Stability testing of iomeprol and iopamidol formulations subjected to X-ray radiation.

INTRODUCTION: Exposure of iodinated contrast media (ICM) to X-rays is not uncommon, as contrast media are often stored in close proximity to radiological equipment. However, the interaction between X-rays and ICM is not widely investigated in literature. The present study aims to investigate the chemical stability of iomeprol and iopamidol, two commercial iodinated ICM commonly used in diagnostic imaging, under X-rays exposure. METHODS: Different formulations of iopamidol and iomeprol (iodine concentration 9 to 400 mgI/mL, volume 50-500 mL) were exposed to three different conditions of X-ray irradiation: i) 1 month storage in CT room (≈5-15 mGy); (ii) low-dose protocol (≈10 mGy); (ii) stressed protocol (≈100 mGy). Unexposed and exposed solutions were characterized by high-performance liquid chromatography in terms of concentration of active pharmaceutical ingredient (API), iodine species and by products. In addition, appearance and colour of the solutions were inspected and pH measured. RESULTS: API concentrations, appearance, colour and pH of the exposed formulations remained unaffected by X-rays. Measured concentrations of iodine species and by products were observed well within the acceptability criteria, i.e. values turned out to be lower than specifications limits established by the manufacturer, considering both release and shelf-life values. CONCLUSIONS: Up to 100 mGy X-ray exposure did not induce any alteration of iomeprol and iopamidol formulation, nor a detectable increase in the concentration of iodine species or by-products. IMPLICATIONS FOR PRACTICE: Our study strengthens the hypothesis that ICM are stable under X-rays exposure up to 100 mGy.

Proteomic analysis in the lichen Physcia adscendens exposed to cadmium stress.

This work was undertaken to explore the potential of proteomics to dissect parallel and consecutive events of cadmium stress response in the lichen Physcia adscendens (Fr.) H. Olivier. Thalli were exposed to 0 (control) and 36 microM Cd for 6, 18, 24 and 48 h. Two-dimensional electrophoresis and mass spectrometry analyses showed an 80-85% spot identity between 6 and 18 h vs. 24 and 48 h of Cd exposure. Putative heat-shock proteins and glutathione S-transferase generally increased their expression all over the Cd treatments. By contrast, ABC transporters were underexpressed after 6-18 h, but in some cases induced after 24-48 h of Cd exposure. The cytochrome P450 appeared to have a variable expression pattern over time. Overall these data suggest that a considerable importance in the response of P. adscendens thalli to Cd stress can be assumed by differential expression of various protein families.

First and second line mechanisms of cadmium detoxification in the lichen photobiont Trebouxia impressa (Chlorophyta).

"First line" defence mechanisms, such as phytochelatin biosynthesis, and "second line" mechanisms, such as stress protein induction, were investigated in cadmium-exposed cells of Trebouxia impressa Ahmadjian, a green microalgal species that is a common photobiont of the lichen Physcia adscendens (Fr.) H. Olivier. When T. impressa cells were exposed to 0, 9 and 18 microM Cd for 6, 18 and 48 h, glutathione and phytochelatins efficiently protected the cells against Cd damage. By contrast, the highest Cd concentration (36 microM) at the longest exposure-time (48 h) caused marked drops in glutathione and phytochelatin content, several types of ultrastructural damage, and decreases in cell density and total chlorophyll concentration. In this case, induction of stress proteins was observed, but only long after the induction of phytochelatins. Thus, stress proteins could represent a "second line" mechanism to counteract Cd stress, activated when there is a decline in the "first line" mechanism of Cd detoxification given by phytochelatins.