Browsing by Author "Smith, Pete"

Now showing 1 - 8 of 8
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    Determinants and consequences of the pharmacokinetics of rifampicin, isoniazid, pyrazinamide and ethambutol in a cohort of tuberculosis patients
    (2004) McIlleron, Helen; Folb, Peter I; Little, Francesca; Smith, Pete
    A prospectlve pharmacokinetic study was conducted amongst a cohort of 142 patients with tuberculosis (TB) susceptible to rifampicin and isoniazid at Brewelsleloof Hospital, Worcester, in the Western Cape.
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    Information on nutritional supplement labels: Time for legislation
    (MedPharm Publications, 2012) Gabriels, Gary; Lambert, Mike; Smith, Pete
    Background: Nutritional supplements have received attention both from food manufacturers, as a means of marketing the added value to health; and from consumers, in terms of awareness, education, and improved health. To assist this process, it is important to have specific knowledge and understanding of the claims made on labels of nutritional supplement products used for general, and more specifically, for sports consumers. The industry is not regulated, and therefore the claims that are made may not always be accurate. Method: The aim was to describe the labelling and claims information on the labels of a select group of nutritional supplements, either manufactured in, or imported into South Africa. Specific predetermined categories of labelling and claims made on the containers were assessed and summarised. Results: Forty products were selected for analysis, of which 21 (53%) were locally assembled or manufactured products, and 19 (48%), international imported products. Ninety-five per cent of products contained a warning statement on the label. Eighty-five per cent of the nutritional supplement products had a disclaimer on the label. Ninety-eight per cent of the nutritional supplement product labels included some claim on the label. Conclusion: The following information, in particular, needs to be regulated and enforced as part of the labelling process, to ensure that the consumer can make an informed choice. This includes highlighting the potential for adverse events, encouraging warning statements pertaining to “exclusion of use, and “not a cure for disease states”, and alerting consumers of the potential for the presence of banned substances, based on laboratory screen methods.
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    Isolation and characterisation of two antiplasmodial diterpenes from Harpagophytum procumbens (Devil's Claw) and chemical modification of a related analogue
    (2002) Clarkson, Cailean; Smith, Pete; Campbell, William E; Chibale, Kelly
    Bibliography: leaves 153-171.
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    Isoniazid and acetylisoniazid urine concentrations as a maker of adherence to isoniazid preventative therapy in children
    (2013) Amlabu, Veronica Asibi; McIlleron, Helen; Smith, Pete
    The World Health Organization recommends the use of isoniazid preventive therapy to reduce the incidence of tuberculosis disease in populations at risk for developing the disease. Adherence to isoniazid preventive therapy is needful for efficacy. A urine assay known as the Arkansas test is widely used to monitor the ingestion of isoniazid. However, this test is limited by a drop in sensitivity with increasing time post isoniazid dose. Furthermore, results from the test can be affected by observer variation in colour changes, concomitant medications, urinary dilution, and presence of other substances in urine. Moreover, the Arkansas test results have not been evaluated against objective measurement of isoniazid and acetylisoniazid urine concentrations. This study seeks to measure the urine concentrations of isoniazid and acetylisoniazid at different time points after a dose in children, in order to establish reference ranges for liquid chromatography tandem mass spectrometry measurements of urine isoniazid and acetylisoniazid, as well as the Arkansas method. The reference ranges would provide a standard which can be used to estimate the probability of adherence to prior doses.
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    Melamine contamination in nutritional supplements - Is it an alarm bell for the general consumer, athletes, and 'Weekend Warriors'?
    (BioMed Central Ltd, 2015) Gabriels, Gary; Lambert, Mike; Smith, Pete; Wiesner, Lubbe; Hiss, Donavon
    BACKGROUND: Nutritional supplements are used or experimented with by consumers, notably these are; competitive and recreational athletes of all ages, and 'weekend warriors'. As a consequence the supplement industry has grown to meet the increasing demand. A Global Industry Analysts Inc. report indicates that the herbal supplement market has not declined during the worldwide recession, but in fact exhibited steady growth over the period 2008 to 2009. It is anticipated that the market will reach US$93.15 billion by the year 2015. These supplements may contain adulterated substances that may potentially have harmful short - and long-term health consequences to the consumer. "Scrap Melamine" is such an example, which has been implicated in the kidney failure and death of several cats, dogs and pigs. In China in 2008, reports described very severe health effects in infants and young children. At the time over 294 000 infants were screened and diagnosed with urinary tract stones and sand-like calculi associated with melamine in milk products, of which 50 000 infants were hospitalised, and at least six associated deaths, recorded. The extent that melamine contamination occurs in nutritional supplements is not known. Therefore, the aim of this study was to determine whether commercially available nutritional and traditional supplement products contain melamine, even though they are not declared by the manufacturer on the product label. METHODS: A total of 138 nutritional supplements products were obtained from (i) direct purchases from shops, pharmacies and outlets, (ii) directly from consumers, and (iii) from suppliers, manufacturers and distributors. The products were laboratory analysed for melamine, using Tandem Liquid Chromatography Mass Spectrometry. RESULTS: Forty-seven % of all the products (n=138) tested positive for melamine. Eight-two % of the South African produced products (n=27) tested positive and 58 % of the products imported into South Africa (n=50) tested positive. The median concentration estimate for melamine in the products tested were, 6.0 mug/g for the 138 supplements tested, 8.9 mug/g for South African produced products, and 6.9 mug/g for products imported into South Africa. CONCLUSION: The melamine (undeclared on product label) levels detected in the nutritional supplements products investigated were within the Tolerable Daily intake (TDI) limit guidelines of 200 mug/g as set by WHO and others. Melamine over exposure within the context of the nutritional supplements consumption in the products investigated should not be of concern to the consumer provided the recommended guidelines of daily product use are adhered to. Further investigation is warranted to determine, (i) the link of melamine as (part) substitute for the perceived total declared protein content on the product label, (ii) cyanuric and uric acid presence in the supplement products that could form chemical-complex formation with melamine and/or analogues that could cause adverse health effects.
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    Preparation of pure and intact Plasmodium falciparum plasma membrane vesicles and partial characterisation of the plasma membrane ATPase
    (BioMed Central Ltd, 2002) Elandalloussi, Laurence; Smith, Pete
    BACKGROUND:In host erythrocytes, the malaria parasite must contend with ion and drug transport across three membranes; its own plasma membrane, the parasitophorous membrane and the host plasma membrane. Isolation of pure and intact Plasmodium falciparum plasma membrane would provide a suitable model to elucidate the possible role played by the parasite plasma membrane in ion balance and drug transport. RESULTS: This study describes a procedure for isolating parasite plasma membrane from P. falciparum-infected erythrocytes. With this method, the trophozoites released by saponin treatment were cleansed of erythrocyte membranes using anti-erythrocyte antibodies fixed to polystyrene beads. These trophozoites were then biotinylated and the parasite plasma membrane was disrupted by nitrogen cavitation. This process allows the membranes to reform into vesicles. The magnetic streptavidin beads bind specifically to the biotinylated parasite plasma membrane vesicles facilitating their recovery with a magnet. These vesicles can then be easily released from the magnetic beads by treatment with dithiotreithol. The parasite plasma membrane showed optimal ATPase activity at 2 mM ATP and 2 mM Mg2+. It was also found that Ca2+ could not substitute for Mg2+ ATPase activity in parasite plasma membranes whereas activity was completely preserved when Mn2+ was used instead of Mg2+. Other nucleoside triphosphates tested were hydrolysed as efficiently as ATP, while the nucleoside monophosphate AMP was not. CONCLUSIONS: We have described the successful isolation of intact P. falciparum plasma membrane vesicles free of contaminating organelles and determined the experimental conditions for optimum ATPase activity.
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    A rising-dose tolerance study in health human subjects, examining increasing doses of chlorproguanil with a constant dose of dapsone
    (2002) Blockman, Marc; Smith, Pete
    Includes bibliographical references.
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    Will the new Consumer Protection Act prevent harm to nutritional supplement users?
    (2011) Gabriels, Gary; Lambert, Mike; Smith, Pete; Hiss, Donavon
    BACKGROUND: There is no clear distinction between the regulation of food, supplements and medicines in South Africa. Consequently, grey areas exist in implementing the legislation, particularly in the supplement industry. The increase in supplement sales in South Africa can be attributed to aggressive marketing by manufacturers whose claims are not always supported by published peer-reviewed evidence. Such claims often go unchecked, resulting in consumers being mislead about the role of supplements. As a result of poor regulation, contaminants or adulterants in supplements may also cause insidious effects unrelated to the listed ingredients. AIM: To assess the regulations, legislation, and claims associated with nutritional supplement products in South Africa. METHOD: Peer-reviewed literature and the relevant South African statutes were consulted. RESULTS: The National Health Act incorporates the Medicine Control Council, which is charged with ensuring the safety, quality and effectiveness of medicines, and related matters, including complementary/alternative medicines. The South African Institute for Drug-Free Sport and Amendment Act provides for testing athletes for using banned substances, but currently does not concern itself with monitoring nutritional supplements for contaminants or adulterants that may cause a positive drug test, which has implications for sports participants and also the health of the general population. The implementation of the Consumer Protection Act 68 of 2008 (CPA) could protect consumer rights if it is administered and resourced appropriately. CONCLUSION: The CPA should promote greater levels of policy development, regulatory enforcement, and consumer education of South Africa's supplement industry.