Biodistribution Studies of a New Antitumor Compound Based on Nanoporous Nanodiamond Composite Labeled with Rhenium-188

This study evaluated a new drug delivery system for local radiotherapy on the base of nanoporous nanodiamond composites (NDC) labeled with β-emitting radionuclide rhenium-188. The biodistribution of labeled compound was assessed after intratumoral (i.t.) and intramuscular (i.m.) injection. 24 mice-bearing solid Ehrlich carcinoma xenografts received i.t. injections of 0.370 ± 0.074 MBq 188Re-nanoporous diamond composites. Another 24 intact mice were injected with the same preparation intramuscularly. The samples of different organs and tissues were collected for gamma count. After i.t. and i.m. administration of 188Re-nanoporous NDC a considerable amount of radioactivity retained at the site of injection. In tumor tissue the total amount of activity decreased from 92.68 % to 9.63 % of injected dose (ID) throughout the study. The removal of injected activity from muscular tissue was faster as compared with tumor tissue, and declined from 81.06 % to 8.40 % ID for up to 72 h. Therefore, after i.m. injection the accumulation of radioactivity in healthy organs and tissues was slightly higher than after i.t. injection. In conclusion, it was demonstrated that 188Renanoporous diamond composites had the potential radiotherapeutic significance. Keywords: composite materials, nanodiamond, rhenium-188, cancer radiotherapy, local radiotherapy

Preliminary Biological Evaluation of Leucine Labeled with Gallium-68—A Potential Agent for Tumor Imaging

Amino acids are important nutrients for proliferating tumor cells, so their transport is generally increased in many malignant tumor cells. Radiolabeled amino acids are of great interest as they can be alternative or complement tracers to the already wellestablished radiopharmaceuticals such as 18F-FDG. The purpose of this study was to synthesize and characterize a novel 68Ga labeled leucine analog, 68Ga-leucine, as a potential imaging agent for tumors which may not be amenable to imaging by 18F-FDG PET. Biodistribution studies of 68Ga-leucine were performed in Wistar rats with transplanted cholangioma RS-1 xenografts after intravenous injection. 68Ga-leucine demonstrated high in vivo stability. Accumulation of 68Ga-leucine at xenograft tumors was about 2-4 higher as compared with 68GaCl3 and reached 0.79% ID/g. Among the soft tissue organs, only kidney had a relatively high uptake. The amount of radioactivity in other organs didn’t exceed 1% ID/g. The results suggest that 68Ga-leucine has the potential to be a new additional diagnostic tool for PET imaging of tumors. Keywords: gallium-68, leucine, radiolabeled amino acids, positron emission tomography, tumor imaging

Two-photon decays of vector mesons and dilepton decays of scalar mesons in dense matter

Two-photon decays of vector mesons and dilepton decays of scalar mesons which are forbidden in vacuum and can occur in dense baryonic matter due to the explicit violation of Lorentz symmetry are described within a quark model of the Nambu--Jona-Lasinio type. The temperature and chemical potential dependence of these processes is investigated. It is found that their contribution to the production of photons and leptons in heavy-ion collisions is enhanced near the conditions corresponding to the restoration of chiral symmetry. Moreover, in the case of the a_0 meson and especially the \rho-meson, a resonant behaviour (an additional amplification) is observed due to the degeneration of \rho and a_0 masses when a hot hadron matter is approaching a chirally symmetric phase.Comment: 20 figures, IOP styl

Preclinical Evaluation of Antitumor Efficacy of a New Radiopharmaceutical Based on Thermoresponsive Carrier and Samarium-153

This work is devoted to studying the in vivo antitumor efficacy of the new injection radiopharmaceutical based on thermoresponsive polymer and β−-emitting radionuclide samarium-153 (153Sm-KARP-CheM). The study of in vivo antitumor efficacy was performed using mice F1 and C57Bl/6 with transplanted subcutaneously sarcoma S37 and melanoma B16, respectively. The animals received single intratumoral bolus injections of 37 MBq (1 mCi), or 18.5 MBq (0.5 mCi) of 153Sm-KARP-CheM, or saline in a volume 0.1 ml. The efficacy of antitumortreatment was evaluated using tumor growth inhibition index (TGI, %) and increase of average life span (ILS, %). The most meaningful therapeutic efficacy after intratumoral injection of 153Sm-KARPCheM was observed in melanoma-bearing mice C57Bl/6. The highest values of TGI for melanoma B16 were 79.5% and 79.6% after treatment with 18.5 MBq or 37 MBq, respectively. An increase of average life span by 17.1% was found in group of melanoma-bearing mice treated with 37 MBq of 153Sm-KARP-CheM only. Tumor growth inhibition of sarcoma S37 was slightly lower as compared with melanoma B16: 62.5% and 59.0% in 37 MBq and 18.5 MBq groups, respectively. 153Sm-KARP-CheM didn’t increase average life span of treated animals. In conclusion, 153Sm-KARP-CheM seems to be effective radiopharmaceutical for local tumor radiotherapy. Keywords: thermoresponsive polymer, samarium-153, radionuclide therapy of cancer, sarcoma S37, melanoma B16, antitumor efficacy

Low-temperature far-infrared ellipsometry of convergent beam

Development of an ellipsometry to the case of a coherent far infrared irradiation, low temperatures and small samples is described, including a decision of the direct and inverse problems of the convergent beam ellipsometry for an arbitrary wavelength, measurement technique and a compensating orientation of cryostat windows. Experimental results are presented: for a gold film and UBe13 single crystal at room temperature (lambda=119 um), temperature dependencies of the complex dielectric function of SrTiO3 (lambda=119, 84 and 28 um) and of YBa2Cu3O7-delta ceramic (lambda=119 um).Comment: 14 pages, 6 figure

Measurement of Muon Capture on the Proton to 1% Precision and Determination of the Pseudoscalar Coupling g_P

The MuCap experiment at the Paul Scherrer Institute has measured the rate L_S of muon capture from the singlet state of the muonic hydrogen atom to a precision of 1%. A muon beam was stopped in a time projection chamber filled with 10-bar, ultra-pure hydrogen gas. Cylindrical wire chambers and a segmented scintillator barrel detected electrons from muon decay. L_S is determined from the difference between the mu- disappearance rate in hydrogen and the free muon decay rate. The result is based on the analysis of 1.2 10^10 mu- decays, from which we extract the capture rate L_S = (714.9 +- 5.4(stat) +- 5.1(syst)) s^-1 and derive the proton's pseudoscalar coupling g_P(q^2_0 = -0.88 m^2_mu) = 8.06 +- 0.55.Comment: Updated figure 1 and small changes in wording to match published versio

Identification of particles with Lorentz factor up to 10410^{4} with Transition Radiation Detectors based on micro-strip silicon detectors

This work is dedicated to the study of a technique for hadron identification in the TeV momentum range, based on the simultaneous measurement of the energies and of the emission angles of the Transition Radiation (TR) X-rays with respect to the radiating particles. A detector setup has been built and tested with particles in a wide range of Lorentz factors (from about $10^3$ to about $4 \times 10^4$ crossing different types of radiators. The measured double-differential (in energy and angle) spectra of the TR photons are in a reasonably good agreement with TR simulation predictions.Comment: 31 pages, 12 figures, paper published on Nuclear Instruments & Methods