No significant association between stable iodine intake and thyroid dysfunction in children after the Fukushima Nuclear Disaster: an observational study

PURPOSE

Stable iodine prophylaxis helps prevent childhood thyroid cancer in nuclear emergencies; however, there is limited information on its effect on thyroid function. This study aimed to examine thyroid function and autoimmunity among children and adolescents that took stable iodine after the Fukushima Nuclear Disaster.

METHODS

For this observational study, data were obtained from children and adolescents that underwent thyroid cancer screening at Hirata Central Hospital from April 2012 to March 2018. Participant characteristics, including possible hypothyroidism and hyperthyroidism, were compared between the prophylaxis and no-prophylaxis groups. Multivariable logistic regression models were used to assess for possible hypothyroidism, autoantibodies positive, and hyperthyroidism.

RESULTS

A total of 1,225 participants with stable iodine prophylaxis and 3,946 without prophylaxis were enrolled. Of those participants, blood samples were available for 144 and 1,201 participants in the prophylaxis and no-prophylaxis groups, respectively. There were 17 (11.8%) and 146 cases (12.2%) of possible hypothyroidism or autoantibodies positive cases in the prophylaxis and no-prophylaxis groups, respectively, and there were no cases and 3 cases (0.2%) of possible hyperthyroidism in those two groups, respectively. Multivariable analysis for possible hypothyroidism revealed no association between stable iodine intake and possible hypothyroidism or autoantibodies positive [odds ratio 0.716 (95% confidence interval 0.399-1.284)] (p = 0.262). We did not perform multivariable analysis for hyperthyroidism due to the limited number of cases.

CONCLUSION

Significant adverse effects of stable iodine intake on thyroid function were not observed among children and adolescents 7 years after the Fukushima Nuclear Disaster.

In vitro invasion capacity of Salmonella Typhimurium DT9 isolates sourced from humans and layer hen environments

In Australia, Salmonella Typhimurium definitive type 9 is frequently isolated during foodborne outbreaks of salmonellosis. Multiple-locus variable number tandem repeat analysis (MLVA) trace back investigations frequently identify isolate distribution patterns that may be epidemiologically linked to disease outbreaks. In this study, the in vitro virulence potential of S. Typhimurium DT9 isolates possessing different MLVA patterns (03 15 07 11 550, 03 24 11 10 523, 03 15 08 11 550 and 03 14 08 11 550) isolated from either humans or layer hens was assessed using a human colon carcinoma cell line. Four strains per MLVA from each host for a total of 32 isolates were included in these experiments. Bacteria were grown to stationary phase and added to cells at a multiplicity of infection of 100. Across all isolates, mean percent recovery ranged from 7.1 ± 1.1 to 33.3 ± 7.1%. The layer hen isolate, KC900 (MLVA profile 03 15 08 11 550), exhibited the greatest invasion with a mean percent recovery of 33.3 ± 7.1%. Overall, layer hen isolates of S. Typhimurium DT9 had significantly higher invasion into Caco2 cells than human isolates (p = .0021). RAPD and enterobacterial repetitive intergenic consensus genomic fingerprinting was also performed. Irrespective of source, the SalmonellaDT9 isolates included in this study exhibited similar fingerprint patterns.

Structure of a single model to describe plutonium and americium decorporation by DTPA treatments

The aim of this study is to propose a single modeling structure to describe both plutonium and americium decorporation by DTPA, which is based on hypotheses mostly validated by experimental data. Decorporation efficacy of extracellular retention depends on the concentration ratio of DTPA vs. actinides and varies in each compartment according to the amount of biological ligands and their affinity for actinides. By contrast, because the relatively long residence time of DTPA after its cell internalization and the stability of actinide-DTPA complexes, intracellular decorporation efficacy is mainly controlled by a DTPA/actinide ratio, which is specific to each retention compartment. Although the affinity of DTPA is much lower for americium than for plutonium, a larger decorporation of americium can be obtained, which is explained by different biological ligands and/or their affinity for the actinide. Altogether, these results show that the relative contribution of intra vs. extracellular decorporation varies depending on the actinide, the chemical form of radionuclides, the galenic formulation of DTPA, and the treatment schedule.

Simplified structure of a new model to describe urinary excretion of plutonium after systemic, liver or pulmonary contamination of rats associated with Ca-DTPA treatments

This study validates, by targeted experiments, several modeling hypotheses for interpretation of urinary excretion of plutonium after Ca-DTPA treatments. Different formulations and doses of Ca-DTPA were administered to rats before or after systemic, liver or lung contamination with various chemical forms of plutonium. The biokinetics of plutonium was also characterized after i.v. injection of Pu-DTPA. Once formed, Pu-DTPA complexes are stable in most biological environments. Pu-DTPA present in circulating fluids is rapidly excreted in the urine, but 2-3% is retained, mainly in soft tissues, and is then excreted slowly in the urine after transfer to blood. Potentially, all intracellular monoatomic forms of plutonium could be decorporated after DTPA internalization involving slow urinary excretion of Pu-DTPA with half-lives varying from 2.5 to 6 days as a function of tissue retention. The ratio of fast to slow urinary excretion of Pu-DTPA depends on both plutonium contamination and Ca-DTPA treatment. Fast urinary excretion of Pu-DTPA corresponds to extracellular decorporation that occurs beyond a threshold of the free DTPA concentration in circulating fluids. Slow excretion corresponds mostly to intracellular decorporation and depends on the amount of intracellular DTPA. From these results, the structure of a simplified model is proposed for interpretation of data obtained with Ca-DTPA treatments after systemic, wound or pulmonary contamination by plutonium.

Targeting of diethylene triamine pentaacetic acid encapsulated in liposomes to rat liver: an effective strategy to prevent bone deposition and increase urine elimination of plutonium in rats

PURPOSE

To modify the distribution of the chelating agent diethylene triamine pentaacetic acid (DTPA) by using a formulation approach with liposomes in order to match the in vivo distribution of plutonium (Pu) and, as a consequence, to improve actinide decorporation.

MATERIALS AND METHODS

DTPA was encapsulated in conventional and stealth liposomes. Their pharmacokinetics and ability to remove Pu were evaluated in rats 2 and 16 days after a single intravenous treatment given 2 h after contamination with colloidal Pu (239Pu phytate) or with soluble Pu (238Pu citrate).

RESULTS

Both formulations induced major pharmacokinetic modifications in rats, allowing an accumulation of [14C]-DTPA mainly in the liver and secondarily (for stealth liposomes) in bone and spleen. These modifications were associated with major increases in urine elimination and with a decrease in skeletal Pu deposition, depending of the nature of the Pu contaminant. After contamination by Pu phytate, conventional liposomes of DTPA (6 micromol kg(-1)) were as efficient as free DTPA (30 micromol kg(-1)) in maintaining the Pu content in the femur below 4.3% of the injected dose after 16 days, a 3.6-fold reduction compared with free DTPA (4 micromol kg(-1)) treatment or without treatment.

CONCLUSIONS

A formulation approach with liposomes appears to be a powerful tool to improve the efficiency of Pu chelating agents in vivo.

Enhanced decorporation of plutonium by DTPA encapsulated in small PEG-coated liposomes

The aim of the study was to demonstrate that decorporation of 238Pu is achieved more efficiently by an optimized liposomal formulation of diethylene triamine pentaacetic acid (DTPA) than by the usual free DTPA treatment. The optimized formulation consisted of polyethylene glycol-coated stealth liposomes with a mean diameter of 100 nm (SL-100 nm). Rats were intravenously injected with various Pu-phytate salt solutions in order to test different contamination conditions (activity and salt concentration) impacting liver kinetics and skeletal uptake of Pu. All treatments were given intravenously 1 h after contamination. Efficiency was evaluated 24 h, 7, 16 or 30 days later through their ability to promote Pu elimination and to reduce Pu burden in the skeleton and liver, the main organs of Pu deposition and radiotoxicological effects. Whatever the conditions of contaminations, a single injection of SL-100 nm (3.2 micromol kg(-1) DTPA) boosted urinary elimination of Pu to above 90% of the injected dose. In addition, liposomes strongly and significantly reduced the Pu burden of the liver and skeleton even 30 days after a single treatment: a dose of 0.3 micromol kg(-1) induced the same skeletal Pu reduction as four injections of free DTPA (30 micromol kg(-1)). A log dose-effect relation was found with SL-100 nm DTPA and Pu excretion in urine or Pu burden in the studied organs (liver, femurs, spleen and kidneys). This efficacy was attributed to an optimized targeting of DTPA to the main Pu retention organs and especially the liver.

Favorable visual outcome in cryptococcal meningitis

PURPOSE

To describe an unusual, favorable visual outcome in a patient with lupus erythematosus and cryptococcal meningitis and to present bilateral superior oblique muscle paresis.

METHODS

Case report. A 15-year-old girl with lupus erythematosus and cryptococcal meningitis had bilateral superior oblique paresis, bilateral optic nerve head swelling, and increased intracranial pressure. She developed a visual acuity of no light perception in the right eye.

RESULTS

Treatment with oral fluconazole, acetazolamide, and dexamethasone, as well as repeated lumbar punctures to reduce intracranial pressure, was followed by recovery to a visual acuity of 20/20 in both eyes and normal ocular motility.

CONCLUSION

With appropriate treatment, visual loss associated with cryptococcal meningitis may have a favorable outcome.