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Biomedical subjects

S Tsuji

Publications and source records attributed to S Tsuji.

At least 289 records · Page 16Linked to original sources
PubMed1998

Cytotoxic T cells react with recombinant Yo protein from a patient with paraneoplastic cerebellar degeneration and anti-Yo antibody.

Antibodies against autologous tumor cells and neurons are found in the sera or cerebrospinal fluid of patients with paraneoplastic neurological syndromes. Attempts to produce animal models by passive transfer or active immunization, however, have failed, and there is no direct evidence that antibodies cause neuronal damage. Previously, we found that patients with paraneoplastic cerebellar degeneration (PCD) and anti-Yo antibody tested had HLA A24. We now have studied cytotoxic T cell activity in peripheral blood that reacts with recombinant Yo protein when autologous dendritic cells are used as the target. Results suggest that cytotoxic T cells are involved in Purkinje cell loss in PCD.

Antibodies↗
PubMed1998

Formation of granular cytoplasmic aggregates in COS7 cells expressing mutant Cu/Zn superoxide dismutase associated with familial amyotrophic lateral sclerosis.

To investigate the molecular mechanisms of the 'gain of toxic function' of mutant Cu/Zn superoxide dismutase (SOD) associated with familial amyotrophic lateral sclerosis (FALS), mutant (Ala 4 --> Thr, Gly 85 --> Arg, Gly 93 --> Ala, and two base-pair deletion in the 126th codon), as well as wild-type (wt), Cu/Zn SODs were expressed in COS7 cells. The formation of granular cytoplasmic aggregates accompanied by collapse of the cytoplasm was observed in cells expressing mutant (mt) Cu/Zn SODs, but not in cells expressing wt Cu/Zn SOD. The aggregates contained ribosome-like particles and endoplasmic reticulum. These results suggest the possibility that mt Cu/Zn SODs promote the formation of aggregates which are toxic to cells.

Amino Acid Substitution↗
PubMed1998

Expressions of CCAAT/Enhancer-binding proteins beta and delta and their activities are intensified by cAMP signaling as well as Ca2+/calmodulin kinases activation in hippocampal neurons.

The transcription factor, Aplysia CCAAT enhancer-binding protein (ApC/EBP), plays a crucial role in long term facilitation, a synaptic mechanism of long term memory in Aplysia. To gain a clue to whether the mammalian C/EBP family of transcription factors are also involved in long term memory, we examined how C/EBP activities in hippocampal neurons can be modulated in response to cAMP and Ca2+, crucial inductive signals for memory formation. As a result, stimulation of either cAMP or Ca2+ signals in hippocampal neurons was found to enhance mRNA expressions and DNA binding activities of C/EBPbeta and C/EBPdelta. Furthermore, it is indicated that CaM kinases have essential roles for increasing the expression and DNA binding activities of C/EBPbeta in hippocampal neurons activated by membrane depolarization. Overexpression of constitutively active calcium/calmodulin-dependent kinase IV was found to directly stimulate either C/EBPbeta-dependent or C/EBPdelta-dependent transcription, reinforcing the evidence that C/EBP family members contribute to Ca2+-dependent transcription. Thus, these results suggest that C/EBPbeta and C/EBPdelta may be involved in the transcription-dependent phase of memory formation by increasing the expression of both the DNA binding and the transcriptional activities under the direction of cAMP and/or Ca2+ signaling in hippocampal neurons.

Animals↗
PubMed1998

Phenotype variation correlates with CAG repeat length in SCA2--a study of 28 Japanese patients.

Spinocerebellar ataxia-2 (SCA2) is an autosomal dominant ataxia caused by an abnormal CAG repeat expansion in a novel gene on chromosome 12q24.1. The size of the mutant allele is unstable during transmission, and correlates inversely with age at onset. We studied eight Japanese SCA2 families, including 28 patients, to assess the effect of repeat length on the phenotype features of SCA2. Frequencies of slow eye movements (SEM), reflex activity, dementia, choreiform movements, and axial tremor correlated significantly with CAG repeat size. Parkinsonism was seen in a man homozygote for SCA2 mutation. The clinical variety of SCA2 is apparently influenced by the size of the mutant allele, as is the case in other CAG repeat disorders.

Adolescent↗
PubMed1998

A Japanese family with adrenoleukodystrophy with a codon 291 deletion: a clinical, biochemical, pathological, and genetic report.

We report a Japanese family with adrenoleukodystrophy (ALD) with a three base pair deletion (delGAG 291) in the ALD gene. A variety of phenotypes were observed within this family. While the proband (patient 1) was classified as having a rare intermediate type of adult cerebral and cerebello-brain stem forms, his younger brother (patient 2) and nephew (patient 3) had a childhood ALD type. Another nephew (patient 4) of patient 1 was classified as having an adolescent form. The tau level in the cerebrospinal fluid (CSF) in patient 1 was as high as that of patients with Alzheimer's disease (AD). His brain magnetic resonance image (MRI) showed abnormalities in the bilateral cerebellar hemispheres and brain stem, but not in the cerebral white matter, where marked reductions of the cerebral blood flow and oxygen metabolism were clearly demonstrated by positron emission tomography (PET). In patients 2 and 3, the autopsy findings showed massive demyelination of the cerebral white matter with sparing of the U-fibers, compatible with the findings of childhood ALD. Oleic and erucic acids (Lorenzo's Oil) were administered to patients 1 and 4, but sufficient effectiveness was not obtained. The findings in this family suggest that delGAG291 is part of the cause of Japanese ALD with phenotypic variations. Moreover, although the scale of the study is limited, there is a possibility that PET can detect an insidious lesion which is undetectable by computed tomogram (CT) or MRI analysis, and that the higher level of tau reflects the process of neuronal degeneration in ALD. Lorenzo's Oil should be given in the early stage.

Adrenoleukodystrophy↗
PubMed1998

Reduction of the major swine xenoantigen, the alpha-galactosyl epitope by transfection of the alpha2,3-sialyltransferase gene.

alpha2,3-Sialyltransferase represents a putative enzyme that reduces the Galalpha1-3Gal beta1-4GlcNAc-R (the alpha-galactosyl epitope) by intracellular competition with alpha1,3-galactosyltransferase for a common acceptor substrate. This study demonstrates that the overexpression of the alpha2,3-sialyltransferase gene suppresses the antigenicity of swine endothelial cells to human natural antibodies by 77% relative to control cells and by 30% relative to cells transfected with alpha1,2-fucosyltransferase, and in addition, it reduces the complement-mediated cell lysis by 75% compared with control cells and by 22% compared with cells transfected with alpha1, 2-fucosyltransferase. The mechanism by which the alpha-galactosyl epitope was reduced was also studied. Suppression of alpha1, 3-galactosyltransferase activity by 30-63% was observed in the transfectants with alpha2,3-sialyltransferase, and mRNA expression of the alpha1,3-galactosyltransferase gene was reduced as well. The data suggest that the alpha2,3-sialyltransferase effectively reduced the alpha-galactosyl epitope as well as or better than the alpha1, 2-fucosyltransferase did and that the reduction of the alpha-galactosyl epitope is due not only to substrate competition but also to an overall reduction of endogenous alpha1, 3-galactosyltransferase enzyme activity.

Acetylglucosamine↗
PubMed1998

Alpha-synuclein immunoreactivity in glial cytoplasmic inclusions in multiple system atrophy.

Lewy bodies in Parkinson' s disease (PD) are strongly immunoreactive with antibodies against alpha-synuclein, which is mutated in some familial cases of the disease. We carried out immunohistochemical examinations of the brains of multiple system atrophy (MSA) patients using anti-alpha-synuclein antibodies. Strong alpha-synuclein immunoreactivity was found in glial cytoplasmic inclusions (GCIs), which are of oligodendroglial origin and occur exclusively in MSA. Alpha-synuclein-immunoreactive neuronal cytoplasmic inclusions (NCIs) were also found occasionally in the substantia nigra, pontine and inferior olivary nuclei, and dentate fascia. These findings indicate that alpha-synuclein is also a major component of GCIs and NCIs in MSA and strongly suggest that alpha-synuclein aggregation is a common process in certain neurodegenerative diseases, including PD and MSA.

Aged↗
PubMed1998

Cyclooxygenase regulates angiogenesis induced by colon cancer cells.

To explore the role of cyclooxygenase (COX) in endothelial cell migration and angiogenesis, we have used two in vitro model systems involving coculture of endothelial cells with colon carcinoma cells. COX-2-overexpressing cells produce prostaglandins, proangiogenic factors, and stimulate both endothelial migration and tube formation, while control cells have little activity. The effect is inhibited by antibodies to combinations of angiogenic factors, by NS-398 (a selective COX-2 inhibitor), and by aspirin. NS-398 does not inhibit production of angiogenic factors or angiogenesis induced by COX-2-negative cells. Treatment of endothelial cells with aspirin or a COX-1 antisense oligonucleotide inhibits COX-1 activity/expression and suppresses tube formation. Cyclooxygenase regulates colon carcinoma-induced angiogenesis by two mechanisms: COX-2 can modulate production of angiogenic factors by colon cancer cells, while COX-1 regulates angiogenesis in endothelial cells.

Animals↗
PubMed1998

Metabolic labeling of a subset of glial cells by UDP-galactose: implication for astrocyte lineage diversity.

Astrocytes are implicated in many aspects of brain function; however, it remains unclear whether astrocytes arise from a single cell lineage. It is therefore important to obtain new markers for the astrocyte cell lineage. We show that exogenously added UDP-galactose (UDP-Gal) can be used to metabolically label a subset of glial fibrillary acidic protein-positive (GFAP+) cells. UDP-Gal was incorporated into the cultured embryonic mouse brain slices in a time-dependent manner. Surprisingly, the transferred sugar moiety was no longer Gal but was mainly glucose. Most of the radioactivity was transferred to a polymer of glucose, most likely to be glycogen, and also to glucosyl ceramide. In the slice culture, the reaction products were distributed densely in the ventricular zone and also on process-like structures extending to the pial surface. In dissociation culture, UDP-Gal labeled some of the GFAP+ cells and some of the vimentin+ cells. Because radial glial cells (RGCs) contain glycogen and change from vimentin+ to GFAP+, it is strongly suggested that UDP-Gal labeled RGCs and their descendants. Only 27% of the GFAP+ cells were labeled with UDP-Gal, which suggests that only a subset of astrocytes are derived from RGCs and that there is a discrete group of GFAP+ cells that is not generated from RGCs.

Animals↗
PubMed1998

A novel long and unstable CAG/CTG trinucleotide repeat on chromosome 17q.

Using the direct identification of repeat expansion and cloning technique, we cloned a novel long CAG/CTG trinucleotide repeat on chromosome 17. Using radiation hybrid panels, the CAG/CTG repeat was mapped to chromosome 17q. The CAG/CTG repeat is highly polymorphic, with a heterozygosity of 85%, and exhibits a bimodal distribution (allele S, 10-26 repeat units, and allele L, 50-92 repeat units). The CAG/CTG repeat of allele L exhibited intergenerational instabilities, which are more prominent in maternal transmission than in paternal transmission. Analyses of Northern blot and RT-PCR indicate that the repeat is transcribed. Although the size of the CAG/CTG repeat of allele L is within the range of the expanded CAG repeat of disease-causing genes, we did not detect any association of allele L with various neurodegenerative diseases, including frontotemporal dementia and parkinsonism, mapped to 17q21-q23.

Base Sequence↗
PubMed1998

Genomic structure and promoter activity of the mouse polysialic acid synthase (mST8Sia IV/PST) gene.

The mouse gene encoding ST8Sia IV/PST, one of two polysialic acid synthases, was isolated and characterized. The mST8Sia IV/PST gene was found to comprise over 60 kilobases and to be composed of five exons. Primer extension analysis revealed that transcription started from 333 nucleotides upstream of the translational initiation site. Transfection with nested deletion mutants of the 5'-flanking region fused to the luciferase reporter gene revealed that the promoter activity of the -107/+145 region was correlated with the gene expression of mST8Sia IV/PST in embryonal carcinoma P19 and neuroblastoma F11 cells. This proximal promoter region lacks an apparent TATA box but has putative binding sites for transcription factors Sp1 and NF-Y (CCAAT binding protein) at nucleotide positions -66/-57 and -47/-37, respectively. Individual deletions and mutations of the inverted Sp1 binding site or inverted NF-Y binding site caused significant reduction of the promoter activity, indicating that each binding site was involved in essential transcription control. Mobility shift assaying also revealed that Sp1 and NF-Y in a nuclear extract of P19 cells bind to the promoter region of the mST8Sia IV/PST gene. Deletion of the region from -60 to -40, which contains parts of both the Sp1 and NF-Y binding sites, completely abolished the promoter activity, suggesting that both Sp1 and NF-Y are synergetically involved in transcription regulation of the mST8Sia IV/PST gene in P19 and F11 cells. Although the overall structures of the two polysialic acid synthase genes (ST8Sia II/STX and IV/PST) are very similar, there is no extensive sequence homology between the 5'-flanking regions of the ST8Sia II/STX and IV/PST genes, suggesting that these two genes are expressed under different regulatory systems.

Animals↗
PubMed1998

Maternal anticipation in Machado-Joseph disease (MJD): some maternal factors independent of the number of CAG repeat units may play a role in genetic anticipation in a Japanese MJD family.

We studied the relationship between the number of CAG repeat units in the MJD1 gene and clinical features of Machado-Joseph disease (MJD) in eight patients from two generations of a Japanese MJD family. Because of lack of characteristic clinical signs of MJD such as dystonia, bulging eyes or facial myokymia, clinical diagnosis of MJD in this family was difficult to make prior to molecular testing for the CAG repeat expansion in the MJD1 gene. All the patients exhibited maternal transmission of MJD, and the intergenerational change in the number of CAG repeat units in the MJD1 gene was very small (+0.5+/-0.3, mean+/-S.E.M., n=4) in spite of marked genetic anticipation (-17.0 years/generation). In the present family, the degree of anticipation per repeat unit in maternal transmissions was much larger than that in maternal transmissions in the other six MJD families. This indicates that some maternal factors other than the increase of the number of CAG repeat units, which is known to be the basis of anticipation, may play a role in genetic anticipation in this MJD family.

Adult↗
PubMed1998

Lyn-mediated down-regulation of B cell antigen receptor signaling: inhibition of protein kinase C activation by Lyn in a kinase-independent fashion.

Stimulation of the B cell Ag receptor (BCR) induces activation of tyrosine kinases such as Lyn and Syk, phosphorylation and activation of multiple signaling components, and eventually, the expression of several genes including c-myc. Syk is required for activation of phospholipase C-gamma 2 and the subsequent phosphatidylinositol hydrolysis, leading to protein kinase C (PKC) activation and intracellular Ca2+ increase. In contrast, the function of Lyn remains obscure. Here, we report that BCR-mediated induction of c-myc promoter activity and of PKC activity, but not the expression level of functional PKC, was markedly augmented in Lyn-deficient chicken B cells. This enhancement was reversed to the level of wild-type cells by the expression of exogenous Lyn of kinase-inactive form. These results indicate that Lyn inhibits BCR-mediated activation of a large portion of PKC isozymes in a kinase-independent fashion. This finding reveals a novel role of Lyn in negative regulation of BCR signaling.

Animals↗
PubMed1998

Structure, chromosomal location, and expression profile of EXTR1 and EXTR2, new members of the multiple exostoses gene family.

Hereditary multiple exostoses (EXT) is an autosomal dominant disorder that is characterized by the appearance of multiple outgrowths of the long bones (exostoses) at their epiphyses. Genetical heterogeneities have segregated at least on chromosome 8, 11, and 19 and been designated EXT1, EXT2, and EXT3, respectively. Recently, the responsible genes for EXT1 and EXT2 have been isolated and appeared to define a structurally related gene family. In the present study, we have identified novel genes which share significant sequence homologies with the EXT genes. The predicted protein products of the novel EXT-related genes, EXTR and EXTR2 (for EXT-related genes 1 and 2), consist of 919 and 330 amino acid residues, respectively. These genes were transcribed ubiquitously in various tissues. Based on PCR-assisted analyses of both a human/rodent mono-chromosomal hybrid cell panel and a radiation hybrid mapping panel, EXTR1 was localized to the chromosome 8p21 region, where loss of heterozygosity has been frequently observed in various tumors, and EXTR2 was assigned to the chromosome 1p21 region, where osteopetrosis, a dominant hereditary disease of bone, has been mapped by genetic linkage analysis, implying that the protein products of these two EXT-related genes, as well as of the EXT genes, have potential tumor suppressor activity.

Amino Acid Sequence↗
PubMed1998

Suprachiasmatic nucleus in a patient with multiple system atrophy with abnormal circadian rhythm of arginine-vasopressin secretion into plasma.

We performed a quantitative investigation of arginine-vasopressin (AVP) immunopositive neurons in the suprachiasmatic nucleus (SCN), which is the endogenous clock of the brain of a patient with multiple system atrophy (MSA) who exhibited nocturnal polyuria associated with decreased urinary specific gravity and depression of nocturnal AVP secretion. Eleven age- and sex-matched subjects were used as controls. Although, the number of AVP-positive neurons was decreased in neither the supraoptic nucleus nor the paraventricular nucleus, the number of AVP-positive neurons in the SCN was decreased and gliosis was present in the SCN. The cytoplasmic area of AVP-immunopositive neurons in the SCN was smaller in the patient than in the control subjects. These findings raise the possibility that SCN is involved in MSA and the neurodegeneration in the SCN results in altered circadian rhythm of AVP secretion and nocturnal polyuria.

Adult↗
PubMed1998

The GTP cyclohydrolase I gene in Russian families with dopa-responsive dystonia.

OBJECTIVE: To search for mutations in the GTP cyclohydrolase I (GCH-I) gene in a set of Russian families with dopa-responsive dystonia (DRD). DESIGN: Six large families with 54 affected family members and 2 patients with sporadic DRD were examined. Mutation screening was performed using single-strand conformation polymorphism analysis followed by direct sequencing of the presumably mutated exons, in patients whose results showed a normal pattern on single-strand conformation polymorphism analysis, the entire coding region of the GCH-I gene was sequenced. RESULTS: Three new heterozygote point mutations located within exons 1, 2, and 4 of the GCH-I gene were identified in 3 families with autosomal-dominant inheritance. All these mutations are predicted to cause amino acid changes in the highly conserved regions of the gene. In patients from 3 other families and in both patients with sporadic DRD, no alterations in the translated portion of the GCH-I gene were observed. CONCLUSIONS: Mutations in the coding region of the GCH-I gene account for a significant fraction (up to half) of the patients with a typical clinical picture of DRD. None of the mutations in the GCH-I gene described so far were detected more than once, which precludes the possibility of creating simple DNA testing procedures for routine clinical practice.

Amino Acid Sequence↗