BACKGROUND: Prostatic fluid (PF) provides a unique medium for noninvasive evaluation of critical growth and differentiation signals in the prostatic microenvironment. The purpose of this study was to establish the feasibility of measuring two prostatic mitogens, epidermal growth factor (EGF) and transforming growth factor-alpha ( @entity7790 ) in PF, and specifically to quantify extraneous variability attributable to the assay itself, sample handling, or biological variation within an individual over time. METHODS: PF was collected by transrectal massage from consecutive @entity1 attending a urology clinic. Pooled PF and individual samples from 25 @entity1 with stable @entity1067 ( @entity1067 ) were analyzed for EGF and @entity7790 by radioimmunoassay and for total protein. RESULTS: Reproducibility was adequate at dilutions as low as 1:50 (2-microliter pooled sample) and 1:5 (20 microliters) for EGF and @entity7790 , respectively. Results were not affected by freeze-thaw cycles, time in storage, or protease inhibition in fresh PF. EGF and @entity7790 were detectable in 100% and 92% of individual @entity1 , with respective means of 152 and 0.2 ng/ml. Correlations between two samples obtained from the same @entity1 within 12 months were highly significant (EGF r = 0.89, @entity7790 r = 0.71). Protein concentrations were consistent over time; expression of either peptide per weight of protein rather than per volume did not improve within- @entity1 correlation. Between- @entity1 variability far exceeded within- @entity1 variability for both peptides, and was estimated to account for 84% and 61% of the total variability in EGF and @entity7790 , respectively. There was no correlation between EGF and @entity7790 in the same samples. CONCLUSIONS: We conclude that @entity1 with @entity1067 secrete consistent and distinct levels of EGF-related peptides in PF, and that these levels can be detected with acceptable sensitivity and precision by radioimmunoassay (RIA). Measurement of @entity7790 , which has not been reported previously, requires a relatively larger sample.

Epidermal growth factor-related peptides in XXXX prostatic fluid: sources of variability in assay results.

@entity1 :: ('9606', 'Species') :: ['patients', 'man', 'men'] @entity1067 :: ('MESH:D011470', 'Disease') :: ['benign prostatic hyperplasia', 'BPH'] @entity7790 :: ('7039', 'Gene') :: ['TGF-alpha']
@entity1 :: (9606,Species) :: ['human']
