Influence of magnetic field strength and image registration strategy on voxel-based morphometry in a study of Alzheimer's disease.

Multi-centre data repositories like the Alzheimer's Disease Neuroimaging Initiative (ADNI) offer a unique research platform, but pose questions concerning comparability of results when using a range of imaging protocols and data processing algorithms. The variability is mainly due to the non-quantitative character of the widely used structural T1-weighted magnetic resonance (MR) images. Although the stability of the main effect of Alzheimer's disease (AD) on brain structure across platforms and field strength has been addressed in previous studies using multi-site MR images, there are only sparse empirically-based recommendations for processing and analysis of pooled multi-centre structural MR data acquired at different magnetic field strengths (MFS). Aiming to minimise potential systematic bias when using ADNI data we investigate the specific contributions of spatial registration strategies and the impact of MFS on voxel-based morphometry in AD. We perform a whole-brain analysis within the framework of Statistical Parametric Mapping, testing for main effects of various diffeomorphic spatial registration strategies, of MFS and their interaction with disease status. Beyond the confirmation of medial temporal lobe volume loss in AD, we detect a significant impact of spatial registration strategy on estimation of AD related atrophy. Additionally, we report a significant effect of MFS on the assessment of brain anatomy (i) in the cerebellum, (ii) the precentral gyrus and (iii) the thalamus bilaterally, showing no interaction with the disease status. We provide empirical evidence in support of pooling data in multi-centre VBM studies irrespective of disease status or MFS.

DANOS CAUSADOS POR LARVAS E ADULTOS DE DIABROTICA SPECIOSA (COLEOPTERA: CHRYSOMELIDAE) EM MILHO

A espécie Diabrotica speciosa (Germar, 1824) é, tradicionalmente, na fase adulta, uma praga polífaga, embora apresente certa preferência por folhas do feijoeiro e soja. Entretanto, nos últimos anos, a fase de larva deste crisomelídeo adquiriu o status de praga, à semelhança de outras espécies do mesmo gênero nos EUA, causando consideráveis danos ao sistema radicular do milho. O objetivo da pesquisa foi avaliar os danos causados por diferentes níveis populacionais de larvas de D. speciosa às raízes de milho, e, pelos adultos às folhas de milho, soja, feijoeiro e arroz. Desde as menores densidades populacionais de larvas, houve redução significativa no peso seco das raízes do milho, peso seco da parte aérea e na altura das plantas em relação à testemunha. Constatou-se que o nível de controle está aquém de 40 larvas por planta. Os adultos tiveram significativa preferência por folhas do feijoeiro e soja, sendo o milho e o arroz menos consumidos.

Movimentos de migração e dispersão de adultos da cigarrinha-das-pastagens

O efeito do movimento de adultos da cigarrinha-das-pastagens (Deois flavopicta Stal) em sua dinâmica populacional foi avaliado em pastagens de Brachiaria ruziziensis na região do Distrito Federal, Brasil. Foram utilizados painéis de plástico com cola adesiva para monitorar as taxas de movimentação. Os dados sugerem a ausência de um padrão predominante de movimentação em relação à posição geográfica das armadilhas. A ocorrência de vegetação baixa, semelhante às pastagens em volta da área estudada, aparentemente favoreceu a dispersão, ao passo que a ocorrência de cerrados ou matas na vizinhança inibiu o movimento nesta direção e aumentou a taxa de retorno da cigarrinha às pastagens. O inseto se deslocou principalmente mediante saltos ou vôos curtos e baixos (abaixo de 1 m). Uma proporção aproximada de 4:1 (macho:fêmea) foi capturada nas armadilhas, indicando que os machos movimentam-se mais que as fêmeas. A velocidade média de movimentação, de populações marcadas com pó fluorescente atóxico e recapturadas após períodos variáveis de liberação, foi inferior a 5 m por dia. O movimento de dispersão de adultos não contribui significativamente para a perda ou recrutamento de adultos em populações de D. flavopicta, a não ser em casos de explosões populacionais ou extinção local.

Relationship between imaging biomarkers, age, progression and symptom severity in Alzheimer's disease.

The early diagnostic value of glucose hypometabolism and atrophy as potential neuroimaging biomarkers of mild cognitive impairment (MCI) and Alzheimer's disease (AD) have been extensively explored using [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) and structural magnetic resonance imaging (MRI). The vast majority of previous imaging studies neglected the effects of single factors, such as age, symptom severity or time to conversion in MCI thus limiting generalisability of results across studies. Here, we investigated the impact of these factors on metabolic and structural differences. FDG-PET and MRI data from AD patients (n = 80), MCI converters (n = 65) and MCI non-converters (n = 64) were compared to data of healthy subjects (n = 79). All patient groups were split into subgroups by age, time to conversion (for MCI), or symptom severity and compared to the control group. AD patients showed a strongly age-dependent pattern, with younger patients showing significantly more extensive reductions in gray matter volume and glucose utilisation. In the MCI converter group, the amount of glucose utilisation reduction was linked to the time to conversion but not to atrophy. Our findings indicate that FDG-PET might be more closely linked to future cognitive decline whilst MRI being more closely related to the current cognitive state reflects potentially irreversible damage.

Parâmetros escroto-testiculares e de sêmen em caprinos adultos submetidos à insulação escrotal

Ejaculados de seis bodes Moxotó e seis ½ sangue Moxotó-Pardo Alpina, adultos, mantidos em confinamento, foram avaliados antes e após a insulação do saco escrotal com bolsa de plástico, de parede dupla, durante 6,5 dias. A degeneração seminal ocorreu em todos os animais na 4ª semana após o início da insulação, ressaltando-se a redução na concentração, o aumento dos defeitos espermáticos e a redução do vigor celular, culminando com a necrospermia. A motilidade individual progressiva (MIP) atingiu os valores mais baixos na 3ª semana após o início da insulação, retornando aos valores normais entre a 8ª e 9ª semanas. Os defeitos espermáticos começaram a aumentar aos sete dias após o início da insulação escrotal. O volume apresentou oscilações atípicas e o aumento da temperatura escrotal afetou os parâmetros físicos e morfológicos do ejaculado de maneira consistente evidenciando-se o efeito negativo sobre a qualidade do sêmen.

Hippocampal and amygdalar volume changes in elderly patients with Alzheimer's disease and schizophrenia.

Patients with Alzheimer's disease (AD) and schizophrenia display cognitive, behavioural disturbances and morphological abnormalities. Although these latter reflect progressive neurodegeneration in AD, their significance in schizophrenia is still unclear. We explored the patterns of hippocampal and amygdalar atrophy in those patients and their associations with clinical parameters. Structural magnetic resonance imaging was performed in 20 elderly schizophrenia patients, 20 AD and 19 healthy older controls. Hippocampal and amygdalar volumes were obtained by manual segmentation with a standardized protocol and compared among groups. In both schizophrenia and AD patients, left hippocampal and amygdalar volumes were significantly smaller. The hippocampus/amygdala ratio was significantly lower in schizophrenia compared to both AD cases [2.4 bilaterally, 95% C.I. 2.2 to 2.7] and healthy controls bilaterally [2.5, 95% C.I. 2.3 to 2.9 in left and 2.7, 95% C.I. 2.4 to 3.1 in right hemisphere]. In schizophrenia patients, a significant positive correlation was found between age at disease onset and the right hippocampus/amygdala volume ratio (Spearman rho=0.56). Negative symptoms correlated with higher right/left amygdala volume ratio (Spearman's rho=0.43). Our data show that unlike AD, the hippocampus/amygdala ratio is abnormally low and correlates with the age at onset in schizophrenia, being a neurodevelopmental signature of the disease.

Buenos libros, malas lectoras: la enfermedad moral de las mujeres del siglo XIX

El seu article parteix de l'afirmació que el destí de les dones al segle XIX està marcat, en la ficció, pel "bovarysme", malaltia que proposa que les dones s'emmalalteixen i moren perquè llegeixen malament. El treball analitza aquest problema de la "mala lectura" traçant un recorregut que va des de Fernán Caballero fins a Freud i es comenten alguns episodis de lectura que apareixen en la "Autobiografía" de Gertrudis Gómez de Avellaneda, Clemencia, Amalia, Madame Bovary, María, La regenta i El caso Dora. Her article departs from the statement that the destiny of women in the 19th century is determined, in fiction, by "bovarysm", an illness which proposes that women get sick and die because they read incorrectly. The work analyzes this problem of "bad reading" tracing a journey from Fernán Caballero to Freud, and comments on several episodes about the act of reading, from Gertrudis Gómez de Avellaneda's "Autobiography", Clemencia, Amalia, Madame Bovary, María, La Regenta and Dora's Case.

Maladaptive exploratory behavior and neuropathology of the PS-1 P117L Alzheimer transgenic mice.

Patients with the early-onset Alzheimer's disease P117L mutation in the presenilin-1 gene (PS-1) present pathological hallmarks in the hippocampus, the frontal cortex and the basal ganglia. In the present work we determined by immunohistochemistry which brain regions were injured in the transgenic PS-1 P117L mice, in comparison to their littermates, the B6D2 mice. Furthermore, as these regions are involved in novelty detection, we investigated the behavior of these mice in tests for object and place novelty recognition. Limited numbers of senile plaques and neurofibrillary tangles were detected in aged PS-1 P117L mice in the CA1 only, indicating that the disease is restrained to an initial neuropathological stage. Western blots showed a change in PSD-95 expression (p=0.03), not in NR2A subunit, NR2B subunit and synaptophysin expressions in the frontal cortex, suggesting specific synaptic alterations. The behavioral tests repeatedly revealed, despite a non-significant preference for object or place novelty, maladaptive exploratory behavior of the PS-1 P117L mice in novel environmental conditions, not due to locomotor problems. These mice, unlike the B6D2 mice, were less inhibited to visit the center of the cages (p=0.01) and they continued to move excessively in the presence of a displaced object (p=0.021). Overall, the PS-1 P117L mice appear to be in an initial Alzheimer's disease-like neuropathological stage, and they showed a lack of reaction toward novel environmental conditions.

Inhibition in early Alzheimer's disease: an fMRI-based study of effective connectivity.

Changes of functional connectivity in prodromal and early Alzheimer's disease can arise from compensatory and/or pathological processes. We hypothesized that i) there is impairment of effective inhibition associated with early Alzheimer's disease that may lead to ii) a paradoxical increase of functional connectivity. To this end we analyzed effective connectivity in 14 patients and 16 matched controls using dynamic causal modeling of functional MRI time series recorded during a visual inter-hemispheric integration task. By contrasting co-linear with non co-linear bilateral gratings, we estimated inhibitory top-down effects within the visual areas. The anatomical areas constituting the functional network of interest were identified with categorical functional MRI contrasts (Stimuli>Baseline and Co-linear gratings>Non co-linear gratings), which implicated V1 and V3v in both hemispheres. A model with reciprocal excitatory intrinsic connections linking these four regions and modulatory inhibitory effects exerted by V3v on V1 optimally explained the functional MRI time series in both subject groups. However, Alzheimer's disease was associated with significantly weakened intrinsic and modulatory connections. Top-down inhibitory effects, previously detected as relative deactivations of V1 in young adults, were observed neither in our aged controls nor in patients. We conclude that effective inhibition weakens with age and more so in early Alzheimer's disease.

Further ultrastructural evidence that spirochaetes may play a role in the aetiology of Alzheimer's disease

Recently it was reported that, at autopsy, in neuropathologically confirmed cases of Alzheimer's disease spirochaetes were found in blood and cerebrospinal fluid using dark-field microscopy. Moreover, the spirochaetes were isolated and cultured from brain tissue. We now show, using scanning electron microscopy and atomic force microscopy that the helically shaped microorganisms isolated and cultured from the Alzheimer brains possess axial filaments. This indicates that these microorganisms taxonomically indeed belong to the order Spirochaetales. A morphometric analysis reinforces this notion.

How early can we predict Alzheimer's disease using computational anatomy?

Computational anatomy with magnetic resonance imaging (MRI) is well established as a noninvasive biomarker of Alzheimer's disease (AD); however, there is less certainty about its dependency on the staging of AD. We use classical group analyses and automated machine learning classification of standard structural MRI scans to investigate AD diagnostic accuracy from the preclinical phase to clinical dementia. Longitudinal data from the Alzheimer's Disease Neuroimaging Initiative were stratified into 4 groups according to the clinical status-(1) AD patients; (2) mild cognitive impairment (MCI) converters; (3) MCI nonconverters; and (4) healthy controls-and submitted to a support vector machine. The obtained classifier was significantly above the chance level (62%) for detecting AD already 4 years before conversion from MCI. Voxel-based univariate tests confirmed the plausibility of our findings detecting a distributed network of hippocampal-temporoparietal atrophy in AD patients. We also identified a subgroup of control subjects with brain structure and cognitive changes highly similar to those observed in AD. Our results indicate that computational anatomy can detect AD substantially earlier than suggested by current models. The demonstrated differential spatial pattern of atrophy between correctly and incorrectly classified AD patients challenges the assumption of a uniform pathophysiological process underlying clinically identified AD.

Early olfactory involvement in Alzheimer's disease.

BACKGROUND: In Alzheimer's disease (AD) the olfactory system, including the olfactory bulb, a limbic paleocortex is severely damaged. The occurrence of early olfactory deficits and the presence of senile plaques and neurofibrillary tangles in olfactory bulb were reported previously by a few authors. The goal of the present study was to analyze the occurrence of AD-type degenerative changes in the peripheral part of the olfactory system and to answer the question whether the frequency and severity of changes in the olfactory bulb and tract are associated with those of the cerebral cortex in AD. MATERIAL AND METHODS: In 110 autopsy cases several cortical areas and the olfactory bulb and tract were analyzed using histo- and immunohistochemical techniques. Based on a semiquantitative analysis of cortical senile plaques, neurofibrillary tangles and curly fibers, the 110 cases were divided into four groups: 19 cases with severe (definite AD), 14 cases with moderate, 58 cases with discrete and 19 control cases without AD-type cortical changes. RESULTS: The number of cases with olfactory involvement was very high, more than 84% in the three groups with cortical AD-type lesions. Degenerative olfactory changes were present in all 19 definite AD cases, and in two of the 19 controls. The statistical analysis showed a significant association between the peripheral olfactory and cortical degenerative changes with respect to their frequency and severity (P < 0.001). Neurofibrillary tangles and neuropil threads appear in the olfactory system as early as in entorhinal cortex. CONCLUSION: The results indicate a close relationship between the olfactory and cortical degenerative changes and indicate that the involvement of the olfactory bulb and tract is one of the earliest events in the degenerative process of the central nervous system in AD.

Danos causados pela broca-da-figueira na produção de frutos e flutuação populacional dos adultos

O objetivo deste trabalho foi avaliar o efeito dos danos causados por Azochis gripusalis Walker, 1859 (Lepidoptera: Pyralidae) na produção da figueira (Ficus carica L.) e o efeito de fatores climáticos sobre a flutuação populacional dos adultos no Estado de Minas Gerais. Quarenta plantas foram utilizadas para determinar o nível de dano, coletando-se os adultos semanalmente com armadilha luminosa. O aumento na porcentagem de ramos broqueados afetou o peso e o número de frutos produzidos. A redução na produção e a necessidade de controle fitossanitário ocorrem aos 10% e aos 40% de dano, respectivamente. A maior ocorrência da praga foi entre 19 de dezembro e 15 de maio. A temperatura foi o fator de maior influência no aumento populacional.

Eficàcia de les intervencions infermeres per a l'autocontrol de la tensió arterial en persones hipertenses

Fonaments: La hipertensió és una malaltia crònica amb alta prevalença al món. Els estils de vidasaludables es relacionen directament amb aquesta patologia pel que el rol de la infermeria és clauen el desenvolupament d'eines i intervencions per millorar l'autocontrol dels pacients hipertensosmitjançant l'educació sanitària.Objectiu: És valorar l'eficàcia de les intervencions en consultes d'infermera per a l'autocontrol dela tensió arterial en pacients amb hipertensió arterial respecte al seguiment habitual d'aquestspacients en consultes mèdiques.Mètode: S'estudiaran a 34 adults hipertensos mitjançant un assaig clínic aleatoritzat en dos grupsde 17 pacients hipertensos. El grup experimental serà objecte d'unes intervencions educativessobre la hipertensió i la repercussió dels estils de vida pel control d'aquesta patologia per partd'infermeria, a més a més, d'un control rutinari mèdic. Mentre que el grup control solamentassistirà als controls rutinaris mèdics sobre la hipertensió i no rebrà intervencions infermeres. Enl'avaluació de les dades es tindran en compte les variables de la mesura de la tensió arterial, ladieta, l'exercici físic i el seguiment del tractament, a més de diferents variablessociodemogràfiques com són l'edat, el gènere i el nivell socioeconòmic. Les dades s'analitzaranmitjançant Chi Cuadrat per a les variables qualitatives, la Correlació de Pearson i la de Spearmanper a les variables quantitatives i, finalment, la T de Student per a la comparació de la mitja de lesdues mostres independents.Conclusió: Amb l'assaig clínic es pretés demostrar que les intervencions d’infermeria en consultesmilloren l'autocontrol dels pacients amb hipertensió arterial, és a dir, són eficaces.