Publications by authors named "Daniel Juan Herrera"
Background: Enzymatic assays using glutamate dehydrogenase (GLDH) to monitor the transformation of NAD(P)H to NAD(P)(+) by a spectrophotometric technique are the most common methods to measure plasma ammonia (PA) in routine laboratories worldwide. However, these assays can potentially be subject to interference by substances in plasma able to oxidize NAD(P)H at a substantial rate, thereby providing falsely high results.
Methods: To study this potential interference, we spiked a plasma pool with a liver homogenate and measured the ammonia concentration using a dry chemistry system (Vitros 250, Ortho Clinical Diagnostic, Raritan, NJ, USA), an enzymatic assay without a sample blanking step (Infinity Ammonia Liquid Stable Reagent, Thermo Fisher Scientific, Waltham, USA) and an enzymatic assay that corrects for the non-specific oxidation of NADPH (Ammonia kit, RANDOX Laboratories Ltd, Crumlin, UK).
Background: Plasma ammonia (PA) measurement is of key importance in the diagnosis and monitoring of some inherited metabolic disorders and to monitor subsequent treatment of hyperammonaemia.
Methods: Over a six-month period, patients' ammonia concentrations were measured in parallel, using an enzymatic-UV kit (Infinity Ammonia Liquid Stable Reagent, Thermo Electron Corporation, Australia) on an Olympus AU640 analyser (Olympus UK Ltd, Hertfordshire) and on our current dry chemistry system (Vitros 250, Ortho Clinical Diagnostic). Alanine amino transferase (ALT) was added to a human plasma sample to investigate its effect on the assessment of ammonia concentration.
Background: D-lactate is essentially a product of bacterial metabolism, and its assessment in plasma has been mainly used to diagnose D-lactic acidosis in patients with short bowel syndrome. In the last few years, there has been growing interest in the use of subclinical elevations of D-lactate concentrations as a diagnostic tool in a variety of clinical conditions such as ischaemia, trauma or infection.
Methods: An endpoint enzymatic spectrophotometric assay to measure plasma D-lactate with a sample blank correction was validated on our routine clinical chemistry analyser (Olympus AU640).