Acinetobacter baumannii is an increasingly common cause of infection in intensive-care units throughout the world, and the occurrence of multiresistant A. baumannii is increasing. The aim of this study was to determine whether a highly purified polyphenol, (-)-epigallocatechin-3-gallate (EGCG), from green tea (Camellia sinesis), had antimicrobial effects against multiresistant clinical isolates of A. baumannii. Standard microplate assays were performed to determine the MIC of EGCG for 21 clinical isolates of A. baumannii. MICs ranged from 0.078 to 0.625 mg/mL, with MIC(50) and MIC(90) of 0.312 mg/mL and 0.625 mg/mL, respectively. All of the isolates of A. baumannii tested were killed by EGCG. In time-kill assays, EGCG resulted in a 3-log reduction in CFU/mL of A. baumannii after 5 h of incubation with the polyphenol. Synergy between the commonly used topical agent 5% mafenide acetate (Sulfamylon) and EGCG was noted for one clinical isolate, and partial synergy was noted for three other isolates. These findings demonstrate that EGCG is an effective bactericidal agent against antibiotic-resistant A. baumannii clinical strains in laboratory settings. EGCG has previously been shown to be safe, and therefore may be an attractive addition for the treatment of cutaneous A. baumannii infections where high concentrations of the drug can be applied to the wound surface.

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Recent publications have demonstrated that human resident and inflammatory monocyte (IM) subpopulations have equivalents in rodents. The effect of thermal injury upon these subpopulations has not been studied. Mice were given a scald burn and killed on postburn days (PBDs) 2, 4, and 8. Bone marrow, blood, and spleen white cells were isolated, and the percentage of resident monocytes (CD11b LY6C), IMs (CD11b LY6C), and monocyte progenitors (macrophage-colony-forming unit [M-CFU]) were determined. The ability of each monocyte population to make TNF-alpha was determined by intracellular cytokine staining. Finally, the ability of sorted fractions from PBD 8 spleen to inhibit lymphocyte proliferation was performed. We noted that there was an increase in M-CFU in the blood and spleen at PBD 8, but the marrow only had a nonsignificant increase in M-CFU. All compartments showed a significant increase in the number of IMs by PBD 8, but no significant changes in resident monocytes were seen. In all compartments, IMs were a major source of TNF-alpha. The postburn increase in IMs and monocyte progenitors in the spleen was accompanied by an increase in the monocyte chemokine monocyte chemoattractant protein 1 and constitutively high levels of the progenitor chemokine stromal-derived factor 1alpha. After burn injury, mice deficient in the receptor for soluble TNF-alpha had equal levels of splenic M-CFU and monocytes, as did wild-type mice, suggesting that this cytokine is not essential for this effect. We conclude that in this model, IMs are a significant source of in vivo TNF-alpha.

Previously, we have shown that statistical synergism between amino acid variants in thyroglobulin (Tg) and specific HLA-DR3 pocket sequence signatures conferred a high risk for autoimmune thyroid disease (AITD). Therefore, we hypothesized that this statistical synergism mirrors a biochemical interaction between Tg peptides and HLA-DR3, which is key to the pathoetiology of AITD. To test this hypothesis, we designed a recombinant HLA-DR3 expression system that was used to express HLA-DR molecules harboring either AITD susceptibility or resistance DR pocket sequences. Next, we biochemically generated the potential Tg peptidic repertoire available to HLA-DR3 by separately treating 20 purified human thyroglobulin samples with cathepsins B, D, or L, lysosomal proteases that are involved in antigen processing and thyroid biology. Sequences of the cathepsingenerated peptides were then determined by matrix-assisted laser desorption ionization time-of-flight-mass spectroscopy, and algorithmic means were employed to identify putative AITD-susceptible HLA-DR3 binders. From four predicted peptides, we identified two novel peptides that bound strongly and specifically to both recombinant AITD-susceptible HLA-DR3 protein and HLA-DR3 molecules expressed on stably transfected cells. Intriguingly, the HLA-DR3-binding peptides we identified had a marked preference for the AITD-susceptibility DR signatures and not to those signatures that were AITD-protective. Structural analyses demonstrated the profound influence that the pocket signatures have on the interaction of HLA-DR molecules with Tg peptides. Our study suggests that interactions between Tg and discrete HLA-DR pocket signatures contribute to the initiation of AITD. The major histocompatibility complex (MHC)3 II molecule is intimately associated with the initiation of autoimmunity. Studies in several MHC II-associated autoimmune conditions, most notably type 1 diabetes, have now convincingly demonstrated that susceptibility to disease is caused by certain structural features of the MHC II peptide binding cleft that influence the display of immunogenic peptides (1-5). Similarly, we have shown that the autoimmune thyroid diseases (AITD), Graves disease (GD) and Hashimoto thyroiditis (HT), are strongly associated with unique HLA-DR peptide binding cleft sequences (6,30). Mechanistically, these pocket amino acid signatures could accommodate autoantigenic peptides derived from any of the thyroid-specific proteins, namely thyroglobulin (Tg), thyroid peroxidase, and thyrotropin receptor. Indeed, there exist data demonstrating that thyroglobulin, which constitutes 80% (8) of total thyroidal protein, is an important thyroidal target and participant in triggering AITD (reviewed in Ref. 9). Along a similar vein of thought, there is mounting evidence that suggests a role for polymorphisms in the thyrotropin receptor, the specific target of Graves disease, in the initiation of Graves hyperthyroidism (28).For the case of thyroid autoimmunity, the connection between MHC II susceptibility...

Heavy metal tungsten alloys have replaced lead and depleted uranium in many munitions applications, due to public perception of these elements as environmentally unsafe. Tungsten materials left in the environment may become bioaccessible as tungstate, which might lead to population exposure through water and soil contamination. Although tungsten had been considered a relatively inert and toxicologically safe material, recent research findings have raised concerns about possible deleterious health effects after acute and chronic exposure to this metal. This investigation describes tissue distribution of tungsten in mice following oral exposure to sodium tungstate. Twenty-four 6-9 weeks-old C57BL/6 laboratory mice were exposed to different oral doses of sodium tungstate (0, 62.5, 125, and 200 mg/kg/d) for 28 days, and after one day, six organs were harvested for trace element analysis with inductively coupled plasma mass spectrometry (ICP-MS). Kidney, liver, colon, bone, brain, and spleen were analyzed by sector-field high-resolution ICP-MS. The results showed increasing tungsten levels in all organs with increased dose of exposure, with the highest concentration found in the bones and the lowest concentration found in brain tissue. Gender differences were noticed only in the spleen (higher concentration of tungsten in female animals), and increasing tungsten levels in this organ were correlated with increased iron levels, something that was not observed for any other organ or either of the two other metals analyzed (nickel and cobalt). These findings confirmed most of what has been published on tungsten tissue distribution; they also showed that the brain is relatively protected from oral exposure. Further studies are necessary to clarify the findings in splenic tissue, focusing on possible immunological effects of tungsten exposure.