Saudi Cultural Missions Theses & Dissertations
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Item Restricted Challenges impacting market access to CGTs and evaluation of the potential strategies(King's College London, 2024) Bogari, Mustafa; Green, NathanaelCell and gene therapies are advanced therapies which offer valuable potentially curative treatments with well-established clinical efficacy and safety. However, there are cases where these advanced therapies have setbacks in market access with some treatments being commercially roadblocked due to challenges. A scoping analysis of literature, stakeholder interviews, and survey data were used to identify and substantiate the critical challenges and potential strategies relating to market access of these therapies. The findings of the three methodologies were compared and combined to signify each challenge and strategy. There were some differences between the findings, but the main trend was that social and economic factors are responsible for the market access setbacks. Several strategies were assessed in their potential to address the market access issues especially in relation to combatting specific challenges. Outcome-based payment plans have been used often to improve market access; however, the high costs still outweigh this plan significantly. Various other strategies have been proposed to enhance market access for CGTs. These include improving manufacturing processes to reduce costs, utilizing conditional approvals to expedite access while gathering further clinical evidence, and encouraging use. The effectiveness of these strategies varies, and their successful implementation often depends on the significance of the specific challenges they act against. Strategies are intended for implementation and further enhancing to eventually minimize market access challenges and facilitate these groundbreaking treatments to the patients in need.11 0Item Restricted A Treatment for Clostridioides difficile Based on Cell Wall Lysins Isolated from C. difficile Specific Bacteriophages(Cardiff University, 2024-04) Alyahya, Khalid Abdullah; Baillie, Les; Heard, Charles; Mehellou, YoucefClostridioides difficile is a Gram-positive, anaerobic, spore-forming bacillus and is a major cause of healthcare-associated infections. While the vegetative form of the pathogen is susceptible to antibiotic treatment, its ability to persist in the gut as antibiotic-resistant spores leads to reinfection in cases where protective microflora is not reestablished. Utilizing recombinant endolysins as treatment of CDI is promising because of their activity against antibiotic and bacteriophage resistant strains. In this study, the recombinantly expressed endolysin LysCD6356 and its enzymically active domain (EAD) were shown to lyse the vegetative forms of a panel of clinical isolates of C. difficile from the UK, including hypervirulent 027 ribotype strains. While these results were promising endolysins, like antibiotics and bacteriophages, endolysins have no effect against the spore form of the pathogen, which is responsible for recurrent infections following successful treatment. To address this issue, a combination of germinants and a bactericidal agent were employed to target the more sensitive form of the pathogen. In this study, exposing of C. difficile spores to germinants followed by endolysin several hours later proved to be the most effective approach suggesting a promising approach to treat relapsing CDI. Additionally, the binding of LysCD6356 and its EAD to the spore and vegetative forms of C. difficile would leave the endolysin ideally placed to target the emerging vegetative cells. This also raise the possibility of developing a diagnostic tool that could be used to detect the pathogen. Bioinformatic studies revealed a significant similarity between LysCD6356 and its EAD to CD27L and CD271-179, respectively, suggesting a possibility of sharing common motifs. However, there was no similarity of LysCD6356 and its EAD with previously published spore binding domains, suggesting the presence of a new spore binding region. An attempt to investigate the binding of endolysins to spore surface proteins, CdeC and CdeM, was unsuccessful possibly due to deficiencies in the experimental approach or the fact that the endolysins recognize other spore surface targets. The combination of our strategy of targeting spores with more traditional approach, such as fecal microbiota transplant, could provide more efficient treatment of relapsing CDI.25 0Item Restricted The Effect of Microbial Bile Acid Metabolism on Clostridium perfringens Virulence(University of Arkansas, 2024-05-11) Alenezi, Tahrir; Sun, XiaolunClostridium perfringens is a predominant intestinal pathogen affecting both humans and animals, including chickens resulting in significant economic losses. In chapter I, I have overviewed the dynamics of the intestinal immune system, the composition of the intestinal microbiome, and how the microbiome influences inflammation in the development of Clostridium infection. The intricate interplay between immunity, microbiota, and their metabolites is likely critical in the pathogenesis of C. perfringens and uncovering these interactions may unveil new avenues for prevention and treatment. The objective of this chapter is to provide updated insights into the role of host-microbe interactions and their potential therapeutic applications in addressing C. perfringens infection. In chapter II, I focused on investigating one of the prominent Clostridium infections of chicken necrotic enteritis (NE), mainly caused by C. perfringens. The classical sign of NE is the foul smell gas in the ballooned small intestine. We hypothesized that deoxycholic acid (DCA) reduces NE by inhibiting C. perfringens virulence signaling pathways. To evaluate the hypothesis, C. perfringens strains CP1 and wild-type (WT) HN13 and its mutants were cultured with different bile acids, including DCA and isoallolithocholic acid (isoalloLCA). Growth, hydrogen sulfide (H2S) production, and virulence gene expression were measured. Notably, isoalloLCA was more potent in reducing growth, H2S production, and virulence gene expression in CP1 and WT HN13 compared to DCA, while other bile acids were less potent compared to DCA. Interestingly, there was a slightly different impact between DCA and isoalloLCA on the growth, H2S production, and virulence gene expression in the three HN13 mutants, suggesting possibly different signaling pathways modulated by the two bile acids. In chapter III, I investigated the effect of deconjugating taurodeoxycholic acids (TDCA) on reducing C. perfringens virulence. Although dietary secondary bile acid DCA reduces chicken NE, the accumulation of conjugated TDCA raised the concerns of its dietary efficacy. In this study, we aimed to deconjugate TDCA by recombinant bile salt hydrolase (BSH) to increase DCA efficacy against NE pathogen C. perfringens. Assays were conducted to evaluate the inhibition of C. perfringens growth, hydrogen sulfide (H2S) production, and virulence gene expression by TDCA and DCA. BSH activity and sequence alignment were conducted to select bsh gene for cloning. The bsh gene from Bifidobacterium longum was PCR-amplified and cloned into plasmids pET-28a (pET-BSH) and pDR111 (pDR-BSH) for expressing BSH protein in E. coli BL21 and Bacillus subtilis 168 (B-sub-BSH), respectively. His-tag purified BSH from BL21 cells was evaluated by SDS-PAGE, Coomassie blue staining, and Western Blot assays. Secretory BSH from B. subtilis was analyzed by Dot-Blot. B-sub-BSH was evaluated for the inhibition of C. perfringens growth. C. perfringens growth reached 7.8 log10 CFU/ml after 24 h culture. C. perfringens growth was at 8 vs. 7.4, 7.8 vs. 2.6, and 6 vs. 0 log10 CFU/ml in 0.2, 0.5, and 1 mM TDCA vs. DCA, respectively. Compared to TDCA, DCA reduced C. perfringens H2S production and virulence gene expression of asrA1, netB, colA, and virT. BSH activity was observed in L. jonsonii and B. longum under anaerobic conditions but not L. jonsonii under 10% CO2. After sequence alignment of bsh from ten bacteria, bsh from B. longum was selected, cloned into pET-BSH, and sequenced at 951 bp. After pET-BSH was transformed in BL21, BSH expression was assessed around 35 kDa using Coomassie staining and verified for His-tag using WB. After subcloned bsh and amylase signal peptide sequence into pDR-BSH, B. subtilis was transformed and named B-sub-BSH. The transformation was evaluated using PCR with B. subtilis around 3 kb and B-sub-BSH around 5 kb. Secretory BSH expressed from B-sub-BSH was determined for His-tag using Dot-Blot. Importantly, C. perfringens growth was reduced greater than 59% log10 CFU/ml in the B-sub-BSH media precultured with 1 vs. 0 mM TDCA. In conclusion, despite the urgent need for antimicrobial free alternatives in agricultural and healthcare industries, few interventions are available. The findings from my research could be used to design new strategies to prevent and treat C. perfringens-induced enteritis or other diseases.12 0Item Restricted The Treatment of Unipolar and Bipolar Depression Today(Saudi Digital Library, 2014) Aljohani, Ahmed Said; Breznoscakova, DagmarDepression is a second major cause of disability worldwide. It divides into two most important types, major depression and bipolar depression. The various American and European guidelines for the treatment include major depression and bipolar disorder providing similar basic treatment principles, which include individualizing the treatment plan, preparing the patient for potential long-term treatment, providing measurement based care, and remission treatment. While the guidelines are all evidence-based, certain factors can influence differences in specific recommendations. The similarities and differences among the three sets of guidelines from Europe and North Americas are reviewed here (American Psychiatry Association, British Association for Psychopharmacology, and Canadian Network for Mood and Anxiety Treatments). The similarity and differences include which psychopharmacology, psychotherapy or other option can be used. Some factors or special situations e.g. pregnancy or older age can affect the choosing of the treatment principle.20 0