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Y Shimoda

Publications and source records attributed to Y Shimoda.

At least 19 recordsLinked to original sources
PubMed2002

Phase diagram of interacting composite fermions in the bilayer nu=2/3 quantum hall effect.

We study the phase diagram of composite fermions (CFs) in the presence of spin and pseudospin degrees of freedom in the bilayer nu=2/3 quantum Hall (QH) state. Activation studies elucidate the existence of three different QH states with two different types of hysteresis in the magnetotransport. While a noninteracting CF model provides a qualitative account of the phase diagram, the observed renormalization of tunneling gap and a non-QH state at high densities are not explained in the noninteracting CF model, and are suggested to be manifestations of interactions between CFs.

Journal Article↗
PubMed2001

Antigens of monoclonal antibody NB3C4 are novel markers for oligodendrocytes.

We produced NB3C4, a novel monoclonal antibody specific for oligodendrocytes, using human neuroblastoma IMR-32 cells. NB3C4 specifically recognized oligodendrocytes in the CNS, although it bound to neuroblastoma IMR-32 cells and oligodendrocytes in vitro. Double immunofluorescence staining of rat brain using NB3C4 and anti-GST-pi, anti-glial fibrillary acidic protein (GFAP), or anti-neurofilament 200 (NF) antibody revealed that anti-GST-pi antibody identified an oligodendrocyte marker recognizing NB3C4-positive cells, while both anti-GFAP and anti-NF antibody did not. Western blotting of rat brain homogenates showed that NB3C4 bound three proteins of 22-28 kDa, while the anti-GST-pi recognized a 27 kDa protein. Therefore, antigens recognized by NB3C4 could be novel markers for oligodendrocytes.

Animals↗
PubMed2001

Expression of glycoconjugates bearing the Lewis X epitope during neural differentiation of P19 EC cells.

The Lewis X (Le(x)) bearing glycolipids were noticeably increased in amounts during the course of neural differentiation of P19 EC cells induced by retinoic acid (RA, all-trans form). Applying neoglycolipid technology and in situ TLC-LSIMS, the oligosaccharide chains of these scarce Le(x) bearing glycolipids were partially characterized after released by endoglycoceramidase and subsequent conversion into neoglycolipids. In order to understand the enzymatic basis for the expression of Le(x) bearing glycolipids, we measured glycolipid, glycoprotein and oligosaccharide fucosyltransferase (Fuc-T) activities using appropriate substrates in P19 EC cells with or without RA treatment. All three Fuc-Ts were increased after RA treatment and the highest activity was in the differentiated neural cells. We then investigated the two possible Fuc-T genes that might be responsible for these changes using RT-PCR analysis. Mouse Fuc-TIX (mFuc-TIX) transcript was detected in all cell types but it was only strongly expressed in RA-induced aggregates and neural cells. In the case of mouse Fuc-TIV (mFuc-TIV) gene, its transcript was only detectable in RA-induced aggregates and not found in either undifferentiated or RA-induced neural cells. These results strongly support that RA induces only a transient expression of the mFuc-TIV gene in cell aggregates but a more persistent expression of the mFuc-TIX gene at the transcription level throughout neural cell differentiation. The mFuc-TIX gene is probably the main cause for the increased expression of Le(x) glycoconjugates during neural differentiation of P19 EC cells.

Animals↗
PubMed2000

Localization of the pituitary adenylate cyclase-activating polypeptide receptor and its mRNA in the rat adrenal medulla.

We examined the localization of the pituitary adenylate cyclase-activating peptide (PACAP) receptor (PAC1-R) and its mRNA with immunocytochemistry and in situ hybridization, respectively. PAC1-R immunoreactivity and its transcript were detected in both chromaffin cells and ganglion cells but not detected in the adrenal cortex. In addition, strong PAC1-R immunoreactivity was found beneath the plasma membrane of the immunoreactive medullary cells. Electron microscopic immunocytochemistry revealed that PAC1-R was predominantly expressed in adrenaline-containing cells. This report supports the notion that PACAP is an activator and modulator of catecholamine secretion as well as synthesis in the adrenal medulla.

Adrenal Medulla↗
PubMed2000

Morphological evidence for neural interactions between leptin and orexin in the hypothalamus.

Both leptin and orexin have been recently discovered as peptides involved in feeding regulation. The morphological evidence of neural interaction between leptin and orexin, one considered to inhibit food intake and the other to stimulate it in the central nervous system (CNS), was studied by use of double immunostaining method. The leptin receptor-like immunoreactive (LR-LI) neurons in the hypothalamic arcuate nucleus and ventromedial nucleus were innervated by orexin-like immunoreactive (OX-LI) neurons. The distribution of LR-LI neurons in the hypothalamus was very similar to that of OX-LI neurons. These results may suggest that leptin and orexin are intimately correlated with each other and that they reciprocally regulate feeding at the hypothalamic level.

Animals↗
PubMed2000

Differential expression of two glucuronyltransferases synthesizing HNK-1 carbohydrate epitope in the sublineages of the rat myogenic progenitors.

HNK-1 epitope is a cell-surface carbohydrate mediating various cell-cell or cell-substrate interactions. We found HNK-1 epitope in longitudinally arrayed fibers in the subpopulation of the epaxial myotome, and hypaxial myoblasts migrating into the limb bud in the rat embryo. We next investigated the expression patterns of genes encoding two glucuronyltransferases (GlcAT-P, GlcAT-D) and sulfotransferase (Sul-T), which are required for biosynthesis of HNK-1 epitope. GlcAT-P gene was expressed in the non-migrating longitudinal fibers, whereas GlcAT-D gene was expressed in the migrating myoblasts in the limb bud. Sul-T gene expression was ubiquitously observed in all these myogenic populations. Thus, differential expression of GlcAT genes may relate to the epaxial/hypaxial or migrating/non-migrating myoblast lineages.

Animals↗
PubMed2000

Ganglioside GT1b in rat brain binds to p58, a brain-specific sodium-dependent inorganic phosphate cotransporter: expression cloning with a specific monoclonal antibody to ganglioside GT1b-binding protein.

To evidence the notion that gangliosides involve neuronal cell interactions in the brain, we surveyed the presence of ganglioside-binding proteins in membrane lysates of adult rat cerebellum. Three proteins (p58, p90, and p160) were identified as GT1b-binding proteins by incubation of the blot of the membrane lysate with GT1b micelles. We generated a monoclonal antibody (mAb) specific to the polypeptide portion of the GT1b-binding proteins (YAK-2). The YAK-2 mAb specifically reacted with all three proteins on blots of proteins pretreated under nonreducing conditions for SDS-PAGE, but reacted mainly with p58 under reducing conditions, showing that p90 and p160 are oligomeric forms of p58. The binding activity of the YAK-2 mAb was completely inhibited by the presence of GT1b micelles, indicating the specificity of YAK-2 mAb for p58 and its oligomers. Immunohistochemical investigations revealed that both p58 and GT1b colocalize within the granular layer of adult rat cerebellum. Expression cloning of p58 cDNA was performed using YAK-2 mAb, and five putative clones were obtained. Among them, the nucleotide sequence of one cDNA completely matched that of rat brain-specific sodium-dependent inorganic phosphate cotransporter (rBNPI), a 61 kDa membrane protein. COS7 cells were transfected with a Flag-chimeric construct containing the rBNPI/p58 cDNA, and the membrane lysate was subjected to immunoprecipitation with anti-Flag antibody. One protein (64 kDa) was detected only with YAK-2 mAb, and the membrane lysate specifically bound to GT1b micelles. Taking together, we propose that rBNPI/p58 functions as a GT1b-binding protein in neuronal cells.

Animals↗
PubMed2000

Functional significance of colocalization of PACAP and catecholamine in nerve terminals.

Medullary neurons containing pituitary adenylate cyclase-activating polypeptide (PACAP) and noradrenalin (NA) project to the hypothalamus and they are involved in the regulation of arginine vasopressin (AVP) neurons. At the ultrastructural level, PACAP immunoreactivity was detected in the granular vesicles in catecholaminergic nerve terminals that made synaptic contact with AVP neurons. Both PACAP (at least 1 nM) and NA (at least 1 microM) induced large increases in the cytosolic Ca2+ concentration ([Ca2+]i) in isolated AVP cells. PACAP at 0.1 nM and NA at 0.1 microM had little effects, if any, on [Ca2+]i. However, when 0.1 nM PACAP and 0.1 microM NA were combined, they evoked large increase in [Ca2+]i in AVP neurons. An inhibitor of protein kinase A (PKA) completely inhibited the PACAP-induced increase in [Ca2+]i, but only partly inhibited the NA-induced increase in [Ca2+]i. In AVP cells that were prelabeled with quinacrine, PACAP and NA acted synergistically to induce a loss of quinacrine fluorescence, indicating secretion of neurosecretory granules in AVP neurons. The results suggest that PACAP and NA, coreleased from the same nerve terminals, act in synergy to evoke calcium signaling and secretion in AVP neurons, and that the synergism is mediated by the interaction between cAMP-PKA pathway an as yet unidentified factor "X" linked to L-type Ca2+ channels. The synergism between PACAP and NA may contribute to the regulation of AVP secretion under physiological conditions.

Animals↗
PubMed1999

Cloning and expression of a novel galactoside beta1, 3-glucuronyltransferase involved in the biosynthesis of HNK-1 epitope.

We isolated a cDNA encoding a novel glucuronyltransferase, designated GlcAT-D, involved in the biosynthesis of the HNK-1 carbohydrate epitope from rat embryo cDNA by the degenerate polymerase chain reaction method. The new cDNA sequence revealed an open reading frame coding for a protein of 324 amino acids with type II transmembrane protein topology. The amino acid sequence of GlcAT-D displayed 50.0% identity to rat GlcAT-P, which is involved in the biosynthesis of the HNK-1 epitope on glycoproteins. Expression of GlcAT-D in COS-7 cells resulted in the formation of the HNK-1 epitope on the cell surface. The enzyme expressed in COS-7 cells transferred a glucuronic acid (GlcA) not only to asialo-orosomucoid, a glycoprotein bearing terminal N-acetyllactosamine structure, but also to paragloboside (lacto-N-neotetraosylceramide), a precursor of the HNK-1 epitope on glycolipids. Furthermore, substrate specificity analysis using a soluble chimeric form of GlcAT-D revealed that GlcAT-D transfers a GlcA not only to Galbeta1-4GlcNAcbeta1-3Galbeta1-4Glc-pyridylamine++ + but also to Galbeta1-3GlcNAcbeta1-3Galbeta1-4Glc-pyridylamine++ +. Enzymatic hydrolysis and Smith degradation of the reaction product indicated that GlcAT-D transfers a GlcA through a beta1,3-linkage to a terminal galactose. The GlcAT-D transcripts were detected in embryonic, postnatal, and adult rat brain. In situ hybridization analysis revealed that the expression pattern of GlcAT-D transcript in embryo is similar to that of GlcAT-P, but distinct expression of GlcAT-D was observed in the embryonic pallidum and retina. Regions that expressed GlcAT-D and/or GlcAT-P were always HNK-1-positive, indicating that both GlcATs are involved in the synthesis of the HNK-1 epitope in vivo.

Amino Acid Sequence↗
PubMed1998

Mutation involving cytochrome P450IID6 in two Japanese patients with neuroleptic malignant syndrome.

Cytochrome P450IID6 (CYP2D6) plays an important role in the hepatic metabolism of various psychotropic drugs. We detected a mutation of the CYP2D6 gene in two patients who previously had episodes of neuroleptic malignant syndrome (NMS). They were homozygous for a mutated CYP2D6J allele conferring a poor-metabolizer phenotype. Possession of this trait may contribute to susceptibility to NMS.

Alleles↗
PubMed1998

Lack of association between neuroleptic malignant syndrome and polymorphisms in the 5-HT1A and 5-HT2A receptor genes.

OBJECTIVE: The molecular basis of neuroleptic malignant syndrome is unclear, but studies suggest that genetic factors are involved in its pathogenesis. Considering possible involvement of the serotonergic system in neuroleptic malignant syndrome, the authors examined the association between neuroleptic malignant syndrome and polymorphisms of the 5-HT1A and 5-HT2A receptor genes. METHOD: The authors examined the frequencies of gene polymorphisms in the 5-HT1A (Arg219Leu) and 5-HT2A (Thr25Asn and His452Tyr) receptor genes in 29 patients previously diagnosed with neuroleptic malignant syndrome, 94 neuroleptic-treated patients with schizophrenia who had no history of neuroleptic malignant syndrome, and 94 healthy comparison subjects. Polymerase chain reaction and restriction fragment length polymorphism analyses were used to screen gene mutations. RESULTS: No polymorphic allele was detected in the patients who had experienced the neuroleptic malignant syndrome. CONCLUSIONS: The authors cannot conclude that polymorphisms in the 5-HT1A and 5HT2A receptor genes are factors determining susceptibility to the neuroleptic malignant syndrome.

Adult↗
PubMed1998

The value of colour Doppler ultrasonography for small bowel involvement of adult Henoch-Schönlein purpura.

Three patients presented with a non-thrombocytopenic purpuric rash on their upper and lower limbs, abdominal pain, diarrhoea, and arthralgia. Grey scale ultrasound showed abnormally thickened walls of the small bowel. Colour Doppler showed blood flow signals in the diseased bowel wall in all patients. Subsequent barium and endoscopic studies showed oedematous bowel loops with petechial lesions. Biopsy from the purpuric rash of the skin demonstrated vasculitis of subdermal small vessels. The clinical diagnosis of Henoch-Schönlein purpura was made in each case. This paper describes the efficacy of grey scale and colour Doppler ultrasonography in the assessment of the small bowel involvement of Henoch-Schönlein purpura.

Adult↗
PubMed1997

[Reliability of Amplicor Mycobacteria test for detection of Mycobacterium tuberculosis complex. M. avium and M. intracellulare: a cooperative study among 9 laboratories].

The Amplicor Mycobacteria, a PCR-based assay, is a rapid test for the detection of Mycobacterium tuberculosis, Mycobacterium avium and Mycobacterium intracellulare in clinical samples. To estimate the reliability and reproducibility of the method, a cooperative blind study was conducted among 9 laboratories. Materials used for testing consisted of 105 sputum and 30 water samples containing known numbers of M. bovis BCG, M. avium, M. intracellulare, and samples without bacteria. Only 2 out of the 9 laboratories correctly identified the presence or absence of mycobacterial DNA in all 135 samples. In sputum samples, 6 out of the 9 laboratories detected mycobacterial DNA in all positive samples, and 4 out of the 9 laboratories correctly reported the absence of DNA in the negative samples, indicating the need for good laboratory practice and development of reference reagents to monitor the performance of the whole study, including pretreatment of clinical samples. The main problem was lack of specificity rather than lack of sensitivity. From about half of the laboratories, false-positive results were reported, however, the ratio was below 6%; 1% (1/106 sputum samples) in 3 laboratories, 1.9% (2/105) in 2 laboratories, and 5.7% (6/105) in one laboratory, respectively. These results indicate that the Amplicor Mycobacteria is quite useful for a rapid diagnosis of tuberculosis.

DNA, Bacterial↗
PubMed1997

[Quantitative evaluation of diabetic gastrointestinal paresis by measuring transit time of the stomach and the digestive canal].

Our subjects comprised eighty six diabetes mellitus (DM) patients without severe complication. To evaluate gastrointestinal motility quantitatively, we measured gastric emptying time by acetaminophen (APAP) method using serum APAP value and oro-cecal transit time (OCTT) by lactulose hydrogen breath test in the subjects and normal controls (NC). Comparing DM patients and NC, mean APAP value was lower and mean OCTT was prolonged in the former. Analysing DM patients' background, patients with peripheral neuropathy had prolonged OCTT than patients without neuropathy did. Comparing patients with higher HbA1c levels and patients with normal HbA1c levels, mean APAP value, which was closer to normal levels, was higher in the former. Analysing symptoms, some of them were apparently related to abnormal gastrointestinal motility. From these results, it was concluded that measuring both gastric emptying and OCTT was a useful method to evaluate slight abnormal motility in DM patients.

Diabetes Mellitus↗
PubMed1995

Natural history of minute sessile colonic adenomas based on radiographic findings. Is endoscopic removal of every colonic adenoma necessary?

PURPOSE: With the development of colonoscopy and double-contrast barium enema, detection of minute sessile colonic adenomas has increased. We evaluated progression of these lesions radiologically and attempted to clarify the natural history. METHODS: A total of 125 minute sessile adenomas (< or = 5 mm in size) with histologic confirmation were examined by double-contrast barium enema at an interval of more than one year. The average follow-up period was 24 (range, 12-36; standard deviation, 9.4) months. To allow for differences in magnification, adenomas increasing in size by 2 mm or more were defined as growing, and the other lesions were defined as unchanged. RESULTS: Eighty-six adenomas showed no interval change in size. Four adenomas decreased 1 mm in size, and 27 adenomas increased 1 mm in size. The remaining eight adenomas (6 percent) increased by 2 or 3 mm in size. None of the adenomas showed any morphologic changes. There was also no difference in degree of histologic atypia between growing and unchanged adenomas. None of the adenomas developed into carcinomas during the follow-up period. CONCLUSIONS: These data show that most minute sessile adenomas remain unchanged in size and morphology over the long term. Accordingly, these adenomas probably should be followed up radiologically or endoscopically to avoid excessive polypectomy.

Adenoma↗
PubMed1994

Isolation, structural determination, and calcium-binding properties of the major glycoprotein present in Bufo japonicus japonicus egg jelly.

Although the previous studies showed that the jelly coat is essential in anuran fertilization under natural conditions, identification and structural studies of the macromolecules that play functional roles have remained to be elucidated. In the present study we isolated acidic glycoproteins (JGP) from the solubilized egg jelly of Bufo japonicus japonicus, and showed that they were the major non-dialyzable macromolecular components of the jelly coat. JGP was a typical mucin-type glycoprotein, and it showed high degree of polydispersity in molecular masses ranging over 100-4000 kDa, but both amino acid and carbohydrate compositions were practically identical among fractions, suggesting that JGP was composed of a repeating glycoprotein unit. Four types of short O-glycan chains were isolated from JGP by reductive beta-elimination and their structures were determined as: Gal beta 1-->3[NeuAc alpha 2-->6]GalNAcol (= N-acetylgalactosaminitol), Fuc alpha 1-->2Gal beta 1-->3 [NeuAc alpha 2-->6]GalNAcol, Fuc alpha 1-->2Gal beta 1-->3[GlcNAc beta 1-->6]GalNAcol, and Fuc alpha 1-->2Gal beta 1-->3-GalNAcol. These carbohydrate units (about 80% of the mass of JGP) were linked to nearly all the serine and threonine residues which accounted for 55% of total amino acid residues. The Ca(2+)-binding property of JGP was studied by equilibrium dialysis. The high Ca(2+)-binding capacity of JGP was abolished by its desialylation of JGP and was highly dependent on the JGP concentration. When the low JGP concentrations as in the hydrated Bufo jelly were used, a 50% increment of both n (the number of binding sites) and Kd (the dissociation constant of JGP-Ca2+) values was observed. This property of JGP is suited to retaining Ca2+ and keeping its concentration at that just necessary for fertilizing sperm.

Animals↗