Zinc sulfate improved the unbalanced T cell profiles in Der p-allergic asthma: An ex vivo study.

INTRODUCTION: In the pathogenesis of asthma, an imbalance between helper T (Th) 1/Th2 and Th17/Treg cells is believed to play a key role in asthmatic inflammatory responses. Some studies indicated that zinc deficiency increases inflammatory factor production and worsens asthma. However, the effects of zinc on T cell profiles to reduce inflammatory response remain unclear. OBJECTIVES: We investigated the beneficial effects of zinc on isolated cell populations and cytokine levels from patients with asthma. METHODS: Thirty-six individuals Dermatophagoides pteronyssinus (Der p)-allergic and 31 healthy subjects were enrolled in the study, and peripheral blood mononuclear cells (PBMCs) were collected. Harvested PBMCs were stimulated with recombinant Der p antigen in the presence or absence of zinc sulfate (25 µM or 50 µM) for 48 h. Cell surface markers and intracellular cytokine levels were examined by flow cytometry. The pro-inflammatory factors in plasma and culture supernatants were measured by commercial enzyme-linked immunosorbent assay. RESULTS: Zinc sulfate dramatically reduced the proportions of Th2 and Th17 cells, but increased that of Th1 and Treg cells. Zinc sulfate also markedly reduced the levels of interleukin (IL)-4 and IL-17, but increased the levels of IFN-γ. CONCLUSIONS: Zinc ameliorates the imbalance in T cell profiles and could be a potential adjuvant therapy for Der p-induced allergic hypersensitivity.

Production of N-acetyl-D-neuraminic acid using two sequential enzymes overexpressed as double-tagged fusion proteins.

BACKGROUND: Two sequential enzymes in the production of sialic acids, N-acetyl-D-glucosamine 2-epimerase (GlcNAc 2-epimerase) and N-acetyl-D-neuraminic acid aldolase (Neu5Ac aldolase), were overexpressed as double-tagged gene fusions. Both were tagged with glutathione S-transferase (GST) at the N-terminus, but at the C-terminus, one was tagged with five contiguous aspartate residues (5D), and the other with five contiguous arginine residues (5R). RESULTS: Both fusion proteins were overexpressed in Escherichia coli and retained enzymatic activity. The fusions were designed so their surfaces were charged under enzyme reaction conditions, which allowed isolation and immobilization in a single step, through a simple capture with either an anionic or a cationic exchanger (Sepharose Q or Sepharose SP) that electrostatically bound the 5D or 5R tag. The introduction of double tags only marginally altered the affinity of the enzymes for their substrates, and the double-tagged proteins were enzymatically active in both soluble and immobilized forms. Combined use of the fusion proteins led to the production of N-acetyl-D-neuraminic acid (Neu5Ac) from N-acetyl-D-glucosamine (GlcNAc). CONCLUSION: Double-tagged gene fusions were overexpressed to yield two enzymes that perform sequential steps in sialic acid synthesis. The proteins were easily immobilized via ionic tags onto ionic exchange resins and could thus be purified by direct capture from crude protein extracts. The immobilized, double-tagged proteins were effective for one-pot enzymatic production of sialic acid.

Chromatographic characterization of molecularly imprinted polymers.

Recent efforts in the investigation of chromatographic characterization of molecularly imprinted polymers (MIPs) have focused mainly on the nature of heterogeneous binding sites. More data on the thermodynamics than on the kinetic features of MIP columns have been published. The present article addresses the sources of peak broadening and tailing, which are the main drawbacks often associated with imprinted polymers in chromatography for practical applications. With use of the theory of nonlinear chromatography, the peak properties of a MIP column, including the retention and peak broadening and tailing, can be well interpreted. Efforts to improve chromatographic efficiency using MIPs prepared by approaches different from the conventional method, including covalent imprinting and the format of uniformly sized spherical microbeads, are reviewed and discussed. This review leads to the conclusion that nonlinear chromatography theory is useful for characterizing chromatographic features of MIP columns, since a MIP is essentially an affinity-based chromatographic stationary phase. We expect more theoretical and experimental studies on the kinetic aspects of MIP columns, especially the factors influencing the apparent rate constant, as well as the analysis of the influences of mobile-phase composition on the chromatographic performance. In addition to revealing the affinity interaction by molecular recognition, slow nonspecific interactions which may be inherited from the imperfect imprinting and may be involved in the rebinding of the template to MIPs also need to be characterized.