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Biomedical subjects

Hitoshi Takahashi

Publications and source records attributed to Hitoshi Takahashi.

At least 127 records · Page 7Linked to original sources
PubMed2002

Immunohistochemical comparison of alpha- and beta-synuclein in adult rat central nervous system.

We investigated the immunohistochemical localization of alpha- and beta-synuclein (alphaS and betaS) in the adult rat CNS and compared the distribution of these proteins with that of synaptophysin (SYN), a well-established presynaptic marker. Anti-SYN, alphaS and betaS antibodies immunolabeled the neuropil in a punctate pattern. No SYN immunoreactivity was found in the neuronal cytoplasm. In contrast, both anti-alphaS and betaS immunostained the neuronal cytoplasm and nucleus to various extents depending on the brain region. alphaS-positive neurons were found in the olfactory bulb, deeper layers of the cerebral neocortex, substantia nigra and pontine nucleus. Immunoreactivity was most intense in neurons of the substantia nigra. betaS-positive neurons were more widely distributed throughout the CNS: more than 50% of neurons were positive for betaS in the granular cell layer of the olfactory bulb, layer IV of the cerebral cortex, CA3 of the hippocampus, basal ganglia and thalamic reticular nuclei. Moreover, there were differences among these proteins in the distribution pattern of immunoreactivity in the neuropil in some CNS regions. These findings suggest that although alphaS and betaS are concentrated in presynaptic terminals, significant amounts of these proteins are also present in the neuronal perikarya. Furthermore, the distribution of alphaS-positive neurons is similar to that of intraneuronal inclusions in alphaS transgenic animals as well as in human alpha-synucleinopathies.

Animals↗
PubMed2002

Expression of alpha-synuclein, the precursor of non-amyloid beta component of Alzheimer's disease amyloid, in human cerebral blood vessels.

The non-amyloid beta component of Alzheimer's disease amyloid (NAC) is detected in cerebral amyloid angiopathy; and the precursor of NAC is now known to be identical to alpha-synuclein (alpha-S), a major component of Lewy bodies in Parkinson's disease. We studied if cerebral vascular cells express alpha-S. Immunohistochemical studies of human cerebral tissues from control and cerebral amyloid angiopathy patients revealed the expression of alpha-S in vascular endothelial and smooth muscle cells. Then we studied the expression of alpha-S in vitro using cultures of vascular cells. Cultures of human umbilical vein endothelial cells and umbilical artery smooth muscle cells were found to constitutively express alpha-S messenger RNA and protein. alpha-S is normally expressed in vascular cells and may play some physiological role in the vascular wall.

Aged↗
PubMed2002

Neuronal migration disturbance and consequent cytoarchitecture in the cerebral cortex following transplacental administration of methylmercury.

To understand the effects of methylmercury (MeHg) on neuronal migration in the developing cerebral cortex, we performed double administrations of MeHg and 5-bromo-2-deoxyuridine (BrdU) to pregnant rats on different embryonic days (E11, E13, E16 or E21). Histopathological examination of a proportion of the offspring on postnatal day 28 revealed no apparent cytoarchitectural abnormalities in the primary motor and primary somatosensory cortices of the cerebrum. Morphometric analysis revealed no significant differences in total neuron population in either of these areas, and no differences in subpopulations of cells in any of the cortical layers, between any of the MeHg-exposed groups and the control animals. However, BrdU immunohistochemistry revealed an abnormally widespread distribution of the labeled cells throughout cortical layers II-VI of offspring exposed to MeHg on E16 and E21, indicating disruption of the inside-out pattern of neuronal migration. We examined one aspect of cell-fate determination by applying immunohistochemistry with antibodies against calbindin, parvalbumin, calretinin, and gamma-aminobutyric acid, but found no differences in the topographic distributions of the antibody-labeled cells in the cortex between the controls and the MeHg-exposed offspring. These results suggest that it is the extrinsic circumstances - rather than the timing of neuron generation - that regulates the expression of these proteins.

Animals↗
PubMed2002

Subgenomic replicon derived from a cell line infected with the hepatitis C virus.

Recently, cell culture systems have been established, where a hepatitis C virus (HCV) subgenomic replicon was efficiently replicated and maintained for a long period. To see whether a HCV sequence derived from HCV-infected cultured cell sequence can be used for the construction of a functional replicon, a HCV subgenomic RNA carrying a neomycin-resistant gene was constructed using the HCV genome RNA obtained from cultured cells infected with HCV. After transfection, G418-resistant Huh-7 cells were selected and subcloned. Finally, the production of HCV proteins and de novo synthesis of subgenomic RNA were confirmed in the selected cell clone, indicating that this subgenomic RNA replicated in cultured cells and functioned as a replicon. These results suggest that the HCV genome obtained from an in vitro HCV infection system with cultured cells can be used to develop a subgenomic replicon system with diverse HCV sequences.

Cell Line↗
PubMed2002

Direct, Ca2+-dependent interaction between tubulin and synaptotagmin I: a possible mechanism for attaching synaptic vesicles to microtubules.

The synaptic vesicle protein synaptotagmin I probably plays important roles in the synaptic vesicle cycle. However, the mechanisms of its action remain unclear. In this study, we have searched for cytoplasmic proteins that interact with synaptotagmin I. We found that the cytoskeletal protein tubulin directly and stoichiometrically bound to recombinant synaptotagmin I. The binding depended on mm Ca(2+), and 1 mol of tubulin dimer bound 2 mol of synaptotagmin I with half-maximal binding at 6.6 microm tubulin. The Ca(2+) dependence mainly resulted from Ca(2+) binding to the Ca(2+) ligands of synaptotagmin I. The C-terminal region of beta-tubulin and both C2 domains of synaptotagmin I were involved in the binding. The YVK motif in the C2 domains of synaptotagmin I was essential for tubulin binding. Tubulin and synaptotagmin I were co-precipitated from the synaptosome extract with monoclonal antibodies to tubulin and SNAP-25 (synaptosome-associated protein of 25 kDa), indicating the presence of tubulin/synaptotagmin I complex and tubulin binding to synaptotagmin I in SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) complexes. Synaptotagmin I promoted tubulin polymerization and bundled microtubules in the presence of Ca(2+). These results suggest that direct interaction between synaptotagmin I and tubulin provides a mechanism for attaching synaptic vesicles to microtubules in high Ca(2+) concentrations.

Animals↗
PubMed2002

Cerebellar cortical tau pathology in progressive supranuclear palsy and corticobasal degeneration.

Immunohistochemical localization of tau in the cerebellar cortex was carried out using a mouse monoclonal antibody against phosphorylation-dependent tau (AT8) in brain tissue (cerebellum) from 13 patients with progressive supranuclear palsy (PSP), 7 patients with corticobasal degeneration (CBD) and 5 age-matched control subjects. Purkinje cell somata that showed diffuse granular accumulation of cytoplasmic tau were found occasionally in 9 of the 13 patients with PSP (69%) and in 4 of the 7 patients with CBD (57%). Tau-positive doughnut-shaped structures were also found occasionally in the cerebellar molecular layer in 6 of the 13 patients with PSP (46%) and 2 of the 7 patients with CBD (29%). No tau immunoreactivity was detected in the cerebellar cortex in the control tissue. In the tissue from one patient with PSP, we also performed a double-labeling immunofluorescence study with anti-glial fibrillary acidic protein (GFAP) antibody and AT8, as well as an immuno-electron microscopic study with AT8. In tau-positive Purkinje cell somata and dendrites, the reaction product was localized mainly within the rough endoplasmic reticulum and free ribosomes. Tau-positive doughnut-shaped structures were located in the GFAP-positive radial processes of Bergmann's glia and were present in the outer areas of inclusions reminiscent of Lewy bodies, which consist of aggregated pathological tau filaments. In conclusion, we have demonstrated a novel tau pathology that affects Purkinje cells and Bergmann's glia in patients with PSP and CBD, indicating that the cerebellar cortex can be involved in the disease processes in PSP and CBD.

Aged↗
PubMed2002

Dementia and delirium in 4 patients with Machado-Joseph disease.

BACKGROUND: Machado-Joseph disease (MJD; spinocerebellar ataxia type 3) is a hereditary neurodegenerative disease caused by mutation of the MJD1 gene. Patients with MJD usually present with cerebellar ataxia, external ophthalmoplegia, pyramidal and extrapyramidal signs, and muscle wasting. However, it has been reported that these patients do not demonstrate dementia. CASE DESCRIPTION: We noticed symptoms of dementia and delirium in 4 patients with MJD. The symptoms included abnormal behavior, excitation, an uncooperative attitude, crying, disorientation, slow thought processes, hallucinations, and delusions. These symptoms were observed in patients with a relatively young onset age, and after a long clinical course. In these patients, the CAG repeat length in the MJD1 gene was much longer compared with the mean repeat length found in patients with MJD. On electroencephalographical examination, they showed slow background activity, but computed tomography and magnetic resonance imaging scans showed no cerebrocortical atrophy. Neuropathological findings in 2 patients revealed a normal cortical structure on conventional morphological examination, but at immunohistochemical examination, we found abnormal staining by an antipolyglutamine antibody in the cerebrocortical neuronal nuclei. CONCLUSIONS: Symptoms of dementia and delirium in patients with MJD could occur in the late stages, and they might be caused not by loss of cerebrocortical neurons, but by their dysfunction.

Delirium↗
PubMed2002

Late-onset frontotemporal dementia with a novel exon 1 (Arg5His) tau gene mutation.

We report a case of frontotemporal dementia and parkinsonism linked to chromosome 17 of 5 years' duration in an 81-year-old man whose brother had died at age 86 years with dementia. In this patient, we found frontal and temporal neuronal loss, glial-predominant tau deposits, progressive supranuclear palsy-like straight tubules, accumulation of 4-repeat-predominant Sarkosyl-insoluble tau, and a novel exon 1 (Arg5His) tau gene mutation. This mutation decreased microtubule-promoting capacity and increased fibrillation of tau in vitro. Thus, we consider that the Arg5His mutation is an authentic tau gene abnormality responsible for the patient's tau pathology and late-onset dementia.

Age of Onset↗
PubMed2002

Involvement of lysosomes in the pathogenesis of CAG repeat diseases.

In CAG repeat diseases, affected neurons possess many cytoplasmic granules immunopositive for expanded polyglutamine stretches. Electron microscopic immunohistochemistry showed that the granules corresponded to lysosomes of primitive type. The results suggest that, in addition to the ubiquitin/proteasome pathway, mutant proteins with expanded polyglutamine stretches are involved in the lysosomal pathway for protein degradation and that this processing mechanism may serve as a target for a new therapeutic approach to CAG repeat diseases.

Adult↗
PubMed2002

Oligodendrocytic polyglutamine pathology in dentatorubral-pallidoluysian atrophy.

White matter degeneration is one of the pathological conditions of dentatorubral-pallidoluysian atrophy. Autopsy brains exhibited a reduced number of glial cells in the lesions and an involvement of oligodendrocytes in nuclear inclusion formation, which previously has been recognized only as a pathological hallmark in neurons. Dentatorubral-pallidoluysian atrophy transgenic mice showed an increased number of affected glias with increasing age and with larger expansions of CAG repeats. These findings suggest that glial cells in dentatorubral-pallidoluysian atrophy also are involved in the polyglutamine pathogenesis.

Adult↗
PubMed2002

Fluvoxamine augmentation in risperidone-resistant schizophrenia: an open trial.

We investigated the efficacy and safety of augmenting risperidone with fluvoxamine for the treatment of residual positive and negative symptoms in patients with chronic schizophrenia who had shown an incomplete response to risperidone. A total of 30 patients completed the open trial over a 12-week period during which fluvoxamine was added to risperidone. The result from the positive and negative syndrome scale (PANSS) and Simpson-Angus extrapyramidal effects (S-A) scale were examined at baseline, 1, 2, 4, 8 and 12 weeks of treatment. There were no significant differences in PANSS positive, negative and general psychopathology scores, or in S-A scale scores at any point during the treatment. These results suggest that fluvoxamine appears to be ineffective in augmenting the risperidone treatment response in chronic schizophrenic patients. Further controlled trials will be needed to confirm this observation.

Antipsychotic Agents↗
PubMed2002

Demonstration of alpha-synuclein immunoreactivity in neuronal and glial cytoplasm in normal human brain tissue using proteinase K and formic acid pretreatment.

alpha-Synuclein (alphaS), a presynaptic nerve terminal protein, is now known to be a major component of neuronal and glial cytoplasmic inclusions in alpha-synucleinopathies (Lewy body disease and multiple system atrophy). However, alphaS has not been identified in either neuronal or glial cytoplasm in formalin-fixed, paraffin-embedded tissue sections from the normal human brain. Previous studies have shown that pretreatment with either proteinase K or formic acid enhances alphaS immunoreactivity. The aim of the present study was, therefore, to study the effects of pretreatment with proteinase K and formic acid on alphaS immunoreactivity in vibratome sections of brain tissue taken from normal human subjects. In addition to presynaptic staining, alphaS immunostaining was recognized in neuronal perikarya in the pretreated sections; this immunoreactivity was more intense in sections taken from the deeper layers of the cerebral neocortex, the CA2/3 region of the hippocampus, and the substantia nigra. This pattern of alphaS expression coincides with the distribution of intraneuronal inclusions in alphaS transgenic animals as well as in human autopsy tissue taken from patients with Lewy body disease. Furthermore, intense immunoreactivity was also found in the cytoplasm of astrocytes and oligodendrocytes throughout the brain. These findings suggest that a significant amount of alphaS is also present in the neuronal and glial cytoplasm in the normal human brain.

Aged↗
PubMed2002

Influence of the serotonin transporter gene-linked polymorphic region on the antidepressant response to fluvoxamine in Japanese depressed patients.

The presence of the long (l) variant of the serotonin (5-hydroxytryptamine: 5-HT) transporter gene-linked polymorphic region (5-HTTLPR) is reported to be associated with a more favorable and faster antidepressant effect of selective serotonin reuptake inhibitors in Caucasians. The frequency of the l allele is lower in Japanese than in Caucasians; therefore, the antidepressant effect of fluvoxamine can be not as good in Japanese as in Caucasians. The authors investigated whether 5-HTTLPR was associated with the antidepressant response to fluvoxamine in 66 Japanese patients with major depressive disorder in a protocolized-dosing 6-week study. The short (s) allele frequency was significantly higher in the responsive individuals than in the nonresponsive ones (P = .010). The present study suggests that fluvoxamine is not less effective in depressive patients carrying the s allele than in the ones carrying the l allele and it is not less effective in Japanese than in Caucasians.

Adult↗
PubMed2002

Monoamine oxidase: A gene polymorphism, tryptophan hydroxylase gene polymorphism and antidepressant response to fluvoxamine in Japanese patients with major depressive disorder.

Monoamine oxidase A (MAOA) and tryptophan hydroxylase (TPH) are the staple enzymes in the metabolism of serotonin (5-HT). The genetic polymorphisms of these two enzymes might individually alter the production, release, reuptake or degradation of 5-HT during the treatment of selective serotonin reuptake inhibitors (SSRIs), leading to the individual differences in the antidepressant effects of SSRIs. The authors investigated whether a functional polymorphism in the MAOA gene promoter (MAOA-VNTR) and a TPH gene polymorphism in intron 7 (TPH-A218C) were associated with the antidepressant response to fluvoxamine in 66 Japanese patients with major depressive disorder during a 6-week study with a specific dosage plan. Fifty-four patients completed the study. The present study fails to demonstrate that the genetic polymorphisms of MAOA-VNTR and TPH-A218C affect the antidepressant effect of fluvoxamine in Japanese patients with major depressive disorder.

Adult↗
PubMed2002

No association between the serotonergic polymorphisms and incidence of nausea induced by fluvoxamine treatment.

We investigated the association between serotonergic polymorphisms and incidence of nausea, which is the most frequent side-effect of selective serotonin reuptake inhibiters (SSRIs), in 66 patients treated with fluvoxamine in a protocolized-dosing method. We focused on three polymorphisms of serotonin (5-HT) neuronal systems such as 5-HT transporter (5-HTT) gene-linked polymorphic region (5-HTTLPR), a variable number of tandem repeat (VNTR) polymorphism in the second intron of the 5-HTT gene (STin2) and tryptophan hydroxylase (TPH) gene polymorphism in intron 7 (TPH-A218C), which have been reported to possess positive association with treatment response to SSRIs. In addition to this, the relationship between development of nausea and treatment response was also analyzed. Results suggested that these three polymorphisms did not affect the development of fluvoxamine-induced nausea, and that incidence of nausea was not a phenomenon that predicts the treatment response to fluvoxamine.

Adult↗