This study explored infants' immediate and residual responses to holding and rocking, and how these responses relate to previously proposed mechanisms to explain long term benefits found when infants are repeatedly exposed to tactile and vestibular stimulation. This form of stimulation has been proposed to increase infants' ability to control and organize l) their behavioral state, 2) their arousal and autonomic functioning, or 3) that there is no clear relationship between immediate responses and long term benefits. Behavioral state and heart rate were collected on 40 infants who were randomly assigned to either a control group where infants were briefly repositioned twice but otherwise lay undisturbed for 90 minutes or an experimental group where infants were held and rocked for 30 minutes during the middle of a 90-minute observation. Results of analyses showed that, when infants were held and rocked they 1) displayed a lower Heart Rate Mean and Standard Deviation, 2) displayed a lower Mean Heart Rate During Active Sleep, 3) spent less time in a FussCry State, 3) were less likely to cry continuously, and 4) displayed nominally Smoother State Transitions and greater Stability Within States. Following the cessation of the rocking stimulus infants in the Experimental Group l) displayed a lower Mean Heart Rate, 2) displayed a lower Mean Heart Rate while in a Quiet Alert State, 3) were more likely to spend some time in a Quiet Sleep State, and 4) were less likely to cry continuously. In addition, all infants displayed Smoother State Transitions and greater Stability Within States during the first 30 minutes than during the final 30 minutes of the observation. Finally, across the 90-minute observation, the infants who were not rocked spent progressively more time in a Quiet Alert State, whereas infants who were rocked spent less time in a Quiet Alert State. The results were the most consistent with the hypothesis that the mechanism leading to both the immediate and residual effects of the stimulation was an increase in control and organization of infants’ arousal and autonomic functioning. / Ph. D.

Neonatal jaundice is a physiological condition which has potentially deleterious outcomes. Elevated serum bilirubin levels are well-documented antioxidants and have been shown to disrupt cellular membranes of Gram-positive organisms under specific conditions. To determine whether bilirubin had antimicrobial potential against neonatal sepsis organisms, relevant isolates were identified by clinical audit and assessed for sensitivity. 26 clinical isolates including 15 CoNS, 7 GBS, E. coli, E. faecalis, K. oxytoca and A. haemolyticum were characterised biochemically, genetically, and by MALDI Biotype. GBS isolates showed a significant reduction in growth from 100–82.0%(±6.1%), between 0–400μM bilirubin– supplemented CBA (p=0.005). A physiologically relevant liquid model with 100μM bilirubin was developed to test growth reduction. Results showed slight growth reduction in isolates at specific time points, but species specific. Transcriptomic analysis was performed on three GBS isolates to determine effect of bilirubin exposure on gene expression. 17 genes were differentially expressed between 100μM bilirubin and solvent control; 16 up-regulated and one down-regulated with bilirubin. Most significantly, a 5 gene cluster describing multiple components of the phosphotransferase system and two ABC transporter genes were up-regulated, potentially to remove bilirubin from the cell. Proteomic analysis was completed to study protein expression: 12 proteins were identified by LC-MS from 2-DGE and Progenesis SameSpots analysis. Of these, 6 were up- and 6 down-regulated with bilirubin. Up-regulated proteins included two ABC transporter components, phosphoglycerate kinase, S-ribosylhomocysteinase, and two transcription regulators: GroEL/GntR. Down-regulated was iron ABC transporter, NeuB, ornithine carbamoyltransferase and ssDNA binding proteins controlling transcription and translation. This study concluded that bilirubin may play a protective role during the neonatal period; it can be considered an antimicrobial compound which disrupts Grampositive organisms such as GBS, an important agent in early-onset sepsis. The results from this study could be used to develop novel antimicrobial treatments based on identified molecular targets.

published_or_final_version / Paediatrics / Doctoral / Doctor of Philosophy

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

Thesis (MSD(Play therapy))--University of Pretoria, 2006. / Abstract in English and Afrikaans. Includes bibliographical references. Available on the Internet via the World Wide Web.

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 246-268). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph.D.)--York University, 2007. Graduate Programme in Sociology. / Typescript. Includes bibliographical references (leaves 217-233). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR39000

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