Combination of sepsis biomarkers may indicate an invasive fungal infection in haematological patients

Background: Invasive fungal infections are a major threat to a large cohort of immunocompromised patients, including patients with chemotherapy-associated neutropenia. Early differential diagnosis with bacterial infections is often complicated, which leads to a delay in empirical antifungal therapy and increases risk for adverse outcome. Accessibility and performance of specific fungal antigen and PCR-tests are still limited, while sepsis biomarkers are more broadly used in most settings currently.

Methods: Haematological patients hospitalized to receive chemotherapy with proven or probable invasive fungal infection or microbiologically proven bacterial bloodstream infection were included in the study. C-reactive protein was assessed daily during the profound neutropenia period, while procalcitonin or presepsin were measured during the first 48?hours after the onset of febrile episode.

Results: There were totally 64 patients included in the study, 53 with bacterial bloodstream infections and 11 with invasive fungal infections. Combination of CRP >120 with PCT <1.25 or presepsin <170 was shown to be a possible combined biomarker for invasive fungal infections in immunocompromised patients, with areas under the ROC-curves: 0.962 (95% CI 0.868 to 0.995) for PCT-based combination and 0.907 (95% CI 0.692 to 0.990) for presepsin-based combination.     

Expression, processing, and glycosaminoglycan binding activity of the recombinant human 315-kDa hyaluronic acid receptor for endocytosis (HARE)

The hyaluronic acid (HA) receptor for endocytosis (HARE; also designated stabilin-2 and FEEL-2) mediates systemic clearance of glycosaminoglycans from the circulatory and lymphatic systems via coated pit-mediated uptake. HARE is primarily found as two isoforms (315- and 190-kDa) in sinusoidal endothelial cells of the liver, lymph node, and spleen. Here we characterize the ligand specificity and function of the large stably expressed 315-HARE isoform in Flp-In 293 cell lines. Like human spleen sinusoidal endothelial cells, Flp-In 293 cell lines transfected with a single cDNA encoding the full-length 315-HARE express both the 315-kDa and the proteolytically truncated 190-kDa isoforms in a ratio of approximately 3-4:1. The 190-kDa HARE isoform generated from the 315-kDa HARE and the 315-kDa HARE specifically bound 125I-HA. Like the 190-kDa HARE expressed alone (Harris, E. N., Weigel, J. A., and Weigel, P. H. (2004) J. Biol. Chem. 279, 36201-36209), the 190- and 315-kDa HARE isoforms expressed in 315-HARE cell lines were recognized by anti-HARE monoclonal antibodies 30, 154, and 159. All 315-HARE cell lines could endocytose and degrade 125I-HA. Competition studies with live cells indicate that 190-HARE and 315-HARE bind HA with higher apparent affinity (Kd approximately 10-20 nM) than chondroitin sulfate (CS) types A, C, D, or E. Only slight competition of HA endocytosis was observed with CS-B (dermatan sulfate) and chondroitin. Direct binding assays with the 315-HARE ectodomain revealed high affinity HA binding, and lower binding affinities for CS-C, CS-D, and CS-E. A majority of each HARE isoform was intracellular, within the endocytic system, suggesting transient surface residency typical of an active endocytic recycling receptor.     

Identification of a region of troponin I important in signaling cross-bridge-dependent activation of cardiac myofilaments

Force generating strong cross-bridges are required to fully activate cardiac thin filaments, but the molecular signaling mechanism remains unclear. Evidence demonstrating differential extents of cross-bridge-dependent activation of force, especially at acidic pH, in myofilaments in which slow skeletal troponin I (ssTnI) replaced cardiac TnI (cTnI) indicates the significance of a His in ssTnI that is an homologous Ala in cTnI. We compared cross-bridge-dependent activation in myofilaments regulated by cTnI, ssTnI, cTnI(A66H), or ssTnI(H34A). A drop from pH 7.0 to 6.5 induced enhanced cross-bridge-dependent activation in cTnI myofilaments, but depressed activation in cTnI(A66H) myofilaments. This same drop in pH depressed cross-bridge-dependent activation in both ssTnI myofilaments and ssTnI(H34A) myofilaments. Compared with controls, cTnI(A66H) myofilaments were desensitized to Ca(2+), whereas there was no difference in the Ca(2+)-force relationship between ssTnI and ssTnI(H34A) myofilaments. The mutations in cTnI and ssTnI did not affect Ca(2+) dissociation rates from cTnC at pH 7.0 or 6.5. However, at pH 6.5, cTnI(A66H) had lower affinity for cTnT than cTnI. We also probed cross-bridge-dependent activation in myofilaments regulated by cTnI(Q56A). Myofilaments containing cTnI(Q56A) demonstrated cross-bridge-dependent activation that was similar to controls containing cTnI at pH 7.0 and an enhanced cross-bridge-dependent activation at pH 6.5. We conclude that a localized N-terminal region of TnI comprised of amino acids 33-80, which interacts with C-terminal regions of cTnC and cTnT, is of particular significance in transducing signaling of thin filament activation by strong cross-bridges.     

Wilson disease: not just a copper disorder. Analysis of a Wilson disease model demonstrates the link between copper and lipid metabolism

Copper is an essential nutrient required for normal growth and development in many organisms. In humans, the disruption of normal copper absorption and excretion is associated with two severe disorders, known as Menkes disease and Wilson disease, respectively. The consequences of insufficient copper supply that is characteristic of Menkes disease have been largely linked to the inactivation of key metabolic enzymes, although other non-enzymatic processes may also be involved. In contrast, the consequences of copper accumulation in Wilson disease have been generally ascribed to copper-induced radical-mediated damage. Recent studies suggest that the cellular response to copper overload, particularly at the early stages of copper accumulation, involves more specific mechanisms and specific pathways. Genetic and metabolic characterization of animal models of Wilson disease has provided new insights into the pre-symptomatic effects of copper that is accumulated in the liver. The studies have uncovered unexpected links between copper metabolism, cell-cycle machinery, and cholesterol biosynthesis. We discuss these new findings along with the earlier reports on dietary effects of copper. Together these experiments suggest a tight link between lipid and copper metabolism and identify several candidate proteins that may mediate the cross-talk between copper status and lipid metabolism.