Sample processing brain

Figure 9.38 Concentration profile of copper and zinc in the scanned area of interest measured by LA-ICP-MS on brain samples (hippocampus). Calibration was performed via synthetic matrix matched laboratory standards for 1, 5 and 10 fxgg-1 of analyte (see inserted figures on left). Bottom histologically processed brain tissue in which cell bodies were stained (cresyl violet staining) in order to demonstrate the layered structure of the analyzed region. (]. S. Becker, M. Zoriy, C. Pickhardt, N. Palomero-Gallagher and K. Zilles, Anal. Chem., 77, 3208 (2005). Reproduced by permission of American Chemical Society.)...

The competitive assay fonnat [82-84] (Fig. 8) performed better than noncompetitive assays [85] for the determination of prion protein (PrP) in brain samples. In the competitive assay, antigen in the sample competes in solution, prior to injection onto the CE column, with a labeled peptide of the PrP to bind to an antibody directed against this peptide. The presence of antigen in the sample increased the size of the CZE peak corresponding to free labeled peptide and decreased that of peptide bound to antibody. Probably, in this case, the higher performance of the competitive mode was not related to the format of the assay but to the successive improvements in sample and antibody purification, in the process of peptide labeling, and in the carefiil choice of the separation buffer carried out in this format. 

Studies of sleep-active neuronal discharge across the sleep-wake cycle in freely moving animals provide important information about the hypnogenic process (see below) but, because of sampling limitations, are not suitable for systematic mapping of the exact locations of putative hypnogenic neurons. The application of the c-Fos immunoreactivity (IR) method to map sleep-active neurons has stimulated several advances. C-Fos IR is a marker of neuronal activation in most brain sites immunohistochemically labeled neurons can be mapped systematically. The localization of c-Fos IR following sustained sleep, but not... 

Fig. 5. Kinetics of brain microtubule depolymerization following rapid dilution. (A) Time course of the disassembly reaction with experimental data represented by the data points and the theoretical progress curve indicated by the solid line. (The inset to A shows that the process can be fitted to a simple decaying exponential for part of the depolymerization reaction.) (B) Microtubule length distribution for the sample subjected to rapid dilution in A. (Reproduced from Karr et al. (1980)./. Biol. Chm. 255, 8560-8566.)...

Figure 6.2. Schematic drawing of the microdialysis probe used to sample the concentration of dopamine, DOPAC, 5HIAA and HVA in the extracellular space in rat brains. The fluid is delivered by a pump and passes via the vertical inlet and the inner cannula down to a 3.0 0.5 mm part of the probe, where a semipermeable membrane surrounds the inner cannula (stippled lines). The dialysis process occurs when the fluid passes between the inner cannula and the dialysis membrane. The perfusion medium flows inside the outer cannula to the horizontal outlet and is collected in 20 min (40 pi)...

In vivo microdialysis is a technique that allows sampling of extracellular levels of neurotransmitters in discrete regions of the brain. The extracellular neurotransmitter levels provide an indication of the net activity of a particular set of neurons, including release, synthesis, and uptake, from conscious unanesthetized animals. For example, in vivo microdialysis studies have shown that extracellular 5-HT levels measured under appropriate conditions are dependent on the concentration of Ca2+ or K+ in the perfusion fluid, is inhibited by tetrodotoxin, and is predominately neuronal in origin (45). In addition, specific neural processes can be measured after the local application of agents through the microdialysis probe, such as release after application of hypertonic KC1, rate of synthesis after synthesis inhibitors, or the local effects of drugs (46). This technique has made it possible to more accurately quantitate and characterize the... 

Although this procedure is necessary for production of samples of pure virions it is usually unnecessary if a viral preparation is only required for subsequent infections. In such circumstances the cells should be harvested aseptically and processed to step e, omitting the DNase and RNase. The debris from the disrupted cells is pelleted at 15,000g for 30 min and the supernatant used as a source of virus. It should be tested for bacterial contamination with brain-heart infusion broth and Saboraud fluid medium (Appendix 4). The virus should be stored at -70°C at about 1010 p.f.u./ml. 

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