Cognitive restructuring through guided imagery : lessons from Gestalt therapy
- Authors: Edwards, David J A
- Date: 1989
- Language: English
- Type: Text
- Identifier: vital:6281 , http://hdl.handle.net/10962/d1013181
- Description: [Summary] In this chapter, a guided imagery method used in gestalt therapy was described in detail and analyzed into its specific components. The basic principles underlying the imagery work were shown to be analogous to those upon which standard cognitive therapy is founded, and this was illustrated by means of case examples, first from one of Perls' dreamwork seminars and then from the author's case files. It was shown how the method could be used to elicit the idiosyncratic meanings of the client in relation to a specific theme and to identify core dysfunctional assumptions. Illustrations were given of specific techniques that could be employed to challenge and restructure these cognitions. The benefits of the imagery modality are that it provides: (1) access to cognitions underlying emotional responses that may be difficult to identify through questioning, (2) a holistic presentation of networks of beliefs, and (3) a means of keeping the client in contact with avoided painful affect. Once a good conceptualization of the client's problem has been achieved, guided imagery provides a modality within which specific strategies for cognitive restructuring can be facilitated through guided discovery. Therapists who are willing to explore this modality and find an aptitude for it will be gaining access to something that will greatly enrich their potential for helping and can provide exciting avenues for developing their own creativity in the challenging work of enabling clients to identify and free themselves from dysfunctional personal meaning systems.
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- Date Issued: 1989
Comparison of different notions of compactness in the fuzzy topological space
- Authors: Morapeli, E Z
- Date: 1989
- Subjects: Fuzzy mathematics Fuzzy topology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5393 , http://hdl.handle.net/10962/d1001982
- Description: Various notions of compactness in a fuzzy topological space have been introduced by different authors. The aim of this thesis is to compare them. We find that in a T₂ space (in the sense that no fuzzy net converges to two fuzzy points with different supports) all these notions are equivalent for the whole space. Furthermore, for N-compactness and f-compactness (being the only notions that are defined for an arbitrary fuzzy subset) we have equivalence under a stronger condition, namely, a T₂ space in the sense that every prime prefilter has an adherence that is non-zero in at most one point
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- Date Issued: 1989
Cross-cultural communication in a north-eastern Cape farming community:
- Authors: Kaschula, Russell H
- Date: 1989
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/175313 , vital:42564 , https://doi.org/10.1080/02572117.1989.10586786
- Description: Cross-cultural communication is dealt with and more specifically, the communicative competence of 15 white English-speaking farmers when they speak Xhosa to their labourers is assessed. This research was conducted in the Elliot, Ugie, and Maclear areas of the north-eastern Cape. A broad sociolinguistic framework drawing on both ethnographic and ethnomethodological principles was used; complications caused by cross-cultural differences which are reflected in language, and which may lead to possible communication breakdown, were isolated. The actual analysis of speech in terms of ethnomethodological principles, such as turn-taking and the co-operative principle, was undertaken.
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- Date Issued: 1989
Educare work in Ciskei with special reference to the Keiskammahoek district
- Authors: Oosthuysen, Lucia
- Date: 1989
- Subjects: Educare , Education, Preschool -- South Africa -- Ciskei , Education, Primary -- South Africa -- Ciskei , Readiness for school -- South Africa -- Ciskei
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: vital:1356 , http://hdl.handle.net/10962/d1001422
- Description: High drop-out rates in the sub-standards in developing countries prompted the researcher to investigate preschool education in first and third world countries, and attend to the related problem of school readiness. The rapidly expanding Educare preschool project in the rural area ot Keiskammahoek in Ciskei was investigated as an example ot community-based low-cost preschool education. A final sample of 41 children who had attended Educare Centres were matched to a control group on age, sex, primary school (where possible), and breadwinner's occupation. The Abbreviated Aptitude Test for School Beginners (standardised on Xhosa-speaking school beginners) was used to test tor significant differences between the two groups six to seven weeks atter school entry. A t-test was used on raw scores and chi-squared tests on staves. No signiticant difference was found between the means of the experimental and control groups. On a subjective rating scale for general-linguistic development and socio-emotional adjustment, no significant difference between means of the experimental and control groups was found. The experimental group's tailure to perform better than the control group, could be ascribed to various reasons, amongst others, the possible shortcoming that the pairs were not matched on intelligence, severe lack ot equipment in Educare Centres, large numbers of children in the majority of groups, uniform programmes for a wide age range, irregular attendance ot children, the low level of training of supervisors and poor home conditions. Scholastic abilities of school beginners in the Keiskammahoek District, as tested, were poor. Results deviated grossly from standardised norms. The expected percentage for the combined categories Very Weak and Weak is, tor instance, 31%; in this investigation, however, 73% of the testees fell in these two classes. Chronologically older children generally performed better. A highly significant difference existed between testees under six years and those over six years. This investigation indicated the need for better organised preschool education in rural areas in Ciskei. proposals with substantial financial implications are: Better training of para-professional staff by qualified staff. Training of qualified staff to provide expertise in preschool education in Ciskei. Provision of sufficient educational materials by Government subsidies and private sponsors. Institution of bridge classes by the Ciskei Department of Education to promote school readiness. Suggestions without financial implications include: An investigation of regulations regarding entrance age for basic education. Only in exceptional cases should children under six be admitted. Daily programmes in Educare Centres geared towards learning readiness without becoming academic. An age limit of three years for admittance to Educare Centres. Very young children should be catered for separately. Liaison between Sub A teachers and Educare staff. , Adobe Acrobat 9.53 Paper Capture Plug-in
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- Date Issued: 1989
Effects of incremented loads over preferred values on psychophysical and selected gait kinematic factor
- Authors: Manley, Peter Gwynne
- Date: 1989
- Subjects: Psychophysiology , Kinematics , Work -- Physiological aspects , Human engineering
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:5160 , http://hdl.handle.net/10962/d1015734
- Description: This study investigated the effects of incremented loads greater than maximal acceptable loads on selected locomotor kinematic and psychophysical variables for four different hand-held load-carriage methods. Ten male and ten female subjects, between the ages of 18 and 30, participated in four experimental sessions. Data collection involved obtaining selected anthropometric, strength, maximal load and preferred load, gait kinematic, and psychophysical values. The anthropometric, strength and load capacity variables enabled absolute and morphology normalised sex-based comparisons to be made. The kinematic and psychophysical parameters were used to quantify any changes from two sets of baseline values,"unloaded" and "maximal acceptable load" values, when loads were increased and carrying methods changed. Statistical analysis revealed that males were taller, heavier and stronger than females (p<0.05). Males chose significantly greater maximal acceptable loads and absolute maximal loads than females when expressed in their absolute or relative terms. Preferred walking speeds were not significantly different for unloaded or loaded conditions, although males walked significantly faster in absolute terms (but not in relative terms) than females. Different load carrying methods and incremented loads brought. about significant changes to several of the kinematic parameters investigated. Finally, ratings of perceived exertion, as well as the number of exertion sites, were seen to increase significantly as load increased. These values were not, however, significantly affected by differences in load carriage method.
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- Date Issued: 1989
Emergency law: judicial control of executive power under the states of emergency in South Africa
- Authors: Grogan, John
- Date: 1989
- Subjects: War and emergency legislation -- South Africa , Internal security -- South Africa , Civil rights -- South Africa , Executive power -- South Africa , Judicial review of administrative acts -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3674 , http://hdl.handle.net/10962/d1003189 , War and emergency legislation -- South Africa , Internal security -- South Africa , Civil rights -- South Africa , Executive power -- South Africa , Judicial review of administrative acts -- South Africa
- Description: This work examines the legal effects of a declaration of a state of emergency under the Public Safety Act 3 of 1953 and the exercise of legislative and administrative powers pursuant thereto. The general basis of judicial control over executive action and the various devices used to limit or oust the court's jurisdiction are set out and explained. Against this background, the courts' performance of their supervisory role under the special circumstances of emergency rule is critically surveyed and assessed. The legal issues raised by the exercise of emergency powers is examined at the various levels of their deployment: first, the declaration of a state of emergency; second, the making of emergency regulations; third, their execution by means of administrative action, including detention, banning, censorship and the use of force. The major cases concerning emergency issues, both reported and unreported, are analysed in their appropriate contexts, and an overview provided of the effects of emergency regulations and orders on such freedoms as South Africans enjoy under the 'ordinary' law. Finally, an attempt is made to assess how these decisions have affected the prospect of judicial review of executive action, both in the emergency context and in the field of administrative law generally. The conclusion is that, however far the Appellate Division may appear to have gone towards eliminating the role of the law in the emergency regime, grounds remain for the courts to exercise a more vigorous supervisory role should they choose to do so in future.
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- Date Issued: 1989
Energetic and kinematic responses to morphology-normalised speeds of walking and running
- Authors: Williams, Martin Andrew
- Date: 1989
- Subjects: Running -- Physiological aspects , Walking -- Physiological aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5166 , http://hdl.handle.net/10962/d1016240
- Description: This study investigated the influence of human morphology upon selected physiological, biomechanical and psychological responses to horizontal locomotion. In so doing, it was possible to evaluate the effectiveness with which morphology-normalised speeds of walking and running reduced the between-subject variability that is inherent in human locomotor responses. Twenty caucasian males were divided into two groups on the basis of stature - ten subjects in each of a "short" category (<170cm) and a "tall" category (>185cm). All subjects were habituated to treadmill locomotion prior to exposure to three walking treatments (0.83, 1.39 and 1.94m.s⁻¹) and three running treatments (2.50, 3.06 and 3.61m.s⁻¹). During each of these five-minute locomotor conditions, energetic (V02), kinematic (cadence and stride length) and psychophysical (central and local RPE) data were captured. From these data, lines of best fit were calculated for each subject, allowing for a prediction of the abovementioned locomotor variables from known absolute rates of progression. Using suitable regression equations, subject responses to morphology-normalised speeds of walking and running were effectively extrapolated. When the rate of progression was expressed in absolute terms (m.s⁻¹), significant differences (P <0.05) were found between the stature-related groups with respect to both energetic and kinematic locomotor responses. Such differences were successfully eliminated when use was made of locomotor speeds relativised on the basis of morphology. This study concludes that the use of appropriately prescribed morphology-normalised rates of progression are effective in reducing the variability in locomotor responses between subjects differing significantly in stature.
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- Date Issued: 1989
Eskom 1989 Negotiations report back
- Authors: NUM
- Date: 1989
- Subjects: NUM
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/134893 , vital:37215
- Description: Eskom has paid wage increases to salaried staff backdated to 1 April 1989. The NUM has NOT agreed with these increases because they are too low. We are not allowed to go on strike at Eskom - we have to get an arbitrator to decide if the increases must be bigger.
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- Date Issued: 1989
Eskom wage negotiations for general workers 1989
- Authors: NUM
- Date: 1989
- Subjects: NUM
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/134916 , vital:37217
- Description: Eskom started the 1989 wage negotiations with an offer of 7% on average. They said this offer is ail they need to make to keep their relative position in the labour market. we believe that the Eskom offer is contrary to the substance and spirit of Arbitration Award which forced Eskom, in 1988, to grant a 14,8% average increase in place of the 10% average increase Eskom implemented unilaterally m July last year. Dr Dry, the Eskom personnel manager, read out from an NUM pamphlet issued after the arbitrators raised the wages. He read out this one sentence. Today, through unity, the minimum wage rates as Eskom are amongst the highest in the country for workers living in compounds.
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- Date Issued: 1989
Ethical issues in human movement research
- Authors: Olivier, Stephen Chris
- Date: 1989
- Subjects: Human mechanics , Human mechanics -- Research -- Moral and ethical aspects , Research -- Moral and ethical aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5156 , http://hdl.handle.net/10962/d1015402
- Description: In acknowledging past abuses of humans in research contexts, and recognising the potential for malpractices in Human Movement Studies (HMS), this study evaluated the extent to which ethical issues are addressed in the discipline. The primary method consisted of the standard techniques of philosophic analysis, with empirical data complementing the conclusions. In general, the study contends that insufficient attention is paid to ethical issues in HMS research. In response to a set of specifically constructed, ethically problematic research proposals, only 1.8% of comments from senior researchers advocated rejection of the proposals on ethical grounds. Also, a journal search indicated that consideration of ethical issues in published research may largely be absent. Questionnaire responses revealed that South African HMS departments may be deficient in terms of accountability towards ethical guidelines. Whilst noting the existence of utilitarian ethics in HMS research, it is advocated that deontologic principles should take precedence. Further, only a sound educative effort will produce improvements. In conclusion, this study advocates a deontology-based approach to research ethics. This is consistent with the contention that the use of humans in research is a privilege, and that the rights of participants ought to outweigh the desire of researchers to conduct research.
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- Date Issued: 1989
Examining of the novel in the senior secondary phase (English first language higher grade): a study of conflicting aims
- Authors: Macrae, Claire Elisabeth
- Date: 1989
- Subjects: Education, Secondary English Secondary -- Study and teaching -- South Africa Education Secondary -- Evaluation
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1357 , http://hdl.handle.net/10962/d1001423
- Description: This study deals with the problems of external examining, the inflexible demands of which dominate and dictate to literature teaching in South African schools today. The aims of teaching literature are discussed, and it is suggested that the negative attitudes among pupils resulting from the present examining system defeat many of these aims. The opportunities for the enjoyment of literature are minimised by the process of preparation for external examinations. Creative teaching methods are abandoned in favour of coaching for specific types of questions, which are determined and limited by the practical constraints of a mass external examination. In catering to the demands for admininstrative reliability and efficiency, the educational validity and efficiency of the examinations are sacrificed. In Britain the Newbolt and Bullock Reports, among others, have made forceful recommendations for alternative approaches to external examining. Subsequently, much experimentation with internal examining, course-work and open-book examining has followed, aspects of which are discussed in this study. There has been limited experimentation in these areas in South Africa. The TED conducted a successful internal examining experiment in English literature, the results of which are considered in this thesis. The national English Olympiad open-book examination is a further example of the success of an alternative approach. By contrast, a comparison of examination papers set by the JMB and CED over the last ten years, shows clearly that the stated syllabus aims of teaching literature and the aims of examining the subject were wholly incompatible. Recommendations are made for the adoption of alternative examining strategies in order to address the shortcomings identified
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- Date Issued: 1989
Family planning : an evaluative study on the attitudes and use of contraceptives by black males in Umtata
- Authors: Madikizela, Nosinodi Alicia
- Date: 1989
- Subjects: Birth control -- South Africa -- Transkei , Transkei (South Africa) -- Social conditions
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3278 , http://hdl.handle.net/10962/d1006454 , Birth control -- South Africa -- Transkei , Transkei (South Africa) -- Social conditions
- Description: The purpose of this study is to identify, observe and record the attitudes and use to of contraceptives by black males in Umtata and to investigate the effect of education, urbanisation and age on fertility control. Data was gathered from a sample of adult males who were past the school going age and were employed or working in Umtata and its surburbs, which are Ngangelizwe, Ikwezi, Southernwood, Northcrest, Norwood, Ncambedlana, Nduli Crescent, Fortgale and Hill Crest. Information was also gathered from Nursing officers in charge of family planning service centres in the areas mentioned above. Findings reveal that, although black urbanised educated males in Umtata seem to have accepted the use of contraceptives by themselves and their sexual partners, their patterns of behaviour in relation to fertility control and the value of children to families remains traditional. This contributes to the relatively high fertility rate in the country. Children are an investment for old age. They are also regarded as a security factor against divorce. It is the duty of legally married couples to raise a family with children who will continue to bear the family name. It appears that men are either suspicious of modern contraception if not totally opposed to it. Many still prefer the use of natural methods of contraception. There is thus need for social workers and health planners to recognise and educate males on the use and benefits of modern contraceptives to limit the number of children borne and control periods when they would like to have children. This study will be of value to social welfare services and to family planning nurses who are in direct contact with clients in hospitals and clinics, in their family planning campaigns, when they motivate couples and individuals on the importance of family planning, and also in mother-and-child health services. Educationists, sociologists, psychologists and persons in other fields of study will also benefit from information attained in this survey.
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- Date Issued: 1989
Fest-Quest '88: survey of visitors to the 1988 Standard Bank Festival of the Arts
- Authors: Davies, William J
- Date: 1989
- Subjects: Standard Bank National Arts Festival
- Language: English
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/1719 , vital:20219 , ISBN 0868101818
- Description: The Standard Bank National Festival of the Arts is held annually in early July in Grahamstown. Apart from its importance as a national cultural event, the Festival is vitally important to the economy of Grahamstown. The annual influx of Festival participants results in expenditure amounting to several million rand, concentrated into a hectic nine-day extravaganza. The Development Studies Unit at Rhodes University and the 1820 Foundation have attempted to monitor the nature and extent of the Festival's impact on Grahamstown since 1987. Information is collected by means of a voluntary questionnaire (the Fest-Quest), and provides a useful resource for the Festival organizers as well as insights into the relative economic importance of the occasion. Fest-Quest '88 is the second such survey undertaken. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
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- Date Issued: 1989
Health and politics : appraisal and evaluation of the provision of health and mental health services for Blacks in South Africa
- Authors: O'Donoghue, Sean B
- Date: 1989
- Subjects: Black people -- Mental health -- South Africa , Mental health services -- South Africa
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:2909 , http://hdl.handle.net/10962/d1002074
- Description: The aim of this study has been to examine, in the light of recent events in the field of Health Care in South Africa, the remarks and claims made by the World Health Organization, and the American Psychiatric Association between 1976 and 1978 on Health Care services, as provided for Blacks, by the South African government. In two reports, these organizations instituted the earliest, and arguably most significant claims against South Africa's system of Health Care. This study sketches firstly the political genesis and social context of the WHO, and APA examinations. Secondly, this study evaluates responses made by the South African State to the critical climate inspired by the above mentioned reports, through a close analysis of recent events associated with the politics, and provision of Health Care Facilities - particularly with regard to Black South Africans. This analysis suggests that the governments' earlier tentative policy of privatisation (which was soundly condemned by WHO and the APA) has been even more enthusiastically pursued - in contradiction to it's avowed policies of Commu ity Health Care, and to the continuing detriment of those South African communities who are in most need of adequate Health Care services. The study concludes that the criticisms raised by the WHO and APA had the effect of inspiring positive reforms in South Africa's health services, but in no way thwarted the governments', at first only tentative plans, to increasingly privatise it's psychiatric and other medical institutions.
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- Date Issued: 1989
High-performance liquid chromatographic studies of the acid degradation, pharmacokinetics and comparative bioavailability of erythromycin
- Authors: Glew, Fiona
- Date: 1989
- Subjects: High performance liquid chromatography , Erythromycin -- Analysis , Erythromycin -- Pharmacokinetics , Erythromycin -- Bioavailability
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3737 , http://hdl.handle.net/10962/d1001529
- Description: Erythromycin is a macrolide antibiotic with a spectrum similar to penicillin and is used mainly in the treatment of infections caused by gram-positive organisms. Since its discovery in 1952, erythromycin has achieved wide-spread clinical use. Susceptibility of erythromycin base to inactivation by acid results in decreased availability following exposure to acidic gastric fluids. Formulation of acid resistant dosage forms and the preparation of acid stable chemical derivatives have been attempted to improve absorption and subsequent clinical efficacy . Two of the most commonly used erythromycin derivatives are the stearic acid salt (erythromycin stearate) and the lauryl sulphate salt of the propionyl ester (erythromycin estolate). Although it has been known for many years that erythromycin is susceptible to acid degradation, very few reports on the stability of erythromycin in aqueous solutions appear in the literature. In this study, a high-performance liquid chromatographic system using electrochemical detection was employed for a kinetic study of erythromycin degradation. The effect of varying acid pH on the degradation rate of both erythromycin base and erythromycin stearate, and the effect on the hydrolysis rate of erythromycin estolate is presented. In addition, the effect of temperature on erythromycin degradation was also investigated. Until recently, the majority of pharmacokinetic and bioavailability studies have utilized relatively non-specific microbiological assay procedures. However, in this study a solid phase extraction, followed by the use of a high-performance liquid chromatographic system using electrochemical coulometric detection was employed for the determination of erythromycin in biological fluids. Human volunteers each received enteric coated erythromycin base pellets in capsule dosage form and also film coated erythromycin stearate tablets on separate occasions. Results from the clinical trials revealed the enteric coated erythromycin base pellets had a greater bioavailability than the film coated erythromycin stearate tablets. Computer fitting of data revealed no intra-volunteer variability in elimination rate constants, suggesting differences in serum levels following administration of both dosage forms are due to variation in absorption. Results from the clinical trials were also compared with those obtained from a further trial, during which the same volunteers received erythromycin estolate
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- Date Issued: 1989
Identification and analysis of manual materials handling tasks within a commercial warehouse in South Africa
- Authors: Walraven, Lynne Louise
- Date: 1989
- Subjects: Materials handling -- Safety measures , Industrial safety -- South Africa , Lifting and carrying -- Safety measures
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:5159 , http://hdl.handle.net/10962/d1015722
- Description: Lifting and overstraining are major causative factors related to musculoskeletal injuries and low back pain. A great number of work-related injuries arise from the handling and/or mishandling of materials. Hence there is a need to quantify risk factors in situ and develop guidelines for safe lifting practises in industry. The aim of this study was to make appropriate in situ quantification, within a commercial warehouse, of the stresses and physical demands imposed on the worker when performing two handed lifts in the sagittal plane. The performance of employees was assessed under normal working conditions through an observational methodology of data collection. Task performance evaluation was based on detailed measurement of all containers handled, an activity and time analysis, and the 'Work Practices Guide to Manual Lifting’ (NIOSH, 1981) which was used as the primary guide to developing theoretical recommendations to probable MMH risk factors for the workers involved. Of the 191 tasks analysed 103 were deemed unsuitable. Appropriate task factor adjustments were made where necessary to both the frequency and Hfactors (horizontal distance between the centre of gravity of the container and that of the worker) in order to reduce the risk factor for the workers
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- Date Issued: 1989
In vitro diffusion cell design and validation. I. A stability-indicating high-performance liquid chromatographic assay for betamethasone 17-valerate in purified isopropyl myristate receptor phase
- Authors: Smith, Eric W , Haigh, John M
- Date: 1989
- Language: English
- Type: text , Article
- Identifier: vital:6431 , http://hdl.handle.net/10962/d1006595
- Description: Introduction: The development of a reliable in vitro permeation system necessitates the use of a precise and accurate method of quantifying the amount of permeant partitioning from the membrane into the cell receptor phase. Aqueous donor and receptor chamber fluids have been used in the majority of reported investigations, which makes quantitative permeant analysis relatively facile. Alternatively, radiolabelled diffusants have been used and flux rates monitored by scintillation counting, obviating the need for chromatographic separation of the receptor-phase components. However, this technique is not applicable when nonlabelled compounds or commercial dosage forms are to be evaluated by a cell system. Furthermore, several studies indicate that aqueous receptor phases may not present an optimal partitioning environment for certain lipophilic permeants (1-4), thereby impairing accurate flux monitoring due to limited diffusant solubility. Several attempts have therefore been made to improve the partitioning environment within these systems, by the addition of surfactants for example (4). A lipophilic receptor environment appears beneficial for corticosteroid partitioning, and thus, the use of isopropyl myristate has been investigated because of its bipolar properties that tend to mimic the biochemical composition of the skin (5,6). Betamethasone 17-valerate and its 21-valerate degradation product are highly soluble in isopropyl myristate and this nonaqueous solvent will not augment C-17-to-C-21 ester degradation reactions.
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- Date Issued: 1989
In vitro systems for the assessment of drug release from topical formulations and trans-membrane permeation
- Authors: Smith, Eric W , Haigh, John M
- Date: 1989
- Language: English
- Type: Book chapter
- Identifier: vital:6441 , http://hdl.handle.net/10962/d1006628
- Description: Numerous experimental methods have been developed to investigate drug release from vehicles and the percutaneous absorption of topically applied chemicals. The objective of this research is often to find correlation between laboratory results and the transdermal absorption experienced by living subjects so that in vivo experimentation may be curtailed. In many instances, the diverse experimental techniques tend to obscure absorption-controlling factors and complicate inter study comparisons, rather than clarify the complex transdermal absorption process. Moreover, lack of agreement between results may occasionally be ascribed to shortcomings in the in vitro methodology employed. The benefits of using an in vitro cell system for the preliminary testing of drug permeation in the laboratory are obvious. The environmental and diffusion variables may be controlled in an attempt to elucidate specific factors affecting the kinetic processes and drug bioavailability. Investigations are complex because of the multiple, interrelated events underlying the processes of drug partitioning from the applied vehicle and diffusion through the portals of the stratum corneum to the myriad of metabolic, binding, and clearance activities in the lower epidermal and dermal strata.
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- Date Issued: 1989
Interactions between ants, herbivorous insects and bracken (Pteridium aquilinum), a fern with extrafloral nectaries
- Authors: Rashbrook, Vanessa Karin
- Date: 1989
- Subjects: Arthropod pests -- South Africa Ants -- South Africa Ferns -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5592 , http://hdl.handle.net/10962/d1002042
- Description: Bracken (Pteridium aquilinum) is a cosmopolitan species of fern which possesses extrafloral nectaries. A survey of the arthropod fauna associated with the plant throughout its range in South Africa identified the most widespread and damaging bracken herbivores and those species most likely to be influenced by ants visiting the extrafloral nectaries. Seventeen herbivorous arthropods were found to be definitely feeding on bracken and a further thirteen species with a less certain status were recorded. In addition, several species of ants were observed on the fronds and feeding at the extrafloral nectarie. On the basis of their widespread distribution and abundance, four bracken herbivores emerged as being particularly detrimental to the plant in South Africa. They were an eriophyid gall mite, a leafhopper and two moths. The biology of the two lepidopterans, Appana cinisigna and Panotima sp., suggested that they were potentially vulnerable to ants at various stages of their life histories. Laboratory experiments were undertaken to observe ant-lepidopteran interactions under controlled conditions. The ant Crematogaster peringueyi rapidly removed exposed A. cini igna eggs, but did not appear to regard Panotima eggs as food items. Small instar larvae of both species proved vulnerable, but the larger larvae appeared capable of escaping ant predation. Ant exclusion experiments in the field, using natural and artificially augmented ant densities, were carried out at two sites near Grahamstown. The dominant ant species was C. peringueyi. Neither the numbers of lepidopterans nor levels of herbivory were significantly reduced by the presence of ants . Despite the implications of the laboratory tests, the results of these field experiments did not support the hypothesis that ants which visit bracken extrafloral nectaries benefit the plant. Ant-bracken field studies on other continents also reported no significant ant-related effects, though marginal reductions in the abundance of certain herbivores have been noted at one site in the U.K. Since ant protection does not appear to be an inevitable consequence of having extrafloral nectaries, their value to bracken is in some doubt. The most likely situation where effective protection will occur is when high densities of vulnerable herbivores are preyed upon by large numbers of aggressive ants. However, even under these conditions, enhancement of plant fitness is not inevitable. This raises the question of why extrafloral nectaries have been retained in a plant that is as successful and widespread as bracken.
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- Date Issued: 1989
Investigation of the causative agents of the 1982 Gazankulu poliomyelitis outbreak, using four biochemical techniques
- Authors: Gibson, Katherine Margaret
- Date: 1989
- Subjects: Poliomyelitis -- Analysis , Poliomyelitis -- History -- South Africa , Poliomyelitis vaccine -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3878 , http://hdl.handle.net/10962/d1001612
- Description: Comparison of poliovirus strains was carried out to determine the origin of the virus in two isolates obtained during the 1982 outbreak of poliomyelitis in Gazankulu. Comparisons of the outbreak isolates with vaccine and wild-type strains of the same poliovirus type were carried out using four biochemical techniques. SDS-polyacrylamide gel electrophoresis (SDS-PAGE), two-dimensional thin-layer chromatography (TLC) and reversed-phase high-performance liquid-chromatography (RP-HPLC) were used for comparing viral capsid proteins. Comparison of poliovirus strains at a genetic level was carried out using two-dimensional oligonucleotide mapping of viral RNA. Results showed the type 1 poliovirus isolate, 5061, to be a novel wild-type poliovirus. The type 2 isolate, 5068, was closely related to the poliovirus type 2 Sabin vaccine strain, P712. It was concluded that the intrinsic variability of poliovirus strains was responsible for the appearance of isolate 5068
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- Date Issued: 1989