Aspirin inhibits in vitro maturation and in vivo immunostimulatory function of murine myeloid dendritic cells

Aspirin is the most commonly used analgesic and antiinflammatory agent. In this study, at physiological concentrations, it profoundly inhibited CD40, CD80, CD86, and MHC class II expression on murine, GM-CSF + IL-4 stimulated, bone marrow-derived myeloid dendritic cells (DC). CD11c and MHC class I expression were unaffected. The inhibitory action was dose dependent and was evident at concentrations higher than those necessary to inhibit PG synthesis. Experiments with indomethacin revealed that the effects of aspirin on DC maturation were cyclooxygenase independent. Nuclear extracts of purified, aspirin-treated DC revealed a decreased NF-kappaB DNA-binding activity, whereas Ab supershift analysis indicated that aspirin targeted primarily NF-kappaB p50. Unexpectedly, aspirin promoted the generation of CD11c+ DC, due to apparent suppression of granulocyte development. The morphological and ultrastructural appearance of aspirin-treated cells was consistent with immaturity. Aspirin-treated DC were highly efficient at Ag capture, via both mannose receptor-mediated endocytosis and macropinocytosis. By contrast, they were poor stimulators of naive allogeneic T cell proliferation and induced lower levels of IL-2 in responding T cells. They also exhibited impaired IL-12 expression and did not produce IL-10 after LPS stimulation. Assessment of the in vivo function of aspirin-treated DC, pulsed with the hapten trinitrobenzenesulfonic acid, revealed an inability to induce normal cell-mediated contact hypersensitivity, despite the ability of the cells to migrate to T cell areas of draining lymphoid tissue. These data provide new insight into the immunopharmacology of aspirin and suggest a novel approach to the manipulation of DC for therapeutic application.     

Fundamental Ca2+ signaling mechanisms in mouse dendritic cells: CRAC is the major Ca2+ entry pathway

Although Ca(2+)-signaling processes are thought to underlie many dendritic cell (DC) functions, the Ca(2+) entry pathways are unknown. Therefore, we investigated Ca(2+)-signaling in mouse myeloid DC using Ca(2+) imaging and electrophysiological techniques. Neither Ca(2+) currents nor changes in intracellular Ca(2+) were detected following membrane depolarization, ruling out the presence of functional voltage-dependent Ca(2+) channels. ATP, a purinergic receptor ligand, and 1-4 dihydropyridines, previously suggested to activate a plasma membrane Ca(2+) channel in human myeloid DC, both elicited Ca(2+) rises in murine DC. However, in this study these responses were found to be due to mobilization from intracellular stores rather than by Ca(2+) entry. In contrast, Ca(2+) influx was activated by depletion of intracellular Ca(2+) stores with thapsigargin, or inositol trisphosphate. This Ca(2+) influx was enhanced by membrane hyperpolarization, inhibited by SKF 96365, and exhibited a cation permeability similar to the Ca(2+) release-activated Ca(2+) channel (CRAC) found in T lymphocytes. Furthermore, ATP, a putative DC chemotactic and maturation factor, induced a delayed Ca(2+) entry with a voltage dependence similar to CRAC. Moreover, the level of phenotypic DC maturation was correlated with the extracellular Ca(2+) concentration and enhanced by thapsigargin treatment. These results suggest that CRAC is a major pathway for Ca(2+) entry in mouse myeloid DC and support the proposal that CRAC participates in DC maturation and migration.     

The genetics of complex diseases

Genetic factors influence virtually every human disorder, determining disease susceptibility or resistance and interactions with environmental factors. Our recent successes in the genetic mapping and identification of the molecular basis of mendelian traits have been remarkable. Now, attention is rapidly shifting to more-complex, and more-prevalent, genetic disorders and traits that involve multiple genes and environmental effects, such as cardiovascular disease, diabetes, rheumatoid arthritis and schizophrenia. Rather than being due to specific and relatively rare mutations, complex diseases and traits result principally from genetic variation that is relatively common in the general population. Unfortunately, despite extensive efforts by many groups, only a few genetic regions and genes involved in complex diseases have been identified. Completion of the human genome sequence will be a seminal accomplishment, but it will not provide an immediate solution to the genetics of complex traits.     

EVA dosimetry in manned spacecraft

Extra Vehicular Activity (EVA) will become a large part of the astronaut's work on board the International Space Station (ISS). It is already well known that long duration space missions inside a spacecraft lead to radiation doses which are high enough to be a significant health risk to the crew. The doses received during EVA, however, have not been quantified to the same degree. This paper reviews the space radiation environment and the current dose limits to critical organs. Results of preliminary radiation dosimetry experiments on the external surface of the BION series of satellites indicate that EVA doses will vary considerably due to a number of factors such as EVA suit shielding, temporal fluctuations and spacecraft orbit and shielding. It is concluded that measurement of doses to crew members who engage in EVA should be done on board the spacecraft. An experiment is described which will lead the way to implementing this plan on the ISS. It is expected that results of this experiment will help future crew mitigate the risks of ionising radiation in space.     

First webspace deepening: comparing the four-flap and five-flap Z-plasty. Which gives the most gain?

A two-part investigation was undertaken to determine whether a four- or a five-flap Z-plasty gives the greatest increase in length (deepening) over the same radius of a web. In part A, flaps were designed on a model of a webspace made from a plastic frame and Speedo fabric; four types of flaps, three different central limb lengths, and three trials for each length gave a total of 36 observations. In part B, flaps were designed on the natural axillary webs of the pig; three Yorkshire pigs with one type of flap per axillary web gave a total of 12 observations. In part A, the stereometric elongation (percent deepening) produced by the five-flap Z-plasty was similar to that of a single 60-degree Z-plasty (4-cm central limb; five-flap versus a single Z procedure, 72.5+/-4.3 versus 75.0+/-2.5 percent). The 90-degree four-flap procedure gave a 1.59 times greater deepening than the five-flap procedure (4-cm central limb; 90-degree four flap technique, 114.2+/-1.4 percent). The 120-degree four-flap technique gave 2.0 and 1.26 times greater deepening than the five-flap and 90-degree four-flap procedures, respectively (4-cm central limb; 120-degree four-flap technique, 144.2+/-1.4 percent). In part B, the 90-degree four-flap Z-plasty again produced a significantly greater lengthening (1.57 times) than the five-flap procedure (132.7+/-6.4 versus 84.0+/-4.0 percent; p<0.05), and the percentage of elongation of the 120-degree four-flap procedure was 1.27 times greater than that of the 90-degree four-flap technique (167.3+/-7.0 versus 131.3+/-2.3 percent; p < 0.05). In conclusion, the four-flap Z-plasty produced greater webspace deepening than that of the five-flap Z-plasty. The 120-degree four-flap procedure gave the greatest percentage of elongation, but it was more difficult to design and close than the 90-degree four-flap Z-plasty.     

Saturation transfer difference (STD) 1H-NMR experiments and in silico docking experiments to probe the binding of N-acetylneuraminic acid and derivatives to Vibrio cholerae sialidase

Saturation transfer difference (STD) (1)H NMR experiments were used to probe the epitope binding characteristics of the sialidase [EC 3.2.1.18] from the bacterium Vibrio cholerae, the causative agent of cholera. Binding preferences were investigated for N-acetylneuraminic acid (Neu5Ac, 1), the product of the sialidase catalytic reaction, for the known sialidase inhibitor 5-acetamido-2,6-anhydro-3,5-dideoxy-D-glycero-D-galacto-non-2-enoic acid (Neu5Ac2en, 2), and for the uronic acid-based Neu5Ac2en mimetic iso-propyl 2-acetamido-2,4-dideoxy-alpha-L-threo-hex-4-enopyranosiduronic acid (3), in which the native glycerol side-chain of Neu5Ac2en is replaced with an O-iso-propyl ether. The STD experiments provided evidence, supporting previous studies, that Neu5Ac (1) binds to the sialidase as the alpha-anomer. Docking experiments using DOCK (version 4.0.1) revealed further information regarding the binding characteristics of the enzyme active site in complex with Neu5Ac2en (2) and the Neu5Ac2en mimetic (3), indicating an expected dominant interaction of the acetamide moiety with the protein.