The Role of Siglec-F as a Regulator of Alveolar Macrophage Function and Adaptation

2019 dissertation for MRes. Alveolar macrophages are found in a truly unique microenvironment of the lung alveoli, where they are in close contact with the respiratory epithelium. This close contact with the epithelium is essential as it is how these highly inflammatory cells (cells that respond quickly to immune response as dysregulation of homeostasis exacerbates pathology) are regulated to prevent excessive inflammation, which otherwise would damage the lung, possibly leading to Asthma or COPD. Meaning that in the absence of pathology, the inflammatory response of alveolar macrophages are limited. Interaction with the lung occurs when macrophages bind to the epithelium through a specific receptor such as CD200R and possibly Siglec-F. Siglec-F is a lectin on the surface of macrophages that binds glycoconjugates containing sialic acid on the lung epithelium and on mucins, which is speculated to negatively regulate alveolar macrophages. Though the specific role of Siglec-F as a regulator of macrophage is not fully understood. The aim of this project is to explore changes in gene expression and functional outcomes of signalling through Siglec-F. An exogenous system was used to stimulate this receptor using antibody crosslinking, which is then confirmed by analysing recruitment of SHP-1 in western blot. We also aim to measure differences in cytokine production using a multiplex kit which can simultaneously measure several different cytokines. Lastly, we aim to use RNA sequencing to analyse changes in gene expression. This data will then be used to propose functional outcomes of Siglec-F signalling; improving the understanding of the role of the receptor in negative regulation of alveolar macrophages. The western blot results showed successful recruitment of SHP-1 and thus successful targeting of Siglec-F. We also observed a reduction in proinflammatory cytokines TNF-α, IL-6, CXCL1 and anti-inflammatory cytokine TGF-β1 when crosslinked with Siglec-F in the presence of a known strong stimulator of the innate immune response (LPS). This reduction of cytokines indicates a negative regulatory function of the Siglec-F receptor, though potential functional effector functions of Siglec-F is not understood. Looking at changes in expression we found interesting putative targets of the Siglec-F signalling pathway including immune related genes such as TREM2, Axl, and IL-6 as well as other genes associated with RNA synthesis and the control of protein translation. This study will provide information about the effector functions of Siglec-F and creates new avenues for future study

An Alternative Parameterization of R-matrix Theory

An alternative parameterization of R-matrix theory is presented which is mathematically equivalent to the standard approach, but possesses features which simplify the fitting of experimental data. In particular there are no level shifts and no boundary-condition constants which allows the positions and partial widths of an arbitrary number levels to be easily fixed in an analysis. These alternative parameters can be converted to standard R-matrix parameters by a straightforward matrix diagonalization procedure. In addition it is possible to express the collision matrix directly in terms of the alternative parameters.Comment: 8 pages; accepted for publication in Phys. Rev. C; expanded Sec. IV, added Sec. VI, added Appendix, corrected typo

Shaking a Box of Sand

We present a simple model of a vibrated box of sand, and discuss its dynamics in terms of two parameters reflecting static and dynamic disorder respectively. The fluidised, intermediate and frozen (`glassy') dynamical regimes are extensively probed by analysing the response of the packing fraction to steady, as well as cyclic, shaking, and indicators of the onset of a `glass transition' are analysed. In the `glassy' regime, our model is exactly solvable, and allows for the qualitative description of ageing phenomena in terms of two characteristic lengths; predictions are also made about the influence of grain shape anisotropy on ageing behaviour.Comment: Revised version. To appear in Europhysics Letter

New broad 8Be nuclear resonances

Energies, total and partial widths, and reduced width amplitudes of 8Be resonances up to an excitation energy of 26 MeV are extracted from a coupled channel analysis of experimental data. The presence of an extremely broad J^pi = 2^+ ``intruder'' resonance is confirmed, while a new 1^+ and very broad 4^+ resonance are discovered. A previously known 22 MeV 2^+ resonance is likely resolved into two resonances. The experimental J^pi T = 3^(+)? resonance at 22 MeV is determined to be 3^-0, and the experimental 1^-? (at 19 MeV) and 4^-? resonances to be isospin 0.Comment: 16 pages, LaTe

The 8^8B Neutrino Spectrum

Knowledge of the energy spectrum of $^8$B neutrinos is an important ingredient for interpreting experiments that detect energetic neutrinos from the Sun. The neutrino spectrum deviates from the allowed approximation because of the broad alpha-unstable $^8$Be final state and recoil order corrections to the beta decay. We have measured the total energy of the alpha particles emitted following the beta decay of $^8$B. The measured spectrum is inconsistent with some previous measurements, in particular with a recent experiment of comparable precision. The beta decay strength function for the transition from $^8$B to the accessible excitation energies in $^8$Be is fit to the alpha energy spectrum using the R-matrix approach. Both the positron and neutrino energy spectra, corrected for recoil order effects, are constructed from the strength function. The positron spectrum is in good agreement with a previous direct measurement. The neutrino spectrum disagrees with previous experiments, particularly for neutrino energies above 12 MeV.Comment: 15 pages, 13 figures, 4 tables, submitted to Phys. Rev. C, typos correcte

Characterizing user requirements for future land observing satellites

The objective procedure was developed for identifying probable sensor and mission characteristics for an operational satellite land observing system. Requirements were systematically compiled, quantified and scored by type of use, from surveys of federal, state, local and private communities. Incremental percent increases in expected value of data were estimated for critical system improvements. Comparisons with costs permitted selection of a probable sensor system, from a set of 11 options, with the following characteristics: 30 meter spatial resolution in 5 bands and 15 meters in 1 band, spectral bands nominally at Thematic Mapper (TM) bands 1 through 6 positions, and 2 day data turn around for receipt of imagery. Improvements are suggested for both the form of questions and the procedures for analysis of future surveys in order to provide a more quantitatively precise definition of sensor and mission requirements

Prelaunch absolute radiometric calibration of the reflective bands on the LANDSAT-4 protoflight Thematic Mapper

The results of the absolute radiometric calibration of the LANDSAT 4 thematic mapper, as determined during pre-launch tests with a 122 cm integrating sphere, are presented. Detailed results for the best calibration of the protoflight TM are given, as well as summaries of other tests performed on the sensor. The dynamic range of the TM is within a few per cent of that required in all bands, except bands 1 and 3. Three detectors failed to pass the minimum SNR specified for their respective bands: band 5, channel 3 (dead), band 2, and channels 2 and 4 (noisy or slow response). Estimates of the absolute calibration accuracy for the TM show that the detectors are typically calibrated to 5% absolute error for the reflective bands; 10% full-scale accuracy was specified. Ten tests performed to transfer the detector absolute calibration to the internal calibrator show a 5% range at full scale in the transfer calibration; however, in two cases band 5 showed a 10% and a 7% difference

Prelaunch absolute radiometric calibration of LANDSAT-4 protoflight Thematic Mapper

Results are summarized and analyzed from several prelaunch tests with a 122 cm integrating sphere used as part of the absolute radiometric calibration experiments for the protoflight TM sensor carried on the LANDSAT-4 satellite. The calibration procedure is presented and the radiometric sensitivity of the TM is assessed. The internal calibrator and dynamic range after calibration are considered. Tables show dynamic range after ground processing, spectral radiance to digital number and digital number to spectral radiance values for TM bands 1, 2, 3, 4, 5, 7 and for channel 4 of band 6