Rapid methods for differentiating reactivated from residual phosphatase in milk and cream: collaborative study.

Three methods for differentiating reactivated from residual phosphatase in milk and cream were collaboratively tested using both magnesium acetate and magnesium chloride for reactivating phosphatase. The methods evaluated were the modified Scharer rapid test, the rapid colorimetric test, and the Rutgers method. Nine collaborators tested 6 unknown milk samples containing reactivated and/or residual phosphatase, and 16 collaborators tested 6 unknown cream samples containing reactivated and/or residual phosphatase. Results indicated that use of magnesium acetate in place of magnesium chloride for reactivating phosphatase improved test results. Visual tests (modified Scharer rapid and Rutgers) predicted correct results when the samples contained high levels of reactivated or residual phosphatase. In borderline cases where the reactivated phosphatase contents of the undiluted control sample and the diluted sample containing Mg were very close, the test results of the visual methods were significantly different from 100% correct results at the alpha=0.05 level. Use of a photoelectric colorimeter or its equivalent for measuring the absorbance in conjunction with the modified Scharer rapid test improved results considerably. The modified Scharer rapid test was adopted official first action.     

Die norwegische Krähen-Massenfalle

Ohne Zusammenfassung     

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.     

Proliferative kidney disease and renal myxosporidiosis in juvenile salmonids from rivers in England and Wales

The results from a survey for proliferative kidney disease (PKD) and renal myxosporidiosis in wild salmonids from rivers in England and Wales are presented. One hundred and eighty-five salmon, Salmo salar , 235 brown trout, Salmo trutta , 16 charr, Salvelinus alpinus, and five grayling, Thymallus thymallus, were obtained from 23 locations on 16 rivers between July and October 1997. They were examined for the presence of clinical PKD and for histological evidence of infections with Tetracapsula bryosalmonae and other renal myxozoans. Prevalence of infection with T. bryosalmonae detected histologically in brown trout varied from 11 to 43% in enzootic rivers and was only found in salmon in two rivers at low prevalence. Nephromegaly was positively associated with PKD in brown trout but in salmon mild nephromegaly was only associated with infection with an unidentified Chloromyxum sp.     

Investigation on the effects of ciclosporin (Atopica) on intradermal test reactivity and allergen‐specific immunoglobulin (IgE) serology in atopic dogs

The ability to use ciclosporin (Atopica^®: Novartis Animal Health, Greensboro, NC, USA) prior to intradermal testing (IDT) would help avoid exacerbation of clinical disease that can be associated with drug withdrawal. This study evaluated the effects of 30 days of administration of ciclosporin at a dose of 5 mg/kg once daily on IDT reactivity (immediate phase reactions) in a group of dogs with atopic dermatitis (AD) with initial positive IDT reactions. 16 dogs diagnosed with AD were included in the study. Eight dogs (group A) were treated with ciclosporin orally at 5 mg/kg once daily for 30 days. Eight dogs (group P) were treated with a placebo orally once daily for 30 days. IDT was performed at day 0 and day 30 on all dogs enrolled using a standardized panel of 45 aqueous allergens (Greer Laboratories, Lenoir, NC, USA) appropriate to our geographical region. IDT reactivity was assessed by both subjective and objective methods at 15 min post‐intradermal injection. Serum for allergen‐specific immunoglobulin (IgE) serology was obtained at day 0 and day 30. The study was designed as a double‐blinded, placebo‐controlled, cross‐over study. Data were analysed using a split‐plot analysis of variance with the grouping factor of treatment and the repeat factor of time (SAS System for Windows). At week 4, ciclosporin did not have a statistically significant effect on IDT reactivity or serology results. It therefore appears that, no withdrawal is recommended to evaluate immediate phase reactions.     

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.     

Direct plating method for enumeration of Staphylococcus aureus: collaborative study.

Considerable evidence has been published regarding the adverse effect of sodium chloride on physiologically impaired cells of Staphylococcus aureus, such as are to be expected in processed foods. A direct plating method for enumeration of S. aureus eliminating the use of sodium chloride was devised and subjected to collaborative study by 16 analysts. Results obtained by the direct plating method were compared to those obtained by the AOAC official first action method (46.036--46.040). Participating analysts examined duplicate samples at population levels of 91, 34, and 20 S. aureus/g. Coefficients of variation among analysts were considerably lower for the direct plating method (31, 81, and 48%, respectively) than for method 46.040 (59, 156, and 150%, respectively) at all 3 population levels. High coefficients of variation for the direct plating method at 2 of the 3 levels were due principally to low populations of S. aureus. The direct plating method has been adopted as official first action for general purpose use and use of method 46.036--46.040 has been restricted to raw food ingredients and nonprocessed foods.