INTRODUCTION Serum concentrations of acetaminophen are measured to predict the risk of hepatotoxicity in cases of acetaminophen overdose and to identify acetaminophen use in patients with acute liver injury without a known cause. The acetaminophen concentration determines if treatment with N-acetyl cysteine, the antidote for acetaminophen poisoning, is warranted. DESCRIPTION A 49-year-old wom...

The prevalence of drug-resistant strains of Mycobacterium tuberculosis (M. tb) emphasizes the need for new antitubercular drugs. An essential component of the drug discovery process is the development of tools to rapidly screen potential drug libraries against important biological targets. Similarly to well-documented M. tb targets, the antigen 85 (Ag85) enzymes are involved in the maintenance ...

This chapter describes the anatomy of an enzyme assay, focusing on the significance of separation and detection in the assay procedure. A classification of the methods used in the assay of enzymatic activities is developed, using the separation step as the criterion for the grouping. Having placed the high performance liquid chromatography (HPLC) method within this classification, we then exami...

Renal inulin clearance remains the standard by which other methods of measuring glomerular filtration rate are judged. A fully automated enzymatic assay capable of use with linear configuration inulin was recently published (Summerfield AL, et al. Clin Chem 1993; 39:2333-7). Sinistrin, a readily soluble preparation of polyfructan with side branching, is more suitable for clinical use and far mo...

We describe an assay for methotrexate in biological fluids. The assay is based on inhibition by methotrexate of dihydrofolate reductase from Lactobacillus casei. The lower limit of sensitivity in serum is 2 X 10(-8) mol (about 10 mug) of methotrexate per liter. Within-run precision is +/- 5% (coefficient of variation) and day-to-day variation is 18%. Advantages of the assay are ease of manipula...

correlated well with those by the highly sensitive enzymatic method (x; the ACS-myokinase-lactate dehydrogenase method) used routinely. The regression equation was y = 1.lx-25.4, the correlation coefficient 0.99, showing excellent correlation. Normal concentrations of various kinds of anticoagulants, albumin, glucose, ascorbic acid, and hemo-globin had no effects on the results. In conclusion, ...

The wide distribution of the uridine nucleotide-activated P2Y2, P2Y4 and P2Y6 receptors suggests a role for UTP as an important extracellular signalling molecule. However, direct evidence for UTP release and extracellular accumulation has been addressed only recently due to the lack of a sensitive assay for UTP mass. In the present study, we describe a method that is based on the uridinylation ...

(10) of 2.0 ␮g/L and Holt et al. (12) of Ͻ3.0 ␮g/L. HPLC-MS has no detectable interference with respect to endogenous compounds. The quantification limits based on acceptable imprecision, recovery, and ability to discriminate from potential interferences within the calibration range of the MEIA are 3.0 ␮g/L (the lower limit of quantification) to 22.0 ␮g/L. We have demonstrated that a higher lim...

A kinetic enzymological assay for methotrexate in serum is described; the results are available after 1.5 hours. The lower limit of sensivity is 50 nmol/1; the day-to-day variation coefficients compare favourably with other procedures (about 7% in the 200-600 nmol/1 range). The method uses purified dihydrofolic acid reductase from bovine liver. The problem of its instability in the assay is ci...

A two-step method for assaying creatinine in serum and urine samples, suitable with automated analyzers, is reported. Reagent 1, for the first step, contains a blanking system [creatine amidinohydrolase (CRTase), urease, glutamate dehydrogenase, NADPH, and 2-oxoglutarate] and a NADPH-regenerating system [Mg(2+)-dependent isocitrate dehydrogenase (ICD), MgCl2, and excess isocitrate]. Reagent 2, ...