Dosimetry of Beryllium in an Animal Model by Accelerator Mass Spectrometry (AMS)

1. Dosimetry of Beryllium in an Animal Model by Accelerator Mass Spectrometry (AMS) Marina Chiarappa-Zucca R.C. Finkel J.E. McAninch R.E. Martinelli K.W. Turteltaub Lawrence Livermore National Laboratory University of California

2. Our aim is to develop a method to quantify attomole (10-18) amounts of Be in biological samples • This method should enable the identification of molecular targets of Be at very low doses and provide detailed characterization of Be dosimetry • Demonstration of this capability will facilitate research collaborations on the cellular and molecular mechanisms of CBD

3. Outline • Introduction • What is accelerator mass spectrometry (AMS)? • Experimental Approach • Sample preparation steps for extracting Be for AMS • AMS measurement of Be standards • Data from experiments showing Be distribution in mouse tissues • Conclusions

4. What is AMS?

5. AMS provides high sensitivity measurements of long-lived (10 < t1/2 > 107 yrs) radioisotopes • AMS counts nuclei directly rather then measuring radioactive decay This results in 3-9 orders of magnitude more sensitivity relative to scintillation counting • Allows analysis of attomole quantities in small samples (µg-mg) with low activity levels (nCi-fCi) • LLNL has 15 years of experience with AMS and has pioneered the bioscience applications

6. Accelerators at Lawrence Livermore National Laboratory • 64 samples (plus standards and blanks) measured as a set • >100 unknowns can be quantified in 24 hr of accelerator time Tandem; multiple isotopes including 10Be 14C BioAMS

7. AMS can be used to measure 10Be • Routine sensitivity is ~0.02 fg • Experiments require fCi total activities • 10Be has a long half life (1.6 My) and therefore can be measured in samples from months to years • 10Be in low dose experiments can typically be handled as non-radioactive and non-hazardous 10Be has significant advantages compared to other Be isotopes

8. Sample Preparation Steps

9. Acid digestion Precipitation Disposable Quartz Crucibles Oxidizing to BeO Packing into AMS target AMS Ion Source There are multiple steps for extracting Be from samples for AMS measurement

10. AMS Measurements of Standards

11. 109 1.0E+09 Measured 10Be atoms 107 1.0E+07 Method Detection Limit 105 1.0E+05 109 107 1.00E+05 1.00E+07 1.00E+09 Expected 10Be atoms AMS measurement of standards is linear in the range of interest with good precision • Each data point represents the mean ± SD of three independently prepared standards • Instrument precision is 1-3%

12. Proof-of-Concept Experiment

13. Proof of concept experiments show Be distribution in mouse tissues • 30 g male ICR mice • Intraperitoneal injection of0.05, 0.5, and 5.0 µg Be (~2-200 µg/kg body weight) • Three mice used for each dose • 24 hr exposure • Liver,spleen,kidneys,lung,blood, and femurs prepared for AMS analysis

14. 105 Be (ng/g wet tissue) 10 method detection limit 10-3 0.001 0.1 10 Total Dose (µg Be) Be measured in tissues is dose-dependent within dose range studied • Spleen and blood data extrapolated to determine dose limits with current MDL ~ 200 pg(.007 µg/kg bw) * ~ 0.01 µg (0.3 µg/kg bw) ** * ** These doses are below environmental Be exposures (e.g. for humans 0.9  0.5 µg/kg bw)

15. Conclusions • AMS provides high sensitivity 10Be measurements in biological samples • Our future direction is to study mechanisms of Be disease • Explore molecular dosimetry • Identify molecular (e.g. protein) targets that are responsible or involved in CBD • Evaluate the correlation between these endpoints and susceptibility to CBD • We are ready now to collaborate with other researchers that have specific applications for this capability

16. Funding Office of Biological and Environmental Research U.S. Department of Energy