Reticular

Netz-, wetting, steeping net, netting, reticular, omental. -adern,/.pi. netted veins or cracks. 

Netz-werkstruktur,/. (Metal., etc.) reticular or cellular structure, -wirkung,/. wetting(-out) action or effect. 

The possibility of conformational changes in chains between chemical junctions for weakly crosslinked CP in ionization is confirmed also by the investigation of the kinetic mobility of elements of the reticular structure by polarized luminescence [32, 33]. Polarized luminescence is used for the study of relaxation properties of structural elements with covalently bonded luminescent labels [44,45]. For a microdisperse form of a macroreticular MA-EDMA (2.5 mol% EDMA) copolymer (Fig. 9 a, curves 1 and 2), as compared to linear PM A, the inner structure of chain parts is more stable and the conformational transition is more distinct. A similar kind of dependence is also observed for a weakly crosslinked AA-EDMA (2.5 mol%) copolymer (Fig. 9b, curves 4 and 5). 

The pore structure of most cross-linked polystyrene resins are the so called macro-reticular type which can be produced with almost any desired pore size, ranging from 20A to 5,000A. They exhibit strong dispersive type interaction with solvents and solutes with some polarizability arising from the aromatic nuclei in the polymer. Consequently the untreated resin is finding use as an alternative to the C8 and Cl8 reverse phase columns based on silica. Their use for the separation of peptide and proteins at both high and low pH is well established. 

Unfortunately, silica gel suffers from a severe disadvantage in that it is slightly soluble in water. This means that the native silica cannot be used in conjunction with aqueous mobile phases. Consequently, silica is precluded from use in the separation of those substances that are strongly polar and require aqueous solvents to render them soluble and stable. For this reason the relatively new, micro-reticular resins are now used in the separation of strongly polar substances by exclusion chromatography. 

The ER has a reticular morphology which provides a large surface area, which presumably is required for the synthesis and transport of proteins and lipids and for the storage of calcium. The ER is associated with microtubules, and the two are highly interdependent structures. Terasaki et al. (1986) found that when microtubules in the cell are depolymerized by colchicine, the ER network slowly retracts toward the center of the cell. If the microtubules are repolymerized, the ER network is restored to its original morphology, thereby suggesting that the MTs participate in the formation and maintenance of the ER. 

Barbiturates produce CNS depression, which ranges from sedation to general anesthesia. Action is through suppression of the mesencephalic reticular activating system. Barbiturates enhance GABA-induced inhibition the site of inhibition may be presynaptic in the spinal cord or postsynaptic in the cortical... 

Patients of varying skin types (1-V) having striae distensae alba on the abdomen or thighs can apply topical 20% glycolic acid daily to the entire treatment area. In addition, these patients apply 10% L-ascorbic acid, 2% zinc sulfate, and 0.5% tyrosine to half of the treatment area and 0.05% tretinoin emollient cream to the other half of the treatment area. The creams are applied on a daily basis for 12 weeks. Improvement is evaluated at 4 and 12 weeks with increased elastin content within the reticular and papillary dermis [14]. 

B9 Nucleus prosupralemniscus B1 and B3 Neurons of the lateral paragigantocellular nucleus and the intermediate reticular nuclei Cells in the area postrema... 

Avanzini, G, de Curtis, M, Marescaux, C, Panzica, F, Spriefico, R and Vergnes, M (1992) Role of the thalamic reticular nucleus in the generation of rhythmic thalamo-cortical activities subserving spike and waves. J. Neural Trans. 35 (Suppl) 85-95. 

The slow (deep sleep) -waves probably originate in the eortex beeause they survive separation from, or lesions of, the thalamus. However, the rhythm and appearanee of spindles in earlier phases of the sleep eyele do depend on links with the thalamus (see Steriade 1999). Unlike stimulation of the specific sensory relay nuclei in the thalamus, which only affects neurons in the appropriate sensory areas of the cortex, the nonspecific nuclei can produce responses throughout the cortex and may not only control, but also generate, cortical activity. Certainly, in vitro studies show that neurons of the non-specific reticular thalamic nucleus (NspRTN) can fire spontaneously at about 8-12 Hz (equivalent to EEG a-rhythm) or lower, and that low-frequency stimulation of this area can induce sleep. 

Ascending inputs from the brainstem ascending reticular activating system (ARAS). As described below, these seem to be particularly important and probably disrupt the thalamo-cortical synchrony. 

Figure 22.5 Pathways involved in cortico-thalamic synchrony and EEG arousal. The ascending reticular activating system (ARAS) extends from the cephalic medulla through the pons and midbrain to the thalamus (see Moruzzi and Mayoun 1949). It is activated by impulses in collaterals of the spinothalamic sensory pathway running to specific thalamic nuclei (SpThNc) and in turn activates much of the cortex, partly through the non-specific thalamic nuclei (NspThNc), which also receive inputs from SpThNc and also via the nucleus basalis (NcB). Its stimulation is followed by EEG arousal. It is probable that reciprocal links between cortical areas and the thalamus, particularly NspThN, lead to slow-wave (8 Hz) cortical EEG synchrony and, in the absence of appropriate sensory input and ARAS activity, a sleep state...

It is important to emphasise that a lesion of the reticular system disrupts a number of afferent inputs to the cortex. Particularly important in this respect are the mono-aminergic (especially noradrenaline, 5-HT and histamine) and cholinergic pathways. When the ascending inputs from these neurons are destroyed, sleep is passive and not at all like natural sleep which, as detailed above, has distinct phases and depends on brainstem influences on cortical function. How these different neurotransmitters might influence sleep and arousal will be considered next. 

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