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1.
Bioorg Med Chem Lett ; 25(21): 4812-4819, 2015 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-26195137

RESUMO

The IC50 of a beta-secretase (BACE-1) lead compound was improved ∼200-fold from 11 µM to 55 nM through the addition of a single methyl group. Computational chemistry, small molecule NMR, and protein crystallography capabilities were used to compare the solution conformation of the ligand under varying pH conditions to its conformation when bound in the active site. Chemical modification then explored available binding pockets adjacent to the ligand. A strategically placed methyl group not only maintained the required pKa of the piperidine nitrogen and filled a small hydrophobic pocket, but more importantly, stabilized the conformation best suited for optimized binding to the receptor.


Assuntos
Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Ácido Aspártico Endopeptidases/antagonistas & inibidores , Hidantoínas/química , Hidantoínas/farmacologia , Secretases da Proteína Precursora do Amiloide/metabolismo , Ácido Aspártico Endopeptidases/metabolismo , Cristalografia por Raios X , Relação Dose-Resposta a Droga , Humanos , Hidantoínas/síntese química , Metilação , Modelos Moleculares , Estrutura Molecular , Relação Estrutura-Atividade
2.
Alzheimer Dis Assoc Disord ; 27(3): 233-43, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23023094

RESUMO

Previous studies that have examined the potential for plasma markers to serve as biomarkers for Alzheimer disease (AD) have studied single analytes and focused on the amyloid-ß and τ isoforms and have failed to yield conclusive results. In this study, we performed a multivariate analysis of 146 plasma analytes (the Human DiscoveryMAP v 1.0 from Rules-Based Medicine) in 527 subjects with AD, mild cognitive impairment (MCI), or cognitively normal elderly subjects from the Alzheimer's Disease Neuroimaging Initiative database. We identified 4 different proteomic signatures, each using 5 to 14 analytes, that differentiate AD from control patients with sensitivity and specificity ranging from 74% to 85%. Five analytes were common to all 4 signatures: apolipoprotein A-II, apolipoprotein E, serum glutamic oxaloacetic transaminase, α-1-microglobulin, and brain natriuretic peptide. None of the signatures adequately predicted progression from MCI to AD over a 12- and 24-month period. A new panel of analytes, optimized to predict MCI to AD conversion, was able to provide 55% to 60% predictive accuracy. These data suggest that a simple panel of plasma analytes may provide an adjunctive tool to differentiate AD from controls, may provide mechanistic insights to the etiology of AD, but cannot adequately predict MCI to AD conversion.


Assuntos
Doença de Alzheimer/sangue , Disfunção Cognitiva/sangue , Proteômica/métodos , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/classificação , Doença de Alzheimer/diagnóstico , Biomarcadores/sangue , Disfunção Cognitiva/classificação , Disfunção Cognitiva/diagnóstico , Progressão da Doença , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes
3.
J Neurosci Res ; 90(12): 2247-58, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22987781

RESUMO

Reduction in cerebrospinal fluid (CSF) amyloid ß42 (Aß42) and elevation in total tau and phospho-thr181 tau consistently differentiate between Alzheimer's disease (AD) and age-matched control subjects. In contrast, CSF ß-site APP-cleaving enzyme activity (BACE1) and soluble amyloid precursor proteins α and ß (sAPPα and sAPPß) are without consistent patterns in AD subjects. Plasma sampling is much easier, with fewer side effects, and is readily applied in primary care centers, so we have developed and validated novel plasma BACE activity, sAPPß, and sAPPα assays and investigated their ability to distinguish AD from age-matched controls. Plasma BACE activity assay was sensitive and specific, with signal being immunodepleted with a specific BACE1 antibody and inhibited with a BACE1-specific inhibitor. Plasma sAPPß and sAPPα assays were specific, with signal diluting linearly, immunodepleted with specific antibodies, and at background levels in APP knockout mice. In rhesus monkeys, BACE1 but not γ-secretase inhibitor led to significant lowering of plasma sAPPß with concurrent elevation of plasma sAPPα. AD subjects showed a significant increase in plasma BACE1 activity, sAPPß, sAPPα, and Aß42 (P < 0.001) compared with age-matched controls. In conclusion, plasma BACE activity and sAPP endpoints provide novel investigative biomarkers for AD diagnosis and potential pharmacodynamic biomarkers for secretase inhibitor studies.


Assuntos
Doença de Alzheimer/sangue , Secretases da Proteína Precursora do Amiloide/sangue , Peptídeos beta-Amiloides/sangue , Precursor de Proteína beta-Amiloide/sangue , Ácido Aspártico Endopeptidases/sangue , Fragmentos de Peptídeos/sangue , Idoso , Doença de Alzheimer/diagnóstico , Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Secretases da Proteína Precursora do Amiloide/deficiência , Animais , Ácido Aspártico Endopeptidases/antagonistas & inibidores , Ácido Aspártico Endopeptidases/deficiência , Biomarcadores , Feminino , Humanos , Imuno-Histoquímica/métodos , Macaca mulatta , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Pessoa de Meia-Idade , Sensibilidade e Especificidade , Sulfonamidas/farmacologia
4.
J Neurosci ; 30(19): 6743-50, 2010 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-20463236

RESUMO

The accumulation of amyloid beta (Abeta) in Alzheimer's disease is caused by an imbalance of production and clearance, which leads to increased soluble Abeta species and extracellular plaque formation in the brain. Multiple Abeta-lowering therapies are currently in development: an important goal is to characterize the molecular mechanisms of action and effects on physiological processing of Abeta, as well as other amyloid precursor protein (APP) metabolites, in models which approximate human Abeta physiology. To this end, we report the translation of the human in vivo stable-isotope-labeling kinetics (SILK) method to a rhesus monkey cisterna magna ported (CMP) nonhuman primate model, and use the model to test the mechanisms of action of a gamma-secretase inhibitor (GSI). A major concern of inhibiting the enzymes which produce Abeta (beta- and gamma-secretase) is that precursors of Abeta may accumulate and cause a rapid increase in Abeta production when enzyme inhibition discontinues. In this study, the GSI MK-0752 was administered to conscious CMP rhesus monkeys in conjunction with in vivo stable-isotope-labeling, and dose-dependently reduced newly generated CNS Abeta. In contrast to systemic Abeta metabolism, CNS Abeta production was not increased after the GSI was cleared. These results indicate that most of the CNS APP was metabolized to products other than Abeta, including C-terminal truncated forms of Abeta: 1-14, 1-15 and 1-16; this demonstrates an alternative degradation pathway for CNS amyloid precursor protein during gamma-secretase inhibition.


Assuntos
Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Secretases da Proteína Precursora do Amiloide/metabolismo , Peptídeos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Encéfalo/metabolismo , Medula Espinal/metabolismo , Peptídeos beta-Amiloides/sangue , Peptídeos beta-Amiloides/líquido cefalorraquidiano , Precursor de Proteína beta-Amiloide/sangue , Precursor de Proteína beta-Amiloide/líquido cefalorraquidiano , Animais , Encéfalo/enzimologia , Radioisótopos de Carbono , Estudos Cross-Over , Humanos , Marcação por Isótopo/métodos , Cinética , Macaca mulatta , Masculino , Modelos Animais , Especificidade da Espécie , Medula Espinal/enzimologia , Fatores de Tempo
5.
J Neurosci Res ; 89(6): 822-32, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21433051

RESUMO

Amyloid-ß peptide (Aß) is generated by sequential cleavage of the amyloid precursor protein (APP) by ß-site amyloid precursor protein cleaving enzyme 1 (ß-secretase, or BACE1) and γ-secretase. Several reports demonstrate increased BACE1 enzymatic activity in brain and cerebrospinal fluid (CSF) from Alzheimer's disease (AD) subjects, suggesting that an increase in BACE1-mediated cleavage of APP drives amyloid pathophysiology in AD. BACE1 cleavage of APP leads to the generation of a secreted N-terminal fragment of APP (sAPPß). To relate BACE1 activity better to endogenous APP processing in AD and control brains, we have directly measured brain sAPPß levels using a novel APP ß-site specific enzyme-linked immunosorbent assay. We demonstrate a significant reduction in brain cortical sAPPß levels in AD compared with control subjects. In the same brain samples, BACE1 activity was unchanged, full-length APP and sAPPα levels were significantly reduced, and Aß peptides were significantly elevated. In conclusion, a reduction in cortical brain sAPPß together with unchanged BACE1 activity suggests that this is due to reduced full-length APP substrate in late-stage AD subjects. These results highlight the need for multiparameter analysis of the amyloidogenic process to understand better AD pathophysiology in early vs. late-stage AD.


Assuntos
Doença de Alzheimer/patologia , Precursor de Proteína beta-Amiloide/metabolismo , Córtex Cerebral/metabolismo , Idoso , Idoso de 80 Anos ou mais , Secretases da Proteína Precursora do Amiloide/metabolismo , Peptídeos beta-Amiloides/metabolismo , Ácido Aspártico Endopeptidases/metabolismo , Ensaio de Imunoadsorção Enzimática/métodos , Feminino , Humanos , Masculino , Fragmentos de Peptídeos/metabolismo , Fosforilação , Treonina/metabolismo , Proteínas tau/metabolismo
6.
Ann Neurol ; 68(2): 220-30, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20641005

RESUMO

OBJECTIVE: Recent evidence suggests that high molecular weight soluble oligomeric Abeta (oAbeta) assemblies (also known as Abeta-derived diffusible ligands, or ADDLs) may represent a primary neurotoxic basis for cognitive failure in Alzheimer disease (AD). To date, most in vivo studies of oAbeta/ADDLs have involved injection of assemblies purified from the cerebrospinal fluid of human subjects with AD or from the conditioned media of Abeta-secreting cells into experimental animals. We sought to study the bioactivities of endogenously formed oAbeta/ADDLs generated in situ from the physiological processing of human amyloid precursor protein (APP) and presenitin1 (PS1) transgenes. METHODS: We produced and histologically characterized single transgenic mice overexpressing APP(E693Q) or APP(E693Q) X PS1DeltaE9 bigenic mice. APP(E693Q) mice were studied in the Morris water maze (MWM) task at 6 and 12 months of age. Following the second MWM evaluation, mice were sacrificed, and brains were assayed for Abetatotal, Abeta40, Abeta42, and oAbeta/ADDLs by enzyme-linked immunosorbent assay (ELISA) and were also histologically examined. Based on results from the oAbeta/ADDL ELISA, we assigned individual APP(E693Q) mice to either an undetectable oAbeta/ADDLs group or a readily detectable oAbeta/ADDLs group. A days to criterion (DTC) analysis was used to determine delays in acquisition of the MWM task. RESULTS: Both single transgenic and bigenic mice developed intraneuronal accumulation of APP/Abeta, although only APP(E693Q) X PS1Delta9 bigenic mice developed amyloid plaques. The APP(E693Q) mice did not develop amyloid plaques at any age studied, up to 30 months. APP(E693Q) mice were tested for spatial learning and memory, and only 12-month-old APP(E693Q) mice with readily detectable oAbeta/ADDLs displayed a significant delay in acquisition of the MWM task when compared to nontransgenic littermates. INTERPRETATION: These data suggest that cerebral oAbeta/ADDL assemblies generated in brain in situ from human APP transgenes may be associated with cognitive impairment. We propose that a DTC analysis may be a sensitive method for assessing the cognitive impact in mice of endogenously generated oligomeric human Abeta assemblies. ANN NEUROL 2010.


Assuntos
Doença de Alzheimer/etiologia , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/toxicidade , Comportamento Animal/efeitos dos fármacos , Fragmentos de Peptídeos/toxicidade , Doença de Alzheimer/genética , Peptídeos beta-Amiloides/química , Peptídeos beta-Amiloides/genética , Precursor de Proteína beta-Amiloide/química , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/toxicidade , Animais , Comportamento Animal/fisiologia , Química Encefálica/genética , Modelos Animais de Doenças , Feminino , Humanos , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Aprendizagem em Labirinto/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/genética , Processamento de Proteína Pós-Traducional/genética
7.
Acta Neuropathol ; 121(5): 597-609, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21311900

RESUMO

The close correlation between abnormally low pre-mortem cerebrospinal fluid (CSF) concentrations of amyloid-ß1-42 (Aß(1-42)) and plaque burden measured by amyloid imaging as well as between pathologically increased levels of CSF tau and the extent of neurodegeneration measured by MRI has led to growing interest in using these biomarkers to predict the presence of AD plaque and tangle pathology. A challenge for the widespread use of these CSF biomarkers is the high variability in the assays used to measure these analytes which has been ascribed to multiple pre-analytical and analytical test performance factors. To address this challenge, we conducted a seven-center inter-laboratory standardization study for CSF total tau (t-tau), phospho-tau (p-tau(181)) and Aß(1-42) as part of the Alzheimer's Disease Neuroimaging Initiative (ADNI). Aliquots prepared from five CSF pools assembled from multiple elderly controls (n = 3) and AD patients (n = 2) were the primary test samples analyzed in each of three analytical runs by the participating laboratories using a common batch of research use only immunoassay reagents (INNO-BIA AlzBio3, xMAP technology, from Innogenetics) on the Luminex analytical platform. To account for the combined effects on overall precision of CSF samples (fixed effect), different laboratories and analytical runs (random effects), these data were analyzed by mixed-effects modeling with the following results: within center %CV 95% CI values (mean) of 4.0-6.0% (5.3%) for CSF Aß(1-42); 6.4-6.8% (6.7%) for t-tau and 5.5-18.0% (10.8%) for p-tau(181) and inter-center %CV 95% CI range of 15.9-19.8% (17.9%) for Aß(1-42), 9.6-15.2% (13.1%) for t-tau and 11.3-18.2% (14.6%) for p-tau(181). Long-term experience by the ADNI biomarker core laboratory replicated this degree of within-center precision. Diagnostic threshold CSF concentrations for Aß(1-42) and for the ratio t-tau/Aß(1-42) were determined in an ADNI independent, autopsy-confirmed AD cohort from whom ante-mortem CSF was obtained, and a clinically defined group of cognitively normal controls (NCs) provides statistically significant separation of those who progressed from MCI to AD in the ADNI study. These data suggest that interrogation of ante-mortem CSF in cognitively impaired individuals to determine levels of t-tau, p-tau(181) and Aß(1-42), together with MRI and amyloid imaging biomarkers, could replace autopsy confirmation of AD plaque and tangle pathology as the "gold standard" for the diagnosis of definite AD in the near future.


Assuntos
Doença de Alzheimer/líquido cefalorraquidiano , Doença de Alzheimer/diagnóstico , Peptídeos beta-Amiloides/líquido cefalorraquidiano , Fragmentos de Peptídeos/líquido cefalorraquidiano , Proteínas tau/líquido cefalorraquidiano , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/mortalidade , Biomarcadores/líquido cefalorraquidiano , Disfunção Cognitiva/líquido cefalorraquidiano , Disfunção Cognitiva/diagnóstico , Disfunção Cognitiva/mortalidade , Humanos , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Prognóstico , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
8.
Bull Math Biol ; 73(1): 230-47, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20411345

RESUMO

Aggregation of the small peptide amyloid beta (Aß) into oligomers and fibrils in the brain is believed to be a precursor to Alzheimer's disease. Aß is produced via multiple proteolytic cleavages of amyloid precursor protein (APP), mediated by the enzymes ß- and γ-secretase. In this study, we examine the temporal dynamics of soluble (unaggregated) Aß in the plasma and cerebral-spinal fluid (CSF) of rhesus monkeys treated with different oral doses of a γ-secretase inhibitor. A dose-dependent reduction of Aß concentration was observed within hours of drug ingestion, for all doses tested. Aß concentration in the CSF returned to its predrug level over the monitoring period. In contrast, Aß concentration in the plasma exhibited an unexpected overshoot to as high as 200% of the predrug concentration, and this overshoot persisted as late as 72 hours post-drug ingestion. To account for these observations, we proposed and analyzed a minimal physiological model for Aß dynamics that could fit the data. Our analysis suggests that the overshoot arises from the attenuation of an Aß clearance mechanism, possibly due to the inhibitor. Our model predicts that the efficacy of Aß clearance recovers to its basal (pretreatment) value with a characteristic time of >48 hours, matching the time-scale of the overshoot. These results point to the need for a more detailed investigation of soluble Aß clearance mechanisms and their interaction with Aß-reducing drugs.


Assuntos
Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Peptídeos beta-Amiloides/metabolismo , Modelos Biológicos , Doença de Alzheimer/etiologia , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/sangue , Peptídeos beta-Amiloides/líquido cefalorraquidiano , Animais , Inibidores Enzimáticos/administração & dosagem , Inibidores Enzimáticos/farmacocinética , Inibidores Enzimáticos/farmacologia , Humanos , Macaca mulatta , Conceitos Matemáticos , Modelos Animais , Solubilidade
9.
J Proteome Res ; 9(3): 1392-401, 2010 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-20095649

RESUMO

The rapid identification of protein biomarkers in biofluids is important to drug discovery and development. Here, we describe a general proteomic approach for the discovery and identification of proteins that exhibit a statistically significant difference in abundance in cerebrospinal fluid (CSF) before and after pharmacological intervention. This approach, differential mass spectrometry (dMS), is based on the analysis of full scan mass spectrometry data. The dMS workflow does not require complex mixing and pooling strategies, or isotope labeling techniques. Accordingly, clinical samples can be analyzed individually, allowing the use of longitudinal designs and within-subject data analysis in which each subject acts as its own control. As a proof of concept, we performed multifactorial dMS analyses on CSF samples drawn at 6 time points from n = 6 cisterna magna ported (CMP) rhesus monkeys treated with 2 potent gamma secretase inhibitors (GSI) or comparable vehicle in a 3-way crossover study that included a total of 108 individual CSF samples. Using analysis of variance and statistical filtering on the aligned and normalized LC-MS data sets, we detected 26 features that were significantly altered in CSF by drug treatment. Of those 26 features, which belong to 10 distinct isotopic distributions, 20 were identified by MS/MS as 7 peptides from CD99, a cell surface protein. Six features from the remaining 3 isotopic distributions were not identified. A subsequent analysis showed that the relative abundance of these 26 features showed the same temporal profile as the ELISA measured levels of CSF A beta 42 peptide, a known pharmacodynamic marker for gamma-secretase inhibition. These data demonstrate that dMS is a promising approach for the discovery, quantification, and identification of candidate target engagement biomarkers in CSF.


Assuntos
Proteínas do Líquido Cefalorraquidiano/análise , Espectrometria de Massas/métodos , Proteômica/métodos , Algoritmos , Sequência de Aminoácidos , Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Secretases da Proteína Precursora do Amiloide/metabolismo , Peptídeos beta-Amiloides/análise , Peptídeos beta-Amiloides/metabolismo , Análise de Variância , Animais , Área Sob a Curva , Biomarcadores/líquido cefalorraquidiano , Proteínas do Líquido Cefalorraquidiano/metabolismo , Macaca mulatta , Dados de Sequência Molecular , Oligopeptídeos/farmacocinética , Fragmentos de Peptídeos/análise , Fragmentos de Peptídeos/metabolismo
10.
Bioorg Med Chem Lett ; 20(6): 1885-9, 2010 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-20176482

RESUMO

The optimization of tertiary carbinamine derived inhibitors of BACE1 from its discovery as an unstable lead to low nanomolar cell active compounds is described. Five-membered heterocycles are reported as stable and potency enhancing linkers. In the course of this work, we have discovered a clear trend where the activity of inhibitors at a given assay pH is dependent on pK(a) of the amino group that interacts directly with the catalytic aspartates. The potency of compounds as inhibitors of Alphabeta production in a cell culture assay correlated much better with BACE1 enzyme potency measured at pH 7.5 than at pH 4.5.


Assuntos
Aminas/metabolismo , Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Ácido Aspártico Endopeptidases/antagonistas & inibidores , Ácido Aspártico/metabolismo , Inibidores Enzimáticos/farmacologia , Catálise , Humanos , Modelos Moleculares , Relação Estrutura-Atividade
11.
Neuron ; 45(6): 861-72, 2005 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-15797548

RESUMO

Lithium inhibits inositol monophosphatase at therapeutically effective concentrations, and it has been hypothesized that depletion of brain inositol levels is an important chemical alteration for lithium's therapeutic efficacy in bipolar disorder. We have employed adult rat cortical slices as a model to investigate the gene regulatory consequences of inositol depletion effected by lithium using cytidine diphosphoryl-diacylglycerol as a functionally relevant biochemical marker to define treatment conditions. Genes coding for the neuropeptide hormone pituitary adenylate cyclase activating polypeptide (PACAP) and the enzyme that processes PACAP's precursor to the mature form, peptidylglycine alpha-amidating monooxygenase, were upregulated by inositol depletion. Previous work has shown that PACAP can increase tyrosine hydroxylase (TH) activity and dopamine release, and we found that the gene for GTP cyclohydrolase, which effectively regulates TH through synthesis of tetrahydrobiopterin, was also upregulated by inositol depletion. We propose that modulation of brain PACAP signaling might represent a new opportunity in the treatment of bipolar disorder.


Assuntos
Antimaníacos/farmacologia , Biopterinas/análogos & derivados , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Inositol/metabolismo , Cloreto de Lítio/farmacologia , Animais , Biomarcadores/metabolismo , Biopterinas/metabolismo , Transtorno Bipolar/metabolismo , Córtex Cerebral/fisiopatologia , Diglicerídeos de Citidina Difosfato/metabolismo , Regulação para Baixo/efeitos dos fármacos , Regulação para Baixo/fisiologia , GTP Cicloidrolase/genética , GTP Cicloidrolase/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica/fisiologia , Masculino , Oxigenases de Função Mista/metabolismo , Complexos Multienzimáticos/metabolismo , Fatores de Crescimento Neural/biossíntese , Neuropeptídeos/biossíntese , Neurotransmissores/biossíntese , Análise de Sequência com Séries de Oligonucleotídeos , Técnicas de Cultura de Órgãos , Polipeptídeo Hipofisário Ativador de Adenilato Ciclase , Ratos , Ratos Sprague-Dawley , Tirosina 3-Mono-Oxigenase/biossíntese , Regulação para Cima/genética
12.
J Pharmacol Exp Ther ; 328(1): 131-40, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-18854490

RESUMO

beta-Site amyloid precursor protein (APP)-cleaving enzyme (BACE) 1 cleavage of amyloid precursor protein is an essential step in the generation of the potentially neurotoxic and amyloidogenic A beta 42 peptides in Alzheimer's disease. Although previous mouse studies have shown brain A beta lowering after BACE1 inhibition, extension of such studies to nonhuman primates or man was precluded by poor potency, brain penetration, and pharmacokinetics of available inhibitors. In this study, a novel tertiary carbinamine BACE1 inhibitor, tertiary carbinamine (TC)-1, was assessed in a unique cisterna magna ported rhesus monkey model, where the temporal dynamics of A beta in cerebrospinal fluid (CSF) and plasma could be evaluated. TC-1, a potent inhibitor (IC(50) approximately 0.4 nM), has excellent passive membrane permeability, low susceptibility to P-glycoprotein transport, and lowered brain A beta levels in a mouse model. Intravenous infusion of TC-1 led to a significant but transient lowering of CSF and plasma A beta levels in conscious rhesus monkeys because it underwent CYP3A4-mediated metabolism. Oral codosing of TC-1 with ritonavir, a potent CYP3A4 inhibitor, twice daily over 3.5 days in rhesus monkeys led to sustained plasma TC-1 exposure and a significant and sustained reduction in CSF sAPP beta, A beta 40, A beta 42, and plasma A beta 40 levels. CSF A beta 42 lowering showed an EC(50) of approximately 20 nM with respect to the CSF [TC-1] levels, demonstrating excellent concordance with its potency in a cell-based assay. These results demonstrate the first in vivo proof of concept of CSF A beta lowering after oral administration of a BACE1 inhibitor in a nonhuman primate.


Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/genética , Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Precursor de Proteína beta-Amiloide/líquido cefalorraquidiano , Precursor de Proteína beta-Amiloide/antagonistas & inibidores , Animais , Ácido Aspártico Endopeptidases/antagonistas & inibidores , Inibidores Enzimáticos/administração & dosagem , Inibidores Enzimáticos/farmacologia , Humanos , Infusões Intravenosas , Macaca mulatta , Camundongos , Camundongos Transgênicos , Transfecção
13.
J Healthc Eng ; 2019: 4794637, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31183030

RESUMO

A variety of cognitive assessment tools are used to determine the functional status of the brain before and after injury in athletes. Questionnaires, neuropsychological tests, and electroencephalographic (EEG) measures have been recently used to directly assess brain function on and near the playing field. However, exercise can affect cognitive performance and EEG measures of cortical activity. To date, little empirical evidence exists on the effects of acute exercise on these measures of neurological function. We therefore quantified athlete performance on a standardized battery of concussion assessment tools and EEG measurements immediately before and after acute exercise to simulate conditions of athletic competition. Heart rate and arterial oxygen levels were collected before and after the exercise challenge consisting of a 1-mile run. Together these data, from a gender-balanced cohort of collegiate athletes, demonstrated that moderate to hard levels of acute exercise improved performance on the King-Devick test (K-D test) and Standardized Assessment of Concussion (SAC) component of the Sport Concussion Assessment Tool (SCAT3). Gender played an important role in these effects, and performance was most affected by exercise in female athletes. EEG activity in the theta band (4-8 Hz) was decreased during periods of quiet resting with eyes open or eyes closed. Additionally, exercise produced a slowing of the EEG during the K-D test and a shift to higher frequencies during the balance assessment of the SCAT3. Together, these data indicate that exercise alone can influence outcome measures of cognitive assessment tools used to assess brain function in athletes. Finally, care must be taken to acquire postinjury measurements during a comparable physiologic state to that in which baseline assessment data were measured, and further research is needed into the factors influencing outcome measures of these tests.


Assuntos
Concussão Encefálica , Eletroencefalografia , Exercício Físico/fisiologia , Atletas , Concussão Encefálica/diagnóstico , Concussão Encefálica/fisiopatologia , Diagnóstico por Computador , Feminino , Frequência Cardíaca/fisiologia , Humanos , Masculino , Testes Neuropsicológicos , Processamento de Sinais Assistido por Computador
14.
J Pharmacol Exp Ther ; 324(3): 957-69, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18156464

RESUMO

beta-Secretase (BACE) cleavage of amyloid precursor protein (APP) is one of the first steps in the production of amyloid beta peptide Abeta42, the putative neurotoxic species in Alzheimer's disease. Recent studies have shown that BACE1 knockdown leads to hypomyelination, putatively caused by a decline in neuregulin (NRG)-1 processing. In this study, we have tested a potent cell-permeable BACE1 inhibitor (IC(50) approximately 30 nM) by administering it directly into the lateral ventricles of mice, expressing human wild-type (WT)-APP, to determine the consequences of BACE1 inhibition on brain APP and NRG-1 processing. BACE1 inhibition, in vivo, led to a significant dose- and time-dependent lowering of brain Abeta40 and Abeta42. BACE1 inhibition also led to a robust brain secreted (s)APPbeta lowering that was accompanied by an increase in brain sAPPalpha levels. Although an increase in full-length NRG-1 levels was evident in 15-day-old BACE1 homozygous knockout (KO) (-/-) mice, in agreement with previous studies, this effect was also observed in 15-day-old heterozygous (+/-) mice, but it was not evident in 30-day-old and 2-year-old BACE1 KO (-/-) mice. Thus, BACE1 knockdown led to a transient decrease in NRG-1 processing in mice. Pharmacological inhibition of BACE1 in adult mice, which led to significant Abeta lowering, was without any significant effect on brain NRG-1 processing. Taken together, these results suggest that BACE1 is the major beta-site cleavage enzyme for APP and that its inhibition can lower brain Abeta and redirect APP processing via the potentially nonamyloidogenic alpha-secretase pathway, without significantly altering NRG-1 processing.


Assuntos
Secretases da Proteína Precursora do Amiloide/biossíntese , Peptídeos beta-Amiloides/antagonistas & inibidores , Precursor de Proteína beta-Amiloide/biossíntese , Ácido Aspártico Endopeptidases/antagonistas & inibidores , Encéfalo/metabolismo , Neuregulina-1/metabolismo , Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Secretases da Proteína Precursora do Amiloide/genética , Secretases da Proteína Precursora do Amiloide/metabolismo , Secretases da Proteína Precursora do Amiloide/fisiologia , Peptídeos beta-Amiloides/genética , Peptídeos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/genética , Animais , Ácido Aspártico Endopeptidases/genética , Ácido Aspártico Endopeptidases/metabolismo , Encéfalo/efeitos dos fármacos , Regulação para Baixo/efeitos dos fármacos , Regulação para Baixo/fisiologia , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Neuregulina-1/genética , Inibidores de Proteases/farmacologia , Regulação para Cima/efeitos dos fármacos , Regulação para Cima/fisiologia
15.
17.
J Med Chem ; 49(25): 7270-3, 2006 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-17149856

RESUMO

We describe the discovery and optimization of tertiary carbinamine derived inhibitors of the enzyme beta-secretase (BACE-1). These novel non-transition-state-derived ligands incorporate a single primary amine to interact with the catalytic aspartates of the target enzyme. Optimization of this series provided inhibitors with intrinsic and functional potency comparable to evolved transition state isostere derived inhibitors of BACE-1.


Assuntos
Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Secretases da Proteína Precursora do Amiloide/química , Compostos de Anilina/síntese química , Oxidiazóis/síntese química , Compostos de Anilina/química , Cristalografia por Raios X , Modelos Moleculares , Oxidiazóis/química
18.
Med Biol Eng Comput ; 53(9): 843-55, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25863694

RESUMO

We have developed a novel approach to elucidate several discriminating EEG features of Alzheimer's disease. The approach is based on the use of a variety of continuous wavelet transforms, pairwise statistical tests with multiple comparison correction, and several decision tree algorithms, in order to choose the most prominent EEG features from a single sensor. A pilot study was conducted to record EEG signals from Alzheimer's disease (AD) patients and healthy age-matched control (CTL) subjects using a single dry electrode device during several eyes-closed (EC) and eyes-open (EO) resting conditions. We computed the power spectrum distribution properties and wavelet and sample entropy of the wavelet coefficients time series at scale ranges approximately corresponding to the major brain frequency bands. A predictive index was developed using the results from statistical tests and decision tree algorithms to identify the most reliable significant features of the AD patients when compared to healthy controls. The three most dominant features were identified as larger absolute mean power and larger standard deviation of the wavelet scales corresponding to 4-8 Hz (θ) during EO and lower wavelet entropy of the wavelet scales corresponding to 8-12 Hz (α) during EC, respectively. The fourth reliable set of distinguishing features of AD patients was lower relative power of the wavelet scales corresponding to 12-30 Hz (ß) followed by lower skewness of the wavelet scales corresponding to 2-4 Hz (upper δ), both during EO. In general, the results indicate slowing and lower complexity of EEG signal in AD patients using a very easy-to-use and convenient single dry electrode device.


Assuntos
Doença de Alzheimer/diagnóstico , Eletroencefalografia , Análise de Ondaletas , Idoso , Idoso de 80 Anos ou mais , Encéfalo/patologia , Árvores de Decisões , Feminino , Análise de Fourier , Humanos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Processamento de Sinais Assistido por Computador
19.
J Med Chem ; 47(26): 6447-50, 2004 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-15588077

RESUMO

We describe the development of cell-permeable beta-secretase inhibitors that demonstratively inhibit the production of the secreted amino terminal fragment of an artificial amyloid precursor protein in cell culture. In addition to potent inhibition in a cell-based assay (IC50 < 100 nM), these inhibitors display impressive selectivity against other biologically relevant aspartyl proteases.


Assuntos
Ácido Aspártico Endopeptidases/antagonistas & inibidores , Etilaminas/síntese química , Sulfonamidas/síntese química , Secretases da Proteína Precursora do Amiloide , Ácido Aspártico Endopeptidases/química , Sítios de Ligação , Linhagem Celular , Permeabilidade da Membrana Celular , Cristalografia por Raios X , Desenho de Fármacos , Etilaminas/química , Etilaminas/farmacologia , Humanos , Modelos Moleculares , Relação Estrutura-Atividade , Sulfonamidas/química , Sulfonamidas/farmacologia
20.
Ann Biomed Eng ; 41(6): 1243-57, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23536113

RESUMO

Alzheimer's disease (AD) is associated with deficits in a number of cognitive processes and executive functions. Moreover, abnormalities in the electroencephalogram (EEG) power spectrum develop with the progression of AD. These features have been traditionally characterized with montage recordings and conventional spectral analysis during resting eyes-closed and resting eyes-open (EO) conditions. In this study, we introduce a single lead dry electrode EEG device which was employed on AD and control subjects during resting and activated battery of cognitive and sensory tasks such as Paced Auditory Serial Addition Test (PASAT) and auditory stimulations. EEG signals were recorded over the left prefrontal cortex (Fp1) from each subject. EEG signals were decomposed into sub-bands approximately corresponding to the major brain frequency bands using several different discrete wavelet transforms and developed statistical features for each band. Decision tree algorithms along with univariate and multivariate statistical analysis were used to identify the most predictive features across resting and active states, separately and collectively. During resting state recordings, we found that the AD patients exhibited elevated D4 (~4-8 Hz) mean power in EO state as their most distinctive feature. During the active states, however, the majority of AD patients exhibited larger minimum D3 (~8-12 Hz) values during auditory stimulation (18 Hz) combined with increased kurtosis of D5 (~2-4 Hz) during PASAT with 2 s interval. When analyzed using EEG recording data across all tasks, the most predictive AD patient features were a combination of the first two feature sets. However, the dominant discriminating feature for the majority of AD patients were still the same features as the active state analysis. The results from this small sample size pilot study indicate that although EEG recordings during resting conditions are able to differentiate AD from control subjects, EEG activity recorded during active engagement in cognitive and auditory tasks provide important distinct features, some of which may be among the most predictive discriminating features.


Assuntos
Doença de Alzheimer/diagnóstico , Eletroencefalografia/métodos , Idoso , Idoso de 80 Anos ou mais , Algoritmos , Doença de Alzheimer/fisiopatologia , Doença de Alzheimer/psicologia , Árvores de Decisões , Eletrodos , Eletroencefalografia/instrumentação , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Análise de Ondaletas
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