Revealing smuggled nuclear material covered by a legitimate radioisotope shipment using CdTe-based gamma-ray spectrometry.

Illicit trade of nuclear materials (NM) represents a serious challenge to radiation monitoring upon scenarios, when legitimate radioisotope shipments are used to obscure the weak radiation of NM. Planar and hemispherical Cd(Zn)Te detectors with a portable mini-multichannel analyzer were proven to be suitable, in measuring times of 10min order, for revealing the presence of low-enriched or natural U-bearing reactor fuel pellets in amounts of kg order, placed beside transport containers of lead or depleted uranium, which contain high activity 60Co (10GBq range) or 192Ir (TBq range) radioisotope sources. Such a hand-held or portable device may help authorities combating illicit trafficking of nuclear materials.

Monitoring bremsstrahlung from 4 MeV electrons by nuclear excitation and Al2O3 thermoluminescence dosemeters.

Isomer excitation by gamma,gamma' reactions and aluminium oxide thermoluminescence dosemeters (TLDs) have been used to monitor bremsstrahlung from the 4 MeV electron beam of a linear accelerator type LPR4 produced on a 0.9 mm Pt converter foil. Natural indium and osmium as well as TLDs have been irradiated at different distances (2-11 cm) and angles (0 degrees-90 degrees). Dose rates measured by TLDs were 5-110 kGy x h(-1). Isomer excitation of 115In (half-life 4.5 h) was used for monitoring bremsstrahlung of energies above 1 MeV, while that of 189Os (half-life 5.8 h) extended the available range down to 200 keV. Isomer production yields measured by gamma spectrometry and found to be about 10(-19)-10(-18) Bq per nucleus were calibrated against dose rate. A graphical method based on a semiempirical formula was used to evaluate the bremsstrahlung flux as well as the dose rate from the activity of isomeric monitors with uncertainties below 20%. The method is simple, of linear response in a large scale, independent of temperature, and able to monitor extremely high gamma intensities.

Roles of growth factors in mediating mesenchymal influence on the cytodifferentiation of the Dunning prostatic adenocarcinoma.

Earlier studies have shown that seminal vesicle mesenchyme (SVM) has the ability to induce Dunning tumor (DT) to undergo morphogenetic changes and cytodifferentiation. The aim of the present study was to investigate the roles of growth factors and their receptors in tumor-mesenchymal interactions. Small pieces of DT were combined with SVM (0-day neonatal SD rat) and the tissue recombinants (SVM + DT) were grafted under the renal capsule of male athymic nude mice and allowed to grow for 4 weeks. Histopathological examination confirmed that SVM can induce DT to express apparently more normal morphological features, with the formation of large tubules lined by highly differentiated columnar epithelial cells and the reappearance of a fibromuscular stroma. Using immunohistochemistry, the results demonstrated that the tissue recombinants typically exhibited an overexpression of EGF, EGF-R, bFGF, TGF-beta(1) together with a concurrent downregulation of TGF-alpha, IGF-I, IGF-II, and VEGF receptors (flk-1, flt-1). The levels of these growth factors and their receptors in DT + SVM tissue recombinants were more similar to those of the normal prostate. These findings reaffirmed that SVM has the ability to reprogram DT toward a more normal direction on one hand, while implicating the importance of cytokines in mesenchyme-induced DT phenotypic changes under in vivo condition on the other hand. This study suggests that these factors and their receptors may be essential mediators in tumor-mesenchymal interactions.