Cytotoxic activity of a recombinant GnRH-PAP fusion toxin on human tumor cell lines

Pokeweed antiviral protein (PAP), a ribosome-inactivating protein isolated from the leaves of Phytolacca americana, reveals potent antiviral activity against viruses or cytotoxic action against cells once inside the cytoplasm. Therefore PAP is a good candidate to be used as an immunotoxin. We constructed a bacterial expression plasmid encoding PAP as a fusion protein with gonadotropin-releasing hormone (GnRH), a neuropeptide with receptor sites on several gynaecologic tumors. The resulting recombinant toxin was produced in Escherichia coli and accumulated in inclusion bodies. After purification under denaturing conditions, renaturated GnRH-PAP shows an IC(50) of 3 nM on in vitro translation assays and selectively inhibits the growth of the GnRH receptor positive Ishikawa cell line (ID(50) of 15 nM); on the other hand, neither GnRH nor PAP alone had any effect.

[Color-coded duplex sonography (angiodynography) in comparison with phlebography]

To verify the suspected diagnosis of deep thrombosis in the pelvic and/or the leg veins or to clarify the causes of pulmonary embolism, 84 patients were examined prospectively by color-coded duplex-sonography. The findings in the 103 legs examined were subsequently compared to those of an ascending phlebography. The deep veins from the region of the vena iliaca communis down to the lower leg were visualized, and blood flow, lumen and compressibility were checked. This procedure enabled the identification of totally occluding thrombi as well as partial thrombi with the circumfluent blood. The sensitivity of thrombus identification was 92.9%, the specificity was about 97% in the different segments. The results show that color-coded duplex sonography is a sensitive diagnostic instrument for follow-up in conservative therapy. Also, in postthrombotic changes, fresh clots can be identified for the most part. Color-coded duplex sonography can replace phlebography in most cases, if special attention is paid to regions which are difficult to visualize, such as the pelvic veins, the Hunter's channel and the veins of the lower leg.