Does Determining Tumor Markers from the Testicular Vein Enable Better Diagnosis and Prognosis?

INTRODUCTION: ß-HCG has been the only tumor marker evaluated in testicular vein (VT) blood until now. OBJECTIVE: To evaluate the correlation between the tumor markers ß-HCG, AFP, PLAP, and LDH from the VT and peripheral blood as well as their significance in predicting tumor recurrence and tumor stage. METHODS: Patients with testicular cancer undergoing orchiectomy were studied retrospectively over a period of 20 years. Tumor stage, tumor histology, time to tumor recurrence, and tumor markers from VT and peripheral blood were analyzed. Minimal follow-up was 2 years. Statistical analysis was performed by means of Cox- and logistic regression models and Spearman rank correlation coefficients. RESULTS: A total of 172 patients with an average follow-up of 9.9 years were investigated. The overall recurrence rate was 18% (seminoma patients 20.8%, nonseminoma patients 14.5%). Marker values measured from VT blood were higher than in peripheral blood and correlated strongly with the peripherally measured values. AFP obtained from peripheral blood was the only tumor marker allowing a statement on the recurrence probability. Tumor markers from VT blood showed no correlation with tumor stage. DISCUSSION/CONCLUSION: Tumor markers from VT blood are significantly higher than in peripheral blood. Tumor markers obtained from VT blood do not provide clinical advantage in terms of assessing tumor stage and recurrence probability.

Improvement of an antibody-enzyme coupling yield by enzyme surface supercharging.

BACKGROUND: Protein cross-coupling reactions demand high yields, especially if the products are intended for bioanalytics, like enzyme-linked immunosorbent assays. Amongst other factors, the coupling yield depends on the concentration of the proteins being used for coupling. Protein supercharging of enzymes can increase the solubility dramatically, which could promote enzyme-antibody coupling reactions. A highly soluble, supercharged variant of the enzyme human enteropeptidase light chain was created by a site-directed mutagenesis of surface amino acids, used for the production of an antibody-enzyme conjugate and compared to the wild type enzyme. RESULTS: Wild type and mutant enzyme could successfully be cross-coupled to an antibody to give antibody-enzyme conjugates suitable for ELISA. Their assay performances and the analysis of the enzyme activities in solution demonstrate that the supercharged version could be coupled to a higher extent, which resulted in better assay sensitivities. The generated conjugate, based on the supercharged enzyme, was feasible as a reporter molecule in a sandwich ELISA and allowed the detection of epidermal growth factor with a detection limit of 15.63 pg (25 pmol/L). CONCLUSION: The highly soluble, surface supercharged, human enteropeptidase light chain mutant provided better yields in coupling the enzyme to an antibody than the wild type. This is most likely related to the higher protein concentration during the coupling. The data suggest that supercharging can be applied favourably to other proteins which have to be covalently linked to other polymers or surfaces with high yields without losses in enzyme activity or specificity.

Highly adaptable and sensitive protease assay based on fluorescence resonance energy transfer.

Proteases are widely used in analytical sciences and play a central role in several widespread diseases. Thus, there is an immense need for highly adaptable and sensitive assays for the detection and monitoring of various proteolytic enzymes. We established a simple protease fluorescence resonance energy transfer (pro-FRET) assay for the determination of protease activities, which could in principle be adapted for the detection of all proteases. As proof of principle, we demonstrated the potential of our method using trypsin and enteropeptidase in complex biological mixtures. Briefly, the assay is based on the cleavage of a FRET peptide substrate, which results in a dramatic increase of the donor fluorescence. The assay was highly sensitive and fast for both proteases. The detection limits for trypsin and enteropeptidase in Escherichia coli lysate were 100 and 10 amol, respectively. The improved sensitivity for enteropeptidase was due to the application of an enzyme cascade, which leads to signal amplification. The pro-FRET assay is highly specific as even high concentrations of other proteases did not result in significant background signals. In conclusion, this sensitive and simple assay can be performed in complex biological mixtures and can be easily adapted to act as a versatile tool for the sensitive detection of proteases.

Synthesis of pathological and nonpathological human exon 1 huntingtin.

Huntington's disease (HD) is a neurodegenerative disorder that affects approximately 1 in 10 000 individuals. The underlying gene mutation was identified as a CAG-triplet repeat expansion in the gene huntingtin. The CAG sequence codes for glutamine, and in HD, an expansion of the polyglutamine (poly-Q) stretch above 35 glutamine residues results in pathogenicity. It has been demonstrated in various animal models that only the expression of exon 1 huntingtin, a 67-amino acid-long polypeptide plus a variable poly-Q stretch, is sufficient to cause full HD-like pathology. Therefore, a deeper understanding of exon 1 huntingtin, its structure, aggregation mechanism and interaction with other proteins is crucial for a better understanding of the disease. Here, we describe the synthesis of a 109-amino acid-long exon 1 huntingtin peptide including a poly-Q stretch of 42 glutamines. This microwave-assisted solid phase peptide synthesis resulted in milligram amounts of peptide with high purity. We also synthesized a nonpathogenic version of exon 1 huntingtin (90-amino acid long including a poly-Q stretch of 23 glutamine residues) using the same strategy. In circular dichroism spectroscopy, both polypeptides showed weak alpha-helical properties with the longer peptide showing a higher helical degree. These model peptides have great potential for further biomedical analyses, e.g. for large-scale pre-screenings for aggregation inhibitors, further structural analyses as well as protein-protein interaction studies.