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- Andersson, Charlotte, et al.
(författare)
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Biodistribution of I-131 in mice is influenced by circadian variations
- 2020
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Effects of radiation and biodistribution of radionuclides are often studied in animal models. Circadian rhythm affects many biological functions and may influence the biokinetics of radionuclides and observed responses. The aim of this study was to investigate if the time during the day of I-131 injection affects the biodistribution and absorbed dose to tissues in mice. Biodistribution studies were conducted on male C57BL/6 N mice for three diurnal time-series: the animals were i.v. injected with 160 kBq I-131 at 8 am, 12 pm or 4 pm. The activity concentration in organs and tissues was measured at 1 h to 7 days after administration and absorbed dose at day 7 was determined. Comparison between the three time-series showed statistically significant differences in activity concentration in all investigated tissues and organs. Administration performed at 12 pm resulted in general in higher absorbed dose to the organs than injection performed at 8 am and 4 pm. Time of day of administration affects the biodistribution of I-131 in mice and consequently the absorbed dose to individual organs. These findings advocate that subsequent biodistribution studies and dosimetry calculations should consider time-point of administration as a variable that could influence the results.
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| 4. |
- Andersson, Charlotte, et al.
(författare)
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Diurnal variations in biodistribution of the radionuclide I-131 in mice
- 2016
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Ingår i: Swedish Cancer Research Meeting, Gothenburg, 2016, November 7-8.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Background: Radionuclides are routinely used to diagnose and treat many different types of cancer. I-131 is a well-established radioisotope used in e.g. treatment of thyroid cancer and neuroblastoma. Accurate knowledge of I-131 biodistribution is essential to correctly estimate the absorbed dose to normal organs and determine potential risks from I-131 exposure, which is especially important when treating children. Many biological functions in living organisms follow a circadian rhythm. Nevertheless, little is known about diurnal variations in radionuclide biodistribution. This study investigates if circadian rhythm affects I-131 biodistribution in mice and absorbed dose to organs and tissues. Materials & Methods: The radioactivity concentration in mice tissues was studied at different time-points after administration of I-131, and absorbed doses were calculated. The effect of circadian rhythm was studied by varying the time of administration. Results: Difference in activity concentration between the administration time-points was observed at many time-points after administration for most investigated tissues. For some organs differences were also observed in the absorbed dose. The highest activity concentration and absorbed dose were found in the thyroid regardless of time of administration. Conclusion: The results demonstrate that the biodistribution of I-131 in mice is influenced by the time of day of administration. These findings advocate that circadian rhythm should be considered in biodistribution studies and suggests that time-point of administration of radiopharmaceuticals containing I-131 for therapy can be further optimized. An optimized time-point could result in higher absorbed dose to the tumor and/or lower absorbed dose to normal tissues.
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| 5. |
- Andersson, Charlotte, et al.
(författare)
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The influence of circadian rhythm on the biodistribution of I-131
- 2016
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Ingår i: Swedish Radiation Research Association for Young Scientists Workshop, Stockholm, 2016, August 25-26.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Background: I-131 is well-established in nuclear medicine. The thyroid is a target organ when treating thyroid cancer with unbound I-131, but also a risk organ in I-131-based radionuclide therapy. Exposure to I-131 can also occur from the environment at nuclear accidents. Accurate knowledge of I-131 biodistribution is essential to correctly estimate the absorbed dose to organs and determine potential risks from both medical and hazard exposure. Many biological functions follow a circadian rhythm. Nevertheless, circadian rhythm remains an unknown factor in radionuclide biodistribution. Aim: The purpose of this study was to investigate if circadian rhythm affects I-131 biodistribution in mice and hence absorbed dose to mouse tissues. Methods: The radioactivity concentration in various tissues was studied at different time points after administration of I-131 and absorbed doses were calculated according to the MIRD formalism. The effect of circadian rhythm was studied by varying the time of administration. Male C57BL/6N mice were i.v. injected with I-131 at 8 am, 12 pm or 4 pm and killed after 1h to 7d. Results: Statistically significant difference in activity concentration and absorbed dose between the three injection series was observed for at least one time point after injection for many tissues. Highest activity concentration and absorbed dose were found in the thyroid. Conclusion: The results demonstrated that the biodistribution of I-131 in mice is influenced by the time of day of administration to a certain extent. These findings advocate that circadian rhythm should be considered in biodistribution studies and dose calculations.
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| 6. |
- Elvborn, Mikael, et al.
(författare)
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Sex-dependence in absorbed dose from I-131 in mice
- 2016
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Ingår i: Höstmöte med Cancerfondens Planeringsgrupp för Onkologisk Radionuklidterapi, Uppsala, 2016, November 24-25.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 8. |
- Elvborn, Mikael, et al.
(författare)
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The influence of biological sex on thyroid cancer treatment risk assessment
- 2016
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Ingår i: Swedish Cancer Research Meeting, Gothenburg, 2016, November 7-8.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Background: Researchers are often reluctant towards using females in studies, especially when radiopharmaceuticals and hormonally dependent diseases are concerned. Simultaneously, women are more prone to thyroid-related diseases such as Grave’s disease and Hashimoto’s thyroiditis, with a 7-10 times higher incidence than in men. The thyroid gland synthesizes iodine-containing hormones, which are needed for several cellular processes in the body. I-131 is routinely used in thyroid cancer treatment, and I-131-containing pharmaceuticals are used for treatment of patients with some neuroendocrine tumor types. This study was performed to evaluate possible differences between sexes in tissue uptake of I-131 in mice. Methods: 35 male and 35 female mice (C57BL/6N, n=5/group) were intravenously injected with I-131 at 8 am, and animals were killed 1 h to 7 d after injection. Tissue samples were collected, weighed, and measured to determine I-131 activity concentration. Results: The results indicate differences in I-131 uptake between males and females, especially in the salivary glands and kidneys. In the majority of the tissues and observed time points, statistical significant differences were found. The decrease of activity concentration in thyroid after 18 h was slower for females (statistical significant), though the obtained maximum uptake was similar. Conclusion: The I-131 uptake differs between males and females, which would result in different absorbed doses from exposure to the same amount of I-131. The difference in magnitude is tissue-dependent. The results suggest biological sex to be treated as a variable in dose calculations and risk assessments when treating cancer patients with radiopharmaceuticals containing I-131.
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