Central nervous system -specific

As would be expected, most effort has been most focused on the detection of nonmuscle tissue that is related to the enforcement of human health and food safety. To enable effective enforcement and removal of SRM, there has been a need for the development of robust CNS (central nervous system)-specific detection methods that are applicable to a wide range of processed meat products. In the case of non-DNA-based techniques, methods for the detection of CNS tissue in meat include direct tissue examination (Bauer et al., 1996), histological preparation and microscopic examination (USDA-FSIS, 1998), and the analysis of cholesterol content (LiickeretaL, 1999 Schmidt et al., 1999). 

Taste-active chemicals react with receptors on the surface of sensory cells in the papillae causing electrical depolarization, ie, drop in the voltage across the sensory cell membrane. The collection of biochemical events that are involved in this process is called transduction (15,16). Not all the chemical steps involved in transduction are known however, it is clear that different transduction mechanisms are involved in different taste quaUties different transduction mechanisms exist for the same chemical in different species (15). Thus the specificity of chemosensory processes, ie, taste and smell, to different chemicals is caused by differences in the sensory cell membrane, the transduction mechanisms, and the central nervous system (14). 

Dmg receptors represent another type of receptor family. The central nervous system (CNS) effects of the anxiolytic, diazepam, and the psychotropic actions of the caimabiaoids and phencycUdine have resulted ia the identification of specific receptors for these molecules. This has resulted ia the search for an endogenous ligand for these receptors. Thus, ia these situations, the pharmacological action has preceded the discovery of the receptor which, ia turn, has provided clues ia several iastances to the endogenous ligand. 

Pituitary Adenylyl Cyclase-activating Polypeptide (PACAP) is a 38-amino acid peptide (PACAP-38), which is widely expressed in the central nervous system. PACAP is most abundant in the hypothalamus. It is also found in the gastrointestinal tract, the adrenal gland and in testis. Its central nervous system functions are ill-defined. In the periphery, PACAP has been shown to stimulate catecholamine secretion from the adrenal medulla and to regulate secretion from the pancreas. Three G-protein coupled receptors have been shown to respond to PACAP, PAQ (PACAP type I) specifically binds PACAP, VPACi and VPAC2 also bind vasoactive intestinal peptide (VDP). Activation of PACAP receptors results in a Gs-mediated activation of adenylyl cyclase. 

Enterochromaffin cells are interspersed with mucosal cells mainly in the stomach and small intestine. In the blood, serotonin is present at high concentrations in platelets, which take up serotonin from the plasma by an active transport process. Serotonin is released on platelet activation. In the central nervous system, serotonin serves as a transmitter. The main serotonin-containing neurons are those clustered in form of the Raphe nuclei. Serotonin exerts its biological effects through the activation of specific receptors. Most of them are G-protein coupled receptors (GPCRs) and belong to the 5-HTr, 5-HT2-, 5-HT4-, 5-HTs-, 5-HT6-, 5-HT7-receptor subfamilies. The 5-HT3-receptor is a ligand-operated ion channel. 

Vergote D, Butler GS, Ooms M, Cox JH, Silva C, Hollenberg MD, Jhamandas JH, Overall CM, Power C (2006) Proteolytic processing of SDF-lalpha reveals a change in receptor specificity mediating HIV-associated neurodegeneration. Proc Nad Acad Sci USA 103(50) 19182-19187 von Giesen HJ, Roller H, Theisen A, Arendt G (2002) Therapeutic effects of nonnucleoside reverse transcriptase inhibitors on the central nervous system in HlV-1-infected patients. J Acquir Immune Defic Syndr 29(4) 363-367... 

Sorensen TL, Sellebjerg F (2001) Distinct chemokine receptor and cytokine expression profile in secondary progressive MS. Neurology 57 1371-1376 Sorensen TL, Tani M, Jensen J, Pierce V, Lucchinetti C, Folcik VA, Qin S, Rottman J, Sellebjerg F, Strieter RM, Frederiksen JL, Ransohoff RM (1999) Expression of specific chemokines and chemokine receptors in the central nervous system of multiple sclerosis patients. J Clin Invest 103 807-815... 

The mechanism whereby the bacteria produce the disease with its attendant symptoms is often due to the cells ability to produce specific poisons, toxins or aggressins (Chapter 14). Many of these are tissue-destroying enzymes which can damage the cellular structure ofthe body or destroy red blood cells. Others (neurotoxins) are highly specific poisons ofthe central nervous system, for example the toxin produced by Clostridium botulinum is, weight for weight, one ofthe most poisonous substances known. 

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