Regional levels of membrane phospholipids [phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylcholine (PC)] were measured in the brain of Alzheimer's disease (AD) and control subjects. The levels of PE-derived and PI-derived total fatty acids were significantly decreased in the hippocampus of AD subjects. Here significant decreases were found in PE-derived stearic, oleic and arachidonic and docosahexaenoic acids, and in PI-derived oleic and arachidonic acids. In the inferior parietal lobule of AD subjects, significant decreases were found only in PE and those decreases were contributed by stearic, oleic and arachidonic acids. In the superior and middle temporal gyri and cerebellum of AD subjects, no significant decreases were found in PC-, PE- and PI-derived fatty acids. The decrease of PE and PI, which are rich in oxidizable arachidonic and docosahexaenoic acids, but not of PC, which contains lesser amounts of these fatty acids, suggests a role for oxidative stress in the increased degradation of brain phospholipids in AD.

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Previous studies have suggested that the neurotrophins brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) are neuroprotective or neurotrophic for certain subpopulations of hippocampal neurons following various brain insults. In the present study, the expression of BDNF and NT-3 mRNAs in rat hippocampus was examined after traumatic brain injury. Following lateral fluid percussion (FP) brain injury of moderate severity (2.0-2.1 atm) or sham injury, the hippocampi from adult rats were processed for the in situ hybridization localization of BDNF and NT-3 mRNAs using 35S-labeled cRNA probes at post-injury survival times of 1, 3, 6, 24 and 72 h. Unilateral FP injury markedly increased hybridization for BDNF mRNA in the dentate gyrus bilaterally which peaked at 3 h and remained above control levels for up to 72 h post-injury. A moderate increase in BDNF mRNA expression was also observed bilaterally in the CA3 region of the hippocampus at 1, 3, and 6 h after FP injury, but expression declined to control levels by 24 h. Conversely, NT-3 mRNA was significantly decreased in the dentate gyrus following FP injury at the 6 and 24 h survival times. These results demonstrate that FP brain injury differentially modulates expression of BDNF and NT-3 mRNAs in the hippocampus, and suggest that neurotrophin plasticity is a functional response of hippocampal neurons to brain trauma.

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vibrations at the liquid surface and cavitation at the gas±liquid interface [16].All the chemicals were obtained from Aldrich Chemicals. In a typical experiment, a methanolic solution of the acetate of zinc, cadmium, cobalt, or lead was prepared with a concentration of 40 g L ±1. The solution was nebulized and the spray carried into a preheated silicon carbide furnace maintained between 800 and 900 C using Ar as a carrier gas. Typical flow rates of Ar used were between 500 to 1000 standard cubic centimeter per minute (sccm). All experiments were performed using a quartz tube with an inner diameter of 25 mm. The reaction was typically carried out for 30 min. The shiny deposits obtained at the outlet (shown in Fig. 1) were used for further analysis. The yield of the nanowires was generally high (~90 %).Characterization: Powder X-ray diffraction (XRD) patterns were recorded using a Seifert XRD 3000 TT instrument. SEM images were obtained with a Leica S-440I microscope. TEM images were recorded with a JEOL JEM 3010 instrument operating at an accelerating voltage of 300 kV fitted with a Gatan CCD camera. Photoluminescence measurements were carried out at room temperature using a 325 nm excitation wavelength with a Perkin-Elmer model LS50B luminescence spectrometer. Thermogravimetric analysis of the samples was carried out on a Mettler-Toledo-TG-850 apparatus. Platinum nanoparticles are currently the subject of intense interest because of their unique catalytic properties; hence, synthesis methodologies of platinum-related catalysts have developed into an increasingly important research area at the frontier of advanced materials chemistry.[1±3] In catalysis, it is of extreme importance to maintain a high surface area for a long period of time at the catalyst's operating temperature.[4]The fabrication of nanoparticlesÐin particular, controlling their shape and ensuring a narrow size distribution of metal nanoparticlesÐhas thus become an important topic in nanotechnology.[5] A number of porous support materials, such as silica, alumina, zeolites, and MCM-41 (mobile crystalline material), have been used to deposit platinum nanoparticles by employing impregnation or ion-exchange methods.[6±8] However, such an approach has not provided a simple way to form robust and reusable catalysts for heterogeneous catalysis. The core±shell approach, whereby nanoparticles enclosed by protecting agents are grown in the channels of porous materials, is of considerable technological importance for improving the lifetime and the reusability of catalysts. [9,10] Herein, we describe the direct synthesis of spherical, mesoporous, nanosized platinum composites (Pt/PVP@MCM-41) via a core±shell approach.As shown in Scheme 1, Pt/PVP@MCM-41 composite particles were prepared by liquid-phase self-assembly. Initially, a colloidal dispersion of platinum nanoparticles was synthesized by employing poly(vinylpyrrolidone) (PVP) as the protecting agent under solvothermal conditions.[11] The Pt/PVP nanoparticles were found to be stable for longer times in ...