We have previously shown that seminal vesicle protein IV (SV-IV) and its 1-70 N-terminal fragment have anti-inflammatory activity and modulate anti-thrombin III (AT) activity. Moreover, mass spectrometry analysis of purified SV-IV has shown that the protein was found to be highly heterogeneous and 14% of the total SV-IV molecules are truncated forms, of particular interest the 1-16, 1-17, and 1-18 peptides. In this work we report experimental data which demonstrate that the 1-16 peptide (P1-16) possesses a marked effect on the AT activity by preventing the formation of the thrombin-AT complex. We found that the formation of thrombin-AT complex is markedly decreased in the presence of P1-16 used at equimolar concentration with thrombin as evaluated with SDS-PAGE. We also monitored the conformational changes of thrombin in the presence of different P1-16 concentrations, and calculated the K(d) of thrombin/P1-16 system by circular dichroism technique. The probable interaction sites of P1-16 with thrombin have been also evaluated by molecular graphics and computational analyses. These results have potential implications in the treatment of sterility and thrombotic diseases.
Amino Acid Sequence ; Animals ; Antithrombin III/metabolism ; Blood Coagulation/drug effects ; Circular Dichroism ; Humans ; Models, Molecular ; Molecular Sequence Data ; Peptide Fragments/*chemistry/pharmacology ; Protein Binding/drug effects ; Protein Structure, Secondary ; Protein Structure, Tertiary ; Rats ; Seminal Vesicle Secretory Proteins/*chemistry/genetics/metabolism ; Thrombin/*chemistry/genetics/metabolism

The early detection of recurrent differentiated thyroid carcinoma (DTC) cells in the post surgery DTC patients relies on the sensitivity of measuring both the level of thyroglobulin (Tg) and 131-Iodine distribution by Whole Body Scan (WBS). Undetectable level of Tg associated with negative WBS or elevated levels of Tg associated with positive WBS ("concordant") is ordinarily indicative of either absence or presence of disease. At times, elevated level of Tg with negative WBS or low levels of Tg with positive WBS ("discordant") could also occur. In the present study, we retrospectively reviewed series of 573 patients with DTC followed in the Diagnostic Imaging and Radiotherapy of the University "Federico II" of Naples between 1993 and 1997. We focused on 9 out of 573 patients (1.56%) who had a discordant pattern with low level of Tg/positive WBS in the post-surgical follow-up. Four patients were metastatic at presentation while 5 patients with metastasis during follow-up still remained in persistently low levels of Tg (<5 ng/mL). This result does point to some flaw in the evaluation of "discordant" cases. Reviewing data previously described series by resetting cut-off values of Tg <1 ng/ml as undetectable changed the apparent "discordant" subgroup of patients into "concordant". Recent introduction of recombinant human TSH (rhTSH) to enhance the expression level of Tg brought significant increase in the sensitivity of diagnostic evaluation of thyroid cancer patients. The role of burdensome WBS in the follow up evaluation of DTC patients is significantly reduced over time especially in low-risk patients while the relevance of Tg assay is steadily increased. Sensitive Tg assays, significantly improved our ability to assess disease status in follow-up of DTC. Given the possibility of late disease relapses, the need for long-term follow-up, and reduced delay in treatment of persistent disease, there is still need for greater sensitive diagnostic tools for DTC.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Biological Markers/blood ; Biomedical Technology ; Carcinoma/*diagnosis/drug therapy/radionuclide imaging ; Female ; Follow-Up Studies ; Humans ; Iodine Radioisotopes/diagnostic use ; Male ; Middle Aged ; Recombinant Proteins/diagnostic use ; Research Support, Non-U.S. Gov't ; Thyroglobulin/*blood ; Thyroid Neoplasms/*diagnosis/drug therapy/radionuclide imaging ; Thyrotropin/*diagnostic use ; Whole-Body Counting