The potential use of biochemical-physiological simulation models in clinical chemistry

Metabolism of guanosine in human erythrocytes

The metabolism of guanosine in human erythrocytes has been studied in two different experimental systems--direct incubation and dialysis incubation--the latter allowing continuous addition and removal of substances. Intra- and extracellular purine compounds were analyzed using high-performance liquid chromatography (HPLC). At 37 degrees C, a normal pH (7.4) and a favorably high concentration of inorganic phosphate, guanine nucleotides were synthesized at a substance rate of about 0.17 mmol . h-1 (calculated per liter erythrocytes) when guanosine was kept at a concentration of 25 mumol . l-1. At a higher guanosine concentration the rate of synthesis increased only moderately. Erythrocytes loaded with guanylates lost these nucleotides at a rate of 0.023 mmol . h-1 at a normal phosphate concentration and somewhat slower at a higher phosphate concentration. The metabolism kept the guanylates in an equilibrium that was similar to the equilibrium between the adenylates.

Methods and approaches to determine "optimal" quality for clinical chemical data

Although clinical reasoning and decision-making may be very complex, there are methods to perform both piecemeal and more complete optimizations with regard to the use of clinical chemical data and for assessing quality specification. Some methods and approaches are described and illustrated with examples: (i) rules for propagation of errors in simple algebraic/statistical transformations; (ii) systems and sensitivity analysis using biochemical/pathophysiological simulation models; (iii) systems and sensitivity analysis of simulated clinical classification and decision processes. It is concluded that the possible gain of useful information by improving analytical and pre-analytical quality should be related to the often more important aspects of test selection test and test combination, period and frequency of observation, and the use of correct conceptual models for transformation of data.