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Regulation of tryptophan-2,3-dioxygenase and pineal indoleamines by selected tryptophan derivatives and antidepressants

- Walsh, Harold Archibold

  • Authors: Walsh, Harold Archibold
  • Date: 1997
  • Subjects: Antidepressants Tryptophan -- Physiological effect Tryptophan -- Therapeutic use Depression, Mental -- Treatment
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:4017 , http://hdl.handle.net/10962/d1004077
  • Description: The regulation of tryptophan-2,3-dioxygenase (TDO) (EC 1.13.1.12) and, to a lesser extent, pineal indoleamines, both in vitro and in vivo, is examined in this study. Rat liver TDO is a cytosolic enzyme which plays a crucial role in the regulation of circulating tryptophan (TRP) levels. Stimulation of this enzyme by heme enhances the catabolism of TRP, making less TRP available for uptake into the brain and other tissues, and for protein synthesis. At pH 7, the enzyme has an approximate Km of 100μM, is subject to substrate inhibition immediately beyond Sopt([S] at Vmax), and response of the enzyme is cooperative in both uninhibited and inhibited regions. Hill analysis of the uninhibited region reveals a biphasic plot and two classes of binding sites. Negative cooperativity is brought about through deprotonation of the enzyme. Substrate iphibition also occurs at both acidic and basic pH values with concomitant shifts in Sopt. The results obtained indicate that substrate inhibition could be an additional mechanism whereby the flux through the TRP-kynurenine pathway is regulated. TDO is subject to a diurnal rhythm, with peak activity during the pre-dark period and the loweSt activity towards the end of the dark period. It is possible that the enzyme controls the synthesis of the neurotransmitter serotonin (5-HT), and that the circadian rhythm in TDO activity is due to the endogenous rhythm of melatonin (aMT) production by the pineal gland. In the present study, aMT displaces TRP from bovine serum albumin (BSA) in vitro, and it is therefore possible for the indoleamine to regulate the availability of TRP for uptake into the brain for conversion to its derivatives. Chronic intraperitoneal administration of aMT affects physiological hepatic parameters in rats, such as TDO activity and stromal fatty acid composition, whilst no observable effect is demonstrable with respect to protein synthesis, nucleic acid metabolism, membrane fatty acid composition and pineal indole biosynthesis. On the other hand, chronic treatment of rats with antidepressants, the tricyclic desmethylimipramine (DMI) and the selective serotonin reuptake inhibitor (SSRI), fluoxetine, reveals significant negative alterations in TDO concentrations and pineal indole amine synthesis. Combining aMT with any of these two drugs normalises the activity of the hepatic enzyme. DMI is found to be an effective inhibitor of TDO in the micromolar range in vitro, and also affects total enzyme concentrations in vivo. Fluoxetine has no effect on TDO in vitro, but in vivo also reduces total enzyme levels in the liver. However, the SSRI does not affect conjugation between apo- and holoenzyme. Instead, it decreases extant holoenzyme levels. Indoleamine synthesis by the pineal gland, in organ culture, is altered by both antidepressants, although in different ways. DMI increases N-acetylserotonin levels and reduces the output of methoxyindole acetic acid and meth6xytryptophol. Fluoxetine treatment markedly reduces aMT concentrations and also brings about high levels of the 5-HT catabolites, 5-hydroxytryptophol and 5-hydroxyindole acetic acid. Insulin also lowers aMT synthesis significantly in pineal organ cultures, via a mechamsm that involves inhibition of the enzyme, N-acetyl transferase, that regulates aMT synthesis. The effects of insulin on pineal indole metabolism are due to the observation that a carbohydrate rich diet which induces insulin release elevates plasma TRP and brain 5-HT, but has no effect on pineal TRP and indole amine synthesis. It could thus be possible for insulin to have an effect on the pineal, since the latter is outside the blood brain barrier. The finilings of this study support the biogenic amine deficiency hypothesis, implicating some of the major biogenic amines such as noradrenaline (NA), 5-HT and aMT in depression. There is believed to be a deficiency of NA and 5-HT at their respective synapses in the depressed state. The drug DMI could act, firstly, by inhibiting TDO and thus increasing plasma TRP levels, and could, secondly, stimulate NA release and inhibit NA reuptake at the pineal membrane. The combined effect would be to enhance aMT synthesis, with eventual remission. Fluoxetine, on the other hand, appears to utilize a slightly different mode of action to DMI, which seems to focus on the preservation of 5-HT. The fact that aMT counteracts the effects of both antidepressants, and restores the activity of TDO to that of the controls, is also consistent with the observation that the therapeutic action of drugs such as these coincides willi the restoration of normal plasma levels of the neurohormone in depressives. In view of the biogenic amine deficiency hypothesis of depression and the contentious claim that TDO is the major peripheral determinant of brain TRP, brain 5-HT and ultimately aMT, the regulation of TDO is investigated and discussed. The study concludes that TDO activity is regulated by a number of endogenous compounds which are mainly derivatives of TRP, such as aMT and oxidized nicotinamide adenine dinucleotide and exogenous substances, of which DMI and fluoxetine are but two. In addition, modulation of IDO activity in depression appears to be an important aspect of antidepressant action. aMT, the product of the pineal gland, also has the potential to increase plasma TRP and hence forebrain TRP levels, and ultimately 5-HT concentrations, firstly by displacing TRP from serum albumin and secondly by inhibiting TDO.
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  • Date Issued: 1997

Reproductive and feeding biology of the Natal mountain catfish, Amphilius natalensis (Siluriformes: Amphiliidae)

- Marriott, Michael S, Booth, Anthony J, Skelton, Paul H

  • Authors: Marriott, Michael S , Booth, Anthony J , Skelton, Paul H
  • Date: 1997
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/125837 , vital:35823 , https://doi.10.1023/A:1007361511052
  • Description: The family Amphiliidae comprises nine genera and about 60 species. Only five species are found in southern Africa, three of which belong to the genus Amphilius (Skelton 1993). These soft-bodied catlets inhabit clear, fast flowing mountain streams where they live amongst cobbles, feeding predominantly on benthic invertebrates (Crass 1964, Skelton 1993). The Natal mountain catfish, A. natalensis Boulenger, 1917, is a small, nocturnal species with a restricted distribution along the eastern seaboard of southern Africa. It occurs in mountain streams from the Umkomaas River north to the Limpopo system in South Africa. It is also present in the Marozi River, a tributary of the Zambezi River in Zimbabwe and in the Ruo River, Malawi (Skelton 1984, 1993). Skelton (1993) suggested that predation by introduced trout species has led to scarcity of A. natalensis in many streams. In spite of this, no studies on the biology of this catfish species have been published. This study presents the first quantitative information on the biology of an amphiliid catfish, A. natalensis including gametogenesis, spawning seasonality, size-at-maturity, adult sex ratio and diet.
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  • Date Issued: 1997

Research report

- NALEDI

  • Authors: NALEDI
  • Date: 1997
  • Subjects: NALEDI
  • Language: English
  • Type: text
  • Identifier: http://hdl.handle.net/10962/151396 , vital:39063
  • Description: The intention of this paper is to highlight debates and issues regarding the use of guota systems in strengthening women’s leadership in the labour movement. The paper is aimed at broadening the debate from mere acceptance or rejection of the guota. Debates on the use of guotas tend to be heated and controversial and can lose sight of the central objective, which is the development of strategies for women’s empowerment. A large proportion of trade unions internationally have adopted forms of the quota system as a strong measure to deal with the ongoing under-representation of women in leadership. The quota system has also been introduced effectively in a number of parliaments all over the world, including South Africa. The countries with the highest representation of women in parliament have all had to use quotas to achieve this. The paper draws from a review of some of the international literature, as well as interviews undertaken with trade unionists and parliamentarians (see Appendix A for a list of interviewees). This paper will also highlight some examples where quota systems have been adopted, including three COSATU affiliates, namely CWIU, NEHAWU and SAMWU.
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  • Date Issued: 1997

Resisting racism: a teachers' guide to equality in education

- Eyber, Carola, Dyer, Dorothy, Versfeld, Ruth

  • Authors: Eyber, Carola , Dyer, Dorothy , Versfeld, Ruth
  • Date: 1997
  • Subjects: Discrimination in education -- South Africa -- Prevention , Educational equalization -- South Africa , Multicultural education -- South Africa , Racism -- South Africa , School integration -- South Africa
  • Language: English
  • Type: text , book
  • Identifier: http://hdl.handle.net/10962/73690 , vital:30217 , 1874864462
  • Description: While South Africa's new democracy has meant that schools are now open to all, there is still racism in our schools. The changes in schools have in some cases exacerbated racial tensions and mistrust. Teachers everywhere are struggling with the changing dynamics of their classrooms and schools. There is much talk about how to work against racism. Various programmes and schools have developed different ways of dealing with it. All have particular ideas about how best to counter it. Resisting Racism aims to discuss and understand the beliefs and assumptions underlying many of these approaches. We look at the theories behind the different practices, present a range of ideas to illustrate them and consider their limits and possibilities. The book is a starting point for teachers and schools to reflect on their practices and help them to work out new strategies in the classroom and school. The approaches described will probably work best if they are used together, specially adapted to the specific context in which they are to be used. In the first part of the book we look at psychological and sociological explanations of why people are racist. Four different ways of looking at the issues are described. Each suggests practical ways of dealing with racism in the classroom and in the school. Chapter Three, on multi-cultural and anti-racist education, covers similar ground but from a slightly different angle, looking at curriculum debates about race, culture and equality. The final section looks at the concerns that many teachers have every day, such as "How can I deal with the language problem?" and "How can I involve parents in these issues?" In discussing these questions we have tried to use current theory to inform the practical ideas suggested. You will discover that this book is not neutral. It does have a point of view. It seeks to explain the limitations of assimilating students into a status quo and asks that schools take a critical look at their policies and practices. There are no easy answers or quick solutions. However thinking about and understanding the issues of racism and the ways in which it may be resisted can only bring us closer to positive change.
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  • Date Issued: 1997

Responding to literature: empowering girls to speak with their own voices in a multicultural context

- Foster, Lesley

  • Authors: Foster, Lesley
  • Date: 1997
  • Subjects: Reader-response criticism--South Africa Multicultural education
  • Language: English
  • Type: Thesis , Masters , MEd
  • Identifier: vital:1742 , http://hdl.handle.net/10962/d1003626
  • Description: The purpose of this study was to investigate whether the space provided by a readerresponse transaction between girls and the text, Roll of Thunder, Hear My Cry (Taylor 1977) .. empowered pupils to tell their own stories. It also sought to identify ways in which the problems and possibilities perceived by these pupils might guide curriculum decisions in a transforming education system. In addition to engaging in reader-response activities around the text, drama and videos providing social context were integral to the programme. Related work in the subject areas of history and lifeskills was also undertaken. Data was drawn from pupils' reading journals, responses to specific passages, transcripts of small group discussions, and interviews. The study is ethnographic in nature and all the data qualitative. Theoretical insights were drawn from the felds of cultural studies, postmodern criticism, and postructural modes of cultural and social analysis inasfar as they illuminate and inform the relationship between language, knowledge and power. The research was conducted in an historically white, girls' school which adopted a nonracial admissions policy in January 1991. Despite the fact that existing traditions and values of the the school to a very large extent influence what is taught, the data suggests that pupils were becoming agents in their own learning and were taking up multiple identities both within and without the world of the school.
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  • Date Issued: 1997

Rhodes University Annual Report 1997

- Rhodes University

Rhodes University Graduation Ceremony 1997

- Rhodes University

  • Authors: Rhodes University
  • Date: 1997
  • Language: English
  • Type: text
  • Identifier: vital:8131 , http://hdl.handle.net/10962/d1006776
  • Description: Rhodes University 1997 Graduation Ceremony [at] 1820 Settlers National Monument Friday, 18 April at 10:30 a.m., 08:15 p.m. [and] Saturday, 19 April at 10:30 a.m. , Rhodes University 1997 Graduation Ceremony City Hall, East London Friday, 9 May at 6:00 p.m.
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  • Date Issued: 1997

SA in the global economy

- TURP

  • Authors: TURP
  • Date: 1997
  • Subjects: TURP
  • Language: English
  • Type: text
  • Identifier: http://hdl.handle.net/10962/160942 , vital:40569
  • Description: There are growing ties in the world between countries which coincides with current major social, political and economic restructuring. This is what many refer to as “globalisation”. Globalisation is a process which involves greater influence by global forces on individual countries such as South Africa. It means that global rules are being set which impact on: the policies of our government, the way companies in South Africa make their plans, the way that trade unions, community organisations and development organisations take up issues, and the way individuals make a living in the country. Globalisation has raised new and difficult issues for the labour movement and have thrown up new forms of struggle. Some of these issues have stumped and even demobilised some unionists in South Africa and internationally. Some feel that globalisation cannot be challenged and that there is no alternative. Others feel that we have not become powerless and that there are ways to fight its negative effects. Turp has published a book on these issues entitled, South Africa in the Global Economy: understanding the challenges, working towards alternatives. One of the main purposes of the book is to clarify what the new complex and challenging issues are. By doing this, we hope to clarify what we are up against.
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  • Date Issued: 1997

Share-net: a case study of environmental education resource material development in a risk society

- Taylor, Robert James

  • Authors: Taylor, Robert James
  • Date: 1997
  • Subjects: Environmental education Environmental education -- South Africa Environmental education -- Activity programs -- South Africa Environmental education -- South Africa -- Information resources
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:1765 , http://hdl.handle.net/10962/d1003650
  • Description: This narrative study reviews the development of Share-Net, an informal resource materials network, located within the developing environmental education activities of the Wildlife and Environment Society of South Africa. Historical shaping factors within the Society are discussed and changing views on conservation, environmental education and research are described. Rather than the research process being a utilitarian and outside endeavour for clarifying and monitoring, the research orientation of this study is one of grounded activity within and integrally part of processes of change. Within a developing story of resource materials and workshops, themes are traced and emergent tensions are critically reviewed. Teacher workshops from 1981 until 1995 are analysed and developing orientations are described. Within this review changes are evident from an orientation of 'us' informing 'them' to joint, collaborative endeavours within the development and use of resource materials. The study reviews and illuminates the Share-Net project around questions of project orientation and management and this is done through the narration of case studies. Principles and patterns emerging within these are examined to guide future resource development projects. Popularist notions of networking and structural functionalist notions of social change are also examined. Grand, modernist strategies designed to cause change in others are questioned and the role of small-scale nodes of resource material activity cooperating within an open network are clarified as useful alternatives. Local resourcing centres such as these have proved useful in supporting teachers in the development, use and adaptation of resource materials. The study also examines income and expenditure of the Share-Net project since 1988 to review economic sustainability. A case is made for sustaining the project conceptually and financially through the sales of products and services rather than through external donor sources. Finally the study raises questions and challenges within the project and proposes guiding frameworks for future review, in action, as the story continues.
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  • Date Issued: 1997

Solid state thermal decomposition of amide complexes of nickel(II) chloride

- Nelwamondo, Aubrey Ndifelani

  • Authors: Nelwamondo, Aubrey Ndifelani
  • Date: 1997
  • Subjects: Decomposition (Chemistry) Materials -- Thermal properties Amides
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:4345 , http://hdl.handle.net/10962/d1005008
  • Description: The thermal decompositions of a series of amide complexes of nickel(II) chloride have been studied. Thermochemical, kinetic, structure and solid-state stability correlations have been investigated. Complexes containing homologous amide ligands (L) of the form NiLCℓ₂, Ni₃L₂Cℓ₆, Ni₃LCℓ₆, NiL₂Cℓ₂(2H₂0) and ML₂Cℓ₂ (where M = Ni(II), Co(II) or Cu(II)) have been prepared. Chemical analysis, spectral and thermogravimetric measurements were used to characterize the complexes and their decomposition stoichiometries. Three sets of reactions were identified as yielding stable products in a single step: (i) NiLCℓ₂ (s) → NiCℓ₂ (s) + L (g) (ii) Ni₃LCℓ₆ (s) → 3NiCℓ₂ (s) + 2L (g) (iii) Ni₃LCℓ₆ (s) → 3NiCℓ₂ (s) + L (g) Characterization of the processes in the ML₂Cℓ₂ and NiL₂Cℓ₂(2H₂0) complexes was not straightforward. Reaction enthalpies (ΔH) were determined using DSC. The orders of the reaction onset temperatures (Tc), peak temperatures (Tmax) and ΔHL values for the NiCℓ₂ system were: N-methylacetamide < acetamide < N-methylformamide, suggesting the importance of steric hindrance of the methyl-substituent groups in the amide skeleton. In the Ni₃LCℓ₆, NiL₂Cℓ₂(2H₂0) and ML₂Cℓ₂ systems no simple orders could be deduced. The Te and Tmax sequences obtained from analogous metal(II) chloride complexes indicated that the copper(II) complexes were the least stable. The kinetics of the loss of L from NiLCℓ₂ complexes were investigated using isothermal TG, non-isothermal TG and DSC measurements. The contracting geometry models described the course of the decompositions in the most satisfactory manner. Apparent activation energies ( Ea) were estimated from Arrhenius plots of rate coefficients from: (i) an approximate zero-order relationship, (ii) the contracting-area (R2) and contracting-volume (R3) equations, (iii) a new empirical (B2) expression, (iv) the half-life ( 1/t₀.₅) and (v) the characteristic feature of the rate-time curve ( 1/tmax/2 ). The non-dependence of Ea on the rate equation used supports the reliability of the kinetic parameters. Non-isothermal experiments were analyzed by the Coats-Redfern, the modified BorchardtDaniels and the Kissinger methods. Arrhenius parameters were in keeping with results from the isothermal kinetic measurements. The values of Ea obtained for the NiLCℓ₂ system increased with an increase in basicity of the amide ligands. No straightforward correlation was found between Ea and Te, Tmax, ΔHL or spectral properties.
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  • Date Issued: 1997

Somagwaza

- Performer not specified, Composer not specified, Dargie, Dave

Somagwaza

- Performer not specified, Composer not specified, Dargie, Dave

Somagwaza

- Performer not specified, Composer not specified, Dargie, Dave

Somagwaza

- Hogsback festival participants, Composer not specified, Dargie, Dave

Somagwaza

- Performer not specified, Composer not specified, Dargie, Dave

South African English: oppressor or liberator?

- Silva, Penny

  • Authors: Silva, Penny
  • Date: 1997
  • Language: English
  • Type: text , conference publication
  • Identifier: vital:7013 , http://hdl.handle.net/10962/d1013236 , https://www.ru.ac.za/media/rhodesuniversity/content/dsae/documents/articles/Silva_article.pdf
  • Description: preprint , [From Conclusion] The advent of Nelson Mandela’s government in 1994 brought about rapid changes in the balance between English and Afrikaans in government and the media, and also increased the use of African languages on television. English remains the politically ‘neutral’ language for public use: President Mandela’s speeches are almost invariably in English; national conferences are held largely in English; in Parliament, although all official languages may be used, English is predominant; tertiary education is in English, with the exception of some of the Afrikaans-language campuses. Multilingualism is entrenched in the constitution, and supported as an ideal, but with its massive translating, interpreting, and printing implications, it is beyond the reach of the South African economy while there are urgent needs in health, housing, and education. The status of English as an international language, and as one which is politically more neutral than any other South African language, and its choice by the ANC, seems to ensure its ever-increasing dominance at a national level. At this level English is a national asset and ‘liberator’, in that it offers international access and a tool for communication between language groups. However, this dominance is likely to result in a growing resentment of English, particularly among those who have an ‘old’ political agenda, or who do not have access to becoming proficient in the language. To these South Africans, English will certainly be seen as ‘oppressor’. English in South Africa has long since passed out of the hands of mother-tongue speakers. With its increased public use by the new black elite, and in the electronic media, it seems likely that standard SAE is entering a period of accelerated change. This has already led to an intolerant reaction from some conservative English-speakers, and ‘standard’ is likely to become an increasingly difficult issue. If English is to be seen as ‘liberator’ by the average second-language speaker, the attitudes of mother-tongue speakers are significant. Triumphalism, arrogance, and irritation towards second-language speakers result in resentment. If it is to be ‘liberator’, English should be a resource to be appropriated and owned by all South Africans, not just the elite, to be used as a gateway to the wider world. For this to happen, creative solutions (and massive expenditure) would have to be applied to the teaching of English, particularly in black rural schools. Simultaneously, SAE will hopefully be claimed as the colourful and particularly local creation of an increasingly multi-ethnic company of first-, second-, and third-language speakers, and be used even more extensively than at present as the national language of communication. If it offers itself (and is perceived) as servant and liberator rather than oppressor, English will provide the linguistic ‘glue’ to bond a diverse and complex society.
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  • Date Issued: 1997

Southern African Journal of Gerontology, volume 6, number 1, April 1997

- Ferreira, Monica (editor), Moller, Valerie, HSRC/UCT Centre for Gerontology

  • Authors: Ferreira, Monica (editor) , Moller, Valerie , HSRC/UCT Centre for Gerontology
  • Date: 1997
  • Subjects: Gerontology -- South Africa , Older people -- Care -- South Africa
  • Language: English
  • Type: Text
  • Identifier: vital:8074 , http://hdl.handle.net/10962/d1012868
  • Description: [From Editorial] A variety of papers covering interesting and relevant topics and emanating from several countries are included in this number. Togonu-Bickersteth examines levels of satisfaction with care received from sons and daughters of older Yoruba in rural Nigeria. She finds that contrary to expectations, older women are more satisfied than older men with the assistance received from children. Makoni examines the effects of Alzheimer's disease as the disease progresses on the conversational ability of an older second-language speaker. Cattell reports on exploratory research among Zulu grandmothers and granddaughters in KwaZulu-Natal and finds that older women continue to have important roles in the socialization of granddaughters, especially regarding sexual behaviour. Van Dokkum makes out a case for a durable power of attorney, not yet provided for in South African legislation, which can help to protect older citizens against malpractices or exploitation when, because of impaired mental functioning, they are no longer able to look after their affairs. Lefroy gives an update on the Special Dementia Unit as an alternative residential care facility for afflicted older Australians and examines the advantages of this type of accommodation for individuals. their families and society. Finally, Moller reviews a book written by Nana Araba Apt of Ghana. entitled Coping with old age in a changing Africa. She concludes that readers will learn much from Apt's ideas on building on indigenous institutions to meet the challenges of ageing in Africa.
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  • Date Issued: 1997

Southern African Journal of Gerontology, volume 6, number 2, October 1997

- Ferreira, Monica (editor), Moller, Valerie, HSRC/UCT Centre for Gerontology

  • Authors: Ferreira, Monica (editor) , Moller, Valerie , HSRC/UCT Centre for Gerontology
  • Date: 1997
  • Subjects: Gerontology -- South Africa , Older people -- Care -- South Africa
  • Language: English
  • Type: Text
  • Identifier: vital:8075 , http://hdl.handle.net/10962/d1012870
  • Description: [From Editorial] This Special Issue of the Journal comprises a selection of papers based on research on ageing in African countries, which were read at the Third Global Conference. The papers were revised and peer reviewed prior to acceptance by the Journal. The theme of the Special Issue is "Ageing in urban and rural Africa." Each of the papers included in the issue deals with a situation of ageing-in-place, a late-life migratory pattern, or the impact, or implications of social forces and social change on older Africans, in either an urban and/or a rural setting, or in both types of settings in Africa. The papers also draw together the main sub-themes and strands of the conference, particularly those relating to the family, ubuntu, urbanization, AIDS, and income security and poverty.
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  • Date Issued: 1997

Structural and stereochemical investigations of terrestrial and marine pyrone metabolites

- Collett, Lynne Alison

  • Authors: Collett, Lynne Alison
  • Date: 1997
  • Subjects: Metabolites , Stereochemistry , Siphonaria
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4348 , http://hdl.handle.net/10962/d1005013 , Metabolites , Stereochemistry , Siphonaria
  • Description: This thesis presents an investigation into the chemistry of 6 substituted 5, 6-dihydro-a-pyrone compounds. A comprehensive review of these compounds was published in 1989 and the subsequent literature is covered in an updated review presented below. Eight 6-substituted 5,6-dihydro-a-pyrone metabolites from three different South African plant species Cryptocarya latijolia, Syncolostemon densiflorus, and Syncolostemon argenteus have been the subject of structural and stereochemical investigations. The absolute stereochemistry of the known compound "triacetate" from C. latijolia has been established as 6R-[2R,4S,6S-(triacetyloxy)heptylJ-5,6-dihydro-2H-pyran-2-one (74) using CD and acetonide formation with subsequent application of the modified Moshers method. The absolute stereochemistry of the related metabolite "diacetate", also from C. latijolia, has been assigned as 6R-[2S,4S-diacetyloxypentylJ-5,6-dihydro-2H-pyran-2-one (76). In addition, the outstanding stereochemistry at C-5' in syndenolide, from S. densiflorus, followed from conversion to its diacetonide and subsequent NMR analysis. Syndenolide is therefore 6R-[5S-(acetoxy)-IR,2R,3S-(trihydroxy)-heptylJ-5,6- dihydro-2H -pyran-2-one. The genus Syncolostemon has proved to be a rich source of a-pyrone compounds and the chemistry of S. argenteus, not investigated previously, was examined as part of an ongoing search for new 5,6-dihydro-a-pyrones. The study yielded five new a-pyrone natural products, synargentolide A-E. The structure of synargentolide A (82) has been assigned as 6R[4R,5R,6S-triacetyloxy-lE-heptenylJ-5,6-dihydro-2H-pyran-2-one using CD and NMR techniques. The structures of synargentolide B (87), C (92) and E (94) also followed from a detailed NMR analysis and the stereochemistry tentatively assigned based on CD and NMR data. Synargentolide D (93) was thermally unstable, and a paucity of material prevented stereochemical investigations, however the structure was determined from initial NMR analysis. The marine molluscs of the genus Siphonaria have only become the subject of chemical studies in the last fifteen years. These molluscs characteristically produce polypropionate type natural products. A review of Siphonarian polypropionate metabolites containing a pyrone functionality is presented. Examination of an endemic South African species Siphonaria serrata yielded one novel polypropionate metabolite containing a ),-pyrone functionality, siserrone A (131). The structure of this compound was unambiguously established using standard NMR experiments. The relative stereochemisty of the hemi-ketal moiety was assigned from a careful analysis of the ROESY NMR spectrum and the stereochemisty of the acyclic portion determined from a comparison of the 13C and 'H NMR data of a degradation product with the corresponding data of a synthetic compound. It was also established that the modified Moshers method could not be used to determine the absolute stereochemistry of the secondary hydroxy I substituent at C-11. The absolute stereochemistry of 131 was thus assigned in accordance with the proven stereochemistry of Siphonarian metabolites.
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  • Date Issued: 1997

Struggle in discourse the International's discourse against racism in the labour-movement in South Africa (1915-1919)

- Caldwell, Marc Anthony

  • Authors: Caldwell, Marc Anthony
  • Date: 1997
  • Subjects: International (Johannesburg, South Africa) -- History , International Socialist League (S.A.) -- History , South African newspapers -- Language , Mass media and race relations -- South Africa , Mass media and language -- South Africa , Labor unions and mass media -- South Africa
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:3419 , http://hdl.handle.net/10962/d1002872 , International (Johannesburg, South Africa) -- History , International Socialist League (S.A.) -- History , South African newspapers -- Language , Mass media and race relations -- South Africa , Mass media and language -- South Africa , Labor unions and mass media -- South Africa
  • Description: The International, as the weekly newspaper of the International Socialist League, articulated from 1915 to 1919 an ideology which stood opposed both to organised labour and nationalist movements in South Africa. This situation reflected significant historical struggles during this period, which constitutes essential background to the discourse of the International. The International's writers opposed the institution of trade unionism in the labour movement because it was fragmented on the lines of skill and race. They opposed both the National Party and the South African Native National Congress because they advocated racial (and national) rather than working class interests. Instead, these writers, according to their international socialist paradigm, advocated a working class united irrespective of race and skill at the level of industry. To analyse these ideological positions, discourse analysis provides a fruitful method for locating its dynamics in relation to other positions and extra-ideological (contextual) practices: The International's writers g~nerated a socialist position against racism by engaging in an ideological struggle in discourse. They articulated their anti-racist position from international socialism's critique of the 'languages' of both militarism and trade unionism in the discourse of labour. Within the discourse of militarism, the working class was signified as divided between hostile nations. These writers applied this as a metaphor to the division of the local labour movement and criticised the latter accordingly. In their view, just as workers were divided between the nations (nationalism), so they were divided within the nation (racism) in South Africa. One context cohered with the other, and both agreed with imperatives of international capitalism. This was fundamentally opposed to the principles of international socialism which characterised the International's discourse. Within the dominant discourse oflabour, workers were signified as divided between different trade unions on the basis of skills. Furthermore, in the South African context, trade unions organised only white workers, and ignored the far larger proportion of black labour. In this context, the International advocated industrial unionism, and criticised the narrow base of the white trade unions for fragmenting and weakening the working class in South African. The International's writers were thus led by the discourse of international socialism to a new discourse, whereby not white workers alone, but a racially-united working class movement would be the key to a socialist future in South Africa. Their struggle entailed a bid in and over discourse to rearticulate the sign of the 'native worker' within their own discourse as the dominant discourse type. Underpinning their struggle was a fundamental opposition to capitalist class relations.
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  • Date Issued: 1997
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