Coronary Heart Disease (CETO) is one of the most common causes of mortality in industrialised societies, and it has been demonstrated elsewhere that shift workers have an increased risk of developing CHD compared to day-workers. One possible explanation for this increased risk is that a shift worker may show inappropriate postprandial responses to a night-time meal, when their biological clock is not adapted to the night shift. This could lead to an elevation in the circulating levels of certain hormones and metabolites, such as triacylglycerol (TAG) and insulin, which are known to be risk factors for CHD. This thesis investigated the relationships between meal times and postprandial hormone and metabolic responses in simulated and real-life shift-workers. The work is presented as three major clinical trials. In the first of these, a combination of timed bright light and darkness/sleep was used to induce a gradual 9-hour phase advance in 12 healthy subjects, who then underwent a rapid 9-hour phase delay. Three meal study days were arranged, to occur during the baseline condition, immediately after the rapid phase delay, so that the subjects effectively had "simulated jet lag", and two days later. Blood parameters measured included plasma glucose, insulin, proinsulin, C-peptide, non-esterified fatty acids (NEFA), TAG and glucose- dependent insulinotropic polypeptide (GIP). Substantial differences in plasma TAG and NEFA were observed in the postprandial responses when the subjects consumed an identical meal immediately after the rapid phase delay, compared with during the baseline conditions. Two days after the rapid phase delay, subjects showed inteimediate hormone and metabolite levels, suggesting that the biological clock had a major effect on these postprandial responses. In the second study, day and night-time postprandial responses were compared in a simulated shift work environment, and the effectiveness of a number of potentially beneficial procedures was investigated. These included alterations to the content of the meal consiraied prior to the night shift, bright light exposure during the night shift, and a daytime rest period prior to the night shift. As in the first study, significant differences were seen in a number of hormones and metabolites on the night shift. compared with during the day. The content of the previous meal, bright light exposure and a daytime rest period prior to the night shift all had significant effects on the night-time postprandial responses. The most exciting discovery made was that a single 8-hour night-time bright light exposure significantly lowered the TAG postprandial responses on the simulated night shift. As all the work conducted up until this point had utilised simulated conditions, it was important to illustrate that similar differences in postprandial responses at night-time could be demonstrated in "real-life shift workers". Thus, nine midwives were recruited from the Royal Surrey County Hospital, and studied on four occasions. This allowed comparison of postprandial responses on both day and night shifts, and also allowed further investigation of the effect of altering the content of the previous meal. Significant differences were again found in a number of blood parameters when the night-time and day-time responses to the test meal were compared, with the most striking being a delayed NEFA rise on the night shift, compared with during the day. In conclusion, this series of studies have illustrated that the human body responds differently to a meal consumed at night-time, compared with during the day, both in a simulated and a real-life environment. This results in variations in the levels of a number of known CHD risk factors, and may be linked with the elevated CHD risk reported in shift workers. Alteration to the meal prior to the night shift, exposure to bright light during the night shift, and instituting a rest period prior to the night shift, were all shown to be potentially beneficial in reducing the variation between day and night-time responses.

Objective: Theoretical and empirical evidence suggests a relationship between Repetitive Thought (RT, e.g. rumination), and depression in patients with Coronary Heart Disease (CHD). To date, cross-sectional studies indicate that rumination is associated with depression in CHD, but additional prospective longitudinal research is required to determine if rumination predicts subsequent depression. This research therefore aimed to test the hypothesis that RT, specifically rumination, is a vulnerability factor for depression over time in a CHD population. It was predicted that RT at baseline would predict depression rates at three month follow-up after controlling for baseline depression and potential confounding factors. Methods: Inpatients and outpatients with a diagnosis of CHD completed self-report questionnaires at baseline (N = 101) and at three month follow-up (N = 85). The data was analysed using a hierarchical multiple regression. Results: Baseline rumination significantly predicted depression at the three month follow-up after controlling for baseline depression and potential confounding factors. Rumination accounted for 8.3% of the variance (p< .001). Subscales of brooding and reflection were also found to be individually predictive of follow-up depression explaining 4% of the variance (p< .005) and 7% of the variance (p< .001) respectively. Conclusion: Findings are consistent with previous prospective and cross-sectional research that indicates that rumination plays a unique role in the maintenance of depression in CHD patients and is an identifiable vulnerability factor.

Introduction There has been much discussion on personalised medicine; however use of genotype in risk prediction for coronary heart disease (CHD) has not resulted in appreciable improvements over non-genetic risk factors. The primary aim was to determine whether candidate single nucleotide polymorphisms (SNPs) identified from genome-wide association studies improved prediction of CHD over conventional risk factors (CRF). The secondary aim was to determine whether the use of apolipoproteins or lipoprotein(a) improved risk prediction of CHD. Methods Analyses used the Edinburgh Heart Disease Prevention Study (EHDPS), with 1592 men aged 30-59 and follow-up after 20 years; and the Edinburgh Artery Study (EAS), with 1592 men and women aged 54-75 and 15 years of follow-up. Candidate SNPs were identified by systematic literature reviews. CHD status was evaluated as severe (myocardial infarction or coronary revascularisation), and any (severe CHD, angina or non-specified ischaemic heart disease). Cox proportional hazards models were used to evaluate addition of candidate SNPs or lipids to models containing CRF. Results A group of genome-wide significant SNPs resulted in a non-significant improvement in C-index for severe CHD (0.038, p=0.082), and a significant improvement in C-index for any CHD (0.042, p=0.016); the associated net reclassification improvements (NRI) were 20.5% and 18.7%, respectively. Regression trees identified SNPs that were predictive of the remaining variance after adjusting for CRF; this resulted in a significant improvement in C-index for any CHD (0.031, p=0.008). The NRI were 11.0% and 9.6% for severe and any CHD, respectively. When compared with HDL cholesterol/total cholesterol, apolipoprotein AI/total cholesterol yielded a NRI of 3.3% for severe CHD. Lipoprotein(a) improved prediction of severe CHD, with a non-significant improvement in C-index (0.020, p=0.087), and NRI of 11.8%. Conclusion The results of this study indicate that a well selected group of candidate SNPs can improve risk prediction for CHD over-and-above CRF. The inclusion of lipoprotein(a), along with CRF, appeared to improve prediction of severe CHD, but not any CHD.

Electrochemical biosensors are renowned for their ability to detect a wide range of analytes in biological fluids for clinical diagnosis. The implementation of biomarkers in electrochemical biosensors for clinical diagnosis is essential for the specific and accurate diagnosis of the disease with high sensitivity and selectivity. Therefore, this thesis evaluates the challenges pertaining to the stability, reproducibility, and obtaining a low limit of detection for the internal/external biomarkers associated with two distinct electrochemical biosensors. The first study tackles the challenge of detecting low analyte concentrations in a label-free biosensor. It introduces an innovative label-free electrochemical biosensing method for the detection of glycosylated hemoglobin (HbA1c) and C-reactive protein (CRP) to predict Coronary Heart Disease (CHD) progression using tailored redox probes, proposing a dual biomarker biosensing platform for future research. Calibration curves reveal an LOD of 5 mg/mL in PBS (8) FeCN (II) and 6 mg/mL in SB for a linear range of 0 – 30 mg/mL of HbA1c. Similarly, an LOD of 0.007 mg/mL and 0.008 mg/mL in PBS (7.4) PcA-NO2 and SB, respectively, is reported for a linear range of 0 – 0.05 mg/mL of CRP. The second study focuses on stabilizing a biomolecule-free sensor for the ultra-low detection of Δ9-tetrahydrocannabinol (THC) in roadside testing. Pre-depositing THC, an external biomarker for drug-impaired driving, onto the biosensor's working electrode enhances its interaction with analytes. However, THC's oxidative nature compromises sensor stability during manufacturing. Consequently, optimal electrode storage conditions were explored, indicating frozen storage as ideal for up to six months, effectively preventing THC oxidation at -18°C, while degradation occurs at 4°C. Modified electrodes stored under optimal conditions exhibit improved calibration curves when exposed to various THC samples. / Thesis / Master of Applied Science (MASc) / An electrochemical biosensor is a sensing device with the ability to detect biological species via the transduction of a specific biological event into electrochemical signals. These sensors are extremely useful for the detection of analytes in biological fluids for clinical diagnostics, to determine the presence or absence of diseases. This manuscript addresses the challenges associated with the stability, reproducibility, and the low limits of detection associated with screen-printed carbon electrodes used in electrochemical biosensing. Subsequently, due to the strong correlation between glycated hemoglobin (HbA1c) and C-reactive protein (CRP) to connote the risk of contracting coronary heart disease (CHD), the manuscript presents a novel label-free electrochemical biosensing method for the detection of HbA1c and CRP with low detection limits. Secondly, the manuscript identifies ambient storage conditions for the long-term stability of a biomolecule-free sensing device for the roadside detection of ultra-low concentrations of Δ9-tetrahydrocannabinol (THC).

The COVID-19 pandemic affected regular health care for patients with chronic diseases. However, the impact of the pandemic on primary care for patients with coronary artery disease (CAD) who are enrolled in a structured disease management program (DMP) in Germany is not clear. We investigated whether the pandemic affected primary care and health outcomes of DMP-CAD patients (n = 750) by using a questionnaire assessing patients’ utilization of medical care, CAD symptoms, as well as health behavior and mental health since March 2020. We found that out of concern about getting infected with COVID-19, 9.1% of the patients did not consult a medical practitioner despite having CAD symptoms. Perceived own influence on infection risk was lower and anxiety was higher in these patients compared to symptomatic CAD patients who consulted a physician. Among the patients who reported chest pain lasting longer than 30 min, one third did not consult a medical practitioner subsequently. These patients were generally more worried about COVID-19. Patients with at least one worsening CAD symptom (chest pain, dyspnea, perspiration, or nausea without apparent reason) since the pandemic showed more depressive symptoms, higher anxiety scores, and were less likely to consult a doctor despite having CAD symptoms out of fear of infection. Our results provide evidence that the majority of patients received sufficient medical care during the COVID-19 pandemic in Germany. However, one in ten patients could be considered particularly at risk for medical undersupply and adverse health outcomes. The perceived infection risk with COVID-19 might have facilitated the decision not to consult a medical doctor.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

This research study examines the manner in which a cardiological sample presents in terms of their psychological make-up by making specific reference to the constructs self-concept and emotions. A literature overview of different aspects of self-concept, emotion and cardiology places the results and discussions of the study within a theoretical background. The study supplies descriptive information relating to the demographic profile of the sample, followed by a description of various aspects of self-concept and emotions, as well as a correlational exploration of the manner in which the sample group presents. The sample consisted of 29 individuals, all who had been diagnosed with coronary heart disease (CHD) and been subjected to surgery as a result thereof. The participants completed a questionnaire, containing two measurement instruments, namely the Adolescent Self-Concept Scale (ASCS) and the Emotions Profile Index (EPI). The scores, obtained by the sample, were subjected to statistical analysis to provide a self-conceptual and emotional profile of the sample. The Spearman Rank-Order Correlation Coefficient was then used to indicate the extent to which the sample tended towards portraying themselves in a positive light, more than they might be experiencing. The study further refers to the views of the sample group, relating to these findings, as obtained from an information and discussion session held with them. The study indicate a significant statistical trend amongst the sample group to portray themselves in a positive light in relation to emotions, even though they were not in reality experiencing such positive emotions. Although the same positive trend was indicated with self-concept, the study cannot conclusively indicate that this is not a realistic presentation of the sample group as a whole. / Dissertation (Counselling Psychology)--University of Pretoria, 2006. / Psychology / unrestricted