Bilateral cochlear implantation is accepted medical practice since 2008 in clinically suitable adults and children to enhance bilateral processing benefits. Bilateral implantation may lead to the restoration of some bilateral hearing advantages, such as improved speech recognition in noise, localisation, head shadow effect, summation, and squelch. The majority of the advantages stated in literature, though, are characteristic of the simultaneously implanted cochlear implant population. Simultaneous implantation is not yet a reality in South Africa due to funding constraints, therefore determining the bilateral processing abilities in sequentially implanted adults is essential. Determining bilateral processing benefits achievable with sequential implantation could result in evidence-based recommendations in terms of candidacy considerations, surgery protocols, motivations for medical aid funding for simultaneous cochlear implantation, and relevant measures to determine the bilateral processing benefit attainable. Furthermore, it might enhance audiologists‟ insight regarding post-implantation performance of sequentially implanted patients and enable them to counsel prospective candidates realistically. The aaim of this study was to determine the bilateral benefit attained by sequentially implanted adults. A quantitative, cross-sectional research approach was followed in a one group post-test-only exploratory research design. A purposive convenient sampling method with specified selection criteria was used to select 11 adult clients of an established cochlear implant programme in Pretoria. Tests of sound localisation in the horizontal plane and speech perception in noise were performed. During the test of sound localisation, performance with only the first or only the second implant was found to be very similar. For the majority of participants the second cochlear implant (CI 2) was the superior performing implant during xviii speech perception in noise testing, in spatially separated speech and noise conditions where noise was directed to the first implant, as well as in spatially coincident speech and noise. A statistical significant bilateral benefit (p < 0.05) was attained by sequentially implanted adults for sound localisation. A bilateral benefit for speech perception in noise was observed when noise was directed to the first implant and in the diotic listening condition with average benefits of 1.69 dB and 0.78 dB, respectively. It was not statistically significant (p > 0.05), however, and was smaller than bilateral benefit values achieved by simultaneously implanted adults in previous studies. The head shadow effect at 180° was found to be the strongest and most robust bilateral spatial benefit. Squelch and summation benefit values ranged from negative values to 2 dB and 6 dB, respectively. This corresponded with values found in previous studies. The improvement in speech perception in spatially distinct speech and noise from adding the ear with a better SNR (signal to noise ratio) indicated that the contribution of CI 2 seems to be greater than that of CI 1 for bilateral spatial benefit. It can be concluded that adults with sequential implants may achieve some extent of bilateral benefit even with many years of unilateral implant use, when speech processors differ, when the second implant is done ≥ 10 years after the first implant, and in cases of prelingual deafness. A key benefit of sequential implantation appears to be related to the advantage of having hearing on both sides so that the ear with the more favourable environmental signalto-noise ratio is always available. AFRIKAANS : Bilaterale kogleêre inplanting is sedert 2008 aanvaarde mediese praktyk vir klinies geskikte volwassenes en kinders, ten einde bilaterale prosesseringsvoordeel te verhoog. Bilaterale inplanting kan lei tot die herstel van sommige van die voordele van bilaterale gehoor, soos verbeterde spraakherkenning in lawaai, klanklokalisering, die kopskadueffek, sommering en selektiewe onderdrukking (“squelch”). Die meeste van die voordele wat in die literatuur bespreek word, is egter kenmerkend van dié persone by wie twee kogleêre inplantings gelyktydig gedoen is. Gelyktydige inplanting is as gevolg van beperkte befondsing nog nie in Suid-Afrika 'n werklikheid nie, daarom is dit noodsaaklik om te bepaal watter bilaterale prosesseringsvoordele by opeenvolgend-geïnplanteerde volwassenes voorkom. Die bepaling van watter bilaterale prosesseringsvoordele met opeenvolgende inplanting bereik kan word, sou kon lei tot getuienis-gebaseerde aanbevelings met betrekking tot besluite oor die geskiktheid van kandidate, protokol vir sjirurgie, motiverings vir die befondsing van gelyktydige kogleêre inplantings deur mediese voorsorgfondse, en toepaslike maatstawwe om te bepaal watter mate van bilaterale prosesseringsvoordeel haalbaar sou wees. Dit sou verder oudioloë se insig kon verbreed met betrekking tot die na-operatiewe prestasie van opeenvolgend-geïnplanteerde persone en hulle sodoende in staat stel om voornemende kandidate van realistiese raad te bedien. Die doel van hierdie studie was om te bepaal wat die bilaterale prosesseringsvoordele is wat deur opeenvolgend-geïnplanteerde volwassenes verkry kan word. 'n Kwantitatiewe navorsingsbenadering met 'n dwarsprofiel van „n enkelgroep is gevolg, met 'n post-toets verkennende navorsingsontwerp. 'n Doelgerigte gerieflikheidssteekproef met 'n gespesifiseerde seleksiekriteria is gebruik om 11 volwasse kliënte van 'n gevestigde kogleêre inplantprogram in Pretoria te selekteer. Klanklokalisering in die horisontale vlak en die waarneming van spraak in lawaai is getoets. Tydens die toets vir klanklokalisering is gevind dat prestasie met slegs die eerste of slegs die tweede inplanting soortgelyk was. Vir die meeste deelnemers aan die studie het die tweede kogleêre inplanting (KI 2) die beste prestasie gelewer tydens spraakwaarneming in lawaai, in omstandighede waar spraak en lawaai ruimtelik geskei is en die lawaai op die eerste inplanting gerig is, asook in omstandighede waar spraak en lawaai ruimtelik saamvoorkomend aangebied is. 'n Statisties beduidende bilaterale voordeel (p < 0.05) is deur opeenvolgend-geïnplanteerde volwassenes vir klanklokalisering behaal. 'n Bilaterale voordeel vir spraakwaarneming in lawaai is waargeneem waar lawaai op die eerste inplanting gerig is en ook in diotiese luistertoestande, met 'n gemiddelde voordeel van 1.69 dB en 0.78 dB, onderskeidelik. Dit was egter nie statisties beduidend nie en was ook kleiner as die bilaterale voordeelwaardes wat in vorige studies deur gelyktydig-geïnplanteerde volwassenes behaal is. Die kopskadu-effek by 180° was die sterkste en mees robuuste bilaterale ruimtelike voordeel. Voordeelwaardes vir selektiewe onderdrukking en sommering het gewissel van negatiewe waardes tot 2 dB en 6 dB onderskeidelik. Dit stem ooreen met waardes wat in vorige studies gevind is. Die verbetering in spraakwaarneming in ruimtelik geskeide spraak en lawaai wat verkry is deur die oor met 'n beter STR (sein-tot-ruis ratio) by te voeg, het daarop gedui dat die bydrae van KI 2 tot bilaterale ruimtelike voordeel waarskynlik groter as die bydrae van KI 1 is. Die gevolgtrekking kan gemaak word dat volwassenes met opeenvolgende inplantings 'n mate van bilaterale voordeel verkry selfs na vele jare van unilaterale inplantingsgebruik, wanneer die spraakprosesseerders in die twee inplantings van mekaar verskil, wanneer die tweede inplanting ≥ 10 jaar na die eerste plaasvind, en in gevalle van prelinguale doofheid. 'n Sleutelvoordeel van opeenvolgende inplanting hou klaarblyklik verband met die voordeel van gehoor aan albei kante te hê sodat die oor met die gunstigste sein-tot-lawaai ratio altyd beskikbaar is. / Dissertation (MCommunication Pathology)--University of Pretoria, 2011. / Speech-Language Pathology and Audiology / Unrestricted

Reverse genetics is an innovative molecular biology tool that enables the manipulation of viral genomes at the cDNA level in order to generate particular mutants or artificial viruses. The reverse genetics system for the influenza virus is arguably one of the best illustrations of the potential power of this technology. This reverse genetics system is the basis for the ability to regularly adapt influenza vaccines strains. Today, reverse genetic systems have been developed for many animal RNA viruses. Selection-free reverse genetics systems have been developed for the members of the Reoviridae family including, African horsesickness virus, bluetongue virus and orthoreovirus. This ground-breaking technology has led to the generation of valuable evidence regarding the replication and pathogenesis of these viruses. Unfortunately, extrapolating either the plasmid-based or transcript-based reverse genetics systems to rotavirus has not yet been successful. The development of a selection-free rotavirus reverse genetics system will enable the systematic investigation of poorly understood aspects of the rotavirus replication cycle and aid the development of more effective vaccines, amongst other research avenues. This study investigated the importance of co-expressed rotavirus proteins in the development of a selection-free rotavirus reverse genetics system. The consensus sequences of the rotavirus strains Wa (RVA/Human-tc/USA/WaCS/1974/G1P[8]) and SA11 (RVA/Simian-tc/ZAF/SA11/1958/G3P[2]) where used to design rotavirus expression plasmids. The consensus nucleotide sequence of a human rotavirus Wa strain was determined by sequence-independent cDNA synthesis and amplification combined with next-generation 454® pyrosequencing. A total of 4 novel nucleotide changes, which also resulted in amino acid changes, were detected in genome segment 7 (NSP3), genome segment 9 (VP7) and genome segment 10 (NSP4). In silico analysis indicated that none of the detected nucleotide changes, and consequent amino acid variations, had any significant effect on viral structure. Evolutionary analysis indicated that the sequenced rotavirus WaCS was closely related to the ParWa and VirWa variants, which were derived from the original 1974 Wa isolate. Despite serial passaging in animals, as well as cell cultures, the Wa genome seems to be stable. Considering that the current reference sequence for the Wa strain is a composite sequence of various Wa variants, the rotavirus WaCS may be a more appropriate reference sequence. The rotavirus Wa and SA11 strains were selected for plasmid-based expression of rotavirus proteins, under control of a T7 promoter sequence, due to the fact that they propagate well in MA104 cells and the availability of their consensus sequences. The T7 RNA polymerase was provided by a recombinant fowlpox virus. After extensive transfection optimisation on a variety of mammalian cell lines, MA104 cells proved to be the best suited for the expression rotavirus proteins from plasmids. The expression of rotavirus Wa and SA11 VP1, VP6, NSP2 and NSP5 could be confirmed with immunostaining in MA104 and HEK 293H cells. Another approach involved the codon-optimised expression of the rotavirus replication complex scaffold in MA104 cells under the control of a CMV promoter sequence. This system was independent from the recombinant fowlpox virus. All three plasmid expression sets were designed to be used in combination with the transcript-based reverse genetics system in order to improve the odds of developing a successful rotavirus reverse genetics system. Rotavirus transcripts were generated using transcriptively active rotavirus SA11 double layered particles (DLPs). MA104 and HEK293H cells proved to be the best suited for the expression of rotavirus transcripts although expression of rotavirus VP6 could be demonstrated in all cell cultures examined (MA104, HEK 293H, BSR and COS-7) using immunostaining. In addition, the expression of transcript derived rotavirus VP1, NSP2 and NSP5 could be confirmed with immunofluorescence in MA104 and HEK 293H cells. This is the first report of rotavirus transcripts being translated in cultured cells. A peculiar cell death pattern was observed within 24 hours in response to transfection of rotavirus transcripts. This observed cell death, however does not seem to be related to normal viral cytopathic effect as no viable rotavirus could be recovered. In an effort to combine the transcript- and plasmid systems, a dual transfection strategy was followed where plasmids encoding rotavirus proteins were transfected first followed, 12 hours later, by the transfection of rotavirus SA11 transcripts. The codon- optimised plasmid system was designed as it was postulated that expression of the DLP-complex (VP1, VP2, VP3 and VP6), the rotavirus replication complex would form and assist with replication and/or packaging. Transfecting codon- optimized plasmids first noticeably delayed the mass cell death observed when transfecting rotavirus transcripts on their own. None of the examined coexpression systems were able to produce a viable rotavirus. Finally, the innate immune responses elicited by rotavirus transcripts and plasmid-derived rotavirus Wa and SA11 proteins were investigated. Quantitative RT-PCR (qRT-PCR) experiments indicated that rotavirus transcripts induced high levels of the expression of the cytokines IFN- α1, IFN-1β, IFN-λ1 and CXCL10. The expression of certain viral proteins from plasmids (VP3, VP7 and NSP5/6) was more likely to stimulate specific interferon responses, while other viral proteins (VP1, VP2, VP4 and NSP1) seem to be able to actively suppress the expression of certain cytokines. In the light of these suppression results, specific rotavirus proteins were expressed from transfected plasmids to investigate their potential in supressing the interferon responses provoked by rotavirus transcripts. qRT-PCR results indicated that cells transfected with the plasmids encoding NSP1, NSP2 or a combination of NSP2 and NSP5 significantly reduced the expression of specific cytokines induced by rotavirus transcripts. These findings point to other possible viral innate suppression mechanisms in addition to the degradation of interferon regulatory factors by NSP1. The suppression of the strong innate immune response elicited by rotavirus transcripts might well prove to be vital in the quest to better understand the replication cycle of this virus and eventually lead to the development of a selection-free reverse genetics system for rotavirus. / PhD (Biochemistry), North-West University, Potchefstroom Campus, 2014

Reverse genetics is an innovative molecular biology tool that enables the manipulation of viral genomes at the cDNA level in order to generate particular mutants or artificial viruses. The reverse genetics system for the influenza virus is arguably one of the best illustrations of the potential power of this technology. This reverse genetics system is the basis for the ability to regularly adapt influenza vaccines strains. Today, reverse genetic systems have been developed for many animal RNA viruses. Selection-free reverse genetics systems have been developed for the members of the Reoviridae family including, African horsesickness virus, bluetongue virus and orthoreovirus. This ground-breaking technology has led to the generation of valuable evidence regarding the replication and pathogenesis of these viruses. Unfortunately, extrapolating either the plasmid-based or transcript-based reverse genetics systems to rotavirus has not yet been successful. The development of a selection-free rotavirus reverse genetics system will enable the systematic investigation of poorly understood aspects of the rotavirus replication cycle and aid the development of more effective vaccines, amongst other research avenues. This study investigated the importance of co-expressed rotavirus proteins in the development of a selection-free rotavirus reverse genetics system. The consensus sequences of the rotavirus strains Wa (RVA/Human-tc/USA/WaCS/1974/G1P[8]) and SA11 (RVA/Simian-tc/ZAF/SA11/1958/G3P[2]) where used to design rotavirus expression plasmids. The consensus nucleotide sequence of a human rotavirus Wa strain was determined by sequence-independent cDNA synthesis and amplification combined with next-generation 454® pyrosequencing. A total of 4 novel nucleotide changes, which also resulted in amino acid changes, were detected in genome segment 7 (NSP3), genome segment 9 (VP7) and genome segment 10 (NSP4). In silico analysis indicated that none of the detected nucleotide changes, and consequent amino acid variations, had any significant effect on viral structure. Evolutionary analysis indicated that the sequenced rotavirus WaCS was closely related to the ParWa and VirWa variants, which were derived from the original 1974 Wa isolate. Despite serial passaging in animals, as well as cell cultures, the Wa genome seems to be stable. Considering that the current reference sequence for the Wa strain is a composite sequence of various Wa variants, the rotavirus WaCS may be a more appropriate reference sequence. The rotavirus Wa and SA11 strains were selected for plasmid-based expression of rotavirus proteins, under control of a T7 promoter sequence, due to the fact that they propagate well in MA104 cells and the availability of their consensus sequences. The T7 RNA polymerase was provided by a recombinant fowlpox virus. After extensive transfection optimisation on a variety of mammalian cell lines, MA104 cells proved to be the best suited for the expression rotavirus proteins from plasmids. The expression of rotavirus Wa and SA11 VP1, VP6, NSP2 and NSP5 could be confirmed with immunostaining in MA104 and HEK 293H cells. Another approach involved the codon-optimised expression of the rotavirus replication complex scaffold in MA104 cells under the control of a CMV promoter sequence. This system was independent from the recombinant fowlpox virus. All three plasmid expression sets were designed to be used in combination with the transcript-based reverse genetics system in order to improve the odds of developing a successful rotavirus reverse genetics system. Rotavirus transcripts were generated using transcriptively active rotavirus SA11 double layered particles (DLPs). MA104 and HEK293H cells proved to be the best suited for the expression of rotavirus transcripts although expression of rotavirus VP6 could be demonstrated in all cell cultures examined (MA104, HEK 293H, BSR and COS-7) using immunostaining. In addition, the expression of transcript derived rotavirus VP1, NSP2 and NSP5 could be confirmed with immunofluorescence in MA104 and HEK 293H cells. This is the first report of rotavirus transcripts being translated in cultured cells. A peculiar cell death pattern was observed within 24 hours in response to transfection of rotavirus transcripts. This observed cell death, however does not seem to be related to normal viral cytopathic effect as no viable rotavirus could be recovered. In an effort to combine the transcript- and plasmid systems, a dual transfection strategy was followed where plasmids encoding rotavirus proteins were transfected first followed, 12 hours later, by the transfection of rotavirus SA11 transcripts. The codon- optimised plasmid system was designed as it was postulated that expression of the DLP-complex (VP1, VP2, VP3 and VP6), the rotavirus replication complex would form and assist with replication and/or packaging. Transfecting codon- optimized plasmids first noticeably delayed the mass cell death observed when transfecting rotavirus transcripts on their own. None of the examined coexpression systems were able to produce a viable rotavirus. Finally, the innate immune responses elicited by rotavirus transcripts and plasmid-derived rotavirus Wa and SA11 proteins were investigated. Quantitative RT-PCR (qRT-PCR) experiments indicated that rotavirus transcripts induced high levels of the expression of the cytokines IFN- α1, IFN-1β, IFN-λ1 and CXCL10. The expression of certain viral proteins from plasmids (VP3, VP7 and NSP5/6) was more likely to stimulate specific interferon responses, while other viral proteins (VP1, VP2, VP4 and NSP1) seem to be able to actively suppress the expression of certain cytokines. In the light of these suppression results, specific rotavirus proteins were expressed from transfected plasmids to investigate their potential in supressing the interferon responses provoked by rotavirus transcripts. qRT-PCR results indicated that cells transfected with the plasmids encoding NSP1, NSP2 or a combination of NSP2 and NSP5 significantly reduced the expression of specific cytokines induced by rotavirus transcripts. These findings point to other possible viral innate suppression mechanisms in addition to the degradation of interferon regulatory factors by NSP1. The suppression of the strong innate immune response elicited by rotavirus transcripts might well prove to be vital in the quest to better understand the replication cycle of this virus and eventually lead to the development of a selection-free reverse genetics system for rotavirus. / PhD (Biochemistry), North-West University, Potchefstroom Campus, 2014

This historical study analyses the holistic dynamics of Ethiopia, taking into account political, social, economic, cultural, religious, and media development aspects, with a focus on the three most recent governments (1930–2014), in relation to freedom of expression. The analysis indicates that the Feudalist-Imperial system was clearly the extension of centuries-old imperial hegemony which had used religious, cultural and patriotic hegemony to stifle freedom of expression. During the Socialist-Military regime every sphere of society, including acts of expression, were oriented towards the revolution and socialist political ideology. During the current ethnically based so-called Revolutionary-Democratic regime, freedom of expression has been stifled by means of legislation, government and party structures, complex surveillance, and social networks. While the instruments of repression have differed, relatively speaking, from government to government, the extent of repression has remained similar over a number of centuries. Threats to freedom of expression derive from rulers or governments, in which instances they are entrenched through policies, laws and bureaucracies, from religious and cultural hegemonies, from poverty and a related lack of education and access to information, and from conflicts, rivalry and wars. These threats have their origins in three main interrelated causal or determining factors, namely the Certainty–Uncertainty Dilemma, Ethno-Luminary Thought and Narcissism, which together form a pyramid beneath which freedom of expression in Ethiopia has been trapped. This pyramid is identified in the study as the Social Pyramid, or the Pyramid of Repression Instruments, and it in turn gives rise to an overall web of suppression, that is, the Pyramid Trap of Repression. The study concludes that the repression of freedom of expression in Ethiopia is likely to remain intact, insofar as the threats to freedom of expression and the factors giving rise to those threats persist. While limited gains concerning the right to freedom of expression are achieved periodically, these are routinely undone and rolled back, since the Pyramid Trap of Repression is not dismantled. / In hierdie historiese studie word die holistiese dinamika van Etiopië ontleed, met inagneming van politieke, sosiale, ekonomiese, kulturele, religieuse, en media-ontwikkelingsaspekte. Daar word op die drie mees onlangse regerings (1930–2014) gefokus, ten opsigte van vrye meningsuiting. Die ontleding dui daarop dat die feodalisties-imperialistiese stelsel duidelik die uitbreiding van eeue-oue imperialistiese hegemonie was wat religieuse, kulturele en patriotiese hegemonie gebruik het om vrye meningsuiting te onderdruk. Gedurende die sosialisties-militêre regime was elke sfeer van die samelewing, insluitende dade van uitdrukking, georiënteer tot die revolusie en sosialisties-politieke ideologie. Tydens die huidige, etnies gebaseerde sogenaamde revolusionêr-demokratiese regime, is vrye meningsuiting onderdruk deur wetgewing, regering- en partystrukture, komplekse bewaking, en sosiale netwerke. Hoewel die instrumente van onderdrukking relatief gesproke verskil het van regering tot regering, het die mate van onderdrukking oor ʼn aantal eeue heen soortgelyk gebly. Bedreigings vir vrye meningsuiting is afkomstig van heersers of regerings (en in sulke gevalle word hulle beveilig deur beleide, wette en burokrasieë), van religieuse en kulturele hegemonieë, van armoede en ʼn verwante gebrek aan opvoeding en toegang tot inligting, en van konflikte, mededinging en oorloë. Hierdie bedreigings het ontstaan vanweë drie vernaamste kousale of bepalende faktore wat onderling verwant is, naamlik die sekerheid-onsekerheid-dilemma, etno-voorligter-denke en narsisme, wat gesamentlik ʼn piramide vorm waaronder vrye meningsuiting in Etiopië vasgevang is. Hierdie piramide word in die studie as die sosiale piramide, of die piramide van onderdrukkingsinstrumente, geïdentifiseer, en dit lei op sy beurt tot ʼn algehele web van onderdrukking – die piramidelokval van onderdrukking. Die gevolgtrekking van die studie is dat die onderdrukking van vrye meningsuiting in Etiopië waarskynlik onaangeroer gaan bly, so lank as wat die bedreigings vir vrye meningsuiting en die faktore wat tot daardie bedreigings aanleiding gee, onveranderd bly. Hoewel beperkte suksesse van tyd tot tyd behaal word rakende die reg tot vrye meningsuiting, word sulke prestasies dikwels ongedaan gemaak, omdat die piramidelokval van onderdrukking nie afgebreek word nie. / Communication Science / D. Litt. et Phil. (Communication)