changes in body weight suggested that mice were influenced by chronic PSY stress, no significant difference from the control group for the CHR of mice exposed to chronic PSY stress was found, as in the case of acute PSY stress loading. The correlation between chronic PSY stress and CHR remains to be ascertained.

Animals↗

Coexistence of Graves' disease and struma ovarii: case report and literature review.

We report a rare case of Graves' disease associated with struma ovarii. A 26-year-old Japanese woman had preexisting Graves' disease and was positive for TSH receptor antibody. She had been on antithyroid medication at presentation. She noted a mass in the lower left abdomen, which was diagnosed as a left struma ovarii by radiological work-up including computed tomography, magnetic resonance imaging and scintigraphy. The surgically excised teratomatous tumor, containing cystic spaces with thyroid tissue, was histologically proved to be struma ovarii. Since thyroid function tests and TSH receptor antibody did not change after surgery, her hyperthyroidism was considered to be due to Graves' disease. Our case was diagnosed as struma ovarii before surgery using various imaging studies.

Adult↗