In the present study, neurons of the entorhinal cortex, hippocampus and frontal lobe from non-demented and Alzheimer's disease (AD) cases, were stained in order to study neurofibrillary changes. We have used double immunolabeling with a phosphorylation dependent monoclonal antibody (mAb) to tau, AD2, and the histochemical dye thiazin red (TR). MAb AD2 specifically recognizes phosphorylated Ser396 and Ser404, while TR shows binding sites for amyloid-β and tau when they are in fibrillar states. We show a morphological sequence of changes in the development of neurofibrillary tangles (NFTs), starting from mAb AD2 diffuse labeling in non-NFT bearing cells recognized by mAb AD2, then going through two subtypes of intracellular NFTs, to a final stage as extracellular-NFTs. Morphometric analysis of the density of AD2 immunoreactive structures showed the NFT density in hippocampus and frontal lobe were the best parameters to differentiate normal aging from AD. Densities of AD2 immunoreactive structures in hippocampus and frontal lobe correlated with the Clinical Dementing Rating score. Based upon the variety of appearances of immunoreactivity displayed by mAb AD2, we were able to stage neurofibrillary changes at the level of individual neurons and brain areas. Our results demonstrate that the intensity of neurofibrillary changes in the hippocampus as well as the extent of the degeneration process in association areas differentiate normal aging from AD, and are well correlated with cognitive impairment.
Worldwide, the most important reuse of wastewater, in volume, is agricultural irrigation. Therefore, there is a need to properly treat wastewater for such purpose, considering the removal of pathogens while leaving suitable amounts of nutrients and other compounds to increase productivity. Helminth ova are one of the main targeted pathogens in the new guidelines for water reuse in agriculture and aquaculture issued in 2006 by the World Health Organization. However, relatively little research has been done recently on how to remove and inactivate helminth ova from wastewater and sludge and recommendations given several decades ago are still used, but when put into practice, particularly in developing countries, produce unsatisfactory results. One problem is that these criteria were developed using inaccurate analytical techniques and the other is the large number and variety of helminth ova species found in wastewater and sludge from the developing world. In fact, the few technological options to remove and inactivate helminth ova come from research performed using wastewater and sludge with low helminth ova content, and refer almost only to Ascaris (one type of helminth). This paper summarises recent research work and results from practical experience concerning helminth ova control for advanced and conventional sanitation.
During an outbreak of gastroenteritis in 28 children living in a small neighbourhood of Cuernavaca city (Mexico), a survey was performed to evaluate the confidence in coliform bacteria as sole indicators of potability of drinking waters. A primary infection by E. coli and a secondary by Pseudomonas aeruginosa was diagnosed in five of the children and the drinking water provided by a well was suspected as a transmission source. General and household distribution systems, household filters and bottled waters were evaluated for total and faecal coliforms, family Enterobacteriaceae, Paeruginosa and residual chlorine. In every sample, pathogenic/opportunistic bacteria were isolated even in the absence of coliforms and in the presence of residual chlorine. Arbitrarily assigned “pollution/risk levels” indicated that the most elevated risk was most frequently associated with storage in tanks and with bacterial colonisation in the pipeline system and commercial household filters where high levels of Paeruginosa were determined. A probability of correspondence between the presence of this bacterium and the secondary gastrointestinal infection diagnosed was found pointing towards a need for the inclusion of other microorganisms, one of which may be Paeruginosa, as indicators of health risk associated with drinking waters in Mexico.
A survey of protozoa polluting bottled mineral water in Mexico was carried out using samples obtained form the three best-selling brands of bottled mineral water in the country. The organisms were concentrated through filtration procedures and subsequently cultured in the sterile media. The cultures were observed over four weeks, with identification to the level of genus and species. Most commonly found were the amoebae Naegleria gruberi, Acanthamoeba astronyxis, and Vahlkampfia vahlkampfi (trophic as well as cystic stages) plus one flagellate, Bodomorpha minima. No ciliates were detected. The public health importance of the findings is obvious, since some strains of Naegleria and Acanthamoeba have the potential to cause human disease that may lead to death.
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