CTLA-4 Modulates the Differentiation of Inducible Foxp3+ Treg Cells but IL-10 Mediates Their Function in Experimental Autoimmune Encephalomyelitis

In vitro induced Foxp3⁺ T regulatory (iTreg) cells form a novel and promising target for therapeutic tolerance induction. However, the potential of these cells as a target for the treatment of various immune diseases, as well as the factors involved in their development and function, remain debated. Here, we demonstrate in a myelin basic protein (MBP)-specific murine model of CNS autoimmune disease that adoptive transfer of antigen-specific iTreg cells ameliorates disease progression. Moreover, we show that the co-stimulatory molecule CTLA-4 mediates in vitro differentiation of iTreg cells. Finally, we demonstrate that the secreted, immunosuppressive cytokine IL-10 controls the ability of antigen-specific iTreg cells to suppress autoimmune disease. Overall, we conclude that antigen-specific iTreg cells, which depend on various immune regulatory molecules for their differentiation and function, represent a major target for effective immunotherapy of autoimmune disease.     

3D reconstruction techniques of human coronary bifurcations for shear stress computations

Background

Heterogeneity in plaque composition in human coronary artery bifurcations is associated with blood flow induced shear stress. Shear stress is generally determined by combing 3D lumen data and computational fluid dynamics (CFD). We investigated two new procedures to generate 3D lumen reconstructions of coronary artery bifurcations for shear stress computations.

Methods

We imaged 10 patients with multislice computer tomography (MSCT) and intravascular ultrasound (IVUS). The 3D reconstruction of the main branch was based on the fusion of MSCT and IVUS. The proximal part of side branch was reconstructed using IVUS data or MSCT data, resulting in two different reconstructions of the bifurcation region. The distal part of the side branch was based on MSCT data alone. The reconstructed lumen was combined with CFD to determine the shear stress. Low and high shear stress regions were defined and shear stress patterns in the bifurcation regions were investigated.

Results

The 3D coronary bifurcations were successfully generated with both reconstruction procedures. The geometrical features of the bifurcation region for the two reconstruction procedures did not reveal appreciable differences. The shear stress maps showed a qualitative agreement, and the low and high shear stress regions were similar in size and average shear stress values were identical. The low and high shear stress regions showed an overlap of approximately 75%.

Conclusion

Reconstruction of the side branch with MSCT data alone is an adequate technique to study shear stress and wall thickness in the bifurcation region. The reconstruction procedure can be applied to further investigate the effect of shear stress on atherosclerosis in coronary bifurcations.     

QM/MM Molecular Dynamics Study of the Galactopyranose → Galactofuranose Reaction Catalysed by Trypanosoma cruzi UDP-Galactopyranose Mutase

The enzyme UDP-Galactopyranose Mutase (UGM) catalyses the conversion of galactopyranose into galactofuranose. It is known to be critical for the survival and proliferation of several pathogenic agents, both prokaryotic and eukaryotic. Among them is Trypanosoma cruzi, the parasite responsible for Chagas'' disease. Since the enzyme is not present in mammals, it appears as a promising target for the design of drugs to treat this illness. A precise knowledge of the mechanism of the catalysed reaction would be crucial to assist in such design. In this article we present a detailed study of all the putative steps of the mechanism. The study is based on QM/MM free energy calculations along properly selected reaction coordinates, and on the analysis of the main structural changes and interactions taking place at every step. The results are discussed in connection with the experimental evidence and previous theoretical studies.     

Physiological and technological considerations for optimising mass algal cultures

The successful coupling between physiology andtechnology is central to the success of algalbiotechnology. Imperative is a proper understandingof the variables and their impacts on biomass and/orbiocompound production. The crux lies inphotosynthesis and the capturing of light energy atthe optimal rate for eventual maximal photochemistry(biosynthesis). It is in the hands of algalbiotechnologists to understand the dynamics andregulatory mechanisms of especially PSII (photosystemII) activity in order to advance this technologyfurther. Biophysical and technological optimisationand design aimed at maximising photon flux capture aresome of the avenues that needs be pursued. This needsto be augmented by molecular, biochemical andphysiological inputs. Unfortunately detailedsystematic analyses of the variables, theirinteraction and possible synergism have rarely beendone. The debate regarding the merits andproductivity in closed, either plate or tubular,vertical or horizontal, and open pond reactors need tobe resolved. Exciting developments regarding onlinemeasurements and feedback control for optimalproductivities are part of the solutions andapproaches that need to be followed. Multistagesystems that not only utilise autotrophic growth andstress components, but also combinedautotrophic/heterotrophic systems could providesolutions to specific production requirements. Theseand other important issues are addressed in theoverview. The challenges facing algalbiotechnologists and future research needs are also discussed.     

Multi‐proxy analyses of Late Cretaceous coprolites from Germany

A total of 462 coprolites from three localities exposing Upper Cretaceous deposits in the Münster Basin, northwestern Germany, have been subjected to an array of analytical techniques, with the aim of elucidating ancient trophic structures and predator–prey interactions. The phosphatic composition, frequent bone inclusions, size and morphology collectively suggest that most, if not all, coprolites were produced by carnivorous (predatory or scavenging) vertebrates. The bone inclusions further indicate that the coprolite producers preyed principally upon fish. Putative host animals include bony fish, sharks and marine reptiles – all of which have been previously recorded from the Münster Basin. The presence of borings and other traces on several coprolites implies handling by coprophagous organisms. Remains of epibionts are also common, most of which have been identified as the encrusting bivalve Atreta. Palynological analyses of both the coprolites and host rocks reveal a sparse assemblage dominated by typical Late Cretaceous dinoflagellates, and with sub‐ordinate fern spores, conifer pollen grains and angiosperm pollen grains. The dinoflagellate key taxon Exochosphaeridium cenomaniense corroborates a Cenomanian age for the Plenus Marl, from which most studied coprolites derive. The findings of this study highlight the potential of a multi‐proxy approach when it comes to unravelling the origin, composition and importance of coprolites in palaeoecosystem analyses.     

Total synthesis of zervamicin IIB and its deuterium-labelled analogues

For the first time the total synthesis of the peptaibol antibiotic zervamicin IIB is described. Synthesis of this peptaibol was achieved by the Fmoc/tert-butyl strategy in solution using a fragment condensation approach. Three fragments of zervamicin IIB were obtained by stepwise elongation with Fmoc amino acids using BOP as a coupling reagent. For the introduction of the highly sterically hindered α-aminoisobutyric acid residues BOP/DMAP activation was applied. The Fmoc group was removed by reaction with 0.1 M NaOH in dioxane/methanol/water (30/9/1, v/v/v). Peptide fragments were coupled by means of a new coupling reagent, CF₃-PyBOP. Using the strategy developed, zervamicin IIB and two analogues specifically deuterium-labelled at different positions of the glutamine-11 residue have been synthesized in 40% overall yield based on the isotopically labelled amino acid and with 98±2% of isotope enrichment. FAB mass spectroscopy, 600 MHz ¹H-NMR spectroscopy and high-performance liquid chromatography provided convincing evidence that the synthetic products, zervamicin IIB and its deuterium-labelled analogues, fully correspond to the naturally occurring zervamicin IIB. © 1997 European Peptide Society and John Wiley & Sons, Ltd.