Epithelial cell specific Raptor is required for initiation of type 2 mucosal immunity in small intestine

AbstractIntestinal tuft cells are one of 4 secretory cell linages in the small intestine and the source of IL-25, a critical initiator of the type 2 immune response to parasite infection. When Raptor, a critical scaffold protein for mammalian target of rapamycin complex 1 (mTORC1), was acutely deleted in intestinal epithelium via Tamoxifen injection in Tritrichomonas muris (Tm) infected mice, tuft cells, IL-25 in epithelium and IL-13 in the mesenchyme were significantly reduced, but Tm burden was not affected. When Tm infected mice were treated with rapamycin, DCLK1 and IL-25 expression in enterocytes and IL-13 expression in mesenchyme were diminished. After massive small bowel resection, tuft cells and Tm were diminished due to the diet used postoperatively. The elimination of Tm and subsequent re-infection of mice with Tm led to type 2 immune response only in WT, but Tm colonization in both WT and Raptor deficient mice. When intestinal organoids were stimulated with IL-4, tuft cells and IL-25 were induced in both WT and Raptor deficient organoids. In summary, our study reveals that enterocyte specific Raptor is required for initiating a type 2 immune response which appears to function through the regulation of mTORC1 activity.</jats:p

Bore collapse and wave run-up on a sandy beach

Wave run-up on beaches and coastal structures is initiated and driven by collapsing incident bores, this process is often considered to define the seaward limit of the swash zone. It is hence a key feature in nearshore wave processes as extreme run-up can lead to structure overtopping and coastal inundation during storm conditions. In addition, the turbulent nature of incident bores and their collapse suspends and advects sediment, resulting in a highly morphologically dynamic swash zone. The cross shore bore collapse location varies from wave to wave and the process is very limited in both spatial and temporal extent, making direct measurement problematic. This paper presents high spatial-temporal resolution LiDAR field measurements of the evolving free-surface in the surf and swash zone which enable the bore collapse detection for 166 waves. These measurements are used to investigate the link between broken wave properties at bore collapse and wave run-up. Incident bores are identified at the seaward boundary of the LiDAR profiles and tracked through the inner surf and swash zones to the run-up limit. It is found that the vertical run-up height exceeds that which would be expected for a perfect conversion of potential to kinetic energy during bore collapse for 24 % of the bores measured. By returning to an existing ballistic-type model to describe the run-up of individual waves, we show that wave run-up can be divided into three components: the bore collapse, terminal bore celerity and their non-linear interaction. For the present dataset, the contribution of the bore collapse and terminal bore celerity is 26 % and 27 % respectively, while non-linear interactions between the two dominates and account for 47% of the measured run-up. By including the terminal bore celerity, the ability to predict run-up is increased by 30 % with the determination coefficient r increasing from 0.573 to 0.785. Likewise, the RMS-error for the wave run-up shows an approximately 10 % reduction from 0.325 to 0.295 m.</p

Bore collapse and wave run-up on a sandy beach

Wave run-up on beaches and coastal structures is initiated and driven by collapsing incident bores, this process is often considered to define the seaward limit of the swash zone. It is hence a key feature in nearshore wave processes as extreme run-up can lead to structure overtopping and coastal inundation during storm conditions. In addition, the turbulent nature of incident bores and their collapse suspends and advects sediment, resulting in a highly morphologically dynamic swash zone. The cross shore bore collapse location varies from wave to wave and the process is very limited in both spatial and temporal extent, making direct measurement problematic. This paper presents high spatial-temporal resolution LiDAR field measurements of the evolving free-surface in the surf and swash zone which enable the bore collapse detection for 166 waves. These measurements are used to investigate the link between broken wave properties at bore collapse and wave run-up. Incident bores are identified at the seaward boundary of the LiDAR profiles and tracked through the inner surf and swash zones to the run-up limit. It is found that the vertical run-up height exceeds that which would be expected for a perfect conversion of potential to kinetic energy during bore collapse for 24% of the bores measured. By returning to an existing ballistic-type model to describe the run-up of individual waves, we show that wave run-up can be divided into three components: the bore collapse, terminal bore celerity and their non-linear interaction. For the present dataset, the contribution of the bore collapse and terminal bore celerity is 26% and 27% respectively, while non-linear interactions between the two dominates and account for 47% of the measured run-up. By including the terminal bore celerity, the ability to predict run-up is increased by 30% with the determination coefficient r increasing from 0.573 to 0.785. Likewise, the RMS-error for the wave run-up shows an approximately 10% reduction from 0.325 to 0.295 m

Safe Positively Invariant Sets for Spacecraft Obstacle Avoidance

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140643/1/1.g000115.pd

Immediate alterations in intestinal oxygen saturation and blood flow after massive small bowel resection as measured by photoacoustic microscopy

Purpose: Massive small bowel resection (SBR) results in villus angiogenesis and a critical adaptation response within the remnant bowel. Previous ex vivo studies of intestinal blood flow after SBR are conflicting. We sought to determine the effect of SBR on intestinal hemodynamics using photoacoustic microscopy, a noninvasive, label-free, high-resolution in vivo hybrid imaging modality. Methods: Photoacoustic microscopy was used to image the intestine microvascular system and measure blood flow and oxygen saturation (SO_2) of the terminal mesenteric arteriole and accompanying vein in C57BL6 mice (n = 7) before and immediately after a 50% proximal SBR. A P value of less than .05 was considered significant. Results: Before SBR, arterial and venous SO_2 were similar. Immediately after SBR, the venous SO_2 decreased with an increase in the oxygen extraction fraction. In addition, the arterial and venous blood flow significantly decreased. Conclusion: Massive SBR results in an immediate reduction in intestinal blood flow and increase in tissue oxygen utilization. These physiologic changes are observed throughout the remnant small intestine. The contribution of these early hemodynamic alterations may contribute to the induction of villus angiogenesis and the pathogenesis of normal intestinal adaptation responses

Up-regulation of hypoxia-inducible factor 1 alpha and hemodynamic responses following massive small bowel resection

Purpose: Massive small bowel resection (SBR) results in an adaptive response within the remnant bowel. We have previously shown an immediate reduction in intestinal blood flow and oxygen saturation (sO_2) after SBR. We therefore sought to determine the duration of resection-induced intestinal hypoxia and expression of hypoxia-inducible factors (HIFs) following SBR. Methods: C57B6 mice were subjected to 50% proximal SBR or a sham procedure. Photoacoustic microscopy (PAM) was used to measure blood flow and sO_2 on postoperative days (PODs) 1, 3, and 7. Ileal tissue was harvested 6 h postoperatively and on PODs 1 and 2, and HIF1α, HIF2α, and VEGF mRNA expression were assessed via RT-PCR. A p value of less than 0.05 was considered significant. Results: Following SBR, reduction in intestinal blood flow persists for 24 h and is followed with hyperemia by POD 3. The immediate reduction in venous sO_2 and increased tissue oxygen utilization continued through POD 7. Enhanced expression of HIF1α was demonstrated 6 h following SBR. Conclusion: Massive SBR results in an immediate relative hypoxic state within the remnant bowel with early enhanced expression of HIF1α. On POD 7, increased tissue oxygen extraction and elevated blood flow persist in the adapting intestine

Improving the photocatalytic reduction of CO2 to CO through immobilisation of a molecular Re catalyst on TiO2.

The photocatalytic activity of phosphonated Re complexes, [Re(2,2'-bipyridine-4,4'-bisphosphonic acid) (CO)3(L)] (ReP; L = 3-picoline or bromide) immobilised on TiO2 nanoparticles is reported. The heterogenised Re catalyst on the semiconductor, ReP-TiO2 hybrid, displays an improvement in CO2 reduction photocatalysis. A high turnover number (TON) of 48 molCO molRe(-1) is observed in DMF with the electron donor triethanolamine at λ>420 nm. ReP-TiO2 compares favourably to previously reported homogeneous systems and is the highest TON reported to date for a CO2-reducing Re photocatalyst under visible light irradiation. Photocatalytic CO2 reduction is even observed with ReP-TiO2 at wavelengths of λ>495 nm. Infrared and X-ray photoelectron spectroscopies confirm that an intact ReP catalyst is present on the TiO2 surface before and during catalysis. Transient absorption spectroscopy suggests that the high activity upon heterogenisation is due to an increase in the lifetime of the immobilised anionic Re intermediate (t50% >1 s for ReP-TiO2 compared with t50% = 60 ms for ReP in solution) and immobilisation might also reduce the formation of inactive Re dimers. This study demonstrates that the activity of a homogeneous photocatalyst can be improved through immobilisation on a metal oxide surface by favourably modifying its photochemical kinetics.Financial support from the EPSRC (EP/H00338X/2 to E.R.; studentship and Doctoral Prize to C.D.W.; DTP scholarship to E.P.), the Christian Doppler Research Association (Austrian Federal Ministry of Science, Research and Economy and the 28 National Foundation for Research, Technology and Development) and the OMV Group (to E.R.), the ERC (project Intersolar to J.D.) and the European Commission Marie Curie CIG (PCIG10-GA-2011-303650 to A.R.) is gratefully acknowledged.This is the final published version. It first appeared in Chemistry - a European Journal, 2015, 21, 3746 – 3754, DOI: 10.1002/chem.20140504

Analysis of the native structure, stability and aggregation of biotinylated human lysozyme.

Fibril formation by mutational variants of human lysozyme is associated with a fatal form of hereditary non-neuropathic systemic amyloidosis. Defining the mechanistic details of lysozyme aggregation is of crucial importance for understanding the origin and progression of this disease and related misfolding conditions. In this study, we show that a biotin moiety can be introduced site-specifically at Lys33 of human lysozyme. We demonstrate, using biophysical techniques, that the structure and stability of the native-state of the protein are not detectably altered by this modification, and that the ability to form amyloid fibrils is unchanged. By taking advantage of biotin-avidin interactions, we show that super-resolution fluorescence microscopy can generate detailed images of the mature fibrils. This methodology can readily enable the introduction of additional probes into the protein, thereby providing the means through which to understand, in detail, the nature of the aggregation process of lysozyme and its variants under a variety of conditions

Application of Lysine-specific Labeling to Detect Transient Interactions Present During Human Lysozyme Amyloid Fibril Formation.

Populating transient and partially unfolded species is a crucial step in the formation and accumulation of amyloid fibrils formed from pathogenic variants of human lysozyme linked with a rare but fatal hereditary systemic amyloidosis. The partially unfolded species possess an unstructured β-domain and C-helix with the rest of the α-domain remaining native-like. Here we use paramagnetic relaxation enhancement (PRE) measured by NMR spectroscopy to study the transient intermolecular interactions between such intermediate species. Nitroxide spin labels, introduced specifically at three individual lysine residues, generate distinct PRE profiles, indicating the presence of intermolecular interactions between residues within the unfolded β-domain. This study describes the applicability to PRE NMR measurements of selective lysine labeling, at different sites within a protein, as an alternative to the introduction of spin labels via engineered cysteine residues. These results reveal the importance of the β-sheet region of lysozyme for initiating self-assembly into amyloid fibrils

Genome-wide association study of primary open-angle glaucoma in continental and admixed African populations.

Primary open angle glaucoma (POAG) is a complex disease with a major genetic contribution. Its prevalence varies greatly among ethnic groups, and is up to five times more frequent in black African populations compared to Europeans. So far, worldwide efforts to elucidate the genetic complexity of POAG in African populations has been limited. We conducted a genome-wide association study in 1113 POAG cases and 1826 controls from Tanzanian, South African and African American study samples. Apart from confirming evidence of association at TXNRD2 (rs16984299; OR[T] 1.20; P = 0.003), we found that a genetic risk score combining the effects of the 15 previously reported POAG loci was significantly associated with POAG in our samples (OR 1.56; 95% CI 1.26-1.93; P = 4.79 × 10-5). By genome-wide association testing we identified a novel candidate locus, rs141186647, harboring EXOC4 (OR[A] 0.48; P = 3.75 × 10-8), a gene transcribing a component of the exocyst complex involved in vesicle transport. The low frequency and high degree of genetic heterogeneity at this region hampered validation of this finding in predominantly West-African replication sets. Our results suggest that established genetic risk factors play a role in African POAG, however, they do not explain the higher disease load. The high heterogeneity within Africans remains a challenge to identify the genetic commonalities for POAG in this ethnicity, and demands studies of extremely large size