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Objectives: To investigate the biomechanical properties of porcine oral tissues with in vivo ultrasonography and to compare the difference between oral alveolar mucosa and gingival tissue concerning compressional and tensile mechanical strain. Materials and Methods: Sinclair minipigs (6 females and 4 males, 6 to 18 months of age) were anesthetized for ultrasonography. In vivo high‐frequency tissue harmonic ultrasound (12/24 MHz) cine‐loops were obtained while inducing mechanical tissue stress (0 to 1 N). Post‐processing strain analysis was performed in a cardiac speckle tracking software (EchoInsight®). Region of interest (ROI) was placed for gingival and alveolar mucosa tissues for longitudinal (compressional) and tensile strain analyses. A calibrated gel pad was employed to determine the absolute force (pressure) for the measured tissue strain response function. The resulting elasticity data was statistically analyzed using custom Matlab scripts. Results: In total, 38 sonography cine‐loops around the third premolars were included in the investigation. The longitudinal strain of alveolar mucosa εAML was found to be significantly (P <.05) larger than that of gingiva εGL. Across the measured force range, εAML ~ 1.7 × εGL. Significant differences between alveolar mucosa and gingiva tissues were found for all forces. The tensile strain of the alveolar mucosa εAMT was found to be ~2 × εGT (on the epithelial surface of the gingiva). Both were statistically significantly different for forces exceeding ~0.08 N. At depth, that is, 500 and 1000 μm below the epithelial surface, the gingiva was found to have less ability to stretch contrary to the alveolar mucosa. Gingival tissue at 500 μm depth has significantly less tensile strain than at its surface and more than at 1000 μm depth. In contrast, the tensile strain of alveolar mucosa is largely independent of depth. Conclusion: Ultrasonography can reveal significant differences in oral alveolar mucosal and gingival elastic properties, such as compressional and tensile strain. Under minute forces equivalent to 10 to 40 g, these differences can be observed. As dental ultrasound is a chairside, and noninvasive modality, obtaining real‐time images might soon find clinical utility as a new diagnostic tool for the objective and quantitative assessment of periodontal and peri‐implant soft tissues in clinical and research realms. As ultrasound is a safe modality with no known bioeffects, longitudinal monitoring of areas of concern would be particularly attractive. [ABSTRACT FROM AUTHOR]

Fluorine-18 labeled phenethylguanidines are currently under development in our laboratory as radiotracers for quantifying regional cardiac sympathetic nerve density using PET imaging techniques. In this study, we report an efficient synthesis of 18 F-hydroxyphenethylguanidines consisting of nucleophilic aromatic [ 18 F]fluorination of a protected diaryliodonium salt precursor followed by a single deprotection step to afford the desired radiolabeled compound. This approach has been shown to reliably produce 4-[ 18 F]fluoro-m-hydroxyphenethylguanidine ([ 18 F]4F-MHPG, [ 18 F]1) and its structural isomer 3-[ 18 F]fluoro-p-hydroxyphenethylguanidine ([ 18 F]3F-PHPG, [ 18 F]2) with good radiochemical yields. Preclinical evaluations of [ 18 F]2 in nonhuman primates were performed to compare its imaging properties, metabolism, and myocardial kinetics with those obtained previously with [ 18 F]1. The results of these studies have demonstrated that [ 18 F]2 exhibits imaging properties comparable to those of [ 18 F]1. Myocardial tracer kinetic analysis of each tracer provides quantitative metrics of cardiac sympathetic nerve density. Based on these findings, first-in-human PET studies with [ 18 F]1 and [ 18 F]2 are currently in progress to assess their ability to accurately measure regional cardiac sympathetic denervation in patients with heart disease, with the ultimate goal of selecting a lead compound for further clinical development.

The phenol of 1-(3-(1H-imidazol-1-yl)propyl)-3-(4-hydroxy-3-methoxyphenyl)thiourea was selectively carbon-11 labelled to generate [ 11 C]PBD150 in 7.3% yield from [ 11 C]methyl triflate (non-decay corrected; radiochemical purity ≥95%, specific activity = 5.7 Ci/µmol, n=5). Evaluation of [ 11 C]PBD150 by small animal PET imaging (mouse and rat) determined it does not permeate the blood brain barrier, indicating previously described therapeutic effect in transgenic mice was likely not the result of inhibiting central nervous system glutaminyl cyclase.

Interest in quantifying metal-Aβ species in vivo led to the synthesis and evaluation of [ 11 C]L2-b and [ 18 F]FL2-b as radiopharmaceuticals for studying the metallobiology of Alzheimer's disease (AD) using positron emission tomography (PET) imaging. [ 11 C]L2-b was synthesized in 3.6% radiochemical yield (nondecay corrected, n = 3), >95% radiochemical purity, from the corresponding desmethyl precursor. [ 18 F]FL2-b was synthesized in 1.0% radiochemical yield (nondecay corrected, n = 3), >99% radiochemical purity, from a 6-chloro pyridine precursor. Autoradiography experiments with AD positive and healthy control brain samples were used to determine the specificity of binding for the radioligands compared to [ 11 C]PiB, a known imaging agent for β-amyloid (Aβ) aggregates. The K d for [ 11 C]L2-b and [ 18 F]FL2-b were found to be 3.5 and 9.4 nM, respectively, from those tissue studies. Displacement studies of [ 11 C]L2-b and [ 18 C]L2-b was examined through microPET imaging in healthy rhesus macaque, which revealed a maximum uptake at 2.5 min (peak SUV = 2.0) followed by rapid egress ( 11 C]L2-b was examined through microPET imaging in healthy rhesus macaque, which revealed a maximum uptake at 2.5 min (peak SUV = 2.0) followed by rapid egress ( n = 2).