Comparison of two purified toxic fractions from Mesobuthus eupeus scorpion venom

Iranian scorpions belong mainly to the Buthidae and Scorpionidae families, distributed into 16 genera and 25 species. In Iran, similar to other parts of the world, there are a few known species of scorpions responsible for severe envenoming; amongst which Mesobuthus eupeus is the most common. Its venom contains several toxin fractions that may affect the ion channel. In the present study purification, labeling and biological evaluation of M. eupeus venom are described. For separation, soluble venom was loaded on a chromatography column packed with Sephadex G-50 gel. Subsequently, the fractions were collected according to UV absorption at a wavelength of 280 nm. Toxic fraction (F3) was loaded on an anionic ion exchanger resin and then on a cationic resin. Finally, toxic subfractions F3.1.6 and F3.1.9 were labeled with 99mTc and injected into normal mice to distinguish excretion pathway. The venom toxic fraction was successfully obtained in its purified form. Radiolabeling of toxic fractions was performed at high specific activity with radiochemical purity of more than 97 and 95 percent respectively for F3.1.6 and F3.1.9. Biodistribution studies in normal mice with two toxic fractions usually show rapid clearance of the compounds from blood and tissue except for kidneys. Since tissue distribution studies are very important for clinical purpose, the present findings suggest that 99mTc labeling of venom is a useful tool for in vivo studies and comprises an excellent approach to monitoring the process of biodistribution and kinetics of toxins.(AU)

Dosimetric studies of micropencil X-ray beam interacting with labelled tissues by Au and Gd agents using Geant4.

The aim of microbeam radiation therapy is to deliver a high dose to tumours while sparing adjacent healthy tissues. Recovery of normal tissues injured by the beam irradiation and ablation of tumour are dependent on the dose distribution generated by the incident microbeams. Using microbeams has the advantage that the areas outside the beams' trajectories (valley region) are poorly irradiated by the radiation scattered inside the tissues. Thus, the normal tissues not directly irradiated are adequately preserved, resulting in a rapid regeneration of blood vessels in the directly irradiated areas (peak region). The goal of this work was to study the effects of using gold (Au) and gadolinium (Gd) as dose enhancement factors on the radial dose distribution when target tissue is irradiated by a micropencil X-ray beam. The Monte Carlo Geant4 simulation program was used to evaluate dose distribution in the phantom in two phases. In phase 1, validity of this model based on Geant4 was evaluated by comparing the obtained results with those of the published reports. In phase 2 of this simulation, Au and Gd were introduced to the assumed cancerous cylindrical shell-shaped region both on the surface (i.e. in the 0-1 cm depth of phantom) and in the depth (i.e. in the 4-5 cm depth of phantom). Then the phantom was exposed to a micropencil beam mimicking the typical conditions used at the European synchrotron radiation facility in the simulated model. The simulated dose profiles indicate that introducing high Z elements considerably enhances the absorbed dose both in the beam path and in the surrounding region. However, this enhancement is more effective for Au in the beam path and for Gd in the surrounding region. This approach of introducing high Z elements leading to their accumulation in cancerous tissue could hopefully prepare new treatment planning of preclinical trials.