Methionine aminopeptidase (MetAP) carries out an essential posttranslational modification of nascent proteins by removing the initiator methionine and is recognized as a potential target for developing antibacterial, antifungal, and anticancer agents. We have established an Escherichia coli expression system for human type I MetAP (HsMetAP1) and characterized the full length HsMetAP1 and its N-terminal-truncated mutants HsMetAP1(Delta1-66) and HsMetAP1(Delta1-135) for hydrolysis of several thiopeptolide and peptide substrates and inhibition by a series of nonpeptidic inhibitors. Although the N-terminal extension with zinc finger motifs in HsMetAP1 is not required for enzyme activity, it has a significant impact on the interaction of the enzyme with substrates and inhibitors. In hydrolysis of the thiopeptolide substrates, a relaxation of stringent specificity for the terminal methionine was observed in the truncated mutants. However, this relaxation of specificity was not detectable in hydrolysis of tripeptide or tetrapeptide substrates. Several nonpeptidic inhibitors showed potent inhibition of the mutant HsMetAP1(Delta1-66) but exhibited only weak or no inhibition of the full length enzyme. With the recombinant HsMetAP1 available, we have identified several MetAP inhibitors with submicromolar inhibitory potencies against E. coli MetAP (EcMetAP1) that do not affect HsMetAP1. These results have demonstrated the possibility of developing MetAP inhibitors as antibacterial agents with minimum human toxicity. In addition, micromolar inhibitors of HsMetAP1 identified in this study can serve as tools for investigating the functions of HsMetAP1 in physiological and pathological processes.

Monocytes/macrophages, which are found in a variety of organs, maintain tissue homeostasis at a steady state and act as the first line of defence during pathogen-induced inflammation in the host. Most monocyte/macrophage lineage studies in chickens have been largely performed using cell lines, while few studies using primary cells have been conducted. In the present study, the phenotypic and functional characteristics of splenic monocyte/macrophage lineage cells during steady state and inflammatory conditions were examined. Splenic monocyte/macrophage lineage cells could be identified as MRC1 lo MHCII hi and MRC1 hi MHCII lo cells based on their surface expression of MRC1 and MHCII. In the steady state, MRC1 lo MHCII hi cells were more frequently found among MRC1 + cells. MRC1 lo MHCII hi cells expressed a higher number of antigen-presenting molecules (MHCII, MHCI, and CD80) than MRC1 hi MHCII lo cells. In contrast, MRC1 hi MHCII lo cells showed better phagocytic and CCR5-dependent migratory properties than MRC1 lo MHCII hi cells. Furthermore, MRC1 hi MHCII lo cells infiltrated the spleen in vivo and then became MRC1 lo MHCII hi cells. During lipopolysaccharide (LPS)-induced inflammatory conditions that were produced via intraperitoneal (i.p.) injection, the proportion and absolute number of MRC1 hi MHCII lo cells were increased in the spleen. Uniquely, inflammation induced the downregulation of MHCII expression in MRC1 hi MHCII lo cells. The major source of inflammatory cytokines (IL-1β, IL-6, and IL-12) was MRC1 lo MHCII hi cells. Furthermore, MRC1 hi MHCII lo cells showed greater bactericidal activity than MRC1 lo MHCII hi cells during LPS-induced inflammation. Collectively, these results suggest that two subsets of monocyte/macrophage lineage cells exist in the chicken spleen that have functional differences.

Geosynthetic encasement of individual stone columns can provide additional confinement to the columns thus increasing their load capacities and reducing lateral and vertical deformations. Most of past studies have been focused on the load capacities and settlements (i.e. vertical deformations) of the encased stone columns. However, the load transfer mechanism and the lateral bulging deformation pattern of the encased stone columns are not thoroughly understood. In the present study, four series of laboratory model tests in a large-scale testing tank were performed to investigate the effect of geogrid encasement on the lateral and vertical deformations of stone columns installed in a clay bed. For comparison purposes, ordinary stone columns were also tested and evaluated. The main objective of this research is to investigate the lateral and vertical deformation patterns of the encased stone columns and the reinforcement mechanisms of the geogrid encasement with different encasement lengths. In addition, the stress-strain characteristics of the encasement were measured and analysed. The test results show that the ultimate load capacity of the soft soil was greatly increased by the geogrid-encased stone columns. The effective length of the encasement was three to four times of the diameter of stone columns based on the consideration of performance and economy. In comparison with the analytical solution based on the unit cell concept with full encasement of columns, the experimental tests on composite foundations with partially encased columns, which allowed lateral deformations of columns and soils and slippage along the column-soil interfaces (geogrid-soil, stone column-geogrid, and stone column-soil if the column is not encased), resulted in larger settlements, especially at higher vertical pressures.

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