C-type lectins L-SIGN and DC-SIGN : Functions in infection and homeostatis

Kooyk, Y. van [Promotor]Geijtenbeek, T.B.H. [Copromotor

Conformal Field Theory and Hyperbolic Geometry

We examine the correspondence between the conformal field theory of boundary operators and two-dimensional hyperbolic geometry. By consideration of domain boundaries in two-dimensional critical systems, and the invariance of the hyperbolic length, we motivate a reformulation of the basic equation of conformal covariance. The scale factors gain a new, physical interpretation. We exhibit a fully factored form for the three-point function. A doubly-infinite discrete series of central charges with limit c=-2 is discovered. A correspondence between the anomalous dimension and the angle of certain hyperbolic figures emerges. Note: email after 12/19: [email protected]: 7 pages (PlainTeX

Wave function multifractality and dephasing at metal-insulator and quantum Hall transitions

We analyze the critical behavior of the dephasing rate induced by short-range electron-electron interaction near an Anderson transition of metal-insulator or quantum Hall type. The corresponding exponent characterizes the scaling of the transition width with temperature. Assuming no spin degeneracy, the critical behavior can be studied by performing the scaling analysis in the vicinity of the non-interacting fixed point, since the latter is stable with respect to the interaction. We combine an analytical treatment (that includes the identification of operators responsible for dephasing in the formalism of the non-linear sigma-model and the corresponding renormalization-group analysis in $2+\epsilon$ dimensions) with numerical simulations on the Chalker-Coddington network model of the quantum Hall transition. Finally, we discuss the current understanding of the Coulomb interaction case and the available experimental data.Comment: 33 pages, 7 figures, elsart styl

The catabolic-to-anabolic shift seen in the canine osteoarthritic cartilage treated with knee joint distraction occurs after the distraction period

Background Cartilage regenerative mechanisms initiated by knee joint distraction (KJD) remain elusive. Animal experiments that are representative for the human osteoarthritic situation and investigate the effects of KJD at consecutive time points could be helpful in this respect but are lacking. This study investigated the effects of KJD on the osteoarthritic joint of dogs on two consecutive timepoints. Methods Osteoarthritis was bilaterally induced for 10 weeks in 12 dogs using the groove model. Subsequently, KJD was applied to the right hindlimb for 8 weeks. The cartilage, subchondral bone and synovial membrane were investigated directly after KJD treatment, and after 10 weeks of follow-up after KJD treatment. Macroscopic and microscopic joint tissue alterations were investigated using the OARSI grading system. Additionally, proteoglycan content and synthesis of the cartilage were assessed biochemically. RT-qPCR analysis was used to explore involved signaling pathways. Results Directly after KJD proteoglycan and collagen type II content were reduced accompanied by decreased proteoglycan synthesis. After 10 weeks of follow-up, proteoglycan and collagen type II content were partly restored and proteoglycan synthesis increased. RT-qPCR analysis of the cartilage suggests involvement of the TGF-β and Notch signalling pathways. Additionally, increased subchondral bone remodelling was found at 10 weeks of follow-up. Conclusion While the catabolic environment in the cartilage is still present directly after KJD, at 10 weeks of follow-up a switch towards a more anabolic joint environment was observed. Further investigation of this timepoint and the pathways involved might elucidate the regenerative mechanisms behind KJD. The Translational Potential of this Article Further elucidation of the regenerative mechanisms behind KJD could improve the existing KJD treatment. Furthermore, these findings could provide input for the discovery or improvement of other joint regenerative treatment strategies

Recognition of the Phanerozoic “Young Granite Gneiss” in the central Yeongnam Massif

Up to now, all the high-grade gneisses of the Korean peninsula have been regarded as Precambrian basement rocks and presence of the Phanerozoic high-grade metamorphic rocks have remained unknown. However, such granite gneiss is discovered through this study from the central Yeongnam massif near Gimcheon. SHRIMP zircon U-Pb age determinations on the granite gneiss, having well-developed gneissic foliations and migmatitic textures, reveal concordant age of ca. 250 Ma indicating the Early Triassic emplacement of this pluton, which is in contradict to the previous belief that it is a Precambrian product. Even though the granite gneiss reveals well-developed gneissic foliations and some zircons show rather low Th/U ratios, the metamorphic age has not been determined successfully. However, the age of metamorphism can be constrained as middle Triassic considering the absence of any evidences of metamorphism from the nearby granitic plutons having emplacement ages of ca. 225 Ma. Early Triassic emplacement and subsequent Middle Triassic metamorphism of the granite gneiss from the Yeongnam massif bear a remarkable resemblance to the case of South China block. We suggest the possibility that Early to Middle Triassic metamorphism of the Korean peninsula might be products of the intracontinental collisional events not directly related with the Early Triassic continental collision event

Molecular richness and biotechnological potential of bacteria cultured from Irciniidae sponges in the north-east Atlantic

Several bioactive compounds originally isolated from marine sponges have been later ascribed or suggested to be synthesized by their symbionts. The cultivation of sponge-associated bacteria provides one possible route to the discovery of these metabolites. Here, we determine the bacterial richness cultured from two irciniid sponge species, Sarcotragus spinosulus and Ircinia variabilis, and ascertain their biotechnological potential. A total of 279 isolates were identified from 13 sponge specimens. These were classified into 17 genera - with Pseudovibrio, Ruegeria and Vibrio as the most dominant - and 3 to 10 putatively new bacterial species. While 16S rRNA gene sequencing identified 29 bacterial phylotypes at the 'species' level (97% sequence similarity), whole-genome BOX-PCR fingerprinting uncovered 155 genotypes, unveiling patterns of specimen-dependent occurrence of prevailing bacterial genomes across sponge individuals. Among the BOX-PCR genotypes recovered, 34% were active against clinically relevant strains, with Vibrio isolates producing the most active antagonistic effect. Several Pseudovibrio genotypes showed the presence of polyketide synthase (PKS) genes, and these were for the first time detected in isolates of the genus Aquimarina (Bacteroidetes). Our results highlight great biotechnological potential and interest for the Irciniidae sponge family and their diversified bacterial genomes.Portuguese Foundation for Science and Technology (FCT) [PTDC/MAR/101431/2008]; FCT [SFRH/BD/60873/2009, SFRH/BPD/62946/2009

Interactions of DC-SIGN with Mac-1 and CEACAM1 regulate contact between dendritic cells and neutrophils

Early during infection neutrophils are the most important immune cells that are involved in killing of pathogenic bacteria and regulation of innate immune responses at the site of infection. It has become clear that neutrophils also modulate adaptive immunity through interactions with dendritic cells (DCs) that are pivotal in the induction of T cell responses. Upon activation, neutrophils release TNF-alpha and induce maturation of DCs that enables these antigen-presenting cells to stimulate T cell proliferation and to induce T helper 1 polarization. DC maturation by neutrophils also requires cellular interactions that are mediated by binding of the DC-specific receptor DC-SIGN to Mac-1 on the neutrophil. Here, we demonstrate that also CEACAM1 is an important ligand for DC-SIGN on neutrophils. Binding of DC-SIGN to both CEACAM1 and Mac-1 is required to establish cellular interactions with neutrophils. DC-SIGN is a C-type lectin that has specificity for Lewis(x), and we show that DC-SIGN mediates binding to CEACAM1 through Lewis(x) moieties that are specifically expressed on CEACAM1 derived from neutrophils. This indicates that glycosylation-driven binding of both Mac-1 and CEACAM1 to DC-SIGN is essential for interactions of neutrophils with DCs and enables neutrophils to modulate T cell responses through interactions with DC