The Cytokine response of rat macrophages to lipopolysaccharide is modulated by adrenomedullin

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The role of adrenomedullin in the cardiovascular system

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Adrenomedullin expression and its effects on cytokine response of rat macrophages to lipopolysaccharide

BACKGROUND: Adrenomedullin (AM) is a potent vasorelaxant peptide that plays important roles in inflammation. AM derived from circulating immune cells, such as monocytes and macrophages, is one of the largest sources of AM which arises in the inflammatory process. To assess the functions of AM in inflammation, we studied the temporal changes in AM production and its effect on cytokine response of rat macrophages activated by lipopolysaccharide (LPS). METHOD: Rat macrophages (NR8383) were activated by LPS in the absence and presence of AM at 1 ng/ml to 1 mg/ml. Concentrations of AM, proinflammatory cytokines (TNF-a, IL-1b and IL-6), and macrophage migration inhibitory factor (MIF) in the culture media were measured at 1, 3, 6, and 24 h after LPS/AM stimulation. Total RNA was extracted from the cells and mRNA expression was quantified by RT-PCR. RESULTS: Stimulation of LPS increased AM secretion and AM mRNA expression of the macrophages by 4- to 15-fold at 3–24 h after LPS-stimulation. AM at 1 mg/ml markedly increased IL-6 secretion from both non-stimulated and LPS-stimulated macrophages at 6–24 h, by 1- to 10-fold. AM also increased initial secretion of IL-1b and MIF from both non-stimulated and LPS-stimulated cells at 1–6 h, but it reduced the subsequent production of IL-1b and MIF from LPS-stimulated cells by 10% and 22%, respectively, at 24 h. However, AM reduced production of TNF-a from LPS-stimulated cells at 1–24 h by 35–66%. CONCLUSION: Our results suggest that AM modulates cytokine production and MIF secretion from rat macrophages and its role in the inflammatory process changes with time after onset of the inflammatory challenge

Membrane fouling in an anaerobic membrane bioreactor: Differences in relative abundance of bacterial species in the membrane foulant layer and in suspension

A laboratory anaerobic membrane bioreactors (AnMBRs) (10L volume) was operated at 30°C and fed with artificial sewage containing 30% protein at COD loading rate 5.1kg/m3-d to investigate membrane fouling with two membranes. Biomass attached to the membrane surface and formed a foulant layer on the membrane. The foulant layers from polyvinylidene fluoride ultrafiltration membranes coated with PEBAX (cPVDF) and an uncoated polyetherimide (PEI) ultrafiltration membranes were analyzed and compared to suspended biomass in the reactor, using terminal restriction fragments (T-RFs) of the 16S rRNA gene and a clone library. One species of OP11 bacteria was present at high relative abundance in the foulant layers of both membranes. By contrast, Bacteroidetes and Firmicutes (LGC) species were present at low relative abundance in the foulant layers but high relative abundance in the suspended biomass. Similar differences were observed for other species. The results suggest that some minority species like OP11 play a direct role in fouling by attaching to the membrane surface while others, including some that likely play a major role in the metabolism of influent organics, play a less important or indirect role. In the AnMBR, the EPS was predominately proteinaceous. EPS and microbial cells of the foulant layer contributed to membrane fouling. The results also indicate that fouling of PEI was faster than cPVDF and this reaffirm the importance of the membrane material in fouling. © 2010 Elsevier B.V.link_to_subscribed_fulltex

Increased adrenomedullin expression in lungs in endotoxaemia

The 9th Medical Research Conference, Hong Kong, 7-8 February 200

Increased adrenomedullin expression in lungs in endotoxaemia

Adrenomedullin (AM) is a peptide involved in cardiovascular homeostasis and in inflammation. We examined its expression in a rat model of endotoxaemia. Male Sprague-Dawley rats received intraperitoneal injection of 5 or 10 mg/kg lipopolysaccharide (LPS), or saline as control. Rats were killed at 1, 3, 6, 12 and 24 h after injection. LPS at 5 mg/kg, but not saline, increased plasma AM significantly at 3 h. At 10 mg/kg, plasma AM was raised at 3, 6 and 12 h. Immunoreactive AM concentration in lung increased after 5 or 10 mg/kg LPS, but not saline. PreproAM mRNA level in lung was significantly increased at 3 and 6 h. In conclusion, endotoxin stimulates the expression of AM in the lungs and increases its circulatory concentration. AM may be involved in the systemic response to sepsis. © 2004 Society for Endocrinology.link_to_OA_fulltex

Simultaneous multifunctional sorption of PFOS and Cr(VI) on activated carbon prepared by one-step microwave activation

Multifunctional sorbents, activated carbons (AC), were prepared by one-step microwave activation utilizing peanut shells and sunflower seed husks. The influence of the original particle size of raw materials on the yield and specific surface area of AC was studied, which reached 33.5 % and 1133.27 m(2)/g, respectively. The repetitive and competitive uptakes of perfluorooctane sulfonate (PFOS) and chromium were applied to investigate the sorption properties of AC. The sorption mechanisms were demonstrated using sulfur Kedge X-ray absorption near edge structure analysis (XANES). In the repetitive experiment, AC made from peanut shells (AC(P05)) still retained 70 % removal efficiency of PFOS after the fourth sorption because sorbed PFOS might form a new organic phase that supplied effective sites for the hydrophobic partition of PFOS. However, the removal efficiency of Cr(VI) decreased dramatically from 60 to 11 % after the fourth uptake because electrostatic attraction was its only removal pathway. In the binary solutes system, AC(P05) possessed perfect sorption performance for both PFOS and Cr(VI), which were 885 and 192 mg/g, respectively. In the multivariate solutes system, the XANES spectra indicated that the thiol functional group existed in the resulting AC and a metal chelate was formed between thiol and Zn2+/Cu2+. Hence, the presence of Zn2+/Cu2+ further promoted the removal of PFOS and Cr(VI) through the electrostatic attraction between the anions and positive metal chelate