Sulphur dioxide sensitivity in South African asthmatic children

Sulphur dioxide (SO2) is a well-known precipitant of asthmatic attacks. Many foodstuffs are preserved with SO2 and other sulphites. In this study 37 asthmatic children attending the Allergy Clinic at the Red Cross Children's Hospital were challenged with SO2 in apple juice in a dose similar to that commonly ingested in soft-drinks containing this preservative. The responses of these children were compared with the responses of 22 asthmatics challenged with apple juice alone.Sixteen out of 37 children (43,2%) challenged with SO2 reacted with a fall in forced expiratory volume in 1 second (FEV1) of more than 10% compared with none of the 22 control asthmatic children challenged with apple juice alone (P = 0,0016). Girls were found to be more sensitive than boys. A 20% or more fall in FEV1 occurred in 8 (21,6%) of the children challenged with SO2 compared with none in the control group (P = 0,039). There was an individual variability in the responses of sensitive individuals to the SO2 challenge. Reactions occurred in spite of maintenance medication and occurred within 5 - 30 minutes of challenge. Since sulphite sensitivity is common in asthmatic children, ingestion of sulphites should be avoided

Decreased TNF-α synthesis by macrophages restricts cutaneous immunosurveillance by memory CD4+ T cells during aging

Immunity declines during aging, however the mechanisms involved in this decline are not known. In this study, we show that cutaneous delayed type hypersensitivity (DTH) responses to recall antigens are significantly decreased in older individuals. However, this is not related to CC chemokine receptor 4, cutaneous lymphocyte-associated antigen, or CD11a expression by CD4+ T cells or their physical capacity for migration. Instead, there is defective activation of dermal blood vessels in older subject that results from decreased TNF-α secretion by macrophages. This prevents memory T cell entry into the skin after antigen challenge. However, isolated cutaneous macrophages from these subjects can be induced to secrete TNF-α after stimulation with Toll-like receptor (TLR) 1/2 or TLR 4 ligands in vitro, indicating that the defect is reversible. The decreased conditioning of tissue microenvironments by macrophage-derived cytokines may therefore lead to defective immunosurveillance by memory T cells. This may be a predisposing factor for the development of malignancy and infection in the skin during aging

Should food labelling be made mandatory?

EditorialThe original publication is available at http://www.samj.org.za[No abstract available]Publisher’s versio

Evaluation of the 16S and 12S rRNA genes as universal markers for the identification of commercial fish species in South Africa

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Evaluating the availability of fish species on the South African market and the factors undermining sustainability and consumer choice

Information pertaining to the commercial availability of fish species in South Africa remains sparse, even though it is crucial for consumers to make informed purchasing decisions in favour of their own well being and the well being of the environment. The aim of this study was to determine the most commonly available fish species in South Africa by means of surveys of restaurants (n = 215) and retail outlets (n = 200) and to assess the conservation statuses of the observed species. Furthermore, the processing states in which fish were mostly sold (fresh, frozen, whole or filleted) and the quality of information available to consumers on fish at the point of sale were evaluated. Kingklip was found to be the most commonly marketed fish species in restaurants, while hake was observed most frequently in retail outlets. More than 30% of the observed species were of conservation concern and included, amongst others, kingklip, kabeljou (kob), east- and west coast soles and geelbek. Specially-protected, illegal-to-sell fish in South Africa, such as white steenbras, white musselcracker and Natal stumpnose, were marketed in restaurants and retail outlets. This study highlighted the poor ability of fish purveyors in South Africa to provide information on the identity, origin, production method and sustainability of fish being sold. Additionally, the labelling of many packaged fish products in retail outlets was in contravention with South African regulations. Poor vendor awareness, disparate naming practices and the highly processed nature of fishery products provide an opportunity for unintentional or deliberate mislabelling of fish in South Africa. © 2011 Elsevier Ltd.Articl

Establishment of a mitochondrial DNA sequence database for the identification of fish species commercially available in South Africa

Article in PressThe limitations intrinsic to morphology-based identification systems have created an urgent need for reliable genetic methods that enable the unequivocal recognition of fish species, particularly those that are prone to overexploitation and/or market substitution. The aim of this study was to develop a comprehensive reference library of DNA sequence data to allow the explicit identification of 53 commercially available fish species in South Africa, most of which were locally caught marine species. Sequences of approximately 655 base pairs were generated for all species from the cytochrome c oxidase I (COI) gene, the region widely adopted for DNA barcoding. Specimens of the genus Thunnus were examined in further detail, employing additional mitochondrial DNA control region sequencing. Cumulative analysis of the sequences from the COI region revealed mean conspecific, congeneric and confamilial Kimura 2-parameter distances of 0.10%, 4.58% and 15.43%, respectively. The results showed that the vast majority (98%) of fish species examined could be readily differentiated by their COI barcodes, but that supplementary control region sequencing was more useful for the discrimination of three Thunnus species. Additionally, the analysis of COI data raised the prospect that Thyrsites atun (snoek) could constitute a species pair. The present study has established the necessary genetic information to permit the unambiguous identification of 53 commonly marketed fish species in South Africa, the applications of which hold a plethora of benefits relating to ecology research, fisheries management and control of commercial practices. © 2011 Blackwell Publishing Ltd