Saudi Cultural Missions Theses & Dissertations
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Item Restricted EVALUATION OF HYDRATION PROTOCOLS FOR HUMAN CORTICAL MINERALIZED PARTICULATE ALLOGRAFTS(Saudi Digital Library, 0025-05-07) Aljowhara, Faraidy; Santana, RonaldoObjective: Bone graft hydration is a critical yet under-explored factor influencing the handling and performance of allograft materials in regenerative procedures. Most manufacturers suggest that biomaterial should be hydrated for at least 30 minutes before use. However, despite widespread clinical use, no standardized hydration protocol exists, and the impact of hydration on the chemical composition, mineralization, and structural integrity of graft materials remains unclear. This study aims to evaluate the physicochemical alterations of mineralized particulate bone grafts following hydration at varying concentrations and time points. Methods: Three commercially available human allograft materials {Straumann Mineralized (SM), Geistlich Mineralized (GM), and Zimmer Mineralized (ZM)} from three different manufacturers, with particle sizes ranging from 250–1000 µm, were examined. The granules were hydrated in 0.9% saline at concentrations of 50 µL and 500 µL and incubated for 1, 10, and 30 minutes. Scanning Electron Microscopy (SEM) was employed to assess hydration-induced structural changes. Chemical composition and molecular alterations were analyzed using Fourier Transform Infrared (FTIR) Spectroscopy and spectral data were processed using second-derivative analysis to improve peak resolution, allowing for the quantification of vibrational bands. Results: SEM analysis revealed no significant differences in surface morphology of the mineralized grafts after hydration. FTIR analysis showed chemical homogeneity across graft materials, with variations in peak intensities reflecting differences in molecular concentrations, mineralization, and collagen integrity. Biomaterial hydration promoted significant selective spectral band increases for all the time points evaluated. Prolonged hydration times did not produce significant or proportional spectral shifts, suggesting a saturation threshold after 1 minute of hydration. Conclusions: Increasing hydration time did not result in significant changes in vibrational bands, suggesting that hydration times longer than 1 minute have minimal impact on the molecular structure of the particulate allografts evaluated.15 0Item Restricted FTIR Imaging with Novel ZnS Hemispheres for Studying Phospholipidosis in Live Macrophages at Subcellular Level(KINGS COLLEGE LONDON, 2024-07) Alshareef, Ohood Ali; Chan, Ka Lung AndrewThe respiratory system plays crucial roles in gas exchange and defence against airborne pathogens. Alveolar macrophages (AMs), vital in this defence within the respiratory tree, undergo morphological and biochemical changes when exposed to xenobiotics, forming lipid vacuoles in their cytoplasm. Pathologists commonly refer to these changes as foamy macrophages (FMs). This response presents challenges for developing new inhaled medicines. In preclinical studies, the presence of FMs in rats can delay development, restrict dosages for clinical evaluation, or even lead to non-approval due to toxicity concerns. While not all formed FMs are recruited to fight infection, they can also be formed as an adaptive (reversible) response. A simple and affordable test to distinguish between adaptive and adverse responses has not been established yet. In addressing this challenge, we investigated if FTIR imaging or microscopy can be used to distinguish these responses by developing and testing the methods against a model utilising the J774A.1 murine macrophage-like cell line. A novel hemispherical-optical substrate device, capable of imaging at the single-cell level while maintaining cell viability and providing high-quality spectra with enhanced spatial resolution, was used. Various phospholipid-inducing drugs, such as amiodarone (an adverse-response inducer), fluticasone (an adaptive-response inducer), and salbutamol (a negative control), were used to demonstrate the developed measurement approach. The demountable liquid-sample holder contains two hemispheres of zinc sulphide with live cells sandwiched between them and a 6-μm spacer to minimise water interference. This configuration allowed for the removal of chromatic aberration and increased the spatial resolution of the measurement to produce spectra with clear and easily analysable hydrocarbon and fingerprint regions that require minimal data processing. Furthermore, the system exhibited the capability to detect changes in the DNA side chain and the carbonyl ester bands at ≈1714 and ≈1745 cm-1, respectively. Subsequently, the system was further developed into a dynamic flow configuration (flow-cell), enabling real-time measurement of subcellular responses to chemical stimuli while preserving cell viability for extended durations. Validation and optimisation of the developed flow-cell were conducted using a standard and a synchrotron-based FTIR imaging microscope (SR-FTIR), acquiring detailed single-cell and subcellular components. The incorporation of a focal plane array detector and SR-FTIR with the novel device was also demonstrated for the first time, providing an improvement in image acquisition time and identification of spectral features. Finally, Raman microspectroscopy was also employed as a complementary method. Both systems, FTIR and Raman, demonstrated the increase in lipid content following treatment with amiodarone and fluticasone, specifically the CH2 asymmetric and symmetric bands and olefinic CH stretching at the high wavenumber region. There were also increases in the carbonyl ester band at ≈1740 cm-1 and the CH2 bending band in the low wavenumber region. Amiodarone presented with clear, drastic changes, whereas fluticasone exhibited similar spectral features but to a lesser extent. The results suggest that FTIR has the potential to become a specific analytical tool, with a low running cost, to distinguish the adaptive and adverse response from macrophages in preclinical drug toxicity screening.9 0