College of Medicine and Health - Doctoral Theses
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Item Digitalisation in healthcare: the future of surgical training(University College Cork, 2023) Galvin, Daniel; O'Reilly, Barry A.Introduction The impact of digital technology and artificial intelligence (AI) has a daily impact on our lives. Healthcare as an industry is at the forefront of technological innovation. The application of novel technology to aid performance and enhance training in surgery is key. Challenges in surgical training owing to an increase in trainee numbers, a reduction in working hours, increase in complexity and variety of surgeries performed have become major issues in surgical education. The COVID-19 pandemic further compounded these concerns between 2020 and 2022 where there was significant disruption and reduction in elective surgical activity. Methods Five studies examining the challenges in surgical training in gynaecology and their potential solutions were designed. These comprised of a national cross-sectional trainee and trainer survey on the current challenges of surgical training in gynaecology and in training during the COVID-19 pandemic. Potential solutions examined were a trial of the application of artificial intelligence to the grading of surgical performance and two randomised controlled trails of the application of transcranial direct current stimulation (tDCS) to enhance surgical performance in laparoscopic and robotic surgery. Results Our results showed significant challenges in surgical training over the last decade with a significant reduction in trainee confidence and experience in operative gynaecology. The COVID-19 pandemic had a significant impact on operative volumes of both trainees and trainers. Trainees failed to increase their self-reported confidence in performing common gynaecology procedures over the pandemic period. AI grading of operative performance was shown to be a potential means of enhancing trainee feedback and reducing workload for trainers. tDCS was shown to decrease rates of excessive velocity events during novice laparoscopic training setting it out as a potential solution to maximise training opportunities. tDCS was not shown to enhance robotic surgical performance. Conclusion While the current training environment is challenging in operative gynaecology, potential solutions to augment and accelerate training exist. Further study is required to assess the best means of implementing these solutions to ensure continued access to high quality surgical training.Item Gut-heart axis in a large animal model of metabolic syndrome and heart failure(University College Cork, 2024) Cluzel, Gaston; Caplice, Noel M.; Stanton, Catherine; SFI ManufacturingBackground The metabolic syndrome (MetS) is a pathological condition diagnosed as the combination of obesity with either hypertension, dyslipidaemia, or hyperglycaemia. MetS constitutes a deadly cocktail of cardiovascular risk factors that greatly increases patient mortality. Among the cardiovascular complications of MetS, heart failure with preserved ejection fraction (HFpEF) represents one of the greatest unmet clinical needs of the 21st century. Indeed, as HFpEF prevalence increases along with soaring MetS cases, current therapeutic strategies fail to prevent disease complications. Therefore, novel approaches are required. MetS and HFpEF are accompanied by a low-grade inflammation (LGI) state. LGI is characterised as a steady but lingering increase in circulating inflammatory factors. Inflammatory signalling is known for promoting structural and functional changes in the myocardium that may contribute to HFpEF. Thus, decreasing LGI may reduce HFpEF progression. While the precise origin of LGI is uncertain, the gut microbiome has recently emerged as a hidden organ with critical immune regulatory functions. Crucially, the gut microbiome is tightly connected to the intestinal barrier. In MetS and HFpEF, patients show alteration of the gut microbiome and of the intestinal barrier, a phenomenon called gut permeability. Gut permeability results in the translocation of bacterial antigens from the gut lumen to circulation. Circulating bacterial antigens are pro-inflammatory, that contributes to LGI and, indirectly, to cardiac structural changes and HFpEF. Therefore, therapeutic strategies aimed at the gut microbiome may effectively prevent HFpEF via reducing gut permeability and LGI. This concept is described as the “gut-heart” axis. The gut-heart axis constitutes a novel field of investigation in cardiometabolic disorders and may answer the urgent need for novel therapeutic strategies directed against HFpEF. However, more research is needed to characterise the mechanisms involved in gut-heart signalling. Aims of the project This thesis aimed at characterising the cardiac pathological mechanisms involved in gut-heart signalling, and determining whether they can be modulated by a microbiota-targeted treatment. Methodology In this project, gut-heart axis pathological signalling was characterised using a porcine model of MetS and HFpEF induced by Western diet (WD) and hypertensive corticosteroid salts (desoxycorticosterone acetate, DOCA). Then, to investigate the effects of a gut microbiome-targeted intervention on MetS and HFpEF, this model was supplemented with a synbiotic product combining soluble corn fibre and Lactobacillus mucosae. Inflammatory signalling associated with HFpEF structural changes was investigated in the four cardiac chambers. In particular, the project focused on the roles of tumour necrosis factor (TNF)-α, lipopolysaccharide (LPS) and NOD-like receptor family, pyrin domain containing 3 (NLRP3). These central inflammatory pathways may be key in transducing gut-originating LGI into cardiac pathological signalling in HFpEF. Results Upon WD and DOCA challenge, the porcine model constituted a clinically-relevant reproduction of MetS and HFpEF. MetS was characterised by increased body weight, severe hypertension, hypercholesterolemia, and hypertriglyceridemia. HFpEF was characterised by left atrium enlargement (LAE) and left ventricle hypertrophy (LVH). LAE was associated with tissue apoptosis, and LVH was accompanied by cardiomyocyte hypertrophy. Left atrium (LA) and left ventricle (LV) also had increased inflammatory activity with cardiac macrophage (Mφ) expansion, and activation of TNF receptor 1 (TNFR1), toll-like receptor 4 (TLR4), and NLRP3 pathways. Moreover, the increase in TNFR1, TLR4, and NLRP3 activity was colocalised with cardiac Mφ, microvascular endothelial cells, and cardiomyocytes. While no structural or pressure-induced changes were observed in right heart chambers, the right atrium and the right ventricle also exhibited prominent inflammatory signalling. Data not reported in this thesis indicated that the model exhibited LGI and features of gut permeability. Overall, the porcine model of MetS and HFpEF was characterised by inflammatory cardiac changes along with systemic and intestinal alterations. Synbiotic treatment of MetS pigs reduced LAE, LA cardiomyocyte apoptosis, and LVH, but did not affect MetS core parameters. These improvements in cardiac structural changes were associated with a reduction in cardiac Mφ expansion and in TNFR1, TLR4, and NLRP3 activity in all four cardiac chambers. Reductions in TNFR1, TLR4, and NLRP3 activity were colocalised within the cardiac Mφ, microvascular endothelial cells, and cardiomyocytes populations. Data not reported in this thesis also indicated that synbiotic treatment reduced LGI and gut permeability. Therefore, synbiotic treatment targeted at the gut microbiome reduced pathological signalling along the gut-heart axis, and effectively reduced cardiac structural changes associated with HFpEF. Discussion The porcine model of MetS and HFpEF stood out as a robust model for investigating gut-heart axis inflammatory signalling. The study also highlighted the central role of TNFR1, TLR4, and NLRP3 in driving structural changes in HFpEF through pro-apoptotic and pro-hypertrophic signalling. Crucially, synbiotic treatment targeted at the gut microbiota effectively reduced HFpEF-associated structural changes via reducing cardiac inflammatory signalling. Finally, while exempt of structural changes, the right heart reflected accurately and dynamically the systemic changes in gut-heart axis pathology and treatment. Conclusions Synbiotic targeting of the gut microbiome resulted in cardiac structural improvements in a clinically-relevant porcine model of MetS and HFpEF. This study demonstrates the critical role of gut-heart inflammatory signalling cardiometabolic disease progression.Item Unravelling the impact of early-life nutrition on microbiota-gut-brain axis signalling(University College Cork, 2024) Ratsika, Anna; Cryan, John; Codagnone, Martin; Science Foundation IrelandCurrent lifestyle habits such as aberrant diet are becoming disruptive to our health. Nutrition in early life is a key factor mediating immunity, neurodevelopment, and behavioural outcomes across the lifespan. Optimal nutrition in the first 1000 days of life, starting from preconception to early childhood, are essential for optimal growth, brain and immune system function. Growing lines of evidence suggest that gut microbiota play a role in immune system education, brain function and behaviour. Disruptions in the gut microbiota composition during critical periods of development perinatally might influence the developmental trajectory of the brain and the immune system, with implications for their function later in life. Although the effects of diet-induced microbiota alterations have been studied in the context of brain and immune system development, studies often overlook the interactions between these systems in critical time-windows of developmental opportunity. Given that external influences such as diet could be decisive for brain function there is a growing need for investigation of the effects of early-life nutrition on the microbiota-immune-brain axis during critical windows of development. In this thesis, I focused on the investigation of the influence of microbiota disruptions perinatally via 1. High-fat diet (HFD) during pregnancy and lactation, 2. C-section and 3. Early-life antibiotic administration on offspring brain and immune system development, and behaviour. Using a model of maternal HFD we disrupted the maternal microbiota, which led to increased potent neurotoxic metabolites in maternal circulation. The maternal-diet-induced microbiota disruption and associated metabolic signals had consequences for embryonic brain function and were associated with altered glutamate-related metabolites and genes in the fetal mouse brain and hyperactivity in adolescence specifically in the female offspring. Next, the impact of disruption of vertical microbiota transmission via C-section on the immune system education during weaning was investigated with outputs in the gut, the periphery and at the level of neuroimmune interactions in the juvenile brain. Our data shows that immune system priming in the gut and the periphery is aberrant in response to altered delivery mode, with implications for microglia activation in the male juvenile mouse brain. This highlights the timeframe around weaning as being a critical one for unmasking the enduring effects of early life microbiota disturbances. Lastly, the influence of postnatal early-life dietary intervention with human milk oligosaccharides (HMOs) and prebiotics was investigated on its ability to reverse the effects of antibiotic-induced microbiota depletion on brain transcriptome and behaviour in juvenile male mice. The combination of HMOs with prebiotics led to enhanced social recognition memory and learning and memory pathways in transcriptomic results in social brain areas, possibly via enriched abundance and function of the gut microbiota in male juvenile mice. Taken together, this work provides evidence that the diet and gut microbiota in critical windows of development regulate brain and immune system function. Moreover, we identified that dietary interventions targeting the gut microbiota in early life improve brain function and social behaviour, demonstrating that early-life gut microbiota is important for neurobehavioural outcomes.Item Evaluation of the role of MxA in oesophageal cancer(University College Cork, 2024) Hayes, Robert Michael; McKenna, Sharon L.; O'Donovan, Tracey; Breakthrough Cancer Research; Health Research BoardOesophageal cancer is the seventh most common cancer worldwide and the sixth leading cause of cancer death. The incidence of oesophageal cancer is predicted to increase by 30% by the year 2040, however five-year survival remains at 20% in Ireland. There are two main subtypes, oesophageal squamous cell carcinoma and oesophageal adenocarcinoma. Both are aggressive cancers which frequently develop resistance to chemotherapeutics. Thus, novel therapeutic options are needed. Myxovirus resistance A (MxA) is an interferon inducible antiviral protein that is frequently upregulated in oesophageal cancer. It is currently unknown whether MxA plays a role in the development and progression of oesophageal cancer. We investigated the relationship between MxA expression and the response to chemotherapeutics (5-fluorouracil and oxaliplatin) in oesophageal cancer cell lines. MxA was differentially expressed in five oesophageal cancer cell lines. KYSE450 and KYSE140 cells did not express MxA and were apoptosis incompetent. FLO-1, KYSE270 and OE21 cells expressed MxA and were apoptosis competent. MxA was artificially overexpressed in cell lines without endogenous expression. This increased the resistance of KYSE450 but not KYSE140 cells. Both cell lines remained apoptosis incompetent. MxA expression was depleted in FLO-1 cells using siRNA, and in OE21 cells using CRISPR knockout. Knockdown of MxA significantly increased drug sensitivity and caspase-3 activation in FLO-1 cells. OE21-MX1KO cells were also more drug-sensitive, but caspase-3 activation was reduced. Therefore, these data indicate MxA can influence drug sensitivity, but this is not always related to apoptosis. We examined the impact of MxA on autophagy. Loss of MxA led to significant elevation of basal and drug-induced autophagy in all cell lines. Limited colocalisation was observed between MxA and the autophagosome marker LC3, suggesting MxA’s negative regulatory effect on autophagy is unlikely to involve direct interaction with autophagosomes. MxA was distributed in variably sized, discrete structures which were more numerous and peripherally located following treatment with a proteasome inhibitor or oxaliplatin. We also found that MxA is a significant component of the secretome of oesophageal cancer cells. This secretome included the mitochondrial protein TOM20. MxA knockout diminished the secretion of TOM20 from cells, in conjunction with the autophagy marker LC3. Therefore, we have established that MxA plays a role in the secretion of mitochondria and may act at the intersection between autophagic degradation and export of cellular material in oesophageal cancer cells. We evaluated the effects of MxA knockout on gene expression by RNAseq analysis. 868 genes were differentially expressed, including interconnected networks of genes involved in cell motility, immune/inflammatory signalling, metabolism, and cell differentiation. 59 differentially expressed genes overlapped with genes affected by inhibition of HDAC6, a central mediator of cancer associated pathways. We examined a potential interaction between MxA and HDAC6. Immunofluorescence analysis of OE21 and FLO-1 cells identified colocalisation between MxA and HDAC6 in particulate structures resembling stress granules. Colocalisation was increased in response to treatment with a chemotherapeutic agent or proteasomal inhibitor. Co-immunoprecipitation analysis indicated a specific interaction between MxA and HDAC6. We then compared migration in OE21 and OE21-MX1KO cells. A wound-healing assay demonstrated that migration was significantly reduced in MxA KO cells. Therefore, our data indicates a diverse role for MxA in oesophageal cancer biology. Depletion of MxA expression increased sensitivity to chemotherapeutics. MxA knockout resulted in differential expression of interconnected networks of genes which are associated with cancer progression. MxA negatively regulated autophagy and promoted secretion. A novel interaction between MxA and HDAC6 was identified, which may have significant consequences for the activity of both proteins. Importantly, as depletion of MxA can increase drug sensitivity and reduce migration, targeting this protein may be beneficial for the treatment of oesophageal cancer in future.Item Perceptions of Class II malocclusions(University College Cork, 2024) Brosnan, Sinead; Millett, DeclanAims • To investigate if Oral Health Related Quality of Life (OHRQoL), self-esteem and perception of orthodontic aesthetic treatment need differ in children/adolescents with Class II division 1 malocclusion (II/1M) compared to children/adolescents with Class II division 2 malocclusion (II/2M). • To investigate if perceived OHRQoL, perceived self-esteem and perception of orthodontic aesthetic treatment need differ in parents of children/adolescents with II/1M compared to parents of children/adolescents with II/2M. • To investigate if OHRQoL, self-esteem and perception of orthodontic aesthetic treatment need are associated in children/adolescents and their parents, separately and across II/1M and II/2M groups. • To investigate if family impact differs for children/adolescents with II/1M compared to those with II/2M. Materials and Methods Following ethical approval, 240 individuals were invited to participate, 120 children/adolescents aged 10-16-years (60 with II/1M and 60 with II/2M) and 120 parents. Subjects were recruited from treatment waiting lists in a publicly funded orthodontic service. Informed consent/assent was obtained from each child/adolescent and their parent. Children/adolescents completed a generic (Child Oral Health Impact Profile, COHIP) and a condition-specific questionnaire (Malocclusion Impact Questionnaire, MIQ) to assess OHRQoL, a self-esteem questionnaire (Child Health Questionnaire- Self-Esteem component, CHQ-SE) and self-assessed orthodontic aesthetic treatment need (Index of Orthodontic Treatment Need- Aesthetic Component, IOTN-AC). A parent of each child/adolescent completed the parent version of COHIP, assessed the family impact of their child’s oral health (Family Impact Scale, FIS), completed the parent version of CHQ-SE and rated their child’s orthodontic aesthetic treatment need (IOTN-AC). Demographic and clinical variables were also recorded for each child/adolescent which included age, child/parent gender, socioeconomic status (SES), caries, dental trauma, overjet, overbite, severity of crowding, as well as IOTN both dental health and aesthetic components. ANOVA was used to investigate associations of OHRQoL, family impact and self-esteem between II/1M and II/2M groups. Perceived orthodontic aesthetic treatment need was compared between II/1M and II/2M groups using ordinal logistic regression models. P < 0.05 was considered as statistically significant. Results In children/adolescents OHRQoL, self-esteem and perception of orthodontic aesthetic treatment need did not differ significantly between malocclusion groups (MIQ p = 0.1480; COHIP p = 0.8067; CHQ-SE p = 0.9505; Child IOTN-AC p = 0.8987). There was also no significant difference in parent-reported OHRQoL, self-esteem or perception of orthodontic aesthetic treatment need or their child between malocclusion groups (Parent COHIP p = 0.2361; Parent CHQ-SE p = 0.9161; Parent IOTN-AC p = 0.3191). Comparing child/adolescents versus parents for each malocclusion, there was no significant difference in OHRQoL (II/1M p = 0.3110; II/2M p = 0.2317), self-esteem (II/1M p = 0.5585; II/2M p = 0.5) or perceived orthodontic aesthetic treatment need (II/1M p = 0.0645; II/2M p = 0.4050). Furthermore, there was no significant difference in family impact for children/adolescents with II/1M compared to those with II/2M (p = 0.3480). Increased age and female gender had a significantly negative impact on child-reported OHRQoL (p = 0.0001 and p < 0.0001, respectively) and self-esteem (p < 0.0001 and p = 0.0016, respectively), while female parent gender and SES i.e. those without medical cards, negatively influenced parent-reported OHRQoL (p = 0.0014 and p = 0.0450, respectively). SES influenced parent-reported self-esteem of their child (p = 0.0125), whereby those with medical cards reported worse self-esteem, while caries experience negatively influenced family impact (p = 0.0295). Younger age and having a medical card had a significantly negative impact on child reported perceived orthodontic aesthetic treatment need (p = 0.0365 and p = 0.0174, respectively). Child and parent perceived orthodontic aesthetic treatment need were significantly lower than clinician-reported (p < 0.05). Conclusions • There were no significant differences between II/1M and II/2M in relation to child-reported or parent-reported OHRQoL, self-esteem, perception of orthodontic aesthetic treatment need or family impact. • For each malocclusion, there were no significant difference between child/adolescent versus parent for all measures recorded. • Other variables, however, were found to impact perceptions, such as age, gender and SES. Increased age and female gender negatively impacted child-reported OHRQoL and self-esteem. Female parents and parents without medical cards reported worse OHRQoL for their child, while parents with medical cards reported worse self-esteem for their child. • Clinician-reported perceived orthodontic aesthetic treatment need was more severe than parent and child perceptions, regardless of malocclusion type.