Alzheimer Disease: Sato S

Sato S, Mizukami K, Asada T. · Department of Psychiatry, Tsukuba Memorial Hospital, Tsukuba, Japan. · Int J Neuropsychopharmacol. · Pubmed #16817981 No free full text.

Abstract: The aim of this study was to assess the efficacy and safety of tandospirone, a 5-HT1A partial agonist, for treatment of behavioural and psychological symptoms of dementia (BPSD). Thirteen outpatients with DSM-IV diagnosis of Alzheimer's type or vascular dementia were enrolled in this study. Their BPSD and cognitive functions were evaluated with the Neuropsychiatric Inventory (NPI) and Mini-Mental State Examination, respectively, for an 8-wk period of treatment. The maximum benefit of tandospirone was achieved at a mean dose of 19.6 mg/d. There were significant improvements in the NPI subscores for delusion, agitation, depression, anxiety, and irritability at 2 or 4 wk after the start of administration of tandospirone. No patients experienced severe adverse effects. The results suggest that tandospirone was effective at improving BPSD symptoms and well-tolerated in elderly demented patients.

Yoshida H, Terada S, Sato S, Kishimoto Y, Ata T, Ohshima E, Honda H, Ishihara T, Kuroda S. · Department of Neuropsychiatry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan. · Dement Geriatr Cogn Disord. · Pubmed #19182480 No free full text.

Abstract: BACKGROUND/AIMS: The frontal assessment battery (FAB) is reported to be a useful tool for screening frontal function. However, the neural substrates involved remain to be elucidated. The aim of the present study was to identify the brain regions responsible for FAB performance in patients with early dementia. We sought a correlation between FAB scores and brain perfusion. METHODS: A total of 117 subjects participated in this study (Alzheimer's disease = 51, frontotemporal dementia = 14, vascular dementia = 13, dementia with Lewy bodies = 7, psychiatric disease = 7, mild cognitive impairment = 11, controls = 14). They underwent brain single photon emission computed tomography with (99m)Tc-ethylcisteinate dimer, and we analyzed the data, using a regional cerebral blood flow (rCBF) quantification software program, 3DSRT (3-dimensional stereotaxic region of interest template). RESULTS: FAB scores had a moderately positive correlation with left callosomarginal and precentral rCBF. Comparison of rCBF between high- and low-scoring FAB groups revealed that the latter showed significantly lower rCBF in the bilateral callosomarginal and left precentral regions. CONCLUSION: The results in this study suggest that the FAB mainly reflects the function of the callosomarginal and precentral segments, especially the left side, and that it might be a valid frontal lobe function test.

Mizukami K, Hatanaka K, Tanaka Y, Sato S, Asada T. · Department of Psychiatry, Institute of Clinical Medicine, University of Tsukuba, Tsukuba City, Japan. · Prog Neuropsychopharmacol Biol Psychiatry. · Pubmed #19166899 No free full text.

Abstract: To clarify the profile of depressive symptoms in major depressive episodes in patients with Alzheimer's disease (AD-MD), we compared AD-MD with major depressive disorder in non-demented elderly patients (MDD) matched for age, using the 17-item Hamilton Rating Scale for Depression (HAM-D(17)). In addition, to clarify which depressive symptoms of AD patients respond to treatment with the selective serotonin and noradrenaline reuptake inhibitor (SNRI) milnacipran, we compared the HAM-D(17) average score and the score of each HAM-D item, the mini-mental state examination (MMSE) score, and GAF score according to the DSM-IV evaluation of AD-MD patients at baseline and at the endpoint (12 weeks). Depressive mood, loss of interest in hobbies and social activities and anxiety (psychic) scored the highest in both AD-MD and MDD groups, while psychomotor retardation scored significantly higher in AD-MD, and insomnia and anxiety (somatic) significantly did so in MDD. We also found that depressive mood, suicidal tendency, loss of interest, psychomotor retardation, anxiety (psychic), gastrointestinal symptoms, general somatic symptoms, and hypochondriasis remarkably improved in patients of AD-MD treated with milnacipran. Our results suggest that in general the profiles of depression in AD-MD and MDD are similar, despite some different clinical features between both conditions. Our study also suggests that milnacipran is promising to treat a broad range of depressive symptoms in AD-MD patients.

Sato S, Xu J, Okuyama S, Martinez LB, Walsh SM, Jacobsen MT, Swan RJ, Schlautman JD, Ciborowski P, Ikezu T. · Department of Pharmacology and Experimental Neuroscience and Center for Neurovirology and Neurodegenerative Disorders, University of Nebraska Medical Center, Omaha, Nebraska 68198-5880, USA. · J Neurosci. · Pubmed #19118186 links to  free full text

Abstract: Tau-tubulin kinase-1 (TTBK1) is involved in phosphorylation of tau protein at specific Serine/Threonine residues found in paired helical filaments, suggesting its role in tauopathy pathogenesis. We found that TTBK1 levels were upregulated in brains of human Alzheimer' disease (AD) patients compared with age-matched non-AD controls. To understand the effects of TTBK1 activation in vivo, we developed transgenic mice harboring human full-length TTBK1 genomic DNA (TTBK1-Tg). Transgenic TTBK1 is highly expressed in subiculum and cortical pyramidal layers, and induces phosphorylated neurofilament aggregation. TTBK1-Tg mice show significant age-dependent memory impairment as determined by radial arm water maze test, which is associated with enhancement of tau and neurofilament phosphorylation, increased levels of p25 and p35, both activators of cyclin-dependent protein kinase 5 (CDK5), enhanced calpain I activity, and reduced levels of hippocampal NMDA receptor types 2B (NR2B) and D. Enhanced CDK5/p35 complex formation is strongly correlated with dissociation of F-actin from p35, suggesting the inhibitory mechanism of CDK5/p35 complex formation by F-actin. Expression of recombinant TTBK1 in primary mouse cortical neurons significantly downregulated NR2B in a CDK5- and calpain-dependent manner. These data suggest that TTBK1 in AD brain may be one of the underlying mechanisms inducing CDK5 and calpain activation, NR2B downregulation, and subsequent memory dysfunction.

Shimizu H, Ghazizadeh M, Sato S, Oguro T, Kawanami O. · Department of Molecular Pathology, Institute of Development and Aging Sciences, Nippon Medical School, Graduate School of Medicine, Kawasaki, 211-8533, Japan. · J Clin Neurosci. · Pubmed #19091577 No free full text.

Abstract: Proteoglycans are important in the pathogenesis of senile dementia of Alzheimer type (SDAT) by participating in amyloidogenesis. Knowledge about specific proteoglycan subtypes in SDAT may be of therapeutic advantage. In this study, we examined proteoglycan constituents of SDAT brains with reference to hyaluronic acid, heparan sulfate (HS), dermatan sulfate and chondroitin sulfate subtypes. Total proteoglycans showed a 1.6-fold increase in the hippocampus and 4.3-fold increase in the gyrus frontalis superior compared to non-demented elderly subjects. The HS subtype showed a 9.3-fold increase in hippocampus and a 6.6-fold increase in gyrus frontalis superior. Immunohistochemical studies of senile plaques revealed the expression of heparan sulfate proteoglycan (HSPG) in a portion of the core of typical plaques. beta-amyloid expression was positive in senile plaques and the degenerated neuronal processes and capillary basement membrane, but was negative in endothelial cells. Microglial cells adjacent to senile plaques were positive for HLA-DR expression, and astroglial cells positive for glial fibrillary acidic protein were scattered around the microglial cells. Immunoelectron microscopic examination showed an electron-dense reaction for HSPG in the thickened basement membrane adjacent to the endothelial cells of capillary vessels, but not inside the endothelial cells. These findings suggest that a markedly increased HSPG in SDAT brains is most likely caused by HSPG from the blood capillary basement membrane and that the degenerated processes around senile plaques may arise from microglial or astroglial cells.

Tatebayashi Y, Planel E, Chui DH, Sato S, Miyasaka T, Sahara N, Murayama M, Kikuchi N, Yoshioka K, Rivka R, Takashima A. · Laboratory for Alzheimer's Disease, Brain Science Institute, The Institute of Physical and Chemical Research (RIKEN), Saitama, Japan. · FASEB J. · Pubmed #16478768 links to  free full text

Abstract: Tauopathies such as Alzheimer disease (AD) probably involve a type of phosphorylation imbalance causing the accumulation of abnormally hyperphosphorylated tau in neurons and/or glias. Investigation of R406W tau mutation may provide insight into such abnormal tau hyperphosphorylation, since this mutation causes AD-like dementia and tauopathy in humans and because it has the unique ability to reduce tau phosphorylation in vitro and in cultured cells. Here we show that R406W mutation primarily disrupts tau phosphorylation at Ser404, a priming phosphorylation site of glycogen synthase kinase-3beta (GSK-3beta), thereby reducing subsequent GSK-3beta-mediated phosphorylation at the PHF-1 site (mostly Ser396). In contrast, c-jun N-terminal kinase (JNK) as activated in the mitotic phase directly hyperphosphorylates R406W tau at the PHF-1 site. This was confirmed by PHF-1 hyperphosphorylation of R406W tau in mitotic cells, its association with cytoplasmic JNK activation, and its inhibition by a JNK inhibitor, SP600125. These data unveil the unknown mechanisms of physiological tau phosphorylation at the PHF-1 site and suggest that cytoplasmic JNK activation may play an important role in the abnormal tau hyperphosphorylation associated with R406W tau mutation and in AD.

Sato S, Mizukami K, Moro K, Tanaka Y, Asada T. · Department of Psychiatry, Tsukuba Memorial Hospital, Tsukuba, Japan. · Psychiatry Clin Neurosci. · Pubmed #16472367 No free full text.

Abstract: The aim of this study was to assess the efficacy of the serotonin-dopamine antagonist perospirone in treating aggressive and agitated behavior in patients with dementia. Six patients were referred to the outpatient clinic of Ishizaki Hospital and were followed for 6 weeks. Their psychiatric diagnoses were made using the DSM-IV. Their behavioral symptoms and degrees of cognitive impairment were measured using the Behavioral Pathology in Alzheimer's Disease (BEHAVE-AD) and the Mini-Mental Examination State. The changes in BEHAVE-AD scores were investigated. Maximum benefit was achieved at a mean perospirone dose of 9.0 mg/day. No patient experienced severe adverse effects. Post-hoc analysis showed significant improvement in the total BEHAVE-AD and aggressiveness subscale scores within 2 weeks. This study suggests that perospirone is effective in improving aggressive and agitated behavioral symptoms in demented patients and is safe to use in elderly patients.

Planel E, Miyasaka T, Launey T, Chui DH, Tanemura K, Sato S, Murayama O, Ishiguro K, Tatebayashi Y, Takashima A. · Laboratory for Alzheimer's Disease, The Institute of Physical and Chemical Research, Wako-shi, Saitama 351-0198, Japan. · J Neurosci. · Pubmed #15014115 links to  free full text

Abstract: Alzheimer's disease (AD) brains contain neurofibrillary tangles (NFTs) composed of abnormally hyperphosphorylated tau protein. Regional reductions in cerebral glucose metabolism correlating to NFT densities have been reported in AD brains. Assuming that reduced glucose metabolism might cause abnormal tau hyperphosphorylation, we induced in vivo alterations of glucose metabolism in mice by starvation or intraperitoneal injections of either insulin or deoxyglucose. We found that the treatments led to abnormal tau hyperphosphorylation with patterns resembling those in early AD brains and also resulted in hypothermia. Surprisingly, tau hyperphosphorylation could be traced down to a differential effect of low temperatures on kinase and phosphatase activities. These data indicate that abnormal tau hyperphosphorylation is associated with altered glucose metabolism through hypothermia. Our results imply that serine-threonine protein phosphatase 2A plays a major role in regulating tau phosphorylation in the adult brain and provide in vivo evidence for its crucial role in abnormal tau hyperphosphorylation in AD.

Tatebayashi Y, Miyasaka T, Chui DH, Akagi T, Mishima K, Iwasaki K, Fujiwara M, Tanemura K, Murayama M, Ishiguro K, Planel E, Sato S, Hashikawa T, Takashima A. · Laboratory for Alzheimer's Disease and Neural Architecture, Brain Science Institute, Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan. · Proc Natl Acad Sci U S A. · Pubmed #12368474 links to  free full text

Abstract: The R406W tau mutation found in frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) causes a hereditary tauopathy clinically resembling Alzheimer's disease. Expression of modest levels of the longest human tau isoform with this mutation under the control of the alpha-calcium-calmodulin-dependent kinase-II promoter in transgenic (Tg) mice resulted in the development of congophilic hyperphosphorylated tau inclusions in forebrain neurons. These inclusions appeared as early as 18 months of age. As with human cases, tau inclusions were composed of both mutant and endogenous wild-type tau, and were associated with microtubule disruption and flame-shaped transformations of the affected neurons. Straight tau filaments were recovered from Sarkosyl-insoluble fractions from only the aged Tg brains. Behaviorally, aged Tg mice had associative memory impairment without obvious sensorimotor deficits. Therefore, these mice that exhibit a phenotype mimicking R406W FTDP-17 provide an animal model for investigating the adverse properties associated with this mutation, which might potentially recapitulate some etiological events in Alzheimer's disease.

Sato S, Tatebayashi Y, Akagi T, Chui DH, Murayama M, Miyasaka T, Planel E, Tanemura K, Sun X, Hashikawa T, Yoshioka K, Ishiguro K, Takashima A. · Laboratory for Alzheimer's Disease, Brain Science Institute, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan. · J Biol Chem. · Pubmed #12191990 links to  free full text

Abstract: Neurofibrillary tangles (NFTs) are found in a wide range of neurodegenerative disorders, including Alzheimer's disease. The major component of NFTs is aberrantly hyperphosphorylated microtubule-associated protein tau. Because appropriate in vivo models have been lacking, the role of tau phosphorylation in NFTs formation has remained elusive. Here, we describe a new model in which adenovirus-mediated gene expression of tau, DeltaMEKK, JNK3, and GSK-3beta in COS-7 cells produces most of the pathological phosphorylation epitopes of tau including AT100. Furthermore, this co-expression resulted in the formation of tau aggregates having short fibrils that were detergent-insoluble and Thioflavin-S-reactive. These results suggest that aberrant tau phosphorylation by the combination of these kinases may be involved in "pretangle," oligomeric tau fibril formation in vivo.

Sun X, Sato S, Murayama O, Murayama M, Park JM, Yamaguchi H, Takashima A. · Lab for Alzheimer's Disease, The Brain Science Institute of RIKEN, 2-1 Hirosawa, Wako, 351-0198 Saitama, Japan. · Neurosci Lett. · Pubmed #11872257 No free full text.

Abstract: To examine the regulation of amyloid secretion in more detail, Abeta sandwich ELISAs with high sensitivity and specificity were developed. Using this technique, we measured Abeta secreted from COS7 cells transiently transfected with APP C100 in the presence of LiCl, a potent glycogen synthase kinase (GSK)-3beta inhibitor. We found that both Abetax-40 and Abetax-42 secretion were reduced by LiCl treatment in a dose-dependent manner. Diminished amyloid secretion was associated with GSK-3beta activity. These results suggest that GSK-3beta might function as a possible mediator for regulating both amyloid deposition and tau pathology in Alzheimer's disease (AD), and that lithium should be re-evaluated as a candidate reagent for preventing AD pathology.

Mann DM, Takeuchi A, Sato S, Cairns NJ, Lantos PL, Rossor MN, Haltia M, Kalimo H, Iwatsubo T. · Clinical Neuroscience Research Group, Department of Medicine, University of Manchester, UK. · Neuropathol Appl Neurobiol. · Pubmed #11489138 No free full text.

Abstract: The pattern of deposition of amyloid beta protein (Abeta) was investigated, using the monoclonal antibodies BA27 and BC05 detecting the C-terminal species Abeta40 and Abeta42(43), in six cases of Alzheimer's disease (AD) due to deletions in exon 9 of PS-1 gene. These cases are characterized histologically by the presence of very large rounded plaques within the frontal cortex, known as 'cotton wool' plaques, composed of both Abeta40 and Abeta42(43) that are relatively free from neuritic changes and glial cell components, and usually devoid of a compact amyloid core. In the cerebellum the plaques are almost entirely of a compact type, again composed of Abeta40 and Abeta42(43), with only few diffuse Abeta42(43) containing plaques. The area fraction of Abeta40, and the ratio between Abeta40 and Abeta42(43), in frontal cortex was significantly higher than that seen in other cases of AD due to different PS-1 mutations, or in cases of sporadic AD, all of similar APO E genotype. The area fractions of Abeta42(43), however, did not significantly differ between these three groups. The unusual nature of the Abeta deposition in these cases may reflect the uniqueness of the mutation, which results in a failure to constitutively cleave the PS-1 holoprotein into its active form, and the effect this might have on APP trafficking and catabolism.