Modulation of human dendritic cell activity by Giardia and helminth antigens.

Giardia duodenalis is a common intestinal protozoan parasite known to modulate host immune responses, including dendritic cell (DC) function. Coinfections of intestinal pathogens are common, and thus, DCs may be concurrently exposed to antigens from multiple parasites. Here, we investigated the effects of G. duodenalis products on human monocyte-derived DC function independently and in combination with helminth antigens (Ascaris suum and Trichuris suis). All antigens individually induced an anti-inflammatory phenotype in DCs, reducing lipopolysaccharide (LPS)-induced interleukin (IL)-6, IL-12p70 and tumour necrosis factor (TNF)-α secretion. G. duodenalis and T. suis products also consistently upregulated IL-10 production. Despite a similar modulation of cytokine secretion, additive effects between Giardia and helminth products were not observed, indicating a dominant effect of a single parasite stimulus and limited interactive effects on DC function. G. duodenalis trophozoites induced rapid apoptosis in DCs, which was not observed with the helminth antigens suggesting that the modulatory effects of G. duodenalis may override that of A. suum and T. suis. Thus, G. duodenalis modulates DC activity by modulating cytokine secretion and/or inducing apoptosis, which may be a parasite-driven mechanism to dampen host immunity and establish chronic infections. The differential mechanisms of DC modulation by intestinal parasites warrant further attention.

Stabilization by ethylenediaminetetraacetic acid of amide and other groups in drug compounds.

Ethylenediaminetetraacetic acid (EDTA) was shown to be effective in stabilizing pharmaceutical compounds, which contain acetamido groups, from degradation by light, e.g. paracetamol. Its addition is particularly effective in stabilizing such compounds from the action of ascorbic acid in the light or dark. EDTA was also shown to stabilize lignocaine, sulphadiazine and succinylsulphathiazole. Previous studies had shown that EDTA stabilizes the acetamido group present in two synthetic food colouring compounds.