Biological activities anti-secretory

Defining the biochemical mechanisms that couple stimulation at the cell surface to secretion by exocytosis is a major focus in biological research. In the mast cell, the steps by which immunologic secretagogues (for example, specific antigen, anti-IgE antibodies) activate a secretory response have been extensively studied and there are several reviews covering this area [ 12-14, 16, 121, 177],... 

This beneficial effect of fluorination on hydrolytic stability has also been demonstrated with the synthetic prostaglandin SC-46275 (Fig. 70). This compound possesses an anti-secretory activity that protects the stomach mucous membrane. However, its clinical development was too problematic because of the instability of the tertiary allyl alcohol in acidic medium (epimerisation, dehydration, etc.). A fluorine atom was introduced on the C-16 methyl to disfavour the formation of the allylic carbocation. This fluorinated analogue possesses the same biological activity, but does not undergo any degradation or rearrangement, and itepimerises only slowly [165]. 

Interleukin-1 (IL-1) produced by monocytes and several other cell types [70, 146] has a wide array of biological properties, including T cell activation and inflammatory interactions with muscle, liver, fibroblasts, brain and bone [70, 146], IL-1, both natural and recombinant, has been shown to release histamine from human basophils and from human adenoidal mast cells [70,146,151] and this release was abolished by an IL-1 antibody. However, the average release produced by 10 units of IL-1 was less than 20% and there was considerable variability between populations of basophils in the extent of histamine release. Moreover, the secretory response elicited was quite slow (within 15 min) compared with that of other peptides [151]. Desensitization of the basophils by anti-IgE serum had no effect on the subsequent IL-1 response, suggesting different mechanisms of action [ 151], as has been the case with other peptides. Interestingly, the portion of the IL-1 molecule that is responsible for its immu-nostimulatory activity appears to be separate from that portion responsible for its proinflammatory effects [152]. However, that portion of the molecule responsible for eliciting basophil and mast-cell histamine release has not as yet been defined. 

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