Induction sites

The main site of the mucosal immune system in the gut is referred to as gut-associated lymphoid tissue (GALT), which can be divided into inductive and effector sites. In the small intestine, the inductive sites are in the Peyer s patches, which consist of large lymphoid follicles in the terminal small intestine. The contact with external antibodies triggers a series of cascade events in the body based on immune response (Brandtzaeg et al., 1999). 

Modified Buehler. Buehler (1964) developed the first test system to use an occlusive patch to maximize dermal exposure and to increase the test sensitivity (Buehler, 1964). Although, this assay is still insensitive for some xenobiotics that may not sufficiently traverse the epidermis, it is particularly useful for compounds that are either highly irritating by intradermal injection or cannot be dissolved or suspended in a form that is conducive to injection. Other advantages are that the test produces few false positives, rarely overpredicts the potency of sensitizers, and is less likely to produce limiting system toxicity or ulceration at the induction sites. Figure 15.4 shows the test design in its current (OECD) form. 

These MALT are structurally and functionally divided into two sites - the inductive sites for antigen uptake and processing on the one hand, and the effector sites engaging lymphocytes/plasma cells, granulocytes and mast cells, on the other hand. 

Nevertheless, there is also accumulating evidence that a certain regionalization exists in the mucosal immune system, in particular a dichotomy between the gut and the upper respiratory tract. Differences in the antigenic repertoire, adhesion molecules or chemokines involved in leukocyte extravasation might explain this disparity. Primed immune cells may tend to home to the effector sites corresponding to the inductive sites, where the initial antigen contact took place. Such regionalization within the common mucosal immune system has to be taken into account in the development of certain mucosal vaccines [11]. 

A wide variety of novel approaches for the development of mucosal immune responses by administration of antigens in different delivery systems have been investigated, in many cases, with considerable success. These approaches include (1) the coadministration of immunogens with adjuvants active at the mucosal surface, (2) the coupling of immunogens to carrier molecules that promote their uptake at the mucosal inductive site, and (3) the expression of antigens in live attenuated bacterial or viral vectors, which can promote the colonization of mucosal tissue and the incorporation of antigens into a variety of microparticulate and adhesive vehicles, which are taken up in mucosal inductive sites. 

Recently, it has been reported that the expression of transient receptor potential vanilloid-1 (TRPV-1) is enhanced in airway nerves of patients with chronic cough (Groneberg et al. 2004). In addition to TRPV-1, acid-sensing ion channels are localized in A5-fibers of guinea pigs (Gu 2006). Therefore, differences in codeine sensitivity of acid-induced coughs may depend on the pH of the cough induction site. Further studies are needed to clarify such differences. 

Fig. 7 The effective charge densities for the water (dashed), permanent charges (dotted), and surfactant induction sites (dot-dashed) for the FP model. The total effective charge density is given by the solid line...

It is important that the contractor s workers are familiar with the procedrrres applying to a particular site for items such as lock-out and tag-out, other permit systems and emergency response. So even if there is cotmnon indrrstry-wide induction, site induction training on specific issues should supplement this, ensrrring it is a good fit to the basic industry-wide induction. 

As described above (see section on Polarizability), fluctuating charges represent another type of model that can yield self-consistent results for the electrostatic moments of a molecule. Here the idea is to replace induction sites with some sort of movable or fluctuating charge distribution that responds to the field of the other molecules.Many variants of this approach have been reported, several of which we comment on. 

The greater positive character hence the increased acidity of the O—H proton of 2 2 2 tnfluoroethanol can be seen m the electrostatic potential maps displayed m Figure 1 8 Structural effects such as this that are transmitted through bonds are called indue tive effects A substituent induces a polarization m the bonds between it and some remote site A similar inductive effect is evident when comparing acetic acid and its trifluoro derivative Trifluoroacetic acid is more than 4 units stronger than acetic acid... 

Inductive effects depend on the electronegativity of the substituent and the num ber of bonds between it and the affected site As the number of bonds increases the inductive effect decreases... 

Closely related to the inductive effect and operating in the same direction is the field effect In the field effect the electronegativity of a substituent is communicated not by successive polarization of bonds but via the medium usually the solvent A substituent m a molecule polarizes surrounding solvent molecules and this polarization is transmit ted through other solvent molecules to the remote site... 

Pig. 3. Representation of promoter sites on the pro-enkephalin gene. The numbers represent the distance in nucleotides from the pro-enkephalin initiation codon the arrow indicates the direction of transcription. The TATA promoter box occurs immediately before the pro-enkephalin initiation site the AP-2 site, which binds immediate-early gene products, is 70 nucleotides upstream, and the CRE site, which binds a regulatory protein involved in cAMP induction of mRNA synthesis, is 107 nucleotides upstream from the initiation codon. The expanded section shows that the CRE site actually consists of two elements, ENKCRE-1 and ENKCRE-2, which separately confer cAMP sensitivity to pro-enkephalin mRNA synthesis. 

The free radicals initially formed are neutralized by the quinone stabilizers, temporarily delaying the cross-linking reaction between the styrene and the fumarate sites in the polyester polymer. This temporary induction period between catalysis and the change to a semisoHd gelatinous mass is referred to as gelation time and can be controUed precisely between 1—60 min by varying stabilizer and catalyst levels. 

The onset of action is fast (within 60 seconds) for the intravenous anesthetic agents and somewhat slower for inhalation and local anesthetics. The induction time for inhalation agents is a function of the equiUbrium estabUshed between the alveolar concentration relative to the inspired concentration of the gas. Onset of anesthesia can be enhanced by increasing the inspired concentration to approximately twice the desired alveolar concentration, then reducing the concentration once induction is achieved (3). The onset of local anesthetic action is influenced by the site, route, dosage (volume and concentration), and pH at the injection site. 

There is some evidence for chemically mediated endocrine disruption in amphibians. The egg yolk protein, vitellogenin, is inducible in amphibians by exposure to DDT. " Males of the short clawed toad Xenopus laevis given 250 fig/g or 1 fig/g o,p -DDT for seven days have been shown to produce vitellogenin, although the induction was less than that achieved by treatment with 1 fig/g of either 17/1-oestradiol or diethylstilboestrol. Research has also shown that endocrine disrupting chemicals can alter sex ratios in wild populations of certain species PCB congeners and organochlorine compounds have been linked with male domination of sex ratios in polluted compared to unpolluted sites. ... 

Induction generator This is a standard squirrel cage motor with additional treatment to weather the site conditions. The normal specifications are generally the same as for a standard motor. The permissible voltage and frequency variations are, however, wider as noted below ... 

The interactions may be physicochemical without the participation of biological mechanisms for example, deep lung exposure to highly soluble irritative gases, such as sulfur dioxide, may become enhanced due to adsorption of the gas onto fine particles. Biological interactions may occur at all stages and body sites. For example, toxicity is increased when adverse effects are due to some reactive metabolic intermediate and exposure to another agent stimulates its metabolic activation (enzyme induction). 

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