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Abstract The 1-dimentional model of aerosol process which includes a hot aerosol stream flowing through a tube with thermal gradients between the aerosols stream and the reactor cooled walls was developed to predict the aerosol formation, growth and thermophoretic deposition in high-temperature reactors. The mass and energy conservation equations were solved to determine the concentration and temperature profiles of the components. The model includes particle formation by nucleation, growth by coagulation, Brownian diffusion as well as the loss of aerosol particles by thermophoretic deposition on the cold reactor walls. The developed model results in the system of ordinary differential equations which were solved in SCILAB software.

Thawing of fresh frozen plasma (FFP) in South Africa is not standardized and thawing at high temperatures may cause clotting factor activation and disseminated intravascular coagulation (DIC). This research project studies the in-vitro effects of thawing FFP at various temperatures on coagulation. Twenty units of FFP were each divided into 4 satellite bags which were respectively thawed at 22ºC, 37ºC, 45ºC and 60ºC and tested for Fibrinogen, DDimers, PT, PTT, r value, Alpha Angle and Maximum Amplitude (MA). FFP thawed at 60ºC showed significant differences suggesting clotting factor inactivation. FFP thawed at 45ºC showed significantly elevated D-Dimers. Clotting factors thawed at 22ºC may be partially inactivated. High thawing temperatures may activate and then denature the factors therein. Twenty two degrees may partially inactivate FFP until it is warmed to body temperature. The clinical implications and recommendations of this study are to thaw FFP at 37ºC.

Paediatric Human Immunodeficiency Virus (HIV) and Acquired Immunodeficiency Syndrome (AIDS) remain a significant health care challenge in South Africa. Oral health and coagulation are only two of the many problems experienced by HIV positive paediatric patients. This research report began with an observation that known HIV positive paediatric patients bled more than known HIV negative paediatric patients or those with unknown HIV status while undergoing dental extractions at Charlotte Maxeke Johannesburg Academic Hospital. The observation prompted a prospective, contextual, descriptive study looking at the coagulation profile (platelet count and thromboelastogram (TEG) profile (reaction time (r-time), clot formation time (Ktime), alpha angle (α-angle) and maximum amplitude (MA)), CD4 counts and percentages and observed clinical bleeding in HIV negative, HIV positive not on antiretroviral treatment (ARVs) and HIV positive on ARVs paediatric patients presenting for dental extraction. Over a two year period 47 HIV negative, 12 HIV positive not on ARVs and 17 HIV positive on ARVs paediatric patients were enrolled in the study using a consecutive, convenience sampling method. Each paediatric patient was given a standard inhalational general anaesthetic using sevoflurane and during intravenous cannulation the researcher drew blood from each child for analysis. A senior dentist from the Department of Paediatric Dentistry assessed bleeding in all cases. The data obtained for each of the three study groups was compared using a oneway analysis of variance followed by pair wise comparison using the Bonferroni adjustment to address multiplicity. To deal with the big standard deviations and skewed data a one-way analysis of variance for ranks tested for differences between the groups. No statistically significant differences were found when comparing the groups for platelet count (p = 0.2087), TEG r-time (p = 0.4738), TEG K-time (p = 0.6967), TEG α-angle (p = 0.7948) or TEG MA (p = 0.2982). There was a statistically significant difference between the HIV negative and HIV positive not on ARVs groups (p = 0.000 and 0.004) and HIV positive on ARVs and HIV positive not on ARVs groups (p = 0.000 and 0.001) when comparing CD4 count and percentage. Patient groups were compared with respect to bleeding complications using the Fisher’s exact test. There was no statistically significant difference in observed bleeding between the three groups of paediatric patients. The entire HIV positive group was then compared for bleeding, and using the Welch t-test, adjusting for unequal variances it was found that there was statistically, significantly more bleeding in the HIV positive children with lower CD4 counts regardless of treatment with ARVs (p = 0.0129). These results were also confirmed using the Wilcoxon rank-sum test (p = 0.0335). Although this study showed statistically significant bleeding in HIV positive paediatric patients with lower CD4 counts, the tests of coagulation used in the study were unable to define the underlying pathogenesis. Further research into coagulation in HIV positive paediatric patients is needed.

MSc (Med) Molecular Medicine and Haematology, Faculty of Health Sciences, University of the Witwatersrand, 2009 / The underlying mechanism and determinants of inhibitor formation in approximately 30% haemophilia A and 5% haemophilia B patients are not fully understood. A large amount of the data on immune responses against FVIII and FIX is from animal models. Studies investigating cytokines in haemophilia are very limited and fragmentary, and the classification of hemophilia patients according to their factor activity levels has been observed to be inconsistent. The current study aims to find the associations between factor levels, clinical phenotype, cytokine profiles and polymorphisms in the IL-10 gene promoter of haemophilia A and B patients with and without inhibitors. This may give more insight into the pathophysiology of haemophilia, help improve the understanding of the pathogenic mechanisms that underlie inhibitor development, and facilitate new diagnostic and therapeutic strategies for haemophilia. Haemophilia A and B patients with and without inhibitors were enrolled in the current study. Forty (40) patients from the Charlotte Maxeke Johannesburg Academic Hospital Haemophilia Comprehensive Care Centre (CMJAH-HCCC) were randomly selected. An equal number of frequent bleeders and infrequent bleeders were recruited. Frequent bleeders were defined as those patients with 2 or more bleeding episodes per month on three consecutive months. Bleeding frequency was evaluated on the patient’s bleeding charts. FVIII and FIX activity levels of all patients were measured using the Dade Behring Sysmex CA-7000 coagulation analyzer, and information on each patient’s bleeding episodes was obtained from the haemophilia bleeding charts. The inhibitor status of all patients was evaluated using the Bethesda inhibitor assay. IL-1β, IL-6 and TNF-α were analyzed using an ELISA kit method. IL-2, IL-4, IL-10 and IFN-γ were analyzed using the CBA Human TH1/TH2 Cytokine Kit. DNA was extracted using the Nucleon BACC3 from Amersham Biosciences. Polymorphisms in the IL-10 gene promoter region were analyzed using PCR. The Statistica Release 8 statistics package was used for statistical analysis. The present study population showed significant discrepancies in the theoretic classification of haemophilia patients. Severe haemophilia patients had significantly higher levels of IL-6 than the mild/moderate group and biochemical classification correlated positively with IL-6. IL-6 was also the only significant predictor of biochemical classification. IL-1β and IL-4 was found to be significantly higher in the mild/moderate group than in the severe group. There were no significant differences in the levels of IL-2, IL-10, and IFNγ between the mild/moderate and severe groups and between patients with inhibitors and without inhibitors. There were also no differences in the cytokine profiles of low and high responders. No significant differences were found between cytokine profiles of frequent and infrequent bleeders. IL-6 and TNF-α were found to be significantly higher in patients with inhibitors than in haemophilia patients without inhibitors. IL-6 and IL-1β were the only significant predictors of the inhibitor status of haemophilia patients. Haemophilia severity and race were found to be significant risk factors for inhibitor development. A 150 bp allele of the IL-10 promoter region with the microsattelite marker was observed in patients with and without inhibitors as well as the healthy controls. The 150 bp allele was also observed in both black and white subjects. Large phenotypic heterogeneity exists in haemophilia patients. The pro-inflammatory cytokines IL-6 and IL-1β together with IL-4 may be involved in determining the biochemical severity of haemophilia. IL-6 was the only cytokine in this study found to be a significant predictor of bleeding frequency. The study results also suggest that IL-6 and IL-1β may be involved in the production of antibodies against infused factor in patients with inhibitors. The presence of a 150 bp allele of the highly polymorphic IL-10 promoter region in patients with and without inhibitors as well as the healthy controls suggests that, polymorphisms in this gene do not influence inhibitor development in this population.

212 leaves : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (M.D.)--University of Adelaide, Dept. of Medicine, 1973

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Reproduction de : Thèse d'exercice : Chirurgie dentaire : Nantes : 2008. / Bibliogr.