Meriem Mezaguer-Lekouaghet

Radioiodine-131 (RAI or iodine-131) is one of the most frequently used radionuclides for diagnosis and therapy of thyroid diseases (90% of all therapies in nuclear medicine). In order to optimize the patient protection, it is important to evaluate the long-term biological effects of RAI therapy on non-target organs. An experimental animal model has been adopted, it consists on miming RAI therapy. An activity of RAI has been administrated in two models of Wistar rats: the first model with an intact thyroid gland (Thy + model), and the second one was thyroidectomized (Thy- model). For each model, 6 rats were orally contaminated with a solution 18.5 ± 1MBq of [¹³¹I]NaI and 6 others rats were used as controls. The 24 rats have been placed in individual cages for a period of 08 months then they were euthanized. The blood was collected by cardiac puncture and all organs were immediately removed. A fraction of thyroid, liver, kidneys and testicles was put in vials containing formaldehyde (10%) for histological investigation. Histological observations show some liver disorders more accentuated in the case of the Thy- model, the appearance of kidney tissue effects (hemosiderin deposits, fibrosis and glomerular necrosis) for both models and an absence of any anomaly for the testicles slides. The disturbance of blood parameters specific to each organ has been revealed. Long-term biological effect of ¹³¹I-administration shows the appearance of various histological disorders confirmed by disturbances in hepatic and renal functions.

Cystic echinococcosis (CE) is one of the most important zoonotic diseases with a worldwide distribution. It is caused by the larval stage of the dog tapeworm “Echinococcus granulosussensu lato” and constitutes a major economic and public health problem in several countries. Protoscoleces are one component of this larval stage that can interact with both definitive and intermediate hosts. The aim of the present study was to investigate the potential role of using a radio‐attenuated form of these protoscoleces for immunoprophylaxis against experimental murine echinococcosis. However, mice were immunized twice at 15‐day intervals with gamma (γ) irradiated protoscoleces at doses of 0.4, 0.8, 1.2 and 1.4 kGy then challenged with the intact parasites. Macroscopic and histological analyses with cytokine measurements were performed in order to estimate the number and diameter of cysts, microscopic changes and cytokine profile. An improvement in protection against the challenge dose was observed with increasing dose, giving percentages of 47.7, 49, 55.23 and 70.6%, for the 0.4, 0.8, 1.2 and 1.4 kGy‐groups respectively. These data suggest that immunization with radio‐attenuated protoscoleces may induce satisfactory protective immunity by reducing successfully the formation of cysts, caused by challenge infection.