Clinical and acquired immunologic responses to West Nile virus infection of domestic chickens (Gallus gallus domesticus).

Numerous bird species are highly susceptible to North American strains of West Nile virus (WNV), and although domestic chickens are relatively resistant to WNV-associated disease, this species currently represents the most practical avian model for immune responses to WNV infection. Knowledge of the immunomodulation of susceptibility to WNV in birds is important for understanding taxonomic differences in infection outcomes. While focusing on immunophenotyping of CD3(+), CD4(+), CD8(+), and CD45(+) lymphocyte subpopulations, we compared lymphocyte subpopulations, blood chemistries, cloacal temperatures, IgM and IgG antibody titers, and differential whole-blood cell counts of WNV-infected and uninfected hens. Total blood calcium and lymphocyte numbers were lower in WNV-infected chickens compared with uninfected chickens. The heterophil-to-lymphocyte ratio increased over time from 2 to 22 d postinoculation (DPI) in uninfected chickens and from 2 to 8 DPI in WNV-infected chickens, although levels declined from 8 to 22 DPI in the latter group. No significant differences were found in the remaining immunological and hematological variables of the WNV-infected and uninfected groups. Our results reaffirm that chickens are resistant to WNV infection, and demonstrated that the heterophil-to-lymphocyte ratio differed between groups, allowing for sorting of infection status. Similar patterns in immune responses over time in both infected and uninfected hens may be related to age (i.e., 10 wk) and associated immune development.

Bradykinin metabolism in the isolated perfused rabbit heart.

BACKGROUND: Bradykinin is a potent cardioprotective hormone, the beneficial role of which in vivo appears to be limited by its rapid metabolism. Inhibitors of peptidases that degrade endogenously formed bradykinin are themselves cardioprotective, presumably by increasing local bradykinin concentrations. As bradykinin-degrading peptidases are potential therapeutic targets, it is important to identify these enzymes in different animal models of cardiac function. OBJECTIVE: To determine the mechanism of bradykinin degradation in the coronary circulation of the rabbit, using an isolated perfused heart preparation. DESIGN AND METHODS: [3H]Bradykinin (16 nmol/l) was perfused as a bolus through the isolated rabbit heart in the presence and absence of specific peptidase inhibitors. The effluent was collected and the radiolabeled metabolites of [3H]bradykinin were separated by high performance liquid chromatography, identified, and quantified. RESULTS: [3H]Bradykinin was metabolized to the extent of 62 +/- 3% in a single passage through the rabbit coronary circulation at a physiological flow rate. The metabolites were identified as [3H]bradykinin(1-5) and [3H]bradykinin(1-7),accounting for 50 +/- 4 and 12 +/- 2% of the radioactivity, respectively. Co-perfusion with the angiotensin converting enzyme inhibitor, ramiprilat, completely blocked formation of these metabolites. CONCLUSIONS: Angiotensin-converting enzyme fully accounts for the metabolism of [3H]bradykinin in the rabbit coronary circulation. This result contrasts with data obtained using rat heart, which demonstrated a prominent role for aminopeptidase P in bradykinin metabolism in this species.

QSAR studies of antiviral agents using molecular similarity analysis and structure-activity maps.

Quantitative structure-activity relationships (QSAR) were developed for nucleoside analogs with anti-HIV activity. These compounds were investigated to determine the correlation of structure and toxicity/activity using molecular similarity analysis and structure-activity maps. A multiple-formula approach was used to perform quantitative molecular similarity analysis (QMSA) and QSAR study. Molecular descriptors such as number of atoms and bonds of a molecule (NAB), maximum common substructure (MaCS), and molecular similarity index (MSI) were used in our structure-activity relationship study. The MaCS of two molecules is defined as the substructure with the greatest NAB value common to both molecules. The MSI of two molecules X and Y is defined as MSI(X,Y) = [MaCS(X,Y)/NAB(X)] x [MaCS(X,Y)/NAB(Y)]. MaCS and MSI quantify the similarity between two molecular structures. Structure-activity maps (structure-toxicity map and structure-antiviral map) and QMSA were used to determine the site and type of modification for reduced toxicity and improved activity of new compounds.