Optical imaging to trace near infrared fluorescent zinc oxide nanoparticles following oral exposure.

BACKGROUND: Understanding how nanomaterials are distributed in the body after exposure is important for assessing whether they are safe. In this study, we investigated the behavior and accumulation of nanoscaled and submicron-scaled zinc oxide (ZnO) particles in the body using optical imaging following oral exposure. METHODS: To trace these nanoparticles in the body, ZnO nanoparticles were conjugated with a monoreactive hydroxysuccinimide ester of Cy5.5 (Cy5.5-NHS), and the conjugation-stabilizing effect of Cy5.5 on the nanoparticles was evaluated in simulated gastric fluid (pH 1.2) for 7 hours. To compare the distribution of Cy5.5-NHS and Cy5.5-conjugated ZnO nanoparticles, Cy5.5-NHS 0.5 mg/kg and Cy5.5-conjugated ZnO nanoparticles 250 mg/kg were administered orally to healthy rats. We collected blood from the rats at predesignated time points for 7 hours after administration, and optical imaging studies were performed at 1, 2, 3, 5, and 7 hours after dosing. To investigate the extent of nanoparticle accumulation in the organs and tissues, the mice were sacrificed at 23 hours after administration, and the organs were removed and imaged. RESULTS: Cy5.5-conjugated ZnO nanoparticles were stable in simulated gastric fluid for 7 hours. The signal intensity of Cy5.5-NHS in blood was highest 3 hours after oral administration, and Cy5.5-conjugated ZnO nanoparticles showed the highest signal intensity in blood 5-7 hours after administration. In vivo optical images indicated that Cy5.5-NHS showed optical signals in the lung, liver, and gastrointestinal tract after oral administration, whereas Cy5.5-conjugated ZnO nanoparticles were seen only in the gastrointestinal tract. Seven hours following administration, biodistribution studies demonstrated that Cy5.5-NHS accumulated in the lung and liver, and Cy5.5-conjugated ZnO nanoparticles resulted in a strong signal in the kidney and liver. Different-sized ZnO nanoparticles showed dissimilar patterns of biodistribution in ex vivo optical images. CONCLUSION: ZnO nanoparticles are absorbed into the tissues following oral exposure and their behavior can be monitored and evaluated using optical imaging.

Comparison of the Influence on the Liver Function Between Thyroid Hormone Withdrawal and rh-TSH Before High-Dose Radioiodine Therapy in Patients with Well-Differentiated Thyroid Cancer.

PURPOSE: An elevated thyroid stimulating hormone level (TSH) is essential to stimulate the uptake of radioiodine into thyroid remnants and metastases of thyroid cancer when a patient undergoes high-dose radioiodine therapy. Nowadays, recombinant human thyroid stimulating hormone (rh-TSH) is increasingly used instead of the classic method of thyroid hormone withdrawal (THW). However, beyond the therapeutic effects, clinical differences between the two methods have not yet been clearly demonstrated. The aim of this work was to investigate the effects of the two methods, especially on liver function. METHODS: We identified 143 evaluable patients who were further divided into two groups: THW and rh-TSH. We first reviewed the aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels, which were measured during the admission period for total thyroidectomy. We called these liver enzyme levels "base AST" and "base ALT." We also assessed other chemistry profiles, including AST, ALT, total cholesterol, LDL cholesterol, alkaline phosphatase (ALP), total bilirubin (TB), and triglyceride (TG), which were measured on admission day for high-dose radioiodine therapy. We called these liver enzyme levels "follow-up AST" and "follow-up ALT." We compared the changes in base and follow-up liver enzyme levels and the other chemistry profiles between the two groups. RESULTS: The base AST and base ALT levels of the two groups were within normal range, and there was no significant difference between the two groups. In contrast to these base liver enzyme levels, follow-up liver enzyme levels between the two groups showed significant differences. Patients in the THW group had higher follow-up AST and ALT levels than did the rh-TSH group. Patients in the THW group also had higher levels of total cholesterol and LDL cholesterol than did the patients in the rh-TSH group. However there were no statistically significant differences in ALP, total bilirubin, and triglyceride levels between the two groups. CONCLUSIONS: In this retrospective analysis of liver function, the use of rh-TSH for high-dose radioiodine therapy had less of an effect on liver function and cholesterol levels than dose thyroid hormone withdrawal. This suggests that rh-TSH can be used effectively and safely especially for patients with metabolic syndrome.