Tachykinin-induced increase in gastric mucosal resistance: role of primary afferent neurons, CGRP, and NO.

The tachykinins [Ala5,beta-Ala8]neurokinin A-(4-10) {[Ala5,beta-Ala8]NKA-(4-10)} and NKA-(4-10) dose dependently protected against ethanol-induced gastric mucosal damage in rats (half-maximal inhibitory dose, 46 and 48 nmol/kg, respectively). These effects were abolished by primary afferent nerve denervation, calcitonin gene-related peptide (CGRP) immunoneutralization, the CGRP receptor antagonist human (h) hCGRP-(8-37), and inhibition of nitric oxide (NO) biosynthesis by NG-nitro-L-arginine methyl ester. Tachykinin-induced protection occurred despite marked depression of gastric mucosal blood flow and was not associated with increased acid secretion. NK2-receptor blockade antagonized the protective effects of [Ala5,beta-Ala8]NKA-(4-10) and NKA-(4-10), whereas NK1-receptor blockade was ineffective. Blockade of NK2 but not NK1 receptors prevented by 65% the protection evoked by topical capsaicin without affecting capsaicin-induced hyperemia. We conclude that the increase in gastric mucosal resistance evoked by tachykinins is NK2 receptor-mediated and involves primary afferent neurons, CGRP, and NO. Gastric mucosal hyperemia and increased acid secretion do not participate in the effect. Tachykinins activating NK2 receptors contribute to the increase in gastric mucosal resistance but not the increment in mucosal blood flow after primary afferent nerve stimulation by capsaicin.

The 39-kilodalton protein of Borrelia burgdorferi: a target for bactericidal human monoclonal antibodies.

Three human monoclonal immunoglobulin M antibodies against Borrelia burgdorferi, obtained from in vitro-stimulated peripheral blood lymphocytes, reacted in Western blots (immunoblots) with a prominent 39-kDa peptide and a faint band of approximately 66 kDa. Two of these antibodies showed bactericidal activity without addition of complement. All three antibodies were reactive in an enzyme immunoassay with cloned P39 (W.J. Simpson, M.E. Schrumpf, and T.G. Schwan, J. Clin. Microbiol. 28:1329-1337, 1990), suggesting that the target molecule of these antibodies is identical to the P39 protein. In addition, the majority of supernatants from human lymphocytes stimulated in vitro with crude B. burgdorferi antigen reacted in this assay, demonstrating that P39, although a minor component of B. burgdorferi, is an immunodominant antigen in these spirochetes. A fourth monoclonal antibody, reacting with OspA, also exhibited bactericidal activity.