Long-term biological effects after acute 131I-administration of two rat models (with and without thyroid).

PURPOSE: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSIONS: Long-term biological effect of 131I-administration shows the appearance of various histological disorders confirmed by disturbances in hepatic and renal functions.

The use of muscle biomarkers for assessing physiological effects of heavy metal pollution in the greater white-toothed shrew (Crocidura russula).

The greater white-toothed shrew Crocidura russula has been used as a sentinel species for estimating environmental risks to human populations. Previous studies in mining areas have focused on the liver of shrews as the primary target of physiological and metabolic changes due to heavy metal pollution. However, populations persist even when detoxification by the liver seems to be compromised and damage is observed. These pollutant-adapted individuals inhabiting contaminated sites may exhibit altered biochemical parameters that confer increased tolerance in various tissues other than the liver. The skeletal muscle tissue of C. russula might be an alternative tissue that allows the survival of organisms inhabiting historically polluted sites due to the detoxification of redistributed metals. Organisms from two heavy metal mine populations and one population derived from an unpolluted site were used to determine the detoxification activities, antioxidant capacity, and oxidative damage, as well as cellular energy allocation parameters and acetylcholinesterase activity (a biomarker of neurotoxicity). Muscle biomarkers differ between shrews from polluted sites and shrews from the unpolluted location, with the mine animals showing: (1) a decreased energy consumption concomitant with increased energy reserves and total available energy; (2) reduced cholinergic activity, suggesting an impairment of neurotransmission at the neuromuscular junction; (3) an overall decrease in detoxification capacity and enzymatic antioxidant response and a higher level of lipid damage. Also, some of these markers differed between females and males. These changes may have resulted from a decreased detoxifying capacity of the liver and could potentially bring about significant ecological effects for this highly active species. Heavy metal pollution induced physiological changes in Crocidura russula showing that skeletal muscle may serve as a backup sink organ allowing rapid species adaptation and evolution.

Two directions that cannot be ignored in the study of endemic fluorosis and endemic arsenicosis in China: long-term exposure to low-dose fluoride and arsenic, and non-target organ damage / 中华地方病学杂志

With the comprehensive implementation of prevention and control measures for endemic fluorosis and endemic arsenicosis in China, and in accordance with the World Health Organization (WHO) recommended drinking water standards and the Chinese standards of allowable daily fluoride intake and limit values of arsenic content in drinking water, Chinese residents have entered the era of low-dose fluoride and arsenic exposure. However, there have been few studies focused on the long-term health effects of exposure to low-dose fluoride and arsenic both domestically and internationally. Further more, study on non-target organs of fluoride and arsenic has been neglected. The conclusions are also inconsistent, and there is an urgent need for systematic study to clarify them. Accordingly, this paper proposes to establish a cohort of people exposed to low-dose fluoride and arsenic, systematically carry out study on the long-term health effects and mechanisms of low-dose fluoride and arsenic exposure, and promote China's prevention and control experience to the "the Belt and Road" countries, in order to provide a scientific basis for the formulation of prevention and control strategies and measures for endemic fluorosis and endemic arsenicosis under the new situation in China.