Patricio Pérez

Human platelets tau: a potential peripheral marker for Alzheimer's disease.

Platelets are a major peripheral reservoir of the amyloid-β protein precursor, so they have been considered as a potential biological marker of Alzheimers disease (AD). Here, it is demonstrated that tau protein is also present in platelets and that the levels of oligomeric species of this protein could serve as a novel and reliable biological marker for AD. Blood samples were obtained from 15 AD patients and 10 paired-age controls and platelets were separated via differential centrifugation. The purity of platelets was determined by flow cytometry and microscopy and the presence of tau was determined by immunofluorescence and immunoblots with tau specific antibodies. Immunofuorescence and immunoblot patterns of platelets were positive for tau. Immunoblots also showed the presence of high molecular weight (HMW) variants of tau that appeared to correspond to oligomeric forms of the protein. The ratio of HMW tau respect to tau monomeric species was significantly higher in AD patients than controls. The present is the first description of the presence of tau in platelets. The analysis of different tau fractions in platelets could serve as a new biological marker for AD.

Platelet Tau Pattern Correlates with Cognitive Status in Alzheimer's Disease

Platelets are major reservoirs of circulating amyloid-β and amyloid-β protein precursor (AβPP) and have been postulated as a reliable source for biological markers of Alzheimers disease (AD). We have recently demonstrated that tau is also present in platelets, and that there are differences in the electrophoretic patterns of platelet tau forms in AD subjects with respect to controls. Here, we demonstrate that modifications in platelet tau forms occur independently of age in a broad population of 104 neurologically healthy individuals. More interesting, a strong correlation of platelet markers with the degree of cognitive impairment was evidenced in a group of 47 AD patients in comparison with 19 cognitive healthy subjects. In our series, platelet tau forms ratio had a sensitivity of 75.7% and specificity of 73.7%, respectively. We also found that platelet tau displays a significantly higher correlation with the presence of AD than the analyses of platelet AβPP.

FEEDING DRY OLIVE CAKE MODIFIES SUBCUTANEOUS FAT COMPOSITION IN LAMBS, NOTING CAKE RESISTANCE TO DEGRADATION AND PEROXIDATION

The purpose of this experiment was to determine the extent to which lamb carcass quality and fat composition could be altered by applying a dry olive cake-based ration instead of a conventional ration or pasture feeding. Three treatments were compared in a completely randomized experiment using 36 single male Suffolk Down lambs with an initial age and live weight of 80 d and 25 kg, respectively. The three treatments were: (a) suckling lambs kept with their mothers on annual Mediterranean grassland (GRAZE); (b) weaned stall-fed lambs on a control ration (CONC); and (c) weaned stall-fed lambs on an olive cake-based ration (CAKE). At the end of the 28-d experimental period, lambs were slaughtered, carcass quality evaluated, and samples of subcutaneous fat analyzed for fatty acids. Treatments did not differ in weight gain or carcass weight and quality, but highly significant differences were found in several fatty acid contents. CAKE animals had reduced palmitic acid as well as increased oleic and stearic acid contents. Atherogenic and thrombogenic indices improved with cake feeding. Principal component and discriminant analyses clearly differentiated treatments suggesting they could be applicable for traceability purposes. A laboratory experiment demonstrated that with or without added vitamin E, the dry olive cake did not alter its lipid properties with increased storage time.

Performance of lambs grazing an annual Mediterranean pasture or fed supplements based on olive oil cake or maize and its influence on system outputs

Three lamb feeding strategies were compared, including finishing of suckling lambs on an annual Mediterranean pasture (GRAZE), weaned followed by a concentrate plus hay diet (CONC), or weaned and fed a concentrate with 33% dry olive oil cake plus hay (CAKE). Grazing lambs averaged a liveweight gain of 334 g/day during the 28-day experimental period, which was higher (P < 0.05) than that of CONC and CAKE (283 and 276 g/day, respectively); however, there were no differences in empty body or dressed carcasses weights due to dietary treatment. The feed conversion of the olive seed cake supplement (kg supplement/kg gain) was lower (P < 0.01) than that of the maize-based supplement. Despite some significant differences between carcasses traits, all were small and of little commercial consequence. Simulation modelling of whole-system performance suggested that early weaning of lambs followed by concentrate feeding would reduce the finishing period, marginally increase the liveweight of ewes and would have little effect on pasture availability. It was further concluded that olive oil cake can be a large proportion of concentrate diets without negatively affecting carcass quality.

Revalidación de Aristolochia pearcei Phil. y notas acerca de la identidad de A. bridgesii (Klotzsch) Duch. (Aristolochiaceae)

Mediante un estudio detallado de las descripciones originales y de los ejemplares tipo, ademas del analisis de nuevos materiales recolectados, se establece que Aristolochia bridgesii y A. pearcei, entidades hasta ahora consideradas sinonimos, corresponden a especies distintas, con una morfologia floral notoriamente diferente y con areas de distribucion alopatricas separadas por mas de 300 km en sentido latitudinal. De este modo, para Chile se reconocen, a la fecha, tres especies, A. bridgesii, A. pearcei y A. chilensis. Se entrega una completa ilustracion de A. bridgesii y una clave para el genero en Chile. Adicionalmente A. bridgesii y A. pearcei son lectotipificadas.

Nuevas combinaciones, una epitipificación y una corrección nomenclatural en Thelocephala (Cactoideae: Notocacteae): género endémico de Chile

Within the revision works of the Thelocephala genus it is necessary to carry out new combinations for generic entities recently described under the broad concept of Eriosyce. Additionally, it has been made a correction for one of the binomies used by F. Ritter in 1980 and an epitype is designated for one of the recent taxa.