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The efficacy of current treatments is still insufficient for Alzheimer's disease (AD), the most common cause of Dementia. Out of the two pathological hallmarks of AD amyloid-ß plaques and neurofibrillary tangles, comprising of tau protein, tau pathology strongly correlates with the symptoms of AD. Previously, screening for inhibitors of tau aggregation that target recombinant tau aggregates have been attempted. Since a recent cryo-EM analysis revealed distinct differences in the folding patterns of heparin-induced recombinant tau filaments and AD tau filaments, this study focused on AD seed-dependent tau aggregation in drug repositioning for AD. We screened 763 compounds from an FDA-approved drug library using an AD seed-induced tau aggregation in SH-SY5Y cell-based assay. In the first screening, 180 compounds were selected, 72 of which were excluded based on the results of lactate dehydrogenase assay. In the third screening with evaluations of soluble and insoluble tau, 38 compounds were selected. In the fourth screening with 3 different AD seeds, 4 compounds, lansoprazole, calcipotriene, desogestrel, and pentamidine isethionate, were selected. After AD seed-induced real-time quaking-induced conversion, lansoprazole was selected as the most suitable drug for repositioning. The intranasal administration of lansoprazole for 4 months to AD seed-injected mice improved locomotor activity and reduced both the amount of insoluble tau and the extent of phosphorylated tau-positive areas. Alanine replacement of the predicted binding site to an AD filament indicated the involvement of Q351, H362, and K369 in lansoprazole and C-shaped tau filaments. These results suggest the potential of lansoprazole as a candidate for drug repositioning to an inhibitor of tau aggregate formation in AD.
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Neuroinflammation contributes to the pathology and progression of Alzheimer's disease (AD), and it can be observed even with mild cognitive impairment (MCI), a prodromal phase of AD. Free water (FW) imaging estimates the extracellular water content and has been used to study neuroinflammation across several neurological diseases including AD. Recently, the role of gut microbiota has been implicated in the pathogenesis of AD. The relationship between FW imaging and gut microbiota was examined in patients with AD and MCI. Fifty-six participants underwent neuropsychological assessments, FW imaging, and gut microbiota analysis targeting the bacterial 16S rRNA gene. They were categorized into the cognitively normal control (NC) (n = 19), MCI (n = 19), and AD (n = 18) groups according to the neuropsychological assessments. The correlations of FW values, neuropsychological assessment scores, and the relative abundance of gut microbiota were analyzed. FW was higher in several white matter tracts and in gray matter regions, predominantly the frontal, temporal, limbic and paralimbic regions in the AD/MCI group than in the NC group. In the AD/MCI group, higher FW values in the temporal (superior temporal and temporal pole), limbic and paralimbic (insula, hippocampus and amygdala) regions were the most associated with worse neuropsychological assessment scores. In the AD/MCI group, FW values in these regions were negatively correlated with the relative abundances of butyrate-producing genera Anaerostipes, Lachnospiraceae UCG-004, and [Ruminococcus] gnavus group, which showed a significant decreasing trend in the order of the NC, MCI, and AD groups. The present study showed that increased FW in the gray matter regions related to cognitive impairment was associated with low abundances of butyrate producers in the AD/MCI group. These findings suggest an association between neuroinflammation and decreased levels of the short-chain fatty acid butyrate that is one of the major gut microbial metabolites having a potentially beneficial role in brain homeostasis.
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Doença de Alzheimer , Disfunção Cognitiva , Microbioma Gastrointestinal , Humanos , Substância Cinzenta/patologia , Doença de Alzheimer/patologia , Butiratos , Doenças Neuroinflamatórias , RNA Ribossômico 16S , Disfunção Cognitiva/patologia , Imageamento por Ressonância MagnéticaRESUMO
The diagnostic criteria for adult-onset Alzheimer's disease (AD) in patients with Down syndrome (DS) have not been standardised. This study investigated the specific symptoms of AD in the prodromal stage of DS, the mean age at diagnosis at each stage of dementia, and the relationship between intellectual disability (ID) and dementia. PubMed, Web of Science, and Embase were searched for studies on DS, AD, early-stage disease, initial symptoms, and prodromal dementia registered between January 2012 and January 2022. We also performed a meta-analysis of the differences between the mean age at prodromal symptoms and AD diagnosis and the proportion of mild cognitive impairment in patients with mild and moderately abnormal ID. We selected 14 articles reporting the behavioural and psychological symptoms of dementia (BPSD) and memory- and language-related impairments as early symptoms of AD in patients with DS. The specific symptoms of BPSD were classified into five categories: irritability (agitation), apathy, abnormal behaviour, adaptive functioning, and sleep disturbance. The mean age at the diagnosis of prodromal symptoms and AD dementia was 52.7 and 56.2 years, respectively (mean difference, + 3.11 years; 95% CI 1.82-4.40) in the meta-analysis. The diagnosis of mild dementia tended to correlate with ID severity (odds ratio [OR], 1.38; 95% CI 0.87-2.18). The features of behaviour-variant frontotemporal dementia may be clinically confirmed in diagnosing early symptoms of DS-associated AD (DSAD). Moreover, age-appropriate cognitive assessment is important. Further studies are required to evaluate DSAD using a combination of biomarkers and ID-related data.
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Doença de Alzheimer , Síndrome de Down , Sintomas Prodrômicos , Síndrome de Down/complicações , Humanos , Doença de Alzheimer/diagnóstico , Doença de Alzheimer/complicações , Disfunção Cognitiva/etiologia , Disfunção Cognitiva/diagnósticoRESUMO
OBJECTIVE: Amyloid positron emission tomography (PET) can reliably detect senile plaques and fluorinated ligands are approved for clinical use. However, the clinical impact of amyloid PET imaging is still under investigation. The aim of this study was to evaluate the diagnostic impact and clinical utility in patient management of amyloid PET using 18F-florbetapir in patients with cognitive impairment and suspected Alzheimer's disease (AD). We also aimed to determine the cutoffs for amyloid positivity for quantitative measures by investigating the agreement between quantitative and visual assessments. METHODS: Ninety-nine patients suspected of having AD underwent 18F-florbetapir PET at five institutions. Site-specialized physicians provided a diagnosis of AD or non-AD with a percentage estimate of their confidence and their plan for patient management in terms of medication, prescription dosage, additional diagnostic tests, and care planning both before and after receiving the amyloid imaging results. A PET image for each patient was visually assessed and dichotomously rated as either amyloid-positive or amyloid-negative by four board-certified nuclear medicine physicians. The PET images were also quantitatively analyzed using the standardized uptake value ratio (SUVR) and Centiloid (CL) scale. RESULTS: Visual interpretation obtained 48 positive and 51 negative PET scans. The amyloid PET results changed the AD and non-AD diagnosis in 39 of 99 patients (39.3%). The change rates of 26 of the 54 patients (48.1%) with a pre-scan AD diagnosis were significantly higher than those of 13 of the 45 patients with a pre-scan non-AD diagnosis (χ2 = 5.334, p = 0.0209). Amyloid PET results also resulted in at least one change to the patient management plan in 42 patients (42%), mainly medication (20 patients, 20%) and care planning (25 patients, 25%). Receiver-operating characteristic analysis determined the best agreement of the quantitative assessments and visual interpretation of PET scans to have an area under the curve of 0.993 at an SUVR of 1.19 and CL of 25.9. CONCLUSION: Amyloid PET using 18F-florbetapir PET had a substantial clinical impact on AD and non-AD diagnosis and on patient management by enhancing diagnostic confidence. In addition, the quantitative measures may improve the visual interpretation of amyloid positivity.
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Doença de Alzheimer , Amiloidose , Disfunção Cognitiva , Humanos , Doença de Alzheimer/diagnóstico por imagem , Etilenoglicóis , Compostos de Anilina , Disfunção Cognitiva/diagnóstico por imagem , Tomografia por Emissão de Pósitrons/métodos , Amiloide , Encéfalo/metabolismo , Peptídeos beta-Amiloides/metabolismoRESUMO
BACKGROUND: The α-Synuclein (α-Syn) V15A variant has been found in two Caucasian families with Parkinson's disease (PD). However, the significance of this missense variant remained unclear. OBJECTIVE: We sought to elucidate whether V15A could increase aggregation or change phospholipid affinity. METHODS: A sequencing analysis for the SNCA encoding α-Syn from 875 patients with PD and 324 control subjects was performed. Comparing with known pathogenic missense variants of α-Syn, A30P, and A53T, we analyzed the effects of V15A on binding to phospholipid membrane, self-aggregation, and seed-dependent aggregation in cultured cells. RESULTS: Genetic screening identified SNCA c.44 T>C (p.V15A) from two Japanese PD families. The missense variant V15A was extremely rare in several public databases and predicted as pathogenic using in silico tools. The amplification activity of α-Syn V15A fibrils was stronger than that of wild-type α-Syn fibrils. CONCLUSIONS: The discovery of the V15A variant from Japanese families reinforces the possibility that the V15A variant may be a causative variant for developing PD. V15A had a reduced affinity for phospholipids and increased propagation activity compared with wild-type. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
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Doença de Parkinson , alfa-Sinucleína , Humanos , alfa-Sinucleína/genética , alfa-Sinucleína/metabolismo , Linhagem Celular , Mutação de Sentido Incorreto , Doença de Parkinson/metabolismo , FosfolipídeosRESUMO
BACKGROUND & AIMS: Coexistence of obesity and decreased muscle strength, defined as sarcopenic obesity, is often observed in the older adults. The present study investigated whether sarcopenic obesity, defined as reduced handgrip strength and increased body mass index (BMI), is associated with cognitive impairment. METHODS: Study participants include 1615 older adults aged 65-84 years who lived in an urban area of Tokyo, Japan and participated in the Bunkyo Health Study. Mild cognitive impairment (MCI) and dementia were defined based on ≤22 points of Montreal Cognitive Assessment and ≤23 points of the Mine-Mental State Examination, respectively. Handgrip strength was measured using a dynamometer in a standing position. We divided participants into four groups according to their sarcopenia (probable) (handgrip strength <28 kg in men and <18 kg in women) and obesity status (BMI ≥25 kg/m2) as control, obesity, sarcopenia and sarcopenic obesity, and investigated the association between cognitive function, sarcopenia, and obesity status. RESULTS: Mean age was 73.1 ± 5.4 years, and 57.6% of study participants were female. The prevalence of control, obesity, sarcopenia, and sarcopenic obesity was 59.4%, 21.2%, 14.6%, and 4.7%, respectively. The prevalence of MCI and dementia, respectively, was highest in participants with sarcopenic obesity, followed by those with sarcopenia, obesity, and control. After multivariate adjustment, sarcopenic obesity was independently associated with increased odds of MCI and dementia compared with the control (MCI: 2.11 [95% confidence interval, 1.12-3.62]; dementia: 6.17 [2.50-15.27]). CONCLUSIONS: Sarcopenic obesity was independently associated with MCI and dementia among Japanese older adults. Future studies are necessary to clarify the causal relationship.
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Disfunção Cognitiva , Demência , Sarcopenia , Idoso , Disfunção Cognitiva/complicações , Estudos Transversais , Demência/complicações , Demência/epidemiologia , Feminino , Força da Mão/fisiologia , Humanos , Vida Independente , Masculino , Obesidade/complicações , Obesidade/diagnóstico , Obesidade/epidemiologia , Sarcopenia/complicações , Sarcopenia/diagnóstico , Sarcopenia/epidemiologiaRESUMO
To investigate the prevalence and genotype-phenotype correlations of parkin RBR E3 ubiquitin protein ligase (PRKN) variants in Parkinson's disease (PD), we first included 2,527 patients with PD. Through the defined selection, we enrolled 2,322 patients, including 1,204 with familial and 1,118 with sporadic PD. We identified 242 patients harboring PRKN variants, which were thought to be susceptibility factors, comprising 137 patients with familial and 105 with sporadic PD; among the 26 identified variants, 13 were novel. We divided our cohort into 2 groups: heterozygote (hereafter called one-allele) and homozygote or compound heterozygote (hereafter called two-allele). The patients with two-allele were significantly younger at onset than those with one-allele. Six families harbored the complex forms of one- and two-allele in different individuals of the same family. The presence of two-allele reflected more frequent normal values of [123I] metaiodobenzylguanidine myocardial scintigraphy. The log-rank test revealed an exacerbation associated with two-allele over 15 years of the disease course. The patients with PRKN variants showed specific symptoms dependent on the number of mutated alleles.
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Doença de Parkinson , Idade de Início , Estudos de Associação Genética , Heterozigoto , Humanos , Doença de Parkinson/epidemiologia , Ubiquitina-Proteína Ligases/genéticaRESUMO
Insulin resistance and muscle weakness are risk factors for silent lacunar infarcts (SLI), but it is unclear whether they are still independent risk factors when adjusted for each other. In addition, the effect of their combination on SLI is completely unknown. We evaluated SLI, insulin sensitivity, and knee extensor muscle strength by magnetic resonance imaging, PREDIM, and dynamometer, respectively, in 1531 elderly people aged 65-84 years living in an urban area of Tokyo. Among the study subjects, 251 (16.4%) had SLI. Impaired insulin sensitivity (High; 1.00 [reference], Medium; 1.53 [95% confidence interval (CI) 0.94-2.48], Low; 1.86 [1.02-3.39], p for trend 0.047) and reduced muscle strength (High; 1.00 [reference], Medium; 1.40 [0.98-2.02], Low; 1.49 [1.04-2.15], p for trend 0.037) were independently associated with increased risk for SLI in the fully adjusted model. In terms of combined, subjects classified as having the lowest insulin sensitivity and lowest strength were 4.33 times (95% CI 1.64-11.45) more likely to have a SLI than those classified as having the highest insulin sensitivity and highest strength. Impaired insulin sensitivity and reduced muscle strength were independently associated with higher risk of SLI in elderly subjects, and their combination synergistically increased this risk.
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Resistência à Insulina , Modelos Cardiovasculares , Debilidade Muscular , Acidente Vascular Cerebral Lacunar , População Urbana , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Japão/epidemiologia , Masculino , Pessoa de Meia-Idade , Debilidade Muscular/epidemiologia , Debilidade Muscular/fisiopatologia , Estudos Prospectivos , Fatores de Risco , Acidente Vascular Cerebral Lacunar/epidemiologia , Acidente Vascular Cerebral Lacunar/fisiopatologiaRESUMO
BACKGROUND: The amyloid-ß oligomers, consisting of 10-20 monomers (AßO10-20), have strong neurotoxicity and are associated with cognitive impairment in Alzheimer's disease (AD). However, their role in patients with idiopathic normal pressure hydrocephalus (iNPH) is poorly understood. OBJECTIVE: We hypothesized that cerebrospinal fluid (CSF) AßO10-20 accumulates in patients with iNPH, and its clearance after CSF shunting contributes to neurological improvement. We measured CSF AßO10-20 levels before and after CSF shunting in iNPH patients evaluating their diagnostic and prognostic role. METHODS: We evaluated two iNPH cohorts: "evaluation" (cohort-1) with 32 patients and "validation" (cohort-2) with 13 patients. Comparison cohorts included: 27 neurologically healthy controls (HCs), and 16 AD, 15 Parkinson's disease (PD), and 14 progressive supranuclear palsy (PSP) patients. We assessed for all cohorts CSF AßO10-20 levels and their comprehensive clinical data. iNPH cohort-1 pre-shunting data were compared with those of comparison cohorts, using cohort-2 for validation. Next, we compared cohort-1's clinical and CSF data: 1) before and after CSF shunting, and 2) increased versus decreased AßO10-20 levels at baseline, 1 and 3 years after shunting. RESULTS: Cohort-1 had higher CSF AßO10-20 levels than the HCs, PD, and PSP cohorts. This result was validated with data from cohort-2. CSF AßO10-20 levels differentiated cohort-1 from the PD and PSP groups, with an area under receiver operating characteristic curve of 0.94. AßO10-20 levels in cohort-1 decreased after CSF shunting. Patients with AßO10-20 decrease showed better cognitive outcome than those without. CONCLUSION: AßO10-20 accumulates in patients with iNPH and is eliminated by CSF shunting. AßO10-20 can be an applicable diagnostic and prognostic biomarker.
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Peptídeos beta-Amiloides/líquido cefalorraquidiano , Derivações do Líquido Cefalorraquidiano , Hidrocefalia de Pressão Normal/líquido cefalorraquidiano , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/líquido cefalorraquidiano , Doença de Alzheimer/patologia , Biomarcadores/líquido cefalorraquidiano , Encefalopatias/líquido cefalorraquidiano , Estudos de Coortes , Feminino , Humanos , Masculino , Doença de Parkinson/líquido cefalorraquidiano , Paralisia Supranuclear Progressiva/líquido cefalorraquidianoRESUMO
Type 2 diabetes mellitus (T2DM) has long been considered a risk factor for Alzheimer's disease (AD). However, the molecular links between T2DM and AD remain obscure. Here, we reported that serum-/glucocorticoid-regulated kinase 1 (SGK1) is activated by administering a chronic high-fat diet (HFD), which increases the risk of T2DM, and thus promotes Tau pathology via the phosphorylation of tau at Ser214 and the activation of a key tau kinase, namely, GSK-3ß, forming SGK1-GSK-3ß-tau complex. SGK1 was activated under conditions of elevated glucocorticoid and hyperglycemia associated with HFD, but not of fatty acid-mediated insulin resistance. Elevated expression of SGK1 in the mouse hippocampus led to neurodegeneration and impairments in learning and memory. Upregulation and activation of SGK1, SGK1-GSK-3ß-tau complex were also observed in the hippocampi of AD cases. Our results suggest that SGK1 is a key modifier of tau pathology in AD, linking AD to corticosteroid effects and T2DM.
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Doença de Alzheimer/metabolismo , Dieta Hiperlipídica/efeitos adversos , Proteínas Imediatamente Precoces/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Transdução de Sinais , Proteínas tau/metabolismo , Doença de Alzheimer/genética , Doença de Alzheimer/patologia , Animais , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/patologia , Ativação Enzimática/genética , Glicogênio Sintase Quinase 3 beta/genética , Glicogênio Sintase Quinase 3 beta/metabolismo , Humanos , Proteínas Imediatamente Precoces/genética , Camundongos , Camundongos Transgênicos , Complexos Multiproteicos/genética , Complexos Multiproteicos/metabolismo , Proteínas Serina-Treonina Quinases/genética , Proteínas tau/genéticaRESUMO
Although l-carnitine alleviated white-matter lesions in an experimental study, the treatment effects of l-carnitine on white-matter microstructural damage and cognitive decline in hemodialysis patients are unknown. Using novel diffusion magnetic resonance imaging (dMRI) techniques, white-matter microstructural changes together with cognitive decline in hemodialysis patients and the effects of l-carnitine on such disorders were investigated. Fourteen hemodialysis patients underwent dMRI and laboratory and neuropsychological tests, which were compared across seven patients each in two groups according to duration of l-carnitine treatment: (1) no or short-term l-carnitine treatment (NSTLC), and (2) long-term l-carnitine treatment (LTLC). Ten age- and sex-matched controls were enrolled. Compared to controls, microstructural disorders of white matter were widely detected on dMRI of patients. An autopsy study of one patient in the NSTLC group showed rarefaction of myelinated fibers in white matter. With LTLC, microstructural damage on dMRI was alleviated along with lower levels of high-sensitivity C-reactive protein and substantial increases in carnitine levels. The LTLC group showed better achievement on trail making test A, which was correlated with amelioration of disorders in some white-matter tracts. Novel dMRI tractography detected abnormalities of white-matter tracts after hemodialysis. Long-term treatment with l-carnitine might alleviate white-matter microstructural damage and cognitive impairment in hemodialysis patients.
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Carnitina/administração & dosagem , Disfunção Cognitiva/prevenção & controle , Demência Vascular/prevenção & controle , Falência Renal Crônica/terapia , Fármacos Neuroprotetores/administração & dosagem , Diálise Renal/efeitos adversos , Administração Oral , Idoso , Idoso de 80 Anos ou mais , Disfunção Cognitiva/diagnóstico , Disfunção Cognitiva/etiologia , Estudos Transversais , Demência Vascular/diagnóstico , Demência Vascular/etiologia , Demência Vascular/patologia , Imagem de Tensor de Difusão , Esquema de Medicação , Feminino , Humanos , Falência Renal Crônica/complicações , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Fatores de Tempo , Resultado do Tratamento , Substância Branca/diagnóstico por imagem , Substância Branca/efeitos dos fármacos , Substância Branca/patologiaRESUMO
Dementia has an enormous impact on medical and financial resources in aging societies like Japan. Diagnosis of dementia can be made by physical and mental examinations, imaging tests, and findings of high abnormal proteins in cerebrospinal fluids. In addition, genetic tests can be performed in neurodegenerative diseases such as Alzheimer's disease (AD), frontotemporal dementia (FTD), and Parkinson's disease (PD). In this case series, we presented three cases of dementia with unknown causes who carry novel variants in the genes associated with neurodegenerative diseases. Three patients (Patients 1, 2, and 6) were found by screening 18 dementia patients using a gene panel including 63 genes. The age of onset for Patient 1 was 74 years old, and his father had PD and mother had AD. The age of onset for Patient 2 was 75 years old, and her mother had AD. The age of onset for Patient 6 was 83 years old, and her father, two sisters, and daughter had dementia. The Mini-Mental State Examination produced results of 20, 15, and 22, respectively. The suspected diagnosis by neurological examinations and imaging studies for Patients 1 and 2 was AD, and for Patient 6 was FTD. Patient 1 was treated with donepezil; Patient 2 was treated with donepezil and memantine; and Patient 6 was treated with donepezil, galantamine, and rivastigmine. The three rare variants identified were: CLCN1, encoding a chloride channel, c.2848G>A:p.Glu950Lys (Patient 1); RYR2, encoding a calcium releasing ryanodine receptor, c.13175A>G:p.Lys4392Arg (Patient 2); and DCTN1, encoding a subunit of dynactin, c. 3209G>A:p.Arg1070Gln (Patient 6). The detected variants were interpreted according to the American College of Medical Genetics (ACMG) guidelines. The minor allele frequency for each variant was 0.025%, 0.023%, and 0.0004% in East Asians, respectively. The DCTN1 variant found in Patient 6 might be associated with FTD. Although none of them were previously reported in dementia patients, all variants were classified as variants of unknown significance (VUS). Our report suggests that results of genetic tests in elderly patients with dementia need to be carefully interpreted. Further data accumulation of genotype-phenotype relationships and development of appropriate functional models are warranted.
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Different conformational strains of tau have been implicated in the clinicopathological heterogeneity of tauopathies. In this study, we hypothesized that distinct strains are degraded in a different manner. Lithium, a drug for bipolar disorder, had previously been reported to reduce aggregation-prone protein content by promoting autophagy. Here, we assessed the effects of lithium on tau aggregates using different tauopathy brain seeds. SH-SY5Y cells were transfected with C-terminal tau fragment Tau-CTF24 (residues 243-441), and Alzheimer's disease (AD), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD) brain seeds were introduced. After 48-h lithium treatment, sarkosyl-insoluble fractions were prepared. Lithium treatment was found to reduce the amount of insoluble tau and p62, and increase LC3-II levels along with the number of autophagic vacuoles in AD-seeded cells. The effects were lower in case of CBD seeds, and comparable between PSP and AD seeds. An inhibitor of myo-inositol monophosphatase (IMPase) also demonstrated similar effects. Overall, the study suggested that aggregated tau protein is degraded by lithium-induced autophagy, influencing IMPase in a strain-specific manner.
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Doença de Alzheimer/tratamento farmacológico , Doenças dos Gânglios da Base/tratamento farmacológico , Compostos de Lítio/farmacologia , Paralisia Supranuclear Progressiva/tratamento farmacológico , Proteínas tau/química , Proteínas tau/metabolismo , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Autofagia/efeitos dos fármacos , Doenças dos Gânglios da Base/metabolismo , Doenças dos Gânglios da Base/patologia , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Encéfalo/patologia , Células Cultivadas , Humanos , Paralisia Supranuclear Progressiva/metabolismo , Paralisia Supranuclear Progressiva/patologia , Tauopatias/tratamento farmacológico , Tauopatias/metabolismo , Tauopatias/patologiaRESUMO
BACKGROUND: Human tauopathy brain injections into the mouse brain induce the development of tau aggregates, which spread to functionally connected brain regions; however, the features of this neurotoxicity remain unclear. One reason may be short observational periods because previous studies mostly used mutated-tau transgenic mice and needed to complete the study before these mice developed neurofibrillary tangles. OBJECTIVE: To examine whether long-term incubation of Alzheimer's disease (AD) brain in the mouse brain cause functional decline. METHODS: We herein used Tg601 mice, which overexpress wild-type human tau, and non-transgenic littermates (NTg) and injected an insoluble fraction of the AD brain into the unilateral hippocampus. RESULTS: After a long-term (17-19 months) post-injection, mice exhibited learning deficits detected by the Barnes maze test. Aggregated tau pathology in the bilateral hippocampus was more prominent in Tg601 mice than in NTg mice. No significant changes were observed in the number of Neu-N positive cells or astrocytes in the hippocampus, whereas that of Iba-I-positive microglia increased after the AD brain injection. CONCLUSION: These results potentially implicate tau propagation in functional decline and indicate that long-term changes in non-mutated tau mice may reflect human pathological conditions.
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Doença de Alzheimer , Encéfalo/patologia , Aprendizagem em Labirinto/efeitos dos fármacos , Microglia/patologia , Proteínas tau/farmacologia , Animais , Proliferação de Células/efeitos dos fármacos , Modelos Animais de Doenças , Feminino , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Microglia/efeitos dos fármacosRESUMO
In tauopathies, tau forms pathogenic fibrils with distinct conformations (termed "tau strains") and acts as an aggregation "seed" templating the conversion of normal tau into isomorphic fibrils. Previous research showed that the aggregation core of tau fibril covers the C-terminal region (243-406 amino acids (aa)) and differs among the diseases. However, the mechanisms by which distinct fibrous structures are formed and inherited via templated aggregation are still unknown. Here, we sought to identify the key sequences of seed-dependent aggregation. To identify sequences for which deletion reduces tau aggregation, SH-SY5Y cells expressing a series of 10 partial deletion (Del 1-10, covering 244-400 aa) mutants of tau-CTF24 (243-441 aa) were treated with tau seeds prepared from a different tauopathy patient's brain (Alzheimer's disease, progressive supranuclear palsy, and corticobasal degeneration) or recombinant tau, and then seed-dependent tau aggregation was assessed biochemically. We found that the Del 8 mutant lacking 353-368 aa showed significantly decreased aggregation in both cellular and in vitro models. Furthermore, to identify the minimum sequence responsible for tau aggregation, we systematically repeated cellular tau aggregation assays for the delineation of shorter deletion sites and revealed that Asn-368 mutation suppressed tau aggregation triggered by an AD tau seed, but not using other tauopathy seeds. Our study suggested that 353-368 aa is a novel aggregation-responsible sequence other than PHF6 and PHF6*, and within this sequence, the Asn-368 residue plays a role in strain-specific tau aggregation in different tauopathies.
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Doença de Alzheimer , Sequência de Aminoácidos , Agregação Patológica de Proteínas , Deleção de Sequência , Proteínas tau , Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Asparagina/química , Asparagina/genética , Asparagina/metabolismo , Linhagem Celular Tumoral , Humanos , Agregação Patológica de Proteínas/genética , Agregação Patológica de Proteínas/metabolismo , Proteínas tau/química , Proteínas tau/genética , Proteínas tau/metabolismoRESUMO
PURPOSE: Idiopathic normal pressure hydrocephalus (iNPH) and Alzheimer's disease (AD) are geriatric diseases and common causes of dementia. Recently, many studies on the segmentation, disease detection, or classification of MRI using deep learning have been conducted. The aim of this study was to differentiate iNPH and AD using a residual extraction approach in the deep learning method. METHODS: Twenty-three patients with iNPH, 23 patients with AD and 23 healthy controls were included in this study. All patients and volunteers underwent brain MRI with a 3T unit, and we used only whole-brain three-dimensional (3D) T1-weighted images. We designed a fully automated, end-to-end 3D deep learning classifier to differentiate iNPH, AD and control. We evaluated the performance of our model using a leave-one-out cross-validation test. We also evaluated the validity of the result by visualizing important areas in the process of differentiating AD and iNPH on the original input image using the Gradient-weighted Class Activation Mapping (Grad-CAM) technique. RESULTS: Twenty-one out of 23 iNPH cases, 19 out of 23 AD cases and 22 out of 23 controls were correctly diagnosed. The accuracy was 0.90. In the Grad-CAM heat map, brain parenchyma surrounding the lateral ventricle was highlighted in about half of the iNPH cases that were successfully diagnosed. The medial temporal lobe or inferior horn of the lateral ventricle was highlighted in many successfully diagnosed cases of AD. About half of the successful cases showed nonspecific heat maps. CONCLUSION: Residual extraction approach in a deep learning method achieved a high accuracy for the differential diagnosis of iNPH, AD, and healthy controls trained with a small number of cases.