Saudi Cultural Missions Theses & Dissertations
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Item Restricted Comparative Analysis of Organofluorine Mass Balance and Per- and Polyfluoroalkyl Substances in Marine and Terrestrial Environments(Saudi Digital Library, 2023-11-23) Alzbedy, Amnah; Jörg Feldmann, Rainer; Ebe, Gareth NortonAbstract Per- and polyfluoroalkyl substances (PFAS) are a group of anthropogenic pollutants. Several PFAS are highly persistent and associated with various adverse health effects and environmental concerns. In response to these concerns, restrictions have been placed on some legacy compounds, such as perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). Consequently, new PFAS compounds have emerged; however, information on the risk of these compounds to human health and the environment is unknown. In this thesis, combustion ion chromatography (CIC) and high-resolution continuous source-graphite furnace molecular absorption spectrometry (HR-GFMAS) were employed to assess the level of all extractable organic fluorine (EOF) in various tissues of whales stranded in Scotland. A comparison between CIC and HR-GFMAS revealed that both methods give results within one order of magnitude, with CIC consistently slightly lower concentrations. The EOF was then related to the sum of all quantified PFAS, analysed by targeted HPLC-MS/MS analysis. A mass balance study was conducted in the blubber, brain, kidney, liver and muscle of pilot whales aged 1 to 35 years. The findings showed that the majority of the EOF was unidentified in all whale samples. For instance, target analytes were unable to explain more than 80% of the extractable organofluorine (EOF) in brain and blubber samples. Due to the detection of perfluoroalkyl substances (PFAS) in marine environments, further work was conducted to explore the impact of these compounds in other environments; in this case, plant uptake was explored. Plant systems are a potentially importatant route of human exposure to these compounds due to the human consumption of crop plants. As a result, the study of PFAS accumulation in crops provides valuable information, particularly in light of the introduction of new PFAS substitutes that have been promoted as safer alternatives. Research in this area is needed because previous concerns regarding GenX accumulation have been raised. A greenhouse experiment using wheat and rice under different growing conditions was conducted to gain insight into the conditions influencing GenX uptake in plants. Moreover, a mass balance analysis was performed on both sample media to estimate the fractions that could be analysed using targeted LC-MS/MS, thereby improving our understanding of PFAS behaviour in plants. The findings revealed that GenX had the ability to accumulate in both rice and wheat shoots, and under non-flooded rice accumulates higher concentrations of GenX compared growing under flooded conditions. It was found that GenX contributed between 78 to 97% of the extractable organic fluorine in flooded rice shoots. Despite the limitations of organofluorine mass balance analysis, it is vital to recognize and address potential health and environmental risks associated with unidentified organofluorine compounds. Considering the scarcity of naturally occurring organofluorine compounds, this analytical approach is crucial in estimating the overall exposure and impacts of per- and polyfluoroalkyl substances (PFAS).26 0Item Restricted INJECTION OF RAT MESENCHYMAL STEM CELLS LEADS TO HOMING AND DIFFERENTIATION IN THE LIVER IN A BLUNT LIVER TRAUMA MODEL(Saudi Digital Library, 2020-12-02) Alhabboubi, Mostafa; Razek, Tarek; Shum Tim, Dominique; Gao, Zu Ha; Khwaja, Kosar; Khwaja, KosarBackground: The liver heals remarkably after different forms of injuries. However, healing time can be lengthy following high-grade blunt injuries. We hypothesize that injected bone marrow derived mesenchymal stem cells (MSC) could locate and differentiate to hepatocytes after blunt trauma using a rat liver trauma model. Methods: Blunt liver trauma was induced to Lewis rats. MSC were extracted from Lewis rats’ femurs and transfected with LacZ retrovirus so that they express B- galactosidase enzyme, giving their nuclei a blue color on light microscopy. Each rat received a single dose of BMDS (n=6 x 106) within 24 hours of trauma. Through different steps of the experiment, route of injection was the tail vein (TV) in 9 rats, the portal vein (PV) in 19 rats and directly to the injured liver (DI) in 6 rats. Rats were euthanized at 2, 7 days after injection of MSC. Livers were harvested and examined under light microscopy to identify the MSC. Results: Liver sections showed localization and active migration of MSC to trauma sites in the PV group euthanized at 48 hours (3/10 rats). Furthermore, some stem cells differentiated to hepatocytes. Although with fewer cells, similar findings were present in 1/9 rats euthanized at 7 days in the PV group. There was no evidence of MSC localization in TV and DI groups. 4 Conclusions: MSC can locate and differentiate to hepatocytes at blunt trauma site and may contribute to liver regeneration process. Portal vein injection of MSC has emerged as the most effective method of delivery to the liver following trauma among different delivery methods studied. This technique has the potential to become an effective therapeutic strategy to improve liver regeneration after severe blunt trauma. Methods of optimizing homing to injured tissue and evaluation of differentiated stem cell functionality are future areas of research.3 0