Mycotoxin contamination of home-grown maize in rural northern South Africa (Limpopo and Mpumalanga Provinces).

The aim of this study was to assess mycotoxin contamination of crops grown by rural subsistence farmers over two seasons (2011 and 2012) in two districts, Vhembe District Municipality (VDM, Limpopo Province) and Gert Sibande District Municiality (GSDM, Mpumalanga Province), in northern South Africa and to evaluate its impact on farmers' productivity and human and animal health. A total of 114 maize samples were collected from 39 households over the two seasons and were analysed using a validated liquid chromatography-tandem mass spectrometry mycotoxins method. Aflatoxin B1 (AFB1) occurrence ranged from 1 to 133 µg kg(-1) in VDM while AFB1 levels in GSDM were less than 1.0 µg kg(-1) in all maize samples. Fumonisin B1 levels ranged from 12 to 8514 µg kg(-1) (VDM) and 11-18924 µg kg(-1) (GSDM) in 92% and 47% positive samples, respectively, over both seasons. Natural occurrence and contamination with both fumonisins and aflatoxins in stored home-grown maize from VDM was significantly (p < 0.0001) higher than from GSDM over both seasons.

Sequence of the cDNA encoding ovine tumor necrosis factor-alpha: problems with cloning by inverse PCR.

We have cloned and sequenced the ovine tumor necrosis factor-alpha (TNF-alpha)-encoding cDNA, using gene amplification by polymerase chain reaction (PCR) technology, to aid studies of assorted diseases in this species. We used primers selected from published TnfA sequences of other species on a cDNA template prepared from lipopolysaccharide-stimulated ovine alveolar macrophages, to generate a product representing the central region of the molecule. We then used a novel method based on 'inverse PCR' to generate a product containing the 5' and 3' ends of the molecule. Here, we present the complete sequence of the ovine TNF-alpha cDNA and compare it with other published TNF sequences. The cloned cDNA has a leader sequence of 156 bp followed by a protein-coding sequence of 702 bp and a 3'-untranslated region of 800 bp. The protein product of the gene is a protein of Mr = 25,586, 79% homologous to human TNF-alpha. An mRNA produced by alveolar macrophages, which hybridises to the cloned gene, is induced greatly, with a peak induction time of approx. 135 min, in response to stimulation by lipopolysaccharide and to plating on plastic. We also discuss the resolution of some artefacts of the inverse PCR technique.

Presentation of colour flow maps of the peripheral circulation.

The use of continuous wave Doppler ultrasound for lower limb arterial assessment is a well established technique in most district hospitals. Patients found to have disturbances in blood flow attributable to arterial plaques are often referred for arteriographic visualization of the disease with its inherent risks and complications. The availability of colour flow mapping on modern ultrasound scanners provides a non-invasive way of detecting the size and extent of these plaques and, in some institutions, is replacing arteriography. One possible disadvantage of the use of colour flow mapping is that it does not provide a permanent record showing the relationship of the plaques to the patient's gross anatomy in the same way as arteriography. This may limit the acceptability of this technique. At Lincoln work was undertaken to develop a system for presenting images of a whole segment of a limb simultaneously along with the associated blood velocity spectrum. This was performed first by hand and then a suite of computer software was developed to automate the process. Comparisons were made between the ultrasound based images and arteriography, showing the techniques to be of similar diagnostic value. The technique provides composite images showing anatomical detail, blood flow and velocity spectra for ease of interpretation. Further studies will be undertaken in order to define patient groups where diagnostic arteriography can be avoided.

Monitoring of recovery following exercise in the Doppler ultrasound evaluation of lower limb arterial disease.

Measurement of the ratio of ankle to brachial systolic blood pressure (pressure index) is an integral part of the Doppler ultrasound investigation of lower limb arterial disease. The recovery of this index following exercise gives further information regarding the clinical significance of the disease. However, serial sphygmomanometry may prolong recovery time by intermittent reduction of blood flow and for certain categories of patients the technique may prove impossible or will lead to unreliable results. The aim of this study was to investigate the use of Pourcelot's Resistance Index, measured from the Doppler blood velocity spectrum, as an alternative means of monitoring recovery. The results show that peripheral resistance is likely to fall following pressure measurement, indicating a potential effect on recovery time. There is reasonable correlation between post-exercise pressure and resistance indices (r = 0.69, P less than 0.001), and good correlation between their recovery times (r = 0.84, P less than 0.001) with no systematic deviation. Resistance index is therefore a viable alternative to pressure index for the monitoring of post-exercise recovery, and overcomes the problems associated with sphygmomanometry.

Expression and characterization of bioactive recombinant ovine TNF-alpha: some species specificity in cytotoxic response to TNF.

We have expressed and partially purified recombinant ovine tumour necrosis factor alpha (rovTNF-alpha) using a yeast Ty, virus like particle, expression system. RovTNF-alpha is at least as active as recombinant human TNF-alpha (rhTNF-alpha) in two different bio-assays performed on ovine material, whilst approximately 1000-fold more rovrTNF-alpha than rhTNF-alpha is required to induce the same level of cytotoxicity in TNF-sensitive murine cell lines L929 and WEHI 164 clone 13. When cytotoxic assays are performed on the porcine TNF sensitive cell line PK(15)-1512, rovTNF-alpha shows about 2 logs greater activity than on murine cells, whilst rhTNF-alpha is about 1 log more active. A monoclonal antibody, raised against rovTNF-alpha, has been used to demonstrate the presence of nanogram amounts of an appropriately sized glycoprotein to be native ovine TNF-alpha in supernants of LPS stimulated ovine alveolar macrophages. These samples show no detectable cytotoxicity to L929 cells, although they show activity attributable to TNF-alpha (through neutralization by a polyclonal antiserum raised to rovTNF-alpha) in an assay on ovine material. The relative lack of activity on murine cells helps to explain previous reports of inability to assay native ovine TNF-alpha using these cells, in spite of their routine use to assay TNF-alpha from several other species. The sequence features in ovine TNF-alpha which might reduce its affinity for the murine TNF type 1 receptor are discussed.