The Screening of River Water for Immunotoxicity Using an In Vitro Whole Blood Culture Assay

The acquired immunity consists of two pathways namely the humoral immunity that defends the host against extracellular pathogens such as bacteria and the cell-mediated immunity that defends the host against intracellular pathogens such as Mycobacterium tuberculosis and viruses and also against cancers. The aim of this study is to determine the effects of river water collected from pristine and contaminated sites along the Eerste River, South Africa on inflammation, humoral and acquired immune pathways. Hydrophobic extracts were prepared from water collected at contaminated and pristine sites. Inflammatory activity was determined by measuring interleukin (IL)-6 levels synthesized by whole blood after incubation with the extracts. For determining the effects on acquired immunity, phytohemagglutinin stimulated whole blood from healthy volunteers was incubated with extracts. The effect on humoral immunity was determined using IL-10 as biomarker, while interferon-gamma was used as biomarker for cell-mediated immunity. The results obtained show that water from the sites downstream from human activity induced IL-6, a biomarker of inflammation. Extracts collected from a site downstream from an informal housing settlement suppressed biomarkers of both humoral and cell-mediated immunity. Water from sites impacted by human activity can potentially suppress the acquired immune system and this can pose a health risk to people using this water source. Studies must be done to investigate the long-term effects of the contaminated water on animals in vivo.     

Deposition of fine sediments in irrigation canals

Sediment control structures constructed at the heads of run-of-river irrigation schemes have little effect on the very fine sands and silts that settle in the smaller distribution canals. One means of minimising the effects of fine sediment deposition in small canals is to design canals so that deposition occurs at selected locations, rather than throughout the canal network. Standard sediment transport predictors cannot be used to predict the effects of changing canal slopes and cross sections when sediment sizes are very small, and thus cannot be used to determine dimensions and slopes of small canal settling basins.The paper presents a simple method for estimating the transport and deposition rates of fine sediment suspensions, for sediments in the cohesive size range. The method, which has been tested against a large data set, enables the effects of changing canal cross sections and slopes on fine sediment transport to be quantified.     

Determination of alkaline phosphatase in casein: collaborative study

A collaborative study was made to determine alkaline phosphatase in casein samples by the rapid colorimetric test. Six to eight collaborators tested 10 unknown casein samples containing various amounts of residual phosphatase with and without the addition of magnesium acetate. Results indicated that magnesium acetate significantly increased phosphatase activity. The collaborators correctly analyzed 95% of the samples with the added magnesium acetate. The method has been adopted official first action.     

Precision parameters of standard methods of analysis for dairy products

The available collaborative studies for standard methods of analysis for various constituents of milk and milk products were examined in an attempt to assign specific repeatability and reproducibility precision parameters to these methods. The different collaborative assays for the primary constituents (moisture/solids, fat, protein), the nutritionally important elements (calcium, sodium, potassium, phosphorus), and miscellaneous analytes/physical constants (ash, lactose, salt, freezing point) produced different estimates of the precision parameters for the same method. A suitable summary of the precision estimates from collaborative studies is given by the reproducibility relative standard deviation, RSDg, which is relatively constant within a product and permits comparisons across products. An estimate of the variation of RSDR for an analyte from a number of collaborative studies is presented in terms of the median and 90% interval (the range of the centermost 90% of values). These estimates are only informative when a substantial number of independent studies are available for pooling the independent estimates to form a distribution of RSDR values. The RSDR for the determination of the primary constituents of milk and milk products is characterized by a median RSDR of 1% and a 90% interval of 0.3-3%, with RSDR estimates occasionally occurring below 0.3% and above 4%. These overall estimates appear to be independent of analyte, matrix, and method and apply to concentrations of primary constituents that range from about 2 to 80%. The repeatability relative standard deviation, RSDr, is unstable, although it tends to converge to about 0.5-0.7 X RSDR. Too few collaborative assays are available to characterize RSDR for the determination of certain other constituents (acidity, ash, lactose, salt, and the nutritionally important elements) unless RSDR values for different analytes, methods, and matrixes are pooled on the basis of similar analyte concentrations. When pooled, the RSDR values are generally better than predicted from the Horwitz equation, RSDR (%) = 2 exp (1-0.5 log10C), where C is the concentration expressed as a decimal fraction; all but one of 661 RSDR values are within the upper empirical limit of twice this curve.