Affibody­mediated imaging of EGFR expression in prostate cancer using radiocobalt­labeled DOTA­ZEGFR:2377.

The epidermal growth factor receptor (EGFR) is often overexpressed during prostate cancer (PCa) progression towards androgen­independence after hormone therapy, but the overexpression is lower than in other types of cancers. Despite the low expression, EGFR has emerged as a promising therapeutic target for patients with castration­resistant PCa. Non­invasive methods for determination of EGFR expression in PCa can serve for patient stratification and therapy response monitoring. Radionuclide imaging probes based on affibody molecules (7 kDa) provide high contrast imaging of cancer­associated molecular targets. We hypothesized that the anti­EGFR affibody molecule DOTA­ZEGFR:2377 labeled with 55Co (positron­emitter, T1/2=17.5 h) would enable imaging of EGFR expression in PCa xenografts. The human PCa cell line DU­145 was used for in vitro and in vivo experiments and 57Co was used as a surrogate for 55Co in the present study. Binding of 57Co­DOTA­ZEGFR:2377 to EGFR­expressing xenografts was saturable with anti­EGFR monoclonal antibody cetuximab, which would motivate the use of this tracer for monitoring the receptor occupancy during treatment. A significant dose­dependent difference in radioactivity accumulation in tumors and normal organs was observed when the biodistribution was studied 3 h after the injection of 10 and 35 µg of 57Co­DOTA­ZEGFR:2377: At lower doses the tumor uptake was 2­fold higher although tumor­to­organ ratios were not altered. For clinically relevant organs for PCa, tumor­to­organ ratios increased with time, and at 24 h pi were 2.2±0.5 for colon, 7±2 for muscle, and 4.0±0.7 for bones. Small animal SPECT/CT images confirmed the capacity of radiocobalt labeled DOTA­ZEGFR:2377 to visualize EGFR expression in PCa. In conclusion, the present study demonstrated the feasibility of using the radiocobalt labeled anti­EGFR affibody conjugate ZEGFR:2377 as an imaging agent for in vivo visualization of low EGFR­expressing tumors, like PCa, and for monitoring of receptor occupancy during cetuximab therapy as well as the importance of optimal dosing in order to achieve higher sensitivity molecular imaging.

Detection and temporal variation of (60)Co in the digestive glands of the common octopus, Octopus vulgaris, in the East China Sea.

(60)Co were detected in common octopus specimens collected in the East China Sea in 1996-2005. The source of (60)Co has remained unclear yet. Stable isotope analyses showed that there was no difference in stable Co concentrations between octopus samples with (60)Co and without (60)Co. This result showed that the stable Co in the digestive gland of octopus potentially did not include a trace amount of (60)Co and the source of (60)Co existed independently. Furthermore, investigations of octopus in other area and other species indicated that the origin of the source of (60)Co occurred locally in the restricted area in the East China Sea and not in the coastal area of Japan. Concentrations of (60)Co have annually decreased with shorter half-life than the physical half-life. This decrease tendency suggests that the sources of (60)Co were identical and were temporary dumped into the East China Sea as a solid waste.

Production and characterization of alpha-amylase from Aspergillus niger JGI 24 isolated in Bangalore.

Five fungal isolates were screened for the production of alpha-amylase using both solid-state and submerged fermentations. The best amylase producer among them, Aspergillus niger JGI 24, was selected for enzyme production by solid-state fermentation (SSF) on wheat bran. Different carbon and nitrogen supplements were used to enhance enzyme production and maximum amount of enzyme was obtained when SSF was carried out with soluble starch and beef extract (1% each) as supplements. Further attempts to enhance enzyme production by UV induced mutagenesis were carried out. Survival rate decreased with increase in duration of UV exposure. Partial purification of the enzyme using ammonium sulphate fractionation resulted in 1.49 fold increase in the enzyme activity. The enzyme showed a molecular weight of 43 kDa by SDS-PAGE. Metal ions Ca2+ and Co2+ increased the enzyme activity. The enzyme was optimally active at 30 degrees C and pH 9.5.