No description available.

Neisseria meningitidis is the most common cause of bacterial meningitis in the Western world and the second leading cause of mortality in 1-5 year-olds in the United Kingdom. A signature-tagged mutagenesis screen of approximately 3,000 insertional mutants of a serogroup B isolate of N. meningitidis, C311⁺, identified 73 genes required for pathogenesis in an infant rat model of meningococcal septicaemia. Homology-based searches indicate that two of the genes identified, NMB0342 and NMB0345, have homologues in other pathogenic bacteria and exist within a potential operon of seven genes (NMB0342-NMB0348). NBM0342 is a homologue of ispA (intracellular septation protein) of Shigella flexneri, required for effective intercellular spread and plaque formation in epithelial cells. NMB0345 is a homologue of cbf, a Campylobacter jejuni gene that encodes a 29 kDa protein which is a major antigenic peptide. PCR and Southern analyses of genes in the NMB0342-NMB0348 locus show that they are conserved across a wide range of pathogenic isolates and serogroups of N. meningitidis. However, these genes are present only in a subset of commensal strains. N. meningitidis mutants with transpoon insertions in NMB0342 and NMB0345 are highly attenuated when directly competed with the wild-type bacterium in the infant rat model of infection. Mutations have been introduced into other genes within the locus and the resulting mutants analyzed for their ability to cause systemic disease. Mutants with transpoon insertions in the NMB0343 and NMB0344 genes are significantly attenuated, while mutants with insertions in NMB0347 and NMB0348 are attenuated to a lesser degree. Complementation of the NMB0342 mutation by ectopic chromosomal integration of a wild-type copy of NMB0342 almost completely restores the virulence of the bacterium. In vitro cell-culture analyses and microscopic analysis of mutants in association with host cells demonstrate that a mutant with a transpoon insertion in NMB0345 is significantly reduced in its adherence to Chang epithelial cells compared to the wild-type bacterium. Whole blood and serum-sensitivity assays show that the NMB0342 and NMB0345 mutants are highly serum-sensitive compared to the wild-type bacterium. Preliminary experiments have demonstrated that immunization of mice with recombinant NMB0345 protein confers protection against challenge with the serogroup B isolate MC58. In vitro assays demonstrate that recombinant NMB0345 is an active peptidyl polyl cistrans isomerase (PPIase). Together, the results from these investigations support a role for genes of the NMB0342-NMB0348 locus in the pathogenesis of N. meningitidis infections. Further investigation is needed to assess the potential of NMB0345 as a vaccine candidate.

Articular cartilage accrual occurs predominantly during childhood and adolescence, with the magnitude, direction, and pattern of internal joint loads directing the cartilage growth. If any of these factors of the joint loading are abnormal, it can predispose these children to degenerative knee joint disease as an adult. To provide an estimate of the internal joint loads, a paediatric-focused, static optimization-based lower limb model was developed, compared to recorded sEMG, and analyzed for sensitivity to changes in ground reaction force and muscle attachment site. The model was found to provide consistent predictions of joint contact force predictions ranging from 0.01 to 0.35xBW with standard error of 8% to 17%, with the exception of left knee medial-lateral shear at 108%. Muscle force predictions related well to sEMG, with the standard error ranging from 14% to 36%, except for gastrocnemius lateral at 104%. The model was sensitive to variations in the ground reaction force vector, with a maximum deviation of 0.11 xBW determined as a result of a ±5% variation in GRF. The model was found to be sensitive to clinically relevant deviations in muscle attachment site. Maximum knee anterior shear was significantly changed (p < 0.05) with a 1cm posterior quadriceps insertion deviation, maximum lateral shear with a posterior semimembranosus deviation, and maximum medial shear with a posterior or medial quadriceps deviation. No deviations caused statistically significant changes in compression. Statistically significant change in joint contact force could not be predicted based on changes in muscle moment arm, but could be indirectly predicted by the predicted muscle forces. The model’s uniform convergence and sensitivity to variations in input indicate that the model is sufficiently reliable and robust. This sensitivity suggests that the model is capable of adapting to altered loading conditions and musculoskeletal geometry, either due to deformity or corrective procedure. The model was therefore deemed to be a strong platform for developing clinically specific models for analyzing internal knee loads in a diverse paediatric population. / Thesis (Master, Rehabilitation Science) -- Queen's University, 2012-09-26 10:37:20.752

A phenomenological study was conducted to understand the lived experience of parents parenting a child with autism in a rural area. The philosophy of hermeneutic phenomenology was used to guide this inquiry. Interviews of 26 families served as primary data. Thematic statements were isolated using van Manen’s (1990) selective highlighting approach. Making the invisible, visible emerged as the essence of the parents’ experience. Parents shared that although autism is an invisible disability, they in fact made it visible in their constant battles to ensure their child received the best quality of life. Five themes represented this essence: using autism to enable, lifelong advocating, centering autism within the family, the ups and downs of living rurally, and a renewed sense of parenting. Findings from this study may be used to guide program development that is concerned with improving the quality of life families of children with autism.

A phenomenological study was conducted to understand the lived experience of parents parenting a child with autism in a rural area. The philosophy of hermeneutic phenomenology was used to guide this inquiry. Interviews of 26 families served as primary data. Thematic statements were isolated using van Manen’s (1990) selective highlighting approach. Making the invisible, visible emerged as the essence of the parents’ experience. Parents shared that although autism is an invisible disability, they in fact made it visible in their constant battles to ensure their child received the best quality of life. Five themes represented this essence: using autism to enable, lifelong advocating, centering autism within the family, the ups and downs of living rurally, and a renewed sense of parenting. Findings from this study may be used to guide program development that is concerned with improving the quality of life families of children with autism.

Tracheobronchial structural lesions present a considerable diagnostic challenge and workload to tertiary paediatrics. Bronchoscopy is the definitive way of confirming these diagnoses. Quantification of the size of lesions is important to the decision-making processes for management, yet this aspect of assessment has been left to subjective visual estimates of the size as there has not been a method developed that enabled quantitative measurement. The clinical profiles of children with these disorders have long been suspected to be worse than respiratory illnesses in normal children however this aspect has never been studied using objective criteria. The major hypothesis of this thesis is that structural lesions such as malacia disorders of the tracheobronchial tree result in significant respiratory morbidity that is a result of dose dependent crossectional area losses in lesions which improve with increasing age and management strategies. The aims of this thesis were i. to develop a methodology for objectively quantifing airway lesions using a paediatric bronchoscope ii. establish a cohort of children with airway lesions and quantitatively define the airway lesions and then longitudinally study these lesions and the respiratory illness profiles using validated scales of illness over a 2 year period.

No description available.

Background: Congenital heart disease (CHD) is the leading non-infectious cause of paediatric morbidity and mortality worldwide and a significant social and healthcare burden. The aetiology of CHD is poorly understood, though heritable genetic factors including copy number variants (CNVs) have been shown to contribute to the risk of CHD in individuals of European ancestry. However, the role of rare CNVs in the development of CHD in African populations including South Africa is unknown. This study aims to identify pathogenic and likely pathogenic CNVs in South African cases of CHD. To our knowledge, this is the first study to investigate the genetic basis of CHD in a South African cohort. Methods: The study cohort included 105 patients presenting to the cardiac clinics at Red Cross War Memorial Children's Hospital and Groote Schuur Hospital with non-syndromic isolated CHD (n = 76), nonsyndromic CHD with additional extra-cardiac anomalies (n = 17), and positive controls with syndromic CHD (n = 12). Genotyping was performed using the Affymetrix CytoScan HD platform. Rare CNVs were filtered using stringent criteria for their size and algorithm-specific quality score and were compared against a gene panel of known CHD-associated genes. Candidate genes were considered based on pLI scores and reported CHD phenotypes in mouse models. The identified CNVs were validated by quantifying the read-coverage of available whole-exome sequencing data of a similar overlapping cohort. Results: Chromosomal microarray analysis was successful for 101 participants (including 89 non-syndromic CHD cases and 12 control cases) and led to the identification of eight CNVs overlapping genes known to be causal for CHD (GATA4, TBX1, FLT4, CRKL, NSD1, and B3GAT3), and four CNVs encompassing candidate genes likely to play a role in the development of CHD (DGCR8, JARID2, KDM2A, and FSTL1). The CNVs were identified in nine unrelated individuals: five of the CNVs were classified as pathogenic or likely pathogenic (5.6% of the cohort) and four were classified as variants of unknown significance (4.6%). CNVs of interest were validated using the available whole-exome sequencing data. Conclusions: In this study, we show that chromosomal microarray analysis is an effective technique for identifying CNVs in patients diagnosed with CHD and that this approach can be performed locally in South Africa, producing results similar to those seen in international CHD studies. The findings of this thesis highlight the wide genetic heterogeneity of CHD and the growing importance of CHD genetic studies for both research and clinical purposes. Advancing our understanding of CHD aetiology will help define disease risk in South Africa and improve the way we care for and assess our cardiac patients.

Background Effective phototherapy reduces neonatal jaundice and its complications. Irradiance increases as the distance of the light source decreases from a single phototherapy light. There are limited studies of the effect of distance and positional changes on different LED light designs on achieving effective phototherapy. Objectives To describe and compare the effect of distance, angle and plastic barriers on three different LED lights of different design. Methods Comparisons were made using a Servolite LED light, a General Electric (GE) Lullaby and a Ningbo David LED phototherapy light. Measurements were done according to methods described by the International Electrotechnical Communission (IEC). The effective irradiated area was measured on a grid measuring 60 x 30 cm subdivided into 5 x 5 cm squares. Measurements were done for the following scenarios: light placed at the manufacturers' recommended distance, 20 cm closer, 20 cm further, at an angle, through clear plastic and through scuffed perspex. Results When the lights were placed closer to the irradiated surface than the manufacturers' recommendations, the maximum irradiance increased, but the median irradiance and uniformity ratio decreased. When the lights were angled at 45 the median irradiance was decreased. A decrease in the median irradiance was also seen when phototherapy lights passed through scuffed plastic and food grade plastic. Conclusion Our study demonstrated that placing LED lights closer than the manufacturers recommendations, the use of transparent barriers and the use of lights at an angle, compromised phototherapy irradiance and distribution. Only the GE light met IEC standards.

Background: Long term survival of children living with HIV due to improved early access to antiretroviral therapy (ART) is contributing to a growing population of adolescents living with perinatally acquired HIV (PHIV+) at risk of developing chronic multisystem comorbidity. There is limited knowledge on the overall burden, progression and causes of morbidity in PHIV+ adolescents, especially in resource limited settings. Much of what is known about morbidity in PHIV+ adolescents relates to single organ system pathology and there is a lack of a holistic approach to PHIV+ adolescents and their overall health. The aim of this PhD project was therefore to investigate the spectrum and determinants of chronic morbidity, the progression of disease and intercurrent illness in PHIV+ adolescents on ART over a 4- year period. Methods: This was a prospective study of participants enrolled in the Cape Town Adolescent Antiretroviral Cohort (CTAAC), a longitudinal cohort study, that recruited 515 PHIV+ adolescents and 110 HIV negative (HIV-) adolescents matched by age from 7 health care sites in Cape Town, South Africa. Eligibility criteria included PHIV+ adolescents who were aged 9-14 years, who had been on ART for at least 6 months and were aware of their HIV status. All adolescents and caregivers gave informed consent/assent. Participants were followed 6-monthly with questionnaires, clinical examination with detailed pulmonary (lung function), neurocognitive (magnetic resonance imaging and a battery of neurocognitive tests), cardiovascular (echocardiogram and ECG) and laboratory investigations. Analyses for each specific objective of the PhD were developed. Three analyses used data from the enrolment visit and were primarily descriptive and two were longitudinal and examined the incidence of hospitalizations, QuantiFERON conversion (an interferon gamma release assay used to measure Mycobacterium tuberculosis infection) and Tuberculosis (TB) disease. Results: Five hundred fifteen PHIV+ and 109 HIV- participants had a median follow-up of 4.1 years (IQR: 3.7–4.6). At enrollment, PHIV+ adolescents had a median duration of ART of 7.6 years (IQR: 4.6–9.2), median CD4 count of 713 cells/mm3 (IQR: 561.0–957.5) and 387 (75%) had a viral load of <50 copies/mL. Neurocognitive impairment was present in more than half of the PHIV+ cohort (56.3% vs. 45.3% in HIV-, p=0.05) but renal impairment was rare (2.3% in PHIV+ vs. 2.1% in HIV-, p=0.89). Microalbuminuria was also rare (8.0 in PHIV+ vs. 9.0% in HIV-, p=0.80). Respiratory or cardiac impairment were more common in PHIV+ adolescents than in HIV- participants (27.1% vs. 14.7%, p=0.01 and 46.1% vs. 33.7%, p=0.03, respectively). Multisystem impairment (defined as impairment of ≥ 3 systems) was uncommon, with only 10% of PHIV+ adolescents having 4-system impairment. Metabolic abnormalities, such as insulin resistance (IR), were relatively common but IR rates did not differ compared to HIV- adolescents (18 vs. 20%, p= 0.17). Incidence rates for hospitalization were 6.6 per 100-person-years (PY) in PHIV+ adolescents, three times that of HIV- adolescents. Sixty percent of hospitalization episodes were due to non-infectious causes and 24% due to infectious causes, of which pneumonia and TB were the predominant causes. PHIV+ adolescents had a substantially higher incidence of TB disease than HIV- adolescents (2.2/100 PY, 95% CI 1.6-3.1 vs. 0.3/100 PY, 95% CI 0.04-2.2), despite a similar rate of TB infection, as measured by QuantiFERON positivity. TB disease was associated with low CD4 counts and high viral loads in PHIV+ adolescents. Conclusion: Chronic single system morbidity experienced by PHIV+ adolescents on ART was common and merits further study, as this population begins to engage in adult lifestyle factors, such as smoking and alcohol use, that may compound these abnormalities. However, multisystem morbidity was relatively rare. In addition, in a relatively small percentage of adolescents there were subclinical metabolic abnormalities (IR and microalbuminuria) that may result in increased morbidity especially with regards to diabetes and cardiovascular disease in later life. The high burden of hospitalization and intercurrent disease, mainly due to TB, could be prevented by proven strategies, such as TB preventive therapy and ensuring adherence to optimal ART regimens.