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1.
Alzheimers Dement ; 20(3): 1725-1738, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38087949

RESUMO

BACKGROUND: Models for forecasting individual clinical progression trajectories in early Alzheimer's disease (AD) are needed for optimizing clinical studies and patient monitoring. METHODS: Prediction models were constructed using a clinical trial training cohort (TC; n = 934) via a gradient boosting algorithm and then evaluated in two validation cohorts (VC 1, n = 235; VC 2, n = 421). Model inputs included baseline clinical features (cognitive function assessments, APOE ε4 status, and demographics) and brain magnetic resonance imaging (MRI) measures. RESULTS: The model using clinical features achieved R2 of 0.21 and 0.31 for predicting 2-year cognitive decline in VC 1 and VC 2, respectively. Adding MRI features improved the R2 to 0.29 in VC 1, which employed the same preprocessing pipeline as the TC. Utilizing these model-based predictions for clinical trial enrichment reduced the required sample size by 20% to 49%. DISCUSSION: Our validated prediction models enable baseline prediction of clinical progression trajectories in early AD, benefiting clinical trial enrichment and various applications.


Assuntos
Doença de Alzheimer , Disfunção Cognitiva , Humanos , Doença de Alzheimer/patologia , Imageamento por Ressonância Magnética/métodos , Disfunção Cognitiva/patologia , Encéfalo/patologia , Progressão da Doença
2.
Alzheimers Dement ; 2024 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-38940656

RESUMO

BACKGROUND: This study investigated the potential of phosphorylated plasma Tau217 ratio (pTau217R) and plasma amyloid beta (Aß) 42/Aß40 in predicting brain amyloid levels measured by positron emission tomography (PET) Centiloid (CL) for Alzheimer's disease (AD) staging and screening. METHODS: Quantification of plasma pTau217R and Aß42/Aß40 employed immunoprecipitation-mass spectrometry. CL prediction models were developed on a cohort of 904 cognitively unimpaired, preclinical and early AD subjects and validated on two independent cohorts. RESULTS: Models integrating pTau217R outperformed Aß42/Aß40 alone, predicting amyloid levels up to 89.1 CL. High area under the receiver operating characteristic curve (AUROC) values (89.3% to 94.7%) were observed across a broad CL range (15 to 90). Utilizing pTau217R-based models for low amyloid levels reduced PET scans by 70.5% to 78.6%. DISCUSSION: pTau217R effectively predicts brain amyloid levels, surpassing cerebrospinal fluid Aß42/Aß40's range. Combining it with plasma Aß42/Aß40 enhances sensitivity for low amyloid detection, reducing unnecessary PET scans and expanding clinical utility. HIGHLIGHTS: Phosphorylated plasma Tau217 ratio (pTau217R) effectively predicts amyloid-PET Centiloid (CL) across a broad spectrum. Integrating pTau217R with Aß42/Aß40 extends the CL prediction upper limit to 89.1 CL. Combined model predicts amyloid status with high accuracy, especially in cognitively unimpaired individuals. This model identifies subjects above or below various CL thresholds with high accuracy. pTau217R-based models significantly reduce PET scans by up to 78.6% for screening out individuals with no/low amyloid.

3.
Alzheimers Dement ; 2024 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-39041435

RESUMO

INTRODUCTION: Tau-positron emission tomography (PET) outcome data of patients with Alzheimer's disease (AD) cannot currently be meaningfully compared or combined when different tracers are used due to differences in tracer properties, instrumentation, and methods of analysis. METHODS: Using head-to-head data from five cohorts with tau PET radiotracers designed to target tau deposition in AD, we tested a joint propagation model (JPM) to harmonize quantification (units termed "CenTauR" [CTR]). JPM is a statistical model that simultaneously models the relationships between head-to-head and anchor point data. JPM was compared to a linear regression approach analogous to the one used in the amyloid PET Centiloid scale. RESULTS: A strong linear relationship was observed between CTR values across brain regions. Using the JPM approach, CTR estimates were similar to, but more accurate than, those derived using the linear regression approach. DISCUSSION: Preliminary findings using the JPM support the development and adoption of a universal scale for tau-PET quantification. HIGHLIGHTS: Tested a novel joint propagation model (JPM) to harmonize quantification of tau PET. Units of common scale are termed "CenTauRs". Tested a Centiloid-like linear regression approach. Using five cohorts with head-to-head tau PET, JPM outperformed linearregressionbased approach. Strong linear relationship was observed between CenTauRs values across brain regions.

4.
Diabetologia ; 59(9): 1977-84, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27193916

RESUMO

AIMS/HYPOTHESIS: Type 2 diabetes is characterised by decreased HDL levels, as well as the level of apolipoprotein A-I (apoA-I), the main apolipoprotein of HDLs. Pharmacological elevation of HDL and apoA-I levels is associated with improved glycaemic control in patients with type 2 diabetes. This is partly due to improved glucose uptake in skeletal muscle. METHODS: This study used kinetic modelling to investigate the impact of increasing plasma apoA-I levels on the metabolism of glucose in the db/db mouse model. RESULTS: Treatment of db/db mice with apoA-I for 2 h significantly improved both glucose tolerance (AUC 2574 ± 70 mmol/l × min vs 2927 ± 137 mmol/l × min, for apoA-I and PBS, respectively; p < 0.05) and insulin sensitivity (AUC 388.8 ± 23.8 mmol/l × min vs 194.1 ± 19.6 mmol/l × min, for apoA-I and PBS, respectively; p < 0.001). ApoA-I treatment also increased glucose uptake by skeletal muscle in both an insulin-dependent and insulin-independent manner as evidenced by increased uptake of fludeoxyglucose ([(18)F]FDG) from plasma into gastrocnemius muscle in apoA-I treated mice, both in the absence and presence of insulin. Kinetic modelling revealed an enhanced rate of insulin-mediated glucose phosphorylation (k 3) in apoA-I treated mice (3.5 ± 1.1 × 10(-2) min(-1) vs 2.3 ± 0.7 × 10(-2) min(-1), for apoA-I and PBS, respectively; p < 0.05) and an increased influx constant (3.7 ± 0.6 × 10(-3) ml min(-1) g(-1) vs 2.0 ± 0.3 × 10(-3) ml min(-1) g(-1), for apoA-I and PBS, respectively; p < 0.05). Treatment of L6 rat skeletal muscle cells with apoA-I for 2 h indicated that increased hexokinase activity mediated the increased rate of glucose phosphorylation. CONCLUSIONS/INTERPRETATION: These findings indicate that apoA-I improves glucose disposal in db/db mice by improving insulin sensitivity and enhancing glucose phosphorylation.


Assuntos
Apolipoproteína A-I/uso terapêutico , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/metabolismo , Fluordesoxiglucose F18/análise , Glucose/metabolismo , Músculo Esquelético/metabolismo , Tomografia por Emissão de Pósitrons/métodos , Animais , Glicemia/efeitos dos fármacos , Diabetes Mellitus Tipo 2/sangue , Modelos Animais de Doenças , Resistência à Insulina/fisiologia , Cinética , Masculino , Camundongos , Músculo Esquelético/efeitos dos fármacos , Fosforilação/efeitos dos fármacos
5.
Neuroimage ; 118: 484-93, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26080302

RESUMO

Quantitative measurements in dynamic PET imaging are usually limited by the poor counting statistics particularly in short dynamic frames and by the low spatial resolution of the detection system, resulting in partial volume effects (PVEs). In this work, we present a fast and easy to implement method for the restoration of dynamic PET images that have suffered from both PVE and noise degradation. It is based on a weighted least squares iterative deconvolution approach of the dynamic PET image with spatial and temporal regularization. Using simulated dynamic [(11)C] Raclopride PET data with controlled biological variations in the striata between scans, we showed that the restoration method provides images which exhibit less noise and better contrast between emitting structures than the original images. In addition, the method is able to recover the true time activity curve in the striata region with an error below 3% while it was underestimated by more than 20% without correction. As a result, the method improves the accuracy and reduces the variability of the kinetic parameter estimates calculated from the corrected images. More importantly it increases the accuracy (from less than 66% to more than 95%) of measured biological variations as well as their statistical detectivity.


Assuntos
Algoritmos , Encéfalo/diagnóstico por imagem , Processamento de Imagem Assistida por Computador/métodos , Neuroimagem/métodos , Tomografia por Emissão de Pósitrons/métodos , Animais , Humanos , Método de Monte Carlo , Ratos
6.
Am J Nucl Med Mol Imaging ; 14(1): 1-12, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38500748

RESUMO

Several therapeutics and biomarkers that target Alzheimer's disease (AD) are under development. Our clinical positron emission tomography (PET) research programs are interested in six radiopharmaceuticals to image patients with AD and related dementias, specifically [11C]UCB-J and [18F]SynVesT-1 for synaptic vesicle glycoprotein 2A as a marker of synaptic density, two vesicular acetylcholine transporter PET radiotracers: [18F]FEOBV and [18F]VAT, as well as the transmembrane AMPA receptor regulatory protein (TARP)-γ8 tracer, [18F]JNJ-64511070, and the muscarinic acetylcholine receptor (mAChR) M4 tracer [11C]MK-6884. The goal of this study was to compare all six radiotracers (labeled with tritium or 18F) by measuring their density variability in pathologically diagnosed cases of AD, mild cognitive impairment (MCI) and normal healthy volunteer (NHV) human brains, using thin-section in vitro autoradiography (ARG). Region of interest analysis was used to quantify radioligand binding density and determine whether the radioligands provide a signal-to-noise ratio optimal for showing changes in binding. Our preliminary study confirmed that all six radiotracers show specific binding in MCI and AD. An expected decrease in their respective target density in human AD hippocampus tissues compared to NHV was observed with [3H]UCB-J, [3H]SynVesT-1, [3H]JNJ-64511070, and [3H]MK-6884. This preliminary study will be used to guide human PET imaging of SV2A, TARP-γ8 and the mAChR M4 subtype for imaging in AD and related dementias.

7.
Invest Ophthalmol Vis Sci ; 64(13): 42, 2023 10 03.
Artigo em Inglês | MEDLINE | ID: mdl-37883093

RESUMO

Purpose: To assess the progression in functional and structural measures over a five-year period in patients with retinal dystrophy caused by RLBP1 gene mutation. Methods: This prospective, noninterventional study included patients with biallelic RLBP1 mutations from two clinical sites in Sweden and Canada. Key assessments included ocular examinations, visual functional measures (best-corrected visual acuity [BCVA], contrast sensitivity [CS], dark-adaptation [DA] kinetics up to six hours for two wavelengths [450 and 632 nm], Humphrey visual fields [HVF], full-field flicker electroretinograms), and structural ocular assessments. Results: Of the 45 patients enrolled, 38 completed the full five years of follow-up. At baseline, patients had BCVA ranging from -0.2 to 1.3 logMAR, poor CS, HVF defects, and prominent thinning in central foveal thickness. All patients had extremely prolonged DA rod recovery of approximately six hours at both wavelengths. The test-retest repeatability was high across all anatomic and functional endpoints. Cross-sectionally, poorer VA was associated with older age (right eye, correlation coefficient [CC]: 0.606; left eye, CC: -0.578; P < 0.001) and HVF MD values decreased with age (right eye, CC: -0.672, left eye, CC: -0.654; P < 0.001). However, no major changes in functional or structural measures were noted longitudinally over the five-year period. Conclusions: This natural history study, which is the first study to monitor patients with RLBP1 RD for five years, showed that severely delayed DA sensitivity recovery, a characteristic feature of this disease, was observed in all patients across all age groups (17-69 years), making it a potentially suitable efficacy assessment for gene therapy treatment in this patient population.


Assuntos
Distrofias Retinianas , Retinose Pigmentar , Humanos , Adolescente , Adulto Jovem , Adulto , Pessoa de Meia-Idade , Idoso , Estudos Prospectivos , Campos Visuais , Acuidade Visual , Retinose Pigmentar/diagnóstico , Retinose Pigmentar/genética
8.
Brain ; 132(Pt 12): 3366-79, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19439423

RESUMO

White matter tracts, which play a crucial role in the coordination of information flow between different regions of grey matter, are particularly vulnerable to multiple sclerosis. Many studies have shown that the white matter lesions in multiple sclerosis are associated with focal abnormalities of grey matter, but little is known about the alterations in the coordinated patterns of cortical morphology among regions in the disease. Here, we used cortical thickness measurements from structural magnetic resonance imaging to investigate the relationship between the white matter lesion load and the topological efficiency of structural cortical networks in multiple sclerosis. Network efficiency was defined using a 'small-world' network model that quantifies the effectiveness of information transfer within brain networks. In this study, we first classified patients (n = 330) into six subgroups according to their total white matter lesion loads, and identified structural brain networks for each multiple sclerosis group by thresholding the corresponding inter-regional cortical thickness correlation matrix, followed by a network efficiency analysis with graph theoretical approaches. The structural cortical networks in multiple sclerosis demonstrated efficient small-world architecture regardless of the lesion load, an organization that maximizes the information processing at a relatively low wiring cost. However, we found that the overall small-world network efficiency in multiple sclerosis was significantly disrupted in a manner proportional to the extent of total white matter lesions. Moreover, regional efficiency was also significantly decreased in specific brain regions, including the insula and precentral gyrus as well as regions of prefrontal and temporal association cortices. Finally, we showed that the lesions also altered many cortical thickness correlations in the frontal, temporal and parietal lobes. Our results suggest that the white matter lesions in multiple sclerosis might be associated with aberrant neuronal connectivity among widely distributed brain regions, and provide structural (morphological) evidence for the notion of multiple sclerosis as a disconnection syndrome.


Assuntos
Córtex Cerebral/patologia , Esclerose Múltipla/patologia , Fibras Nervosas Mielinizadas/patologia , Rede Nervosa/patologia , Adulto , Mapeamento Encefálico/métodos , Córtex Cerebral/fisiopatologia , Transtornos Cognitivos/etiologia , Transtornos Cognitivos/patologia , Transtornos Cognitivos/fisiopatologia , Feminino , Humanos , Processamento de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/métodos , Masculino , Processos Mentais/fisiologia , Pessoa de Meia-Idade , Esclerose Múltipla/complicações , Esclerose Múltipla/fisiopatologia , Rede Nervosa/fisiopatologia , Vias Neurais/patologia , Vias Neurais/fisiopatologia , Neurônios/patologia , Índice de Gravidade de Doença , Adulto Jovem
9.
Sci Rep ; 10(1): 9968, 2020 06 19.
Artigo em Inglês | MEDLINE | ID: mdl-32561881

RESUMO

Glioblastoma is a highly malignant, largely therapy-resistant brain tumour. Deep infiltration of brain tissue by neoplastic cells represents the key problem of diffuse glioma. Much current research focuses on the molecular makeup of the visible tumour mass rather than the cellular interactions in the surrounding brain tissue infiltrated by the invasive glioma cells that cause the tumour's ultimately lethal outcome. Diagnostic neuroimaging that enables the direct in vivo observation of the tumour infiltration zone and the local host tissue responses at a preclinical stage are important for the development of more effective glioma treatments. Here, we report an animal model that allows high-contrast imaging of wild-type glioma cells by positron emission tomography (PET) using [18 F]PBR111, a selective radioligand for the mitochondrial 18 kDa Translocator Protein (TSPO), in the Tspo-/- mouse strain (C57BL/6-Tspotm1GuMu(GuwiyangWurra)). The high selectivity of [18 F]PBR111 for the TSPO combined with the exclusive expression of TSPO in glioma cells infiltrating into null-background host tissue free of any TSPO expression, makes it possible, for the first time, to unequivocally and with uniquely high biological contrast identify peri-tumoral glioma cell invasion at preclinical stages in vivo. Comparison of the in vivo imaging signal from wild-type glioma cells in a null background with the signal in a wild-type host tissue, where the tumour induces the expected TSPO expression in the host's glial cells, illustrates the substantial extent of the peritumoral host response to the growing tumour. The syngeneic tumour (TSPO+/+) in null background (TSPO-/-) model is thus well suited to study the interaction of the tumour front with the peri-tumoral tissue, and the experimental evaluation of new therapeutic approaches targeting the invasive behaviour of glioblastoma.

10.
Sci Rep ; 10(1): 16011, 2020 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-32968119

RESUMO

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

11.
Amyotroph Lateral Scler ; 10(5-6): 269-79, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19922113

RESUMO

Our objective was to assess and compare the diagnostic sensitivity of conventional MRI (cMRI), magnetization transfer imaging (MTI), diffusion-weighted imaging (DWI), and proton magnetic resonance spectroscopic imaging ((1)H-MRSI) in patients with amyotrophic lateral sclerosis (ALS) and primary lateral sclerosis (PLS). Thirty-eight ALS patients, nine PLS patients, and 22 healthy controls were enrolled. cMRI, MTI, DWI and (1)H-MRSI were obtained. ALS patients were classified as advanced phase (Ap)-ALS (definite+probable) and early phase (Ep)-ALS (possible+probable-laboratory supported). cMRI was highly sensitive in detecting corticospinal tract (CST) hyperintensities in Ap-ALS (63.4%) and PLS (71.9%), but it was poorly sensitive in Ep-ALS (17.1%). Hyperintensity on proton density-weighted images correlated with ALS severity (p=0.02). CST apparent diffusion coefficient was significantly increased in ALS (p<0.01) and PLS (p=0.02) versus controls. The N-acetylaspartate/creatine ratio was significantly reduced in the motor cortex of patients versus controls (p< or = 0.01 in PLS, p=0.02 in Ap-ALS). The study shows the utility of cMRI for diagnosing ALS. Nevertheless, MRI sensitivity is limited at the early stages of the disease. In these cases, DWI and (1)H-MRSI seem to have the potential to ameliorate the patients' work-up and estimate the nature and extent of the underlying pathological damage.


Assuntos
Esclerose Lateral Amiotrófica , Encéfalo , Imageamento por Ressonância Magnética/métodos , Doença dos Neurônios Motores , Esclerose Lateral Amiotrófica/diagnóstico , Esclerose Lateral Amiotrófica/metabolismo , Esclerose Lateral Amiotrófica/patologia , Encéfalo/anatomia & histologia , Encéfalo/metabolismo , Encéfalo/patologia , Imagem de Difusão por Ressonância Magnética/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Doença dos Neurônios Motores/diagnóstico , Doença dos Neurônios Motores/metabolismo , Doença dos Neurônios Motores/patologia , Sensibilidade e Especificidade
12.
J Alzheimers Dis ; 71(3): 1037-1048, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31476153

RESUMO

At autopsy, individuals with Alzheimer's disease (AD) exhibit heterogeneity in the distribution of neurofibrillary tangles in neocortical and hippocampal regions. Subtypes of AD, defined using an algorithm based on the relative number of tangle counts in these regions, have been proposed-hippocampal sparing (relative sparing of the hippocampus but high cortical load), limbic predominant (high hippocampal load but lower load in association cortices), and typical (balanced neurofibrillary tangles counts in the hippocampus and association cortices) AD-and shown to be associated with distinct antemortem clinical phenotypes. The ability to distinguish these AD subtypes from the more typical tau signature in vivo could have important implications for clinical research. Flortaucipir positron emission tomography (PET) images acquired from 45 amyloid-positive participants, defined clinically as mild cognitive impairment or AD, aged 50-92 years, 56% female, and estimated to be Braak V-VI based on their PET pattern of tau pathology, were studied. By translating the neuropathologic algorithm to flortaucipir PET scans, patterns of tau pathology consistent with autopsy findings, and with a similar prevalence, were identified in vivo. 6/45 (13%) participants were identified as hippocampal sparing and 6/45 (13%) as limbic predominant AD subtypes. Hippocampal sparing participants were significantly younger than those assigned to the other two subtypes. Worse performance on delayed recall was associated with increased hippocampal tau signal, and worse performance on the trail making test B-A was associated with lower values of the hippocampus to cortex ratio. Prospective studies can further validate the flortaucipir SUVR cut-points and the phenotype of the corresponding AD subtypes.


Assuntos
Doença de Alzheimer/classificação , Doença de Alzheimer/diagnóstico por imagem , Carbolinas , Tomografia por Emissão de Pósitrons/métodos , Compostos Radiofarmacêuticos , Tauopatias/classificação , Tauopatias/diagnóstico por imagem , Idoso , Idoso de 80 Anos ou mais , Algoritmos , Doença de Alzheimer/psicologia , Autopsia , Disfunção Cognitiva/diagnóstico por imagem , Feminino , Hipocampo/diagnóstico por imagem , Humanos , Sistema Límbico/diagnóstico por imagem , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Estudos Prospectivos , Tauopatias/psicologia
13.
Alzheimers Dement (N Y) ; 5: 328-337, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31388559

RESUMO

INTRODUCTION: Solanezumab is a humanized monoclonal antibody that preferentially binds to soluble amyloid ß and promotes its clearance from the brain in preclinical studies. The objective of this study was to assess the effect of solanezumab in slowing global and anatomically localized brain atrophy as measured by volumetric magnetic resonance imaging (MRI). METHODS: In the EXPEDITION3 phase 3 trial, participants with mild Alzheimer's disease were randomized to receive intravenous infusions of either 400 mg of solanezumab or placebo every 4 weeks for 76 weeks. Volumetric MRI scans were acquired at baseline and at 80 weeks from 275 MRI facilities using a standardized imaging protocol. A subset of 1462 patients who completed both MRI and 14-item Alzheimer's Disease Assessment Scale-Cognitive Subscale assessments at both time points were selected for analysis. Longitudinal MRI volume changes were analyzed centrally by tensor-based morphometry with a standard FreeSurfer brain parcellation. Prespecified volumetric measures, including whole brain and ventricles, along with anatomically localized regions in the temporal, parietal, and frontal lobes were evaluated in those participants. RESULTS: Group-mean differences in brain atrophy rates were directionally consistent across a number of brain regions but small in magnitude (1.3-6.9% slowing) and not statistically significant when corrected for multiple comparisons. The annualized rates of change of the volumetric measures and the correlation of these changes with cognitive changes in placebo-treated subjects were similar to those reported previously. DISCUSSION: In the EXPEDITION3 trial, solanezumab did not significantly slow down rates of global or anatomically localized brain atrophy. Brain volume changes and their relationship to cognition were consistent with previous reports.

14.
J Neurol ; 255(9): 1378-83, 2008 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-18584233

RESUMO

To assess the value of clinical and MRI variables in predicting short-term brain atrophy accumulation and clinical evolution in a large cohort of patients with RRMS, we studied a cohort of 548 patients, previously enrolled as a placebo arm of a 14-month, double-blind trial of oral glatiramer acetate (GA). A logistic regression model with EDSS progression as the dependent variable was built to assess baseline clinical and MRI variables associated with clinical worsening during follow-up. In 466 patients with complete central brain atrophy assessment, another linear regression model with percentage central brain volume change (PCBVC) as the dependent variable was built to assess baseline clinical and MRI variables associated with atrophy development.A total of 80 patients (15%) had EDSS progression over the follow-up period. Factors independently predicting the probability to have a clinical progression were lower EDSS (OR = 0.78, 95% CI = 0.62-0.97 p = 0.02) and higher T2 LL (OR = 1.022, 95% CI = 1.006-1.038, p = 0.007) at baseline. In the 466 patients with atrophy assessment, PCBVC declined, on average, by -2.0% (SD = 2.8) (p < 0.001) over the follow-up. The multivariate PCBVC analysis revealed that the PCBVC decrease was independently correlated with higher EDSS (p = 0.03) and T2 LL (p = 0.005) at baseline. The squared correlation coefficients of the composite scores made up of EDSS and T2 LL considered together were able to explain only 3 % of the variance in disability progression and only 4 % of the variance of PCBVC.In RRMS patients, clinical and conventional MRI findings at baseline only modestly predict shortterm accumulation of brain atrophy and disability. These data confirm the need to develop clinical and MRI measures more sensitive towards the more disabling aspects of the disease.


Assuntos
Encéfalo/patologia , Avaliação da Deficiência , Imageamento por Ressonância Magnética/métodos , Esclerose Múltipla Recidivante-Remitente/diagnóstico , Adulto , Atrofia , Progressão da Doença , Feminino , Seguimentos , Humanos , Modelos Lineares , Modelos Logísticos , Masculino , Esclerose Múltipla Recidivante-Remitente/patologia , Esclerose Múltipla Recidivante-Remitente/fisiopatologia , Exame Neurológico/métodos , Valor Preditivo dos Testes , Fatores de Tempo
15.
Alzheimers Dement (Amst) ; 10: 322-331, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29780876

RESUMO

INTRODUCTION: Relationship between self- and informant memory concerns and tau aggregation was assessed in adults at risk for Alzheimer's disease (AD). METHODS: Regional mean standardized uptake value ratios were extracted from [18F]flortaucipir positron emission tomography (PET) scans of 82 at-risk adults in the Alzheimer's Disease Neuroimaging Initiative (ADNI) cohort. Associations between self- and informant ECog memory scores and tau aggregation were analyzed on both regional and voxelwise bases. Analyses were completed both on the whole sample and restricted to amyloid-positive individuals only. RESULTS: Memory concerns were associated with tau aggregation. Self-perception was more associated with frontal tau. In contrast, informant scores were more associated with parietal tau. This source-by-region interaction was more prominent in amyloid-positive participants and observed in both regional and voxelwise analyses. DISCUSSION: Quantitative assessment of perceived memory functioning may be useful for screening older adults at risk for Alzheimer's disease. Individuals and their informants may provide complementary information relating to the anatomical distribution of tau.

16.
Alzheimers Dement (Amst) ; 10: 221-231, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29780867

RESUMO

INTRODUCTION: It has been proposed that the signal distribution on tau positron emission tomography (PET) images could be used to define pathologic stages similar to those seen in neuropathology. METHODS: Three topographic staging schemes for tau PET, two sampling the temporal and occipital subregions only and one sampling cortical gray matter across the major brain lobes, were evaluated on flortaucipir F 18 PET images in a test-retest scenario and from Alzheimer's Disease Neuroimaging Initiative 2. RESULTS: All three schemes estimated stages that were significantly associated with amyloid status and when dichotomized to tau positive or negative were 90% to 94% concordant in the populations identified. However, the schemes with fewer regions and simpler decision rules yielded more robust performance in terms of fewer unclassified scans and increased test-retest reproducibility of assigned stage. DISCUSSION: Tau PET staging schemes could be useful tools to concisely index the regional involvement of tau pathology in living subjects. Simpler schemes may be more robust.

17.
Theranostics ; 8(20): 5645-5659, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30555570

RESUMO

Given the strong clinical evidence that copper levels are significantly elevated in a wide spectrum of tumors, copper homeostasis is considered as an emerging target for anticancer drug design. Monitoring copper levels in vivo is therefore of paramount importance when assessing the efficacy of copper-targeting drugs. Herein, we investigated the activity of the copper-targeting compound Dextran-Catechin by developing a [64Cu]CuCl2 PET imaging protocol to monitor its effect on copper homeostasis in tumors. Methods: Protein expression of copper transporter 1 (CTR1) in tissue microarrays representing 90 neuroblastoma patient tumors was assessed by immunohistochemistry. Western blotting analysis was used to study the effect of Dextran-Catechin on the expression of CTR1 in neuroblastoma cell lines and in tumors. A preclinical human neuroblastoma xenograft model was used to study anticancer activity of Dextran-Catechin in vivo and its effect on tumor copper homeostasis. PET imaging with [64Cu]CuCl2 was performed in such preclinical neuroblastoma model to monitor alteration of copper levels in tumors during treatment. Results: CTR1 protein was found to be highly expressed in patient neuroblastoma tumors by immunohistochemistry. Treatment of neuroblastoma cell lines with Dextran-Catechin resulted in decreased levels of glutathione and in downregulation of CTR1 expression, which caused a significant decrease of intracellular copper. No changes in CTR1 expression was observed in normal human astrocytes after Dextran-Catechin treatment. In vivo studies and PET imaging analysis using the neuroblastoma preclinical model revealed elevated [64Cu]CuCl2 retention in the tumor mass. Following treatment with Dextran-Catechin, there was a significant reduction in radioactive uptake, as well as reduced tumor growth. Ex vivo analysis of tumors collected from Dextran-Catechin treated mice confirmed the reduced levels of CTR1. Interestingly, copper levels in blood were not affected by treatment, demonstrating potential tumor specificity of Dextran-Catechin activity. Conclusion: Dextran-Catechin mediates its activity by lowering CTR1 and intracellular copper levels in tumors. This finding further reveals a potential therapeutic strategy for targeting copper-dependent cancers and presents a novel PET imaging method to assess patient response to copper-targeting anticancer treatments.


Assuntos
Tomografia por Emissão de Pósitrons/métodos , Animais , Catequina , Proteínas de Transporte de Cátions , Linhagem Celular Tumoral , Cobre , Transportador de Cobre 1 , Dextranos , Feminino , Homeostase , Humanos , Imuno-Histoquímica , Técnicas In Vitro , Camundongos , Camundongos Endogâmicos BALB C , Imagem Molecular , Neuroblastoma , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Análise Serial de Tecidos
18.
J Neurol Sci ; 259(1-2): 7-15, 2007 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-17397873

RESUMO

A number of recent magnetic resonance imaging studies have challenged the classical view of multiple sclerosis (MS) as a "two-stage" disease where an early inflammatory demyelinating phase with focal macroscopic lesions formed in the white matter (WM) of the central nervous system is followed by a late neurodegenerative phase, which is believed to be a mere consequence of repeated inflammatory insults and irreversible demyelination. These studies have consistently shown the presence of diffuse normal-appearing WM damage, marked gray matter involvement and significant cortical functional reorganization, as well as the occurrence of the neurodegenerative component of MS from the earliest clinical stages of the disease with only a partial relation to MRI markers of inflammatory demyelination. The present review argues that MS can no longer be viewed as a "two-stage" disease, which suggests that the two pathological components are dissociated in time, but rather as a "simultaneous two-component" disease, where the relative contributions of the various pathological processes of the disease to the development of "fixed" disability, their relationship and their evolution over time need to be clarified. This new view of MS should inform the development of future research protocols to define its actual physiopathology and prompt the institution of early treatment which should ideally target not only inflammatory demyelination, but also the neurodegenerative aspects of the disease, as well as promote neuroprotection and enhance reparative mechanisms and adaptive functional reorganization of the cortex.


Assuntos
Doenças Desmielinizantes/etiologia , Esclerose Múltipla/fisiopatologia , Degeneração Neural/etiologia , Doenças Desmielinizantes/patologia , Progressão da Doença , Humanos , Imageamento por Ressonância Magnética/métodos , Esclerose Múltipla/patologia , Degeneração Neural/patologia
19.
Neurology ; 89(21): 2176-2186, 2017 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-29070667

RESUMO

OBJECTIVE: To test the hypothesis that cortical and hippocampal volumes, measured in vivo from volumetric MRI (vMRI) scans, could be used to identify variant subtypes of Alzheimer disease (AD) and to prospectively predict the rate of clinical decline. METHODS: Amyloid-positive participants with AD from the Alzheimer's Disease Neuroimaging Initiative (ADNI) 1 and ADNI2 with baseline MRI scans (n = 229) and 2-year clinical follow-up (n = 100) were included. AD subtypes (hippocampal sparing [HpSpMRI], limbic predominant [LPMRI], typical AD [tADMRI]) were defined according to an algorithm analogous to one recently proposed for tau neuropathology. Relationships between baseline hippocampal volume to cortical volume ratio (HV:CTV) and clinical variables were examined by both continuous regression and categorical models. RESULTS: When participants were divided categorically, the HpSpMRI group showed significantly more AD-like hypometabolism on 18F-fluorodeoxyglucose-PET (p < 0.05) and poorer baseline executive function (p < 0.001). Other baseline clinical measures did not differ across the 3 groups. Participants with HpSpMRI also showed faster subsequent clinical decline than participants with LPMRI on the Alzheimer's Disease Assessment Scale, 13-Item Subscale (ADAS-Cog13), Mini-Mental State Examination (MMSE), and Functional Assessment Questionnaire (all p < 0.05) and tADMRI on the MMSE and Clinical Dementia Rating Sum of Boxes (CDR-SB) (both p < 0.05). Finally, a larger HV:CTV was associated with poorer baseline executive function and a faster slope of decline in CDR-SB, MMSE, and ADAS-Cog13 score (p < 0.05). These associations were driven mostly by the amount of cortical rather than hippocampal atrophy. CONCLUSIONS: AD subtypes with phenotypes consistent with those observed with tau neuropathology can be identified in vivo with vMRI. An increased HV:CTV ratio was predictive of faster clinical decline in participants with AD who were clinically indistinguishable at baseline except for a greater dysexecutive presentation.


Assuntos
Doença de Alzheimer/complicações , Doença de Alzheimer/patologia , Encéfalo/patologia , Transtornos Cognitivos/etiologia , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/líquido cefalorraquidiano , Doença de Alzheimer/diagnóstico por imagem , Peptídeos beta-Amiloides/líquido cefalorraquidiano , Atrofia/classificação , Atrofia/diagnóstico por imagem , Atrofia/etiologia , Encéfalo/efeitos dos fármacos , Transtornos Cognitivos/diagnóstico por imagem , Estudos Transversais , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Estudos Longitudinais , Imageamento por Ressonância Magnética , Masculino , Testes Neuropsicológicos , Fragmentos de Peptídeos/líquido cefalorraquidiano , Análise de Regressão
20.
Lancet Neurol ; 5(10): 841-52, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16987731

RESUMO

Although the diagnosis of multiple sclerosis relies on the demonstration of disease dissemination in space and time, the exclusion of other neurological disorders is also essential. The limited specificity of abnormalities disclosed by MRI may increase the likelihood of diagnosis of multiple sclerosis in patients affected by other disorders. The available criteria for diagnosis of multiple sclerosis have not taken advantage of the potential of MRI to detect features "not suggestive" of multiple sclerosis. Recognition of such features in the work-up of patients suspected of having multiple sclerosis may reduce the likelihood of a false positive diagnosis of the disorder in some, while suggesting the correct alternative diagnosis in other patients. On the basis of this, a workshop of the European MAGNIMS (Magnetic Resonance Network in Multiple Sclerosis) was held to define a series of MRI red flags in the setting of clinically suspected multiple sclerosis that is derived from evidence-based findings and educated guesses. The presence of such red flags should alert clinicians to reconsider the differential diagnosis more extensively. In this review we will report on the conclusions of this international consensus, which should represent a first step beyond the concept of "no better explanation", and inform future diagnostic criteria for multiple sclerosis.


Assuntos
Imageamento por Ressonância Magnética , Esclerose Múltipla/diagnóstico , Encefalopatias/diagnóstico , Encefalopatias/patologia , Isquemia Encefálica/diagnóstico , Isquemia Encefálica/patologia , Transtornos Cerebrovasculares/diagnóstico , Transtornos Cerebrovasculares/patologia , Doenças Desmielinizantes/diagnóstico , Doenças Desmielinizantes/patologia , Humanos , Hipóxia Encefálica/diagnóstico , Hipóxia Encefálica/patologia , Infecções/diagnóstico , Infecções/patologia , Inflamação/diagnóstico , Inflamação/patologia , Esclerose Múltipla/patologia
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