Quantitative electroencephalography power and coherence measurements in the diagnosis of mild and moderate Alzheimer's disease / Medidas de coerência e de potência absoluta no eletrencefalograma quantitativo no diagnóstico da doença de Alzheimer

OBJECTIVE: To evaluate the contribution of quantitative electroencephalographic (qEEG) analyses in the diagnosis of Alzheimer's disease (AD). METHOD: Thirty-five patients from the Neurology Outpatients Clinic of PUC-Campinas, diagnosed with AD according to the NINCDS/ADRDA were evaluated, and compared with a control group consisting of 30 individuals with no cognitive deficit. The procedures consisted of clinical-neurological, cognitive and behavioral analyses and the qEEG (absolute power and coherence). RESULTS: The AD group presented greater absolute power values in the delta and theta bands, greater theta/alpha indices and less frontal alpha and beta coherence. Logistic multiple regression models were constructed and those only showing variations in the qEEG (frontal alpha coherence and left frontal absolute theta power) showed an accuracy classification (72.3 percent) below that obtained in the mini-mental state examination (93 percent). CONCLUSION: The study of coherence and power in the qEEG showed a relatively limited accuracy with respect to its application in routine clinical practice.

OBJETIVO: Avaliar a contribuição das análises quantitativas do eletroencefalograma (qEEG) no diagnóstico da doença de Alzheimer (DA). MÉTODO: Foram avaliados 35 pacientes do ambulatório de Neurologia Clínica da PUC-Campinas, com o diagnóstico de DA segundo o NINCDS/ADRDA e comparados a 30 indivíduos, sem déficit cognitivo, de grupo controle. Os procedimentos foram avaliação clínico-neurológica, cognitiva e comportamental e EEGq (potência absoluta e coerência). RESULTADOS: O grupo DA apresentou maiores potências absolutas nas faixas delta e teta, maiores índices teta/alfa e menor coerência alfa e beta frontal. Foram construídos modelos de regressão múltipla logística e aquele que contou apenas com variáveis do EEGq (coerência alfa frontal e potência absoluta teta frontal esquerda) teve acurácia de classificação (72,3 por cento), inferior à obtida com o mini-exame do estado mental (93 por cento). CONCLUSÃO: O estudo de coerência e potência no qEEG tem acurácia relativamente limitada no sentido de aplicação prática clínica rotineira.

Free radical generation in the toxicity of inhaled mineral particles: the role of iron speciation at the surface of asbestos and silica.

Free radical generation at the particle/biological fluid interface is one of the chemical processes that contributes to pathogenicity. In order to investigate the role played by iron, fibres of crocidolite asbestos have been modified by thermal treatments to alter their surface iron content. Two radical mechanisms, HO* from H2O2 and cleavage of a C-H bond, which are both active on the original fibres, have been tested on the modified fibres. C-H cleavage is dependent on Fe(II) abundance and location and is suppressed by surface oxidation while HO* release appears independent of the oxidation state of iron. Quartz specimens with different levels of iron impurities have been tested in a similar manner. A commercially available quartz (Min-U-Sil 5) containing trace levels of iron is also active in both tests, but reactivity is not fully suppressed by treatment with desferrioxamine, which should remove/inactivate iron. The radical yield attained is close to the level produced by a pure quartz dust, suggesting the presence of active sites other than iron. Ascorbic acid reacts with both crocidolite and quartz, with subsequent depletion of the level of antioxidant defences when particle deposition occurs in the lung lining layer. Following treatment with ascorbic acid the radical yield increases with quartz, but decreases with asbestos. Selective removal of iron and silicon from the surface may account for the differences in behaviour of the two particulates.

Iron inhibits the nitric oxide synthesis elicited by asbestos in murine macrophages.

Crocidolite fibers stimulated nitric oxide synthase (NOS) activity and expression in glial and alveolar murine macrophages: this effect was inhibited by iron supplementation and enhanced by iron chelation. We suggest that in these cells crocidolite stimulates NOS expression by decreasing the iron bioavailability and activating an iron-sensitive transcription factor.

Extensive atrazine pollution of drinking water in the Lombardia region and related public health aspects.

Introduced in 1957, atrazine is a herbicide used worldwide, mainly in corn cultivation areas for weed control. It is only slightly volatile, is highly soluble in water, and is moderately persistent in topsoil, where it is strongly absorbed to organic carbon. Because of these properties, atrazine can leach to ground water and persist for a long time. This work presents the results obtained so far from an investigation initiated because of an emergency situation in the Lombardia Region of Italy caused by the occurrence of levels of atrazine in drinking water exceeding those established by the European Economic Community and Italian regulations. Water samples from almost 3000 wells were analyzed in different laboratories of the Lombardia Region. Atrazine contamination occurred in a significant number of the wells examined. Examination of the analytical data overall leads to the conclusion that the agricultural use of atrazine in the Lombardia Region is a serious source of ground water contamination. In some areas other factors may be responsible for the contamination of ground water (for instance, industrial activities and/or uncontrolled waste discharges). Geological and hydrological characteristics may play an important role in ground water contamination. Purification systems containing active charcoal seem to be highly efficient in removing atrazine from contaminated water.