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T Ashizawa

Publications and source records attributed to T Ashizawa.

At least 37 records · Page 2Linked to original sources
PubMed2001

Alcohol dehydrogenase polymorphism and Parkinson's disease.

A particular alcohol dehydrogenase (ADH) polymorphism (allele A1) in the promoter region of the gene has been recently demonstrated to be associated with increased risk of Parkinson's disease (PD). In a case control study, we examine frequencies of ADH A1 allele in 100 PD patients (i.e. 200 alleles), 100 diseased controls (i.e. 200 alleles), and 194 healthy controls (i.e. 388 alleles). In addition, we study possible association of a combined non-amyloid component of plaque (NACP-Rep 1) allele and ADH A1 allele with risk of PD. There was no statistical significance of the frequencies of ADH A1 allele between PD patients 12/200 (6%), diseased controls 13/200 (6.5%), and healthy controls 20/388 (5.2%). No strong evidence of an association was found between ADH A1 allele and PD susceptibility in our study patients. There was also no suggestion of linkage disequilibrium between NACP-Rep 1 and ADH A1 alleles.

Adult↗
PubMed2001

"Mitotic drive" of expanded CTG repeats in myotonic dystrophy type 1 (DM1).

In myotonic dystrophy type 1 (DM1), an expanded CTG repeat shows repeat size instability in somatic and germ line tissues with a strong bias toward further expansion. To investigate the mechanism of this expansion bias, 29 DM1 and six normal lymphoblastoid cell lines (LBCLs) were single-cell cloned from blood cells of 18 DM1 patients and six normal subjects. In all 29 cell lines, the expanded CTG repeat alleles gradually shifted toward further expansion by "step-wise" mutations. Of these 29 cell lines, eight yielded a rapidly proliferating mutant with a gain of large repeat size that became the major allele population, eventually replacing the progenitor allele population. By mixing cell lines with different repeat expansions, we found that cells with larger CTG repeat expansion had a growth advantage over those with smaller expansions in culture. This growth advantage was attributable to increased cell proliferation mediated by Erk1,2 activation, which is negatively regulated by p21(WAF1). This phenomenon, which we designated "mitotic drive" , is a novel mechanism which can explain the expansion bias of DM1 CTG repeat instability at the tissue level, on a basis independent of the DNA-based expansion models. The lifespans of the DM1 LBCLs were significantly shorter than normal cell lines. Thus, we propose a hypothesis that DM1 LBCLs drive themselves to extinction through a process related to increased proliferation.

Cell Division↗
PubMed2001

Genetic testing in spinocerebellar ataxias: defining a clinical role.

Although genetic tests for known spinocerebellar ataxia (SCA) genes are increasingly available, their exact clinical role has received much less attention. Currently available DNA tests can define the genotypes of up to two thirds of patients with dominantly inherited SCAs. Certain characteristic clinical features and ethnic predilection of some of the SCA subtypes may help prioritize specific SCA gene testing. Available data on genotype-phenotype correlation suggest that currently available DNA tests cannot accurately predict age of onset or prognosis. Because of the mostly adult-onset symptoms and the absence of effective treatment, genetic counseling is essential for addressing ethical, social, legal, and psychological issues associated with SCA DNA testing.

Animals↗
PubMed2001

Clinical and genetic analysis of four Mexican families with spinocerebellar ataxia type 10.

Spinocerebellar ataxia type 10 (SCA10) is an autosomal dominant disorder caused by expansion of an unstable ATTCT repeat. SCA10 has been described as a pure cerebellar syndrome accompanied by seizures and has been recognized only in families of Mexican origin. We describe clinical and molecular findings of 18 patients in four Mexican families with SCA10. Affected individuals had an average age at onset of 26.7 years (range 14-44 years) and ATTCT repeats ranging from 920 to 4,140 repeats. We could not detect significant anticipation or correlation between repeat size and age at onset, probably due to the small sample size. In addition to pure cerebellar ataxia and seizures, patients often showed soft pyramidal signs, ocular dyskinesia, cognitive impairment, and/or behavioral disturbances. Brain magnetic resonance imaging showed predominant cerebellar atrophy, and nerve conduction studies indicated polyneuropathy in 66% of patients. One family showed hepatic, cardiac, and hematological abnormalities in affected members. These findings suggest that a wide range of tissues may be affected in SCA10, including those outside of the cerebellum and cerebral cortex.

Adolescent↗
PubMed2001

[Recurrent breast cancer successfully treated with a weekly dose of paclitaxel--a case report].

The patient was a 46-year-old women who was treated for axillary lymph node recurrence of breast cancer by a variety of methods, including surgery, chemotherapy, and radiotherapy, but who experienced recurrences in the cervical and mediastinal lymph nodes and skin, and developed hydrothorax and ascites. Although the recurrent foci responded to 4 cycles of CAF chemotherapy, there was concern that the foci would become refractory or resistant to chemotherapy. The administration of paclitaxel was therefore initiated. The patient received a dose of paclitaxel once a week for 5 consecutive weeks followed by a 1-week recovery period (one cycle). After two cycles of the paclitaxel treatment, a marked shrinkage of the lymph nodes and complete resolution of the hydrothorax and ascites were observed. Even though the patient exhibited bone marrow suppression and G-CSF was administered twice for neutropenia, there were no adverse effects except mild alopecia, again suggesting the possibility that paclitaxel is effective chemotherapy for recurrent breast cancer.

Antineoplastic Agents, Phytogenic↗
PubMed2001

[Spinocerebellar ataxia type 10 (SCA10): a disease caused by a novel pentanucleotide repeat expansion].

Spinocerebellar ataxia type 10 (SCA10) is an autosomal dominant progressive disorder characterized by ataxia, seizures and anticipation, mapped to chromosome 22q13.3. We have found that the mutation of SCA10 is an unstable and massive expansion (800-4,500 repeats) of the ATTCT pentanucleotide repeat in intron 9 of SCA 10 (also known as E46L), a novel gene of unknown function. The mutation, so far, has only been found in the population of the Mexican descent with a founder effect supported by haplotype data. The expansion size of the repeat inversely correlates with age of disease onset and SCA10 is highly expressed throughout the central nervous system. Expanded ATTCT repeats in SCA10 patients show repeat size instability in their somatic and germline cells as well as time-dependent instability in blood. This novel type of microsatellite repeat expansion is the largest found to date in human diseases. Its epidemiological, clinical, genetic and pathophysiological features need to be further investigated.

Chromosomes, Human, Pair 22↗
PubMed2000

RNA CUG repeats sequester CUGBP1 and alter protein levels and activity of CUGBP1.

An RNA CUG triplet repeat binding protein, CUGBP1, regulates splicing and translation of various RNAs. Expansion of RNA CUG repeats in the 3'-untranslated repeat of the mutant myotonin protein kinase (DMPK) mRNA in myotonic dystrophy (DM) is associated with alterations in binding activity of CUGBP1. To investigate whether CUGBP1 is directly affected by expansion of CUG repeats in DM tissues, we examined the intracellular status of CUGBP1 in DM patients as well as in cultured cells over expressing RNA CUG repeats. The analysis of RNA-protein complexes showed that, in control tissues, the majority of CUGBP1 is free of RNA, whereas in DM patients the majority of CUGBP1 is associated with RNA containing CUG repeats. Similarly to DM patients, overexpression of RNA CUG repeats in cultured cells results in the re-allocation of CUGBP1 from a free state to the RNA.protein complexes containing CUG repeats. CUG repeat-dependent translocation of CUGBP1 into RNA-protein complexes is associated with increased levels of CUGBP1 protein and its binding activity. Experiments with cyclohexamide-dependent block of protein synthesis showed that the half-life of CUGBP1 is increased in cells expressing CUG repeats. Alteration of CUGBP1 in DM is accompanied by alteration in translation of a transcription factor CCAAT/enhancer-binding protein beta (C/EBPbeta), which has been previously described to be a target of CUGBP1. Analysis of C/EBPbeta isoforms in DM patients with altered levels of CUGBP1 showed that translation of a dominant negative isoform, LIP, is induced by CUGBP1. Results of this paper demonstrate that the expansion of CUG repeats in DM affects RNA-binding proteins and leads to alteration in RNA processing.

Animals↗
PubMed2000

A "dystrophic" variant of autosomal recessive myotonia congenita caused by novel mutations in the CLCN1 gene.

OBJECTIVES: To identify the disease-causing mutation and its molecular consequence for a clinically distinct type of myotonic myopathy. BACKGROUND: The authors encountered a unique myotonic disorder of early onset in a 37-year-old man and his 47-year-old sister. METHODS: After examining known loci of inherited myotonic disorders, the authors looked for mutations within the CLCN1 gene using single strand conformation polymorphism and direct sequencing. To investigate the disease mechanism, reverse transcriptase PCR analyses of total RNA were performed. RESULTS: In the proband and his affected sister, two novel mutations comprising a compound heterozygous state in the CLCN1 gene were identified: 1) a base (G) insertion in exon 7 generating a premature termination codon (fs289X) in the D5 domain, and 2) a C-to-T substitution in exon 23 resulting in a missense mutation (P932L). These mutations accompanied a clinical phenotype that is distinguishable from recessive myotonia congenita by progressive generalized muscle weakness, severe distal muscle atrophy, joint contractures, high serum creatine kinase levels, and conspicuous myopathic changes on muscle histopathology. Reverse transcriptase PCR analyses detected only the P932L mutant mRNA in skeletal muscle, suggesting that the fs289X mRNA is degraded rapidly. CONCLUSIONS: These data suggest that fs289X is a null mutation, rendering the patients with the compound heterozygous genotype of fs289X/P932L to exclusively express P932L homomeric channels that may have caused the "dystrophic" phenotype.

Adult↗
PubMed2000

Variability and validity of polymorphism association studies in Parkinson's disease.

BACKGROUND: In recent years, interest in gene-environment interactions has spurred a great number of association studies on polymorphism of different genes. OBJECTIVE: To review case-control studies of genetic polymorphisms in PD, and perform meta-analysis of individual gene polymorphism. METHODS: The authors searched the Medline database (PubMed) for publications (English language) from January 1966 to November 1999 for association studies in PD. The key words used were "PD" and "polymorphism." The authors supplemented the search with relevant references quoted in these published articles. Those with four or more independent studies of a specific gene polymorphism were subjected to meta-analysis, with the exception of cytochrome-P450 enzyme polymorphisms, for which meta-analyses results were already available in the literature. RESULTS: The authors identified 84 studies on 14 genes, including dopamine receptors (DRD2 and DRD4), dopamine transporter (DAT), monoamine oxidase (MAOA and MAOB), catechol-O-methyltransferase (COMT), N-acetyltransferase 2 (NAT2), APOE, glutathione transferase (GSTT1, GSTM1, GSTP1, and GSTZ1), and mitochondrial genes (tRNAGlu and ND2). Four polymorphisms showed significant association with PD: slow acetylator genotypes of NAT2 (PD:control OR = 1.36), allele >188bp of the MAOB (GT)n polymorphism (OR = 2.58), the deletion allele of GSTT1 (OR = 1.34), and A4336G of tRNAGlu (OR = 3.0). No significant differences were found for the other genes. CONCLUSION: Significant associations with PD were found in polymorphisms of NAT2, MAOB, GSTT1, and tRNAGlu. Although significant association does not imply a causal relationship between the presence of the polymorphisms and PD pathogenesis, their pathophysiologic significance should be studied further.

Apolipoproteins E↗
PubMed2000

Paroxysmal kinesigenic dyskinesia and infantile convulsions: clinical and linkage studies.

OBJECTIVE: To clinically characterize affected individuals in families with paroxysmal kinesigenic dyskinesia (PKD), examine the association with infantile convulsions, and confirm linkage to a pericentromeric chromosome 16 locus. BACKGROUND: PKD is characterized by frequent, recurrent attacks of involuntary movement or posturing in response to sudden movement, stress, or excitement. Recently, an autosomal dominant PKD locus on chromosome 16 was identified. METHODS: The authors studied 11 previously unreported families of diverse ethnic background with PKD with or without infantile convulsions and performed linkage analysis with markers spanning the chromosome 16 locus. Detailed clinical questionnaires and interviews were conducted with affected and unaffected family members. RESULTS: Clinical characterization and sampling of 95 individuals in 11 families revealed 44 individuals with paroxysmal dyskinesia, infantile convulsions, or both. Infantile convulsions were surprisingly common, occurring in 9 of 11 families. In only two individuals did generalized seizures occur in later childhood or adulthood. The authors defined a 26-cM region using linkage data in 11 families (maximum lod score 6.63 at theta = 0). Affected individuals in one family showed no evidence for a shared haplotype in this region, implying locus heterogeneity. CONCLUSIONS: Identification and characterization of the PKD/infantile convulsions gene will provide new insight into the pathophysiology of this disorder, which spans the phenotypic spectrum between epilepsy and movement disorder.

Adolescent↗
PubMed2000

Suppression of experimental myasthenia gravis by monoclonal antibodies against MHC peptide region involved in presentation of a pathogenic T-cell epitope.

We have prepared monoclonal antibodies (mAbs) against an antigen-binding region of I-A, region 62-76 of I-Abeta(b), which is involved in the T-cell participation in the pathogenesis of EAMG. The mAbs reacted with its parent molecules and inhibited the proliferation of disease-related T-cells. Passive transfer of these mAbs suppressed the occurrence of clinical EAMG, which was accompanied by decreased T-cell and Ab responses to tAChR. The results indicated that blocking the function of disease-related MHC by targeting a disease-associated region on MHC molecules could be an effective, straightforward and feasible strategy for immunointervention in MG.

Amino Acid Sequence↗
PubMed2000

Polymorphism of NACP-Rep1 in Parkinson's disease: an etiologic link with essential tremor?

An allele (263bp) of the nonamyloid component of plaques (NACP)-Repl polymorphism has shown association with sporadic PD in a German population. The authors studied this polymorphism in 100 American PD patients and 100 healthy controls. The authors also studied 46 essential tremor (ET) and 55 Huntington's disease (HD) patients. Allele 263bp was significantly higher in PD patients (OR = 3.86) and ET patients (OR = 6.42) but not HD patients, compared with healthy controls. The association of allele 263bp with PD and ET suggests a possible etiologic link between these two conditions.

Adult↗
PubMed2000

An interrupted 34-CAG repeat SCA-2 allele in patients with sporadic spinocerebellar ataxia.

In spinocerebellar ataxia type 2 (SCA-2), a difference of three CAG repeats distinguishes normal alleles (14 to 31 repeats) from pathogenic alleles (34 to 57 repeats). All sequenced pathogenic alleles have a pure CAG repeat structure, whereas interrupted repeats have been seen exclusively in normal alleles. The authors present two patients with sporadic SCA with an interrupted 34-CAG repeat allele, (CAG)24(CAA)(CAG)9, who showed a phenotype compatible with SCA-2. The interrupted allele coding for a 34 pure polyglutamine tract may cause the SCA phenotype.

Aged↗
PubMed2000

Antigen mimicry in autoimmune disease. Can immune responses to microbial antigens that mimic acetylcholine receptor act as initial triggers of Myasthenia gravis?

Myasthenia gravis (MG) is an autoimmune disease caused by autoantibodies against self acetylcholine receptor (AChR). Although a great deal of information is known about the molecular and cellular parameters of the disease, its initial trigger is not known. In order to study the possibility of the involvement of microbial antigens that mimic AChR in triggering MG, we have searched the microbial proteins in the data bank for regions that are similar in structure to the regions of human (h) AChR alpha chain recognized by autoAbs in MG patients. Hundreds of candidate structures on a large number of bacterial and viral proteins were identified. To test the feasibility of the idea, we synthesized four microbial regions similar to each of the major autodeterminants of hAChR (alpha12-27, alpha111-126, alpha122-138, alpha182-200) and investigated their ability to bind autoAbs in MG and normal sera controls. It was found that MG sera recognized a significant number of these microbial regions. The results indicate that in some MG cases immune responses to microbial antigens may cross-react with self antigen (in this case hAChR) and could constitute initial triggers of the disease.

Amino Acid Sequence↗
PubMed2000

Large expansion of the ATTCT pentanucleotide repeat in spinocerebellar ataxia type 10.

Spinocerebellar ataxia type 10 (SCA10; MIM 603516; refs 1,2) is an autosomal dominant disorder characterized by cerebellar ataxia and seizures. The gene SCA10 maps to a 3.8-cM interval on human chromosome 22q13-qter (refs 1,2). Because several other SCA subtypes show trinucleotide repeat expansions, we examined microsatellites in this region. We found an expansion of a pentanucleotide (ATTCT) repeat in intron 9 of SCA10 in all patients in five Mexican SCA10 families. There was an inverse correlation between the expansion size, up to 22.5 kb larger than the normal allele, and the age of onset (r2=0.34, P=0.018). Analysis of 562 chromosomes from unaffected individuals of various ethnic origins (including 242 chromosomes from Mexican persons) showed a range of 10 to 22 ATTCT repeats with no evidence of expansions. Our data indicate that the new SCA10 intronic ATTCT pentanucleotide repeat in SCA10 patients is unstable and represents the largest microsatellite expansion found so far in the human genome.

Animals↗