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Bioequivalence testing of topical dermatological formulations, the gap between science and legislation

- Schwarb, Fabian P, Smith, Eric W, Haigh, John M, Surber, Christian

Authors: Schwarb, Fabian P , Smith, Eric W , Haigh, John M , Surber, Christian
Date: 1998
Language: English
Type: Conference paper
Identifier: vital:6341 , http://hdl.handle.net/10962/d1006608
Description: Bioavailability concerns for topical dermatological products are complex and it is especially difficult to determine the bioequivalence of similar topical formulations. Since only small amounts of drug dispersed in an appropriate vehicle are applied to the skin, the amount of drug that actually reaches the systemic circulation is often too small to be easily quantified. Additionally, it can be argued that the relevance of any serum/plasma concentration-time curve of a topical agent is questionable, since the curve reflects the amount of drug after the active moiety has left the site of action. For some topical drugs e.g., topical corticosteroids, it is possible to perform a pharmacodynamic bioassay to obtain acceptable bioequivalence data. In this case, the intensity of the side effect of blanching (vasoconstriction) in the skin caused by topical corticosteroids can be measured. The response is directly proportional to the clinical efficacy, and the skin blanching assay has proved to be a reliable procedure for the determination of topical corticosteroid bioavailability. Recently, we had sight of the results of a topical bioequivalence study, which was conducted for the registration of a new generic corticosteroid cream formulation. In this trial the new formulation was compared to two equivalent product from the local market and bioequivalence was demonstrated by the investigators for all three products. These results were examined with interest as the respective reference products have been used repeatedly as standard formulations in our laboratory. However, one of these reference formulations has consistently shown superior bioavailability in our trials, but was not demonstrated to be superior in the study results examined. In the present publication an overview of topical bioequivalence testing in general is given and the difficulties occurring in practice, for topical corticosteroid formulations in particular, are demonstrated.
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Date Issued: 1998

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Chromametry: measuring precision of diurnal and local variation of human forearm skin colour

- Schwarb, Fabian P, Smith, Eric W, Haigh, John M, Surber, Christian

Authors: Schwarb, Fabian P , Smith, Eric W , Haigh, John M , Surber, Christian
Date: 1998
Language: English
Type: Conference paper
Identifier: vital:6343 , http://hdl.handle.net/10962/d1006610
Description: Chromameters are compact portable instruments used for the assessment of surface colour based on the tristimulus analysis of a reflected xenon light pulse, and have been used for the quantification of erythema in the study of irritant dermatitis, and corticosteroid-induced skin blanching in the vasoconstriction assay. The variability and the reproducibility of chromameter results were investigated since it is known that the location and application force of the measuring head on the skin and the orthostatic maneuver of the arms influence the colour measurement. Furthermore the diurnal variation and the homogeneity of forearm skin colour were investigated.
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Date Issued: 1998

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Comparison of visual CR-200 and CR-300 chromameter data obtained from the corticosteroid-induced skin-blanching assay

- Schwarb, Fabian P, Smith, Eric W, Haigh, John M, Surber, Christian

Authors: Schwarb, Fabian P , Smith, Eric W , Haigh, John M , Surber, Christian
Date: 1998
Language: English
Type: Conference paper , text
Identifier: vital:6344 , http://hdl.handle.net/10962/d1006611
Description: In a recent Guidance document the American FDA recommended the use of a chromameterrather thanthe human eye for the assessment of the pharmacodynamic blanching response produced after topical application of corticosteroids. The purpose of this study was to investigate the appropriateness of the human eye and two types of chromameter for the estimation of skin blanching.
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Date Issued: 1998

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Precision of tristimulus chromameter results from corticosteroid-induced skin blanching

- Smith, Eric W, Haigh, John M

Authors: Smith, Eric W , Haigh, John M
Date: 1998
Language: English
Type: Conference paper
Identifier: vital:6342 , http://hdl.handle.net/10962/d1006609
Description: The human skin blanching (vasoconstriction) assay has been in use for 3 decades as a tool for the assessment of the release of corticosteroids from topical dosage forms. Application of corticosteroids produces a whitening (blanching) of the skin, the intensity of which is directly related to the clinical efficacyof the formulation. Assessment of the intensity of the induced blanching has classically been, and continues to be, pe1fonned by visual grading, a method which has been criticised because of the subjectivenature of the assessment Recently there has been considerablediscussion in the literature regarding the use of the chromameter as an objective instrumental method of monitoring corticosteroid induced skin blanching for bioequivalence assessment purposes. The FDA has released a Guidance document recommending the use of the chromameter for this purpose. The chromameter measures colour in teims of three indices: the L-scale (light-dark), the a-scale (red-green) and the b-scale (yellow-blue).Any colour can be expressedabsolutelyin terms of these three values.The Guidance protocol suggests the use of only the a-scale values in quantifying the blanching response after correction of the data which includes subtraction of baseline and unmedicated site values. One of the unresolved issues in the FDA Guidance document is this method of data manipulation suggested since the instrument should be capable of assigning an absolute colour value to each site during the vasoconstriction period. The purpose of this study was to manipulate the instrumental data from a typical blanching study in a number of ways to investigate the appropriatenessof these suggested procedures.
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Date Issued: 1998

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The use of supersaturated solutions for the percutaneous delivery of rooperol tetra-acetate

- Pefile, S C, Haigh, John M, Smith, Eric W

Authors: Pefile, S C , Haigh, John M , Smith, Eric W
Date: 1998
Language: English
Type: Conference paper , text
Identifier: vital:6340 , http://hdl.handle.net/10962/d1006537
Description: A major problem encountered in the transdermal delivery of drugs is the effectiveness of the barrier system imposed by the stratum corneum.To overcome tbe resistance of the skin to the ingress of exogenous chemicals, numerous innovative techniques requiring complex delivery systems have been studied. Many of these systems attempt to alter the barrier potential by the use of enhancer technology. Supersaturation, on the other hand, is a simple and economical technique which is not intended to modify the physical structure or the chemical composition of the stratum corneum, yet may effectively deliver a markedly greater mass of drug to the skin than that achieved by the use of conventional, saturated solutions. Supersaturated systems make use of the elevated thermodynamic activity of the permeant in the delivery vehicle, which results in higher flux rates across the contacting membrane by increasing the concentration gradient. The present study investigated the potential for using supersaturation techniques to transdermally deliver rooperol tetra-acetate (RTA), a lipophilic, cytotoxic agent with potential for use in the treatment of solar keratosis. The diffusion characteristics of the drug from a 60% propylene glycol/water supersaturated solution across silicone membrane and full thickness rat skin were studied using Franz diffusion cells. A comparison was made of the drug diffusion rates from a saturated system and from supersaturated systems prepared with and without an antinucleating agent.
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Date Issued: 1998

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Mentoring and prospects for teacher development - a South African perspective

- Probyn, Margie J, Van der Mescht, Hennie

Authors: Probyn, Margie J , Van der Mescht, Hennie
Date: 2001
Language: English
Type: Conference paper
Identifier: vital:6090 , http://hdl.handle.net/10962/d1009744
Description: School-based mentoring has developed in response to a number of factors pertaining to the pre-service education of student teachers and the in-service professional development of experienced teachers. Traditionally teacher education has consisted of university-based theory with school-based practice, based on an understanding of professional learning as ‘theory into practice’. One of the problems with this model is that theory may come to seem too remote from practice, and that practice appears untheorised by remaining implicit and unproblematised. The one-year teachers’ diploma course offered by the Rhodes University Education Department incorporates a ten-week teaching practice slot. This protracted period has been useful in allowing frequent and consistent contact between university tutors and student teachers, and between mentor teachers and student teachers. Where the system has not been strong is in enabling meaningful collaboration among all three parties. A pilot school-based mentoring programme was thus implemented in 1999, involving English First and Second Language student teachers, the two university tutors and seven mentor teachers. Ongoing evaluative research revealed that the programme was welcomed by all, and that the student teachers in particular gained much in the way of learning to be critically reflexive in a non-threatening environment. However, the research also uncovered areas that need to be developed. Student teachers, for example, need guidance in terms of learning how to talk about teaching; mentor teachers need to develop the confidence and expertise required to open up their practice in a critically constructive context. On the strength of the programme’s success, the Education Department has extended school-based mentoring to all HDE students, and is exploring ways of setting up courses through which other educators (such as EDOs) may receive training in pre- and in-service teacher mentoring.
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Date Issued: 2001

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XML to facilitate management of multi-vendor networks

- Halse, Guy A, Wells, George C, Terzoli, Alfredo

Authors: Halse, Guy A , Wells, George C , Terzoli, Alfredo
Date: 2001
Subjects: XML Network Management SNMP
Language: English
Type: Conference paper
Identifier: vital:6602 , http://hdl.handle.net/10962/d1009322
Description: Many standards aimed at managing networks currently exist, and yet networks remain notoriously difficult to maintain. Template-based management systems go a long way towards solving this problem. By developing an XML based language to describe network elements, as well as the topology of a network, we can create tools that are free from vendor specific idiosyncrasies, and are capable of managing both today’s networks and those of the future.
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Date Issued: 2001

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A bi-directional SOAP/SMS gateway service

- Halse, Guy A, Terzoli, Alfredo, Wells, George C

Authors: Halse, Guy A , Terzoli, Alfredo , Wells, George C
Date: 2002
Subjects: Broadband 2 SATNAC 2002
Language: English
Type: Conference paper
Identifier: vital:6600 , http://hdl.handle.net/10962/d1008293
Description: Many applications need the ability to do real-time notification when events occur. Often the people who need to be kept aware of events are in a remote location. This paper looks at a bi-directional gateway between networked computers and the GSM short message service. The gateway is implemented as a web service, and uses the Simple Object Access Protocol to facilitate data communication. The service interacts with a database in order to facilitate retrieval of sent or received messages, as well as provide accounting abilities. It is intended as a practical proof-of-concept application demonstrating some ofdemonstrating some of the capabilities of the Simple Object Access Protocol.
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Date Issued: 2002

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Accelerated sludge solubilisation under sulphate reducing conditions: the effect of hydrolytic enzymes on sludge floc size distribution and EPS composition

- Akhurst, P, Rose, Peter D, Whiteley, Chris G, Pletschke, Brett I

Authors: Akhurst, P , Rose, Peter D , Whiteley, Chris G , Pletschke, Brett I
Date: 2002
Language: English
Type: Conference paper
Identifier: vital:6455 , http://hdl.handle.net/10962/d1010430
Description: Extracellular polymeric substances (EPS) are the construction materials for microbial aggregates such as biofilms, flocs and sludge, and greatly contribute to the structural integrity of sludge flocs in wastewater treatment processes. The loss of integrity of the sewage sludge floc is believed to be due to enhanced hydrolysis of important structural components such as lignin, protein and cellulose in the sludge floc matrix. The mechanism of enhanced sludge floc fracture, due to the action of enzymes hydrolysing these structural components, remains a key element in our understanding of how the floc integrity in systems utilising a sulphate reducing system is compromised. A range of relatively non-specific exogenous enzymes (ß-glucosidase, cellulase, proteases: trypsin, pronase E and chymotrypsin) were added to a sulphidogenic bioreactor- (containing both sulphate reducing bacteria (SRB) and a methanogenic bacterial system) and a (control) methanogenic bioreactor sample, and the effect of these enzymes on sludge floc size (diameter) distribution and EPS composition was investigated. Sludge samples from the bioreactors were examined under bright field and differential interference contrast light microscopy. Proteolytic and glucohydrolytic activity of the enzymes were monitored using standard enzyme assaying techniques, and Bradford, Somogyi-Nelson, and total carbohydrate assays were performed to establish the composition of the EPS (after extraction with 3% (v/v) glutaraldehyde and Sephacryl S-400 size exclusion chromatography). Sludge flocs present in the sulphidogenic environment of the sulphidogenic bioreactor were found to have smaller diameters than their counterparts present in the methanogenic bioreactor. The addition of hydrolytic (i.e. proteolytic and glycohydrolytic) enzymes resulted in an increased rate of matrix hydrolysis, leading to increased rates of floc fracture and deflocculation. The presence of ß-glucosidase, cellulase, and proteases naturally residing within the sludge floc was confirmed. We propose that the addition of commercially available enzymes may be prohibitively costly on a large scale, and that the activity of the enzymes naturally residing within the floc matrix be optimised or enhanced. As the bulk of the EPS was shown to be composed of mainly polysaccharides, we propose that by increasing the activity of the naturally occurring ß-glucosidases residing within the floc matrix, the process of deflocculation may be enhanced. As sulphide has been shown to increase the activity of this very important key enzyme, we propose that this is one of the contributing factors why sludge solubilisation is accelerated under sulphate reducing conditions.
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Date Issued: 2002

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The land question in South Africa, Zimbabwe and Kenya: a geographical perspective on resource endowment

- Fox, Roddy C, Rowntree, Kate M

Authors: Fox, Roddy C , Rowntree, Kate M
Date: 2002
Language: English
Type: Conference paper
Identifier: vital:6664 , http://hdl.handle.net/10962/d1006671
Description: In sharp contrast to the debates concerning land policy, land tenure and sustainable resource management in South Africa is any input concerning the geographical distribution of land productivity. This paper attempts to redress this imbalance by providing an empirical investigation of land potential in South Africa. In this way we intend to provide the crucial context for policy and academic studies of the land issue in South Africa. Furthermore, we will undertake our study in such a way that comparison can be made to Zimbabwe and Kenya where the land issue has been such a critical component of the post-colonial development process. Theoretically our work is contextualised within the debates surrounding the importance of geographical endowments, institutions and policies in the development process.
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Date Issued: 2002

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Refining lecturers’ assessment practices through formal professional development at Rhodes University, Grahamstown

- Sayigh, Elizabeth

Authors: Sayigh, Elizabeth
Date: 2003
Language: English
Type: Conference paper
Identifier: vital:6080 , http://hdl.handle.net/10962/d1008584
Description: In recent years, the so-called Accreditation and Registration of Assessors has given rise to much debate in the Higher Education sector. The idea that anyone assessing student learning should be required to train in order to gain a formal qualification and register as an assessor originated with the South African Qualifications Authority (SAQA) and was soon challenged within the higher education community. The Study Team appointed to investigate the implementation of the NQF (National Qualifications Framework) in 2001 recommended that registration of assessors should not be required of individuals teaching in the higher education sector if employed by an accredited institution and this recommendation was later accepted by the Department of Education and the Department of Labour in their joint consultative document entitled ‘An Interdependent National Qualifications Framework System’ (Department of Education, Department of Labour 2003). The waiving of the requirement to register assessors has been welcomed within the public higher education sector. But despite this, the need to train and qualify assessors of students’ learning remains important due to the emphasis placed on assessment by the HEQC (Higher Education Quality Committee) in its ‘Criteria for Institutional Audits’ (2004). The central issue has become how higher education institutions are to successfully train lecturers as assessors in higher education.
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Date Issued: 2003

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The biogeography of the Prosopistomatidae, with a particular emphasis on Southern African species

- Barber-James, Helen M

Authors: Barber-James, Helen M
Date: 2003
Language: English
Type: Conference paper
Identifier: vital:6998 , http://hdl.handle.net/10962/d1008378
Description: The mayfly family Prosopistomatidae consists of the single genus Prosopistoma Latreille. Its known distribution includes species from Africa, Madagascar, the Comores, Europe, the Levant, India, Sri Lanka, China, Vietnam, the Philippines, Malaysia, Sumatra, Java, the Solomon Islands, Papua New Guinea and northern Australia. A tropical Gondwanaland origin of the family has been suggested. No species are currently known from the Neotropical or Nearctic regions, though the family may yet be discovered in northeastern South America, since this region separated from West Africa only c.120 mya. Focussing on southern Africa, several undescribed species have recently been discovered, with interesting implications to the biogeography on a more localised scale. In the western Cape, a prosopistomatid species has been collected in the Olifants River, extending the distribution of this family further south into a more temperate region. Geological evidence indicates that the Olifants River was connected to the Orange River during the Tertiary period. Prosopistomatidae are known from the Orange River today, and the presence of the family in the Olifants River in the western Cape supports the geological evidence of the historical link between these two rivers. Another unexpected discovery was from the Buffalo River in the eastern Cape, at 33ºS. A subtropical zone extends along the east coast of South Africa as a result of the warm Agulhas current offshore, allowing the southerly extension of the distribution of more tropical species. , Research Update on Ephemeroptera & Plecoptera: Proceedings of the Tenth International Conference on Ephemeroptera, 8-11 August 2001, Perugia, Italy. University of Perugia, Perugia, Italy, pp. 263-270.
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Date Issued: 2003

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Evaluating parts-of-speech taggers for use in a text-to-scene conversion system

- Glass, Kevin R, Bangay, Shaun D

Authors: Glass, Kevin R , Bangay, Shaun D
Date: 2005
Language: English
Type: Conference paper
Identifier: vital:6603 , http://hdl.handle.net/10962/d1009323
Description: This paper presents parts-of-speech tagging as a first step towards an autonomous text-to-scene conversion system. It categorizes some freely available taggers, according to the techniques used by each in order to automatically identify word-classes. In addition, the performance of each identified tagger is verified experimentally. The SUSANNE corpus is used for testing and reveals the complexity of working with different tagsets, resulting in substantially lower accuracies in our tests than in those reported by the developers of each tagger. The taggers are then grouped to form a voting system to attempt to raise accuracies, but in no cases do the combined results improve upon the individual accuracies. Additionally a new metric, agreement, is tentatively proposed as an indication of confidence in the output of a group of taggers where such output cannot be validated.
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Date Issued: 2005

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Learning science through two languages in South Africa

- Probyn, Margie J

Authors: Probyn, Margie J
Date: 2005
Language: English
Type: Conference paper
Identifier: vital:7015 , http://hdl.handle.net/10962/d1007208
Description: [From the introduction]: South Africa is a multilingual country with eleven national languages - nine indigenous languages and the two former colonial languages of English and Afrikaans1 - recognised as official languages in the Constitution of 1996 (Constitution of the Republic of South Africa, 1996). Despite these provisions, since the democratic elections of 1994 English has expanded its position as the language of access and power with the relative influence of Afrikaans shrinking, and African languages effectively confined to functions of ‘home and hearth’. McLean and McCormick (1996: 329 in Mazrui 2002: 269) suggest that the constitutional recognition of 11 official languages in South Africa is largely 'intended and perceived as a symbolic statement and that for instrumental purposes, English remains the dominant language in South Africa'.
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Date Issued: 2005

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Active learning for understanding land degradation : African Catchment Game and Riskmap

- Rowntree, Kate M, Fox, Roddy C

Authors: Rowntree, Kate M , Fox, Roddy C
Date: 2006
Language: English
Type: Conference paper
Identifier: vital:6669 , http://hdl.handle.net/10962/d1006793
Description: Land degradation is the result of the intersection of a complex set of biophysical and socio-economic factors. The capacity of an individual or community to address land degradation is likewise constrained. While it is quite possible for professionals and learners to grasp the main issues around land degradation from a theoretical perspective, internalizing the reality of what it means to be the resource degrader is more difficult. We have developed two active learning methods that aim to address this problem. The first is the African Catchment Game, a role-playing game based on Graham Chapman’s Green Revolution Game, adapted for the southern Africa context and incorporating a land degradation component. In this game participants play out the complex dynamics of rural-urban-global linkages against a background of environmental hazards. The second is based on Save the Children Fund’s RiskMap computer simulation that models risk in terms of rural livelihoods for different income groups. Ethiopia is used as the example. This paper evaluates the two active learning techniques as tools for exploring the relationships between land degradation and poverty through an evaluation of participants’ experiences.
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Date Issued: 2006

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