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Masahito Yamada

Publications and source records attributed to Masahito Yamada.

At least 19 recordsLinked to original sources
PubMed2007

Geographic difference of mortality of Creutzfeldt-Jakob disease in Japan.

BACKGROUND: The geographic mortality difference of Creutzfeldt-Jakob disease is still unclear in Japan. METHODS: Using vital statistics of Japan for 6 year period between 1999 and 2004 officially published by the government, we observed the mortality from Creutzfeldt-Jakob disease (ICD-10th: A81.0 and A81.8) by prefecture. Standardized mortality ratios were calculated for the 47 prefectures. RESULTS: For the observed 6 years, a total of 792 deaths from Creutzfeldt-Jakob disease were observed whole in Japan. Two prefectures, Akita and Yamanashi, presented significantly high standardized mortality ratios. In addition, Tochigi, Kochi, and Nagasaki showed standardized mortality rates higher than 1.5 without significance. No prefecture had significantly low standardized mortality ratios. CONCLUSION: Some prefectures with high mortality rate from Creutzfeldt-Jakob disease existed in Japan. Some of them had high incidence rate in a survey conducted in 1996 as well.

Adolescent↗
PubMed2006

Vitamin A potently destabilizes preformed alpha-synuclein fibrils in vitro: implications for Lewy body diseases.

Alpha-synuclein (alphaS) is the major component of the filamentous inclusions that constitute defining characteristics of Lewy body diseases (LBD) and multiple system atrophy (MSA). Clinically, antioxidant vitamins, such as vitamin E and the vitamin-like substance coenzyme Q10, have been used in the treatment of LBD with some efficacy. Using fluorescence spectroscopy with thioflavin S, electron microscopy and atomic force microscopy, here we examined the effects of ten antioxidant vitamins and vitamin-like substances, vitamin A (retinol, retinal and retinoic acid), beta-carotene, vitamins B2, B6, C, E, coenzyme Q10 and alpha-lipoic acid, on the formation of alphaS fibrils (falphaS) and on preformed falphaS. Among them, vitamin A, beta-carotene and coenzyme Q10 dose-dependently inhibited the formation of falphaS. Moreover, they also dose-dependently destabilized preformed falphaS. With such potent anti-fibrillogenic as well as fibril-destabilizing activities, these compounds could be useful in the treatment and prevention of LBD and MSA.

Antioxidants↗
PubMed2006

Cerebrospinal fluid of Alzheimer's disease and dementia with Lewy bodies patients enhances alpha-synuclein fibril formation in vitro.

Deposition of alpha-synuclein (alphaS) aggregates inside brain cells is a pathological hallmark of several neurodegenerative diseases, including Parkinson's disease (PD), and dementia with Lewy bodies (DLB). Recently, extracellular alphaS was detected in cerebrospinal fluid (CSF) and plasma of humans. We investigated whether CSF influences alphaS aggregation in vitro using fluorescence spectroscopy with thioflavin S and electron microscopy. We found that CSF obtained from Alzheimer's disease (AD) and DLB patients enhanced the alphaS fibril formation compared with tauopathy and non-central nervous system disease. Thus, CSF of AD and DLB characterized by aggregation of Abeta or alphaS might promote falphaS formation.

Aged↗
PubMed2006

CADASIL with a novel mutation in exon 7 of NOTCH3 (C388Y).

We report a 38-year-old Japanese woman who had cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) with a novel mutation (TGT to TAT) at nucleotide position 1241 (C388Y) in exon 7 of the Notch3 gene (NOTCH3). Immunostaining of a skin biopsy with a Notch3 monoclonal antibody is a beneficial method for the screening of CADASIL, particularly in the case of rare mutations outside the mutation hotspots in NOTCH3 as shown in this patient.

Adult↗
PubMed2006

Neuronal atrophy and synaptic alteration in a mouse model of dentatorubral-pallidoluysian atrophy.

Dentatorubral-pallidoluysian atrophy (DRPLA) is a hereditary spinocerebellar degeneration caused by expansion of a CAG repeat in the disease protein. Despite the restricted and stable brain lesions, DRPLA patients show a variety of clinical symptoms and the brain exhibits generalized atrophy. In previous studies of DRPLA, we proposed that intranuclear diffuse accumulation of the mutant protein is a significant pathological feature of neurons, and that the variable prevalence of this pathology may be relevant to the variation of symptoms observed in patients with different repeat sizes. In this study, to elucidate the pathogenesis of the brain atrophy in DRPLA, we conducted morphological and statistical analyses of neurons affected by the polyglutamine pathology in DRPLA transgenic (Tg) mice with 129 polyglutamine stretches. Golgi-impregnated pyramidal neurons in cerebral cortical layer V of 15-week-old Tg mice showed significant atrophy of the perikarya and dendrites. Dendritic spines were decreased in number and size, and showed a change in morphology resulting in dominance of stubby spines. Interestingly, dendritic arborization was preserved. Electron microscopy revealed that axons in the pyramis and corpus callosum were also atrophic. The number of axonal microtubules was preserved; however, the inter-microtubule spacing was significantly decreased. In the neuropil of cerebral cortical layers II and III, atrophy of the pre-synaptic areas and lengths of the post-synaptic density was detected, but synaptic vesicle diameter was preserved. These results suggest that neuronal atrophy is an essential feature of the cell pathology in DRPLA and that this is closely related to polyglutamine pathogenesis and development of the clinical phenotype.

Animals↗
PubMed2006

Blood-borne factors inhibit Alzheimer's beta-amyloid fibril formation in vitro.

Soluble amyloid beta-protein (Abeta) does not aggregate to beta-amyloid fibrils (fAbeta) in the brain of normal humans. We recently found that the cerebrospinal fluid (CSF) from non-Alzheimer's disease (AD) subjects inhibited the formation of fAbeta(1-40) and fAbeta(1-42) more strongly than that from AD subjects, although the CSF obtained from both groups inhibited the fAbetas formation in vitro. Here, we examined the influence of plasma obtained from AD, non-AD and healthy control (CTL) subjects on the formation of fAbeta(1-40) and fAbeta(1-42) in vitro. Although the plasma obtained from all groups inhibited the formation of fAbeta(1-40) and fAbeta(1-42), the plasma from non-AD and CTL subjects inhibited the formation of fAbetas more strongly than that from AD subjects. These results indicate that the plasma as well as CSF in AD would provide a molecular environment favorable for fAbeta formation, suggesting a decrease of specific inhibitory factors and/or increase of specific accelerating factors.

Aged↗
PubMed2006

Voglibose inhibits postprandial hypotension in neurologic disorders and elderly people.

The authors examined blood pressure, glucose, insulin, and neurotensin before and after intake of 75 g glucose with or without voglibose in 28 neurologic patients and 20 healthy controls. Voglibose significantly prevented hypotension and neurotensin increment after glucose intake and had no influence on glucose or insulin increment. These results suggest that voglibose benefits postprandial hypotension.

Adult↗
PubMed2006

Anti-amyloidogenic effects of antioxidants: implications for the prevention and therapeutics of Alzheimer's disease.

Alzheimer's disease (AD) is one of the most common dementing disorders and has profound medical and social consequences. The initiating molecular event is unknown, and its pathophysiology is highly complex. However, free radical injury appears to be a fundamental process contributing to the neuronal death seen in this disorder, and many studies using surrogate markers of oxidative damage have provided evidence supporting this hypothesis. Various compounds with antioxidant ability attenuated the oxidative stress induced by amyloid beta-protein (Abeta) in studies done in vitro and in vivo. Moreover, various antioxidants have been reported to inhibit the formation and extension of beta-amyloid fibrils (fAbeta), as well as to destabilize preformed fAbeta in vitro. In cell culture experiments, destabilized fAbeta were suggested to be less toxic than intact fAbeta. In transgenic mice model studies, some antioxidant compounds reduced plaque burden in vivo. In this article, we review the recent advances in the research on the antioxidants that inhibit the formation of fAbeta, as well as destabilize preformed fAbeta. Although the mechanisms by which these compounds inhibit fAbeta formation from Abeta, and destabilize preformed fAbeta are still unclear, they could be key molecules for the development of preventives and therapeutics for AD.

Alzheimer Disease↗
PubMed2006

Acute autonomic sensory and motor neuropathy associated with central nervous system disturbance.

We report a 45-year-old woman with acute autonomic sensory and motor neuropathy (AASMN) showing central nervous system (CNS) disturbance. She presented with disturbance of consciousness, complex partial seizures with automatisms, autonomic, sensory and motor neuropathy, showing severe orthostatic hypotension and neurogenic bladder. Nerve conduction studies and nerve biopsy indicated axonal degeneration involving both the myelinated and unmyelinated fibers. Muscle biopsy revealed neurogenic muscular atrophy. Electroencephalogram revealed theta wave activities and sharp wave abnormalities in the frontal lobe. Intravenous immunoglobulin therapy resulted in complete recovery of consciousness levels, but no obvious improvement of the other symptoms. Only eight patients with AASMN have been reported. This is the first report of AASMN showing CNS disturbance. Perivascular lymphocytic infiltration into the temporal lobe and brain stem was described in an autonomic neuropathy patient. An inflammatory pathogenesis of the CNS disturbance associated with this autonomic neuropathy was proposed.

Acute Disease↗
PubMed2006

Elevation of IL-12 p40 and its antibody in myasthenia gravis with thymoma.

We examined the serum levels of cytokines, interferon (IFN)-alpha, IFN-gamma, interleukin (IL)-4, IL-12 p40, and IL-12 p70; those that affect the T helper 1 and 2 balance in patients with myasthenia gravis (MG). Among the cytokines tested, only IL-12 p40, together with the serum titer of anti-IL-12 p40 antibody, was significantly elevated in MG with thymoma. Their elevation was independent of the histopathology of thymoma. Thymectomy decreased the levels of IL-12 p40 accompanied by the anti-acetylcholine receptor antibody, but not anti-IL-12 p40 antibodies. These data strongly suggest the association of IL-12 p40 and its autoantibody with the immunopathology of MG with thymoma.

Adolescent↗
PubMed2006

Antioxidant compounds have potent anti-fibrillogenic and fibril-destabilizing effects for alpha-synuclein fibrils in vitro.

The aggregation of alpha-synuclein (alphaS) in the brain has been implicated as a critical step in the development of Lewy body diseases (LBD) and multiple system atrophy (MSA). Various antioxidants not only inhibit the formation of beta-amyloid fibrils (fAbeta), but also destabilize preformed fAb in vitro. Using fluorescence spectroscopy with thioflavin S and electron microscopy, here we examined the effects of the antioxidants nordihydroguaiaretic acid, curcumin, rosmarinic acid, ferulic acid, wine-related polyphenols [tannic acid, myricetin, kaempferol (+)-catechin and (-)-epicatechin], docosahexaenoic acid, eicosapentaenoic acid, rifampicin and tetracycline on the formation of alphaS fibrils (falphaS) and on preformed falphaS. All molecules, except for docosahexaenoic acid and eicosapentaenoic acid, dose-dependently inhibited the formation of falphaS. Moreover, these molecules dose-dependently destabilized preformed falphaS. The overall activity of the molecules examined was in the order of: tannic acid=nordihydroguaiaretic acid=curcumin=rosmarinic acid=myricetin>kaempferol=ferulic acid>(+)-catechin=(-)-epicatechin>rifampicin=tetracycline. These compounds with anti-fibrillogenic as well as antioxidant activities could be key molecules for the development of preventives and therapeutics for LBD and MSA as well as Alzheimer's disease.

Aged↗
PubMed2006

Immunoglobulin light-chain (AL) amyloidosis with myasthenic symptoms and echocardiographic features of dilated cardiomyopathy.

Myasthenic symptoms and the echocardiographic findings of dilated cardiomyopathy are very rare in primary AL amyloidosis. We report a 59-year-old man with dyspnea on effort and weakness after exercise. His electrocardiogram showed ischemic heart disease and echocardiography indicated dilated cardiomyopathy. Muscle biopsy revealed amyloidosis with deposits of lambda light chain-derived amyloid within the vessel wall. Treatment with PGE1 resulted in improvement of the myasthenic symptoms. This patient indicates that myasthenic symptoms and dilated cardiomyopathy would be a unique syndrome associated with systemic AL amyloidosis involving mainly the small vessels, i.e., AL amyloid angiopathy, in the skeletal muscles and myocardium vessels.

Alprostadil↗
PubMed2006

Allodynia in the flank after thalamic stroke.

Lesions responsible for thalamic pain are often thought to involve the ventral posteromedial nucleus and ventral posterolateral nucleus of the thalamus. We describe two patients with allodynia and hyperpathia in the contralateral flank caused by a small lesion in the posteroventral part of the thalamus. When considered with the literature, involvement of the ventral posteroinferior nucleus may be responsible for this unique post-stroke pain syndrome.

Aged↗
PubMed2006

Alpha-lipoic acid exhibits anti-amyloidogenicity for beta-amyloid fibrils in vitro.

Inhibition of the formation of beta-amyloid fibrils (fAbeta), as well as the destabilization of preformed fAbeta in the CNS would be attractive therapeutic targets for the treatment of Alzheimer's disease (AD). Using fluorescence spectroscopic analysis with thioflavin T and electron microscopic studies, we examined the effects of alpha-lipoic acid (LA) and the metabolic product of LA, dihydrolipoic acid (DHLA), on the formation, extension, and destabilization of fAbeta at pH 7.5 at 37 degrees C in vitro. LA and DHLA dose-dependently inhibited fAbeta formation from amyloid beta-protein, as well as their extension. Moreover, they destabilized preformed fAbetas. LA and DHLA could be key molecules for the development of therapeutics for AD.

Amyloid↗
PubMed2006

Autopsy case of sporadic Creutzfeldt-Jakob disease presenting with signs suggestive of brainstem and spinal cord involvement.

We describe an autopsy case of MM1-type sporadic Creutzfeldt-Jakob disease (CJD), the duration of which was 93 days. The patient was a 59-year-old Japanese man with no family history of prion disease or known iatrogenic exposure to CJD. His first symptom was dysesthesia in the left arm, suggestive of cervical cord involvement, and he showed rapidly progressive neurologic signs, such as dysarthria, dysphagia, lethargy, sleep apnea and respiratory failure, suggestive of brainstem involvement. Progressive mental deterioration combined with episodes of myoclonic seizure and periodic synchronous discharges on the electroencephalogram were observed in the later disease stage. Autopsy showed typical spongiform change to be wide-spread in the cerebral and cerebellar cortices, thalamus and basal ganglia. Synaptic-type PrP deposition was marked in the cerebral cortex, thalamus and basal ganglia. In the cerebellum, although the granular, molecular and Purkinje cell layers were well preserved from neuronal loss and gliosis, PrP deposition was marked in the molecular and granular cell layers. Spongiform degeneration and neuronal loss were not seen in the brainstem and spinal cord, but relatively marked PrP deposition was observed in the quadrigeminal body, substantia nigra, pontine nucleus, inferior olivary nucleus and posterior horn. Immunohistochemical staining for HLA-DR showed proliferation of activated microglia in the cerebral and cerebellar cortices, pontine nucleus, inferior olivary nucleus and posterior horn. The mechanisms underlying the neurologic symptoms and signs were unclear, but we speculate that, in addition to widespread involvement of the cerebral cortex, PrP deposition and microglial activation in the brainstem and spinal cord were responsible.

Brain Stem↗
PubMed2006

The development of preventives and therapeutics for Alzheimer's disease that inhibit the formation of beta-amyloid fibrils (fAbeta), as well as destabilize preformed fAbeta.

Neuritic plaques composed mainly of amyloid beta-protein (Abeta) in the brain are an early and invariant neuropathological feature of Alzheimer's disease (AD). The current search for anti-AD drugs is mainly focused on modification of the process of Abeta deposition in the brain. In this article, the recent development of the molecules that inhibit the formation of beta-amyloid fibrils (fAbeta), as well as destabilize preformed fAbeta is reviewed. Recently, various compounds such as curcumin, nicotine and wine-related polyphenols have been reported to inhibit the formation, extension of fAbeta, as well as destabilize preformed fAbeta at pH 7.5 at 37 degrees C in vitro. In cell culture experiments, destabilized fAbeta were suggested to be less toxic than intact fAbeta. In transgenic mice model study, some coumpounds such as curcumin and nicotine have also been reported to reduce plaque burden in vivo. Although the mechanisms by which these compounds inhibit fAbeta formation from Abeta, and destabilize preformed fAbeta are still unclear, they could be key molecules for the development of preventives and therapeutics for AD.

Alzheimer Disease↗
PubMed2005

Anti-Parkinsonian agents have anti-amyloidogenic activity for Alzheimer's beta-amyloid fibrils in vitro.

Inhibition of the accumulation of amyloid beta-peptide (Abeta) and the formation of beta-amyloid fibrils (fAbeta) from Abeta, as well as the destabilization of preformed fAbeta in the central nervous system would be attractive therapeutic targets for the treatment of Alzheimer's disease (AD). Many studies have demonstrated that oxidative damage plays a central role in AD pathogenesis, as well as Parkinson disease (PD). Among the antioxidant strategies proposed, increasing evidence points to the possibility of achieving neuroprotection by dopamine agonists, as well as monoamine oxidase B (MAO-B) inhibitors. Actually, the beneficial effect of selegiline, a MAO-B inhibitor, in AD has been noted in several clinical studies. On the reverse, antimuscarinic agents have been reported to accelerate beta-amyloidosis and senile plaque formation in PD. Using fluorescence spectroscopic analysis with thioflavin T and electron microscopic studies, we examined the effects of anti-Parkinsonian agents, dopamine, levodopa, pergolide, bromocriptine, selegiline, and trihexyphenidyl on the formation, extension, and destabilization of fAbeta(1-40) and fAbeta(1-42) at pH 7.5 at 37 degrees C in vitro. The anti-Parkinsonian agents other than trihexyphenidyl dose-dependently inhibited fAbeta formation from Abeta(1-40) and Abeta(1-42), as well as their extension. Moreover, these agents dose-dependently destabilized preformed fAbetas. The overall activity of the molecules examined was in the order of: dopamine>selegiline>levodopa=pergolide>bromocriptine. Although the exact mechanism of the anti-amyloidogenic activity of these agents is unclear, these and other structurally related compounds could be key molecules for the development of therapeutics for AD and other conformational diseases.

Amyloid beta-Peptides↗