Activation of glycogen synthase kinase-3 beta mediates ß-amyloid induced neuritic damage in Alzheimer's disease.

ß-Amyloid (Aß) plaques in Alzheimer (AD) brains are surrounded by severe dendritic and axonal changes, including local spine loss, axonal swellings and distorted neurite trajectories. Whether and how plaques induce these neuropil abnormalities remains unknown. We tested the hypothesis that oligomeric assemblies of Aß, seen in the periphery of plaques, mediate the neurodegenerative phenotype of AD by triggering activation of the enzyme GSK-3ß, which in turn appears to inhibit a transcriptional program mediated by CREB. We detect increased activity of GSK-3ß after exposure to oligomeric Aß in neurons in culture, in the brain of double transgenic APP/tau mice and in AD brains. Activation of GSK-3ß, even in the absence of Aß, is sufficient to produce a phenocopy of Aß-induced dendritic spine loss in neurons in culture, while pharmacological inhibition of GSK-3ß prevents spine loss and increases expression of CREB-target genes like BDNF. Of note, in transgenic mice GSK-3ß inhibition ameliorated plaque-related neuritic changes and increased CREB-mediated gene expression. Moreover, GSK-3ß inhibition robustly decreased the oligomeric Aß load in the mouse brain. All these findings support the idea that GSK3ß is aberrantly activated by the presence of Aß, and contributes, at least in part, to the neuronal anatomical derangement associated with Aß plaques in AD brains and to Aß pathology itself.

Cardiac sympathetic impairment parallels nigrostriatal degeneration in Probable Dementia with Lewy Bodies.

AIM: Dementia with Lewy Bodies (DLB) must be distinguished from other types of dementia because of important differences in patient management and outcome. Both reduction in cardiac 123I-metaiodobenzilguanidine (MIBG) uptake and decreased 123I-FP-CIT binding in basal ganglia have been described in DLB. The aim of this study was to assess the relationship between cardiac sympathetic activity and nigrostriatal degeneration in patients with probable DLB. METHODS: Twenty-eight patients (15 males; mean age 77 years, range 64-88 years) with clinical international criteria of probable DLB were included in the study. All patients underwent a cardiac MIBG scintigraphy and a FP-CIT SPECT. Global cardiac MIBG uptake was semiquantified by means of heart-to-mediastinum ratio (HMR) (normal >1.56). FP-CIT binding in basal ganglia was calculated and compared with an age-matched control group. The relation between cardiac MIBG uptake and FP-CIT uptake in basal ganglia, and the relationship of these two techniques with distinctive symptoms of DLB, features of past medical history and data from the neuropsychological examination were assessed. RESULTS: Cardiac MIBG uptake was decreased in 23 of 28 patients (HMR=1.32, range 0.95-1.85). The FP-CIT binding in basal ganglia was significantly lower than in control group (2.01±0.5 vs 2.62±0.2, P<0.05). All patients with reduced cardiac HMR showed decreased FP-CIT binding in basal ganglia. There was a positive correlation between the HMR and specific binding ratio of striatum (P<0.01). A high correlation between FP-CIT SPECT and the presence of parkinsonism also was found. No correlation between cardiac MIBG uptake and demographic, clinical or neuropsychological data was found. CONCLUSION: In probable DLB cardiac MIBG uptake and FP-CIT binding in basal ganglia are reduced. The positive correlation between both measures suggests that cardiac sympathetic degeneration and nigrostriatal degeneration parallel similarly in patients with probable DLB.

[(123)I-MIBG myocardial scintigraphy in the diagnosis of Lewy body dementia]. / Gammagrafía miocárdica con I-MIBG en el diagnóstico de la demencia con cuerpos de Lewy.

INTRODUCTION: Lewy body dementia (LBD) is the second most common cause of neurodegenerative dementia after Alzheimer's disease (AD). A cardiac post-ganglionic sympathetic denervation has been described in this condition which can be quantified by MIBG (metaiodobenzylguanidine) myocardial scintigraphy. The aim of our work was to retrospectively evaluate cardiac MIBG uptake (expressed as the heart-to-mediastinum ratio at 4h (HMR) in patients with suspected LBD, and to examine its relationship with clinical and para-clinical data. MATERIAL AND METHODS: A total of 77 patients with clinical suspicion of LBD evaluated at our centre between September 2005 and June 2008 to whom a MIBG myocardial scintigraphy has been performed were retrospectively reviewed. International Consensus Criteria of LBD were applied to divide the sample into probable LBD, possible LBD and non-LBD. HMR values and their relationships with clinical and neuropsychological data were analysed. A subgroup of patients had FP-CIT (fluoropropyl-carbomethoxy-3ß-4-iodophenyltropane) SPECT as a part of the evaluation. RESULTS: Mean HMR values were significantly lower in probable LBD group than in possible LBD and non-LBD groups. Low HMR values were associated only with reduced FP-CIT uptake in the striatum, but not with any clinical or neuropsychological item. CONCLUSIONS: Low MIBG myocardial scintigraphy uptake is a robust measure in LBD, and it is not largely affected by medical conditions, or by the stage of the disease. In LBD reduced MIBG myocardial uptake is associated with nigrostriatal degeneration.

Gammagrafía miocárdica con 123I-MIBG en el diagnóstico de la demencia con cuerpos de Lewy / 123I-MIBG myocardial scintigraphy in the diagnosis of Lewy body dementia

Introducción: La demencia con cuerpos de Lewy (DCLw) es la segunda causa más frecuente de demencia degenerativa tras la demencia tipo Alzheimer (DTA). En esta entidad se ha descrito una denervación simpática cardíaca posganglionar, que puede cuantificarse mediante la gammagrafía miocárdica con MIBG (metayodobencilguanidina). El objetivo de nuestro trabajo fue evaluar retrospectivamente la captación miocárdica de MIBG, expresada cuantitativamente como el índice corazón/mediastino a las 4h (ICM) en pacientes con sospecha clínica de DCLw, y examinar su relación con los datos clínicos y paraclínicos. Pacientes y métodos:Se revisaron retrospectivamente datos de 77 pacientes con sospecha clínica de DCLw evaluados entre septiembre de 2005 y junio de 2008 en nuestro hospital a los que se les había realizado una gammagrafía miocárdica con MIBG. Se aplicaron los criterios internacionales de consenso para dividir la muestra en DCLw probable, DCLw posible y sin DCLw. Se analizaron el ICM en cada grupo y su relación con variables clínicas y neuropsicológicas. A un subgrupo de pacientes se le había realizado además un SPECT con FP-CIT (fluoropropil-carbometoxi-3β-4-yodofeniltropano) como parte de la evaluación. Resultados:Los valores medios de ICM fueron significativamente menores en el grupo de DCLw probable que en los grupos de DCLw posible y sin DCLw. Valores disminuidos de ICM solamente se asociaron a una captación disminuida en el estriado en el FP-CIT SPECT, pero no a ninguna variable clínica ni neuropsicológica. Conclusiones:La captación miocárdica reducida de MIBG es una medida robusta en la DCLw, y no se ve afectada por condiciones médicas o el estadio de la enfermedad. Una disminución en la captación miocárdica de MIBG se asocia a la degeneración nigroestriada en la DCLw (AU)

Introduction: Lewy body dementia (LBD) is the second most common cause of neurodegenerative dementia after Alzheimer's disease (AD). A cardiac post-ganglionic sympathetic denervation has been described in this condition which can be quantified by MIBG (metaiodobenzylguanidine) myocardial scintigraphy. The aim of our work was to retrospectively evaluate cardiac MIBG uptake (expressed as the heart-to-mediastinum ratio at 4h (HMR) in patients with suspected LBD, and to examine its relationship with clinical and para-clinical data. Material and methods: A total of 77 patients with clinical suspicion of LBD evaluated at our centre between September 2005 and June 2008 to whom a MIBG myocardial scintigraphy has been performed were retrospectively reviewed. International Consensus Criteria of LBD were applied to divide the sample into probable LBD, possible LBD and non-LBD. HMR values and their relationships with clinical and neuropsychological data were analysed. A subgroup of patients had FP-CIT (fluoropropyl-carbomethoxy-3β-4-iodophenyltropane) SPECT as a part of the evaluation.Results: Mean HMR values were significantly lower in probable LBD group than in possible LBD and non-LBD groups. Low HMR values were associated only with reduced FP-CIT uptake in the striatum, but not with any clinical or neuropsychological item.Conclusions: Low MIBG myocardial scintigraphy uptake is a robust measure in LBD, and it is not largely affected by medical conditions, or by the stage of the disease. In LBD reduced MIBG myocardial uptake is associated with nigrostriatal degeneration (AU)

Triflusal reduces dense-core plaque load, associated axonal alterations and inflammatory changes, and rescues cognition in a transgenic mouse model of Alzheimer's disease.

Inflammation has been associated with the two classic lesions in the Alzheimer's (AD) brain, amyloid deposits and neurofibrillary tangles. Recent data suggest that Triflusal, a compound with potent anti-inflammatory effects in the central nervous system in vivo, might delay the conversion from amnestic mild cognitive impairment to a fully established clinical picture of dementia. In the present study, we investigated the effect of Triflusal on brain Abeta accumulation, neuroinflammation, axonal curvature and cognition in an AD transgenic mouse model (Tg2576). Triflusal treatment did not alter the total brain Abeta accumulation but significantly reduced dense-cored plaque load and associated glial cell proliferation, proinflammatory cytokine levels and abnormal axonal curvature, and rescued cognitive deficits in Tg2576 mice. Behavioral benefit was found to involve increased expression of c-fos and BDNF, two of the genes regulated by CREB, as part of the signal transduction cascade underlying the molecular basis of long-term potentiation. These results add preclinical evidence of a potentially beneficial effect of Triflusal in AD.

A novel GSK-3beta inhibitor reduces Alzheimer's pathology and rescues neuronal loss in vivo.

Amyloid deposits, neurofibrillary tangles, and neuronal cell death in selectively vulnerable brain regions are the chief hallmarks in Alzheimer's (AD) brains. Glycogen synthase kinase-3 (GSK-3) is one of the key kinases required for AD-type abnormal hyperphosphorylation of tau, which is believed to be a critical event in neurofibrillary tangle formation. GSK-3 has also been recently implicated in amyloid precursor protein (APP) processing/Abeta production, apoptotic cell death, and learning and memory. Thus, GSK-3 inhibition represents a very attractive drug target in AD and other neurodegenerative disorders. To investigate whether GSK-3 inhibition can reduce amyloid and tau pathologies, neuronal cell death and memory deficits in vivo, double transgenic mice coexpressing human mutant APP and tau were treated with a novel non-ATP competitive GSK-3beta inhibitor, NP12. Treatment with this thiadiazolidinone compound resulted in lower levels of tau phosphorylation, decreased amyloid deposition and plaque-associated astrocytic proliferation, protection of neurons in the entorhinal cortex and CA1 hippocampal subfield against cell death, and prevention of memory deficits in this transgenic mouse model. These results show that this novel GSK-3 inhibitor has a dual impact on amyloid and tau alterations and, perhaps even more important, on neuronal survival in vivo further suggesting that GSK-3 is a relevant therapeutic target in AD.

Whole genome analysis in a consanguineous family with early onset Alzheimer's disease.

Early-onset Alzheimer's disease (EOAD) is a clinically and genetically heterogeneous condition in which the typical features appear significantly earlier in life (before 65 years). Mutations in three genes (PSEN1, PSEN2, and APP) have been identified in autosomal dominant forms of EOAD. However, in about 50% of Mendelian cases and in most of the sporadic EOAD patients, no mutations have been found. We present clinical characteristics of an Israeli family comprising two affected siblings with EOAD born to neurologically healthy parents who were first cousins (both parents died after 90 years old). Sequence analysis of PSEN1, PSEN2, APP, TAU, PGRN, and PRNP failed to reveal any mutations in the affected siblings. Because the disease in this family is consistent with an autosomal recessive mode of inheritance we identified all homozygous regions identical by descent (IBD) in both siblings, by high-density SNP genotyping. We provide here the first catalog of autozygosity in EOAD and suggest that the regions identified are excellent candidate loci for a recessive genetic lesion causing this disease.

Current advances on different kinases involved in tau phosphorylation, and implications in Alzheimer's disease and tauopathies.

Hyperphosphorylation and accumulation of tau in neurons (and glial cells) is one the main pathologic hallmarks in Alzheimer's disease (AD) and other tauopathies, including Pick's disease (PiD), progressive supranuclear palsy, corticobasal degeneration, argyrophilic grain disease and familial frontotemporal dementia and parkinsonism linked to chromosome 17 due to mutations in the tau gene (FTDP-17-tau). Hyperphosphorylation of tau is regulated by several kinases that phosphorylate specific sites of tau in vitro. GSK-3-immunoprecipitated sarcosyl-insoluble fractions in AD have the capacity to phosphorylate recombinant tau. In addition, GSK-3 phosphorylated at Ser9, that inactivates GSK-3, is found in the majority of neurons with neurofibrillary tangles and dystrophic neurites of senile plaques in AD, and in Pick bodies and other phospho-tau-containing neurons and glial cells in other tauopathies. Increased expression of active kinases, including stress-activated kinase, c-Jun N-terminal kinase (SAPK/JNK) and kinase p38 has been found in brain homogenates in all the tauopathies. Strong active SAPK/JNK and p38 immunoreactivity has been observed restricted to neurons and glial cells containing hyperphosphorylated tau, as well as in dystrophic neurites of senile plaques in AD. Moreover, SAPK/JNK- and p38-immunoprecipitated sub-cellular fractions enriched in abnormal hyperphosphorylated tau have the capacity to phosphorylate recombinant tau and c-Jun and ATF-2 which are specific substrates of SAPK/JNK and p38 in AD and PiD. Interestingly, increased expression of phosphorylated (active) SAPK/JNK and p38 and hyperphosphorylated tau containing neurites have been observed around betaA4 amyloid deposits in the brain of transgenic mice (Tg 2576) carrying the double APP Swedish mutation. These findings suggest that betaA4 amyloid has the capacity to trigger the activation of stress kinases which, in turn, phosphorylate tau in neurites surrounding amyloid deposits. Complementary findings have been reported from the autopsy of two AD patients who participated in an amyloid-beta immunization trial and died during the course of immunization-induced encephalitis. The neuropathological examination of the brain showed massive focal reduction of amyloid plaques but not of neurofibrillary degeneration. Activation of SAPK/JNK and p38 were reduced together with decreased tau hyperphosphorylation of aberrant neurites in association with decreased amyloid plaques in both Tg2576 mice and human brains. These findings support the amyloid cascade hypothesis of tau phosphorylation mediated by stress kinases in dystrophic neurites of senile plaques but not that of neurofibrillary tangles and neuropil threads in AD.

Expression of stress-activated kinases c-Jun N-terminal kinase (SAPK/JNK-P) and p38 kinase (p38-P), and tau hyperphosphorylation in neurites surrounding betaA plaques in APP Tg2576 mice.

Hyperphosphorylated tau in neurites surrounding beta-amyloid (betaA) deposits, as revealed with phospho-specific anti-tau antibodies, are found in amyloid precursor protein (APP) Tg2576 mice. Because betaA is a source of oxidative stress and may be toxic for cultured cells, the present study examines the expression of phosphorylated (active) stress-activated kinase c-Jun N-terminal kinase (SAPK/JNK-P) and p38 kinase (p38-P), which have the capacity to phosphorylate tau at specific sites, and their specific substrates c-Jun and ATF-2, which are involved in cell death and survival in several paradigms, in Tg2576 mice. The study was planned to shed light about the involvement of these kinases in tau phosphorylation in cell processes surrounding amyloid plaques, as well as in the possible phosphorylation (activation) of c-Jun and activating transcription factor-2 (ATF-2) in relation to betaA deposition. Moderate increase in the expression of phosphorylated mitogen-activated protein kinase and extracelullar signal-regulated kinase (MAPK/ERK-P) occurs in a few amyloid plaques. However, strong expression of SAPK/JNK-P and p38-P is found in the majority of, if not all, amyloid plaques, as seen in serial consecutive sections stained for betaA and stress kinases. Moreover, confocal microscopy reveals colocalization of phospho-tau and SAPK/JNK-P, and phospho-tau and p38-P in many dystrophic neurites surrounding amyloid plaques. Increased expression levels of nonbound tau, SAPK/JNK-P and p38-P are corroborated by Western blots of total cortical homogenate supernatants in Tg2576 mice when compared with age-matched controls. No increase in phosphorylated c-JunSer63 (c-Jun-P) and ATF-2Thr71 (ATF-2-P) is found in association with betaA deposits. In addition, no expression of active (cleaved) caspase-3 (17 kDa) has been found in transgenic mice. Taken together, these observations provide a link between betaA-induced oxidative stress, activation of stress kinases SAPK/JNK and p38, and tau hyperphosphorylation in neurites surrounding amyloid plaques, but activation of these kinases is not associated with accumulation of c-Jun-P and ATF-2-P, nor with activation of active caspase-3 in the vicinity of betaA deposits.

Nitric oxide in the cerebral cortex of amyloid-precursor protein (SW) Tg2576 transgenic mice.

Changes in the amyloid-peptide (Abeta), neuronal and inducible nitric oxide (NO)synthase (nNOS, iNOS), nitrotyrosine, glial fibrillary acidic protein, and lectin from Lycopersicon esculentum (tomato) were investigated in the cerebral cortex of transgenic mice (Tg2576) to amyloid precursor protein (APP), by immunohistochemistry (bright light, confocal, and electron microscopy). The expression of nitrergic proteins and synthesis of nitric oxide were analyzed by immunoblotting and NOS activity assays, respectively. The cerebral cortex of these transgenic mice showed an age-dependent progressive increase in intraneuronal aggregates of Abeta-peptide and extracellular formation of senile plaques surrounded by numerous microglial and reactive astrocytes. Basically, no changes to nNOS reactivity or expression were found in the cortical mantle of either wild or transgenic mice. This reactivity in wild mice corresponded to numerous large type I and small type II neurons. The transgenic mice showed swollen, twisted, and hypertrophic preterminal and terminal processes of type I neurons, and an increase of the type II neurons. The calcium-dependent NOS enzymatic activity was higher in wild than in the transgenic mice. The iNOS reactivity, expression and calcium-independent enzymatic activity increased in transgenic mice with respect to wild mice, and were related to cortical neurons and microglial cells. The progressive elevation of NO production resulted in a specific pattern of protein nitration in reactive astrocytes. The ultrastructural study carried out in the cortical mantle showed that the neurons contained intracellular aggregates of Abeta-peptide associated with the endoplasmic reticulum, mitochondria, and Golgi apparatus. The endothelial vascular cells also contained Abeta-peptide deposits. This transgenic model might contribute to understand the role of the nitrergic system in the biological changes related to neuropathological progression of Alzheimer's disease.

Abnormal alpha-synuclein interactions with Rab proteins in alpha-synuclein A30P transgenic mice.

Mutation A30P in the alpha-synuclein gene is a cause of familial Parkinson disease. Transgenic mice expressing wild mouse and mutant human A30P alpha-synuclein, Tg5093 mice (Tg), show a progressive motor disorder characterized by tremor, rigidity, and dystonia, accompanied by accumulation of alpha-synuclein in the soma and neurites and by a conspicuous gliosis beginning in the hippocampal formation at the age of 7 to 8 months and spreading throughout the CNS. Impaired short-term changes in synaptic strength have also been documented in hippocampal slices from Tg mice. Alpha-synuclein aggregates of approximately 34 and 70 kDa, in addition to the band of 17 kDa, corresponding to the molecular weight of alpha-synuclein, were recovered in the PBS-soluble fraction of brain homogenates from Tg mice but not from brain samples from age-matched wildtype littermates. MPTP-treated Tg and wildtype mice produced alpha-synuclein aggregates in the PBS-, deoxycholate-, and SDS-soluble fractions. Aggregates of alpha-synuclein, although with different molecular weights, were also observed in rotenone-treated Tg and wildtype mice. Pull-down studies with members of the Rab protein family have shown that alpha-synuclein from Tg mice interacts with Rab3a, Rab5, and Rab8. This binding is not due to the amount of alpha-synuclein (levels of which are higher in Tg mice) and it is not dependent on the amount of Rab protein used in the assay. Rather, alpha-synuclein interactions with Rab proteins are due to mutant alpha-synuclein as demonstrated in Rab pull-down assays with recombinant of wildtype and mutant A30P human alpha-synuclein. Since Rab3a, Rab5, and Rab8 are important proteins involved in synaptic vesicle trafficking and exocytosis at the synapse, vesicle endocytosis, and trans-Golgi transport, respectively, it can be suggested that these functions are impaired in Tg mice. This rationale is consistent with previous data showing that short-term hippocampal synaptic plasticity is altered and that alpha-synuclein accumulates in the cytoplasm of neurons in Tg mice.

Serum insulin-like growth factor I regulates brain amyloid-beta levels.

Levels of insulin-like growth factor I (IGF-I), a neuroprotective hormone, decrease in serum during aging, whereas amyloid-beta (Abeta), which is involved in the pathogenesis of Alzheimer disease, accumulates in the brain. High brain Abeta levels are found at an early age in mutant mice with low circulating IGF-I, and Abeta burden can be reduced in aging rats by increasing serum IGF-I. This opposing relationship between serum IGF-I and brain Abeta levels reflects the ability of IGF-I to induce clearance of brain Abeta, probably by enhancing transport of Abeta carrier proteins such as albumin and transthyretin into the brain. This effect is antagonized by tumor necrosis factor-alpha, a pro-inflammatory cytokine putatively involved in dementia and aging. Because IGF-I treatment of mice overexpressing mutant amyloid markedly reduces their brain Abeta burden, we consider that circulating IGF-I is a physiological regulator of brain amyloid levels with therapeutic potential.

MRI measures of entorhinal cortex vs hippocampus in preclinical AD.

BACKGROUND: MRI measures of the entorhinal cortex and the hippocampus have been used to predict which nondemented individuals with memory problems will progress to meet criteria for AD on follow-up, but their relative accuracy remains controversial. OBJECTIVES: To compare MRI measures of the entorhinal cortex and the hippocampus for predicting who will develop AD. METHODS: MRI volumes of the entorhinal cortex and the hippocampus were obtained in 137 individuals comprising four groups: 1) individuals with normal cognition both at baseline and after 3 years of follow-up (n = 28), 2) subjects with memory difficulty but not dementia both at baseline and after 3 years of follow-up (n = 73), 3) subjects with memory difficulty at baseline who were diagnosed with probable AD within 3 years of follow-up (n = 21), and 4) patients with mild AD at baseline (n = 16). RESULTS: Measures of both the entorhinal cortex and the hippocampus were different for each of the pairwise comparisons between the groups (p < 0.001) and were correlated with tests of memory (p < 0.01). However, the volume of the entorhinal cortex differentiated the subjects from those destined to develop dementia with considerable accuracy (84%), whereas the measure of the hippocampus did not. CONCLUSION: These findings are consistent with neuropathologic data showing substantial involvement of the entorhinal cortex in the preclinical phase of AD and suggest that, as the disease spreads, atrophic change develops within the hippocampus, which is measurable on MRI.

[Present and future of neurology in Spain]. / Presente y futuro de la neurología española.

This is a document prepared by the Spanish Society of Neurology (SEN), which was given to the President of Spain (Mr. José María Aznar) last September with the main aim of examining the current situation of Neurology in our country. It analyses the present and future of Neurology in clinical assistance, teaching and research. To prepare this document the criteria of patients' associations has been considered, including the Declaration of Madrid which has been subscribed by thirty of these associations. In spite of its relevant development in the previous decades, the current situation of Neurology in Spain is far from the ideal. To reach the recommendable menber of 3 or 4 neurologists per 100,000 inhabitants it is necessary to duplicate the present number of neurologists which has been estimated around 2/100,000; this situation is especially urgent in some Autonomous Communities. The most important problems in neurological assistance are: inadequate follow-up of the chronic outpatients, low numbers of neurological beds and of duties of Neurology, as well as of neurological case of patients with urgent neurological disorders. It is also necessary to increase the number of professors of Neurology to adequately cover pregraduate teaching; again there are important differences in teaching positions among Autonomous Communities. Neurology residence should be prolonged from 4 to 5 years. Finally, it is necessary to support the appearance of superespecialised units and to promote a coordinated research with other close specialities including basic neuroscience.

The human DIMINUTO/DWARF1 homolog seladin-1 confers resistance to Alzheimer's disease-associated neurodegeneration and oxidative stress.

In Alzheimer's disease (AD) brains, selected populations of neurons degenerate heavily, whereas others are frequently spared from degeneration. To address the cellular basis for this selective vulnerability of neurons in distinct brain regions, we compared gene expression between the severely affected inferior temporal lobes and the mostly unaffected fronto-parietal cortices by using an mRNA differential display. We identified seladin-1, a novel gene, which was downregulated in large pyramidal neurons in vulnerable regions in AD but not control brains. Seladin-1 is a human homolog of the DIMINUTO/DWARF1 gene described in plants and Caenorhabditis elegans. Its sequence shares similarities with flavin-adenin-dinucleotide (FAD)-dependent oxidoreductases. In human control brain, seladin-1 was highly expressed in almost all neurons. In PC12 cell clones that were selected for resistance against AD-associated amyloid-beta peptide (Abeta)-induced toxicity, both mRNA and protein levels of seladin-1 were approximately threefold higher as compared with the non-resistant wild-type cells. Functional expression of seladin-1 in human neuroglioma H4 cells resulted in the inhibition of caspase 3 activation after either Abeta-mediated toxicity or oxidative stress and protected the cells from apoptotic cell death. In apoptotic cells, however, endogenous seladin-1 was cleaved to a 40 kDa derivative in a caspase-dependent manner. These results establish that seladin-1 is an important factor for the protection of cells against Abeta toxicity and oxidative stress, and they suggest that seladin-1 may be involved in the regulation of cell survival and death. Decreased expression of seladin-1 in specific neurons may be a cause for selective vulnerability in AD.

Endocytic pathway abnormalities precede amyloid beta deposition in sporadic Alzheimer's disease and Down syndrome: differential effects of APOE genotype and presenilin mutations.

Endocytosis is critical to the function and fate of molecules important to Alzheimer's disease (AD) etiology, including the beta protein precursor (betaPP), amyloid beta (Abeta) peptide, and apolipoprotein E (ApoE). Early endosomes, a major site of Abeta peptide generation, are markedly enlarged within neurons in the Alzheimer brain, suggesting altered endocytic pathway (EP) activity. Here, we show that neuronal EP activation is a specific and very early response in AD. To evaluate endocytic activation, we used markers of internalization (rab5, rabaptin 5) and recycling (rab4), and found that enlargement of rab5-positive early endosomes in the AD brain was associated with elevated levels of rab4 immunoreactive protein and translocation of rabaptin 5 to endosomes, implying that both endocytic uptake and recycling are activated. These abnormalities were evident in pyramidal neurons of the neocortex at preclinical stages of disease when Alzheimer-like neuropathology, such as Abeta deposition, was restricted to the entorhinal region. In Down syndrome, early endosomes were significantly enlarged in some pyramidal neurons as early as 28 weeks of gestation, decades before classical AD neuropathology develops. Markers of EP activity were only minimally influenced by normal aging and other neurodegenerative diseases studied. Inheritance of the epsilon4 allele of APOE, however, accentuated early endosome enlargement at preclinical stages of AD. By contrast, endosomes were normal in size at advanced stages of familial AD caused by mutations of presenilin 1 or 2, indicating that altered endocytosis is not a consequence of Abeta deposition. These results identify EP activation as the earliest known intraneuronal change to occur in sporadic AD, the most common form of AD. Given the important role of the EP in Abeta peptide generation and ApoE function, early endosomal abnormalities provide a mechanistic link between EP alterations, genetic susceptibility factors, and Abeta generation and suggest differences that may be involved in Abeta generation and beta amyloidogenesis in subtypes of AD.

Description of microcolumnar ensembles in association cortex and their disruption in Alzheimer and Lewy body dementias.

The cortex of the brain is organized into clear horizontal layers, laminae, which subserve much of the connectional anatomy of the brain. We hypothesize that there is also a vertical anatomical organization that might subserve local interactions of neuronal functional units, in accord with longstanding electrophysiological observations. We develop and apply a general quantitative method, inspired by analogous methods in condensed matter physics, to examine the anatomical organization of the cortex in human brain. We find, in addition to obvious laminae, anatomical evidence for tightly packed microcolumnar ensembles containing approximately 11 neurons, with a periodicity of about 80 microm. We examine the structural integrity of this new architectural feature in two common dementing illnesses, Alzheimer disease and dementia with Lewy bodies. In Alzheimer disease, there is a dramatic, nearly complete loss of microcolumnar ensemble organization. The relative degree of loss of microcolumnar ensembles is directly proportional to the number of neurofibrillary tangles, but not related to the amount of amyloid-beta deposition. In dementia with Lewy bodies, a similar disruption of microcolumnar ensemble architecture occurs despite minimal neuronal loss. These observations show that quantitative analysis of complex cortical architecture can be applied to analyze the anatomical basis of brain disorders.

Use of structural magnetic resonance imaging to predict who will get Alzheimer's disease.

We used magnetic resonance imaging (MRI) measurements to determine whether persons in the prodromal phase of Alzheimer's disease (AD) could be accurately identified before they developed clinically diagnosed dementia. Normal subjects (n = 24) and those with mild memory difficulty (n = 79) received an MRI scan at baseline and were then followed annually for 3 years to determine which individuals subsequently met clinical criteria for AD. Patients with mild AD at baseline were also evaluated (n = 16). Nineteen of the 79 subjects with mild memory difficulty "converted" to a diagnosis of probable AD after 3 years of follow-up. Baseline MRI measures of the entorhinal cortex, the banks of the superior temporal sulcus, and the anterior cingulate were most useful in discriminating the status of the subjects on follow-up examination. The accuracy of discrimination was related to the clinical similarity between groups. One hundred percent (100%) of normal subjects and patients with mild AD could be discriminated from one another based on these MRI measures. When the normals were compared with the individuals with memory impairments who ultimately developed AD (the converters), the accuracy of discrimination was 93%, based on the MRI measures at baseline (sensitivity = 0.95; specificity = 0.90). The discrimination of the normal subjects and the individuals with mild memory problems who did not progress to the point where they met clinical criteria for probable AD over the 3 years of follow-up (the "questionables") was 85% and the discrimination of the questionables and converters was 75%. The apolipoprotein E genotype did not improve the accuracy of discrimination. The specific regions selected for each of these discriminations provides information concerning the hierarchical fashion in which the pathology of AD may affect the brain during its prodromal phase.

Donepezil therapy in clinical practice: a randomized crossover study.

OBJECTIVE: To determine the efficacy of donepezil hydrochloride for the treatment of Alzheimer disease in patients drawn from clinical practice. DESIGN: Two-center, randomized, placebo-controlled, double-masked crossover study. SETTING: Memory disorders units at Massachusetts General and Brigham and Women's hospitals, Boston. PATIENTS: Sixty individuals (30 men and 30 women; mean +/- SD age, 75.0+/-9.5 years) with probable Alzheimer disease and scores of 20 or less on the information-memory-concentration subscale of the Blessed Dementia Scale. INTERVENTIONS: Placebo wash-in, followed in randomized sequence by (1) donepezil hydrochloride therapy, 5 mg/d, for 6 weeks, followed by placebo washout for 6 weeks and (2) placebo treatment for 6 weeks. PRIMARY OUTCOME MEASURE: Change in Alzheimer's Disease Assessment Scale cognitive subscale scores from the beginning to the end of the two 6-week treatment periods. RESULTS: Among patients completing treatment and testing for both periods (n = 48), subscale scores improved (mean +/- SEM) 2.17+/-0.98 points (95% confidence interval, 0.20-4.10 points) during donepezil therapy relative to placebo therapy (P = .04). Scores returned toward baseline within 3 weeks of drug washout. There was no associated change in caregiver-rated global impression (donepezil vs placebo: proportion improved, 0.24 vs 0.22; proportion worsened, 0.27 vs 0.35; P = .34) or on specific tests of explicit memory or verbal fluency. Contrary to studies with tacrine, the presence of the apolipoprotein E epsilon4 allele did not predict donepezil treatment failure. Most common adverse events related to donepezil therapy were nausea (5 patients), diarrhea (3 patients), and agitation (3 patients). Serious events possibly related to drug use were seizure, pancreatitis, and syncope (1 patient each). CONCLUSION: This independent confirmation of data from phase 3 trials suggests that donepezil therapy modestly improves cognition in patients with Alzheimer disease who are encountered in clinical practice.

Clinical and neuropathological correlates of dementia with Lewy bodies.

Dementia with Lewy bodies (DLB) is characterized pathologically by widespread Lewy body (LB) neuronal inclusions in the brain, but the contribution of LBs to the clinical syndrome of dementia and parkinsonism is unclear. In a clinical-pathological study of 25 cases with DLB, we examined the regional neuroanatomical distribution of Lewy-related pathology using alpha-synuclein immunostaining to evaluate the relationship between LBs, neuronal loss, Alzheimer-type changes, and the clinical phenotype. Compared to traditional ubiquitin immunostaining, alpha-synuclein immunohistochemistry was more specific and slightly more sensitive, staining about 5% more intracytoplasmic structures. There was a consistent pattern of vulnerability to LB formation across subcortical, paralimbic, limbic, and neocortical structures, which was independent of concomitant Alzheimer-type changes. There were no significant differences in regional LB densities among patients with or without cognitive fluctuations, visual hallucinations, delusions, recurrent falls or parkinsonism. Duration of disease correlated weakly with LB density. There was no neuronal loss in superior temporal sulcus or entorhinal cortex in pure DLB cases compared to nondemented controls. Thus, DLB is characterized by a specific neuroanatomical vulnerability to LB pathology, distinct from AD pathology, with a complicated relationship to clinical symptoms.