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OBJECTIVES To determine the pediatric reference ranges for iron, cortisol, CK, CKMB, and troponin I. METHODS Iron and CK were measured on the Vitros analyzer (Johnson and Johnson) while CKMB, troponin I, and cortisol were measured on the Immuno I (Bayer Corp.). Pediatric reference ranges were determined on hospitalized patients using the Hoffmann(More)
OBJECTIVES Tacrolimus (FK506) is an immunosuppressive drug with great clinical promise. There is a controversy regarding the role of tacrolimus metabolites in immunosuppression and toxicity, and immunoassays and immunophilin binding assays have not been adequately tested for metabolite cross-reactivity. Methods are limited to HPLC and HPLC-MS for(More)
OBJECTIVE To evaluate the Point-of-Care (POC) i-STAT system for measuring blood gases (pH, pCO2, pO2) and whole blood electrolytes (sodium, Na+, potassium, K+ and ionized calcium, iCa2+) in the neonatal and pediatric intensive care units. DESIGN AND METHODS The i-STAT system was evaluated for imprecision, necessity of running quality control and accuracy.(More)
OBJECTIVES To determine the effect of gestational age and birth weight (BW) on troponin I (TnI) and creatine kinase MB fraction (CKMB) levels during the first year of life. METHODS Troponin I and CKMB levels were determined in infants less than 1 year of age using the Immuno I (Bayer Corp.). RESULTS Troponin I fractions were greatest in the preterm(More)
OBJECTIVES To compare the binding characteristics of four rapamycin (RAPA) metabolites to the 14 and 52 kDa minor immunophilins with their pharmacologic activity, as measured by the mixed-lymphocyte culture (MLC) assay. METHODS Four RAPA metabolites were isolated by HPLC from the urine of renal transplant patients. Each metabolite was evaluated at 40(More)
OBJECTIVES There is a controversy regarding the role of cyclosporine (CsA) metabolites in both immunosuppression and toxicity, and measurement of the parent drug is commonly recommended. High performance liquid chromatography (HPLC) is the method commonly used for specific measurement of the parent drug, but is very time consuming. Antibody techniques are(More)
We describe a quantitative radioreceptor assay (RRA) for quantifying FK-506 in whole blood. FK-506 extracted from whole blood with a cyclohexyl-sorbent column competes with [3H]dihydro-FK-506 for binding to a partially purified preparation of FK-506 binding protein (FK-BP). Free and protein-bound FK-506 are separated on LH 20 Sephadex chromatographic(More)
The major immunophilins that bind cyclosporine (cyclophilin) and FK-506/rapamycin (FK-BP 12) have been well characterized. They possess rotamase activity, which is inhibited by the immunosuppressant that binds to them. The immunosuppressive action does not appear to be coupled to rotamase activity. The literature is reviewed on some possible mechanisms of(More)
OBJECTIVES We have previously identified a minor immunophilin of 52 kDa molecular weight capable of binding tacrolimus and sirolimus. Because immunophilins are capable of binding both parent drug and metabolites and HPLC assays are typically used to assess parent drug in clinical situations, we used this immunophilin in a radioreceptor assay (RRA) to(More)