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Analysis of chromameter results obtained from corticosteroid-induced skin blanching. I. Manipulation of data

- Smith, Eric W, Haigh, John M, Walker, Roderick B

Authors: Smith, Eric W , Haigh, John M , Walker, Roderick B
Date: 1998
Language: English
Type: text , Article
Identifier: vital:6424 , http://hdl.handle.net/10962/d1006559
Description: Purpose. One of the unresolved issues in the FDA Guidance document for topical corticosteroid bioequivalence testing is the method of manipulation suggested for the chromameter data. The purpose of this study was to manipulate the instrumental data from a typical blanching study in a number of ways to investigate the appropriateness of these procedures for comparison with the subjective visually-assessed results. Methods. The human skin blanching assay methodology routinely practiced in our laboratories was utilised and the vasoconstriction produced by two corticosteroid formulations of different potency was assessed visually and instrumentally by use of a Minolta chromameter. The instrumental data were corrected for zero-time and unmedicated site readings. In addition, Euclidean distances were calculated using all data generated by the instrument. Results. Individually the a-, b- and L-scale chromameter values are imprecise and there is negligible vasoconstriction response recorded for the moderately potent formulation. Arithmetical manipulation of the data as suggested by the FDA does not appear to improve the quality of the data in any way. Euclidean distance analysis more closely resembles the visual data and appears to have better precision. Conclusions. It is clear that mathematical correction of chromameter data is unnecessary, especially since the instrumental data are extremely imprecise. Furthermore, the assessment of each individual chromameter index does not adequately characterise the blanching response profile. It is therefore suggested that Euclidean distance may be a better measure on which to base an analysis of bioequivalence than the truncated data set methodology currently suggested by the FDA.
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Date Issued: 1998

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Analysis of macrolide antibiotics

- Kanfer, Isadore, Skinner, Michael F, Walker, Roderick B

Authors: Kanfer, Isadore , Skinner, Michael F , Walker, Roderick B
Date: 1998
Language: English
Type: Article , text
Identifier: vital:7011 , http://hdl.handle.net/10962/d1008394 , http://www.sciencedirect.com/science/article/pii/S0021967398002763
Description: The following macrolide antibiotics have been covered in this review: erythromycin and its related substances, azithromycin, clarithromycin, dirithromycin, roxithromycin, flurithromycin, josamycin, rokitamycin, kitasamycin, mycinamycin, mirosamycin, oleandomycin, rosaramicin, spiramycin and tylosin. The application of various thin-layer chromatography, paper chromatography, gas chromatography, high-performance liquid chromatography and capillary zone electrophoresis procedures for their analysis are described. These techniques have been applied to the separation and quantitative analysis of the macrolides in fermentation media, purity assessment of raw materials, assay of pharmaceutical dosage forms and the measurement of clinically useful macrolide antibiotics in biological samples such as blood, plasma, serum, urine and tissues. Data relating to the chromatographic behaviour of some macrolide antibiotics as well as the various detection methods used, such as bioautography, UV spectrophotometry, fluorometry, electrochemical detection, chemiluminescence and mass spectrometry techniques are also included.
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Date Issued: 1998

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New developments in the methodology available for the assessment of topical corticosteroid-induced skin blanching

- Haigh, John M, Smith, Eric W, Maibach, Howard I

Authors: Haigh, John M , Smith, Eric W , Maibach, Howard I
Date: 1998
Language: English
Type: text , Article
Identifier: vital:6384 , http://hdl.handle.net/10962/d1006305
Description: Since the publication of the previous edition of this book there have been considerable developments and controversy in the field of topical corticosteroid bioequivalence assessment. There has been considerable discussion in the literature concerning the use of the Minolta chromameter for the measurement of corticosteroid-induced skin blanching, as it is believed this instrument would produce more objective results than the visual grading procedure. These efforts culminated in the release of a guidance document from the Food and Drug Administration (FDA) detailing the procedures to be followed for the determination of topical corticosteroid bioequivalence using the chromameter. Since the promulgation of this document there have been challenges on the validity and scientific merit of the documented procedures, and recently the FDA itself conceded that it may be necessary to redefine some of the protocol evaluations. This chapter attempts to redefine the current standing of the two methods of response assessment.
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Date Issued: 1998

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Surface distribution of microphytoplankton of the south-west Indian Ocean along a repeat transect between Cape Town and the Prince Edward Islands

- Froneman, P William, Pakhomov, E A, Meaton, V

Authors: Froneman, P William , Pakhomov, E A , Meaton, V
Date: 1998
Language: English
Type: text , Article
Identifier: vital:6933 , http://hdl.handle.net/10962/d1011953
Description: Surface chlorophyll-a (chl-a) concentrations, microphytoplankton (>20 μm) species composition and distribution along a repeat transect between Cape Town and the Prince Edward Islands were investigated in early austral autumn (April/May) 1996. Samples were collected at approximately 30 nautical mile intervals for the analysis of size-fractionated chl-a and the identification and enumeration of microphytoplankton species. Peaks in total chl-a (>1 μg 1 [superscript -1]) were recorded at the Subtropical Convergence (STC), at the Sub-Antarctic Front (SAF) and in the waters surrounding the Prince Edward Islands. In addition, a minor peak in chl-a concentration was recorded in the continental shelf waters. At stations where elevated chl-a concentrations were recorded, microphytoplankton generally formed a substantial contribution (-10%) to total chlorophyll. Outside these regions, total chlorophyll concentrations were lower (<0.9 μg 1 [superscript -1]) and almost entirely dominated by nano- and picophytoplankton, which contributed >95% of the total. Microphytoplankton species composition along both transects were dominated by chain-forming species of the genera Chaetoceros (mainly C. neglectum, C. peruvianus and C. constrictus), Nitzschia spp. and Pseudoeunotia doliolus. Cluster and ordination analysis based on species composition identified five distinct microphytoplankton assemblages, which were closely associated with the different water masses in the region between Cape Town and the Prince Edward Islands. The microphytoplankton species composition and biogeographic zones identified during this investigation are in general agreement with similar studies conducted in the south-west Indian Ocean during the austral summer, which suggests that there are little seasonal trends in both the microphytoplankton species composition and biogeographic zonation.
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Date Issued: 1998

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The end of apartheid and the organisation of work in manufacturing plants in South Africa's Eastern Cape Province

- Smith, M R, Wood, G T

Authors: Smith, M R , Wood, G T
Date: 1998
Language: English
Type: text , Article
Identifier: vital:6319 , http://hdl.handle.net/10962/d1011313
Description: The election of 1994 radically changed the environment within which management chose its labour control policies. Prior to the change of government in 1994 plant practices were shaped by the fact of substantial protection against foreign competition, widespread illiteracy, and a set of laws and policies that offered few protections for individual workers or organised labour. Since the change in government the political and legal environment has substantially changed. In this paper we report on management practices before and after the political changes in South Africa in a set of plants in a part of the country where many of the current difficulties of the South African economy exist in a fairly extreme form.
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Date Issued: 1998

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The human skin blanching assay for in vivo topical corticosteroid assessment. II. Subject- and observer-dependent variation in blanching responses

- Haigh, John M, Meyer, Eric, Smith, Eric W, Kanfer, Isadore

Authors: Haigh, John M , Meyer, Eric , Smith, Eric W , Kanfer, Isadore
Date: 1997
Language: English
Type: text , Article
Identifier: vital:6382 , http://hdl.handle.net/10962/d1006300
Description: The human skin blanching (vasoconstriction) assay for the assessment of topical corticosteroids has been in use for over 30 years, the intensity of the drug-induced blanching being assessed subjectively by eye. Both arms of several male and female volunteers are used for product application and more than one observer is used to estimate the degree of induced blanching. There are, therefore, numerous variables which are inherent in the assay procedure. This investigation consisted of three identical trials performed at 8-week intervals, utilising the same 18 volunteers and the same three observers in an attempt to address the question of reproducibility of the assay. From the results obtained it is clear that the assay methodology is capable of consistently distinguishing, on a rank order basis, between preparations which show similar blanching (chemically-equivalent formulations). The similarity of the results for the three individual trials gives considerable confidence to results produced using this methodology. An experiment designed to test the reproducibility of the blanching scores showed that the observers are capable of producing identical results even though visual observation is highly subjective.
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Date Issued: 1997

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