Evaluation of the clinical and allergen specific serum immunoglobulin E responses to oral challenge with cornstarch, corn, soy and a soy hydrolysate diet in dogs with spontaneous food allergy.

Fourteen dogs with known clinical hypersensitivity to soy and corn were maintained on a limited antigen duck and rice diet until cutaneous manifestations of pruritus were minimal (78 days). Sequential oral challenges with cornstarch, corn and soy were then performed. Subsequently, the dogs were fed a diet containing hydrolysed soy protein and cornstarch. Throughout the study period the dogs were examined for cutaneous manifestations of pruritus and, additionally, serum was collected for measurement of allergen-specific and total immunoglobulin (Ig)E concentrations. Intradermal testing with food antigens was performed prior to entry into the study and after 83 days. A statistically significant clinical improvement was measured between days 0 and 83. Significant pruritus was induced after oral challenge with cornstarch, corn and soy (P = 0.04, 0.002, 0.01, respectively) but not with the hydrolysed diet (P = 0.5). The positive predictive value of the skin test for soy and corn allergy was reduced after feeding a soy and corn free diet. Although increases in soy and corn-specific serum IgE concentrations were measured in individual dogs post challenge they were not statistically significant and could not be used to predict clinical hypersensitivity.

The in vitro processing of the NGF precursors by the gamma-subunit of the 7S NGF complex.

The in vitro translation of the capped nerve growth factor (NGF) mRNA in wheat germ extracts produced a major 34 kDa NGF precursor with translation starting at the first methionine residue and a minor 29 kDa precursor with translation starting probably at the second methionine. Digestion with the gamma-subunit generated the 22 and 18 kDa intermediates as well as a very small amount of NGF indicating that the gamma-subunit is able to carry out all the processing steps in NGF biosynthesis. The digestion also produced a large amount of a peptide from the N-terminus of the NGF precursors. The discrepancy between the yield of this peptide and of mature NGF emphasizes that inappropriate formation or the lack of formation of disulfide bridges in the NGF precursors, resulting in rapid proteolysis, probably accounts for the low yield of the NGF peptide chains.