Human urinary excretion of NC100692, an RGD-peptide for imaging angiogenesis.

The (99m)Tc complex of NC100692 is being evaluated as a diagnostic agent for the detection of angiogenesis. In the present study, human urine samples from a clinical Phase I study were analysed using reversed-phase liquid chromatography coupled with an ion-trap mass spectrometer (LC-MS) in order to estimate the amount of intact NC100692 and any metabolites excreted in urine following intravenous injection of 150microg (99m)Tc-NC100692. Only intact NC100692 was observed in these urine samples, no metabolites were detected, in contrast to data earlier reported for rat urine where two metabolites and no NC100692 were observed. Within 4-8h after injection, 30+/-6% of the injected NC100692 was excreted in the urine, with the majority (23+/-5%) recovered within the first hour post-injection. There was good agreement between the calculated urinary recoveries of NC100692 and total radioactivity in urine samples voided approximately 1h post-injection. NC100692 constituting 98+/-24% of the total urinary (99m)Tc recovery indicating that the (99m)Tc excreted during this period was most likely excreted as (99m)Tc-NC100692. The ratio of NC100692 to (99m)Tc decreased in the urine samples as a function of time following injection for all subjects; this change is most likely due to reduced accuracy in the results at low levels of NC100692.

Metabolism in rats of NC100692, an RGD-peptide for imaging of angiogenesis.

The 99mTc complex of NC100692 is being evaluated as a diagnostic agent for imaging of angiogenesis. We here report in vivo studies performed with NC100692 and 14C-labelled NC100692 using liquid chromatography coupled to either an ion-trap mass spectrometer or a radiochemical detector. Following injection of 14C-labelled NC100692, only the parent compound and no metabolites was observed in rat blood, whereas no parent compound and only 1 metabolite was observed in urine. Analysis of rat urine samples with liquid chromatography with mass spectrometric detection following administration of NC100692 verified the absence of the parent compound and showed the presence of 2 metabolites. The structures of the 2 metabolites were identified based on mass spectra and accurate mass determinations. The major metabolite was identified as the molecule obtained following hydrolytic cleavage at the end of the C-terminal amino acid of NC100692. The minor metabolite was identified as that obtained following removal of phenylalanine within the cyclic structure of the major metabolite.

Nonaqueous electrochromatography on continuous bed columns of sol-gel bonded large-pore C18 material: separation of retinyl esters.

A nonaqueous electrochromatographic reversed-phase separation method for retinyl esters using continuous bed columns has been developed. The packing material 7 microm Nucleosil 4,000 angstroms C18 was sol-gel bonded in 180 microm I.D. capillaries. The mobile phase used was 2.5 mM lithium acetate in N,N-dimethylformamide-acetonitrile-methanol (2+7+1, v/v). At 350 V/cm and 30 degrees C, this mobile phase composition gave rise to an electroosmotic flow of 1 mm/s. No Joule heating nor bubble formation were observed even at 625 V/cm (17 microA). With a 36 cm L(eff) column complete separation of the commercially available and synthesized standards (all-trans-retinyl acetate, palmitate, heptadecanoate, stearate, oleoate, and linoleoate) was obtained within 10 min. The within-day and between-day variations of retention times of all-trans-retinyl palmitate were <0.3% relative standard deviation (RSD) (n=3) and <2% RSD (n=6), respectively. The within-day and between-day variations of peak areas were both <2% (both n=3). The columns were used for more than 1 month without degradation. Liver extracts from arctic seal were analyzed.

Nonaqueous electrochromatography on C30 columns: separation of retinyl esters.

A nonaqueous packed capillary electrochromatographic reversed-phase method for separation of retinyl esters has been developed. The retinyl esters all-trans-retinyl acetate, palmitate, heptadecanoate, stearate, oleoate, and linoleoate were separated on a 180 microm ID column packed with 5 microm C30 particles with a mobile phase consisting of 2.5 mM lithium acetate in N,N-dimethylformamide-methanol (99:1, v/v). With this mobile phase, the electroosmotic flow was 0.8 mm/s at 650 V/cm and 40 degrees C, and the separation was completed in less than 30 min on 30 cm columns. To obtain electrostable frits of the hydrophobic C30 material both the preparation of the frits and the conditioning of the column prior to electroconditioning were of importance. Selectivity changes were introduced by replacing up to 70% v/v of the N,N-dimethylformamide by acetonitrile. The increase in the amount of acetonitrile was, however, accompanied by a significant increase in analysis time. Liver extracts obtained from arctic seal were analyzed.

Upwelling: oceanic structure at the edge of the arctic ice pack in winter.

Observations taken on an expedition into the Arctic Ocean north of Spitsbergen indicated the existence of a region of wind-driven upwelling along the edge of the ice pack. Models underestimate the 12-kilometer width of the upwelling region.