Assay Information Sheets:
These information sheets cover the use and limitations of specific assays performed at Regional Laboratory Services, including sample requirements, methods and result ranges expected for various species.
Download Glutathione Peroxidase Assay Information Sheet
Download Liver Copper, Zinc, Manganese Assay Information Sheet
Download Vitamin B12 Assay Information Sheet
Download Ceruloplasmin Assay Information Sheet
Download D-Lactate Assay Information Sheet
Applied Research / Assay Validations:
Ammonia Determination - collection factors affecting ammonia concentration in serum/plasma/eye fluids in sheep and cattle.
Glutathione Peroxidase Vs Selenium in Liver
Liver Glutathione Peroxidase correlations with Liver Selenium - these correlations are used to validate the use of Glutathione Peroxidase in liver as an indicator of Selenium status in a range of species. Data for these correlations are derived from diagnostic submissions to Regional Laboratory Services ie. samples have been collected from a range of sites for reasons which may or may not be related to Selenium.
Glutathione Peroxidase Vs Selenium in Blood
Blood Glutathione Peroxidase correlations with whole blood Selenium - these correlations are particularly useful in assessment of acute Selenium toxicosis; selenium in Glutathione Peroxidase normally accounts for >75% of whole blood selenium and selenium is incorporated into Glutathione Peroxidase at erythropoesis. With acute toxicity, the proportion of non-selenium Glutathione Peroxidase is significantly increased. As with the liver Glutathione Peroxidase data, data for these correlations are derived from diagnostic submissions to Regional Laboratory Services.
Magnesium Assay Validations in Blood and Eye Fluids
Validation data for two colourimetric magnesium assays in blood and eye fluids; Xylidyl Blue assay (Thermo Fisher Scientific, Product #981884, modified to include sample blanking) and the CPZ III assay (Roche Product #20737593.322). Results for these two products are correlated with results obtained by Flame Atomic Absorption Spectroscopy (method of Phybus (1968) Clin. Chim. Acta 23, 309-317). Comparisons were made with non-haemolyzed serums, haemolyzed serums and eye fluid samples, over a range of magnesium concentrations. Samples were selected from ovine and bovine diagnostic samples submitted to RLS.
Post-Mortem effects on Bovine Eye Fluid Analytes
Eye fluids are a useful aid in ascertaining causes of death in production animals. In contrast to blood and cerebro-spinal fluids that can change rapidly post-mortem, concentrations of metabolites in eye fluids are in many instances far more stable.
Metabolites that can be routinely measured include: Calcium and Magnesium (monitoring for hypo-calcaemia, hypomagnesia), Urea (renal damage/shutdown/increased protein catabolism), B-hydroxybutyrate (ketosis), Nitrate/Nitrite (nitrate/nitrite poisoning), Glucose (clostridial disease), D-Lactate (lactic acidosis/grain overload), and Ammonia (urea toxicity/acute phalaris poisoning).
When sampling from the eye post-mortem, aqueous humour is the preferred sample. Aqueous humour is the fluid contained between the cornea and the lens (see diagram below). Vitreous humour is contained within the body of the eye. All validation work at Regional Laboratory Services has used aqueous humour as the sample.
Anatomy of the Mammalian Eye
Changes in eye fluid metabolites with time post-mortem are investigated in the attached Regional Laboratory Services studies.