Simultaneous measurement of phenylalanine and tyrosine by high performance liquid chromatography (HPLC) with fluorescence detection.

Objectives: An HPLC method was developed to quantify serum concentrations of phenylalanine and tyrosine simultaneously using fluorescence detection without derivatization.

Methods: Serum protein is precipitated with trichloroacetic acid, 0.015mM dihydrogen-phosphate solution is used for separation on reversed-phase C18 material, and acetonitrile is avoided.

Performance of a fully automated quantitative neopterin measurement assay in a routine voluntary blood donation setting.

Background: Acute virus infections are indicated by increased serum neopterin concentrations. Testing of blood donations for increased neopterin was introduced in the Austrian Tyrol in 1986 and throughout Austria in 1994 to improve the safety of blood transfusions. Radioimmunoassay (RIA) was the first available test, and the 98th percentile for neopterin concentrations from 76,500 donations was defined as the cut-off threshold, excluding donations with neopterin >or=10 nmol/L.

Acute cytomegalovirus infections in blood donors are indicated by increased serum neopterin concentrations.

In Austria serum neopterin measurement was introduced as an additional unspecific screening marker for the detection of routinely unscreened viral infections in blood donations in 1994. This study was performed to test for associations between serum neopterin concentrations in blood donations and cytomegalovirus infections of the donors. All consecutive blood donations from volunteer blood donors collected during 1 year were incorporated into the study.

Human parvovirus Bb19 detection in asymptomatic blood donors: association with increased neopterin concentrations.

Serum neopterin concentrations were determined in 20,000 blood donations. For the 400 donations with neopterin concentrations above the 98 th percentile and another 1200 donations with neopterin concentrations in the lower range, results of human parvovirus (HPV) B19 tests were compared. Infectious specimens were identified by dot blot hybridization assay and polymerase chain reaction (PCR) that used the outer primers and detected 1 pg of HPV B19 DNA, corresponding to approximately 10(5) copies of the genome, in the specimens and by a nested PCR that detected 1-10 fg of DNA, corresponding to 10(2)-10(3) copies of the genome.