Design, Synthesis, and Evaluation of [18F]BIBD-300 as a Positron Emission Tomography Tracer for Poly(ADP-Ribose) Polymerase-1.

Compounds 8a-j were designed to adjust the mode of interaction and lipophilicity of FTT by scaffold hopping and changing the length of the alkoxy groups. Compounds 8a, 8d, 8g, and BIBD-300 were screened for high-affinity PARP-1 through enzyme inhibition assays and are worthy of further evaluation. PET imaging of MCF-7 subcutaneous tumors with moderate expression of PARP-1 showed that compared to [18F]FTT, [18F]8a, [18F]8d, and [18F]8g exhibited greater nonspecific uptake, a lower target-to-nontarget ratio, and severe defluorination, while [18F]BIBD-300 exhibited lower nonspecific uptake and a greater target-to-nontarget ratio. PET imaging of 22Rv1 subcutaneous tumors, which highly express PARP-1, confirmed that the uptake of [18F]BIBD-300 in normal organs, such as the liver, muscle, and bone, was lower than that of [18F]FTT, and the ratio of tumor-to-muscle and tumor-to-liver [18F]BIBD-300 was greater than that of [18F]FTT. The biodistribution results in mice with MCF-7 and 22Rv1 subcutaneous tumors further validated the results of PET imaging. Unlike [18F]FTT, which mainly relies on hepatobiliary clearance, [18F]BIBD-300, which has lower lipophilicity, undergoes a partial shift from hepatobiliary to renal clearance, providing the possibility for [18F]BIBD-300 to indicate liver cancer. The difference in the PET imaging results for [18F]FTT, [18F]BIBD-300, and [18F]8j in 22Rv1 mice and the corresponding molecular docking results further confirmed that subtle structural modifications in lipophilicity greatly optimize the properties of the tracer. Cell uptake experiments also demonstrated that [18F]BIBD-300 has a high affinity for PARP-1. Metabolized and unmetabolized [18F]FTT and [18F]BIBD-300 were detected in the brain, indicating that they could not accurately quantify the amount of PARP-1 in the brain. However, PET imaging of glioma showed that both [18F]FTT and [18F]BIBD-300 could accurately localize both in situ to C6 and U87MG tumors. Based on its potential advantages in the diagnosis of breast cancer, prostate cancer, and glioma, as well as liver cancer, [18F]BIBD-300 is a new option for an excellent PARP-1 tracer.

18F-Labeled PET Tracers Specific for Adenosine A2A Receptor: Design, Synthesis, and Biological Evaluation.

By modifying the structures of targeted A2AR antagonists and tracers, novel compounds 3, 7a, 9, 12c, and BIBD-399 were designed and synthesized. In vitro inhibition experiments demonstrated that 3, 12c, and BIBD-399 have high affinity for A2AR. [18F]3 and [18F]BIBD-399 were successfully synthesized. In terms of biological distribution, the brain uptake of [18F]MNI-444 exhibits greater than that of [18F]3 and [18F]BIBD-399. PET imaging shows that [18F]3 is off-target in the brain, while [18F]BIBD-399 and [18F]MNI-444 can be specifically imaged in regions with high A2AR expression. Differently, [18F]BIBD-399 could quickly reach equilibrium in the targeted region within 10 min after administration, while [18F]MNI-444 shows a slowly increasing trend within 2 h of administration. [18F]BIBD-399 is mainly metabolized by the liver and kidney, and there is no obvious defluorination in vivo. Additional in vitro autoradiography showed that the striatal signals of [18F]BIBD-399 and [18F]MNI-444 were inhibited by the A2AR antagonist SCH442416 but not by the A1R antagonist DPCPX, demonstrating the high A2AR binding specificity of [18F]BIBD-399. Molecular docking further confirms the high affinity of MNI-444 and BIBD-399 for A2AR. Further tMCAo imaging showed that [18F]BIBD-399 can sensitively distinguish between infarcted and noninfarcted sides, a capability not observed with [18F]MNI-444. Given its pharmacokinetic properties and the ability to identify lesion regions, [18F]BIBD-399 has potential advantages in monitoring A2AR changes, meriting further clinical investigation.

A Multiplex RT-PCR Method for the Detection of Reptarenavirus Infection.

Reptarenaviruses cause Boid Inclusion Body Disease (BIBD), a fatal disease of boid snakes with an economic and ecological impact, as it affects both captive and wild constrictor snakes. The clinical picture of BIBD is highly variable but often only limited. Intracytoplasmic inclusion bodies (IB), which develop in most cell types including blood cells, are the pathognomonic hallmark of BIBD; their detection represents the diagnostic gold standard of the disease. However, IBs are not consistently present in clinically healthy reptarenavirus carriers, which can, if undetected, lead to and maintain the spread of the disease within and between snake populations. Sensitive viral detection tools are required for screening and control purposes; however, the genetic diversity of reptarenaviruses hampers the reverse transcription (RT) PCR-based diagnostics. Here, we describe a multiplex RT-PCR approach for the molecular diagnosis of reptarenavirus infection in blood samples. The method allows the detection of a wide range of reptarenaviruses with the detection limit reaching 40 copies per microliter of blood. Using 245 blood samples with a reference RT-PCR result, we show that the technique performs as well as the segment-specific RT-PCRs in our earlier studies. It can identify virus carriers and serve to limit reptarenavirus spreading in captive snake collections.

Synthesis and In Vitro and In Vivo Evaluation of 18F-Labeled Positron Emission Tomography Tracers for Imaging Aß Plaques.

Accurate quantification of amyloid beta (Aß) plaques is an important indicator for Alzheimer's disease diagnosis and treatment. For this purpose, new highly sensitive Aß tracers were designed by regulating the position and number of nitrogen atoms. A series of derivatives of florbetapir (AV45) containing different numbers and positions of N atoms were synthesized and evaluated for in vitro affinity and in vivo biodistribution. Preliminary study results showed that [18F]BIBD-124 and [18F]BIBD-127 had better clearance rates and less in vivo defluorination than AV45 in ICR (ICR = Institute of Cancer Research) mice. Autoradiography and molecular docking indicated that the binding sites of [18F]BIBD-124/127 were similar to that of [18F]AV45. Micro-positron emission tomography-computed tomography imaging further demonstrated that [18F]BIBD-124 could monitor Aß plaques similar to [18F]AV45. Besides, the imaging contrast of [18F]BIBD-124 is better than that of [18F]AV45. Mass spectrometric metabolic analysis showed that BIBD-124 was less demethylated than AV45 without subsequent acetylation, which might explain its less non-specific uptake and higher imaging contrast. Gauss calculations further confirmed that the introduction of N5 in [18F]BIBD-124 decreased demethylation. Considering imaging contrast and in vivo defluorination, [18F]BIBD-124 is expected to be a promising radiotracer of Aß plaques for further clinical trials.

[18F]BIBD-239: 18F-Labeled ER176, a Positron Emission Tomography Tracer Specific for the Translocator Protein.

[11C]ER176 has adequate sensitivity to image the human brain translocator protein (TSPO) in all three genotypes by positron emission tomography (PET). However, its clinical application is limited by the short half-life of 11C (20.38 min). To overcome the deficiency of [11C]ER176 and keep the pharmacophore features of ER176 to the maximum extent, we designed four fluorine-labeled ER176 derivatives using the deuterium method. In vitro competition binding confirmed that the designed compounds had high affinity for TSPO. Biodistribution experiments showed that tissues with high expression of TSPO had high uptake of these compounds, as well as that the compound showed high brain penetration and mild defluorination in vivo. Therefore, [18F]BIBD-239 with simple synthesis conditions was selected for further biological evaluation. Theoretical simulations showed that BIBD-239 and ER176 have similar binding modes and sites to Ala147-TSPO and Thr147-TSPO, which indicated that the tracers may have consistent sensitivity to the three affinity genotypes. In vitro autoradiography and in vivo PET studies of the ischemic rat brain showed dramatically higher uptake of [18F]BIBD-239 on the lesion site compared to the contralateral side with good brain kinetics. Additionally, [18F]BIBD-239 provided clear tumor PET images in a GL261 glioma model. Importantly, PET imaging and liquid chromatography-high-resolution mass spectrometry (LC-HRMS) results showed that in vivo defluorination and other metabolites of [18F]BIBD-239 did not interfere with brain imaging. Conclusively, [18F]BIBD-239, similar to ER176 with low polymorphism sensitivity, has simple labeling conditions, high labeling yield, high affinity, and high specificity for TSPO, and it is planned for further evaluation in higher species.

Novel 18F-Labeled PET Tracers Specific to Aromatase: Design, Synthesis, and Biological Evaluation.

The abnormal expression of aromatase is associated with the occurrence and development of a variety of neurological diseases and tumors. A series of 18F-labeled and 68Ga-labeled potential aromatase-binding candidate compounds were designed and synthesized based on the structures of aromatase inhibitors. Competitive inhibition experiments in vitro and molecular docking showed that BIBD-069 and BIBD-071 have high affinity for aromatase. The radiolabeling conditions of [18F]BIBD-069 and [18F]BIBD-071 were simple, and the yields were high. Biodistribution and in vivo inhibition experiments confirmed that [18F]BIBD-069 and [18F]BIBD-071 specifically bind to aromatase. [18F]BIBD-069 and [18F]BIBD-071 selectively imaged the amygdala and nucleus of the stria terminalis, which is similar to the imaging result of [11C]vorozole. Radiometabolites of [18F]BIBD-069 and [18F]BIBD-071 did not bind to aromatase and interfered with brain imaging. MicroPET-CT imaging further confirmed that [18F]BIBD-069 and [18F]BIBD-071 can specifically bind to aromatase and were not defluorinated in vivo. Given that [18F]BIBD-069 and [18F]BIBD-071 exhibit excellent aromatase binding affinities, mild radiolabeling conditions, and good pharmacokinetics, they can be important tools for the diagnosis and treatment of aromatase-related diseases.

Virtopsy of a gravid Boa constrictor using computed tomography and magnetic resonance imaging.

This article presents radiologic examinations of a deeply sedated Boa constrictor with boid inclusion body disease (BIBD) as an adjunction to the subsequent necropsy. This method is known as virtopsy. The Boa constrictor in the present case was gravid. Computed tomography (CT) allowed for the detailed depiction of a fetal skeleton at the rear end of the adult snake. Furthermore, tiny gas formation was detected inside the cranium of the fetus, which was deemed a radiologic sign for decomposition. Magnetic resonance imaging (MRI) delineated the soft tissue at high resolution. This article illustrates the use of CT and MRI for the examination of a gravid Boa constrictor before necropsy and demonstrates the detection of "normal" postmortem findings leading to the confirmation of fetal death in situ.

Differences in Tissue and Species Tropism of Reptarenavirus Species Studied by Vesicular Stomatitis Virus Pseudotypes.

Reptarenaviruses cause Boid Inclusion Body Disease (BIBD), and co-infections by several reptarenaviruses are common in affected snakes. Reptarenaviruses have only been found in captive snakes, and their reservoir hosts remain unknown. In affected animals, reptarenaviruses appear to replicate in most cell types, but their complete host range, as well as tissue and cell tropism are unknown. As with other enveloped viruses, the glycoproteins (GPs) present on the virion's surface mediate reptarenavirus cell entry, and therefore, the GPs play a critical role in the virus cell and tissue tropism. Herein, we employed single cycle replication, GP deficient, recombinant vesicular stomatitis virus (VSV) expressing the enhanced green fluorescent protein (scrVSV∆G-eGFP) pseudotyped with different reptarenavirus GPs to study the virus cell tropism. We found that scrVSV∆G-eGFPs pseudotyped with reptarenavirus GPs readily entered mammalian cell lines, and some mammalian cell lines exhibited higher, compared to snake cell lines, susceptibility to reptarenavirus GP-mediated infection. Mammarenavirus GPs used as controls also mediated efficient entry into several snake cell lines. Our results confirm an important role of the virus surface GP in reptarenavirus cell tropism and that mamma-and reptarenaviruses exhibit high cross-species transmission potential.

INVESTIGATION OF THE TRACHEAL MUCOCILIARY CLEARANCE IN SNAKES WITH AND WITHOUT BOID INCLUSION BODY DISEASE AND LUNG PATHOLOGY.

Pneumonia is a common complication of boid inclusion body disease (BIBD) in snakes. The tracheal mucociliary apparatus of eight boas ( Boa constrictor) and two pythons ( Python regius, Morelia viridis) was examined to assess whether absent or reduced mucociliary clearance could be a predisposing factor. Nine of the examined snakes were positive for BIBD by detection of inclusion bodies and three had lung pathologies other than the formation of inclusion bodies. A considerable individual variation of ciliary beat frequency (CBF, 3.0 ± 0.75 Hz to 7.8 ± 1.27 Hz), transport speed (23.1 ± 12.56 µm/sec to 189.2 ± 41.17 µm/sec), and transport direction (-12.5° ± 11.43° to 36.1° ± 7.53°) was found. CBFs of the BIBD-affected snakes with or without lung pathologies were markedly lower than ranges published for birds or mammals, but the net transport speeds and directions lay well within. The present investigation does therefore not reveal any signs of an inadequate mucociliary clearance in BIBD-affected snakes.

Chorea as a clinical feature of the basophilic inclusion body disease subtype of fused-in-sarcoma-associated frontotemporal lobar degeneration.

Choreoathetoid involuntary movements are rarely reported in patients with frontotemporal lobar degeneration (FTLD), suggesting their exclusion as a supportive feature in clinical diagnostic criteria for FTLD. Here, we identified three cases of the behavioral variant of frontotemporal dementia (bvFTD) that display chorea with fused in sarcoma (FUS)-positive inclusions (FTLD-FUS) and the basophilic inclusion body disease (BIBD) subtype. We determined the behavioral and cognitive features in this group that were distinct from other FTLD-FUS cases. We also reviewed the clinical records of 72 FTLD cases, and clarified additional clinical features that are predictive of the BIBD pathology. Symptom onset in the three patients with chorea was at 44.0 years of age (±12.0 years), and occurred in the absence of a family history of dementia. The cases were consistent with a clinical form of FTD known as bvFTD, as well as reduced neurological muscle tone in addition to chorea. The three patients showed no or mild parkinsonism, which by contrast, increased substantially in the other FTLD cases until a later stage of disease. The three patients exhibited severe caudate atrophy, which has previously been reported as a histological feature distinguishing FTLD-FUS from FTLD-tau or FTLD-TAR DNA-binding protein 43. Thus, our findings suggest that the clinical feature of choreoathetosis in bvFTD might be associated with FTLD-FUS, and in particular, with the BIBD subtype.

Frontotemporal lobar degeneration: diversity of FTLD lesions.

Frontotemporal lobar degeneration (FTLD) is a heterogeneous group including both sporadic and familial diseases, characterized by a macroscopic alteration. It may correspond to various cognitive syndromes: behavioral variant of frontotemporal dementia (bvFTD), progressive nonfluent aphasia, and semantic dementia. The neuropathologic classification is now based on identification of the protein that accumulates in neurons and glia: Tau, TAR DNA Binding Protein 43 (TDP-43), and FUsed in Sarcoma (FUS). The disorders in which the corresponding proteins accumulate have been named FTLD-Tau, FTLD-TDP, and FTLD-FUS. FTLD-Tau includes sporadic cases (e.g. Pick's disease) and Tau mutations. FTLD-TDP are subdivided within four types (A, B, C, D) according to the shape and distribution of TDP-43 positive lesions within the associative frontal cortex. The FTLD-FUS group includes atypical FTLD with ubiquitinated lesions (FTLD-U), Neuronal Intermediate Filament Inclusion Disease (NIFID) and Basophilic Inclusion Body Disease (BIBD).

Pathological features of FTLD-FUS in a Japanese population: analyses of nine cases.

We investigated the pathological features of frontotemporal lobar degeneration (FTLD) with fused in sarcoma protein (FUS) accumulation (FTLD-FUS) in the Japanese population. Only one out of nine FTLD-FUS cases showed pathology that corresponds to atypical FTLD with ubiquitin-positive inclusions (aFTLD-U). Five were basophilic inclusion body disease (BIBD) and two were neuronal intermediate filament inclusion disease. The last case was unclassifiable and was associated with dystrophic neurites (DNs) as the predominant FUS pathology. The results of this study indicate an ethnic difference from western countries. In Japan, BIBD is the most common subtype of FTLD-FUS and aFTLD-U is rare, a finding which contrasts with aFTLD-U being the most common form in western countries. Immunohistochemical analyses of these FTLD-FUS cases reveal that FUS abnormally accumulated in neuronal cytoplasmic inclusions (NCIs) and DNs has an immunohistochemical profile distinct from that of normal, nuclear FUS. NCIs and DNs are more readily stained than the nuclei by antibodies to the middle portion of FUS. Antibodies to the carboxyl terminal portion, on the other hand, stain the nuclei more readily than NCIs and DNs. Such an immunohistochemical profile of NCIs and DNs was similar to that of cytoplasmic granular FUS staining which we previously reported to be associated with dendrites and synapses. Redistribution of FUS from the nucleus to the cytoplasm could be associated with the formation of abnormal FUS aggregates in FTLD-FUS.