Judith A.P. Bons

Protein profiling as a diagnostic tool in clinical chemistry: a review

Abstract Serum protein profiling by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) appears to be an important diagnostic tool for a whole range of diseases. Sensitivities and specificities obtained with this new technology often seem superior to those obtained with current biomarkers. However, reproducibility and standardization are still problematic. The present review gives an overview of the diagnostic value of protein profiles obtained with SELDI in studies on prostate and ovarian cancer. To identify aspects important for protein profiling, we compare and discuss differences in pre- and post-analytical conditions presented in the literature supplemented with some of our own data. Further progress in protein profiling as a diagnostic tool requires a more comprehensive description of technical details in all future studies.

Clinical proteomics in chronic inflammatory diseases: A review

There is a need for better markers for the diagnosis and prognosis of chronic inflammatory diseases. Proteomic strategies can be helpful to detect new biomarkers. Proteomic analyses are performed to characterize the behaviour of the system rather than the behaviour of any single component. Since the genome has been unravelled, the proteome received more attention. Aim of this review was to focus on the use of different proteomics techniques to detect potential and/or common biomarkers in chronic inflammatory diseases. The identified and validated proteins detected in the different studies are compared and discussed to conclude if there are some common markers which can be used in the diagnosis and prognosis of the three chronic inflammatory diseases described in this study; multiple sclerosis, rheumatic diseases and lung inflammatory diseases. The heat shock protein family (hsp) was entitled as biomarkers with potential for further research in multiple sclerosis. Myeloid‐related protein 8 (MRP‐8) was found in three different rheumatoid arthritis (RA) studies with different sample materials and could be a potential marker for RA. α1‐Antitrypsin was validated in two studies as a marker for sarcoidosis and α1‐antitrypsin was also found to be a marker for cystic fibrosis (CF), together with myeloperoxidase and IgG.

A multicenter evaluation of dysthyroxinemia in a defined patient cohort

Abstract Background: In the region Limburg (The Netherlands) almost all of the five participating laboratories use a different immunoassay platform to determine thyroid stimulating hormone (TSH) and free thryoxine (FT4). With the frequent transfer of patients within the region, harmonization of test result interpretation is necessary. In this study, we investigated dysthyroxinemia classification between participating laboratories and developed procedures for improvement. Methods: Two ring surveys with an interval of 2 years were performed. Four patient groups (n=100) with different dysthyroxinemia classification were based on biochemical results of the Autodelphia analyzer. Samples were tested in five participating laboratories. In each group the percentage of patients classified with dysthyroxinemia was calculated and differences were analyzed by the Fisher’s exact test. Results: After the first survey, the percentage of patients with hyperthyroxinemia was more than 20% lower in three laboratories compared to the other two. Bhattacharya analysis revealed that the upper reference limit of FT4 was 20%–30% too high in two laboratories. Adjustments of reference ranges appeared to be effective in the second survey. The third laboratory reported significantly lower percentages of patients with hyperthyroxinemia in the second survey. New FT4 reference ranges were determined for this laboratory, resulting in adequate classification of hyperthyroxinemia. Conclusions: This study illustrates the potential of a multicenter evaluation of dysthyroxinemia in a biochemical-defined patient cohort. In particular, classification of hyperthyroxinemia differed between laboratories. Adjustments of reference ranges resulted in better agreement of dysthyroxinemia classification. Even using internal and external quality assurance programs, application of multicenter ring surveys is advised to prevent inadequate reference ranges.

Assay-specific pitfalls of catecholamine HPLC assays

1 Department of Clinical Chemistry , Maastricht University Medical Center, Maastricht , The Netherlands 2 Department of Internal Medicine , Division of Endocrinology, Maastricht University Medical Center, Maastricht , The Netherlands 3 Department of Cardiology , Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht , The Netherlands 4 Department of Laboratory Medicine , University Medical Center, Groningen, University of Groningen , The Netherlands

Searching for potential biomarkers that can be used as biomarkers for diagnosing ankylosing spondylitis

AIM Ankylosing spondylitis (AS) is a chronic systemic inflammatory rheumatic disorder that primarily affects the axial skeleton. To date there is no satisfactory biomarker for diagnosis or prognosis of AS. This study is focused on detection of potential biomarkers for the diagnosis of AS using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) with the ultimate goal of developing a progression biomarker for AS. MATERIALS & METHODS Protein profiles of sera of 38 AS patients and 38 healthy controls were obtained using ProteinChip arrays. Different arrays and conditions were compared with find out which condition resulted in the optimal discrimination of both groups. RESULTS Optimal discrimination was reached using weak cation exchange (CM10) and immobilized metal affinity capture coupled with copper (IMAC-Cu(2+)) arrays. Using a multimarker approach on protein profiles obtained with CM10 arrays resulted in a sensitivity of 66% and a specificity of 74%. Using a multimarker approach on protein profiles obtained with IMAC-Cu(2+) arrays resulted in a sensitivity and specificity of 70%. CONCLUSIONS This is the first study that shows that protein profiling in serum using SELDI-TOF-MS can be used as a diagnostic tool for AS. The biomarkers will be validated to confirm if they can be used as progression biomarkers.