Synthesis and Evaluation of a Novel PET Radioligand for Imaging Glutaminyl Cyclase Activity as a Biomarker for Detecting Alzheimer's Disease.

Several new lines of research have demonstrated that a significant number of amyloid-ß peptides found in Alzheimer's disease (AD) are truncated and undergo post-translational modification by glutaminyl cyclase (QC) at the N-terminal. Notably, QC's products of Abeta-pE3 and Abeta-pE11 have been active targets for investigational drug development. This work describes the design, synthesis, characterization, and in vivo validation of a novel PET radioligand, [18F]PB0822, for targeted imaging of QC. We report herein a simplified and robust chemistry for the synthesis of the standard compound, [19F]PB0822, and the corresponding [18F]PB0822 radioligand. The PET probe was developed with 99.9% radiochemical purity, a molar activity of 965 Ci.mmol-1, and an IC50 of 56.3 nM, comparable to those of the parent PQ912 inhibitor (62.5 nM). Noninvasive PET imaging showed that the probe is distributed in the brain 5 min after intravenous injection. Further, in vivo PET imaging with [18F]PB0822 revealed that AD 5XFAD mice harbor significantly higher QC activity than WT counterparts. The data also suggested that QC activity is found across different brain regions of the tested animals.

Increased sensitivity in detection of deficits following two commonly used animal models of stroke.

Stroke is a leading cause of death and disability in the United States. Most strokes are ischemic, resulting in both cognitive and motor impairments. Animal models of ischemic stroke such as the distal middle cerebral artery occlusion (dMCAO) and photothrombotic stroke (PTS) procedures have become invaluable tools, with their own advantages and disadvantages. The dMCAO model is clinically relevant as it occludes the artery most affected in humans, but yields variability in the infarct location as well as the behavioral and cognitive phenotypes disrupted. The PTS model has the advantage of allowing for targeted location of infarct, but is less clinically relevant. The present study evaluates phenotype disruption over time in mice subjected to either dMCAO, PTS, or a sham surgery. Post-surgery, animals were tested over 28 days on standard motor tasks (grid walk, cylinder, tapered beam, and rotating beam), as well as a novel odor-based operant task; the 5:1 Odor Discrimination Task (ODT). Results demonstrate a significantly greater disturbance of motor control with PTS as compared with Sham and dMCAO. Disruption of the PTS group was detected up to 28 days post-stroke on the grid walk, and up to 7 days on the rotating and tapered beam tasks. PTS also led to significant short-term disruption of ODT performance (1-day post-surgery), exclusively in males, which appeared to be driven by motoric disruption of the lick response. Together, this data provides critical insights into the selection and optimization of animal models for ischemic stroke research. Notably, the PTS procedure was best suited for producing disruptions of motor behavior that can be detected with common behavioral assays and are relatively enduring, as is observed in human stroke.

Simulation Teaching Associates: a Model Utilizing Senior Medical Students as Simulation Educators.

Student-as-teacher programs have become commonplace in undergraduate medical education over the past 15 years. Recognizing the important role of medical students as teachers, we created an innovative Simulation Teaching Associate elective to improve the quality and consistency of simulation education and to encourage and support medical students as future educators.

Tumor therapy by targeting extracellular hydroxyapatite using novel drugs: A paradigm shift.

BACKGROUND: It has been shown that tumor microenvironment (TME) hydroxyapatite (HAP) is typically associated with many malignancies and plays a role in tumor progression and growth. Additionally, acidosis in the TME has been reported to play a key role in selecting for a more aggressive tumor phenotype, drug resistance and desensitization to immunotherapy for many types of cancers. TME-HAP is an attractive target for tumor detection and treatment development since HAP is generally absent from normal soft tissue. We provide strong evidence that dissolution of hydroxyapatite (HAP) within the tumor microenvironment (TME-HAP) using a novel therapeutic can be used to kill cancer cells both in vitro and in vivo with minimal adverse effects. METHODS: We developed an injectable cation exchange nano particulate sulfonated polystyrene solution (NSPS) that we engineered to dissolve TME-HAP, inducing localized acute alkalosis and inhibition of tumor growth and glucose metabolism. This was evaluated in cell culture using 4T1, MDA-MB-231 triple negative breast cancer cells, MCF10 normal breast cells, and H292 lung cancer cells, and in vivo using orthotopic mouse models of cancer that contained detectable microenvironment HAP including breast (MMTV-Neu, 4T1, and MDA-MB-231), prostate (PC3) and colon (HCA7) cancer using 18 F-NaF for HAP and 18 F-FDG for glucose metabolism with PET imaging. On the other hand, H292 lung tumor cells that lacked detectable microenvironment HAP and MCF10a normal breast cells that do not produce HAP served as negative controls. Tumor microenvironment pH levels following injection of NSPS were evaluated via Chemical Exchange Saturation (CEST) MRI and via ex vivo methods. RESULTS: Within 24 h of adding the small concentration of 1X of NSPS (~7 µM), we observed significant tumor cell death (~ 10%, p < 0.05) in 4T1 and MDA-MB-231 cell cultures that contain HAP but ⟨2% in H292 and MCF10a cells that lack detectable HAP and in controls. Using CEST MRI, we found extracellular pH (pHe) in the 4T1 breast tumors, located in the mammary fat pad, to increase by nearly 10% from baseline before gradually receding back to baseline during the first hour post NSPS administration. in the tumors that contained TME-HAP in mouse models, MMTV-Neu, 4T1, and MDA-MB-231, PC3, and HCA7, there was a significant reduction (p<0.05) in 18 F-Na Fuptake post NSPS treatment as expected; 18 F- uptake in the tumor = 3.8 ± 0.5 %ID/g (percent of the injected dose per gram) at baseline compared to 1.8 ±0.5 %ID/g following one-time treatment with 100 mg/kg NSPS. Of similar importance, is that 18 F-FDG uptake in the tumors was reduced by more than 75% compared to baseline within 24 h of treatment with one-time NSPS which persisted for at least one week. Additionally, tumor growth was significantly slower (p < 0.05) in the mice treated with one-time NSPS. Toxicity showed no evidence of any adverse effects, a finding attributed to the absence of HAP in normal soft tissue and to our therapeutic NSPS having limited penetration to access HAP within skeletal bone. CONCLUSION: Dissolution of TME-HAP using our novel NSPS has the potential to provide a new treatment paradigm to enhance the management of cancer patients with poor prognosis.

Fully automated radiosynthesis of [68Ga]Ga-FAPI-46 with cyclotron produced gallium.

BACKGROUND: Radiopharmaceuticals capable of targeting the fibroblast activation protein have become widely utilized in the research realm as well as show great promise to be commercialized; with [68Ga]Ga-FAPI-46 being one of the most widely utilized. Until now the synthesis has relied on generator-produced gallium-68. Here we present a developed method to utilize liquid-target cyclotron-produced gallium-68 to prepare [68Ga]Ga-FAPI-46. RESULTS: A fully-automated manufacturing process for [68Ga]Ga-FAPI-46 was developed starting with the 68Zn[p,n]68Ga cyclotron bombardment to provide [68Ga]GaCl3, automated purification of the [68Ga]GaCl3, chelation with the precursor, and final formulation/purification. The activity levels produced were sufficient for multiple clinical research doses, and the final product met all release criteria. Furthermore, the process consistently provides < 2% of Ga-66 and Ga-67 at the 4-h expiry, meeting the Ph. Eur. CONCLUSIONS: The automated radiosynthesis on the GE FASTlab 2 module purifies the cyclotron output into [68Ga]GaCl3, performs the labeling, formulates the product, and sterilizes the product while transferring to the final vial. Production of > 40 mCi (> 1480 MBq) of [68Ga]Ga-FAPI-46 in excellent radiochemical yield was achieved with all batches meeting release criteria.

Blocking Formation of Neurotoxic Reactive Astrocytes is Beneficial Following Stroke.

Microglia and astrocytes play an important role in the neuroinflammatory response and contribute to both the destruction of neighboring tissue as well as the resolution of inflammation following stroke. These reactive glial cells are highly heterogeneous at both the transcriptomic and functional level. Depending upon the stimulus, microglia and astrocytes mount a complex, and specific response composed of distinct microglial and astrocyte substates. These substates ultimately drive the landscape of the initiation and recovery from the adverse stimulus. In one state, inflammation- and damage-induced microglia release tumor necrosis factor (TNF), interleukin 1α (IL1α), and complement component 1q (C1q), together 'TIC'. This cocktail of cytokines drives astrocytes into a neurotoxic reactive astrocyte (nRA) substate. This nRA substate is associated with loss of many physiological astrocyte functions (e.g., synapse formation and maturation, phagocytosis, among others), as well as a gain-of-function release of neurotoxic long-chain fatty acids which kill neighboring cells. Here we report that transgenic removal of TIC led to reduction of gliosis, infarct expansion, and worsened functional deficits in the acute and delayed stages following stroke. Our results suggest that TIC cytokines, and likely nRAs play an important role that may maintain neuroinflammation and inhibit functional motor recovery after ischemic stroke. This is the first report that this paradigm is relevant in stroke and that therapies against nRAs may be a novel means to treat patients. Since nRAs are evolutionarily conserved from rodents to humans and present in multiple neurodegenerative diseases and injuries, further identification of mechanistic role of nRAs will lead to a better understanding of the neuroinflammatory response and the development of new therapies.

Increased microglia activation in late non-central nervous system cancer survivors links to chronic systemic symptomatology.

Prolonged inflammatory expression within the central nervous system (CNS) is recognized by the brain as a molecular signal of "sickness", that has knock-on effects to the blood-brain barrier, brain-spinal barrier, blood-cerebrospinal fluid barrier, neuro-axonal structures, neurotransmitter activity, synaptic plasticity, neuroendocrine function, and resultant systemic symptomatology. It is concurred that the inflammatory process associated with cancer and cancer treatments underline systemic symptoms present in a large portion of survivors, although this concept is largely theoretical from disparate and indirect evidence and/or clinical anecdotal reports. We conducted a proof-of-concept study to link for the first time late non-CNS cancer survivors presenting chronic systemic symptoms and the presence of centralized inflammation, or neuroinflammation, using TSPO-binding PET tracer [11 C]-PBR28 to visualize microglial activation. We compared PBR28 SUVR in 10 non-CNS cancer survivors and 10 matched healthy controls. Our data revealed (1) microglial activation was significantly higher in caudate, temporal, and occipital regions in late non-central nervous system/CNS cancer survivors compared to healthy controls; (2) increased neuroinflammation in cancer survivors was not accompanied by significant differences in plasma cytokine markers of peripheral inflammation; (3) increased neuroinflammation was not accompanied by reduced fractional anisotropy, suggesting intact white matter microstructural integrity, a marker of neurovascular fiber tract organization; and (4) the presentation of chronic systemic symptoms in cancer survivors was significantly connected with microglial activation. We present the first data empirically supporting the concept of a peripheral-to-centralized inflammatory response in non-CNS cancer survivors, specifically those previously afflicted with head and neck cancer. Following resolution of the initial peripheral inflammation from the cancer/its treatments, in some cases damage/toxification to the central nervous system occurs, ensuing chronic systemic symptoms.

Employing High-Fidelity Simulation for the High-Risk, Low-Frequency Diagnosis and Management of Acute Radiation Syndrome (ARS).

Introduction: Acute radiation syndrome (ARS) is a high-risk, low-frequency diagnosis that can be fatal and is difficult to diagnose without an obvious history of ionizing radiation exposure. Methods: Twenty-two emergency medicine residents and one pharmacy resident participated in an hour-long simulation session. To accommodate all learners, the simulation was conducted eight times over a block of scheduled time (two to four learners/session). Sessions included a prebriefing, pre/post questionnaires, the ARS case, and a debriefing. Learners evaluated and managed a 47-year-old male (manikin) with the hematopoietic and cutaneous subsyndromes of ARS who presented with hand pain/erythema/edema and underlying signs of infection 2 weeks after an unrecognized radiation exposure. Learners had to perform a history and physical, recognize/manage abnormal vitals, order/interpret labs, consult appropriate disciplines, and initiate supportive care. Results: There was a mean reported increase in ability to recognize signs and symptoms of ARS (p < .001) and appropriately manage a patient with this condition (p = .03) even after controlling for baseline confidence in ability to make and manage uncommon diagnoses, respectively. Learners rated this simulation as a valuable learning experience, effective in teaching them how to diagnose and treat ARS, and one they would recommend to other health care professionals. Discussion: This simulation aimed to teach the diagnosis and initial management of the hematopoietic and cutaneous subsyndromes of ARS. It should be used to increase awareness of the potential for ionizing radiation exposure under less obvious conditions and raise the index of suspicion for ARS in the undifferentiated patient.

Translatome analysis reveals microglia and astrocytes to be distinct regulators of inflammation in the hyperacute and acute phases after stroke.

Neuroinflammation is a hallmark of ischemic stroke, which is a leading cause of death and long-term disability. Understanding the exact cellular signaling pathways that initiate and propagate neuroinflammation after stroke will be critical for developing immunomodulatory stroke therapies. In particular, the precise mechanisms of inflammatory signaling in the clinically relevant hyperacute period, hours after stroke, have not been elucidated. We used the RiboTag technique to obtain microglia and astrocyte-derived mRNA transcripts in a hyperacute (4 h) and acute (3 days) period after stroke, as these two cell types are key modulators of acute neuroinflammation. Microglia initiated a rapid response to stroke at 4 h by adopting an inflammatory profile associated with the recruitment of immune cells. The hyperacute astrocyte profile was marked by stress response genes and transcription factors, such as Fos and Jun, involved in pro-inflammatory pathways such as TNF-α. By 3 days, microglia shift to a proliferative state and astrocytes strengthen their inflammatory response. The astrocyte pro-inflammatory response at 3 days is partially driven by the upregulation of the transcription factors C/EBPß, Spi1, and Rel, which comprise 25% of upregulated transcription factor-target interactions. Surprisingly, few sex differences across all groups were observed. Expression and log2 fold data for all sequenced genes are available on a user-friendly website for researchers to examine gene changes and generate hypotheses for stroke targets. Taken together, our data comprehensively describe the microglia and astrocyte-specific translatome response in the hyperacute and acute period after stroke and identify pathways critical for initiating neuroinflammation.

Translatome analysis reveals microglia and astrocytes to be distinct regulators of inflammation in the hyperacute and acute phases after stroke.

Neuroinflammation is a hallmark of ischemic stroke, which is a leading cause of death and long-term disability. Understanding the exact cellular signaling pathways that initiate and propagate neuroinflammation after stroke will be critical for developing immunomodulatory stroke therapies. In particular, the precise mechanisms of inflammatory signaling in the clinically relevant hyperacute period, hours after stroke, have not been elucidated. We used the RiboTag technique to obtain astrocyte and microglia-derived mRNA transcripts in a hyperacute (4 hours) and acute (3 days) period after stroke, as these two cell types are key modulators of acute neuroinflammation. Microglia initiated a rapid response to stroke at 4 hours by adopting an inflammatory profile associated with the recruitment of immune cells. The hyperacute astrocyte profile was marked by stress response genes and transcription factors, such as Fos and Jun , involved in pro-inflammatory pathways such as TNF-α. By 3 days, microglia shift to a proliferative state and astrocytes strengthen their inflammatory response. The astrocyte pro-inflammatory response at 3 days is partially driven by the upregulation of the transcription factors C/EBPß, Spi1 , and Rel , which comprise 25% of upregulated transcription factor-target interactions. Surprisingly, few sex differences across all groups were observed. Expression and log 2 fold data for all sequenced genes are available on a user-friendly website for researchers to examine gene changes and generate hypotheses for stroke targets. Taken together our data comprehensively describe the astrocyte and microglia-specific translatome response in the hyperacute and acute period after stroke and identify pathways critical for initiating neuroinflammation.

Blocking of microglia-astrocyte proinflammatory signaling is beneficial following stroke.

Microglia and astrocytes play an important role in the neuroinflammatory response and contribute to both the destruction of neighboring tissue as well as the resolution of inflammation following stroke. These reactive glial cells are highly heterogeneous at both the transcriptomic and functional level. Depending upon the stimulus, microglia and astrocytes mount a complex, and specific response composed of distinct microglial and astrocyte substates. These substates ultimately drive the landscape of the initiation and recovery from the adverse stimulus. In one state, inflammation- and damage-induced microglia release tumor necrosis factor (TNF), interleukin 1α (IL1α), and complement component 1q (C1q), together "TIC." This cocktail of cytokines drives astrocytes into a neurotoxic reactive astrocyte (nRA) substate. This nRA substate is associated with loss of many physiological astrocyte functions (e.g., synapse formation and maturation, phagocytosis, among others), as well as a gain-of-function release of neurotoxic long-chain fatty acids which kill neighboring cells. Here we report that transgenic removal of TIC led to reduction of gliosis, infarct expansion, and worsened functional deficits in the acute and delayed stages following stroke. Our results suggest that TIC cytokines, and likely nRAs play an important role that may maintain neuroinflammation and inhibit functional motor recovery after ischemic stroke. This is the first report that this paradigm is relevant in stroke and that therapies against nRAs may be a novel means to treat patients. Since nRAs are evolutionarily conserved from rodents to humans and present in multiple neurodegenerative diseases and injuries, further identification of mechanistic role of nRAs will lead to a better understanding of the neuroinflammatory response and the development of new therapies.

Longitudinal Consumption of Ergothioneine Reduces Oxidative Stress and Amyloid Plaques and Restores Glucose Metabolism in the 5XFAD Mouse Model of Alzheimer's Disease.

Background: Ergothioneine (ERGO) is a unique antioxidant and a rare amino acid available in fungi and various bacteria but not in higher plants or animals. Substantial research data indicate that ERGO is a physiological antioxidant cytoprotectant. Different from other antioxidants that need to breach the blood-brain barrier to enter the brain parenchyma, a specialized transporter called OCTN1 has been identified for transporting ERGO to the brain. Purpose: To assess whether consumption of ERGO can prevent the progress of Alzheimer's disease (AD) on young (4-month-old) 5XFAD mice. Methods and materials: Three cohorts of mice were tested in this study, including ERGO-treated 5XFAD, non-treated 5XFAD, and WT mice. After the therapy, the animals went through various behavioral experiments to assess cognition. Then, mice were scanned with PET imaging to evaluate the biomarkers associated with AD using [11C]PIB, [11C]ERGO, and [18F]FDG radioligands. At the end of imaging, the animals went through cardiac perfusion, and the brains were isolated for immunohistology. Results: Young (4-month-old) 5XFAD mice did not show a cognitive deficit, and thus, we observed modest improvement in the treated counterparts. In contrast, the response to therapy was clearly detected at the molecular level. Treating 5XFAD mice with ERGO resulted in reduced amyloid plaques, oxidative stress, and rescued glucose metabolism. Conclusions: Consumption of high amounts of ERGO benefits the brain. ERGO has the potential to prevent AD. This work also demonstrates the power of imaging technology to assess response during therapy.

Automated synthesis of (R)-[18 F]MH.MZ on the iPhase Flexlab reaction platform.

(R)-[18 F]MH.MZ ([18 F]MH.MZ) is a promising positron emission tomography (PET) radiotracer for in vivo study of the 5-HT2A receptor. To facilitate clinical trials, a fully automated radiosynthesis procedure for [18 F]MH.MZ was developed using commercially available materials on the iPhase Flexlab module. The overall synthesis time was 100 min with a radiochemical yield of 7 ± 0.9% (n = 3). The radiochemical purity was greater than 99% for [18 F]MH.MZ with a molar activity of 361 ± 57 GBq/µmol (n = 3). The protocol described herein reliably provides [18 F]MH.MZ that meets all relevant release criteria for a GMP radiopharmaceutical.

Improved synthesis of an ergothioneine PET radioligand for imaging oxidative stress in Alzheimer's disease.

L-ergothioneine (ERGO) is a potent antioxidant with cytoprotective effects. To study ERGO biodistribution and detect oxidative stress in vivo, we report an efficient and reproducible preparation of [11 C]-labeled ERGO PET radioligand based on protecting the histidine carboxylic group with a methyl ester. Overall, this new protection approach using methyl ester improved the chemical yield of a 4-step reaction from 14% to 24% compared to the previous report using t-butyl ester. The [11 C]CH3 methylation of the precursor provided the desired product with 55 ± 10% radiochemical purity and a molar activity of 450 ± 200 TBq·mmol-1 . The [11 C]ERGO radioligand was able to detect threshold levels of oxidative stress in a preclinical animal model of Alzheimer's disease.

First-in-Human PET Imaging and Estimated Radiation Dosimetry of l-[5-11C]-Glutamine in Patients with Metastatic Colorectal Cancer.

Altered metabolism is a hallmark of cancer. In addition to glucose, glutamine is an important nutrient for cellular growth and proliferation. Noninvasive imaging via PET may help facilitate precision treatment of cancer through patient selection and monitoring of treatment response. l-[5-11C]-glutamine (11C-glutamine) is a PET tracer designed to study glutamine uptake and metabolism. The aim of this first-in-human study was to evaluate the radiologic safety and biodistribution of 11C-glutamine for oncologic PET imaging. Methods: Nine patients with confirmed metastatic colorectal cancer underwent PET/CT imaging. Patients received 337.97 ± 44.08 MBq of 11C-glutamine. Dynamic PET acquisitions that were centered over the abdomen or thorax were initiated simultaneously with intravenous tracer administration. After the dynamic acquisition, a whole-body PET/CT scan was acquired. Volume-of-interest analyses were performed to obtain estimates of organ-based absorbed doses of radiation. Results:11C-glutamine was well tolerated in all patients, with no observed safety concerns. The organs with the highest radiation exposure included the bladder, pancreas, and liver. The estimated effective dose was 4.46E-03 ± 7.67E-04 mSv/MBq. Accumulation of 11C-glutamine was elevated and visualized in lung, brain, bone, and liver metastases, suggesting utility for cancer imaging. Conclusion: PET using 11C-glutamine appears safe for human use and allows noninvasive visualization of metastatic colon cancer lesions in multiple organs. Further studies are needed to elucidate its potential for other cancers and for monitoring response to treatment.

Disaster medicine and pandemic response: A novel curriculum to improve understanding of complex care delivery during the COVID-19 pandemic.

Background: Despite a 2009 recommendation from the AMA that disaster medicine and public health response training should be implemented in medical schools, anywhere from 31% to 47% of medical education programs lack a formalized disaster medicine curriculum. A need for disaster medicine response training for University of Alabama medical students in an appropriately socially distanced format was identified during the COVID-19 pandemic. Methods: Our emergency medicine faculty in collaboration with the Federal Emergency Management Agency Center for Disaster Preparedness (FEMA CDP) created and implemented a novel virtual disaster medicine and pandemic response course for third-year medical students at the University of Alabama at Birmingham (UAB). The course was administered via a teleconferencing platform (Zoom, Zoom Video Communications, Inc.) in spring 2020 to more than 130 medical students. Results: Using pre- and postcourse surveys, we assessed a change in student confidence levels for their ability to explain topics covered in the course and their understanding of a chosen disaster. The students reported an average increase of 2.183 on a 5-point scale, with a score of 5 representing "completely confident" and a score of 1 representing "not at all confident." This course established the feasibility of a virtual instructor-led training (VILT) format for disaster medicine education and provided a template for the delivery of over 300 courses to more than 4,000 first responders and medical professionals through the FEMA CDP. Conclusions: Through collaboration with the FEMA CDP, our UAB faculty were able to successfully deliver a novel virtual disaster-preparedness and response course. The course resulted in subjective improvement of students' content understanding while also establishing the feasibility and effectiveness of a VILT format that could be readily applied to future courses in undergraduate medical education and beyond.

A novel antioxidant ergothioneine PET radioligand for in vivo imaging applications.

Ergothioneine (ERGO) is a rare amino acid mostly found in fungi, including mushrooms, with recognized antioxidant activity to protect tissues from damage by reactive oxygen species (ROS) components. Prior to this publication, the biodistribution of ERGO has been performed solely in vitro using extracted tissues. The aim of this study was to develop a feasible chemistry for the synthesis of an ERGO PET radioligand, [11C]ERGO, to facilitate in vivo study. The radioligand probe was synthesized with identical structure to ERGO by employing an orthogonal protection/deprotection approach. [11C]methylation of the precursor was performed via [11C]CH3OTf to provide [11C]ERGO radioligand. The [11C]ERGO was isolated by RP-HPLC with a molar activity of 690 TBq/mmol. To demonstrate the biodistribution of the radioligand, we administered approximately 37 MBq/0.1 mL in 5XFAD mice, a mouse model of Alzheimer's disease via the tail vein. The distribution of ERGO in the brain was monitored using 90-min dynamic PET scans. The delivery and specific retention of [11C]ERGO in an LPS-mediated neuroinflammation mouse model was also demonstrated. For the pharmacokinetic study, the concentration of the compound in the serum started to decrease 10 min after injection while starting to distribute in other peripheral tissues. In particular, a significant amount of the compound was found in the eyes and small intestine. The radioligand was also distributed in several regions of the brain of 5XFAD mice, and the signal remained strong 30 min post-injection. This is the first time the biodistribution of this antioxidant and rare amino acid has been demonstrated in a preclinical mouse model in a highly sensitive and non-invasive manner.

A Fixed, Unreducible, Unstable Medial Swivel Dislocation of the Talonavicular Joint with Associated Navicular Fracture.

A 32-year-old white male was on a second-story balcony when he fell off and landed on the cement below. With initial X-rays being read as negative on the radiology report due to the subtle nature of the injury, the patient was promptly diagnosed with a medial swivel dislocation by the orthopaedic team, which ended up being fixed, unstable, and irreducible. The patient also had acute skin compromise and needed to be taken to the operating room prior to progression of skin breakdown. This dislocation pattern is a rare variant, especially when paired with the fixed nature of the dislocation and the soft tissue compromise. In the end, open treatment was necessary in order to reduce the talonavicular joint. Because of early recognition and prompt treatment, skin breakdown was avoided. Internal screw fixation of the fractured navicular bone was needed along with K-wire insertion to hold the normal anatomy of the talonavicular joint reduced. All hardware was ultimately removed after healing, and anatomy was restored with excellent patient function. This case report highlights the orthopaedic knowledge needed to not only recognize this rare fracture-dislocation pattern but to also treat it promptly when encountered.

EphA2 Is a Clinically Relevant Target for Breast Cancer Bone Metastatic Disease.

EphA2 receptor tyrosine kinase (RTK) is highly expressed in breast tumor cells across multiple molecular subtypes and correlates with poor patient prognosis. In this study, the potential role of EphA2 in this clinically relevant phenomenon is investigated as metastasis of breast cancer to bone is a major cause of morbidity and mortality in patients. It was found that the EphA2 function in breast cancer cells promotes osteoclast activation and the development of osteolytic bone disease. Blocking EphA2 function molecularly and pharmacologically in breast tumors reduced the number and size of bone lesions and the degree of osteolytic disease in intratibial and intracardiac mouse models, which correlated with a significant decrease in the number of osteoclasts at the tumor-bone interface. EphA2 loss of function in tumor cells impaired osteoclast progenitor differentiation in coculture, which is mediated, at least in part, by reduced expression of IL-6. EPHA2 transcript levels are enriched in human breast cancer bone metastatic lesions relative to visceral metastatic sites; EphA2 protein expression was detected in breast tumor cells in bone metastases in patient samples, supporting the clinical relevance of the study's findings. These data provide a strong rationale for the development and application of molecularly targeted therapies against EphA2 for the treatment of breast cancer bone metastatic disease. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.