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Yoshikuni Mizuno

Publications and source records attributed to Yoshikuni Mizuno.

At least 19 recordsLinked to original sources
PubMed2007

The isolation of neural stem cells from the olfactory bulb of Parkinson's disease model.

Hyposmia is one of the characteristic symptoms of PD. We isolated the neurosphere forming cells (NSFCs) from the olfactory bulb (OB) after dopaminergic neuronal loss induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), which is a model of Parkinson's disease. We used BrdU to label dividing cells and isolated NSFCs from the OB of adult mice with or without MPTP to confirm the function of OB in PD models. Seven days after MPTP treatment, BrdU-positive cells were significantly increased in the OB, especially in the glomerular layer (GL) and the subependymal zone (SEZ). The number of neurospheres derived from the adult OB was not decreased in groups receiving MPTP, instead, it was significantly increased at 21 days post-injection and only returned to control levels 40 days after MPTP administration. We also evaluated the differentiation of NSFCs into neural subtypes and found that these NSFCs could be well infected with retrovirus. Adult neurogenesis may be enhanced as a repair system in the tyrosine hydroxylase (TH) positive cells of the OB after MPTP administration. The isolation of neural stem cells from the OB after MPTP administration has helped to establish the cellular basis of neurogenesis and supports a role for the transplant-mediated treatment of PD.

Animals↗
PubMed2007

Placebo-controlled, double-blind dose-finding study of entacapone in fluctuating parkinsonian patients.

We conducted a multicenter randomized, placebo-controlled double-blind parallel-group study in Japanese Parkinson's disease (PD) patients with wearing-off motor fluctuations to determine the clinical efficacy and safety of entacapone as an adjunct to concomitant treatment with levodopa and a dopa decarboxylase inhibitor (DCI). We randomized 341 patients to receive entacapone 100 or 200 mg or placebo per dose of levodopa/DCI for 8 weeks. The primary efficacy variable was on time change while awake, determined by patients' diaries. Mean baseline on time in each group was approximately 8 hours. Mean on time change at final assessment was 1.4 hours each for entacapone 100-mg and 200-mg groups and by 0.5 hours for the placebo group (P < 0.05). The two entacapone doses were equally efficacious. Adverse events occurred in 79 patients (69.9%) in placebo, 82 (72.6%) in 100 mg, and 98 (86.0%) in 200 mg. The most common adverse event with entacapone was an increase in dyskinesias. The overall safety profile was satisfactory in both entacapone groups. In conclusion, both entacapone 100 and 200 mg were equally effective in increasing on time of PD patients with wearing-off fluctuations, although the safety and tolerability profile appeared more favorable for the 100-mg dose.

Aged↗
PubMed2006

p53 protein, interferon-gamma, and NF-kappaB levels are elevated in the parkinsonian brain.

We and other workers found markedly increased levels of proinflammatory cytokines and apoptosis-related proteins in parkinsonian brain. Although the pathogenesis of Parkinson's disease (PD) remains enigmatic, apoptosis might be involved in the degeneration of dopaminergic neurons in PD. To investigate the possible presence of other inflammatory cytokines and/or apoptosis-related protein, the levels of p53 protein, interferon-gamma, and NF-kappaB were measured for the first time in the brain (substantia nigra, caudate nucleus, putamen, cerebellum, and frontal cortex) from control and parkinsonian patients by a highly sensitive sandwich enzyme-linked immunosorbent assay. The p53 protein level in the caudate nucleus was significantly higher in parkinsonian patients than in controls (P<0.05), whereas this protein in the substantia nigra, putamen, and cerebral cortex showed no significant difference between parkinsonian and control subjects. The interferon-gamma level was significantly higher in the nigrostriatal dopaminergic regions (substantia nigra, caudate nucleus, and putamen) in parkinsonian patients than in the controls (P<0.05), but was not significantly different in the cerebellum or frontal cortex between the two groups. In accordance with previous immunohistochemical analysis, the NF-kappaB level in the nigrostriatal dopaminergic regions was significantly higher in parkinsonian patients than in the controls (P<0.05). These data suggest that the significant increase in the levels of p53 protein, interferon-gamma, and NF-kappaB reflect apoptosis and the inflammatory state in the parkinsonian brain and that their elevation is involved in the degeneration of the nigrostriatal dopaminergic neurons.

Adult↗
PubMed2006

Dopaminergic neuronal dysfunction associated with parkinsonism in both a Gaucher disease patient and a carrier.

A clinical association between Gaucher disease and parkinsonism has been demonstrated. We herein report a Japanese patient with type 3 Gaucher disease who was compound heterozygous for F213I and L444P mutations in the glucocerebrosidase gene while his father was heterozygous for the L444P mutation. They both presented with parkinsonism characterized by a predominance of akinetic-rigid signs and a favorable response to anti-Parkinson therapies. We investigated the dopaminergic neuronal function using positron emission tomography (PET) with radioligands, [(11)C] CFT and [(11)C] raclopride. PET studies of both patients demonstrated the [(11)C] CFT uptake to be severely decreased in the putamen and the caudate nucleus, however, the [(11)C] raclopride uptake was normal in the basal ganglia. Although the majority of Gaucher disease patients with parkinsonism tend to be refractory to anti-Parkinson therapies. The clinical features and the findings of the PET studies suggest that patients with parkinsonism associated with the mutation in the glucocerebrosidase gene, even in heterozygosis, may be related to the presynaptic dopaminergic neuronal dysfunction reported in Parkinson's disease. A PET study to evaluate the dopaminergic neuronal function in Gaucher disease would provide both a better understanding of the effects of anti-Parkinson therapies and a help to improve our ability to make an early diagnosis of parkinsonism associated with Gaucher disease.

Adult↗
PubMed2006

Decline of striatal dopamine release in parkin-deficient mice shown by ex vivo autoradiography.

Parkin is the causal gene of autosomal recessive juvenile parkinsonism (AR-JP). Dopamine (DA) metabolism has been linked to Parkinson's disease (PD). To understand the pathogenesis of AR-JP, we generated parkin-deficient mice to assess the status of DA signaling pathway and examine DA release and DA receptor by ex vivo autoradiography. Ex vivo autoradiography using [11C]raclopride showed a clear decrease in endogenous DA release after methamphetamine challenge in parkin-deficient mice. Furthermore, parkin deficiency was associated with considerable upregulation of DA (D1 and D2) receptor binding in vivo in the striatum and increased DA levels in the midbrain. Our results suggest that dopaminergic neurons could behave abnormally before neuronal death.

3,4-Dihydroxyphenylacetic Acid↗
PubMed2006

Nuclear localization of the 20S proteasome subunit in Parkinson's disease.

Considering the involvement of ubiquitin-proteasome system (UPS) in Parkinson's disease (PD), the aim of the present study was to determine the distribution of proteasomes in PD brains. Immunohistochemical studies showed localization of 20S proteasome in the nuclei of neurons of the putamen and substantia nigra of PD. In contrast, no nuclear staining was observed in the same areas of brains of controls. Our results suggest that nuclear localization of 20S proteasome seems to be associated with the pathogenesis of PD.

Adult↗
PubMed2006

Dopaminergic neuronal loss in transgenic mice expressing the Parkinson's disease-associated UCH-L1 I93M mutant.

The I93M mutation in ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1) was reported in one German family with autosomal dominant Parkinson's disease (PD). The causative role of the mutation has, however, been questioned. We generated transgenic (Tg) mice carrying human UCHL1 under control of the PDGF-B promoter; two independent lines were generated with the I93M mutation (a high- and low-expressing line) and one line with wild-type human UCH-L1. We found a significant reduction in the dopaminergic neurons in the substantia nigra and the dopamine content in the striatum in the high-expressing I93M Tg mice as compared with non-Tg mice at 20 weeks of age. Although these changes were absent in the low-expressing I93M Tg mice, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) treatment profoundly reduced dopaminergic neurons in this line as compared with wild-type Tg or non-Tg mice. Abnormal neuropathologies were also observed, such as silver staining-positive argyrophilic grains in the perikarya of degenerating dopaminergic neurons, in I93M Tg mice. The midbrains of I93M Tg mice contained increased amounts of insoluble UCH-L1 as compared with those of non-Tg mice, perhaps resulting in a toxic gain of function. Collectively, our data represent in vivo evidence that expression of UCHL1(I93M) leads to the degeneration of dopaminergic neurons.

Animals↗
PubMed2006

Clustering of risk factors increases the incidence of echolucent carotid plaque in stroke patients.

BACKGROUND: The purpose of this study was to assess the influence of clusters of risk factors on the incidence of echolucent carotid plaque in stroke patients. METHODS: A retrospective analysis of 413 stroke patients who had undergone carotid ultrasonography was performed. High-resolution B-mode ultrasonography was used to evaluate the characteristics of carotid plaque. We investigated the relationships between the incidence of echolucent carotid plaque and clustering of risk factors (hypertension, diabetes mellitus and hyperlipidemia) and stroke subtypes and transient ischemic attack (TIA). RESULTS: Echolucent plaques were present in 10.5% of patients free of risk factors, in 18.8% with a single risk factor (NS), in 27.7% with two risk factors (p <0.01) and in 50.0% with three risk factors (p <0.001), and were significantly more common in patients with multiple risk factors (odds ratio 1.79; 95% CI, 1.05-3.06; p = 0.045). Echolucent plaques were observed in 41.2% of patients with atherothrombotic infarction, in 17.6% with lacunar infarction, in 11.5% with cardioembolic stroke, and in 25.0% with TIA, and were significantly more common in patients with atherothrombotic infarction than in those with lacunar infarction or cardioembolic stroke (p<0.001), or in those with TIA (p <0.05). CONCLUSIONS: The clustering of risk factors increased the incidence of echolucent carotid plaque. Patients with multiple risk factors were at increased risk of echolucent plaque, and these had a significant relationship with atherothrombotic infarction compared with other stroke subtypes and TIA.

Aged↗
PubMed2006

Statistical parametric mapping of immunopositive cell density.

We developed a new method for comparing immunopositive cell densities across groups of animals and creating statistical parametric maps on standardized sections. As an example, we compared Iba-1 (microglial marker) positive cell densities in rats with (n=6) and without (n=6) unilateral injection of 1-methyl-4-phenylpyridinium salt (MPP+). Immunopositive cells were automatically counted in each animal over a coronal section in the midbrain (bregma -5.9 mm) and a positive cell density map was created for each animal. After the positive cell density map was normalized to a template section from an atlas, positive cell densities of the two groups were compared in each pixel over the section and a statistical parameter (p-value from t-test) was mapped on each pixel. We were able to detect significant increases of microglias in the side of MPP+ injection not only in the substantia nigra pars compacta but also in adjacent white matter. We also applied the same analysis to tyrosine hydroxylase stained sections and detected significant decreases of dopamine neurons in the side of MPP+ injection. The new method was proven to be useful for detecting significant changes of cell densities over the entire area of immunostained sections.

1-Methyl-4-phenylpyridinium↗
PubMed2006

Pseudoathetosis caused by migrated cervical disc.

Although pseudoathetosis has been described in various conditions, it has been rarely reported in patients with epidural lesions. We report the first case of a patient with pseudoathetosis caused by a migrated cervical disc. The patient was a 76-year-old woman who presented with progressive clumsiness of the hands and athetotic movements. Electrophysiological studies revealed normal peripheral nerve conduction and delayed and attenuated cortical SEPs. Spinal MRI revealed an epidural mass with gadolinium enhancement at the C3-4 level. An anterior cervical surgery disclosed a migrated disc, and its removal resulted in a marked improvement. Migrated cervical disc should be considered in patients with a profound sensory loss and pseudoathetosis in the hands, because this condition is treatable.

Aged↗
PubMed2006

Genetic vitamin E deficiency does not affect MPTP susceptibility in the mouse brain.

Oxidative stress is involved in the degeneration of the nigrostriatal dopaminergic system in Parkinson's disease (PD). Vitamin E (alpha-tocopherol) is a potent antioxidant in the cell membrane that can trap free radicals and prohibit lipid peroxidation. The retention and secretion of vitamin E are regulated by alpha-tocopherol transfer protein (TTP) in the brain and liver. Dysfunction of TTP results in systemic deficiency of vitamin E in humans and mice, and increased oxidative stress in mouse brain. In this study, we investigated the effect of vitamin E deficiency in PD development by generating an 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD using TTP knockout (TTP-/-) mice. Vitamin E concentration in the brains of TTP+/- mice was half that in TTP+/+ mice, and in TTP-/- mice, was undetectable. MPTP treatment tended to decrease striatal dopamine, but the effect was comparable and not significant in any of the three genotypes. Furthermore, the extent of loss of dopaminergic cell bodies in the substantia nigra did not differ among the groups. One the other hand, oral administration of vitamin E resulted in the partial protection of striatal dopaminergic terminals against MPTP toxicity. Our results suggest that vitamin E does not play a major protective role in MPTP-induced nigrostriatal dopaminergic neurodegeneration in the brain.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed2006

Up-regulation of hMUTYH, a DNA repair enzyme, in the mitochondria of substantia nigra in Parkinson's disease.

There is ample evidence for the involvement of oxidative stress in mitochondrial DNA damage and repair mechanisms in Parkinson's disease (PD). The human MutY homolog (hMUTYH) which removes misincorporated adenine opposite 8-oxoG in DNA functions in post-replication, and is localized in the nuclei and mitochondria. We hypothesized that hMUTYH is involved in the disease process of PD. To test our hypothesis, we performed immunohistochemical and biochemical studies on brains of patients with PD and those of control patients. Our results showed up-regulation of hMUTYH in the mitochondria of the SN of PD patients. Western blot analysis also revealed high hMUTYH levels in PD patients and expression of a 47-kDa molecule in the brains as the major isoform. This molecule was localized within the mitochondria as confirmed by double staining with a mitochondrial marker. To confirm the presence of this molecule, we examined the mRNAs of isoforms that translate to the 47-kDa molecule. Based on the amount of mRNAs, the major molecule was alpha4. Interestingly, this molecule lacks the mitochondria targeting sequence. Our results suggest that hMUTYH might be a useful marker of oxidative stress and that oxidative stress and genomic instability are important in the PD disease process.

Aged↗
PubMed2006

Expression levels of vascular endothelial growth factor and its receptors in Parkinson's disease.

Recently, we confirmed the presence of enhanced neural reconstruction in Parkinson's disease and in an animal model of Parkinson's disease based on increased polysialic acid-like immunoreactivity. Changes in neurogenesis often appear parallel to changes in angiogenesis. Moreover, both these processes share similar modulating factors, like vascular endothelial growth factor (VEGF) and its receptors VEGFR-1 (Flt-1) and VEGFR-2 (Flk-1). Using immunohistochemistry, we identified in this study upregulation of VEGF in the substantia nigra but not in the striatum of patients with Parkinson's disease by enzyme-linked immunosorbent assay. Such overexpression may participate in vascular remodeling and neurogenesis in the substantia nigra of Parkinson's disease.

Aged↗
PubMed2006

Cilostazol protects against brain white matter damage and cognitive impairment in a rat model of chronic cerebral hypoperfusion.

BACKGROUND AND PURPOSE: White matter lesions contribute to cognitive impairment in poststroke patients. The present study was designed to assess the neuroprotective mechanisms of cilostazol, a potent inhibitor of type III phosphodiesterase, through signaling pathways that lead to activation of transcription factor cAMP-responsive element binding protein (CREB) phosphorylation using rat chronic cerebral hypoperfusion model. METHODS: Rats underwent bilateral common carotid artery ligation. They were divided into the cilostazol group (n=80) and the vehicle (control) group (n=80). Performance at the Morris water maze task and immunohistochemistry for 4-hydroxy-2-nonenal (HNE), glutathione-S-transferase-pi (GST-pi), ionized calcium-binding adaptor molecule 1, phosphorylated CREB (p-CREB), Bcl-2, and cyclooxygenase-2 (COX-2) were analyzed at baseline and at 3, 7, 14, 21, and 28 days after hypoperfusion. RESULT: Cilostazol significantly improved spatial learning memory (6.8+/-2.3 seconds; P<0.05) at 7 days after hypoperfusion. Cilostazol markedly suppressed accumulation of HNE-modified protein and loss of GST-pi-positive oligodendrocytes in the cerebral white matter during the early period after hypoperfusion (P<0.05). Cilostazol upregulated p-CREB and Bcl-2 (P<0.05), increased COX-2 expression, and reduced microglial activation in the early period of hypoperfusion. CONCLUSIONS: Our results indicate that cilostazol exerts a brain-protective effect through the CREB phosphorylation pathway leading to upregulation of Bcl-2 and COX-2 expressions and suggest that cilostazol is potentially useful for the treatment of cognitive impairment in poststroke patients.

Animals↗
PubMed2006

Down-regulation of alpha-synuclein expression can rescue dopaminergic cells from cell death in the substantia nigra of Parkinson's disease rat model.

Fibrillization and aggregation of alpha-synuclein may play a critical role in neurodegenerative diseases like Parkinson's diseases. Adeno-associated virus (AAV) vector delivery of an alpha-synuclein ribozyme was tested for its silencing effect on degenerating nigrostriatal neurons in the MPP(+) model of Parkinson's disease. We designed alpha-synuclein ribozyme against human alpha-synuclein gene expression and constructed alpha-synuclein ribozymes-carrying rAAV vector (designated rAAV-SynRz). Co-transfection of rAAV-SynRz and rAAV-alpha-synuclein into HEK293 cells resulted in down-regulation of alpha-synuclein protein expression in vitro. Then, rAAV-SynRz was injected into the substantia nigra (SN) of MPP(+)-treated rats. Cell counts of TH-positive neurons in the SN revealed that rAAV-SynRz significantly protected TH-positive cells against apoptotic death, compared with those of rAAV-EGFP or no rAAV injected rats. Our results indicate that the use of rAAV-SynRz allowed the survival of higher number of TH-positive neurons in SN in the MPP(+) model. Down-regulation of alpha-synuclein expression could be potentially a suitable target for gene therapy of Parkinson's disease.

Adenoviridae↗
PubMed2006

Intrinsic and extrinsic erythropoietin enhances neuroprotection against ischemia and reperfusion injury in vitro.

This study was designed to investigate the neuroprotective effect of intrinsic and extrinsic erythropoietin (EPO) against hypoxia/ischemia, and determine the optimal time-window with respect to the EPO-induced neuroprotection. Experiments were conducted using primary mixed neuronal/astrocytic cultures and neuron-rich cultures. Hypoxia (2%) induces hypoxia-inducible factor-1alpha (HIF-1alpha) activity followed by strong EPO expression in mixed cultures and weak expression in neuron-rich cultures as documented by both western blot and RT-PCR. Immunoreactive EPO was strongly detected in astrocytes, whereas EPOR was only detected in neurons. Neurons were significantly damaged in neuron-rich cultures but were distinctly rescued in mixed cultures. Application of recombinant human EPO (rhEPO) (0.1 U/mL) within 6 h before or after hypoxia significantly increased neuronal survival compared with no rhEPO treatment. Application of rhEPO after onset of reoxygenation achieved the maximal neuronal protection against ischemia/reperfusion injury (6 h hypoxia followed 24 h reoxygenation). Our results indicate that HIF-1alpha induces EPO gene released by astrocytes and acts as an essential mediator of neuroprotection, prove the protective role of intrinsic astrocytic-neuronal signaling pathway in hypoxic/ischemic injury and demonstrate an optimal therapeutic time-window of extrinsic rhEPO in ischemia/reperfusion injury in vitro. The results point to the potential beneficial effects of HIF-1alpha and EPO for the possible treatment of stroke.

Animals↗
PubMed2006

Clinical heterogeneity of alpha-synuclein gene duplication in Parkinson's disease.

OBJECTIVE: Recently, genomic multiplications of alpha-synuclein gene (SNCA) have been reported to cause hereditary early-onset parkinsonism. The objective of this study was to assess the frequency of SNCA multiplications among autosomal dominant hereditary Parkinson's disease (ADPD). METHODS: We screened 113 ADPD probands and 200 sporadic PD cases by quantitative polymerase chain reaction and confirmed SNCA multiplications by fluorescence in situ hybridization (FISH) and comparative genomic hybridization array. RESULTS: Two families (two patients from Family A and one from Family B) with SNCA duplication were identified among ADPD patients. Even though they had the same SNCA duplication, one patient had dementia. Because there was exactly the same difference between the regions originated from each patient, the finding suggests that the phenotype of SNCA multiplication may be also influenced by the range of duplication region. We also detected asymptomatic carriers in the families of both patients. Interestingly, the penetrance ratio was 33.3% (2/6) in one kindred, indicating that the ratio was very much lower than expected. INTERPRETATION: These two newly identified Japanese patients with SNCA duplication and the five previously identified American and European families with SNCA triplication or duplication mutations indicate that the incidence of SNCA multiplication may be more frequent than previously estimated.

Aged↗