Comparison of in vivo binding properties of the 18-kDa translocator protein (TSPO) ligands [(18)F]PBR102 and [ (18)F]PBR111 in a model of excitotoxin-induced neuroinflammation.

PURPOSE: The in vivo binding parameters of the novel imidazopyridine TSPO ligand [(18)F]PBR102 were assessed and compared with those of [(18)F]PBR111 in a rodent model of neuroinflammation. The validity of the key assumptions of the simplified reference tissue model (SRTM) for estimation of binding potential (BP) was determined, with validation against a two-tissue compartment model (2TC). METHODS: Acute neuroinflammation was assessed 7 days after unilateral stereotaxic administration of (R,S)-α-amino-3-hydroxy-5-methyl-4-isoxazolopropionique (AMPA) in anaesthetized adult Wistar rats. Anaesthetized rats were implanted with a femoral arterial cannula then injected with a low mass of [(18)F]PBR102 or [(18)F]PBR111 and dynamic images were acquired over 60 min using an INVEON PET/CT camera. Another population of rats underwent the same PET protocol after pretreatment with a presaturating mass of the same unlabelled tracer (1 mg/kg) to assess the validity of the reference region for SRTM analysis. Arterial blood was sampled during imaging, allowing pharmacokinetic determination of radiotracer concentrations. Plasma activity concentration-time curves were corrected for unchanged tracer based on metabolic characterization experiments in a separate cohort of Wistar rats. The stability of neuroinflammation in both imaging cohorts was assessed by [(125)I] CLINDE TSPO quantitative autoradiography, OX42/GFAP immunohistochemistry, Fluoro-Jade C histology, and elemental mapping using microparticle-induced x-ray emission spectroscopy. The BP of each ligand were assessed in the two cohorts of lesioned animals using both SRTM and a 2TC with arterial parent compound concentration, coupled with the results from the presaturation cohort for comparison and validation of the SRTM. RESULTS: The BPs of [(18)F]PBR102 [(18)F]PBR111 were equivalent, with improved signal-to-noise ratio and sensitivity compared with [(11)C]PK11195. The presaturation study showed differences in the volume of distribution between the ipsilateral striatum and the striatum contralateral to the injury (0.7) indicating that an assumption of the SRTM was not met. The modelling indicated that the BPs were consistent for both ligands. Between the SRTM and 2TC model, the BPs were highly correlated, but there was a bias in BP. CONCLUSION: [(18)F]PBR102 and [(18)F]PBR111 have equivalent binding properties in vivo, displaying significantly greater BPs with lower signal-to-noise ratio than [(11)C]PK11195. While an assumption of the SRTM was not met, this modelling approach was validated against 2TC modelling for both ligands, facilitating future use in longitudinal PET imaging of neuroinflammation.

Zinc from foliar-applied nanoparticle fertiliser is translocated to wheat grain: A 65Zn radiolabelled translocation study comparing conventional and novel foliar fertilisers.

Foliar zinc (Zn) fertilisers can be used to supplement or replace soil applications of Zn in situations where soil properties may decrease the plant bioavailability of Zn. However, conventional foliar Zn formulations such as zinc sulfate can cause leaf damage due to the rapid release of high amounts of Zn2+ into leaf tissue which can be locally phytotoxic. Zinc oxide nanoparticles (ZnO-NPs) offer an alternative approach by providing a more sustained release of Zn into leaf tissue, and potentially avoiding the need for multiple applications. We compared the efficacy of ZnO-NPs and microparticles (ZnO-MPs) to that of conventional formulations (ZnCl2 and ZnEDTA) in wheat. This is the first study to use 65Zn radiolabelled formulations and gamma spectrometry to determine the translocation of Zn to the grains and subsequent efficiency of foliar-applied ZnO-NP fertilisers. We found that ZnEDTA was the most efficient fertiliser in terms of the proportion of applied Zn translocated to wheat grain. We also investigated the effect of Zn application rate on fertiliser efficiency. For all forms of Zn, when plants were treated with Zn at 750 mg/L or 75 mg/L, there were no significant differences in the concentration of applied Zn translocated to the grain. This suggests that current Zn application rates could be decreased while still maintaining the nutritional quality of grain. Finally, using photo-stimulated luminescence (PSL) autoradiography and synchrotron-based X-ray fluorescence microscopy (XFM) we showed that the grain distribution of foliar-applied Zn mirrors that of Zn derived from root uptake.

Plutonium and other radionuclides persist across marine-to-terrestrial ecotopes in the Montebello Islands sixty years after nuclear tests.

Since the 1956 completion of nuclear testing at the Montebello Islands, Western Australia, this remote uninhabited island group has been relatively undisturbed (no major remediations) and currently functions as high-value marine and terrestrial habitat within the Montebello/Barrow Islands Marine Conservation Reserves. The former weapons testing sites, therefore, provide a unique opportunity for assessing the fate and behaviour of Anthropocene radionuclides subjected to natural processes across a range of shallow-marine to island-terrestrial ecological units (ecotopes). We collected soil, sediment and biota samples and analysed their radionuclide content using gamma and alpha spectrometry, photostimulated luminescence autoradiography and accelerator mass spectrometry. We found the activity levels of the fission and neutron-activation products have decreased by ~hundred-fold near the ground zero locations. However, Pu concentrations remain elevated, some of which are high relative to most other Australian and international sites (up to 25,050 Bq kg-1 of 239+240+241Pu). Across ecotopes, Pu ranked from highest to lowest in the following order: island soils > dunes > foredunes > marine sediments > and beach intertidal zone. Low values of Pu and other radionuclides were detected in all local wildlife tested including endangered species. Activity concentrations ranked (highest to lowest) terrestrial arthropods > terrestrial mammal and reptile bones > algae > oyster flesh > whole crab > sea turtle bone > stingray and teleost fish livers > sea cucumber flesh > sea turtle skin > teleost fish muscle. The three detonations (one from within a ship and two from 30 m towers) resulted in differing contaminant forms, with the ship detonation producing the highest activity concentrations and finer more inhalable particulate forms. The three sites are distinct in their 240/239Pu and 241/239Pu atom ratios, including the Pu transported by natural process or within migratory living organisms.

Abortion and religion.

PIP: This paper argues that religious communities should pose new questions about abortion in an attempt to reinvigorate the abortion debate and make it more constructive. Such questions would break the current impasse, enlarge the global and ecological scope of abortion inquiry, and engage plural religious perspectives in an interreligious dialogue about justice and abortion. After an introduction, the paper discusses the first impasse in the abortion debate, which is caused by conflicting definitions of personhood that create a fetus/pregnant woman dualism and artificially separate the fetus from its interdependence with the mother. Section 2 looks at how the abortion impasse results from the assertions of competing fetal and maternal rights and from conflict over who controls nature and women's bodies. The third section seeks alternatives to the dichotomizing of individual and community in the abortion debate in Christian theology, such as the notion of the relational self that demands attention to the wider social implications of reproduction. By examining theories that presume that people are relational, section 4 locates the abortion debate in a wider ecological context with concerns about overpopulation and environmental degradation. Section 5 explores questions of what authority can be used to determine whether abortion is ever justifiable for Christians and what authority is relevant for determining a Christian theological ethic of abortion. This section also looks at Jewish, Muslim, Hindu, and Buddhist views of abortion in the belief that the complex ethical issues relating to abortion may be explored through religious ritual.^ieng