Disconnecting the yin and yang relation of epidermal growth factor receptor (EGFR)-mediated delivery: a fully synthetic, EGFR-targeted gene transfer system avoiding receptor activation.

The epidermal growth factor receptor (EGFR) is upregulated within a high percentage of solid tumors and hence is an attractive target for tumor-targeted therapies including gene therapy. The natural EGFR ligand epidermal growth factor (EGF) has been used for this purpose, despite the risk of mitogenic effects due to EGFR activation. We have developed a fully synthetic, EGFR-targeted gene delivery system based on PEGylated linear polyethylenimine (LPEI), allowing evaluation of different EGFR-binding peptides in terms of transfection efficiency and EGFR activation. Peptide sequences directly derived from the human EGF molecule enhanced transfection efficiency with concomitant EGFR activation. Only the EGFR-binding peptide GE11, which has been identified by phage display technique, showed specific enhancement of transfection on EGFR-overexpressing tumor cells including glioblastoma and hepatoma, but without EGFR activation. EGFR targeting led to high levels of cell association of fluorescently labeled polyplexes after only 30 min of incubation. EGF pretreatment of cells induced enhanced cellular internalization of all polyplex types tested, pointing at generally enhanced macropinocytosis. EGF polyplexes diminished cell surface expression of EGFR for up to 4 hr, whereas GE11 polyplexes did not. In a clinically relevant orthotopic prostate cancer model, intratumorally injected GE11 polyplexes were superior in inducing transgene expression when compared with untargeted polyplexes.

Biosynthesis of Erythrina alkaloids in Erythrina crista-galli.

A precursor application system was developed to allow the study of Erythrina alkaloid formation in Erythrina crista-galli. Fruit wall tissue of this species was recognized as the major site of alkaloid biosynthesis. The application of radioactively and 13C-labelled potential precursors showed that the hitherto assumed precursor (S)-norprotosinomenine was not incorporated into the Erythrina alkaloids. In contrast, (S)-coclaurine as well as (S)-norreticuline were metabolized to erythraline and erythrinine, respectively, suggesting that a coclaurine-norreticuline pathway is operative in Erythrina alkaloid formation. Feeding of [1-13C]-labelled (S)-norreticuline with subsequent NMR spectroscopy demonstrated that the resulting erythraline was exclusively labelled at position C-10. Therefore, the participation of a symmetrical intermediate of the diphenoquinone type in Erythrina alkaloid biosynthesis can be excluded.

[Double contrast small bowel examination--a methodologic comparison using transnasal and peroral probes]. / Dünndarmdoppelkontrastuntersuchung--Ein methodischer Vergleich zwischen der transnasalen und der peroralen Sondierung.

A new flexible probe to be introduced through the nose was used for the intubation of the jejunum for double-contrast small bowel enema. The new probe has a diameter of only 2.8 mm and was better tolerated than the normally applied Camus probe. Nevertheless, the failure rate (intubation of jejunum not successful) with the new probe as compared to the Camus probe was higher (17% versus 1%). We, therefore, conclude that the new probe should mainly be used by experienced examiners.

[Value of small bowel double contrast enema in clinical interventions]. / Die Wertigkeit des Dünndarmdoppelkontrasteinlaufes im klinischen Einsatz.

The double contrast enema is the most effective morphological screening method for the evaluation of the whole small bowel. Its sensitivity is 85%, its specifity 96.7%. In specific clinical problems the number of pathological roentgen findings rises: from 34.4% when all indications are taken into consideration to 58% in indications specific to the small intestine such as Morbus Crohn or the malabsorption syndrome. Search for tumours and the double contrast of the small bowel in unclear gastro-intestinal bleeding are unproductive. The weak point of this screening method is the lower part of the small intestine. Therefore, the selective peroral or retrograde analysis of the terminal ileum supplement the contrast method. A precondition for good results is an adequate technical standard. Besides the clinical results some technical results are therefore discussed such as contrast medium quantities, examination and X-ray time, radiation exposure and influences on the image quality.