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Takeshi Hamada

Publications and source records attributed to Takeshi Hamada.

16 recordsLinked to original sources
PubMed2005

CSF pleocytosis and expansion of spinal lesions in Japanese multiple sclerosis with special reference to the new diagnostic criteria.

New diagnostic criteria for multiple sclerosis (MS) were recently proposed from the international panel on the diagnosis of MS, and they include exclusion criteria, such as lesions extending over more than two vertebral segments on spinal MRI and CSF pleocytosis of more than 50/mm3. We reviewed the clinical features of 158 patients who satisfied the diagnostic criteria for MS except for having the above atypical paraclinical findings. All patients exhibited two or more clinical attacks and objective clinical evidence of multiple lesions without any evidence of other disorders. Thirty-three (20.9%) patients had one or both atypical paraclinical findings. Twenty-one out of the 33 patients were classified as having optico-spinal MS (OSMS), and the other 12 as non-OSMS patients with atypical large expanding or destructive cerebral, cerebellar or brainstem lesions on MRI as well as one or both atypical paraclinical findings. Based on this heterogeneity in clinical findings in MS, there is an urgent need to develop a common general concept of the "MS" syndromes, and the ethnic-related heterogeneity should be considered in the revised criteria for the diagnosis of MS.

Adolescent↗
PubMed2005

Synthesis and inhibition mechanism of Delta lac-acetogenins, a novel type of inhibitor of bovine heart mitochondrial complex I.

We have synthesized Deltalac-acetogenins that are new acetogenin mimics possessing two n-alkyl tails without an alpha,beta-unsaturated gamma-lactone ring and suggested that their inhibition mechanism may be different from that of common acetogenins [Hamada et al. (2004) Biochemistry 43, 3651-3658]. To elucidate the inhibition mechanism of Deltalac-acetogenins in more detail, we carried out wide structural modifications of original Deltalac-acetogenins and characterized the inhibitory action with bovine heart mitochondrial complex I. In contrast to common acetogenins, both the presence of adjacent bis-THF rings and the stereochemistry around the hydroxylated bis-THF rings are important structural factors required for potent inhibition. The inhibitory potency of a derivative possessing an n-butylphenyl ether structure (compound 7) appeared to be superior to that of the original Deltalac-acetogenins and equivalent to that of bullatacin, one of the most potent natural acetogenins. Double-inhibitor titration of steady-state complex I activity showed that the extent of inhibition of compound 7 and bullatacin is not additive, suggesting that the binding sites of the two inhibitors are not identical. Competition tests using a fluorescent ligand indicated that the binding site of compound 7 does not overlap with that of other complex I inhibitors. The effects of compound 7 on superoxide production from complex I are also different from those of other complex I inhibitors. Our results clearly demonstrate that Deltalac-acetogenins are a novel type of inhibitor acting at the terminal electron-transfer step of bovine complex I.

Acetogenins↗
PubMed2005

Treatment of cerebellar ataxia with 5-HT1A agonist.

Effective, pharmacologic approaches to the treatment of cerebellar ataxia are lacking or inadequate. We recently reported preliminary evidence that tandospirone citrate (tandospirone), a 5-HT1A agonist, improved cerebellar ataxia in patients with Machado-Joseph disease (MJD). In the course of that study, we found that such treatment also alleviated the pain associated with cold sensations in the legs, insomnia, anorexia, and depression, all of which are thought to be mediated through activation of the 5-HT1A receptor. In this paper, we reviewed the few published clinical trials that involved the use of 5-HT1A receptor agonists for the treatment of cerebellar ataxia, and discussed the current theories regarding their mechanism of action. Cortical cerebellar atrophy (CCA) was reported, in a double-blind study, to be amenable to treatment with tandospirone. Other types of spinocerebellar degeneration (SCD) i.e., olivopontocerebellar atrophy (OPCA) and Machado-Joseph disease (MJD) have also been reported to respond to the drug, but these have been small studies. Responsive patients exhibited only mild ataxia. The doses of 5-HT1A agonists that have been used successfully ranged from 12.5 mg/day to 60 mg/day (or 1 mg/kg), and were well tolerated by most patients.

Buspirone↗
PubMed2004

CTLA-4 gene polymorphism is not associated with conventional multiple sclerosis in Japanese.

We investigated the polymorphisms of exon 1 (+49A/G) and promoter (-318C/T and -651C/T) regions of the CTLA-4 gene in 133 Japanese patients with conventional/classical multiple sclerosis (MS) and 156 healthy controls. Patients with optico-spinal MS (OSMS) or atypical clinical attacks were excluded from the study. There was no significant difference in the distribution of polymorphisms between patients and controls. Furthermore, there were no associations between polymorphisms and clinical characteristics, such as age at onset, disease prognosis, and HLA profiles. Our results suggest that CTLA-4 gene polymorphisms are neither conclusively related to susceptibility nor to the clinical characteristics of MS, especially in Japanese patients with conventional/classical form and clinical features identical to those of their counterparts in Western countries.

Adolescent↗
PubMed2004

Attack-related severity: a key factor in understanding the spectrum of idiopathic inflammatory demyelinating disorders.

Understanding the spectrum of idiopathic inflammatory demyelinating disorders (IIDD) is a fundamental issue for the diagnosis and treatment of these disorders as well as for the approach to their pathogenesis. The spectrum of IIDD is usually classified according to clinical course and lesion distribution. We compared the demographic features, clinical characteristics, laboratory findings, and genetic backgrounds between 193 Japanese patients with and without clinically or radiographically fulminant attacks who all satisfied the diagnostic criteria for multiple sclerosis (MS). "Fulminant attacks" in the current study represent attack-related clinically or radiologically severe relapses but do not necessarily mean severe disability. Patients with fulminant attacks were clinically and immunogenetically distinct from those free of such attacks, and the previously described characteristics of the opticospinal form of MS (OSMS) or neuromyelitis optica (NMO) were mostly shared by patients with fulminant attacks. HLA profiles were similar among patients with fulminant attacks irrespective of the lesion distributions. The GG homozygous and G alleles of the CTLA4 gene A/G coding SNP at position 49 in exon 1 were significantly more common in patients with fulminant attacks than in those without. Attack-related severity may be an important factor if validated by prospective studies defining criteria and establishing relationships to disease course and treatment regimens.

Adolescent↗
PubMed2004

Synthesis and inhibitory action of novel acetogenin mimics with bovine heart mitochondrial complex I.

Studies on the inhibition mechanism of acetogenins, the most potent inhibitors of complex I, are useful to elucidate the structural and functional features of the terminal electron-transfer step of this enzyme. We synthesized acetogenin mimics that possess two alkyl tails without a gamma-lactone ring, named Deltalac-acetogenin, and examined their inhibitory action on bovine heart mitochondrial complex I. Unexpectedly, the Deltalac-acetogenin carrying two n-undecanyl groups (compound 3) elicited very potent inhibition comparable to that of bullatacin. The inhibitory potency of compound 3 markedly decreased with shortening the length of either or both alkyl tails, indicating that symmetric as well as hydrophobic properties of the inhibitor are important for the inhibition. Both acetylation and deoxygenation of either or both of two OH groups adjacent to the tetrahydrofuran (THF) rings resulted in a significant decrease in inhibitory potency. These structural dependencies of the inhibitory action of Deltalac-acetogenins are in marked contrast to those of ordinary acetogenins. Double-inhibitor titration of steady-state complex I activity showed that inhibition of compound 3 and bullatacin are not additive, though the inhibition site of both inhibitors is downstream of iron-sulfur cluster N2. Our results indicate that the mode of inhibitory action of Deltalac-acetogenins differs from that of ordinary acetogenins. Therefore, Deltalac-acetogenins can be regarded as a novel type of inhibitor acting on the terminal electron-transfer step of complex I.

Acetogenins↗
PubMed2004

Essential structural features of acetogenins: role of hydroxy groups adjacent to the bis-THF rings.

The presence of two hydroxy groups adjacent to the THF ring(s) is a common structural feature of natural acetogenins. To elucidate the role of each hydroxy group in the inhibitory action of acetogenins, we synthesized three acetogenin analogues which lack either or both of the hydroxy groups, and investigated their inhibitory activities with bovine heart mitochondrial complex I. Our results indicate that the presence of either of the two hydroxy groups sufficiently sustains a potent inhibitory effect.

Acetogenins↗
PubMed2003

Synthesis and inhibitory activity of ubiquinone-acetogenin hybrid inhibitor with bovine mitochondrial complex I.

To elucidate the inhibitory action of acetogenins, the most potent inhibitors of mitochondrial complex I, we synthesized an acetogenin analogue which possesses a ubiquinone ring (i.e., the physiological substrate of complex I) in place of the alpha,beta-unsaturated gamma-lactone ring of natural acetogenins, and named it Q-acetogenin. Our results indicate that the gamma-lactone ring of acetogenins is completely substitutable with the ubiquinone ring. This fact is discussed in light of the inhibitory action of acetogenins.

Acetogenins↗
PubMed2003

Positional vertigo and macroscopic downbeat positioning nystagmus in spinocerebellar ataxia type 6 (SCA6).

To investigate the frequency of positioning nystagmus in degenerative ataxic disorders, we examined downbeat positioning nystagmus (DPN) in 25 patients with spinocerebellar ataxia type 6 (SCA6) and 58 patients with other types of degenerative ataxia. DPN was observed in 21 of the 25 patients with SCA6 (84 %) versus only 3 of the 58 patients (5.2 %) with other types of degenerative ataxia, including multiple system atrophy, SCA1, SCA2, SCA3/Machado-Joseph disease, and non-SCA6 late-onset pure cerebellar ataxia. Our findings indicated that DPN is a distinct part of the clinical presentation of SCA6, showing that vestibular cerebellum is more affected in SCA6 than other types of degenerative ataxia.

Adult↗
PubMed2003

[Susceptibility genes for multiple sclerosis].

Multiple lines of evidence support the role of genetic factors for susceptibility to multiple sclerosis (MS), although unknown environmental factors must play an important role in developing MS. In this paper, we review the reports studied for the possible associations between Japanese MS and candidate genes by using case-control method. As for HLA alleles, HLA-DRB1*1501 and -DPB1*0501 allele have been confirmed to be associated with conventional MS and opticospinal MS, respectively. Some polymorphisms of vitamin D receptor gene, estrogen receptor gene, CTLA-4 gene, and osteopontin gene were reported to be associated with conventional MS. Appropriate case ascertainment and collection as well as proper statistical method are needed to isolate the susceptibility genes for MS.

Alleles↗
PubMed2002

Estrogen receptor gene polymorphism and multiple sclerosis in Japanese patients: interaction with HLA-DRB1*1501 and disease modulation.

We investigated PvuII and XbaI polymorphism in the estrogen receptor gene (ERG) and HLA-DRB1*1501 positivity in 116 conventional multiple sclerosis (MS) patients and 101 healthy controls in a Japanese population. Logistic analysis revealed independent associations of [P] allele in the profiles for PvuII (p=0.0005, adjusted odds ratio (aOR)=3.17) and DRB1*1501 (p=0.0089, aOR=2.61) with conventional MS. Synergistic elevated risk of MS due to interaction between the [P] allele and HLA-DRB1*1501 allele was found among female patients (odds ratio=16.0; 95% CI=3.99-63.8, p<0.0001). The [P] allele-positive patients with disease duration of more than 5 years had a significantly higher progression index (PI) of disability (p=0.0230) and a worse ranked MS severity score (p=0.0152) than their non-[P] counterparts.

Adolescent↗
PubMed2002

Beneficial effects of tandospirone on ataxia of a patient with Machado-Joseph disease.

Tandospirone citrate (tandospirone) is an anti-anxiety drug that acts by combining with serotonin receptor (5-hydroxytryptamine-1 A [5-HT1A]). Recently, there have been a few reports of its potential role in the treatment of cerebellar ataxia. We report the first case of a patient with Machado-Joseph disease in which we successfully treated cerebellar ataxia. In addition, his leg pain, insomnia, anorexia, and depression, which are thought to be related to 5-HT1A receptors, were also remarkably alleviated by treatment with tandospirone.

Anti-Anxiety Agents↗
PubMedDate not supplied

Effects of tandospirone on "5-HT1A receptor-associated symptoms" in patients with Machado-Josephe disease: an open-label study.

BACKGROUND: We investigated the frequencies of the symptoms such as "ataxia, depression, insomnia, anorexia, and pain," that have been reported to be associated with 5-HT1A receptor, and the effect of tandospirone citrate (tandospirone: 5-HT1A agonist) in patients with Machado-Joseph disease (MJD). METHODS: Ten MJD patients received tandospirone (15-30 mg/d) for seven weeks. During that time, they were evaluated weekly using the Ataxia Rating Scale (ARS) and Total Length Traveled (TLT) by Stabilimetry tests, the Self-rating Depression Scale (SDS), which in addition to evaluating their level of depression, also evaluated their degree of insomnia and anorexia, and a pain questionnaire. RESULTS: Before tandospirone therapy, all patients displayed cerebellar ataxia, while insomnia, and leg pain was observed in 7 patients, depression in 6 patients, and anorexia was observed in 2 patients. In response to treatment, 7 of the 10 patients who were ataxic showed a reduction in their ARS, while 3 of 6 patients showed a reduction in their SDS, and 5 of 7 patients showed an alleviation of their insomnia and leg pain. Both of the affected patients showed a marked improvement in their anorexia. A stabilimetry test could be performed in 7 patients, 5 of whom showed a reduction in TLT. CONCLUSIONS: Our data indicate that the patients with MJD are prone to manifest 5-HT1A receptor-associated symptoms, and tandospirone is a useful drug for these symptoms in patients with MJD, though a double-blind study is needed.

Adult↗