No description available.

The use of exercise is a valuable tool in the healthcare management of young patients with chronic chest diseases (CCD). Indeed, exercise testing yields important prognostic data which are a strong predictor of survival. Such information can indicate to the clinician to increase drug therapy treatment, and functional capacity of the patient can be monitored over time with repeated testing. Exercise training has been shown to improve both aerobic and anaerobic fitness and quality of life in patients with lung disease. The use of exercise testing and training in the healthcare of patients with lung disease in the UK, however, has not been investigated. In order for recommendations for exercise testing and training based on scientific evidence to be implemented, they should relate to current standards and resources. Therefore, the first study of the present thesis sought to characterise the use of both exercise testing and training in UK Cystic fibrosis (CF) clinics through a nationwide audit. Data from the audit showed that exercise testing and training are underused despite recognition of the importance of each in the healthcare of the patient by clinicians and other healthcare providers. Indeed, resources for exercise testing in UK CF clinics are limited. A patient over the age of 8 y will only have a 41.1 % chance of receiving an exercise test of any type over a 12 month period, and the exercise test will be quite crude. Exercise training is frequently discussed with the patient; however, there is a strong likelihood (72.9 %) that the advice given will only be general encouragement. The prognostic value of exercise testing is becoming increasingly recognised. Indeed, peak oxygen uptake (VO2peak) derived through maximal cardiopulmonary exercise testing (CPET) has been reported to be equal or superior to that of resting spirometric lung function tests in the prognostic evaluation of patients with CCD. Furthermore, a high correlation between VO2peak and long term survival in both adults and children with CF has been reported. Other physiological data from CPET, such as oxygen uptake (VO2) recovery following CPET, has not been investigated in young patients with CCD and may provide an additional physiological marker of patient health. The aim of study two, therefore, was to investigate recovery following CPET in young patients with CCD, and determine if any significant relationships exist between VO2 recovery and measures of disease severity in these patients. Data from study two showed that young patients with CCD compared to healthy controls had significantly reduced aerobic fitness (t52 = - 2.64, P = 0.011), and the fast component of the VO2 recovery following CPET, analysed by a mono-exponential model, is significantly prolonged (t52 = 2.63, P = 0.011). Furthermore, the fast component of the VO2 recovery is significantly related to disease severity, as assessed by the Shwachman score (SS), in the CF subgroup (r = - 0.75, P < 0.001), and as assessed by forced expiratory volume in 1 s (FEV1), in the young patients with CCD (r = - 0.49, P = 0.009). Thus, indicating that greater disease severity is associated with a longer VO2 recovery following CPET. A significant relationship between VO2peak and VO2 recovery was shown in the young patients with CCD (r = - 0.45, P = 0.018). Although the relationship is significant, however, it is still quite weak, and, therefore, indicates that the VO2 recovery is not closely related to the VO2peak in these patients. Quality of life and likelihood of survival are greater in patients with CCD with higher levels of aerobic fitness, and regular exercise has been shown to improve both lung function and exercise capacity in these patients. Indeed, exercise training programmes tailored to the individual patient are recommended in the standards of patient healthcare in the UK. Whilst the chronic effects of regular exercise have been investigated, the acute physiological responses to exercise training have not been studied in young patients with CCD. In study three young patients with CCD and healthy controls performed intermittent exercise (IE) designed to replicate the typical activity and exercise patterns of young people. Following IE, in the healthy controls the VO2 required to sustain moderate steady-state exercise fell significantly from 3 min to 1 h and 1 h to 24 h, however, in the young patients with CCD VO2 during moderate steady-state exercise increased significantly from 3 min to 1 h and then decreased significantly from 1 h to 24 h (main effect for time: F1.5,79.2 = 22.82, P < 0.001). A significant time × group interaction between young patients with CCD and controls in VO2 during moderate steady-state exercise 3 min, 1 h and 24 h following IE (interaction: F1.5,79.4 = 30.01, P < 0.001) may suggest that metabolic stress is still evident over this time period, which may be indicative of fatigue. Data from the present thesis shows that exercise is underused in UK CF clinics, with the availability of equipment and personnel both being limiting factors. Furthermore, a lack of standardisation in the provision of exercise between clinics is evident. In studies two and three, data shows different physiological responses following CPET and IE, respectively, between children with CCD and controls. The present thesis has advanced our understanding of the provision of exercise in the healthcare of CF in the UK, and furthered knowledge in how young patients with CCD respond physiologically to exercise.

Dyskeratosis congenita (DC) is a multi system disorder that exhibits considerable clinical and genetic heterogeneity. It is characterised by mucocutaneous features, bone marrow failure and a predisposition to cancer. Research has identified mutations affecting several telomerase components and patients often have short telomeres, implicating defective telomere maintenance in this disease. Affected components include dyskerin, NOP10 and NHP2, which together with GAR1 form a protein core common to telomerase and all other H/ACA ribonucleoprotein complexes (H/ACA RNPs). Initially characterised as H/ACA RNP components important for pseudouridylation and rRNA processing, their role in the functionally distinct telomerase complex and telomere maintenance is less defined. In order to better understand their implications in DC, this study investigated the importance of these core proteins for the integrity and function of telomerase in human cells. RNAi knockdown studies demonstrated that dyskerin, NOP10 and NHP2 are necessary for the accumulation of TERC (telomerase RNA component); dyskerin and NOP10 for telomerase activity. Moreover, dyskerin was found to be important for maintaining telomere length over time. The impact of NOP10 and NHP2 missense mutations was also analysed in vitro, which indicated that they impair TERC accumulation. The potential effect on pseudouridylation was also considered in this study; the analysis of other H/ACA RNA levels in these knockdown experiments and in a cohort of patients with DKC1 mutations revealed an irregular and inconsistent impact compared to that observed on TERC. Finally, defective telomere maintenance is heavily implicated as the primary cause of DC and very short telomeres have been proposed as a diagnostic marker. This study investigated telomere length in a patient cohort of unprecedented size. It demonstrated the prevalence of the telomere length defect, but telomere length was not found to correlate with either genetic subtype or disease severity, implicating the rate of telomere shortening as the correlating factor instead.

Malaria has been a major driving force in the evolution of the human genome. In sub-Saharan African populations, two neighbouring polymorphisms in the Complement Receptor 1 (CR1) gene, named Swain-Langley (Sl2) and McCoy (McCb), occur at high frequencies, consistent with selection by malaria. This thesis investigates the association between these two polymorphisms and severe malaria. Previous studies into this area have produced conflicting findings. Using a large case-control study of severe malaria in Kenyan children and statistical models adjusted for confounders, I found that the Sl2 polymorphism was associated with markedly reduced odds of cerebral malaria and death, while the McCb polymorphism was associated with increased odds of cerebral malaria. I also identified an interaction between Sl2 and α+thalassaemia, with the protective association of Sl2 greatest in children with normal α-globin. Following these epidemiological findings, I explored potential biological hypotheses which might explain them. The first approach examined whether the Sl2 and McCb polymorphisms affected how CR1 forms clusters on erythrocyte membranes, a process which is key in the binding and transfer of immune complexes from erythrocytes to macrophages. Using erythrocytes from Kenyan children, I performed immunofluorescence assays (IFAs) with confocal microscopy to quantify CR1 cluster number and volume. I found no association between the Sl2 and McCb polymorphisms and either the number or volume of CR1 clusters formed. The second approach investigated whether the cerebral malaria-specific associations seen with Sl2 and McCb might be due to expression of CR1 by human brain endothelial cells (HBEC). The immortalised cell line HBEC-5i was investigated for expression of CR1 using IFA, flow cytometry, western blotting, functional C3b degradation assays, mass spectrometry, immunoprecipitation and siRNA knockdown experiments. A pool of α-CR1 monoclonal antibodies recognised an intracellular antigen in permeabilised HBEC-5i cells which was a similar molecular weight to CR1 on western blotting. However, when the α-CR1 monoclonal antibodies were tested individually, only E11 recognised an HBEC-5i antigen. Further investigative approaches did not support the presence of CR1 on HBEC-5i cells, instead suggesting that E11 was not specific for CR1 and was instead recognising a protein in the Golgi apparatus. The final approach was to examine whether the Sl2 and McCb polymorphisms might influence the binding of the complement components mannose binding lectin, C1q and L-ficolin to the LHR-D region of CR1. I aimed to generate recombinant proteins of the LHR-D region which included the polymorphisms. Site-directed mutagenesis of the region was successful and subcloning and expression of the mutant amplicons will be performed at a later date. In summary, I have identified opposing associations between the Sl2 and McCb polymorphisms and cerebral malaria, which do not appear to be due to differences in CR1 clustering or expression of CR1 by human brain endothelial cells. My investigation into whether the polymorphisms might influence complement component binding is ongoing.

Paediatrics became a viable medical specialty in Australia and New South Wales between 1945 and 1965. Paediatricians took possession of occupational spaces previously claimed by other medical groups and created their own new spaces. They argued that children were still growing and differed physically and emotionally from adults. Their special needs warranted the formation of a new division in medicine. Paediatricians adopted the new knowledge, technology and therapeutics that became available in the post-war period and demonstrated that they were capable of following the scientific medicine paradigm, the prevailing standard in internal medicine. Access to the children's hospital was essential for paediatricians as a workshop for their professional development, to treat their seriously ill patients, to support their claims for occupational space and for their authority and status as specialists in medicine.. Scientific medicine demanded more of the time of the paediatricians and in RAHC they elected to continue working in an honorary capacity. In another children's hospital, RCH in Melbourne, paediatricians were employed in a version of the full-time system. The different approaches to staffing illustrate the conflicts of interest found in specialty development in Australia and the pervasive influence of medico-political issues. As members of a privileged autonomous profession paediatricians in RAHC owed a duty to the people of NSW, and in their honorary positions, to the hospital. They had responsibilities to their patients, both private and public. They were committed to their own professional development and they had to make a living in private practice. By retaining the honorary system paediatricians in RAHC were obliged to give priority to their interests outside the hospital so that scientific medicine expanded only slowly. In RCH service development and research were enhanced because the conflicts of interest were reduced and paediatricians could devote more of their time to the hospital without compromising their other roles. The development of a new specialty required the acquisition by members of professional power, authority and status. This process was assisted by the formation of a professional association, but paediatricians had difficulty in creating an independent body that they controlled. For professional authority and status paediatricians in RAHC were strongly dependent on maintaining their dominant position in the hierarchy of the hospital. Although children were central to the development of paediatrics, their place at the bottom of the institutional hierarchy meant they were disempowered and unable to influence the development of the specialty. / PhD Doctorate

Unfractionated heparin (UFH) therapy is frequently used in tertiary paediatric healthcare facilities despite a lack of paediatric-specific research informing the optimal therapeutic intensity, monitoring recommendations or side-effect-profile in infants and children. As a result, the majority of clinical recommendations regarding UFH management in children have been extrapolated from adult evidence. The process of developmental haemostasis, in association with the variable pathogenesis of thromboembolic disease (TED) in children compared to adults, suggests that extrapolation of adult guidelines for UFH management to children is not ideal. / This study hypothesised that the process of developmental haemostasis would influence both the action and effect of UFH in children of different ages. This hypothesis was tested by addressing the following aims: 1. To determine the pharmacokinetics (PK) of UFH in children of different ages; 2. To compare the different methods of monitoring UFH in children of different ages; 3. To identify the impact of competitive plasma binding of UFH in children of different ages; 4. To determine the impact of UFH upon tissue factor pathway inhibitor (TFPI) release in children. / A prospective cohort study of children receiving a single bolus dose of UFH for primary thromboprophylaxis in the setting of cardiac angiography was conducted. Venous blood samples were collected prior to the UFH, then at 15, 30, 45 and 120 minutes post-UFH bolus. Laboratory assays performed included activated partial thromboplastin time (APTT), anti-Xa assay, anti-IIa assay, thrombin clotting time (TCT), protamine titration and TFPI. Levels of two plasma proteins known to competitively bind UFH (vitronectin and platelet factor 4) were determined and the impact of competitive plasma binding upon UFH activity, as measured by the anti-Xa assay, was quantified. A population approach to pharmacokinetic analysis, based on protamine titration results, was performed using WinNonMix™ Professional 2.0.1 (®1998-2000 Pharsight Corporation, Mountain View, CA, USA). Results were analysed according to the following age-groups: less than one year; one to five years; six to ten years; 11-16 years. / Sixty-four children were recruited, ranging in age from six months to fifteen-and-ahalf years. The mean dose/Kg of UFH across the entire cohort was 90.9± 15.5 IU/Kg. / Pharmacokinetic model specifications were systematically assessed, investigating the impact of parameter covariates and different error models upon objective function value and/or curve fitting. A first-order kinetic model best fitted the data. This model used weight 0.75 as the covariate of clearance and total weight as the covariate for volume of distribution. Parameter estimates for clearance and volume of distribution both demonstrated variance from adult and small neonatal PK studies of UFH, however methodological differences in PK analysis techniques limited comparisons. The half-life of UFH reported in this study was consistently and significantly shorter than that previously reported for adults, but longer than that reported for neonates. / All measures of UFH-effect demonstrated a significant and prolonged increase post- UFH bolus. The mean APTT was 261 seconds 102 ± 25 minutes post-UFH, representing a seven-fold increase from the mean baseline APTT (38 seconds). Anti- Xa assay levels were within the therapeutic range for TED management (0.35 to 0.7 IU/mL), or greater, at every post-UFH bolus timepoint. This prolonged UFH-effect was evident to nearly two hours post-UFH bolus, without concurrent UFH infusion. Age-related differences in UFH-response were evident for anti-Xa, anti-IIa and protamine titration results. Furthermore, during periods of high UFH concentration, the ratio of anti-Xa to anti-IIa activity in children less than one year of age significantly favoured UFH-mediated anti-Xa effect over anti-IIa effect (1.9), compared to teenagers (1.3). / This study demonstrated poor correlation between protamine titration and both the anti-Xa assay (r2 = 0.47) and APTT (r2 = 0.56). Use of the anti-Xa assay (0.35 to 0.7 IU/mL) or protamine titration assay (0.2 to 0.4 IU/mL) to establish APTT-based reference ranges for therapeutic management of TED resulted in APTT ranges with upper limits greater than 250 seconds. / No age-related quantitative differences in plasma levels of vitronectin or platelet factor 4 were identified across the childhood years. The addition of dextran sulphate (DS) to ex vivo study samples demonstrated no change in anti-Xa activity in samples collected within 20 minutes of UFH bolus, however a significant increase in anti-Xa activity following the addition of DS was evident at all later timepoints post-UFH bolus. / The measurement of TFPI before and after a single bolus dose of UFH demonstrated children have a similar immediate increase in TFPI activity following intravenous UFH compared to adults. However, the children in this series demonstrated a significantly prolonged level of increased TFPI activity, out to 102 ± 25 minutes post-UFH, compared to that reported in adult patients. / This study has developed the first paediatric-specific PK profile of UFH and has elucidated a number of age-dependent UFH-mechanisms of action that contribute to the previously reported age-dependent response to UFH in children. The results of this study support the hypothesis that developmental haemostasis influences both the action and effect of UFH in children of different ages.

Nutrition education is recognised as being of value in the prevention of malnutrition. However, in order for it to be effective, an in-depth study of the community prior to the implementation of any nutrition education programme is essential. A study of the nutritional status of pre-school children in Malukazi (an informal, unplanned Black township in the greater Durban area) together with background information on the household and the childminder was therefore undertaken, so that recommendations for a nutrition education programme in the area could be made. The relationship between nutritional status and certain ecological variables was also studied in order to determine which of these, if any, was a significant factor in the development of malnutrition. Nutritional status was assessed by using anthropometric measures (height and weight) and dietary intake (24-hour recall and food frequency). Background information obtained included socio-economic status; food purchasing, preparation and storage patterns; intrafamilial pattern of eating; food taboos; clinic attendance; and the childminder's sage, educational level, body size, nutritional knowledge and attitude towards nutrition education. Information was obtained by means of face-to-face interviews using a single, trained interviewer. The incidence of low weight-for-age was relatively low and that of low height-for-age ("stunting") considerably higher (14,2% and 47,3% below the 3rd percentile respectively), indicating that chronic malnutrition is a serious problem in this community. Information on dietary intake showed that intakes of several nutrients notably energy, calcium, vitamin A, ascorbic acid and vitamin D were low for the study population. The percentage of total energy provided by the various macronutrients was however in line with recommendations, which tends to indicate that the greatest need is for an overall increase in food intake. Of the ecological variables studied, only two were found to be significantly associated with the incidence of malnutrition. These were the number of children cared for by the childminder (p=0,04) and whether or not the household grew their own vegetables (p=0,02). The degree of malnutrition found to exist in this community, together with the unsatisfactory level of nutritional knowledge of the childminders and their apparent willingness to learn more, revealed the desirability for further nutrition education in this area. Recommendations regarding future nutrition education programmes for this community based on the findings of the study are submitted. / Thesis (M.Med.)-University of Natal, Durban, 1991.

Hypothesis: Trimethoprim promotes wound healing, decreases lesion counts and improves quality of life of recessive dystrophic epidermolysis bullosa (RDEB) patients. Objectives: Assess feasibility of conducting a large randomized clinical trial. Determine efficacy of trimethoprim in healing of chronic wounds, decreasing lesion counts and improving quality of life of RDEB patients. Methods: Prospective, randomized, double-blinded, placebo-controlled, cross-over pilot study. Results: Ten patients enrolled in the trial, 7 completed both study periods. Despite showing that all patients improved on trimethoprim and that there was a 41% difference in affected area percent change favoring trimethoprim, the cross-over analysis did not show a significant difference between the drug and placebo (p=0.08). Secondary outcome measures did not achieve statistical significance. Limitations: Small sample size, large variation in wound size and unaccounted confounders. Conclusions: Although patients experienced improvement while on trimethoprim, no statistical significant change was showed when compared to placebo.

Hypothesis: Trimethoprim promotes wound healing, decreases lesion counts and improves quality of life of recessive dystrophic epidermolysis bullosa (RDEB) patients. Objectives: Assess feasibility of conducting a large randomized clinical trial. Determine efficacy of trimethoprim in healing of chronic wounds, decreasing lesion counts and improving quality of life of RDEB patients. Methods: Prospective, randomized, double-blinded, placebo-controlled, cross-over pilot study. Results: Ten patients enrolled in the trial, 7 completed both study periods. Despite showing that all patients improved on trimethoprim and that there was a 41% difference in affected area percent change favoring trimethoprim, the cross-over analysis did not show a significant difference between the drug and placebo (p=0.08). Secondary outcome measures did not achieve statistical significance. Limitations: Small sample size, large variation in wound size and unaccounted confounders. Conclusions: Although patients experienced improvement while on trimethoprim, no statistical significant change was showed when compared to placebo.

- / -