Adhesion of water-borne particulates on freshwater biota.

The retention of suspended particles transported by river flow on surfaces of freshwater plants is a potentially important process in the contamination of aquatic biota. Field experiments have been performed to test the role of benthic algae (periphyton) in trapping inorganic suspended solids transported by the river water and to discriminate between the caesium content of periphyton caused by the adherence of inorganic solids and by the active uptake inside the organisms. The contribution of caesium of suspended solids adhering to biotic surfaces was estimated by determining the scandium content (scandium method). The scandium method was used because this element is geologically ubiquitous in soils and it is not taken up actively by plants and other organisms. The mass of suspended particles retained on the surfaces of microorganisms growing on submerged substrates were determined by comparing the scandium content of suspended material with that in algal communities. Neutron activation analysis was used as the analytical method for determination for both scandium, and caesium. The results indicate that the suspended particle fraction can contribute up to 80% of the caesium contamination of periphyton samples. Active caesium uptake and accumulation by aquatic biota represents the remaining 20% of the total caesium contamination.

Invivo control of tumor-growth by lonidamine and radiations - influence of the timing and sequence of drug administration and irradiation treatment.

It has been well established that Lonidamine (LND), [1,(2,4 dichlorobenzyl)-1H-indazol-3-carboxylic acid], affects tumor growth and enhances the effect of X-ray both in vitro and in vivo. Nevertheless, difficulties arise if the available experimental data should be utilized to design clinical trials since schedules, routes of administration as well as dosages greatly differ from those currently employed in the clinic. With the aim to overcome these difficulties, experiments with modalities similar to those employed in the current clinical practice have been undertaken to evaluate: (i) the influence of the LND dosage on the antitumor effect; (ii) the time lenght of its administration for the optimal effect; (iii) the best schedule of treatment when LND is associated with radiations. The results may be summarized as follows: (i) antitumor effectiveness of LND, in terms of growth delay, increases with LND dosage. Moreover, the drug administered from the day of transplant significantly decreases the tumor takes. (ii) to exert the antineoplastic effect LND must be administered continuosly because if the treatment is interrupted the tumor regrows like an untreated one. (iii) the maximal response of the association X-ray-LND is elicited when the drug is given after irradiation treatment.