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We investigated nuclear medicine therapeutics targeting the L-type amino acid transporter 1 (LAT1). We previously reported that a nuclear medicine therapeutic drug using astatine 211 (211At), an alpha-emitting nuclide that can be produced in an accelerator and targets LAT1 as a molecular target, is effective. The seed compound was 3-[211At] Astato-α-methyl-L-tyrosine (211At-AAMT-OH-L). We used a unique labeling method. By changing the OH group of phenol to a methyl group, retention was successfully increased. It was also found that the amount of the L-isomer taken up by the D-isomer and L-isomer was clearly higher, and the L-isomer was superior as a therapeutic drug. Compounds in which the methyl group was replaced with an ethyl or propyl group were also examined, but their retention did not increase significantly. In fact, we observed increased non-specific accumulation and dynamics, suggesting that labeling may be off. In addition, 211At-AAMT-O-Me-L, which has a simple structure, was clearly superior in terms of uptake speed for several candidate compounds. As a result, we were able to develop a compound that can be easily labeled, has high specific radioactivity, is stable, and has a strong therapeutic effect. [ABSTRACT FROM AUTHOR]

Novel nuclear medicine therapeutics are being developed by labeling medium-molecular-weight compounds with short-lived alpha-emitting radionuclides. Fibroblast activation protein α (FAPα) is recognized as a highly useful molecular target, and its inhibitor, FAPI, is a compound capable of theranostics, both therapeutic and diagnostic, for cancer treatment. In this study, we compared the functions of two compounds that target FAPα: 211At-FAPI1 and 211At-FAPI2. First, in vitro screening procedures are generally accepted because of the low endogenous expression of FAPα. We suggest the usefulness of this 3D culture system for in vitro screening. Second, when FAPIs are used therapeutically, the expected therapeutic effects are often not achieved. Therefore, we compared the accumulation and excretion in tumor tissues and the anti-tumor effects based on the length of the linker in the compounds. The compounds were rapidly labeled using the Shirakami reaction. Doubling the linker length increased tumor retention. Additionally, the excretion pathway was altered, suggesting a potential reduction in toxicity. Although no significant differences were observed in the anti-tumor effects of 211At-FAPI1 and 211At-FAPI2, it was confirmed that the linker length affects the biological half-life. [ABSTRACT FROM AUTHOR]

Birds, bats and ants are recognised as significant arthropod predators. However, empirical studies reveal inconsistent trends in their relative roles in top‐down control across strata. Here, we describe the differences between forest strata in the separate effects of birds, bats and ants on arthropod densities and their cascading effects on plant damage.We implemented a factorial design to exclude vertebrates and ants in both the canopy and understorey. Additionally, we separately excluded birds and bats from the understorey using diurnal and nocturnal exclosures. At the end of the experiments, we collected all arthropods and assessed herbivory damage.Arthropods responded similarly to predator exclusion across forest strata, with a density increase of 81% on trees without vertebrates and 53% without both vertebrates and ants. Additionally, bird exclusion alone led to an 89% increase in arthropod density, while bat exclusion resulted in a 63% increase. Herbivory increased by 42% when vertebrates were excluded and by 35% when both vertebrates and ants were excluded. Bird exclusion alone increased herbivory damage by 28%, while the exclusion of bats showed a detectable but non‐significant increase (by 22%). In contrast, ant exclusion had no significant effect on arthropod density or herbivory damage across strata.Our results reveal that the effects of birds and bats on arthropod density and herbivory damage are similar between the forest canopy and understorey in this temperate forest. In addition, ants were not found to be significant predators in our system. Furthermore, birds, bats and ants appeared to exhibit antagonistic relationships in influencing arthropod density. These findings highlight, unprecedentedly, the equal importance of birds and bats in maintaining ecological balance across different strata of a temperate forest. [ABSTRACT FROM AUTHOR]

The foraging efficiency of Alpine Accentors Prunella collaris and Japanese Accentors P. rubida is highest on the snow surface in the alpine zone, where they forage for fallen arthropods. To compare the foraging efficiency of two bird species across alpine habitats, including the snow surface, and discuss the impact of changes in snow cover on their foraging behaviour. The foraging efficiency of two alpine bird species, recorded as the number of pecks per unit time, was compared in the alpine zone of Mount Norikura in central Japan, among four habitat types: snow surface, Japanese Stone Pine scrub, alpine tundra and scree. In total, respective 45 and 32 foraging sequences of Alpine Accentors and Japanese Accentors were recorded. For both species, foraging efficiency was markedly higher on the snow surface than in other habitats. Alpine bird species exhibit high foraging efficiency on the snow surface in the alpine zone, assuming that prey sizes are similar across habitats. With the decreasing amount of remaining snowpack in the alpine zone, due to the general trend of climate change, bird species will likely have a shorter period to efficiently utilize these foraging habitats in the future. [ABSTRACT FROM AUTHOR]