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Natural neural tissues

Biomedical research continues to broaden our understanding of the molecular mechanisms underlining both health and disease. Research undertaken since the 1950s has pinpointed a host of proteins produced naturally in the body that have obvious therapeutic applications. Examples include the interferons and interleukins (which regulate the immune response), growth factors, such as erythropoietin (EPO which stimulates red blood cell production), and neurotrophic factors (which regulate the development and maintenance of neural tissue). [Pg.3]

The receptor-like protein tyrosine phosphatases have a transmembrane and, in some cases, a large extracellular domain with a very variable structme (Fig. 8.16). Many, but not all, membrane protein tyrosine phosphatases have two catalytic domains in the cytoplasmic region. The complete structme is very similar to the structure of transmembrane receptors. Understanding of their function is far from complete. Both the natural ligands and the substrate proteins following in the sequence are incompletely characterized. Several studies have demonstrated a role for receptor-like PTPs in neuronal cell adhesion signaling pathways. In cells of the neural tissue, a surface protein, contactin has been identified as ligand for the extracellular domain of a protein tyrosine phosphatase (Peles et al., 1995). [Pg.313]

Malignancies, particularly of neural crest origin, are known to affect brain function adversely through remote (presumably hormonal) effects on neural tissue. For example, ovarian adenocarcinoma can selectively induce a profound cerebellar syndrome caused by the selective death of Purkinje cells (presumably from a neurotoxic hormonal factor). Such phenomena simply illustrate the complicated nature of CNS functioning and the need to be cautious about explanations in the absence of systematic data. [Pg.106]

It is becoming more popular in the US for infant formula manufactures to add fish oils to fortify infant formulae with long-chain polyunsaturated fatty acids, which are critical in early child development because they are necessary for the formation of neural tissues and cells of vascular tissue, but are produced de novo at very low levels from the dietary essential fatty acids Ci8 2, m-3 and Cis 3, co-3. Typically, the long-chain fatty acids, doco-sahexaenoic acid (DHA C22 6) and arachidonic acid (AA C2o 4), were not added to infant formulae available in the US until recently. Many commercial infant formulae manufactures, including Wyeth, Ross and Mead Johnson, now produce infant formulae that are supplemented with DHA and AA. The level of DHA is approximately 0.32%, w/w of fat, and the level of AA is approximately 0.64% w/w of fat. Breast-milk naturally contains small amounts of these long-chain polyunsaturated fatty acids. [Pg.475]

The most unsaturated fatty acid found in significant quantities in nature (some algal lipids contain trace amounts of fatty acids with as many as eight double bonds) is DHA. This fatty acid is known to be especially important in the neural development in animals indeed, DHA alongside ARA are the predominant PUFA in neural tissue (56). A deficiency in DHA in has been linked to impaired brain and visual development in neonates (56). [Pg.1504]

The structure of chemicals and their differential access to the nervous system are of critical importance in determining the presence and nature of the neurotoxic response. While access to nervous tissue dictates the possibility of a direct neurotoxic effect, neurotoxicity ultimately depends on the ability of the substance to bind to neural tissue targets and interfere with functional or structural integrity. Structure-activity relationships are therefore of cardinal importance. For example, 1,2-diacetylbenzene but not 1,3-diacetylben-zene induces leg weakness because only the former binds to and crosslinks neuroproteins. Triethyltin targets the myelin sheath, trimethyltin damages neurons, but tributyltin lacks neurotoxic properties - another illustration of the critical importance of chemical structure in determining the presence and nature of the neurotoxic response. [Pg.1793]

The in vitro biocompatibility of CPs has been generally investigated by cell viability, proliferation and cytotoxicity assays of various cell types, including rat pheochromocy-toma cells (PC 12), rat Schwann cells, cardiac myoblasts, astrocytes, and various neural tissue explants [ 13,27,43,47]. Studies on a wide variety of CPs have indicated good in vitro cell responses, with minimal cytotoxicity and, in several cases, preferential adherence of cells to the CP surface, compared to conventional implant materials. However, the majority in vitro studies examine the passive or nonelectrochemically activated state of CPs. Due to the application-specific nature of biocompatibility, passive CP assessment, although a useful preliminary study, is an imperfect characterization of CP biological performance for most implant applications. [Pg.726]

In the development of scaffolds for tissue regeneration, the use of composite materials with diverse chemical and physical properties maybe plausible to mimic the complex cellular microenvironment. In general, composite scaffolds can be prepared using a simple combination of both natural and synthetic polymers and both organic and inorganic materials, which are desired for their unique properties. Here, we will briefly discuss composite scaffolds used in bone, muscle, and neural tissue regeneration. [Pg.226]

In most cases in nature, a toxin, naturally produced by an organism, comes at a cost to its producer, and as such, toxic chemicals that do not convey a distinct survival advantage to the producer represent an energetic cost without any fitness benefit. Under these circumstances, the toxic chemical is not likely to remain in production over generational periods of time, as the costs can far outweigh the benefits. Prions turn this idea on its head, as the prion is produced accidentally, not deliberately. Furthermore, a prion is a self-replicating entity therefore the concept of a dose-response relationship is limited in its utility, as the concentration of prions within the neural tissue of an infected animal is likely to increase over time even without successive inoculations from the environment. At the same time, however, a prion does not behave in the environment like other natural organic chemicals, as they are persistent, and environmental exposure to bioactive prions is a very real prospect. Prions represent a special class of compound that is neither alive nor merely a toxic chemical, but rather shares properties of both. [Pg.163]


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